•Improved implementation of OpenACC is adopted to accelerate LB simulation.•A speedup around 50–60X can be achieved for multiphysics LB simulation.•Benchmark quality results are obtained with fine ...grid of 20492.
We assess the performance of the combined Open Accelerator (OpenACC) programming standard and graphics processing unit (GPU) accelerator for lattice Boltzmann (LB) simulations of fluid flow, heat and mass transfer. By optimizing the data layout, minimizing the memory access frequency, and adjusting the number of gangs and vector length, we show that the enhanced parallel computations can result in orders of magnitudes of speedup relative to the serial implementation of the LB algorithm. Based on such implementations, benchmark quality results are obtained with fine grid of 20492 for both two-dimensional lid driven cavity flow with Reynolds number up to 7500, and double diffusive cavity flow with solute Rayleigh number up to 108.
Methanol crossover due to the low selectivity of proton exchange membranes is a long-standing issue in direct methanol fuel cell technology. Here we attempt to address this issue by designing a ...composite membrane fabricated by sandwiching a monolayer graphene between two thin Nafion membranes to take advantage of monolayer graphene's selective permeability to only protons. The methanol permeability of the present membrane is demonstrated to have a 68.6% decrease in comparison to that of the pristine Nafion membrane. The test in a passive direct methanol fuel cell (DMFC) shows that the designed membrane retains high proton conductivity while substantially suppressing methanol crossover. As a result, the present membrane enables the passive DMFC to exhibit a decent performance even at a methanol concentration as high as 10.0 M.
•A composite membrane consisting of monolayer graphene is proposed for DMFCs.•The methanol permeability through the membrane is demonstrated to decrease by 68%.•The membrane enables a passive DMFC to operate with highly concentrated solutions.
•Ion-exchange zeolite and MgCl2 impregnated zeolite were developed.•Sorption capacity improved by 18% for Mg-exchange and 53% for MgCl2 impregnation.•Sorption equilibrium and kinetics of zeolites ...were studied.•Temperature and concentration dependence of diffusivity were discussed.
Zeolite NaX is one of the most popular water sorption materials for dehumidification, thermal energy storage and sorption cooling. In this paper, zeolite NaX is modified by magnesium chloride to achieve ion-exchange (zeolite NaMgX) and salt impregnation (zeolite NaX/MgCl2) with the aim of improving water sorption capacity and thermal performance. The pore structure, desorption heat, water equilibrium sorption property, adsorption kinetics and cycling stability of zeolite NaX, NaMgX and NaX/MgCl2 were studied to evaluate their potential for sorption application. Experimental results show the zeolite NaMgX has stronger hydrophilic and can improve the water sorption capacity from 0.17 g/g to 0.20 g/g at 2500 Pa. The zeolite NaX/MgCl2 with 12.6 wt% salt confined inside the meso-/macro-pore, can improve the water sorption capacity from 0.17 g/g to 0.26 g/g with sorption heat of 842 J/g. The sorption rate of zeolite NaX/MgCl2 is much lower than that of pure zeolite NaX, while zeolite NaMgX has a slight lower sorption rate than pure zeolite NaX. The diffusivity of zeolite NaX is in the range of 8.03 × 10−10–1.97 × 10−9 m2/s at 1000–2500 Pa, while zeolite NaMgX and zeolite NaX/MgCl2 have diffusivities in the range of 5.22 × 10−10–1.73 × 10−9 m2/s and 3.76 × 10−10–9.87 × 10−10 m2/s respectively. The diffusivities of different zeolite samples increase with temperature which can be described by activated energy factor, and the relation between diffusivity and pressure is strongly coupled with the equilibrium equation. The modified zeolites have good thermal stabilities and no obvious uptake loss after ten adsorption-desorption cycles, making them feasible, scalable and economical for sorption thermal energy storage and cooling applications.
We report preparation of carbon-supported Co
3
O
4
electrocatalysts with nano-rods and spherical structures by the solvent-mediated morphological control method. The catalytic properties of the ...prepared catalysts for the oxygen reduction reaction (ORR) in alkaline media are investigated. We show that the ORR catalytic activity of the prepared catalysts is sensitive to the number and activity of surface-exposed Co
3+
ions that can be tailored by the morphology of cobalt oxides. In particular, we demonstrate that the non-precious Co
3
O
4
electrocatalyst with the nano-rod structure (12 nm in length and 5.1 nm in diameter) prepared in the mixed solvent of water to dimethylformamide ratio of 1:1 exhibits a higher current density than a much more expensive palladium-based catalyst does at the low potential region.
