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Sökning: WFRF:(Nawaz Muhammad)

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1.
  • Lozano, Rafael, et al. (författare)
  • Measuring progress from 1990 to 2017 and projecting attainment to 2030 of the health-related Sustainable Development Goals for 195 countries and territories: a systematic analysis for the Global Burden of Disease Study 2017
  • 2018
  • Ingår i: The Lancet. - : Elsevier. - 1474-547X .- 0140-6736. ; 392:10159, s. 2091-2138
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Efforts to establish the 2015 baseline and monitor early implementation of the UN Sustainable Development Goals (SDGs) highlight both great potential for and threats to improving health by 2030. To fully deliver on the SDG aim of “leaving no one behind”, it is increasingly important to examine the health-related SDGs beyond national-level estimates. As part of the Global Burden of Diseases, Injuries, and Risk Factors Study 2017 (GBD 2017), we measured progress on 41 of 52 health-related SDG indicators and estimated the health-related SDG index for 195 countries and territories for the period 1990–2017, projected indicators to 2030, and analysed global attainment. Methods: We measured progress on 41 health-related SDG indicators from 1990 to 2017, an increase of four indicators since GBD 2016 (new indicators were health worker density, sexual violence by non-intimate partners, population census status, and prevalence of physical and sexual violence [reported separately]). We also improved the measurement of several previously reported indicators. We constructed national-level estimates and, for a subset of health-related SDGs, examined indicator-level differences by sex and Socio-demographic Index (SDI) quintile. We also did subnational assessments of performance for selected countries. To construct the health-related SDG index, we transformed the value for each indicator on a scale of 0–100, with 0 as the 2·5th percentile and 100 as the 97·5th percentile of 1000 draws calculated from 1990 to 2030, and took the geometric mean of the scaled indicators by target. To generate projections through 2030, we used a forecasting framework that drew estimates from the broader GBD study and used weighted averages of indicator-specific and country-specific annualised rates of change from 1990 to 2017 to inform future estimates. We assessed attainment of indicators with defined targets in two ways: first, using mean values projected for 2030, and then using the probability of attainment in 2030 calculated from 1000 draws. We also did a global attainment analysis of the feasibility of attaining SDG targets on the basis of past trends. Using 2015 global averages of indicators with defined SDG targets, we calculated the global annualised rates of change required from 2015 to 2030 to meet these targets, and then identified in what percentiles the required global annualised rates of change fell in the distribution of country-level rates of change from 1990 to 2015. We took the mean of these global percentile values across indicators and applied the past rate of change at this mean global percentile to all health-related SDG indicators, irrespective of target definition, to estimate the equivalent 2030 global average value and percentage change from 2015 to 2030 for each indicator. Findings: The global median health-related SDG index in 2017 was 59·4 (IQR 35·4–67·3), ranging from a low of 11·6 (95% uncertainty interval 9·6–14·0) to a high of 84·9 (83·1–86·7). SDG index values in countries assessed at the subnational level varied substantially, particularly in China and India, although scores in Japan and the UK were more homogeneous. Indicators also varied by SDI quintile and sex, with males having worse outcomes than females for non-communicable disease (NCD) mortality, alcohol use, and smoking, among others. Most countries were projected to have a higher health-related SDG index in 2030 than in 2017, while country-level probabilities of attainment by 2030 varied widely by indicator. Under-5 mortality, neonatal mortality, maternal mortality ratio, and malaria indicators had the most countries with at least 95% probability of target attainment. Other indicators, including NCD mortality and suicide mortality, had no countries projected to meet corresponding SDG targets on the basis of projected mean values for 2030 but showed some probability of attainment by 2030. For some indicators, including child malnutrition, several infectious diseases, and most violence measures, the annualised rates of change required to meet SDG targets far exceeded the pace of progress achieved by any country in the recent past. We found that applying the mean global annualised rate of change to indicators without defined targets would equate to about 19% and 22% reductions in global smoking and alcohol consumption, respectively; a 47% decline in adolescent birth rates; and a more than 85% increase in health worker density per 1000 population by 2030. Interpretation: The GBD study offers a unique, robust platform for monitoring the health-related SDGs across demographic and geographic dimensions. Our findings underscore the importance of increased collection and analysis of disaggregated data and highlight where more deliberate design or targeting of interventions could accelerate progress in attaining the SDGs. Current projections show that many health-related SDG indicators, NCDs, NCD-related risks, and violence-related indicators will require a concerted shift away from what might have driven past gains—curative interventions in the case of NCDs—towards multisectoral, prevention-oriented policy action and investments to achieve SDG aims. Notably, several targets, if they are to be met by 2030, demand a pace of progress that no country has achieved in the recent past. The future is fundamentally uncertain, and no model can fully predict what breakthroughs or events might alter the course of the SDGs. What is clear is that our actions—or inaction—today will ultimately dictate how close the world, collectively, can get to leaving no one behind by 2030.
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2.
  • Mobeen Zafar, Muhammad, et al. (författare)
  • 9p21 Locus Polymorphism Is A Strong Predictor of Metabolic Syndrome and Cardiometabolic Risk Phenotypes Regardless of Coronary Heart Disease.
  • 2022
  • Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 13:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The world population is genetically predisposed to metabolic syndrome (MetS) and its components, also known as cardiometabolic risk phenotypes, which can cause severe health complications including coronary heart disease (CHD). Genetic variants in the 9p21 locus have been associated with CHD in a number of populations including Pakistan. However, the role of the 9p21 locus in MetS and cardiometabolic risk phenotypes (such as obesity, hypertension, hyperglycemia, and dyslipidemia) in populations with CHD or no established CHD has not been explored. Therefore, the present study was designed to explore the association of the minor/risk allele (C) of 9p21 locus SNP rs1333049 with MetS or its risk phenotypes regardless of an established CHD, in Pakistani subjects. Genotyping of rs1333049 (G/C) was performed on subjects under a case-control study design; healthy controls and cases, MetS with CHD (MetS-CHD+) and MetS with no CHD (MetS-CHD-), respectively. Genotype and allele frequencies were calculated in all study groups. Anthropometric and clinical variables (Means ± SD) were compared among study groups (i.e., controls, MetS + CHD and MetS-CHD) and minor/risk C allele carriers (GC + CC) vs. non-carriers (Normal GG genotype). Associations of the risk allele of rs1333049 SNP with disease and individual metabolic risk components were explored using adjusted multivariate logistic regression models (OR at 95% CI) with a threshold p-value of ≤0.05. Our results have shown that the minor allele frequency (MAF) was significantly high in the MAF cases (combined = 0.63, MetS-CHD+ = 0.57 and MetS-CHD- = 0.57) compared with controls (MAF = 0.39). The rs1333049 SNP significantly increased the risk of MetS, irrespective of CHD (MetS-CHD+ OR = 2.36, p < 0.05 and MetS-CHD- OR = 4.04, p < 0.05), and cardiometabolic risk phenotypes; general obesity, central obesity, hypertension, and dyslipidemia (OR = 1.56-3.25, p < 0.05) except hyperglycemia, which lacked any significant association (OR = 0.19, p = 0.29) in the present study group. The 9p21 genetic locus/rs1333049 SNP is strongly associated with, and can be a genetic predictor of, MetS and cardiometabolic risks, irrespective of cardiovascular diseases in the Pakistani population.
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3.
  • Murray, Christopher J. L., et al. (författare)
  • Population and fertility by age and sex for 195 countries and territories, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017
  • 2018
  • Ingår i: The Lancet. - 1474-547X .- 0140-6736. ; 392:10159, s. 1995-2051
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Population estimates underpin demographic and epidemiological research and are used to track progress on numerous international indicators of health and development. To date, internationally available estimates of population and fertility, although useful, have not been produced with transparent and replicable methods and do not use standardised estimates of mortality. We present single-calendar year and single-year of age estimates of fertility and population by sex with standardised and replicable methods. Methods: We estimated population in 195 locations by single year of age and single calendar year from 1950 to 2017 with standardised and replicable methods. We based the estimates on the demographic balancing equation, with inputs of fertility, mortality, population, and migration data. Fertility data came from 7817 location-years of vital registration data, 429 surveys reporting complete birth histories, and 977 surveys and censuses reporting summary birth histories. We estimated age-specific fertility rates (ASFRs; the annual number of livebirths to women of a specified age group per 1000 women in that age group) by use of spatiotemporal Gaussian process regression and used the ASFRs to estimate total fertility rates (TFRs; the average number of children a woman would bear if she survived through the end of the reproductive age span [age 10–54 years] and experienced at each age a particular set of ASFRs observed in the year of interest). Because of sparse data, fertility at ages 10–14 years and 50–54 years was estimated from data on fertility in women aged 15–19 years and 45–49 years, through use of linear regression. Age-specific mortality data came from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 estimates. Data on population came from 1257 censuses and 761 population registry location-years and were adjusted for underenumeration and age misreporting with standard demographic methods. Migration was estimated with the GBD Bayesian demographic balancing model, after incorporating information about refugee migration into the model prior. Final population estimates used the cohort-component method of population projection, with inputs of fertility, mortality, and migration data. Population uncertainty was estimated by use of out-of-sample predictive validity testing. With these data, we estimated the trends in population by age and sex and in fertility by age between 1950 and 2017 in 195 countries and territories. Findings: From 1950 to 2017, TFRs decreased by 49·4% (95% uncertainty interval [UI] 46·4–52·0). The TFR decreased from 4·7 livebirths (4·5–4·9) to 2·4 livebirths (2·2–2·5), and the ASFR of mothers aged 10–19 years decreased from 37 livebirths (34–40) to 22 livebirths (19–24) per 1000 women. Despite reductions in the TFR, the global population has been increasing by an average of 83·8 million people per year since 1985. The global population increased by 197·2% (193·3–200·8) since 1950, from 2·6 billion (2·5–2·6) to 7·6 billion (7·4–7·9) people in 2017; much of this increase was in the proportion of the global population in south Asia and sub-Saharan Africa. The global annual rate of population growth increased between 1950 and 1964, when it peaked at 2·0%; this rate then remained nearly constant until 1970 and then decreased to 1·1% in 2017. Population growth rates in the southeast Asia, east Asia, and Oceania GBD super-region decreased from 2·5% in 1963 to 0·7% in 2017, whereas in sub-Saharan Africa, population growth rates were almost at the highest reported levels ever in 2017, when they were at 2·7%. The global average age increased from 26·6 years in 1950 to 32·1 years in 2017, and the proportion of the population that is of working age (age 15–64 years) increased from 59·9% to 65·3%. At the national level, the TFR decreased in all countries and territories between 1950 and 2017; in 2017, TFRs ranged from a low of 1·0 livebirths (95% UI 0·9–1·2) in Cyprus to a high of 7·1 livebirths (6·8–7·4) in Niger. The TFR under age 25 years (TFU25; number of livebirths expected by age 25 years for a hypothetical woman who survived the age group and was exposed to current ASFRs) in 2017 ranged from 0·08 livebirths (0·07–0·09) in South Korea to 2·4 livebirths (2·2–2·6) in Niger, and the TFR over age 30 years (TFO30; number of livebirths expected for a hypothetical woman ageing from 30 to 54 years who survived the age group and was exposed to current ASFRs) ranged from a low of 0·3 livebirths (0·3–0·4) in Puerto Rico to a high of 3·1 livebirths (3·0–3·2) in Niger. TFO30 was higher than TFU25 in 145 countries and territories in 2017. 33 countries had a negative population growth rate from 2010 to 2017, most of which were located in central, eastern, and western Europe, whereas population growth rates of more than 2·0% were seen in 33 of 46 countries in sub-Saharan Africa. In 2017, less than 65% of the national population was of working age in 12 of 34 high-income countries, and less than 50% of the national population was of working age in Mali, Chad, and Niger. Interpretation: Population trends create demographic dividends and headwinds (ie, economic benefits and detriments) that affect national economies and determine national planning needs. Although TFRs are decreasing, the global population continues to grow as mortality declines, with diverse patterns at the national level and across age groups. To our knowledge, this is the first study to provide transparent and replicable estimates of population and fertility, which can be used to inform decision making and to monitor progress. Funding: Bill & Melinda Gates Foundation.
