bluuebunny/crossref_metadata_2025_split huggingface dataset:
VIVO Complexes of Bis(imidazol‐2‐yl) Derivatives: A Potentiometric, Spectroscopic and DFT Study
Authors: Várnagy Katalin , Csorba Timea , Kiss Dóra , Garribba Eugenio , Micera Giovanni , Sanna Daniele 
Published: September 2007

AbstractThe complexation of the VIVO ion with four amino acid derivatives of bis(imidazol‐2‐yl)methylamine [N‐glycyl‐bis(imidazol‐2‐yl)methylamine = Gly‐BIMA, N‐α‐aspartyl‐bis(imidazol‐2‐yl)methylamine = α‐Asp‐BIMA, N‐α‐glutamyl‐bis(imidazol‐2‐yl)methylamine = α‐Glu‐BIMA and N‐histidyl‐bis(imidazol‐2‐yl)methylamine = His‐BIMA] was studied in aqueous solution through the combined application of potentiometric and spectroscopic (UV/Vis and EPR) techniques. For comparison, the complexing capability of three simple bis(imidazol‐2‐yl) derivatives [bis(imidazol‐2‐yl)methane = BIM, bis(imidazol‐2‐yl)methylamine = BIMA and bis(imidazol‐2‐yl)nitromethane = BINM] and two benzyloxycarbonyl (Z) derivatives (Z‐Gly‐BIMA and Z‐Ala‐BIMA) was reported. Mono‐ and bis‐chelated species with the (Nim, Nim) donor set were formed in both acid and neutral pH conditions, with the bis‐chelated complexes being characterised by a cis‐trans isomerism. In the basic pH range the complexation process continues with the formation of a mono‐hydroxo cis‐VOL2H–1 complex in systems with BIM, BIMA and BINM, and with the deprotonation and coordination of the amide nitrogen to give VOLH–1 and VOLH–2 in those with Gly‐BIMA, α‐Asp‐BIMA, α‐Glu‐BIMA and His‐BIMA. The results demonstrate that the bis(imidazol‐2‐yl)methyl residue is an anchoring group of intermediate strength, capable of avoiding extensive hydrolysis of the VIVO ion in the presence of a slight excess of ligand (L/M from 3:1 to 5:1). DFT calculations with progressively more complex basis sets were performed in order to obtain information on the structure of the VOLH–1 and VOLH–2 complexes. Finally, a discussion on the 51V anisotropic parallel hyperfine coupling constant (A∥) of VOLH–1 and VOLH–2 and on the EPR properties connected to the V–N–(amide) bond in VIVO complexes is presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The First Example of a Bis(trifluoromethyl)carbene Transition‐Metal Complex and Its Reduction to a Perfluoroallene Complex
Authors: Yuan Jian , Hughes Russell P. , Rheingold Arnold L. 
Published: September 2007

AbstractNa/Pb alloy reduction of the (perfluoroisopropyl)iridium complex Cp*(CO)IrI[CF(CF3)2] afforded the first example of a bis(trifluoromethyl)carbene complex, Cp*(CO)Ir=C(CF3)2, which has been crystallographically characterized. Further reduction of this carbene complex with KC8 yielded the perfluoroallene iridium complex Cp*Ir(CO)(η2‐CF2CCF2). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Simple and Feasible Simultaneous Determination of Three Phenolic Pollutants on Boron‐Doped Diamond Film Electrode
Authors: Lei Yanzhu , Zhao Guohua , Liu Meichuan , Xiao Xiaoe , Tang Yiting , Li Dongming 
Published: September 2007

AbstractA simple, rapid and feasible method is developed for direct and simultaneous determination of phenol (Ph), hydroquinone (HQ) and 4‐nitrophenol (4‐NP) on unmodified boron‐doped diamond (BDD) electrode. Results showed that the oxidative peaks of these three phenolic compounds can be completely separated on BDD electrode in acidic conditions by using electrochemical cyclic voltammetry technique. The peak potential separations are all higher than 0.35 V. Moreover, BDD electrode is extremely easy to be refreshed to obtain current values with good reproducibility, even if it is passivated by phenolic compounds with different adsorption characteristics. All the above features are on account of the outstanding electrochemical characteristics of BDD electrode, and lead to the advantage and feasibility for simultaneous determination of three phenolic compounds without any other separation operation. For each tested phenolic compound, the concentration range with linearity is in two or three orders of magnitude in the presence of other coexisting phenolic compounds with the concentrations more than 1000 times higher than that of the tested component. The present method is also shown to be promising for the determination of phenolic contaminants in the real wastewater samples.
Effect of Various Deposition Techniques, Electrode Materials and Posttreatment with Tetrabutylammonium and Tetrabutylphosphonium Salts on the Electrochemical Behavior and Stability of Various Prussian Blue Modified Electrodes
Authors: Haghighi Behzad , Shams Nafiseh , Gorton Lo 
Published: September 2007

