| 1. |
- Phu, Vu Dinh, et al.
(author)
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Ventilator-associated respiratory infection in a resource-restricted setting: impact and etiology
- 2017
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In: Journal of Intensive Care. - : BioMed Central (BMC). - 2052-0492. ; 5
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Journal article (peer-reviewed)abstract
- Ventilator-associated respiratory infection (VARI) is a significant problem in resource-restricted intensive care units (ICUs), but differences in casemix and etiology means VARI in resource-restricted ICUs may be different from that found in resource-rich units. Data from these settings are vital to plan preventative interventions and assess their cost-effectiveness, but few are available.
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| 2. |
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| 3. |
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| 4. |
- Stanaway, Jeffrey D., et al.
(author)
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Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: A systematic analysis for the Global Burden of Disease Study 2017
- 2018
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In: The Lancet. - 1474-547X .- 0140-6736. ; 392:10159, s. 1923-1994
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Journal article (peer-reviewed)abstract
- Background The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk-outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk-outcome pairs, and new data on risk exposure levels and risk- outcome associations. Methods We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk-outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017.
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| 5. |
- Tran, Ngoc Hieu, et al.
(author)
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Genetic profiling of Vietnamese population from large-scale genomic analysis of non-invasive prenatal testing data
- 2020
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Journal article (peer-reviewed)abstract
- The under-representation of several ethnic groups in existing genetic databases and studies have undermined our understanding of the genetic variations and associated traits or diseases in many populations. Cost and technology limitations remain the challenges in performing large-scale genome sequencing projects in many developing countries, including Vietnam. As one of the most rapidly adopted genetic tests, non-invasive prenatal testing (NIPT) data offers an alternative untapped resource for genetic studies. Here we performed a large-scale genomic analysis of 2683 pregnant Vietnamese women using their NIPT data and identified a comprehensive set of 8,054,515 single-nucleotide polymorphisms, among which 8.2% were new to the Vietnamese population. Our study also revealed 24,487 disease-associated genetic variants and their allele frequency distribution, especially 5 pathogenic variants for prevalent genetic disorders in Vietnam. We also observed major discrepancies in the allele frequency distribution of disease-associated genetic variants between the Vietnamese and other populations, thus highlighting a need for genome-wide association studies dedicated to the Vietnamese population. The resulted database of Vietnamese genetic variants, their allele frequency distribution, and their associated diseases presents a valuable resource for future genetic studies.
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| 6. |
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| 7. |
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| 8. |
- Mac, TH, et al.
(author)
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Optimizing Active Tuberculosis Case Finding: Evaluating the Impact of Community Referral for Chest X-ray Screening and Xpert Testing on Case Notifications in Two Cities in Viet Nam
- 2020
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In: Tropical medicine and infectious disease. - : MDPI AG. - 2414-6366. ; 5:4
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Journal article (peer-reviewed)abstract
- To accelerate the reduction in tuberculosis (TB) incidence, it is necessary to optimize the use of innovative tools and approaches available within a local context. This study evaluated the use of an existing network of community health workers (CHW) for active case finding, in combination with mobile chest X-ray (CXR) screening events and the expansion of Xpert MTB/RIF testing eligibility, in order to reach people with TB who had been missed by the current system. A controlled intervention study was conducted from January 2018 to March 2019 in five intervention and four control districts of two low to medium TB burden cities in Viet Nam. CHWs screened and referred eligible persons for CXR to TB care facilities or mobile screening events in the community. The initial diagnostic test was Xpert MTB/RIF for persons with parenchymal abnormalities suggestive of TB on CXR or otherwise on smear microscopy. We analyzed the TB care cascade by calculating the yield and number needed to screen (NNS), estimated the impact on TB notifications and conducted a pre-/postintervention comparison of TB notification rates using controlled, interrupted time series (ITS) analyses. We screened 30,336 individuals in both cities to detect and treat 243 individuals with TB, 88.9% of whom completed treatment successfully. All forms of TB notifications rose by +18.3% (95% CI: +15.8%, +20.8%). The ITS detected a significant postintervention step-increase in the intervention area for all-form TB notification rates (IRR(β6) = 1.221 (95% CI: 1.011, 1.475); p = 0.038). The combined use of CHWs for active case findings and mobile CXR screening expanded the access to and uptake of Xpert MTB/RIF testing and resulted in a significant increase in TB notifications. This model could serve as a blueprint for expansion throughout Vietnam. Moreover, the results demonstrate the need to optimize the use of the best available tools and approaches in order to end TB.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Tran, Dien M., et al.
(author)
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High prevalence of colonisation with carbapenem-resistant Enterobacteriaceae among patients admitted to Vietnamese hospitals : Risk factors and burden of disease
- 2019
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In: Journal of Infection. - : Saunders Elsevier. - 0163-4453 .- 1532-2742. ; 79:2, s. 115-122
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Journal article (peer-reviewed)abstract
- BackgroundCarbapenem-resistant Enterobacteriaceae (CRE) is an increasing problem worldwide, but particularly problematic in low- and middle-income countries (LMIC) due to limitations of resources for surveillance of CRE and infection prevention and control (IPC).MethodsA point prevalence survey (PPS) with screening for colonisation with CRE was conducted on 2233 patients admitted to neonatal, paediatric and adult care at 12 Vietnamese hospitals located in northern, central and southern Vietnam during 2017 and 2018. CRE colonisation was determined by culturing of faecal specimens on selective agar for CRE. Risk factors for CRE colonisation were evaluated. A CRE admission and discharge screening sub-study was conducted among one of the most vulnerable patient groups; infants treated at an 80-bed Neonatal ICU from March throughout June 2017 to assess CRE acquisition, hospital-acquired infection (HAI) and treatment outcome.ResultsA total of 1165 (52%) patients were colonised with CRE, most commonly Klebsiella pneumoniae (n=805), Escherichia coli (n=682) and Enterobacter spp. (n=61). Duration of hospital stay, HAI and treatment with a carbapenem were independent risk factors for CRE colonisation. The PPS showed that the prevalence of CRE colonisation increased on average 4.2 % per day and mean CRE colonisation rates increased from 13% on the day of admission to 89% at day 15 of hospital stay. At the NICU CRE colonisation increased from 32% at admission to 87% at discharge, mortality was significantly associated (OR 5•5, P < 0•01) with CRE colonisation and HAI on admission.ConclusionThese data indicate that there is an epidemic spread of CRE in Vietnamese hospitals with rapid transmission to hospitalised patients.
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| 14. |
- Abbafati, Cristiana, et al.
(author)
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- 2020
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Journal article (peer-reviewed)
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| 15. |
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- 2019
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Journal article (peer-reviewed)
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| 16. |
- Lam, Thua-Phong, et al.
