bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of γ‐Oxo‐α,β‐dehydro‐α‐amino Acids from N–tert‐Butyloxycarbonyl‐α‐Imino Esters and Carbonylmethyl 2‐Pyridinylsulfones via an Mannich‐Elimination Cascade
Authors: Wu Deyan , Zhu Jin , Sheng Chunquan , Wang Wei , Li Jian 
Published: May 2014

AbstractA method for facile synthesis of γ‐oxo‐α,β‐dehydro‐α‐amino acids has been developed. The process involves a triethylamine‐mediated Mannich‐elimination cascade process from N‐tert‐butyloxycarbonyl (Boc)‐α‐imino esters with carbonylmethyl 2‐pyridinylsulfones. The γ‐oxo‐α,β‐dehydro‐α‐amino acids are produced in good yields of 51–98 % and with excellent E selectivity. The γ‐oxo‐α,β‐dehydro‐α‐amino acid derivatives can be conveniently transformed to highly enantioenriched α‐amino acids via an asymmetric hydrogenation.
Eine auf Ru‐Katalyse basierende wiederaufladbare Wasserstoffbatterie
Authors: Hsu Shih‐Fan , Rommel Susanne , Eversfield Philipp , Muller Keven , Klemm Elias , Thiel Werner R. , Plietker Bernd 
Published: May 2014

AbstractAußer der wirtschaftlichen Energiegewinnung sind auch die effiziente Speicherung und Freisetzung von Energie wesentliche Anforderungen beim Aufbau einer nachhaltigen Energieversorgung. Wir berichten hier über die Entwicklung einer wiederaufladbaren Wasserstoffbatterie, die auf dem Prinzip einer Ru‐katalysierten Hydrierung von CO2 zu Ameisensäure (Aufladevorgang) und einer Ru‐katalysierten Zersetzung der Ameisensäure zu CO2 und H2 (Entladevorgang) beruht. Beide Prozesse laufen mit dem gleichen Katalysator unter identischen Bedingungen bei hoher Temperatur unter Druck (Aufladevorgang) bzw. bei hoher Temperatur unter druckfreien Bedingungen (Entladevorgang) ab. Bis zu fünf Lade‐Entlade‐Zyklen können ohne Verlust an Speicherkapazität durchlaufen werden; das entstehende CO2/H2‐Gemisch ist CO‐frei und kann direkt in der Brennstoffzelle verwendet werden.
Auf dem Weg zur Hochleistungs‐Lewis‐Säure‐Organokatalyse
Authors: Ratjen Lars , van Gemmeren Manuel , Pesciaioli Fabio , List Benjamin 
Published: May 2014

AbstractDie Kombination von Lewis‐Säure‐Organokatalyse und interner Aktivierung durch Wasserstoffbrücken wurde verwendet, um neue hochaktive Disulfonimidkatalysatoren zu entwickeln. Die erhöhte Lewis‐Acidität wurde durch Aktivitätsvergleiche und theoretische Untersuchungen bestätigt. Schließlich wurde das Potenzial dieser Wasserstoffbrücken‐aktivierten Disulfonimidkatalysatoren durch deren Verwendung in einer enantioselektiven Reaktion aufgezeigt.
Gold‐Catalyzed Allylation of Aryl Boronic Acids: Accessing Cross‐Coupling Reactivity with Gold
Authors: Levin Mark D. , Toste F. Dean 
Published: May 2014

AbstractA sp3–sp2 CC cross‐coupling reaction catalyzed by gold in the absence of a sacrificial oxidant is described. Vital to the success of this method is the implementation of a bimetallic catalyst bearing a bis(phosphino)amine ligand. A mechanistic hypothesis is presented, and observable transmetalation, CBr oxidative addition, and CC reductive elimination in a model gold complex are shown. We expect that this method will serve as a platform for the development of novel transformations involving redox‐active gold catalysts.
EBC‐219: A New Diterpene Skeleton, Crotinsulidane, from the Australian Rainforest Containing a Bridgehead Double Bond
Authors: Maslovskaya Lidiya A. , Savchenko Andrei I. , Krenske Elizabeth H. , Pierce Carly J. , Gordon Victoria A. , Reddell Paul W. , Parsons Peter G. , Williams Craig M. 
Published: May 2014