We report a promising non-precious carbon-supported Co
3
O
4
nanorod electrocatalyst prepared by the solvent-mediated morphological control method for the oxygen reduction reaction in anion-exchange membrane fuel cells.
Mechanisms implicated in disease progression in multiple sclerosis include continued oligodendrocyte (OL)/myelin injury and failure of myelin repair. Underlying causes include metabolic stress with ...resultant energy deficiency. Biotin is a cofactor for carboxylases involved in ATP production that impact myelin production by promoting fatty acid synthesis. Here, we investigate the effects of high dose Biotin (MD1003) on the functional properties of post-natal rat derived oligodendrocyte progenitor cells (OPCs). A2B5 positive OPCs were assessed using an in vitro injury assay, culturing cells in either DFM (DMEM/F12+N1) or "stress media" (no glucose (NG)-DMEM), with Biotin added over a range from 2.5 to 250 μg/ml, and cell viability determined after 24 hrs. Biotin reduced the increase in OPC cell death in the NG condition. In nanofiber myelination assays, biotin increased the percentage of ensheathing cells, the number of ensheathed segments per cell, and length of ensheathed segments. In dispersed cell culture, Biotin also significantly increased ATP production, assessed using a Seahorse bio-analyzer. For most assays, the positive effects of Biotin were observed at the higher end of the dose-response analysis. We conclude that Biotin, in vitro, protects OL lineage cells from metabolic injury, enhances myelin-like ensheathment, and is associated with increased ATP production.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Carbon-supported gold nanoparticles (Au/C) are successfully decorated with mono- or sub-monolayer palladium atoms with different Pd/Au atomic ratios by a chemically epitaxial seeded growth method. ...TEM, UV–vis spectrometry and XRD techniques are used to characterize the particle size, dispersion, palladium coverage on gold seeds and crystal structures of the prepared catalysts. Cyclic voltammetric tests show that the Pd-decorated Au/C (denoted by Pd@Au/C) have higher specific activities than that of Pd/C for the oxidation of ethanol in alkaline media. This suggests that the Pd utilization is improved with such a surface-alloyed nanostructure. In addition, stable chronoamperometric responses are achieved with the so-prepared electrocatalysts during ethanol oxidation.
Although microRNAs (miRs) have been implicated in the pathogenesis of various human malignancies, limited information is available regarding mechanisms by which these noncoding RNAs contribute to ...initiation and progression of tobacco-induced esophageal cancers. In this study, array and quantitative reverse transcriptase-PCR techniques were used to examine miR expression in immortalized esophageal epithelia (IEE) and esophageal adenocarcinoma (EAC) cells cultured in normal media with or without cigarette smoke condensate (CSC). Under relevant exposure conditions, CSC significantly decreased miR-217 expression in these cells. Endogenous levels of miR-217 expression in cultured EAC cells (EACC)/primary EACs were significantly lower than those observed in IEE/ paired normal esophageal tissues. RNA crosslink immunoprecipitation, quantitative reverse transcriptase-PCR (qRT-PCR) and immunoblot experiments demonstrated direct interaction of miR-217 with kallikrein 7 (KLK7), encoding a putative oncogene not previously implicated in EAC. Repression of miR-217 correlated with increased levels of KLK7 in primary EACs, particularly those from smokers. Chromatin and methylated DNA immunoprecipitation experiments demonstrated that CSC-mediated repression of miR-217 coincided with DNMT3b-dependent hypermethylation and decreased occupancy of nuclear factor 1 within the miR-217 genomic locus. Deoxyazacytidine induced miR-217 expression and downregulated KLK7 in EACC; deoxyazacytidine also attenuated CSC-mediated miR-217 repression and upregulation of KLK7 in IEE and EACC. Overexpression of miR-217 significantly decreased, whereas overexpression of KLK7 increased proliferation, invasion and tumorigenicity of EACC. Collectively, these data demonstrate that epigenetic repression of miR-217 contributes to the pathogenesis of EAC via upregulation of KLK7 and suggest that restoration of miR-217 expression may be a novel treatment strategy for these malignancies.
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