(author)
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Flavonoids as dual-target inhibitors against α-glucosidase and α-amylase : a systematic review of in vitro studies
- 2024
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In: NATURAL PRODUCTS AND BIOPROSPECTING. - : Springer. - 2192-2195 .- 2192-2209. ; 14:1
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Research review (peer-reviewed)abstract
- Diabetes mellitus remains a major global health issue, and great attention is directed at natural therapeutics. This systematic review aimed to assess the potential of flavonoids as antidiabetic agents by investigating their inhibitory effects on alpha-glucosidase and alpha-amylase, two key enzymes involved in starch digestion. Six scientific databases (PubMed, Virtual Health Library, EMBASE, SCOPUS, Web of Science, and WHO Global Index Medicus) were searched until August 21, 2022, for in vitro studies reporting IC50 values of purified flavonoids on alpha-amylase and alpha-glucosidase, along with corresponding data for acarbose as a positive control. A total of 339 eligible articles were analyzed, resulting in the retrieval of 1643 flavonoid structures. These structures were rigorously standardized and curated, yielding 974 unique compounds, among which 177 flavonoids exhibited inhibition of both alpha-glucosidase and alpha-amylase are presented. Quality assessment utilizing a modified CONSORT checklist and structure-activity relationship (SAR) analysis were performed, revealing crucial features for the simultaneous inhibition of flavonoids against both enzymes. Moreover, the review also addressed several limitations in the current research landscape and proposed potential solutions. The curated datasets are available online at https://github.com/MedChemUMP/FDIGA.
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| 17. |
- Minh, Hoang Van, et al.
(author)
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Tobacco Control Policies in Vietnam : Review on MPOWER Implementation Progress and Challenges
- 2016
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In: Asian Pacific Journal of Cancer Prevention. - 1513-7368. ; 17, s. 1-9
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Journal article (peer-reviewed)abstract
- In Vietnam, the WHO Framework Convention on Tobacco Control (WHO FCTC) took effect in March 2005 while MPOWER has been implemented since 2008. This paper describes the progress and challenges of implementation of the MPOWER package in Vietnam. We can report that, in term of monitoring, Vietnam is very active in the Global Tobacco Surveillance System, completing two rounds of the Global Adult Tobacco Survey (GATS) and three rounds of the Global Youth Tobacco Survey (GYTS). To protect people from tobacco smoke, Vietnam has issued and enforced a law requiring comprehensive smoking bans at workplaces and public places since 2013. Tobacco advertising and promotion are also prohibited with the exception of points of sale displays of tobacco products. Violations come in the form of promotion girls, corporate social responsibility activities from tobacco manufacturers and packages displayed by retail vendors. Vietnam is one of the 77 countries that require pictorial health warnings to be printed on cigarette packages to warn about the danger of tobacco and the warnings have been implemented effectively. Cigarette tax is 70% of factory price which is equal to less than 45% of retail price and much lower than the recommendation of WHO. However, Vietnam is one of the very few countries that require manufacturers and importers to make "compulsory contributions" at 1-2% of the factory price of cigarettes sold in Vietnam for the establishment of a Tobacco Control Fund (TCF). The TCF is being operated well. In 2015, 67 units of 63 provinces/cities, 22 ministries and political-social organizations and 6 hospitals received funding from TCF to implement a wide range of tobacco control activities. Cessation services have been starting with a a toll-free quit-line but need to be further strengthened. In conclusion, Vietnam has constantly put efforts into the tobacco control field with high commitment from the government, scientists and activists. Though several remarkable achievements have been gained, many challenges remain. To overcome those challenges, implementation strategies that take into account the contextual factors and social determinants of tobacco use in Vietnam are needed.
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| 18. |
- Nguyen, Thanh N, et al.
(author)
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Global Impact of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events: A 1-Year Follow-up.
- 2023
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In: Neurology. - 1526-632X. ; 100:4
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Journal article (peer-reviewed)abstract
- Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020).We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, IVT treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.There were 148,895 stroke admissions in the 1 year immediately before compared with 138,453 admissions during the 1-year pandemic, representing a 7% decline (95% CI [95% CI 7.1-6.9]; p < 0.0001). ICH volumes declined from 29,585 to 28,156 (4.8% [5.1-4.6]; p < 0.0001) and IVT volume from 24,584 to 23,077 (6.1% [6.4-5.8]; p < 0.0001). Larger declines were observed at high-volume compared with low-volume centers (all p < 0.0001). There was no significant change in mechanical thrombectomy volumes (0.7% [0.6-0.9]; p = 0.49). Stroke was diagnosed in 1.3% [1.31-1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82-2.97], 5,656/195,539) of all stroke hospitalizations.There was a global decline and shift to lower-volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared with the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year.This study is registered under NCT04934020.
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| 19. |
- Pham, Thi Anh Mai, et al.
(author)
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Evaluation of screening algorithms to detect rectal colonization with carbapenemase-producing Enterobacterales in a resource-limited setting
- 2024
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In: JAC - Antimicrobial Resistance. - : OXFORD UNIV PRESS. - 2632-1823. ; 6:3
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Journal article (peer-reviewed)abstract
- Objectives To improve and rationalize the detection of carbapenemase-producing Enterobacterales (CPE) in rectal swabs in a high-prevalence and resource-constrained setting, addressing surveillance challenges typically encountered in laboratories with limited resources.Methods A point prevalence survey (PPS) was conducted on 15 August 2022, in a provincial children's hospital in northern Vietnam. Rectal swab samples of all admitted children were collected and plated on a selective medium for carbapenem-resistant Enterobacterales (CRE). Species identification and antimicrobial susceptibility testing (AST) were performed by MALDI-TOF, and VITEK2 XL and interpreted according to CLSI breakpoints (2022). Carbapenemases were detected by the carbapenem inactivation method (CIM) and quantitative real-time PCR (qRT-PCR).Results Rectal swab samples were obtained from 376 patients. Of 178 isolates growing on the CRE screening agar, 140 isolates were confirmed as Enterobacterales of which 118 (84.3%) isolates were resistant to meropenem and/or ertapenem. CIM and PCR showed that 90/118 (76.3%) were carbapenemase producers. Overall, 83/367 (22.6%) were colonized by CPE. Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae complex were the most common CPE detected, with NDM as the predominant carbapenemase (78/90; 86.7%). Phenotypic resistance to meropenem was the best predictor of CPE production (sensitivity 85.6%, specificity 100%) compared with ertapenem resistance (95.6% sensitivity, 36% specificity). CIM was 100% concordant with PCR in detecting carbapenemases.Conclusions These findings underscore the effectiveness of meropenem resistance as a robust indicator of the production of carbapenemases and the reliability of the CIM method to detect such carbapenemases in resource-limited settings where the performance of molecular methods is not possible.
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| 20. |
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| 21. |
- Ahmad, Amais, et al.
