INFLUENCE OF A LEVELNESS DEFECT IN A THRUST BEARING ON THE DYNAMIC BEHAVIOUR OF AN ELASTIC SHAFT

This paper examines the non-linear dynamic behaviour of a flexible shaft. The shaft is mounted on two journal bearings and the axial load is supported by a defective hydrodynamic thrust bearing at one end. The defect is a levelness defect of the rotor. The thrust bearing behaviour must be considered to be non-linear because of the effects of the defect. The shaft is modelled with typical beam finite elements including effects such as the gyroscopic effects. A modal technique is used to reduce the number of degrees of freedom. Results show that the thrust bearing defects introduce supplementary critical speeds. The linear approach is unable to show the supplementary critical speeds which are obtained only by using non-linear analysis.     

Global Analysis of the Flows of Fluids with Pressure-Dependent Viscosities

 To describe the flows of fluids over a wide range of pressures, it is necessary to take into account the fact that the viscosity of the fluid depends on the pressure. That the viscosity depends on the pressure has been verified by numerous careful experiments. While the existence of solutions local-in-time to the equations governing the flows of such fluids are available for small, special data and rather unrealistic dependence of the viscosity on the pressure, no global existence results are in place. Our interest here is to establish the existence of weak solutions for spatially periodic three-dimensional flows that are global in time, for a large class of physically meaningful viscosity-pressure relationships. (Accepted May 1, 2002) Published online November 15, 2002 Communicated by S. S. ANTMAN     

The effects of mass accuracy,data acquisition speed,and search algorithm choice on peptide identification rates in phosphoproteomics

Proteomic analyses via tandem mass spectrometry have been greatly enhanced by the recent development of fast, highly accurate instrumentation. However, successful application of these developments to high-throughput experiments requires careful optimization of many variables which adversely affect each other, such as mass accuracy and data collection speed. We examined the performance of three shotgun-style acquisition methods ranging in their data collection speed and use of mass accuracy in identifying proteins from yeast-derived complex peptide and phosphopeptide-enriched mixtures. We find that the combination of highly accurate precursor masses generated from one survey scan in the FT-ICR cell, coupled with ten data-dependent tandem MS scans in a lower-resolution linear ion trap, provides more identifications in both mixtures than the other examined methods. For phosphopeptide identifications in particular, this method identified over twice as many unique phosphopeptides as the second-ranked, lower-resolution method from triplicate 90-min analyses (744 ± 50 vs. 308 ± 50, respectively). We also examined the performance of four popular peptide assignment algorithms (Mascot, Sequest, OMSSA, and Tandem) in analyzing the results from both high-and low-resolution data. When compared in the context of a false positive rate of approximately 1%, the performance differences between algorithms were much larger for phosphopeptide analyses than for an unenriched, complex mixture. Based upon these findings, acquisition speed, mass accuracy, and the choice of assignment algorithm all largely affect the number of peptides and proteins identified in high-throughput studies. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

基于相关性的中红外温度与发射率分离算法

温度和发射率是耦合在一起的.在精确获得大气参数的情况下,由传感器的辐射测量反演地表的温度与发射率,仍然是一个病态问题,必须采取一定的策略进行温度与发射率的分离.因此,温度与发射率的分离是红外遥感的核心问题.文章在分析无太阳直射光影响时大气下行辐射和含有大气残留的地表发射率之间关系的基础上,提出了一个针对野外测量中红外高光谱数据的温度与发射率分离算法.该算法利用大气下行辐射和含有大气残留的地表发射率之间的相关性作为判据来优化地表温度,进而获得地表发射率.基于模拟的中红外高光谱数据,对算法的精度进行评价.结果表明,该算法能够获得较高的地表温度和发射率反演精度;具有较广的适用范围,对测量过程中大气下行辐射变化不敏感;同时算法具有一定的抗噪性.     

FLUORESCENCE ENERGY TRANSFER BETWEEN DIMETHYLDIAZAPEROPYRENIUM DICATION AND ETHIDIUM INTERCALATED IN POLY d(A-T)

Dimethyldiazaperopyrenium is one of the largest known DNA intercalators. Fluorescence energy transfer occurred between dimethyldiazaperopyrenium (donor) and ethidium (acceptor) when these dyes were bound to a double-stranded polynucleotide such as poly d(A-T). The addition of increasing amounts of ethidium bromide led to a marked shortening of the fluorescence lifetime of the donor, whereas the excited state of the acceptor was progressively populated via energy transfer from the donor. Critical Förster distance between these two chromophores was calculated to be 3.8 nm. The observed transfer efficiency was lower than that calculated on the basis of this critical distance and a statistical distribution of bound drugs. These results are discussed taking into account the conformational change induced by intercalation of dimethyldiazaperopyrenium in the double-stranded polynucleotide.     

PHOTODYNAMIC INHIBITION OF ESCHERICHIA COLI DNA POLYMERASE I BY 8-METHOXYPSORALEN PLUS NEAR ULTRAVIOLET IRRADIATION

Abstract— Morphological abnormality due to the UV irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pukherrimus. When sperm was UV-irradiated and allowed to fertilize unirradiated eggs, the effect of the UV was manifested as an abnormal morphology of embryos in the gastrula or later stages. The UV-induced morphological abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. In the experiments on a stage-dependent change of PR effectiveness, it was found that an illumination sufficed to effect a nearly complete PR when applied up to the onset of the first DNA synthetic phase, while the PR effectiveness declined thereafter. Illumination after the completion of DNA synthesis had little effect for PR.     

多约束水平运输问题的时间费用均衡

基于为顾客提供最佳服务的现代营销理念,剖析了从一定产地到一定销地所发生的运输问题,构建了时间用均衡的目标模式及多目标约束水平MC^2运输问题的数学模型,本文在建立一系列定义,定理的基础上,提出了认明时间费用均衡解空间的优化决策方法,并结合示例展现了这一方法在解决客观实际问题中的有效性。     

Comparison of α CH and CF activation in alkyl transition metal complexes: a DFT and CASSCF study

DFT (B3PW91) and CASSCF calculations have been carried out to study the relative α migratory abilities of H and F in alkyl transition metal complexes. It is shown that the activation energy is considerably lower to migrate H than F, whereas the energies of reaction are similar for the two reactions. A study of the electron configurations and the orbitals describing these configurations shows that the high activation energy for F is due to a 4-electron repulsion between an F lone pair and the occupied Ru=C π orbital.     

Bis(salicylaldiminate) copper(II) and palladium(II) complexes: towards columnar mesophases

Copper and palladium complexes of new salicylaldimines derived from 3,4,5-tridecyloxyaniline, 2,3,4-tridecyloxyaniline and 4-decyloxyaniline have been synthesized and characterized. All the ligands bear four or more aliphatic chains with the aim of inducing columnar mesophases at low temperatures. In particular, metal complexes derived from 4-(3,4,5-tridecyloxybenzoyloxy)-salicyliden-3,4,5-tridecyloxyaninile display rectangular columnar mesophases at (or near) room temperature. These mesophase assignments have been confirmed by X-ray diffraction. A significant decrease of the melting points of the compounds is observed in the tridecyloxyaniline derivatives compared with those of similar complexes derived from mono- or di-decyloxyaniline.