bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of primaquine and its metabolite carboxyprimaquine in biological samples: enantiomeric separation, method validation and quantification
Authors: Avula Bharathi , Khan Shabana I. , Tekwani Babu L. , Dhammika Nanayakkara N.P. , McChesney James D. , Walker Larry A. , Khan Ikhlas A. 
Published: November 2010

AbstractThe clinical formulation of primaquine (PQ) is a mixture of (−)‐(R)‐ and (+)‐(S)‐ primaquine enantiomers which may show different pharmacokinetic and pharmacodynamic properties. To assess the efficacy and toxicity of primaquine enantiomers, a method using LC‐MSD‐TOF has been developed. The enantiomers were well separated using a Chiralcel OD column (250 × 4.6 mm, 10 µm) with a linear gradient of mobile phase consisting of acetonitrile (0.1% formic acid) and aqueous ammonium formate (20 mm; 0.1% formic acid) adjusted to pH 5.9 at a flow rate of 0.7 mL/min. The method was validated for linearity, precision, accuracy and limits of detection and quantification. The calibration curves were linear with all correlation coefficients being >0.999. The average recoveries of (−)‐(R)‐ and (+)‐(S)‐primaquine and (−)‐(R)‐ and (+)‐(S)‐carboxyprimaquine were 88 and 92%, respectively, in spiked human plasma and 89 and 93% respectively in spiked mouse plasma samples. The RSD of (−)‐(R)‐ and (+)‐(S)‐primaquine and (−)‐(R)‐ and (+)‐(S)‐carboxyprimaquine were 2.15, 1.74, 1.73 and 2.31, respectively, in spiked human plasma and 2.21, 1.09, 1.95 and 1.17% in spiked mouse plasma, respectively. The intra‐day and inter‐day precisions expressed as RSD were lower than 10% in all analyzed quality control levels. The method as reported is suitable for study of the pharmacokinetic and pharmacodynamic properties of the enantiomers of primaquine. The method was successfully applied to study plasma pharmacokinetic profile of enantiomers of primaquine and carboxyprimaquine in mice administered with primaquine in racemic form. The analytical method was found to be linear, accurate, precise and specific. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of phenolic monomers on growth of Acidothermus cellulolyticus
Authors: Joh Lawrence D. , Rezaei Farzaneh , Barabote Ravi D. , Parales Juanito V. , Parales Rebecca E. , Berry Alison M. , VanderGheynst Jean S. 
Published: November 2010

AbstractPrevious studies on biological pretreatment of switchgrass by solid‐state fermentation with Acidothermus cellulolyticus 11B have shown that inhibitory compounds prevent growth on untreated switchgrass. A. cellulolyticus was grown in liquid medium containing cellobiose with phenolic monomers added to determine if the phenolic compounds are one possible source of inhibition. Cinnamic acid derivatives (trans‐p‐coumaric, trans‐ferulic, and hydrocinnamic acids), hydroxybenzoic acids (p‐hydroxybenzoic, syringic, and vanillic acids), benzaldehydes (vanillin and p‐hydroxybenzaldehyde), and condensed tannin monomers (catechin and epicatechin) were tested at levels up to 20 mM. All compounds exhibited a dose‐response relationship and strongly inhibited growth at 20 mM. trans‐p‐Coumaric acid was found to be the strongest inhibitor of A. cellulolyticus growth, with a specific growth rate of 0.004 h−1 at 1 mM (0.18 h−1 without phenolic monomer). GC‐MS and HPLC methods were used to confirm the presence of these phenolic compounds in switchgrass and measure the amounts extracted using different conditions. The amounts of phenolic compounds measured were found to be higher than the threshold for growth inhibition. Leaching with water at 55°C was inefficient at removing bound phenolics, whereas NaOH treatment improved efficiency. Phenolic compounds spiked into alkaline pretreated switchgrass were also found to inhibit growth of A. cellulolyticus in solid‐state fermentation. However, addition of insoluble polyvinylpolypyrrolidone (PVPP) to switchgrass improved growth of A. cellulolyticus in liquid cultures, providing a possible approach for alleviating microbial inhibition due to phenolic compounds in lignocellulose. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Enhanced Functionality for Donor–Acceptor Oligothiophenes by means of Inclusion of BODIPY: Synthesis, Electrochemistry, Photophysics, and Model Chemistry
Authors: Collado Daniel , Casado Juan , González Sandra Rodríguez , Navarrete Juan T. López , Suau Rafael , Perez‐Inestrosa Ezequiel , Pappenfus Ted. M. , Raposo M. Manuela M. 
Published: November 2010

