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| 3. |
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- 2019
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Journal article (peer-reviewed)
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| 4. |
- Franceschini, N., et al.
(author)
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GWAS and colocalization analyses implicate carotid intima-media thickness and carotid plaque loci in cardiovascular outcomes
- 2018
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1
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Journal article (peer-reviewed)abstract
- Carotid artery intima media thickness (cIMT) and carotid plaque are measures of subclinical atherosclerosis associated with ischemic stroke and coronary heart disease (CHD). Here, we undertake meta-analyses of genome-wide association studies (GWAS) in 71,128 individuals for cIMT, and 48,434 individuals for carotid plaque traits. We identify eight novel susceptibility loci for cIMT, one independent association at the previously-identified PINX1 locus, and one novel locus for carotid plaque. Colocalization analysis with nearby vascular expression quantitative loci (cis-eQTLs) derived from arterial wall and metabolic tissues obtained from patients with CHD identifies candidate genes at two potentially additional loci, ADAMTS9 and LOXL4. LD score regression reveals significant genetic correlations between cIMT and plaque traits, and both cIMT and plaque with CHD, any stroke subtype and ischemic stroke. Our study provides insights into genes and tissue-specific regulatory mechanisms linking atherosclerosis both to its functional genomic origins and its clinical consequences in humans. © 2018, The Author(s).
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| 5. |
- Ariyawansa, Hiran A., et al.
(author)
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Fungal diversity notes 111–252—taxonomic and phylogenetic contributions to fungal taxa
- 2015
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In: Fungal diversity. - : Springer Science and Business Media LLC. - 1560-2745 .- 1878-9129. ; 75, s. 27-274
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Journal article (peer-reviewed)abstract
- This paper is a compilation of notes on 142 fungal taxa, including five new families, 20 new genera, and 100 new species, representing a wide taxonomic and geographic range. The new families, Ascocylindricaceae, Caryosporaceae and Wicklowiaceae (Ascomycota) are introduced based on their distinct lineages and unique morphology. The new Dothideomycete genera Pseudomassariosphaeria (Amniculicolaceae), Heracleicola, Neodidymella and P s e u d o m i c ros p h a e r i o p s i s ( D id y m e l l a c e a e ) , P s e u d o p i t h o m y c e s ( D i d y m o s p h a e r i a c e a e ) , Brunneoclavispora, Neolophiostoma and Sulcosporium (Halotthiaceae), Lophiohelichrysum (Lophiostomataceae), G a l l i i c o l a , Popul o c re s c e n t i a a nd Va g i c o l a (Phaeosphaeriaceae), Ascocylindrica (Ascocylindricaceae), E l o n g a t o p e d i c e l l a t a ( R o u s s o e l l a c e a e ) , Pseudoasteromassaria (Latoruaceae) and Pseudomonodictys (Macrodiplodiopsidaceae) are introduced. The newly described species of Dothideomycetes (Ascomycota) are Pseudomassariosphaeria bromicola (Amniculicolaceae), Flammeascoma lignicola (Anteagloniaceae), Ascocylindrica marina (Ascocylindricaceae) , Lembosia xyliae (Asterinaceae), Diplodia crataegicola and Diplodia galiicola ( B o t r yosphae r i a cea e ) , Caryospor a aquat i c a (Caryosporaceae), Heracleicola premilcurensis and Neodi dymell a thai landi cum (Didymellaceae) , Pseudopithomyces palmicola (Didymosphaeriaceae), Floricola viticola (Floricolaceae), Brunneoclavispora bambusae, Neolophiostoma pigmentatum and Sulcosporium thailandica (Halotthiaceae), Pseudoasteromassaria fagi (Latoruaceae), Keissleriella dactylidicola (Lentitheciaceae), Lophiohelichrysum helichrysi (Lophiostomataceae), Aquasubmersa japonica (Lophiotremataceae) , Pseudomonodictys tectonae (Macrodiplodiopsidaceae), Microthyrium buxicola and Tumidispora shoreae (Microthyriaceae), Alloleptosphaeria clematidis, Allophaeosphaer i a c y t i s i , Allophaeosphae r i a subcylindrospora, Dematiopleospora luzulae, Entodesmium artemisiae, Galiicola pseudophaeosphaeria, Loratospora(Basidiomycota) are introduced together with a new genus