bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalytic Asymmetric Formal [3+3] Cycloaddition of an Azomethine Ylide with 3‐Indolylmethanol: Enantioselective Construction of a Six‐Membered Piperidine Framework
Authors: Shi Feng , Zhu Ren‐Yi , Dai Wei , Wang Cong‐Shuai , Tu Shu‐Jiang 
Published: February 2014

AbstractA catalytic asymmetric formal [3+3] cycloaddition of 3‐indolylmethanol and an in situ‐generated azomethine ylide has been established to construct a chiral six‐membered piperidine framework with two stereogenic centers. This approach not only represents the first enantioselective cycloaddition of isatin‐derived 3‐indolylmethanol, but also has realized an unusual enantioselective formal [3+3] cycloaddition of azomethine ylide rather than its common [3+2] cycloadditions. Besides, this protocol combines the merits of a multicomponent reaction and organocatalysis, which efficiently assembles a variety of isatin‐derived 3‐indolylmethanols, aldehydes, and amino esters into structurally diverse spiro[indoline‐3,4′‐pyridoindoles] with one all‐carbon quaternary stereogenic center in high yields and excellent enantioselectivities (up to 93 % yield, >99 % enantiomeric excess (ee)). Although the diastereoselectivity of the reaction is generally moderate, most of the diastereomers can be separated by using column chromatography followed by preparative TLC.
Organocatalytic One‐Pot Synthesis of Highly Substituted Pyridazines from Morita–Baylis–Hillman Carbonates and Diazo Compounds
Authors: Mao Haibin , Lin Aijun , Tang Zhongkai , Hu Hongwen , Zhu Chengjian , Cheng Yixiang 
Published: February 2014

AbstractA biologically inspired organocatalytic one‐pot synthesis of highly functionalized pyridazines, which are ubiquitous structural units in a number of biologically active compounds, has been developed by starting from readily available diazo compounds and Morita–Baylis–Hillman (MBH) carbonates. Under mild reaction conditions, this synthetic route tolerated significant substrate variation to deliver a broad range of substituted products, including CF3‐substituted pyridazines derivatives. Moreover, the introduction of trifluoromethyl groups into the ring of pyridazine could be completed conveniently from 2,2,2‐trifluorodiazoethane.
Highly Enantioselective Extraction of Underivatized Amino Acids by the Uryl‐Pendant Hydroxyphenyl‐Binol Ketone
Authors: Huang Haofei , Chen Qian , Choi Misun , Nandhakumar Raju , Su Zhishan , Ham Sihyun , Kim Kwan Mook 
Published: February 2014

AbstractThe hydroxyphenyl chiral ketone, (S)‐3, reacts with D‐amino acids bearing hydrophobic side chains exclusively over the L‐amino acids in a two‐phase liquid–liquid extraction, and thus acts as a highly stereoselective extractant. Calculations for the energy‐minimized structures for the imine diastereomers and the comparison of the selectivities with other phenyl ketones, (S)‐4 and (S)‐5, demonstrate that the hydrogen bond between the carboxylate group and the phenolic hydroxyl group contributes to the remarkable enantioselectivities. The multiple hydrogen bonds present in the imine of (S)‐3 reinforce the rigidity, and results in the difference between the stabilities of the imine diastereomers. The imine could be hydrolyzed in methanolic HCl solution, and the extraction of the evaporated residues revived the organic layer of (S)‐3, which could enter into a new extractive cycle and leaves the D‐amino acid with enantiomeric excess (ee) values of over 97 % in the aqueous layer.
Inorganic Double‐Helix Nanotoroid of Simple LithiumPhosphorus Species
Authors: Ivanov Alexander S. , Boldyrev Alexander I. , Frenking Gernot 
Published: February 2014

AbstractA theoretical study of Li90P90, which possesses a circular double‐helix structure that resembles the Watson–Crick DNA structure, is reported. This is a new bonding motif in inorganic chemistry. The calculations show that the molecule might become synthesized and that it could be a model for other inorganic species which possess a double‐helix structure.
Stable Mixed‐Valent Radicals from Platinum(II) Complexes of a Bis(dioxolene) Ligand
Authors: Loughrey Jonathan J. , Sproules Stephen , McInnes Eric J. L. , Hardie Michaele J. , Halcrow Malcolm A. 
Published: February 2014