(author)
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IMI – Oral biopharmaceutics tools project – Evaluation of bottom-up PBPK prediction success part 4 : Prediction accuracy and software comparisons with improved data and modelling strategies
- 2020
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In: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 156, s. 50-63
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Journal article (peer-reviewed)abstract
- Oral drug absorption is a complex process depending on many factors, including the physicochemical properties of the drug, formulation characteristics and their interplay with gastrointestinal physiology and biology. Physiological-based pharmacokinetic (PBPK) models integrate all available information on gastro-intestinal system with drug and formulation data to predict oral drug absorption. The latter together with in vitro-in vivo extrapolation and other preclinical data on drug disposition can be used to predict plasma concentration-time profiles in silico. Despite recent successes of PBPK in many areas of drug development, an improvement in their utility for evaluating oral absorption is much needed. Current status of predictive performance, within the confinement of commonly available in vitro data on drugs and formulations alongside systems information, were tested using 3 PBPK software packages (GI-Sim (ver.4.1), Simcyp® Simulator (ver.15.0.86.0), and GastroPlusTM (ver.9.0.00xx)). This was part of the Innovative Medicines Initiative (IMI) Oral Biopharmaceutics Tools (OrBiTo) project.Fifty eight active pharmaceutical ingredients (APIs) were qualified from the OrBiTo database to be part of the investigation based on a priori set criteria on availability of minimum necessary information to allow modelling exercise. The set entailed over 200 human clinical studies with over 700 study arms. These were simulated using input parameters which had been harmonised by a panel of experts across different software packages prior to conduct of any simulation. Overall prediction performance and software packages comparison were evaluated based on performance indicators (Fold error (FE), Average fold error (AFE) and absolute average fold error (AAFE)) of pharmacokinetic (PK) parameters.On average, PK parameters (Area Under the Concentration-time curve (AUC0-tlast), Maximal concentration (Cmax), half-life (t1/2)) were predicted with AFE values between 1.11 and 1.97. Variability in FEs of these PK parameters was relatively high with AAFE values ranging from 2.08 to 2.74. Around half of the simulations were within the 2-fold error for AUC0-tlast and around 90% of the simulations were within 10-fold error for AUC0-tlast. Oral bioavailability (Foral) predictions, which were limited to 19 APIs having intravenous (i.v.) human data, showed AFE and AAFE of values 1.37 and 1.75 respectively. Across different APIs, AFE of AUC0-tlast predictions were between 0.22 and 22.76 with 70% of the APIs showing an AFE > 1. When compared across different formulations and routes of administration, AUC0-tlast for oral controlled release and i.v. administration were better predicted than that for oral immediate release formulations. Average predictive performance did not clearly differ between software packages but some APIs showed a high level of variability in predictive performance across different software packages. This variability could be related to several factors such as compound specific properties, the quality and availability of information, and errors in scaling from in vitro and preclinical in vivo data to human in vivo behaviour which will be explored further. Results were compared with previous similar exercise when the input data selection was carried by the modeller rather than a panel of experts on each in vitro test. Overall, average predictive performance was increased as reflected in smaller AAFE value of 2.8 as compared to AAFE value of 3.8 in case of previous exercise.
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| 22. |
- Le, Ha Vu, et al.
(author)
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Bacterial Cellulose Aerogels Derived from Pineapple Peel Waste for the Adsorption of Dyes
- 2023
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In: ACS Omega. - 2470-1343. ; 8:37, s. 33098-34195
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Journal article (peer-reviewed)abstract
- Valorization of pineapple peel waste is an attractive research topic because of the huge quantities of this byproduct generated from pineapple processing industries. In this study, the extract from pineapple waste was collected to produce a hydrogel-like form containing bacterial cellulose fibers with a three-dimensional structure and nanoscale diameter by the Acetobacter xylinum fermentation process. The bacterial cellulose suspension was subsequently activated by freeze-drying, affording lightweight aerogels as potential adsorbents in wastewater treatment, in particular the adsorptive removal of organic dyes. Intensive tests were carried out with the adsorption of methylene blue, a typical cationic dye, to investigate the influence of adsorption conditions (temperature, pH, initial dye concentration, time, and experiment scale) and aerogel-preparation parameters (grinding time and bacterial cellulose concentration). The bacterial cellulose-based aerogels exhibited high adsorption capacity not only for methylene blue but also for other cationic dyes, including malachite green, rhodamine B, and crystal violet (28-49 mg/g). However, its activity was limited for most of the anionic dyes, such as methyl orange, sunset yellow, and quinoline yellow, due to the repulsion of these anionic dyes with the aerogel surface, except for the case of congo red. It is also an anionic dye but has two amine groups providing a strong interaction with the hydroxyl group of the aerogel via hydrogen bonding. Indeed, the aerogel has a substantially large congo red-trapping capacity of 101 mg/g. Notably, the adsorption process exhibited similar performances, upscaling the solution volume to 50 times. The utilization of abundant agricultural waste in the simple aerogel preparation to produce a highly efficient and biodegradable adsorbent is the highlight of this work.
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| 23. |
- Nguyen, Anh Mai, et al.
(author)
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Sizeable Macroporous Monolithic Polyamide Entities Prepared in Closed Molds by Thermally Mediated Dissolution and Phase Segregation
- 2008
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In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 20:19, s. 6244-6247
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Journal article (peer-reviewed)abstract
- A simple method is presented for the preparation of macroporous monoliths from an aliphatic polyamide in closed molds, based on swelling/dissolution in benzyl alcohol at elevated temperature, followed by precipitation into a continuous monolithic structure by cooling the solution below the upper critical solution temperature. Subsequent removal of the solvent led to the formation of rigid macroporous nylon monoliths with a continuous and evenly spaced macropore system. The intended use is as supports for flow-through systems, where efficient mass transport at low flow resistance is the key optimization criterion.
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| 24. |
- Svahnberg, Mikael, et al.
(author)
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Uni-REPM : Validated and Improved
- 2013
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In: Requirements Engineering. - : Springer. - 0947-3602 .- 1432-010X. ; 18:1, s. 85-103
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Journal article (peer-reviewed)abstract
- Software products are usually developed for either a specific customer (bespoke) or a broader market (market-driven). Due to their characteristic, bespoke and market-driven development face different challenges, especially concerning requirements engineering. Many challenges are caused by an inadequate requirements engineering process, and hence there is a need for process improvement frameworks based on empirical research and industry needs. In a previous article we introduced Uni-REPM, a lightweight requirements engineering process assessment framework based on a review of empirically motivated practices in market-driven and bespoke requirements engineering literature. In this article, we validate this framework in academia as well as industry, in order to prepare Uni-REPM for widespread industry use. We conduct two validations; a static validation based on interviews with seven academic experts and a dynamic validation where Uni-REPM is applied in four industrial organisations. Uni-REPM is refined according to the feedback obtained in the validations. The study shows that Uni-REPM is a quick, simple, and cost-effective solution to assess the maturity level of the requirements engineering process of projects. Moreover, the assessment method using checklists is highly usable and applicable in various international development environments.
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| 25. |
- Svahnberg, Mikael, et al.