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4.
  • Farooq, Muhammad, et al. (författare)
  • Thermodynamic Performance Analysis of Hydrofluoroolefins (HFO) Refrigerants in Commercial Air-Conditioning Systems for Sustainable Environment
  • 2020
  • Ingår i: Processes. - : MDPI. - 2227-9717. ; 8:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Global warming is one of most severe environmental concerns that our planet is facing today. One of its causes is the previous generation of refrigerants that, upon release, remain in the atmosphere for longer periods and contribute towards global warming. This issue could potentially be solved by replacing the previous generation's high global warming potential (GWP) refrigerants with environmentally friendly refrigerants. This scenario requires an analysis of new refrigerants for a comparison of the thermodynamic properties of the previously used refrigerants. In the present research, a numerical study was conducted to analyze the thermodynamic performance of specifically low GWP hydrofluoroolefens (HFO) refrigerants for an actual vapor compression refrigeration cycle (VCRC) with a constant degree of 3 K superheat. The output parameters included the refrigeration effect, compressor work input, the coefficient of performance (COP), and the volumetric refrigeration capacity (VRC), all of which were calculated by varying the condenser pressure from 6 to 12 bars and vapor pressure from 0.7 to 1.9 bars. Results showed that R1234ze(Z) clearly possessed the desired thermodynamic performance. The drop in refrigeration effect for R1234ze(Z) was merely 14.6% less than that of R134a at a 12 bar condenser pressure; this was minimum drop among candidate refrigerants. The drop in the COP was the minimum for R1234ze(Z)-5.1% less than that of R134a at a 9 bar condenser pressure and 4.7% less than that of R134a at a 1.9 bar evaporator pressure, whereas the COP values of the other refrigerants dropped more drastically at higher condenser pressures. R1234ze(Z) possessed favorable thermodynamic characteristics, with a GWP of 7, and it can serve as an alternative refrigerant for refrigeration systems for a sustainable environment.
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5.
  • Saqlain, Muhammad, et al. (författare)
  • Risk variants of obesity associated genes demonstrate BMI raising effect in a large cohort.
  • 2022
  • Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 17:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Obesity is highly polygenic disease where several genetic variants have been reportedly associated with obesity in different ethnicities of the world. In the current study, we identified the obesity risk or protective association and BMI raising effect of the minor allele of adiponectin, C1Q and collagen domain containing (ADIPOQ), cholesteryl ester transfer protein (CEPT), FTO alpha-ketoglutarate dependent dioxygenase (FTO), leptin (LEP), and leptin receptor (LEPR) genes in a large cohort stratified into four BMI-based body weight categories i.e., normal weight, lean, over-weight, and obese. Based on selected candidate genetic markers, the genotyping of all study subjects was performed by PCR assays, and genotypes and allele frequencies were calculated. The minor allele frequencies (MAFs) of all genetic markers were computed for total and BMI-based body weight categories and compared with MAFs of global and South Asian (SAS) populations. Genetic associations of variants with obesity risk were calculated and BMI raising effect per copy of the minor allele were estimated. The genetic variants with higher MAFs in obese BMI group were; rs2241766 (G = 0.43), rs17817449 (G = 0.54), rs9939609 (A = 0.51), rs1421085 (C = 0.53), rs1558902 (A = 0.63), and rs1137101 (G = 0.64) respectively. All these variants were significantly associated with obesity (OR = 1.03-4.42) and showed a high BMI raising effect (β = 0.239-0.31 Kg/m2) per copy of the risk allele. In contrast, the MAFs of three variants were higher in lean-normal BMI groups; rs3764261 A = 0.38, rs9941349 T = 0.43, and rs7799039 G = 0.40-0.43). These variants showed obesity protective associations (OR = 0.68-0.76), and a BMI lowering effect per copy of the protective allele (β = -0.103-0.155 Kg/m2). The rs3764261 variant also showed significant and positive association with lean body mass (OR = 2.38, CI = 1.30-4.34). Overall, we report six genetic variants of ADIPOQ, FTO and LEPR genes as obesity-risk markers and a CETP gene variant as lean mass/obesity protective marker in studied Pakistani cohort.
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6.
  • Ali, Muhammad Amjad, et al. (författare)
  • Transcription factors WRKY11 and WRKY17 are involved in abiotic stress responses in Arabidopsis
  • 2018
  • Ingår i: Journal of plant physiology (Print). - : Elsevier. - 0176-1617 .- 1618-1328. ; 226, s. 12-21
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant WRKY transcription factors play a vital role in abiotic stress tolerance and regulation of plant defense responses. This study examined AtWRKY11 and AtWRKY17 expression under ABA, salt, and osmotic stress at different developmental stages in Arabidopsis. We used reverse transcriptase PCR, quantitative real-time PCR, and promoter:GUS lines to analyze expression. Both genes were upregulated in response to abiotic stress. Next, we applied the same stressors to seedlings of T-DNA insertion wrky11 and 17 knock-out mutants (single and double). Under stress, the mutants exhibited slower germination and compromised root growth compared with the wild type. In most cases, double-mutant seedlings were more affected than single mutants. These results suggest that wrky11 and wrky17 are not strictly limited to plant defense responses but are also involved in conferring stress tolerance.
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7.
  • Arslan, Muhammad, et al. (författare)
  • Impact of Varying Load Conditions and Cooling Energy Comparison of a Double-Inlet Pulse Tube Refrigerator
  • 2020
  • Ingår i: Processes. - : MDPI. - 2227-9717. ; 8:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental data using different boundary conditions. To predict its performance, a detailed two-dimensional DIPTR model was developed. A double-drop pulse pipe cooler was used for solving continuity, dynamic and power calculations. External conditions for applicable boundaries include sinusoidal pressure from an end of the tube from a user-defined function and constant temperature or limitations of thermal flux within the outer walls of exchanger walls under colder conditions. The results of the system's cooling behavior were reported, along with the connection between the mass flow rates, heat distribution along pulse tube and cold-end pressure, the cooler load's wall temp profile and cooler loads with varied boundary conditions i.e. opening of 20% double-inlet and 40-60% orifice valves, respectively. Different loading conditions of 1 and 5W were applied on the CHX. At 150 K temperature of the cold-end heat exchanger, a maximum load of 3.7 W was achieved. The results also reveal a strong correlation between computational fluid dynamics modeling results and experimental results of the DIPTR.
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8.
  • Habiba, Umme, et al. (författare)
  • Differential Treatment Responses in Pakistani Schizophrenia Samples: Correlation with Sociodemographic Parameters, Drug Addiction, Attitude to the Treatment and Antipsychotic Agents
  • 2023
  • Ingår i: Brain Sciences. - : MDPI AG. - 2076-3425. ; 13:407, s. 1-25
  • Tidskriftsartikel (refereegranskat)abstract
    • Schizophrenia patients demonstrate variations in response to different therapies that are currently being used for the treatment of disorders, such as augmentation therapy (ECT or mood stabilizer) and combination therapy (with antipsychotics). These therapies are also used to treat schizophrenia patients in Pakistan; however, patients show poor overall response. Therefore, this study was conducted to investigate the association between the patients’ response to treatment and the use of antipsychotic agents, with variability in overall response, within different groups of patients. Methods: We conducted a retrospective study that included schizophrenia subjects (N = 200) belonging to different age groups, ethnicities, and regions from different outpatient and inpatient departments in psychiatric institutes located in different cities of Pakistan. These patients were assessed for their response to treatment therapies and categorized into four groups (non-responders (N-R), slow response (S-R), patients with relapse, and completely recovered patients (C-R)) according to their responses. Results: The final analysis included 200 subjects, of which 73.5% were males. Mean age was 34 ± 10 years. Percentage of N-R was 5%, S-R was 42%, patients with relapse were 24%, and C-R was 1.5%. The generalized linear regression model shows a significant association between medication response and age (p = 0.0231), age of onset (p = 0.0086), gender (p = 0.005), and marital status (p = 0.00169). Variability within the medication responses was a result of the treatment regime followed. Antipsychotic agents were significantly associated with the treatment response (p = 0.00258, F = 4.981) of the patients. Significant variation was also observed in the treatment response (p = 0.00128) of the patients that were given augmentation therapy as well as combination therapy. Conclusion: The data suggests proper monitoring of patients’ behavior in response to treatment therapies to implement tailored interventions. Despite several genetic studies supporting the heritability of schizophrenia, an insignificant association between characteristic features and family history might have been due to the limited sample size, suggesting collaborative work with massive sample sizes.
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9.
  • Nawaz, Sadia, et al. (författare)
  • WNT10A missense mutation associated with a complete odonto-onycho-dermal dysplasia syndrome
  • 2009
  • Ingår i: European Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 17:12, s. 1600-1605
  • Tidskriftsartikel (refereegranskat)abstract
    • Wnt signalling is one of a few pathways that are crucial for controlling genetic programs during embryonic development as well as in adult tissues. WNT10A is expressed in the skin and epidermis and it has shown to be critical for the development of ectodermal appendages. A nonsense mutation in WNT10A was recently identified in odonto-onycho-dermal dysplasia (OODD; MIM 257980), a rare syndrome characterised by severe hypodontia, nail dystrophy, smooth tongue, dry skin, keratoderma and hyperhydrosis of palms and soles. We identified a large consanguineous Pakistani pedigree comprising six individuals affected by a complete OODD syndrome. Autozygosity mapping using SNP array analysis showed that the affected individuals are homozygous for the WNT10A gene region. Subsequent mutation screening showed a homozygous c.392C>T transition in exon 3 of WNT10A, which predicts a p.A131V substitution in a conserved alpha-helix domain. We report here on the first inherited missense mutation in WNT10A with associated ectodermal features.
