bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Determination of Thiocyanate and Salycilate by a Combined UV‐Spectrophotometric Detection Principal Component Artificial Neural Network
Authors: Karimi Hajir , Ghaedi Mehrorang
Published: November 2006

A modified principle component artificial neural network (PC‐ANN) model is developed for simultaneous determination of thiocyanate and salycilate concentration after passing through the bulk of a liquid membrane by tri‐phenyl benzyl phosphonium chloride. All calibration, and test samples data were obtained using UV‐Vis spectrophotometer. In this way, a modified PC‐ANN consisting of three layers of nodes was trained by combination of Bayesian‐Levenberg‐Marquardt as training rule. Sigmoid and liner transfer functions were used in the hidden and output layers respectively to facilitate nonlinear calibration. The model could accurately estimate the concentration of components with acceptable precision and accuracy, for mixtures. The PC‐ANN model exhibits a good ability for the simultaneous determination of the thiocyanate and salycilate in concentration range 0.5 × 10−4mol.l−1up to 5.0 × 10−4mol.l−1with Root Mean square error (2.22% and 2.20%, for thiocyanate and salycilate, respectively) and high correlation coefficients (R2= 0.998 or greater). Results obtained with modified trained PC‐ANN were compared with stepwise linear regression (SMLR) model. Validation of the two models shows a better ability in estimation of the modified PC‐ANN as compared with the SMLR model (MSRE given are 3.12%, 6.31%.).
Municipal sludge degradation kinetic in thermophilic CSTR
Authors: de la Rubia Ángeles , Pérez Montserrat , Sales Diego , Romero Luis I.
Published: November 2006

The performance of a pilot‐scale continuous‐flow stirred‐tank reactor (CSTR) treating municipal sludge under thermophilic conditions has been studied. Two pilot‐scale reactors (CSTR1 (175 L) and CSTR2 (850 L)) were operated at different hydraulic residence times (θ: 40 to 15 days). The anaerobic sludge processes are generally affected by variations in the concentration of substrate (determined as influent volatile solids, VS) and volumetric flow, both of which lead to a modification in biomass concentration and VS removal efficiency. This unsteady‐state situation is mathematically explained in terms of an autocatalytic kinetic model. The general kinetic equation in this model has been applied to experimental data obtained in CSTR1. The fit of the experimental data to the model was used to estimate kinetic parameters and the yield coefficients (μmax, α, YP/S). The estimated parameters were μmax: 0.175d−1, α: 0.358, YP/S: 0.309 m3CH4/kgVS). These parameters were subsequently used to model the substrate utilization rate and the methane generation rate in CSTR2. The model with the estimated parameters was found to provide excellent results, and is satisfactory in describing the concentration of VS and the methane generation rate in an actual digestion plant. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Reaktionen in Mikrofluidiktröpfchen
Authors: Song Helen , Chen Delai L. , Ismagilov Rustem F.
Published: November 2006

Tröpfchenbasierte Mikrofluidiksysteme bieten in der Chemie und Biologie ausgezeichnete experimentelle Möglichkeiten für die Grundlagenforschung und angewandte Forschung. Sie ermöglichen die Miniaturisierung von Reaktionen, indem Reaktionsvolumina in femto‐ bis mikrolitergroßen Tröpfchen kompartimentiert werden. Die Kompartimentierung in Tröpfchen ermöglicht die schnelle Durchmischung der Reagentien, die zeitliche Steuerung der Reaktionen im Bereich von Millisekunden bis zu Monaten, die Steuerung von Grenzflächeneigenschaften und die Synthese und den Transport von festen Reagentien und Produkten. Mithilfe von tröpfchenbasierten Mikrofluidiksystemen können Anwendungen im Bereich des chemischen und biologischen Screenings, der Proteinkristallisation und der Enzymkinetik verbessert und beschleunigt werden. Darüber hinaus bietet die mögliche Steuerung von Tröpfchen in Mikrofluidikeinheiten Aussichten auf neue wissenschaftliche Methoden und Erkenntnisse.
Luminol chemiluminescence catalysed by colloidal platinum nanoparticles
Authors: Xu Sheng‐Liang , Cui Hua
Published: November 2006

Platinum colloids prepared by the reduction of hexachloroplatinic acid with citrate in the presence of different stabilizers were found to enhance the chemiluminescence (CL) of the luminol–H2O2 system, and the most intensive CL signals were obtained with citrate‐protected Pt colloids synthesized with citrate as both a reductant and a stabilizer. Light emission was intense and reproducible. Transmission electron microscopy and X‐ray photoelectron spectroscopy studies were conducted before and after the CL reaction to investigate the possible CL enhancement mechanism. It is suggested that this CL enhancement is attributed to the catalysis of platinum nanoparticles, which could accelerate the electron‐transfer process and facilitate the CL radical generation in aqueous solution. The effects of Pt colloids prepared by the hydroborate reduction were also investigated. The application of the luminol–H2O2–Pt colloids system was exploited for the determination of compounds such as uric acid, ascorbic acid, phenols and amino acids. Copyright © 2006 John Wiley & Sons, Ltd.
Luminol–hydrogen peroxide chemiluminescence produced by sweet potato peroxidase
Authors: Alpeeva Inna S. , Yu. Sakharov Ivan
Published: November 2006