AbstractThe effect of various deposition techniques, electrode materials and posttreatment with tetrabutylammonium and tetrabutylphosphonium salts on the electrochemical behavior and stability of various Prussian blue (PB) modified electrodes, namely PB modified glassy carbon electrodes, silicate‐film supported PB modified glassy carbon electrodes, PB‐doped silicate glassy carbon electrodes, PB modified carbon ceramic electrodes using electrochemical deposition and PB modified carbon ceramic electrodes using chemical deposition is reported. Cyclic voltammetry and amperometric measurements of hydrogen peroxide were performed in a flow injection system while the carrier phosphate buffer (pH 7.0) with a flow rate of 0.8 mL min−1 was propelled into the electrochemical flow through cell housing the PB modified working electrode as well as an Ag|AgCl|0.1 M KCl reference and a Pt auxiliary electrode. The results showed that the deposition procedure, electrode material and posttreatment with additional chemicals can significantly alter the stability and electrochemical behavior of the PB film. Among the studied PB modified electrodes, those based on carbon ceramic electrodes modified with a film of electropolymerized PB showed the best electrochemical stability.
Zinc Oxide/Zinc Hexacyanoferrate Hybrid Film‐Modified Electrodes for Guanine Detection
Authors: Chu Hung‐Wei , Thangamuthu R. , Chen Shen‐Ming 
Published: September 2007

AbstractAn electroactive polynuclear hybrid films of zinc oxide and zinc hexacyanoferrate (ZnO/ZnHCF) have been deposited on electrode surfaces from H2SO4 solution containing Zn(NO3)2 and K3[Fe(CN)6] by repetitive potential cycling method. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) measurements demonstrate the steady growth of hybrid film. There are two redox couples present in the voltammograms of hybrid film and it is obvious in the case of pH 2. Surface morphology of hybrid film was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Energy dispersive spectrometer (EDS) data confirm existence of zinc oxide in the hybrid film. The effect of type of monovalent cations on the redox behavior of resulting film was investigated. In pure supporting electrolyte, electrochemical responses of modified electrode resemble with that of a surface immobilized redox couple. The electrocatalytic activity of ZnO/ZnHCF hybrid film was investigated towards guanine using cyclic voltammetry and rotating disc electrode (RDE) techniques. Finally, feasibility of using ZnO/ZnHCF hybrid film‐coated electrodes for guanine estimation in flow injection analysis (FIA) was also investigated.
Novel staining‐free proteomic method for simultaneous identification of proteins and determination of their pI values by using low‐molecular‐mass pI markers
Authors: Chmelík Josef , Mazanec Karel , Šlais Karel 
Published: September 2007

AbstractA new proteomic staining‐free method for simultaneous identification of proteins and determination of their pI values by using low‐molecular‐mass pI markers is described. It is based on separation of proteins in gels by IEF in combination with mass spectrometric analysis of both peptides derived by in‐gel digestion and low‐molecular‐mass pI markers extracted form the same piece excised from the gel. In this method, the pI markers are mixed with a protein mixture (a commercial malted barley protein extract) deposited on a gel and separated in a pH gradient. Color pI markers enable supervision of progress of focusing process. Several separated bands of the pI markers (including separated proteins) were excised and the pI markers were eluted from each gel piece by water/ethanol and identified by MALDI‐TOF/TOF MS. The remaining carrier ampholytes were then washed out from gel pieces and proteins were in‐gel digested with trypsin or chymotrypsin. Obtained peptides were measured by MALDI‐TOF/TOF MS and proteins were identified via protein database search. This procedure allows omitting time‐consuming protein staining and destaining procedures, which shortens the analysis time. For comparison, other IEF gels were stained with CBB R 250 and proteins in the gel bands were identified. Similarity of the results confirmed that our approach can give information about the correct pI values of particular proteins in complex samples at significantly shorter analysis times. This method can be very useful for identification of proteins and their post‐translational modifications in prefractioned samples, where post‐translational modifications (e.g., glycation) are frequent.
Lights, Camera, Action! Systematic variation in 2‐D difference gel electrophoresis images
Authors: Sellers Kimberly F. , Miecznikowski Jeffrey , Viswanathan Surya , Minden Jonathan S. , Eddy William F. 
Published: September 2007

