bluuebunny/crossref_metadata_2025_split huggingface dataset:
Marine Archaeogeophysical Prospection of Roman Salapia Settlement (Puglia, Italy): Detecting Ancient Harbour Remains
Authors: Cocchi L. , Stefanelli P. , Carmisciano C. , Caratori Tontini F. , Taramaschi L. , Cipriani S. 
Published: March 2012

ABSTRACTThe Gulf of Manfredonia and the Tavoliere Plain have experienced intense human colonization since the neolithic times. There is past evidence in the study area of a Roman‐age settlement historically known as Salapia, probably located close to the salt‐production ponds. In particular, several portions of a partly submerged ancient pier‐like structure were found close to Torre Pietra town. This structure has been interpreted as a portion of a dragged‐ship channel that connected the town of Salapia to the sea. In this article we discuss the results of a high‐resolution geophysical prospecting of the Margherita di Savoia offshore archaeological site (Puglia, Italy). We collected magnetic gradiometric and bathymetric data to map the submerged remains of Salapia harbour. We found evidence of an offshore projection of a Torre Pietra pier‐like structure, identifying the direction of the ship channel and possibly the location of the harbour's defensive post. Copyright © 2012 John Wiley & Sons, Ltd.
Superior Electrochemical Performance of Sulfur/Graphene Nanocomposite Material for High‐Capacity Lithium–Sulfur Batteries
Authors: Wang Bei , Li Kefei , Su Dawei , Ahn Hyojun , Wang Guoxiu 
Published: March 2012

AbstractSulfur/graphene nanocomposite material has been prepared by incorporating sulfur into the graphene frameworks through a melting process. Field‐emission scanning electron microscope analysis shows a homogeneous distribution of sulfur in the graphene nanosheet matrix. The sulfur/graphene nanocomposite exhibits a super‐high lithium‐storage capacity of 1580 mAh g−1 and a satisfactory cycling performance in lithium–sulfur cells. The enhancement of the reversible capacity and cycle life could be attributed to the flexible graphene nanosheet matrix, which acts as a conducting medium and a physical buffer to cushion the volume change of sulfur during the lithiation and delithiation process. Graphene‐based nanocomposites can significantly improve the electrochemical performance of lithium–sulfur batteries.
Quadruple Click: A Facile Pathway leading to Tetrakis(4‐(1,2,3‐triazolyl)methyl)‐ethylenediamine Derivatives as a New Class of Extracting Agents for Soft Metal Ions
Authors: Watanabe Wataru , Maekawa Tetsuya , Miyazaki Yuji , Kida Tatsuya , Takeshita Kenji , Mori Atsunori 
Published: March 2012

AbstractTetrakis(triazolylmethyl)ethylenediamine, which is a class of tetrakis(2‐pyridylmethyl)ethylenediamine (TPEN) analogue, is synthesized by a quadruple click reaction of tetrapropargylated ethylenediamine and four equivalents of alkyl azide. The obtained compound efficiently extracted the soft metal cadmium(II) ions by solvent extraction. It is also found that an N‐isopropylacryl amide (NIPA) gel using the triazole ethylenediamine as a cross‐linker exhibits a temperature‐dependent extraction performance.
A Joss–Waldvogel disdrometer derived rainfall estimation study by collocated tipping bucket and rapid response rain gauges
Authors: Islam Tanvir , Rico‐Ramirez Miguel A. , Han Dawei , Srivastava Prashant K. 
Published: March 2012

AbstractThis article studies the rainfall estimates derived from a Joss–Waldvogel disdrometer, using an extensive dataset of raindrop spectra for the period of 2003–2010. Four rain gauges (one tipping bucket and three rapid response drop counting devices) are employed for the appraisal with the disdrometer observations. The appraisal has been carried out in view of hourly rainfall accumulations, time series accumulative rainfall, and rain rate observations. From the yearly timescale statistics, the correlation between the disdrometer derived hourly rain accumulations to those measured by the rain gauges are in the range of 0.89–0.99 (mean absolute error, 0.10–0.45 mm, and normalized mean bias −1.03% to −50.28%). Especially, the estimated rainfall by the tipping bucket rain gauge is in sound agreement with the disdrometer observations, which is also reflected in time series accumulative rainfall comparisons, showing no more than 20% differences roughly. On the other hand, the results reveal that regardless of any influence of the integration period, the agreement between the disdrometer and the three rapid response rain gauges are quite consistent. Nevertheless, the association of the tipping bucket rain gauge is sensitive to the integration periods. In fact, increasing the integration period improves the rain rates agreement. Further to the appraisal for various rain classes, there is an underestimation to overestimation trend of disdrometer estimated rain rates with the increase of rain classes. Copyright © 2012 Royal Meteorological Society
Semantic Coherence and Inconsistency in Estimating Conditional Probabilities
Authors: Wolfe Christopher R. , Fisher Christopher R. , Reyna Valerie F. 
Published: March 2012