Anionic sweet potato peroxidase (SPP; Ipomoea batatas) was shown to efficiently catalyse luminol oxidation by hydrogen peroxide, forming a long‐term chemiluminescence (CL) signal. Like other anionic plant peroxidases, SPP is able to catalyse this enzymatic reaction efficiently in the absence of any enhancer. Maximum intensity produced in SPP‐catalysed oxidation of luminol was detected at pH 7.8–7.9 to be lower than that characteristic of other peroxidases (8.4–8.6). Varying the concentrations of luminol, hydrogen peroxide and Tris buffer in the reaction medium, we determined favourable conditions for SPP catalysis (100 mmol/L Tris–HCl buffer, pH 7.8, containing 5 mmol/L hydrogen peroxide and 8 mmol/L luminol). The SPP detection limit in luminol oxidation was 1.0 × 10−14 mol/L. High sensitivity in combination with the long‐term CL signal and high stability is indicative of good promise for the application of SPP in CL enzyme immunoassay. Copyright © 2006 John Wiley & Sons, Ltd.
Adsorption, absorption, and biological degradation of ammonia in different biofilter organic media
Authors: Pagans Estela , Font Xavier , Sánchez Antoni
Published: November 2006

A tailor‐made apparatus called ammoniometer, which is a batch mode respirometer applied to the study of ammonia biodegradation in biofilter media, has been used to evaluate adsorption, absorption, and biodegradation in five different organic materials (compost, coconut fibre, bark, pruning wastes, and peat) obtained from full‐scale biofilters in operation in several waste treatment plants. The results showed that absorption could be represented by a Henry's law linear equation, with values of the Henry coefficient significantly higher (from 1,866 to 15,320) than that of pure water (1,498). Adsorption data were successfully fitted to Langmuir and Freundlich isotherms and maximum adsorption capacity varies from 1.06 to 1.81 mg NH3/g dry media. Ammonia biodegradation rates for each organic material were also calculated. Biodegradation rates varied from 0.67 to 7.82 mg NH3/kg media/d depending on the material tested. The data obtained showed important differences in the behaviour of the biofilter organic media, which has important implications in the design and modelling of these systems. Biotechnol. Bioeng. 2007;97: 515–525. © 2006 Wiley Periodicals, Inc.
SEM and 3D synchrotron radiation micro‐tomography in the study of bioceramic scaffolds for tissue‐engineering applications
Authors: Peyrin Françoise , Mastrogiacomo Maddalena , Cancedda Ranieri , Martinetti Roberta
Published: November 2006

Different biomaterials have been proposed as scaffolds for the delivery of cells and/or biological molecules to repair or regenerate damaged or diseased bone tissues. Particular attention is being given to porous bioceramics that mimic trabecular bone chemistry and structure. Chemical composition, density, pore shape, pore size, and pore interconnection are elements that have to be considered to improve the efficiency of these biomaterials. Commonly, two‐dimensional (2D) systems of analysis such as scanning electron microscope (SEM) are used for the characterization and comparison of the scaffolds. Unfortunately, these systems do not allow a complete investigation of the three‐dimensional (3D) spatial structure of the scaffold. In this study, we have considered two different techniques, that is, SEM and 3D synchrotron radiation (SR) micro‐CT to extract information on the geometry of two hydroxyapatite (HA) bioceramics with identical chemical composition but different micro‐porosity, pore size distribution, and pore interconnection pathway. The two scaffolds were obtained with two different procedures: (a) sponge matrix embedding (scaffold FB), and (b) foaming (scaffold EP). Both scaffolds showed structures suitable for tissue‐engineering applications, but scaffold EP appeared superior with regard to interconnection of pores, surface on which the new bone could be deposited, and percentage of volume available to bone deposition. Biotechnol. Bioeng. 2007;97: 638–648. © 2006 Wiley Periodicals, Inc.
Thermodynamic electron equivalents model for bacterial yield prediction: Modifications and comparative evaluations
Authors: McCarty Perry L.
Published: November 2006

Modifications are made to an earlier thermodynamic model (TEEM1) for prediction of maximum microbial yields from aerobic and anaerobic as well as heterotrophic and autotrophic growth. The revised model (TEEM2) corrects for lower yields found with aerobic oxidations of organic compounds where an oxygenase is involved and with growth on single‐carbon (C1) compounds. TEEM1 and TEEM2 are based on energy release and consumption as determined from the reduction potential or Gibbs free energy of ½‐reaction reduction equations together with losses of energy during energy transfer. Energy transfer efficiency is a key parameter needed to make predictions with TEEM2, and was determined through evaluations with extensive data sets on aerobic heterotrophic yield available in the literature. For compounds following normal catabolic pathways, the best‐fit value for energy transfer efficiency was 0.37, which permitted accurate predictions of growth with a precision of 15%–20% as determined by standard deviation. Using the same energy transfer efficiency, a similar precision, but somewhat less accuracy was found for organic compounds where oxidation involves an oxygenase (estimates 8% too high) and for C1 compounds (estimates 17% too high). In spite of the somewhat lower accuracy, the TEEM2 modifications resulted in improved predictions over TEEM1 and the comparison models. Biotechnol. Bioeng. 2007;97: 377–388. © 2006 Wiley Periodicals, Inc.
Catalytic Relationships between Type I and Type II Iterative Polyketide Synthases: The Aspergillus parasiticus Norsolorinic Acid Synthase
Authors: Ma Yue , Smith Leah H. , Cox Russell J. , Beltran‐Alvarez Pedro , Arthur Christopher J. , Simpson Thomas J.
Published: November 2006

