bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disulfides, Imines, and Metal Coordination within a Single System: Interplay between Three Dynamic Equilibria
Authors: Sarma Rupam J. , Otto Sijbren , Nitschke Jonathan R. 
Published: September 2007

AbstractWe report a system in which three distinct dynamic linkages, disulfide (SS), imine (CN), and coordinative (N→metal) bonds were shown to be capable of simultaneous reversible exchange. The “disulfide layer” of the system under study consists of two homo‐disulfides, bis(4‐aminophenyl) disulfide 1 and bis(4‐methoxyphenyl) disulfide 2 that equilibrate in the presence of catalytic amount of triethylamine to favor the formation of a hetero‐disulfide product, 4‐aminophenyl‐4′‐methoxyphenyl disulfide 3. The addition of 2‐formylpyridine and a metal salt strongly perturbed this 1+2⇄3 equilibrium through the formation of metal complexes incorporating disulfide 1 as a subcomponent. CuI perturbed the equilibrium by a factor of 3.3, and FeII by a factor of 179, in both cases in favor of the homo‐disulfides. The disulfide equilibrium could be further modified, following metal‐complex formation, by coordinative (transmetallation: substitution of FeII for CuI) or covalent (imine exchange: the substitution of one amine residue for another) exchange. Thus, although the three kinds of dynamic linkages were demonstrated to be mutually compatible, changes at one kind of linkage could be used to predictably perturb an equilibrium involving another.
A network‐centric approach for access and interface selection in heterogeneous wireless environments
Authors: Koundourakis George , Axiotis Dimitrios I. , Argyropoulos Michael , Theologou Michael 
Published: September 2007

AbstractIn this paper, we introduce a network‐based approach for access and interface selection (AIS) in the context of resource management in heterogeneous wireless environments (UMTS, WLAN and DVB‐T). We focus on the optimization of resource utilization, while ensuring acceptable quality of service (QoS) provision to the end users. Our objective is to optimally manage the overall system resources and minimize the possibility of QoS handovers (non‐mobility handovers). The adopted architecture applies to typical heterogeneous environments and network entities (Access Routers) are enhanced with extra functionalities. We propose an AIS algorithm that exploits the multihoming concept and globally manages network resources at both radio access and IP backbone networks. The algorithm can estimate near‐optimal solutions in real time and we also introduce a novel triggering policy. We present simulation results of typical scenarios that demonstrate the advantages of our approach. System performance metrics, derived from the simulations, show minimum degradations in high load and congestion situations. Copyright © 2007 John Wiley & Sons, Ltd.
Operational Limits of Controlled Current Coulometry with Ion‐Selective Polymeric Membranes
Authors: Bhakthavatsalam Vishnupriya , Bakker Eric 
Published: September 2007

AbstractPlasticized polymeric membrane electrodes containing selective chemical receptors (ionophores) that are used in potentiometric and optical sensors have recently been shown to be attractive in controlled current coulometry for calibration free reagent delivery. For this purpose, a galvanostatic pulse of fixed duration is applied across an ion‐selective membrane containing added ion‐exchanger sites, resulting in the release of a calculated amount of ions from the membrane into the sample phase. This paper evaluates the operational limits of such coulometric actuators with chronopotentiometry, using silver‐selective membranes as model systems. Diffusion theory predicts the depletion of ionophore and ion‐exchanger at one of the two interfaces in a matter of minutes, owing to the relatively small diffusion coefficients in such membranes. Chronopotentiometry on membranes containing lipophilic cations at either side of the membrane, rather than silver ions, confirms that the ionophore depletes at the inner side of the membrane. At the sample side, ionophore is expected to increase in concentration and does not result in a loss of selectivity. Chronopotentiometric responses show a drastic transition at long times, typically 30 min, which cannot plausibly be explained by the depletion of added lipophilic ion‐exchanger at the sample side since the diffusion coefficients are similar to that of ionophore. It is postulated that the intrinsic anion‐exchanger sites of the PVC matrix are relatively immobile and do not easily concentration polarize upon application of a transmembrane current pulse, in agreement with Buck's earlier work on fixed site membranes. Indeed, silver and calcium‐selective membranes fabricated with increased concentrations of such fixed sites, by using carboxylated PVC, exhibited chronopotentiometric breakdown times larger than 60 min and no loss in coulometric efficiency. The results obtained here will help in designing coulometric actuators with improved characteristics on the basis of hydrophobic polymeric ion‐selective membranes.
A Miniature Electrolytic Conductivity Probe with a Wide Linear Range
Authors: Park Sang‐Ryoul , Swerdlow Harold 
Published: September 2007