Neoantrodiella (Neoantrodiellaceae), here based on both morphology coupled with molecular data. In the class Agaricomycetes, Agaricus pseudolangei, Agaricus haematinus, Agaricus atrodiscus and Agaricus exilissimus (Agaricaceae) , Amanita m e l l e i a l b a , Amanita pseudosychnopyramis and Amanita subparvipantherina (Amanitaceae), Entoloma calabrum, Cora barbulata, Dictyonema gomezianum and Inocybe granulosa (Inocybaceae), Xerocomellus sarnarii (Boletaceae), Cantharellus eucalyptorum, Cantharellus nigrescens, Cantharellus tricolor and Cantharellus variabilicolor (Cantharellaceae), Cortinarius alboamarescens, Cortinarius brunneoalbus, Cortinarius ochroamarus, Cortinarius putorius and Cortinarius seidlii (Cortinariaceae), Hymenochaete micropora and Hymenochaete subporioides (Hymenochaetaceae), Xylodon ramicida (Schizoporaceae), Colospora andalasii (Polyporaceae), Russula guangxiensis and Russula hakkae (Russulaceae), Tremella dirinariae, Tremella graphidis and Tremella pyrenulae (Tremellaceae) are introduced. Four new combinations Neoantrodiella gypsea, Neoantrodiella thujae (Neoantrodiellaceae), Punctulariopsis cremeoalbida, Punctulariopsis efibulata (Punctulariaceae) are also introduced here for the division Basidiomycota. Furthermore Absidia caatinguensis, Absidia koreana and Gongronella koreana (Cunninghamellaceae), Mortierella pisiformis and Mortierella formosana (Mortierellaceae) are newly introduced in the Zygomycota, while Neocallimastix cameroonii and Piromyces irregularis (Neocallimastigaceae) ar e i n t roduced i n the Neocallimastigomycota. Reference specimens or changes in classification and notes are provided for Alternaria ethzedia, Cucurbitaria ephedricola, Austropleospora, Austropleospora archidendri, Byssosphaeria rhodomphala, Lophiostoma caulium, Pseudopithomyces maydicus, Massariosphaeria, Neomassariosphaeria and Pestalotiopsis montellica.
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| 6. |
- Chauhan, G., et al.
(author)
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Genetic and lifestyle risk factors for MRI-defined brain infarcts in a population-based setting
- 2019
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In: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 92:5
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Journal article (peer-reviewed)abstract
- ObjectiveTo explore genetic and lifestyle risk factors of MRI-defined brain infarcts (BI) in large population-based cohorts.MethodsWe performed meta-analyses of genome-wide association studies (GWAS) and examined associations of vascular risk factors and their genetic risk scores (GRS) with MRI-defined BI and a subset of BI, namely, small subcortical BI (SSBI), in 18 population-based cohorts (n = 20,949) from 5 ethnicities (3,726 with BI, 2,021 with SSBI). Top loci were followed up in 7 population-based cohorts (n = 6,862; 1,483 with BI, 630 with SBBI), and we tested associations with related phenotypes including ischemic stroke and pathologically defined BI.ResultsThe mean prevalence was 17.7% for BI and 10.5% for SSBI, steeply rising after age 65. Two loci showed genome-wide significant association with BI: FBN2, p = 1.77 x 10(-8); and LINC00539/ZDHHC20, p = 5.82 x 10(-9). Both have been associated with blood pressure (BP)-related phenotypes, but did not replicate in the smaller follow-up sample or show associations with related phenotypes. Age- and sex-adjusted associations with BI and SSBI were observed for BP traits (p value for BI, p([BI]) = 9.38 x 10(-25); p([SSBI]) = 5.23 x 10(-14) for hypertension), smoking (p([BI]) = 4.4 x 10(-10); p([SSBI]) = 1.2 x 10(-4)), diabetes (p([BI]) = 1.7 x 10(-8); p([SSBI]) = 2.8 x 10(-3)), previous cardiovascular disease (p([BI]) = 1.0 x 10(-18); p([SSBI]) = 2.3 x 10(-7)), stroke (p([BI]) = 3.9 x 10(-69); p([SSBI]) = 3.2 x 10(-24)), and MRI-defined white matter hyperintensity burden (p([BI]) = 1.43 x 10(-157); p([SSBI]) = 3.16 x 10(-106)), but not with body mass index or cholesterol. GRS of BP traits were associated with BI and SSBI (p 0.0022), without indication of directional pleiotropy.ConclusionIn this multiethnic GWAS meta-analysis, including over 20,000 population-based participants, we identified genetic risk loci for BI requiring validation once additional large datasets become available. High BP, including genetically determined, was the most significant modifiable, causal risk factor for BI.