Norsolorinic acid synthase (NSAS) is a type I iterative polyketide synthase that occurs in the filamentous fungus Aspergillus parasiticus. PCR was used to clone fragments of NSAS corresponding to the acyl carrier protein (ACP), acyl transferase (AT) and β‐ketoacyl‐ACP synthase (KS) catalytic domains. Expression of these gene fragments in Escherichia coli led to the production of soluble ACP and AT proteins. Coexpression of ACP with E. coli holo‐ACP synthase (ACPS) let to production of NSAS holo‐ACP, which could also be formed in vitro by using Streptomyces coelicolor ACPS. Analysis by mass spectrometry showed that, as with other type I carrier proteins, self‐malonylation is not observed in the presence of malonyl CoA alone. However, the NSAS holo‐ACP serves as substrate for S. coelicolor MCAT, S. coelicolor actinorhodin holo‐ACP and NSAS AT domain‐catalysed malonate transfer from malonyl CoA. The AT domain could transfer malonate from malonyl CoA to NSAS holo‐ACP, but not hexanoate or acetate from either the cognate CoA or FAS ACP species to NSAS holo‐ACP. The NSAS holo‐ACP was also active in actinorhodin minimal PKS assays, but only in the presence of exogenous malonyl transferases.
Magnetic Face‐to‐Face Interaction and Electrocommunication in Chromium Sandwich Compounds
Authors: Elschenbroich Christoph , Kanellakopulos Basil , Köhler Frank H. , Metz Bernhard , Lescouëzec Rodrigue , Mitzel Norbert W. , Strauß Werner
Published: November 2006

The reaction of [{(C5Me5)CrCl2}2] with [2.2](1,4)cyclophane gave [(C5Me5)Cr{[2.2](1,4)cyclophane}] (1) and [(C5Me5)Cr{[2.2](1,4)cyclophane}Cr(C5Me5)] (2), depending on the reaction conditions. X‐ray structure analysis showed 2 to be a ministack which in turn is stacked in the lattice. The chromium atoms are 6.035 Å apart, and the distortion of the benzene rings to boat‐shaped moieties is less pronounced than in parent [2.2](1,4)cyclophane. The NMR and EPR spectra were consistent with a S=1/2 ground state for 1 and with two interacting S=1/2 centers in 2. Spin density was found in the ligand π systems, where its sign was negative when the π system was adjacent to chromium, while on the nonbonded benzene moiety of 1 it was positive. Cyclic voltammograms showed reductions to 1− and 22−, as well as oxidations to 1+, 2+, and 22+ which were quasireversible, whereas oxidations to 12+ and 23+ were irreversible. Interaction between the metal ions was revealed by a 260 mV separation of the redox waves belonging to 2+, and 22+. Both cations were isolated as [B(C6H5)4]− salts, which in solution decomposed to [2.2](1,4)cyclophane and [(C5Me5)Cr{(η6‐C6H5)B(C6H5)3}] (3). The 1H and 13C NMR spectra of 3 were in accordance with an S=1 ground state. Solid‐state magnetic measurements of the dimetallic compounds showed antiferromagnetic interaction with J=−122 cm−1 for 2, J=−31 cm−1 for 2+ (ground state S=1/2), and J=−23.5 cm−1 for 22+ (with H=−JS1S2). The decrease of J in the series 2, 2+, and 22+ was traced to the number of unpaired electrons and, for the mixed‐valent cation 2+, to additional double exchange.
Enantioseparation, absolute configuration determination, and anticonvulsant activity of (±)‐1‐(4‐aminophenyl)‐7,8‐methylenedioxy‐1,2,3,5‐tetrahydro‐4H‐2,3‐benzodiazepin‐4‐one
Authors: Calabrò Maria Luisa , Raneri Daniela , Ficarra Paola , Ferreri Guido , De Sarro Giovambattista , Bruno Giuseppe , Zappalà Maria , Micale Nicola , Grasso Silvana
Published: November 2006

The resolution of 1‐(4‐aminophenyl)‐7,8‐methylenedioxy‐1,2,3,5‐tetrahydro‐4H‐benzodiazepin‐4‐one (±)‐(R,S)‐2 was accomplished by chiral HPLC. The absolute configuration of (+)‐2, determined by X‐ray crystallographic analysis, was R. The in vivo anticonvulsant activity of the enantiomers (+)‐(R)‐2 and (−)‐(S)‐2 is reported. It has been also demonstrated that compound (±)‐(R,S)‐2 in vivo undergoes oxidative metabolism to derivative 1. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Formation of Trichlorinated Dibenzo‐p‐dioxins from 2,4‐Dichlorophenol and 2,4,5‐Trichlorophenolate: A Theoretical Study
Authors: Suárez Ernesto , Suárez Dimas , Menéndez Maria Isabel , López Ramón , Sordo Tomás Luis
Published: November 2006

The reaction of the 2,4,5‐trichlorophenolate anion with 2,4‐dichlorophenol to afford trichlorinated dibenzo‐p‐dioxins (T3CDDs) is investigated at the B3LYP/6‐31+G(d) and B3LYP/6‐311+G(3df,2p)//B3LYP/6‐31+G(d)+ZPVE(B3LYP/6‐31+G(d)) levels of theory. The first stage of the process corresponds to the formation of a predioxin, which can evolve through four different routes. Two of them lead directly to the products 2,3,7‐T3CDD and 1,3,8‐T3CDD, and the other two afford different predioxin‐type intermediates, which in turn can evolve through all or some of the four routes to give new predioxins or T3CDD. Consequently, the theoretical results obtained show plainly the complex chemistry implied in the formation of dioxins from chlorophenols via anionic mechanisms by disclosing all the critical structures through which the system evolves, thus allowing assessment of the viability of the different mechanistic routes and the accessible products. The statistical thermodynamics treatment at 1 atm and 298.15, 600, 900, and 1200 K indicates that at higher temperatures, the Gibbs energy barrier for the formation of the initial predioxin is clearly the rate‐determining step for the whole process, but at lower temperatures the Gibbs energy barrier for this step is similar to those for its evolution into 2,3,7‐T3CDD. This result is in contrast with previous proposals that the closure of the central ring is the rate‐limiting step. Finally, according to our results the rate constant for the formation of polychlorinated dibenzo‐p‐dioxins increases with the temperature, in agreement with the experimental observation that the conversion of trichlorophenols increases when going from 600 to 900 K in the gas phase in the absence of catalysts, and with DFT molecular dynamics results.
Innovative interventions for disordered eating: Evaluating dissonance‐based and yoga interventions
Authors: Mitchell Karen S. , Mazzeo Suzanne E. , Rausch Sarah M. , Cooke Kathryn L.
Published: November 2006