AbstractA novel miniature electrolytic conductivity probe and its successful operation with modified bipolar pulse conductometry are presented. The probe based on a concentric ring‐disk electrode configuration of less than 1 mm in diameter featured extremely small detection volume, and conductivity was measured with a 1 μL solution. Rapid response, easy and quick washing, and virtually no consumption of samples by measurements were additional advantages of the suggested probe design. Poor linearity was observed with conventional AC conductometry due to a large cell constant and a small double layer capacitance of the probe. Measurement circuits for modified bipolar pulse conductometry were designed, and optimization of the various pulse parameters led to a wide linear dynamic range of 0.05–10 mS cm−1, thus achieving high accuracy with a single‐point calibration. The suggested conductometric device could be conveniently applied to biological reagents and samples that are usually too little to be measured with conventional conductometers.
The Cyclic Renewable Mercury Film Silver Based Electrode for Determination of Uranium(VI) Traces Using Adsorptive Stripping Voltammetry
Authors: Piech Robert , Baś Bogusław , Kubiak Władysław W. 
Published: September 2007

AbstractThe new cyclic renewable mercury film silver based electrode (Hg(Ag)FE), applied for the determination of uranium(VI) traces using differential pulse adsorptive cathodic stripping voltammetry (DP AdCSV) is presented. The Hg(Ag)FE electrode with a surface area adjustable from 1.1 to 12 mm2 is characterized by very good surface reproducibility (≤2%) and long‐term stability (more than 2 thousand measurement cycles). The mechanical refreshing of mercury film is realized in the simple constructed device, in a time shorter than 1–2 seconds. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 0.4 nM (95 ng L−1) to 250 nM (60 μg L−1) for an accumulation time of tacc=20 s, with correlation coefficient of 0.9996. For a Hg(Ag)FE with a surface area of 2.7 mm2 the detection limit for an accumulation time of 120 s is as low as 12 ng L−1. The repeatability of the method at a concentration level of the analyte as low as 2.4 μg L−1, expressed as RSD is 2.5% (n=7). The proposed method was successfully applied and validated by studying the recovery of U(VI) from spiked river water and sediment samples.
Voltammetric Determination of Mercury(II) at Poly(3‐hexylthiophene) Film Electrode. Effect of Halide Ions
Authors: Tamer Uğur , Oymak Tülay , Ertaş Nusret 
Published: September 2007

AbstractThe well‐known method for the determination of mercury(II), which is based on the anodic stripping voltammetry of mercury(II), has been adapted for applications at the thin film poly(3‐hexylthiophene) polymer electrode. Halide ions have been found to increase the sensitivity of the mercury response and shift it more positive potentials. This behavior is explained by formation of mercuric halide which can be easily deposited and stripped from the polymer electrode surface. The procedure was optimized for mercury determination. For 120 s accumulation time, detection limit of 5 ng mL−1 mercury(II) has been observed. The relative standard deviation is 1.3% at 40 ng mL−1 mercury(II). The performance of the polymer film studied in this work was evaluated in the presence of surfactants and some potential interfering metal ions such as cadmium, lead, copper and nickel.
Genotoxicity of three mouthwash products, Cepacol®, Periogard®, and Plax®, in the Drosophila wing‐spot test
Authors: Rodrigues Fábio , Lehmann Maurício , do Amaral Viviane Souza , Reguly Maria Luíza , de Andrade Heloísa Helena Rodrigues 
Published: September 2007

