bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of heterogeneous rate constants of reaction of electrochemically generated o‐benzoquinones with various nucleophiles containing thiol group
Authors: Fotouhi Lida , Tammari Esmail , Asadi Samaneh , Heravi Majid M. , Nematollahi Davood 
Published: March 2009

AbstractThe reaction of o‐benzoquinone derived by the oxidation of catechols (1a–c) with some nucleophiles containing thiol group (2a–f) has been studied in various conditions, such as pH, nucleophile concentration, and scan rate, using cyclic voltammetry. In various conditions, based on an EC electrochemical mechanism (“E” represents an electron transfer at the electrode surface and “C” represents a homogeneous chemical reaction), the observed homogeneous rate constants (kobs) were estimated by comparison of the experimental cyclic voltammetric responses with the digital simulated results for each of the nucleophile. The results show that the magnitude of kobs is dependent on the nature of the substituted group on the catechol ring and nucleophilicity of nucleophile. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 426–431, 2009
Kinetic studies of hydrazine and 2‐hydroxyethylhydrazine alkylation by 2‐chloroethanol: Influence of a strong base in the medium
Authors: Goutelle V. , Pasquet V. , Stephan J. , Bougrine A. J. , Delalu H. 
Published: March 2009

AbstractTo optimize yields, the study of reaction kinetics related to the synthesis of 2‐hydroxyethylhydrazine (HEH) obtained from the alkylation of N2H4 by 2‐chloroethanol (CletOH) was carried out with and without sodium hydroxide. In both cases, the main reaction of HEH formation was followed by a consecutive, parallel reaction of HEH alkylation (or dialkylation of N2H4), leading to the formation of two isomers: 1,1‐di(hydroxyethyl)hydrazine and 1,2‐di(hydroxyethyl)hydrazine. In this study, hydrazine and hydroxyalkylhydrazine alkylations followed SN2 reactions triggered directly by CletOH or indirectly in the presence of a strong base by ethylene oxide, an intermediate compound. The kinetics was studied in diluted mediums by quantifying HEH and CletOH by gas chromatography and gas chromatography coupled with mass spectrometry (GC‐MS). The activation parameters of each reaction and the influence of a strong base present in the medium on the reaction mechanisms were established. A global mathematical treatment was applied for each alternative. It allowed modeling the reactions as a function of reagent concentrations and temperature. In the case of direct alkylation by CletOH, simulation was established for semi‐batch and batch syntheses and was confirmed in experiments for concentrated mediums (1.0 M ≤ [CletOH]0 ≤ 3.2 M and 15.7 M ≤ [N2H4]0 ≤ 18.8 M). Simulation therefore permits the prediction of the instantaneous concentration of reagents and products, in particular ethylene oxide concentration in the case of indirect alkylation, which must be as weak as possible. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 382–393, 2009
Rate constants for the gas‐phase β‐myrcene + OH and isoprene + OH reactions as a function of temperature
Authors: Hites Ronald A. , Turner Andrew M. 
Published: March 2009

AbstractRate constants for the gas‐phase reactions of the hydroxyl radical with the biogenic hydrocarbons, β‐myrcene and isoprene, were measured using the relative rate technique over the temperature range 313–413 K and at ∼1 atm total pressure. OH was produced by the photolysis of H2O2, and helium was the diluent gas. The reactants were detected by online mass spectrometry, which resulted in high time resolution allowing for large amounts of data to be collected and used in the determination of the Arrhenius parameters. Many experiments were performed over the temperature range of interest, leading to more accurate parameters than previous investigations. The following Arrhenius expression has been determined for these reactions (in units of cm3 molecule−1 s−1): for isoprene k = (3.14) × 10−11 exp [(338 ± 19)/T] and for β‐myrcene k = (9.19) × 10−12 exp[(1071 ± 82)/T]. The Arrhenius plot for the isoprene + OH reaction indicates curvature in this relationship and is given by k = (3.47 ± 0.14) × 10−17 T2 exp [(1036 ± 14)/T]. Our measured rate constant for the β‐myrcene + OH reaction at 298 K is higher, but not significantly, than current literature values. This is the first report of β‐myrcene's rate constant with OH as a function of temperature. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 407–413, 2009
Kinetics of catalytic esterification of propionic acid with different alcohols over Amberlyst 15
Authors: Ali Sami H. 
Published: March 2009

