bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of homogeneous rate constants of reaction of electrochemically generated ortho‐benzoquinones with 1,3‐indandione
Authors: Nematollahi Davood , Ardakani Mohammad Mazloum , Shekarlab Nastaran 
Published: September 2007

AbstractElectrochemical oxidation of some catechol derivatives has been studied in the presence of 1,3‐indandione as nucleophile in aqueous solution, by means of cyclic voltammetry and controlled‐potential coulometry. The results indicate the participation of electrochemically produced o‐benzoquinones in the Michael reaction with 1,3‐indandione to form the corresponding new catechol derivatives. On the basis of the EC mechanism, the observed homogeneous rate constants (kobs) of reaction of produced o‐benzoquinones with 3‐indandione were estimated by comparing the experimental cyclic voltammograms with the digitally simulated results. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 605–613, 2007
Kinetics of OH radical reaction with phenanthrene: New absolute rate measurements and comparison with other PAHs
Authors: Ananthula Rajeshwar , Yamada Takahiro , Taylor Philip H. 
Published: September 2007

AbstractUsing an in situ pulsed laser photolysis/pulsed laser‐induced fluorescence/technique, the OH reaction kinetics of a three‐ring polycyclic aromatic hydrocarbon (PAH), phenanthrene (and its deuterated form), was investigated over the temperature range of 373–1000 K. This study represents the first examination of the OH kinetics for phenanthrene at elevated temperatures using the absolute rate technique. The phenanthrene results indicate a temperature dependence similar to its isomer anthracene, reported previously in R. Ananthula, T. Yamada, and P. H. Taylor, J Phys Chem A 2006, 100, 3559–3566, over a similar temperature range. The phenanthrene rate constants are similar to anthracene at high temperature (ca. 1000 K) and a factor of ca. 2 lower at low temperatures (373–700 K). The rate measurements were best fitted by the following two‐parameter expression of the form ATn: k1(373–1000 K) = 4.98 ± 2.96 × 10−6 * T−1.97±0.10 (in units of cm3 molecule−1 s−1, error limits ±1σ). Rate measurements with deuterated phenanthrene below 725 K were indistinguishable from the phenanthrene rate measurements, within random error limits, providing strong evidence for an OH‐addition mechanism. The effects of PAH size on their reactivity with OH radicals based on selected data over the temperature range of 243–1200 K are discussed. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 629–637, 2007
Kinetics of the alkaline hydrolysis of fenuron in aqueous and micellar media
Authors: Gangwar S. K. , Rafiquee M. Z. A. 
Published: September 2007

AbstractThe kinetics of the hydrolysis of fenuron in sodium hydroxide has been investigated spectrometrically in an aqueous medium and in cationic micelles of cetyltrimethylammonium bromide (CTAB) medium. The reaction follows first‐order kinetics with respect to [fenuron] in both the aqueous and micellar media. The rate of hydrolysis increases with the increase in [NaOH] in the lower concentration range but shows a leveling behavior at higher concentrations. The reaction followed the rate equation, 1/kobs = 1/k + 1/(kK[OH−]), where kobs is the observed rate constant, k is rate constant in aqueous medium, and k is the equilibrium constant for the formation of hydroxide addition product. The cationic CTAB micelles enhanced the rate of hydrolytic reaction. In both aqueous and micellar pseudophases, the hydrolysis of fenuron presumably occurs via an addition–elimination mechanism in which an intermediate hydroxide addition complex is formed. The added salts decrease the rate of reaction. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 638–644, 2007
Liquid chromatography combined with mass spectrometry for 13C isotopic analysis in life science research
Authors: Godin Jean‐Philippe , Fay Laurent‐Bernard , Hopfgartner Gérard 
Published: September 2007

