bluuebunny/crossref_metadata_2025_split huggingface dataset:
ChemInform Abstract: A Short and Flexible Route to Tetrahydropyran‐4‐ones via Conjugated Nitrile Oxides Cycloaddition and Oxa‐Michael Cyclization: A Concise Diastereoselective Total Synthesis of (.+‐.)‐Diospongin A.
Authors: Yao Hongliang , Ren Jingyun , Tong Rongbiao 
Published: April 2013

AbstractA convenient four step procedure is developed for the synthesis of tetrahydropyranones (IV) based on the conversion of unsaturated aldehydes (I) into corresponding nitrile oxides, 1,3‐dipolar cycloaddition, SmI2‐mediated reductive ring‐opening of resulting isoxazolines (III), and Amberlyst‐15 promoted 6‐endo‐trig oxa‐Michael cyclization of intermediate β‐hydroxyenones.
ChemInform Abstract: Rhodium or Ruthenium‐Catalyzed Oxidative C—H/C—H Cross‐Coupling: Direct Access to Extended π‐Conjugated Systems.
Authors: Dong Jiaxing , Long Zhen , Song Feijie , Wu Ningjie , Guo Qiang , Lan Jingbo , You Jingsong 
Published: April 2013

AbstractThis method is highly chemo‐ and regioselective and applicable to a broad variety of heteroarenes.
ChemInform Abstract: Silver‐Catalyzed Cyclization of N‐(Prop‐2‐yn‐1‐yl)pyridin‐2‐amines.
Authors: Chioua Mourad , Soriano Elena , Infantes Lourdes , Jimeno M. Luisa , Marco‐Contelles Jose , Samadi Abdelouahid 
Published: April 2013

AbstractThis reaction yields 3‐methyl‐imidazo[1,2‐α]pyridines (II) from readily available substrates.
ChemInform Abstract: Three‐Component Stereoselective Synthesis of Spirooxindole Derivatives
Authors: Yu Fuchao , Huang Rong , Ni Hangchen , Fan Juan , Yan Shengjiao , Lin Jun 
Published: April 2013

Abstractby refluxing mixtures of heterocyclic ketene aminals with isatins (I) and trifluoroacetate (III)
ChemInform Abstract: Synthesis of trans‐1,3‐Diaryl‐2‐(5‐methylisoxazol‐3‐yl)‐2,3‐dihydro‐1H‐naphtho [1,2‐e][1,3]oxazines via Bismuth(III)‐Catalyzed One‐Pot pseudo‐Four Component Reaction.
Authors: Shafiee Mehdi , Khosropour Ahmad Reza , Mohammadpoor‐Baltork Iraj , Moghadam Majid , Tangestaninejad Shahram , Mirkhani Valiollah , Khavasi Hamid Reza 
Published: April 2013

AbstractThis is a solvent‐free one‐pot multicomponent reaction which gives naphtho[1,2‐e][1,3]oxazines in good yields and with good diastereoselectivity.
ChemInform Abstract: 1,2‐ and 1,4‐Additions of 2‐Alkynylcyclohexadienimines with Aromatic Amines to Access 4‐Amino‐N‐arylindoles and ‐azepinoindoles.
Authors: Zhang Li , Li Zhiming , Fan Renhua 
Published: April 2013

AbstractAlkynylcyclohexadienimines (I) derived from the oxidation of alkynylanilines react with aromatic amines to 4‐aminoarylindoles.
ChemInform Abstract: An Unusual Silicon Mediated Transannular Cyclopropanation.
Authors: You Bing , Hamer Kate , Lewis William , Dowden James 
Published: April 2013

AbstractThe treatment of readily available 5,6‐dihydroazocinones (V) with tetrabutylammonium fluoride leads to fused cyclopropane derivatives (VI) as a result of a transannular cyclopropanation.
ChemInform Abstract: Efficient Metathesis of Terminal Alkynes.
Authors: Haberlag Birte , Freytag Matthias , Daniliuc Constantin G. , Jones Peter G. , Tamm Matthias 
Published: April 2013

