Search

Flows at Ma = 1.5 over a cavity with different leading-edge sawtooth spoilers were numerically studied using improved delayed detached-eddy simulation based on the two-equation shear stress transport model, coupled with the adaptive dissipation scheme. Transonic flow past M219 cavity was chosen as the validation case for numerical methods and mesh convergence. Comparison of predicted sound pressure levels and spectra against the measurements has proved that the major oscillation dynamics inside the cavity is captured numerically. Five sawtooth spoilers were then evaluated before the leading edge of a complex irregular cavity in a supersonic flow. It is found that the spoiler lifts the shear layer, preventing its reattachment on the cavity floor, and completely changes the cavity flow type. The presence of sawtooth is necessary to promote instability more upstream. All spoilers show significant reduction in pressure fluctuation. Pressure decrease on the cavity floor and rear wall contributes to overall drag reduction, despite the extra drag by the spoiler. The spoiler with height equal to the local boundary layer thickness and a 90° tooth angle achieves optimal and balanced performance in both drag reduction and noise suppression among the evaluated spoilers. [ABSTRACT FROM AUTHOR]

Exploration of heterogeneous molecular catalysts combining the atomic-level tunability of molecular structures and the practical handling advantages of heterogeneous catalysts represents an attractive approach to developing high-performance catalysts for important and challenging chemical reactions such as electrochemical carbon dioxide reduction which holds the promise for converting emissions back to fuels utilizing renewable energy. Thus, far, efficient and selective electroreduction of CO2 to deeply reduced products such as hydrocarbons remains a big challenge. Here, we report a molecular copper-porphyrin complex (copper(II)-5,10,15,20-tetrakis(2,6-dihydroxyphenyl)porphyrin) that can be used as a heterogeneous electrocatalyst with high activity and selectivity for reducing CO2 to hydrocarbons in aqueous media. At -0.976 V vs the reversible hydrogen electrode, the catalyst is able to drive partial current densities of 13.2 and 8.4 mA cm-2 for methane and ethylene production from CO2 reduction, corresponding to turnover frequencies of 4.3 and 1.8 molecules⋅site-1⋅s-1 for methane and ethylene, respectively. This represents the highest catalytic activity to date for hydrocarbon production over a molecular CO2reduction electrocatalyst. The unprecedented catalytic performance is attributed to the built-in hydroxyl groups in the porphyrin structure and the reactivity of the copper(I) metal center. [ABSTRACT FROM AUTHOR]

Strong metal/oxide interactions havebeen acknowledged to play prominent roles in chemical catalysis inthe gas phase, but remain as an unexplored area in electrocatalysisin the liquid phase. Utilization of metal/oxide interface structurescould generate high performance electrocatalysts for clean energystorage and conversion. However, building highly dispersed nanoscalemetal/oxide interfaces on conductive scaffolds remains a significantchallenge. Here, we report a novel strategy to create metal/oxideinterface nanostructures by growing mixed metal oxide nanoparticleson carbon nanotubes (CNTs) and then selectively promoting migrationof one of the metal ions to the surface of the oxide nanoparticlesand simultaneous reduction to metal. Employing this strategy, we havesynthesized Ni/CeO2nanointerfaces coupled with CNTs. TheNi/CeO2interface promotes hydrogen evolution catalysisby facilitating water dissociation and modifying the hydrogen bindingenergy. The Ni/CeO2–CNT hybrid material exhibitssuperior activity for hydrogen evolution as a result of synergisticeffects including strong metal/oxide interactions, inorganic/carboncoupling, and particle size control. [ABSTRACT FROM AUTHOR]

