关键词： CHEMICAL kinetics   BINARY metallic systems   MECHANICAL alloying   X-ray diffraction   MOSSBAUER spectroscopy   MECHANICAL energy  

摘要： X-ray diffraction and Mossbauer probe spectroscopy data on mechanically alloyed binary systems of the Si(Al, Mg, Cr)(99) Fe-57(1) composition have been analyzed within the framework of the energetic approach. It has been established that the initial stage of mechanical alloying is preceded by a "preparatory" period, during which grains of a main component (element) reach critical size L (cr), followed by the alloying process per se. It has been shown that, the maximum of derivative dN/d(logD) (N is the yield of reaction products, and D is the mechanical energy dose), with the maximum corresponding to grain size L (max) = 17 nm irrespective of the type of the main component, is a universal characteristic when considering the kinetics of the initial stage of alloying. The chemical interaction of a main component with Fe has been found to play the decisive role in the kinetics of mechanical alloying, with the significance of this role increasing in a series Mg, Al, Si, and Cr. A phenomenological explanation has been given to the linear N(D) dependence at the linear dependence of the specific surface area of grain boundaries on the mechanical energy dose.

关键词： Transfer matrix method   multibody system dynamics   Open CASCADE   virtual simulation   multiple launch rocket system  

摘要： The complex mechanical systems such as high-speed trains, multiple launch rocket system, self-propelled artillery, and industrial robots are becoming increasingly larger in scale and more complicated in structure. Designing these products often requires complex model design, multibody system dynamics calculation, and analysis of large amounts of data repeatedly. In recent 20years, the transfer matrix method of multibody system has been widely applied in engineering fields and welcomed at home and in abroad for the following features: without global dynamic equations of the system, low orders of involved system matrices, high computational efficiency, and high programming. In order to realize the rapid and visual simulation for complex mechanical system virtual design using transfer matrix method of multibody system, a virtual design software named MSTMMSim is designed and implemented. In the MSTMMSim, the transfer matrix method of multibody system is used as the solver for dynamic modeling and calculation;the Open CASCADE is used for solid geometry modeling. Various auxiliary analytical tools such as curve plot and animation display are provided in the post-processor to analyze and process the simulation results. Two numerical examples are given to verify the validity and accuracy of the software, and a multiple launch rocket system engineering example is given at the end of this article to show that the software provides a powerful platform for complex mechanical systems simulation and virtual design.

关键词： SELECTION rules (Nuclear physics)   PARTICLES (Nuclear physics) -- Chirality   MAGNETIZATION transfer   FIELD theory (Physics)   WAVE functions   PION-nucleon interactions   INTERMEDIATES (Chemistry)  

摘要： The nucleon's peripheral transverse charge and magnetization densities are computed in chiral effective field theory. The densities are represented in first-quantized form, as overlap integrals of chiral light-front wave functions describing the transition of the nucleon to soft pion-nucleon intermediate states. The orbital motion of the pion causes a large left-right asymmetry in a transversely polarized nucleon. The effect attests to the relativistic nature of chiral dynamics [pion momenta k=O(Mπ)] and could be observed in form factor measurements at low momentum transfer.

关键词： Impact-resistant propylene-ethylene   copolymer   beta-Nucleating agent   Crystallization kinetics   Nucleation activity   Morphology   Mechanical property   Heat deflection temperature  

摘要： beta-nucleated impact-resistant propylene-ethylene copolymer (IPC) samples were prepared via melt compounding. The isothermal and non-isothermal crystallization and melting behaviors of the samples were investigated by means of differential scanning calorimetry (DSC). Avrami equation was used to analyze the isothermal crystallization kinetics of the samples. The Lauritzen-Hoffman theory was applied and the nucleation constant Kg and the surface free energy sigma(e) was calculated. Jeziorny's and Mo's methods were used to analyze the non-isothermal crystallization kinetics of the samples. The activation energy (SE) of non-isothermal crystallization and the nucleating activity of the samples were calculated by Friedman's formula and Dobreva's method, respectively. The results show that the addition of beta-nucleating agent (NT-A and NT-C) decreases the Kg and sigma(e), so that the nucleation and crystallization rate of IPC is increased greatly under isothermal condition. Jeziorny's and Mo's methods well describe the non-isothermal crystallization kinetics of the samples. NT-C is more effective than NT-A as a beta-nucleating agent. It is also found that the addition of nucleating agent decreases the size and increases the number of spherulites significantly. The Izod notched impact strength and heat deflection temperatures (HDT) of IPC are also improved by the nucleating agents. (C) 2015 Elsevier B.V. All rights reserved.

