红细胞膜变形能力与胞内血红蛋白聚合状态及细胞形态的关系

以显微激光散射光谱和图像分析技术,对单个活态红细胞在无扰、在位、实时的情况下,测量了人血红细胞胞膜的变形能力,以及与之同时对应的胞内血红蛋白的聚合状态和细胞的形态结构.并据此研究了它们的相关关系以及随各种生理条件而交互变化的情况.     

柠檬醛作用下黄曲霉细胞膜的多力学参数测定

在无扰、在位、实时的情况下,测量了黄曲霉细胞膜的力学参量:弯曲模量Kc、剪切模量μ及表征切向与弯曲模量之比ε.对不同柠檬醛浓度作用下黄曲霉细胞各力学参量进行了连续动态检测.结果表明,柠檬醛浓度的提高黄曲霉素细胞的变形能力逐渐减弱,提示出柠檬醛对黄曲霉素细胞膜的破坏作用.     

红细胞拉伸变形的粗粒化模拟

采用最近提出的一种红细胞膜粗粒化网络模型研究红细胞在外力作用下的变形.该模型中细胞膜由非线性弹簧连接构成的网状结构组成,弹簧选用蠕虫链模型.系统的自由能考虑面内自由能、弯曲自由能、红细胞表面积和体积控制势能.经过粗粒化参数处理,利用耗散粒子动力学方法模拟红细胞在拉力作用下的变形.对模型中量纲一参数与真实物理量之间的对应关系进行讨论,对弯曲势能及面积、体积控制势能所对应的粒子点上的受力进行分析,并验证前人的计算与实验结果.结果表明:红细胞膜粗粒化网络模型能有效地模拟红细胞的变形,但红细胞的变形受多种因素影响,需要不断完善模型.     

板料弯曲成形实验研究

金属板料在激光作用下发生弯曲变形，其弯曲角度与激光功率、激光扫描速度以及扫描次数有关。     

船舶钢板激光弯曲成形的数值模拟及实验研究

对船舶钢板激光弯曲成形过程进行了数值模拟及实验研究。建立了成形过程的三维非线性热力耦合有限元模型,模型中考虑了材料热物性参数和力学性能参数与温度的相关性。计算了弯曲成形过程的温度场及变形场,预测了钢板的最终弯曲角度。实测了激光弯曲成形过程中的温度变化和弯曲变形量。数值模拟结果与实验结果吻合较好。     

遗传球形红细胞增多症红细胞膜力学特性研究

彩和微管吸吮实验技术并结合十二烷基硫酸钠－聚丙烯酰胺凝胶电泳等生化方法研究遗传球形红细胞增多症红细胞膜粘弹性特及膜骨架蛋白的变化。结果表明：ＨＳ红细胞膜的弹性模量和正常对照组比较无明显差异而粘性系数显著高于正常值,细胞粘滞性增大型汽轮发电机组轴系的变形能力降低;     

Fe-Ni-C合金粉末选择性激光熔化成形

针对金属零件在选择性激光熔化成形过程中容易产生翘曲变形、裂纹与球化现象等问题,在理论分析与试验的基础上,探讨了其工艺参数与扫描路径对金属粉末在熔化成形中翘曲变形、裂纹与球化的影响,以及化学成分、熔池冷却速度与制件金相组织、显微硬度的关系,为选择性激光熔化技术的发展提供理论指导与实验依据.实验表明:通过合适的工艺参数与扫描路径,能够得到高致密度金属零件,金相组织均匀细小,没有出现明显翘曲变形、裂纹与球化现象.     

透明土土体变形测量系统中激光散斑图像的获取

透明土试验技术实现了土体内部可视化,其变形测量的获取目前多通过与透明土相适应的透明土土体变形测量系统进行。该系统利用片状激光实现了对透明土的内部切片观察,通过获取激光散斑图像结合图像处理方法分析得到土体变形的情况。但是该系统在获取散斑图像时并没有考虑到激光在透明土试样内的散射特点及其对散斑图像的影响,存在一定的局限性。对此,通过对透明土中激光散射现象进行观测,归纳了透明土中激光散射的特点,并就激光散斑图像获取进行分析改进,同时应用图像处理技术解决了图像获取过程中可能产生的变形问题。     

激光偏振特性在微尺度工件激光弯曲成形中的作用

根据激光的偏振特性影响金属材料对激光的吸收这一特点,通过改变激光扫描工件表面的入射角,提高了金属表面对CO2激光能量的吸收率,使厚度为0.1 mm的微尺度不锈钢工件在未进行黑化处理的情况下获得了弯曲变形.实验结果表明,在采用线偏振激光对具有吸收层的工件进行多次扫描时,由于变形部分入射角增大引起激光吸收率提高,以及光斑面积增大引起激光功率下降,从而导致作用于工件表面的激光能量因素改变,这是弯曲角度发生变化的主要原因.     

