Ultrasonics in the dehydration process of sludge

This paper discusses from the physico-chemical point of view the increase of the dehydration efficiency of sludge from some selected mineral and organic sewages as a result of preliminary ultrasound irradiation and the addition of ion-active flocculants.     

Biomolecular absorption of ultrasound: II. Molecular structure

Measurements of absorption coefficients in several globular and linear proteins yield no correlations of absorption with alpha-helix content or with the number of polypeptide chains in the protein. Removal of all but the primary structure with denaturing agents that convert proteins to random chains causes only small changes in the absorption of globular proteins. Complete denaturing of linear muscle proteins results in large reductions in absorption. Therefore, it is concluded that absorption in globular proteins is insensitive to structural characteristics while in linear proteins it is dependent upon the amount of alpha-helix content. An alternative explanation of the results is that alpha-helix contributes to absorption in both globular and linear proteins but tertiary structure in globular proteins reduces absorption because of inhibited solvent interactions.     

Galilean inertial structure. II

Galilean space-time is characterized in an axiomatic manner within a certain class of fiber bundles over the time axis IR. The distinction comes about through an examination of the inertial structure constituted by the entirety of the inertial trajectories. The latter are defined geometrically as a relation on the space-time expressing the situation of relative rest for events.     

Determination of the optical characteristics of thin film coatings. II

The applicability of formulas obtained earlier by the author for determining the important optical characteristics of films comparable in thickness to the wavelength of light are discussed in this paper. Corroborative experimental data for amorphous films of titanium dioxide prepared by chemical means and heated for 1 hr in air at 600 ° C are reported. Values of the index of refraction calculated by the author's method are compared with data obtained using A. S. Valeev's interference method [5]. A new formula for determining the transmittance of films in a highly absorbing region is presented, which ensures better convergence of the approximating series.     

Canonical structure of soliton equations: II. The Kaup-Newell system

The canonical structure of the Kaup-Newell system, i.e. the family of the derivative nonlinear Schrödinger equation and its generalizations, is discussed.     

Study on crystalline to amorphous structure transition of Cr coatings by magnetron sputtering

The influence of deposition rate on crystalline to amorphous microstructure transition of Cr coatings was studied through preparation of Cr coatings deposited onto silicon wafers using magnetron sputtering technique. The microstructure and morphology of Cr coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results show that Cr coating prepared at 400 W exhibits dense columnar crystalline structure and the crystallite size and crystallization rate are increased expressly in the initial 5 min. When the deposition rate achieved to the maximum, Cr coating shows a case of infinite periodic renucleation where new crystals are assumed to be nucleated periodically on the surfaces of growing crystals and strong persistence of the columnar growth morphology is apparent. However, Cr coating exhibits overall microstructure of amorphous phase mixed with a few nano-crystal grains as the deposition rate decreases to the minimum.     

六水氯化镁脱水蓄热过程的数值模拟

六水氯化镁(MgCl2·6H2O)由于较强的吸附能力、低反应焓以及较高的储热效率,成为当今热化学储能常用的材料.建立六水氯化镁脱水蓄热过程二维数值模型,将质量、动量、能量与化学反应物理场进行耦合,研究反应床的温度与转换程度分布,同时对反应器内自由空气流道的布置进行结构优化设计.讨论了入口流体流速和温度、材料孔隙率以及导...     

Control of the structure and stress state of thin films and coatings in the process of their preparation by ion-plasma methods

A system analysis of the influence of the substrate temperature during deposition on two main factors (nanodimensionality of structural aggregates and high stresses) responsible for the nonequilibrium state of the materials of ion-plasma-deposited films and coatings has been performed. It has been shown that an increase in the temperature during deposition leads to a preferred growth of nanocrystallites in the direction of incidence of film-forming particles, which, in turn, results in the formation of an anisometric crystal structure. The main causes of the generation of high elastic stresses in ion-plasma condensates are the ion/atom bombardment in the process of deposition (which stimulates the development of compressive stresses) and the difference in the thermal expansion coefficients of the condensate and substrate materials (which initiates the development of thermal stresses; the sign is determined by the difference between the thermal expansion coefficients of the condensate and substrate materials). An increase in the temperature during deposition results in the relaxation of compressive stresses stimulated by the ion/atom bombardment and in an enhancement of the influence of thermal stresses on the state of the ion-plasma condensate. This makes it possible to control the stress state of ion-plasma films and coatings by purposefully varying the substrate temperature during deposition.     