Abstract: Cyclosporin A (CsA), one of the most fundamental immunosuppressive drugs, is routinely used in clinics for the treatment of liver and other organ rejections. However, one of the major challenges of the application of CsA is the occurrence of the serious adverse effects, namely, acute and chronic nephrotoxicity, severe hypertension and neurotoxicity. Although N-(3?,4?-dimethoxycinnamoyl) anthranilic acid (3,4-DAA) plays an important role in apoptosis of activated T cells, and is therapeutically used as an orally active anti-allergic drug for the treatment of allergy, it has not been tested for use in the treatment of organ rejection. In this study, we used the dark agouti (DA)-Lewis rat orthotopic liver transplantation (OLT) model to investigate whether the combination of 3,4-DAA with CsA is a promising and useful strategy to lower CsA dosage for reducing CsA side effect and preserve therapeutic effect of CsA. Here, we document that the combination treatment effectively inhibits acute liver rejection in OLT model with only half the normally suggested dosage of CsA that has much less side effect in rats than that of the full dosage. These results indicate that 3,4-DAA may serve as an effective adjunct for a CsA-based immunosuppressive regimen to treat transplant recipients for reducing CsA side effect. [Copyright &y& Elsevier]

As the genome is organized into a three-dimensional structure in intracellular space, epigenomic information also has a complex spatial arrangement. However, most epigenetic studies describe locations of methylation marks, chromatin accessibility regions, and histone modifications in the horizontal dimension. Proper spatial epigenomic information has rarely been obtained. In this study, we designed spatial chromatin accessibility sequencing (SCA-seq) to resolve the genome conformation by capturing the epigenetic information in single-molecular resolution while simultaneously resolving the genome conformation. Using SCA-seq, we are able to examine the spatial interaction of chromatin accessibility (e.g. enhancer–promoter contacts), CpG island methylation, and spatial insulating functions of the CCCTC-binding factor. We demonstrate that SCA-seq paves the way to explore the mechanism of epigenetic interactions and extends our knowledge in 3D packaging of DNA in the nucleus. [ABSTRACT FROM AUTHOR]

The rechargeable lithium-sulfur battery is a promising option for energy storage applications because of its low cost and high energy density. The electrochemical performance of the sulfur cathode, however, is substantially compromised because of fast capacity decay caused by polysulfide dissolution/shuttling and low specific capacity caused by the poor electrical conductivities of the active materials. Herein we demonstrate a novel strategy to address these two problems by designing and synthesizing a carbon nanotube (CNT)/NiFe2O4-S ternary hybrid material structure. In this unique material architecture, each component synergistically serves a specific purpose: The porous CNT network provides fast electron conduction paths and structural stability. The NiFe2O4 nanosheets afford strong binding sites for trapping polysulfide intermediates. The fine S nanoparticles well-distributed on the CNT/NiFe2O4 scaffold facilitate fast Li+ storage and release for energy delivery. The hybrid material exhibits balanced high performance with respect to specific capacity, rate capability, and cycling stability with outstandingly high Coulombic efficiency. Reversible specific capacities of 1350 and 900 mAh g-1 are achieved at rates of 0.1 and 1 C respectively, together with an unprecedented cycling stability of ~0.009% capacity decay per cycle over more than 500 cycles. [ABSTRACT FROM AUTHOR]

• Rainfall leads to increased humidity and a subsequent end to the heatwave. • Post- heatwave periods witness a notable decrease in water storage. • Heatwave conclusions correspond with heightened rainfall and increased runoff. • Rainfall is more probable post- heatwave than in non– heatwave intervals. Extreme heat and drought conditions are affecting water availability in many regions worldwide, leading to negative impacts on human societies, agriculture, and ecosystems. However, current research lacks comprehensive spatiotemporal analysis examining the interplay between multiple hydrological factors and heatwave events, especially in the context of climate change. This research broadly pertains to understanding the dynamics of hydrological factors and their potential responses to heatwave during warm seasons across the contiguous United States for the period from 2003 to 2022. Utilizing data from the Global Land Data Assimilation System (GLDAS), we analyzed surface runoff, evapotranspiration (ET), precipitation, Groundwater Storage (GWS), Root Zone Soil Moisture (RZSM), and Total Water Storage (TWS) to discern annual patterns and the impacts of heatwave. The spatial patterns of heatwave highlighted a higher occurrence in the western, central, and northeastern U.S., with longer average durations in the western and south-central regions. These events are predominantly dry, characterized by low Relative Humidity (RH), except in the southeastern U.S., where heatwave coincide with high RH levels. Post-heatwave analysis indicated a reduction in GWS, TWS, RZSM, and ET, alongside an increase in surface runoff, RH, and precipitation. An in-depth examination of rainfall and temperature dynamics during heatwave revealed weak correlations between rainfall and temperature, as well as between rainfall and heatwave duration, highlighting the complex nature of these interactions. The study also found an enhanced probability of rainfall following heatwave, particularly in the eastern regions, drawing attention to the potential for increased flood risks post-heatwave. Our findings contribute to the growing body of knowledge on the impacts of heatwave on hydrological factors, providing valuable insights for climate change adaptation and water resource management strategies. [ABSTRACT FROM AUTHOR]

