Far infrared properties of PLZT ceramics

Far infrared and mid infrared reflectivity measurements have been made of lead titanate zirconate (PLZT) ceramics at room temperature in the frequency range 40–1500 cm-1. Kramers-Krönig analysis and a fitting procedure based on a four parameter model of the spectrum, determined the infrared active transverse and longitudinal optical modes and their damping factors. Group theory analysis has been done and the number of experimentally observed infrared active modes was compared with the theoretical prediction. Three ionic oscillators for a cubic perovskite Pm3m structure should exist, but four ionic oscillators for the PLZT polycrystalline sample were observed. This excluded the possibility that the sample could have a cubic lattice and confirmed that the tetragonal structure was present at room temperature. X-ray analysis of the PLZT sample was performed and the results were compared with infrared spectroscopy work. It was concluded that infrared optical reflectivity measurements, as a non-destructive method, can give more reliable results at the boundary cases when it is very difficult to distinguish if a material has either a cubic or tetragonal lattice structure.     

Simple lattice model ford-type gap anisotropy for layered cuprates

Double electron exchange between Cu4s and O2p_σ orbitals is analyzed as mechanism which creates traditional cooper pairing in layered cuprates. The conductivity band is obtained in the oversimplified model which considers only hopping between O2p_σ orbitals, and the amplitude of the Cu4s-O2p_σ hybridization is accounted as perturbation. The proposed toy model possesses most of the distinguishable features of the experimental data: angle dependence of the superconducting gap, the shape of the Fermi surface, dispersion law for conductivity band and the electron spectrum of the superconducting phase. The influence of the Cu3d_x ²−y² orbital, electron doping and disorder for transition to s-type superconducting gap is briefly discussed.     

CMOS RLC and crystal oscillators based on current conveyors

Analysis and design of RLC and crystal oscillators based on current conveyors, in 1.5 μm CMOS integrated technology, are described. Maximal operating frequencies are 350 and 50 MHz, respectively     

Design Trade-offs in Customized On-chip Crossbar Schedulers

In this paper, we present a design and an analysis of customized crossbar schedulers for reconfigurable on-chip crossbar networks. In order to alleviate the scalability problem in a conventional crossbar network, we propose adaptive schedulers on customized crossbar ports. Specifically, we present a scheduler with a weighted round robin arbitration scheme that takes into account the bandwidth requirements of specific applications. In addition, we propose the sharing of schedulers among multiple ports in order to reduce the implementation cost. The proposed schedulers arbitrate on-demand (at design time) interconnects and adhere to the link bandwidth requirements, where physical topologies are identical to logical topologies for given applications. Considering conventional crossbar schedulers as reference designs, a comparative performance analysis is conducted. The hardware scheduler modules are parameterized. Experiments with practical applications show that our custom schedulers occupy up to 83% less area, and maintain better performance compared to the reference schedulers.     

Synthesis of novel 3‐hetaryl‐substituted 6‐ and 8‐hydroxybenzo[f]coumarin derivatives

Eight novel 3‐hetaryl‐substituted 6‐ and 8‐hydroxybenzo[f]iminocoumarin compounds were synthesised by the reaction of 2,5‐dihydroxynaphthaldehydes or 2,7‐dihydroxynaphthaldehydes with 2‐cyanomethylbenzo‐thiazole, 2‐cyanomethylbenzoimidazole, 1‐methyl‐2‐cyanomethylbenzoimidazole and 2‐cyanomethyl‐4‐phenylthiazole. The iminocompounds obtained were hydrolysed with hydrochloric acid to the benzo[f]coumarins. Becaue of the high reactivity of the iminocoumarins, only mixtures which also contained the corresponding coumarin compounds were isolated. The absorption and steady‐state fluorescence characteristics of the benzo[f]coumarins (benzo[f]chromen‐2‐ones) synthesised were studied in ethanol and in toluene.     

The design of a microcontroller temperature compensated crystaloscillator (μCTCXO) and automatic compensation line

A new concept in the design of the compensation circuit in microcontroller temperature compensated crystal oscillators (μCTCXO) and the corresponding production line (ACL-automatic compensation line) for fully automatic oscillator calibration are presented. The communications ability of μCTCXO is introduced to provide automatic calibration. The shortened successive approximation calibration algorithm gives a short calibration time and a reliable convergence of oscillator adjustment by the ACL system. The μCTCXO is realized as a low-cost device encapsulated in a single cubic inch volume. The ±0.5 ppm frequency accuracy in the -40°C/+85°C temperature range is obtained by a 9-bit A/D converter, 10-bit D/A and 512 bytes of software placed in an EEPROM. The ACL system, in addition to the standard laboratory frequency counter, temperature chamber and a PC host computer, requires only two additional boards: an analog multiplexer board and an interface board. During production and recalibration, the ACL system can compensate many oscillators simultaneously in a single temperature run, without requiring component selection and human supervision     

Aufklärung von Korrosionsprozessen bei der Erdölverarbeitung mittels Mössbauer- und Röntgenuntersuchung – II. Wasserkondensator und Separatoren

Study of the corrosion processes at the primary oil refining by Mössbauer and X-ray investigation – II. Water condensator und separators Samples from the tube bundle surface of a water condensator and from benzene-water separators in an operating installation for primary oil refining are investigated. The compositions of the samples and the types of corrosion on the technological route of the refined oil were established on the basis of Mössbauer spectroscopy and X-ray diffraction analysis.     

The combined use of cryosurgery and solcoseryl in treating malignant neoplasms

Antitumour efficacy of a combined use of cryosurgery and solcoseryl in mice with Lewis carcinoma was studied. Solcoseryl improves results of cryosurgery. An increase in antitumour effect with a combined use of cryodestruction and solcoseryl is supposed to be followed by the rise of oxygen tension in tissues. Solcoseryl injection followed by cryosurgery of cancer of mouth cavity mucosa in patients considerably accelerates the wound surface regeneration. Thus solcoseryl increases the treatment efficacy of the cryosurgical method.     

Probing the Structural Properties of DNA/RNA Grooves with Sterically Restricted Phosphonium Dyes: Screening of Dye Cytotoxicity and Uptake

To explore in greater detail the recently reported rare kinetic differentiation between homo‐polymeric and alternating AT‐DNA sequences by using sterically restricted phosphonium dyes that form dimers within the DNA minor groove, new analogues were prepared in which the quinolone phosphonium moiety was kept constant, while the size and hydrogen bonding properties of the rest of the molecule were varied. Structure–activity relationship studies revealed that a slight increase in length by an additional methylene unit results in loss of kinetic AT selectivity, but yielded an AT‐selective fluorescence response. These DNA/RNA‐groove‐bound dyes combine very low cytotoxicity with efficient cellular uptake and intriguingly specific fluorescent marking of mitochondria. In contrast to longer analogues, a decrease in length (by methylene unit removal) and rearrangement of positive charge resulted in dyes that had switched to the intercalative binding mode to GC DNA/dsRNA but that still form dimers in the minor groove of AT sequences, consequently yielding a significantly different chiro‐optical response. The latter dyes also revealed strongly selective antiproliferative activity toward HeLa cancer cells.