Abstract2‐D Difference gel electrophoresis (DIGE) circumvents many of the problems associated with gel comparison via the traditional 2‐DE approach. DIGE's accuracy and precision, however, is compromised by the existence of other significant sources of systematic variation, including that caused by the apparatus used for imaging proteins (location of the camera and lighting units, background material, imperfections within that material, etc.). Through a series of experiments, we estimate some of these factors, and account for their effect on the DIGE experimental data, thus providing improved estimates of the true relative protein intensities. The model presented here includes 2‐DE images as a special case.
Bulk modification of PDMS microchips by an amphiphilic copolymer
Authors: Xiao Yan , Yu Xiao‐Dong , Xu Jing‐Juan , Chen Hong‐Yuan 
Published: September 2007

AbstractA simple and rapid bulk‐modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)–poly(ethylene glycol) (PLA–PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk‐modified PDMS microchips decreased. The effects of the additive loading and the pH on the EOF were investigated in detail. The bulk‐modified PDMS microchips exhibited reproducible and stable EOF behavior. The application of the bulk‐modified PDMS microchips was also studied and the results indicated that they could be successfully used to separate amino acids and to suppress protein adsorption.
Mass distribution, polydispersity, and focusing properties of carrier ampholytes for IEF. Part V: pH 9–11 interval
Authors: Simó Carolina , Citterio Attilio , Righetti Pier Giorgio 
Published: September 2007

AbstractAs a last part of an investigation on all 2‐pH‐unit intervals of carrier ampholytes (CAs) for IEF (see Electrophoresis 2006, 27, 3919–3934; 2006, 27, 4849–4858; 2007, 28, 715–723) two different lots of Servalyt CAs, in the pH 9–11 range, have been analyzed by a 2‐D technique based on preparative Rotofor fractionation followed by capillary electrophoresis mass‐spectrometry of 10 out of 20 fractions harvested, in the second dimension. The findings: the two lots contain 65 and 69 different Mr compounds, in the Mr interval of 232–667 Da, for a total of 341–387 isoforms, respectively. Since this is a chaotic organic synthesis, the high reproducibility (here demonstrated for the first time during the 40 years of existence of CAs) of the synthetic process (for two batches produced at 6 years of distance) is remarkable, considering that a 94% agreement for the individual chemicals and 88% agreement for the total number of isoforms for the two lots is found. It is additionally demonstrated that the lower pI species are accompanied by considerably more isoforms than the high pI forms and that in all cases such isoforms consist of family of compounds clustered around the pI of the parental form, with a pI spread of ca. 0.1–0.2 pH units.
An investigation of peak‐broadening effects arising when combining CE with MS
Authors: Axén Jakob , Axelsson Bengt‐Olof , Jörntén‐Karlsson Magnus , Petersson Patrik , Sjöberg Per J. R. 
Published: September 2007

AbstractIn this study, peak‐broadening effects caused by nebulizing gas flow and lack of temperature control have been investigated for separation capillaries with three different inner diameters. The study was performed with serial UV/ESI‐MS detection in an effort to distinguish between peak broadening arising in the separation and peak broadening arising in the ion source. The nebulizing gas was found to significantly affect both migration time and separation efficiency when using capillaries with 50 and 75 µm id. If the nebulizing gas is on during injection, the injection volume increases to such an extent that significant peak broadening is induced. Reducing the id to 25 µm minimizes the parabolic flow induced by the nebulizing gas. Results indicate that the nebulizing gas pressure can be optimized to minimize peak broadening in the ion source. A decrease in detection sensitivity, possibly related to the orthogonal design of the interface, was observed when the nebulizing gas pressure was increased. A tapered capillary tip was found to provide superior separation efficiency as well as sensitivity.
INAR(1) modeling of overdispersed count series with an environmental application
Authors: Pavlopoulos Harry , Karlis Dimitris 
Published: September 2007

