Determination of Feasible Muscle Forces in Human Walking Using Static Optimization and Hill's Muscle Dynamics Constraints

Static optimization is a widely used technique for solving the redundant problem of muscle-force determination for given inverse dynamics. There are different cost functions, such as minimal metabolic energy, minimal forces, minimal fatigue, which lead to different results. One problem in this setting is that the resulting time histories of the ensuing equilibrium forces may not be feasible with respect to the muscle dynamics, i.e., the resulting force gradients at the muscle cannot be reproduced by the dynamics of the corresponding muscle. In this paper, a combined method is presented which takes into account the limitations induced by the muscle dynamics by applying static optimization techniques at each time step and prescribing minimal and maximal constraints for the forces by extrapolating the force values from previous steps using feasible muscle activation values. Thus, both the advantages of fast static optimization and the guarantee of feasible time histories of the muscle forces can be achieved. Moreover, joint forces turn out to be 20–40% higher in swing phase than those predicted with classical static optimization. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

巯基葡聚糖凝胶分离富集微乳液增敏三甲氧基苯基荧光酮光度法测定痕量锌

研究了微乳液介质中 ,pH =10 .4时 ,锌与三甲氧基苯基荧光酮 (TM PF)显色生成稳定的 1∶2络合物 ,于 5 80nm处摩尔吸光系数为 2 .94× 10 5L·mol-1·cm-1,锌含量在 0～ 0 .4g/L范围内符合比耳定律。引入微乳液介质 ,显著改善了锌的显色条件 ,使体系灵敏度提高。采用吸附容量大 ,且机械性能好的巯基葡聚糖凝胶分离富集 ,消除了共存离子的干扰 ,降低了测定体系的检出限。用所拟方法测定了施尔康药品、奶粉、味精、血清、尿样和发样中的锌 ,相对标准偏差低于 3.7% ;回收率在 95 .2 %～ 10 5 %。     

微乳液增敏钼(Ⅵ)-3′,5′-二溴水杨基荧光酮络合物光谱探针测定蛋白质

研究了在乳化剂OP微乳液介质中钼（Ⅵ）-3′,5′-二溴水杨基荧光酮(3′,5′-DBSF)-蛋白质体系的相互作用和吸收光谱情况。在最佳条件下,牛血清蛋白质含量在0～10mg／L范围内服从比尔定律;同时测得络合物与蛋白质的结合数n=93。乳化剂OP微乳液引入到蛋白质的测定中提高了体系的灵敏度。结果表明：该法具有很高的灵敏度、选择性和稳定性,可直接用于人尿、奶粉和人血清样品的定量测定。     

碘-淀粉光度法测定水中溶解氧含量

根据碘与淀粉反应生成蓝色络合物以及此络合物在574 nm波长处有吸收峰,提出了水样中溶解氧的光度测定法.为固定样品中的溶解氧,于碱性介质中加入硫酸锰与之形成三氧化二锰沉淀物.测定时加入硫酸使与沉淀物反应而释出所固定的氧,并立即与同时由溶液中已加入的碘化钾与硫酸反应而释出碘而使溶液中呈现蓝色.用光度法在574 nm波长处测得其吸光度.从由碘酸钾标准溶液作为溶解氧标准所制作的标准曲线上查得试样中溶解氧的含量,对显色的条件作了系统试验并选定了优化的反应条件,溶解氧的质量浓度在0.027～0.80 mg·L-1之间符合比耳定律.取3种不同来源的水样按此方法测定其溶解氧含量,所得结果与碘量法及溶解氧测定仪所测得的结果相符.     

Incompressible limits of the Navier-Stokes equations for all time

We study the asymptotic behaviors of the regular solutions to the compressible Navier-Stokes equations for “well-prepared” initial data for all time as the Mach number tends to zero, by deriving a differential inequality with certain decay property. The estimates obtained in this paper are uniform both in time and Mach number.     