关键词： NITROBENZENE   DECOMPOSITION (Chemistry)   STRONTIUM compounds   PHOTOCATALYSTS   ULTRAVIOLET radiation   CHEMICAL kinetics   AQUEOUS solutions  

摘要： In this article, the SrFeO3-delta photocatalyst was synthesized by a solution combustion method and applied for the photocatalytic degradation of aqueous nitrobenzene in the presence and absence of H2O2. The SrFeO3-delta photocatalyst was characterized by XRD, FT-IR, FE-SEM, TEM, TG-DTG, XPS, and UV visible spectroscopy. The band gap energy of SrFeO3-delta was found to be 3.75 eV which lies in the UV region. The XPS results indicate that the oxidation state of Sr and Fe in SrFeO3-delta was 2+ and 3+, respectively, and the surface atomic ratio of Sr and Fe is 0.995. The photocatalytic activity reveals that the degradation of nitrobenzene over the SrFeO3-delta catalyst itself (UV/SFO) is superior compared to SrFeO3-delta in the presence of H2O2 (UV/SFO/H2O2) with a degradation efficiency of 99-96%. The degradation of nitrobenzene obeys first-order kinetics in both UV/SFO and UV/SFO/H2O2 processes. The decrease in degradation efficiency with UV/SFO/H2O2 was attributed due to the formation of strontium carbonate on the photocatalyst surface.

关键词： walking pattern generation   powered prosthetic leg   motion capture  

摘要： In this paper, we describe the design procedure of an above-knee powered prosthetic leg and an algorithm to generate appropriate gait patterns that are synchronized with the movement of the user. The developed prosthetic leg has powered knee and ankle joints for transfemoral amputees, and its weight and dimensions were determined on the basis of human body data. In particular, two degrees of freedom (roll and pitch axes) were adopted in the ankle joint to achieve dynamic balance control on uneven ground, and passive toe joints using a crank-rocker mechanism and torsional springs were attached at the foot to increase the walking stability. In addition, we developed a walking pattern simulator that is able to test the walking patterns of the powered prosthetic leg in the air. By attaching two inertial sensors on both thighs of the user and measuring both thigh motions, the per cent of gait cycle is suitably calculated from the proposed algorithm, and smooth gait motions are generated according to the gait cycle percent. Finally, walking patterns of the powered prosthetic leg were successfully generated by synchronizing to the human gait, and the generated gaits were analyzed by comparing them to the human gait.

关键词： RARE earth metals   HYDRATION   GADOLINIUM   DYSPROSIUM   HOLMIUM   AB initio methods (Quantum mechanics)   MOLECULAR dynamics  

摘要： A theoretical study of dysprosium(III) and holmium(III) in aqueous solution based on a quantum mechanical charge field-molecular dynamics (QMCF-MD) simulation is presented. The obtained structural and dynamical data were found to be in good agreement with several experimental and theoretical data. It is shown that the coordination number is constantly switching between eight and nine adopting square antiprismatic and tricapped trigonal prismatic configurations, thus supporting the interpretation of experimental data. (C) 2015 Elsevier B.V. All rights reserved.

关键词： artificial   Catecholamines   Hemodynamics   Respiration   Respiratory insufficiency   Sedation   人工   儿茶酚胺类   呼吸   呼吸功能不全   血流动力学   镇静   Language of Keywords: English   Chinese  

