磷酸钾缓冲溶液与模型细胞膜相互作用的和频光谱

利用和频光谱技术详细研究了磷酸钾缓冲溶液与带负电荷的生物仿生膜(d₅₄-DMPG磷脂双层膜)相互作用的实时过程．通过监控CD₂、CD₃、磷脂分子头部的磷酸根以及羰基官能团的光谱信号随加入磷酸钾缓冲溶液的实时变化,获得了磷脂双层膜分子结构的动力学变化．结果表明K⁺能够结合到细胞膜上,并且很快地引起了CD₂、CD₃、磷脂头部磷酸根以及羰基官能团信号的变化．根据各官能团的和频信号响应,磷酸钾缓冲溶液很可能是通过在双层膜中形成环形气孔来与磷脂双层膜发生作用．该结果可以很好地解释磷酸钾缓冲溶液环境下的离子协助蛋白质的跨膜过程．     

Na2SO4 + NaCl molten salts corrosion mechanism of thermal barrier coatings used in ships

6–8 mass% Y₂O₃ stabilized ZrO₂ (6–8YSZ) thermal barrier coatings (TBCs) are widely applied to protect the hot ends of gas turbines in large navy ships. In this work, the 8YSZ TBCs were prepared by air plasma spraying technique, and their microstructure and phase composition were investigated. The hot corrosion mechanism of YSZ TBCs in molten salts consisting of 80% Na₂SO₄?+?20% NaCl at 900 °C was comprehensively analyzed. The results showed that the corrosion product Y₂(SO₄)₃ was formed due to the reaction between Na₂SO₄ media and the stabilizer Y₂O₃. As the result of the depletion of Y₂O₃ phase, the transformation from the tetragonal phase to monoclinic phase of ZrO₂ could not been totally inhibited, which consequently induced the 4–6 vol.% expansion and more cracks of YSZ TBCs. Meanwhile, the cracks could work as transfer paths for oxygen and molten salts. The kinetic analysis on hot corrosion also showed that more reaction products (from 2 to 8.1 mg cm^?1) were generated from 20 to 60 h due to more cracks generated by molten salts and oxygen infiltrating. More thermal grown oxides generated between ceramic layer, bonding layer and substrate, and the volume expansion caused by phase transition, increased the stresses in the coatings. Consequently, the peeling-off failure of 8YSZ TBCs could happen.

     

疫情影响下的全球治理：碎片化与中等强国的角色

世界正面临着第二次世界大战以来最严重的全球危机。不仅各国政府正在尽其所能改善国内公共卫生管理,而且国际社会也迫切需要改善全球治理。然而,面对这场全球性危机,世界没有应有的团结。相反,美国推进对抗性竞争战略以维护世界霸权,其政客试图将预防和控制政治化,破坏全球协调机制。这使得全球治理的缺陷进一步暴露,碎片化趋势进一步呈现,大国竞争及权势转移的趋势更为明显。可预见的未来,全球治理进程更有可能采用区域形式。适应全球治理的迫切需求,中等强国在全球治理中的多重作用空间显著扩大,多数选择平衡外交政策,力主践行多边主义,扮演“催化剂”“搭桥者”角色,赢得全球影响力;不过“追随者”角色也让部分中等强国暴露出能力上的弱点与外交独立性的不足。     

A sensitive porphyrin/reduced graphene oxide electrode for simultaneous detection of guanine and adenine

Journal of Solid State Electrochemistry - In this study, we prepared the porphyrin/reduced graphene oxide (porphyrin/RGO) nanocomposite which combined the excellent electrical conductivity and high...     

A RELATIVE BENEFIT ALGORITHM FOR BASIC ECONOMIC LOT SIZE PROBLEM

1 IntroductionMany problems in inventory control, production planning can be formulated in terms of asimple economic lot size model proposed by H.M.wagner and T.M.Whitin(1958). Since 1958, theManne-Wagner-Ehitin model has received considerable attention, and several hundred paPershave directly or ndirectly discus8ed this model; most Of these paper8 have either eXtended thismodel or proYided efficient algorithms for production problems that arise in it. (In particular,see Florian, Lenstra…     

与GA-凸函数有关的若干单调函数

利用GA-凸函数的定义及其Hermite-Hadamard型不等式,得到与GA-凸函数有关的若干单调函数.     

In situ synthesis of crosslinked-polyaniline nano-pillar arrays/reduced graphene oxide nanocomposites for supercapacitors

Crosslinked-polyaniline (CPA) nano-pillar arrays adsorbed on the surface of reduced graphene oxide (RGO) sheets were synthesized by in situ solution polymerization through two steps of reduction. The electrochemical analyses demonstrated that the befittingly reduced CPA/RGO composite exhibited high performance as electrode materials for supercapacitors. The CPA/RGO composite showed very high specific capacitance of 1532 F g^?1 at a scan rate of 10 mV s^?1 or 694 F g^?1 at a current density of 2 A g^?1 in 1 M H₂SO₄ electrolyte, as well as great energy density of 61.4 W h kg^?1 at a current density of 2 A g^?1. The electrode material also had decent power density of 4 kW kg^?1 at a current density of 10 A g^?1, and good cycling stability of 92.5 % capacitance retained after 500 cycles of cyclic voltammetry at 500 mV s^?1. The neat microstructures and super electrochemical properties suggest the potential use of the composites in supercapacitors.     

Interaction between Potassium Phosphate Bu er Solution and Modeling Cell Membrane Investigated by Sum Frequency Generation Vibrational Spectroscopy (cited: 1)

Potassium phosphate buffer solution has been widely used in the biological experiments, which represents an important process of the interaction between ions and biomolecules, yet the in fluences of potassium phosphate on biomolecules such as the cell membrane are still poorly understood at the molecular level. In this work, we have applied sum frequency generation vibrational spectroscopy and carried out a detailed study on the interaction between potassium phosphate buffer solution (PBS) and negative 1,2-dimyristoyl-d₅₄-sn-glycero-3-[phospho-rac-(1-glycerol)] (d₅₄-DMPG) lipid bilayer in real time. The PBS-induced dynamic change in the molecular structure of d₅₄-DMPG lipid bilayer was monitored using the spectral features of CD₂, CD₃, lipid head phosphate, and carbonyl groups for the first time. It is found that K⁺ can bind to the cell membrane and cause the signal change of CD₂, CD₃, lipid head phosphate, and carbonyl groups quickly. Potassium PBS interacts with lipid bilayers most likely by formation of toroidal pores inside the bilayer matrix. This result can provide a molecular basis for the interpretation of the effect of PBS on the ion-assisted transport of protein across the membrane.     

Solving fuzzy multi-objective linear programming problems using deviation degree measures and weighted max–min method

This paper proposes a method for solving fuzzy multi-objective linear programming (FMOLP) problems where all the coefficients are triangular fuzzy numbers and all the constraints are fuzzy equality or inequality. Using the deviation degree measures and weighted max–min method, the FMOLP problem is transformed into crisp linear programming (CLP) problem. If decision makers fix the values of deviation degrees of two side fuzzy numbers in each constraint, then the δ-pareto-optimal solution of the FMOLP problems can be obtained by solving the CLP problem. The bigger the values of the deviation degrees are, the better the objectives function values will be. So we also propose an algorithm to find a balance-pareto-optimal solution between two goals in conflict: to improve the objectives function values and to decrease the values of the deviation degrees. Finally, to illustrate our method, we solve a numerical example.