无穷级亚纯函数的公共值与奇异方向

f（z）为无穷级亚纯函数,且σ（f）〈∞。本文证明了复平内存在奇异方向,f（z）与其k阶导函数f（k）（z）（k≥3）在这方向所对应的任意小角域内至多有两个不同的有穷公‘共值。     

High-performance air-stable n-type transistors with an asymmetrical device configuration based on organic single-crystalline submicrometer/nanometer ribbons

High-performance air-stable n-type field-effect transistors based on single-crystalline submicro- and nanometer ribbons of copper hexadecafluorophthalocyanine (F(16)CuPc) were studied by using a novel device configuration. These submicro- and nanometer ribbons were synthesized by a physical vapor transport technique and characterized by the powder X-ray diffraction pattern and selected area electron diffraction pattern of transmission electron microscopy. They were found to crystallize in a structure different from that of copper phthalocyanine. These single-crystalline submicro- and nanometer ribbons could be in situ grown along the surface of Si/SiO(2) substrates during synthesis. The intimate contact between the crystal and the insulator surface generated by the "in situ growing process" was free from the general disadvantages of the handpicking process for the fabrication of organic single-crystal devices. High performance was observed in devices with an asymmetrical drain/source (Au/Ag) electrode configuration because in such devices a stepwise energy level between the electrodes and the lowest unoccupied molecular orbital of F(16)CuPc was built, which was beneficial to electron injection and transport. The field-effect mobility of such devices was calculated to be approximately 0.2 cm(2) V(-)(1) s(-)(1) with the on/off ratio at approximately 6 x 10(4). The performances of the transistors were air stable and highly reproducible.     

Monolithic silica capillary column with coated cellulose tris(3,5-dimethylphenylcarbamate) for capillary electrochromatographic separation of enantiomers

Monolithic silica capillary columns were prepared by a sol-gel process in fused-silica capillaries with an inner diameter of 50 microm and were modified by coating of cellulose tris(3,5-dimethylphenylcarbamate). Influences of the factors in the modification process on enantiomer separations were investigated. The prepared columns were used to perform enantiomer separations by CEC. Fifteen and two pairs of enantiomers were separated under aqueous and nonaqueous mobile phases, respectively, and most of them were baseline-separated with very high column efficiencies. The Van Deemter curve was found flat under high linear velocity of the mobile phase, which indicated favorable kinetic properties of the prepared columns. Baseline separation of a pair of enantiomers was achieved in 90 s with high-column efficiency by short-end separation under high voltage.     

Capillary electrochromatography with zwitterionic stationary phase on the lysine-bonded poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolithic capillary column

A polymer-based neutral monolithic capillary column was prepared by radical polymerization of glycidyl methacrylate and ethylene dimethacrylate in a 100 mum id fused-silica capillary, and the prepared monolithic column was subsequently modified based on a ring opening reaction of epoxide groups with 1 M lysine in solution (pH 8.0) at 75 degrees C for 10 h to produce a lysine chemically bonded stationary phases in capillary column. The ring opening reaction conditions were optimized so that the column could generate substantial EOF. Due to the zwitterionic functional groups of the lysine covalently bonded on the polymer monolithic rod, the prepared column can generate cathodic and anodic EOF by varying the pH values of running buffer during CEC separation. EOF reached the maximum of -2.0 x 10(-8) m2v(-1)s(-1) and 2.6 x 10(-8) m2v(-1)s(-1) with pH of the running buffer of 2.25 and 10, respectively. As a consequence, neutral compounds, ionic solutes such as phenols, aromatic acids, anilines, and basic pharmaceuticals were all successfully separated on the column by CEC. Hydrophobic interaction is responsible for separation of neutral analytes. In addition, the electrostatic and hydrophobic interaction and the electrophoretic migration play a significant role in separation of the ionic or ionizable analytes.     

Spider's microstructure for sensing

The spider is well known for sensing the movements of air and preys. Bionics of the spider based on this principle is being paid great attention by many researchers. Here, this paper presents some detailed organs of the spider to make an attempt to clarify the sensing mechanism of the spider from the point view of physical structure by scanning electron microscopy. And behavior characteristics concerning sensing action are observed by optical microscopy. Compared with structures, some novel features of sense movements in micro- and nano-scale size and corresponding possible models are presented. At the same time, simple structure analysis is made to explain and prove this hypothesis.