bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Siderophore Isolated from Streptomyces sp. TM‐34 with Potent Inhibitory Activity Against Angiotensin‐Converting Enzyme
Authors: Kodani Shinya , Ohnishi‐Kameyama Mayumi , Yoshida Mitsuru , Ochi Kozo 
Published: May 2011

AbstractA new siderophore named tsukubachelin was isolated from an iron‐deficient culture medium of newly isolated strain Streptomyces sp. TM‐34. The chemical structure of tsukubachelin was established by the interpretation of 2D NMR and TOF‐Mass spectroscopic data. The structure of tsukubachelin consists of six amino acid residues, including three serine, and one each of N‐α‐methyl‐N‐δ‐hydroxy‐N‐δ‐formylornithine, N‐α‐methyl‐N‐δ‐hydroxyornithine, and cyclic N‐hydroxyornithine. Because the structurally related siderophore, desferri‐foroximithine, was reported to have potent angiotensin‐converting enzyme inhibition activity, the inhibitory activity of desferri‐tsukubachelin and desferri‐foroximithine were tested for structure–activity comparison. Desferri‐tsukubachelin showed 14 times more potent inhibitory activity than desferri‐foroximithine. This result indicates that desferri‐tsukubachelin may become a promising agent for angiotensin‐converting enzyme inhibition.
Synthesis and Aggregation Properties of Two‐ and Three‐Armed Nitrogen‐Rich Chelate Ligands: Novel Bis(N‐acylamidines), Tris(N‐acylamidines) and Bis(triazapentadienes) with Flexible or Rigid Spacers
Authors: Clodt Juliana Isabel , Wigbers Christof , Reiermann Ralph , Fröhlich Roland , Würthwein Ernst‐Ulrich 
Published: May 2011

AbstractTwo‐ and three‐armed ligands, like bis(N‐acylamidines) 7 and 9, tris(N‐acylamidines) 8 and bis(1,3,5‐triazapenta‐1,3‐dienes) 10 with different spacers between the ligand moieties, have been easily prepared in moderate‐to‐good yields starting from diamines, triamines or dicarboxylic acid derivatives. Thus, the reaction of diamines and triamines with N‐acylimidates 3 led to bis(N‐acylamidines) 7 and tris(N‐acylamidines) 8, respectively, linked through the amino group. Ligands 9, interconnected through the carbonyl groups, were obtained starting from dicarboxylic acid dichlorides and amidines. Bis(triazapentadienes) 10, linked through carbon atoms, were synthesized from a diamide, which was converted into a bis(N‐imidoylimidate) 17 followed by reactions with deprotonated amines. These compounds show variable aggregation behaviour in the solid state as a result of intra‐ and intermolecular hydrogen bonding. All compounds were thoroughly characterized including by X‐ray diffraction.
Intermolecular Phosphoryl Transfer of N‐Phosphoryl Amino Acids
Authors: Gao Xiang , Deng Honggui , Tang Guo , Liu Yan , Xu Pengxiang , Zhao Yufen 
Published: May 2011

AbstractN‐Phosphoryl amino acids (NPAAs) are a novel series of N‐terminal‐activated amino acids that act as the energy source and phosphoryl donor in intra‐ and intermolecular phosphoryl transfer to form “high‐energy” species, such as acetyl phosphate and aminoacyl phosphates, and in the self‐assembled synthesis of polypeptides under mild aqueous conditions. In this work, the chemical reactivity of N‐mono(methoxyphosphoryl)glycine as a representative was investigated in detail by using a combination of the stable‐isotope‐labeling (15N) technique, 31P NMR, ESI‐MS/MS and LC‐MS. The phosphoryl group of NPAAs can be transferred intermolecularly to the carboxy group of another molecule through intramolecular cyclic pentacoordinate phosphoric–amino acid anhydride intermediates. In addition to C‐terminal activation by phosphate anhydride, amino acids can also be self‐activated by N‐phosphorylation. This information not only provides some interesting clues for understanding the active role of the phosphoryl group in living systems, but also shows that the origin of life might be attributed to the chemical evolution of N‐phosphoryl amino acids.
Schiff Bases from TRIS and ortho‐Hydroxyarenecarbaldehydes: Structures and Tautomeric Equilibria in the Solid State and in Solution
Authors: Martínez R. Fernando , Ávalos Martín , Babiano Reyes , Cintas Pedro , Jiménez José L. , Light Mark E. , Palacios Juan C. 
Published: May 2011

