微载荷含油轴承摩擦性能研究Ⅰ.摩擦试验机设计

研制了1种针对径向轴承的微载荷摩擦试验机,介绍了其工作原理及结构,即利用外加载荷抵消浮动测试架重量以施加微小载荷,并利用激光位置传感器(PSD传感器)实现无接触位移测量;同时测量了摩擦副的转动角度并计算出摩擦系数;采用摩擦转角测量法和外加力矩平衡摩擦法测量微载荷下的摩擦性能,以测量时间末端位置作为位置基准,通过极限偏载平衡进行载荷标定.结果表明:微载荷摩擦试验机可应用于径向轴承在微小载荷下的摩擦力测量;可以通过在较大范围内设置结构参数来研究径向轴承的摩擦特性;并可利用数据采集技术研究速度和载荷连续变化条件下的摩擦性能.     

Analysis of data transmission technique based on pulsed laser

Pulsed lasers are used mainly in lidar systems as sources of short and highly energetic light pulses. In data transmission systems continuous wave lasers are typically applied, however it is also possible to use pulsed lasers in such systems. Such approach seems to be especially reasonable for devices where a pulsed laser is applied anyway and executes another function (rangefinding). The article discusses a data transmission concept based on a pulsed laser technology. Advantages and limits of such a transmission method are described. Influence of individual transmission elements on the effective data transmission speed is analysed.     

Surface‐Plasmon‐Coupled Emission of Rhodamine 110 in a Silica Nanolayer

The first observation of strong directional surface‐plasmon‐coupled emission (SPCE) of Rhodamine 110 in silica nanofilms deposited on silver nanolayers is reported. The preparation of the material is described in detail. The intensity of SPCE exceeds 10 times that of free space fluorescence and total linear light polarization in the SPCE ring is observed. A new experimental setup and an original data collection method is presented. Our material completely preserves its fluorescence properties for at least eight months.     

ELEMENTAL SULFUR REACTIONS WITH 2-PICOLINE

Abstract

A study of the reaction of the elemental sulfur with 2-picoline is reported. The process was carried out at the boiling point of the 2-picoline under argon. After removing unreacted solids, the reaction products were identified by means of LC. GC and GC-MS. The following products have been identified by mass spectrometry: 1,2-di/2-pyridyl/-ethane. 1,2-di/2-pyridyl/-ethene. 2-methyl-x-[/2-pyridyl/methyl]pyridines, 2-mercapto-methyl-[x/2-pyridyl/methyl]-pyridines, l-mercapto-1,2-di/2-pyridyl/-ethane, 5,6-di/2-pyridyl/-5H-cyclopenta-[b]pyridine, 5,6-di/2-pyridyl/-7H-cyclopenta[b]pyridine, 1,2,3-tri/2-pyridyl/-propane. 1,2-di/2-pyridyl/-1-[x-/2-methyl/-pyridyl]-ethane, 5,6-di/2-pyridyl/-7-[/2-pyridyl/methyl]-7H-cyclopenta[b]pyridine, 5,6-di/2-pyridyl/-5-[/2-pyridyl/-methyl]-5H-cyclopenta-[b]pyridine. Di{7-[5,6-di/2-pyridyl/-7H-cyclopenta[b]pyridyl]} sulfide and di(7-[5,6-di/2-pyridyl/-7H-cyclopentalblpyridyl]} disulfide.     

Elimination of autofluorescence background from fluorescence tissue images by use of time-gated detection and the AzaDiOxaTriAngulenium (ADOTA) fluorophore

Sample autofluorescence (fluorescence of inherent components of tissue and fixative-induced fluorescence) is a significant problem in direct imaging of molecular processes in biological samples. A large variety of naturally occurring fluorescent components in tissue results in broad emission that overlaps the emission of typical fluorescent dyes used for tissue labeling. In addition, autofluorescence is characterized by complex fluorescence intensity decay composed of multiple components whose lifetimes range from sub-nanoseconds to a few nanoseconds. For these reasons, the real fluorescence signal of the probe is difficult to separate from the unwanted autofluorescence. Here we present a method for reducing the autofluorescence problem by utilizing an azadioxatriangulenium (ADOTA) dye with a fluorescence lifetime of approximately 15 ns, much longer than those of most of the components of autofluorescence. A probe with such a long lifetime enables us to use time-gated intensity imaging to separate the signal of the targeting dye from the autofluorescence. We have shown experimentally that by discarding photons detected within the first 20 ns of the excitation pulse, the signal-to-background ratio is improved fivefold. This time-gating eliminates over 96 % of autofluorescence. Analysis using a variable time-gate may enable quantitative determination of the bound probe without the contributions from the background.     

