Manufacturing garnet ferrite film resonators using the chemical etching technique

A procedure of manufacturing microwave resonators on the basis of epitaxial Y₃Fe₅O₁₂ and (Y, Sm, Lu, Ca)₃(Fe, Ge)₅O₁₂ garnet ferrites with thicknesses of ≤5 μm, which are grown on gallium-gadolinium garnet substrates, is described. To obtain circular garnet ferrites—resonators with diameters of 0.5–3.0 mm-via chemical etching in orthophosphoric acid at T = 60–175°C, protecting SiO₂, silicon adhesive, and photoresist coatings are used. It is established that the resonators that were manufactured using a protective FP-383 photoresist coating have the narrowest ferromagnetic-resonance line.     

Picosecond mid-IR laser induced surface damage on Gallium Phosphate (GaP) and Calcium Fluoride(CaF<Subscript>2</Subscript>)

Picosecond mid-IR USPL induced surface damage on a Gallium Phosphate (GaP) and Calcium Fluoride (CaF₂) is reported. A semiconductor GaP and a dielectric material CaF₂, that are transparent over3–10μm, were exposed to one picosecond mid-IR light (4.7μm) to investigate laser-induced surface morphological changes on the target The initiation of damage along the polishing scratch line of GaP and the random location of damage digs on the CaF₂ suggests that the mid-IR picosecond laser-induced damage on targets started from intrinsic surface defects. Multiple pulse irradiations produced periodic corrugated surface structures (ripples) perpendicular to the polarization of light on both GaP and CaF₂. In terms of the orientation and the spacing between ripples, observed ripples have common features with previously reported ripples.     

Automatic discrete-action lines (2 × 1 structure) with sections of different productivity

For an automatic discrete-action line (2 × 1 structure), with section productivities q ₁ > q ₂, an analytical solution is obtained in the case where the random process includes an admixture of determinate processes associated with the system’s transition from one state to another after manufacturing a certain number of parts. In this case, there are too many unknown parameters to employ a mathematical model of the automatic line. No account is taken of simultaneous failure of the sections nor of bunker failure.     

Specimen preparation technique for high resolution transmission electron microscopy studies on model supported metal catalysts

A new technique is described which can be used for preparing transmission electron microscopy (TEM) specimens suitable for high resolution studies on supported metal catalysts. By conventional silicon processing techniques 200 × 200 μm² Si₃N₄ membranes on Si wafers are produced. These membranes are extremely flat and have a uniform thickness of 13 nm. They can be used as a support in various kinds of thin film deposition. A TiO₂ film, optimally structured with respect to the requirements for high resolution TEM work in TiO₂–metal cluster systems, is deposited on the Si₃N₄ layer. It consists of one monolayer of 10–25 nm TiO₂ crystallites. TiO₂ lattice images show that a line resolution down to 0.19 nm is possible. Examples of TiO₂–Pd and TiO₂–Rh are given using respectively photodeposition and impregnation reduction to produce l.5–4 nm metal clusters.     

A wideband converter of the main mode of the coaxial line into the lowest symmetric mode of a circular waveguide

Band-pass (in a 0.5- to 10.0-GHz range) characteristics of a converter based on a coaxial conical line with a cylindrical inner conductor, which excites the TM₀₁ mode of a circular waveguide, are theoretically and experimentally studied. It is shown that the upper frequency of the operating band of this converter is limited by the resonance excitation of the TM ₀₁ ^c mode in the coaxial conical line. Another version of the converter based on the coaxial conical line with a conical inner conductor, in which the conversion bandwidth of 95% TEM mode power into the TM₀₁ mode power is increased to 60%, is designed.     

