bluuebunny/crossref_metadata_2025 huggingface dataset:
Coupling Between the Discharge Plasma Instability and the Laser Oscillation in a He—Cd Laser
Authors: Cristescu C. P. , Popescu I. M. , Preda A. M. , Podoleanu A.
Published: July 2007

The investigation of the output of a He–Cd laser with electrically floating hollow electrodes shows that the discharge plasma instability plays an important role in the generation of the population inversion. The experimental evidence is presented and a qualitative interpretation is given by considering the plasma instability as equivalent to a radio frequency component of the discharge voltage.
Methods for the Numerical Calculation of the Plasma Potential from Measured Langmuir Probe Characteristics
Authors: Seifert W. , Johanning D. , Lehmann H.‐R. , Bankov N.
Published: July 2007

In a previous paper the results of the Langmuir probe experiment carried out on board of two INTERKOSMOS satellites have been described. The experiences have shown that the usage of high quality algorithms for analyzing the current‐voltage‐characteristics is necessary to yield real physical parameters.

The key problem is the determination of the plasma potential. This paper reviews the different methods to determine the plasma potential especially under the circumstances of computer application. The test of the well developed methods shows, that for the evaluation of the applied methods a number of different factors, discussed in the following sections of this paper, has to be taken into account. The used test data are model values or real measurements obtained by the satellite missions IK‐10, IK‐18 and BULGARIA‐1300.

The computer procedures have been realized as FORTRAN‐subroutines for the BESM 6 and ES 1040.
Desaktivierung angeregter He‐Atome (31P1, 31S0, 41S0, 51S0, 61S0) durch Rb‐Atome
Authors: Kasjanenko S. W. , Talmatschov J. A. , Krause U.
Published: July 2007

Total collisional depopulation rates for He(n1S0) (3 ≦ n ≦ 6), He(31P1) in thermal collisions with Rb have been measured using the transient‐decay method. The measured quenching cross‐sections increase from 4.3 · 10−10 cm2 to 24 · 10−14 cm2 with increasing n from 3 to 6.

Comparison of experimental results with theoretical estimations shows that the main processes of quenching depend on n. He‐atoms in the n = 3, 4 states are mainly quenched by Penning ionisation and higher excited states by collisional l‐mixing.
The Electrical Conductivity of Break Arcs: A Diffusion Dominated Phenomenon
Authors: Vogel N. , Cebulla H.
Published: July 2007

The current‐conducting channel near the cathode of metal vapour ares is described theoretically by a diffusion model. Time resolved measurements of voltage and current during opening of electric contacts are used to determine channel radius and plasma conductivity. Channel radii of the order of 1–10 μm are deduced, leading to conductivities of the metal vapour plasma of the order of 105 Ω−1 cm−1. This is considerably higher than the classical conductivity according to Spitzer.
On the Transversal Diffusion of Electrons in a Gas in an Electric Field
Authors: Braglia G. L. , Diligenti M.
Published: July 2007

Discrepancies between Monte Carlo and Boltzmann calculations of electron drift and diffusion in gases have recently led some authors to call into question the same definition of diffusion coefficient perpendicular to the electric field. In this paper we report new results which confirm the observed discrepancies but at the same time we will show that the Monte Carlo results are consistent with more rigorous calculations based on theories of higher order than the first.
Zur Eindeutigkeit eines neuen Differenzmeßverfahrens für die sehr genaue Bestimmung der Resonatorgüte und der Resonanzfrequenz von Mikrowellenresonatoren
Authors: Gundermann S.
Published: July 2007

It is possible to improve the resolving power at the determination of the resonance frequency and the cavity Q by the timed modulation af a plasma loading the resonator. By this we get a higher exactness for the determination of the plasma parameters. The resonance curves obtained by aid of the differences of the output signals of the resonator result from the solutions of a nonlinear system of equations. The existence and uniqueness of the solutions are discussed in some special cases.
A Study of Small Amplitude Ion Acoustic Double Layers in a Multi‐Species Unmagnetized Plasma
Authors: Sharma N. K. , Goswami K. S. , Bujarbarua S.
Published: July 2007

We report here analytic solutions for weak ion acoustic double layers in an unmagnetized multi‐species plasma having two electron components, each described by a Boltzmann distribution, and two ions of different masses, each described by usual fluid equations. The velocity and the width of the double layers for different amplitude has been studied.
Self‐Interaction of Electron Plasma Waves in a Planar Plasma‐Filled Waveguide
Authors: Ghosh B. , Das K. P.
Published: July 2007

Nonlinear behaviour of electron plasma waves propagating in a planar plasma‐loaded waveguide immersed in an infinite magnetic field is analysed including finite temperature and mobile ion effects. It is shown that the wave becomes modulationally unstable if the wavenumber exceeds certain critical value Kc, which decreases with rise of temperature. The growth rate of instability is calculated and is found to increase with the rise of temperature.
Nonlinear Theory of the Plasma Wave Excitation in a Bounded Beam‐Plasma System
Authors: Kruscha K. J. G.
Published: July 2007

