快速凝固过程中的多定态与非晶转变

注意到非晶转变实际上是在严重的非平衡凝固条件下发生的一种物理现象，运用非线性理论分析了快速凝固条件下的非晶转变的动力学过程，并建立了非晶转变的分支理论模型，结果表明：由于冷却条件严重的非平衡性及凝固速度与凝固温度之间的非线性耦合，在快速凝固条件下，凝固纱可产生多定态现象，而这种多定态现象可以被理解为非晶转变，该交好地解释发生非晶转变时的实验特点，并能预测金属及合金形成非晶的临界冷却速度及非晶转变点     

SPS过程中导电粉体的显微组织演变规律及机理

放电等离子烧结(spark plasma sintering, SPS)是最近几年国际上兴起的粉末烧结新技术, 具有升温速度快、保温时间短、冷却迅速等独特优势, 尤其适于纳米及非晶块体材料、陶瓷和梯度材料等先进材料的制备. 然而, 与利用SPS技术探索新材料制备的实验报道相比, 有关其特殊烧结机制的研究极为缺乏. 基此, 选用导电的纯金属铜粉作为烧结原料, 设计了一系列烧结实验, 研究得出了SPS过程几个重要的特征烧结阶段及其中显微组织演变的规律. 提出了SPS过程中烧结体显微组织演变的“自调节机制”, 由此揭示了制备高致密度、均匀、细晶材料的SPS技术优势的内在机理; 还对SPS烧结体的致密化过程进行了定量预测, 实验测定值证实了模型预测结果.     

非晶态合金晶化过程的高精度电阻监测研究

发展了一种高精度四线交流电阻测试设备，原位监测Ｎｉ８０Ｐ２０，ＦｅＺｒ２和Ｆｅ８６Ｂ１４非晶合金的晶化动力学过程。结果表明这种方法可以发现非晶合金早期晶化过程，测试出的晶化温度范围明显宽于ＤＳＣ方法，能够更加灵敏地反映晶化过程的信息，这种方法还能够临别共晶型和多形型晶化中的形核和长大过程，而对于初晶型晶化过程电阻测试亦反映了初晶相的形核信息。     

Zr60Al15Ni25块体非晶合金在室温轧制过程中的相变

利用X射线衍射(XRD)、差示扫描量热法(DSC)和高分辨电镜(HREM)对Zr₆₀Al₁₅Ni₂₅块体非晶合金在室温轧制过程中的微观结构变化进行了研究. 实验发现XRD衍射峰的半高宽FWHM和DSC曲线上的晶化放热焓ΔH的值在较小变形度ε(约为20%)的情况下小于铸态值; 当e 增大到一定值(大于30%)后, FWHM和ΔH的值又大于铸态值; 当ε进一步增大到约85%时, FWHM和ΔH的值又大幅减小. 实验结果表明, 在轧制过程中合金原子的组态发生了有序化和无序化之间的可逆转变. HREM图像进一步证实了这种可逆相变. Zr₆₀Al₁₅Ni₂₅块体非晶合金在轧制变形过程中出现的可逆相变是扩散控制的有序化和剪切应力诱导的无序化两个相反过程之间竞争选择的结果.     

阳极氧化温度对Al-Ti复合氧化膜结构和电性能的影响

采用水解沉积-阳极氧化方法制备了高介电常数的Al-Ti复合氧化膜. 通过膜溶解试验, 膜成分AES深度分析及电性能测试, 研究了恒电流阳极氧化过程中, 阳极氧化温度对Al-Ti复合氧化膜的生长、结构及电性能的影响. 结果表明, 随着阳极氧化温度升高, Al-Ti复合氧化膜的形成速率增大, 氧化膜的结构由两层转变为三层, I-V特性也发生显著变化, 铝电极箔的比容有一最大值. 50℃所形成氧化膜的局部击穿最明显, 氧化膜的漏电流最小, 而耐电压最高.     

Al-Ni非晶合金的原子堆垛结构及密度的第一性原理分子动力学模拟

在Al基非晶合金中，Al-Ni系的非晶形成能力（GFA）相比其他系列较佳，但是目前对Al—Ni二元合金系的原子排列、玻璃转变和堆垛密度与成分之间的内在联系，至今还未形成系统的认识．本文利用第一性原理分子动力学（AIMD）模拟方法对AlxNi100-x（x=80，83，85，86，87，90）二元非晶合金的原子堆垛结构和密度进行了研究．双体分布函数和Voronoi多面体分析表明，在该非晶合金系中存在明显的拓扑和化学短程有序，拓扑短程序主要是由以Al原子为中心的类似二十面体结构和以Ni原子为中心的三棱体覆盖三个半八面体（TTP）结构组成．在该合金系非晶中A-与Ni原子间存在强烈的化学交互作用，Al—Ni原子对键长小于原子半径和，化学有序随着Ni含量的增加呈现增加的趋势．AIMD计算结果表明，当x=85时，合金的堆垛密度出现了峰值，偏离了直线规律．综合结构特征和密度特征，从理论上推断，当Al含量为84％～86％时，合金的非晶形成能力较好，可以推广至多元合金体系．     

