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As a carbon-free fuel, hydrogen has received significant attention recently since it can help enable low-carbon-economy. Hydrogen has very broad flammability range and very low minimum ignition energy, and thereby there are severe safety concerns for hydrogen transportation and utilization. Cryo-compressed hydrogen is popularly used in practice. Therefore, it is necessary to investigate the combustion properties of hydrogen at extremely low or cryogenic temperatures. This study aims to assess and interpret the effects of cryogenic temperature on premixed hydrogen/air flame propagation and acceleration in a thin closed channel. Different initial temperatures ranging from normal temperature (T 0 = 300 K) to cryogenic temperature (T 0 = 100 K) are considered. Both one- and two-dimensional hydrogen/air flames are investigated through transient simulations considering detailed chemistry and transport. It is found that when the initial temperature decreases from T 0 = 300 K to T 0 = 100 K, the expansion ratio and equilibrium pressure both increase substantially while the laminar flame speeds relative to unburned and burned gasses decrease moderately. The one-dimensional flame propagation is determined by laminar flame speed and thereby the combustion duration increases as the initial temperature decreases. However, the opposite trend is found to happen to two-dimensional flame propagation, which is mainly controlled by the flame surface area increase due to the no-slip side wall constraint and flame instability. Based on the change in flame surface area, three stages including the initial acceleration, steady burning and rapid acceleration are identified and investigated. It is demonstrated that the large expansion ratio and high pressure rise at cryogenic temperatures can significantly increase the flame surface area in early stage and promote both Darrieus-Landau instability (hydrodynamic instability) and Rayleigh-Taylor instability in later stage. These two instabilities can substantially increase the flame surface area and thereby accelerate flame propagation in hydrogen/air mixtures at cryogenic temperatures. The present study provides useful insights into the fundamental physics of hydrogen flames at extremely low temperatures, and is closely related to hydrogen safety. [ABSTRACT FROM AUTHOR]

X-linked inhibitor of apoptosis (XIAP) deficiency is a rare primary immunodeficiency disease caused by XIAP gene mutations. A broad range of phenotype, severity, and age at onset present challenges for patient management. We sought to characterize the phenotype, treatment, and survival outcomes of XIAP deficiency and to assess parameters influencing prognosis. Data published from 2006 to 2020 were retrospectively analyzed. A total of 167 patients from 117 families with XIAP deficiency were reported with 90 different mutations. A wide spectrum of clinical features were seen, of which hemophagocytic lymphohistiocytosis (HLH) and inflammatory bowel disease were the most common. Patients frequently developed multiple features with no clear genotype–phenotype correlation. A total of 117 patients were managed conservatively and 50 underwent hematopoietic stem-cell transplantation (HSCT), with respective overall survival probabilities of 90% and 53% at age 16 years. The predominant indication for HSCT was early-onset HLH. Active HLH and myeloablative conditioning regimens increased HSCT-related mortality, although HSCT outcome was much better after 2015 than before. For conservatively managed patients reaching adulthood, survival probabilities were 86% at age 30 years and 37% by age 52 years, with worse outcomes for patients developing the disease before the age of 5 years or with new disease features in adulthood. Nine asymptomatic mutation carriers with a median age of 13.5 years were identified. Our study demonstrates the variable nature of XIAP deficiency, which evolves over life for individual patients. Better therapeutic strategies and prospective studies are required to reduce morbidity and mortality and improve decision making and long-term outcomes for patients with XIAP deficiency. [ABSTRACT FROM AUTHOR]