The excitation of symmetric and antisymmetric plasma waves by a beam layer that moves within a homogeneous plasma enclosed by a metallic wall was dealt with theoretically. Investigations were carried out for the magnetic field free case and for a magnetized electron beam. In the latter case, the beam electrons are assumed to be unable to move in the perpendicular direction. The theoretical model bases upon an extension of the well known single wave theory to a two‐dimensional beam‐plasma system. Special emphasis should be paid to the fact that the perpendicular wave profile of the excited waves was determined self‐consistently. Energy and momentum balance equations are derived for this system. The theoretical method outlined in this paper which is based on a Green's‐function technique can be extended easily to three‐dimensional systems or to beam‐plasma systems with other boundary conditions. The main features of the saturation process of the basic unstable wave types are discussed. Several interesting effects were found in the magnetic field free case: (i) numerical solutions describe an increasing steepening of the wave amplitudes in perpendicular direction near the center of the system for the symmetric potential wave; (ii) for the antisymmetric wave, a smoothing tendency was found in the development of the perpendicular wave potential profile; (iii) spatial separation of the slow and fast beam electrons was observed; (iv) it is shown for the antisymmetric potential wave type that, under certain conditions, a very efficient beam particle retardation mechanism occurs which is connected with a strong reduction of the formation of a fast particle group; (v) generally it was shown that the conversion of the kinetic energy of the beam electrons into the plasma wave energy may be more effective as compared with the case of the magnetized beam.
Comments on Surface Plasma Wave Solitons
Authors: Stenflo L. , Zhelyazkov I. , Yu M. Y.
Published: July 2007

We discuss surface waves propagating on a semi‐infinite cold plasma with slowly varying density. Previous results are modified.
Excitation of Convective Cells by Nonlinear Interaction of Interchange Mode
Authors: Majumdar D.
Published: July 2007

Convective Cell formation due to nonlinear interaction of interchange mode is studied using multiple time and space scales. Basic interchange mode equation is modified to obtain nonlinear localized structure with modulational perturbation in the drift direction and periodic boundary condition for the perturbation in the direction of the density gradient. To study modulational instability we have deduced nonlinear evolution equation for the first order perturbation from third order secularity elimination condition. Modulational instability, which is responsible for localized structure, is studied in two limits of the dispersion relation.
Stability of a Stratified Layer of a Gravitating Partially Ionized Plasma
Authors: Bhatia P. K. , Sankhla V. D.
Published: July 2007

The instability in a stratified layer of a self‐gravitating partially ionized plasma has been studied in the presence of effects of Hall currents. For a plasma permeated by a uniform vertical magnetic field, the dispersion relation has been obtained through variational method. It is found that the Hall currents have a destabilizing effect while the neutral gas frictional effects have a stabilizing influence.
Central Structure of Dβ Line in Low Pressure T‐Tube Deuterium Plasmas
Authors: Pavlov M. , Mijatović Z.
Published: July 2007

The perturbing ion motion effect on the relative central dip of the Hβ (Dβ) has been firmly established for numerous values of the reduced mass of the radiating atom – perturbing ion. In this paper the ion motion effect is confirmed for the cases in which the reduced mass and electron densities are constant, while the temperature of plasma is changing. Also a dependence of the dip values on electron density Ne is checked following theoretical results of Demura, Lisitza and Sholin. It is shown that the dip value is a linear function of N, where α is a number close to 1.
Electron Attachment and Detachment Processes in Electronegative Gases
Authors: Christophorou L. G.
Published: July 2007

Selected results of recent studies on electron attachment (especially to excited molecules) and detachment processes in electronegative gases are presented and discussed and their relevance to modern technologies is indicated.
The Arc Cathode Regime: An Approach from Basic Laws
Authors: Hantzsche E.
Published: July 2007

The question is examined whether or not the existence of a cathode mechanism with high power density may be predicted from general physical laws, as well as the order of magnitude of the main cathode parameters of such a discharge. The answer is yes, though – because of many feedbacks and simplifications – the numerical values calculated in this way are not more than crude estimations.

Essentially two conditions have to be fulfilled: The first is the dominance of collective electron emission processes, the second is the dominance of Joule heating combined with the limit of stationarity. Both conditions result in similar values of the cathode parameters.

In this low‐current region (about 10…100 A) the existence of a high‐current density cathode mechanism (order of magnitude: 108 A/cm2) is proved, with consequences for all the other parameters, in rough agreement with the results of measurements in arc cathode spots. Thus the typical arc spot regime may be founded theoretically by these argumentations.
General Formulation for the Ponderomotive Force in a Warm Two Fluid Magnetized Plasma
Authors: Tyagi S. S. , Srivastava M. P.
Published: July 2007

A general expression for the ponderomotive force in a warm, inhomogeneous, nonstationary, magnetized and collisionless two fluid plasma in the presence of electromagnetic field is obtained. We start with two fluid equations viz. continuity, momentum equations and Maxwell's equation. Expanding the physical quantities in terms of a high frequency part and a slowly varying part and averaging the quantities over one period of the high frequency, we have obtained the expression for the ponderomotive force. The results are compared with the results of earlier workers under different approximations.
Ternary Complexes of Zinc(II), Cyclen and Pyridinecarboxylic Acids
Authors: Vargová Zuzana , Kotek Jan , Rudovský Jakub , Plutnar Jan , Gyepes Robert , Hermann Petr , Györyová Katarina , Lukeš Ivan
Published: July 2007