(author)
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Uni-REPM : a framework for requirements engineering process assessment
- 2015
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In: Requirements Engineering. - : Springer. - 0947-3602 .- 1432-010X. ; 20:1, s. 91-118
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Journal article (peer-reviewed)abstract
- It has been shown that potential business benefits could be achieved by assessing and improving the requirements engineering (RE) process. However, process assessment models such as CMMI and ISO9000 only cover RE shallowly. Tailored models such as REGPG and REPM, on the other hand, do not cover market-driven requirements engineering. Other attempts such as MDREPM covers market-driven requirements engineering, but correspondingly neglects bespoke requirements engineering. Moreover, the area itself has evolved so practices that once were cutting edge are now commonplace. In this article, we develop and evaluate a unified requirements engineering process maturity model (Uni-REPM) that can be used in a market-driven as well as a bespoke context. This model is based on REPM, but has evolved to reflect contemporary requirements engineering practices. Uni-REPM is primarily created based on a systematic literature review of market-driven requirements engineering practices and a literature review of bespoke practices. Based on the results, Uni-REPM is formulated. The objective of Uni-REPM is twofold. Firstly, it is expected to be applicable for assessing the maturity of RE processes in various scenarios where an organisation would use different development approaches. Secondly, it instructs practitioners about which RE practices to perform and their expected benefits. As an assessment instrument, Uni-REPM provides a simple and low-cost solution for practitioners to identify the status of their RE process. As a guidance tool, Uni-REPM lessens the gap between theoretical and practical worlds by transferring the available RE technologies from research to industry practice.
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| 26. |
- Thi Tuyet-Hanh, Tran, et al.
(author)
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Climate Variability and Dengue Hemorrhagic Fever in Hanoi, Viet Nam, During 2008 to 2015
- 2018
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In: Asia Pacific journal of public health. - : Sage Publications. - 1941-2479 .- 1010-5395. ; 30:6, s. 532-541
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Journal article (peer-reviewed)abstract
- Dengue fever/dengue hemorrhagic fever (DF/DHF) has been an important public health challenge in Viet Nam and worldwide. This study was implemented in 2016-2017 using retrospective secondary data to explore associations between monthly DF/DHF cases and climate variables during 2008 to 2015. There were 48 175 DF/DHF cases reported, and the highest number of cases occurred in November. There were significant correlations between monthly DF/DHF cases with monthly mean of evaporation (r = 0.236, P < .05), monthly relative humidity (r = −0.358, P < .05), and monthly total hours of sunshine (r = 0.389, P < .05). The results showed significant correlation in lag models but did not find direct correlations between monthly DF/DHF cases and monthly average rainfall and temperature. The study recommended that health staff in Hanoi should monitor DF/DHF cases at the beginning of epidemic period, starting from May, and apply timely prevention and intervention measures to avoid the spreading of the disease in the following months. A larger scale study for a longer period of time and adjusting for other potential influencing factors could better describe the correlations, modelling/projection, and developing an early warning system for the disease, which is important under the impacts of climate change and climate variability.
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| 27. |
- Tran, Minh Quan, et al.
(author)
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MPC-Based Coordinated Voltage Control in LV Distribution Systems: A Case Study in Chalmers Campus Network
- 2023
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In: Conference Proceedings - 2023 IEEE Asia Meeting on Environment and Electrical Engineering, EEE-AM 2023.
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Conference paper (peer-reviewed)abstract
- This paper presents detailed analysis results of a model predictive control (MPC)-based coordinated voltage control demonstrated in a real low voltage network, the Chalmers campus in Sweden. First, the modeling of the MPC is presented, and the state space mode is obtained by linearization of the power flow equation around the operation point. Thus, an updated voltage vector in the grid is calculated through the sensitivity gain corresponding to reactive power deviation in the grid. Second, the developed MPC model is integrated into an Internet of Things (IoT) platform developed under the European FlexiGrid project. The state measurements in the Chalmers campus network are collected through the IoT platform as the input for the MPC model. Then, the optimal setpoints for distributed energy resources (DERs) are calculated and sent to DERs via the IoT platform. Lastly, onsite demonstration results are analyzed, showing the performance of the MPC-based voltage control in low-voltage distribution systems.
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| 28. |
- Ali, Mai, et al.
(author)
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Autonomous Patient/Home Health Monitoring powered by Energy Harvesting
- 2017
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In: Globecom 2017 - 2017 IEEE Global Communications Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509050192
-
Conference paper (peer-reviewed)abstract
- This paper presents the design of an autonomous smart patient/home health monitoring system. Both patient physiological parameters as well as room conditions are being monitored continuously to insure patient safety. The sensors are connected on an IoT regime, where the collected data is wirelessly transferred to a nearby gateway which performs preliminary data analysis, commonly referred to as fog computing, to make sure emergency personnel and healthcare providers are notified in case patient being monitored is at risk. To achieve power autonomy three energy harvesting sources are proposed, namely, solar, RF and thermal. The design of the RF energy harvesting system is demonstrated, where novel multiband antenna is fabricated as well as an efficient RF-DC rectifier achieving maximum conversion efficiency of 84%. Finally, the sensor node is tested with different type of sensors and settings while being solely powered by a Photovoltaic (PV) solar cell.
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| 29. |
- Bui, Hue Thi Buu, et al.
(author)
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Microwave assisted synthesis and cytotoxic activity evaluations of new benzimidazole derivatives
- 2016
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In: Tetrahedron Letters. - : Elsevier. - 0040-4039 .- 1359-8562. ; 57:8, s. 887-891
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Journal article (peer-reviewed)abstract
- Twelve new 2-quinolizinylbenzimidazole and 2-naphthalylbenzimidazole derivatives with various 5- and 6-positioned substituents (aza, H, CH3, Cl, NO2, NH2, OCH3), have been synthesized in moderate to excellent yields via the condensation of 4-oxo-4H-quinolizinecarbaldehyde or naphthalenecarbaldehyde with substituted o-phenylenediamines, o-nitroaniline, and 2,3-pyridinediamine using sodium metabisulfite or sodium hydrosulfite under microwave irradiation. The new benzimidazole derivatives were screened for their cytotoxic activity against the human breast cancer cell line (MCF-7). The results showed on one hand that 2-(substituted quinolizinyl)-1H-benzimidazoles (12b–f) were less active (3–6 fold) than the positive control Tamoxifen (CC50 = 6.52 μM), and on the other hand, among the 2-(substituted naphthalyl)-1H-benzimidazoles series (13a–f), compounds 6,7,8-trimethoxy-3-(5-chloro-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13c) (CC50 = 7.48 μM) and 6,7,8-trimethoxy-3-(5-methoxy-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13f) (CC50 = 6.43 μM) were found to be as active as Tamoxifen.
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| 30. |
- Darwich, Adam S., et al.
(author)
-
IMI - Oral biopharmaceutics tools project - Evaluation of bottom-up PBPK prediction success part 3 : Identifying gaps in system parameters by analysing In Silico performance across different compound classes
- 2017
-
In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 626-642
-
Journal article (peer-reviewed)abstract
- Three Physiologically Based Pharmacokinetic software packages (GI-Sim, Simcyp (R) Simulator, and GastroPlus (TM)) were evaluated as part of the Innovative Medicine Initiative Oral Biopharmaceutics Tools project (OrBiTo) during a blinded "bottom-up" anticipation of human pharmacokinetics. After data analysis of the predicted vs. measured pharmacokinetics parameters, it was found that oral bioavailability (F-oral) was underpredicted for compounds with low permeability, suggesting improper estimates of intestinal surface area, colonic absorption and/or lack of intestinal transporter information. Foralwas also underpredicted for acidic compounds, suggesting overestimation of impact of ionisation on permeation, lack of information on intestinal transporters, or underestimation of solubilisation of weak acids due to less than optimal intestinal model pH settings or underestimation of bile micelle contribution. F-oral was overpredicted for weak bases, suggesting inadequate models for precipitation or lack of in vitro precipitation information to build informed models. Relative bioavailability was underpredicted for both high logP compounds as well as poorly water-soluble compounds, suggesting inadequate models for solubility/dissolution, underperforming bile enhancement models and/or lack of biorelevant solubility measurements. These results indicate areas for improvement in model software, modelling approaches, and generation of applicable input data. However, caution is required when interpreting the impact of drug-specific properties in this exercise, as the availability of input parameters was heterogeneous and highly variable, and the modellers generally used the data "as is" in this blinded bottom-up prediction approach.