AbstractFor the first time, terminal ring‐closing alkyne metathesis (TRAM) is accomplished; only one other related example with 25% yield exists in the literature.
ChemInform Abstract: Synthesis of Azaaromatic—Borane Intramolecular Complexes by Palladium‐Catalyzed Reaction of Azaaromatic Halides with Alkynyl(triaryl)borates.
Authors: Ishida Naoki , Narumi Mizuna , Murakami Masahiro 
Published: April 2013

AbstractA versatile method for the synthesis of (E)‐azastilbenes with an intramolecular B‐N coordination is presented for a wide variety of azaaromatics.
ChemInform Abstract: Straightforward Iron‐Catalyzed Synthesis of Vinylboronates by the Hydroboration of Alkynes.
Authors: Haberberger Michael , Enthaler Stephan 
Published: April 2013

AbstractThe iron‐catalyzed hydroboration of terminal alkynes (I) affords selectively the corresponding (E)‐isomer (III) in high yields.
ChemInform Abstract: Highly Chemoselective Metal‐Free Reduction of Phosphine Oxides to Phosphines.
Authors: Li Yuehui , Lu Liang‐Qiu , Das Shoubhik , Pisiewicz Sabine , Junge Kathrin , Beller Matthias 
Published: April 2013

AbstractA new, mild, and chemoselective method for the conversion of phosphine oxides into phosphines is reported.
ChemInform Abstract: Nickel‐Catalyzed C—P Cross‐Coupling of Diphenylphosphine Oxide with Aryl Chlorides.
Authors: Zhang Hong‐Yu , Sun Meng , Ma Yan‐Na , Tian Qiu‐Ping , Yang Shang‐Dong 
Published: April 2013

AbstractVarious diphenylphosphoryl compounds (III) and (V) are prepared using a simple and mild method.
ChemInform Abstract: Regioselective Formation of Tetrahydroselenophenes via 5‐exo‐dig‐Cyclization of 1‐Butylseleno‐4‐alkynes.
Authors: Gai Rafaela M. , Schumacher Ricardo F. , Back Davi F. , Zeni Gilson 
Published: April 2013

AbstractElectrophilic cyclization of butylselenoalkynes with iodine results in the formation of the title compounds which can be used for further transformations such as cyanation, Suzuki and Ullmann coupling reactions.
ChemInform Abstract: Lignans from Schisandra sphenathera Rehd. et Wils. and Semisynthetic Schisantherin A Analogues: Absolute Configuration, and Their Estrogenic and anti‐Proliferative Activity.
Authors: Liu Han‐Wei , Yu Xiu‐Zhu , Padula Daniele , Pescitelli Gennaro , Lin Zhi‐Wei , Wang Fei , Ding Kai , Lei Ming , Gao Jin‐Ming 
Published: April 2013

AbstractDerivatives (I) and (II) show very potent estrogenic effects.
Asymmetric Zinc‐Catalyzed Hydrosilylation of Ketones and the Effect of Carboxylate on the Enantioselectivity
Authors: Pang Shaofeng , Peng Jiajian , Li Jiayun , Bai Ying , Xiao Wenjun , Lai Guoqiao 
Published: April 2013

ABSTRACTSeveral chiral ligands containing (R,R)‐diaminocyclohexane moieties and pyrrole, furan, or benzene have been synthesized. These ligands were tested in enantioselective zinc‐catalyzed hydrosilylation reactions; excellent enantioselectivities were obtained when the ligands containing (R,R)‐diaminocyclohexane moieties and furan rings were used. For comparison, zinc chloride combined with different potassium carboxylate salts and ligands were also tested for catalytic hydrosilylation reactions. Chirality 25:275–280, 2013. © 2013 Wiley Periodicals, Inc.
Infrared Spectroscopy Using ATR Probe Technology
Authors: Lüttjohann Stephan 
Published: April 2013