Binary and ternary systems containing Zn2+, cyclen and/or pyridinecarboxylic acids and amides [picolinic (HL1), nicotinic (HL2) and dipicolinic (H2L3) acids and nicotinamide (L4)] have been investigated in solution and in the solid state. Dissociation and stability constants for the ligands and binary systems, respectively, are in accordance with literature results. Both picolinic and dipicolinic acids form stable ternary complexes with the [Zn(cyclen)]2+species; a weak interaction is observed for nicotinic acid and nicotinamide. The formation of ternary complexes stabilizes the products of protonation at the cyclen nitrogen atom, and these protonated complexes are found even up to pH = 7. The structures of the complexes in solution correlate well with those found in the solid state and by molecular modelling calculations. The solid‐state structures of several complexes are determined. The zinc atom in the [Zn(cyclen)(NO3)]+complex is bound in an N4O tetragonal‐pyramidal environment. The nicotinic acid anion forms a bridge in the [{Zn(cyclen)}2(μ‐L2‐N,O)]3+cation, and both [Zn(cyclen)]2+units exhibit tetragonal‐pyramidal arrangements. An unusual coordination mode is found in the [{Zn(cyclen)}2(μ‐L1‐O:N,O′)]3+cation, where the picolinic acid anion also bridges two [Zn(cyclen)]2+units but is coordinated monodentately through one oxygen atom to one unit (N4O tetragonal pyramid) and chelates through the other pyridine nitrogen and carboxylate oxygen atoms. Nicotinamide in the [Zn(cyclen)(L4‐N)]2+cation is bound to the [Zn(cyclen)]2+unit through the pyridine nitrogen atom in the axial position of the tetragonal pyramid. This is the first fully quantitative assessment of Zn2+‐cyclen‐ligand ternary systems, and the results, namely the presence of protonated cyclen in the ternary species even at high pH, are relevant for evaluation of the [Zn(cyclen)]2+unit as a model complex for zinc‐containing enzymes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Silicon–Phosphorus and Silicon–Arsenic Cage Compounds with Bicyclo[2.2.1]heptane, Bicyclo[3.2.1]octane and Tricyclo[3.3.3.1.03,7]nonane Backbones
Authors: Tekautz Günter , Baumgartner Judith , Dransfeld Alk , Hassler Karl
Published: July 2007

The reaction of tris(chlorodimethylsilyl)methylsilane (1) and 1,1,2,2‐tetrakis(chlorodimethylsilyl)‐1,2‐dimethyldisilane (2) with sodium/potassium arsenide Na3As/K3As afforded decamethyl‐2,3,5,6,7‐pentasila‐1,4‐diarsabicyclo[2.2.1]heptane (3)and dodecamethyl‐2,3,4,6,7,8,9‐heptasila‐1,5‐diarsatricyclo[3.3.1.03,7]nonane (4). Compounds 3 and 4 were isolated from the reaction mixture by fractional crystallization and structurally characterized by single‐crystal X‐ray crystallography. The reaction of 1 with an excess amount of sodium/potassium phosphide (Na3P/K3P) afforded the cage‐shaped anionsodium hexamethyl‐2,4,6,7‐tetrasila‐1‐phosphanido‐3,5‐diphosphabicyclo[3.2.1]octane (5), which reacts with chlorotrimethylsilane to form trimethylsilyl‐substituted derivative 6. The molecular structures of 5 and 6 were established by X‐ray crystallography. Cages 3–6 were also characterized by 29Si‐ and 31P NMR spectroscopy. Owing to indirect spin–spin coupling between the 29Si and 31P nuclei, the resonances of the 29Si nuclei in the spectra of 5 and 6 are only of first order approximately. To account for the observed preferences of the cage structures in these reactions, extensive B3LYP/6‐31G* quantum chemical calculations of relative energies of bicyclo[2.2.2] and bicyclo[3.2.1] isomers of Si8H14, PSi7H13, P2Si6H12 and P3Si5H11 were conducted. On the basis of the computed charge distributions, the concept of topological charge stabilization was used to predict the relative stabilities. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Activated Aryl Chlorides: Useful Partners for the Coupling with 2‐Substituted Thiazoles in the Palladium‐Catalysed C‐H Activation/Functionalisation Reaction
Authors: Gottumukkala Aditya L. , Doucet Henri
Published: July 2007

Aryl chlorides are noticeably uncommon partners in coupling reactions with heteroaromatics through C‐H activation. We report herein that as little as 1 mol‐% of the air‐stable PdCl(dppb)(C3H5) complex catalyses the direct coupling of electron‐deficient aryl chlorides with 2‐substituted thiazole derivatives. A range of functionalities on the aryl chloride such as acetyl, formyl, ester, nitro, nitrile or trifluoromethyl is tolerated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Shearing‐Like Distortion in Binuclear End‐to‐End CuII Azido Compounds: An Ab Initio Study of the Magnetic Interactions
Authors: Angels Carvajal Maria , Aronica Christophe , Luneau Dominique , Robert Vincent
Published: July 2007

The direct control of magnetic interactions in CuII azido‐bridged binuclear complexes is investigated by means of explicitly correlated ab initio calculations. It is shown that in the end‐to‐end series, the shearing‐like asymmetry parameter δ = dlong(Cu–N) – dshort(Cu–N) should be considered as an important parameter in the control of the coupling constant. A practical route that could be used to enhance the ferromagnetism of the compound is suggested in light of our calculations.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Oxidation of Inorganic Sulfur Compounds in Acidophilic Prokaryotes
Authors: Rohwerder T. , Sand W.
Published: July 2007