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10.
  • Wang, Haidong, et al. (författare)
  • Estimates of global, regional, and national incidence, prevalence, and mortality of HIV, 1980-2015 : the Global Burden of Disease Study 2015.
  • 2016
  • Ingår i: The lancet. HIV. - : Elsevier. - 2352-3018. ; 3:8, s. e361-e387
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Timely assessment of the burden of HIV/AIDS is essential for policy setting and programme evaluation. In this report from the Global Burden of Disease Study 2015 (GBD 2015), we provide national estimates of levels and trends of HIV/AIDS incidence, prevalence, coverage of antiretroviral therapy (ART), and mortality for 195 countries and territories from 1980 to 2015.METHODS: For countries without high-quality vital registration data, we estimated prevalence and incidence with data from antenatal care clinics and population-based seroprevalence surveys, and with assumptions by age and sex on initial CD4 distribution at infection, CD4 progression rates (probability of progression from higher to lower CD4 cell-count category), on and off antiretroviral therapy (ART) mortality, and mortality from all other causes. Our estimation strategy links the GBD 2015 assessment of all-cause mortality and estimation of incidence and prevalence so that for each draw from the uncertainty distribution all assumptions used in each step are internally consistent. We estimated incidence, prevalence, and death with GBD versions of the Estimation and Projection Package (EPP) and Spectrum software originally developed by the Joint United Nations Programme on HIV/AIDS (UNAIDS). We used an open-source version of EPP and recoded Spectrum for speed, and used updated assumptions from systematic reviews of the literature and GBD demographic data. For countries with high-quality vital registration data, we developed the cohort incidence bias adjustment model to estimate HIV incidence and prevalence largely from the number of deaths caused by HIV recorded in cause-of-death statistics. We corrected these statistics for garbage coding and HIV misclassification.FINDINGS: Global HIV incidence reached its peak in 1997, at 3·3 million new infections (95% uncertainty interval [UI] 3·1-3·4 million). Annual incidence has stayed relatively constant at about 2·6 million per year (range 2·5-2·8 million) since 2005, after a period of fast decline between 1997 and 2005. The number of people living with HIV/AIDS has been steadily increasing and reached 38·8 million (95% UI 37·6-40·4 million) in 2015. At the same time, HIV/AIDS mortality has been declining at a steady pace, from a peak of 1·8 million deaths (95% UI 1·7-1·9 million) in 2005, to 1·2 million deaths (1·1-1·3 million) in 2015. We recorded substantial heterogeneity in the levels and trends of HIV/AIDS across countries. Although many countries have experienced decreases in HIV/AIDS mortality and in annual new infections, other countries have had slowdowns or increases in rates of change in annual new infections.INTERPRETATION: Scale-up of ART and prevention of mother-to-child transmission has been one of the great successes of global health in the past two decades. However, in the past decade, progress in reducing new infections has been slow, development assistance for health devoted to HIV has stagnated, and resources for health in low-income countries have grown slowly. Achievement of the new ambitious goals for HIV enshrined in Sustainable Development Goal 3 and the 90-90-90 UNAIDS targets will be challenging, and will need continued efforts from governments and international agencies in the next 15 years to end AIDS by 2030.
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11.
  • Ahmed, Saad, et al. (författare)
  • Demystifying Energy Consumption Dynamics in Transiently Powered Computers
  • 2020
  • Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery. - 1539-9087 .- 1558-3465. ; 19:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Transiently powered computers (TPCs) form the foundation of the battery-less Internet of Things, using energy harvesting and small capacitors to power their operation. This kind of power supply is characterized by extreme variations in supply voltage, as capacitors charge when harvesting energy and discharge when computing. We experimentally find that these variations cause marked fluctuations in clock speed and power consumption. Such a deceptively minor observation is overlooked in existing literature. Systems are thus designed and parameterized in overly conservative ways, missing on a number of optimizations.We rather demonstrate that it is possible to accurately model and concretely capitalize on these fluctuations. We derive an energy model as a function of supply voltage and prove its use in two settings. First, we develop EPIC, a compile-time energy analysis tool. We use it to substitute for the constant power assumption in existing analysis techniques, giving programmers accurate information on worst-case energy consumption of programs. When using EPIC with existing TPC system support, run-time energy efficiency drastically improves, eventually leading up to a 350% speedup in the time to complete a fixed workload. Further, when using EPIC with existing debugging tools, it avoids unnecessary program changes that hurt energy efficiency. Next, we extend the MSPsim emulator and explore its use in parameterizing a different TPC system support. The improvements in energy efficiency yield up to more than 1000% time speedup to complete a fixed workload.
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12.
  • Hallén, Anders, et al. (författare)
  • Low-Temperature Annealing of Radiation-Induced Degradation in 4H-SiC Bipolar Junction Transistors
  • 2010
  • Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 31:7, s. 707-709
  • Tidskriftsartikel (refereegranskat)abstract
    • Radiation hardness is tested for 4H-SiC n-p-n bipolar junction transistors designed for 1200-V breakdown voltage by implanting MeV protons and carbon ions at different doses and energies. The current gain is found to be a very sensitive parameter, and a fluence as low as 1 x 107 cm(-2) of 10 MeV C-12 can be clearly detected in the forward-output characteristics, I-C(V-CE). At this low dose, no influence of ion radiation is seen in the open-collector characteristics, I-B(V-EB), or the reverse bias leakage and breakdown properties. Moreover, by annealing the implanted devices at 420 degrees C for 30 min, a complete recovery of the electrical characteristics is accomplished.
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13.
  • Khan, Shah Nawaz, et al. (författare)
  • Numerical investigation of thermomechanical behavior of Yttrium barium zirconate-coated aluminum alloy piston in an internal combustion engine
  • 2024
  • Ingår i: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 236:part B
  • Tidskriftsartikel (refereegranskat)abstract
    • Increasing engine power to volume density is under investigation and being analysed extensively. Turbocharger, which is used to boost volumetric efficiency, also raises cylinder temperature and pressure, thus resulting in thermal distortions and reducing clearances in tribo-contacts, thereby compromising engine life. Thermal barrier coatings (TBCs) have shown potential to provide remedies to reduce heat losses, hazardous emissions, and heat flow toward the piston skirt in an internal combustion engine. In this study, a detailed thermo-mechanical analysis was performed for a diesel engine piston with a novel yttrium barium zirconate (YBZ) coating and then compared with other TBCs with varying thicknesses. The results revealed a notable decrease in piston substrate surface temperature when coated with various TBCs, with YBZ coating demonstrating superior performance over others. The 0.2 mm coating of YBZ-coated piston exhibited significant reductions of 15% and 10.3% in temperature and thermal stress respectively, thus enhancing piston durability. The better performance of the novel YBZ coating could be attributed to its stable thermal and elastic properties and lower thermal conductivity than other TBC materials. YBZ coating provides a promising solution to improve engine efficiency while extending engine life, making it an attractive option for the automotive industry.
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14.
  • Khan, Tahir Naeem, et al. (författare)
  • Novel missense mutation in the RSPO4 gene in congenital hyponychia and evidence for a polymorphic initiation codon (p.M1l)
  • 2012
  • Ingår i: BMC Medical Genetics. - : Springer Science and Business Media LLC. - 1471-2350. ; 13, s. 120-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Anonychia/hyponychia congenita is a rare autosomal recessive developmental disorder characterized by the absence (anonychia) or hypoplasia (hyponuchia) of finger- and/or toenails frequently caused by mutations in the R-spondin 4 (RSPO4) gene. Methods: Three hypo/anonychia consanguineous Pakistani families were ascertained and genotyped using microsatellite markers spanning the RSPO4 locus on chromosome 20p13. Mutation screening of the RSPO4 gene was carried out by direct sequencing of the entire coding region and all intron-exon boundaries. Results: Mutations in the RSPO4 gene were identified in all families including a novel missense mutation c.178C>T (p.R60W) and two recurrent variants c.353G>A (p.C118Y) and c.3G>A (p.M1l). The c.3G>A variant was identified in unaffected family members and a control sample in a homozygous state. Conclusions: This study raises to 17 the number of known RSPO4 mutations and further expands the molecular repertoire causing hypo/anonychia. The c.353G>A emerges as a recurrent change with a possible founder effect in the Pakistani population. Our findings suggest that c.3G>A is not sufficient to cause the disorder and could be considered a polymorphism.
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15.
  • Majeed, Khaliq, et al. (författare)
  • Shuffled Complex Evolution-Based Performance Enhancement and Analysis of Cascade Liquefaction Process for Large-Scale LNG Production
  • 2020
  • Ingår i: Energies. - : MDPI. - 1996-1073. ; 13:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Among all large-scale natural gas (NG) liquefaction processes, the mixed fluid cascade (MFC) process is recognized as a best-alternative option for the LNG production, mainly due its competitive performance. However, from a thermodynamic point of view, the MFC process is still far from its potential maximum energy efficiency due to non-optimal execution of design variables. Therefore, the energy efficiency enhancement of the MFC process remains an ongoing issue. The design optimization after fixing the main configuration of the process is one of the most economic, but challenging exercises during the design stages. In this study, shuffled complex evolution (SCE) is studied to find the optimal design of the MFC process corresponding to minimal energy consumption in refrigeration cycles. The MFC process is simulated using Aspen Hysys((R)) v10 and then coupled with the SCE approach, which is coded in MATLAB((R)) 2019a. The refrigerant composition and operating pressures for each cycle of the MFC process were optimized considering the approach temperature inside the LNG heat exchanger as a constraint. The resulting optimal MFC process saved 19.76% overall compression power and reduced the exergy destruction up to 28.76%. The thermodynamic efficiency (figure of merit) of the SCE-optimized process was 25% higher than that of the published base case. Furthermore, the optimization results also imply that there is a trade-off between the thermodynamic performance improvement and the computational cost (no. of iterations). In conclusion, SCE exhibited potential to improve the performance of highly nonlinear and complex processes such as LNG processes.
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16.