Applications of small iridium-based mercury electrodes to high concentrations of depolarizers

Voltammetric and microscopic data on the analytical properties of small iridium-based (127- μm diameter) mercury film electrodes are presented. A method of estimating and controlling the size of the deposit is described. The voltammetric behaviour of electrodes with mercury deposits varying from a film to a near-hemisphere is discussed for linear-scan, differential- and normal- pulse voltammetry. The systems Pb²⁺/Pb, Fe³⁺/Fe²⁺ and Co²⁺/Co, are used to show that, by changing the size of the deposit, either time-dependent or almost time-independent (steady-state) voltammograms can be obtained under the same instrumental conditions. Possible applications to the determination of high concentrations of depolarizers are outlined; voltammetric data for the determination of lead in the range 10–120 mM are presented. The evaluation of diffusion coefficients is discussed.     

Crystal growth, structure and electrical properties of thorium phosphorosulfide

Single crystals of thorium phosphorosulfide have been grown by the chemical vapour transport method. The X-ray diffraction examination showed that the unit cell of the crystals belongs to a tetragonal system of the PbFCl-type structure. The basal plane resistivity ρ(300 K)=64 μΩ cm and thermoelectric power S(300 K)=−7.7 μV/K, examined between 0.4 and 315 K, show metallic behaviour.     

Studies of photooxidative degradation of poly(vinyl chloride)/poly(ethylene oxide) blends

The photooxidative degradation of blends (in a full range of compositions) of amorphous poly(vinyl chloride) (PVC) with semicrystalline poly(ethylene oxide) (PEO) in the form of thin films is investigated using absorption spectroscopy (UV–visible and Fourier transform infrared) and atomic force microscopy (AFM). The amount of insoluble gel formed as a result of photocrosslinking is estimated gravimetrically. It is found that the PVC/PEO blendsí susceptibility to photooxidative degradation differs from that pure of the components and depends on the blend composition and morphology. Photoreactions such as degradation and oxidation are accelerated whereas dehydrochlorination is retarded in blends. The photocrosslinking efficiency in PVC/PEO blends is higher than in PVC; moreover, PEO is also involved in this process. AFM images showing the lamellar structure of semicrystalline PEO in the blend lead to the conclusion that the presence of PVC does not disturb the crystallization process of PEO. The changes induced by UV irradiation allow the observation of more of the distinct PEO crystallites. This is probably caused by recrystallization of short, more mobile chains in degraded PEO or by partial removal of the less stable amorphous phase from the film surface. These results confirm previous information on the miscibility of PVC with PEO. The mechanism of the interactions between the components and the blend photodegradation are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 585–602, 2004     

Microscopic theory of superfluid3He-superfluid4He solutions II. Acoustical approximation. Propagation of sounds

Linearized hydrodynamic equations for superfluid³He-superfluid⁴He solutions are examined. The addition of a new parameter, the velocity of the Fermi-pair condensate, increases the number of equations and, in consequence, the rank of the determinant of the equations. This leads to a new energy root of the determinant which describes an extra sound mode different from the first and second sound.     

Preparation and semiconducting properties of Th3As4

The resistivity, thermoelectric power and Hall constant in the temperature range of 78–830 K were determined for polycrystalline Th₃As₄ samples obtained by annealing thin thorium slabs in arsenic vapour. The samples examined were n-type semiconductors with a carrier concentration ranging from 1.0 × 10¹⁸cm^?3 to 2.8 × 10¹⁸ cm^?3 for which the effective mass was found to be equal to 0.55–0.76m₀. The Hall mobility, about 450cm²V^?1s^?1 at room temperature, obeys a $\text{T}{}^{\mathrm{<mtext>?3</mtext><mtext>2</mtext>}}$ law at high temperatures. On the basis of the electrical measurements the forbidden gap of Th₃As₄ was found to be equal to 0.43 eV.