AbstractThe kinetics of the esterification reaction between propionic acid and methanol, ethanol, and 1‐butanol over the ion exchange resin, Amberlyst 15, was investigated. Experiments were conducted using a fixed‐bed plug flow reactor over the temperature range of 298–328 K. Acid to alcohol molar ratios of 3:1, 1:1, and 1:3 were employed. For each esterification system, the equilibrium conversion of propionic acid was found to increase with increasing reaction temperature. Several kinetic models were tested to correlate the collected data under kinetically controlled conditions; the pseudo‐homogeneous (P‐H), Eley–Rideal (E–R), Langmuir–Hinshelwood (L–H), and Pöpken (P‐P) models. In all cases, the activity coefficients were estimated using the UNIFAC model to account for the nonideal thermodynamic behavior of the reactants and products. The P‐P model was found to best represent the kinetic data of the investigated esterification systems with a total average error of less than 3%. The increase of alcohol chain length had a negative impact on the conversion of propionic acid due to steric hindrance. The activation energy of the esterification reaction is influenced by the chain length of the alcohol used. The adsorption equilibrium constants estimated by the P‐P model and the solubility parameters reported by AICHE DIPPER® followed the same trend; ester < acid < alcohol < water. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 432–448, 2009
Surface Area Effects in Hydroxyapatite/Poly(ε‐caprolactone) Nanocomposites
Authors: Kaur Jasmeet , Shofner Meisha L. 
Published: March 2009

AbstractIn order to understand the contribution of nanoparticle surface area to the properties of nanocomposite materials, hydroxyapatite nanoparticles with different specific surface areas (60 m2 · g−1 and 111 m2 · g−1) were synthesized using reverse microemulsion and processed into nanocomposites. Experimental results indicated that the thermomechanical reinforcement did show a dependence on nanoparticle surface area, although the transition temperatures did not. The reinforcement trends were dependent on temperature, suggesting that the nanoparticles had a greater impact on the amorphous polymer chains. The reinforcement above Tg may be plotted against nanoparticle surface area to obtain a single reinforcement trend, suggesting that surface area is a general parameter for nanocomposite property control.magnified image
Myocardial 3D strain calculation by combining cine displacement encoding with stimulated echoes (DENSE) and cine strain encoding (SENC) imaging
Authors: Hess Aaron T. , Zhong Xiaodong , Spottiswoode Bruce S. , Epstein Frederick H. , Meintjes Ernesta M. 
Published: March 2009

AbstractThree‐dimensional (3D) strain maps of the myocardium provide a coordinate‐system–independent quantification of myocardial deformation and kinematics. We combine two MRI techniques, displacement encoding with stimulated echoes (DENSE) and strain encoding (SENC), to fully formulate a 3D strain map in a single slice of myocardium. The method utilizes 2D DENSE in‐plane displacement measurements in two adjacent slices in conjunction with a single SENC through‐plane strain measure to calculate the 3D strain tensor. Six volunteers were imaged and the technique demonstrated 3D strain measures in all volunteers that are consistent with those reported in the literature from 3D tagging. The mean peak strain (± standard deviation [SD]) for six healthy volunteers for the first, second, and third principal strains are 0.42 ±0.11, –0.10 ±0.03, and –0.21 ±0.02, respectively. These results show that this technique is capable of reliably quantifying 3D cardiac strain. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Post hoc interpretation of urodynamic evaluation is qualitatively different than interpretation at the time of urodynamic study
Authors: Smith Phillip P. , Hurtado Eric A. , Appell Rodney A. 
Published: March 2009

