Tribological properties and testing of bearings fabricated from hot-pressed silicon nitride-based ceramics

Results of studies of tribological properties of hot-pressed silicon nitride-based ceramics for fabrication of rolling bearings are reported.__________Translated from Novye Ogneupory, No. 10, pp. 50 – 56, October, 2004.     

Acquiring writing revision and self-regulatory skill through observation and emulation.

The influences of modeling and social feedback on the acquisition of writing revision were studied with 72 college students. Students watching a coping female model gradually improving her writing technique on a sentence-combining task were hypothesized to surpass students observing a mastery model perform the technique flawlessly on a writing-skill measure and an array of self-regulatory measures, such as self-satisfaction reactions, self-efficacy perceptions, and intrinsic interest in the task. Students observing a mastery model were expected, in turn, to surpass those learning without the benefit of modeling on these same measures. Support for both hypotheses was found. Social feedback during enactive performance assisted learners from all modeling groups in acquiring writing and self-regulatory skills. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance of New Biodegradable Di‐Sulfonate Surfactants as Hydrotropes in High‐Temperature and Salinity Environments

Propyl alkyl ether sulfonate (PAES) surfactants, recently developed by The Dow Chemical Company, show excellent electrolyte, hard water and caustic solubility, with attractive ECOTOX profile and biodegradability. Due to their unique structure and properties, they are good candidates for use as hydrotropes in formulations containing nonionic surfactants. The goal of these studies was to evaluate hydrotropic efficiency of PAES materials via cloud point analysis. The effects of PAES alkyl tail length, concentration, and mono‐ and di‐sulfonate components on the cloud point of TERGITOL? 15‐S‐9 in solutions of varying electrolyte strength were investigated. In the presence of high electrolyte levels, PAES 12C had the highest hydrotropic efficiency of all materials tested, including commonly used commercial hydrotropes. Di‐sulfonate components of the PAES materials were found to be more efficient hydrotropes than mono‐sulfonate in high electrolyte environments for all tail lengths tested. The di/mono ratio and tail length were found to be critical parameters.     

UNICORE 6 — Recent and Future Advancements

UNICORE is a European Grid Technology with more than 10 years of history. Originating from the Supercomputing domain, the latest version UNICORE 6 has turned into a general-purpose Grid technology that follows established standards and offers a rich set of features to its users. The paper starts with an architectural insight into UNICORE 6, highlighting the workflow features, standards and the different clients. Next, the current state of advancement is presented by describing recent developments. The paper closes with an outlook on future planned developments.     

Evaluating the combined effect of water activity,pH and temperature on ochratoxin A production by Aspergillus ochraceus and Aspergillus carbonarius οn culture medium and Corinth raisins

The objectives of this study were: (a) to evaluate the potential of the ELISA method in the determination of the produced OTA by Aspergillus ochraceus and Aspergillus carbonarius in malt extract agar (MEA) at different pH (3.9, 5.1, 5.9, 6.8), water activity (a_w) (0.87, 0.93, 0.99), and temperature (10, 15, 20, 25, 30, 40 °C) levels, providing a rapid screening for the optimum and marginal conditions of OTA production, (b) to comparatively evaluate the performance of ELISA and HPLC method, and (c) to evaluate the ability of A. ochraceus to produce OTA in rehydrated Corinth raisins during storage for 36 days. Two independent experiments were carried out to estimate OTA production on MEA and Corinth raisins. The produced OTA was evaluated qualitatively by the ELISA method and selected cases were verified by HPLC. The levels of OTA decreased with water activity, whereas pH seemed to have no specific effect. Furthermore, A. ochraceus produced maximum amounts of OTA on raisins at the 24th day of incubation, indicating that the endogenous microflora may restrictively affect OTA production. The knowledge of optimal and marginal levels of ecological factors in order to optimise post-harvest and storage of food products may significantly affect the production of OTA. Moreover, endogenous microflora of certain foodstuffs may cause OTA detoxification and consequently reduction of OTA levels; a fact that has to be taken into account in food commodities such as raisins, grapes, and wine.     

Biobehavioral approaches to the treatment of essential hypertension.

Despite recent advances in the medical management of hypertension, chronically elevated blood pressure remains a major health problem in the United States, affecting almost 50 million Americans. It is widely recognized that lifestyle factors contribute to the development and maintenance of elevated blood pressure. This article critically reviews current approaches to the nonpharmacological treatment of high blood pressure and highlights outcome studies of exercise, weight loss and dietary modification, and stress management and relaxation therapies. Methodological issues in the assessment and treatment of hypertension are discussed, along with possible mechanisms by which lifestyle modification may reduce elevated blood pressure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coupled heat conduction and thermal stress analyses in particulate composites

This study introduces two micromechanical modeling approaches to analyze spatial variations of temperatures, stresses and displacements in particulate composites during transient heat conduction. In the first approach, a simple micromechanical model based on a first order homogenization scheme is adopted to obtain effective mechanical and thermal properties, i.e., coefficient of linear thermal expansion, thermal conductivity, and elastic constants, of a particulate composite. These effective properties are evaluated at each material (integration) point in three dimensional (3D) finite element (FE) models that represent homogenized composite media. The second approach treats a heterogeneous composite explicitly. Heterogeneous composites that consist of solid spherical particles randomly distributed in homogeneous matrix are generated using 3D continuum elements in an FE framework. For each volume fraction (VF) of particles, the FE models of heterogeneous composites with different particle sizes and arrangements are generated such that these models represent realistic volume elements “cut out” from a particulate composite. An extended definition of a RVE for heterogeneous composite is introduced, i.e., the number of heterogeneities in a fixed volume that yield the same expected effective response for the quantity of interest when subjected to similar loading and boundary conditions. Thermal and mechanical properties of both particle and matrix constituents are temperature dependent. The effects of particle distributions and sizes on the variations of temperature, stress and displacement fields are examined. The predictions of field variables from the homogenized micromechanical model are compared with those of the heterogeneous composites. Both displacement and temperature fields are found to be in good agreement. The micromechanical model that provides homogenized responses gives average values of the field variables. Thus, it cannot capture the discontinuities of the thermal stresses at the particle-matrix interface regions and local variations of the field variables within particle and matrix regions.