A complete symplectic eigenfunction expansion for the elastic thin plate with simply supported edges

The eigenvalue problem for the Hamiltonian operator associated with the mathematical model for the deflection of a thin elastic plate is investigated. First, the problem for a rectangular plate with simply supported edges is solved directly. Then, the completeness of the eigenfunctions is proved, thereby demonstrating the feasibility of using separation of variables to solve the problem. Finally, the general solution is obtained by using the proved expansion theorem.     

线极化高功率微波双工器空间谐波的选择性

 研究了一种用于GW级高功率微波耦合输出的新型线极化高功率微波双工器,该双工器由周期性的金属圆柱组成。对该双工器的Floquet空间谐波影响因素进行了讨论,得到了双工器空间谐波选择的重要规律,并以此设计了一个S/X波段线极化高功率微波双工器。对其进行的低功率冷测实验发现,该双工器对S/X波段的反射效率和透射效率分别高于97%。在进一步的高功率实验研究中,利用S和X波段1.8 GW,80 ns的高功率微波照射没有发现微波击穿。     

低磁场过模慢波结构型高功率毫米波发生器的改进

 利用粒子模拟的方法设计了一个高功率毫米波发生器,并对其进行了实验研究及改进。采用过模慢波结构以增大束波作用空间,从而提高功率容量;为实现过模慢波器件的单模、单频工作,选择TM01模的π模作为工作模式。采用过模慢波结构,结合合理的器件结构设计,可降低器件工作所需的导引磁场。实验在TORCH-01加速器平台进行,产生的微波频率由色散线法测量,其功率由远场积分法得到。最初的器件采用矩形波纹慢波结构,得到频率为33.56 GHz、功率约110 MW的微波输出,但功率难以进一步提高,脉宽仅为7~8 ns,且在慢波结构边沿发现击穿痕迹。对矩形慢波结构进行倒圆角处理后,借助数值模拟,发现其TM01模的π模频率变化不大。改进后的器件在0.8 T导引磁场下,当电压和电流分别为590 kV与5.2 kA时,实验得到频率33.56 GHz、功率320 MW的毫米波输出,微波模式为准TM01模,效率约10%,脉宽延长至约13 ns,器件内表面无明显击穿痕迹。     

Metal-free carbon-nitrogen bond-forming coupling reaction between arylboronic acids and organic azides

A novel and efficient metal-free carbon-nitrogen bond-forming coupling reaction between arylboronic acids and organic azides is reported. The reaction is fairly general for the preparation of secondary aromatic amines. Furthermore, the reaction is very functional-group tolerant. A possible mechanism is also proposed.     

聚(α,β-L-天冬氨酸丁酯)的合成及水解降解行为研究

以L-天冬氨酸为原料,采用热缩聚法合成聚琥珀酰亚胺.选用醇钠作为亲核试剂,开环反应得到聚(α,β-烷氧基-L-天冬氨酸).该聚合物部分水解制备两亲性聚天冬氨酸(PAsp-Na/PAsp-R).以聚(α,β-L-天冬氨酸丁酯)为例,利用UV、<'1>H NMR等方法研究聚合物的水解降解行为.通过<'1>H NMR中侧链酯基信号的消失和主链游离氨基在紫外光谱中吸光度的变化,证明水解降解过程包括侧链酯键的水解和主链酰胺键的适度裂解两部分,水解过程受环境温度和缓冲溶液pH的共同影响.水解速率具有温度响应性,环境温度越高水解速率越快(37℃时的水解速率>25℃时的水解速率).缓冲溶液pH对聚合物降解速率的影响顺序为:pH 12>pH4>pH 7.     

Binding of Puerarin to Human Serum Albumin: A Spectroscopic Analysis and Molecular Docking

Puerarin is a widely used compound in Chinese traditional medicine and exhibits many pharmacological activities. Binding of puerarin to human serum albumin (HSA) was investigated by ultraviolet absorbance, fluorescence, circular dichroism and molecular docking. Puerarin caused a static quenching of intrinsic fluorescence of HSA, the quenching data was analyzed by Stern–Volmer equation. There was one primary puerarin binding site on HSA with a binding constant of 4.12 × 10⁴ M⁻¹ at 298 K. Thermodynamic analysis by Van Hoff equation found enthalpy change () and entropy change () were −28.01 kJ/mol and −5.63 J/mol K respectively, which indicated the hydrogen bond and Van der waas interaction were the predominant forces in the binding process. Competitive experiments showed a displacement of warfarin by puerarin, which revealed that the binding site was located at the drug site I. Puerarin was about 2.22 nm far from the tryptophan according to the observed fluorescence resonance energy transfer between HSA and puerarin. Molecular docking suggested the hydrophobic residues such as tyrosine (Tyr) 150, Tyr 148, Tyr 149 and polar residues such as lysine (Lys) 199, Lys 195, arginine 257 and histidine 242 played an important role in the binding reaction.     

Synthesis and Properties of Novel Reactive Dyes Comprising Acyl Fluoride Group on Cotton Fabrics

Novel reactive dyes with mono- and bi-acyl fluoride reactive groups have been designed and synthesized, which are obtained by using 2-amino-8-naphthol-6-sulfonic acid or 1-amino-8-naphthol-3,6-disulfonicacid as the coupling component and 4-aminobenzoyl fluoride (PABF) as the diazo component. Their structures have been defined by nuclear magnetic resonance spectroscopy and ultraviolet–visible spectra (UV—Vis). The novel reactive dyes were evaluated on cotton by using the exhaust dyeing method. The properties were examined in detail, and the results showed that the dye concentration of 4% (o.w.f), pH = 9, and salt-free was the most effective condition. The fixation of the novel reactive dyes on cotton was 60.27% and 64.13%, respectively. The micro-fluorine-containing reactive dyes have favorable dyeing properties owing to the covalent bond formed between the reactive group of dyes and the functional group of cotton fibers, which can achieve salt-free dyeing of cotton.     

Self-shutdown function and uniform Li-ion flux enabled by a double-layered polymer electrolyte for high-performance Li metal batteries

Journal of Solid State Electrochemistry - Polymer electrolytes with high safety and high performance are considered to be one of the most promising candidates to upgrade the traditional...