AbstractObjectivesIntraobserver reliability of post hoc urodynamic interpretation is greater than interobserver reliability, attributable to interpreter bias. If post hoc interpretation is qualitatively similar to interpretation at the time of study by a urodynamicist in attendance (“live” interpretation), a similar intraobserver bias should be observed. We therefore evaluated the intra‐ and interobserver reliability of post hoc versus “live” interpretation.MethodsFifty‐five consecutive urodynamic studies administered by each of two urodynamicists and interpreted at the time of study were de‐identified and later re‐interpreted by the same two physicians. History and exam findings, cystometric tracing, uroflow summary and radiographs were available for interpretation. Intraobserver (post hoc vs. live), interobserver (post hoc vs. live) and interobserver (post hoc vs. post hoc) reliability was assessed by correlation coefficients for quantitative data, and Cohen's kappa statistic for categorical data.ResultsPost hoc versus live interpretations demonstrated no superiority of intraobserver reliability. For categorical observations, intraobserver reliability was best for urodynamic observations, but worse for clinical diagnosis (κ = 0.37) and primary treatment recommendation (κ = 0.26). Interobserver reliabilities were similar to intraobserver. Post hoc/post hoc interobserver correlations for quantitative data were good to very good, r2 = 0.611–0.914.ConclusionsIn contrast to previously reported post hoc/post hoc comparisons, post hoc/live comparison demonstrated no superiority of intraobserver reliability. Urodynamic observations and impressions are more reliable than are clinical diagnosis and therapeutic recommendation based upon urodynamic evaluation. Unrecorded and heuristic observations at the time of study as well as interpreter judgment may thus be determinants of diagnostic interpretation of urodynamic evaluation. Neurourol. Urodynam. 28:998–1002, 2009. © 2009 Wiley‐Liss, Inc.
A metabonomic approach to early prognostic evaluation of experimental sepsis by 1H NMR and pattern recognition
Authors: Lin Zhong‐ying , Xu Ping‐bo , Yan Shi‐kai , Meng Hai‐bing , Yang Gen‐jin , Dai Wei‐xing , Liu Xin‐ru , Li Jin‐bao , Deng Xiao‐ming , Zhang Wei‐dong 
Published: March 2009

AbstractThis study proposes an NMR‐based metabonomic approach to early prognostic evaluation of sepsis. Forty septic rats receiving cecal ligation and puncture (CLP) were divided into the surviving group and nonsurviving group on day 6, while 20 sham‐operated rats served as the control group. Serum samples were collected from septic and sham‐operated rats at 12 h after surgery and analyzed using 1H NMR spectroscopy. Orthogonal partial least squares (OPLS) were applied and showed clustering according to predefined groups, indicating that NMR‐based metabolic profiling could reveal pathologic characteristics in the serum of sham‐operated, surviving, and nonsurviving septic rats. In addition, six characteristic metabolites including lactate, alanine, acetate, acetoacetate, hydroxybutyrate, and formate, which are mainly involved in energy metabolism, changed markedly in septic rats, especially in the nonsurvivors. Using these metabolites, a predictive model for prognostic evaluation of sepsis was constructed using a radial basis function neural network (RBFNN) with a prediction accuracy of about 87% by test samples. The results indicated that the NMR‐based metabonomic approach is a potential technique for the early prognostic evaluation of sepsis. Copyright © 2009 John Wiley & Sons, Ltd.
1H HR‐MAS and genomic analysis of human tumor biopsies discriminate between high and low grade astrocytomas
Authors: Righi Valeria , Roda Jose M. , Paz José , Mucci Adele , Tugnoli Vitaliano , Rodriguez‐Tarduchy Gemma , Barrios Laura , Schenetti Luisa , Cerdán Sebastián , García‐Martín María L. 
Published: March 2009

AbstractWe investigate the profile of choline metabolites and the expression of the genes of the Kennedy pathway in biopsies of human gliomas (n = 23) using1H High Resolution Magic Angle Spinning (HR‐MAS, 11.7 Tesla, 277 K, 4000 Hz) and individual genetic assays.1H HR‐MAS spectra allowed the resolution and relative quantification by the LCModel of the resonances from choline (Cho), phosphocholine (PC) and glycerophosphorylcholine (GPC), the three main components of the combined tCho peak observed in gliomas byin vivo1H NMR spectroscopy. All glioma biopsies depicted a prominent tCho peak. However, the relative contributions of Cho, PC, and GPC to tCho were different for low and high grade gliomas. Whereas GPC is the main component in low grade gliomas, the high grade gliomas show a dominant contribution of PC. This circumstance allowed the discrimination of high and low grade gliomas by1H HR‐MAS, a result that could not be obtained using the tCho/Cr ratio commonly used byin vivo1H NMR spectroscopy. The expression of the genes involved in choline metabolism has been investigated in the same biopsies. High grade gliomas depict an upregulation of the β gene of choline kinase and phospholipase C, as well as a downregulation of the cytidyltransferase B gene, the balance of these being consistent with the accumulation of PC. In the low grade gliomas, phospholipase A1and lysophospholypase are upregulated and phospholipase D is downregulated, supporting the accumulation of GPC. The present findings offer a promising procedure that will potentially help to accurately grade glioma tumors using1H HR‐MAS, providing in addition the genetic background for the alterations of choline metabolism observed in high and low grade gliomas. Copyright © 2009 John Wiley & Sons, Ltd.
Multislice multiecho T2* cardiac magnetic resonance for the detection of heterogeneous myocardial iron distribution in thalassaemia patients
Authors: Positano Vincenzo , Pepe Alessia , Santarelli Maria Filomena , Ramazzotti Anna , Meloni Antonella , De Marchi Daniele , Favilli Brunella , Cracolici Eliana , Midiri Massimo , Spasiano Anna , Lombardi Massimo , Landini Luigi 
Published: March 2009

