Effects of α‐form or β‐form nuclei on polymorphic crystalline morphology of poly(butylene adipate)

The effects of α‐form and β‐form nuclei on polymorphic morphology of poly(butylene adipate) (PBA) upon recrystallization from the molten state up to various T_max values were examined by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and polarized light microscopy (PLM). In this study, PBA with complex melting and polymorphism behaviour was used as a model for examining different types and extents of residual nuclei. As the PBA initially containing the sole α‐crystal was brought to a molten state of various T_max, the extents of trace α‐form crystal nuclei varied and were dependent on T_max. Furthermore, it did not matter whether, initially, the PBA contained α‐ or β‐form crystals (or both) because only a single type of α‐nuclei could be left upon treatment to the molten liquid state at T_max. Therefore, only the α‐crystal in PBA had ‘memory capacity’ in the molten liquid state while the β‐crystal did not. This was so because the latter had been completely transformed into the solid state prior to being heated into a liquid. PBA crystallized before α‐nuclei could be packed into α‐crystal, regardless of the crystallization temperature (T_c). For recrystallization from molten PBA without any nuclei, the crystalline polymorphism was correspondingly influenced by T_c. Copyright © 2005 Society of Chemical Industry     

铸铁孕育处理时的石墨核心研究

将铁水用75FeSi孕育后液淬,终止其溶解过程,在溶解区中出现已经生长石墨相的非金属夹杂物,它们随后又溶回铁水中去.但已经复盖有石墨相的晶核能存在较长的时间孕育剂的作用是提供一个碳的过冷溶液,使位于其中的非金属夹杂物活化成为晶核     

基于多变量形态学特征的健康老年人认知发展预测算法

由于体积、表面积等常规形态学指标对于皮层下核团而言过于笼统,因此传统的形态特征获取手段难以检测到其表面形态的细微变化。为解决这一问题,本文提出了一种针对皮层下核团的精细特征提取算法,并将其应用到老年人认知状态预测任务上。通过表面共形参数化、表面共形表示和基于互信息的表面流配准,提取了46名被试双侧海马和杏仁核各15 000×2个顶点上的形态学特征;通过斑块选择、稀疏编码与字典学习,和最大池化的降维流程,避免了维度诅咒的同时充分保留了核团的纹理信息;最后,以树为弱学习器,采用GentleBoost算法集成了最终的强分类器做认知预测。结果显示,仅纳入海马和杏仁核两个皮层下结构的新颖特征,即可达到85%的预测准确率,为皮层下结构的精细特征发掘提供了新思路。     

钒氮钢中铁素体等温形核规律的试验研究

采用Geeble 3500热模拟试验机，对比研究了钒氮钢、钒钢的等温相变特征。结果表明，在相变过程中，钒氮钢中铁素体形核总量和晶内铁素体形核数量都明显高于钒钢，分析认为，这与钒氮钢中V（C，N）的析出造成了铁素体形核位置的改变，同时也增加了形核位置密度有关，尝试用一种新的形核方式对此进行了描述。     

硝酸钬对小鼠骨髓细胞核异常和肝脏三种抗氧化酶活力的影响

两次给小鼠腹腔注射硝酸钬溶液,相间24h,第二次注射24h后取股骨骨髓涂片,同时取肝脏检测超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活力。结果发现,在(10～40)mg/kg·bw剂量范围内,微核率和三种酶的活力随剂量的增加而升高;当剂量升至80mg/kg·bw时,三种酶活力趋于下降,但仍高于阴性对照组,而微核率增加到最大值;当剂量升至160mg/kg·bw时,微核率和酶活力均低于阴性对照组。低剂量(<40mg/kg·bw)硝酸钬溶液可促进骨髓细胞增殖,高浓度则表现出抑制作用。实验中还观察到核异常程度随剂量的增加而上升。推测低剂量钬离子通过诱导小鼠机体三种抗氧化酶活力的升高,清除部分自由基,一定程度上减轻了染色体损伤,高剂量则抑制了细胞分裂指数,又降低小鼠体内抗氧化酶活力,从而促进核异常。     

Contextual Fear Conditioning Is Associated With Lateralized Expression of the Immediate Early Gene c-fos in the Central and Basolateral Amygdalar Nuclei.

Fos, the protein product of the immediate early gene c-fos, was used to map functional circuitry underlying contextual conditioned fear. Male rats were given footshocks in a distinctive context and later tested using freezing as the behavioral measure and compared with no-shock and no-retention-test control groups. An increased number of Fos-immunoreactive neurons was found in the lateral part of the central nucleus and in the anterior basolateral and lateral amygdalar nuclei in the brains of the conditioned-fear group compared with controls. Further, a greater number of Fos-immunoreactive neurons was observed in the right central and anterior basolateral nuclei compared with the number of labeled neurons in these structures on the left. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemical Effects of Radiation Emitted from 10B(n, γ)7Li Reaction on Mixture of n-Propylamine and n-Propanol

The long term variation of the mean dose due to natural radiation in Japan received by an individual person was investigated. The mean exposure rate in each prefecture obtained by in-situ measurements was adopted as a basis of the radiation level. Population data were taken from both the resident registration and the census taking into account the essential difference of their meanings. It was revealed that the per capita dose due to outdoor natural radiaiton in Japan has been decreasing in the last approximate 30 yr. It will be due to the population movement from countrysides towards urban areas. That is because countrysides generally consist of stable mountainlands where granitic rocks distribute though urban areas generally consist of alluvial plains where volcanic ash or humus dominates. Although the contribution of low radiation level (below 9.0μR/h) areas to the nation-wide collective dose still remains under 50%, its relative importance has certainly been increasing in the last three decades. It is expected that human population will be the dominating factor which eventually controls the mean dose due to natural radiation in Japan.     

Separation of Americium from Europium using Camphor-BisTriazinyl Pyridine: A Fundamental Study

Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. Selective extraction of americium from acidic solution (up to 2M HNO₃) containing tenth molar quantities of lanthanides has been achieved using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented.     

Systematics of a-preformation factors in closed-shell regions

The a-preformation factors of medium and heavy-mass nuclei are calculated by using the cluster-formation model.The obtained preformation factors of even–even,odd-A,and odd–odd nuclei consist in both magnitude and trend with the general features predicted by standard calculations.The variation of a clustering affected by the evolution of nuclear structure is observed from different behaviors of preformation factors.We typically analyze the variation of preformation factors in the closed-shell N =126 and Z =82 regions,and discuss in detail the structural effects on a-cluster formation.This work shows the strong correlation between a-preformation factors and the shell structure,which would be a useful reference for microscopic cluster-model calculations of a-decay half-lives.     

大都市核心区的社会空间隔离--以上海市静安区南京西路街道为例

当今,我国城市正经历着重要的社会转型,一方面新的社会阶层的成长使得社会结构更加复杂,另一方面全球化和经济重组则趋于导向增长的社会极化.就空间趋势而言,隔离已在多种尺度上出现.大都市核心区马赛克状的隔离是不平衡开发的直接产物,而一个极化的居住结构是日益锐化的社会经济隔离的自然结果.通过对上海市静安区南京西路街道地区的案例,研究了大都市核心区的社会空间隔离.