Powder mechanics in tribology

Recently considerable progress has been made in understanding the interactions between a surface and a solid lubricant layer deposited or formed by various physical and chemical methods. Very few studies have been conducted on how these films lubricate and fail from a microscopic point of view. In some of them it has been observed that lubrication and failure criteria are usually arbitrary and that particle interactions play a fundamental role as constituent elements of lubricant layers or as wear debris.To understand these mechanisms, “lubricating” and “abrasive” powders were studied from tribological and rheological point of view.Via classical mechanics, the flow properties of micronized powders were analysed in terms of size, shape and stress-strain relations. Starting from the cumminution process, crushing and grinding phenomena were analysed to determine experimentally through packing, cohesion and consolidation and ultimate shear strength and to predict the boundary friction coefficient in powder lubrication. The rupture surface and instability phenomena were involved for cohesive and noncohesive, “lubricating” and “abrasive” powders.The librication process was found to be very instable, consisting of the plastic flow of thin laminated films formed of coalesced fine particles and reactive films. The effect of substrate surface finish in terms of statistical moments criteria was demonstrated.The tribological process, analysed as particle mechanics of wear debris and as lubricating or abrasive powder interactions, was elucidated.     

Frontal Electroencephalogram Alpha Asymmetry During Sleep: Stability and Its Relation to Affective Style.

Electroencephalogram (EEG) alpha (8-12 Hz) asymmetries were collected from the mid-frontal and central regions during presleep wakefulness and Stage 1, Stage 2, and rapid eye movement (REM) sleep in 11 healthy right-handed participants who were free of psychiatric, neurological, and sleep problems. The authors found significant correlations between presleep wakefulness and different stages of sleep in the frontal, but not central, EEG alpha asymmetry measure. The strongest correlation was between presleep waking and REM sleep, replicating and extending relation earlier work to a normal population. The high degree of association between presleep waking and REM sleep may be a result of high cortical activation common to these states and may reflect a predisposition to different styles of emotional reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A randomized trial of a brief primary-care based intervention for reducing at-risk drinking practices.

This randomized trial evaluated an intervention for reducing at-risk drinking practices in a sample of 307 patients. Eligible drinking patterns included chronic drinking (≥ 2 drinks per day in the past month), binge drinking (≥ 5 drinks per occasion at least twice in the past month), and drinking and driving (driving after ≥ 2 drinks in the past month). Members of the intervention group received a message from their physician during their regularly scheduled visit, a self-help manual, written personalized feedback, and up to 3 telephone counseling calls. Dropout was significantly higher in the intervention than control group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning from the basics: Clinical implications of social, developmental, and cross-cultural study of the self.

This article serves as an introduction to a series aimed at informing psychotherapists about the current state of theory and research on the self across different domains of basic psychological science (i.e., social, developmental, and cross-cultural). The authors highlight several gaps in integration that continue to exist both within the field of psychotherapy, and across psychology as a whole and argue that such chasms serve to limit the applied utility of an abundance of scholarly work. The self is then presented as a potentially unifying construct that may begin to address such chasms. The overarching goal of this special series is to attempt a direct stimulation of science and practice, as well as cross-discipline integration, by presenting the clinical implications of the highly diverse study of the self. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The inflammatory response system and the availability of plasma tryptophan in patients with primary sleep disorders and major depression

Food restriction increases maximal life span in rodents. Male rats that exercise in voluntary running wheels do not have an increase in maximal longevity despite a relative caloric deficit. In contrast, sedentary rats that are food restricted so as to cause the same caloric deficit have an extension of maximal longevity. It seemed possible that exercise-induced oxidative stress might prevent a maximum life span-extending effect of a caloric deficit to manifest itself. This study was done to determine if antioxidants would allow a maximal longevity-extending effect of exercise to manifest itself in male rats. The antioxidant diet had no effect on longevity of the runners (Antiox., 951 +/- 158 days versus control 937 + 171 days), or of the sedentary controls (875 +/- 127 versus 858 +/- 152 days). As in previous studies, wheel running modestly increased average longevity (approximately 9%), but had no effect on maximal life span. The finding that antioxidants had no effect on longevity of the wheel runners supports the interpretation that the caloric deficit induced by exercise in male rats does not have a life-extending effect that is countered by oxidative tissue damage.     

Selective expansion of activated V delta 4+ cells during experimental infection of mice with Leishmania major

Previous work from this laboratory has revealed that infection of mice with Leishmania major leads to an expansion of gamma delta+ T cells in the spleen. Further examination of the gamma delta+ T cells expanding in infected mice has shown that the majority of these cells in the spleen, lymph nodes, blood and liver expressed the V delta 4 gene segment. Cell cycle analysis, using propidium iodide incorporation, demonstrated that while only 1% of alpha beta+ T cells in the spleen were in either S + G2/M phase, up to 10% of the gamma delta+ T cells were in cycling phase 8 weeks after infection. Comparison of the state of activation of the two populations in different organs after infection, confirmed that gamma delta+ T cells are actively dividing in lymph nodes, liver and blood, but not in the thymus or among intraepithelial lymphocytes. Examination of the expression of different activation markers on the surface of gamma delta+ T cells in the spleen of both normal and chronically infected BALB/c mice by FACS analysis, revealed increased expression of LFA-1, CD25, CD44, 4F2, CD28 and the heat-stable antigen, whereas Thy-1 and CD5 decreased. Collectively, these results suggest an oligoclonal expansion and activation of gamma delta+ T cells in response to L. major infection.     

Hot-carrier degradation behavior of N- and P-channel MOSFET's underdynamic operation conditions

An in-depth study of the dynamic hot-carrier degradation behavior of N- and P-channel MOS transistors was performed based on the change of charge pumping and I-V characteristics. It is shown that for transistors with channel lengths ranging from 2 to 0.5 μm and frequencies up to 100 MHz the degradation under dynamic stress can completely be described as a quasi-static degradation, provided all static degradation effects are taken into account in the appropriate way. This means that the influence of post-stress effects and charge buildup or charge detrapping have to be considered