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41,608 result(s) for "Song, Chen"
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The living record of scientific history : conversations with CN Yang
Professor Chen-Ning Yang is best known for his achievements in Physics. He has also made significant contributions to the development of mathematics, as mathematics is extensively used in his research. In his long and fruitful academic career, he has witnessed many important events in the fields of Physics and Mathematics, and has collaborated or interacted with many great scientists in history. This book records eight interviews with Professor Chen-Ning Yang, which were conducted by the authors from 2016 to 2019. Through Professor Yang's unique perspective, major scientific events in the 20th century were revisited vividly, elaborating the development and mutual influences of mathematics and physics, as well as unveiling the academic work, the daily lives, and the personalities of scientists, as well as their collaboration and competition, some stories unknown to the public before are also revealed in this book.
Effects of phosphorus deficiency on the absorption of mineral nutrients, photosynthetic system performance and antioxidant metabolism in Citrus grandis
Phosphorus (P) is an essential macronutrient for plant growth, development and production. However, little is known about the effects of P deficiency on nutrient absorption, photosynthetic apparatus performance and antioxidant metabolism in citrus. Seedlings of ‘sour pummelo’ ( Citrus grandis ) were irrigated with a nutrient solution containing 0.2 mM (Control) or 0 mM (P deficiency) KH 2 PO 4 until saturated every other day for 16 weeks. P deficiency significantly decreased the dry weight (DW) of leaves and stems, and increased the root/shoot ratio in C . grandis but did not affect the DW of roots. The decreased DW of leaves and stems might be induced by the decreased chlorophyll (Chl) contents and CO 2 assimilation in P deficient seedlings. P deficiency heterogeneously affected the nutrient contents of leaves, stems and roots. The analysis of Chl a fluorescence transients showed that P deficiency impaired electron transport from the donor side of photosystem II (PSII) to the end acceptor side of PSI, which showed a greater impact on the performance of the donor side of PSII than that of the acceptor side of PSII and photosystem I (PSI). P deficiency increased the contents of ascorbate (ASC), H 2 O 2 and malondialdehyde (MDA) as well as the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in leaves. In contrast, P deficiency increased the ASC content, reduced the glutathione (GSH) content and the activities of SOD, CAT, APX and monodehydroascorbate reductase (MDHAR), but did not increase H 2 O 2 production, anthocyanins and MDA content in roots. Taking these results together, we conclude that P deficiency affects nutrient absorption and lowers photosynthetic performance, leading to ROS production, which might be a crucial cause of the inhibited growth of C . grandis .
Coordination modulation of hydrated zinc ions to enhance redox reversibility of zinc batteries
The dendrite growth of zinc and the side reactions including hydrogen evolution often degrade performances of zinc-based batteries. These issues are closely related to the desolvation process of hydrated zinc ions. Here we show that the efficient regulation on the solvation structure and chemical properties of hydrated zinc ions can be achieved by adjusting the coordination micro-environment with zinc phenolsulfonate and tetrabutylammonium 4-toluenesulfonate as a family of electrolytes. The theoretical understanding and in-situ spectroscopy analysis revealed that the favorable coordination of conjugated anions involved in hydrogn bond network minimizes the activate water molecules of hydrated zinc ion, thus improving the zinc/electrolyte interface stability to suppress the dendrite growth and side reactions. With the reversibly cycling of zinc electrode over 2000 h with a low overpotential of 17.7 mV, the full battery with polyaniline cathode demonstrated the impressive cycling stability for 10000 cycles. This work provides inspiring fundamental principles to design advanced electrolytes under the dual contributions of solvation modulation and interface regulation for high-performing zinc-based batteries and others. Zinc-based batteries suffer from the dendrite growth and surface passivation of zinc derived from the unfavourable deposition and side reactions. Here, the authors modulate the coordination chemistry of hydrated zinc ions via electrolyte-design and gain insights into the reversible cycling of long-lived zinc electrode.
Dialect connectedness and tunneling: evidence from China
PurposeThis study aims to examine the effects of dialect connectedness between the chairman and the chief executive officer (CEO) (DCCC) on the tunneling activities of controlling shareholders.Design/methodology/approachThis study uses abnormal related-party transactions (ARPT) as a proxy for tunneling activities and traces dialects of chairmen and CEOs based on the respective birthplace information. Baseline results are examined using a fixed-effects model. The results remain robust when using the instrumental variable approach, propensity score matching (PSM) technique, changing the measurement of tunneling and Heckman two-step selection model.FindingsThe results show that DCCC reduces tunneling activities. This negative association is more pronounced for non-state-owned enterprises and firms whose chairmen and CEOs work in the respective hometowns. DCCC restrains tunneling activities through mechanisms by establishing an informal supervisory effect on CEOs because the CEOs fear reputational damage and strengthening cooperation between chairmen and CEOs. Further analyses suggest that this negative association is more significant when chairmen and CEOs are non-controlling shareholders, but the association is weakened during the coronavirus disease 2019 (COVID-19) crisis.Originality/valueAs dialect is a carrier of culture, this study's results imply that cultural proximity can replace formal mechanisms to enhance corporate governance.