The structure and tribological behaviors of CrN and Cr-Ti-N coatings

The Cr-Ti-N coatings with different composition were deposited in a medium frequency magnetron sputtering system on Si (1 1 1) substrates. The structures, surface morphology and wear properties were measured. The binary CrN coatings, formed a single-phase fcc structure with nearly random (1 1 1), (2 0 0) and (2 2 0) orientation, while for the Ti was introduced, coatings show a preferred orientation of (2 0 0). Cr-Ti-N coating shows a much smoother surface than CrN coating. Cr-Ti-N coating with 31.75% Ti content shows the best wear behavior. The excellent tribological properties of this composition coating are corresponding to the solid solution nitride structures.     

Transfer process of multilayer optical coatings for patterned components

The capability to transfer a multilayer coating from the initial substrate on which it was deposited to another one is an interesting technique for the manufacturing of patterned components with a high number of different filters such as stripe filters. The two major technological steps of the transfer, namely the removal from the initial substrate, and the bonding onto the new one, are described in this paper. The principle of this approach is validated by the transfer of a band-pass filter with the typical sizes of a stripe.     

Molecular structure and optical properties of PTFE-based nanocomposite polymer-metal coatings

The molecular organization of polytetrafluoroethylene (PTFE) thin coatings with incorporated Ag, Cu, and Mo nanoparticles that are deposited from an active gas component has been studied. Polyethylene terephtalate film coated by aluminium served as a substrate. The active gas component was produced by electron beam dispersion of original components in vacuum. The effect of metal particle size and its nature on the molecular structure of coatings have been investigated. Dichroism of thin nanocomposite coatings has been examined by polarized Fourier transform infrared spectroscopy using an attenuated total reflection unit. The morphology of the coatings has been analyzed by transmission (TEM), atomic-force (AFM), and scanning electron (SEM) microscopy. It is found that introduction of a metal (Ag or Cu) yields oriented layers at a lesser efficient thickness of a coating. The surface plasmon resonance of such structures was studied by measuring optical absorption of the coatings in the ultraviolet and visible ranges. The results show that the composite coatings containing Ag clusters are diameter less than 30 nm and absorb within the short-wave range from 400 to 550 nm.     

Deposition of TiSiN coatings by arc ion plating process

Titanium silicon nitride (TiSiN) thin films were deposited on tungsten cemented carbide tools by cathode arc ion plating (AIP) process using alloy TiSi targets. The effects of silicon addition and negative substrate bias on the development of the textures of films were studied systematically by varying the bias voltage from −20 to −200 V. The structural features of the films were investigated in detail using X-ray diffraction. The effect of the texture on such mechanical properties as hardness and adhesion of the films was also studied. A maximum hardness of 42 GPa was obtained at a DC substrate bias of −150 V. The characteristics of TiSiN thin films exhibited excellent adhesion of over 150 N. The cutting performance of end-mills and drillers was evaluated by milling and drilling of highly hardened material under high-speed cutting conditions. The results reveal that cutting tools with TiSiN coatings markedly outperformed those with TiN coatings, and the uncoated cutting tools. TiSiN coating increased the cutting lifetime to seven times that of the uncoated one.     

Quark antisymmetrization and deep-inelastic scattering II. Nuclear structure functions

We consider the effects of quark antisymmetrization for nuclear structure functions. Antisymmetrizing the naive folding of nuclear wave functions in terms of nucleons and the nucleon wave function in terms of quarks, introduces additional contributions. Using the calculated results on quark three-momentum distributions, we calculate the effects on the deep-inelastic structure functions for s- and p-wave nuclei. The effects of quark antisymmetrization turn out to be small.     

Ion-beam analysis of the structure and composition of nanocomposite nc-TiC/a-C:H coatings

The structure and composition of nanocomposite nc-TiC/a-C:H thin films prepared by closed-field unbalanced reactive magnetron sputtering in an argon-acetylene atmosphere have been investigated. The concentrations of carbon and heavier elements have been obtained by Rutherford backscattering and nuclear backscattering. The hydrogen concentration in the films has been determined by elastic recoil detection analysis. Based on the data obtained, a scheme has been proposed to evaluate the C:H matrix mass density and the sp ³ and sp ² fractions in the matrix.     