AbstractThree Schiff bases generated by conventional condensation of a simple aminopolyol (TRIS) and 5‐bromo‐ and 5‐iodosalicylaldehyde, and 2‐hydroxy‐1‐naphthaldehyde, have been fully characterized, both in solution and in the solid state. This study provides a complete analysis of imine–enamine equilibria, and sheds light onto the mechanism of hydrogen transfer, which has been controversial in the literature. Low‐temperature X‐ray diffraction accompanied by electron‐density maps have further been complemented by theoretical studies at the B3LYP/6‐31G* and M06‐2X/6‐311++G** levels. To ascertain the influence of crystal packing on tautomeric stability, the lattice has also been simulated by computation. This protocol involves the assessment of a supramolecular cluster around a core tautomer possessing either imine or enamine structures. Such an analysis, in full agreement with solid‐state data, reveals the greater stability of zwitterionic structures for the salicyl derivatives. In contrast, these substances show preferential imine forms in solution, whereas the naphthyl‐based compound exhibits a prevalent keto‐enamine structure in all cases.
Synthesis of Tn/T Antigen MUC1 Glycopeptide BSA Conjugates and Their Evaluation as Vaccines
Authors: Cai Hui , Huang Zhi‐Hua , Shi Lei , Zou Peng , Zhao Yu‐Fen , Kunz Horst , Li Yan‐Mei 
Published: May 2011

AbstractThe tumor‐associated mucin MUC1 over‐expressed in most epithelial tumor tissues is considered a promising target for immunotherapy. The extracellular part of MUC1 contains a domain of numerous tandem repeats of the amino acid sequence HGVTSAPDTRPAPGSTAPPA, including five potential O‐glycosylation sites. In this study, T9 and S15 have been chosen as the positions of glycosylation. The glycopeptides N‐terminally equipped with a triethylene glycol spacer were synthesized by microwave‐assisted Fmoc solid‐phase peptide synthesis. After detachment from the resin and deprotection, the MUC1 glycopeptides were conjugated to bovine serum albumin (BSA). To evaluate the immunological properties, balb/c mice were immunized with these BSA vaccines.
Chiral Heterodisulfoxide Ligands in Rhodium‐Catalyzed Asymmetric 1,4‐Addition of Arylboronic Acids to Chromenones
Authors: Han Fuzhong , Chen Guihua , Zhang Xiangyang , Liao Jian 
Published: May 2011

AbstractA new family of benzene‐based chiral heterodisulfoxide ligands L1–L5 was synthesized in a single step. These disulfoxide ligands were applied in the rhodium‐catalyzed asymmetric 1,4‐addition of arylboronic acids to chromenones. The addition of diverse arylboronic acids to chromenones proceeds smoothly in up to 70 % yield with up to 95 % ee.
Anthradithiophene Derivatives Substituted at the 2,8‐Positions by Formyl and Triphenylamine Units: Synthesis, Optical, and Electrochemical Properties
Authors: Balandier Jean‐Yves , Sebaihi Noham , Boudard Pol , Lemaur Vincent , Quist Florence , Niebel Claude , Stas Sara , Tylleman Benoît , Lazzaroni Roberto , Cornil Jérôme , Geerts Yves Henri 
Published: May 2011