AbstractAmong the different disciplines covered by mass spectrometry, measurement of 13C/12C isotopic ratio crosses a large section of disciplines from a tool revealing the origin of compounds to more recent approaches such as metabolomics and proteomics. Isotope ratio mass spectrometry (IRMS) and molecular mass spectrometry (MS) are the two most mature techniques for 13C isotopic analysis of compounds, respectively, for high and low‐isotopic precision. For the sample introduction, the coupling of gas chromatography (GC) to either IRMS or MS is state of the art technique for targeted isotopic analysis of volatile analytes. However, liquid chromatography (LC) also needs to be considered as a tool for the sample introduction into IRMS or MS for 13C isotopic analyses of non‐volatile analytes at natural abundance as well as for 13C‐labeled compounds. This review presents the past and the current processes used to perform 13C isotopic analysis in combination with LC. It gives particular attention to the combination of LC with IRMS which started in the 1990's with the moving wire transport, then subsequently moved to the chemical reaction interface (CRI) and was made commercially available in 2004 with the wet chemical oxidation interface (LC‐IRMS). The LC‐IRMS method development is also discussed in this review, including the possible approaches for increasing selectivity and efficiency, for example, using a 100% aqueous mobile phase for the LC separation. In addition, applications for measuring 13C isotopic enrichments using atmospheric pressure LC‐MS instruments with a quadrupole, a time‐of‐flight, and an ion trap analyzer are also discussed as well as a LC‐ICPMS using a prototype instrument with two quadrupoles. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:751–774, 2007
Preparation and Characterization of pH‐Sensitive Microgels of Poly((2‐dimethylamino) ethyl methacrylate)
Authors: Emileh Ali , Vasheghani‐Farahani Ebrahim , Imani Mohammad 
Published: September 2007

AbstractSummary: pH‐sensitive microgels of poly((2‐dimethylamino) ethyl methacrylate) (PDMAEMA) were prepared by dispersion polymerization of 2‐dimethylamino ethyl methacrylate in a mixed solvent of water/ethanol. 1HNMR, FTIR and SEM were used to confirm the chemical structure and morphological properties of the resulting microgels. Dynamic Light Scattering (DLS) was used to measure the hydrodynamic diameter of the particles. SEM micrographs showed that the microgel particles have a diameter of about 100–200 nm in dry state. Mean hydrodynamic diameter of the particles at their collapsed state at pH = 9.5 was found to be about 150 nm. DLS measurements at various pH values showed that the prepared microgels have a volume phase transition around pH = 8 at which the hydrodynamic diameter decreased from about 470 nm to around 150 nm corresponding to a 32 fold change in the mean volume of a microgel particle.
Preparation of Magnetite‐Polystyrene Core‐Shell Hybrid Nanoparticles, Initiated by a Covalently Bonded Azo Compound
Authors: Hartmann Patrice C. , Sanderson Ronald D. 
Published: September 2007

AbstractSummary: Magnetite nanoparticles (MNP), onto which the radical initiator 4,4′ azobis (4‐cyanovaleric acid) (ACV) was grafted, were used as a macro‐initiators in the polymerization of styrene. Bulk and emulsion polymerizations were performed. Core‐shell nanoparticles with a magnetite core and a polystyrene (PS) shell were obtained by emulsion polymerizations. A simple geometrical model was proposed to correlate the size of the final PS shell to the styrene/MNP ratio. The diameter of the shell of the prepared core‐shell nanoparticles was found to be greater than expected. This was due to the fact that most of the PS shell contained several MNP cores. This feature was confirmed by transmission electron microscopy (TEM) imaging of the stable latexes obtained. Particles of nearly mono‐disperse size were obtained by emulsion polymerization, and their diameters decreased as the ratio of MNP/styrene increased. Films were cast from the core‐shell nanoparticles dissolved in chloroform. Due to the superparamagnetic properties of the MNP, a change in their organization in the polymer matrix was obtained by applying a magnetic field at a temperature above the Tg of the PS shell.
Synthesis, Characterisation of Novel Polyaniline Nanomaterials and Application in Amperometric Biosensors
Authors: Michira I. , Akinyeye R. , Somerset V. , Klink M. J. , Sekota M. , Al‐Ahmed A. , Baker P. G. L. , Iwuoha E. 
Published: September 2007

AbstractSummary: Anthracene sulfonic acid doped polyaniline nanomaterials were prepared through the chemical oxidative polymerisation process. Ammonium peroxydisulfate (APS) was employed as oxidant. Scanning electron microscopy (SEM) results show the resultant polyaniline (PANi) materials exhibited nanofibrillar morphology with diameter sizes less than 300 nm. Using the nanofibrillar PANI, amperometric biosensors for H2O2 and erythromycin were constructed through the drop‐coating technique. Anthracene sulfonic acid (ASA) doped PANi and the test enzymes horseradish peroxidase, (HRP), or cytochrome P450 3A4, (CYP4503A4) were mixed in phosphate buffer solution before drop coating onto the electrode. The resultant biosensors displayed typical Michaelis‐Menten behaviour. The apparent Michaelis‐Menten constant obtained was 0.18 ± 0.01 mM and 0.80 ± 0.02 µM L−1 for the peroxide and erythromycin biosensor respectively. The sensitivity for the peroxide sensor was 3.3 × 10−3 A · cm−2 · mM−1, and the detection limit was found to be 1.2 ×  10−2 mM respectively. Similarly, the sensitivity for the erythromycin sensor was in the same order at 1.57 × 10−3 A · cm−2 · mM−1 and detection limit was found to be 7.58 × 10−2 µM.
CMC and Phase Separation Studies of RAFT Mediated Amphiphilic Diblock Glycopolymers with Methyl Acrylate and Styrene
Authors: Ramiah V. , Matahwa H. , Weber W. , McLeary J. B. , Sanderson R. D. 
Published: September 2007