Hydrogen is an attractive alternative fuel which may play an important role in the reduction of carbon dioxide emission. The widespread use of hydrogen raises concerns on safety issues such as fires and explosions related to the storage, transportation and utilization of liquid hydrogen. Therefore, it is necessary to understand the combustion properties of hydrogen at cryogenic temperatures. In this study, we conduct two-dimensional simulations of circular expanding hydrogen/air flame in an open space and investigate the flame morphology evolution and self-acceleration processes. Stoichiometric hydrogen/air mixtures with near-unity Lewis number at cryogenic temperature (100 K) and normal temperature (300 K) are considered so that the flame propagation is mainly affected by the Darrieus-Landau instability (DLI, or hydrodynamic instability) instead of the diffusional-thermal instability (DTI). The flame morphology, flame propagation speed pulsation, development and evolution of cellular structure, and self-acceleration are investigated. Since the thermal expansion increases greatly with the decrease in the initial temperature, the DLI at cryogenic temperature becomes much stronger than that at normal temperature, which results in significant increase in flame propagation speed, total heat release rate, acceleration exponent as well as violent cell evolution including cell growth, splitting and merging. The stronger DLI at lower initial temperature leads to larger cell number, smaller mean cell size and longer mean cell depth. Analyses on cell statistics show that the intermittent characteristic of flame propagation speed is mainly caused by cell evolution. Interestingly, the integral heat release rate and flame propagation speed at cryogenic temperature can be comparable to those at normal temperature. Such counterintuitive observation is important for fire safety control and risk assessment of cryogenic hydrogen storage and utilization. [ABSTRACT FROM AUTHOR]

Emodin-8- O -β-D-glucopyranoside (Em8G) is an active ingredient of traditional Chinese medicine Rhei Radix et Rhizoma and Polygonum multiflorum Thunb.. And it caused hepatotoxicity, while the underlying mechanism was not clear yet. We aimed to explore the detrimental effects of Em8G on the zebrafish liver through the metabolome and transcriptome integrated analysis. In this study, zebrafish larvae were used in acute toxicity tests to reveal the hepatotoxicity of Em8G. Adult zebrafish were then used to evaluate the gender differences in hepatotoxicity induced by Em8G. Integration of transcriptomic and metabolomic analysis was used further to explore the molecular mechanisms underlying gender differences in hepatotoxicity. Our results showed that under non-lethal concentration exposure conditions, hepatotoxicity was observed in Em8G-treated zebrafish larvae, including changes in liver transmittance, liver area, hepatocyte apoptosis and hepatocyte vacuolation. Male adult zebrafish displayed a higher Em8G-induced hepatotoxicity than female zebrafish, as demonstrated by the higher mortality and histopathological alterations. The results of transcriptomics combined with metabolomics showed that Em8G mainly affected carbohydrate metabolism (such as TCA cycle) in male zebrafish and amino acid metabolism (such as arginine and proline metabolism) in females, suggesting that the difference of energy metabolism disorder may be the potential mechanism of male and female liver toxicity induced by Em8G. This study provided the direct evidence for the hepatotoxicity of Em8G to zebrafish models in vivo , and brought a new insight into the molecular mechanisms of Em8G hepatotoxicity, which can guide the rational application of this phytotoxin. In addition, our findings revealed gender differences in the hepatotoxicity of Em8G to zebrafish, which is related to energy metabolism and provided a methodological reference for evaluating hepatotoxic drugs with gender differences. [Display omitted] [ABSTRACT FROM AUTHOR]

Influenza A virus (IAV) infection causes acute and often lethal inflammation in the lung. The role of macrophages in this adverse inflammation is partially understood. The surfactant protein A receptor 210 (SP-R210) consists of two isoforms, a long (L) SP-R210 L and a short (S) SP-R210 S isoform encoded by alternative splicing of the myosin 18A gene. We reported that disruption of SP-R210 L enhances cytosolic and endosomal antiviral response pathways. Here, we report that SP-R210 L antagonizes type I interferon β (IFNβ), as depletion of SP-R210 L potentiates IFNβ secretion. SP-R210 antibodies enhance and attenuate IFNβ secretion in SP-R210 L replete and deficient macrophages, respectively, indicating that SP-R210 isoform stoichiometry alters macrophage function intrinsically. This reciprocal response is coupled to unopposed and restricted expression of viral genes in control and SP-R210 L -deficient macrophages, respectively. Human monocytic cells with sub-stoichiometric expression of SP-R210 L resist IAV infection, whereas alveolar macrophages with increased abundance of SP-R210 L permit viral gene expression similar to murine macrophages. Uptake and membrane binding studies show that lack of SP-R210 isoforms does not impair IAV binding and internalization. Lack of SP-R210 L , however, results in macropinocytic retention of the virus that depends on both SP-R210 S and interferon-inducible transmembrane protein-3 (IFITM3). Mass spectrometry and Western blot analyses indicate that SP-R210 isoforms modulate differential recruitment of the Rho-family GTPase RAC1 and guanine nucleotide exchange factors. Our study suggests that SP-R210 isoforms modulate RAC-dependent macropinosomal sorting of IAV to discrete endosomal and lysosomal compartments that either permit or prevent endolysosomal escape and inflammatory sensing of viral genomes in macrophages. [ABSTRACT FROM AUTHOR]