High-throughput sequencing of the transcriptome and chromatin accessibility in the same cell
Single-cell RNA sequencing can reveal the transcriptional state of cells, yet provides little insight into the upstream regulatory landscape associated with open or accessible chromatin regions. Joint profiling of accessible chromatin and RNA within the same cells would permit direct matching of transcriptional regulation to its outputs. Here, we describe droplet-based single-nucleus chromatin accessibility and mRNA expression sequencing (SNARE-seq), a method that can link a cell’s transcriptome with its accessible chromatin for sequencing at scale. Specifically, accessible sites are captured by Tn5 transposase in permeabilized nuclei to permit, within many droplets in parallel, DNA barcode tagging together with the mRNA molecules from the same cells. To demonstrate the utility of SNARE-seq, we generated joint profiles of 5,081 and 10,309 cells from neonatal and adult mouse cerebral cortices, respectively. We reconstructed the transcriptome and epigenetic landscapes of major and rare cell types, uncovered lineage-specific accessible sites, especially for low-abundance cells, and connected the dynamics of promoter accessibility with transcription level during neurogenesis.
The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis
Background To quantitatively summarize the available epidemiological evidence on the survival rate of out-of-hospital cardiac arrest (OHCA) patients who received cardiopulmonary resuscitation (CPR). Methods We systematically searched the PubMed, Embase, and Web of Science databases, and the references of retrieved articles were manually reviewed to identify studies reporting the outcome of OHCA patients who received CPR. The overall incidence and outcome of OHCA were assessed using a random-effects meta-analysis. Results A total of 141 eligible studies were included in this meta-analysis. The pooled incidence of return of spontaneous circulation (ROSC) was 29.7% (95% CI 27.6–31.7%), the rate of survival to hospital admission was 22.0% (95% CI 20.7–23.4%), the rate of survival to hospital discharge was 8.8% (95% CI 8.2–9.4%), the pooled 1-month survival rate was 10.7% (95% CI 9.1–13.3%), and the 1-year survival rate was 7.7% (95% CI 5.8–9.5%). Subgroup analysis showed that survival to hospital discharge was more likely among OHCA patients whose cardiac arrest was witnessed by a bystander or emergency medical services (EMS) (10.5%; 95% CI 9.2–11.7%), who received bystander CPR (11.3%, 95% CI 9.3–13.2%), and who were living in Europe and North America (Europe 11.7%; 95% CI 10.5–13.0%; North America: 7.7%; 95% CI 6.9–8.6%). The survival to discharge (8.6% in 1976–1999 vs. 9.9% in 2010–2019), 1-month survival (8.0% in 2000–2009 vs. 13.3% in 2010–2019), and 1-year survival (8.0% in 2000–2009 vs. 13.3% in 2010–2019) rates of OHCA patients who underwent CPR significantly increased throughout the study period. The Egger’s test did not indicate evidence of publication bias for the outcomes of OHCA patients who underwent CPR. Conclusions The global survival rate of OHCA patients who received CPR has increased in the past 40 years. A higher survival rate post-OHCA is more likely among patients who receive bystander CPR and who live in Western countries.
Recent Advances and Synergistic Effects of Non-Precious Carbon-Based Nanomaterials as ORR Electrocatalysts: A Review
The use of platinum-free (Pt) cathode electrocatalysts for oxygen reduction reactions (ORRs) has been significantly studied over the past decade, improving slow reaction mechanisms. For many significant energy conversion and storage technologies, including fuel cells and metal–air batteries, the ORR is a crucial process. These have motivated the development of highly active and long-lasting platinum-free electrocatalysts, which cost less than proton exchange membrane fuel cells (PEMFCs). Researchers have identified a novel, non-precious carbon-based electrocatalyst material as the most effective substitute for platinum (Pt) electrocatalysts. Rich sources, outstanding electrical conductivity, adaptable molecular structures, and environmental compatibility are just a few of its benefits. Additionally, the increased surface area and the simplicity of regulating its structure can significantly improve the electrocatalyst’s reactive sites and mass transport. Other benefits include the use of heteroatoms and single or multiple metal atoms, which are capable of acting as extremely effective ORR electrocatalysts. The rapid innovations in non-precious carbon-based nanomaterials in the ORR electrocatalyst field are the main topics of this review. As a result, this review provides an overview of the basic ORR reaction and the mechanism of the active sites in non-precious carbon-based electrocatalysts. Further analysis of the development, performance, and evaluation of these systems is provided in more detail. Furthermore, the significance of doping is highlighted and discussed, which shows how researchers can enhance the properties of electrocatalysts. Finally, this review discusses the existing challenges and expectations for the development of highly efficient and inexpensive electrocatalysts that are linked to crucial technologies in this expanding field.
