Thermogravimetry of the NiO-Al2O3 system in a hydrogen flow

Thermogravimetry in a hydrogen flow is used to distinguish different forms of NiO-Al₂O₃ bonding at the temperatures of reduction of NiO. The influences of the temperature of preliminary treatment and the component ratio on the shapes of the TG and DTG curves of reduction were represented. By comparison of the results obtained with different weights and with different particle sizes, the influences of diffusion of water vapour in macropores on the characters of TG and DTG curves were studied. Different types of TG and DTG curves of reduction were observed:

1. Curves usual in thermal analysis, whose positions depend on the specimen weight and on the dispersity of the sample.
2. Curves whose position displays almost no change with variations of 1–2 orders the specimen weight.
3. Curves the number of reduction rate peaks in which depend on the experimental conditions.

     

Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Rigorous model of multiwave exposure in optical lithography

A theoretical model of contactless optical lithography with simultaneous participation of several different light waves one of which is incident along the normal to the exposure mask and the remaining are incident obliquely and symmetrically on both sides is considered. The model is based on rigorous solution of the problem of diffraction of a plane optical wave for a simplified 2D diffraction structure consisting of a perfectly conducting finite-thickness screen with a single slot (mask) and a semi-infinite absorbing dielectric located behind the screen (photoresist). The total diffraction field arising in this medium as a result of super-position of different diffraction fields generated by differently directed waves incident on the screen with a slot is analyzed. The quality of reproduction of the optical image of the slot is evaluated using several integrated parameters introduced by the authors earlier. An important case of nanolithography is considered, when the slot width, the screen thickness, and the distance to the medium are on the order of the illumination wavelength. It is found that the optimal value of the slot image quality in this case is attained for two-wave and three-wave regimes of exposure for identical initial phases of incident waves and for angles of incidence of lateral waves from 10° to 20°.     

Oxygen non-stoichiometry and diffusion in RBA2CU3O6+x (R=Y, Gd, Ho) investigated by TG method

By means of thermogravimetry (TG) and chemical analysis equilibrium dependencies of oxygen content in GdBa₂Cu₃O_6+x and HoBa₂Cu₃O_6+x on temperature and were studied. It is found that at equal temperature and the oxygen content in RBa₂Cu₃O_6+x increased in order Ho-Y-Gd.On the basis of Fick 2nd law mathematical procedures to determine diffusion coefficients of oxygen from TG data were developed. The oxygen diffusion coefficients in RBa₂Cu₃O_6+x (R=Y, Gd, Ho) were evaluated in a wide temperature (300–900°C) range (at =0.21 bar). The developed model rather satisfactory decribes oxygen diffusion processes in phases under investigation. It is found that for all studied compounds oxygen diffusion in orthorhombic phase happened faster than in tetragonal one. The values of diffusion coefficients increase in order Ho-Y-Gd with increasing of ionic radius of the rare earth element.     

Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

The multi-functional aspect of scanning holographic microscopy: a review(Invited Paper)

Recent developments in scanning holographic microscopy that offer the prospects of new quantitative tools and imaging modalities in bio, micro, and nano sciences are reviewed. The versatility of the method is emphasized. Scanning holography can operate in an incoherent mode for fluorescence imaging, in a coherent mode for quantitative phase imaging, or in a tomographic mode for axial sectioning and rejection of the out-of-focus haze. Possible applications are illustrated with examples, and future prospects ...     

Primitive Illumination Systems for Families of Convex Bodies in the Plane

Let F= {C₁,C₂,...,C} be a family of ndisjoint convex bodies in the plane. We say that a set Vof exterior light sources illuminates F, if for every boundary point of any member of Fthere is a point in Vsuch that is visible from ,i.e. the open line segment joining and is disjoint from F. An illumination system Vis called primitive if no proper subset of Villuminates F. Let p_max(F) denote the maximum number of points forming a primitive illumination system for F, and letp_max(n) denote the minimum of F) taken over all families Fconsisting of ndisjoint convex bodies in the plane. The aim of this paper is to investigate the quantities p_max(F) and p_max(n).     

Nonself-sustained arc discharge in anode material vapors

The basic characteristics of the nonself-sustained arc discharge in a vapor of the anode material are studied. The influence of thermoemission parameters of the cathode on volt-ampere characteristics of the discharge is described. It is established that in a free mode of the discharge cathode operation, when the discharge current I_D is lower than the current of the thermoelectron emission from the discharge cathode I_C, the deposition rate of the films q is directly proportional to the discharge current I_D. In the compelled mode of the cathode operation, when I_D>I _C, q~W_D², where W_D=I_D U_D with U_D being the discharge voltage. It is shown that the magnetic field increases the plasma density and changes the density profile from n(x)-1/x² to n(x)-1/x with x being a distance along the flow. The motion of created plasma flow is shown to have a noncollisional character with constant electron temperature of 5-7 eV along the flow. The values of plasma potential and electric field in the flow are determined; the values of cathodic and anodic potential drops in the discharge are evaluated. The angular distributions of ion and neutral fluxes in the created plasma flow are described. It is shown that the plasma flows parameters depend substantially on the working material. With use of crossed electric and magnetic fields, the flow ionization coefficient was enhanced up to 85% for the discharge in Ti vapors, and 35% for the discharge in Cu vapors