AbstractThe synthesis and characterization of two new anthradithiophene (ADT) derivatives substituted by thiophenyl or 2‐octylthiophenyl units at the 5,11‐positions and donor (triphenylamine) or acceptor (aldehyde functions) moieties at the 2,8‐positions of their backbone are described. Optical measurements were performed to evaluate the effect of electron‐rich/‐poor substituents on their stability towards photo‐oxidation and were supported by quantum chemical calculations and cyclic voltammetry experiments.
Anodic Stripping Voltammetric Determination of Iron(II) at a Carbon Paste Electrode Modified with Dithiodianiline (DTDA) and Gold Nanoparticles (GNP)
Authors: Gholivand Mohammad Bagher , Geravandi Behrooz , Parvin Mohammad Hadi 
Published: May 2011

AbstractA differential pulse anodic stripping voltammetric procedure was developed for the determination of trace amounts of iron(II) in the presence of iron(III) at a carbon paste electrode (CPE) modified with dithiodianiline and gold nanoparticle. At the pH working of 3.0, a wide concentration range from 0.1 nM to 100 nM was observed with the detection limit of 0.05 nM. The relative standard deviation for a solution containing 50 nM of iron(II) was found to be 3.11 % (n=9). Possible interferences from the coexisting ions were also investigated. The validity of the method and applicability of the sensor were successfully tested by determining of iron(II) in lentil, wheat seed and barley seed samples.
Comparison of Multi‐walled Carbon Nanotubes and Poly(3‐octylthiophene) as Ion‐to‐Electron Transducers in All‐Solid‐State Potassium Ion‐Selective Electrodes
Authors: Mousavi Zekra , Teter Agnieszka , Lewenstam Andrzej , Maj‐Zurawska Magdalena , Ivaska Ari , Bobacka Johan 
Published: May 2011

AbstractMulti‐walled carbon nanotubes (MWCNTs) were compared with poly(3‐octylthiophene) (POT) as ion‐to‐electron transducer in all‐solid‐state potassium ion‐selective electrodes with valinomycin‐based ion‐selective membranes. MWCNTs and POT were mixed with the other components of the potassium ion‐selective membrane cocktail (valinomycin, KTpClPB, o‐NPOE, PVC, THF) which was then applied on a glassy carbon (GC) substrate to prepare single‐piece ion‐selective electrodes (SPISEs). Results from potentiometric and impedance measurements showed that the MWCNT‐based electrodes have a more reproducuible standard potential and a lower overall impedance than the electrodes based on POT. Both types of electrodes showed similar sensitivity to potassium ions and no redox sensitivity.
Application of Square Wave Anodic Stripping Voltammetry for Determination of Traces of Ti(I) at Carbon Electrodes In Situ Modified with Bi Films
Authors: Caldeira Alexandra , Gouveia‐Caridade Carla , Pauliukaite Rasa , Brett Christopher M. A. 
Published: May 2011

AbstractBismuth films deposited in situ at glassy carbon and carbon film electrodes were tested for the determination of traces of Tl(I) separately and together with Zn(II) and Pb (II), in acetate buffer solution pH 3.7, using square wave anodic stripping voltammetry. Electrochemical impedance spectra in the presence of Tl(I) showed differences between the electrode substrates. The sensitivity to Tl does not depend on the presence of other ions, and was better at carbon film electrodes, although the 2 nmol L−1 detection limit was independent of electrode substrate. Application to the measurement of Tl(I) in commercial berry juice is demonstrated.
Carbon Nanoparticle Surface Electrochemistry: High‐Density Covalent Immobilisation and Pore‐Reactivity of 9,10‐Anthraquinone
Authors: Watkins John D. , Lawrence Katherine , Taylor James E. , James Tony D. , Bull Steven D. , Marken Frank 
Published: May 2011