  • Nawaz, Muhammad Ul Saqlain, et al. (författare)
  • Efficient resource prediction framework for software-defined heterogeneous radio environmental infrastructures
  • 2023
  • Ingår i: Advanced Engineering Informatics. - : Elsevier Ltd.. - 1474-0346. ; 56
  • Tidskriftsartikel (refereegranskat)abstract
    • Artificial Intelligence (AI) is defining the future of next-generation infrastructures as proactive and data-driven systems. AI-empowered radio systems are replacing the existing command and control radio networks due to their intelligence and capabilities to adapt to the radio environmental infrastructures that include intelligent networks, smart cities and AV/VR enabled factory premises or localities. An efficient resource prediction framework (ERPF) is proposed to provide proactive knowledge about the availability of radio resources in such software-defined heterogeneous radio environmental infrastructures (SD-HREIs). That prior information enables the coexistence of radio users in SD-HREIs. In a proposed framework, the radio activity is measured in both the unlicensed bands that include 2.4 and 5 GHz, respectively. The clustering algorithms k- means and DBSCAN are implemented to segregate the already measured radioactivity as signal (radio occupancy) and noise (radio opportunity). Machine learning techniques CNN and LRN are then trained and tested using the segregated data to predict the radio occupancy and radio opportunity in SD-HREIs. Finally, the performance of CNN and LRN is validated using the cross-validation metrics.
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17.
  • Nawaz, Sadia, et al. (författare)
  • Report of a recurrent mutation in ARS (component B) gene with severe Mal de Meleda in a large consanguineous Pakistani family
  • 2011
  • Ingår i: Pakistan journal of medical sciences print. - 1682-024X .- 1681-715X. ; 27:3, s. 686-689
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To characterize the disease causing mutation in a large consanguineous Pakistani family with severe Mat de Meleda (MDM) or keratosis palmoplantaris transgrediens, a rare autosomal recessive skin disorder. Methodology: Single nucleotide polymorphism (SNPs) genotyping was performed using the Gene Chip Mapping 250K array (Affymetrix). Homozygosity mapping and sorting of genomic regions were performed with dedicated software called AutoSNPa. Selected regions were further investigated by genotyping with microsatellite markers derived from known and novel pOlymorphic repeats. Two-point LOD score calculation was performed by using the MLINK of Fast link computer package. All three coding exons of ARS (component B) gene were amplified by PCR and sequenced. Conclusion: Sequencing of all the coding exons of ARS (component B) gene in the affected individuals revealed a recurrent missense mutation in exon 3 at base pair 256 from Guanine to Alanine (256G>A) and as a result the amino acid Glycine is replaced by Arginine at position 86 (G86R). This finding will facilitate control of affected MDM births in the Pakistani families.
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18.
  • Zhang, Tianle, et al. (författare)
  • A Joint Deep Learning and Internet of Medical Things Driven Framework for Elderly Patients
  • 2020
  • Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 8:2020, s. 75822-75832
  • Tidskriftsartikel (refereegranskat)abstract
    • Deep learning (DL) driven cardiac image processing methods manage and monitor the massive medical data collected by the internet of things (IoT) based on wearable devices. A Joint DL and IoT platform are known as Deep-IoMT that extracts the accurate cardiac image data from noisy conventional devices and tools. Besides, smart and dynamic technological trends have caught the attention of every corner such as, healthcare, which is possible through portable and lightweight sensor-enabled devices. Tiny size and resource-constrained nature restrict them to perform several tasks at a time. Thus, energy drain, limited battery lifetime, and high packet loss ratio (PLR) are the keys challenges to be tackled carefully for ubiquitous medical care. Sustainability (i.e., longer battery lifetime), energy efficiency, and reliability are the vital ingredients for wearable devices to empower a cost-effective and pervasive healthcare environment. Thus, the key contribution of this paper is the sixth fold. First, a novel self-adaptive power control-based enhanced efficient-aware approach (EEA) is proposed to reduce energy consumption and enhance the battery lifetime and reliability. The proposed EEA and conventional constant TPC are evaluated by adopting real-time data traces of static (i.e., sitting) and dynamic (i.e., cycling) activities and cardiac images. Second, a novel joint DL-IoMT framework is proposed for the cardiac image processing of remote elderly patients. Third, DL driven layered architecture for IoMT is proposed. Forth, the battery model for IoMT is proposed by adopting the features of a wireless channel and body postures. Fifth, network performance is optimized by introducing sustainability, energy drain, and PLR and average threshold RSSI indicators. Sixth, a Use-case for cardiac image-enabled elderly patient's monitoring is proposed. Finally, it is revealed through experimental results in MATLAB that the proposed EEA scheme performs better than the constant TPC by enhancing energy efficiency, sustainability, and reliability during data transmission for elderly healthcare.
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19.
  • Akbari, Ali, et al. (författare)
  • Free and hydrogel encapsulated exosome-based therapies in regenerative medicine.
  • 2020
  • Ingår i: Life sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 249
  • Tidskriftsartikel (refereegranskat)abstract
    • Over the last few decades, mesenchymal stem cells-derived exosomes (MSCs-Ex) have attracted a lot of attention as a therapeutic tool in regenerative medicine. Exosomes are extracellular vehicles (EVs) that play important roles in cell-cell communication through various processes such as stress response, senescence, angiogenesis, and cell differentiation. Success in the field of regenerative medicine sparked exploration of the potential use of exosomes as key therapeutic effectors of MSCs to promote tissue regeneration. Various approaches including direct injection, intravenous injection, intraperitoneal injection, oral administration, and hydrogel-based encapsulation have been exploited to deliver exosomes to target tissues in different disease models. Despite significant advances in exosome therapy, it is unclear which approach is more effective for administering exosomes. Herein, we critically review the emerging progress in the applications of exosomes in the form of free or association with hydrogels as therapeutic agents for applications in regenerative medicine.
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20.
  • Alyami, Mana, et al. (författare)
  • Estimating compressive strength of concrete containing rice husk ash using interpretable machine learning-based models
  • 2024
  • Ingår i: Case Studies in Construction Materials. - : Elsevier. - 2214-5095. ; 20
  • Tidskriftsartikel (refereegranskat)abstract
    • The construction sector is a major contributor to global greenhouse gas emissions. Using recycled and waste materials in concrete is a practical solution to address environmental challenges. Currently, agricultural waste is widely used as a substitute for cement in the production of eco-friendly concrete. However, traditional methods for assessing the strength of such materials are both expensive and time-consuming. Therefore, this study uses machine learning techniques to develop prediction models for the compressive strength (CS) of rice husk ash (RHA) concrete. The ML techniques used in the present study include random forest (RF), light gradient boosting machine (LightGBM), ridge regression, and extreme gradient boosting (XGBoost). A total of 348 values of CS were collected from the experimental studies, and five characteristics of RHA concrete were taken as input variables. For the performance assessment of the models, multiple statistical metrics were used. During the training phase, the correlation coefficients (R) obtained for ridge regression, RF, XGBoost, and LightGBM were 0.943, 0.981, 0.985, and 0.996, respectively. In the testing set, the developed models demonstrated even higher performance, with correlation coefficients of 0.971, 0.993, 0.992, and 0.998 for ridge regression, RF, XGBoost, and LightGBM, respectively. The statistical analysis revealed that the LightGBM model outperformed other models, whereas the ridge regression model exhibited comparatively lower accuracy. SHapley Additive exPlanation (SHAP) method was employed for the interpretability of the developed model. The SHAP analysis revealed that water-to-cement is a controlling parameter in estimating the CS of RHA concrete. In conclusion, this study provides valuable guidance for builders and researchers to estimate the CS of RHA concrete. However, it is suggested that more input variables be incorporated and hybrid models utilized to further enhance the reliability and precision of the models.
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21.
  • Alyami, Mana, et al. (författare)
  • Predictive modeling for compressive strength of 3D printed fiber-reinforced concrete using machine learning algorithms
  • 2024
  • Ingår i: Case Studies in Construction Materials. - : Elsevier. - 2214-5095. ; 20
  • Tidskriftsartikel (refereegranskat)abstract
    • Three-dimensional (3D) printing in the construction industry is growing rapidly due to its inherent advantages, including intricate geometries, reduced waste, accelerated construction, cost-effectiveness, eco-friendliness, and improved safety. However, optimizing the mixture composition for 3D-printed concrete remains a formidable task, encompassing multiple variables and requiring a comprehensive trial-and-error experimentation process. Accordingly, this study used seven machine learning (ML) algorithms, including support vector regression (SVR), decision tree (DT), SVR-Bagging, SVR-Boosting, random forest (RF), gradient boosting (GB), and gene expression programming (GEP) for forecasting the compressive strength (CS) of 3D printed fiber-reinforced concrete (3DP-FRC). For model development, 299 data points were collected from experimental studies and split into two portions: 70% for model training and 30% for model validation. Various statistical metrics were employed to examine the accuracy and generalizability of the established models. The DT, RF, GB, and GEP models demonstrated higher accuracy in the validation set, achieving correlation (R) values of 0.987, 0.986, 0.986, and 0.98, respectively. The DT, RF, GB, and GEP models exhibited mean absolute error (MAE) scores of 4.644, 3.989, 3.90, and 5.691, respectively. Furthermore, the combination of SVR with boosting and bagging techniques slightly improved the accuracy compared to the individual SVR model. Additionally, the SHapley Additive exPlanations (SHAP) approach unveils the proportional significance of parameters in influencing the CS of 3DP-FRC. The SHAP technique revealed that water, silica fume, superplasticizer, sand content, and loading directions are the dominant parameters in estimating the CS of 3DP-FRC. The SHAP local interpretability unveils the intrinsic relationship between diverse input variables and their impacts on the strength of 3DP-FRC. The SHAP interpretability offers significant insights into the optimum mix proportion of 3DP-FRC.
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22.
  • Delgado Carrascon, Rosalia, 1987-, et al. (författare)
  • Hot-Wall MOCVD for High-Quality Homoepitaxy of GaN : Understanding Nucleation and Design of Growth Strategies
  • 2022
  • Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 22:12, s. 7021-7030
  • Tidskriftsartikel (refereegranskat)abstract
    • Thick GaN layers with a low concentration of defects are the key to enable next-generation vertical power electronic devices. Here, we explore hot-wall metalorganic chemical vapor deposition (MOCVD) for the development of GaN homoepitaxy. We propose a new approach to grow high quality homoepitaxial GaN in N2-rich carrier gas and at a higher supersaturation as compared to heteroepitaxy. We develop a low temperature GaN as an optimum nucleation scheme based on the evolution and thermal stability of the GaN surface under different gas compositions and temperatures. Analysis in the framework of nucleation theory of homoepitaxial layers simultaneously grown on GaN templates on SiC and on hydride vapor phase epitaxy GaN substrates is presented. We show that residual strain and screw dislocation densities affect GaN nucleation and subsequent growth leading to distinctively different morphologies of GaN homoepitaxial layers grown on GaN templates and native substrates, respectively. The established comprehensive picture provides a guidance for designing strategies for growth conditions optimization in GaN homoepitaxy. GaN with atomically flat and smooth epilayer surfaces with a root-mean-square roughness value as low as 0.049 nm and low background carbon concentration of 5.3 x 1015 cm-3 has been achieved. It is also shown that there is no generation of additional dislocations during homoepitaxial growth. Thus, our results demonstrate the potential of the hot-wall MOCVD technique to deliver high-quality GaN material for vertical power devices.
