Channel Dimension Constraints for Miniature Low Humidity PEM Fuel Cells

Numerous applications exist requiring power for small loads (\u3c5W) with minimal mass operating in extreme ambient conditions. Making progress toward reducing stack mass, we investigate the influence of flow field channel depth and endplate compression on cell performance. The best performance was found at endplate compressions of 139 psi, cathode channel depths of 0.032 in and anode channel depths of 0.032 in. The maximum power mass-density achieved with these 4.84 cm2 cells was 16.8 mW/g in a single cell stack. If deployed in a multicell stack, this same performance would translate to a power mass-density of 45.3 mW/g, nearing the performance of off-the-shelf lithiumion batteries (approximately 70 mW/g)

Association between ideal cardiovascular health metrics and suboptimal health status in Chinese population

Suboptimal health status (SHS) is a physical state between health and illness, and previous studies suggested that SHS is associated with majority components of cardiovascular health metrics defined by American Heart Association (AHA). We investigated the association between SHS and cardiovascular health metrics in a cross-sectional analysis of China suboptimal health cohort study (COACS) consisting of 4313 participants (60.30% women) aged from 18 to 65 years old. The respective prevalence of SHS is 7.10%, 9.18%, 10.04% and 10.62% in the first, second, third and fourth quartiles of ideal cardiovascular health (CVH) metrics (P for trend = 0.012). Participants in the largest quartile of ideal CVH metrics show a lower likelihood of having optimal SHS score compared to those in the smallest quartile (odds ratio (OR), 0.43; 95% confidence interval (CI), 0.32–0.59), after adjusting for age, gender, marital status, alcohol consumption, income level and education. Four metrics (smoking, physical inactivity, poor dietary intake and ideal control of blood pressure are significantly correlated with the risk of SHS. The present study suggests that ideal CVH metrics are associated with a lower prevalence of SHS, and the combined evaluation of SHS and CVH metrics allows the risk classification of cardiovascular disease, and thus consequently contributes to the prevention of cardiovascular diseases

Association between ideal cardiovascular health metrics and suboptimal health status in Chinese population

Suboptimal health status (SHS) is a physical state between health and illness, and previous studies suggested that SHS is associated with majority components of cardiovascular health metrics defined by American Heart Association (AHA). We investigated the association between SHS and cardiovascular health metrics in a cross-sectional analysis of China suboptimal health cohort study (COACS) consisting of 4313 participants (60.30 % women) aged from 18 to 65 years old. The respective prevalence of SHS is 7.10 %, 9.18 %, 10.04 % and 10.62 % in the first, second, third and fourth quartiles of ideal cardiovascular health (CVH) metrics (P for trend = 0.012). Participants in the largest quartile of ideal CVH metrics show a lower likelihood of having optimal SHS score compared to those in the smallest quartile (odds ratio (OR), 0.43; 95% confidence interval (CI), 0.32 – 0.59), after adjusting for age, gender, marital status, alcohol consumption, income level and education. Four metrics (smoking, physical inactivity, poor dietary intake and ideal control of blood pressure are significantly correlated with the risk of SHS. The present study suggests that ideal CVH metrics are associated with a lower prevalence of SHS, and the combined evaluation of SHS and CVH metrics allows the risk classification of cardiovascular disease, and thus consequently contributes to the prevention of cardiovascular diseases

Identification of the Ilex macrocarpa anthracnose pathogen and the antifungal potential of the cell-free supernatant of Bacillus velezensis against Colletotrichum fioriniae

IntroductionAnthracnose is a significant fungal disease that affects tree growth and development, with Colletotrichum spp. exhibiting host non-specificity and targeting various organs, making disease control challenging.MethodsThis study aimed to identify the pathogenic species causing anthracnose in Ilex macrocarpa in Nanchong, Sichuan Province, and screen effective fungicides, particularly biological ones. The pathogen was identified as Colletotrichum fioriniae through morphological observation, pathogenicity assays, and molecular biological methods. Three biological and five chemical fungicides were evaluated for their effects on the mycelial growth and spore germination rate of the pathogen.ResultsThe results indicated that prochloraz was the most effective chemical fungicide, while the cell-free supernatant (CFS) of Bacillus velezensis had the most significant inhibitory effect among the biological fungicides. Transcriptome analysis revealed that the CFS of B. velezensis significantly reduced the expression of genes associated with ribosomes, genetic information processing, membrane lipid metabolism, and sphingolipid biosynthesis in C. fioriniae. Additionally, the glutathione pathway’s expression of various genes, including key genes such as GST, GFA, Grx, TRR, and POD, was induced. Furthermore, the expression of 17 MFS transporters and 9 ABC transporters was increased. Autophagy-related ATGs were also affected by the B. velezensis CFS.DiscussionThese findings suggest that the B. velezensis CFS may inhibit C. fioriniae through interference with ribosomes, genetic information processing, cell membrane metabolism, and energy metabolism. These results provide potential target genes for the B. velezensis CFS and insights into the antifungal mechanism by which B. velezensis inhibits C. fioriniae

