bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bismuth Film Electrode for the Cathodic Electrochemical Determination of Thiamethoxam
Authors: Guzsvány Valéria , Kádár Mihály , Gaál Ferenc , Bjelica Luka , Tóth Klára 
Published: July 2006

AbstractA cathodic electrochemical application of bismuth film modified glassy carbon electrode was investigated with the objective of determining thiamethoxam insecticide. The conditions of bismuth film deposition (electrode pretreatment procedure, composition of the plating solution, plating potential and film stability) were optimized using electrochemical and microscopic techniques. It was found that the bismuth film generation on glassy carbon substrate in a plating solution of 0.02 M Bi(NO3)3, 1 M HCl and 0.5 M KBr, at −0.25 V (vs. Ag/AgCl/3 M KCl) for 60 s and subsequent electrochemical conditioning yielded a modified electrode suitable for analytical purposes. Thiamethoxam was determined by differential pulse voltammetry in Britton–Robinson buffer of pH 8.0 in the concentration range of 1.26–45.0 μg/cm3. The reproducibility of the analytical signal was characterized by a relative standard deviation smaller than 1.5%, and the calculated values of detection and quantitation limits were 0.38 μg/cm3 and 1.26 μg/cm3, respectively. The applicability of the modified electrode was tested on real, agriculturally‐incurred potato and maize samples.
Microcavity Based Solid‐Contact Ion‐Selective Microelectrodes
Authors: Sundfors Fredrik , Bereczki Róbert , Bobacka Johan , Tóth Klára , Ivaska Ari , Gyurcsányi Róbert E. 
Published: July 2006

AbstractA novel design and fabrication procedure is proposed for the preparation of robust ionophore based ion‐selective microelectrodes. The essential component of the new design is a microcavity that is formed after recessing a voltammetric inlaid disk type gold microelectrode by chemical etching of the gold microwire. The microcavity of ca. 50 pL volume and 25 μm diameter accommodates the inherently conducting polymeric inner contact and the ion‐selective liquid membrane, which are thereby mechanically protected from the sample environment. As inner contacts poly(3,4‐ethylenedioxythiophene) (PEDOT) films doped with poly(4‐styrenesulfonate) (PSS) and tetrakis[3,5‐bis‐(trifluoromethyl)phenyl]borate (TFPB) electropolymerized from aqueous and organic solvents, respectively, were used. Potassium‐ and calcium‐selective microelectrodes fabricated according to the new procedure exhibited potentiometric characteristics similar to the conventional electrodes. The formation of an aqueous layer below the ion‐selective membrane could be avoided by using the proposed electrode construction.
Trace‐Level Determination of Cs+ Using Membrane‐Based Ion‐Selective Electrodes
Authors: Radu Aleksandar , Peper Shane , Gonczy Chad , Runde Wolfgang , Diamond Dermot 
Published: July 2006

AbstractA membrane‐based ion‐selective electrode (ISE) has been developed for the trace‐level determination of Cs+ in aqueous samples. A systematic evaluation of several ionophores was performed, examining the effect of membrane plasticizer and ion exchanger on sensor selectivity. Poly(vinyl chloride) (PVC)‐based ion‐selective membranes of conventional composition containing calix[6]arene hexaacetic acid hexaethylester as ionophore (Cs I, 10 mmol/kg), bis(2‐ethylhexyl) sebacate (DOS, 66 wt%) as plasticizer, and undecaiodinated closo‐dodecacarborane (UIC, 4.1 mmol/kg) as ion exchanger exhibited superior performance with respect to selectivity over alkali and alkaline earth metal cations. The unbiased selectivity coefficients, log K$\rm{ {_{Cs,J}^{pot}}}$, for the principal interfering ions (J=K+, Na+, Ca2+, and Mg2+) were determined to be −2.9, −4.7, −8.5, and −8.7, respectively. DOS‐plasticized PVC electrodes containing Cs I and UIC were optimized for trace‐level measurements, exhibiting a lower detection limit of 7.9×10−9 M Cs+ (log aCs,LDL=−8.1) in the presence of a 1×10−5 M Na+ background. The utility of the optimized ISEs was demonstrated by determining the concentration of Cs+ in both drinking water and natural water samples.
Synthesis and Characterization of a Novel, Colored Lipophilic Additive for Spectral Imaging the Transport in Ionophore Based Ion‐Selective Membranes
Authors: Móczár Ildikó , Gyurcsányi Róbert E. , Huszthy Péter , Jágerszki Gyula , Tóth Klára , Lindner Ernő 
Published: July 2006