Abstract2‐Bromomethyl‐9,10‐anthraquinone is covalently bound to carbon nanoparticle surfaces (Emperor 2000, Cabot Corp., with sulphonamide groups, ca. 9 to 18 nm diameter) with a coverage of ca. 250 anthraquinone molecules per particle (ca. 180 Å2 per anthraquinone). The resulting hydrophobic carbon particles are dispersed in ethanol and coated onto glassy carbon electrodes. Electrochemical experiments are reported demonstrating the effect of surface coverage, scan rate, and pH. A linear shift in reversible potential of ca. 59 mV per pH unit from pH 2 to 12 is observed consistent with the reversible 2‐electron 2‐proton reduction of anthraquinone. High density of anthraquinone in carbon nanoparticle aggregates causes buffer capacity effects. Binding of hydrophobic tetraphenylborate anions into carbon nanoparticle aggregate pores is demonstrated. Applications in buffer characterisation and pH‐sensing are discussed.
Forward likelihood‐based predictive approach for space–time point processes
Authors: Chiodi Marcello , Adelfio Giada 
Published: May 2011

AbstractDealing with data from a space–time point process, the estimation of the conditional intensity function is a crucial issue even if a complete definition of a parametric model is not available. In particular, in case of exploratory contexts or if we want to assess the adequacy of a specific parametric model, some kind of nonparametric estimation procedure could be useful.Often, for these purposes kernel estimators are used and the estimation of the intensity function depends on the estimation of bandwidth parameters. In some fields, like for instance the seismological one, predictive properties of the estimated intensity function are pursued. Since a direct ML approach cannot be used, we propose an estimation procedure based on the subsequent increments of likelihood obtained adding an observation one at a time. Simulated results and some applications to statistical seismology are provided. Copyright © 2011 John Wiley & Sons, Ltd.
Quantifying local and background contributions to PM10 concentrations in Haute‐Normandie, using random forests
Authors: Bobbia Michel , Jollois François‐Xavier , Poggi Jean‐Michel , Portier Bruno 
Published: May 2011

AbstractThe problem is to quantify local and background contributions to PM10 concentrations in Haute‐Normandie region. We use measures of pollution variables on a network of 11 monitoring sites, completed by meteorological variables, during 2004–2009. Random forests (RFs), a recent statistical method, are used to put in evidence the marginal effects of explanatory variables, and to classify parameters of influence on PM10 pollution in different situations: roadside, urban background, industrial, and rural. The local pollution is the most important source and is marked by the classic tracers NO and NO2 as urban activity pollution, and SO2 as industrial one. The entire process of statistical quantification of local and background contributions, without neither direct information nor measurements about sources, can be divided in three main steps. The first one is to classify the explanatory variables (pollutants and meteorological parameters) into five groups: pollutants from urban activity, pollutants from industrial activity, and three groups of meteorological variables. The second step is to handle the specificity of a rural and coastal station for which there is a priori no local pollution sources, to use it as a marker of the background pollution. The final step consists of quantifying the local and background contributions to the PM10 pollution, using only markers of urban and industrial activities and PM10 background. As a synthetic conclusion, it appears as often seen in publications about other geographical locations, that the local part contributes half of the total pollution. Copyright © 2011 John Wiley & Sons, Ltd.
Global optimization of wastewater integration networks for processes with multiple contaminants
Authors: Nápoles‐Rivera Fabricio , Ponce‐Ortega José María , El‐Halwagi Mahmoud M. , Jiménez‐Gutiérrez Arturo 
Published: May 2011

AbstractA formulation for the global optimization of recycle and reuse mass integration networks is presented. In addition to direct recycle, the model includes adding in‐plant interceptors and terminal treatment systems. The model also considers wastewater streams with multiple contaminants. Because of the nonlinear and nonconvex nature of the optimization model, a two‐tier approach is proposed along with a simplifying superstructure. First, a presynthesis problem is solved to identify the performance and cost of interceptors with specific tasks. Next, a representation that avoids the mixing of different streams in the treatment system is formulated. As a result, linear relationships on the mass balances are obtained, which implies that the model can be solved for global optimality. An application to a real case study of a refinery system is carried out. When compared to the original system and to the results provided by an integration based on a simple direct recycle strategy, the results show that significant reductions in fresh sources consumption and waste generated can be achieved with the application of the proposed integration framework. © 2011 American Institute of Chemical Engineers Environ Prog, 2011
Acid blue 92 photocatalytic degradation in the presence of scavengers by two types photocatalyst
Authors: Elahifard Mohammad Reza , Gholami Mohammad Reza 
Published: May 2011