Electronic structure of high-temperature superconductors II. La-Ba-Cu-O systems

Electronic structure of La_2–x Ba _x CuO₄ superconductors has been studied. Model systems La₁₀CuO ₂₂ ^–12 , La₁₀cuO ₁₄ ⁺⁴ and La_gBaCuO ₁₄ ⁺³ with various Ba positions have been investigated using the quasirelativistic INDO molecular orbital method. The oxidation state of copper atoms corresponds to Cu(II). The influence of Ba/La substitution on copper atoms is much lower than on their oxygen ligands sphere.     

Geometry of crystal structure with defects. II. Non-Euclidean picture

The following point of view is geometrically formulated and its consequences examined: the lattice of a crystalline body with a continuous distribution of dislocations can be locally described as an ideal lattice in non-Euclidean space. The types of distribution of dislocations are described by the classification of three-dimensional real Lie algebras. The influence of point defects and the elastic deformation field on the geometry of the material structure of a crystalline body with dislocations is examined. The case where a crystal with dislocations reacts as a body with internal rotational degrees of freedom is discussed.     

Study of the phase composition and structure of composite coatings based on transition-metal oxide compounds via X-ray diffraction and X-ray absorption fine structure spectroscopy

The phase composition of composite coatings based on transition-metal oxides deposited from aqueous solutions of their salts on steel surfaces under polarization by an asymmetric alternating current is determined. X-ray absorption fine structure spectroscopy is used to study the charge state of molybdenum contained in the coatings.     

Numerical analysis and synthesis of electron-optical systems of complex structure. II

The numerical analysis and synthesis of intrinsically three dimensional electron-optical systems with complex structures are examined. Zh. Tekh. Fiz. 68, 126–129 (July 1998)     

Laser sintering of perovskite-oxide and metal coatings by the sol gel process

This paper presents a novel laser technique for the formation of metal Ag and perovskite-oxide La_xSr_1-xCoO₃ coatings. Metallic Ag and La_xSr_1-xCoO₃ are conductive materials with applications as resistors and as electrodes in the microelectronics area. Suitable precursors in the form of sol gels are placed on substrates and are subsequently sintered by high-power laser irradiation. The Ag precursor is an aqueous sol of nanosized particles, while for the La_0.8Sr_0.2CoO₃, a sol gel type precursor is used. Substrates (e.g., fused silica) are coated with the precursor solutions by spinning and are dried to stable solid layers. The coatings are cured and sintered to a defined pattern by means of a 3-kW CO₂ laser beam scanned over the whole substrate surface. The microstructure of the coatings was examined by the use of scanning electron microscopy and X-ray diffraction, and the electrical properties were measured by the four-point resistivity method. The La_0.8Sr_0.2CoO₃ coatings had a perovskite cubic structure with a lattice constant of 0.383 nm. The resistivity of the coatings was 30 mQ cm, and the temperature dependence of the resistivity was 1.8 mQ cm/°C. Metallic Ag coatings with a thickness of 100-170 nm were obtained with a resistivity of 20 7Q cm. This new technology is promising for the growth of three-dimensional (3-D) structures and multilayers, especially because it can be introduced in industrial scale production.     

Electrical and structural investigations of perovskite structure reactively sputter deposited coatings

Sr(Zr_0.84Y_0.16)_0.91O_3 ? δ (SZY) and Ba(Zr_0.84Y_0.16)_0.96O_3 ? δ (BZY) protonic conductor coatings were co-sputter deposited from metallic targets in argon–oxygen reactive gas mixtures. The chemical and structural features were investigated by energy dispersive X-ray spectroscopy and X-ray diffraction, and their morphology was assessed by scanning electron microscopy of the surface and of brittle fracture cross sections. The electrical properties of the coating were determined by complex impedance spectroscopy as a function of temperature in air. Relationships are established between the electrical properties and the morphology of the coatings. The SZY as deposited coatings is amorphous and crystallises under the convenient perovskite structure after annealing treatment at 873 K under air. The BZY as deposited coatings is crystallised at 523 K in situ under perovskite structure and a further annealing treatment increases the grain size. Conductivities and activation energies of crystallised coatings were 3.1 · 10^? 5 S cm^? 1/2 · 10^? 5 S cm^? 1 and 0.65 eV/0.71 eV after stabilization at 773 K for strontium and barium zirconate, respectively.