AbstractThe synthesis and application of a novel colored lipophilic additive (2,4,6‐trinitro‐3‐pentadecylphenol (TNPDP)) as optical tracer for imaging membrane transport is presented. It was found that TNPDP (estimated pKa=5.53) does not dissociate completely in the studied membranes, even in the presence of the highly basic ETH 5294 chromoionophore (pKa=12.0). In voltage polarization experiments the TNPDP compounded, ETH 5294 based membranes behaved similarly to fixed site membranes, i.e., the external field did not induce concentration polarization in TNPDP and the protonated chromoionophore. To interpret this peculiar behavior, original methods have been implemented to i) compare the diffusion properties and determine the diffusion coefficients of multiple species in ion‐selective membranes by hyperspectral imaging, and ii) determine the ion pair formation constant of the ETH 5294 with the novel colored lipophilic anion and a commonly used tetraphenylborate derivative by impedance spectroscopy. Using the “merged membrane” method individual diffusion coefficients of (2.39±0.07)×10−8 cm2/s (N=5), and (2.34±0.02)×10−8 cm2/s (N=2) were determined for the unprotonated form of ETH 5294 and for the undissociated form of TNPDP, respectively. Once in combination with a counter anion, the diffusion coefficient of the protonated ETH 5294 depended on the properties of the lipophilic anion in the membrane. The apparent diffusion coefficient of the protonated ETH 5294 were much smaller when paired with TNPDP ((1.8±0.8)×10−9 cm2/s, N=9) than with tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (TFPB) ((1.19±0.42)×10−8 cm2/s, N=5). In agreement, the ion pair formation constants of the ETH 5294 with TNPDP (3.14×104 M−1) were almost three orders of magnitude higher than with TFPB (83 M−1).
Amperometric Glucose Biosensor Based on Entrapment of Glucose Oxidase in a Poly(3,4‐ethylenedioxythiophene) Film
Authors: Nien Po‐Chin , Tung Tsai‐Shih , Ho Kuo‐Chuan 
Published: July 2006

AbstractIn this study, conducting polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT), is used as a matrix for the entrapment of glucose oxidase (GOD) and served as the working electrode for sensing glucose. The monomer, EDOT, is electropolymerized onto the platinum electrode by the cyclic voltammetric (CV) technique, scanned between 0.2 and 1.2 V (vs. Ag/AgCl/saturated KCl) in a phosphate buffer solution (PBS) containing GOD, which is entrapped into the PEDOT film simultaneously. The biosensor senses the reoxidative current of the mediator, ferricinium ions, with a constant applied potential of 0.35 V in the sensing system containing a phosphate buffer solution, ferricinium ions, and glucose. The indirect electrochemical method can efficiently reduce the sensing potential of the glucose. The sensing results show that the linear range of the calibration curve for the glucose concentration lies between 0.1 and 10.0 mM, which is a suitable level in the human body. Besides, the limit of detection and sensing sensitivity on glucose for the biosensor are 0.13 mM and 12.42 mA cm−2 M−1, respectively. The response time of the biosensor, which is defined as the reaction current reaching 95% of the steady‐state current, is about 4–10 s. In the aspects of interferences on ascorbic acid (AA) and uric acid (UA), the sensing currents increased about 9.7% and 39.1%, respectively, when compared to the sensing current of glucose. Moreover, the biosensor shows a good stability in which the sensing current of the electrode retains 80% of its original one over a period of 18 days.
Galvanostatic Polarization of All‐Solid‐State K+‐Selective Electrodes with Polypyrrole Ion‐to‐Electron Transducer
Authors: Pawłowski Paweł , Michalska Agata , Maksymiuk Krzysztof 
Published: July 2006