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23.
  • Dilshad, E., et al. (författare)
  • Synthesis of Functional Silver Nanoparticles and Microparticles with Modifiers and Evaluation of Their Antimicrobial, Anticancer, and Antioxidant Activity
  • 2020
  • Ingår i: Journal of Functional Biomaterials. - : MDPI AG. - 2079-4983. ; 11:4
  • Tidskriftsartikel (refereegranskat)abstract
    • An accumulating body of evidence reports the synthesis and biomedical applications of silver nanoparticles. However, the studies regarding the use of maleic acid and citric acid in the synthesis of nano-sized silver particles (AgNPs) and micro-sized silver particles (AgMPs) as well as their antibacterial, antifungal, and anticancer activities have not been reported. In the current study, we synthesized AgNPs and AgMPs using maleic acid and citric acid as capping agents and have characterized them by UV-Vis, energy-dispersive X-Ray spectroscopy (EDS), X-Ray diffraction (XRD), and scanning electron microscope (SEM) analysis. The capped silver particles were examined for their antimicrobial activity and cytotoxicity against bacteria, fungi, and brine shrimp. Additionally, the anticancer activity of these particles was tested against human breast and liver cancer cell lines. The free radical scavenging activity of capped silver particles was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. SEM analysis revealed a round plate-like morphology of maleic acid capped particles with an average size of 39 +/- 4 nm, whereas citric acid capped particles display flower-shaped morphology with rough surfaces and an average size of 250 +/- 5 nm. The uncapped AgMPs were hexagonal with 500 +/- 4 nm size. EDS and XRD analysis confirmed the presence of Ag and face-centered cubic crystalline nature, respectively. Functionally, capped silver particles exhibited antibacterial activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis, and Micrococcus luteus) and Gram-negative bacteria (Salmonella setubal, Enterobacter aerogenes, and Agrobacterium tumefaciens). The bactericidal activity was more active against Gram-negative bacteria with minimum inhibitory concentration (MIC) as low as 5 ppm as compared to 25 ppm for Gram-positive. Similarly, the silver particles demonstrated antifungal activity by inhibiting the growth of five fungal strains (Mucor species, Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, and Fusarium solani) up to 50% at the concentration of 500 ppm. Additionally, these particles showed substantial toxicity against brine shrimp and also significantly inhibited the proliferation of breast cancer (MCF7) and liver cancer (HePG2) cell lines (IC50 8.9-18.56 mu M). Uncapped AgMPs were less effective, inhibiting only the proliferation of MCF7 cells with IC50 46.54 mu M. Besides cytotoxicity, these particles acted as potential antioxidants, showing free radical scavenging up to 74.4% in a concentration-dependent manner. Taken together, our results showed that the modifiers affect the shape and size of silver particles and may, in part, contribute to the antimicrobial and antioxidant activity of silver particles. However, the contribution of maleic acid and citric acid in enhancing the antimicrobial, anticancer, and antioxidant potential independent of silver nano and microparticles needs to be studied further. In vivo experiments may determine the therapeutic effectiveness of silver particles capped with these modifiers.
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24.
  • Farash, Mohammad Sabzinejad, et al. (författare)
  • A Provably Secure RFID Authentication Protocol Based on Elliptic Curve for Healthcare Environments
  • 2016
  • Ingår i: Journal of medical systems. - : Springer-Verlag New York. - 0148-5598 .- 1573-689X. ; 40:7
  • Tidskriftsartikel (refereegranskat)abstract
    • To enhance the quality of healthcare in the management of chronic disease, telecare medical information systems have increasingly been used. Very recently, Zhang and Qi (J. Med. Syst. 38(5):47, 32), and Zhao (J. Med. Syst. 38(5):46, 33) separately proposed two authentication schemes for telecare medical information systems using radio frequency identification (RFID) technology. They claimed that their protocols achieve all security requirements including forward secrecy. However, this paper demonstrates that both Zhang and Qi’s scheme, and Zhao’s scheme could not provide forward secrecy. To augment the security, we propose an efficient RFID authentication scheme using elliptic curves for healthcare environments. The proposed RFID scheme is secure under common random oracle model.
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25.
  • Fatima, Farah, et al. (författare)
  • Long Distance Metabolic Regulation through Adipose-Derived Circulating Exosomal miRNAs: A Trail for RNA-Based Therapies?
  • 2017
  • Ingår i: Frontiers in physiology. - : Frontiers Media SA. - 1664-042X. ; 8
  • Forskningsöversikt (refereegranskat)abstract
    • The contribution of non-coding RNAs, such as microRNAs (miRNAs) in regulating physiological and pathological states has been intensively elucidated during last 15 years. The discovery of circulating miRNAs (cir-miRNAs) in variety of body fluids, is, however a recent focus of interest in understanding pathophysiological states of their originating cells/organs. Yet another stimulating debate that takes miRNAs to the next level is their presence in exosomes, and this is truly interesting area of research. Exosomes are cell-derived extracellular vesicles, and are naturally equipped biological vehicles that not only enable functional transfer of miRNAs between cells (horizontal transfer) but also foster inter-organ communication, presumably guided by organ specific receptors-decorated on their surface. However, understandings on inter-organ communication elicited by tissue specific exosomal-miRNA fingerprints remain elusive. Recently, Thomou et al., has discovered that adipose tissue contributes a large fraction of adipose specific exosomal-miRNA fingerprints in blood circulation. Experimental evidence emphasize adipose tissue as major depot of cir-miRNAs that sail through blood flow and reach to distal organs-primarily in the liver, where they regulate gene expression of host tissue and elicit metabolic control. This appears to be a genetic form of adipokines (endocrine factors secreted from adipose tissue). We review such offshore metabolic insults, and make an effort to address few important missing links between miRNAs processing and their incorporation into exosomes. We provide potential perspectives on how this knowledge could be steered towards RNA-based therapeutics for monitoring complex metabolic diseases and beyond.
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26.
  • Fatima, Farah, et al. (författare)
  • Non-coding RNAs in Mesenchymal Stem Cell-Derived Extracellular Vesicles: Deciphering Regulatory Roles in Stem Cell Potency, Inflammatory Resolve, and Tissue Regeneration
  • 2017
  • Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 8
  • Forskningsöversikt (refereegranskat)abstract
    • Extracellular vesicles (EVs) are heterogeneous populations of nano- and micro-sized vesicles secreted by various cell types. There is mounting evidence that EVs have widespread roles in transporting proteins, lipids, and nucleic acids between cells and serve as mediators of intercellular communication. EVs secreted from stem cells could function as paracrine factors, and appear to mimic and recapitulate several features of their secreting cells. EV-mediated transport of regulatory RNAs provides a novel source of trans-regulation between cells. As such, stem cells have evolved unique forms of paracrine mechanisms for recapitulating their potencies with specialized functions by transporting non-coding RNAs (ncRNAs) via EVs. This includes the dissemination of stem cell-derived EV-ncRNAs and their regulatory effects elicited in differentiation, self-renewal, pluripotency, and the induction of reparative programs. Here, we summarize and discuss the therapeutic effects of mesenchymal stem cell-derived EV-ncRNAs in the induction of intrinsic regenerative programs elicited through regulating several mechanisms. Among them, most noticeable are the EV-mediated enrichment of ncRNAs at the injury sites contributing the regulation of matrix remodeling, epithelial mesenchymal transitions, and attraction of fibroblasts. Additionally, we emphasize EV-mediated transmission of anti-inflammatory RNAs from stem cells to injury site that potentially orchestrate the resolution of the inflammatory responses and immune alleviation to better facilitate healing processes. Collectively, this knowledge indicates a high value and potential of EV-mediated RNA-based therapeutic approaches in regenerative medicine.
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27.
  • Fatima, Farah, et al. (författare)
  • Radiological features of experimental staphylococcal septic arthritis by micro computed tomography scan.
  • 2017
  • Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 12:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Permanent joint dysfunction due to bone destruction occurs in up to 50% of patients with septic arthritis. Recently, imaging technologies such as micro computed tomography (μCT) scan have been widely used for preclinical models of autoimmune joint disorders. However, the radiological features of septic arthritis in mice are still largely unknown.NMRI mice were intravenously or intra-articularly inoculated with S. aureus Newman or LS-1 strain. The radiological and clinical signs of septic arthritis were followed for 10 days using μCT. We assessed the correlations between joint radiological changes and clinical signs, histological changes, and serum levels of cytokines.On days 5-7 after intravenous infection, bone destruction verified by μCT became evident in most of the infected joints. Radiological signs of bone destruction were dependent on the bacterial dose. The site most commonly affected by septic arthritis was the distal femur in knees. The bone destruction detected by μCT was positively correlated with histological changes in both local and hematogenous septic arthritis. The serum levels of IL-6 were significantly correlated with the severity of joint destruction.μCT is a sensitive method for monitoring disease progression and determining the severity of bone destruction in a mouse model of septic arthritis. IL-6 may be used as a biomarker for bone destruction in septic arthritis.
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28.
  • Fatima, Farah, et al. (författare)
  • Stem cell-derived exosomes: roles in stromal remodeling, tumor progression, and cancer immunotherapy
  • 2015
  • Ingår i: Cancer Communications. - : Springer Science and Business Media LLC. - 2523-3548. ; 34:12, s. 541-53
  • Tidskriftsartikel (refereegranskat)abstract
    • Stem cells are known to maintain stemness at least in part through secreted factors that promote stem-like phenotypes in resident cells. Accumulating evidence has clarified that stem cells release nano-vesicles, known as exosomes, which may serve as mediators of cell-to-cell communication and may potentially transmit stem cell phenotypes to recipient cells, facilitating stem cell maintenance, differentiation, self-renewal, and repair. It has become apparent that stem cell-derived exosomes mediate interactions among stromal elements, promote genetic instability in recipient cells, and induce malignant transformation. This review will therefore discuss the potential of stem cell-derived exosomes in the context of stromal remodeling and their ability to generate cancer-initiating cells in a tumor niche by inducing morphologic and functional differentiation of fibroblasts into tumor-initiating fibroblasts. In addition, the immunosuppressive potential of stem cell-derived exosomes in cancer immunotherapy and their prospective applications in cell-free therapies in future translational medicine is discussed.
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29.
  • Gisladottir, Rosa S, et al. (författare)
  • Sequence Variants in TAAR5 and Other Loci Affect Human Odor Perception and Naming.