FAD非晶金刚石薄膜的场电子限射性能研究

利用真空磁过滤弧沉积技术制备得到了无氢的非晶碳膜。由于非晶碳膜中数量极高的四面体键的存在，这种非晶碳膜也可被称作非晶金刚石薄膜。报道了这种非晶金刚石膜的场电子发射特性，并对其能带结构和发射机理进行了研究。实验结果表明，在阈值电场为１５Ｖ／μｍ的情况下，测得的场发射电流超过了２０μＡ，薄膜的电子发射行为符合Ｆｏｗｌｅｒ－Ｎｏｒｄｈｅｉｍ场发射理论，非晶金刚石膜是有负电子亲合势和较小的有效功函数，如此     

高温应变下的亚晶界湮没与位错旋转机制的晶体相场模拟

采用先进的晶体相场模型,分别模拟了不同高温条件下的小角对称倾侧晶界,在施加应变下的晶界分解和亚晶界湮没的过程.研究表明:对于不靠近固-液共存温度的高温(T1)预熔化样品,施加应变下的晶界位错发生滑移运动,生成亚晶界和新的晶粒.随后,具有相反Burgers矢量的位错亚晶界相向运动,新晶粒不断吞噬旧晶粒而长大,最后发生亚晶界相遇湮没,亚晶界和预熔化区域消失,双晶转变为完整单晶.对于靠近固-液共存温度的高温(T2)预熔化样品,在应变作用下,生成的亚晶界相向运动,当接近到一定距离时,形成位错对偶极子,发生亚晶界位错结构二次转换,之后亚晶界运动反向,往回迁移运动,最后与另一列返回的亚晶界相向靠近,相互作用转变成"之"字形的亚晶界,然后湮没消失,整个体系转变为单晶.对于高温T2预熔化亚晶界,在应变作用下,形成位错对偶极子的过程中,偶极子的2个位错对的预熔化区域开始扩张、连通,形成近似棒状区域.这一过程的实质是高温预熔化区内部的原子晶格变软,使得在应变作用下,原子排列可以较容易的发生滑移和扭转变形,发生了不同类型的位错相互作用,出现了位错萌生、形核和增殖,位错分解和湮没等一系列位错反应,由此引起了位错的Burgers矢量方向的改变和亚晶界位错类型交换.     

FAD非晶金刚石薄膜的场电子发射性能研究

利用真空磁过滤弧沉积(FAD)技术制备得到了无氢的非晶碳膜.由于非晶碳膜中数量极高的四面体键(sp~3键)的存在,这种非晶碳膜也可被称作非晶金刚石薄膜.报道了这种非晶金刚石膜的场电子发射特性,并对其能带结构和发射机理进行了研究.实验结果表明,在阈值电场为15V/μm的情况下,测得的场发射电流超过20μA,薄膜的电子发射行为符合Fowler-Nordheim场发射理论.非晶金刚石膜具有负电子亲合势和较小的有效功函数.如此低的阈值电场和高的发射电流,表明这种非晶金刚石薄膜的场电子发射性能已达到甚至超过目前文献上报道的最好结果,为非晶金刚石膜作为场发射材料在平板显示器等真空微电子器件中的实际应用提供了可能性     

Cu在非晶合金Fe—Zr—B结晶过程中的作用

利用场离子显微镜－原子探针和透射电子显微镜研究了Ｃｕ在非晶合金Ｆｅ－７Ｚｒ－３Ｂ－１Ｃｕ初晶转变过程中的行为，结果表明，结晶前有富Ｃｕ的原子团簇形成，结晶过程中富Ｃｕ的原子团簇为α－Ｆｅ相提供形核位置，有效提高了α－Ｆｅ的形核密度。     

The generation of new ‘white’ muscle fibers by budding in the lateral musculature of elversAnguilla anguilla (L.) during normal development

Summary The elver is a developmental stage of the European eel Anguilla anguilla (L.). During its growth, relatively large numbers of new muscle fibers are formed in the lateral musculature. We investigated the origin of these fibers. They proved to originate from already existing fibers by budding.     

Comparison of the inhibitory activity and concentration of alfa1-antiprotease in normal human sera

Summary Inhibitory activity and concentration of alfa₁-antiprotease were simultaneously determined in sera of 80 blood donors. The lack of the coincidence of these 2 parameters was observed in about half the subjects tested.This work was supported in part by the Polish Academy of Sciences — PAN 337/VI.     