The oxidation of reduced inorganic sulfur compounds to sulfuric acid is of great importance for biohydrometallurgical technologies as well as the formation of acidic (below pH 3) and often heavy metal‐contaminated environments. The use of elemental sulfur as an electron donor is the predominant energy‐yielding process in acidic natural sulfur‐rich biotopes but also at mining sites containing sulfidic ores. Contrary to its significant role in the global sulfur cycle and its biotechnological importance, the microbial fundamentals of acidophilic sulfur oxidation are only incompletely understood. Besides giving an overview of sulfur‐oxidizing acidophiles, this review describes the so far known enzymatic reactions related to elemental sulfur oxidation in acidophilic bacteria and archaea. Although generally similar reactions are employed in both prokaryotic groups, the stoichiometry of the key enzymes is different. Bacteria oxidize elemental sulfur by a sulfur dioxygenase to sulfite whereas in archaea, a sulfur oxygenase reductase is used forming equal amounts of sulfide and sulfite. In both cases, the activation mechanism of elemental sulfur is not known but highly reactive linear sulfur forms are assumed to be the actual substrate. Inhibition as well as promotion of these biochemical steps is highly relevant in bioleaching operations. An efficient oxidation can prevent the formation of passivating sulfur layers. In other cases, a specific inhibition of sulfur biooxidation may be beneficial for reducing cooling and neutralization costs. In conclusion, the demand for a better knowledge of the biochemistry of sulfur‐oxidizing acidophiles is underlined.
Heterogeneity of gene expression profiles in head and neck cancer
Authors: Pramana Jimmy , Pimentel Nuno , Hofland Ingrid , Wessels Lodewijk F. A. , van Velthuysen Marie‐Louise F. , Atsma Douwe , Rasch Coen R. N. , van den Brekel Michiel W. M. , Begg Adrian C.
Published: July 2007

Background.

Results of gene expression profiling studies from different institutes often lack consistency. This could be due to the use of different microarray platforms and protocols, or to intratumoral heterogeneity in mRNA expression. The aim of our study was to quantify intratumoral heterogeneity in head and neck cancer.

Methods.

Forty‐four fresh frozen biopsies were taken from 22 patients, 2 per tumor. RNA was extracted, tested for quality, amplified, labeled, and hybridized to a 35k oligoarray.

Results.

Unsupervised clustering analyses using all genes, the most variable genes, or random gene sets showed that 80% to 90% of biopsy pairs clustered together. A within‐pair‐between‐pair scatter ratio analysis showed that the similarity between matching pairs was significantly greater than that between random pairs (p <.00001).

Conclusions.

Two biopsies from the same tumor show far greater similarity in gene expression than biopsies from different tumors, supporting the use of 1 biopsy for expression profiling. © 2007 Wiley Periodicals, Inc. Head Neck 2007
Integration of the sensory inputs to place cells: What, where, why, and how?
Authors: Jeffery Kathryn J.
Published: July 2007

The hippocampal place cells are a highly multimodal class of neurons, receiving information from many different sensory sources to correctly localize their firing to restricted regions of an environment. Evidence suggests that the sensory information is processed upstream of the hippocampus, to extract both angular and linear metric information, and also contextual information. These various kinds of information need to be integrated for coherent firing fields to be generated, and the present article reviews recent evidence concerning how this occurs. It is concluded that there is a functional dissociation of the cortical inputs, with one class of incoming information comprising purely metric information concerning distance and orientation, probably routed via the grid cells and head direction cells. The other class of information is much more heterogeneous and serves, at least in part, to contextualize the spatial inputs so as to provide a unique representation of the place the animal is in. Evidence from remapping studies suggests that the metric and contextual inputs interact upstream of the place cells, perhaps in entorhinal cortex. A full understanding of the generation of the hippocampal place representation will require elucidation of the representational functions of the afferent cortical areas. © 2007 Wiley‐Liss, Inc.
Regional variability, processing methods, and biophysical properties of human fascia lata extracellular matrix
Authors: Derwin Kathleen A. , Baker Andrew R. , Spragg Rebecca K. , Leigh Diane R. , Farhat Walid , Iannotti Joseph P.
Published: July 2007

This study aims to assess the regional variability, processing methods, mechanical, biochemical, and cellular properties of human fascia lata as a scaffold for soft tissue repair and tissue engineering applications. Ten pairs of fascia lata (donor age 18–55) were used. One fascia patch from each pair was used to assess the geometric and biomechanical variability of fresh fascia. The other from each pair was subjected to 1 of 2 allograft processing methods: antibiotic soak alone or acellularization plus antibiotic soak. Stiffness, modulus, hydroxyproline, chondroitin/dermatan sulfate glycosaminoglycan (CSDS GAG), and DNA content were quantified in fascia from fresh and treated groups. The effect of location was not significant for thickness or stiffness within a 6 × 12 cm2 region of the iliotibial tract of fresh human fascia lata. Processing did not significantly change the stiffness, modulus, or CSDS GAG content of fascia ECM. However, hydroxyproline (collagen) content is significantly reduced in acellularized fascia, probably reflecting a removal of soluble collagen during the treatment (p < 0.02). Processing reduced the DNA content of fresh fascia approximately 10‐fold (p < 0.001). The mechanical, chemical and ultrastructural similarities between fascia lata and tendon may make fresh or processed fascia an attractive ECM scaffold for soft tissue, particularly tendon, repair. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Three‐dimensional nanocomposite scaffolds with ordered cylindrical orthogonal pores
Authors: Rodríguez Hernández José Carlos , Serrano Aroca Ángel , Gómez Ribelles José Luis , Pradas Manuel Monleón
Published: July 2007