  • 2020
  • Ingår i: Current biology : CB. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 30:23
  • Tidskriftsartikel (refereegranskat)abstract
    • Olfactory receptor (OR) genes in humans form a special class characterized by unusually high DNA sequence diversity, which should give rise to differences in perception and behavior. In the largest genome-wide association study to date based on olfactory testing, we investigated odor perception and naming with smell tasks performed by 9,122 Icelanders, with replication in a separate sample of 2,204 individuals. We discovered an association between a low-frequency missense variant in TAAR5 and reduced intensity rating of fish odor containing trimethylamine (p.Ser95Pro, pcombined= 5.6× 10-15). We demonstrate that TAAR5 genotype affects aversion to fish odor, reflected by linguistic descriptions of the odor and pleasantness ratings. We also discovered common sequence variants in two canonical olfactory receptor loci that associate with increased intensity and naming of licorice odor (trans-anethole: lead variant p.Lys233Asn in OR6C70, pcombined= 8.8× 10-16 and pcombined= 1.4× 10-9) and enhanced naming of cinnamon (trans-cinnamaldehyde; intergenic variant rs317787-T, pcombined= 5.0× 10-17). Together, our results show that TAAR5 genotype variation influences human odor responses and highlight that sequence diversity in canonical OR genes can lead to enhanced olfactory ability, in contrast to the view that greater tolerance for mutations in the human OR repertoire leads to diminished function.
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30.
  • Haneef, Tahir, et al. (författare)
  • Recent progress in two dimensional Mxenes for photocatalysis : a critical review
  • 2023
  • Ingår i: 2D Materials. - : Institute of Physics (IOP). - 2053-1583. ; 10:1
  • Forskningsöversikt (refereegranskat)abstract
    • Transition metal carbides and nitrides, generally known as MXenes have emerged as an alternative to improve photocatalytic performance in renewable energy and environmental remediation applications because of their high surface area, tunable chemistry, and easily adjustable elemental compositions. MXenes have many interlayer groups, surface group operations, and a flexible layer spacing that makes them ideal catalysts. Over 30 different members of the MXenes family have been explored and successfully utilized as catalysts. Particularly, MXenes have achieved success as a photocatalyst for carbon dioxide reduction, nitrogen fixation, hydrogen evolution, and photochemical degradation. The structure of MXenes and the presence of hydrophilic functional groups on the surface results in excellent photocatalytic hydrogen evolution. In addition, MXenes' surface defects provide abundant CO2 adsorption sites. Moreover, their highly efficient catalytic oxidation activity is a result of their excellent two-dimensional nanomaterial structure and high-speed electron transport channels. This article comprehensively discusses the structure, synthesis techniques, photocatalytic applications (i.e. H-2 evolution, N-2 fixation, CO2 reduction, and degradation of pollutants), and recyclability of MXenes. This review also critically evaluates the MXene-based heterostructure and composites photocatalyst synthesis process and their performance for organic pollutant degradation. Finally, a prospect for further research is presented in environmental and energy sciences.
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31.
  • Irshad, Azeem, et al. (författare)
  • A secure and provable multi-server authenticated key agreement for TMIS based on Amin et al. scheme
  • 2017
  • Ingår i: Multimedia tools and applications. - : Springer. - 1380-7501 .- 1573-7721. ; 76:15, s. 16463-16489
  • Tidskriftsartikel (refereegranskat)abstract
    • The security for Telecare Medicine Information Systems (TMIS) has been crucial for reliable dispensing of the medical services to patients at distant locations. Security and privacy element needs to be there for any physician or caregiver to make certain an appropriate diagnosis, medical treatment or any other exchange of critical information. In this connection, many relevant TMIS-based authentication schemes have been presented, however various forms of attacks and inefficiencies render these schemes inapplicable for a practical scenario. Lately, Amin et al. proposed a scheme based on a multi-server authentication for TMIS. However, the Amin et al., scheme has been found vulnerable to user and server impersonation attacks. We have proposed an improved model with higher performance and efficiency, as evident from the forthcoming sections. Besides, the scheme has been backed up by formal security analysis using BAN logic to ensure the resilience of the proposed scheme.
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32.
  • Jabbari, Nasrollah, et al. (författare)
  • Bystander effects of ionizing radiation: conditioned media from X-ray irradiated MCF-7 cells increases the angiogenic ability of endothelial cells.
  • 2019
  • Ingår i: Cell communication and signaling : CCS. - : Springer Science and Business Media LLC. - 1478-811X. ; 17:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Non-targeting effects of radiotherapy have become as clinical concern due to secondary tumorigenesis in the patients receiving radiotherapy. Radiotherapy also affects non-tumoral cells present in the tumor microenvironment and surrounding tissues. As such, the irradiated cells are thought to communicate the signals that promote secondary tumorigenesis by affecting the function and fate of non-irradiated cells in the vicinity including endothelial cells. This may include up-regulation of genes in irradiated cells, secretion of paracrine factors and induction of gene expression in surrounding non-irradiated cells, which favor cell survival and secondary tumorigenesis. In the current study, we aimed to investigate whether the conditioned media from X-ray irradiated MCF-7 cells contribute to induction of gene expression in human umbilical vein endothelial cells (HUVECs) in vitro and modulate their angiogenic capability and migration.Following the co-culturing of X-ray irradiated MCF-7 media with HUVECs, the migration and wound healing rate of HUVECs was monitored using Transwell plate and scratch wound healing assay, respectively. The levels of angiogenic protein i.e. vascular endothelial growth factor (VEGF-A) in the conditioned media of MCF-7 cells was measured using ELISA. Additionally, we quantified mRNA levels of VEGFR-2, HSP-70, Ang-2, and Ang-1 genes in HUVECs by real time-PCR. Tubulogenesis capacity of endothelial cells was measured by growth factor reduced Matrigel matrix, whereas expression of CD34 (a marker of angiogenic tip cells) was detected by flow cytometry.Data showed that VEGF-A protein content of conditioned media of irradiated MCF-7 cells was increased (P<0.05) with increase in dose. Data showed that irradiated conditioned media from MCF-7 cells, when incubated with HUVECs, significantly enhanced the cell migration and wound healing rate of HUVECs in a dose-dependent manner (P<0.05). The mRNA levels of VEGFR-2, HSP-70, Ang-2, and Ang-1 were dose-dependently enhanced in HUVECs incubated with irradiated conditioned media (P<0.05). Importantly, HUVECs treated with irradiated conditioned media showed a marked increase in the tube formation capability as well as in expression of CD34 marker (P<0.05).Our findings indicate that conditioned media from irradiated MCF-7 cells induce angiogenic responses in endothelial cells in vitro, which could be due to transfer of overexpressed VEGF-A and possibly other factors secreted from irradiated MCF-7 cells to endothelial cells, and induction of intrinsic genes (VEGFR-2, HSP-70, Ang-2, and Ang-1) in endothelial cells. Video abstract.
  •  
33.
  • Jabbari, N., et al. (författare)
  • Ionizing Radiation Increases the Activity of Exosomal Secretory Pathway in MCF-7 Human Breast Cancer Cells: A Possible Way to Communicate Resistance against Radiotherapy
  • 2019
  • Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 20:15
  • Tidskriftsartikel (refereegranskat)abstract
    • Radiation therapy, which applies high-energy rays, to eradicate tumor cells, is considered an essential therapy for the patients with breast cancer. Most tumor cells secrete exosomes, which are involved in cell-to-cell communication in tumor tissue and contribute therapeutic resistance and promote tumor aggressiveness. Here, we investigated the effect of clinically applicable doses of X-ray irradiation (2, 4, 6, 8, 10 Gy) on the dynamics of the exosomes' activity in MCF-7 breast cancer cells. Survival and apoptosis rate of cells against X-ray doses was examined using MTT and flow cytometry assays, respectively. Whereas, the levels of reactive oxygen species (ROS) in the X-ray-treated cells were detected by fluorometric method. The mRNA levels of vital genes involved in exosome biogenesis and secretion including Alix, Rab11, Rab27a, Rab27b, TSPA8, and CD63 were measured by real-time PCR. The protein level of CD63 was examined by Western blotting. Additionally, exosomes were characterized by monitoring acetylcholinesterase activity, transmission electron microscopy, size determination, and zeta potential. The result showed that in comparison with control group cell survival and the percentage of apoptotic cells as well as amount of ROS dose-dependently decreased and increased in irradiated cells respectively (p < 0.05). The expression level of genes including Alix, Rab27a, Rab27b, TSPA8, and CD63 as well as the protein level of CD63 upraised according to an increase in X-ray dose (p < 0.05). We found that concurrent with an increasing dose of X-ray, the acetylcholinesterase activity, size, and zeta-potential values of exosomes from irradiated cells increased (p < 0.05). Data suggest X-ray could activate exosome biogenesis and secretion in MCF-7 cells in a dose-dependent way, suggesting the therapeutic response of cells via ROS and exosome activity.
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34.
  • Johannesson, Daniel, et al. (författare)
  • Analytical PSpice model for SiC MOSFET based high power modules
  • 2016
  • Ingår i: Microelectronics Journal. - : Elsevier. - 0026-2692. ; 53, s. 167-176
  • Tidskriftsartikel (refereegranskat)abstract
    • A simple analytical PSpice model has been developed and verified for a 4H–SiC based MOSFET power module with voltage and current ratings of 1200 V and 120 A. The analytical simulation model is a temperature dependent silicon carbide (SiC) MOSFET model that covers static and dynamic behavior, leakage current and breakdown voltage characteristics. The technology dependent MOSFET modeling parameters are extracted from characterization measurements, datasheets and PSpice simulations at various temperatures. The SiC MOSFET model is implemented in the PSpice circuit simulation platform using PSpice standard components and analog behavior modeling (ABM) blocks. The MOSFET switching performance is investigated under influence of different circuit elements, such as stray inductance, gate resistance and temperature, in order to study and estimate on-state and switching losses pre-requisite for design of various converter and inverter topologies. The performance of the SiC MOSFET model is fairly accurate and correlates well with the measured results over a wide temperature range.
  •  
35.
  • Johannesson, Daniel, et al. (författare)
  • Assessment of 10 kV, 100 A Silicon Carbide MOSFET Power Modules
  • 2018
  • Ingår i: IEEE transactions on power electronics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0885-8993 .- 1941-0107. ; 33:6, s. 5215-5225
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a thorough characterization of 10 kV SiC MOSFET power modules, equipped with third-generation MOSFET chips and without external free-wheeling diodes, using the inherent SiC MOSFET body-diode instead. The static performance (e.g., IDS-VDS, IDS-VGS, C-V characteristics, leakage current, body-diode characteristics) is addressed by measurements at various temperatures. Moreover, the power module is tested in a simple chopper circuit with inductive load to assess the dynamic characteristics up to 7 kV and 120 A. The SiC MOSFET power module exhibits an on-state resistance of 40 m Omega at room-temperature and leakage current in the range of 100 nA, approximately one order of magnitude lower than that of a 6.5 kV Si-IGBT. The power module shows fast switching characteristics with the turn-on (turn-on loss) and turn-off (turn-off loss) times of 130 ns (89 mJ) and 145 ns (33 mJ), respectively, at 6.0 kV supply voltage and 100 A current. Furthermore, a peak short-circuit current of 900 A and a short-circuit survivability time of 3.5 mu s were observed. The extracted characterization results could serve as input for power electronic converter design and may support topology evaluation with realistic system performance predictability, using SiC MOSFET power modules in the energy transmission and distribution networks.