AbstractInfluence of galvanostatic polarizations on potential vs. logarithm of ion activity dependences of all‐solid‐state ion‐selective electrodes with conducting polymer ion‐to‐electron transducer was studied. As a model system K+‐sensor with polypyrrole solid contact and poly(vinyl chloride) based membrane containing valinomycin was chosen. The influence of the lipophilic salt included to the membrane composition was of special interest.
Choosing the parameters of multiple‐repetition strategies
Authors: Veugen Thijs 
Published: July 2006

AbstractThe class of multiple‐repetition strategies is known to achieve capacity for specific discrete memoryless channels with noiseless feedback. We show, given an arbitrary discrete memoryless channel with noiseless feedback, that the repetition parameters should be chosen close to the self information of a transmission error to maximise the transmission rate. Furthermore, it is indicated how close the channel capacity can be approached in the general case. Finally, we compare some results on a related problem: the capacity of a discrete noiseless channel with constraints on the input symbols. Copyright © 2006 AEIT
Energy barriers of proton transfer reactions between amino acid side chain analogs and water from ab initio calculations
Authors: Herzog Elena , Frigato Tomaso , Helms Volkhard , Lancaster C. Roy D. 
Published: July 2006

AbstractProton transfer reactions were studied in all titratable pairs of amino acid side chains where, under physiologically reasonable conditions, one amino acid may function as a donor and the other one as an acceptor. Energy barriers for shifting the proton from donor to acceptor atom were calculated by electronic structure methods at the MP2/6‐31++G(d,p) level, and the well‐known double‐well potentials were characterized. The energy difference between both minima can be expressed by a parabola using as argument the donor–acceptor distance R(DA). In this work, the fit parameters of the quadratic expression are determined for each donor–acceptor pair. Moreover, it was found previously that the energy barriers of the reactions can be expressed by an analytical expression depending on the distance between donor and acceptor and the energy difference between donor and acceptor bound states. The validity of this approach is supported by the extensive new data set. This new parameterization of proton transfer barriers between titratable amino acid side chains allows us to very efficiently estimate proton transfer probabilities in molecular modelling studies or during classical molecular dynamics simulation of biomolecular systems. © 2006 Wiley Periodicals, Inc.J Comput Chem 27: 1534–1547, 2006
PROFASI: A Monte Carlo simulation package for protein folding and aggregation
Authors: Irbäck Anders , Mohanty Sandipan 
Published: July 2006

AbstractWe present a flexible and efficient program package written in C++, PROFASI, for simulating protein folding and aggregation. The systems are modeled using an all‐atom description of the protein chains with only torsional degrees of freedom, and implicit water. The program package has a modular structure that makes the interaction potential easy to modify. The currently implemented potential is able to fold several peptides with about 20 residues, and has also been used to study aggregation and force‐induced unfolding. The simulation methods implemented in PROFASI are Monte Carlo‐based and include a semilocal move and simulated tempering. Adding new updates is easy. The code runs fast in both single‐ and multi‐chain applications, as is illustrated by several examples. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1548–1555, 2006
Novel thermostable serine collagenase from Thermoactinomyces sp. 21E: purification and some properties
Authors: Petrova Detelina Hristova , Shishkov Stoyan Angelov , Vlahov Stoyan Stefanov 
Published: July 2006

AbstractA thermophilic actinomycete strain Thermoactinomyces sp. 21E producing a highly thermostable serine collagenase was isolated from Bulgarian soil. The collagenase, produced extracellular by Thermoactinomyces sp. 21E, was purified to homogeneity by heat treatment, ultrafiltration, saturation with ammonium sulfate and gel filtration chromatography with a 101‐fold increase in specific activity and 58% recovery. The collagenase has a relative molecular mass of 50000 by SDS‐PAGE. The optimum temperature for the enzyme activity was 60–65 °C in the absence of Ca2+ and 70–75 °C in the presence of Ca2+. About 40% of the original activity remaining after incubation at 85 °C for 30 min in the presence of Ca2+. The optimum pH for the enzyme activity was 9.0–9.5 and the enzyme was stable for 1h at 70 °C in the pH range from 7.5 to 12.5. The collagenase was strongly inhibited by active‐site inhibitors of serine protease PMSF and DFP, which indicated that the enzyme is serine protease. The enzyme activity was completely inhibited by Hg2+, Cu2+ and Fe2+. However, Ca2+ strongly activated the collagenase activity. The collagenase from Thermoactinomyces sp. 21E showed high activity toward type I collagen, acid‐soluble collagen, gelatin and Pz‐PLGPR. However, elastin for collagenase was inert as substrate. The properties of the collagenase from strain 21E suggest that this enzyme is a new collagenolytic protease that differs from the collagenases and serine proteases reported so far. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antibacterial activity of the soy isoflavone genistein
Authors: Hong Hyunki , Landauer Michael R. , Foriska Mark A. , Ledney G. David 
Published: July 2006

