Additional Mass: Orthotropic Membrane Material with Four Sides Fixed in Air Flow

When the membrane material in the air field vibrates, it will drive the movement of the surrounding air. The aerodynamic force generated by the moving air will act on the membrane material in turn, resulting in the change of dynamic characteristics such as membrane vibration frequency. In this paper, the additional air mass produced by membrane vibration in air is studied. Firstly, under the assumption that the incoming flow is uniform and incompressible ideal potential flow, the additional air mass acting on the surface is derived by using the thin airfoil theory and potential flow theory respectively. Then, according to the first law of thermodynamics and the principle of aeroelasticity, the analytical expression of the additional air mass is derived. Finally, through a specific example, the variation of the additional air mass with the membrane material parameters and pretension, as well as the influence of the aerodynamic force on the vibration frequency and amplitude of the membrane is obtained.

Cardiac Na^(+)-Ca^(2+) exchanger 1(ncx1h)is critical for the ventricular cardiomyocyte formation via regulating the expression levels of gata4 and hand2 in zebrafish

Ca^(2+) signaling is critical for heart development;however,the precise roles and regulatory pathways of Ca^(2+) transport proteins in cardiogenesis remain largely unknown.Sodium-calcium exchanger 1(Ncx1)is responsible for Ca^(2+) efflux in cardiomyocytes.It is involved in cardiogenesis,while the mechanism is unclear.Here,using the forward genetic screening in zebrafish,we identified a novel mutation at a highly-conserved leucine residue in ncx1 gene(mutant^(LDD353)/ncx1h^(L154P))that led to smaller hearts with reduced heart rate and weak contraction.Mechanistically,the number of ventricular but not atrial cardiomyocytes was reduced in ncx1h^(L154P) zebrafish.These defects were mimicked by knockdown or knockout of ncx1h.Moreover,ncx1h^(L154P) had cytosolic and mitochondrial Ca^(2+) overloading and Ca^(2+) transient suppression in cardiomyocytes.Furthermore,ncx1h^(L154P) and ncx1h morphants downregulated cardiac transcription factors hand2 and gata4 in the cardiac regions,while overexpression of hand2 and gata4 partially rescued cardiac defects including the number of ventricular myocytes.These findings demonstrate an essential role of the novel 154th leucine residue in the maintenance of Ncx1 function in zebrafish,and reveal previous unrecognized critical roles of the 154th leucine residue and Ncx1 in the formation of ventricular cardiomyocytes by at least partially regulating the expression levels of gata4 and hand2.

硫脲基聚酰亚胺/还原氧化石墨烯复合正极:碱金属离子储存机理的综合研究

尽管有机电极材料具有资源丰富、结构多样及环境友好等特点,但是它们的电化学性能仍然不理想.本文通过缩聚法合成了一种硫脲基聚酰亚胺/还原氧化石墨烯复合物.当其作为正极材料应用于锂离子电池时,展现出优异的电化学性能,如高可逆比容量(144.2 mA h g^−1),高放电电压(∼2.5 V)和长循环寿命(在500 mA g^−1电流密度下超过2000次),可以和其他发展较好的无机正极材料相媲美.当其作为正极材料应用于钠离子电池时,也可获得较好的电化学性能(在500 mA g^−1电流密度下循环寿命达800次),但是作为钾离子电池正极材料时的性能较差.理论计算表明羰基是和三种碱金属离子结合的活性位点,且插入的金属离子被邻位的两个羰基共用.更重要的是,硫原子和钾之间的作用力要远远大于和锂/钠之间的作用力,使得该聚合物在钾离子电池中表现出较差的可逆性和循环稳定性.我们的发现不仅为聚酰亚胺基的聚合物电极的设计和开发提供了理论基础,同时也为高性能的碱金属离子电池有机电极材料的设计和开发提供了帮助.

Amphichoterpenoids A-C,unprecedented picoline-derived meroterpenoids from the ascidian-derived fungus Amphichorda felina SYSU-MS7908

Amphichoterpenoids A-C(1-3),unprecedented picoline-derived meroterpenoids possessing a pyrano[3,2-c]pyridinyl-g-pyranone scaffold,were characterized from the ascidian-derived fungus Amphichorda felina SYSU-MS7908.Their structures were elucidated by spectroscopic methods,X-ray diffraction and electronic circular dichroism(ECD)calculations.A plausible biosynthetic pathway was proposed.The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase with 50%inhibiting concentration(IC_(50))values of 18.8-53.2 mmol/L.

Roussoelins A and B:two phenols with antioxidant capacity from ascidian-derived fungus Roussoella siamensis SYSU-MS4723

Ascidian-derived microorganisms are a signifcant source of pharmacologically active metabolites with interesting structural properties.When discovering bioactive molecules from ascidian-derived fungi,two new phenols,roussoelins A(1)and B(2),and ten known polyketides(3–12)were isolated from the ascidian-derived fungus Roussoella siamensis SYSU-MS4723.The planar structure of compounds 1 and 2 was established by analysis of HR-ESIMS and NMR data.The conformational analysis of the new compounds was assigned according to coupling constants and selective gradient NOESY experiments,and absolute confgurations were completed by the modifed Mosher’s method.Among the isolated compounds,1,2,and 9 showed moderate antioxidant capacity.