ON THE RELATIONSHIP BETWEEN THE VACCO MODEL AND CHETAEV MODEL

In this paper,the geometric property and the mechanical property ofnon-holonomic constraints are studied.Vacco equation is obtained by using theclassical Hamilton principle.On the basis of Vacco equation,Chetaev condition isobtained by using mechanics principle of determining the ideal constraint.It is pointedout that the Vacco model is compatible with Chetaev model,so these two kinds ofmodels are unified.     

Copolymerization of ethylene with 1‐hexene promoted by novel multi‐chelated non‐metallocene complexes with imine bridged imidazole ligand

A series of novel bridged multi‐chelated non‐metallocene catalysts is synthesized by the treatment of N,N‐imidazole, N,N‐dimethylimidazole, and N,N‐benzimidazole with n‐BuLi, 2,6‐dimethylaniline, and MCl₄ (M = Ti, Zr) in THF. These catalysts are used for copolymerization of ethylene with 1‐hexene after activated by methylaluminoxane (MAO). The effects of polymerization temperature, Al/M molar ratio, and pressure of monomer on ethylene copolymerization behaviors are investigated in detail. These results reveal that these catalysts are favorable for copolymerization of ethylene with 1‐hexene featured high catalytic activity and high comonomer incorporation. The copolymer is characterized by ¹³C NMR, WAXD, GPC, and DSC. The results confirm that the obtained copolymer features broad molecular weight distribution (MWD) about 33–35 and high 1‐hexene incorporation up to 9.2 mol %, melting temperature of the copolymer depends on the content of 1‐hexene incorporation within the copolymer chain and 1‐hexene unit in the copolymer chain isolates by ethylene units. The homopolymer of ethylene has broader MWD with 42–46. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 417–424, 2010     

非完整系统动力学中的Vakonomic模型和Четаев模型

综述了非完整系统动力学中Чｅтａｅв模型和Ｖａｋｏｎｏｍｉｃ模型．论证了Ｈｅｒｔｚ,Ｃａｐｏｎ和Ｌｉｎｄｅｌｏｆ的工作与Ｖａｋｏｎｏｍｉｃ模型相吻合,而Ｈｏｌｄｅｒ,Ｐａｒｓ和Чаплыгин的工作与Четаев模型相吻合;Ｖａｋｏｎｏｍｉｃ模型和четаев模型两类模型并存的局面可以追溯到非完整力学发展的初期．说明了伴随两类模型并存的现象而出现的两个问题:ｄ－δ交换性问题和∫－δ交换性问题．综述了我国学者为统一两类模型作出的贡献．最后,展望了该领域的研究方向．      

ON THE UNIFICATION OF THE HAMILTON PRINCIPLES IN NONHOLONOMIC SYSTEM AND IN HOLONOMIC SYSTEM

ＯＮＴＨＥＵＮＩＦＩＣＡＴＩＯＮＯＦＴＨＥＨＡＭＩＬＴＯＮＰＲＩＮＣＩＰＬＥＳＩＮＮＯＮＨＯＬＯＮＯＭＩＣＳＹＳＴＥＭＡＮＤＩＮＨＯＬＯＮＯＭＩＣＳＹＳＴＥＭ（梁立孚）（韦扬）ＯＮＴＨＥＵＮＩＦＩＣＡＴＩＯＮＯＦＴＨＥＨＡＭＩＬＴＯＮＰＲＩＮＣＩＰＬ...     

基于可能性理论的结构模糊可靠性方法

利用模糊变量描述结构的不确定性 ,基于可能性理论和模糊区间分析 ,依据基于区间分析的非概率可靠性方法 ,建立了用于模糊结构和系统的能度可靠性模型。该模型可给出模糊可靠性指标的可能性分布和结构失效的可能性度量 ,并提供更多的关于结构安全程度的有用信息 ,且应用简便。算例分析说明了文中方法的应用     