AbstractWe have synthesized several new push–pull oligothiophenes based on the boron dipyrromethene (BODIPY) moiety as the electron acceptor and the more well‐known oligothiophenes substituted with N,N‐dialkylamino functions to enhance their electron‐donor ability. A complete characterization of the electronic properties has been carried out; it consists of their photophysical, electrochemical, and vibrational properties. The compounds have been studied after chemical treatment with acids and after oxidation. In this regard, they can be termed as NIR dyes and amphoteric redox electroactive molecules. We have described the presence of dual fluorescence in these molecules and fluorescence quenching either by energy transfer or, in the push–pull molecules, by electron exchange. The combination of electrochemical and proton reversibility along with the interesting optical properties of the new species offer an interesting platform for sensor and material applications.
Geometrically Specific Imino Complexes of the [Re6(μ3‐Se)8]2+ Core‐Containing Clusters
Authors: Tu Xiaoyan , Truong Huong , Alster Eli , Muñoz‐Castro Alvaro , Arratia‐Pérez Ramiro , Nichol Gary S. , Zheng Zhiping 
Published: November 2010

AbstractThe reactions of nitrile complexes of the [Re6(μ3‐Se)8]2+ core‐containing clusters, [Re6(μ3‐Se)8(PEt3)n(CH3CN)6−n]2+ [n=5 (1); n=4, cis‐ (2) and trans‐ (3); n=0 (4)], with organic azides C6H5CH(CH3)N3 and C6H5CH2N3 produced the corresponding cationic imino complexes of the general formula [Re6(μ3‐Se)8(PEt3)n(L)6−n]2+ [L=PhNCHCH3: n=5 (5); n=4, cis‐ (6) and trans‐ (7); n=0 (8) and L=HNCHPh: n=5 (9); n=4, cis‐ (10) and trans‐ (11)]. These novel complexes were characterized by NMR spectroscopy (1H and 31P) and single‐crystal X‐ray diffraction. A mechanism involving the migration of one of the groups on the azido α‐C atom to the α‐N atom of the azido complex, concerted with the photo‐expulsion of N2, was invoked to rationalize the formation of the imino complexes. Density functional theory (DFT) calculations indicated that due to the coordination with and activation by the cluster core, the energy of the electronic transition responsible for the photo‐decomposition of a cluster‐bound azide is much reduced with respect to its pure organic counterpart. The observed geometric specificity was rationalized by using the calculated and optimized preferred ground‐state conformation of the cluster‐azido intermediates.
Breakup of drops around the edges of Rushton turbine
Authors: Patil Pramod , Kumar Sanjeev 
Published: November 2010

