Effect of a laser pre-quenched steel substrate surface on the crack driving force in a coating-steel substrate system

A mechanical model of a coating/laser pre-quenched steel substrate specimen with a crack oriented perpendicular to the interface between the coating and the hardened layer is developed to quantify the effects of the residual stress and hardness gradient on the crack driving force in terms of the J-integral. It is assumed that the crack tip is in the middle of the hardened layer of the pre-quenched steel substrate. Using a composite double cantilever beam model, analytical solutions can be derived, and these can be used to quantify the effects of the residual stress and the hardness gradient resulting from the pre-quenched steel substrate surface on the crack driving force. A numerical example is presented to investigate how the residual compressive stress, the coefficient linking microhardness and yield strength and the Young's modulus ratio of the hardened layer to the coating influence the crack driving force for a given crack length. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Physiological responses to capture and handling of free-ranging male Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

We captured free-ranging male Yangtze finless porpoises over three seasons and assayed leukocytes and serum biochemistry to investigate physiological responses to the capture and handlings. Serum thyroid hormones (THs) declined sharply in those porpoises compared with hormone variation in a captive male finless porpoise. Hypernatremia and hypokalemia were also significant in the free-ranging animals suggesting that conservation of serum sodium might be acutely vital for this freshwater subspecies. The animals captured in spring showed more significant neutrophilia and eosinopenia than those captured in autumn suggesting that they may be more affected by capture during the breeding season. Furthermore, physical examination of porpoises when out of the water was apparently stressful, particularly when they were kept out of the water for longer periods. However, an increase in circulating THs may be an adaptive response to accommodate these short-term stresses.

PURIFICATION AND CHARACTERIZATION OF A KINASE SPECIFIC FOR THE SERINE-RICH AND ARGININE-RICH PRE-MESSENGER-RNA SPLICING FACTORS

Members of the SR family of pre-mRNA splicing factors are phosphoproteins that share a phosphoepitope specifically recognized by monoclonal antibody (mAb) 104. Recent studies have indicated that phosphorylation may regulate the activity and the intracellular localization of these splicing factors. Here, we report the purification and kinetic properties of SR protein kinase 1 (SRPK1), a kinase specific for SR family members. We demonstrate that the kinase specifically recognizes the SR domain, which contains serine/arginine repeats. Previous studies have shown that dephosphorylated SR proteins did not react with mAb 104 and migrated faster in SDS gels than SR proteins from mammalian cells. We show that SRPK1 restores both mobility and mAB 104 reactivity to a SR protein SF2/ASF (splicing factor 2/alternative splicing factor) produced in bacteria, suggesting that SRPK1 is responsible for the generation of the mAb 104-specific phosphoepitope in vivo. Finally, we have correlated the effects of mutagenesis in the SR domain of SF2/ASF on splicing with those on phosphorylation of the protein by SRPK1, suggesting that phosphorylation of SR proteins is required for splicing.

Electron irradiation-induced defects in InP pre-annealed at high temperature

Electron irradiation-induced deep level defects have been studied in InP which has undergone high-temperature annealing in phosphorus and iron phosphide ambients, respectively. In contrast to a high concentration of irradiation-induced defects in as-grown and phosphorus ambient annealed InP, InP pre-annealed in iron phosphide ambient has a very low concentration of defects. The phenomenon has been explained in terms of a faster recombination of radiation-induced defects in the annealed InP. The radiation-induced defects in the annealed InP have been compared and studied. (c) 2006 Elsevier Ltd. All rights reserved.

Silicon nanowires grown on a pre-annealed Si substrate

Polycrystalline Si nanowires (poly SiNWS) were successfully synthesized by plasma-enhanced chemical vapor deposition (PECVD) at 440degreesC using silane as the Si source and Au as the catalyst. The diameters of Si nanowires range from 15 to 100nm. The growth process indicates that to fabricate SiNWS by PECVD, pre-annealing at high temperature is necessary. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique. (C) 2002 Elsevier Science B.V. All rights reserved.

The effects of pre-irradiation on the formation of Si1-xCx alloys

Carbon ions were implanted into crystal Si to a concentration of (0.6-1.5)at% at room temperature. Some samples were pre-irradiated with S-29(i)+ ions, while others were not pre-irradiated. Then the two kinds of samples were implanted with C-12(+) ions simultaneously, and Si1-xCx alloys were grown by solid phase epitaxy with high-temperature annealing. The effects of preirradiation on the formation of Si1-xCx alloys were studied. If the dose of implanted C ion was less than that for amorphizing Si crystals, the implanted C atoms would like to combine with defects produced during implantation, and then it was difficult for Si1-xCx alloys to form after annealine, at 950 degreesC. Pre-irradiation was advantageous for Si1-xCx alloy formation. With the increase of C ion dose, the damage produced by C ions increased. Pre-irradiation was unfavorable for Si1-xCx, alloy formation. If the implanted C concentration was higher than that for solid phase epitaxy solution, only part of the implanted C atoms form Si1-xCx alloys and the effects of pre-irradiation could be neglected. As the annealing temperature was increased to 1050 degreesC, Si1-xCx alloys in both pre-irradiated and unpreirradiated samples of low C concentration remained, whereas most part of Si1-xCx alloys in samples with high C concentration vanished.