The Ca2+ permeation mechanism of the ryanodine receptor revealed by a multi-site ion model
Ryanodine receptors (RyR) are ion channels responsible for the release of Ca 2+ from the sarco/endoplasmic reticulum and play a crucial role in the precise control of Ca 2+ concentration in the cytosol. The detailed permeation mechanism of Ca 2+ through RyR is still elusive. By using molecular dynamics simulations with a specially designed Ca 2+ model, we show that multiple Ca 2+ ions accumulate in the upper selectivity filter of RyR1, but only one Ca 2+ can occupy and translocate in the narrow pore at a time, assisted by electrostatic repulsion from the Ca 2+ within the upper selectivity filter. The Ca 2+ is nearly fully hydrated with the first solvation shell intact during the whole permeation process. These results suggest a remote knock-on permeation mechanism and one-at-a-time occupation pattern for the hydrated Ca 2+ within the narrow pore, uncovering the basis underlying the high permeability and low selectivity of the RyR channels. Although the permeation mechanisms for K + and Na + channels have been extensively studied, the ion permeation mechanism through Ca 2+ channels was largely unknown. Here the authors develop a multisite Ca 2+ model that can be used in the framework of classical MD simulations to study Ca 2+ in a quantitative manner, and use it to investigate the ion permeation mechanism of the ryanodine receptor 1.
Low-dose metformin targets the lysosomal AMPK pathway through PEN2
Metformin, the most prescribed antidiabetic medicine, has shown other benefits such as anti-ageing and anticancer effects 1 – 4 . For clinical doses of metformin, AMP-activated protein kinase (AMPK) has a major role in its mechanism of action 4 , 5 ; however, the direct molecular target of metformin remains unknown. Here we show that clinically relevant concentrations of metformin inhibit the lysosomal proton pump v-ATPase, which is a central node for AMPK activation following glucose starvation 6 . We synthesize a photoactive metformin probe and identify PEN2, a subunit of γ-secretase 7 , as a binding partner of metformin with a dissociation constant at micromolar levels. Metformin-bound PEN2 forms a complex with ATP6AP1, a subunit of the v-ATPase 8 , which leads to the inhibition of v-ATPase and the activation of AMPK without effects on cellular AMP levels. Knockout of PEN2 or re-introduction of a PEN2 mutant that does not bind ATP6AP1 blunts AMPK activation. In vivo, liver-specific knockout of Pen2 abolishes metformin-mediated reduction of hepatic fat content, whereas intestine-specific knockout of Pen2 impairs its glucose-lowering effects. Furthermore, knockdown of pen-2 in Caenorhabditis elegans abrogates metformin-induced extension of lifespan. Together, these findings reveal that metformin binds PEN2 and initiates a signalling route that intersects, through ATP6AP1, the lysosomal glucose-sensing pathway for AMPK activation. This ensures that metformin exerts its therapeutic benefits in patients without substantial adverse effects. The molecular target of the antidiabetic medicine metformin is identified as PEN2, a subunit of γ-secretases, and the PEN2–ATP6AP1 axis offers potential targets for screening for metformin substitutes.
High performance n-type Ag2Se film on nylon membrane for flexible thermoelectric power generator
Researches on flexible thermoelectric materials usually focus on conducting polymers and conducting polymer-based composites; however, it is a great challenge to obtain high thermoelectric properties comparable to inorganic counterparts. Here, we report an n-type Ag 2 Se film on flexible nylon membrane with an ultrahigh power factor ~987.4 ± 104.1 μWm −1 K −2 at 300 K and an excellent flexibility (93% of the original electrical conductivity retention after 1000 bending cycles around a 8-mm diameter rod). The flexibility is attributed to a synergetic effect of the nylon membrane and the Ag 2 Se film intertwined with numerous high-aspect-ratio Ag 2 Se grains. A thermoelectric prototype composed of 4-leg of the Ag 2 Se film generates a voltage and a maximum power of 18 mV and 460 nW, respectively, at a temperature difference of 30 K. This work opens opportunities of searching for high performance thermoelectric film for flexible thermoelectric devices. Although flexible thermoelectric materials based on conducting polymers are attractive for energy harvesting, their performance is inferior to their inorganic counterparts. Here, the authors present a facile method to deliver inorganic nanowire films with high power factor and flexibility.