AbstractGenistein, a radioprotective soy isoflavone and protein kinase inhibitor, blocks the invasion of pathogenic bacteria in mammalian epithelial cells. The purpose of this study was to evaluate the direct effect of genistein on the survival and growth of the probiotic Lactobacillus reuteri and selected opportunistic bacteria in vitro as a prelude to in vivo use for managing postirradiation sepsis. We evaluated the opportunistic bacterial enteropathogens Escherichia coli, Shigella sonnei, and Staphylococcus aureus as well as Klebsiella pneumoniae and the non‐pathogenic organism, Bacillus anthracis (Sterne). The latter two bacteria are found in the environment and may be of concern in irradiated individuals. A standard in vitro test was employed to evaluate the direct effect of genistein on the bacteria. This test involved determining bacterial colony forming unit (CFU) counts at a single concentration of genistein. In the CFU assays, significant reductions in CFUs were found for S. aureus and B. anthracis when cultured in the presence of 100 μM genistein. However, L. reuteri, E. coli, S. sonnei, and K. pneumoniae were not altered by in vitro culturing in the presence of 100 μM genistein. These results demonstrate the in vitro antimicrobial activity of genistein. Furthermore, the use of genistein in combination with probiotics may augment the effectiveness of antimicrobial therapies currently used in the management of infections, including those induced by ionizing irradiation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Auxotrophic mutant of the cyanobacterium Nostoc muscorum showing absolute requirement of Cs+ or Rb+ for diazotrophy and autotrophy
Authors: Bhargava Santosh , Chauhan Rajendra , Patil Pramod K. , Singh Sarva Daman 
Published: July 2006

AbstractCaesium‐resistant (Cs+‐R) mutant clones of the cyanobacterium Nostoc muscorum were characterized for diazotrophic growth in a medium devoid of Cs+ or Rb+ or both. Cs+‐R phenotype suffered severe genetic damage of a pleiotropic nature affecting diazotrophic growth, chlorophyll a content, nitrogenase activity and photosynthetic O2 evolution. Mutation leading to development of Cs+‐R phenotype could be overcome by availability of Cs+/Rb+. Parent and mutant strains were similar with respect to their Cs+/Rb+ uptake. Available data suggests operation of an efficient coupling of the two incompatible reactions viz. oxygenic photosynthesis and oxygen sensitive N2 fixation in this cyanobacterium. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Purification and characterization of a halotolerant intracellular protease from Bacillus subtilis strain FP‐133
Authors: Setyorini Endang , Kim Young‐Ju , Takenaka Shinji , Murakami Shuichiro , Aoki Kenji 
Published: July 2006

AbstractA halotolerant strain FP‐133, able to grow at concentrations of 0–12.5% (w/v) NaCl, was isolated from a fish paste and identified as Bacillus subtilis . B. subtilis strain FP‐133 produced an intracellular protease which showed catalytic activity under saline conditions. The enzyme was purified to homogeneity 143‐fold with a yield of 0.9%. The purified enzyme showed an optimum activity at a concentration of 5% (w/v) NaCl. After storage in 7.5% (w/v) NaCl at 4 °C for 24 h, the enzyme kept 100% of its activity. The molecular mass of the protease was determined to be 59 kDa by gel filtration; the protein consisted of four subunits each with a molecular mass of 14 kDa. The enzyme showed aminopeptidase activity. It acted on l‐leucyl‐p ‐nitroanilide, l‐leucyl‐β‐naphthylamide, and oligopeptides containing glycine, l‐histidine, or l‐leucine. The Km and V max values for l‐leucyl‐p ‐nitroanilide were 18 µm and 2.2 mm/h mg, respectively. The enzyme was activated by Fe2+, Fe3+, and Ni2+ in synergism with Mg2+. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Infectivity of soilborneFrankiaand mycorrhizae inDiscaria trinervisalong a vegetation gradient in Patagonian soil
Authors: Chaia Eugenia Esther , Fontenla Sonia Beatriz , Vobis Gernot , Wall Luis Gabriel 
Published: July 2006