A silica reinforcement can improve the mechanical properties of hydrogels in the rubbery state. A method to prepare a scaffold with a well‐ordered array of cylindrical pores is presented in this work, which yields a scaffold with a biphasic matrix of a hybrid nanocomposite: the hydrogel poly(2‐hydroxyethyl acrylate) (PHEA) and a silica network obtained by an acid catalyzed sol–gel process of tetraethoxysilane (TEOS). As porogenic template of the scaffold stacked layers of commercial polyamide 6 fabrics were used, which were compressed and sintered. Porosity and dynamic mechanical response of the resulting scaffolds were measured and compared with the bulk properties. Removal of the organic polymer phase of the scaffold by pyrolysis revealed the overall continuity of the silica network; the residue maintained the original cylindrical pore structure of the scaffolds, though slightly shrunk. Atomic force microscopy topography measurements of these pyrolysed residues revealed a silica structure with particle aggregates having sizes around tens of nanometers. The silica distribution was assessed by X‐ray microanalysis mapping, showing homogeneity at a micrometer scale. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Identification of osteopontin phosphorylation sites involved in bone remodeling and inhibition of pathological calcification
Authors: Saad Fawzy A. , Salih Erdjan , Glimcher Melvin J.
Published: July 2007

Osteopontin is a noncollagenous, phosphorylated extracellular glycoprotein, expressed in mineralized and nonmineralized tissues, organs and body fluids. The protein contains an RGD tripeptide cell‐binding motif, and is subjected to a variety of posttranslational modifications that play important roles in its multiple biological functions, such as bone remodeling and inhibition of pathological calcification. In this study, we have expressed bovine osteopontin in a prokaryotic system and identified the seven amino acid residues phosphorylated in vitro by CKII. J. Cell. Biochem. 103: 852–856, 2008. © 2007 Wiley‐Liss, Inc.
Kinetic study of ytterbium(III) extraction from sulfate medium with Cyanex 923
Authors: Wang Weiwei , Liu Jianjun , He Wenwei , Li Deqian
Published: July 2007

The kinetics of ytterbium(III) extraction from sulfate medium with Cyanex 923 in heptane has been investigated with a constant interfacial cell with laminar flow, which aimed to identify the extraction regime, reaction zone and rate equations. It was found that the extraction rate of ytterbium(III) increased linearly with stirring speed and specific interfacial area. The activation energy Ea (9.56 kJ mol−1), activation enthalpy ΔH± (7.05 kJ mol−1), activation entropy ΔS±298 (−0.31 kJ mol−1) and Gibbs free energy of activation ΔG±298 (98.3 kJ mol−1) were calculated from the dependence of extraction rate on temperature. The experiential rate equations were obtained by investigating the influence of the concentration of various species on the extraction rate. A diffusion regime has been deduced from evidence of the linear dependence of extraction rate on stirring speed and the low value of the activation energy. The liquid–liquid interface is most probably the reaction zone in view of the linear dependence of extraction rate on specific interfacial area, the high interfacial activity and low water‐solubility of extractant. Thus the mass transfer rate is controlled by interfacial film diffusion of species. Copyright © 2007 Society of Chemical Industry
Optimization of media constituents through response surface methodology for improved production of alkaline proteases by Serratia rubidaea
Authors: Doddapaneni Kiran Kumar , Tatineni Radhika , Potumarthi Ravichandra , Mangamoori Lakshmi Narasu
Published: July 2007

BACKGROUND: Response surface methodology is used to build a predictive model of the combined effects of independent variables (pH, salt concentration starch and casein). The model was validated in a laboratory‐scale bioreactor for extracellular protease production from a newly isolated Serratia rubidaea.

RESULTS: Optimum medium conditions obtained from the optimization experiments after 48 h incubation were starch, 8 g L−1; casein, 4 g L−1; salt concentration 6.25 g L−1; and initial pH, 8. A coefficient of determination (R2) value of 0.9305 shows the fitness of the second‐order model for the present studies. Results of model coefficients estimated by multiple linear regressions indicate that linear effects of casein concentration (P < 0.001308) and initial pH (P < 7.91 E‐07) are more significant than similarly interactive effects of starch and casein (P < 0.019153), casein and salt concentration (P < 0.016294), casein and pH (P < 0.039904) and salt concentration and pH (p < 0.017845). The P‐values of quadratic effects of casein, x2 × x2 (P < 0.000171); SC, x3 × x3 (P < 0.009134); initial pH, x4 × x4 (P < 0.000114) are more significant for maximal production. After optimization, protease production was enhanced experimentally by almost 65% in a shake flask and by almost 115% in a bioreactor.