AbstractThree diplatinum(II) complexes [{PtL}2(μ‐thea)] (H4thea=2,3,6,7‐tetrahydroxy‐9,10‐dimethyl‐9,10‐dihydro‐9,10‐ethanoanthracene) have been prepared, with diphosphine or bipyridyl “L” co‐ligands. One‐electron oxidation of these complexes gave radical cations containing a mixed‐valent [thea]3− ligand with discrete catecholate and semiquinonate centers separated by quaternary methylene spacers. The electronic character of these radicals is near the Robin–Day class II/III border determined by UV/Vis/NIR and EPR spectroscopies. Crystal‐structure determinations and a DFT calculation imply that oxidation of the thea4− ligand may lead to an increased through‐space interaction between the dioxolene π systems.
Saturated Excitation Microscopy with Optimized Excitation Modulation
Authors: Yonemaru Yasuo , Yamanaka Masahito , Smith Nicholas I. , Kawata Satoshi , Fujita Katsumasa 
Published: February 2014

AbstractSaturated excitation (SAX) microscopy utilizes the nonlinear relation between fluorescence emission and excitation under saturated excitation to improve the spatial resolution of confocal microscopy. In this study, we theoretically and experimentally investigate the saturation of fluorescence excitation under modulated excitation to optimize the excitation conditions for SAX microscopy. Calculation of the relationships between fluorescence and excitation intensity with different modulation frequencies reveals that the lifetime of the triplet state of the fluorescent probe strongly affects the strength of the demodulated fluorescence signals. We also find that photobleaching shows little dependence on the modulation frequency. These investigations allow us to determine the optimum excitation conditions, that is, the conditions providing sufficient fluorescence saturation without strong photobleaching. For a sample stained with ATTO Rho6G phalloidin, we estimate the optimal excitation conditions, which are produced with 50 kHz excitation modulation and a 50 μsec pixel dwell time, and successfully perform three‐dimensional imaging with sub‐diffraction resolution.
Organohelium Compounds: Structures, Stabilities and Chemical Bonding Analyses
Authors: Fourré Isabelle , Alvarez Elsa , Chaquin Patrick 
Published: February 2014

AbstractThis paper deals with the possibility of forming short and relatively strong carbon–helium bonds in small typical organic molecules through substitution of one or several H atoms by He+. A structural and energetics study (based on high‐level calculations) of this unusual bonding, as well as a topological characterization of the resulting cations, is undertaken. Stable species generally requires substitution of about half of the hydrogen atoms for formation. Under these conditions, the number of such species appears to be potentially unlimited. “True” CHe bonds exhibit equilibrium distances ranging from 1.327 (C2H2He22+) to 1.129 Å (He2CO2+). The energies of neutral He releasing range from approximately 5 kcal mol−1[He2CO2+, (Z)‐C2H2He22+] to 25 kcal mol−1(C2HHe33+), but remain most frequently around 10 kcal mol−1. However, most of He+‐substituted hydrocarbons are metastable with respect to CC cleavage, except derivatives of ethene. Atoms in molecules (AIM) and electron localization function (ELF) topological descriptors classify the CHe bond as a weak charge‐shift interaction [S. Shaik, D. Danovich, B. Silvi, D. L. Lauvergnat, P. C. Hiberty,Chem. Eur. J. 2005, 11, 6358–6371] in agreement with a recent publication by Rzepa [S. H. Rzepa,Nat. Chem. 2010, 2, 390–393]. He2CO2+is the only investigated compound that presents a CHe bonding ELF basin, which indicates a non‐negligible covalent contribution to the bond. Other modifications in the electronic structure, such as the breaking of the triple bond in ethyne derivatives or the loss of aromaticity in C6H3He33+, are also nicely revealed by the ELF topology.
A workflow task scheduling algorithm based on the resources' fuzzy clustering in cloud computing environment
Authors: Guo Fengyu , Yu Long , Tian Shengwei , Yu Jiong 
Published: February 2014