ABSTRACTTwo studies examined semantic coherence and internal inconsistency fallacies in conditional probability estimation. Problems reflected five distinct relationships between two sets: identical sets, mutually exclusive sets, subsets, overlapping sets, and independent sets (a special case of overlapping sets). Participants estimated P(A), P(B), P(A|B), and P(B|A). Inconsistency occurs when this constellation of estimates does not conform to Bayes' theorem. Semantic coherence occurs when this constellation of estimates is consistent with the depicted relationship among sets. Fuzzy‐trace theory predicts that people have difficulty with overlapping sets and subsets because they require class‐inclusion reasoning. On these problems, people are vulnerable to denominator neglect, the tendency to ignore relevant denominators, making the gist more difficult to discern. Independent sets are simplified by the gist understanding that P(A) provides no information about P(B), and thus, P(A|B) = P(A). The gist for identical sets is that P(A|B) = 1.0, and the gist of mutually exclusive sets is that P(A|B) = 0. In Study 1, identical, mutually exclusive, and independent sets yielded superior performance (in internal inconsistency and semantic coherence) than subsets and overlapping sets. For subsets and overlapping sets, interventions clarifying appropriate denominators generally improved semantic coherence and inconsistency, including teaching people to use Euler diagrams, 2 × 2 tables, or relative frequencies. In Study 2, with problems about breast cancer and BRCA mutations, there was a strong correlation between inconsistency in conditional probability estimation and conjunction fallacies of joint probability estimation, suggesting that similar fallacious reasoning processes produce these errors. Copyright © 2012 John Wiley & Sons, Ltd.
Engineered Bacteriorhodopsin: A Molecular Scale Potential Switch
Authors: Patil Amol V. , Premaraban Thenuhan , Berthoumieu Olivia , Watts Anthony , Davis Jason J. 
Published: March 2012

AbstractBacteriorhodopsin, BR, is a natural, photoresponsive, biomolecule that has potential application in data storage, imaging and sensing. Being membrane‐bound, however, it is coupled with metallic electronic surfaces only with some difficulty. We report herein a facile method to generate uniformly orientated, anchored and active monolayers of BR on metallic electrodes. In the present study, the cytoplasmic side of the BR is equipped with an engineered cysteine to achieve largely lipid‐free, orientation‐specific, highly stable, covalent immobilization on gold surfaces. By using non‐invasive Kelvin probe force microscopy, it is possible to measure the light‐induced proton accumulation at the extracellular protein surface at truly molecular scales. The intimate probe–BR interaction possible on lipid removal facilitates the detection of photoinduced surface potential switching substantially larger ((20.4±7.5) mV) with functional single delipidated mutant BR trimers than for the wild‐type protein. The proton pumping detected is also notably highly unidirectional with the orientated protein.
Bifunctional Rhenium Complexes for the Catalytic Transfer‐Hydrogenation Reactions of Ketones and Imines
Authors: Landwehr Anne , Dudle Balz , Fox Thomas , Blacque Olivier , Berke Heinz 
Published: March 2012

AbstractThe silyloxycyclopentadienyl hydride complexes [Re(H)(NO)(PR3)(C5H4OSiMe2tBu)] (R=iPr (3 a), Cy (3 b)) were obtained by the reaction of [Re(H)(Br)(NO)(PR3)2] (R=iPr, Cy) with Li[C5H4OSiMe2tBu]. The ligand–metal bifunctional rhenium catalysts [Re(H)(NO)(PR3)(C5H4OH)] (R=iPr (5 a), Cy (5 b)) were prepared from compounds 3 a and 3 b by silyl deprotection with TBAF and subsequent acidification of the intermediate salts [Re(H)(NO)(PR3)(C5H4O)][NBu4] (R=iPr (4 a), Cy (4 b)) with NH4Br. In nonpolar solvents, compounds 5 a and 5 b formed an equilibrium with the isomerized trans‐dihydride cyclopentadienone species [Re(H)2(NO)(PR3)(C5H4O)] (6 a,b). Deuterium‐labeling studies of compounds 5 a and 5 b with D2 and D2O showed H/D exchange at the HRe and HO positions. Compounds 5 a and 5 b were active catalysts in the transfer hydrogenation reactions of ketones and imines with 2‐propanol as both the solvent and H2 source. The mechanism of the transfer hydrogenation and isomerization reactions was supported by DFT calculations, which suggested a secondary‐coordination‐sphere mechanism for the transfer hydrogenation of ketones.
Extraordinary Radical Scavengers: 4‐Mercaptostilbenes
Authors: Cao Xiao‐Yan , Yang Jie , Dai Fang , Ding De‐Jun , Kang Yan‐Fei , Wang Fu , Li Xiu‐Zhuang , Liu Guo‐Yun , Yu Sha‐Sha , Jin Xiao‐Ling , Zhou Bo 
Published: March 2012