AbstractEBC‐219 (4), isolated from Croton insularis (Baill), was established by spectroscopic and DFT methods as the first member of a new diterpene skeletal class, uniquely defined by the presence of a bicyclo[10.2.1] bridgehead olefin. The proposed biogenetic pathway to 4 from the co‐isolated natural products EBC‐131 (1), EBC‐180 (2) and EBC‐181 (3) is highly likely. EBC‐180 (2) and EBC‐181 (3) showed moderate to strong cytotoxic activity against various cancer cell lines.
Podlike N‐Doped Carbon Nanotubes Encapsulating FeNi Alloy Nanoparticles: High‐Performance Counter Electrode Materials for Dye‐Sensitized Solar Cells
Authors: Zheng Xiaojia , Deng Jiao , Wang Nan , Deng Dehui , Zhang Wen‐Hua , Bao Xinhe , Li Can 
Published: May 2014

AbstractPodlike nitrogen‐doped carbon nanotubes encapsulating FeNi alloy nanoparticles (Pod(N)‐FeNi) were prepared by the direct pyrolysis of organometallic precursors. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization measurements revealed their excellent electrocatalytic activities in the I−/I3− redox reaction of dye‐sensitized solar cells (DSSCs). This is suggested to arise from the modification of the surface electronic properties of the carbon by the encapsulated metal alloy nanoparticles (NPs). Sequential scanning with EIS and CV further showed the high electrochemical stability of the Pod(N)‐FeNi composite. DSSCs with Pod(N)‐FeNi as the counter electrode (CE) presented a power conversion efficiency of 8.82 %, which is superior to that of the control device with sputtered Pt as the CE. The Pod(N)‐FeNi composite thus shows promise as an environmentally friendly, low‐cost, and highly efficient CE material for DSSCs.
Improved Cyclopropanation Activity of Histidine‐Ligated Cytochrome P450 Enables the Enantioselective Formal Synthesis of Levomilnacipran
Authors: Wang Z. Jane , Renata Hans , Peck Nicole E. , Farwell Christopher C. , Coelho Pedro S. , Arnold Frances H. 
Published: May 2014

AbstractEngineering enzymes capable of modes of activation unprecedented in nature will increase the range of industrially important molecules that can be synthesized through biocatalysis. However, low activity for a new function is often a limitation in adopting enzymes for preparative‐scale synthesis, reaction with demanding substrates, or when a natural substrate is also present. By mutating the proximal ligand and other key active‐site residues of the cytochrome P450 enzyme from Bacillus megaterium (P450‐BM3), a highly active His‐ligated variant of P450‐BM3 that can be employed for the enantioselective synthesis of the levomilnacipran core was engineered. This enzyme, BM3‐Hstar, catalyzes the cyclopropanation of N,N‐diethyl‐2‐phenylacrylamide with an estimated initial rate of over 1000 turnovers per minute and can be used under aerobic conditions. Cyclopropanation activity is highly dependent on the electronic properties of the P450 proximal ligand, which can be used to tune this non‐natural enzyme activity.
Catalytic Asymmetric Synthesis of 3,3′‐Diaryloxindoles as Triarylmethanes with a Chiral All‐Carbon Quaternary Center: Phase‐Transfer‐Catalyzed SNAr Reaction
Authors: Shirakawa Seiji , Koga Kenta , Tokuda Takashi , Yamamoto Kenichiro , Maruoka Keiji 
Published: May 2014