AbstractA detailed experimental and simulation study has been carried out in the present work to understand drop breakup in regions around the edge of the Rushton turbine in agitated vessels. The effect of impeller speed, impeller size, interfacial tension, and the viscosities of the two phases is studied on drop breakup through their effect on dmax, the size of the largest drop in the system, and the whole size distribution. The measurements were carried out using Galai particle size analyser and optical microscope. Experimental analysis shows that the dmax, maximum stable drop diameter varies with impeller tip velocity to the power −1. The variation of dmax with interfacial tension is studied using different surfactants. The effect of viscosity ratio, achieved by changing the dispersed phase viscosity, on dmax is captured. For the same dmax values obtained from two different dispersed phases show that the wider drop size distribution is observed for higher dispersed phase viscosity.Une étude expérimentale et de simulation détaillée a été réalisée dans ce travail dans le but de comprendre la rupture de gouttes dans les zones près de l'extrémité de la turbine Rushton dans des cuves agitées. L'effet de la vitesse de l'impulseur, de la taille de l'impulseur, de la tension interfaciale et des viscosités des deux phases est étudié sur la rupture de gouttes par leur effet sur le diamètre de goutte stable maximal, la taille de la plus grosse goutte du système et la distribution pour toute la taille. Les mesures ont été effectuées à l'aide d'un analyseur granulométrique Galai et d'un microscope optique. Une analyse expérimentale démontre que le diamètre de goutte stable maximal varie avec une vélocité du bout de l'impulseur à la puissance ‐1. La variation du diamètre de goutte stable maximal avec la tension interfaciale est étudiée à l'aide de différents surfactifs. L'effet de viscosité relative, atteint en changeant la viscosité de phase dispersée, sur le diamètre de goutte stable maximal est capté. Les mêmes valeurs de diamètre de goutte stable maximal obtenues de deux phases dispersées différentes indiquent que la distribution des plus grosses gouttes est observée pour la viscosité de phase dispersée supérieure. Can. J. Chem. Eng. © 2010 Canadian Society for Chemical Engineering
Thermodynamic, kinetic, and equilibrium studies on phenol removal by use of cashew nut shell
Authors: Senthil Kumar P. , Ramakrishnan K. , Dinesh Kirupha S. , Sivanesan S. 
Published: November 2010

AbstractAdsorption of phenol from aqueous solution onto cashew nut shell (CNS) was investigated to assess the possible use of this adsorbent. The influence of various parameters such as contact time, phenol concentration, adsorbent dose, pH, and temperature has been studied. Studies showed that the pH of aqueous solutions affected phenol removal as a result of decrease in removal efficiency with increasing solution pH. The experimental data were analysed by the Langmuir equation. Equilibrium data fitted well with the Langmuir model with maximum monolayer adsorption capacity of 5.405 mg/g. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° have also been evaluated and it has been found that the sorption process was feasible, spontaneous, and exothermic in nature. The pseudo‐first‐order and pseudo‐second‐order kinetic models were selected to follow the adsorption process. Kinetic parameters, rate constants, equilibrium sorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the adsorption of phenol could be described by the pseudo‐second‐order equation, suggesting that the adsorption process is presumable a chemisorption. The CNS investigated in this study showed good application potential for the removal of phenol from aqueous solution.
Study of cyclic operation of RO desalination process
Authors: Ali M. Al‐haj , Ajbar A. , Ali E. , Alhumaizi K. 
Published: November 2010

AbstractThe performance of a tubular reverse osmosis (RO) process for water desalination was investigated when the unit was periodically forced. The study was performed using a dynamic model that was developed and validated in a previous work of the authors [Al‐haj Ali et al., Desalination; 245, 194–204 (2009)]. The forcing was carried out through feed pressure using both symmetric and asymmetric rectangular pulses. For a symmetric pulse, it was found that the permeate flow rate increased monotonically with the forcing amplitude. The improvement in the permeate flow rate was limited by the constraints on the operating pressure. For an asymmetric pressure pulse, the permeate flow rate reached a clear maximum for some values of ratio of pulse width to the period. For both pulses, the model predicted that the enhancement in the permeate flow rate was attributed to the reduction in the effect of concentration polarisation. Moreover, the trends obtained with both symmetric and asymmetric shapes were consistent with the experimental results reported in the literature.
Acute hypoxia and exercise improve insulin sensitivity (SI2*) in individuals with type 2 diabetes
Authors: Mackenzie Richard , Maxwell Neil , Castle Paul , Brickley Gary , Watt Peter 
Published: November 2010

