一种基于分组密码的hash函数

提出了一个基于分组密码的hash函数体制,它的rate小于1但却具有更高的效率,同时,这个hash函数可以使用不安全的压缩函数进行构造,降低了对压缩函数安全性的要求.首先,在黑盒子模型下对这个新的体制的安全性进行了证明,然后给出了能够用于构造该体制的使用分组密码构造的压缩函数,最后通过实验对比发现,新hash函数的速度比rate为1的hash函数快得多.实验结果表明,除了rate以外,密钥编排也是影响基于分组密码hash函数效率的重要因素,甚至比rate影响更大.该体制只有两个密钥,不需要进行大量的密钥扩展运算,大大提高了基于分组密码hash函数的效率,而且该体制可以使用现有的分组密码来构造.

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.

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.

Direct Wafer Bonding Technology employing vacuum-cavity pre-bonding

A novel low temperature direct wafer bonding technology employing vacuum-cavity pre-bonding is proposed and applied in bonding of InGaAs/Si couple wafers under 300 degrees C and InP/GaAs couple wafers under 350 degrees C. Aligning accuracy of 0.5 mu m is achieved. During wafer bonding process the pressure on the couple wafers is 10MPa. The interface energy is sufficiently high to allow thinning of the wafers down from 350um to about 100um. And the tensile strength test indicates the bonding energy of bonded samples is about equal to the bonded samples at 550 degrees C.

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.