Objective:

Eating‐disordered behavior is prevalent among college women. Few interventions have successfully reduced risk factors for these behaviors, however. The most promising interventions are both selective and interactive. This study compared two newer types of interventions that meet these criteria: cognitive dissonance and yoga programs.

Method:

This study advertised programs for women who were dissatisfied with their bodies. Participants (N = 93) were randomly assigned to dissonance, yoga, or control groups.

Results:

Hierarchical regression analyses revealed that there were no significant post‐intervention differences between the yoga and control groups. Dissonance group participants had significantly lower scores than the scores of both other groups on measures of disordered eating, drive for thinness, body dissatisfaction, alexithymia, and anxiety.

Conclusion:

These findings have important implications for interventions on college campuses. In particular, dissonance interventions appear to be an efficient and inexpensive approach to reducing eating disorder risk factors. Additional research regarding the value of yoga interventions is needed. © 2006 by Wiley Periodicals, Inc. Int J Eat Disord 2006
A randomized comparison of cognitive behavioral therapy and behavioral weight loss treatment for overweight individuals with binge eating disorder
Authors: Munsch Simone , Biedert Esther , Meyer Andrea , Michael Tanja , Schlup Barbara , Tuch Alex , Margraf Juergen
Published: November 2006

Objectives:

The aim of this study was to determine the efficacy of cognitive‐behavioral therapy (CBT) and behavioral weight loss treatment (BWLT) for overweight patients with binge eating disorder (BED).

Method:

Eighty obese patients meeting criteria of BED according to DSM‐IV‐TR were randomly assigned to either CBT or BWLT consisting of 16 weekly treatments and 6 monthly follow‐up sessions. Binge eating, general psychopathology, and body mass index (BMI) were assessed before, during, and after treatment, and at 12‐month follow‐up.

Results:

At posttreatment results favored CBT as the more effective treatment. Analysis of the course of treatments pointed to a faster improvement of binge eating in CBT based on the number of self‐reported weekly binges, but faster reduction of BMI in BWLT. At 12‐month follow‐up, no substantial differences between the two treatment conditions existed.

Conclusion:

CBT was somewhat more efficacious than BWLT in treating binge eating but this superior effect was barely maintained in the long term. Further research into cost effectiveness is needed to assess which treatment should be considered the treatment of choice. © 2006 by Wiley Periodicals, Inc. Int J Eat Disord 2006
Relationships among attachment styles, personality characteristics, and disordered eating
Authors: Eggert Janet , Levendosky Alytia , Klump Kelly
Published: November 2006

Objective:

Insecure attachment styles and certain personality characteristics (i.e., high levels of neuroticism) have been associated with eating pathology. However, previous research has not examined these variables simultaneously and has not examined possible mediating relationships between attachment and personality characteristics for disordered eating. Because personality characteristics have emerged as some of the most robust predictors of disordered eating, it was predicted that the link between attachment and disordered eating might be through personality styles.

Method:

Participants included 85 female twins and triplets who took part in the Michigan State University Twin Study. Disordered eating, attachment style, and personality characteristics were assessed. Hierarchical linear models were used to examine relationships among the variables.

Results:

Overall, neuroticism, and extra version to a lesser extent, mediated the relationship between insecure‐resistant attachment and disordered eating. Specifically, higher scores on the neuroticism scale predicted more disordered eating and explained the relationship between insecure‐resistant attachment and disordered eating.

Conclusion:

These results suggest that relationships between attachment style and disordered eating are indirect, in that neuroticism fully mediates associations between insecure‐resistant attachment and disordered eating. © 2006 by Wiley Periodicals, Inc. Int J Eat Disord 2006
One‐Step Synthesis of Natural Product‐Inspired Biaryl Ether‐Cyclopeptoid Macrocycles by Double Ugi Multiple‐Component Reactions of Bifunctional Building Blocks
Authors: Michalik Dirk , Schaks Angela , Wessjohann Ludger A.
Published: November 2006

Isonitrile‐functionalized biaryl ethers can serve as key building blocks for the highly efficient one‐step production of natural product inspired‐macrocycles, with six or even twelve new bonds and rings with up to 50 members being formed in total yields of up to 51 %. Aliphatic diamine and diacid tethers give access to two different classes of N‐substituted biaryl ether cyclopeptides, suitable for library construction. As part of a conceptual work on MiBs (multiple multicomponent macrocyclizations/macrocycles including bifunctional building blocks), the influence of length and type of flexible tethers on the propensity for cyclization is studied.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Tandem‐Selective Bond Cleavage of the Lactam Nucleus and Michael Reaction
Authors: De Vitis Luisella , Troisi Luigino , Granito Catia , Pindinelli Emanuela , Ronzini Ludovico
Published: November 2006