AbstractIn the past decade, there was a great deal of interest and excitement in developing more active antioxidants and cancer chemoprevention agents than resveratrol, a naturally occurring stilbene. In this work, eight resveratrol‐directed 4‐mercaptostilbenes were constructed based on the inspiration that thiophenol should be a stronger radical scavenger than phenol, and their reaction rates with galvinoxyl (GO.) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH.) radicals in methanol and ethyl acetate were measured by using stopped‐flow UV/Vis spectroscopy at 25 °C. Kinetic analysis demonstrates that 4‐mercaptostilbenes are extraordinary radical scavengers, and the substitution of the 4‐SH group for the 4‐OH group in the stilbene scaffold is an important strategy to improve the radical‐scavenging activity of resveratrol. Surprisingly, in methanol, some of the 4‐mercaptostilbenes are 104‐times more active than resveratrol, dozens of times to hundreds of times more effective than known antioxidants (α‐tocopherol, ascorbic acid, quercetin, and trolox). The detailed radical‐scavenging mechanisms were discussed based on acidified‐kinetic analysis. Addition of acetic acid remarkably reduced the GO. and DPPH. radical‐scavenging rates of the 4‐mercaptostilbenes in methanol, a solvent that supports ionization, suggesting that the reactions proceed mainly through a sequential proton loss electron transfer mechanism. In contrast, an interesting acid‐promoted kinetics was observed for the reactions of the 4‐mercaptostilbenes with DPPH. in ethyl acetate, a solvent that weakly supports ionization. The increased ratio in rates is closely correlated with the electron‐rich environment in the molecules, suggesting that the acceleration could benefit from the contribution of the electron transfer from the 4‐mercaptostilbenes and DPPH.. However, the addition of acetic acid had no influence on the GO.‐scavenging rates of the 4‐mercaptostilbenes in ethyl acetate, due to the occurrence of the direct hydrogen atom transfer. Our results show that the radical‐scavenging activity and mechanisms of 4‐mercaptostilbenes depends significantly on the molecular structure and acidity, the nature of the attacking radical, and the ionizing capacity of the solvent.
“Relaxometry” experiments and analysis of dispersion curves: An illustrative example of toluene in liquid and in organogel phases
Authors: Steiner Emilie , Bouguet‐Bonnet Sabine , Robert Anthony , Canet Daniel 
Published: March 2012

AbstractAt very low or low frequency, the so‐called dispersion curves (longitudinal relaxation rate as a function of the measurement frequency) are obtained with a “relaxometer,” which is generally run according to the “field‐cycling” technique. Because of the very poor field homogeneity, relaxation times of a single (broad) signal are measured. When going to higher fields, with standard nuclear magnetic resonance spectrometers (possibly with variable field capacities), different lines are resolved. We show how the relaxation rates pertaining to these lines can be connected to the results obtained via the relaxometer. Among other things, we demonstrate why the magnitude mode (generally used for processing the relaxometer data) must be used with caution when several lines are resolved. Actually, we could obtain accurate 1H dispersion curves in a very broad frequency range (5 kHz–400 MHz), and we show that a decomposition into several Lorentzian curves proves to be adequate, as far as paramagnetic relaxation due to dissolved oxygen is concerned. The method will be applied i) to nondegassed liquid toluene, ii) to the same solvent involved in the formation of an organogel. In that latter case, a low frequency contribution to the dispersion curve (possibly non‐Lorentzian) reveals the part of the solvent within the organogel structure. The algorithm used for analyzing these dispersion curves is described. © 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 80–89, 2012.
Synthesis of Molecular Gallium Hydrides by Means of Low‐Temperature Catalytic Dehydrogenation
Authors: Rudolf Daniel , Storch Golo , Kaifer Elisabeth , Himmel Hans‐Jörg 
Published: March 2012