AbstractSummary: Interesting new CMC and phase separation data of carbohydrate‐based self‐assembling core‐shell nanoparticles which were synthesized via the Reversible Addition‐Fragmentation Transfer (RAFT) process. The macro‐RAFT agent, poly(3‐O‐ Methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐D‐glucofuranose) (PMAlpGlc), was prepared by RAFT polymerization of the glycomonomer with cumyl phenyl dithioacetate as the chain transfer agent. Chain extension with styrene and methyl acrylate afforded the diblock copolymers (PMAlpGlc‐b‐styrene and PMAlpGlc‐b‐methyl acrylate) having predetermined molecular weight and narrow molecular weight distributions. Acidolysis of these diblock copolymers were undertaken and confirmed by NMR. Core‐shell nanoparticles were observed by TEM.
Chemo‐enzymatic Synthesis and RAFT Polymerization of 6‐O‐Methacryloyl Mannose: A Suitable Glycopolymer for Binding to the Tetrameric Lectin Concanavalin A?
Authors: Granville Anthony M. , Quémener Damien , Davis Thomas P. , Barner‐Kowollik Christopher , Stenzel Martina H. 
Published: September 2007

AbstractSummary: The chemo‐enzymatic synthesis of 6‐O‐methacryloyl mannose (MaM) glycomonomer was successfully performed for the first time. Subsequent aqueous RAFT polymerization of the monomer yielded well‐defined, linear poly(6‐O‐methacryloyl mannose) (PMaM) glycopolymers without the need for protecting and deprotecting group chemistry. As well as investigating the RAFT polymerization kinetics of this monomer using various initial monomer to chain transfer agent concentration ratios, the protein binding ability of the generated glycopolymer was tested using concanavalin A, a known mannose‐residue binding lectin.
Determinants of firm‐specific thresholds in acquisition decisions
Authors: Folta Timothy B. , O'Brien Jonathan P. 
Published: September 2007

AbstractWe develop a model to explain why some firms make acquisitions, while other firms with equal performance expectations do not. We argue that the decision to acquire is not strictly a function of expected abnormal returns, but also depends on a firm's unique acquisition threshold. Our model posits that the threshold is determined by governance, managerial competence, synergy with assets in place, and synergy with growth options. Our empirical findings, drawn from a sample of over 27 000 US acquisitions, offer strong support for the model, suggesting that firms with low thresholds may choose to invest despite comparatively low abnormal returns. Copyright © 2007 John Wiley & Sons, Ltd.
Microglial activation mediates neurodegeneration related to oligodendroglial α‐synucleinopathy: Implications for multiple system atrophy
Authors: Stefanova Nadia , Reindl Markus , Neumann Manuela , Kahle Philipp J. , Poewe Werner , Wenning Gregor K. 
Published: September 2007

AbstractThe role of microglial activation in multiple system atrophy (MSA) was investigated in a transgenic mouse model featuring oligodendroglial α‐synuclein inclusions and loss of midbrain dopaminergic neurons by means of histopathology and morphometric analysis. Our findings demonstrate early progressive microglial activation in substantia nigra pars compacta (SNc) associated with increased expression of iNOS and correlating with dopaminergic neuronal loss. Suppression of microglial activation by early long‐term minocycline treatment protected dopaminergic SNc neurons. The results suggest that oligodendroglial overexpression of α‐synuclein may induce neuroinflammation related to nitrosive stress which is likely to contribute to neurodegeneration in MSA. Further, we detected increased toll‐like receptor 4 immunoreactivity in both transgenic mice and MSA brains indicating a possible signaling pathway in MSA which needs to be further studied as a candidate target for neuroprotective interventions. © 2007 Movement Disorder Society
Pupil diameter in darkness differentiates progressive supranuclear palsy (PSP) from other extrapyramidal syndromes
Authors: Schmidt Claudia , Herting Birgit , Prieur Silke , Junghanns Susann , Schweitzer Katherine , Globas Christoph , Schöls Ludger , Antoni Sabine , Ferger Dietmar , Reichmann Heinz , Wilhelm Helmut , Berg Daniela , Ziemssen Tjalf 
Published: September 2007