CONCLUSION: The alkaline proteases secreted by S. rubidaea were significant from an industrial perspective because of their stability against surfactants, oxidants and solvents. The statistical design is useful in economic protease production in a cost‐effective medium for potential use on an industrial scale. Copyright © 2007 Society of Chemical Industry
Alternative technologies for biotechnological fuel ethanol manufacturing
Authors: Vertès Alain A , Inui Masayuki , Yukawa Hideaki
Published: July 2007

The challenges of implementing biorefineries on a global scale include socioeconomic, financial, and technological constraints. In particular, the development of biorefineries is tightly linked to the continued availability of fermentation raw materials. These constraints can be relaxed by the use of diverse raw materials, while advances that confer higher flexibility would enable biotechnological plant managers to swiftly react to volatile markets. In conventional processes,Saccharomyces cerevisiaegrows on a relatively limited range of substrates, and produces only a single product—ethanol. Given the observed maturity of theS. cerevisiaefermentation technology, alternatives to baker's yeast may be needed to tip the economic balance in favour of biotechnological ethanol. These alternative fermentation technologies may allow a greater diversity of substrates to be used to produce an individually tailored mix of ethanol and other chemicals. Copyright © 2007 Society of Chemical Industry
Horseradish peroxidase‐catalysed oxidation of aqueous natural and synthetic oestrogens
Authors: Khan Usman , Nicell James A
Published: July 2007

The horseradish peroxidase (HRP)‐catalysed oxidation of selected potent oestrogens, including the natural oestrogens 17β‐oestradiol and oestriol and the synthetic oestrogen ethinyloestradiol, was studied and compared with that of phenol. HRP catalysed the oxidation of these oestrogens and phenol over a wide range of pH values, with optimal performance around neutral pH, which is in the range of typical urban wastewaters. In comparison with that of phenol, the oxidation of oestrogens consistently required less hydrogen peroxide. In addition, the rate of oxidation of oestradiol was equivalent, twofold faster and fivefold faster compared with that of ethinyloestradiol, oestriol and phenol respectively. For all substrates studied, similar kinetics of removal were observed provided that sufficient enzyme was added to reactions to compensate for differences in substrate affinity. In contrast with earlier studies with phenols in which HRP was observed to be susceptible to significant inactivation due to interactions with hydrogen peroxide and reaction products, minimal inactivation of HRP was observed during the present study, probably owing to the very low concentration of target substrates used here (i.e. 10 µmol dm−3) relative to earlier studies with other phenolic substrates. These observations suggest that this enzymatic approach has strong potential to be used to target the treatment of oestrogenic compounds. Copyright © 2007 Society of Chemical Industry
Direct detection of explosives on solid surfaces by mass spectrometry with an ambient ion source based on dielectric barrier discharge
Authors: Na Na , Zhang Chao , Zhao Mengxia , Zhang Sichun , Yang Chengdui , Fang Xiang , Zhang Xinrong
Published: July 2007

Trace amounts of explosives on solid surfaces were detected by mass spectrometry at ambient conditions with a new technique termed dielectric barrier discharge ionization (DBDI). By the needle–plate discharge mode, a plasma discharge with energetic electrons was generated, which could launch the desorption and ionization of the explosives from solid surfaces. Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), 2,4,6‐trinitrotoluene (TNT), and pentaerythritol tetranitrate (PETN) were desorbed directly from the explosives‐contaminated surface by DBDI, forming the typical anions of [TNT]−, [TNT − H]−, [RDX + NO2]−, [PETN + ONO2]−, and [RDX + ONO2]−. The ions were transferred into the MS instrument for analysis in the negative ion mode. The detection limit of present method was 10 pg for TNT (m/z 197, S/N 8 : 1), 0.1 ng for RDX (m/z 284, S/N 10 : 1), and 1 ng for PETN (m/z 260, S/N 12 : 1). The present method allowed the detection of trace explosives on various matrices, including paper, cloth, chemical fiber, glass, paints, and soil. A relative standard deviation of 5.57% was achieved by depositing 100 pg of TNT on these matrices. The analysis of A‐5, a mixture of RDX and additives, has been carried out and the results were consistent with the reference values. The DBDI‐MS method represents a simple and rapid way for the detection of explosives with high sensitivity and specificity, which is especially useful when they are present in trace amounts on ordinary environmental surfaces. Copyright © 2007 John Wiley & Sons, Ltd.
Rapid determination of gemcitabine in plasma and serum using reversed‐phase HPLC
Authors: Lanz Christian , Früh Martin , Thormann Wolfgang , Cerny Thomas , Lauterburg Bernhard H.
Published: July 2007

Gemcitabine (2′2′‐difluorodeoxycytidine) is a pyrimidine analog used in the treatment of a variety of solid tumors. After intravenous (i.v.) administration, it is rapidly inactivated to 2′‐deoxy‐2′,2′‐difluorouridine (dFdU). A sensitive analytical method for the quantitation of gemcitabine is required for the assessment of alternative dosage and treatment schemes. A rapid and robust RP‐HPLC assay for analysis of gemcitabine in human and animal plasma and serum was developed and validated using 2′‐deoxyuridine (dU) and 5‐fluoro‐2′‐deoxyuridine (5FdU) as internal standards. It is based on protein precipitation, the use of an Atlantis dC18 column of 100 mm length (inner diameter, 4.6 mm; particle size, 3 μm) and isocratic elution using a 10 mM phosphate buffer, pH 3.0, followed by isocratic elution with the same buffer containing 3% of ACN. For gemcitabine, RSD values for intraday and interday precision were < 4.4 and 5.3%, respectively, the LOQ was 20 ng/mL, and the assay was linear in the range of 0.020–20 μg/mL with an accuracy of ⪈89%. The recovery for gemcitabine, dU and 5FdU was 86–98%. The assay was applied to determine gemcitabine levels in plasma samples of patients collected during and shortly after conventional infusion of 25–30 mg/kg body mass (levels: 2.0–18.9 μg/mL) and rats that received lower doses (1.5 mg/kg) via i.v., subcutaneous and oral drug administration (levels: 0.20–2.60 μg/mL). It could also be applied to estimate dFdU levels in human plasma.
Quantitative determination of clozapine in serum by instrumental planar chromatography
Authors: Mennickent Sigrid , Sobarzo Alejandra , Vega Mario , Godoy Carmen Gloria , de Diego Marta
Published: July 2007

