bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimizing Biofuel Cell Performance Using a Targeted Mixed Mediator Combination
Authors: Wilkinson Stuart , Klar Jason , Applegarth Shawn 
Published: September 2006

AbstractA study of how mediators might interact with the catabolic pathways of yeast was undertaken with a view towards improving the performance of microbial fuel cells. This work suggests that no single mediator is ideally suited to the task, and that a carefully selected mixture of two targeted mediators (Methylene Blue and Neutral Red) might be optimal. To test this hypothesis a yeast‐catalyzed microbial fuel cell was built and empirically evaluated under different mediation conditions. The results clearly show that a judicious mix of the two mediators can indeed achieve significantly superior performance, in terms of power‐density, than when either mediator is used singly at the same overall concentration.
Real‐Time PCR Sensing by Thermal Conductivity Monitoring
Authors: Noh Seungbeom , Lee Jinsang , Shin Jang‐Kyoo , Lim Geunbae 
Published: September 2006

AbstractTraditional PCR (Polymerase Chain Reaction) technology is based on an end‐point system which confirms the existence of a target DNA sequence by electrophoresis and UV transillumination steps. This process is labor‐intensive and time consuming. A real‐time PCR is the best alternative that can improve problems of analysis time and accuracy. Therefore, we propose a smaller, non‐optical and non‐labeling system with the advantages of an established real‐time PCR. The proposed technique utilizes a variation of the thermal conductivity of the DNA sample with a PCR cycle. We confirmed that thermal conductivity depends on amounts of PCR products.
Electrochemistry of and Redox‐Induced Metal Release from Metallothioneins at a Nafion‐Coated Bismuth Film Electrode
Authors: Xu Maotian , Wu Yihui , Wang Jianxiu , Zhou Feimeng 
Published: September 2006

AbstractNafion‐coated bismuth film electrodes (NCBiFEs) were used to investigate the redox behavior of and metal release from rabbit liver metallothioneins (MTs) in an acetate buffer. Owing to the permselective exchange between positively charged MT molecules and cations in Nafion and the absence of detectable MT adsorption at bismuth surface, a diffusion‐controlled Nernstian redox wave of MTs (Epc=−0.869 V) was observed for the first time. The Nernstian behavior of the diffusing MTs is in contrast to the voltammetric responses of MTs at thin mercury films or Nafion‐coated mercury film electrodes, which either result in the replacement of the metals originally present in MTs by mercury or lead to a noticeable MT adsorption. By avoiding these undesirable features, the NCBiFE provides an excellent milieu for voltammetric studies of different types of MTs and related isoforms, paving the way for studying the redox‐modulated metal transfer of MTs and understanding the biological role of MTs in heavy metal detoxification and essential metal regulations.
Understanding the Electrochemical Reactivity of Bamboo Multiwalled Carbon Nanotubes: the Presence of Oxygenated Species at Tube Ends May not Increase Electron Transfer Kinetics
Authors: Banks Craig E. , Ji Xiaobo , Crossley Alison , Compton Richard G. 
Published: September 2006

AbstractThe result of acid washing multiwalled carbon bamboo nanotubes is explored with voltammetry and X‐ray Photoelectron Spectroscopy; it is found that the presence of oxygenated species formed as a result at the ends of the nanotubes does not measurably change the heterogeneous charge transfer kinetics.
Selenomethionine‐Catalyzed Nickel Ion Reduction at a Mercury Electrode: Applications in the Analysis of Nutritional Supplements
Authors: Banica Florinel Gabriel , Kafar Beata , Skrzypek Sławomira , Ciesielski Witold 
Published: September 2006