AbstractCatalytic asymmetric synthesis of unsymmetrical triarylmethanes with a chiral all‐carbon quaternary center was achieved by using a chiral bifunctional quaternary phosphonium bromide catalyst in the SNAr reaction of 3‐aryloxindoles under phase‐transfer conditions. The presence of a urea moiety in the chiral phase‐transfer catalyst was important for obtaining high enantioselectivity in this reaction.
A water‐soluble CO2‐triggered viscosity‐responsive copolymer of N,N‐dimethylaminoethyl methacrylate and acrylamide
Authors: Lu Hongsheng , Jiang Jifeng , Huang Zhiyu , Dai Shanshan 
Published: May 2014

ABSTRACTA series of copolymers PDAMs were synthesized with varying monomer ratio of acrylamide (AM) and N,N‐dimethylaminoethyl methacrylate (DMAEMA). The resulting copolymer solution shows an interesting property of viscosity‐response which is CO2‐triggered and N2‐enabled. Tertiary amine groups of PDAMs experience a reversible transition between hydrophobic and hydrophilic state upon CO2 addition and its removal, which induced different rheological behavior. A combination of zeta‐potential, laser particle‐size analysis, and electrical conductivity analysis indicated that, when the monomer mole ratio of DMAEMA and AM is less than or equal to 3 : 7, the hydrophobic association structure between the copolymer molecules was destroyed by the leading of CO2 and caused a viscosity decrease in its solution. On the contrary, when the monomer mole ratio of DMAEMA and AM is more than 3 : 7, a more extended conformation due to the protonated tertiary amine groups is formed and the enhanced repulsive interactions among the copolymer molecule results in a rise of its solution viscosity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40872.
Development of physiologically based pharmacokinetic model to evaluate the relative systemic exposure to quetiapine after administration of IR and XR formulations to adults, children and adolescents
Authors: Johnson Trevor N. , Zhou Diansong , Bui Khanh H. 
Published: May 2014

ABSTRACTQuetiapine is an atypical antipsychotic drug with a high permeability, moderate solubility and defined as a Biopharmaceutics Classification System class ll compound. The pharmacokinetics (PK) of the quetiapine immediate‐release (IR) formulation has been studied in both adults and children, but the quetiapine extended‐release (XR) formulation has only been conducted in adults. The purpose of the current study was to use physiologically based pharmacokinetic modeling (PBPK) quantitatively to predict the PK of the XR formulation in children and adolescents. Using a ‘learn and confirm’ approach, PBPK models were developed employing in vitro ADME and physicochemical data, clinical PK data of quetiapine IR/XR in adults and clinical PK data of quetiapine IR in children. These models can predict well the effects of CYP3A4 inhibition and induction on the PK of quetiapine, the PK profile of quetiapine IR in children and adults, and the PK profile of quetiapine XR in adults. The AUC and Cmax ratios (children vs adults) for the different age groups were in reasonable agreement with the observed ratios. In addition, the PBPK model predicted that children and adolescents are likely to achieve a similar exposure following administration of either the XR formulation once daily or the IR formulation twice daily at similar total daily doses. The results from the study can help inform dosing regimens in pediatrics using the quetiapine XR formulation. Copyright © 2014 John Wiley & Sons, Ltd.
Essential role of amino acid position 226 in oligosaccharide elongation by amylosucrase from Neisseria polysaccharea
Authors: Cambon Emmanuelle , Barbe Sophie , Pizzut‐Serin Sandra , Remaud‐Simeon Magali , André Isabelle 
Published: May 2014

ABSTRACTAmylosucrase from Neisseria polysaccharea is a remarkable transglucosylase that synthesizes an insoluble amylose‐like polymer from sole substrate sucrose. One particular amino acid, Arg226, was proposed from molecular modeling studies to play an important role in the formation of the active site topology and in the accessibility of ligands to the catalytic site. The systematic mutation of this Arg residue by all 19 other possible amino acids revealed that all single‐mutants had a higher activity on sucrose compared to the wild‐type enzyme. An extensive kinetic investigation showed that catalytic efficiencies are greatly impacted by the presence of natural acceptors in the reaction media, their chain length and the nature of the amino acid at position 226. Compared to the wild‐type enzyme, the R226N mutant showed a 10‐fold enhancement in the catalytic efficiency and a nearly twofold higher production of an insoluble amylose‐like polymer that can be of interest for biotechnological applications. Biotechnol. Bioeng. 2014;111: 1719–1728. © 2014 Wiley Periodicals, Inc.
Polyethersulfone/Poly(D,L‐lactide) Blend Membranes: Preparation, Characterization, and Performance
Authors: Hassani Fatemeh , Mousavi Seyed M. , Saghatoleslami Nasser , Ghaffarian Vahideh 
Published: May 2014