AbstractAntiseptic mouthwashes used in biofilm control are widely available in the marketplace, despite inconsistent data concerning their genetic and cellular toxicity. In the present study, we investigated the genotoxic potential of three antiseptics currently used for odontologic treatment, Cepacol® (containing cetylpyridinium chloride), Periogard® (chlorhexidine digluconate), and Plax® (triclosan). Genotoxicity was evaluated using the Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster, employing flies having normal bioactivation (the standard cross) and flies with increased cytochrome P450‐dependent biotransformation capacity (the high bioactivation cross). Periogard and Plax produced negative responses in both types of flies; however, Cepacol (75 and 100%) produced positive responses in both the standard and high bioactivation assays, with the genotoxic responses mainly due to the induction of mitotic recombination. Assays performed with ethanol and cetylpirydinium chloride, two major ingredients of Cepacol, indicated that the genotoxity of the mouthwash is likely to be due to ethanol. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Attachment styles, memories of parental rearing and therapeutic bond: a study with eating disordered patients, their parents and therapists
Authors: Tereno Susana , Soares Isabel , Martins Carla , Celani Mariana , Sampaio Daniel 
Published: September 2007

AbstractPatients diagnosed with anorexia nervosa (n = 30) and bulimia nervosa (n = 27), their parents and therapists were recruited for this study aimed at examining differences between clinical groups and a control group (n = 35) in terms of attachment styles and perceptions of memories of parental rearing. Within the clinical groups, relations among these variables and therapeutic bond were explored. In addition, parents' and their daughters' attachment styles were compared. The results showed differences between clinical and control groups: the daughters in the control group reported lower levels of attachment anxiety compared to those of the clinical groups; their mothers exhibited higher security than mothers of anorectic patients and lower avoidance than mothers of bulimic patients. For the anorectic group, therapeutic bond was associated to higher father's emotional support and lower rejection; in the bulimic group, therapeutic bond was related to higher maternal emotional support and lower rejection as well as to lower paternal overprotection. Copyright © 2007 John Wiley & Sons, Ltd and Eating Disorders Association.
Application of a 3D laser scanner in the assessment of erosion and deposition volumes and channel change in a proglacial river
Authors: Milan David J. , Heritage George L. , Hetherington David 
Published: September 2007

AbstractPrevious studies of channel morphological change have often relied upon sparse spatial and temporal data‐sets, resulting in a degree of uncertainty in their conclusions. Furthermore, previous methodologies have been unable to quantify small‐scale changes in channels composed of sand and fine gravel due to inadequate data density. This study reports the use of a high‐resolution 3D laser scanner (LMS‐Z210) in the assessment of erosion and deposition volumes in the proglacial zone of Glacier du Ferpècle and Mont Miné, Switzerland. High‐resolution (>500 points/m2) data obtained across a 5881 m2 area of braid plain during the early part of the melt‐water season permitted digital elevation models (DEMs) of bar surfaces and channels to be produced. The approach negates the need for complex surface interpolation algorithms required in surveys with lower point density, e.g. those obtained from global positioning systems or total stations. Furthermore, the technique has the advantage of being able to cover a large area over a comparatively short time period. Laser scanner returns revealed high vertical precision, ±0·02 m, for dry bar surfaces; however, submerged areas (<0·2 m depth) returned lower precision, with a range of −0·15 to +0·06 m. To account for this, different levels of detection (LoD) were applied to the dry and wet parts of the study reach during DEM subtraction. Subtraction of successive DEMs revealed two short depositional episodes over the ten‐day study, with erosion dominating in between. Three episodes of avulsion were identified, two of which appeared to be triggered by constriction avulsion, whilst the other was initiated by bar‐edge erosion. Transient lobes and sediment sheets could also be identified at the downstream end of the reach, as could lobe progradation. Relatively minor, but common, changes in channel morphology could also be detected, such as bar edge accretion, bank erosion and chute development. In an analysis of the effects of survey frequency upon volumes calculated following DEM subtraction, daily surveys were found to increase erosion volumes by 67 per cent and deposition volumes by 14 per cent when compared with an 8‐day survey interval. Copyright © 2007 John Wiley & Sons, Ltd.
The value of the clock drawing test and the mini‐mental state examination for identifying vascular cognitive impairment no dementia
Authors: Zhou Aihong , Jia Jianping 
Published: September 2007