AbstractInfrarotspektroskopie ist eine aussagekräftige Analysemethode, die auf charakteristischen Absorptionen von infraroter Strahlung bei der Anregung von Molekülschwingungen beruht. Gerade im Bereich zwischen 400 – 4000 cm–1 ergeben sich stark ausgeprägte Absorptionsbanden, die die Identifikation von Molekülen und Molekülgruppen möglich machen. Die hohe Absorptionsstärke erfordert für Transmissionsmessungen erhöhte Probenpräparation. So können nur Schichtdicken von wenigen Mikrometern verwendet werden. Bei der abgeschwächten Totalreflexion (ATR) sind solche Anstrengungen dagegen nicht erforderlich. Hier ist es ausreichend, beispielsweise eine Flüssigkeit in Kontakt mit einem ATR‐Kristall zu bringen. ATR‐Messsonden ermöglichen es, diese einfache Technik auch zur Online‐Überwachung an chemischen Reaktoren einzusetzen.
Fermentative Production of Monorhamnolipids in Pilot Scale – Challenges in Scale‐Up
Authors: Küpper Benjamin , Mause Anika , Halka Lisa , Imhoff Adam , Nowacki Christian , Wichmann Rolf 
Published: April 2013

AbstractDie fermentative Herstellung von Biotensiden wird meist durch die exzessive Bildung von stabilem Schaum erschwert. Am Beispiel von Monorhamnolipiden werden Vorschläge sowohl zur stabilen Aufrechterhaltung von begasten und gerührten Fermentationen wie auch zur Isolierung dieser Biotenside im größeren Maßstab gegeben, da diese kommerziell nur in sehr kleinen Mengen erhältlich sind. Ein besonderer Fokus liegt dabei auf der Verwendung nachwachsender Rohstoffe.
Omix – A Visualization Tool for Metabolic Networks with Highest Usability and Customizability in Focus
Authors: Droste Peter , Nöh Katharina , Wiechert Wolfgang 
Published: April 2013

AbstractVisualization has become indispensable in the analysis and interpretation of data from experiment and simulation. To adequately represent the diversity of studied phenomena, it is necessary to support researchers with tools that are easy to use and allow effective data visualization with special regard to individual requirements. This contribution presents the visualization tool Omix, an editor for metabolic network diagrams and a customizable visualization framework. As an outstanding feature, data visualization is script‐based. The dedicated new scripting language OVL (Omix Visualization Language) enables the user to freely design the manner data is visualized in the network. An intuitive user interface, several newly developed, domain‐specific drawing automatisms as well as visualization concepts make the software Omix a mature computational tool supporting the specific requirements of researchers from systems biology and life science domains as will be demonstrated on several application examples.
Synthesis and in vitro Evaluation of West Nile Virus Protease Inhibitors Based on the 2‐{6‐[2‐(5‐Phenyl‐4H‐{1,2,4]triazol‐3‐ylsulfanyl)acetylamino]benzothiazol‐2‐ylsulfanyl}acetamide Scaffold
Authors: Samanta Sanjay , Lim Ting Liang , Lam Yulin 
Published: April 2013

AbstractIn recent years, clinical symptoms resulting from West Nile virus (WNV) infection have worsened in severity, with an increased frequency in neuroinvasive diseases among the elderly. As there are presently no successful therapies against WNV for use in humans, continual efforts to develop new chemotherapeutics against this virus are highly desired. The viral NS2B‐NS3 protease is a promising target for viral inhibition due to its importance in viral replication and its unique substrate preference. In this study, a WNV NS2B‐NS3 protease inhibitor with a 2‐{6‐[2‐(5‐phenyl‐4H‐[1,2,4]triazol‐3‐ylsulfanyl)acetylamino]benzothiazol‐2‐ylsulfanyl}acetamide scaffold was identified during screening. Optimization of this initial hit by synthesis and screening of a focused compound library with this scaffold led to the identification of a novel uncompetitive inhibitor (1 a24, IC50=3.4±0.2 μM) of the WNV NS2B‐NS3 protease. Molecular docking of 1 a24 into the WNV protease showed that the compound interferes with productive interactions of the NS2B cofactor with the NS3 protease and is an allosteric inhibitor of the WNV NS3 protease.
Design of a quadrature surface coil for hyperpolarized 13C MRS cardiac metabolism studies in pigs
Authors: Giovannetti G. , Frijia F. , Hartwig V. , Attanasio S. , Menichetti L. , Vanello N. , Positano V. , Ardenkjaer‐Larsen J.H. , Lionetti V. , Aquaro G.D. , Marchi D. De , Schulte R.F. , Wiesinger F. , Landini L. , Lombardi M. , Santarelli M.F. 
Published: April 2013