Numerical investigations of the leading-edge sawtooth spoiler and slanted aft wall were performed to explore the mechanisms of the suppression of pressure fluctuations in an open-type cavity flow, focusing on the pressure fluctuation spectra and their spatial distributions. The rectangular cavity has a length-to-depth ratio of six, and the freestream Mach number is 1.5. Improved delayed detached-eddy simulation was used to predict the unsteady cavity flows and pressure fluctuations. Both control methods exhibited effectiveness in pressure fluctuation suppression, but their respective mechanisms are quite different. It was observed that the leading-edge sawtooth spoiler lifts the shear layer and reduces its interaction with the aft wall. The energy distribution of Rossiter modes changes significantly, which indicates that the pressure fluctuation feedback loop inside the cavity has changed. However, the slanted aft wall merely alters the cavity flowfield. Unlike the leading-edge method, the Rossiter mode distribution and the feedback mechanism remain unchanged. The slanted aft wall mainly suppresses the upstream-traveling perturbation generated by the cavity trailing edge but has little influence on the downstream-traveling perturbation. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (Li-S batteries) have attracted intense interest because of their high specific capacity and low cost, although they are still hindered by severe capacity loss upon cycling caused by the soluble lithium polysulfide intermediates. Although many structure innovations at the material and device levels have been explored for the ultimate goal of realizing long cycle life of Li-S batteries, it remains a major challenge to achieve stable cycling while avoiding energy and power density compromises caused by the introduction of significant dead weight/volume and increased electrochemical resistance. Here we introduce an ultrathin composite film consisting of naphthalimide-functionalized poly(amidoamine) dendrimers and graphene oxide nanosheets as a cycling stabilizer. Combining the dendrimer structure that can confine polysulfide intermediates chemically and physically together with the graphene oxide that renders the film robust and thin (<1% of the thickness of the active sulfur layer), the composite film is designed to enable stable cycling of sulfur cathodes without compromising the energy and power densities. Our sulfur electrodes coated with the composite film exhibit very good cycling stability, together with high sulfur content, large areal capacity, and improved power rate. [ABSTRACT FROM AUTHOR]

Rational design of multicomponent material structures with strong interfacial interactions enabling enhanced electrocatalysis represents an attractive but underdeveloped paradigm for creating better catalysts for important electrochemical energy conversion reactions. In this work, we report metal-phosphide core-shell nanostructures as a new model electrocatalyst material system where the surface electronic states of the shell phosphide and its interactions with reaction intermediates can be effectively influenced by the core metal to achieve higher catalytic activity. The strategy is demonstrated by the design and synthesis of iron-iron phosphide (Fe@FeP) core-shell nanoparticles on carbon nanotubes (CNTs) where we find that the electronic interactions between the metal and the phosphide components increase the binding strength of hydrogen adatoms toward the optimum. As a consequence, the Fe@FeP/CNT material exhibits exceptional catalytic activity for the hydrogen evolution reaction, only requiring overpotentials of 53-110 mV to reach catalytic current densities of 10-100 mA cm-2. [ABSTRACT FROM AUTHOR]