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| 7. |
- Darwich, Adam S., et al.
(author)
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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
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In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 626-642
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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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| 8. |
- Li, Mengtian, 1989, et al.
(author)
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Sealing System Analysis of Rotary Piston Pump
- 2019
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In: IOP Conference Series: Materials Science and Engineering. - 1757-8981 .- 1757-899X. ; 520:1
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Conference paper (peer-reviewed)abstract
- Rotary piston pump is designed by the Wankel engine. The structure, working feature and sealing system of rotary piston pump are introduced. The mathematical model of the internal cylinder profile and the theoretical flow are obtained by analysing the structural characteristics of the new pump. The axial seal and face seal of the rotary piston pump and their structures are analysed. The force analysis of the sealing strip is carried out in various cases. It can be concluded from the analysis that, for axial sealing, the key parameters that affect seal strip wear are working pressure, rotate speed of the crankshaft and the friction coefficient between sealing strip and inner wall of the cylinder. For axial sealing, the force of the spring under the curved sealing strips, the size of the sealing rings and curved sealing strips and material of them are the key design parameters.
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| 9. |
- 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
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In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 610-625
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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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| 10. |
- Miller, V., et al.
(author)
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Availability, affordability, and consumption of fruits and vegetables in 18 countries across income levels: findings from the Prospective Urban Rural Epidemiology (PURE) study
- 2016
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In: Lancet Global Health. - : Elsevier BV. - 2214-109X. ; 4:10
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Journal article (peer-reviewed)abstract
- Background Several international guidelines recommend the consumption of two servings of fruits and three servings of vegetables per day, but their intake is thought to be low worldwide. We aimed to determine the extent to which such low intake is related to availability and affordability. Methods We assessed fruit and vegetable consumption using data from country-specific, validated semi-quantitative food frequency questionnaires in the Prospective Urban Rural Epidemiology (PURE) study, which enrolled participants from communities in 18 countries between Jan 1, 2003, and Dec 31, 2013. We documented household income data from participants in these communities; we also recorded the diversity and non-sale prices of fruits and vegetables from grocery stores and market places between Jan 1, 2009, and Dec 31, 2013. We determined the cost of fruits and vegetables relative to income per household member. Linear random effects models, adjusting for the clustering of households within communities, were used to assess mean fruit and vegetable intake by their relative cost. Findings Of 143 305 participants who reported plausible energy intake in the food frequency questionnaire, mean fruit and vegetable intake was 3.76 servings (95% CI 3.66-3.86) per day. Mean daily consumption was 2.14 servings (1.93-2.36) in low-income countries (LICs), 3.17 servings (2.99-3.35) in lower-middle-income countries (LMICs), 4.31 servings (4.09-4.53) in upper-middle-income countries (UMICs), and 5.42 servings (5.13-5.71) in high-income countries (HICs). In 130 402 participants who had household income data available, the cost of two servings of fruits and three servings of vegetables per day per individual accounted for 51.97% (95% CI 46.06-57.88) of household income in LICs, 18.10% (14.53-21.68) in LMICs, 15.87% (11.51-20.23) in UMICs, and 1.85% (-3.90 to 7.59) in HICs (p(trend) = 0.0001). In all regions, a higher percentage of income to meet the guidelines was required in rural areas than in urban areas (p<0.0001 for each pairwise comparison). Fruit and vegetable consumption among individuals decreased as the relative cost increased (p(trend) = 0.00040). Interpretation The consumption of fruit and vegetables is low worldwide, particularly in LICs, and this is associated with low aff ordability. Policies worldwide should enhance the availability and aff ordability of fruits and vegetables.
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| 11. |
- Naghavi, Mohsen, et al.