AbstractBackgroundHypoxia has been shown to increase glucose uptake in skeletal muscle using the contraction‐stimulated pathway, independent of the actions of insulin. Yet, the same stress has also been linked with causing insulin resistance and hyperglycaemia. The aim of this study was to examine the effects of acute hypoxia with and without exercise on insulin sensitivity ($S{_{{\rm I}}}^{2*}$) in individuals with type 2 diabetes.MethodsEight type 2 diabetic patients completed 60 min of the following: (1) normoxic rest; (2) hypoxic rest [O2 = 14.6 (0.4)%]; (3) normoxic exercise and (4) hypoxic exercise [O2 = 14.6 (0.4)%]. Exercise trials were set at 90% of lactate threshold. Each condition was followed by a labelled intravenous glucose tolerance test to provide estimations of insulin sensitivity ($S{_{{\rm I}}}^{2*}$) and β‐cell function.ResultsTwo‐compartmental analysis showed that insulin sensitivity ($S{_{{\rm I}}}^{2*}$) was higher following hypoxic rest compared with normoxic rest (p = 0.047). Insulin sensitivity ($S{_{{\rm I}}}^{2*}$) was also higher following hypoxic exercise [4.37 (0.48) × 10−4/min (µU/mL)] compared with normoxic exercise [3.24 (0.51) × 10−4/min (µU/mL)] (p = 0.048). Acute insulin response to glucose was reduced following hypoxic rest versus normoxic rest (p = 0.014).ConclusionsThis study demonstrated that (1) hypoxic‐induced improvements in glucose tolerance in the 4 h following exposure can be attributed to improvements in peripheral insulin sensitivity ($S{_{{\rm I}}}^{2*}$) and (2) exercise and hypoxia have an additive effect on insulin sensitivity ($S{_{{\rm I}}}^{2*}$) in type 2 diabetic patients. Acute hypoxia may therefore improve short‐term glycaemic control in individuals with type 2 diabetes. The application of these findings in the clinic will require further investigation. Copyright © 2010 John Wiley & Sons, Ltd.
Design of Tri‐Substituted Dodecatungstosilicate from a Trilacunary Silicotungstate by Insertion of Manganese Ions of [Mn3(μ3‐O)(2‐Cl‐benzoato)6(py)3]: Synthesis, Structure, Redox and Magnetic Studies
Authors: Dutta Daipayan , Jana Atish D. , Debnath Mainak , Mostafa Golam , Clérac Rodolphe , Tojal Javier G. , Ali Mahammad 
Published: November 2010

AbstractA mixed‐valent manganese tricapped Keggin polyoxometalate (3) has been designed by insertion of three Mn atoms from [MnIIMnIII2(μ3‐O)(2‐Cl‐benzoato)6(py)3] (1) into the vacant sites of the trilacunary precursor Na10[A‐α‐SiW9O34] (2). This compound exhibits strong antiferromagnetic interaction between the spin carriers of the Mn mixed‐valent trinuclear moiety, which suggests an S = 5/2 ground state.
Monitoring cyclic acyloxonium ion formation in palmitin systems using infrared spectroscopy and isotope labelling technique
Authors: Rahn Anja Katerina Karin , Yaylayan Varoujan Antranik 
Published: November 2010

