Li_8SiN_4-Li_3N-BN体系中立方BN转化行为的研究

研究了高温高压下x·Li_8SiN_4-0.1(1-x)·Li_3N-0.9(1-x)·BN体系中立方氮化硼(cBN)的转化行为。Li_8SiN_4的存在可显著改善cBN晶体的发育,提高晶体质量。在4.2～5.5GPa,1340～1750℃范围内确定了x=4.8％时体系的cBN转化区,并对转化区内cBN转化率、平均生长速度、成核速度及破碎强度与转化温度和压力的关系进行了研究。

Measurement of w-InN/h-BN Heterojunction Band Offsets by X-Ray Photoemission Spectroscopy

X-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being -0.30 +/- A 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 +/- A 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices.

巨大芽孢杆菌(Bacillusmegaterium)突变株Bn,B5的生物学特性及在Vc二步发酵中的伴生作用

对选出的巨大芽孢杆菌突变株Bn ,B5进行了生物学特性及发酵条件的研究 ,发现它们具耐低 pH和抗高浓 2KGA特性。可促进氧化葡萄糖酸杆菌生长 ,使其延迟期缩短 ,产酸增加。适宜的通气量下 ,摇瓶糖酸转化率提高 10 %～ 14% ;当发酵 pH为 6 .2～ 6 .6时 ,转化率提高 2 0 %～ 30 %

Formation of epsilon-FeXN/BN magnetic nanocomposite and its thermodynamic and kinetic analyses

A nanocomposite of nanometer-sized magnetic granular epsilon-FeXN embedded in a nonmagnetic amorphous boron nitride matrix was prepared by ball milling mixture of alpha-Fe and hexagonal boron nitride in argon atmosphere. The grain size of the epsilon-FeXN alloy was about 10-20 nm. The nitrogen concentration in the epsilon-FeXN alloy increases with extending milling time. Both thermodynamic calculation and the present experiment show that iron and nitrogen atoms have higher alloying driving force than iron and boron atoms. Analyses of thermodynamics and kinetics about formation of the epsilon-FeXN alloy suggested that the formation of the epsilon-FeXN alloy is related to amorphization of the hexagonal boron nitride and refinement of the alpha-Fe. II was found from the present experiment that a critical grain size of the alpha-Fe reacting with nitrogen in the amorphous boron nitride is about 8 nm.

添加剂Li_8SiN_4对cBN晶体形貌的影响

在４．５～５．０ＧＰａ，１５００～１８００℃范围内，在Ｌｉ基复合氮硼化物的催化体系中添加Ｌｉ８ＳｉＮ４后，得到了具有光泽的棕色透明的ｃＢＮ单晶。研究了ｃＢＮ晶体的形貌，结果表明，添加Ｌｉ８ＳｉＮ４后得到的等积形ｃＢＮ晶体的百分比明显增多，除部分截角四面体外，多为截角八面体晶体，且棱角尖锐，晶面致密光滑

Analysis of the strengthening and toughening of a biomaterial interface

Based on the transmission electron micrographs of nacre, the existence of mineral bridges in the organic matrix interface is confirmed. It is proposed that the microarchitecture of nacre should be considered as a "brick-bridge-mortar" (BBM) arrangement rather than traditional "brick and mortar" (BM) one. Experiments and analyses indicate that the mineral bridges effectively affect the strength and toughness of the interfaces in nacre. Comparison with a laminated composite with BM structure, SiC/BN, shows that the pattern of the crack extension and the toughening mechanism of the two materials are different. This reveals that the mineral bridges play a key role in the toughening mechanisms of nacre, which gives a conceptual guidance in material synthesis.

Structure and UV emission of nanocrystal ZnO films by thermal oxidation of ZnS films

ZnO films prepared by the thermal oxidation of the ZnS films through thermal evaporation are reported. The as-deposited ZnS films have transformed to ZnO films completely at 400 degrees C. The 400-700 degrees C annealed films with a preferential c-axis (002) orientation have a hexagonal wurtzite structure. The band gap of ZnO films shifts towards longer wavelength with the increase of the annealing temperature. The relationship between the band gap energy of ZnO films and the grain size is discussed. The shift of the band gap energy can be ascribed to the quantum confinement effect in nanocrystal ZnO films. The photoluminescence spectra of ZnO films show a dominant ultraviolet emission and no deep level or trap state defect emission in the green region. It confirms the absence of interstitial zinc or oxygen vacancies in ZnO films. These results indicate that ZnO film prepared by this simple thermal oxidation method is a promising candidate for optoelectronic devices and UV laser. (c) 2005 Elsevier BN. All rights reserved.

铃蟾肽

两栖类动物皮肤中富含多种与哺乳类动 物调节有关的活性肤，是获取多肤的巨大储 存库。铃蟾肤(Bombesin, BN)是1971年由 Erspamer和Anastasi等从欧洲铃蟾。. bombin。的皮肤中分离到的一种活性多肤。 1986年，国内陈枫等也从东方铃蟾B . o riento l皮肤中分离到了BN。人们对BN进行了 大量的研究，发现它具有广泛而复杂的生物 学效应。

眼镜蛇毒因子消耗补体对大鼠移植心急性排斥反应的抑制作用

目的 研究中华眼镜蛇毒因子(CVF)消耗补体对大鼠心脏移植急性排斥反应的影响.方法 以近交系BN大鼠为供者,Lewis大鼠为受者,建立腹腔异位心脏移植模型.实验分为2组,每组8只.CVF组:心脏移植术前3 d、2 d时,经受者尾静脉注射CVF 50 μg/kg;术前12 h至移植心停跳时,经尾静脉注射CVF 20 μg/kg,每2 d注射1次.对照组:术前、术后不给予受者任何特殊处理.术后观察移植心的存活时间,测定术后第1、3、5和6d及移植心停跳时的血清总补体活性(CH50法)、移植心C3沉积及CD3+T细胞浸润情况,并观察移植心的病理变化.结果 CVF组和对照组的移植心存活时间分别为(11.69±0.72)d和(6.65±0.35)d,两组比较,差异有统计学意义(P＜0.01).CVF组移植心组织内C3沉积和CD3+T细胞浸润程度均较对照组同期明显减轻,病理损害程度也较对照组同期明显减轻.结论 CVF消耗补体对大鼠心脏移植急性排斥反应起到了明显的抑制作用,从而延长移植心存活时间.