用材料力学方法研究不同模量梁的弯曲变形

为得到不同模量梁弯曲正应力及挠度的实用计算公式,采用材料力学方法分析复杂外载荷下的不同模量梁的弯曲变形,将材料力学方法得到的计算结果与弹性理论方法得到的计算结果进行比较。研究结果表明:用材料力学方法研究不同模量梁的弯曲变形不但计算精度较高,而且计算过程也简便,克服了弹性理论存在一题一解及计算过程复杂繁琐的缺陷;不同模量梁的剪切形状因子与不同模量材料的拉压弹性模量有关,而各向同性材料梁的剪切形状因子与材料的弹性模量无关。     

运动、氧化应激与红细胞膜流动性

红细胞膜对于红细胞正常结构和功能的维持尤为重要，其与运动性疲劳的关系日益受到重视，笔者就运动与氧化应激、氧化损伤与红细胞膜流动性以及与红细胞功能的关系作一简要综述。     

海水淡化膜蒸馏膜的研究现状与展望

海水淡化技术(热法和膜法)是一项有望使人类摆脱淡水资源短缺困境的有效方法，其中，膜蒸馏技术是一种能源消耗低、脱盐能力强且有望实现淡水经济可持续生产的新型膜分离技术，但是膜蒸馏性能在很大程度上受膜污染与温度极化的制约，严重阻碍了其规模化应用，为此，研究人员围绕膜改性做了系列研究，以提高膜抗污染性并最大限度地降低温度极化。从阻碍膜蒸馏发展的问题入手，简要介绍了膜污染与温度极化及其对膜蒸馏造成的不利影响，综合分析了当前通过构造特殊润湿性表面抵抗膜污染以及利用限域加热降低/消除温度极化的研究现状，并指出当今膜蒸馏膜面临的问题，认为未来对于膜蒸馏膜的研究应从以下几方面开展：1)选用高导热/高光吸收的材料制造有限域加热功能并具有特殊润湿性表面的膜；2)设计能够适应多元污染物进料液的膜蒸馏膜；3)构筑一体化的具有高导热/光吸收性亲水层的Janus膜。     

A B cell-deficient mouse by targeted disruption of the membrane exon of the immunoglobulin mu chain gene

Of the various classes of antibodies that B lymphocytes can produce, class M (IgM) is the first to be expressed on the membrane of the developing cells. Pre-B cells, the precursors of B-lymphocytes, produce the heavy chain of IgM (mu chain), but not light chains. Recent data suggest that pre-B cells express mu chains on the membrane together with the 'surrogate' light chains lambda 5 and V pre B (refs 2-7). This complex could control pre-B-cell differentiation, in particular the rearrangement of the light-chain genes. We have now assessed the importance of the membrane form of the mu chain in B-cell development by generating mice lacking this chain. We disrupted one of the membrane exons of the gene encoding the mu-chain constant region by gene targeting in mouse embryonic stem cells. From these cells we derived mice heterozygous or homozygous for the mutation. B-cell development in the heterozygous mice seemed to be normal, but in homozygous animals B cells were absent, their development already being arrested at the stage of pre-B-cell maturation.     

Topological restriction of SNARE-dependent membrane fusion

To fuse transport vesicles with target membranes, proteins of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) complex must be located on both the vesicle (v-SNARE) and the target membrane (t-SNARE). In yeast, four integral membrane proteins, Sed5, Bos1, Sec22 and Bet1 (refs 2-6), each probably contribute a single helix to form the SNARE complex that is needed for transport from endoplasmic reticulum to Golgi. This generates a four-helix bundle, which ultimately mediates the actual fusion event. Here we explore how the anchoring arrangement of the four helices affects their ability to mediate fusion. We reconstituted two populations of phospholipid bilayer vesicles, with the individual SNARE proteins distributed in all possible combinations between them. Of the eight non-redundant permutations of four subunits distributed over two vesicle populations, only one results in membrane fusion. Fusion only occurs when the v-SNARE Bet1 is on one membrane and the syntaxin heavy chain Sed5 and its two light chains, Bos1 and Sec22, are on the other membrane where they form a functional t-SNARE. Thus, each SNARE protein is topologically restricted by design to function either as a v-SNARE or as part of a t-SNARE complex.     