AbstractTo confirm the possible involvement of acyloxonium ions as reactive intermediates in food related lipids, their formation was monitored in triplamitin, 1,2 dipalmitin, 1‐monopalmitin and specifically labelled tripalmitin (1,1,1‐13C3) using Fourier‐transform IR spectroscopy (FTIR). Reactions were conducted at 100°C using a mixture of ZnCl2 and the lipids. When tripalmitin or 1,2‐dipalmitin samples were heated at 100°C in the presence of ZnCl2 a new band centred at 1651 cm−1 was formed and increased over time. When 13C‐labelled tripalmitin (1,1,1‐13C3) was studied the spectrum exhibited an expected 40 cm−1 shift from 1651 to 1611cm−1 indicating the involvement of the carbonyl carbon in the formation of the band. The 1‐monopalmitin generated a similar but weaker band at higher temperatures and requiring longer times. These observations may indicate that under hydrophobic environment acyloxonium ions are preferentially formed with neighbouring ester groups assisted by the catalytic action of a free hydroxyl group serving as a proton transfer site. In the absence of such a free hydroxyl group tripalmitin undergoes acyloxonium ion formation at a slower rate than 1,2‐dipalmitoyl glycerol, whereas, 1‐monopalmitoyl glycerol due to the absence of a neighbouring ester shows even slower transformation efficiencies. This order of reactivity may however change in the presence of water.
Methodological aspects of spectrum occupancy evaluation in the context of cognitive radio
Authors: López‐Benítez Miguel , Casadevall Fernando 
Published: November 2010

AbstractCognitive radio has recently emerged as a promising solution to conciliate the existing conflicts between spectrum demand growth and spectrum underutilisation. The basic underlying idea is to allow unlicensed users to access in an opportunistic and non‐interfering manner some licensed bands temporarily unoccupied by the licensed users. Within the framework of cognitive radio, several spectrum measurement campaigns have been performed in diverse locations and scenarios in order to assess the degree to which allocated spectrum bands are currently being used in real wireless communication systems. Although such measurement campaigns follow similar approaches, there is a lack of common and appropriate evaluation methodology, which would be desirable not only to prevent inaccurate results but also to enable the direct comparison of results from different sources. In this context, this work presents a comprehensive and in‐depth discussion of several important methodological aspects that need to be accounted for when evaluating spectrum occupancy in the context of cognitive radio. Moreover, a quantitative evaluation of the impact of different factors on the obtained results along with various useful guidelines is also provided. The results presented in this work highlight the importance of carefully designing an appropriate methodology when evaluating spectrum occupancy in the context of cognitive radio. Copyright © 2010 John Wiley & Sons, Ltd.
Studies on the metabolism of the α‐pyrrolidinophenone designer drug methylenedioxy‐pyrovalerone (MDPV) in rat and human urine and human liver microsomes using GC–MS and LC–high‐resolution MS and its detectability in urine by GC–MS
Authors: Meyer Markus R. , Du Peng , Schuster Frank , Maurer Hans H. 
Published: November 2010

AbstractSince the late 1990s, many derivatives of the α‐pyrrolidinophenone (PPP) drug class appeared on the drugs of abuse market. The latest compound was described in 2009 to be a classic PPP carrying a methylenedioxy moiety remembering the classic entactogens (ecstasy). Besides Germany, 3,4‐methylene‐dioxypyrovalerone (MDPV) has appeared in many countries in Europe and Asia, indicating its worldwide importance for forensic and clinical toxicology. The aim of the presented work was to identify the phase I and II metabolites of MDPV and the human cytochrome‐P450 (CYP) isoenzymes responsible for its main metabolic step(s). Finally, the detectability of MDPV in urine by the authors' systematic toxicological analysis (STA) should be studied. The urine samples were extracted after and without enzymatic cleavage of conjugates. The metabolites were separated and identified after work‐up by GC–MS and liquid chromatography (LC)–high‐resolution MS (LC–HR‐MS). The studies revealed the following phase I main metabolic steps in rat and human: demethylenation followed by methylation, aromatic and side chain hydroxylation and oxidation of the pyrrolidine ring to the corresponding lactam as well as ring opening to the corresponding carboxylic acid. Using LC–HR‐MS, most metabolite structures postulated according to GC–MS fragmentation could be confirmed and the phase II metabolites were identified. Finally, the formation of the initial metabolite demethylenyl‐MDPV could be confirmed using incubation of human liver microsomes. Using recombinant human CYPs, CYP 2C19, CYP 2D6 and CYP 1A2 were found to catalyze this initial step. Finally, the STA allowed the detection of MDPV metabolites in the human urine samples. Copyright © 2010 John Wiley & Sons, Ltd.
Characterization of Nα‐Fmoc‐protected ureidopeptides by electrospray ionization tandem mass spectrometry (ESI‐MS/MS): differentiation of positional isomers
Authors: Ramesh M. , Raju B. , Srinivas R. , Sureshbabu V. V. , Narendra N. , Vasantha B. 
Published: November 2010