论Vacco模型与Chetaev模型之间的关系

本文在深入研究非完整约束的几何性质和力学性质的基础上：（１）应用经典的Ｈａｍｉｌｔｏｎ原理推导出Ｖａｃｃｏ方程；（２）在Ｖａｃｃｏ方程的基础上，应用判定理想约束的力学原理，推导出Ｃｈｅｔａｅｖ条件，实现了从Ｖａｃｃｏ模型向Ｃｈｅｔａｅｖ模型的过渡；（３）论证了Ｖａｃｃｏ模型与Ｃｈｅｔａｅｖ模型是相辅相成的，从而统一了这两种模型。     

Detection of uranium with a wireless sensing method by using salophen as receptor and magnetic nanoparticles as signal-amplifying tags

A new wireless sensing method for the detection of uranium in water samples has been reported in this paper. The method is based on a sandwich-type detection strategy. Salophen, a tetradentate ligand of uranyl ion, was immobilized on the surface of the polyurethane-protected magnetoelastic sensor as receptor for the capture of uranyl ion. The phosphorylated polyvinyl alcohol coated magnetic Fe₃O₄ nanoparticles were used as signal-amplifying tags of uranyl ion. In a procedure of determining uranium, firstly uranyl ion in sample solution was captured on the sensor surface. Then the captured uranyl bound the nanoparticle through its coordination with the phosphate group. The amount of uranium was detected through the measure of the resonance frequency shift caused by the enhanced mass loading on the sensor surface. A linear range was found to be 0.2–20.0 μg/L under optimal conditions with a detection limit of 0.11 μg/L. The method has been applied to determine uranium in environmental water samples with the relative standard deviations of 2.1–3.6 % and the recoveries of 98.0–101.5 %. The present technique is one of the most suitable techniques for assay of uranium at trace level in environmental water samples collected from different sources.     

Experimental research on combustion dynamics of medium-scale fire whirl

The medium-scale fire whirl was extensively investigated by experimental means, in order to establish correlations of the burning rate, flame height and flame temperature of fire whirl, and to clarify the difference between fire whirls and general pool fires. Experimental observations and data confirmed that a free burning fire whirl is a highly stable burning phenomenon with large quasi-steady periods. Burning rates of fire whirls depend on pool diameter similarly to those of general pool fires; however the transition turbulent burning occurs sooner as the pool diameter increases. The lip height seems to have little effect on the burning rate of fire whirls. The correlation was proposed to couple the height of fire whirl to the fire release rate and ambient circulation. It correlates the data from both this work and the literature. Radial temperature profiles in the continuous region of the fire whirl were confirmed to be hump-type, implying the existence of fuel-rich inner core. The pool diameter and heat release rate do not significantly affect the radial temperature profiles in non-dimensional radial coordinates. It was found that the fire plume of fire whirl involves three distinct zones just like that of pool fire, but with different normalized ranges. Fire whirls maintain a higher ratio of continuous flame height to the overall flame height, and also higher maximum centerline excess temperature in continuous flame region, as compared to general pool fires. It was further demonstrated that the fire whirl plume at its origin behaves like a turbulent jet with moderate swirling, and then tends to become buoyancy dominated downstream, with slight swirling. With an increase in dimensionless height adjusted by the plume origin, the plume centerline excess temperature decays rapidly and approaches the theoretical value of −5/3 for free buoyancy plume.     

Untargeted Tumor Metabolomics with Liquid Chromatography–Surface‐Enhanced Raman Spectroscopy

Metabolomics is a powerful systems biology approach that monitors changes in biomolecule concentrations to diagnose and monitor health and disease. However, leading metabolomics technologies, such as NMR and mass spectrometry (MS), access only a small portion of the metabolome. Now an approach is presented that uses the high sensitivity and chemical specificity of surface‐enhanced Raman scattering (SERS) for online detection of metabolites from tumor lysates following liquid chromatography (LC). The results demonstrate that this LC‐SERS approach has metabolite detection capabilities comparable to the state‐of‐art LC‐MS but suggest a selectivity for the detection of a different subset of metabolites. Analysis of replicate LC‐SERS experiments exhibit reproducible metabolite patterns that can be converted into barcodes, which can differentiate different tumor models. Our work demonstrates the potential of LC‐SERS technology for metabolomics‐based diagnosis and treatment of cancer.