AbstractThe present study investigated myocardial T2* heterogeneity in thalassaemia major (TM) patients by cardiac magnetic resonance (CMR), to determine whether is related to inhomogeneous iron overload distribution. A total of 230 TM patients consecutively referred to our laboratory were studied retrospectively. Three short‐axis views (basal, medium and apical) of the left ventricle (LV) were obtained by multislice multiecho T2* CMR. T2* segmental distribution was mapped on a 16‐segment LV model. The level of heterogeneity of the T2* segmental distribution, evaluated by the coefficient of variation (CoV), was compared with that of a surrogate data set, to determine whether the inhomogeneous segmental distribution of T2* could be generated by susceptibility artefacts. Susceptibility artefacts offer an explanation for the T2* heterogeneity observed in patients without iron overload. In subjects with global T2* below the lower limit of the normal, T2* heterogeneity increased abruptly which could not be explained by artefactual effects. Some segmental T2* values were below and others above the limit of normal threshold (20 ms) in 104 (45%) TM patients. Among these patients, 74% showed a normal T2* global value. In conclusion, a true heterogeneity in the iron overload distribution may be present in TM patients. Heterogeneity seemingly appears in the borderline myocardial iron and stabilizes at moderate to severe iron burden. Copyright © 2009 John Wiley & Sons, Ltd.
In ovo non‐invasive quantification of the myocardial function and mass of chick embryos using magnetic resonance imaging
Authors: Holmes William M. , McCabe Christopher , Mullin Jim M. , Condon Barrie , Bain Maureen M. 
Published: March 2009

AbstractMagnetic resonance imaging (MRI) has evolved as one of the major non‐invasive tools to study healthy and diseased hearts in animal models, especially rodent models. Even though, the chick embryo has long been used as a model for cardiovascular research, MRI has not yet been used for in vivo cardiac studies. Part of the reason for this is the difficulty in monitoring the ECG and respiration of the chick embryo in the magnet for gating purposes. To overcome this complication, this paper presents the use of retrospective Cine MRI to measure the cardiac function of chick embryos in ovo for the first time, without the need for respiratory or cardiac gating. The resulting left ventricular functional parameters, from six chick embryos at 20 days of incubation, were (mean ± SD) EDV 69 ± 15 µL, ESV 31 ± 7 µL, SV 38 ± 9 µL and EF 54.5 ± 2%. The use of retrospective Cine MRI at earlier stages of development is also discussed and difficulties have been highlighted. Copyright © 2009 John Wiley & Sons, Ltd.
Polyimide molecular composites containing a stiff‐chain polymer derived from 1,5‐diaminonaphathalene and pyromellitic dianhydride
Authors: Khalil Muhammad , Ha Chang‐Sik , Saeed Shaukat , Khan Irum Majeed , Ahmad Zahoor 
Published: March 2009

AbstractPolyimide molecular composite (MC) films were prepared by embedding a stiff‐chain polyimide (PIS) in the ductile matrix of a flexible‐chain polyimide (PIF) by blending their respective poly(amic acid) precursor solutions, followed by casting, drying, and thermal imidization upto 300°C. The PIS was prepared from pyromellitic dianhydride (PMDA) and 1,5‐diaminonaphathalene (DAN), whereas the PIF was prepared from the same dianhydride and 4,4′‐oxydianiline (ODA). Transparent, tough, and creasable MC films were obtained with 2.5–40 wt% of PIS content. The disruption of crystalline order of PIS in the MC films evidenced its fine dispersion in the matrix. Visco‐elastic measurements showed a single and enhanced value of the glass transition temperature for MC films indicating miscibility of this polyimide pair. Furthermore, the variation of charge transfer (CT) fluorescence intensity with the PIS content in the blends verified complete miscibility upto 30 wt% of PIS loading. These MCs showed a notable enhancement in the mechanical properties. Among all, the blend containing 30 wt% of stiff‐chain molecules gave the best combination of properties when compared with the matrix polyimide: a 50% higher value of tensile modulus, a 17°C rise in the glass transition temperature, and better thermal stability. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Consolidation of net‐shape random fiber thermoplastic composite preforms
Authors: Jespersen S.T. , Baudry F. , Wakeman M.D. , Michaud V. , Blanchard P. , Norris R. , Månson J‐A.E. 
Published: March 2009