Light-suppressible, cyclic GMP-sensitive conductance in the plasma membrane of a truncated rod outer segment

Recent experiments by Fesenko et al and ourselves have shown that excised membrane patches from retinal rod outer segments contain a cyclic GMP-sensitive conductance which has electrical properties similar to those of the light-sensitive conductance. This finding supports the notion that cGMP mediates phototransduction (see ref. 3) by directly modulating the light-sensitive conductance. However, some uncertainty remained about whether the patch experiments had discriminated completely between plasma and intracellular disk membranes; thus the cGMP response in an excised membrane could have resulted from contaminating disk membrane fragments, which are known to contain a cGMP-regulated conductance. Furthermore, the patch conductance has not yet been shown to be light-suppressible, an ultimate criterion for identity with the light-sensitive conductance. We now report experiments on a truncated rod outer segment preparation which resolved these issues. The results demonstrated that the cGMP-sensitive conductance was present in the plasma membrane of the outer segment, and that in the presence of GTP the conductance could be suppressed by a light flash. With added ATP, the effectiveness of the light flash was reduced and the suppression was more transient. The effects of both GTP and ATP were consistent with the known biochemistry. From the maximum current inducible by cGMP, we estimate that approximately 1% of the light-sensitive conductance is normally open in the dark; this would give an effective free cGMP concentration of a few micromolar in the intact outer segment in the dark.     

长方体充气膜结构设计简化计算方法研究

文章以非线性有限元知识为基础,对非线性有限元迭代方法简化,对不同荷载工况下结构的膜面应力和顶点最大位移等基本结构变化特性进行分析,得出模型的荷载-变形关系;并与ANSYS分析软件的分析结果进行比较,二者结果较为接近,证明了该文充气膜结构的简化有限元迭代方法正确性与可靠性。     

金属膜片联轴器圆环式膜片的应力分析

用ANSYS有限元程序对金属膜片联轴器中圆环式膜片进行了应力分析,给出了膜片中存在的4种应力的计算结果,并分析比较了4种应力对膜片疲劳寿命的影响.其结果对膜片疲劳寿命的计算提供了参考.     

Functional architecture of an intracellular membrane t-SNARE

Lipid bilayer fusion is mediated by SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) located on the vesicle membrane (v-SNAREs) and the target membrane (t-SNAREs). The assembled v-SNARE/t-SNARE complex consists of a bundle of four helices, of which one is supplied by the v-SNARE and the other three by the t-SNARE. For t-SNAREs on the plasma membrane, the protein syntaxin supplies one helix and a SNAP-25 protein contributes the other two. Although there are numerous homologues of syntaxin on intracellular membranes, there are only two SNAP-25-related proteins in yeast, Sec9 and Spo20, both of which are localized to the plasma membrane and function in secretion and sporulation, respectively. What replaces SNAP-25 in t-SNAREs of intracellular membranes? Here we show that an intracellular t-SNARE is built from a 'heavy chain' homologous to syntaxin and two separate non-syntaxin 'light chains'. SNAP-25 may thus be the exception rather than the rule, having been derived from genes that encoded separate light chains that fused during evolution to produce a single gene encoding one protein with two helices.     

超滤膜表面预沉积吸附剂对膜污染的缓解作用研究

选择三种含铁吸附剂FeO_xH_y、Fe_3O_4和MnFe_2O_4,分别预沉积到超滤膜表面的方式,通过对比3种蛋白质引起的膜通量变化;并分析超滤膜表明形态,探究超滤过程中蛋白质对膜污染的作用以及吸附剂对缓解膜污染的效果。试验结果表明:鸡卵白蛋白(ovalbumin,OVA)造成的膜污染最严重;预沉积MnFe_2O_4的对OVA的吸附效果,预沉积Fe_3O_4对OVA的吸附效果较差,对膜污染没有缓解作用。