The reactivity of the β‐lactam ring towards nucleophiles has been investigated. Ring‐opening reactions were performed on 3‐allyl‐β‐lactams with CH3O–/CH3OH at room temperature and/or reflux. Lactam nucleus isomerization followed by N1–C2 bond cleavage and methanol Michael addition afforded substituted amino esters. The reactivity of the four‐membered ring towards nucleophiles was found to depend on the substituents at the lactamic nitrogen and the C3 and C4 atoms. The ring‐opening path is highlighted in this report. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis of Alkaloid Analogues from β‐Amino Alcohols by β‐Fragmentation of Primary Alkoxyl Radicals
Authors: Boto Alicia , Hernández Dácil , Hernández Rosendo , Montoya Adriana , Suárez Ernesto
Published: November 2006

The fragmentation of primary alkoxyl radicals is usually a minor process with respect to hydrogen abstraction and other competing reactions. However, when β‐amino alcohols were used as substrates, the scission proceeded in good to excellent yields and no side reactions were observed. The fragmentation can be coupled with an allylation or alkylation reaction, to give alkaloid analogues and functionalized nitrogen heterocycles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis of Chiral Ligands from Hydrindene Diols with a Consecutive Heterodomino Transformation as the Key Reaction Step
Authors: Finet Laure , Dakir Mohamed , Castellote Isabel , Kaoudi Talbi , Toupet Loïc , Arseniyadis Siméon
Published: November 2006

We report here the elaboration of a bicyclo[2.2.2]octane system, synthesized by a consecutive domino process, towards highly functionalized stereopure derivatives, which could be used as multidentate ligands for the generation of asymmetric catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Seasonal confounding and residual correlation in analyses of health effects of air pollution
Authors: Ghement Isabella R. , Heckman Nancy E. , Petkau A. John
Published: November 2006

To investigate the health effects of air pollution via a partially linear model, one must choose an appropriate amount of smoothing for accurate estimation of the linear pollution effects. This choice is complicated by the dependencies between the various covariates and by the potential residual correlation. Most existing approaches to making this choice are inadequate, as they neither target accurate estimation of the linear pollutant effects nor handle residual correlation. In this paper, we illustrate two new adaptive and objective methods for determining an appropriate amount of smoothing. We construct valid confidence intervals for the linear pollutant effects, intervals that account for residual correlation. We use our inferential methods to investigate the same‐day effects of PM10 on daily mortality in two data sets for the period 1994 to 1996: one collected in Mexico City, an urban area with high levels of air pollution, and the other collected in Vancouver, British Columbia, an urban area with low levels of air pollution. For Mexico City, our methodology does not detect a PM10 effect. In contrast, for Vancouver, a PM10 effect corresponding to an expected 2.4% increase (95% confidence interval ranging from 0.0% to 4.7%) in daily mortality for every 10 µg/m3 increase in PM10 is identified. Copyright © 2006 John Wiley & Sons, Ltd.
Osteogenic differentiation of marrow stromal cells cultured on nanoporous alumina surfaces
Authors: Popat Ketul C. , Chatvanichkul Kwan‐Isara , Barnes George L. , Latempa Thomas Joseph , Grimes Craigs A. , Desai Tejal A.
Published: November 2006

A major goal in orthopedic biomaterials research is to design implant surfaces, which will enhance osseointegration in vivo. Several microscale as well as nanoscale architectures have been shown to significantly affect the functionality of bone cells i.e., osteoblasts. In this work, nanoporous alumina surfaces fabricated by a two‐step anodization process were used. The nanostructure of these surfaces can be controlled by varying the voltage used for anodization process. Marrow stromal cells were isolated from mice and seeded on nanoporous and amorphous (control) alumina surfaces. Cell adhesion, proliferation, and viability were investigated for up to 7 days of culture. Furthermore, the cell functionality was investigated by calcein staining. The cells were provided with differentiation media after 7 days of culture. The alkaline phosphatase (ALP) activity and matrix production were quantified using a colorimetric assay and X‐ray photoelectron spectroscopy (XPS) for up to 3 weeks of culture (2 weeks after providing differentiation media). Further, scanning electron microscopy (SEM) was used to investigate osteoblast morphology on these nanoporous surfaces. Over the 3‐week study, the nanoporous alumina surfaces demonstrated ∼45% increase in cell adhesion, proliferation, and viability, 35% increase in ALP activity, and 50% increase in matrix production when compared with the control surfaces. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Batch production of biosurfactant with foam fractionation
Authors: Chen Chien‐Yen , Baker Simon C. , Darton Richard C.
Published: November 2006

Methods of producing the biosurfactant surfactin from cultures of Bacillus subtilis (BBK006) have been investigated. A reactor with integrated foam fractionation was designed and used in batch mode, and the performance compared with that of the same culture in shaken flasks. In the batch reactor, significant foaming occurred between 12.5 h and 14.5 h of culture time. During this period, the foam was routed through the foam fractionation column to a mechanical foam breaker, and a biosurfactant‐enriched foamate was collected. Concentration of surfactin in the foamate product was around 50 times greater than that in the culture medium. Using the integrated reactor, 136 mg L−1 of surfactin was produced, significantly more than was achieved in shaken flasks (92 mg L−1). The foam fractionation method allowed a real‐time measurement of the rate of surfactin production during growth. This showed that the maximum rate of production occurred at the interphase between log and stationary modes of growth, in contrast to previous work showing that surfactin is exclusively a secondary metabolite. The high value of surfactin yield in relation to biomass (YP/x = 0.262) indicated that surfactin was produced very efficiently by Bacillus subtilis (BBK006) in this integrated bioreactor. Copyright © 2006 Society of Chemical Industry
Evaluation of the titanium dioxide approach for MS analysis of phosphopeptides
Authors: Klemm Clementine , Otto Sebastian , Wolf Constanze , Haseloff Reiner F. , Beyermann Michael , Krause Eberhard
Published: November 2006