AbstractThe infective capacities of the nitrogen fixing ActinomyceteFrankiaand arbuscular mycorrhizal fungi from soils near watercourses, along a vegetation gradient, were studied using plant bioassays.Frankiaand arbuscular mycorrhizas capable of infectingDiscaria trinerviswere found at seventeen sites sampled. More specific enumeration of the infective capacities of both microorganisms in relation to environmental factors was performed in seven representative soils of the analysed vegetation zones (rainforest, xeric forest and steppe) using the most probable number method. The highest nodulation capacities ranged from 340 infective units g–1soil, in a steppe marsh devoid of actinorhizas, to 61 in a coastal actinorhizal scrub (in xeric forest). The highest number of infective mycorrhizal units – also found in marsh – was 145. In general, rainforest soils had the lowest values for both microorganisms. Infective units ofFrankiaand arbuscular mycorrhizal fungi in soil were positively correlated (r= 0.89,P< 0.05). Both soilborne symbionts showed the highest infective capacity in semi‐arid conditions nearby watercourse and at the valley bottom location. Tripartite symbiosis was effective in plants inoculated with steppe and xeric forest soils and plants inoculated withFrankiaBCU110501 andGlomus mosseae.Interaction between both symbionts and influence of environmental conditions, in general, would contribute to define comparable trends of their infective capacities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Incidence of Leptosphaerulina crassiasca in symptomless leaves of peanut in southern India
Authors: Suryanarayanan Trichur S. , Murali Thokur S. 
Published: July 2006

AbstractA Loculoascomycete fungus belonging to the genus Leptosphaerulina was found to survive as symptomless endophyte in the leaflets and rachis of peanut plant (TMV 7). Based on morphological and colony characteristics, it is identified as Leptosphaerulina crassiasca, a fungus that causes the pepper spot and leaf scorch diseases in peanut. Although several common endophytic fungi were recovered from the leaves of peanut, L . crassiasca showed a high relative density of infection. Owing to its endophytic nature, its pathogenicity could not be proved by infection studies. However, its identification as L. crassiasca suggests that this pathogen survives as symptomless endophyte in its host. There are limited studies on fungal endophytes of cultivated crops and hence, the present observation underlines the need to know more about the biology of endophytic fungi of crop plants. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microclimates of l'Aven d'Orgnac and other French limestone caves (Chauvet, Esparros, Marsoulas)
Authors: Bourges F. , Genthon P. , Mangin A. , D'Hulst D. 
Published: July 2006

AbstractWe assess the aerodynamics of the atmosphere in some limestone caves using a 5‐year monitoring of the Aven d'Orgnac system, shorter thermal vertical profiling experiments, and comparison with the time series from other French caves. In the first rooms, located under the Aven opening, our records indicate, for each year, a succession of a summer regime characterized by stable parameters (except for the perturbations introduced by tourist visits) and a winter regime, in which the inner air temperature drops and is highly correlated with that outside. Atmospheric composition suggests that during the winter regime the cave is ventilated by the outside air. We show that the onset of the winter regime is governed by a thermo‐convective instability involving the inflow of the outside cold and dense air. Atmospheric temperature and composition allow us to follow the stepwise progression of the winter regime toward the adjacent rooms.In the Salle Plane (SP), a far room of the Orgnac‐Issirac karstic system, in which the winter regime has never been observed, the air temperature is extremely homogeneous and steady, and is characterized by a half‐daily signal of amplitude less than 0.03 °C, which is correlated with the derivative of pressure versus time. This correlation, which is also observed in various other confined caves, may be explained by pressure‐induced temperature changes relaxed in less than 1 h by thermal exchanges with a large volume of rock whose temperature is assumed to be constant.The various microclimates of karstic cave systems should be taken into account for the conservation of the caves open to tourists and for the interpretation of growth laminae of speleothems. Copyright © 2006 Royal Meteorological Society.