AbstractSelenomethionine (SeMet) is a catalyst for Ni2+ reduction at a mercury electrode in a borax buffer at pH around 9 and gives rise to a differential pulse voltammetric peak, A, at −0.74 V vs. the Ag|AgCl, (3 M KCl) reference electrode. Peak current is directly proportional to SeMet concentration over the concentration range 0.4–10 μM. Alkali and alkali‐earth ions depress to some extent the sensitivity but the current‐concentration relationships remains linear even under these conditions. Differential pulse cathodic stripping voltammetry (DPCSV) in 0.01 M borax results in two partially overlapped peaks. The more negative (A, at about −0.74 V) is similar to that recorded with no deposition and is due to the catalysis by nonadsorbed SeMet, whereas the more positive one (B, at about −0.60 V) results from the catalysis by adsorbed SeMet. Only the DPCSV peak A appears if 0.1 M KNO3 is also present along with 0.01 M borax. Stearic acid, which is present in nutritional supplement tablets, improves the separation of the DPCSV peaks. Consequently, the peak B recorded with 0.01 M borax buffer allows determining SeMet in nutritional supplement tablets by the standard addition method and enables discriminating between the organic and inorganic selenium forms.
A new method for fabrication of an integrated indium tin oxide electrode on electrophoresis microchips with amperometric detection and its application for determination of synephrine and hesperidin in pericarpium citri reticulatae
Authors: Wang Wei , Xu Xueqin , Bin Qiu , Ling Jinming , Chen Guonan 
Published: September 2006

AbstractA new, simple, and fast method to integrate indium tin oxide electrode in an amperometric detection (AD) microchip is introduced. Without the help of photoresist and complicated apparatus, the microchip could be fabricated in most laboratories in a very short time by this method. The experiment indicated that the microchip was stable and had good reproducibility. On this microchip, a new method was established to separate and determine synephrine and hesperidin, which are the main electroactively bioactive ingredients of pericarpium citri reticulatae, by AD. Under the optimal conditions, the two compounds could be completely separated within 5.5 min and the detection limits were 0.13 and 0.57 μg/mL, respectively. The proposed method has been successfully used to determine synephrine and hesperidin in real pericarpium citri reticulatae sample, and the results show that the proposed method is sensitive, reliable, fast, and economical.
Speciation of selenium compounds by open tubular capillary electrochromatography‐inductively coupled plasma mass spectrometry
Authors: Lin Shu‐Yu , Wang Guan‐Ren , Huang Quan‐Pin , Liu Chuen‐Ying 
Published: September 2006

AbstractWe introduce a T‐type interface and a crossflow nebulizer to find ways to combine CEC with inductively coupled plasma MS (ICP‐MS) detection for selenium speciation. For CEC separation, we employed a macrocyclic polyamine‐bonded phase capillary as the separation column and a bare fused‐silica capillary filled with the make‐up liquid (0.05 M HNO3). The effect of nebulizer gas flow rate, make‐up liquid flow, type, concentration and pH of the mobile phase on the separation have been studied. Tris buffer of 50 mM at pH 8.50 gave the best performance for selenium speciation. The reproducibility of the retention time indicated that sample injection by electrokinetic and nebulizer gas flow was better than that by self‐aspiration alone. The detection limits for selenate, selenite, selenocystine and selenomethionine were found to be 2.40, 3.53, 12.86 and 11.25 ng/mL, respectively. Due to the high sensitivity and element‐specific detection, as well as the high selectivity of the bonded phase, quantitative analysis of selenium speciation in urine was also achieved.
Adenosine released by astrocytes contributes to hypoxia‐induced modulation of synaptic transmission
Authors: Martín Eduardo D. , Fernández Miriam , Perea Gertrudis , Pascual Olivier , Haydon Philip G. , Araque Alfonso , Ceña Valentín 
Published: September 2006

AbstractAstrocytes play a critical role in brain homeostasis controlling the local environment in normal as well as in pathological conditions, such as during hypoxic/ischemic insult. Since astrocytes have recently been identified as a source for a wide variety of gliotransmitters that modulate synaptic activity, we investigated whether the hypoxia‐induced excitatory synaptic depression might be mediated by adenosine release from astrocytes. We used electrophysiological and Ca2+imaging techniques in hippocampal slices and transgenic mice, in which ATP released from astrocytes is specifically impaired, as well as chemiluminescent and fluorescence photometric Ca2+techniques in purified cultured astrocytes. In hippocampal slices, hypoxia induced a transient depression of excitatory synaptic transmission mediated by activation of presynaptic A1 adenosine receptors. The glia‐specific metabolic inhibitor fluorocitrate (FC) was as effective as the A1 adenosine receptor antagonist CPT in preventing the hypoxia‐induced excitatory synaptic transmission reduction. Furthermore, FC abolished the extracellular adenosine concentration increase during hypoxia in astrocyte cultures. Several lines of evidence suggest that the increase of extracellular adenosine levels during hypoxia does not result from extracellular ATP or cAMP catabolism, and that astrocytes directly release adenosine in response to hypoxia. Adenosine release is negatively modulated by external or internal Ca2+concentrations. Moreover, adenosine transport inhibitors did not modify the hypoxia‐induced effects, suggesting that adenosine was not released by facilitated transport. We conclude that during hypoxia, astrocytes contribute to regulate the excitatory synaptic transmission through the release of adenosine, which acting on A1 adenosine receptors reduces presynaptic transmitter release. Therefore, adenosine release from astrocytes serves as a protective mechanism by down regulating the synaptic activity level during demanding conditions such as transient hypoxia. © 2006 Wiley‐Liss, Inc.
Comparison of alternative methods of collection of service use data for the economic evaluation of health care interventions
Authors: Byford Sarah , Leese Morven , Knapp Martin , Seivewright Helen , Cameron Susan , Jones Vanessa , Davidson Kate , Tyrer Peter 
Published: September 2006