SummaryCloud computing is the key and frontier field of the current domestic and international computer technology, workflow task scheduling plays an important part of cloud computing, which is a policy that maps tasks to appropriate resources to execute. Effective task scheduling is essential for obtaining high performance in cloud environment. In this paper, we present a workflow task scheduling algorithm based on the resources' fuzzy clustering named FCBWTS. The major objective of scheduling is to minimize makespan of the precedence constrained applications, which can be modeled as a directed acyclic graph. In FCBWTS, the resource characteristics of cloud computing are considered, a group of characteristics, which describe the synthetic performance of processing units in the resource system, are defined in this paper. With these characteristics and the execution time influence of the ready task in the critical path, processing unit network is pretreated by fuzzy clustering method in order to realize the reasonable partition of processor network. Therefore, it largely reduces the cost in deciding which processor to execute the current task. Comparison on performance evaluation using both the case data in the recent literature and randomly generated directed acyclic graphs shows that this algorithm has outperformed the HEFT, DLS algorithms both in makespan and scheduling time consumed. Copyright © 2014 John Wiley & Sons, Ltd.
A novel noncooperative game competing model using generalized simple additive weighting method to perform network selection in heterogeneous wireless networks
Authors: Salih Yass K. , Hang See Ong , Ibrahim Rabha W. , Yussof Salman , Iqbal Azlan 
Published: February 2014

SummaryNetwork selection mechanisms have a significant role in guaranteeing the QoS for users in a heterogeneous wireless networks environment. These mechanisms allow the selection of an optimal wireless network to satisfy the needs of users. Users are provided with the opportunity to select from multiple connectivity opportunities available all over various wireless networks. Furthermore, the network operators themselves can execute active selection strategies that facilitate proper decision making, in which user preferences are considered. This study proposes a new noncooperative competing game‐theoretic model and strategy space based on user preference. This model can solve network selection problems and capture the inter‐linkages of decisions taken by various networks. A generalized simple additive weighting method is incorporated into the framework of noncooperative game theory. In addition, the utility function is employed to assess the usefulness of the system. Simulation results and analysis illustrate the efficacy of the suggested model in attaining optimum network utility for heterogeneous wireless networks while optimizing user satisfaction. Copyright © 2014 John Wiley & Sons, Ltd.
Button‐based method for the prevention of near field communication relay attacks
Authors: Kang Sukin , Kim Jonguk , Hong Manpyo 
Published: February 2014

SummaryIn this study, we developed a novel method for preventing relay attacks over near field communication (NFC) using a simple interface. NFC provides standardized short‐range contactless communication using one of the radio frequency identification communication channels. NFC‐enabled mobile devices can exchange information in close proximity (within 4 cm). In particular, modern mobile phones have adopted NFC technology because of its promising functionalities, for example, mobile payments, Bluetooth pairing, and electronic keys. The distance limitation of NFC communication offers security advantages against passive or active attackers, but it is still vulnerable to relay attacks. During a relay attack, adversaries relay messages between two legitimate participants without any attempt at message modification. There is no requirement for knowledge of a cryptographic key or to share secrets with victims, therefore encrypting messages is not a solution that prevents relay attacks. We propose a new method for relay attack prevention, which uses a simple interface with only one button. In our scheme, the elapsed time of button pressing is used for verification. Our experimental results obtained using the proposed scheme demonstrated the accuracy of our method for verifying human users and the difficulties experienced by human attackers. Copyright © 2014 John Wiley & Sons, Ltd.
A novel grouped multilevel dynamic space–time trellis coding scheme
Authors: Jain Dharmvir , Sharma Sanjay 
Published: February 2014

SummaryGrouped multilevel space–time trellis codes (GMLSTTCs) utilize multilevel coding, antenna grouping and STTCs for simultaneously providing coding gain, diversity improvement and increased spectral efficiency. The performance of GMLSTTCs is limited because of using predefined STTCs as component codes in multilevel coding. GMLSTTCs assume perfect channel state information (CSI) at the receiver only and do not consider the CSI at the transmitter. It has been shown that when perfect or partial CSI is available at the transmitter, the performance and capacity of a space–time coded system can be further improved. In this paper, we present new codes, designed by combining GMLSTTCs and the CSI information at the transmitter, henceforth referred to as grouped multilevel dynamic space–time trellis codes (GMLDSTTCs). A code set having different sets of generator sequences is selected that matches best with the current channel profile. The selected code set is used for generating DSTTCs. DSTTCs are used as component codes in GMLSTTCs instead of predefined STTCs to generate GMLDSTTCs. Analysis and simulation results show that GMLDSTTCs outperform GMLSTTCs. Copyright © 2014 John Wiley & Sons, Ltd.
Restrictive mitral annuloplasty with or without surgical ventricular reconstruction in ischaemic cardiomyopathy: impacts on neurohormonal activation, reverse left ventricular remodelling and survival
Authors: Kainuma Satoshi , Taniguchi Kazuhiro , Toda Koichi , Funatsu Toshihiro , Miyagawa Shigeru , Kondoh Haruhiko , Masai Takafumi , Otake Shigeaki , Yoshikawa Yasushi , Nishi Hiroyuki , Sakaguchi Taichi , Ueno Takayoshi , Kuratani Toru , Daimon Takashi , Sawa Yoshiki 
Published: February 2014