AbstractObjectiveTo determine the validity of the Clock Drawing Test (CDT) and the Mini‐Mental State Examination (MMSE) respectively or in combination for differentiating Vascular Cognitive Impairment No Dementia (V‐CIND) from normal subjects.MethodsEighty V‐CIND patients and 80 healthy control subjects were blindly evaluated with MMSE, CDT, and additional neuropsychological tests. CDT was scored according to the Rouleau method and AD Cooperative Study method. Sensitivities and specificities of the two CDT measures and MMSE for identifying V‐CIND patients were determined. The Areas Under the Receiver Operating Characteristic Curve (AUCs) were compared, and the sensitivity of the combination of CDT with MMSE calculated.ResultsV‐CIND group performed worse than controls on both MMSE (p < 0.0001) and the two CDTs (p < 0.0001). In differentiating V‐CIND patients from normal subjects, the two CDT measures provided sensitivities of 68.7% and 65.0%, and specificities of 78.7% and 86.2% respectively at optimal cutoff scores, which did no better than MMSE (sensitivity 80%, specificity 70%) (comparison of the AUCs, p = 0.992 and 0.428). The sensitivity of MMSE was marginally higher than that of CDT scored with AD Cooperative Study method (p = 0.053). By combining the two CDT measures with MMSE, the sensitivity was improved to 93.7% and 92.5% respectively.ConclusionsCompared with MMSE, CDT is of only similar or even weaker ability for identifying V‐CIND. MMSE at a cutoff of 28 may be of some value in detecting V‐CIND patients. CDT and MMSE in combination provide a valid instrument for V‐CIND screening. Copyright © 2007 John Wiley & Sons, Ltd.
Configurational assignment of N‐arylsulfonylimines of α‐polychloroaldehydes
Authors: Krivdin Leonid B. , Chernyshev Kirill A. , Rosentsveig Gulnur N. , Ushakova Irina V. , Rosentsveig Igor B. , Levkovskaya Galina G. 
Published: September 2007

AbstractConfigurational assignment of seven synthesized N‐arylsulfonylimines of α‐polychloroaldehydes has been carried out by means of experimental measurements and high‐level ab initio calculations of their 13C13C, 13C1H and 15N1H spin–spin coupling constants. The title compounds were shown to exist in solution solely in the form of E isomers, in line with thermodynamic reasoning. Copyright © 2007 John Wiley & Sons, Ltd.
Multiscale multiresolution genetic algorithm with a golden sectioned population composition
Authors: Kim Dae Seung , Jung Dong Hoon , Kim Yoon Young 
Published: September 2007

AbstractA new genetic algorithm (GA) strategy called the multiscale multiresolution GA is proposed for expediting solution convergence by orders of magnitude. The motivation for this development was to apply GAs to a certain class of large optimization problems, which are otherwise nearly impossible to solve. For the algorithm, standard binary design variables are binary wavelet transformed to multiscale design variables. By working with the multiscale variables, evolution can proceed in multiresolution; converged solutions at a low resolution are reused as a part of individuals of the initial population for the next resolution evolution. It is shown that the best solution convergence can be achieved if three initial population groups having different fitness levels are mixed at the golden section ratio. An analogy between cell division and the proposed multiscale multiresolution strategy is made. The specific applications of the developed method are made in topology optimization problems. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of withanolides in root and leaf of Withania somnifera by HPLC with photodiode array and evaporative light scattering detection
Authors: Chaurasiya Narayan Das , Uniyal Girish Chandra , Lal Payare , Misra Laxminarain , Sangwan Neelam Singh , Tuli Rakesh , Sangwan Rajender Singh 
Published: September 2007

