The application of cholesky decomposition in valence bond calculation

The Cholesky decomposition (CD) technique, used to approximate the two‐electron repulsion integrals (ERIs), is applied to the valence bond self‐consistent field (VBSCF) method. Test calculations on ethylene, C_2nH_2n+2, and C_2nH_4n?2 molecules (n = 1–7) show that the performance of the VBSCF method is much improved using the CD technique, and thus, the integral transformation from basis functions to VB orbitals is no longer the bottleneck in VBSCF calculations. The errors of the CD‐based ERIs and of the total energy are controlled by the CD threshold, for which a value of 10^?6 ensures to control the total energy error within 10^?6 Hartree. © 2016 Wiley Periodicals, Inc.     

Hydration force due to the reduced screening of the electrostatic repulsion in few-nanometer-thick films

Experiments with foam films from solutions of 1 mM SDS + 100 mM electrolyte (LiCl, NaCl and CsCl) were carried out by a thin-film-pressure balance. The measured dependences of disjoining pressure versus film thickness exhibit a steep increase when the thickness of the film's water core becomes smaller than 3.7 nm. This behavior can be interpreted as a manifestation of the hydration force. We unsuccessfully tried to interpret the data with different available theoretical models. Eventually, we found that a relatively simple model of “reduced screening” can fit the data. Such reduced screening of the electric field could exist only in a narrow range of film thicknesses, which practically coincides with the region where the hydration repulsion is acting. This model and its experimental verification are described in the article.     

关于Zn1-xBexO电子结构和光学性质的研究

采用基于密度泛函理论和平面波赝势技术的CASTEP程序对Zn_1-xBe_xO合金电子结构和光学性质进行了计算.当0≤x≤1,其带隙从0.963 eV变化到7.293 eV.分析了晶格畸变和能带间排斥效应对带隙的影响.当Be含量x=0.125,0.25,0.375,0.5,0.625,0.75时,a/b轴压应变控制着带隙变化;当x=0.875,1时,c轴压应变控制着带隙变化.能带间的p-d排斥影响价带顶变动,Γ_1v与Γ_1c之间排斥影响导带底变动.这些能带间的排斥效应被用来分析Zn_1-xBe_xO带隙变动.另外,也分析了Zn_1-xBe_xO介电函数虚部ε₂. 关键词： 带结构 光学性质 应变 排斥     

Diamagnetic repulsion—A versatile tool for label-free particle handling in microfluidic devices

We report the exploration of diamagnetic repulsion forces for the selective manipulation of microparticles inside microfluidic devices. Diamagnetic materials such as polymers are repelled from magnetic fields, an effect greatly enhanced by suspending a diamagnetic object in a paramagnetic Mn²⁺ solution. The versatility of diamagnetic repulsion is demonstrated for the trapping, focussing and deflection of polystyrene particles for three example applications. Firstly, magnet pairs with unlike poles facing each other were arranged along a microcapillary to trap plugs of differently functionalised particles for a simultaneous surface-based assay in which biotin was selectively bound to a plug of streptavidin coated particles utilising only 22 nL of reagent. Secondly, by slightly modifying the magnetic field design, the rapid focussing of particles into a narrow central stream at a flow rate of 650 μm s⁻¹ was accomplished for particle pre-concentration. In a third application, 5 and 10 μm polystyrene particles were separated from each other in continuous flow by passing the particle mixture through a microfluidic chamber with a perpendicular magnetic field, a method termed diamagnetophoresis. The separation was investigated between flow rates of 20–100 μL h⁻¹, with full resolution of the particle populations being achieved at 20 μL h⁻¹. These experiments show the potential of diamagnetic repulsion for simple, label-free manipulation of particles and other diamagnetic objects such as cells for a range of bioanalytical techniques.     

晶须状多壁碳纳米管导电液及透明导电薄膜的研究

以碳纳米管醇分散剂TNADIS(粉末状聚合物分散剂)作为分散剂,同时应用超声振荡和高速剪切相互配合的工艺制成多壁碳纳米管(MWCNT)乙醇导电液.通过拉曼光谱,TEM和SEM表征MWCNTs的微观形态,通过离心,静置以及丁达尔效应的检测分析MWCNTs导电液的分散情况和稳定性.结果显示,添加0.05wt;分散剂时碳纳米管分散效果最佳,未石墨化MWCNTs的分散效果优于石墨化后的MWCNTs,且静置五个月后导电液依然保持良好的稳定性.应用此导电液通过旋涂工艺制得的涂覆均匀的MWCNTs透明导电薄膜,旋涂3min的透明导电薄膜方块电阻为0.34 kΩ/sq.     