AbstractThe most important features that characterize and differentiate progressive supranuclear palsy from other Parkinsonian syndromes are postural instability, supranuclear gaze palsy, pseudobulbar palsy, parkinsonism, and cognitive disturbances. In this article, we demonstrate that progressive supranuclear palsy patients exhibit pathologically decreased pupil diameters after dark adaptation recorded by TV pupillography. A cut off value of 3.99 mm was defined to differentiate progressive supranuclear palsy patients from patients with other extrapyramidal disorders like Parkinson's disease and multiple system atrophy with a specificity of 86.4% and a sensitivity of 70.8%. Other pupil abnormalities could not be described in patients with extrapyramidal syndromes. © 2007 Movement Disorder Society
Antero‐ventral internal pallidum stimulation improves behavioral disorders in Lesch–Nyhan disease
Authors: Cif Laura , Biolsi Brigitte , Gavarini Sophie , Saux Aude , Robles Santiago Gil , Tancu Cornel , Vasques Xavier , Coubes Philippe 
Published: September 2007

AbstractThe Lesch–Nyhan syndrome is an X‐linked recessive disorder caused by a deficiency in hypoxanthine–guanine phosphoribosyl transferase, a purine salvage enzyme. Affected individuals exhibit a characteristic neurobehavioral disorder with delayed acquisition of motor skills, dystonia, severe self‐mutilations, and aggressive behavior. Deep brain stimulation has been previously proposed for controlling isolated involuntary movements and psychiatric disorders. We applied a double bilateral simultaneous stimulation to limbic and motor internal pallidum in one patient for controlling both behavioral and movement disorders, respectively. The injurious compulsions disappeared; dystonia and dyskinesia were decreased at 28 months follow‐up. © 2007 Movement Disorder Society
Strong solvability of 3‐D Cahn–Hilliard system in elastic solids
Authors: Pawłow Irena , Zaja̧czkowski W. M. 
Published: September 2007

AbstractIn this paper we prove the existence and uniqueness of a strong solution to a 3‐D model of phase separation in elastic solids. The model has the form of an initial‐boundary‐value problem for a nonlinear coupled system of hyperbolic–parabolic type. The key idea of the proof is based on the analysis of the system once‐ and twice differentiated with respect to time variable. The paper develops results of the previous work (Top. Meth. Nonlin. Anal., in press). Copyright © 2007 John Wiley & Sons, Ltd.
A new hybrid velocity integration method applied to elastic wave propagation
Authors: Chen Zhiyun , Steeb Holger , Diebels Stefan 
Published: September 2007

AbstractWe present a novel space–time Galerkin method for solutions of second‐order time‐dependent problems. By introducing the displacement–velocity relationship implicitly, the governing set of equations is reformulated into a first‐order single field problem with the unknowns in the velocity field. The resulting equation is in turn solved by a time‐discontinuous Galerkin approach (Int. J. Numer. Anal. Meth. Geomech. 2006; 30:1113–1134), in which the continuity between time intervals is weakly enforced by a special upwind flux treatment. After solving the equation for the unknown velocities, the displacement field quantities are computed a posteriori in a post‐processing step. Various numerical examples demonstrate the efficiency and reliability of the proposed method. Convergence studies with respect to the h‐ and p‐refinement and different discretization techniques are given. Copyright © 2007 John Wiley & Sons, Ltd.
Longitudinal assessment of immunological status and rate of immune recovery following treatment in children with ALL
Authors: Kosmidis Sofia , Baka Margarita , Bouhoutsou Despina , Doganis Dimitrios , Kallergi Constantina , Douladiris Nikolaos , Pourtsidis Apostolos , Varvoutsi Maria , Saxoni‐Papageorgiou Fotini , Vasilatou‐Kosmidis Helen 
Published: September 2007