AbstractEconomic evaluation of health care interventions usually requires the collection of service use data to estimate the total cost of participants in an evaluation. There are a number of methods available to measure the quantity of services used but little is known about the relative accuracy of alternative methods. In a multicentre randomised controlled trial of interventions for the treatment of adults with recurrent episodes of deliberate self‐harm (the POPMACT trial), health service data were collected by patient self‐report after six and twelve months and also from GP records by independent investigators. Agreement for overall costs was relatively high. However, this hides substantial variation in agreement between the two sources of information for different services. The results suggest that GP records provide more accurate data on the use of general practice‐based contacts than patient report, but less reliable information on contacts with other health services. Thus reliance on GP records for data on hospital services and other community health services based outside of general practice surgeries is not recommended. Future research should explore the level of agreement between patient report and other providing sector records, such as hospital records. Copyright © 2006 John Wiley & Sons, Ltd.
A Raman spectroscopic study of humite minerals
Authors: Frost Ray L. , Palmer Sara J. , Bouzaid Jocelyn M. , Reddy B. Jagannadha 
Published: September 2006

AbstractRaman spectroscopy has been used to study the structure of the humite mineral group ((A2SiO4)n–A(OH, F)2 where n represents the number of olivine and brucite layers in the structure and is 1, 2, 3 or 4 and A2+ is Mg, Mn, Fe or some mix of these cations). The humite group of minerals forms a morphotropic series with the minerals olivine and brucite. The members of the humite group contain layers of the olivine structure that alternate with layers of the brucite‐like sheets. The minerals are characterized by a complex set of bands in the 800–1000 cm−1 region attributed to the stretching vibrations of the olivine (SiO4)4− units. The number of bands in this region is influenced by the number of olivine layers. Characteristic bending modes of the (SiO4)4− units are observed in the 500–650 cm−1 region. The brucite sheets are characterized by the OH stretching vibrations in the 3475–3625 cm−1 wavenumber region. The position of the OH stretching vibrations is determined by the strength of the hydrogen bond formed between the brucite‐like OH units and the olivine silica layer. The number of olivine sheets and not the chemical composition determines the strength of the hydrogen bonds. Copyright © 2006 John Wiley & Sons, Ltd.
Direct characterization of phase behavior and compatibility in PET/HDPE polymer blends by confocal Raman mapping
Authors: Huan Shuangyan , Lin Weiqi , Sato Harumi , Yang Haifeng , Jiang Jianhui , Ozaki Yukihiro , Wu Hailong , Shen Guoli , Yu Ruqin 
Published: September 2006

AbstractMorphology, chemical distribution and domain size in poly(ethylene terephthalate)/high‐density poly(ethylene) (PET/HDPE) polymer blends of various ratios prepared with and without maleic anhydride have been analyzed with confocal Raman mapping and SEM. The ratioimage method introduced here allows us to obtain enhanced chemical images with higher contrast and reliability. Compatibility numbers (Nc) are calculated to evaluate the compatibility of the blends. The incompatible polymer blends show heterogeneous distribution with phase separation behavior, while the semicompatible blends prepared with maleic anhydride show much smaller subphase distributions with less distinct interphases. After the blending modification by maleic anhydride of only 0.5%, the viscosity status and dispersibility between PET and HDPE could be substantially improved, and the interactions that exist between the two phases have also been proved by ATR‐FT‐IR results. High‐spatial‐resolution confocal Raman mapping coupled with the ratioimage method provides a very attractive way to characterize the compatibility and phase behavior of the polymer blend through different blending methodologies. Copyright © 2006 John Wiley & Sons, Ltd.
Evaluation of residual values of different fertilisers at various rates used in phosphorus recapitalisation of an acid tropical soil
Authors: Gikonyo Esther W , Zaharah Abdul R , Hanafi Mohamed M , Anuar Abdul R 
Published: September 2006

