Deviation of residual stress patterns in 52 100 bearing steel due to inherent microstructural transformations after rolling contact

A previous publication proved empirically that residual stresses in 52 100 bearing steel are caused mainly by microstructural transformations during rolling contact. It also introduced a model estimating the magnitude of residual stresses resulting from microstructural transformations. The results from this model prompted this study because the model showed a discrepancy between the measured results and the magnitude of the estimated residual stresses derived from the model. This study uses metallurgical analysis and modeling to explain why the measured and estimated magnitudes of residual stresses did not coincide. Metallurgical analysis explains the roles of retained austenite transformation and martensite decay in the ultimate magnitude of residual stresses at the surface of the bearing balls after rolling contact. The model estimates the magnitude of expected residual stresses due to martensite decay and suggests the number of cycles that bearing balls can operate under the beneficial effects of compressive residual stresses without spalling.     

Spontaneous splenic hypofunction in systemic lupus erythematosus and primary Sj?gren syndrome

The carbon catabolism of L-lysine starts in Saccharomyces cerevisiae with acetylation by an acetyl-CoA:L-lysine N6-acetyltransferase. The enzyme is strongly induced in cells grown on L-lysine as sole carbon source and has been purified about 530-fold. Its activity was specific for acetyl-CoA and, in addition to L-lysine, 5-hydroxylysine and thialysine act as acetyl acceptor. The following apparent Michaelis constants were determined: acetyl-CoA 0.8 mM, L-lysine 5.8 mM, DL-5-hydroxylysine, 2.8 mM, L-thialysine 100 mM. The enzyme had a maximum activity at pH 8.5 and 37 degrees C. Its molecular mass, estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, was 52 kDa. Since the native molecular mass, determined by gel filtration, was 48 kDa, the enzyme is a monomer.     

Effect of process parameter on the kerf geometry in abrasive water jet milling

This research work introduces a model to predict the kerf profile in abrasive water jet slot milling in aluminium 7075-T651. The experimentation allowed modelling the maximum cutting depth and the width at the half of maximum depth in terms of four process parameters: pressure, abrasive mass flow rate, stand-off distance, and traverse feed rate. It is shown that the introduction of the maximum depth and the width at the half of maximum depth in a Gaussian function is suitable to describe the kerf profile. The definition of an equivalent traverse feed rate at every instant along the jet trajectory introduces the effect of the jet acceleration in the model. Thus, the model is capable of predicting the kerf profile at constant traverse feed rate and at variable traverse feed rate due to direction changing trajectories. The variations of cutting depth along a slot are also studied in order to avoid the cutting parameters combinations which lead to low repetitiveness conditions and then irregular milling surfaces.     

Protection of deoxyribose and DNA from degradation by using aqueous extracts of several wild plants

BACKGROUND: Aqueous extracts of 48 herbal plants were obtained via alternative extraction protocols, and were assayed for their capacity to protect deoxyribose and DNA itself from degradation (or, conversely, for their capacity to promote DNA degradation), using electrophoresis as analytical tool. RESULTS: For a given (constant) volume of extract, deoxyribose protection ranged from 14.13 ± 1.35% (mean ± SD) inhibition by dwarf mallow powder infusion, up to 106.51 ± 15.93% inhibition by avocado powder infusion. DNA protection was tested at two extract concentrations, and was slightly greater at the higher concentration. Pro‐oxidant effects were essentially absent. CONCLUSION: The anti‐oxidative roles of plants upon deoxyribose and DNA displayed by our experimental results were rather promising with regards to practical applications of those plants, viz. as ingredients in the formulation of nutraceutical beverages and/or foods. Copyright © 2007 Society of Chemical Industry     

Theoretical analysis of the frictional losses in magnetohydrodynamic microflows considering slippage

In this article, we study the frictional losses in magnetohydrodynamic (MHD) microflows by analyzing the Poiseuille number defined through the Darcy–Weisbach friction factor. We consider two-dimensional fully developed flow models characteristic of MHD micropumps including the Hartmann braking effect and the existence of slippage. Unlike the purely hydrodynamic case, in MHD flows the Poiseuille number depends not only on the aspect ratio but also on the physical properties of the fluid and the externally applied magnetic field. Three different combinations of boundary conditions (slip and no-slip) are investigated. Calculations show that the Poiseuille number is considerably reduced as the dimensionless slip length is increased, while it increases as Hartmann number does. The obtained results are consistent with previous models and are helpful for the design of magnetohydrodynamic microflow devices.

     

Correction to: Indicator system for managing science,technology and innovation in universities

This study investigated the external contributors of library and information science (LIS) knowledge who were unaffiliated with LIS-related institutions but published their research results in LIS journals. Differences between the contributors to library science (LS) and contributors to information science (IS) were considered. Articles published in 39 strongly LIS-oriented journals indexed in the Web of Science database between 2005 and 2014 were analyzed. The results demonstrated that 46.5% of the LIS articles were written by at least one non-LIS author; authors’ backgrounds ranged across 29 disciplines. An increasing trend was observed in degrees of interdisciplinarity of LS and IS. An increase in proportion of articles by LIS and non-LIS authors was identified in LS and IS as well. Those with medical backgrounds were the primary non-LIS authors contributing to the LS field and collaborated the most frequently with LIS authors. Those with computer science backgrounds were the most prevalent non-LIS contributors to the IS field and preferred to publish individually. A critical difference was also identified in research topics between LS and IS. The foundations of LIS and scientometrics were the largest research topics in LS and IS, respectively.