Wirkungsweise polymerer Vergrauungsinhibitoren in Waschmitteln

Zusammenfassung Im Waschprozeß werden ölige Anschmutzungen von textilen Oberflächen abgelöst und dispergiert. Die Flotte soll darüber hinaus das Wideraufziehen (Redeposition) frei schwebender Schmutzanteile auf Textilfasern vermindern.Bei empfohlener Solldosierung eines Waschmittels entfalten Tenside, Komplexbildner, Builder und Zeolithe den größten Teil der erforderlichen Stabilisierungswirkung. Polymere Vergrauungsinhibitoren bewirken nur graduelle zusätzliche Verbesserungen. Mit fortschreitender Unterdosierung nimmt die stabilisierende Tensid-und Builder-Wirkung schnell ab und die Bedeutung polymerer Vergrauungsinhibitoren steigt.Der Wirkungsmechanismus weist ein hohes Maß an Selektivität gegenüber textilen Substraten auf. Auf polarem Gut (z. B. Baumwolle) wird oft mit Erfolg Carboxymethylcellulose eingesetzt. Die Wirkungsweise beruht in diesem Falle weitgehend auf der sterischen Polymerschutzwirkung adsorbierter Schichten.Auf hydrophoberen Polyesterfasern zeigen Celluloseether mit hydrophoben Seitenketten (z. B. Hydroxypropylcellulose) sehr gute Effekte. Dabei wird die sterische Komponente der Polymerschutzwirkung durch Erniedrigung der treibenden Kraft der Heterokoagulation (Hydrophilierung sämtlicher hydrophober Grenzflächen) verstärkt. An Mischgeweben werden daher oft Kombinationen mehrerer Vergrauungsinhibitoren genutzt.Die vergrauungsinhibierende Wirksamkeit polymerer Substanzen für Polyester kann durch deren Fähigkeit, ungeachtet der Konkurrenz mit restlichen Inhaltsstoffen des Waschmittels möglichst starke effektiv irreversible Hydrophilierungseffekte hervorzurufen, charakterisiert werden.

---

In laundering, oily soils are detached from textile surfaces and dispersed. In addition, the washing solution should reduce the redeposition of free suspended soil particles onto the textile fibres.In the case of a recommended predetermined dosage of a detergent the main part of the required stabilizing effect is due to the surfactants, complexing agents, builders and zeolites. Polymeric antiredeposition agents cause only gradual additional improvements. In the case of a weak dosage the stabilizing effects of the surfactants and builders rapidly decrease and the effects of the polymeric antiredeposition agents increase.The mechanism of these effects is characterized by high selectivity of the textile substrates. In the case of polar textiles (for instance cotton) carboxy methyl cellulose is often successfully used. In this case the mode of action is mostly due to steric repulsion of the adsorbed layer.In the case of hydrophobic polyester fibres cellulose ethers with hydrophobic sidechains (for instance hydroxy propyl cellulose) show very good effects. In this case the steric component of the polymeric repulsion is supported by the decrease of the driving force of the heterocoagulation (hydrophilization of all hydrophobic interfaces). For this reason combinations of several antiredeposition agents are often used for mixed fabrics.The performenace of the polymeric agents for polyesters can be characterized by their ability to cause strong effective irreversible hydrophilization effects despite the competitive influences of the residual detergent ingrediences.

Vortrag anläßlich der Hauptversammlung der Kolloid-Gesellschaft in Berlin vom 2. bis 4. Oktober 1985.     

The reactivity of silanes in free-radical reactions: Analysis in terms of the parabolic model of the transition state

Rate constants and activation energies of free-radical reactions of silanes and silyl radicals were analyzed in terms of the parabolic model of the transition state. The kinetic parameters were estimated for 16 groups of reactions of silanes and silyl radicals. These parameters were used to calculate the activation energies for 112 free-radical reactions and to estimate the dissociation energies of the Si−H bond for 21 compounds and those of the C−Cl bond for 12 substituted benzyl chlorides. Triplet repulsion, electronegativity, and radii of atoms of the reaction center of the transition state were shown to play an important role in the formation of the activation barrier. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1311–1316, July, 1998.     

环式结构体系中的双碳正离子

在某些环式结构体系中,由于某些轨道的相互作用使正电荷离域,从而克服正电荷间的相互排斥形成长寿命的双碳正离子。本文介绍苯双碳正离子,双环[m.n.p]桥头双碳正离子、去氢金刚烷基双碳正离子及宝塔烷双碳正离子的生成、检测、性能及理论处理。