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     

Structural properties of Zinc Lithium borate glass

Zinc Lithium Borate glasses of different composition were prepared with the aim of using it for thermoluminescence dosimetry. Melt quenching method was adopted in this process. Fourier transform Infrared (FTIR) spectroscopy and UV-vis-NIR spectroscopy techniques were employed to investigate the infrared spectra and energy band gap of different composition of Zinc Lithium Borate glasses. X-ray diffraction analysis was used to confirm the amorphous nature of the glass samples. Glass forming ability and stability of the glass was checked using Differential thermal analysis (DTA). Density, molar volume, refractive index parameters have been analyzed in the light of different concentration of the modifier. The active vibrational modes of 1200–1600 cm^?1 for B-O stretching of BO₃ units, 800–1200 cm^?1 for B-O stretching of BO₄ units and 400–800 cm^?1 for bending vibration of various borate segments were detected. Addition of ZnO to lithium borate shows its influence in converting the dominant BO₃ group to BO₄ group. BO₄ are known for creating complex defects, a situation that established deep and stable traps good for thermoluminescence phenomena. From optical data, direct and indirect energy band gap has been calculated using the data obtained from UV-vis-NIR spectroscopy. Both direct and indirect band gaps decrease with the increase of modifier Li₂CO₃.     

The effect of europium oxide impurity on the optical and physical properties of lithium potassium borate glass

The most hosts that is utilized in scientific application is borate glass. By using melt-quenching technique, five samples of lithium potassium borate (LKB) doped with different concentration of europium oxide (Eu₂O₃) were prepared. To investigate the influence of dopant on the optical and physical characteristics of the proposed glass, two methods have been applied (XRD, PL). The amorphous nature was confirmed by X-ray diffraction (XRD). The physical parameters of the glass matrix doped by different oxidation state have been analyzed, these parameters are density, molar volume, ion concentration, inter-nuclear distance, and polaron radius. The exchange in the concentration of Eu³⁺ indicated the influence of Eu as a dopant on the photoluminescence (PL) emission of LKB glasses. The emission spectrum of LKB:Eu³⁺ show a chain of emission bands, which are attributed to ⁵ D ₀-⁷ F _r (r = 1–4) transition of Eu³⁺. The luminescence studies showed four peaks 590 (yellow), 613 (orange), 650 (red), and 698 nm (red) for all samples except sample 0, the high luminescence efficiency is in emitting orange light at 613 nm.     

The effect of diallyl polysulfanes on cellular signaling cascades

Diallyl polysulfanes, such as diallyl trisulfide and diallyl tetrasulfide, are regarded as a group of potential chemopreventive compounds as they have been proven to be effective inhibitors of cancer cells. These agents have been implicated in signal transductions, including the generation of Reactive Oxygen Species (ROS), Endoplasmic Reticulum (ER) stress, mitogen-activated protein kinase (MAPK) signaling, regulation of cell cycle progression, and induction of apoptosis. Nonetheless, certain aspects of the diallyl polysulfane triggered inhibitory effects on cancer cells are still not clear. Understanding the targeted signaling pathways may help to develop new strategies to treat cancer and other diseases. This review is therefore aimed at addressing the targeting of specific intracellular signal transduction cascades by these diallyl polysulfanes in order to shed some light on possible mechanisms of action of these compounds.     

Characterization and electrochemical studies on poly(1-naphthylamine)-graphene oxide nanocomposites prepared by in situ chemical oxidative polymerization

Journal of Solid State Electrochemistry - Present work demonstrates the synthesis of novel poly(1-naphthylamine)-graphene oxide (PNA–GO) nanocomposites by the polymerization of NA in GO...     

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.