Multi-H phase-coded modulations with asymmetric modulationindexes

Multi-H phase-coded modulation (MHPM) is a bandwidth-efficient modulation scheme which offers substantial coding gain over conventional digital modulation schemes. MHPM with asymmetric modulation indices corresponding to the bipolar data +1 and -1 is considered, and numerical results for the minimum Euclidean distances are provided. It is shown that performance improvements on the error probability over conventional MHPM are gained with essentially the same bandwidth and a very slight modification in implementation. The upper bounds on the error probabilities as functions of observation intervals and received E_b/N₀ are also investigated in detail. It is concluded that the concept of asymmetric modulation indices for MHPM is attractive for bandwidth and power-efficient modulation     

Development of sealing compositions with nanostructure iron-based fillers

The possibility of utilizing nanopowders of iron and Fe-Co-Ni produced bu a thermochemical method in the fabrication of sealing composition materials is investigated. It is established that such hermetic sealing composition materials function reliably under extremal conditions and guarantee elevated strength of adhesion to the surface of the metal and high corrosion and temperature stability. __________ Translated from Poroshkaya Metallurgiya, Nos. 3–4(448), pp. 112–117, March–April, 2006.     

Construction of transmission lines above valuable standing timber

Problems with the construction of transmission lines above a forest are examined. Construction of lines above standing timber makes it possible to shorten the length of the route, eliminate the clearing of a continuous swath along the line, and reduce the volume of in-service work. To implement this solution, it is necessary to introduce changes and supplements to existing regulatory technical documents. __________ Translated from élektricheskie Stantsii, No. 10, October 2007, pp. 48–51.     

Adaptive control of diamond drilling of nonmetallic materials

The basic principles for selecting the work regimes for diamond drilling of nonmetallic materials are presented. The process of microcutting by a single diamond grain is examined, and relations between the components of the cutting force and the ratio of the rate of the main motion to the feed rate are obtained on the basis of known relationships. It is shown that adaptive control of the drilling nonmetallic materials is possible using two-circuit systems — one for feed-rate control and one for cutting-rate. __________ Translated from Steklo i Keramika, No. 3, pp. 28–30, March, 2007.     

A compact full MMIC module for Ku-band phase-lockedoscillators

A compact Ku-band phase-locked oscillator module has been developed in a full MMIC (monolithic microwave integrated circuit) configuration. The module includes an MMIC voltage-controlled oscillator, an analog frequency divider, and interstage amplifiers. The constituent monolithic chips are integrated in a very small single-package module and operate at the target frequencies without any external trimming or matching network. The oscillator is tuned more than 1 GHz with a constant output amplitude. The frequency-divided output is also obtained over the whole tuning range. Spurious output is not found at any frequency up to 22 GHz. In spite of the very low-Q factor of GaAs monolithic circuitry, the oscillator phase noise exhibited is less than -80 dBc/Hz, due to the high-gain, high-speed phase lock     

Optimization of metal-based multilayers for transparent heat mirrors

Multilayer calculations by conventional matrix methods for dielectricum/noble metal/dielectricum systems on glass have been performed. The aim has been to maximize the integrated parameters for solar transmission, T_sol, and transmission of visible light, T_eye We have found that Ag is superior for maximizing the transmittance over the narrow visible wavelength range owing to the low internal absorptance. When solar energy transmission is considered multilayers based on Au are the best choice for metal film thicknesses above 15 nm. For thinner films, Ag is still to be preferred.     

Excited state absorption of pump radiation as a loss mechanism insolid-state lasers

The characteristics of optical pumping dynamics in laser-pumped, rare-earth-doped, solid-state laser materials are investigated by using a tunable alexandrite laser to pump Y₃Al₅O₁₂ :Nd³⁺ in an optical cavity. It is found that the slope efficiency of the Nd laser operation depends strongly on the wavelength of the pump laser. For pump wavelengths resulting in low slope efficiencies, intense fluorescence emission is observed from the sample in the blue-green spectral region. This is attributed to the excited-state absorption of pump photons which occurs during radiationless relaxation from the pump band to the metastable state. This type of process is an important loss mechanism for monochromatic pumping of laser systems at specific pump wavelengths     

Purification and Properties of β-Glucuronidase from the Muscle of Bombay Duck (Harpodon Nehereus)

Bombay duck muscle β-glucuronidase purified 4200-fold had molecular weight of 160,000 as estimated by gel filtration on Sephadex G-200. The glycoprotein enzyme exhibited dimeric structure on SDS-PAGE and had a pI of 5.0. The enzyme was optimally active at pH 5.2 when phenolphthalein β-D-glucuronide was used as the substrate while with p-nitrophenyl glucuronide the pH optimum was 4.6. Saccharo-1,4-lactone was a potent competitive inhibitor of the enzyme. Heavy metalic ions such as Hg²⁺, Cd²⁺ and Ag⁺ also proved to be inhibitory to the enzyme. Radiation inactivation of the enzyme could be protected in the presence of mercaptoethanol. Sodium chloride activated the enzyme while sodium tripolyphosphate inhibited it.     

Gene Transfer Systems and Molecular Cloning in Group N Streptococci: A Review

Plasmid deoxyribonucleic acid of group N streptococci codes for a wide variety of important metabolic properties associated with dairy fermentations. The increasing knowledge of the genetics of these bacteria has created exciting possibilities for genetically constructing improved starter strains. A review of current literature is presented on the genetics of group N streptococci, especially the development and implications of gene transfer and molecular cloning systems for further genetic studies and for strain improvement. Functional properties of plasmid deoxyribonucleic acid and gene transfer systems, which include transduction, conjugation, transformation, and protoplast fusion, are reviewed and followed by a discussion of recent advances in gene cloning.