AbstractThis paper is concerned with a novel version of the INAR(1) model, a non‐linear auto‐regressive Markov chain on ℕ, with innovations following a finite mixture distribution of $m \geq 1$ Poisson laws. For $m > 1$, the stationary marginal probability distribution of the chain is overdispersed relative to a Poisson, thus making INAR(1) suitable for modeling time series of counts with arbitrary overdispersion. The one‐step transition probability function of the chain is also a finite mixture, of m Poisson‐Binomial laws, facilitating likelihood‐based inference for model parameters. An explicit EM‐algorithm is devised for inference by maximization of a conditional likelihood. Alternative options for inference are discussed along with criteria for selecting m. Integer‐valued prediction (IP) is developed by a parametric bootstrap approach to ‘coherent’ forecasting, and a certain test statistic based on predictions is introduced for assessing performance of the fitted model. The proposed model is fitted to time series of counts of pixels where spatially averaged rain rate exceeds a given threshold level, illustrating its capabilities in challenging cases of highly overdispersed count data. Copyright © 2007 John Wiley & Sons, Ltd.
Empirical significance values for linkage analysis: trait simulation using posterior model distributions from MCMC oligogenic segregation analysis
Authors: Igo Robert P. , Wijsman Ellen M. 
Published: September 2007

AbstractVariance‐components (VC) linkage analysis is a powerful model‐free method for assessing linkage, but the distribution of VC logarithm of the odds ratio (LOD) scores may deviate substantially from the assumed asymptotic distribution. Typically, the null distribution of the VC‐LOD score and other linkage statistics has been estimated by generating new genotype data independently of the trait data, and computing a linkage statistic for many such marker‐simulated data sets. However, marker simulation is susceptible to errors in the assumed marker and map model and is computationally intensive. Here, we describe a method for generating posterior distributions of linkage statistics through simulation of trait data based on the original sample and on results from an initial scan using a Bayesian Markov‐chain Monte Carlo (MCMC) approach for oligogenic segregation analysis. We use samples of oligogenic trait models taken from the posterior distribution to generate new samples of trait data, which were paired with the original marker data for analysis. Empirical P‐values obtained from trait and marker simulation were similar when derived for several strong linkage signals from published linkage scans, and for analysis of data with a known, simulated, trait model. Furthermore, trait simulation produces the expected null distribution of VC‐LOD scores and is computationally fast when marker identity‐by‐descent estimates from the original data could be reused. These results suggest that trait simulation gives valid estimates of statistical significance of linkage signals. Finally, these results also demonstrate the feasibility of obtaining empirical significance levels for evaluating Bayesian oligogenic linkage signals with either marker or trait simulation. Genet. Epidemiol. 2008. © 2007 Wiley–Liss, Inc.
Reaction of a cyclic triphosphenium ion with triflic acid and SnX2 (X = Br or Cl): A 31P NMR study
Authors: Boyall Alice J. , Dillon Keith B. , Monks Philippa K. , Potts Jennifer C. 
Published: September 2007

AbstractThe di‐ium dication formed by triflic acid protonation of the cyclic triphosphenium ion derived from 1,4‐bis‐diphenylphosphinobutane, (dppb), and P3(X = Br or Cl) decomposes via an acyclic dication bearing a PHX group; this intermediate is reduced by SnX2 in the presence of HX to yield a dication with a PH2 primary phosphane terminal group, which is comparatively stable. The structure of this species has been unequivocally confirmed by 31P solution‐state NMR spectroscopy. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:609–612, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20302
Lithium bis(2‐phenylphosphidoethyl)phenyl‐phosphine: A reactive phosphorus intermediate
Authors: Mason Lucas J. , Moore Alexander J. , Carr Amy , Helm Monte L. 
Published: September 2007