AbstractPolyethersulfone (PES) was blended with poly(D,L‐lactide) (PDLLA) to prepare asymmetric membranes using the phase inversion method. The effects of the blend ratios and poly(ethylene glycol) (PEG) as additive on the membrane structure, properties, and performance were investigated. The membranes were characterized by contact angle determination, scanning electron microscopy, porosity measurement, thermogravimetric analysis, degradation tests in compost, and dynamic tests for pure water flux and bakery product wastewater treatment. PES and PEG slightly reduced the membrane contact angle. Increasing the PDLLA concentration in the blend membranes enhanced the membrane degradation in compost and also the membrane porosity. The permeate flux of the membranes was improved, but the rejection of pollution indices did not change noticeably.
Chiral Phosphoric‐Acid‐Catalyzed Transfer Hydrogenation of Ethyl Ketimine Derivatives by Using Benzothiazoline
Authors: Saito Kodai , Horiguchi Kosaku , Shibata Yukihiro , Yamanaka Masahiro , Akiyama Takahiko 
Published: May 2014

AbstractChiral phosphoric acid catalyzed transfer hydrogenation of ketimines derived from propiophenone derivatives and reductive amination of alkyl ethyl ketone derivatives were extensively examined in the presence of two representative hydrogen donors. The excellent enantioselective transfer hydrogenation was achieved by use of benzothiazoline as a hydrogen donor. The theoretical studies elucidated that the unsymmetrical structure of benzothiazoline plays an important role in high enantioselective hydrogenation.
Improved Bioactivity of Antimicrobial Peptides by Addition of Amino‐Terminal Copper and Nickel (ATCUN) Binding Motifs
Authors: Libardo M. Daben , Cervantes Jorge L. , Salazar Juan C. , Angeles‐Boza Alfredo M. 
Published: May 2014

AbstractAntimicrobial peptides (AMPs) are promising candidates to help circumvent antibiotic resistance, which is an increasing clinical problem. Amino‐terminal copper and nickel (ATCUN) binding motifs are known to actively form reactive oxygen species (ROS) upon metal binding. The combination of these two peptidic constructs could lead to a novel class of dual‐acting antimicrobial agents. To test this hypothesis, a set of ATCUN binding motifs were screened for their ability to induce ROS formation, and the most potent were then used to modify AMPs with different modes of action. ATCUN binding motif‐containing derivatives of anoplin (GLLKRIKTLL‐NH2), pro‐apoptotic peptide (PAP; KLAKLAKKLAKLAK‐NH2), and sh‐buforin (RAGLQFPVGRVHRLLRK‐NH2) were synthesized and found to be more active than the parent AMPs against a panel of clinically relevant bacteria. The lower minimum inhibitory concentration (MIC) values for the ATCUN–anoplin peptides are attributed to the higher pore‐forming activity along with their ability to cause ROS‐induced membrane damage. The addition of the ATCUN motifs to PAP also increases its ability to disrupt membranes. DNA damage is the major contributor to the activity of the ATCUN–sh‐buforin peptides. Our findings indicate that the addition of ATCUN motifs to AMPs is a simple strategy that leads to AMPs with higher antibacterial activity and possibly to more potent, usable antibacterial agents.
A randomized phase 2 trial of gemcitabine/cisplatin with or without cetuximab in patients with advanced urothelial carcinoma
Authors: Hussain Maha , Daignault Stephanie , Agarwal Neeraj , Grivas Petros D. , Siefker‐Radtke Arlene O. , Puzanov Igor , MacVicar Gary R. , Levine Ellis Glenn , Srinivas Sandy , Twardowski Przemyslaw , Eisenberger Mario A. , Quinn David I. , Vaishampayan Ulka N. , Yu Evan Y. , Dawsey Scott , Day Kathleen C. , Day Mark L. , Al‐Hawary Mahmoud , Smith David C. 
Published: May 2014

