Fabrication of a heterodyne receiver OEIC with optimized integration process using three MOVPE growth steps only

An optimized integration process is reported requiring only three epitaxial growth steps for the fabrication of an OEIC encompassing a single-mode laser, a waveguide element, and fast photodiodes. The process was applied to the fabrication of a heterodyne receiver including a semi-insulating buried heterostructure (SIBH)-DFB-laser with an output power of 14 mW and a side-mode suppression ratio greater than 40 dB, a 3-dB coupler, and high-speed balanced photodiodes with a bandwidth of 9 GHz. The laser can also be used as a transmitter laser exhibiting a modulation bandwidth of 11 GHz.     

Highly efficient ceramic catalytic blocks with a honeycomb structure

Compositions and technologies are suggested for preparing highly efficient catalyst blocks with a honeycomb structure to be used for reducing nitrogen oxides with ammonia in flue gases from thermal power plants. The blocks have high structural strength and catalytic activity.     

Fractional composition of partly hydrolysed polyvinyl acetate and its compatibility with hydroxypropyl methylcellulose in aqueous solutions

Fractionation of partly hydrolysed polyvinyl acetate (PVA) was performed by warming of its aqueous solutions. The following properties of the obtained fractions were determined: viscosity, molecular weight and molecular weight distribution, surface tension, and absorbance in the IR range. The blockiness of the polymer molecules, characterized by their behaviour towards iodine-containing systems such as I₂,-H₃BO₃ and I₂,-KI, was estimated. Fractionation of the aqueous solutions of PVA by warming is based mainly on the different internal molecular structure of the separated products, i.e. on the length of the vinyl acetate blocks in the PVA molecules and, to a lesser extent, on the degree of hydrolysis and the degree of polymerization. The more blocklike are the PVA molecules, the less compatible are the polymers in the PVA-hydroxypropyl methylcellulose (HPMC)-water system. At phase separation in this sytem the PVA molecules which are not compatible with HPMC are, in the first place, those of the highest blockiness.     

Parameter evaluation in automated digital deep-level transientspectroscopy (DLTS)

A method of directly evaluating the activation energy ΔE, capture cross section σ, and density N_T, of deep-level traps from the pulsed reverse bias capacitance transient is described. The main advantages of this technique are that it requires only a single temperature scan, and it can resolve nonexponential transients due to closely-spaced energy levels. The test samples used for this paper consisted of Schottky diodes fabricated on nonirradiated and 1-MeV electron-irradiated n-type VPE (vapor-phase epitaxy) GaAs wafers. The well known EL2 trap was identified with ΔE of 0.81 eV, and σ _n of 1.0×10^-13 cm² for the nonirradiated sample. These values were found to be in good agreement with published data using established, conventional DLTS techniques. For the irradiated samples a nonexponential capacitance transient was found in the EL2 range of temperatures. The discussed technique was able to resolve two closely spaced deep levels lying at E_c-0.81 eV and E_c-0.84 eV, and with capture cross sections of 1.5×10^-13 cm² and 2.5×10^-12 cm², respectively     

Effect of L-carnitine treatment on very low density lipoprotein kinetics in the hyperlipidemic rabbit

This study examined the hypolipidemic effect of 4 weeks of L-carnitine treatment (170 mg/kg b.w./day) in New Zealand White rabbits fed a high fat diet (5% corn oil/0.5% cholesterol). Specifically, [3H] glycerol and [125I] very low density lipoprotein (VLDL) turnover studies were conducted to examine the effect of treatment on VLDL kinetics. The masses of plasma VLDL-triglycerides (VLDL-TG) and VLDL-apoprotein B (VLDL-apoB) were significantly increased by the high-fat diet. Four weeks of treatment with L-carnitine significantly reduced these masses. Kinetic analysis indicated that fat feeding reduced the fractional catabolic rates (FCRs) of VLDL-TG and VLDL-apoB relative to chow-fed controls. The transport of these VLDL components was not altered by the diet. L-carnitine treatment had no effect on the FCRs of VLDL-TG and VLDL-apoB or on the transport of VLDL-apoB. Yet, treatment significantly lowered the transport of VLDL-TG. These data indicate that the lipid-lowering effect of L-carnitine in this animal model was due, in part, to a decrease in the transport and not due to an alteration in the fractional catabolic rate of VLDL-TG.     

Modified refraction-interference method for calculating the geometric and optical parameters of optical waveguides

We describe a ray method for analysis of the geometric and optical characteristics of two-layer fiber optical waveguides. We have analyzed the effect of the polarization of the illuminating beam on the overall pattern of the intensity distribution. We consider the characteristic types of rays for a single-layer and two-layer fiber optical waveguide. We have obtained definitive dependences of the beam intensity for each ray individually. We have developed a program for calculation of the scattering pattern in fiber optical waveguides illuminated by a broad beam. Translated from Izmeritel'naya Tekhnika, No. 3, pp. 39–42, March, 1996.     

Wind energy systems

Wind energy has matured to a level of development where it is ready to become a generally accepted utility generation technology. A brief discussion of this development is presented, and the operating and design principles are discussed. Alternative designs for wind turbines and the tradeoffs that must be considered are briefly compared. Development of a wind energy system and the impacts on the utility network including frequency stability, voltage stability, and power quality are discussed. The assessment of wind power station economics and the key economic factors that determine the economic viability of a wind power plant are presented     

The Bi-Rb (bismuth-rubidium) system

This work was supported by ASM International. Literature searched through 1988. Dr. Pelton is the Alloy Phase Diagram Program Co-Category Editor for binary alkali alloys.