The affinity of titanium dioxide for phosphate groups has been successfully used for enrichment of phosphopeptides from complex mixtures. This paper reports the relationship between the occurrence of some amino acids and the phospho‐specific and nonspecific binding of peptides that occurs during titanium dioxide enrichment. In order to perform a systematic study, two well‐characterized peptide mixtures consisting of either 33 or 8 synthetic phosphopeptides and their nonphosphorylated analogs, which differed in charge and hydrophobicity, were synthesized and analyzed by ESI‐MS and MALDI‐MS. The titanium dioxide procedure was also evaluated for comprehensive detection of phosphopeptides in phosphoproteomics. In summary, our results clearly confirm the high selectivity of titanium dioxide for phosphorylated sequences. Drastically reduced recovery was observed for phosphopeptides with multiple basic amino acids. Nonspecific binding of nonphosphorylated peptides and sample loss of phosphopeptides must also be taken into account. Copyright © 2006 John Wiley & Sons, Ltd.
Callus formation enhanced by BMP‐7 ex vivo gene therapy during distraction osteogenesis in rats
Authors: Hu J. , Qi M.C. , Zou S.J. , Li J.H. , Luo E.
Published: November 2006

This study was designed to observe the effects of bone morphogenetic protein‐7 (BMP‐7) ex vivo gene therapy on callus formation during rat mandibular distraction osteogenesis (DO). Fifty‐four Sprague‐Dawley rats underwent osteodistraction of the right mandible and were then randomly divided into three groups. Immediately after distraction, autologous bone marrow mesenchymal stem cells (MSCs) transfected with BMP‐7, MSCs untransfected with BMP‐7, and physiological saline were injected into the distraction gaps of the mandibles in groups A, B, and C, respectively. Nine animals from each group were euthanized at 2 and 6 weeks after completion of distraction. The distracted mandibles were removed and processed for radiographic, histological, immunohistochemical, and scanning electron microscopic examinations as well as Ca/P ratio analysis. Group A animals showed greater bone formation and earlier mineralization in the distracted callus when compared with group B. Similarly increased callus formation was found in group B than group C. Positive immunostaining of BMP‐7 was observed in the distracted callus in all groups. However, BMP‐7 expression was much stronger in group A compared with groups B and C. The results of this study suggest that BMP‐7‐mediated ex vivo gene transfer based on MSCs may accelerate callus formation in distraction osteogenesis and facilitate consolidation. Local gene therapy may ultimately be an alternative or supplemental approach to DO enhancement, especially for patients whose osteogenic potentials are compromised by diseases such as osteoporosis, severe trauma, and postoncologic irradiation. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:241–251, 2007
Vibrational study of the superprotonic phase transition in the mixed crystal Rb2(HSeO4)(H2PO4)
Authors: Jaouadi K. , Zouari N. , Mhiri T. , Daoud A. , Romain F.
Published: November 2006

Raman spectra (10–1200 cm−1) of polycrystalline samples of Rb2(HSeO4)(H2PO4) were studied at temperatures ranging from 300 to 423 K. An assignment of most of the observed bands is proposed. The first‐order phase transition previously detected at 382 K was characterized as:

This superionic‐protonic transition is believed to be governed by librations of the HSe/PO42− ion and the AOH (A = Se, P) stretching mode. It corresponds to the weakening of Se(P)OH˙˙˙ HOSe(P)hydrogen bonds and to the melting of the proton sublattice into a quasi‐liquid state in which the protons and the HSe/PO42− ions contribute to the unusually high conductivity. The activation energy that was determined from the plot Δν1/2 versus temperature for the ν (AOH) band has the same order of magnitude as that determined from conductivity measurements. Copyright © 2006 John Wiley & Sons, Ltd.
Acute effects of a lateral postural assist on voluntary step initiation in patients with Parkinson's disease
Authors: Mille Marie‐Laure , Johnson Hilliard Marjorie , Martinez Katherine M. , Simuni Tanya , Rogers Mark W.
Published: November 2006

Anticipatory postural adjustments (APAs) for lateral weight transfer and stability precede and accompany voluntary stepping. Patients with Parkinson's disease (PD) show delays in step initiation with altered APA characteristics that may reflect impaired interactions between posture and locomotion. The purpose of this study was to examine the influence of a lateral postural assist on step initiation in patients with early stage PD while off medication and healthy controls. Subjects performed self‐paced rapid forward steps. In one condition (ASSIST), the APA was assisted at onset with a lateral pull applied to the pelvis by a motor‐driven robotic system. Ground reaction forces and whole body kinematics were recorded to characterize the APA and step characteristics. Overall, PD subjects had a longer APA duration (P < 0.01) and longer first step duration (P < 0.027) than Control subjects. With the ASSIST, the APA duration for both groups was shorter (P < 0.001), the step onset time was earlier (P < 0.001), and the speed of the first step became faster for PD subjects. Postural assistance affecting the interaction between posture and locomotion may have therapeutic potential for improving movement function in patients with PD. © 2006 Movement Disorder Society
Validation of a new scale for the evaluation of sialorrhea in patients with Parkinson's disease
Authors: Perez Lloret Santiago , Pirán Arce Gabriel , Rossi Malco , Caivano Nemet María Laura , Salsamendi Paz , Merello Marcelo
Published: November 2006

