Drop retention force as a function of resting time

The force, f, required to slide a drop on a surface is shown to be a growing function of the time, t, that the drop waited resting on the surface prior to the commencement of sliding. In this first report on the resting time effect, we demonstrate the existence of this phenomenon in different systems, which suggests that this phenomenon is general. We show that d f/d t is never negative. The shorter the resting times, the higher d f/d t is. As the resting time increases, d f/d t decreases toward zero (plateau) as t --> infinity. The increase in the force, Delta f, due to the resting time effect (i.e., f( t --> infinity) - f( t --> 0)) correlates well with the vertical component of the liquid-vapor surface tension, and we attribute this phenomenon to the corrugation of the surface by the drop due to this unsatisfied normal component of Young's equation.     

微流控芯片在食品安全分析中的应用进展

微流控芯片技术可以实现从样品处理到检测的微型化、自动化、集成化及便携化,因而在食品安全检测方面展现出强大的发展活力。目前微流控芯片技术在农药残留、兽药残留、重金属、食品添加剂等食品安全检测方面已取得了一系列重要进展。该文着重介绍了微流控芯片技术在食品安全分析中的研究进展,并展望了其在食品安全分析中的应用前景。     

水凝胶微流控芯片的快速加工及在细胞培养检测中的应用

采用具有紫外光聚合性能的聚乙二醇(PEG)基水凝胶材料, 通过紫外光聚合作用快速加工双层水凝胶微流控芯片, 并验证了其对肿瘤细胞代谢液进行检测的可行性. 与传统微流控芯片材料相比, 该水凝胶芯片材料具有更好的生物相容性及可操控性, 可直接加工成形, 在生物学领域特别是细胞培养过程控制方面具有良好的应用前景. 实验结果表明, 该水凝胶微流控芯片可在微尺度空间有效模拟细胞生长环境, 并实现对细胞连续捕获后的原位培养. 将该芯片与卟啉可视阵列传感器系统结合, 经代谢特征分析可有效区分不同种类肿瘤细胞, 实现芯片细胞培养平台上的细胞代谢指纹快速可视化传感检测.     

Tetragonal Distortion of InN Thin Films by RBS/Channeling

Rutherford backscattering and channeling spectrometry （RBS/C） are used to identify the crystalline quality （Xmin = 4.87%） Of an InN thin film as a function of depth, and make a non-destructive quantitative analysis of the structure, in order to analyze the tetragonal distortion of the InN thin film at the depth determined.     

关于动态位错场张量势的规范变换

本文引入并论证了描述动态位错场的张量势(A与B)的规范交换问题,而且证明这种变换可采取这样的形式:B′=B+▽F, A′=A-ρ?/(?t)▽G,x′=x-ρ?/(?t)F,其中x_i=e_iklA_kl。至于F与G,则为带有很大任意性的时空坐标的矢量函数,但它们要满足以下关系式:F=▽×G,▽²F-1/G_t²-(?²/?t²)F=0.进 关键词：     

纳豆激酶分离纯化和酶活性测定的研究进展

该文对纳豆激酶的分离纯化和酶活性测定进行了综述。重点讨论了溶剂沉淀法、柱层析法、磁性微球吸附法、膨胀床法、反相胶束法、三相分割法等分离方法。对酶活性的不同测定方法进行了讨论和比较。提出了将核酸适配体识别技术用于纳豆激酶分离纯化和酶活性测定的可行性。     

Photocatalytic degradation of 1,5-naphthalenedisulfonate on colloidal titanium dioxide

Photocatalytic degradation of 1,5-naphthalenedisulfonate (NDS) was investigated by monitoring the absorption and emission spectral changes, chemical oxygen demand, total organic carbon (TOC) content as well as pH and sulfate concentration. Intermediates formed during the irradiation were also detected by liquid chromatographic-mass spectrometric analysis. The results obtained by the applied analytical techniques clearly indicate that the initial step of degradation is oxygenation (hydroxylation) of the starting surfactant resulting in the formation of an 8-hydroxy derivative, although desulfonation and some mineralization, that is, decrease of TOC indicating carbon dioxide generation, also take place at this stage. Further oxygenation and desulfonation lead to the destruction of the diaromatic naphthalene system, then to ring fission, producing diols, aldehydes, and carboxylic acids on the side-chains. A tentative scheme involving possible pathways of degradation is proposed, taking the intermediates detected by mass spectrometry into consideration. On the basis of the results of quantum chemical calculations, the most possible points of attack by HO radical were identified, supplementing the MS results, and elucidating the initial oxidation step in the degradation of NDS and the benzenesulfonate (BS) intermediate. Thus, in the case of NDS para position is favored for hydroxylation, while for BS, formation of the ortho-hydroxy derivative is preferred.     

Production of highly purified clotting factor IX by a combination of different chromatographic methods.

A highly enriched preparation of human clotting factor IX was produced by a combination of adsorption chromatography, hydrophobic interaction chromatography and heparin affinity chromatography. The introduction of adsorption chromatography with a hydroxyaminopropyl support allows the capture step to be carried out directly from the cryoprecipitate-depleted plasma with a chromatographic column in flow-through mode. This replaces the batch procedure used until now. The other two chromatographic steps are designed in such a way that the eluate from the preceding step can be directly applied, without any intermediate treatment of the sample. This cuts the period of time required for the process by almost 50%, and increases the yield considerably. The isolated factor IX contains practically no contaminants and has a specific activity over 200 IU/mg of protein.     

改性纳米TiO2固相光催化降解废弃聚氯乙烯

用偶联剂改性的纳米TiO2作催化剂，采用包埋法制备了一种新型的可光催化降解的纳米PVC-M-TiO2复合薄膜．在空气中紫外光照的条件下进行了该薄膜的光催化降解实验，并与以末改性的TiO2为催化剂的PVC-Un-TiO3复合薄膜的降解效率进行了比较，利用光照失重、傅立叶红外（FT-IR）光谱和扫描电子显微镜（SEM）等方法对光照前后复合薄膜进行厂分析表征．实验结果表明PVC-M-TiO2复合薄（TiO2质量百分含量为2％）膜在空气中能被有效的降解，连续光照480h后降解效率达到36．9％，明屁高于纯膜及未改性的PVC-Un-TiO2复合膜。