An instrumental planar chromatographic (HPTLC) method for quantitative analysis of clozapine in human serum was developed and validated. Clozapine was extracted with n‐hexane–isoamyl alcohol (75:25 v/v). The chromatographic separation was achieved on precoated silica gel F 254 HPTLC plates using a mixture of chloroform and methanol (9:1 v/v) as mobile phase. Quantitative analyses were carried out by densitometry at a wavelength of 290 nm. The method was linear between 10 and 100 ng/spot, corresponding to 0.10 and 1.00 ng/μL of clozapine in human serum after extraction process and applying 10 μL to the chromatographic plates. The method correlation coefficient was 0.999. The intra‐assay variation was between 2.10 and 3.33% (n = 5) and the interassay was between 2.67 and 4.44% (n = 9). The detection limit was 0.03 ng/μL, and the quantification limit was 0.05 ng/μL. The method proved to be accurate, with a recovery between 97.00 and 99.00%, with an RSD not higher than 7.22%, and was selective for the active principle tested. This method was successfully applied to quantify clozapine in patient serum samples. In conclusion, the method is useful for the quantitative determination of clozapine in serum.
Broad‐spectrum separations in metabolomics using enhanced polar LC stationary phases: A dedicated evaluation using plant metabolites
Authors: t'Kindt Ruben , Alaerts Goedele , Vander Heyden Yvan , Deforce Dieter , Van Bocxlaer Jan
Published: July 2007

In metabolomics, major efforts are invested in the development of suitable analytical approaches. A tendency towards the use of LC‐MS is nowadays very obvious. A great majority of the metabolites of interest are polar to highly polar in nature. We focus on the so‐called ‘extended polarity’ reversed LC phases, developed specifically to allow better retention characteristics for polar compounds. Several of these phases (Atlantis dC18, Inertsil ODS‐3, Zorbax XDB, Alltima HP C18) are tested for different column dimension variations (0.5, 1.0, 2.1 mm id) in a specific LC‐MS metabolomics setting. Important chromatographic and mass spectrometric quality parameters such as capacity factor, separation efficiency, peak symmetry, sensitivity, and mass accuracy are taken into account. All phases show adequate retention of polar compounds and also perform well with highly aqueous mobile phase compositions. On comparing 1.0 and 2.1 mm id columns, it is clear that the potential gain in sensitivity is not achieved. Using a Lockspray® device, accurate mass measurement with a Q‐TOF micro is feasible within a mass range of 12 ppm if signal intensities of compound and lockmass are equated. Finally, the extended polarity RP approach in metabolomics experiments is endorsed using real plant extracts.
Ropinirole is effective on motor function when used as an adjunct to levodopa in Parkinson's disease: STRONG study
Authors: Mizuno Yoshikuni , Abe Takashi , Hasegawa Kazuko , Kuno Sadako , Kondo Tomoyoshi , Yamamoto Mitsutoshi , Nakashima Mitsuyoshi , Kanazawa Ichiro ,   STRONG Study Group
Published: July 2007

We report the results of a randomized, double‐blind, placebo‐controlled, 16‐week study to evaluate the efficacy and safety of ropinirole, 0.75 to 15.0 mg/day, as an adjunct to levodopa. A total of 243 patients were randomly assigned into placebo or ropinirole groups. The mean (standard deviation) dose of ropinirole at endpoint was 7.12 (2.88) mg/day. The primary endpoint—the mean reduction in the Unified Parkinson's Disease Rating Scale (UPDRS) total motor score—was significantly greater for the ropinirole group than the placebo group (−9.5 vs. −4.5, P = 0.00001). The mean reduction in the UPDRS total activities of daily living (ADL) score was also significantly greater for ropinirole than for placebo (−2.7 vs. −1.0, P = 0.0002). The percentage of patients showing at least a 20% reduction in the percentage of time spent “off” was significantly greater for the ropinirole group than for the placebo group (58.7% vs. 38.6%, P = 0.030). A total of 84.3 and 65.6% of the patients experienced adverse events while receiving ropinirole or placebo, respectively. The results showed that ropinirole was more effective than placebo in improving motor function and ADL when used as an adjunct to levodopa in patients with advanced Parkinson's disease. © 2007 Movement Disorder Society
Administrative problems of the provincial sales tax on beer in Papua New Guinea
Authors: Ord T.
Published: July 2007