面向三峡库区水环境监测的混合网络构建

针对三峡库区分布广,面积大的特殊应用背景,提出了一种新的适合三峡库区水环境监测网络构建的组网策略——"一网多PAN(Personal Area Network),一PAN多簇",构建了一个包含WSN、GPRS和Internet的三层混合网络模型,并采用"告警上报,点播访问"的数据访问流程实现了监测网络数据传输。实验表明:该混合网络可以满足三峡库区水环境监测的应用需求;同时,"告警上报,点播访问"的数据传输流程可以有效降低节点能量消耗,延长网络生存周期。     

Interaction between bradykinin and voltage-sensitive sodium channels in myelinated nerve fibers

The effects of externally and internally applied bradykinin on the excitability of single myelinated nerve fibers were studied. External bradykinin (10 microM) slightly prolongs the action potential of a single myelinated nerve fiber; hence, when the fibers are stimulated by long-lasting pulses, this raises the frequency of repetitive firing in sensory fibers and evokes repetitive activity in motor fibers. Under voltage-clamp conditions, sodium channel inactivation is slowed, while sodium channel activation remains unaffected. Prolonged depolarization of the membrane leads to a maintained sodium current. The voltage dependence of the steady-state sodium current inactivation (h infinity) is shifted in the depolarized direction by approximately 10 mV. Internally applied bradykinin produces a frequency-dependent block of the sodium current. The phenomena described here imply that more than one site on the sodium channel is modified by bradykinin.     

Selectivity of alterations in skeletal fibers in chronic Chagas' disease of the mouse

In mice chronically infected with Trypanosoma cruzi, the masseter muscle (rich in type II fibers) was devoid of inflammatory infiltrates and parasites. In contrast, other muscles, composed of type I and II fibers, showed a decrease of type I fibers, parasites and lesions, suggesting that in T. cruzi infection type I muscle fibers are selectively damaged.     

Selectivity of alterations in skeletal fibers in chronic Chagas' disease of the mouse

Summary In mice chronically infected withTrypanosoma cruzi, the masseter muscle (rich in type II fibers) was devoid of inflammatory infiltrates and parasites. In contrast, other muscles, composed of type I and II fibers, showed a decrease of type I fibers, parasites and lesions, suggesting that inT. cruzi infection type I muscle fibers are selectively damaged.     

Uptake and transport of exogenous peroxidase in the masticatory muscles of cats. Localization of ganglionic neurons]

Retrograde axonal transport of Horseradish peroxydase (HRP) has been used to trace the cells of origin of proprioceptive fibers in jaw-closing and jaw-opening muscles. After injection of HRP in young cats' masticatory muscles (masseteric, temporal, pterygoid, mylohyoid and digastric) labelled neurons were found in the ipsilateral semi-lunar ganglion and trigeminal mesencephalic nucleus. It is concluded that sensory endings are present in jaw-opening as in jaw-closing muscles; possibly the afferent fibers from muscle endings of the opener muscles have their somata in the mesencephalic nucleus, afferent fibers from tendinous receptors in the semi-lunar ganglion.     

Different methotrexate effects in cultured normal and leukaemic human leukocytes

Summary Evidence is presented that the use of 2 different culture media, with or without methionine, can help to distinguish between normal and leukaemic methotrexate (MTX)-sensitive cells derived from chronic myeloid leukaemia patients. During the blast crisis MTX assays may help directly in the diagnostics of lymphoid involvement.This work was supported by the Polish Academy of Sciences within the project 09.7.4.1.4.Acknowledgments. We are indebted to Prof. Zofia Zieliska, Dept. of Cell Biochemistry, M. Nencki Institute of Experimental Biology PAN for providing the 5-methyltetrahydrofolate and for advice in these studies.     

Substance P-like immunoreactive fibers in the frog taste organs

Summary In the frog tongue, substance P(SP)-like immunoreactive fibers were consistently present in each fungiform papilla, which contained the gustatory apparatus. Numerous SP-like immunoreactive fibers were usually distributed in the periphery of the gustatory disc and formed a varicose meshwork among the ciliated cells encircling the gustatory disc. SP-like immunoreactive fibers were rarely evident inside the gustatory disc. The role of SP-containing fibers in the frog taste organ was discussed.     

Substance P-like immunoreactive fibers in the frog taste organs

In the frog tongue, substance P(SP)-like immunoreactive fibers were consistently present in each fungiform papilla, which contained the gustatory apparatus. Numerous SP-like immunoreactive fibers were usually distributed in the periphery of the gustatory disc and formed a varicose meshwork among the ciliated cells encircling the gustatory disc. SP-like immunoreactive fibers were rarely evident inside the gustatory disc. The role of SP-containing fibers in the frog taste organ was discussed.