Background: Long non-coding RNA (lncRNA) H19 has been reported to involve in many kinds of human cancers and functions as an oncogene. Our previous study found that H19 was over-expressed in gallbladder cancer (GBC) and was shown to promote tumor development in GBC. However, the competing endogenous RNA (ceRNA) regulatory network involving H19 in GBC progression has not been fully elucidated. We aim to detect the role of H19 as a ceRNA in GBC. Methods and Results: In this study, the expression of H19 and miR-342-3p were analyzed in 35 GBC tissues and matched normal tissues by using quantitative polymerase chain reaction (qRT-PCR). We demonstrated H19 was overexpressed and negatively correlated with miR-342-3p in GBC. By dual-luciferase reporter assays, RNA-binding protein immunoprecipitation (RIP) and RNA pull-down assays, we verified that H19 was identified as a direct target of miR-342-3p. QRT-PCR and Western-blotting assays demonstrated that H19 silencing down-regulated, whereas over-expression enhanced the expression of miR-342-3p targeting FOXM1 through competitively 'sponging' miR-342-3p. Furthermore, transwell invasion assays and cell cycle assays indicated that H19 knockdown inhibited both cells invasion and proliferation, but this effects was attenuated by co-transfection of siRNA-H19 and miR-342-3p inhibitor in GBC cells. In vivo, tumor volumes were decreased significantly in H19 silenced group compared to the control group, but was attenuated by co-transfection of shRNA-H19 and miR-342-3p inhibitor, which were stablely constructed through lenti-virus vector. Conclusion: Our results suggest a potential ceRNA regulatory network involving H19 regulates FOXM1 expression by competitively binding endogenous miR-342-3p in GBC. This mechanism may contribute to a better understanding of GBC pathogenesis and provides potential therapeutic strategy for GBC. [ABSTRACT FROM AUTHOR]

Background Protein coding genes account for only about 2% of the human genome, whereas the vast majority of transcripts are non-coding RNAs including long non-coding RNAs. A growing volume of literature has proposed that lncRNAs are important players in cancer. HOTAIR was previously shown to be an oncogene and negative prognostic factor in a variety of cancers. However, the factors that contribute to its upregulation and the interaction between HOTAIR and miRNAs are largely unknown. Methods A computational screen of HOTAIR promoter was conducted to search for transcription-factor-binding sites. HOTAIR promoter activities were examined by luciferase reporter assay. The function of the c-Myc binding site in the HOTAIR promoter region was tested by a promoter assay with nucleotide substitutions in the putative E-box. The association of c-Myc with the HOTAIR promoter in vivo was confirmed by chromatin immunoprecipitation assay and Electrophoretic mobility shift assay. A search for miRNAs with complementary base paring with HOTAIR was performed utilizing online software program. Gain and loss of function approaches were employed to investigate the expression changes of HOTAIR or miRNA-130a. The expression levels of HOTAIR, c-Myc and miRNA-130a were examined in 65 matched pairs of gallbladder cancer tissues. The effects of HOTAIR and miRNA-130a on gallbladder cancer cell invasion and proliferation was tested using in vitro cell invasion and flow cytometric assays. Results We demonstrate that HOTAIR is a direct target of c-Myc through interaction with putative c-Myc target response element (RE) in the upstream region of HOTAIR in gallbladder cancer cells. A positive correlation between c-Myc and HOTAIR mRNA levels was observed in gallbladder cancer tissues. We predicted that HOTAIR harbors a miRNA-130a binding site. Our data showed that this binding site is vital for the regulation of miRNA-130a by HOTAIR. Moreover, a negative correlation between HOTAIR and miRNA-130a was observed in gallbladder cancer tissues. Finally, we demonstrate that the oncogenic activity of HOTAIR is in part through its negative regulation of miRNA-130a. Conclusion Together, these results suggest that HOTAIR is a c-Myc-activated driver of malignancy, which acts in part through repression of miRNA-130a. [ABSTRACT FROM AUTHOR]