AbstractBackgroundWe prospectively evaluated the immunological status, immune recovery and risk of infection in pediatric ALL patients treated on the BFM 95 protocol.ProcedureHumoral and cellular immunity were evaluated in 72 children with ALL at the end of intensive therapy and values were compared to those at the completion of therapy and 6‐monthly. Parameters investigated included lymphocyte subpopulation by flow cytometry, immunoglobulin levels by nephelometry, antibody titers to previous immunizations and delayed hypersensitivity with skin testing. Immune responses were correlated to duration of therapy, CNS radiotherapy, age and sex.ResultsHumoral immunity was severely depressed by the end of intensive therapy with low immunoglobulin levels and CD19, improved after therapy cessation. Cellular immune responses were normal at the end of intensive treatment but declined significantly by the end of therapy and both CD4 and CD8 remained low at later evaluation points whereas CD4/CD8 ratio was increasing. Duration of therapy and CNS radiotherapy did not affect the rate of immune recovery whereas female had higher CD19, CD45RO, and IgM and children >7 years had higher CD19 and lower CD16 and CD3DR. Among immunized children, 86.7% maintained protective antibodies to MMR and 63% to polio. Despite impairment of immunity, infections outside the neutropenic periods were common viral illnesses.ConclusionHumoral immunity was depressed in children with ALL at the end of intensive therapy but began to recover after cessation of therapy. In contrast, cellular immunity declined significantly by the end of therapy and remained abnormal for at least 1 year post‐therapy. Pediatr Blood Cancer 2008;50:528–532. © 2007 Wiley‐Liss, Inc.
Simultaneous determination of cinnamaldehyde, eugenol and piperine by HPTLC densitometric method
Authors: Gopu C. L. , Aher Suyog , Mehta Hiral , Paradkar A. R. , Mahadik K. R. 
Published: September 2007

AbstractAn HPTLC densitometric method for the simultaneous determination of cinnamaldehyde and eugenol as well as trace amounts of piperine in pepper‐contaminated cinnamon was developed. The applicability of the method was tested with cinnamon bark powder adulterated with pepper powder, cinnamon oil, clove powder, clove oil and a commercial preparation containing cinnamaldehyde and eugenol. The method was validated for specificity, precision, accuracy and robustness. The method was found to be precise for different concentrations of cinnamaldehyde, eugenol and piperine. The accuracy of the method was checked by conducting a recovery study at three different levels. The linearity was found to be in the ranges 52.54–735.56, 533.2–8531.2 and 50–300 ng/spot, respectively, with correlation coefficients of 0.9985 ± 0.04, 0.9982 ± 0.06 and 0.9937 ± 0.11 for cinnamaldehyde, eugenol and piperine. Copyright © 2007 John Wiley & Sons, Ltd.
A reversed‐phase high‐performance liquid chromatographic method for the determination of aloesin, aloeresin a and anthraquinone in Aloe ferox
Authors: Zahn Michael , Trinh Thao , Jeong Mijeong Lee , Wang Desheng , Abeysinghe Padmapriya , Jia Qi , Ma Wenwen 
Published: September 2007

AbstractA reversed‐phase HPLC method for the quantification of aloesin, aloeresin a and anthraquinone (as barbaloin) in Aloe ferox Miller and aloe‐related products has been developed and validated. The method utilized a C18 column with a water–methanol gradient and UV detection at 297 nm. The method validation included linearity, accuracy, precision, limit of detection, limit of quantitation, specificity and standard solution stability. The method showed good linearity (r > 0.99 for all components) and recovery (>85% for all components). The detection and quantitation limits for barbaloin were determined to be 0.02 and 0.1 ppm at signal‐to‐noise ratios of approximately 3:1 and 10:1, respectively. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of hydroxyl content on the morphology and properties of epoxy/poly(styrene‐co‐allylalcohol) blends
Authors: Prolongo Silvia G. , Salazar Alicia , Ureña Alejandro , Rodríguez Jesús 
Published: September 2007

AbstractBlends based on epoxy resin and random copolymers, poly(styrene‐co‐allylalcohol) (PS‐co‐PA), were studied. Two PS‐co‐PA copolymers, with different hydroxyl content, and a polyallylalcohol (PA) homopolymer were used to analyze the effect of polyalcohol content. The polymers presented similar values of molar mass. The miscibility of noncured mixtures and the thermal transition behavior of cured blends were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Its morphology was studied using both scanning and transmission electron microscopy (SEM and TEM). While the epoxy/PA blends are homogenous materials, because of the epoxy/hydroxyl reaction, PS‐co‐PA/epoxy blends shows separated phases. In these blends, the presence of a third glass transition, whose value is an intermediate between those of pure components, and the presence of a well‐defined interfacial layer between PS‐co‐PA domains and epoxy matrix indicates a secondary epoxy/hydroxyl reaction. The modification of epoxy resin with PS‐co‐PA provides significant increase in the storage modulus measured by DMTA. POLYM. ENG. SCI., 47:1580–1588, 2007. © 2007 Society of Plastics Engineers