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| 31. |
- Di Paolo, Carolina, et al.
(author)
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Bioassay battery interlaboratory investigation of emerging contaminants in spikedwater extracts : Towards the implementation of bioanalytical monitoring tools inwater quality assessment and monitoring
- 2016
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In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 104, s. 473-484
-
Journal article (peer-reviewed)abstract
- Bioassays are particularly useful tools to link the chemical and ecological assessments in water quality monitoring. Different methods cover a broad range of toxicity mechanisms in diverse organisms, and account for risks posed by non-target compounds and mixtures. Many tests are already applied in chemical and waste assessments, and stakeholders from the science-police interface have recommended their integration in regulatory water quality monitoring. Still, there is a need to address bioassay suitability to evaluate water samples containing emerging pollutants, which are a current priority in water quality monitoring. The presented interlaboratory study (ILS) verified whether a battery of miniaturized bioassays, conducted in 11 different laboratories following their own protocols, would produce comparable results when applied to evaluate blinded samples consisting of a pristine water extract spiked with four emerging pollutants as single chemicals or mixtures, i.e. triclosan, acridine, 17α-ethinylestradiol (EE2) and 3-nitrobenzanthrone (3-NBA). Assays evaluated effects on aquatic organisms from three different trophic levels (algae, daphnids, zebrafish embryos) and mechanism-specific effects using in vitro estrogenicity (ER-Luc, YES) and mutagenicity (Ames fluctuation) assays. The test battery presented complementary sensitivity and specificity to evaluate the different blinded water extract spikes. Aquatic organisms differed in terms of sensitivity to triclosan (algae > daphnids > fish) and acridine (fish > daphnids > algae) spikes, confirming the complementary role of the three taxa for water quality assessment. Estrogenicity and mutagenicity assays identified with high precision the respective mechanism-specific effects of spikes even when non-specific toxicity occurred in mixture. For estrogenicity, although differences were observed between assays and models, EE2 spike relative induction EC50 values were comparable to the literature, and E2/EE2 equivalency factors reliably reflected the sample content. In the Ames, strong revertant induction occurred following 3-NBA spike incubation with the TA98 strain, which was of lower magnitude after metabolic transformation and when compared to TA100. Differences in experimental protocols, model organisms, and data analysis can be sources of variation, indicating that respective harmonized standard procedures should be followed when implementing bioassays in water monitoring. Together with other ongoing activities for the validation of a basic bioassay battery, the present study is an important step towards the implementation of bioanalytical monitoring tools in water quality assessment and monitoring.
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| 32. |
- Dinh, Ngoc Phuoc, et al.
(author)
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Functionalization of epoxy-based monoliths for ion exchange chromatography of proteins
- 2009
-
In: Journal of Separation Science. - : Wiley InterScience. - 1615-9306. ; 32:15-16, s. 2556-2564
-
Journal article (peer-reviewed)abstract
- Macroporous epoxy-based monoliths prepared by emulsion polymerization have been modified for use in ion exchange chromatography (IEC) of proteins. Strong anion exchange functionality was established by iodomethane quaternization of tertiary amine present on the monolith surface as a part of the polymer backbone. The modification pathway to cation exchange materials was via incorporation of glycidyl methacrylate (GMA) brushes which were coated using atom transfer radical polymerization (ATRP). Strong (SO3-) and weak (COO-) cation exchange groups were thereafter introduced onto the GMA-grafted monoliths by reactions with sodium hydrogen sulfite and iminodiacetic acid, respectively. Grafting was confirmed by XPS, gravimetric measurement, and chromatographic behavior of the modified materials toward model proteins. In incubation experiments the proteins were recovered quantitatively with no obvious signs of unfolding after contact with the stationary phase for >2 h. Chromatographic assessments on the functionalized columns as well as problems associated with flow-through modification by ATRP are discussed.
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| 33. |
- Duong, Ngoc Son, et al.
(author)
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Sparse Bayesian Learning with Atom Refinement for mmWave MIMO Channel Estimation
- 2023
-
In: IEEE Workshop on Statistical Signal Processing Proceedings. ; 2023-July, s. 155-159
-
Conference paper (peer-reviewed)abstract
- In this paper, we introduce a novel estimation method for the downlink millimeter-wave (mmWave) multiple-input multiple-output (MIMO) channel. The proposed method is able to determine the angles, time delays, and gains of the multi-path components by using the spatially sparse nature of mmWave channels. We first use on-grid sparse Bayesian learning (SBL) to coarsely estimate the channel parameters in the beamspace domain. We then develop a refinement method based on Newton-Raphson and Least Square-based atomic tuning to generate a mismatch-free basis. Finally, we finely reconstruct the channel by SBL using the basis found in the previous step. Simulation results show that the proposed channel estimation method outperforms the traditional ones in terms of mean square error and algorithmic complexity.
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| 34. |
- Hakkaart, C, et al.
(author)
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Copy number variants as modifiers of breast cancer risk for BRCA1/BRCA2 pathogenic variant carriers
- 2022
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In: Communications biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 5:1, s. 1061-
-
Journal article (peer-reviewed)abstract
- The contribution of germline copy number variants (CNVs) to risk of developing cancer in individuals with pathogenic BRCA1 or BRCA2 variants remains relatively unknown. We conducted the largest genome-wide analysis of CNVs in 15,342 BRCA1 and 10,740 BRCA2 pathogenic variant carriers. We used these results to prioritise a candidate breast cancer risk-modifier gene for laboratory analysis and biological validation. Notably, the HR for deletions in BRCA1 suggested an elevated breast cancer risk estimate (hazard ratio (HR) = 1.21), 95% confidence interval (95% CI = 1.09–1.35) compared with non-CNV pathogenic variants. In contrast, deletions overlapping SULT1A1 suggested a decreased breast cancer risk (HR = 0.73, 95% CI 0.59-0.91) in BRCA1 pathogenic variant carriers. Functional analyses of SULT1A1 showed that reduced mRNA expression in pathogenic BRCA1 variant cells was associated with reduced cellular proliferation and reduced DNA damage after treatment with DNA damaging agents. These data provide evidence that deleterious variants in BRCA1 plus SULT1A1 deletions contribute to variable breast cancer risk in BRCA1 carriers.
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| 35. |
- Iashchishyn, Igor A., et al.