AbstractThe success of ‘phosphorus (P) recapitalisation’ depends on the changes in residual value (RV) over time. RVs of triple superphosphate (TSP), Gafsa phosphate rock (GPR) and Christmas Island phosphate rock (CIPR) were determined with and without manure bimonthly for 14 months. RV was calculated as the amount of previously applied fertiliser required to produce yieldXdivided by the amount of freshly applied TSP required to produce the same yield. Dry matter yield (DMY) response curves were curvilinear, with maximum DMY (11 t ha−1) occurring between 150 and 200 kg P ha−1at 6 months and declining with time to 2–4 t ha−1(14 months). Manure/fertiliser combinations increased DMY for CIPR but depressed DMY for TSP and GPR in all harvests except the first one. This can be attributed to nutrient imbalance caused by high P levels. RVs declined with time for fertilisers alone from 100–140% to 10–20% (14 months), while for fertiliser/manure combinations they declined from 110–180% to 10–20% (14 months). Increasing P rates from 100 to 300 kg P ha−1resulted in the depression of initial RVs (100–140%) to 20–60% and later to 10–20% (14 months). Therefore P recapitalisation was not beneficial and hence annual P application would be recommended at 100–150 kg P ha−1. The phosphate rocks could effectively substitute for TSP.Copyright © 2006 Society of Chemical Industry
Effect on Photopolymerization of the Structure of Amine Coinitiators Contained in Novel Polymeric Benzophenone Photoinitiators
Authors: Wei Jun , Wang Hongyu , Jiang Xuesong , Yin Jie 
Published: September 2006

AbstractSummary: By the polycondensation of TDI with DATBP or AATBP, and different coinitiator amines, six novel thio‐containing polymeric photoinitiators that contain a coinitiator amine and a side‐chain or in‐chain benzophenone (PUSBA or PUIBA) have been synthesized. FT‐IR, 1H NMR, and GPC analyses confirm the structures of all polymers. The UV‐vis spectra indicate that the structure of the coinitiator amines has no significant influence on the maximal absorption. ESR spectra indicate that the polymeric photoinitiators that contain PDEA moieties can generate free radicals most efficiently. Three types of monomer with different functionality, EA, PPGDA, and TMPTA, are chosen to be initiated by these polymeric photoinitiators. The results show that the structure of the coinitiator amines has an important effect on the photopolymerization. For the PUSBA photoinitiators, the photoinitiator that contains N‐phenyldiethanolamine as the coinitiator amine is the most efficient for EA, and that with N‐butyldiethanolamine is the most efficient for both PPGDA and TMPTA. As for the PUIBA photoinitiators, that containing N‐phenyldiethanolamine as the coinitiator amine is the most efficient for the polymerization of the three monomers.Structure of the polymeric photoinitiators with benzophenone moieties in the side chains.magnified imageStructure of the polymeric photoinitiators with benzophenone moieties in the side chains.
Thermo‐responsive Poly(methyl methacrylate)‐block‐poly(N‐isopropylacrylamide) Block Copolymers Synthesized by RAFT Polymerization: Micellization and Gelation
Authors: Tang Tian , Castelletto Valeria , Parras Petros , Hamley Ian W. , King Stephen M. , Roy Debashish , Perrier Sebastien , Hoogenboom Richard , Schubert Ulrich S. 
Published: September 2006

