Enhancing alkyne semi-hydrogenation through engineering metal-support interactions of Pd on oxides

Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene semi-hydrogenation as a model reaction,here we explore the optimization approaches toward better Pd catalysts for alkyne semi-hydrogenation through investigating support effect and metal-support interactions.The results show that the states of Pd with supports can be tuned by varying oxide reducibility,loading ratios,and post-treatments.In our system,0.06 wt.%Pd on rutile-TiO_(2) nanorods shows the highest activity owing to the synergistic effects of single-atoms and clusters.Support reducibility can change the filling degrees of Pd 4d orbitals through varying interfacial bonding strengths,which further affect catalytic activity and selectivity.

面向临床应用的抗菌肽:递送和剂型

抗菌肽作为传统抗生素的潜在替代物已经引起了人们的极大关注[1,2].虽然抗生素是人类对抗细菌感染的有效武器,但细菌种类的快速适应和抗生素的滥用导致了耐药菌株的出现和广泛传播.因此,迫切需要在机制上开发不同于现有抗生素的新抗菌方案.事实证明,抗菌肽有望替代抗生素成为一种理想的抗菌剂.除了具有显著的杀菌效果外,抗菌肽还能抑制生物膜的形成并破坏现有的生物膜[3].

Genetic and biological characteristics of the globally circulating H5N8 avian influenza viruses and the protective efficacy offered by the poultry vaccine currently used in China

The H5N8 avian influenza viruses have been widely circulating in wild birds and are responsible for the loss of over 33 million domestic poultry in Europe, Russia, Middle East, and Asia since January 2020. To monitor the invasion and spread of the H5N8 virus in China, we performed active surveillance by analyzing 317 wild bird samples and swab samples collected from 41,172 poultry all over the country. We isolated 22 H5N8 viruses from wild birds and 14 H5N8 viruses from waterfowls. Genetic analysis indicated that the 36 viruses formed two different genotypes: one genotype viruses were widely detected from different wild birds and domestic waterfowls;the other genotype was isolated from a whopper swan. We further revealed the origin and spatiotemporal spread of these two distinct H5N8 virus genotypes in 2020 and 2021. Animal studies indicated that the H5N8 isolates are highly pathogenic to chickens, mildly pathogenic in ducks, but have distinct pathotypes in mice. Moreover, we found that vaccinated poultry in China could be completely protected against H5N8 virus challenge. Given that the H5N8 viruses are likely to continue to spread in wild birds, vaccination of poultry is highly recommended in high-risk countries to prevent H5N8 avian influenza.

预防性抗菌治疗新策略:基于蛋白间相互作用抑制EPEC感染

细菌感染对人类生命构成了严重的威胁,1929年青霉素的发现为人类的抗菌战役提供了强有力的武器[1,2].随后,科研工作者发现了一系列的抗菌药物.然而,长期大量使用抗生素引发的耐药性问题日益严重,亟需探索基于新型抗菌机制的治疗策略[3~6].因此,本研究团队与香港中文大学夏江团队和山东大学李永强团队合作提出了通过蛋白之间相互作用而达到抑制相关信号通路传导,最终抑制细菌感染的抗菌新方法,该抗菌机制主要是针对宿主细胞而不是致病菌的预防性抗菌治疗,在Proc Natl Acad Sci USA上发表了题为“Safeguarding intestine cells against enteropathogenic Escherichia coli by intracellular protein reaction,a preventive antibacterial mechanism”的研究论文.

Insights from avian influenza surveillance of chickens and ducks before and after exposure to live poultry markets

Dear Editor, Live poultry markets are the major trading system of poultry in China and many other countries, and are also thought to be important for the generation and spread of avian influenza viruses and other avian pathogens (Zhang et al., 2013;Shi et al., 2017;Quan et al., 2018).

