MCM-41 deposition on alumina ceramic foams

Alumina-based macro-porous ceramic foams were successfully coated with MCM-41 meso-porous materials using an in-situ one step hydrothermal synthesis. Low H₂O/NaOH ratio in the starting mixture leads to a not uniform deposition of the meso-porous materials. Using higher H₂O/NaOH ratio and two cycles of deposition, a CF with a continuous and thick layer of well-ordered MCM-41 material coating was produced.     

大型长廊阻抗式调压室三维非线性数值分析

采用三维非线性有限元分析方法，结合泸定水电站调压室的开挖，模拟了大型长廊阻抗式调压室开挖和支护的施工过程。利用改进的锚杆单元模拟支护结构中锚杆的作用。分别从围岩稳定和衬砌结构的受力特性两个方面对调压室进行了分析，给出了围岩支护和结构设计的基本分析方法．可为类似工程提供借鉴。     

Strict regulation of c-Raf kinase levels is required for early organogenesis of the vertebrate inner ear

Regulation of organogenesis involves a dynamic balance of the mechanisms regulating cell division, differentiation and death. Here we have investigated the pattern of expression of c-Raf kinase in the inner ear during early developmental stages and the consequences of manipulating c-Raf levels by misexpression of c-raf viral vectors in organotypic cultures of otic vesicle explants. We found that otic vesicles expressed c-Raf and its level remained constant during embryonic days 2 and 3 (E2-E3). c-Raf activity was increased in response to insulin like growth factor-I (IGF-I) and the activation by IGF-I of the c-Raf kinase pathway was a requirement to turn on cell proliferation in the otic vesicle. Overexpression of c-raf in E2.5 explants increased the proliferative response to low serum and IGF-I and blocked differentiation induced by retinoic acid. The increase in c-Raf levels also prevented nerve growth factor (NGF)-dependent induction of programmed cell death. Consistent with these results, the expression of a dominant negative c-Raf mutant potentiated retinoic acid action and decreased the rate of cell proliferation. We conclude that a strict control of c-Raf levels is essential for the co-ordination of the biological processes that operate simultaneously during early inner ear development.     

How to visualize the spider mite silk?

Tetranychus urticae (Acari: Tetranychidae) is a phytophagous mite that forms colonies of several thousand individuals. Like spiders, every individual produces abundant silk strands and is able to construct a common web for the entire colony. Despite the importance of this silk for the biology of this worldwide species, only one previous study suggested how to visualize it. To analyze the web structuration, we developed a simple technique to dye T. urticae'silk on both inert and living substrates. Fluorescent brightener 28 (FB) (Sigma F3543) diluted in different solvents at different concentrations regarding the substrate was used to observe single strands of silk. On glass lenses, a 0.5% dimethyl sulfoxide solution was used and on bean leaves, a 0.1% aqueous solution. A difference of silk deposit was observed depending the substrate: rectilinear threads on glass lenses and more sinuous ones on bean leaves. This visualizing technique will help to carry out future studies about the web architecture and silk used by T. urticae. It might also be useful for the study of other silk-spinning arthropods. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc.     

Property estimation using structural characterizations: Heat capacities of coal liquids

Three coal liquids were characterized by estimating the concentrations of the functional groups present in the liquids. The concentrations were deduced using data from Chromatographic separations, elemental analysis, ¹H n.m.r., ¹³C n.m.r. and mass spectrometry. The concentration estimates were then used, in conjunction with simple group additivity rules, to estimate the heat capacities of the liquids as a function of temperature. The heat capacity estimates were in excellent agreement with experimentally determined values.     

Hybrid dynamical systems theory and the Signal language

The logic and synchronization characteristics of general dynamical systems called hybrid dynamical systems (HDS) are studied. The theory is related to discrete event dynamical system theory, but handles numerics as well as symbolics. It is supported by the programming language Signal and a mathematical model of general implicit dynamical systems. The core of the theory is the notion of HDS resolution which is based on a coding of any HDS into a dynamic graph which consists of a skew product of a polynomial dynamical system on the finite field of integers modulo 3 (to describe the transitions of the underlying automation) and directed graphs (to describe how data dependencies dynamically evolve). The resolution algorithms are based on the study of this dynamical system     

Machining induced residual stress in structural aluminum parts

Machining operations of aluminum structural parts are typically carried out under high feeds and high cutting speeds. Under these conditions, high thermomechanical loads are exerted on the workpiece, which may result in changes in the subsurface material. Residual stresses can be one of the machining induced changes and can lead to considerable rejection rates caused by part distortion. Due to their significant economic importance, it is essential to understand the influence of the machining process on the residual stresses in aluminum. This paper presents the influence of the machining parameters as well as the cutting edge geometry on residual stress of workpieces made out of a forged aluminum alloy.     

Precipitation of an ordered intermetallic phase in WC-10% Ni

The cause of the variability of the intensity of magnetization of the nickel binder phase in cemented carbides was sought by electron diffraction and dark-field microscopy studies of fractured specimens, one of which was partially magnetic and the other almost non-magnetic. A coherent phase in the nickel binder having either a b c c or a CsCI-type structure was found on the boundaries of crack paths. A coherent non-randomly arranged CsCI-type phase was found in an epitaxial relationship with (12.0) planes of WC. The lattice parametera=0.295 nm for both coherent phases. This phase or phases occurs more frequently in non-magnetic than in magnetic nickel binders of hardmetals. When seen near WC grains the ordered phase is often accompanied by randomly arranged tungsten trioxide particles. The implication is that the ordered phase occurs more readily in carbon-deficient surroundings. The phase is postulated to be NiW because large quantities of tungsten are known to form solid solutions with nickel.     

Current and current density limitations in existing electron storage rings

Storage rings dedicated for synchrotron light sources must show good beam performances in order to obtain high flux and brilliance. In particular bunch length, energy spread, beam intensity and transverse emittances have to satisfy special requirements.We intend here to briefly overview twenty years of experience obtained with small and medium size storage rings which were initially built as high energy physics facilities. The limiting effects will be extensively discussed by comparing theoretical models with systematic experimental studies.The possible means to remedy the inconveniences are also mentioned.