Sialorrhea is common in Parkinson disease (PD), affecting approximately 70% to 75% of patients. Several tools for measuring saliva volume or production exist, but none are designed specifically for assessing sialorrhea‐related discomfort. The objective of this study was to develop and validate a clinical scale for subjective evaluation of sialorrhea in PD. In Phase I, internal consistency of the Sialorrhea Clinical Scale for PD (SCS‐PD) was established in 39 PD patients. In Phase II, scale validity was proven through saliva volume measurements obtained in 49 PD patients and 27 healthy volunteers. Internal consistency estimated using Cronbach's alpha was 0.78, indicating none of the original seven items tested needed to be removed. Twenty‐one patients complaining of sialorrhea (63%) studied during Phase II, showed higher SCS‐PD scores but no differences in saliva volume. SCS‐PD scores showed significant correlation with saliva volume (r = 0.41; P = 0.004) and with total Unified Parkinson's Disease Rating Scale Part III (UPDRS III) scores (r = 0.70). Furthermore, saliva volume showed inverse relation to age in PD patients as well as in controls (r = −0.3 and r = −0.4; P < 0.05), but SCS‐PD scores did not. The SCS‐PD scale showed good internal consistency and validity, providing support for its use in routine clinical sialorrhea‐related discomfort evaluation. © 2006 Movement Disorder Society
Laterality, region, and type of motor dysfunction correlate with cognitive impairment in Parkinson's disease
Authors: Williams Lindsy N. , Seignourel Paul , Crucian Gregory P. , Okun Michael S. , Rodriguez Ramon L. , Skidmore Frank M. , Foster Paul S. , Jacobson Charles E. , Romrell Janet , Bowers Dawn , Fernandez Hubert H.
Published: November 2006

We studied the relationship between two screening cognitive measures and off motor Unified Parkinson's Disease Rating Scale (UPDRS) scores in 108 Parkinson's disease patients. Multiple regressions were conducted to examine the UPDRS subscores' unique contributions to cognitive function. When including bradykinesia, rigidity, and postural/gait instability subscores, only bradykinesia predicted Mini Mental Status Examination (MMSE), normalized β = −0.57, t(104) = −3.31, P < 0.01, and Dementia Rating Scale‐2 (DRS‐2), normalized β = −0.45, t(104) = −2.55, P < 0.05. Tremor was not included in the regression analyses because it did not correlate with cognitive function. When including axial and appendicular subscores, only the axial subscore predicted MMSE, normalized β = −0.39, t(105) = −3.19, P < 0.01, and DRS‐2 scores, normalized β = −0.40, t(106) = −3.28, P < 0.01. When including left‐sided and right‐sided subscores, only the right‐sided symptoms predicted DRS‐2 scores, normalized β = −0.28, t(105) = −2.45, P < 0.05, and showed a trend toward predicting MMSE scores, normalized β = −0.22, t(105) = −1.95, P = 0.054. We therefore found that right‐sided symptoms (for laterality), axial symptoms (for region), and bradykinesia (for type of symptoms) were thebest predictors of cognitive function. © 2006 Movement Disorder Society
Sodium MRI of the human kidney at 3 Tesla
Authors: Maril Nimrod , Rosen Yael , Reynolds Glenn H. , Ivanishev Alex , Ngo Long , Lenkinski Robert E.
Published: November 2006

The sodium concentration gradient in the kidney (from the cortex to the medulla) serves to regulate fluid homeostasis and is tightly coupled to renal function. It was previously shown that renal function and pathophysiology can be characterized in rat kidneys by measuring the sodium gradient with 23Na MRI. This study demonstrates for the first time the ability of 23Na MRI to map the distribution of sodium in the human kidney and to quantify the corticomedullary sodium gradient. The study was performed on a 3T Signa LX scanner (GE) using an in‐house‐built quadrature surface coil. 23Na images of volunteers were acquired using a 3D coronal gradient‐echo sequence at a spatial resolution of 0.3 × 0.3 × 1.5 cm3 in a 25‐min scan time. The signal intensity (relative to the noise) increased linearly from the cortex to each of the medullae with a mean slope of 1.6 ± 0.2 in relative arbitrary units per mm (Rel.u./mm, N = 6) and then decreased, as expected, toward the renal pelvis. Water deprivation (12 hr) induced a significant increase of 25% (P < 0.05) in this gradient. Based on these results, we suggest that sodium MRI can serve as a valuable noninvasive method for functional imaging of the human kidney. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Fast 3D radiofrequency field mapping using echo‐planar imaging
Authors: Jiru F. , Klose U.
Published: November 2006

An inhomogeneous radiofrequency (RF) magnetic field is an essential source of error for the quantification of MRI and MRS parameters. To correct for effects of RF inhomogeneities in 3D data sets, it is necessary to have knowledge of the 3D RF distribution in the sample. In this paper a method for fast 3D RF mapping is presented. The method is based on the simultaneous acquisition of a spin echo (SE) and a stimulated echo (STE) using echo‐planar imaging (EPI). The acquisition of the 3D RF map using 64 partitions and TR = 500 ms requires 1.5 min. The use of the sequence in vivo is demonstrated by the calculation of the RF maps in the human brain at 3T. The comparison of calculated flip angles with the flip angles obtained by fitting signal behavior in the 3D stimulated‐echo acquisition mode (STEAM)‐EPI sequence and the analysis of errors due to spatially dependent T1 values in the brain show that the accuracy of the calculated flip angles in the human brain is about 2°. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Intrinsic fat suppression in TIDE balanced steady‐state free precession imaging
Authors: Paul Dominik , Hennig Jürgen , Zaitsev Maxim
Published: November 2006