BACKGROUNDEpidermal growth factor receptor overexpression is associated with poor outcomes in urothelial carcinoma (UC). Cetuximab (CTX) exhibited an antitumor effect in in vivo UC models. The efficacy of gemcitabine/cisplatin (GC) with or without CTX in patients with advanced UC was evaluated.METHODSPatients with advanced UC, measurable disease, and adequate organ function were randomized 1:2 to cisplatin (70 mg/m2) on day 1 plus gemcitabine (1000 mg/m2) on days 1, 8, and 15 (arm A) or GC plus CTX (500 mg/m2) on days 1 and 15 (arm B). The primary endpoint was the overall response rate. The secondary endpoints were the response duration, safety, progression‐free survival, overall survival, determination of whether or not CTX sensitized nonresponders to GC, and exploratory biomarker analysis. The accrual targets were 27 and 54 patients for the 2 arms, respectively. The overall response rate was reported by arm with binomial confidence intervals (CIs). Kaplan‐Meier methods were used for time‐to‐event endpoints.RESULTSEighty‐eight eligible patients were randomized; 87 were toxicity‐evaluable, and 85 were response‐evaluable. The overall response rates were 57.1% for arm A (95% CI = 37%‐76%) and 61.4% for arm B (95% CI = 48%‐74%). The median progression‐free survival times were 8.5 months for arm A (95% CI = 5.7‐10.4 months) and 7.6 months for arm B (95% CI = 6.1‐8.7 months). The median overall survival times were 17.4 months for arm A (95% CI = 12.8 months to unreached) and 14.3 months for arm B (95% CI = 11.6‐22.2 months). The most common grade 3/grade 4 adverse events in both arms were myelosuppression and nausea. Thromboembolism, acneiform rash, fatigue, pain, hypersensitivity reactions, elevated transaminases, hyponatremia, and hypomagnesemia were more common in arm B; 3 grade 5 adverse events occurred in arm B. The presence of primary disease significantly correlated with thromboembolism. An increased soluble E‐cadherin level after cycle 2 correlated with a higher risk of death.CONCLUSIONSGC plus CTX was feasible but was associated with more adverse events and no improvements in outcomes. Cancer 2014;120:2684–2693. © 2014 American Cancer Society.
Early experiences in developing and managing the neuroscience gateway
Authors: Sivagnanam Subhashini , Majumdar Amit , Yoshimoto Kenneth , Astakhov Vadim , Bandrowski Anita , Martone MaryAnn , Carnevale Nicholas. T. 
Published: May 2014

SummaryThe last few decades have seen the emergence of computational neuroscience as a mature field where researchers are interested in modeling complex and large neuronal systems and require access to high performance computing machines and associated cyber infrastructure to manage computational workflow and data. The neuronal simulation tools, used in this research field, are also implemented for parallel computers and suitable for high performance computing machines. But using these tools on complex high performance computing machines remains a challenge because of issues with acquiring computer time on these machines located at national supercomputer centers, dealing with complex user interface of these machines, dealing with data management and retrieval. The Neuroscience Gateway is being developed to alleviate and/or hide these barriers to entry for computational neuroscientists. It hides or eliminates, from the point of view of the users, all the administrative and technical barriers and makes parallel neuronal simulation tools easily available and accessible on complex high performance computing machines. It handles the running of jobs and data management and retrieval. This paper shares the early experiences in bringing up this gateway and describes the software architecture it is based on, how it is implemented, and how users can use this for computational neuroscience research using high performance computing at the back end. We also look at parallel scaling of some publicly available neuronal models and analyze the recent usage data of the neuroscience gateway. Copyright © 2014 John Wiley & Sons, Ltd.
Following the Azide‐Alkyne Cycloaddition at the Silica/Solvent Interface with Sum Frequency Generation
Authors: Li Zhiguo , Weeraman Champika N. , Gibbs‐Davis Julianne M. 
Published: May 2014