An extrapolation method for the determination of Cliff-Lorimer kAB factors at zero foil thickness

An extrapolation method is proposed to be useful for the determination of the Cliff-Lorimer k_AB factor at zero foil thickness. The method consists of measuring k_AB factors as a function of the measured foil thickness, t_M, and extrapolating the relationship toward t_M=0. The intersection between the extrapolated line and the ordinate of t_M=0 gives (k_AB)₀ which is free from the effect of absorption. The straight line extrapolation that can be achieved by a linear-least squares method is particularly developed to eliminate arbitrariness introduced in the extrapolation process. The extrapolation method is applied to data available in the literature. It is shown that the method yields the (k_AB)₀ factors compatible with those predicted from the theoretical calculation. It is also shown that this method can circumvent several problems which make it complex and difficult to determine accurate values of the absorption-free k_AB factors. Using the straight line extrapolatioin, it is possible to estimate the degree of the thickness overestimation which arises when the foil thickness is measured by the contamination spot separation (CSS) method. Validity of the straight line extrapolation is further discussed.     

Stretch Vibrations of CH<Subscript>2</Subscript> as a Measure of Conformational and Lateral Orders in Fatty Acid and Phospholipid Layers

The intensity of the line of antisymmetric vibrations of CH₂ in the Raman spectrum of molecular layers of fatty acids and phospholipids is sensitive both to the molecular order in the layer (lateral order) and to the conformational order of the hydrocarbon chain of the molecule. Though the intensity of this line is widely used as an indicator of order in molecular layers containing hydrocarbon tails, the nature of sensitivity of the line of antisymmetric vibrations to the order is still disputable. This issue has been experimentally studied, and it has been demonstrated that disordering leads to redistribution of vibrational modes and to changes in polarizability of antisymmetric vibrations. A hypothesis is proposed that the intensity of the line of the Raman scattering of antisymmetric vibrations of CH₂ is determined to a large extent by their interaction with electron excitation of the hydrocarbon chain.     

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication problems

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication (EHL) problems is presented. First, by introducing a special matrix splitting iteration method into the traditional compound direct iterative method, the full matrices for the linear systems of equations are transformed into sparse banded ones with any half-bandwidth; then, an extended Thomas method which can solve banded linear systems with any half-bandwidth is derived to accelerate the computing speed. Through the above two steps, the computational complexity of each iteration is reduced approximately from O(N ³/3) to O(β ² _N), where _N is the total number of nodes, and β is the half-bandwidth. Two kinds of numerical results of transient EHL line contact problems under sinusoidal excitation or pure normal approach process are obtained. The results demonstrate that the new algorithm increases computing speed several times more than the traditional compound direct iterative method with the same numerical precision. Also the results show that the new algorithm can get the best computing speed and robustness when the ratio, half-bandwidth to total number of nodes, is about 7.5%–10.0% in moderate load cases.     

Single-Frequency TEA CO<Subscript>2</Subscript> Laser for Experiments on Non-Resonant Radiation Interaction with Matter

The design philosophy and output radiation parameters of single frequency TEA CO₂ laser with bleaching intracavity longitudinal modes selector (cell filled with SF₆) are described. At cavity tuning to 10P(16) line and choosing optimum SF₆ pressure in the cell the stable single frequency lasing is realized with scatter of radiation peak power in a series of “shots” less than ±7% of average value. The radiation energy density and intensity gradually tuned in the ranges 0.36–12.5 J/cm² and 2.9–100 MW/cm² correspondingly were realized in the focal plane of a lens with f = 127 mm.     

Features of the mechanism of formation of X-ray shadowgraphs in scintillation crystals

A digital X-ray imaging system based on a luminophor-lens-CCD-array structure [1] is used to obtain a spatial resolution of 25 line pairs/mm [2]. Such a high resolution is attained, in particular, owing to the use of CsI(Tl) and BGO (Bi₄Ge₃O₁₂) single crystals as X-ray converters.     

Determining the constants of integration for automatic lines with determinate processes

In the study of automated lines, a method is proposed for determining the constants of integration in the case of the general solution when the productivities of different sections of the line are unequal (q ₁ > q ₂ or q ₁ < q ₂) and the particular solution when q ₁ = q ₂. This method provides the basis for the solution of all problems regarding 2 × 1 automatic lines with deterministic processes.     