AbstractLow‐temperature catalytic dehydrogenation of H3Ga·NMe3 and a bicyclic guanidine [1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine (hppH) or 1,5,7‐triazabicyclo[4.3.0]non‐6‐ene (Htbn)] led to temperature‐sensitive gallium hydrides H3Ga(tbn)·Htbn and [H2Ga(μ‐hpp)]2. Both hydrides, which are stable only at low temperatures, were structurally characterized. A possible pathway and the role of the catalyst are discussed on the basis of NMR spectroscopic experiments and quantum chemical calculations.
Development of a capillary electrophoresis‐mass spectrometry method for the determination of rivastigmine in human plasma – Optimization of the limits of detection and quantitation
Authors: Nicolaou Irene N. , Kapnissi‐Christodoulou Constantina P. 
Published: March 2012

AbstractA capillary zone electrophoresis‐electrospray ionization‐mass spectrometry (CZE‐ESI‐MS) method was developed for the analysis of the acetylcholinesterase inhibitor rivastigmine. Several electrophoretic and ESI‐MS parameters were investigated in order to improve sensitivity. These parameters were categorized in three areas: (i) background electrolyte (BGE) parameters, (ii) sheath liquid parameters, and (iii) spray chamber parameters. The optimized results were obtained by using 40‐mM ammonium acetate at pH 9 as BGE, a sheath liquid of 1% acetic acid in water:MeOH (50:50 v/v) at a flow rate of 10 μL/min, and a drying gas flow rate that was set at 6 L/min and at a temperature of 200°C. These parameters provided limit of detection and limit of quantitation of 2.8 ng/mL and 8.4 ng/mL, respectively. The optimal CZE‐ESI‐MS conditions were applied to a plasma sample obtained from an Alzheimer's disease patient following rivastigmine patch administration, and the mean (±standard deviation) plasma concentration was estimated to be 14.6 (±1.7) ng/mL. Several sample preparation procedures were examined, and solid‐phase extraction using a C18 cartridge proved to be the most effective procedure, since higher sensitivity and recovery were obtained. In addition, precision was evaluated based on migration time and peak area in plasma, and the relative standard deviations were in the range of 0.10–0.16% and 0.62–9.0%, respectively.
A simple and robust LC‐MS/MS method for quantification of free 3‐nitrotyrosine in human plasma from patients receiving on‐pump CABG surgery
Authors: Hui Yu , Wong Michael , Zhao Shuai Sherry , Love Jennifer A. , Ansley David M. , Chen David D.Y. 
Published: March 2012

AbstractWe have developed a simple, sensitive, and robust liquid chromatography‐mass spectrometry/mass spectrometry (LC‐MS/MS) method to determine free 3‐nitrotyrosine concentrations in human plasma of patients receiving on‐pump coronary artery bypass grafting surgery. A one‐step solid‐phase extraction protocol was optimized to enrich the analyte at low nanomolar concentrations. The processed samples were analyzed by LC‐MS/MS with a 2.1 × 100 mm Kinetex PFP column and a triple quadrupole mass spectrometer. The method was validated for 3‐nitrotyrosine concentrations close to real patient plasma levels. The relative standard deviations or relative errors of the intraday and interday determinations were all within 10%. Limit of detection and limit of quantitation were determined to be 0.034 nM and 0.112 nM, respectively, while lower limit of quantitation was below 0.625 nM. No deterioration of the column performance was noticed after running a large number of patient samples. The results showed that the 3‐nitrotyrosine concentrations in coronary sinus plasma samples were elevated after cardiopulmonary bypass (CPB) procedure. The pre‐CPB and post‐CPB concentrations of 3‐nitrotyrosine in patient plasmas were 1.494 ± 0.107 nM and 2.167 ± 0.177 nM (mean ± SEM), respectively. Application of this method to more patients in clinical studies may help validate 3‐nitrotyrosine as a meaningful biomarker for nitrosative stress and link patient characteristics, clinical outcomes, and cardioprotective treatments to endogenous nitrosative stress levels.
Implementation of a design of experiments to study the influence of the background electrolyte on separation and detection in non‐aqueous capillary electrophoresis–mass spectrometry
Authors: Posch Tjorben Nils , Müller Alexander , Schulz Wolfgang , Pütz Michael , Huhn Carolin 
Published: March 2012