With the establishment of provincial government in Papua New Guinea, the Organic Law has conferred on the provincial governments the authority to raise revenue using local revenue bases including retail sales taxes. These taxes have significant advantages and a sales tax on beer has particular benefits in P.N.G. in terms of potential yield and ease of administrative management. The tax is levied on the two breweries and the breweries collect the tax at their breweries and wholesale warehouses on behalf of the provincial governments. For the brewery with the dominant share of the market the arrangement under which it collects the tax for a commission and pays over quarterly to the provincial governments brings financial advantage. The brewery with a smaller share of the market and localized sales is less likely to be benefitting by the arrangement. For the future given expected beer consumption a change from a quantity based tax to ad valorem rates would be financially advantageous to the provincial governments, and would reduce the need for some provinces to seek tax sources elsewhere, but experience shows the general benefit of raising the tax, not at the point of final sale, but on the wholesaler or manufacturer.
Private sector investment in the development of the Bahamas: Lessons learned from successful programme implementation
Authors: Agor Weston H.
Published: July 2007

One of the most significant problems developing nations have faced in recent years has been finding effective ways of implementing development plans and programmes. This is in large part due to the dearth of knowledge about programme implementation, and the lack of attention given to the design of implementation strategies by planners and administrators in third world nations.

But, implementation is now becoming a central concern of governments in developing countries and of officials in international funding institutions. Also, development administration theory in the 1980s is likely to have as its dominant focus the improvement of implementation management of development programmes and projects.

One way to improve the management of development programmes and projects is to analyse those development projects that have succeeded, identify the factors that appear to influence successful implementation, and disseminate this information as broadly and quickly as possible to relevant administrators and administrative theorists. It is revealing that relatively few studies of this type have been completed.

This article outlines the lessons learned from a programme that the Government of the Bahamas is successfully implementing‐the encouragement of foreign private sector investment in the Bahamas. The article (a) briefly outlines th'e plan for encouraging foreign investment, (b) describes the basic approaches and techniques the Bahamian Government has learned to use to improve the prospects of implementing this programme, and (c) indicates how this experience may be potentially useful in guiding the implementation of similar programmes in other developing countries.
Decentralization for regional development: A comparative study of Tanzania, Zambia and Papua New Guinea
Authors: Conyers Diana
Published: July 2007

Decentralization has been a common aim in administrative reform and this article points to common themes in the decentralization programmes of Tanzania, Zambia and Papua New Guinea. The programmes involve both developing field administrative structures on an area basis in which horizontal links between the field staff of different ministries are at least as important as the vertical lines of authority linking field staff with headquarters' departments, and also decentralizing authority over planning and implementing development programmes to local decision making bodies. The impact of these decentralization programmes has not hitherto been adequately monitored or evaluated, and experience of attempts at doing this in Tanzania emphasizes the importance of building into a decentralization programme a method of monitoring it which produces usable information. The article points to the plans for monitoring to be pursued in Zambia.
A case for professionalization of water management in irrigation projects in India
Authors: Jayaraman T. K.
Published: July 2007

The heavy investment in irrigation in India has not brought the expected benefits and this article argues first that a major difficulty arises from the way irrigated water is administered. The distribution of water is controlled by irrigation engineers who lack the knowledge and information to manage water in a way that maximizes agricultural production and achieves the confidence of farmers. The staffing structure and related professional values discourage the development of a new more appropriate specialism. The article goes on to argue that a new organization of work and associated staffing structure is needed which will encourage a new professional specialization bringing together staff and expertise currently dispersed in separate specialisms in engineering, agronomy and other aspects of agriculture.
Modernizing the budget system: The Malaysian experience
Authors: Joon‐Chien Doh
Published: July 2007

Programme and performance budgeting (PPB) was first introduced in Malaysia in 1969 and experience with operating and developing the system carries lessons for other countries. The initial introduction under the influence of external advisers, involved treating PPB as a mechanical exercise in which right procedures had to be followed. From 1972 the strategy changed to making the system serve to assist with utilizing and managing resources more efficiently in relation to programme objectives. The successful development of the system agency by agency points first to the importance of local rather than foreign expertise; second, to the need for the agency head to be committed and involved, rather than leave the introduction and management of the system to lower level experts; and third to the significance of the leadership role of the Treasury.
The legal environment of planned urban growth
Authors: McAuslan Patrick
Published: July 2007

The part that law as a skill and as a discipline can and should play in urban development and in the work of an urban development agency is discussed on the basis of recent experience in three countries. Emphasis is given to the importance of involving lawyers from the start of any programme for planned urban growth, and the disadvantage of bringing lawyers in only for specific legal jobs is stressed. The article surveys the range of work in which a lawyer is necessarily involved where planned urban development proceeds within a framework of law.
Sites and services schemes in Dacca: A critique
Authors: Hasnath Syed Abu
Published: July 2007

This paper presents a critical analysis of two sites and services projects in Dacca, in the light of previous studies of low income housing. The analysis demonstrates that resource limitation is not the most important factor preventing resolution of the low‐income housing problem, that there is a perverse use of resources which makes the situation worse, and that this use continues because it is in the pecuniary interest of the dominant interest group. The conclusions drawn are far from optimistic: (a) without radical changes in the main direction of resource allocation, there exists little or no possibility for an improvement in the living conditions of poor families; and, (b) the provision of housing for the lowest income group is more a question of political will and social engineering than building technology.