(author)
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Finke-Watzky Two-Step Nucleation-Autocatalysis Model of S100A9 Amyloid Formation : Protein Misfolding as "Nucleation" Event
- 2017
-
In: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 8:10, s. 2152-2158
-
Journal article (peer-reviewed)abstract
- Quantitative kinetic analysis is critical for understanding amyloid mechanisms. Here we demonstrate the application of generic Finke-Watzky (F-W) two-step nucleation-autocatalytic growth model to the concentration-dependent amyloid kinetics of proinflammatory alpha-helical S100A9 protein at pH 7.4 and at 37 and 42 degrees C. The model is based on two pseudoelementary reaction steps applied without further analytical constraints, and its treatment of S100A9 amyloid self-assembly demonstrates that initial misfolding and beta-sheet formation, defined as "nucleation" step, spontaneously takes place within individual S100A9 molecules at higher rate than the subsequent fibrillar growth. The latter, described as an autocatalytic process, will proceed if misfolded amyloid-prone S100A9 is populated on a macroscopic time scale. Short lengths of S100A9 fibrils are consistent with the F-W model. The analysis of fibrillar length distribution by the Beker-Doring model demonstrates independently that such distribution is solely determined by slow fibril growth and there is no fragmentation or secondary pathways decreasing fibrillar length.
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| 36. |
- Johnstone, Devon L., et al.
(author)
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Early infantile epileptic encephalopathy due to biallelic pathogenic variants in PIGQ : Report of seven new subjects and review of the literature
- 2020
-
In: Journal of Inherited Metabolic Disease. - : Wiley. - 0141-8955 .- 1573-2665. ; 43:6, s. 1321-1332
-
Journal article (peer-reviewed)abstract
- We investigated seven children from six families to expand the phenotypic spectrum associated with an early infantile epileptic encephalopathy caused by biallelic pathogenic variants in the phosphatidylinositol glycan anchor biosynthesis class Q (PIGQ) gene. The affected children were all identified by clinical or research exome sequencing. Clinical data, including EEGs and MRIs, was comprehensively reviewed and flow cytometry and transfection experiments were performed to investigate PIGQ function. Pathogenic biallelic PIGQ variants were associated with increased mortality. Epileptic seizures, axial hypotonia, developmental delay and multiple congenital anomalies were consistently observed. Seizure onset occurred between 2.5 months and 7 months of age and varied from treatable seizures to recurrent episodes of status epilepticus. Gastrointestinal issues were common and severe, two affected individuals had midgut volvulus requiring surgical correction. Cardiac anomalies including arrythmias were observed. Flow cytometry using granulocytes and fibroblasts from affected individuals showed reduced expression of glycosylphosphatidylinositol (GPI)-anchored proteins. Transfection of wildtype PIGQ cDNA into patient fibroblasts rescued this phenotype. We expand the phenotypic spectrum of PIGQ-related disease and provide the first functional evidence in human cells of defective GPI-anchoring due to pathogenic variants in PIGQ.
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| 37. |
- Kien, Tran Mai, et al.
(author)
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Climate Services For Infectious Disease Control: A Nexus Between Public Health Preparedness and Sustainable Development, Lessons Learned From Long-Term Multi Site Time Series Analysis of Dengue Fever in Vietnam
- 2016
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In: International conference on public health: Accelerating the achievement of sustainable development goals for the improvement and equitable distribution of population health. ; , s. 83-84
-
Conference paper (other academic/artistic)abstract
- Background: Climate Services provide valuable information for making actionable, data-driven decisions to protect public health in a myriad of manners. There is mounting global evidence of the looming threat climate change poses to human health, including the variability and intensity of infectious disease outbreaks in Vietnam and other low-resource and developing areas. In light of the Sustainable Development Goals, lessons learned from time-series analysis may inform public health preparedness strategies for sustainable urban development in terms of dengue epidemiology, surveillance, control, and early warnings.Subjects and Methods: Nearly 40 years of spatial and temporal (times-series) dataset of meteorological records, including rainfall, temperature, and humidity (among others) which can be predictors of dengue were assembled for all provinces of Vietnam and associated with case data reported to General Department of Preventive Medicine, Ministry of Health of Vietnam during the same period. Time series of climate and disease variables was analyzed for trends and changing patterns of those variables over time. The time-series statistical analysis methods sought to identify spatial (when possible) and temporal trends, seasonality, cyclical patterns of disease, and to discover anomalous outbreak events, which departed from expected epidemiological patterns and corresponding meteorological phenomena, such as El Nino Southern Oscillation (ENSO).Results: Analysis yielded largely conserved finding with other locations in South East Asia for larger Outbreak years and events such as ENSO. Seasonality, trend, and cycle in many provinces were persistent throughout the dataset, indicating strong potential for Climate Services to be used in dengue early warnings.Conclusion: Even public health practitioners, having adequate tools for dengue control available must plan and budget vector control and patient treatment efforts well in advance of large scale dengue epidemics to curb such events overall morbidity and mortality. Similarly, urban and sustainable development in Vietnam might benefit from evidence linking climate change, and ill-health events spatially and temporally in future planning. Long term analysis of dengue case data and meteorological records, provided a cases study evidence for emerging opportunities that on how refined climate services could contribute to protection of public health.
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| 38. |
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| 39. |
- Mai, Tam T., et al.
(author)
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An overview of grid-edge control with the digital transformation
- 2021
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In: Electrical Engineering. - : Springer Science and Business Media LLC. - 1432-0487 .- 0948-7921. ; 103:4, s. 1989-2007
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Journal article (peer-reviewed)abstract
- Distribution networks are evolving to become more responsive with increasing integration of distributed energy resources (DERs) and digital transformation at the grid edges. This evolution imposes many challenges to the operation of the network, which then calls for new control and operation paradigms. Among others, a so-called grid-edge control is emerging to harmonise the coexistence of the grid control system and DER’s autonomous control. This paper provides a comprehensive overview of the grid-edge control with various control architectures, layers, and strategies. The challenges and opportunities for such an approach at the grid edge with the integration of DERs and digital transformation are summarised. The potential solutions to support the network operation by using the inherent controllability of DER and the availability of the digital transformation at the grid edges are discussed.
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| 40. |
- Manni, Giovanni Li, et al.
(author)
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The OpenMolcas Web : A Community-Driven Approach to Advancing Computational Chemistry
- 2023
-
In: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 19:20, s. 6933-6991
-
Journal article (peer-reviewed)abstract
- The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations.
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| 41. |
- Margolskee, Alison, et al.