A novel fat‐suppressed balanced steady‐state free precession (b‐SSFP) imaging method based on the transition into driven equilibrium (TIDE) sequence with variable flip angles is presented. The new method, called fat‐saturated (FS)‐TIDE, exploits the special behavior of TIDE signals from off‐resonance spins during the flip angle ramp. As shown by simulations and experimental data, the TIDE signal evolution for off‐resonant isochromats during the transition from turbo spin‐echo (TSE)‐like behavior to the true fast imaging with steady precession (TrueFISP) mode undergoes a zero crossing. The resulting signal notch for off‐resonant spins is then used for fat suppression. The efficiency of FS‐TIDE is demonstrated in phantoms and healthy volunteers on a 1.5T system. The resulting images are compared with standard TrueFISP data with and without fat suppression. It is demonstrated that FS‐TIDE provides a fast and stable means for homogenous fat suppression in abdominal imaging while maintaining balanced SSFP‐like image contrast and signal‐to‐noise ratio (SNR). The scan time of FS‐TIDE is not increased compared to normal TrueFISP imaging without fat suppression and identical k‐space trajectories. Because of the intrinsic fat suppression, no additional preparation is needed. Possible repetition times (TRs) are not firmly limited to special values and are nearly arbitrary. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Deconvolution‐interpolation gridding (DING): Accurate reconstruction for arbitrary k‐space trajectories
Authors: Gabr Refaat E. , Aksit Pelin , Bottomley Paul A. , Youssef Abou‐Bakr M. , Kadah Yasser M.
Published: November 2006

A simple iterative algorithm, termed deconvolution‐interpolation gridding (DING), is presented to address the problem of reconstructing images from arbitrarily‐sampled k‐space. The new algorithm solves a sparse system of linear equations that is equivalent to a deconvolution of the k‐space with a small window. The deconvolution operation results in increased reconstruction accuracy without grid subsampling, at some cost to computational load. By avoiding grid oversampling, the new solution saves memory, which is critical for 3D trajectories. The DING algorithm does not require the calculation of a sampling density compensation function, which is often problematic. DING's sparse linear system is inverted efficiently using the conjugate gradient (CG) method. The reconstruction of the gridding system matrix is simple and fast, and no regularization is needed. This feature renders DING suitable for situations where the k‐space trajectory is changed often or is not known a priori, such as when patient motion occurs during the scan. DING was compared with conventional gridding and an iterative reconstruction method in computer simulations and in vivo spiral MRI experiments. The results demonstrate a stable performance and reduced root mean square (RMS) error for DING in different k‐space trajectories. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Quantifying the performance effects of idle time utilization in multiserver systems
Authors: Tian Naishuo , Zhang Zhe George
Published: November 2006

In many practical multiserver queueing systems, servers not only serve randomly arriving customers but also work on the secondary jobs with infinite backlog during their idle time. In this paper, we propose a c‐server model with a two‐threshold policy, denoted by (e d), to evaluate the performance of this class of systems. With such a policy, when the number of idle servers has reached d (<c), then e (<d) idle agents will process secondary jobs. These e servers keep working on the secondary jobs until they find waiting customers exist in the system at a secondary job completion instant. Using the matrix analytic method, we obtain the stationary performance measures for evaluating different (e, d) policies. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007.
On valuing appreciating human assets in services
Authors: Zeynep Akşin O.
Published: November 2006

This paper derives optimal policies for when to hire, train, and lay off employees in service organizations when worker productivity appreciates deterministically or stochastically under constant, monotonic, and cyclic service demand. The model, an extension of the machine replacement problem from the engineering economy literature, uses infinite horizon linear programming to produce optimal personnel planning strategies and dual prices that characterize the workforce's economic value. The effect of employee attrition is also considered. In its valuation of human assets, unlike pure accounting approaches that only try to measure, this paper proposes an approach to capture the interaction between firm decisions pertaining to human resources and human resource value. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Uniformly optimal digraphs for strongly connected reliability
Authors: Brown J.I. , Li Xiaohu
Published: November 2006

Boesch et al. conjectured that for any n and m there exists a uniformly optimal (n,m)–graph Gn,m for all terminal reliability, that is, the all‐terminal reliability of Gn,m is at least as large as the all‐terminal reliability of any other graph G with n vertices and m edges, no matter what the probability of an edge being operational is. Although there are counterexamples known when one restricts attention to simple graphs, the conjecture remains open when one allows parallel edges. We consider the analogous problem for strongly connected reliability, that is, the probability that a digraph contains a spanning strongly connected subdigraph, given that each vertex is operational, but arcs are independently operational with probability p. We show that there do indeed exist uniformly optimal digraphs for strongly connected (n,m)–digraphs. We also show that if one restricts attention to simple digraphs (without parallel arcs) then such uniformly optimal digraphs need not exist. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 49(2), 145–151 2007
On super edge‐connectivity of Cartesian product graphs
Authors: Lü Min , Chen Guo‐Liang , Xu Jun‐Ming
Published: November 2006

The super edge‐connectivity λ′ of a connected graph G is the minimum cardinality of an edge‐cut F in G such that every component of G − F contains at least two vertices. Let Gi be a connected graph with order ni, minimum degree δi and edge‐connectivity λi for i = 1, 2. This article shows that λ′(G1 × G2) ≥ min{n1λ2, n2λ1, λ1 + 2 λ2, 2 λ1 + λ 2} for n1, n2 ≥ 3 and λ′(K2 × G2) = min{ n2, 2λ2}, which generalizes the main result of Shieh on the super edge‐connectedness of the Cartesian product of two regular graphs with maximum edge‐connectivity. In particular, this article determines λ′(G1 × G2) = min{n1δ2, n2δ1, ξ{G1 × G2)} if λ′(Gi) = ξ(Gi), where ξ(G) is the minimum edge‐degree of a graph G. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 49(2), 152–157 2007