AimsIn the STICH trial, adding surgical ventricular reconstruction (SVR) to coronary artery bypass grafting (CABG) reduced LV end‐systolic volume index (LVESVI) by 19%, as compared with 6% with CABG alone, providing no survival or functional benefits. Herein, we compared the efficacy of restrictive mitral annuloplasty (RMA) alone with that of RMA combined with SVR in patients with functional mitral regurgitation (MR).Methods and resultsOne hundred and six patients with ischaemic cardiomyopathy underwent RMA with (n = 52) or without SVR (n = 54) for functional MR. Pre‐ and post‐operative (1 month) left ventriculography and longitudinal measurements of plasma BNP were performed. Pre‐operatively, patients who underwent RMA plus SVR had a larger LVESVI (126 ± 26 vs. 100 ± 24 mL/m2, P < 0.0001). After surgery, RMA plus SVR reduced LVESVI more than RMA alone (43% vs. 22%, P <0.0001), yielding a nearly identical post‐operative LVESVI (71 ± 17 vs. 78 ± 26 mL/m2). Survival rate was not different between the groups (4‐year survival, 62% vs. 62%, P = 0.99), though among patients with pre‐operative LVESVI ranging from 105 to 150 mL/m2, that was higher in the RMA plus SVR group (73% vs. 40%, P = 0.046), accompanied by a larger percentage reduction in plasma BNP from baseline to the latest follow‐up examination (63 ± 34% vs. 34 ± 46%, P = 0.012). After propensity score adjustment, patients with LVESVI ranging from 105 to 150 mL/m2 who underwent RMA alone showed a greater association with mortality (hazard ratio 7.5, 95% confidence interval 2.1–27, P = 0.010), as compared with those with LVESVI <105 mL/m2 who underwent RMA alone.ConclusionsRMA plus SVR reduced LVESVI to a greater degree than RMA alone, neutralizing anticipated worse prognosis. Selected patients with functional MR and advanced LV remodelling may benefit by adding SVR to RMA.
Connective tissue growth factor and cardiac diastolic dysfunction: human data from the Taiwan Diastolic Heart Failure Registry and molecular basis by cellular and animal models
Authors: Wu Cho‐Kai , Wang Yi‐Chih , Lee Jen‐Kuang , Chang Sheng‐Nan , Su Mao‐Yuan , Yeh Huei‐Ming , Su Ming‐Jai , Chen Jin‐Jer , Chiang Fu‐Tien , Hwang Juey‐Jen , Lin Jiunn‐Lee , Tsai Chia‐Ti 
Published: February 2014

AimsConnective tissue growth factor (CTGF) is an emerging marker for tissue fibrosis. We investigated the association between CTGF and cardiac diastolic function using cellular and animal models and clinical human data.Methods and resultsA total of 125 patients with a diagnosis of diastolic heart failure (DHF) were recruited from 1283 patients of the Taiwan Diastolic Heart Failure Registry. The severity of DHF was determined by tissue Doppler imaging (E/e′). Cardiac magnetic resonance imaging (CMRI) was used to evaluate myocardial fibrosis in some of the patients (n = 25). Stretch of cardiomyocytes on a flexible membrane base serves as a cellular phenotype of cardiac diastolic dysfunction (DD). A canine model of DD was induced by aortic banding. A significant correlation was found between plasma CTGF and E/e′ in DHF patients. The severity of cardiac fibrosis evaluated by CMRI also correlated with CTGF. In the cell model, stretch increased secretion of CTGF from cardiomyocytes. In the canine model, myocardial tissue CTGF expression and fibrosis significantly increased after 2 weeks of aortic banding. Notably, the expression of CTGF paralleled the severity of LV DD (r = 0.40, P < 0.001 for E/e') and haemodynamic changes (r = 0.80, P < 0.001). After adjusting for confounding factors, CTGF levels still correlated with diastolic parameters in both human and canine models (human plasma CTGF, P < 0.001; canine tissue CTGF, P = 0.04).ConclusionPlasma CTGF level correlated with the severity of DD and tissue fibrosis in DHF patients. The mechanism may be through myocardial stretch. Our study indicated that CTGF may serve as an early marker for DHF.
The renal arterial resistance index: a marker of renal function with an independent and incremental role in predicting heart failure progression
Authors: Ciccone Marco Matteo , Iacoviello Massimo , Gesualdo Loreto , Puzzovivo Agata , Antoncecchi Valeria , Doronzo Annalisa , Monitillo Francesco , Citarelli Gaetano , Paradies Valeria , Favale Stefano 
Published: February 2014