(author)
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Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013
- 2015
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In: The Lancet. - 1474-547X .- 0140-6736. ; 385:9963, s. 117-171
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Journal article (peer-reviewed)abstract
- Background Up-to-date evidence on levels and trends for age-sex-specifi c all-cause and cause-specifi c mortality is essential for the formation of global, regional, and national health policies. In the Global Burden of Disease Study 2013 (GBD 2013) we estimated yearly deaths for 188 countries between 1990, and 2013. We used the results to assess whether there is epidemiological convergence across countries. Methods We estimated age-sex-specifi c all-cause mortality using the GBD 2010 methods with some refinements to improve accuracy applied to an updated database of vital registration, survey, and census data. We generally estimated cause of death as in the GBD 2010. Key improvements included the addition of more recent vital registration data for 72 countries, an updated verbal autopsy literature review, two new and detailed data systems for China, and more detail for Mexico, UK, Turkey, and Russia. We improved statistical models for garbage code redistribution. We used six different modelling strategies across the 240 causes; cause of death ensemble modelling (CODEm) was the dominant strategy for causes with sufficient information. Trends for Alzheimer's disease and other dementias were informed by meta-regression of prevalence studies. For pathogen-specifi c causes of diarrhoea and lower respiratory infections we used a counterfactual approach. We computed two measures of convergence (inequality) across countries: the average relative difference across all pairs of countries (Gini coefficient) and the average absolute difference across countries. To summarise broad findings, we used multiple decrement life-tables to decompose probabilities of death from birth to exact age 15 years, from exact age 15 years to exact age 50 years, and from exact age 50 years to exact age 75 years, and life expectancy at birth into major causes. For all quantities reported, we computed 95% uncertainty intervals (UIs). We constrained cause-specific fractions within each age-sex-country-year group to sum to all-cause mortality based on draws from the uncertainty distributions. Findings Global life expectancy for both sexes increased from 65.3 years (UI 65.0-65.6) in 1990, to 71.5 years (UI 71.0-71.9) in 2013, while the number of deaths increased from 47.5 million (UI 46.8-48.2) to 54.9 million (UI 53.6-56.3) over the same interval. Global progress masked variation by age and sex: for children, average absolute diff erences between countries decreased but relative diff erences increased. For women aged 25-39 years and older than 75 years and for men aged 20-49 years and 65 years and older, both absolute and relative diff erences increased. Decomposition of global and regional life expectancy showed the prominent role of reductions in age-standardised death rates for cardiovascular diseases and cancers in high-income regions, and reductions in child deaths from diarrhoea, lower respiratory infections, and neonatal causes in low-income regions. HIV/AIDS reduced life expectancy in southern sub-Saharan Africa. For most communicable causes of death both numbers of deaths and age-standardised death rates fell whereas for most non-communicable causes, demographic shifts have increased numbers of deaths but decreased age-standardised death rates. Global deaths from injury increased by 10.7%, from 4.3 million deaths in 1990 to 4.8 million in 2013; but age-standardised rates declined over the same period by 21%. For some causes of more than 100 000 deaths per year in 2013, age-standardised death rates increased between 1990 and 2013, including HIV/AIDS, pancreatic cancer, atrial fibrillation and flutter, drug use disorders, diabetes, chronic kidney disease, and sickle-cell anaemias. Diarrhoeal diseases, lower respiratory infections, neonatal causes, and malaria are still in the top five causes of death in children younger than 5 years. The most important pathogens are rotavirus for diarrhoea and pneumococcus for lower respiratory infections. Country-specific probabilities of death over three phases of life were substantially varied between and within regions. Interpretation For most countries, the general pattern of reductions in age-sex specifi c mortality has been associated with a progressive shift towards a larger share of the remaining deaths caused by non-communicable disease and injuries. Assessing epidemiological convergence across countries depends on whether an absolute or relative measure of inequality is used. Nevertheless, age-standardised death rates for seven substantial causes are increasing, suggesting the potential for reversals in some countries. Important gaps exist in the empirical data for cause of death estimates for some countries; for example, no national data for India are available for the past decade.
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| 12. |
- Pang, F., et al.
(author)
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A dual-band slotted trapezoidal inverted-F antenna for indoor WLAN communications
- 2016
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In: Progress In Electromagnetics Research Letters. - 1937-6480. ; 64, s. 57-63
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Journal article (peer-reviewed)abstract
- This letter presents a new directional dual-band slotted trapezoidal inverted-F antenna (IFA) for indoor Wireless Local Area Network (WLAN) applications. The dual-band performance can be obtained by tuning the lengths of the inner symmetrical trapezoidal slots and the outer trapezoidal arms in a nearly independent manner. The measured results show that the proposed antenna can provide two separate impedance bandwidths (return loss better than 10 dB) around 180MHz and 750MHz for 2.4/5.1-5.8 GHz WLAN bands, respectively. Good radiation performance and roughly constant in-band antenna directivities are also observed.
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| 13. |
- Pelaz, B, et al.
(author)
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Diverse Applications of Nanomedicine
- 2017
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In: ACS nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 11:3, s. 2313-2381
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Journal article (peer-reviewed)
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| 14. |
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| 15. |
- Wei, S., et al.