Folate-conjugated polyspermine for lung cancer–targeted gene therapy

Biodegradable polyamines have long been studied as potential recombinant viral gene vectors.Spermine(SPE) is an endogenous tetra-amine with excellent biocompatibility yet poor gene condensation capacity. We have previously synthesized a polyspermine based on SPE and poly(ethylene glycol)(PEG)diacrylate(SPE-alt-PEG) for enhanced transfection performance, but the synthesized SPE-alt-PEG still lacked specificity towards cancer cells. In this study, folic acid(FA) was incorporated into SPE-alt-PEG to fabricate a targeted gene delivery vector(FA-SPE-PEG) via an acylation reaction. FA-SPE-PEG exhibited mild cytotoxicity in both cancer cells and normal cells. FA-SPE-PEG possessed higher transfection efficiency than PEI 25 K and Lipofectamines2000 in two tested cancer cell lines at functional weight ratios, and its superiority over untargeted SPE-alt-PEG was prominent in cells with overexpressed folate receptors(FRs). Moreover, in vivo delivery of green fluorescent protein(GFP) with FA-SPE-PEG resulted in highest fluorescent signal intensity of all investigated groups. FA-SPE-PEG showed remarkably enhanced specificity towards cancer cells both in vivo and in vitro due to the interaction between FA and FRs. Taken together, FA-SPE-PEG was demonstrated to be a prospective targeted gene delivery vector with high transfection capacity and excellent biocompatibility.

Performance analysis and optimization of free cooling strategies for a liquid-cooled data center

The increasing power density of IT electronics and the enormous energy consumption of data centers lead to the urgent demand for efficient cooling technology.Due to its efficiency and safety,liquid-cooled heat sink technology may gradually replace air-cooled technology over time.With the ambient or higher water supply temperature,the liquid-cooled technology shortens the operating time of the chiller and improves its coefficient of performance,while the pump power consumption may increase for satisfying the constant cooling capacity.Therefore,it is significant to study the optimal water supply temperature to achieve energy-efficient operation of data centers.A virtual 30.1 kW data center is considered as the case,the liquid-cooled system is constructed with a combination of innovative manifold microchannel heat sink with oblique fins and indirect evaporative cooling technology to minimize energy consumption.A hybrid thermal management model integrating the heat dissipation model and the power consumption model is established by TRNSYS and FLUENT software.To the highest chip-safe operating temperature premise,the energy performance is analyzed under various water supply temperatures in Guangzhou.The result shows that only 21.5-hour mechanical cooling is needed with the 30℃server inlet temperature throughout the year.And the minimized power consumption occurs with the constant 29℃server inlet temperature.Moreover,the temperature adaptive control strategy(TACS)is adopted to test the cooling system power consumption under different regulation frequencies,and the by-week TACS can achieve another 11.5%energy saving than the minimum power consumption of the constant temperature control strategy.

Geometry independent C^(*)-T_(z) dominance of three-dimensional quasistatic growing crack-tip fields in creeping solids

In creeping solids,plane stress and plane strain solutions for asymptotic singular crack-tip fields have been first put forward by Riedel and Rice with C^(*)as the dominating parameter and developed by Xiang and Guo into three-dimensional solution(3D)for stationary cracks under the domination of C^(*)with the constraint factor Tz.However,how to characterize the 3D crack-tip fields under creep damage-induced quasistatic growing conditions remains challenging.In this study,we reveal that,for 3D quasistatic growing cracks,the leading singular solution can effectively characterize the crack-tip stress distributions with relative errors less than 10.8%for relative creep time up to 0.8 in various specimens with finite thickness.For a given relative time,Tz distributions can be unified by the equivalent thickness concept,Beq.The results show that C^(*)-T_(z) can effectively quantify both the load and constraint effects on the crack-tip fields.Such geometry independent dominance can considerably simplify the treatments of load and constraint effects,thereby promoting the application of fracture mechanics in high-temperature damage tolerance designs.

Symplectic Analysis on Coupling Behaviors of Spatial Fiexible Damping Beam

Although the complex structure-preserving method presented in our previous studies can be used to investigate the orbit–attitude–vibration coupled dynamic behaviors of the spatial flexible damping beam,the simulation speed still needs to be improved.In this paper,the infinite-dimensional dynamic model describing the orbit–attitude–vibration coupled dynamic problem of the spatial flexible damping beam is pretreated by the method of separation of variables,and the second-level fourth-order symplectic Runge–Kutta scheme is constructed to investigate the coupling dynamic behaviors of the spatial flexible damping beam quickly.Compared with the simulation speed of the complex structure-preserving method,the simulation speed of the symplectic Runge–Kutta method is faster,which benefits from the pretreatment step.The effect of the initial radial velocity on the transverse vibration as well as on the attitude evolution of the spatial flexible damping beam is presented in the numerical examples.From the numerical results about the effect of the initial radial velocity,it can be found that the appearance of the initial radial velocity can decrease the vibration frequency of the spatial beam and shorten the evolution interval for the attitude angle to tend towards a stable value significantly.In addition,the validity of the numerical results reported in this paper is verified by comparing with some numerical results presented in our previous studies.