Controllability on classical Lie groups

We consider the problem of accessibility and controllability of certain bilinear systems. These evolve on Lie groups whose Lie algebras are the normal real forms of complex simple Lie algebras. Previous results by other authors were obtained under the assumption that the controlled vector field is strongly regular. Our paper is aimed at weakening this requirement, and involves relating the root structure of elements in a Lie algebra as above to the nodal connection graphs obtained from their standard matrix representations. This is in turn related to a standard irreducibility assumption on the uncontrolled vector field. The abstract results on generation of Lie algebras are of some independent interest. The work of this author was supported in part by a Fulbright grant, while she was visiting the Arizona State University, and by the Centro de Matemática da Universidade de Coimbra/INIC. The work of this author was partially supported by AFOSR Contract No. 85-0224A.     

New synthetic routes for quantum dots

Various methods for the synthesis of quantum dots of compound semiconductors are discussed. Emphasis is placed on methods involving the decomposition of chalcogenide-containing precursors in tri-n-octylphosphine oxide. The use of simple coordination complexes can avoid the use of pyrophoric precursors. Approaches based on melts or the use of imino-bisdichalcogeno-diphosphinates are also discussed. These routes may be suitable for the production of large quantities of quantum dots.     

Metal-organic chemical vapor deposition of β-In2S3 thin films using a single-source approach

Dithioimidobisdiisopropylphosphinato indium chloride In[(SPⁱPr₂)₂N]₂Cl has been shown to be an effective single-source precursor for the deposition of indium sulfide films by aerosol-assisted chemical vapor deposition (AACVD). X-ray powder diffraction (XRPD) studies indicated that polycrystalline -In₂S₃ films with the tetragonal phase have been deposited on glass substrates (425–475 °C). The morphology of films was confirmed by scanning electron microscopy (SEM). Energy dispersive X-ray analysis (EDAX) indicates the presence of indium and sulfur.     

Diamond-like carbon,a barrier coating for polymers used in packaging applications

Water and oxygen permeability measurements on two polymers, poly(ethylene terephthalate) and polypropylene, are presented as a function of diamond-like carbon coating thickness. Results show that reliable and reproducible coatings can be achieved on poly(ethylene terephthalate) such that levels of permeability are about 1 cc/m²/day for oxygen and 1.5 g/m²/day for water vapour, comparable to the levels for silicon oxides and aluminium coatings used in the packaging industry. The advantages conferred by diamond-like carbon over aluminium is primarily that of retaining optical transparency in the thickness of films used in this work (20 nm). The advantages of diamond-like carbon over silicon oxides is related to its intrinsic flexibility. Other advantages over other barrier films (e.g. polyvinylidine chloride) and coating technologies is the ability to recycle the used product. The permeability of diamond-like carbon-coated polypropylene to oxygen is in the range of 200 cc/m²/day, again comparable to results obtained with the other coatings. The optimum film thickness for poly(ethylene terephthalate) to minimize permeability was 20 nm. Atomic force microscopy revealed agglomerated structures (possibly graphitic) with the underlying substrate appearing smoother than the starting material. In comparison, polypropylene exhibited increased surface roughness under the same coating conditions.     

A Galerkin boundary integral method for multiple circular elastic inclusions

The problem of an infinite, isotropic elastic plane containing an arbitrary number of circular elastic inclusions is considered. The analysis procedure is based on the use of a complex singular integral equation. The unknown tractions at each circular boundary are approximated by a truncated complex Fourier series. A system of linear algebraic equations is obtained by using the classical Galerkin method and the Gauss–Seidel algorithm is used to solve the system. Several numerical examples are considered to demonstrate the effectiveness of the approach. Copyright © 2001 John Wiley & Sons, Ltd.     

Physico-chemical and electrochemical characterization of Ti/RhOx–IrO2 electrodes using sol–gel technology

Sol–gel technology has been successfully used for the incorporation of RhO_x–IrO₂ on a Ti substrate. RhO_x–IrO₂ was prepared from chloride precursors of Rh and Ir, for surface studies. These metal oxides were then immobilised on solid Ti substrates via dip withdrawal coating methods to form thin films. The Ti/RhO_x–IrO₂ thin films were extensively characterized in terms of surface characterization and chemical composition and used in the oxidation of phenol. Thermo-gravimetric analysis (TGA) determined the calcination temperature at 700 °C where no further structural changes occurred due to mass loss. The rhodium oxide showed two-phase formations, RhO₂ and Rh₂O₃, which were attributed to high calcinated temperatures compare to one phase IrO₂ which was stable at lower temperatures. The scanning electron microscopy (SEM) showed that the morphology of the film was found to be rough with a grain-like appearance in the 150-nm range. The phase composition of these metal oxides was determined by X-ray diffraction (XRD) technique and found to have crystalline structures. The results obtained from Rutherford backscattering spectrometry (RBS) revealed information regarding the chemical composition of the metal oxides and confirmed the diffusion of Rh and Ir into the Ti substrate. Electrochemical characterization of the Ti/RhO_x–IrO₂ electrode, via cyclic voltammetry (CV), showed distinctive redox peaks: anodic and cathodic peaks associated with the oxidation and reduction of the ferricyanide–ferrocyanide couple was seen at 250 and 100 mV respectively; the peak observed at 1000 mV was associated with oxygen evolution and a broad reductive wave at −600 mV can be ascribed to the Ti/RuO_x–IrO₂ reduction, which proved that the Ti/RhO_x–IrO₂ electrode were electroactive and exhibit fast electrochemistry.     