AbstractBis(2‐phenylphosphinoethyl)phenylphosphine, PhP(CH2CH2PPh2)2, reacts with lithium in tetrahydrofuran to give the corresponding lithium bis(2‐diphenylphosphidoethyl)phenylphosphine, Li2[PhP(CH2CH2PPh)2]. The lithium diphosphide is identified by NMR spectroscopy and further characterized through arylation with excess brombenzene to reform the starting phosphine, PhP(CH2CH2PPh2)2. Initial reactivity studies of the diphosphide, PhP(CH2CH2PPh), with some alkylhalides are also described. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:675–678, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20351
Inhibition of mRNA synthesis in the hippocampus impairs consolidation and reconsolidation of spatial memory
Authors: Da Silva Weber C. , Bonini Juliana S. , Bevilaqua Lia R.M. , Medina Jorge H. , Izquierdo Iván , Cammarota Martín 
Published: September 2007

AbstractUsing two different mRNA synthesis inhibitors, we show that blockade of hippocampal gene expression during restricted posttraining or postretrieval time windows hinders retention of long‐term spatial memory for the Morris water maze task, without affecting short‐term memory, nonspatial learning, or the functionality of the hippocampus. Our results indicate that spatial memory consolidation induces the activation of the hippocampal transcriptional machinery and suggest the existence of a gene expression‐dependent reconsolidation process that operates in the dorsal hippocampus at the moment of retrieval to stabilize the reactivated mnemonic trace. © 2007 Wiley‐Liss, Inc.
GSK3 promotes arsenite‐induced apoptosis via facilitation of mitochondria disruption
Authors: Watcharasit Piyajit , Thiantanawat Apinya , Satayavivad Jutamaad 
Published: September 2007

AbstractArsenic is an environmental toxicant that recently has been shown to have anticancer activity against a number of types of cancer cells by inducing apoptosis. Glycogen synthase kinase‐3 (GSK3), a serine/threonine kinase, is an important pro‐apoptotic signaling enzyme. Although GSK3 has been shown to promote apoptosis caused by a wide variety of insults, a role for GSK3 in arsenic‐induced apoptosis has not yet been identified. Investigation of the involvement of GSK3 in arsenite‐induced apoptosis demonstrated that arsenite induced apoptosis in SH‐SY5Y human neuroblastoma cells, activating the executioner caspase‐3 which caused cleavage of poly‐ADP ribose‐polymerase (PARP). Two selective GSK3 inhibitors, lithium and SB216763, attenuated caspase‐3 activation and PARP cleavage induced by arsenite treatment indicating that GSK3 contributed to arsenite‐induced apoptosis. Apoptotic signaling following exposure to arsenite involved cytochrome C release from mitochondria, and this was reduced by inhibition of GSK3 indicating that GSK3 promotes arsenite‐induced apoptotic signaling upstream of mitochondrial disruption. Moreover, arsenite induced the translocation of Bax and p53 to the mitochondria and the activation‐associated oligomerization of Bax, and these crucial events were reduced by inhibition of GSK3, indicating that GSK3 promotes arsenite‐induced apoptosis by facilitating signals leading to mitochondrial apoptotic events. Taken together, the findings from this study reveal that GSK3 promotes arsenite‐induced apoptosis by facilitating signaling leading to disruption of mitochondria. Copyright © 2007 John Wiley & Sons, Ltd.
Effects of irradiance, wavelength, and thermal emission of different light curing units on the Knoop and Vickers hardness of a composite resin
Authors: Torno Vladja , Soares Paulo , Martin Juliana M. H. , Mazur Rui F. , Souza Evelise M. , Vieira Sérgio 
Published: September 2007

AbstractThe aim of this study was to evaluate the effects of irradiance, light emission wavelength, and heating of different light curing units on the Knoop and Vickers hardness of a hybrid composite resin. The specimens were irradiated during 40 s with ten different light curing units, LEDs, and halogen lights. The spectral emission of each light curing unit was assessed by a spectrometer, the irradiance was measured by two commercial radiometers, and the heating measured with a thermocouple. After 48 h of storage in a dark recipient under a 100% humidity condition, the Knoop and Vickers hardness tests were carried out. The hardness results were analyzed by ANOVA, and Tukey HSD test (p < 0.05). The results showed that the surface hardness of the composite resin depends not only on the irradiance, but strongly on the emission wavelength and heating of the light curing units. It was observed, a linear correlation between the conversion degree and radiant exposure. In addition, it is suggested that the well known base to top surface hardness ratio convention of 80–90% is not appropriate to evaluate curing efficiency of composites, since the top surface is not always sufficiently polymerized. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008