AbstractTwo types of nanosized photocatalyst, TiO2 P‐25 and ap/Ag/AgBr/TiO2, were used for decolorization of Acid Blue 92 (AB92) in dark, visible light (V‐L), and UV media. Under UV and V‐L, the effect of three possible photodegradation processes of AB92 including photocatalytic degradation, self‐photosensitization, and direct photolysis were studied. Results showed that in UV/photocatalysts, photocatalytic degradation is the major process for photodecolorization. However, in the presence of TiO2, self‐photosensitization has the major role under V‐L. Because of the presence of AgBr as photoactive center in ap/Ag/AgBr/TiO2, the main process is the photocatalytic degradation in V‐L. By using isopropanol and catalase as •OH and H2O2 scavenger, the results showed that in ap/Ag/AgBr/TiO2, •OH and hole act as AB92 oxidizer, respectively, while in TiO2, •OH, hole, and also H2O2 play that role. Meanwhile, AB92 showed a different regular behavior with KI in photodegradation processes. This phenomena is assisted by the formation of I2 in photocatalytic process. By direct oxidation, I2 increases the reaction rate and shifts the maximum wavelength absorption of AB92. © 2011 American Institute of Chemical Engineers Environ Prog, 2011
Spatial and temporal controls on historical channel responses – study of an atypical case: Someşu Mic River, Romania
Authors: Perşoiu Ioana , Rădoane Maria 
Published: May 2011

AbstractIn this paper the spatial and temporal responses of the Someşu Mic River (Romania) to natural and anthropogenic controls over the past 150 years are analysed, based on a series of morphometric parameters extracted from five successive sets of topographic maps and one set of orthophotos. Prior to the intensive hydrotechnical interventions of the last four decades, the river was characterized by a complex alternation of different channel types, resulting in a mixture of alluvial and mixed sinuous – meandering – sinuous anabranched – meandering anabranched reaches, each a few hundred metres to a few kilometres long. The main cause for this spatial behaviour was the local geology. Its effects were intensified by a larger scale slope, slightly higher than along a longitudinal profile with normal concavity, as a consequence of the presence of a 400 m elevation knick‐point located in the catchment area.A generalized maintenance of river in the floodplain perimeter during the entire interval of study (centennial scale), with local planform adjustments and lack of median scale avulsion in lateral tilting areas and along the anabranched reaches, channel lengthening and meander development during hydrological stable periods and channel shortening and increasing of natural cutoffs during periods with higher incidence of floods (decadal scale), and the incapacity of local morphologic changes resulted from human interventions to completely counterbalance general trends (decadal scale), supports the idea of decreasing the amplitude and frequency of important floods, after the end of the Little Ice Age.Channel metamorphosis by canalization, diminishing/elimination of overflows and medium‐scale avulsions by changes in flow regimes (dams) and the presence of dykes in the floodplain perimeter, channel narrowing (43%) and incision (at least after 1945) downstream from dams, and probably because of in‐channel gravel mining are the main anthropically induced changes along the Someşu Mic River. Even if human impact is important, both at the drainage basin scale and along the Someşu Mic River, it has only local impacts, subordinated to climate. The low level of human impact on this river could be the consequence of the higher general slope downstream from 400 m elevation knick‐point, which probably forces the positioning of its effects under an important internal threshold of the fluvial system. This boundary condition defines Someşu Mic River as an atypical river. This study supports the idea that climate has a more important role in the post‐Little Ice Age (LIA) rivers' behaviour than currently accepted. Copyright © 2011 John Wiley & Sons, Ltd.
Performance Assessment of a Combined PEM Fuel Cell and Triple‐Effect Absorption Cooling System for Cogeneration Applications
Authors: Ratlamwala T. A. H. , Gadalla M. A. , Dincer I. 
Published: May 2011