The unreliable durability of high temperature proton exchange membrane fuel cells (HT-PEMFCs) is one of the restriction factors upon the commercialization process. In this paper, 600-h accelerated stress tests (ASTs) were performed on HT-PEMFCs to investigate the performance degradation under start/stop, load cycling (0.2–0.8 A cm−2 and 0.04–0.2 A cm−2) conditions. The activation, ohmic and mass transport polarization losses were determined in combination with the electrochemical impedance spectroscopy (EIS) and Tafel slope analysis, and the degradation modes such as carbon corrosion, catalyst degradation, acid loss and membrane degradation were analyzed by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and transmission electron microscopy (TEM) characterization. The polarization curves of ASTs show that load cycling between 0.04 and 0.2 A cm−2 extensively aggravates performance degradation, indicating that high-potential operation has the greatest detrimental impact on the durability. By comparing the changes of the activation, ohmic and mass transport polarization losses, it can be found that the activation polarization is the dominant factor leading to performance degradation in the 600-h test, and the ohmic polarization has little effect on the performance degradation. After the test at load cycling between 0.2 and 0.8 A cm−2, the membrane is seriously degraded and the ohmic resistance increases significantly, and the severe acid loss becomes critical issue in the long-term durability of HT-PEMFC. • Activation, ohmic and mass transfer polarization losses are determined. • Activated polarization accounts for the largest proportion in the short term test. • Acid loss seriously affects the long term durability of HT-PEMFC. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) as a remarkable fluorescent nanomaterial have the advantages of easy preparation, good photostability and high sensitivity. However, the poor aqueous solution stability of carbon dots largely limited their practical application due to the characteristic of easily forming precipitation for long time storage. Here, a kind of cationic fluorescent carbon dots CDs-P(Ph) 3 was designed by introducing a cationic compound, (4-carboxybutyl) triphenyl phosphonium bromide, to construct an electrostatic shell outside the dots. Such electrostatic shell could highly improve carbon dots stability in an aqueous solution to make CDs-P(Ph) 3 stable for long-term storage with negligible aggregation. Meanwhile, the sensitivity of CDs-P(Ph) 3 for hypochlorous acid (HClO) was also enhanced on the basis of the electron-withdrawing effect of cationic substituents on the surface of carbon dots. The limit of detection of CDs-P(Ph) 3 for HClO was as low as ∼0.32 μM. Additionally, the fluorescence of CDs-P(Ph) 3 could be rapid quenched by HClO with a quenching efficiency of more than 80% within 30 s. The excellent stability of CDs-P(Ph) 3 in an aqueous solution made it suitable for on-site detecting HClO in real samples, such as tap, well and lake water. Such designed fluorescent nanomaterial would provide a practical application pathway for optical sensing detection in environmental samples. [Display omitted] • The cationic fluorescence carbon dots were easily obtained by one-step synthesis. • Utilize the electrostatic repulsion of cation groups modified on surface of CDs to highly enhance its stability in aqueous. • The strong electron-withdrawing inductive effect of cation groups made CDs having higher sensitivity for HClO. • Real-time assessment and in-situ inspections of drinking water safety in the field. [ABSTRACT FROM AUTHOR]