(author)
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Reconstruction of genome-scale metabolic model of Yarrowia lipolytica and its application in overproduction of triacylglycerol
- 2017
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In: Bioresources and Bioprocessing. - : Springer. - 2197-4365. ; 4:1
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Journal article (peer-reviewed)abstract
- Background: Yarrowia lipolytica is widely studied as a non-conventional model yeast owing to the high level of lipid accumulation. Therein, triacylglycerol (TAG) is a major component of liposome. In order to investigate the TAG biosynthesis mechanism at a systematic level, a novel genome-scale metabolic model of Y. lipolytica was reconstructed based on a previous model iYL619_PCP published by our lab and another model iYali4 published by Kerkhoven et al. Results: The novel model iYL_2.0 contains 645 genes, 1083 metabolites, and 1471 reactions, which was validated more effective on simulations of specific growth rate. The precision of 29 carbon sources utilities reached up to 96.6% when simulated by iYL_2.0. In minimal growth medium, 111 genes were identified as essential for cell growth, whereas 66 essential genes were identified in yeast extract medium, which were verified by database of essential genes, suggesting a better prediction ability of iYL_2.0 in comparison with other existing models. In addition, potential metabolic engineering targets of improving TAG production were predicted by three in silico methods developed in-house, and the effects of amino acids supplementation were investigated based on model iYL_2.0. Conclusions: The reconstructed model iYL_2.0 is a powerful platform for efficiently optimizing the metabolism of TAG and systematically understanding the physiological mechanism of Y. lipolytica. [Figure not available: see fulltext.].
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| 16. |
- Xie, C., et al.
(author)
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An Ultrawideband Dipole With a Director as a Feed for Reflector Antennas
- 2017
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In: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1548-5757 .- 1536-1225. ; 16, s. 1341-1344
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Journal article (peer-reviewed)abstract
- A novel ultrawideband directional flat dipole capped by a planar director is proposed in this letter. The novelty of the antenna is the great improvement of the bandwidth of a flat dipole above an ordinary finite ground plane by using a simple parasitic top patch, referred to as the "director." A linearly polarized prototype has been designed and manufactured, and achieved a nearly 3:1 operating bandwidth (2.2-6.5 GHz) with a return loss higher than 10 dB, nearly constant radiation patterns, and high aperture efficiency over the entire operating band.
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| 17. |
- Xie, C., et al.
(author)
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Low-Profile Ultra-Wideband Directional Dipole Antenna as a Feed for Reflectors in Radio Telescopes
- 2016
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In: 9th International Conference on Microwave and Millimeter Wave Technology Proceedings, Vol. 1, (ICMMT 2016). ; 1, s. 495-497
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Conference paper (peer-reviewed)abstract
- In this paper, a small top plate is found useful to improve the impedance bandwidth of an ultra-wideband dipole antenna horizontally above a ground plane. A linearly-polarized prototype based on this new and simple design methodology can operate over nearly 3.5:1 bandwidth with return losses better than 10 dB, and with nearly stable radiation patterns, high BOR1 efficiency and aperture efficiency over the entire operating band.
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| 18. |
- Yu, J. F., et al.
(author)
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Nonlinear evolution of 2D cellular lean hydrogen/air premixed flames with varying initial perturbations in the elevated pressure environment
- 2017
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In: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 42:6, s. 3790-3803
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Journal article (peer-reviewed)abstract
- This paper reports on studies of cellular instability of lean hydrogen/air laminar premixed flames with an equivalence ratio of 0.6 at a 5 atm and a 25 atm pressure. Numerical simulations employing a detailed chemical kinetics mechanism and detailed transport properties are carried out to simulate the initial linear growth of instability as well as the nonlinear evolution of flames. At the initial linear growth stage, the amplitude of the initial sinusoidal shaped flame front grows exponentially. Later on, in the nonlinear evolution stage the flame front develops into a cellular surface with wavelengths and amplitudes different from its initial ones. At higher pressures, hydrodynamic instability is enhanced, due to smaller flame thermal thickness; the flame fronts are more chaotic. Chaotic flame fronts are captured during the nonlinear evolution stage and it is shown that the evolution is very sensitive to initial perturbations. Two phenomena in the nonlinear evolution process are observed, mode-lock and preferential choice of modes. Both of these appear in connection with the initial disturbances to the flame front. Sensitivity of the numerical results to numerical schemes and the computational setups is examined.
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