AbstractA novel thermoplastic composite preforming process has been developed. This thermoplastic programmable powdered preforming process (TP‐P4) uses commingled glass and polypropylene yarns, which are chopped to a desired length and deposited onto a vacuum screen. The as‐placed fibers are then heat‐set for improved handling, before potential preconsolidation, and final conversion with preheating and press forming. This work investigated the effect of using either a double belt lamination preconsolidation stage or using an improved heat‐setting stage. Polymer degradation was examined using gel permeation chromatography analysis, and the void content evolution tracked using image analysis techniques from the heat setting stage until the final part. It was shown that without preconsolidation, preforms prepared for a 2 mm thick final pressed part could be compression molded into a substantially void free, non degraded part. By using the lamination route, this limit could be increased to 4 mm, but without allowing local thickness changes in the preform. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Fatigue characterization and reliability analysis of wood flour filled polypropylene composites
Authors: Yang Han‐Seung , Qiao Pizhong , Wolcott Michael P. 
Published: March 2009

AbstractIn this article, the flexural fatigue behavior of wood flour filled polypropylene (PP) composite samples was investigated, and a probabilistic approach is presented to evaluate the fatigue reliability. A nondimensional analysis was adopted to establish a prediction equation for the fatigue life of the composites, and the S‐N curves and survivability diagrams are then constructed to evaluate the fatigue reliability for the wood plastic composites. The predicted results in the nondimensional fatigue model are better related to the testing data than the general S‐N curve, and they could be used as the predictive model for fatigue life analysis of the wood plastic composites. The best‐fit S‐N curve and its corresponding bounds based on 95% confidence are provided, and the fatigue data are well distributed within a 95% confidence range. A two‐parameter Weibull distribution function is used to analyze statistically the fatigue life test results of composite samples based on the probability of survival concept which is proposed to incorporate the probability of survival and the fatigue life time of the composites at a specified lifetime. Weibull graphics are plotted for the composite samples used in the fatigue test, and the S‐N curves are then drawn for different reliability index (RI) of 0.01, 0.1, 0.5, 0.9, 0.99, and 0.368 using these data. These S‐N curves are introduced for the identification of the first failure time as reliability and safety limits. It is shown that the nondimensional fatigue model and two‐parameter probability distribution model can be used successfully for reliability evaluation and lifetime estimation of wood plastic composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Proteomics analysis of BHK‐21 cells infected with a fixed strain of rabies virus
Authors: Zandi Fatemeh , Eslami Naser , Soheili Masoomeh , Fayaz Ahmad , Gholami Alireza , Vaziri Behrouz 
Published: March 2009

AbstractRabies is a neurotropic virus that causes a life threatening acute viral encephalitis. The complex relationship of rabies virus (RV) with the host leads to its replication and spreading toward the neural network, where viral pathogenic effects appeared as neuronal dysfunction. In order to better understand the molecular basis of this relationship, a proteomics study on baby hamster kidney cells infected with challenge virus standard strain of RV was performed. This cell line is an in vitro model for rabies infection and is commonly used for viral seed preparation. The direct effect of the virus on cellular protein machinery was investigated by 2‐DE proteome mapping of infected versus control cells followed by LC‐MS/MS identification. This analysis revealed significant changes in expression of 14 proteins, seven of these proteins were viral and the remaining were host proteins with different known functions: cytoskeletal (capping protein, vimentin), anti‐oxidative stress (superoxide dismutase), regulatory (Stathmin), and protein synthesis (P0). Despite of limited changes appeared upon rabies infection, they present a set of interesting biochemical pathways for further investigation on viral‐host interaction.