AbstractA reversed‐phase HPLC method for the simultaneous analysis of nine structurally similar withanolides, namely, 27‐hydroxy withanone, 17‐hydroxy withaferin A, 17‐hydroxy‐27‐deoxy withaferin A, withaferin A, withanolide D, 27‐hydroxy withanolide B, withanolide A, withanone and 27‐deoxywithaferin A, has been developed using a linear binary gradient solvent system comprising methanol and water containing 0.1% acetic acid. Both photodiode array and evaporative light scattering detection were used to profile the extract compositions and to quantify the withanolides therein. Homogeneity and purity of each peak was ascertained by comparative evaluation of the on‐line UV spectra of the eluted compounds with those of the reference compounds. The method has been validated with respect to various parameters of performance quality including computation regression analysis based on calibration curves, peak resolution factor, asymmetry factor, tailing factor, RSD (%) of retention time and peak area response, limit of quantivation, limit of detection, precision and recovery. The developed method has been applied to the analysis of leaf and root tissues of Withania somnifera for withanolide content. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of crystalline peripheral chain length on the solid‐state assemblies of amphiphilic dendrons
Authors: Chung Yeon‐Wook , Lee Byung‐Ill , Kim Hyun‐Yu , Wiesner Ulrich , Cho Byoung‐Ki 
Published: September 2007

AbstractWe prepared third‐generation amphiphilic dendrons 3‐14 and 3‐18 consisting of a hydrophilic aliphatic polyether dendritic core and either tetradecyl or octadecyl peripheries, respectively. Their solid‐state self‐assembly behavior was investigated by comparison with 3‐22 having the same dendritic core and longer docosyl peripheries. In marked contrast to the lamellar assembly of 3‐22, small‐angle X‐ray analysis suggested that 3‐14 and 3‐18 show oblique columnar structures with presumably elliptical cross sections. The observed results can be rationalized by dendron shape anisotropy, which is strongly associated with the degree of crystallization as a function of alkyl chain length. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4988–4994, 2007
Operational definition of intrinsically unstructured protein sequences based on susceptibility to the 20S proteasome
Authors: Tsvetkov Peter , Asher Gad , Paz Aviv , Reuven Nina , Sussman Joel L. , Silman Israel , Shaul Yosef 
Published: September 2007

AbstractIntrinsically unstructured proteins (IUPs), also known as natively unfolded proteins, lack well‐defined secondary and tertiary structure under physiological conditions. In recent years, growing experimental and theoretical evidence has accumulated, indicating that many entire proteins and protein sequences are unstructured under physiological conditions, and that they play significant roles in diverse cellular processes. Bioinformatic algorithms have been developed to identify such sequences in proteins for which structural data are lacking, but still generate substantial numbers of false positives and negatives. We describe here a simple and reliable in vitro assay for identifying IUP sequences based on their susceptibility to 20S proteasomal degradation. We show that 20S proteasomes digest IUP sequences, under conditions in which native, and even molten globule states, are resistant. Furthermore, we show that protein–protein interactions can protect IUPs against 20S proteasomal action. Taken together, our results thus suggest that the 20S proteasome degradation assay provides a powerful system for operational definition of IUPs. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Compatibility factor for the power output of a thermogenerator
Authors: Seifert W. , Müller E. , Snyder G. J. , Walczak S. 
Published: September 2007

AbstractThe compatibility approach introduced by Snyder and Ursell enables the description of both thermoelectric generator (TEG) and Peltier cooler (TEC) within the framework of a unified 1D model. Both TEG's efficiencyηand TEC's coefficient of performance (C.O.P.) can be formulated in terms of the reduced current densityu, which has been introduced as a new, intensive state variable of a thermoelectric system. Forηand C.O.P., integral expressions are formed from additive contributions of all length segments of a thermoelectric ele‐ment, enabling exact calculation of these quantities even for arbitrarily graded elements. Maximization of these global performance parameters can thus be deduced to local maximization. Here the maximum power from a TEG with fixed length but variable heat supply is considered, which leads to the new concept of power‐related compatibility and to the introduction of a new, different compatibility factor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)