AbstractIn this paper, a parametric study of a combined proton exchange membrane (PEM) fuel cell and triple‐effect absorption cooling system (TEACS) is undertaken to investigate the effect of different operating conditions and system parameters on the COPs, efficiency of the fuel cell and the integrated system's overall utilisation factor. It is found that the fuel cell efficiency increases from 40% to 44.5% as the operating temperature of the fuel cell increases. However, as the fuel cell's temperature and current density increase, the COPs decrease from 2.4 to 0.9 as a result of the increase in the energy output of the fuel cell ranging from 7.4 to 10.7 kW. The efficiency of the fuel cell decreases from 41% to 32% with an increase in both fuel cell's current density and membrane thickness. The overall utilisation factor of the integrated system decreases from 84% to 35% with an increase in the current density and molar flow rate. Finally, this study reveals that the present integrated PEM fuel cell unit with a TEACS can be considered as an attractive and environmentally benign option for cogeneration purposes in sustainable buildings.
Thermal Behaviours and Single Cell Performance of PBI‐OO/PFSA Blend Membranes Composited with Lewis Acid Nanoparticles for Intermediate Temperature DMFC Application
Authors: Hu J. , Luo J. , Wagner P. , Agert C. , Conrad O. 
Published: May 2011

AbstractBuilding on the improved proton conductivity at intermediate temperatures under anhydrous conditions using a ‘proton donor–proton acceptor' concept demonstrated for the first time in the composite membrane made of inorganic lewis acid (boron‐based electron‐deficient nanoparticles) and a poly‐[(1‐(4,4′‐diphenylether)‐5‐oxybenzimidazole)‐benzimidazole] (PBI‐OO)/perfluorosulfonic acid (PFSA) blend, we report here the thermal behaviours and direct methanol fuel cell (DMFC) single cell performance of these membranes at intermediate temperatures (90–120 °C). It is found that the PFSA/PBI‐OO blends and PFSA/PBI‐OO/nano‐BN composites show decreased thermal stability compared to pristine PFSA. We attribute this to a proton transfer reaction between the sulfonic acid and imidazole moieties of the constituent polymers inducing a decreased stability of the resulting sulfonate group. When operated with dry oxygen and methanol/water vapour, the single cell performance of PFSA/PBI‐OO blends is slightly improved compared to that of pristine PFSA. The PFSA/PBI‐OO/nano‐BN composite membranes exhibit much better single cell performance at intermediate temperatures, which could be mainly attributed to its higher anhydrous proton conductivity.
Preliminary Study on Direct Operation of LT‐SOFCs Based on GDC Electrolyte Film With DME Fuel
Authors: Ding J. , Liu J. , Feng Y. , Yin G. 
Published: May 2011

AbstractDirect operation of anode‐supported cone‐shaped tubular low temperature solid oxide fuel cells (LT‐SOFCs) based on gadolinia‐doped ceria (GDC) electrolyte film with dimethyl ether (DME) fuel was preliminarily investigated in this study. The single cell exhibited maximum power densities of 500 and 350 mW cm–2 at 600 °C using moist hydrogen and DME as fuel, respectively. A durability test of the single NiO‐GDC/GDC/LSCF‐GDC cell was performed at a constant current of 0.1 A directly fuelled with DME for about 200 min at 600 °C. The results indicate that the single cell coking easily directly operated in DME fuel. EDX result shows a clear evidence of carbon deposition in the anode. Further studies are needed to develop the novel anti‐carbon anode materials, relate the carbon deposition with anode microstructure and cell‐operating condition.