Optimal design of vibration absorber using minimax criterion with simplified constraints

In this paper, a minimax design of damped dynamic vibration absorber for a damped primary system is investigated to minimize the vibration magnitude peaks. Moreover, to reduce the sensitivity of the primary system response to variations of the forcing frequency for a two- degree-of-freedom system, the primary system should have two equal resonance magnitude peaks. To meet this re- quirement, a set of simplified constraint equations includ- ing distribution characteristics of the resonant frequencies of the primary system is established for the minimax objective function. The modified constraint equations have less un- known variables than those by other authors, which not only simplifies the computation but also improves the accuracy of the optimal values. The advantage of the proposed method is illustrated through numerical simulations.

Correlation of p38MAPK,ERK1/2 and JNK expression in peripheral blood with the cytokines and pain mediators in patients with post-herpetic neuralgia

Objective: To study the correlation of p38MAPK, ERK1/2 and JNK expression in peripheral blood with the cytokines and pain mediators in patients with post-herpetic neuralgia (PHN). Methods: Patients who were diagnosed with herpes zoster for the first time in the Second Hospital of Hanbin District Ankang City between March 2015 and April 2016 were selected and divided into the PHN group who were combined with post-herpetic neuralgia and the pure HZ group who were without neuralgia, and the healthy volunteers who received physical examination in the Second Hospital of Hanbin District Ankang City during the same period were selected as control group. The peripheral blood was collected to determine the expression of MAPK signaling molecules, and serum was collected to determine the contents of cytokines and pain mediators. Results: p38MAPK, ERK1/2 and JNK mRNA expression in peripheral blood as well as 5-HT, CGRP, SP, NSE, S100B, IFN-γ, TNF-α and IL-17 levels in serum of PHN group and HZ group were significantly higher than those of control group while β-EP levels were significantly lower than that of control group;p38MAPK, ERK1/2 and JNK mRNA expression in peripheral blood as well as 5-HT, CGRP, SP, NSE, S100B, IFN-γ, TNF-α and IL-17 levels in serum of PHN group were significantly higher than those of HZ group while β-EP level was significantly lower than that of HZ group. p38MAPK, ERK1/2 and JNK expression in peripheral blood of PHN patients were positively correlated with CGRP, 5-HT, SP, NSE, S100B, IFN-γ, TNF-α and IL-17 levels in serum, and negatively correlated with β-EP level in serum. Conclusion: The high expression of p38MAPK, ERK1/2 and JNK in peripheral blood of PHN patients can increase the secretion of cytokines and algogenic mediators and decrease the secretion of analgesic mediators.

醇溶性高性能聚氨酯基透明涂层的制备及应用研究

随着环保要求的逐渐提高,高毒性有机溶剂的使用已成为制约聚氨酯(PU)基透明涂层生产和应用的主要原因,通过结构设计赋予PU醇溶性是制备绿色环保型透明涂层的有效策略.本研究以聚氧化丙烯二醇为软段,通过将异佛尔酮二异氰酸酯的脂环结构引入PU的硬段,赋予其醇溶性和透明性.通过傅里叶变换红外光谱仪表征PU基涂层的化学结构,采用紫外-可见分光光度计表征PU基涂层的醇溶性及光学性能,通过静态接触角测试观察PU基涂层的疏水性能,使用热重分析仪测定PU基涂层的热稳定性,并通过电子万能试验机分析硬段含量对PU基涂层力学性能的影响.此外,通过划格实验和耐腐蚀测试考察PU基涂层的应用性能.结果表明:具有大空间位阻的环型结构使得硬段中氨酯基团间的氢键作用较弱,而乙醇与氨酯基团间的氢键促进了PU基涂层的溶解,进而表现出良好的醇溶性.软段和硬段的非晶状态使得PU基涂层具有良好的透明性,但是随着硬段含量的增加,PU的微相分离程度提高,导致涂层的透光率降低,疏水性能略有降低,而拉伸强度明显提高.制备的醇溶性PU基透明涂层具有优异的疏水性、热稳定性、黏附性及耐腐蚀性,有望在光学器件、高端玻璃仪器等方面得到应用.

Manipulation of Na_(3)V_(2)(PO_(4))_(2)F_(3) via aluminum doping to alter local electron states toward an advanced cathode for sodiumion batteries

With its unique 3D skeleton structure and exceptional cyclic stability,the Na^(+)superionic conducto(NASICON)-type Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)has been con sidered as a competitive cathode material for advanced Na ion batteries.However,the release of fluorine during th heat treatment leads to the formation of an additional phas Na_(3)V_(2)(PO_(4))_(3)(NVP),which results in a low-voltage plateau and compromises the energy density.Herein,we modulat the local electronic states of the V site by aluminum sub stitution to strengthen the stability of F.The results confirm that the aluminum introduction not only changes the loca electron states of V sites,significantly reducing the for mation of NVP by-product from 6.71 wt%to 1.01 wt%but also effectively reduces the band gap,improving th electronic conductivity of NVPF.The optimized Na_(3)V_(1.9)Al_(0.1)(PO_(4))_(2)F_(3)exhibits higher energy density of 340 Wh·kg^(-1)and excellent rate performance of 106.7 mAh·g^(-1)at 10C compared with the pristine cathode.

Ni_(3)FeN anchored on porous carbon as electrocatalyst for advanced Li-S batteries

Lithium-sulfur(Li-S)battery is one of the newgeneration energy storage systems with great potential.However,the development of Li-S battery now is hampered by the shuttle effect and depressed redox kinetics.Herein,we report a composite of Ni_(3)FeN nanoparticles anchored in grid-like porous carbon(PC)spheres as an effective cathode electrocatalyst with simultaneous polysulfide trapping and rapid polysulfides conversion in Li-S battery.The multi-cavity structure of PC with high-efficiency encapsulation ability can significantly improve sulfur utilization and confinement.Furthermore,Ni_(3)FeN nanoparticles embedded in PC cavities render highly active catalytic sites to promote the redox conversion of solvated poly sulfide,as revealed by the electrochemical results.Moreover,the catalytic mechanism is further analyzed through density functional theory calculations and in-situ Fourier transform infrared analysis.As a result,PC@Ni_(3)FeN@S cathode delivers an outstanding capacity of 1294mAh·g^(-1)at 0.1C and low decay rates of 0.10%per cycle over 500 cycles at 0.5C.