AimsThe renal arterial resistance index (RRI) is a measure of renal blood flow obtained by Doppler ultrasonography, which has been demonstrated to reflect both vascular and parenchymal renal abnormalities. The aim of the study was to evaluate clinical correlates and the prognostic relevance of RRI in a group of patients affected by chronic heart failure (CHF).Methods and resultsWe enrolled 250 CHF outpatients in a stable clinical condition and receiving conventional therapy. Peak systolic velocity and end‐diastolic velocity of a segmental renal artery were obtained by pulsed Doppler flow. Then the RRI was calculated. Standard renal function assessment was obtained by the measurement of creatinine serum levels and the estimation of the glomerular filtration rate (GFR). During follow‐up (21.4 ± 11.3 months), 41 patients experienced heart failure progression (hospitalization and/or heart transplantation and/or death due to worsening heart failure). Considered as a continuous variable, RRI was associated with events at univariate [hazard ratio (HR) 1.14; 95% confidence interval (CI) 1.09–1.19; P < 0.001] as well as at multivariate Cox regression analysis (HR 1.08; 95% CI 1.02–1.13; P = 0.004) after correction for independent predictors of the reference model. When the RRI was added to the reference model including GFR, a significant improvement of reclassification according to both category‐free net reclassification improvement (NRI, 47%; 95% CI 13–80%; P = 0.006) and integrated discrimination improvement (IDI, 0.034; 95% CI 0.006–0.061; P = 0.016) was observed.ConclusionsQuantification of arterial renal perfusion provides a new parameter that independently predicts CHF patient outcome, thus strengthening its possible role in current clinical practice in order to better characterize renal function and stratify patients' prognosis.
The effect of thyroid function on clinical outcome in patients with heart failure
Authors: Chen Shmuel , Shauer Ayelet , Zwas Donna R. , Lotan Chaim , Keren Andre , Gotsman Israel 
Published: February 2014

AimsThyroid dysfunction is known to effect cardiac function and is a risk factor for developing heart failure (HF). Data regarding the clinical significance of thyroid‐stimulating hormone (TSH) levels alone as a predictor of outcome in patients with HF is sparse. We evaluated the significance of TSH on clinical outcome in a large cohort of patients with chronic HF.Methods and resultsPatients with a diagnosis of HF at a Health Maintenance Organization (n = 5599) were followed for cardiac‐related hospitalizations and death. Median TSH levels were 2.2 mIU/L (interquartile range 1.4–3.5). We divided patients into quartiles based on TSH levels. Median follow‐up time was 434 days and the overall mortality rate was 13.2%. Both a high and a low TSH level was associated with an increased mortality rate. Cox regression analysis after adjustment for other significant predictors demonstrated that the highest TSH quartile was associated with increased mortality compared with those with the lowest mortality [second quartile: TSH 1.4–2.2 mIU/L, hazard ratio (HR) 1.36, 95% confidence interval (CI) 1.08–1.71, P = 0.01]. TSH was also an independent predictor of death and cardiac‐related hospitalization. Analysis of patients not on levothyroxine treatment (78%) demonstrated that TSH was an even stronger predictor of mortality (HR 1.54, 95% CI 1.17–2.03, P = 0.002). Additional analysis based on accepted clinical cut‐offs of TSH demonstrated that increasing TSH levels above normal were independently associated with increased mortality and cardiac‐related hospitalizations.ConclusionsIncreased TSH levels are associated with worse clinical outcome in patients with HF. Thyroid imbalance confers significant risk in HF and warrants attention.