(author)
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IMI - Oral biopharmaceutics tools project - Evaluation of bottom-up PBPK prediction success part 2 : An introduction to the simulation exercise and overview of results
- 2017
-
In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 610-625
-
Journal article (peer-reviewed)abstract
- Orally administered drugs are subject to a number of barriers impacting bioavailability (F-oral), causing challenges during drug and formulation development. Physiologically-based pharmacokinetic (PBPK) modelling can help during drug and formulation development by providing quantitative predictions through a systems approach. The performance of three available PBPK software packages (GI-Sim, Simcyp (R), and GastroPlus (TM)) were evaluated by comparing simulated and observed pharmacokinetic (PK) parameters. Since the availability of input parameters was heterogeneous and highly variable, caution is required when interpreting the results of this exercise. Additionally, this prospective simulation exercise may not be representative of prospective modelling in industry, as API information was limited to sparse details. 43 active pharmaceutical ingredients (APIs) from the OrBiTo database were selected for the exercise. Over 4000 simulation output files were generated, representing over 2550 study arm-institution-software combinations and approximately 600 human clinical study arms simulated with overlap. 84% of the simulated study arms represented administration of immediate release formulations, 11% prolonged or delayed release, and 5% intravenous (i.v.). Higher percentages of i.v. predicted area under the curve (AUC) were within two-fold of observed (52.9%) compared to per oral (p.o.) (37.2%), however, F-oral and relative AUC (F-rel) between p.o. formulations and solutions were generally well predicted (64.7% and 75.0%). Predictive performance declined progressing from i.v. to solution and immediate release tablet, indicating the compounding error with each layer of complexity. Overall performance was comparable to previous large-scale evaluations. A general overprediction of AUC was observed with average fold error (AFE) of 1.56 over all simulations. AFE ranged from 0.0361 to 64.0 across the 43 APIs, with 25 showing overpredictions. Discrepancies between software packages were observed for a few APIs, the largest being 606, 171, and 81.7-fold differences in AFE between SimCYP and GI-Sim, however average performance was relatively consistent across the three software platforms.
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| 42. |
- Ngo, Son Tung, et al.
(author)
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Distal Hydrophobic Loop Modulates the Copper Active Site and Reaction of AA13 Polysaccharide Monooxygenases
- 2022
-
In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 126:39, s. 7567-7578
-
Journal article (peer-reviewed)abstract
- Polysaccharide monooxygenases (PMOs) use a type-2 copper center to activate O2 for the selective hydroxylation of one of the two C-H bonds of glycosidic linkages. Our electron paramagnetic resonance (EPR) analysis and molecular dynamics (MD) simulations suggest the unprecedented dynamic roles of the loop containing the residue G89 (G89 loop) on the active site structure and reaction cycle of starch-active PMOs (AA13 PMOs). In the Cu(II) state, the G89 loop could switch between an open and closed conformation, which is associated with the binding and dissociation of an aqueous ligand in the distal site, respectively. The conformation of the G89 loop influences the positioning of the copper center on the preferred substrate of AA13 PMOs. The dissociation of the distal ligand results in the bending of the T-shaped core of the Cu(II) active site, which could help facilitate its reduction to the active Cu(I) state. In the Cu(I) state, the G89 loop is in the closed conformation with a confined copper center, which could allow for efficient O2 binding. In addition, the G89 loop remains in the closed conformation in the Cu(II)-superoxo intermediate, which could prevent off-pathway superoxide release via exchange with the distal aqueous ligand. Finally, at the end of the reaction cycle, aqueous ligand binding to the distal site could switch the G89 loop to the open conformation and facilitate product release.
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| 43. |
- Nguyen, Anh Mai, et al.
(author)
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Epoxy-Based Monoliths. A Novel Hydrophilic Separation Material for Liquid Chromatography of Biomolecules
- 2006
-
In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 18:26, s. 6308-15
-
Journal article (peer-reviewed)abstract
- In our efforts to develop novel hydrophilic monolithic porous materials for use as supports in liquid chromatographic separation of proteins, polymers based on epoxy monomers and diamines as curing agents were synthesized. The epoxy dispersed phase was emulsified in an aqueous phase containing the amine with the aid of a nonionic polymeric surfactant, and the resulting emulsions were thermally polymerized. Various factors, namely, the type of epoxy component, levels of reactants, type and concentration of diluents, and curing procedures, were studied to obtain suitable morphology and adequate mechanical properties for their intended use. Characterization of their morphologies and porous properties was done using scanning electron microscopy, nitrogen adsorption/desorption measurement (BET method), mercury intrusion porosimetry, and X-ray photoelectron spectroscopy.
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| 44. |
- Nguyen, Anh Mai, 1960-
(author)
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New approaches to preparation of macroporous monoliths for use in liquid chromatography
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- High performance liquid chromatography (HPLC) is one of the major techniques in separat-ion sciences. Faster separation and higher efficiency are required to meet ever-growing demands. Despite numerous studies and achievements on improving mass transfer in particulate packings discontinuity seems to be the cornerstone drawback in their development. Macroporous continuous beds or monoliths are therefore a promising alternative to the particle medium. This thesis deals with preparation of new monoliths used as carrier for HPLC. Two different approaches were developed for two polymer systems. One was based on polycondensation of epoxy resins and polyamines which were components of an oil-in-water emulsion. An epoxy resin mixture was dispersed in aqueous polyamine phase with the aid of a surfactant. The other involved a traverse of a ready-made polymer solution around its upper critical solution temperature (UCST). In other words, linear polyamides, non-covalently crosslinked polymers, dissolved in a solvent at temperature higher than their UCST followed by slow cooling to below the critical temperature to precipitate the polymers. Partly re-established hydrogen bonds resulted in the formation of crystallites that interconnected into a network structure. Factors controlling morphology and porosity of final products were investigated. The study also deals with surface modifying for chromatographic applications. Functionalization pathways attempted in the thesis were quaterization of inherent amine of the epoxy-based monoliths and grafting tentacle ion groups via glycidyl methacrylate by atom transfer radical polymerization (ATRP) for ion exchange chromatography (IEC).
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| 45. |
- Nguyen, Anh Mai, et al.
(author)
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Preparation and characterization of sizable macroporous epoxy resin-based monolithic supports for flow-through systems
- 2009
-
In: Journal of Separation Science. - : Wiley InterScience. - 1615-9306 .- 1615-9314. ; 32:15-16, s. 2608-2618
-
Journal article (peer-reviewed)abstract
- This paper presents further results from our efforts to prepare sizable macroporous monolithic materials from epoxy resins and polyamines by emulsion polymerization. For their uses as supports in flow systems, the study aimed at developing materials possessing maximum fluid permeability, high mechanical stability, and a controlled porosity and surface area. Characterization of the materials has been carried out using different techniques, focusing on morphological and mechanical features, and on the surface chemistry. Morphology and porosity were studied with SEM, nitrogen adsorption/desorption, mercury intrusion porosimetry (MIP), and (2)H NMR cryoporosimetry. The chemical composition of the bulk structures and their surfaces was studied by means of bulk elemental analysis and X-ray photoelectron spectroscopy, and potentiometric titration was used to assess the relative amounts of amines and epoxy groups. Essentially, the morphological features were a high fluid permeability, but rather low specific surface area. Convective flow was facilitated by large, interconnected, and evenly spaced macropores which were formed by nonporous skeletons of the connected-rod type. Despite the interfacial nature of the polymerization, the bulk and the surface of the fully cured materials showed similar elemental compositions. All materials were found to have a high surface density of hydroxyl groups, which facilitates functionalization reactions.
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| 46. |
- Nguyen, Anh Mai, et al.