摘要： Objective To observe the effect of two kinds of sedative method on the plasma catecholamine level and hemodynamics in respiratory failure patients with mechanic ventilation. Methods 54 respiratory failure patients needing tracheal intubation and mechanical ventilation in our hospital from January to December 2014 were selected and randomly divided into the control group(C), propofol+ fentanyl group (group P+F) and midazolam+fentanyl group (group M+F), 18 cases in each group. The plasma catecholamine content was detected before tracheal intubation, at 30 min, 3 h after tracheal intubation, meanwhile HR and BP at the corresponding time points were measured. Results Compared with pre-tracheal intubation, plasma catecholamine concentrations, HR and BP at 30 min after tracheal intubation in the group C were significantly increased compared with before tracheal intubation (P<0.05); plasma catecholamine concentrations, HR and BP at 30 min, 3 h after tracheal intubation in the group P+F and M+F were significantly decreased compared with before tracheal intubation, the differences were statistically significant (P<0.05). Furthermore, plasma catecholamine concentrations, HR and BP at 30 min after tracheal intubation in the group P+F and M+F were significantly decreased compared with the group C, the differences were statistically significant(P<0.05); however, there were no statistically significant differences in plasma catecholamine concentrations and HR at 30 min, 3 h after tra cheal intubation between the group P+F and M+F (P>0.05), but BP was significantly decreased with statistical difference (P<0.05). Conclusion Tracheal intubation and mechanical ventilation can enhance the level of plasma catecholamine, the sedation therapy can effectively reduce the blood catecholamine concentration in the patients with tracheal intubation and mechanical ventilation. Propofol+fentanyl and midazolam+fentanyl sedation can effectively alleviate the stress response of patients, but the se

关键词： alpha(v)beta(3) Integrin   Nanoparticles   siRNA   Stem-loop RT-qPCR   RGD peptidomimetic   Chitosan  

摘要： Integrin-targeted nanoparticles are promising for the delivery of small interfering RNA (siRNA) to tumor cells or tumor endothelium in cancer therapy aiming at silencing genes essential for tumor growth. However, during the process of optimizing and realizing their full potential, it is pertinent to gain a basic mechanistic understanding of the bottlenecks existing for nanoparticle-mediated intracellular delivery. We designed alpha(v)beta(3) integrin-targeted nanoparticles by coupling arginine-glycine-aspartate (RGD) or RGD peptidomimetic (RGDp) ligands to the surface of poly(ethylene glycol) (PEG) grafted chitosan-poly(ethylene imine) hybrid nanoparticles. The amount of intracellular siRNA delivered by alpha(v)beta(3)-targeted versus non-targeted nanoparticles was quantified in the human non-small cell lung carcinoma cell line H1299 expressing enhanced green fluorescent protein (EGFP) using a stem-loop reverse transcription quantitative polymerase chain reaction (RT-qPCR) approach. Data demonstrated that the internalization of alpha(v)beta(3)-targeted nanoparticles was highly dependent on the surface concentration of the ligand. Above a certain threshold concentration, the use of targeted nanoparticles provided a two-fold increase in the number of siRNA copies/cell, subsequently resulting in as much as 90% silencing of EGFP at well-tolerated carrier concentrations. In contrast, non-targeted nanoparticles mediated low levels of gene silencing, despite relatively high intracellular siRNA concentrations, indicating that these nanoparticles might end up in late endosomes or lysosomes without releasing their cargo to the cell cytoplasm. Thus, the silencing efficiency of the chitosan-based nanoparticles is strongly dependent on the uptake and the intracellular trafficking in H1299 EGFP cells, which is critical information towards a more complete understanding of the delivery mechanism that can facilitate the future design of efficient siRNA delivery systems. (C) 2015 Els

关键词： METAL-organic frameworks   COPPER   STRUCTURAL frames   NATIVE element minerals   X-rays  

摘要： A series of metal organic framework (MOP) materials has been prepared, each containing a mechanically interlocked molecule (MIM) as the linker and a copper(II) paddlewheel as the secondary building unit (SBU). The MIM linkers are [2]rotaxanes with varying sizes of crown ether macrocycles ([22]crown-6, 22C6;[24]crown-6, 24C6;[26]crown-6, 26C6;benzo[24]crown-6, B24C6) and an anilinium-based axle containing four carboxylate donor groups. Herein, the X-ray structures of MOFs UWCM-1 (no crown) and UWDM-1((22)) are compared and demonstrate the effect of including a macrocycle around the axle of the linker. The rotaxane linkers are linear and result in nbo-type MOFs with void space that allows for motion of the interlocked macrocycle inside the MOF pores, while the macrocycle-free linker is bent and yields a MOP with a novel 12-connected bcc structure. Variable temperature H-2 solid-state nuclear magnetic resonance showed that the macrocycles in UWDM-1((22)), UWDM-1((24)), and UWDM-1((B24)) undergo different degrees and rates of rotation depending on the size and shape of the macrocycle.