  •  
36.
  • Johannesson, Daniel, et al. (författare)
  • Assessment of Junction Termination Extension Structures For Ultrahigh-Voltage Silicon Carbide Pin-Diodes; A Simulation Study
  • 2021
  • Ingår i: IEEE Open Journal of Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2644-1314. ; 2, s. 304-314
  • Tidskriftsartikel (refereegranskat)abstract
    • The junction termination extension (JTE) structures for ultrahigh-voltage (UHV) devices consumes a considerable part of the semiconductor chip area. The JTE area is closely related to chip performance, process yield and ultimately device cost. The JTE lengths for UHV devices (i.e., > 30 kV) are still unknown, not visible in the scientific literature and have therefore been predicted in this study by means of two-dimensional numerical simulations using the Sentaurus based technology computer-aided design (TCAD) tool. A previously reported space-modulated, two-zone JTE (SM-JTE) structure has been used as an input to set up a suitable TCAD model, which is further scaled to JTE lengths required for 40 kV class and 50 kV class SiC PiN diodes. The simulation results indicate that the SM-JTE requires an 1800 μm one-sided JTE length with 27 guard rings for a 40 kV theoretical PiN diode and 2700 μm with 36 guard rings for a 50 kV device, resulting in breakdown voltages of 41.4 kV and 51.7 kV, respectively. Moreover, the design considerations of different JTE categories are discussed with focus on the adaptability of the termination structures in ultrahigh-voltage devices, e.g., V B > 30 kV, which results in a comparison of the SM-JTE structure with other high-voltage JTE designs.
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37.
  • Johannesson, Daniel, et al. (författare)
  • Assessment of PSpice model for commercial SiC MOSFET power modules
  • 2015
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, a circuit level simulation model for SiC MOSFET power modules has been assessed. The static and dynamic characteristics of a 1.2 kV 800 A SiC MOSFET power module has been measured, simulated and verified in the PSpice circuit simulation platform. The SiC MOSFET power module is evaluated in two case studies, first where the power module is treated as a single device (simulated with one sub-module) and secondly where the performance of the power module is simulated as multiple MOSFET chips in parallel (multiple sub-modules). Here, the bond-wires between the chips are also included as inductive elements. The simulated static characteristics of the SiC MOSFET power module are well aligned with the measured data. In the first case, the simulation model in PSpice shows accurate dynamic performance overall, with exceptions from high-frequency oscillations that arises during turn-on and turn-off. The second case study shows that the oscillations can be captured by introducing multiple MOSFET chips in parallel and where the bond-wires in between are represented by inductors. A slight increase of high-frequency oscillations is noticed but on the cost of reduced simulation robustness (e.g. convergence issues) due to a more complex simulation circuit. Finally, it is concluded that the simulation model performance is overall accurate, both for static and dynamic performance. Further, the model is capable to estimate on-state loss and switching loss in a satisfactory manner and is utilized to evaluate and optimize power electronic converter cell parameters, for instance stray inductance, gate resistance and temperature, and their impact on converter energy loss.
  •  
38.
  • Johannesson, Daniel, et al. (författare)
  • Development of a PSPICE Model for 1200 V/800 A SiC Bipolar Junction Transistor Power Module
  • 2014
  • Konferensbidrag (refereegranskat)abstract
    • The characteristics of a 1200 V and 800 A bipolar junction transistor (BJT) power module has been measured, simulated and verified for the first time in the PSPICE platform. The simulation model is based on a silicon carbide (SiC) Gummel-Poon model for high power applications. The implemented model has been extended with temperature dependent equations in order to extend the BJT operating temperature range. PSPICE simulations are performed to extract technology dependent modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. The performance of the SiC BJT model is fairly accurate and correlates well with the measured results over a wide temperature range.
  •  
39.
  • Johannesson, Daniel, et al. (författare)
  • Development of a PSpice Model for SiC MOSFET Power Modules
  • 2015
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, the static and dynamic characteristics of a 1200 V and 120 A silicon carbide (SiC) MOSFET power module has been measured, simulated and verified in the PSpice circuit simulation platform. Experimental measurements and PSpice simulations are performed to extract the technology dependent modeling parameters. The model is implemented in the PSpice circuit simulation platform using both standard components and analog behavior modeling (ABM) blocks. The simulation results of the model is fairly accurate and correlates well with the measured results over a wide temperature range. The developed model is used to facilitate converter design at cell level and hence predict and optimize the cell performance (i.e., energy losses) with varying circuit parameters (e.g., stray inductances, temperatures, gate resistances etc.,).
  •  
40.
  • Johannesson, Daniel, et al. (författare)
  • Development of a Simple Analytical PSpice Model for SiC-Based BJT Power Modules
  • 2016
  • Ingår i: IEEE transactions on power electronics. - : IEEE Press. - 0885-8993 .- 1941-0107. ; 31:6, s. 4517-4525
  • Tidskriftsartikel (refereegranskat)abstract
    • A simple analytical Spice-type model has been developed and verified for the first time for 4H-SiC-based bipolar junction transistor (BJT) power module with voltage and current rating of 1200 V and 800 A. The simulation model is based on a temperature-dependent silicon carbide (SiC) Gummel-Poon model for high-power applications. PSpice simulations are performed to extract technology-dependent modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. Influence of various circuit elements, for instance, stray inductance and base resistance and internal device modeling parameters, carrier life time, and emitter doping, on switching losses has been studied. The performance of the SiC BJT model is fairly accurate and correlates well with the measured results over a wide temperature range.
  •  
41.
  • Johannesson, Daniel, et al. (författare)
  • Dynamic Avalanche Limit and Current Filamentation Onset Limit in 4H-Silicon Carbide High-Voltage Diodes
  • 2021
  • Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; , s. 1-1
  • Tidskriftsartikel (refereegranskat)abstract
    • Dynamic avalanche (DA) phenomena and current filament (CF) formation are two extreme conditions observed in high-power devices, setting the maximum limit on turn-on/off current capability and di/dt in Silicon-based bipolar devices. The properties of the Silicon Carbide (SiC) material enable devices with increased resilience for DA and CF compared to Si counterparts, and thus the SOA limits may be extended. In this study, the limit of DA and CF in SiC-based semiconductor structures are investigated by numerical TCAD simulations, for different current levels, di/dt, and temperatures for high-voltage devices (e.g., 20 kV class). DA is first indicated for di/dt beyond 105 kA/μs for current densities in the range of 50–1000 A/cm2, at 448 K. Similarly, stray inductance induced avalanche conditions are initiated above 33 kA/μs, while CF is initiated for di/dt starting from 83 kA/μs for current densities in the range of 8.3 kA/cm2. Moreover, the effects of the stray inductance in the main circuit loop are studied which may cause critical voltage transients during certain operating conditions. The outcome of the study may be useful to determine safe-operating-area limits and to be used as input for power electronic converter design as well as gate driver design for high-power electronic systems.
  •  
42.
  • Johannesson, Daniel, et al. (författare)
  • Evaluation of Ultrahigh-Voltage 4H-SiC Gate Turn-Off Thyristors and Insulated-Gate Bipolar Transistors for High-Power Applications
  • 2021
  • Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 37:4, s. 4133-4147
  • Tidskriftsartikel (refereegranskat)abstract
    • Technology-based computer-aided design (TCAD) models have been used to predict the static and dynamic performance of ultrahigh-voltage (UHV) 4H-Silicon Carbide (SiC) PiN diodes, insulated-gate bipolar transistors (IGBTs), and gate turn-off (GTO) thyristors designed for 2050 kV blocking voltage capability. The simulated forward voltage drops of 2050 kV device designs range between 3.15.6 V for PiN diodes, 4.210.0 V for IGBTs, and 3.47.8 V for GTO thyristors at 20 A/cm2 for room temperature operation. Moreover, with a low switching frequency application (i.e., 150 Hz) in mind, the switching energy losses using an 30 kV SiC GTO thyristor design are approximately EON/EOFF_GTO = 268/640 mJ, EON/EOFF_FWD = 388/6 mJ diode recovery losses, and EON/EOFF_SNUB = 954/22 mJ snubber component losses. The corresponding values for a SiC IGBT design are EON/EOFF_IGBT = 983/748 mJ, both operated at 448 K, A = 20 s, and with 30 A/cm2. The simulation output is used in a benchmark evaluation for a 1 GW, 640 kV application case, employing modular multilevel high-power converter legs comprising series-connected UHV SiC devices and state-of-the-art 4.5 kV Si bi-mode insulated-gate transistors (BiGTs). It is concluded that the high-voltage SiC power electronic building blocks present promising alternatives to existing high-voltage Si device counterparts in terms of system compactness and efficiency.
  •  
43.
  • Johannesson, Daniel, et al. (författare)
  • Potential of Ultra-High Voltage Silicon Carbide Semiconductor Devices
  • 2016
  • Ingår i: 2016 IEEE 4TH WORKSHOP ON WIDE BANDGAP POWER DEVICES AND APPLICATIONS (WIPDA). - : IEEE conference proceedings. - 9781509015764 ; , s. 253-258
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, the theoretical performance of ultra-high voltage Silicon Carbide (SiC) based devices are investigated. The SiC semiconductor device conduction power loss and switching power loss are predicted and compared with different modeling approaches, for SiC metal-oxide semiconductor field-effect transistors (MOSFETs) up to 20 kV and SiC gate turn-off (GTO) thyristors and SiC insulated-gate bipolar transistors (IGBTs) up to 50 kV. A parameter sensitivity analysis has been performed to observe the device power loss under various operating conditions, for instance current density, temperature and charge carrier lifetime. Also, the maximum allowed current density and maximum switching frequency for a maximum chip power dissipation limit of 300 W/cm(2) are investigated. The simulation results indicate that the SiC MOSFET has the highest current capability up to approximately 15 kV, while the SiC IGBT is suitable in the range of 15 kV to 35 kV, and thereafter the SiC GTO thyristor supersedes the loss performance from 35 kV to 50 kV.
  •  
44.