AbstractSummary: RAFT polymerization was used to prepare PMMA‐b‐PNIPAM copolymers. Two different chain transfer agents, tBDB and MCPDB, were used to mediate the sequential polymerizations. Micellar solutions and gels were prepared from the resulting copolymers in aqueous solution. When heated above Tc of PNIPAM (about 31 °C), DLS revealed that PNIPAM coronas collapsed, resulting in aggregation of the original micelles. The micellar gels underwent syneresis above Tc as water was expelled from the ordered gel structure, the lattice periodicity of which was determined by SANS. A large decrease in lattice spacing was observed above Tc. The gel became more viscoelastic at high temperature, as revealed by shear rheometry which showed a large increase in G″.
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Characterization of Linear and 3‐Arm Star Block Copolymers by Liquid Chromatography at Critical Conditions
Authors: Gao Haifeng , Min Ke , Matyjaszewski Krzysztof 
Published: September 2006

AbstractSummary: LCCC for polyMA homopolymers was established in order to analyze the polyMA‐polySt linear and star block copolymers. The validity of the assumption that under the LCCC for polyMA, the polyMA segment in the polyMA‐containing block copolymer is chromatographically “invisible” was verified. It was found that within the scale of investigation ($\overline M _{{\rm n},{\rm polyMA}} \leq 5\;\overline M _{{\rm n},{\rm polySt}}$), the molecular weight and architecture of the polyMA segments had no evident influence on the retention behavior of the polySt‐polyMA block copolymers and the polyMA block in the copolymer was “invisible”. The critical conditions of polyMA were used for quantitative analysis of the polySt block in the linear and 3‐arm star polyMA‐polySt block copolymers, which were synthesized by AGET ATRP in miniemulsion. It was shown that the copolymer had completely different elution peak from its MI. The calculated molecular weights of polySt blocks in the block copolymers were similar to those obtained from normal SEC analysis. Transferring the eluates from the LCCC (the first dimension) column to a SEC column (the second dimension) produced LCCC × SEC two‐dimensional chromatogram, which contained information on both chemical composition and molecular weight of the synthesized copolymers. The combination of these liquid chromatography methods clearly confirmed the high initiation efficiency of the polyMA MIs during the synthesis of block copolymers and the presence of a byproduct formed by radical‐radical coupling.
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Progress in type II dehydroquinase inhibitors: From concept to practice
Authors: González‐Bello Concepción , Castedo Luis 
Published: September 2006

AbstractScientists are concerned by an ever‐increasing rise in bacterial resistance to antibiotics, particularly in diseases such as malaria, toxoplasmosis, tuberculosis, and pneumonia, where the currently used therapies become progressively less efficient. It is therefore necessary to develop new, safe, and more efficient antibiotics. Recently, the existence of the shikimic acid pathway has been demonstrated in certain parasites such as the malaria parasite. These types of parasites cause more than a million casualties per year, and their effects are particularly strong in people with a compromised immune system such as HIV patients. In such cases it is possible that inhibitors of this pathway could be active against a large variety of microorganisms responsible for the more opportunistic infections in HIV patients. Interest in this pathway has resulted in the development of a wide variety of inhibitors for the enzymes involved. This review covers recent progress made in the development of inhibitors of the third enzyme of this pathway, i.e., the type II dehydroquinase. The X‐ray crystal structures of several dehydroquinases (Streptomyces coelicolor, Mycobacterium tuberculosis, etc.) with an inhibitor bound in the active site have recently been solved. These complexes identified a number of key interactions involved in inhibitor binding and have shed light on several aspects of the catalytic mechanism. These crystal structures have also proven to be a useful tool for the design of potent and selective enzyme inhibitors, a feature that will also be discussed. © 2006 Wiley Periodicals, Inc. Med Res Rev
Natural vibration characteristics of gravity structures
Authors: Chugh Ashok K. 
Published: September 2006

AbstractA forced vibration procedure is presented to estimate fundamental and higher frequencies of vibrations and associated mode shapes of gravity structures. The gravity structures considered are retaining walls and gravity dams. The validity of the proposed procedure is tested on three test problems of varying complexity for which the natural vibration frequencies and mode shapes either have known analytical solutions or have been determined via numerical means/field tests by others. Also included are the results of natural vibration frequencies and associated mode shapes for a spillway control structure located near the abutment end of an embankment dam obtained using the proposed procedure. For all problems considered, fundamental frequency and mode shape results using the proposed procedure are compared with the results obtained using an alternative procedure in which static deflections due to the structure's own weight are used as the starting point for free vibrations by setting the gravity vector to zero. All results compare well. The merits of the proposed procedure are discussed. Published in 2006 by John Wiley & Sons, Ltd.