Simultaneous measurement of CO and CO2 at elevated temperatures by diode laser wavelength modulated spectroscopy

One single semiconductor distributed-feedback (DFB) laser is used to demonstrate the possibility of simultaneous measurements of CO and CO₂ at elevated temperatures. Wavelength modulation spectroscopy with second-harmonic detection is used to improve the detection sensitivity and accuracy. The concentrations of CO and CO₂ are determined from the WMS-1-normalized absorption-based WMS-2f signal peak heights of a proper line pair of CO and CO₂ near 6357.814 cm⁻¹ and 6357.312 cm⁻¹, which are selected using some line-selection criterions for the target temperature range of 300–1000 K. The CO and CO₂ concentrations measurements are within 2.86% and 2.69% of the expected values over the tested temperature range 300–1000 K. The minimum detectable concentrations of CO and CO₂ at 1000 K are 250 ppm m and 280 ppm m respectively.     

CO2 LASER PHOTOACOUSTIC SPECTROSCOPY AND ABSOLUTE ABSORPTION COEFFICIENTS OF SHORT CHAIN SATURATED FATTY ACID VAPOURS

Abstract

A resonant photoacoustic cell, capable of contamination free operation at temperatures above that of the ambient, was constructed and used to determine absolute absorption coefficients of C6:0 (hexanoic) and C8:0 (octanoic) fatty acid vapours at CO₂ laser wavelengths. At atmospheric pressure, the maximum absorption coefficients at the 9R(32) line of the CO₂ laser (1085.77cm^?1) are 8.0 atm^?1 cm^?1 (C6:0 at 332K) and 8.9 atm^?1 cm^?1 (C8:0 at 342 K).

     

A universal slip-line model with non-unique solutions for machining with curled chip formation and a restricted contact tool

A universal slip-line model and the corresponding hodograph for two-dimensional machining which can account for chip curl and chip back-flow when machining with a restricted contact tool are presented in this paper. Six major slip-line models previously developed for machining are briefly reviewed. It is shown that all the six models are special cases of the universal slip-line model presented in this paper. Dewhurst and Collins's matrix technique for numerically solving slip-line problems is employed in the mathematical modeling of the universal slip-line field. A key equation is given to determine the shape of the initial slip-line. A non-unique solution for machining processes when using restricted contact tools is obtained. The influence of four major input parameters, i.e. (a) hydrostatic pressure (P_A) at a point on the intersection line of the shear plane and the work surface to be machined; (b) ratio of the frictional shear stress on the tool rake face to the material shear yield stress (τ/k); (c) ratio of the undeformed chip thickness to the length of the tool land (t₁/h); and (d) tool primary rake angle (γ₁), upon five major output parameters, i.e. (a) four slip-line field angles (θ, η₁, η₂, ψ); (b) non-dimensionalized cutting forces (F_c/kt₁w and F_t/kt₁w); (c) chip thickness (t₂); (d) chip up-curl radius (R_u); and (e) chip back-flow angle (η_b), is theoretically established. The issue of the “built-up-edge” produced under certain conditions in machining processes is also studied. It is hoped that the research work of this paper will help in the understanding of the nature and the basic characteristics of machining processes.     

Stoichiometry and valence measurements of niobium oxides using electron energy-loss spectroscopy

Qualitative and quantitative electron energy‐loss spectroscopy analyses have been performed on niobium and stable niobium oxides (NbO, NbO₂ and Nb₂O₅). At integration windows (Δ) greater than 75 eV, k‐factor analysis can be used to distinguish between the stoichiometry of the three oxides within 5.7% error. As seen in other metal oxides, with increasing oxidation state the metal ionization edges shift to higher energies relative to the O‐K edge. Normalized M_2,3 white‐line intensities show a strong correlation with 4d occupancy for each compound. The data are in correspondence with that observed in the literature for 4d transition metals using normalized L_2,3 white lines. Lastly, a distinctive energy‐loss near‐edge, structure of the O‐K edge was observed for each oxide, which could be used as a fingerprint for analysis of unknowns.     

