NIR studies of the surface modification in silica fillers

Methods of estimating the degree of condensation of the surface silanol groups of silica due to its modification by silane coupling agents are reported.Also, a procedure for estimating the surface silanol groups for the pre- and post-modified silicas for the NIR 7326 cm^–1 band is given.Using electron microscope studies and heats of immersion of silica surfaces, the silane effect on agglomeration of silica particles and, thus, on the physicochemical properties of its surface has been demonstrated.     

Weierstrass Type Representation of Willmore Surfaces in <Emphasis Type="Italic">S</Emphasis><Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>

In this paper, we reformulate the Euler-Lagrange equations of Willmore surfaces in S^n as the flatness of a family of certain loop algebra-valued 1-forms. Therefore we can give the Weierstrass type representation of conformal Willmore surfaces. We also discuss the relations between conformal Willmore surfaces in S^n and minimal surfaces in constant curvature spaces S^n, R^n, H^n, and prove that some special Willmore surfaces can be derived from minimal surfaces in S^n, R^n, H^n.     

The Development of Dioptric Projection Lenses for Deep Ultraviolet Lithography

Advanced dioptric projection lenses from Carl Zeiss are used in some of the world’s most advanced deep ultraviolet projection lithography systems. These lenses provide a resolution of better than 100nm across the entire field of view with a level of aberration control that maximizes critical dimension uniformity and lithographic process latitude. These dioptric projection lenses are currently being used for critical layer device patterning for a wide array of complex logic, memory, and application specific integrated circuits.     

脉冲偏压上升沿特性对等离子体浸没离子注入鞘层扩展动力学的影响

等离子体浸没离子注入(PIII)是用于材料表面改性的一种廉价高效、非视线的技术.采用等离子体粒子模型，通过假设电子密度服从Boltzmann分布，求解Poisson方程和Newton方程，跟踪离子在等离子体鞘层中的运动形态及特性并进行统计分析，研究了不同上升速率和形状的6种波形上升沿对鞘层时空演化、离子注入能量和剂量的影响.结果表明，在PIII过程中，脉冲上升沿影响了等离子体鞘层的扩展，且不同波形诱导的鞘层厚度间存在最大差值.电场强度在鞘层的外边缘区域存在陡降区，离子的运动为非匀加速过程.可以通过调整脉冲 关键词： 等离子体浸没离子注入 鞘层 粒子模型 上升沿     

The nature of the reaction between aqueous KOH and the acid surface oxides on porous carbons

The uptake of KOH from an aqueous solution by activated porous carbon is shown to be concentration dependent. The dependency is also revealed by enthalpy of immersion measurements. Decreasing the weight carbon/weight solution ratio increases the uptake of base. Langmuirian treatment of the isotherm data gives reaction parameters which can be associated with the acid surface oxides on the carbon.     

Modified silica precipitated in the medium of organic solvents — an active rubber filler

Studies were performed on application of highly dispersed silicas, specially obtained in organic solvent medium, to processing of elastomers. Particular attention was paid to silica surface modification and to estimation of an extent of the surface modification. To this aim, near infrared techniques were used and heat effects associated with surface wetting with water and benzene were estimated. Application studies were also conducted on the use of modified silicas in butadiene-styrene rubber.     

氮、氧及金属离子注入铝合金表面改性层摩擦磨损性能研究

在不同温度下对6061铝合金分别进行了氮、氧等离子体浸没离子注入处理，氮与氢混合气体等离子体浸没离子注入处理，以及在氮气氛中的钛或铝等离子体浸没离子注入与沉积处理；采用X射线光电子能谱仪分析了注入改性层的相组成、高温下氧离子注入层的成分及注入离子浓度的深度分布；同时测定了注入改性层的显微硬度及摩擦磨损性能．结果表明：经300℃下氧离子注入处理后铝合金表面形成了较厚的硬质Al2O3层，从而使铝合金表面的耐磨寿命显著延长；经氮／氢混合注入以及氮气氛中金属离子注入和沉积处理后的铝合金表面的抗磨性能显著改善；同单一氮离子注入相比，氮／氢混合注入能更有效地改善铝合金的性能．     

Immersion Calorimetry: Molecular Packing Effects in Micropores

Repeated and controlled immersion calorimetry experiments were performed to determine the specific surface area and pore‐size distribution (PSD) of a well‐characterized, microporous poly(furfuryl alcohol)‐based activated carbon. The PSD derived from nitrogen gas adsorption indicated a narrow distribution centered at 0.57±0.05 nm. Immersion into liquids of increasing molecular sizes ranging from 0.33 nm (dichloromethane) to 0.70 nm (α‐pinene) showed a decreasing enthalpy of immersion at a critical probe size (0.43–0.48 nm), followed by an increase at 0.48–0.56 nm, and a second decrease at 0.56–0.60 nm. This maximum has not been reported previously. After consideration of possible reasons for this new observation, it is concluded that the effect arises from molecular packing inside the micropores, interpreted in terms of 2D packing. The immersion enthalpy PSD was consistent with that from quenched solid density functional theory (QSDFT) analysis of the nitrogen adsorption isotherm.     

PVDF membrane formation by diffusion‐induced phase separation‐morphology prediction based on phase behavior and mass transfer modeling

The equilibrium phase behavior of water (nonsolvent)‐DMF (solvent)‐PVDF system at 25°C was investigated via both theoretical and experimental approaches. Using binary interaction parameters, χ_ij, obtained previously, the theoretical phase boundaries were computed and were found to match closely the measured binodal and crystallization‐induced gelation data. Membranes were prepared using the isothermal immersion‐precipitation processes in various dope and bath conditions. The formed membranes demonstrated a broad spectrum of morphologies: At one extreme, asymmetric structure was obtained featuring a continuous tight skin and a sublayer composed of parallel macrovoids and cellular pores; at the other limit, skinless microporous membrane was produced with spherical particles packed into a bi‐continuous structure. The crystalline characters of PVDF gels and membranes were examined by small angle light scattering, scanning electron microscopy, and differential scanning calorimetry techniques. In addition, diffusion trajectories and concentration profiles in the membrane solution before precipitation were calculated for the immersion process. These results predicted reasonably the various morphologies observed in the membranes. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2079–2092, 1999     

Metastable liquid–liquid and solid–liquid phase boundaries in polymer–solvent–nonsolvent systems

In general liquid–liquid demixing processes are responsible for the porous morphology of membranes obtained by immersion precipitation. For rapidly crystallizing polymers, solid–liquid demixing processes also generate porous morphologies. In this study, the interference of both phase transitions has been analyzed theoretically using the Flory–Huggins theory for ternary polymer solutions. It is demonstrated that four main thermodynamic and kinetic parameters are important for the structure formation in solution: the thermodynamic driving force for crystallization, the ratio of the molar volumes of the solvent and the nonsolvent, the polymer–solvent interaction parameter, and the rate of crystallization of the polymer compared to the rate of solvent-nonsolvent exchange. An analysis of the relevance of each of these parameters for the membrane morphology is presented. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 763–770, 1997