Warfarin resistance in a patient with short bowel syndrome

Drug therapy in short bowel syndrome can be complicated by inadequate or incomplete absorption of drugs in the small intestine. Many case reports claim that warfarin absorption is not affected by the syndrome. We treated a patient with oral warfarin for recurring deep vein thrombosis; up to 20 mg/day was administered with no increase in the international normalized ratio. Drug-drug interactions that may prevent absorption, increase metabolism, or antagonize the effects of warfarin were ruled out. Intravenous lipid administration, which is anecdotally reported to precipitate warfarin resistance, may have contributed to the condition, but dosing was less frequent than in published reports. The most probable explanation of warfarin resistance is the reduced surface area for drug absorption secondary to surgical removal of the patient's duodenum and gastrojejunostomy.     

Laboratory validation study of drug evaluation and classification program: alprazolam, d-amphetamine, codeine, and marijuana

The Drug Evaluation and Classification (DEC) program is used by police agencies to identify drivers impaired because of drug use and to determine the class(es) of drug causing the impairment. The primary goal of this study was to determine the validity of the DEC evaluation in predicting whether research volunteers were administered alprazolam, d-amphetamine, codeine, or marijuana. A secondary goal was to determine the accuracy of Drug Recognition Examiners (DREs) in detecting if subjects were dosed with these drugs. Community volunteers (n = 48) were administered alprazolam (0, 1, 2 mg), d-amphetamine (0, 12.5, 25 mg), codeine (0, 60, 120 mg), or marijuana (0, 3.58% THC) in a double-blind, randomized, between-subject design. A single drug dose or placebo was administered at each experimental session, and blood samples were obtained before and after dosing. With the exception of marijuana, plasma drug concentration was at or near maximum during the DEC evaluation. The ability of the DEC evaluation to predict the intake of alprazolam, d-amphetamine, codeine, or marijuana was optimal when using 2-7 variables from the evaluation. DREs' decisions of impairment were consistent with the administration of any active drug in 76% of cases, and their drug class decisions were consistent with toxicology in 32% of cases, according to standards of the International Association of Chiefs of Police. These findings suggest that the DEC evaluation can be used to predict accurately acute administration of alprazolam, d-amphetamine, codeine, and marijuana and that predictions of drug use may be improved by focusing on a subset of variables.     

Caucasian versus African-American differences in orosomucoid: potential implications for therapy

We conducted a prospective, nonrandomized study in healthy volunteers to determine if racial differences exist in orosomucoid (ORM) and its variants, and to examine quinidine and lidocaine binding to the protein. Total ORM serum concentrations were measured by Laurell-Rocket immunoelectrophoresis. Allele types were determined by isoelectric focusing and immunoblotting. Total and unbound quinidine and lidocaine concentrations were measured with standard fluorescence polarization immunoassays after ultrafiltration. The frequency of the common ORM alleles was similar between 38 Caucasians and 67 African-Americans. Mean total ORM concentration was significantly lower in Caucasians (57.3 +/- 25.4 vs 73.2 +/- 33.9 mg/dl, p=0.01). However, more Caucasians took oral contraceptives, which may have decreased ORM concentrations. Quinidine unbound fraction (UF) was related to ORM phenotype. The highest UF was found with ORM 1-S (p=0.009). There were no significant relationships between ORM phenotype and lidocaine UF. Overall, African-Americans had higher ORM concentrations than Caucasians. Quinidine binding showed significant relationships to specific ORM variants.     

Effects of r-metHuG-CSF on polymorphonuclear leucocyte kinetics and function in patients on continuous ambulatory peritoneal dialysis

End-stage renal failure (ESRF) patients undergoing continuous ambulatory peritoneal dialysis (CAPD) are immunocompromised and exhibit abnormal circulating polymorphonuclear leucocyte (PMN) function, including reduced phagocytosis and intracellular killing. Six uraemic patients on CAPD were each given 300 microg granulocyte colony stimulating factor (G-CSF) every day for 5 d and PMN function tests were performed daily. By day 5 of the study CD11b expression was significantly decreased in response to N-formylmethionylleucylphenylalanine (fMLP) and opsonized Staphylococcus epidermidis stimulation, and expression of L-selectin (CD62L) was significantly decreased in response to opsonized Staphylococcus epidermidis stimulation. Further, superoxide anion production and Fc gammaRI (CD64) expression were found to be significantly increased and Fc gammaRII (CD16) expression was lowered. Circulating white cell and PMN counts were significantly elevated in response to treatment. Administration of G-CSF did not appear to have corrected the abnormalities in phagocytosis and intracellular killing. This study suggests that G-CSF does no harm to ESRF patients and influences uraemic PMN function in a manner that is comparable to its effects on PMN in non-uraemic subjects.