ABSTRACTThis work describes the design of a quadrature surface coil constituted by a circular loop and a butterfly coil, employed in transmit/receive (TX/RX) mode for hyperpolarized 13C studies of pig heart with a clinical 3T scanner. The coil characterization is performed by developing an SNR model for coil performance evaluation in terms of coil resistance, sample‐induced resistance and magnetic field pattern. Experimental SNR‐vs.‐depth profiles, extracted from the [1–13C]acetate phantom chemical shift image (CSI), showed good agreement with the theoretical SNR‐vs.‐depth profiles. Moreover, the performance of the quadrature coil was compared with the single TX/RX circular and TX/RX butterfly coil, in order to verify the advantage of the proposed configuration over the single coils throughout the volume of interest for cardiac imaging in pig. Finally, the quadrature surface coil was tested by acquiring metabolic maps with hyperpolarized [1–13C]pyruvate injected i.v. in a pig. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B: 69–77, 2013
Consideration of comorbidity in risk stratification prior to prostate biopsy
Authors: Liss Michael A. , Billimek John , Osann Kathryn , Cho Jane , Moskowitz Ross , Kaplan Adam , Szabo Richard J. , Kaplan Sherrie H. , Greenfield Sheldon , Dash Atreya 
Published: April 2013

BACKGROUNDPreviously, the patient‐reported Total Illness Burden Index for Prostate Cancer (TIBI‐CaP) questionnaire and/or the physician‐reported Charlson Comorbidity Index (CCI) have provided assessments of competing comorbidity during treatment decisions for patients with prostate cancer. In the current study, the authors used these assessments to determine comorbidity and prognosis before prostate biopsy and the subsequent diagnosis of prostate cancer to identify those patients least likely to benefit from treatment.METHODSA prospective observational cohort study was performed of 104 participants aged 64.0 years ± 6.5 years from 3 institutions representing different health care delivery systems. Patients were identified before undergoing transrectal ultrasound‐guided prostate biopsy and followed for a median of 28 months. Associations between the comorbidity scores and nonelective hospital admissions were investigated using logistic regression and Cox proportional hazards models.RESULTSAmong the 104 patients who underwent prostate biopsy, 2 died during the follow‐up period. The overall hospital admission rate was 20% (21 of 104 patients). Higher scores on both the TIBI‐CaP (≥ 9) and CCI (≥ 3) were found to be significantly associated with an increased odds for hospital admission (odds ratio, 11.3 [95% confidence interval (95% CI), 2.4‐53.6] and OR, 5.7 [95% CI, 1.4‐22.4]) and hazards ratios (HRs) for time to hospital admission (HR, 3.8 [95% CI, 1.3‐11.2] and HR, 3.2 [95% CI, 1.1‐9.1]), respectively.CONCLUSIONSTIBI‐CaP and CCI scores were found to successfully predict which patients were at high risk for nonelective hospital admission. These patients are likely to have poorer health and a potentially shortened lifespan. Therefore, comorbidity analysis using these tools may help to identify those patients who are least likely to benefit from prostate cancer therapy and should avoid prostate biopsy. Cancer 2013;119:2413‐2418. © 2013 American Cancer Society.
The Factors Influencing Nonlinear Characteristics of the Short‐Circuit Current in Dye‐Sensitized Solar Cells Investigated by a Numerical Model
Authors: Shi Yushuai , Dong Xiandui 
Published: April 2013