Structure and performance of welding joint of Q235 steel welded by SHS welding

A self-propagating high-temperature synthesis (SHS) welding-pen that can weld steel workpiece from 6 to 10 mm is developed and welds the Q235 steel. The structure and properties of the welding joint are studied. The result indicates that this type of welding is melting and the fusion zone is clear. The tensile-strength of the welding joint is 283 MPa, flexural strength is 628 MPa, impact toughness is 46.43 J·cm⁻², and the microhardness of the welding joint and fusion zone are 230 HV_0.1 and 255.6HV_0.1, respectively. The mircohardness of the fusion zone and the welding line are higher than that of the matrix.     

A laser analyzer of the kinetics of interaction of water molecules with an adsorbent

A device for recording high-speed processes of water-vapor sorption at the surfaces of porous materials is described. The water-vapor pressure over a sample is measured during the sorption process by registering the integral intensity of the absorption line of H₂O molecules at a wavelength of 1.85 μm. The kinetic curves of changes in the partial pressure (concentration of H₂O molecules) from 1 mTorr to 20 Torr are recorded in a time range from 1 ms to 24 h with an accuracy better than 1% at buffer-gas concentrations of 0–760 Torr. The obtained data are used to determine the sorption and structural parameters of investigated materials.     

Capacitive and barrier discharge excilamps and their applications (Review)

The results of studies, development works, and tests of barrier-and capacitive-discharge excilamps radiating in the UV and VUV spectrum regions are presented. The main information on the designs of radiators and generators is presented. The spectral, temporal, and energy characteristics of excilamps based on the emission of KrCl*, XeCl*, XeI*, XeBr*, KrBr*, Xe*₂, Br*₂, and Cl*₂ molecules and the I* atomic line are described. It is shown that the created generators and sealed-off radiators have long service lives. Examples of specific applications of excilamps are presented.     

Arsenic trioxide inhibits the activity of SphK1 by decreasing the level of phosphatidylserine and phosphatidic acid in the human gastric cancer cell line MGC-803

Sphingosine kinase 1 (SphK1) is an important synthetase during the synthesis of sphingosine-1-phosphate (S1P) from sphingosine (Sph). Previous studies demonstrated that arsenic trioxide (As₂O₃) could reduce the level of S1P in human gastric cancer cell line MGC-803, indicating that As₂O₃ may inhibit the activity of SphK1. In this study, the effect of As₂O₃ on the SphK1 activation pathway was investigated. Western blot and quantitative real-time PCR analysis were used to evaluate the changes in protein and mRNA levels. The multi-dimensional mass spectrometry-based shotgun lipidomics method (MDMS-SL) was used for the quantitative detection of phosphatidylserine (PS) and phosphatidic acid (PA). The results revealed that As₂O₃ did not affect the protein and mRNA expression of SphK1 in the MGC-803 cells. However, As₂O₃ increased the levels of p-ERK1/2 and CIB1 in the SphK1 activation pathway and decreased the levels of PS and PA in the MGC-803 cells. The outcomes suggested that As₂O₃ may enhance the activity of SphK1 by increasing the levels of p-ERK1/2 and CIB1 and decrease the activity of SphK1 by decreasing the levels of PS and PA. It was suggested that the inhibition effect is stronger and resulting in an overall decrease in the activity of SphK1.     

A ГИН-1200 high-voltage pulse generator

The electric circuit, design, and electric and triggering characteristics of the ГИН-1200 small-sized 12-stage high-voltage pulse generator used for charging a double forming line to 1 MV for a 300-ns period are described. The generator is mounted in a metallic housing with the transformer-oil insulation. The storages in stages of the generator are KMK 100–0.017 (100 kV, 0.017 μF) capacitors with a 1-kJ total stored energy. The switches are trigatron gaps filled with a 20% SF₆ + 80% N₂ gas mixture. The gap housings are assembled into one line. The through-passing axial channel ensures spark illumination of adjacent intervals, thereby improving the triggering characteristics of the generator. The operation-time scatter of the ГИН-1200 generator at an 85-kV charging voltage and 65% electric-strength margin was ≤10 ns, and the operation delay time was ～100 ns. The ГИН-1200 generator operated ～2000 times and demonstrated reliable stable operation.