Numerical analysis of near-infrared wave propagationcharacteristics in dielectric-coated parallel planar microstructuralwaveguides

In this paper, the properties of electromagnetic (EM) wave propagation in layered planar microstructural waveguides are investigated. Analytical and numerical results are presented on the propagation of a 1-μm EM wave in a parallel planar waveguide. Its walls are made of Au or Si, coated with a thin layer of SiO₂ and separated by a fluid. The propagation characteristics of even and odd TE and TM modes are described as a function of the coating thickness. It is shown that the propagation of TE modes exhibits a sudden shift in power flow distribution from the fluid to the coating when the coating thickness exceeds a critical value. This property may be exploited for micromachined sensor applications. TM modes do not exhibit this behaviour     

Minimizing pattern count for interconnect test under a ground bounce constraint

When testing the interconnect structures on a board, test programmers sometimes ask, How can I control the test pattern generation process to avoid ground bounce problems during Extest mode? Those wishing to satisfy a simultaneously-switching-outputs constraint will find several new solutions in this article.     

Hydrogen atom abstraction of 3,5-disubstituted analogues of paracetamol by horseradish peroxidase and cytochrome P450

1. The formation of free radicals during enzyme catalysed oxidation of eight 3,5-disubstituted analogues of paracetamol (PAR) has been studied. A simple peroxidase system as well as cytochrome P450-containing systems were used. Radicals were detected by electron spin resonance (ESR) on incubation of PAR and 3,5-diCH3-, 3,5-diC2H5-, 3,5-ditC4H9-, 3,5-diOCH3-, 3,5-diSCH3-, 3,5-diF-, 3,5-diCl- and 3,5-diBr-substituted analogues of PAR with horseradish peroxidase in the presence of hydrogen peroxide (H2O2). Initial analysis of the observed ESR spectra revealed all radical species to be phenoxy radicals, based on the absence of dominant nitrogen hyperfine splittings. No radicals were detected in rat liver cytochrome P450-containing microsomal or reconstituted systems. 2. To rationalize the observed ESR spectra, hydrogen atom abstraction of PAR and four of the 3,5-disubstituted analogues (3,5-diCH3-, 3,5-diOCH3-, 3,5-diF- and 3,5-diCl-PAR) was calculated using ab initio calculations, and a singlet oxygen atom was used as the oxidizing species. The calculations indicated that for all compounds studied an initial hydrogen atom abstraction from the phenolic hydroxyl group is favoured by approximately 125 kJ/mol over an initial hydrogen atom abstraction from the acetylamino nitrogen atom, and that after hydrogen abstraction from the phenolic hydroxyl group, the unpaired electron remains predominantly localised at the phenoxy oxygen atom (+/-85%). 3. The experimental finding of phenoxy radicals in horseradish peroxidase/H2O2 incubations paralleled these theoretical findings. The failure to detect experimentally phenoxy radicals in cytochrome P450-catalysed oxidation of any of the eight 3,5-disubstituted PAR analogues is more likely due to the reducing effects that agents like NADPH and protein thiol groups have on phenoxy radicals rather than on the physical instability of the respective substrate radicals.     

A refined substrate model for human cytochrome P450 2D6

Human epidermal keratinocytes possess cholinergic enzymes, which synthesize and degrade acetylcholine, and express both nicotinic and muscarinic classes of cholinergic receptors on their cell surfaces. These receptors bind acetylcholine and initiate cellular response. The presence in keratinocytes of a functional cholinergic system suggests a role for acetylcholine in most, if not all, aspects of keratinocyte function. Autocrine and paracrine acetylcholine are required to sustain the viability of keratinocytes in vitro, and cholinergic drugs can alter keratinocyte proliferation, adhesion, migration, and differentiation. Acetylcholine employs calcium as a mediator for its effects on keratinocytes. In turn, changes in calcium concentration may affect expression and function of keratinocyte cholinergic enzymes and cholinergic receptors. At different stages of their differentiation, keratinocytes may demonstrate unique combinations of cholinergic enzymes and cholinergic receptor types. This would allow basal, prickle, and granular keratinocytes to respond to acetylcholine differently, in accordance with their functions at each stage of keratinocyte development in epidermis.     

Effect of Oral Taurine on Morbidity and Mortality in Elderly Hip Fracture Patients: A Randomized Trial

Hip fracture patients represent a large part of the elderly surgical population and face severe postoperative morbidity and excessive mortality compared to adult surgical hip fracture patients. Low antioxidant status and taurine deficiency is common in the elderly, and may negatively affect postoperative outcome. We hypothesized that taurine, an antioxidant, could improve clinical outcome in the elderly hip fracture patient. A double blind randomized, placebo controlled, clinical trial was conducted on elderly hip fracture patients. Supplementation started after admission and before surgery up to the sixth postoperative day. Markers of oxidative status were measured during hospitalization, and postoperative outcome was monitored for one year after surgery. Taurine supplementation did not improve in-hospital morbidity, medical comorbidities during the first year, or mortality during the first year. Taurine supplementation lowered postoperative oxidative stress, as shown by lower urinary 8-hydroxy-2-deoxyguanosine levels (Generalized estimating equations (GEE) analysis average difference over time; regression coefficient (Beta): −0.54; 95% CI: −1.08–−0.01; p = 0.04), blunted plasma malondialdehyde response (Beta: 1.58; 95% CI: 0.00–3.15; p = 0.05) and a trend towards lower lactate to pyruvate ratio (Beta: −1.10; 95% CI: −2.33–0.12; p = 0.08). We concluded that peri-operative taurine supplementation attenuated postoperative oxidative stress in elderly hip fracture patients, but did not improve postoperative morbidity and mortality.     

Thermodynamics and kinetics of the thin film magnesium–hydrogen system

The absorption and desorption isotherms of Mg thin films are determined by electrochemical techniques at room temperature. Up to now, especially for hydrogen desorption from pure Mg, the temperature range for determining the isotherm has been confined to high temperatures. The enthalpy of hydride formation and hydride decomposition is in agreement with the data reported previously; however, the present data are measured directly at room temperature. The dynamic electrochemical responses during hydrogen extraction reveal that at the beginning of the dehydrogenation reaction the rate is mostly impeded by a nucleation and growth mechanism. The desorption isotherm is simulated with a lattice gas model and excellent agreement between experiment and theory is found. The parameters are used to obtain detailed information about the magnesium–hydrogen system.     

Scanning our past [Popov lightning recorder]

The Historical Interest Group of the South African Institute of Electrical Engineers (SAIEE) has been collecting historical artifacts and documents over the past 20 years for a future museum of Science and Technology. Recently, a rediscovery of a rare, almost century-old instrument based on the work of the Russian wireless innovator Aleksandr Stepanovich Popov has shed new light on the early days of electromagnetic receivers. The SAIEE discovered that they had a coherer wireless receiver in their collection. The SAIEE took the examination a step further and finally realized that this must be the lightning recorder used at the Transvaal Meteorological Station from 1904     

Power-efficient flexible processor architecture for embedded applications

In the design of embedded systems, a processor architecture is a tradeoff between energy consumption, area, speed, design time, and flexibility to cope with future design changes. New versions in a product generation may require small design changes in any part of the design. We propose a novel processor architecture concept, which provides the flexibility needed in practice at a reduced power and performance cost compared to a fully programmable processor. The crucial element is a novel protocol combining an efficient, customized component with a flexible processor into a hybrid architecture.