  • Johannesson, Daniel, et al. (författare)
  • Static and Dynamic Performance Prediction of Ultra-High-Voltage Silicon Carbide Insulated-Gate Bipolar Transistors
  • 2021
  • Ingår i: IEEE transactions on power electronics. - 0885-8993 .- 1941-0107. ; 36:5, s. 5874-5891
  • Tidskriftsartikel (refereegranskat)abstract
    • The performance of theoretical ultra-high-voltagepower semiconductor devices has been predicted by means ofnumerical simulations using the Sentaurus technology computeraideddesign tool. A general silicon carbide punch-throughinsulated-gate bipolar transistor (IGBT) structure has beenimplemented with suitable physics-based models and parametersto reflect the device characteristics in a wide range of deviceblocking voltages from 20 to 50 kV. The models for 20 kV classIGBTs have been implicitly validated by means of publishedexperimental results. Mixed-mode simulations were performedthat predicted total switching energy loss densities of 335, 629,906 and 999 mJ/cm2 for 20, 30, 40 and 50 kV class devicesrespectively, at 25ºC, JC = 20 A/cm2 and an ambipolar carrierlifetime of 20 μs. While the IGBT on-state forward voltage dropreduces, the switching losses increase with higher charge-carrierlifetime for a given current density (e.g., 20 A/cm2). The largespan of simulation results will be used as an input support to thedesign of future high-power converters.
  •  
45.
  • Johannesson, Daniel, et al. (författare)
  • TCAD Model Calibration of High Voltage 4H-SiC Bipolar Junction Transistors
  • 2019
  • Ingår i: Materials Science Forum. - : Trans Tech Publications, Ltd.. ; , s. 670-673
  • Konferensbidrag (refereegranskat)abstract
    • In this project, a Technology CAD (TCAD) model has been calibrated and verified against experimental data of a 15 kV silicon carbide (SiC) bipolar junction transistor (BJT). The device structure of the high voltage BJT has been implemented in the Synopsys Sentaurus TCAD simulation platform and design of experiment simulations have been performed to  extract and fine-tune device parameters and 4H-SiC material parameters to accurately reflect the 15 kV SiC BJT experimental results. The set of calibrated TCAD parameters may serve as a base for further investigations of various SiC device design and device operation in electrical circuits.
  •  
46.
  • Johannesson, Daniel (författare)
  • Ultrahigh-Voltage Silicon Carbide Device Performance, Requirements, and Limitations in High-Power Applications
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The increased awareness of the on-going climate change accelerates the electric energy system transformation from fossil-fueled power sources towards systems with larger portions of renewable energy sources. Moreover, the grid infrastructure requires reinforcements to cope with increasing electrical energy demand. Flexible AC transmission systems (FACTS) and high-voltage DC (HVDC) transmission systems allow higher grid capacity, efficient transmission over long distances and sub-sea electrical energy transfer. Efficient sub-sea transmission is required for off-shore wind- and intercontinental grid connections. It is predicted that basic power electronic building blocks (PEBB) utilizing SiC-based semiconductor devices will provide converter system benefits (e.g., reduced number of series connected devices, less complex system, lower energy losses, lower cooling requirements and smaller station footprint), in comparison to systems employing Si-based semiconductor devices. The main objective of this thesis is to design, evaluate and identify the performance, requirements, and limitations of high-voltage SiC devices suitable for high-power applications. The SiC semiconductor device characteristics have been investigated by two-dimensional numerical simulations and experiments to assess the suitability in high-power applications. A calibrated set of technology computer-aided design (TCAD) simulation models are used as foundation for estimating the performance of SiC PiN diodes, SiC insulated-gate bipolar transistors (IGBTs) and SiC gate turn-off (GTO) thyristors with blocking voltage capabilities in the range of 20–50 kV. The static and dynamic device performances are assessed along with related gate driver requirements and snubber design requirements. The devices characteristic are studied using physical parameters of device layer structures, device processing parameters, and varying circuit parameters using mixed-mode simulations that results in a wide range of data for device performance predictability. Moreover, the experimental characterization of 10 kV, 100 A SiC metal-oxide semiconductorfield-effect transistor (MOSFET) power modules are demonstrated and compared to Si counterparts. The junction termination extension (JTE) design aspects for 20, 30, 40, and 50 kV devices are investigated where the results are used to predict the active area ratio for each blocking voltage class. In addition, the limit of critical operating conditions such as dynamic avalanche and current filamentation are derived by TCAD simulations, which indicates that the critical operation points are significantly higher than that of Si-based counterparts. The wide-range simulation data have been used in benchmarking SiC-based devices with Si counterparts in an application case of a 1 GW, 640 kV, modular multilevel converter (MMC)-based HVDC system. The analytical benchmark model indicates an energy loss reduction to approximately half by employing SiC device configurations compared to state-of-the-art Si bi-mode insulated gate transistors (BiGTs). The low energy losses along with the benefits by reduction of system complexity, control hardware, cables, and fibers (due to a lower amount of PEBBs), the SiC converter design presents a promising alternative to existing Si-based high-power modular multilevel converters.
  •  
47.
  • Johannesson, Daniel, et al. (författare)
  • Wide-Range Prediction of Ultra-High Voltage SiC IGBT Static Performance Using Calibrated TCAD Model
  • 2020
  • Ingår i: Materials Science Forum. ; , s. 911-916
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, a technology computer-aided design (TCAD) model of a silicon carbide (SiC) insulated-gate bipolar transistor (IGBT) has been calibrated against previously reported experimental data. The calibrated TCAD model has been used to predict the static performance of theoretical SiC IGBTs with ultra-high blocking voltage capabilities in the range of 20-50 kV. The simulation results of transfer characteristics, IC-VGE, forward characteristics, IC-VCE, and blocking voltage characteristics are studied. The threshold voltage is approximately 5 V, and the forward voltage drop is ranging from VF = 4.2-10.0 V at IC = 20 A, using a charge carrier lifetime of τA = 20 μs. Furthermore, the forward voltage drop impact for different process dependent parameters (i.e., carrier lifetimes, mobility/scattering and trap related defects) and junction temperature are investigated in a parametric sensitivity analysis. The wide-range simulation results may be used as an input to facilitate high power converter design and evaluation. In this case, the TCAD simulated static characteristics of SiC IGBTs is compared to silicon (Si) IGBTs in a modular multilevel converter in a general highpower application. The results indicate several benefits and lower conduction energy losses using ultra-high voltage SiC IGBTs compared to Si IGBTs.
  •  
48.
  • Khalid, M., et al. (författare)
  • Genetic Risk of Autism Spectrum Disorder in a Pakistani Population
  • 2020
  • Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 11:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Autism spectrum disorder (ASD) is a group of complex multifactorial neurodevelopmental and neuropsychiatric disorders in children characterized by impairment of communication and social interaction. Several genes with associated single nucleotide polymorphisms (SNPs) have been identified for ASD in different genetic association studies, meta-analyses, and genome-wide association studies (GWAS). However, associations between different SNPs and ASD vary from population to population. Four SNPs in genes CNTNAP2, EIF4E, ATP2B2, CACNA1C, and SNP rs4307059 (which is found between CDH9 and CDH10 genes) have been identified and reported as candidate risk factors for ASD. The aim of the present study was, for the first time, to assess the association of SNPs in these genes with ASD in the Pakistani population. PCR-based genotyping was performed using allele-specific primers in 93 ASD and 93 control Pakistani individuals. All genetic associations, genotype frequencies, and allele frequencies were computed as odds' ratios (ORs) using logistic regression with a threshold of p <= 0.01 to determine statistical significance. We found that the homozygous genotypes of mutant T alleles of CNTNAP2 and ATP2B2 were significantly associated with Pakistani ASD patients in unadjusted ORs (p < 0.01), but their significance score was lost in the adjusted model. Other SNPs such as rs4307059, rs17850950 of EIF4E, and rs1006737 of CACNA1C were not statistically significant. Based on this, we conclude that SNPs are not associated with, or are not the main cause of, autism in the Pakistani population, indicating the involvement of additional players, which need to be investigated in future studies in a large population size. One of the limitations of present study is its small sample size. However, this study, being the first on Pakistani ASD patients, may lay the foundations for future studies in larger samples.
  •  
49.
  • Khan, Owais, et al. (författare)
  • A Novel Densely Packed 4 × 4 MIMO Antenna Design for UWB Wireless Applications
  • 2023
  • Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 23:21
  • Tidskriftsartikel (refereegranskat)abstract
    • In this article, a compact 4-port UWB (Ultra-Wide Band) MIMO (Multiple Input Multiple Output) antenna is proposed. A low profile FR-4 substrate is used as a dielectric material with the dimensions of 58 × 58 mm2 (0.52λ × 0.52λ) at 2.8 GHz and a standard thickness of 1.6 mm. The proposed design characterizes an impedance bandwidth starting from 2.8 to 12.1 GHz (124.1%). Each of the four elements of the proposed MIMO antenna configuration consists of a monopole antenna with PG (partial ground) that has a slot at its center. The corner of each patch (radiator) and ground slot are rounded for impedance matching. Each unit cell is in an orthogonal orientation, forming a quad-port MIMO antenna system. For reference, the partial ground of each unit cell is connected meticulously with the others. The simulated results of the proposed quad-port MIMO antenna design were configured and validated by fabrication and testing. The proposed Quad-port MIMO design has a 6.57 dBi peak gain and 97% radiation efficiency. The proposed design has good isolation below 15 dB in the lower frequency range and below 20 dB in the higher frequency range. The design has a measured ECC (Envelop Correlation Co-efficient) of 0.03 and DG (Diversity Gain) of 10 dB. The value of TARC (Total Active Reflection Coefficient) over the entire operating band is less than 10 dB. Moreover, the design maintained CCL (Channel Capacity Loss) < 0.4 bits/sec/Hz and MEG (Mean Effective Gain) < 3 dB. Based on the obtained results, the proposed design is suitable for the intended high data rate UWB wireless communication portable devices.
  •  
50.
  • Khan, Waqas Nawaz, et al. (författare)
  • Performance Evaluation of Time-Reversal on Measured 60 GHz Wireless Channels
  • 2013
  • Ingår i: Wireless Personal Communications. - : Springer Science and Business Media LLC. - 1572-834X .- 0929-6212. ; 71:1, s. 707-717
  • Tidskriftsartikel (refereegranskat)abstract
    • Time-reversal (TR) signal processing has the potential to focus the transmitted signal at a desired receive (Rx) location in both space and time. At lower frequency bands, TR in conjunction with array antennas at transmit (Tx) or Rx has been shown to significantly improve its focusing performance relative to the case of single antennas at both link ends. This work for the first time investigates TR processing for multi-antenna systems in the 60 GHz band. We consider both multiple-input-single-output and single-input-multiple-output (SIMO) channels measured in the 60 GHz band in a conference room environment and investigate the effect of array size and its orientation on spatial and temporal compression properties of TR. It is observed that the root mean square (RMS) delay spread can be reduced significantly by the application of TR in the 60 GHz band and that the orientation of the Rx array significantly affects TR performance for SIMO systems.
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