AbstractThe CuI‐catalyzed 1,3‐dipolar azide‐alkyne cycloaddition (CuAAC) has arisen as one of the most useful chemical transformations for introducing complexity onto surfaces and materials owing to its functional‐group tolerance and high yield. However, methods for monitoring such reactions in situ at the widely used silica/solvent interface are hampered by challenges associated with probing such buried interfaces. Using the surface‐specific technique broadband sum frequency generation (SFG), we monitored the reaction of a benzyl azide monolayer in real time at the silica/methanol interface. A strong peak at 2096 cm−1 assigned to the azides was observed for the first time by SFG. Using a cyano‐substituted alkyne, the decrease of the azide peak and the increase of the cyano peak (2234 cm−1) were probed simultaneously. From the kinetic analysis, the reaction order with respect to copper was determined to be 2.1, suggesting that CuAAC on the surface follows a similar mechanism as in solution.
A Probe for the Selective and Parts‐per‐Billion‐Level Detection of Copper(II) and Mercury(II) using a Micellar Medium and Its Utility in Cell Imaging
Authors: Kumari Namita , Jha Satadru , Misra Santosh K. , Bhattacharya Santanu 
Published: May 2014

AbstractA novel colorimetric probe 1 based on the picolyl moiety has been designed and synthesized. Probe 1 is composed of a pyrene and a bispicolyl amine (BPA) unit, in which the BPA moiety acts as a binding unit and the binding phenomenon is sensed from the changes in the signaling subunit. The probe detects Cu2+ specifically in water and both Cu2+ and Hg2+ efficiently in neutral Brij‐58 micellar media. The probe shows a color change visible to the naked eye upon addition of metal ions. Notably, in a micellar medium, probe 1 can detect both the Cu2+ and Hg2+ ions even at parts‐per‐billion levels. Furthermore, the probe shows ratiometric detection of both the metal ions making the sensing quantitative. The two metal ions could be discriminated both visibly under a UV lamp and with the use of fluorescence spectroscopy. The probe could be also used in biological cell lines for the detection of both Hg2+ and Cu2+ ions.
Reversibility of Lithium‐Ion–Air Batteries Using Lithium Intercalation Compounds as Anodes
Authors: Chun Jinyoung , Kim Hyojin , Jo Changshin , Lim Eunho , Lee Jinwoo , Kim Youngsik 
Published: May 2014

AbstractA Li (ion)–air cell was designed to investigate the reversible utilization of Li that was harvested from a cathode. In the Li (ion)–air cell, 0.1 M LiOH(aq) was used as the catholyte with oxygen in air and Li intercalation compounds such as graphite (C6) and Li4Ti5O12 (LTO) were used as the anodes. It appeared that the Li metal formed on the stainless‐steel anode in the first charge of the Li–air cell was poorly reversible in further cycling owing to irreversible loss of Li during cycling. However, when Li intercalation compounds were used as anodes in a Li‐ion–air cell, high coulombic efficiency by reversible reactions and good cycle performance were achieved. These results show that Li intercalation materials have significant potential as anode materials since they effectively utilize Li resources in Li–air battery systems and ensure reversibility in these systems.
Brønsted Acid Ionic Liquid as a Solvent‐Conserving Catalyst for Organic Reactions
Authors: Taheri Amir , Pan Xiaojuan , Liu Changhui , Gu Yanlong 
Published: May 2014

AbstractA sulfonyl‐containing ammonium‐based Brønsted acid ionic liquid was prepared and used as a liquid heterogeneous catalyst for organic reactions. The unique macroscopic phase heterogeneity of the IL in the reaction system not only ensures an excellent catalytic activity of the IL catalyst but also avoids the use of organic reaction solvents. The catalyst system is applicable for a wide range of reactions.