(author)
-
Thermally induced dissolution/precipitation : A simple approach for the preparation of Macroporous Monoliths from Linear Aliphatic Polyamides
- 2009
-
In: Journal of Separation Science. - : Wiley InterScience. - 1615-9306 .- 1615-9314. ; 32:15-16, s. 2619-2628
-
Journal article (peer-reviewed)abstract
- A versatile way of preparing macroporous monolithic materials from linear aliphatic polyamides is presented. Simply, polyamide pellets were treated in benzyl alcohol (BA) at elevated temperature, causing dissolution by interchain hydrogen bond disruption. Subsequent cooling below the upper critical solution temperature (UCST) resulted in precipitation and partial restoration of the semicrystalline polymer, which is organized into network structures. The final steps were a solvent exchange of BA for methanol, followed by drying to form monolithic entities. A number of polyamides ranging from hydrophilic to hydrophobic were tested and under the experimental conditions, poly(1-aza-2-cycloheptanone (PA6) and (poly-[imino-1,6-hexanediylimino{1,10-dioxo-1,10-decanediyl}] (PA610) yielded entities with macroporous properties that were deemed useful for liquid chromatography. The morphological features and porous properties of the monoliths produced by this dissolution-precipitation procedure were studied by scanning electron microscopy, adsorption/desorption of N2(g) according to the Brunauer-Emmett-Teller (BET) principle, and mercury intrusion porosimetry. Degradation of the polymer backbone was noticeable when the dissolution time was extended and shortening of the polymer chains was confirmed by MALDI-MS, viscosity measurements, X-ray photoelectron spectroscopy (XPS), and potentiometric titration. When the heating was limited to the time it took to dissolve the polymers, mechanically stable monoliths could be obtained. The dissolution/heat treatment time further seemed to be useful for controlling the macroporous morphology.
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| 47. |
- Nguyen, Tho D. K., et al.
(author)
-
Visualization of Partial Exocytotic Content Release and Chemical Transport into Nanovesicles in Cells
- 2022
-
In: Acs Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:3, s. 4831-4842
-
Journal article (peer-reviewed)abstract
- For decades, "all-or-none"and "kiss-and-run"were thought to be the only major exocytotic release modes in cell-to-cell communication, while the significance of partial release has not yet been widely recognized and accepted owing to the lack of direct evidence for exocytotic partial release. Correlative imaging with transmission electron microscopy and NanoSIMS imaging and a dual stable isotope labeling approach was used to study the cargo status of vesicles before and after exocytosis; demonstrating a measurable loss of transmitter in individual vesicles following stimulation due to partial release. Model secretory cells were incubated with 13C-labeled l-3,4-dihydroxyphenylalanine, resulting in the loading of 13C-labeled dopamine into their vesicles. A second label, di-N-desethylamiodarone, having the stable isotope 127I, was introduced during stimulation. A significant drop in the level of 13C-labeled dopamine and a reduction in vesicle size, with an increasing level of 127I-, was observed in vesicles of stimulated cells. Colocalization of 13C and 127I- in several vesicles was observed after stimulation. Thus, chemical visualization shows transient opening of vesicles to the exterior of the cell without full release the dopamine cargo. We present a direct calculation for the fraction of neurotransmitter release from combined imaging data. The average vesicular release is 60% of the total catecholamine. An important observation is that extracellular molecules can be introduced to cells during the partial exocytotic release process. This nonendocytic transport process appears to be a general route of entry that might be exploited pharmacologically. © 2022 The Authors. Published by American Chemical Society.
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| 48. |
- Nguyen, Tram Mai, et al.
(author)
-
Stretch increases alveolar type 1 cell number in fetal lungs through ROCK-Yap/Taz pathway
- 2021
-
In: American journal of physiology. Lung cellular and molecular physiology. - : American Physiological Society. - 1522-1504 .- 1040-0605. ; 321:5, s. 814-826
-
Journal article (peer-reviewed)abstract
- Accurate fluid pressure in the fetal lung is critical for its development, especially at the beginning of the saccular stage when alveolar epithelial type 1 (AT1) and type 2 (AT2) cells differentiate from the epithelial progenitors. Despite our growing understanding of the role of physical forces in lung development, the molecular mechanisms that regulate the transduction of mechanical stretch to alveolar differentiation remain elusive. To simulate lung distension, we optimized both an ex vivo model with precision cut lung slices and an in vivo model of fetal tracheal occlusion. Increased mechanical tension showed to improve alveolar maturation and differentiation toward AT1. By manipulating ROCK pathway, we demonstrate that stretch-induced Yap/Taz activation promotes alveolar differentiation toward AT1 phenotype via ROCK activity. Our findings show that balanced ROCK-Yap/Taz signaling is essential to regulate AT1 differentiation in response to mechanical stretching of the fetal lung, which might be helpful in improving lung development and regeneration.
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| 49. |
- Nguyen, Tram Mai, et al.
(author)
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The proportion of alveolar type 1 cells decreases in murine hypoplastic congenital diaphragmatic hernia lungs
- 2019
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:4
-
Journal article (peer-reviewed)abstract
- Background Pulmonary hypoplasia, characterized by incomplete alveolar development, remains a major cause of mortality and morbidity in congenital diaphragmatic hernia. Recently demonstrated to differentiate from a common bipotent progenitor during development, the two cell types that line the alveoli type 1 and type 2 alveolar cells have shown to alter their relative ratio in congenital diaphragmatic hernia lungs. Objective We used the nitrofen/bisdiamine mouse model to induce congenital diaphragmatic hernia and accurately assess the status of alveolar epithelial cell differentiation in relation to the common bipotent progenitors. Study design Pregnant Swiss mice were gavage-fed with nitrofen/bisdiamine or vehicle at embryonic day 8.5. The administered dose was optimized by assessing the survival, congenital diaphragmatic hernia and facial abnormality rates of the exposed mouse pups. NanoCT was performed on embryonic day 11.5 and 16.5 to assess the embryonic and early canalicular stages of lung development. At embryonic day 17.5 corresponding to late canalicular stage, congenital diaphragmatic hernia lungs were characterized by measuring the lung weight/ body weight ratio, morphometry, epithelial cell marker gene expression levels and alveolar cell type quantification. Results Nitrofen/bisdiamine associated congenital diaphragmatic hernia lungs showed delayed development, hypoplasia with morphologic immaturity and thickened alveolar walls. Expression levels of distal epithelial progenitor marker Id2 increased, alveolar type 1 cell markers Pdpn and Hopx decreased, while type 2 cell markers pro-SPC and Muc1 remained constant during the canalicular stage. The number of Pdpn + type 1 alveolar cells also decreased in congenital diaphragmatic hernia lungs. Conclusion The mouse nitrofen/bisdiamine model is a potential model allowing the study of congenital diaphragmatic hernia lung development from early stages using a wide array of methods. Based on this model, the alveolar epithelium showed a decrease in the number of alveolar type 1 cell in congenital diaphragmatic hernia lungs while type 2 cell population remains unchanged.
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| 50. |
- Nguyen, Xuan Nhat Chi Mai, et al.
(author)
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English in Vietnam
- 2023
-
In: The Wiley Blackwell Encyclopedia of World Englishes. - Oxford : Wiley-Blackwell. - 9781119518310
-
Book chapter (peer-reviewed)
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