The stoichiometric ratio and flow channel geometry play a vital role in the performance of high temperature proton exchange membrane (HT-PEM) fuel cells. Because of the high cost of experiments or simulations, most analyses and optimization of the stoichiometric ratio and flow channel geometry are limited to several points in the entire design domain. In this study, an analysis and optimization method for HT-PEM fuel cells based on the surrogate model was proposed. Surrogate models were constructed using some of the available budgets of samples to analyze and optimize the entire design domain. With this method, it was indicated that the effect of the cathode stoichiometric ratio is more significant to the cell performance than the anode stoichiometric ratio and there are significant nonlinear interactions among the flow channel geometry parameters. At the fixed operating voltage, the flow channel geometry with the maximum current density and that with the maximum real power were obtained. Compared with the base design, the designs obtained by the surrogate model improve the current density and real power by 10.54% and 3.93%, respectively. Thus, this analysis and optimization method is demonstrated to be helpful and deserves attention in future research. Image 1 • It is proved that the effect of cathode stoichiometric ratio was more significant. • The design obtained by the surrogate model improve current density by 10.54%. • The design obtained by the surrogate model improve real power by 3.93%. [ABSTRACT FROM AUTHOR]

Direct urea fuel cells (DUFCs) can be used to treat residual wastewater while generating electricity. Herein, self-supported electrodes consisting of NiO nanosheets vertically grown on CuO nanowires are synthesized to realize the urea oxidation reaction (UOR). Such electrodes show excellent UOR performance requiring 1.39 V vs. RHE to achieve 100 mA/cm2. Besides, DUFCs provide open circuit voltages and power densities up to 0.88 V and 11.35 mW/cm2. Electrochemical characterization and Raman spectroscopy prove the formation of NiOOH to enable the UOR. Mott-Schottky analysis and UV photoelectron spectroscopy show the NiO/CuO p-p heterostructure to facilitate the charge transfer from CuO nanowires to NiO nanosheets. Besides, at a local level, density functional theory calculations show that the presence of CuO modulates the electronic states of Ni at the very NiOOH/CuO interface, which results in stretched Ni-O bonds and a uniquely elongated N-H bond of urea that favors its oxidation. [Display omitted] • A 2D NiO nanosheets vertically grown on 1D CuO nanowires on Cu mesh was engineered. • NiO/CuO heterojunction modulates the surface electronic states and facilitates electrons transfer at the interface. • Elongated N-H bond of urea molecules facilitate the dehydrogenation process. • Direct urea fuel cells based on NiO/CuO@CuM show excellent performance. [ABSTRACT FROM AUTHOR]

Volume-regulated anion channels (VRACs) are hexamers of LRRC8 proteins that are crucial for cell volume regulation. N termini (NTs) of the obligatory LRRC8A subunit modulate VRACs activation and ion selectivity, but the underlying mechanisms remain poorly understood. Here, we report a 2.8-Å cryo-electron microscopy structure of human LRRC8A that displays well-resolved NTs. Amino-terminal halves of NTs fold back into the pore and constrict the permeation path, thereby determining ion selectivity together with an extracellular selectivity filter with which it works in series. They also interact with pore-surrounding helices and support their compact arrangement. The C-terminal halves of NTs interact with intracellular loops that are crucial for channel activation. Molecular dynamics simulations indicate that low ionic strength increases NT mobility and expands the radial distance between pore-surrounding helices. Our work suggests an unusual pore architecture with two selectivity filters in series and a mechanism for VRAC activation by cell swelling. [Display omitted] • Cryo-EM structure of LRRC8A volume-regulated anion channel reveals back-folded N termini • N termini form a selectivity filter in series with a second one at the external pore opening • Molecular dynamics calculations suggest that low ionic strength partially unwinds N termini • The unwound N termini may modulate channel activation by cell swelling Liu et al. show that the N terminus of LRRC8A, resolved in their structure of a volume-regulated VRAC anion channel, inserts into the pore. It forms a second selectivity filter in series with an external one. Its partial unfolding under low ionic strength may trigger activation of VRAC by cell swelling. [ABSTRACT FROM AUTHOR]