静电场作用下H2O偶极极化对冰晶形成过程的影响

采用去离子水为实验样品，在-30℃低温环境中冷冻，冷冻过程中施加不同强度的静电场干扰，研究静电场对去离子水冰核形成及冰晶生长过程的影响．研究发现，在冷冻过程初期静电场的引入可以诱发冰核形成，导致过冷点升高，但在随后液相到固相的相变过程中，静电场对冰晶生长具有抑制作用．分析认为，在静电场作用下电偶极矩沿电场方向分布的H2O具有最稳定的状态，能量的分布函数具有最大值，这些结果是诱发冰核形成、抑制冰晶生长的原因．     

冷冻浓缩水处理工艺中冰晶纯度影响因素分析

冷冻浓缩水处理工艺的核心是制备颗粒大、纯度高的冰晶.以尿液为试验水样,通过试验研究,分析了冷冻温度、冰晶形态、溶液初温、溶液浓度、种冰、再结晶过程和结晶时间对冰晶纯度的影响,并在此基础上提出了制备高纯度冰晶的途径.     

低过冷度下抗冻糖蛋白(AFGP8)溶液中冰晶生长速率的理论模型

抗冻糖蛋白是一种具有抗冻作用的特殊生物功能蛋白质分子，可以防止低温环境中生物细胞被冻伤。通过与冰晶的某些晶面相结合，抗冻糖蛋白分子能降低冰晶的生长点温度，而对冰晶的熔点温度无明显影响。冰晶在抗冻蛋白溶液中的生长行为与冰晶在纯水中生长有明显区别。根据晶体生长理论，分析了抗冻糖蛋白溶液中冰晶基面上水分子发生固-液相转变概率与纯水中冰晶棱面上水分子发生固-液相转变概率的差异。在此基础上，结合Jackson理论并将其推广应用于抗冻糖蛋白溶液中冰晶的生长，提出了在低过冷度下抗冻糖蛋白溶液中冰晶沿c轴生长速率的理论模型，应用该理论模型的计算结果与实验数据更加符合。     

相场法模拟冰晶生长的参数优化

水溶液冻结过程生成的冰晶是低温保存中造成细胞损伤的主要原因.研究如何降低冰晶形成和生长过程对细胞伤害的方法,是低温生物研究的重要课题.本文采用国内外描述相变微观结构的相场模型,将体系视为水和溶质二元系统,研究了界面厚度尺度、各向异性强度和过冷度对结晶过程冰晶生长的影响.结果表明:界面厚度影响模拟结果,为了获得可靠的计算结果,界面厚度参数取值为3.00dx;各向异性系数大小对冰晶形貌有很大影响,取值越大,冰晶的二次分枝越发达,且尖端速度波动的幅值越大,各向异性系数取值范围0.010~0.025;过冷度明显影响冰晶的生长和形貌,过冷度大,冰晶生长速度加快,二次分枝发达,形貌变化较大,固相率也随之变大.参数优化结果为:界面厚度尺度等于3.00dx,各向异性系数等于0.023,过冷度等于20K的模拟结果与低温显微镜下观察到的冰晶生长形貌试验结果相吻合.     

冰浆存储过程中冰晶粒径动力学演化影响因素

为研究冰浆存储过程中冰晶粒径演化的影响因素及其规律,运用群体平衡模型,并通过数学变换,将模型中数量守恒方程转换为质量守恒方程,进而对冰浆存储过程中冰晶粒径分布及演化的影响因素进行数值模拟研究,着重分析添加剂种类与质量分数、含冰率、耗损率等因素对冰晶粒径分布密度及冰晶平均粒径的影响。研究结果表明:在相同添加剂质量分数下,乙二醇和乙醇比氯压钠对抑制冰晶粒径增长的效果好。对于同一种类添加剂,减少添加剂质量分数会降低冰晶粒径增长的速度;含冰率越低,冰浆溶液中冰晶粒径增长速度越慢,而降低含冰率会导致冰浆的蓄能密度下降;耗损率越高,冰浆溶液中冰晶粒径增长速度越慢,增大耗损率会改善冰浆流动性但会增加冰浆制冷的能耗。研究成果为冰浆存储与应用过程中冰晶粒径的控制与预测提供了参考。     

磁场影响水溶液冰晶的试验及装置

为寻找生物组织低温无损保存的新方法,研究了磁场对KMnO4溶液冰晶形成的影响.建立了不同形式的磁场发生装置,包括旋转磁场、方波叠加正弦波磁场、50kHz磁场.为保证样品降温过程慢速均匀,运用虚拟仪器技术建立了温度测控系统.使用低温显微系统对磁场影响下样品冰晶的形态进行了记录.结果表明,低频旋转磁场对生物溶液冰晶的形成产生了影响,尤其50kHz交变磁场对溶液中冰晶的生长具有较为显著的抑制作用,说明在易于产生的低冷冻速率下,交变磁场对生物组织的低温无损保存研究具有重要意义,适合实际应用.     

含盐冰的特异高介电常数特性

在-5℃～-60℃温度范围内,对掺有一价碱卤盐离子的含盐冰的介电特性进行了实验研究。结果发现在相同条件下,一定浓度的含盐冰具有极高的介电常数,它比纯冰的介电常数高出几倍甚至几十倍,最高可达10~3以上。从浓度为0.9％NaCl 含盐冰的介电温谱中发现,在相同温     

通孔金属泡沫强化蓄冰实验研究

为了研究通孔金属泡沫内嵌相变材料凝固过程特性及泡沫材料孔结构参数对凝固过程的影响,搭建了固液相变传热可视化测量系统,利用该系统就通孔铜泡沫强化蓄冰过程开展了实验研究。实时观测了凝固相界面的瞬态移动过程,测量了金属骨架表面和内嵌相变介质的实时温度,研究结果表明:铜泡沫可有效改善蓄冰后期传热恶化现象,大幅减少蓄冰时间,加入铜泡沫后,结冰所需时间与纯水工况相比减少为48.86%(孔密度为1 181m~(-1),孔隙率为0.90)和60.97%(孔密度为1 181m~(-1),孔隙率为0.97);铜泡沫的孔隙率对结冰过程影响较大,孔隙率为0.90的铜泡沫比孔隙率为0.97的铜泡沫中水完全凝固时间减少20%,而孔密度对结冰过程影响可忽略不计。可视化结果表明,未凝固相局部自然对流导致凝固相界面发生倾斜,呈现下部略快于上部的凝固界面。     

带电胶体系统固液相变的分子动力学研究

在修正Yukawa相互作用的基础上，采用常温分子动力学方法数值研究了带电胶体系统的大离子屏蔽效应和多分散性效应对其固液边界的影响．研究结果发现，在屏蔽长度较大时，固液相变曲线出现了明显偏差．初步定性认为这种相边界偏差现象来自于系统多体效应的增强．另外，数值研究了固液相变时键接取向序参数的变化．     

直接接触固液相变制冰及冰蓄冷系统的研究进展

综述了直接接触固液相变制冰、强化制冰的方法及冰蓄冷系统的研究进展，考虑到目前对蓄冰技术相关的固液相变传热问题的研究与发展现状，提出了一些有待研究解决的问题     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with