AbstractA numerical model for interpretation of the light‐intensity‐dependent nonlinear characteristics of the short‐circuit current in dye‐sensitized solar cells is suggested. The model is based on the continuity equation and includes the influences of the nongeminate recombination between electrons and electron acceptors in the electrolyte and the geminate recombination between electrons and oxidized dye molecules. The influences of the order and rate constant of the nongeminate recombination reaction, the light‐absorption coefficient of the dye, the film thickness, the rate constant of geminate recombination, and the regeneration rate constant on the nonlinear characteristics of the short‐circuit current are simulated and analyzed. It is proposed that superlinear and sublinear characteristics of the short‐circuit current should be attributed to low electron‐collection efficiency and low dye‐regeneration efficiency, respectively. These results allow a deep understanding of the origin of the nonlinear characteristics of the short‐circuit current in solar cells.
Cooperative bargaining solution for efficient and fair spectrum management in cognitive wireless networks
Authors: Guan Zhangyu , Yuan Dongfeng , Zhang Haixia , Ding Lei 
Published: April 2013

SUMMARYThis paper studies the fairness among the primary users (PUs) and the secondary users (SUs) for resource allocation in cognitive radio systems. We propose a novel co‐opetition strategy based on the Kalai–Smorodinsky bargaining solution to balance the system efficiency and the fairness among users. The strategy formulates the spectrum sharing problem as a nonlinear and integral sum utility maximization subject to a set of constraints describing the co‐opetition among the PUs and the SUs. Then, we solve the maximization problem by proposing a heuristical method that consists of four steps: multi‐PU competition, PU's subcarrier contribution, multi‐SU competition, and SU's subcarrier contribution. Extensive simulation results are presented by comparing the co‐opetition strategy with several conventional ones, including the Kalai–Smorodinsky bargaining solution, sum rate maximization as well as the Max–Min. Results indicate that the co‐opetition strategy can jointly balance the system efficiency and fairness in multiuser resource allocation, as it is able to support more satisfied users and in the meanwhile improve the utility of those unsatisfied. Moreover, the co‐opetition can help enable the coexistence of the PUs and the SUs in cognitive radio systems. Copyright © 2013 John Wiley & Sons, Ltd.
Reevaluation of a classic phylogeographic barrier: new techniques reveal the influence of microgeographic climate variation on population divergence
Authors: Soto‐Centeno J. Angel , Barrow Lisa N. , Allen Julie M. , Reed David L. 
Published: April 2013

AbstractWe evaluated themtDNAdivergence and relationships withinGeomys pinetisto assess the status of formerly recognizedGeomystaxa. Additionally, we integrated new hypothesis‐based tests in ecological niche models (ENM) to provide greater insight into causes for divergence and potential barriers to gene flow in SoutheasternUnitedStates (Alabama,Florida, andGeorgia). OurDNAsequence dataset confirmed and strongly supported two distinct lineages withinG. pinetisoccurring east and west of theARD. Divergence date estimates showed that eastern and western lineages diverged about 1.37 Ma (1.9 Ma–830 ka). Predicted distributions fromENMswere consistent with molecular data and defined each population east and west of theARDwith little overlap. Niche identity and background similarity tests were statistically significant suggesting thatENMsfrom eastern and western lineages are not identical or more similar than expected based on random localities drawn from the environmental background.ENMsalso support the hypothesis that theARDrepresents a ribbon of unsuitable climate between more suitable areas where these populations are distributed. The estimated age of divergence between eastern and western lineages ofG. pinetissuggests that the divergence was driven by climatic conditions during Pleistocene glacial–interglacial cycles. TheARDat the contact zone of eastern and western lineages ofG. pinetisforms a significant barrier promoting microgeographic isolation that helps maintain ecological and genetic divergence.
Platinum(II) Acetylides in the Formal [2+2] Cycloaddition‐Retroelectrocyclization Reaction: Organodonor Versus Metal Activation
Authors: Tchitchanov Boris H. , Chiu Melanie , Jordan Markus , Kivala Milan , Schweizer W. Bernd , Diederich François 
Published: April 2013