AbstractNon‐aqueous capillary electrophoresis (NACE) background electrolytes are most often composed of a mixture of methanol and acetonitrile (ACN) with soluble ammonium salts added as electrolyte. In this study on NACE‐MS, we used a mixture of glacial acetic acid and ACN giving rise to an acidic background electrolyte (BGE) with a very low dielectric constant. Impressive changes in selectivity and resolution were observed for structurally closely related indole alkaloids including diastereomers upon addition of ammonium formate as electrolyte and upon variation of the solvent ratio. In order to obtain best separation and MS detection conditions and to reveal the influence of the parameters of the BGE on separation and detection and vice versa of the MS parameters on separation, an optimization strategy was employed using a design of experiments in a central composite design with response surface methodology. It was proven that at high electroosmotic flow conditions capillary electrophoretic separations and thus optimization can be realized without interference from the coupling to an MS system. Several significantly interacting parameters were revealed, which are not accessible with classical univariate optimization approaches. With this optimization, alkaloid mixtures from a plant extract of Mitragyna speciosa, containing a large number of diastereomeric compounds were successfully separated.
Chiral electrokinetic chromatography‐electrospray ionization‐mass spectrometry using a double junction interface
Authors: Hung Sih‐Hua , Cheng Wen‐Shuo , Huang Ju‐Li , Wang Che‐Wei , Her Guor‐Rong 
Published: March 2012

AbstractA double junction interface was utilized to preserve separation efficiency and alleviate ion suppression from sulfated β‐cyclodextrin (S‐β‐CD) in electrokinetic chromatography‐electrospray ionization‐mass spectrometry. The utility of the approach was demonstrated by chiral EKC‐MS analysis of dihydroxyphenylalanine and methyldihydroxyphenylalanine enantiomers using either low concentration (counter‐migration mode; 0.1% S‐β‐CD) or high concentration (carrier mode; 2% S‐β‐CD). In the counter‐migration mode, S‐β‐CD anions were supplied continuously from the junction reservoir to the separation column so that the effective separation length was preserved. This interface is especially useful under carrier mode in which high concentration of S‐β‐CD will migrate toward the ESI source. With the use of the double junction interface, the S‐β‐CD exited the separation column will remain in the junction reservoir, whereas the analyte will flow toward the ESI source through a connecting column. As a result, no ion suppression was observed and the sensitivity was improved significantly.
Simultaneous analysis of cocaine and its metabolites in urine by capillary electrophoresis–electrospray mass spectrometry using a pressurized liquid junction nanoflow interface
Authors: Hezinová Věra , Aturki Zeineb , Klepárník Karel , D'Orazio Giovanni , Foret František , Fanali Salvatore 
Published: March 2012

AbstractA new method for the simultaneous separation of cocaine and four metabolites in urine by CE‐ESI‐MS via a pressurized nanoliquid junction interface was developed. The resolution of cocaine, cocaethylene, benzoylecgonine, norcocaine, and ecgonine methyl ester was achieved in a polyvinyl‐alcohol‐coated capillary with 75 μm id × 50 cm total length, using a 15 mM ammonium formate electrolyte solution (pH 9.5) in less than 15 min. In addition, to enhance sensitivity, a field‐amplified sample injection (FASI) was evaluated in terms of injection time and sample solvent composition. The limits of detection achieved with the FASI method ranged from 1.5 to 10 ng/mL for all the compounds. The detection of the studied compounds was performed using an ion‐trap mass spectrometer in a positive ionization mode. A mixture of methanol:water (80:20 v/v) containing 0.1% v/v of formic acid was employed as spray liquid and delivered at ˜200 nL/min. Under optimal CE–MS conditions, linearity was assessed in the concentration range of interest for all analytes with correlation coefficients r2 ≥ 0.9913. Intra‐ and inter‐day precision provided a relative standard deviation lower than 1.54% for migration times and lower than 12.15% for peak areas. Finally, urine samples, spiked with the standard mixture, were extracted using a solid‐phase extraction procedure and injected under FASI conditions, providing recoveries from 80% to 94% for all analytes.
Capillary electrophoresis coupled to electrospray mass spectrometry through a coaxial sheath flow interface and semi‐permanent phospholipid coating for the determination of oligosaccharides labeled with 1‐aminopyrene‐3,6,8‐trisulfonic acid
Authors: Langan Ted J. , Holland Lisa A. 
Published: March 2012

AbstractFor the first time, a semi‐permanent phospholipid coating is utilized in capillary electrophoresis–electrospray ionization–mass spectrometry (CE‐ESI‐MS). Although phospholipids in free solution are generally avoided in ESI, they did not interfere with the detection of linear and branched oligosaccharides using ESI operated in negative mode. The CE and ESI were coupled using a coaxial sheath flow interface. The separation was operated in reversed polarity and the electroosmotic flow was effectively suppressed by the phospholipid coating. The method was characterized with linear oligosaccharides and used to monitor the enzymatic hydrolysis of maltooligosaccharides with α‐amyloglucosidase. Branched oligosaccharides were separated and detected with the system. The enzyme β1–4 galactosidase was used to distinguish branched isomeric oligosaccharides derived from asialofetuin.