Mechanisms of additive effectiveness

Discusses the nature and extent of base oil-additive and additive-additive interactions. The first interaction is in the bulk oil phase, where solution chemistry is involved. The second interaction occurs at the wear surfaces. Various experimental techniques (DSC, TFOUT, FRT, Four ball) were used to measure interactions. In an examination of base oil-additive-interactions on oxidation stability, various species of base oils exert a strong influence on the performance of antioxidants. In additive-additive interactions, the data suggest a strong concentration of dependent interaction patterns among the various additives and the base oils. Mechanistic studies are recommended to elucidate some of the observed phenonema.     

软磁薄带（丝）的巨磁阻抗效应及其应用

介绍了居磁阻抗效应的来源，综述了它和样品的磁各向异性，驱动电流的频率，样品的电导率及厚度的关系，并简要介绍了它的应用。     

How to Evaluate and Forecast Changes in Landscape Image: The Case of a Small River Valley in Poland

River valleys play a key role in functioning landscape systems on a regional and continental level. Their ecological and cultural functions have developed simultaneously for centuries, creating a unique composition. Cultural heritage has grown from natural heritage and has enriched it wonderfully. However, river valleys have become areas of particularly intense human pressure for approximately the last two centuries, but especially over the last half century; changes occurring in the landscape are more and more drastic. The analysis and evaluation of these changes can therefore be a good indicator and predictor of changes that occur in the environment of entire (regional and transregional) landscape systems. This paper presents the method and results of landscape studies based on the sequence: retrospection—diagnosis—variant prognosis. The aim of the present work was to attempt to answer questions concerning the future direction of the development landscape physiognomy of small river valleys.     

Contact Fatigue under Oscillatory Normal Load

Experimental studies were made wherein contact fatigue was brought about by a cyclic variation of normal load applied to the contact between a ball and a flat specimen. Curves of flat-specimen temperature versus time showed that a rapid temperature rise occurred in the initial stage of crack formation rather than after the appearance of fully developed spalls; thus the temperature criterion appeared to provide an early indication of fatigue. Fatigue failure was observed in unlubricated as well as lubricated contact, but with much longer life when unlubricated.

Toroidal rings of hardened and softened material were noted both on and below the contact surface. These hardness variations bore symmetrical relationship to the contact geometry and were apparently related to the stress pattern.

It was found that the fatigue cracks did not initiate in the most severely hardened material but in the material adjacent to it. Further, the slope of the cracks tended to follow the boundary of the hardened region in general direction. Propagation of microcracks in this general direction appeared to be influenced by the prior austenitic grain boundaries. These microcracks at times appeared to propagate along carbide stringers.     

A novel tribometer for the measurement of friction in MEMS

A new tribometer has been developed to determine friction under conditions that are representative of MEMS (micro-electro-mechanical-systems). The tribometer consists of a rotating silicon disc, loaded against a stationary silicon disc. Friction and film thickness values are measured using laser displacement techniques. In this study, two different test set-ups were used: a flat on flat specimen geometry, and a moving flat against a structured surface, similar to that of a miniature thrust pad bearing. Using this tribometer, hydrodynamic tests have been carried out with the specimens fully submerged in hydrocarbon lubricants. Results suggest that friction increases with sliding speed and decreases with increasing applied normal load, which is in accordance with the hydrodynamic theory.     

300 mm硅片双面抛光运动轨迹模拟和优化

通过建立300 mm硅片双面化学机械抛光中硅片上定点相对于上下抛光垫的运动轨迹方程,分析了内外齿轮转速、抛光布转速对运动轨迹分布的影响,调整三者大小使得运动轨迹分布较均匀。实验证明运动轨迹路径长度与抛光去除厚度成正比关系,计算运动轨迹路径长度确定抛光垫的转速以达到上下表面具有相同的抛光速率。研究结果为300 mm硅片双面化学机械抛光找出优化工艺参数、提高硅片抛光后表面质量提供了理论依据。     

The bacterial battery and the effect of different exposure conditions on biofilm properties

A galvanic cell with pure copper and Al 2024 and Shewanella oneidensis MR-1 in Luria Bertani (LB) medium and a control cell, which did not contain the bacteria, have been tested. Potentiodynamic polarization experiments were used to determine cell voltage (V)-current (i) and power (P)-i curves as a function of time. The results for the cell without bacteria demonstrated that the maximum power output was obtained in the first day and dropped drastically in the following days. For the cell with MR-1 the power output of the cell increased slowly with time for around 100 days and remained at similar values for another 100 days. For pure Cu significant changes of the impedance spectra were found in the presence of MR-1. The impedance spectra resembled those usually observed for polymer-coated metals. In order to investigate this phenomenon in more detail, the effects of the different exposure conditions on the electrochemical behavior of copper were evaluated in LB containing MR-1. A second time constant was observed in the impedance spectra of copper that was partially immersed in the test solution (cell B). Complete immersion of copper in the electrolyte (no air/liquid interface) or deaeration of cell B resulted in one-time-constant spectra that are typical of those found for passive metals. Excellent corrosion protection was provided by MR-1 regardless of exposure condition. The corrosion potential increased with time for the Cu electrode exposed in cell B, while it decreased for the other two exposure conditions.     

Adolescent sexual behavior, drug use, and violence: increased reporting with computer survey technology

Surveys of risk behaviors have been hobbled by their reliance on respondents to report accurately about engaging in behaviors that are highly sensitive and may be illegal. An audio computer-assisted self-interviewing (audio-CASI) technology for measuring those behaviors was tested with 1690 respondents in the 1995 National Survey of Adolescent Males. The respondents were randomly assigned to answer questions using either audio-CASI or a more traditional self-administered questionnaire. Estimates of the prevalence of male-male sex, injection drug use, and sexual contact with intravenous drug users were higher by factors of 3 or more when audio-CASI was used. Increased reporting was also found for several other risk behaviors.     

Access control to two multiserver loss queues in series

We consider admission policies to two multiserver loss queues in series with two types of traffic. Both are generated according to independent Poisson processes with constant arrival rates. The first type requires service at the first queue and with a positive probability enters the second queue; the second type requires service at only the second queue. The service time distribution is exponential at either station. We show that under appropriate conditions the optimal admission policy that maximizes the expected total discounted reward over an infinite horizon is given by a switching curve. We characterize the form and shape of this curve and its variation with system parameters     

Co3O4 Nanoparticles with Ultrasmall Size and Abundant Oxygen Vacancies for Boosting Oxygen Involved Reactions

Ultrasmall size and abundant defects are two crucial factors for improving the performance of catalysts. However, it is a big challenge to introduce defects into ultrafine catalysts because of the surface tension and self‐purification effect of the nanoparticles. In the present work, physical laser fragmentation with chemical oxidization reaction is combined to synthesize Co₃O₄ nanoparticles (L‐CO) with ultrasmall size (≈2.1 nm) as well as abundant oxygen vacancies, thus providing an effective solution to the long‐standing contradiction between the size reduction and defect generation. The ultrasmall particle size allows more catalytic sites to be exposed. The surficial oxygen vacancies enhance the intrinsic activity, while the internal oxygen vacancies improve the electron transfer, and all of these benefits make L‐CO an active and durable bifunctional catalyst for oxygen reduction/evolutions. As the air cathode of zinc–air battery, L‐CO displays excellent rechargeable performance with a power density of ≈337 mW cm^?2, outperforming the commercial noble metal couple (Pt/C+RuO₂).