AbstractFormal cycloaddition‐retroelectrocyclization (CA‐RE) reactions between electron‐donor‐activated alkynes and electron‐poor alkenes yielding cyanobuta‐1,3‐dienes have recently attracted increasing interest. The transformation has been subjected to a fundamental investigation of the relative degrees of alkyne activation by organic and metallorganic donor substituents by using platinum(II) σ‐acetylides as model substrates and studying their behavior towards the cyano carbons TCNE and TCNQ. Various cyanobutadienes were obtained in good to excellent yields and four trends in reactivity were discerned: 1) The presence of an anilino substituent clearly dominates the regioselectivity of the TCNQ addition. 2) In the absence of an organodonor, the regioselectivity is inverted. 3) When platinum(II) complexes of buta‐1,3‐diynes are used, the addition always takes place at the triple bond distal to the metal center. 4) In general, trans‐bis‐acetylides are more reactive than the corresponding cis complexes. The structural parameters of the CA‐RE adducts were investigated by X‐ray crystallography and their optical properties by UV/Vis spectroscopy, giving further insights into the structural trends and degree of intramolecular charge transfer. These fundamental investigations may enable the synthesis of new Pt‐based molecular dyads in which the effect of regioselectivity on photoinduced charge separation can be studied.
Variation in total electron content above large thunderstorms
Authors: Lay Erin H. , Shao Xuan‐Min , Carrano Charles S. 
Published: April 2013

AbstractTotal electron content (TEC) measured by Global Positioning System (GPS) receivers in the United States Great Plains is examined for three nights with large thunderstorms and for one night with little thunderstorm activity. The GPS TEC data are fit with a polynomial, and the variations are estimated by subtracting this fit from the data. We found that anomalous TEC variations are closely associated in time and space to the large underlying thunderstorms. The largest storm‐related TEC variation is observed to be ~1.4 total electron content unit (TECU) over a typical nighttime background value of several TECUs. The variations near the storm appear to have more high‐frequency content than those away from the storm, with periods of minutes to tens of minutes. No detectable localized TEC variation is observed for the thunderstorm‐quiet night.
The importance of ebullition as a mechanism of methane (CH4) loss to the atmosphere in a northern peatland
Authors: Stamp Imelda , Baird Andy J. , Heppell Catherine M. 
Published: April 2013

AbstractWe measured the escape of methane‐containing gas bubbles to the water table in two microhabitats (muddy hollows and Sphagnum‐plus‐sedge lawns) in a raised bog in West Wales, typical of many northern peatlands. Our study was unusual in its degree of replication (14 gas traps in each microhabitat). Seasonally integrated bubble loss of CH4 to the water table did not differ significantly between microhabitats. After applying an oxidation correction to give CH4 fluxes to the atmosphere, the microhabitats still did not differ. Our results suggest that ebullition is an important mechanism of CH4 loss to the atmosphere, with mean summer rates of 11.7 mg CH4 m−2 d−1 (muddy hollows) and 6.8 mg CH4 m−2 d−1 (Sphagnum‐plus‐sedge lawns). Our data show that the process is spatially and temporally very variable, and that the small sample sizes of many studies (e.g., n = 5) may lead to considerable errors in flux estimation.
Transoral laser microsurgery for the unknown primary: Role for lingual tonsillectomy
Authors: Nagel Thomas H. , Hinni Michael L. , Hayden Richard E. , Lott David G. 
Published: April 2013

BackgroundWe conducted a retrospective review of patients with unknown primary head and neck cancer who underwent a transoral laser microsurgery (TLM)‐assisted search for an occult tumor.MethodsFifty‐two patients at a single center with unknown primaries of squamous cell carcinoma (SCC) were treated with a surgical algorithm.ResultsThe overall rate of primary tumor identification was 75% (39 of 52 patients). When selecting those cases in which a TLM algorithm with lingual tonsillectomy was utilized, the detection rate was 86% (31 of 36). Tumors were most commonly found in the lingual (65.0%) and palatine tonsils (27.5%). When directed biopsies did not locate a tumor, a higher yield was obtained with the addition of a lingual tonsillectomy in 8 patients.ConclusionA surgical algorithm for the unknown primary that includes TLM‐assisted techniques, including a lingual tonsillectomy, offers the greatest likelihood of successfully detecting the location of occult primary tumors. © 2014 Wiley Periodicals, Inc. Head Neck 36: 942–946, 2014