AbstractFour pairs of positional isomers of ureidopeptides, FmocNH‐CH(R1)‐φ(NH‐CO‐NH)‐CH(R2)‐OY and FmocNH‐CH(R2)‐φ(NH‐CO‐NH)‐CH(R1)‐OY (Fmoc = [(9‐fluorenyl methyl)oxy]carbonyl; R1 = H, alkyl; R2 = alkyl, H and Y = CH3/H), have been characterized and differentiated by both positive and negative ion electrospray ionization (ESI) ion‐trap tandem mass spectrometry (MS/MS). The major fragmentation noticed in MS/MS of all these compounds is due to NCH(R)Nbond cleavage to form the characteristic N‐ and C‐terminus fragment ions. The protonated ureidopeptide acids derived from glycine at the N‐terminus form protonated (9H‐fluoren‐9‐yl)methyl carbamate ion at m/z 240 which is absent for the corresponding esters. Another interesting fragmentation noticed in ureidopeptides derived from glycine at the N‐terminus is an unusual loss of 61 units from an intermediate fragment ion FmocNH = CH2+ (m/z 252). A mechanism involving an ion‐neutral complex and a direct loss of NH3 and CO2 is proposed for this process. Whereas ureidopeptides derived from alanine, leucine and phenylalanine at the N‐terminus eliminate CO2 followed by corresponding imine to form (9H‐fluoren‐9‐yl)methyl cation (C14H11+) from FmocNH = CHR+. In addition, characteristic immonium ions are also observed. The deprotonated ureidopeptide acids dissociate differently from the protonated ureidopeptides. The [M − H]− ions of ureidopeptide acids undergo a McLafferty‐type rearrangement followed by the loss of CO2 to form an abundant [M − H − Fmoc + H]− which is absent for protonated ureidopeptides. Thus, the present study provides information on mass spectral characterization of ureidopeptides and distinguishes the positional isomers. Copyright © 2010 John Wiley & Sons, Ltd.
Rocking vibration of a rigid circular disc in a transversely isotropic full‐space
Authors: Eskandari‐Ghadi Morteza , Mirzapour Ammar , Ardeshir‐Behrestaghi Azizollah 
Published: November 2010

AbstractIn this paper, forced rocking vibration of a rigid circular disc placed in a transversely isotropic full‐space, where the axis of material symmetry of the full‐space is normal to the surface of the plate, is analytically investigated. Because of using the Fourier series and Hankel integral transforms, the mixed boundary‐value problem is transformed into two separate pairs of integral equations called dual integral equations. The dual integral equations involved in this paper are reduced to Fredholm integral equations of the second kind. With the aid of contour integration, the governing integral equation is numerically evaluated in the general dynamic case. The reduced static case of the dual integral equations is solved analytically and the vertical displacement, the contact pressure and the static impedance/compliance function are explicitly determined, and it is shown that the pressure in between the plate and the full‐space and the compliance function reduced for isotropic half‐space are identical to the previously published solutions. The dynamic contact pressure in between the disc and the space and also the related impedance function are numerically evaluated in general dynamic case and illustrated. It is shown that the singularity exists in the contact pressure at the edge of the disc is the same as the static case. To show the effect of material anisotropy, the numerical evaluations are given for some different transversely isotropic materials and compared. Copyright © 2010 John Wiley & Sons, Ltd.