Predation of Daurian redstarts offspring in nest boxes by the Oriental magpie‐robin and tree sparrow

Abstract Birds select suitable nest sites for breeding to ensure their own and offspring's survival; however, they inevitably suffer some potential predation risk. We studied the breeding ecology of Daurian redstarts (Phoenicurus auroreus) by providing nest boxes for their breeding from March to August of 2022. We recorded the predation of both Daurian redstarts eggs or nestlings by Oriental magpie‐robins (Copsychus saularis) and tree sparrow (Passer montanus). Oriental magpie‐robin were recorded attacking a feeding female adult and depredating nestlings. After the nestling predation event, the Daurian redstarts abandoned the nest. This video evidence provide a better understanding of the potential predators of cavity‐nesting birds

Measurement of contact resistivity at metal-tin sulfide (SnS) interfaces

We measured the contact resistivity between tin(II) sulfide (SnS) thin films and three different metals (Au, Mo, and Ti) using a transmission line method (TLM). The contact resistance increases in the order Au < Mo < Ti. The contact resistances for Au and Mo are low enough so that they do not significantly decrease the efficiency of solar cells based on SnS as an absorber. On the other hand, the contact resistance of Ti to SnS is sufficiently high that it would decrease the efficiency of a SnS solar cell using Ti as a back contact metal. We further estimate the barrier heights of the junctions between these metals and tin sulfide using temperature-dependent TLM measurements. The barrier heights of these three metals lie in a narrow range of 0.23-0.26 eV, despite their large differences in work function. This Fermi level pinning effect is consistent with the large dielectric constant of SnS, and comparable to Fermi-level pinning on Si. The contact resistivity between annealed SnS films and Mo substrates under light illumination is as low as 0.1 Ω cm2.National Science Foundation (U.S.) (Award No. 1541959

Framework to predict optimal buffer layer pairing for thin film solar cell absorbers: A case study for tin sulfide/zinc oxysulfide

An outstanding challenge in the development of novel functional materials for optoelectronic devices is identifying suitable charge-carrier contact layers. Herein, we simulate the photovoltaic device performance of various n-type contact material pairings with tin(II) sulfide (SnS), a p-type absorber. The performance of the contacting material, and resulting device efficiency, depend most strongly on two variables: conduction band offset between absorber and contact layer, and doping concentration within the contact layer. By generating a 2D contour plot of device efficiency as a function of these two variables, we create a performance-space plot for contacting layers on a given absorber material. For a simulated high-lifetime SnS absorber, this 2D performance-space illustrates two maxima, one local and one global. The local maximum occurs over a wide range of contact-layer doping concentrations (below 1016 cm−3), but only a narrow range of conduction band offsets (0 to −0.1 eV), and is highly sensitive to interface recombination. This first maximum is ideal for early-stage absorber research because it is more robust to low bulk-minority-carrier lifetime and pinholes (shunts), enabling device efficiencies approaching half the Shockley-Queisser limit, greater than 16%. The global maximum is achieved with contact-layer doping concentrations greater than 1018 cm−3, but for a wider range of band offsets (−0.1 to 0.2 eV), and is insensitive to interface recombination. This second maximum is ideal for high-quality films because it is more robust to interface recombination, enabling device efficiencies approaching the Shockley-Queisser limit, greater than 20%. Band offset measurements using X-ray photoelectron spectroscopy and carrier concentration approximated from resistivity measurements are used to characterize the zinc oxysulfide contacting layers in recent record-efficiency SnS devices. Simulations representative of these present-day devices suggest that record efficiency SnS devices are optimized for the second local maximum, due to low absorber lifetime and relatively well passivated interfaces. By employing contact layers with higher carrier concentrations and lower electron affinities, a higher efficiency ceiling can be enabled.Chemistry and Chemical Biolog