Existence and asymptotic results for a system of integro-partial differential equations

A non-Fourier phase field model is considered. A global existence result for a Dirichlet, or generalized Neumann, initial-boundary value problem is obtained, followed by a discussion of the regularity and asymptotic properties of solutions ast.This research was supported in part by the National Science Foundation under Grant DMS 91-11794 and in part by the Italian M.U.R.S.T. project Problemi non lineari...Part of this author's work was done while visiting Ohio University.     

Effects of steric and hydrophobic forces on the rheological properties of ZrO2 suspensions

 The effect of pH on the flow behavior of ZrO₂ suspensions containing polyacrylic and octanoic acids was evaluated. In the flocculated pH regime, the flow behavior is highly shearthinning and can be described by a power-law model. The shear-thinning behavior increases with increasing degree of flocculation. Maximum shearthinning was observed at the zero zeta potential condition. Hydrophobic interaction arising from adsorbed octanoic acid was found to enhance the shear-thinning behavior. No such enhancement was observed for adsorbed polyacrylic acid. It was also illustrated that the viscosity–pH behavior is a mirror image of the yield stress–pH behavior. A quantitative particle-pair interactions model incorporating steric and hydrophobic interactions was proposed to explain the effects of polyacrylic and octanoic acids on the maximum yield stress. Received: 23 May 1997 Accepted: 4 June 1997     

激光光散射研究丙烯酰胺-二甲基二烯丙基氯化铵共聚物的溶液行为

用激光光散射技术表征了阳离子含量受控的丙烯酰胺 二甲基二烯丙基氯化铵共聚物 (简称P(AM DMDAAC) )在 0 1mol LNaCl溶液中的基本参数和溶液行为 .表观基本参数 : Mw ,app =5 0 4× 10 5g·mol- 1 、app =39 9nm和A2 ,APP =1 5× 10 - 4cm3·mol·g- 2 .动态光散射研究结果表明 ,扩散系数Dt 与角度、浓度皆呈非线性依赖关系 ,当C >C 或在较大的散射角域 ,Dt 偏离线性关系所预示的理论值而向减小的方向发展 ,表明存在缔合物 ;流体力学半径Rh 分布有大、小两个范围 ,并随温度升高向小尺寸方向发展 ,证明了体系中存在缔合行为以及升温的解缔合作用 .在一定条件下 ,“亚稳定性”的存在有力地旁证了体系的缔合行为     

辅酶Ⅰ在Co／CFUE上的电化学行为及应用

辅酶I(NAD+)在0.005moL/LTris 0.01moL/LNaCl溶液(pH7.0)中,于钴离子注入修饰碳纤维电极上出现一个S形的还原波,半波电位为-1.45V(vs.SCE)。峰电流与NAD+的浓度在2.38×10-5～4.76×10-4mol/L(r=0 9992)和4.76×10-4～1.78×10-3mol/L(r=0.9982)之间成线性关系,检出限为1.19×10-5mol/L,回收率在96.7%～103.4%之间。用线性扫描、循环伏安法研究了钴离子注入修饰碳纤维电极上NAD+的电化学行为。电极反应机理为:NAD++e NAD·;NAD·+e+H+ NADH;2NAD·→NAD2。另外,钴离子注入修饰碳纤维电极对NAD+具有电催化作用。     

钌—钛金属氧化物涂层电极的电子能谱分析

用X-光电子能谱分析了Ru-Ti金属氧化物电极的组成、结构和元素价态。结果表明,电极表面不同于体内,讨论了表面和体内Ti的价态区别对Ru-Ti阳极活性和寿命的影响,指出掺杂Ir和Pd后会提高电极活性。     

A New Method to Investigate the Clustering Phenomena in Supercritical Fluids

EstimationoflocaldensityofsolventaboutthesoluteSolvatochromicbehaviorsofspectroscopicprobesarewidelyusedtoestimatethesol-ventstrengthofsupercriticalfluids(SCF,).i-3lnthiswork,thesolvatochrondcshiftofthen-n*transitionbandforacetone(O.o37mo1.L-')insupercrihcal(SC)CO2wasde-terminedbyUVspectroscopytostUdythesolvationeffect.TheMcRae-BaylissexpressionbasedonthedielectriccontinUUInmodelgivestherelahonshipbetWeenso1vatochromicshiftandpo1arizabilityofnonPolarsolvents4-5asfollows:wherevisthewave…     

聚吡咯衍生物的合成及液晶性能

系统论述了新型导电功能性液晶聚合物3-和N-液晶基元取代聚吡咯的合成和液晶行为。指出通过化学氧化聚合、电化学氧化聚合和脱卤缩合聚合可以获得液晶性聚吡咯衍生物。它们均显示热致液晶行为，且多数呈现近晶液晶相，少数呈现向列液晶相，有些具有2种近晶相，有些具有单变液晶性。N-液晶基元取代聚吡咯比3-位取代聚吡咯具有较高的液晶稳定性。较长的亚甲基间隔和极性的介晶基团能够使N-取代聚吡咯具有较大的液晶微区和稳定的液晶相。N-取代液晶聚吡咯在摩擦力的作用下还可以诱发单轴取向。这种热致液晶性聚吡咯衍生物的研究成功有希望克服聚吡咯难以成型加工的巨大障碍。     

Scaling properties of ℤ k- 1 actions on the circle

We derive universal scaling properties for ^k–1 actions on the circle whose generators have rotation numbers algebraic of degreek. As fork=2 these properties can be explained for arbitraryk in terms of a renormalization group transformation. It has at least one trivial fixed point corresponding to an action whose generators are pure rotations. The spectrum of the linearized transformation in this fixed point is analyzed completely. The fixed point is hyperbolic with a (k–1)-dimensional unstable manifold. In the casek=2 the known results are therefore recovered.     

A facile synthesis of aliphatic polybenzoxazoles from a bis(o-aminophenol) or its hydrochloride and aliphatic dinitriles

A facile one-step method for the synthesis of aliphatic polybenzoxazoles has been developed. Thus, a series of aliphatic polybenzoxazoles having inherent viscosities of 0.2–0.7 dL/g in concentrated sulfuric acid were successfully synthesized by the melt polycondensation of alipatic dinitriles with 4,4′-diamino-3,3′-dihydroxybiphenyl (AHB) or its hydrochloride (AHB–HCl) with the elimination of ammonia or ammonium chloride, respectively. Monomer AHB–HCl was more reactive than the parent AHB, thereby affording higher molecular weight polybenzoxazoles in a shorter reaction time. The aliphatic polybenzoxazoles having 6–10 methylene units were highly crystalline with melting temperatures in the range of 187–308°C, which were stable up to 400°C in a melt state in nitrogen. © 1994 John Wiley & Sons, Inc.     

羟基化合物及其葡醛酸苷化学结构与RP—HPLC保留行为相关性研究

采用体外孵育生物合成方法获得羟基化合物葡醛酸苷系列化合物，并对其反相高效液相色谱保留行为及底物与其葡醛酸结合物保留行为相关性进行了研究，建立了相应的结构－色谱保留行为相关性方程及葡醛酸苷类代谢物保留行为的预测方法。将ＱＳＲＲ研究扩展到药物代谢物领域，对药物Ⅱ相葡醛酸化代谢产物的ＨＰＬＣ分析提供了帮助。