bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective Aza‐Ene‐type Reactions of Enamides with Gold Carbenes Generated from α‐Diazoesters
Authors: Zhao Feng , Li Nan , Zhang Tao , Han Zhi‐Yong , Luo Shi‐Wei , Gong Liu‐Zhu 
Published: February 2017

AbstractCarbophilic gold carbenes generated from the decomposition of α‐diazoesters show high reactivity towards enamides, leading to an unprecedented aza‐ene‐type reaction. The presence of 0.1 mol % of a chiral Brønsted acid co‐catalyst is sufficient to give synthetically relevant γ‐keto esters in excellent yields and selectivities (up to 99 % yield, 97 % ee).
Inversion of the Side‐Chain Stereochemistry of Indvidual Thr or Ile Residues in a Protein Molecule: Impact on the Folding, Stability, and Structure of the ShK Toxin
Authors: Dang Bobo , Shen Rong , Kubota Tomoya , Mandal Kalyaneswar , Bezanilla Francisco , Roux Benoit , Kent Stephen B. H. 
Published: February 2017

AbstractShK toxin is a cysteine‐rich 35‐residue protein ion‐channel ligand isolated from the sea anemone Stichodactyla helianthus. In this work, we studied the effect of inverting the side chain stereochemistry of individual Thr or Ile residues on the properties of the ShK protein. Molecular dynamics simulations were used to calculate the free energy cost of inverting the side‐chain stereochemistry of individual Thr or Ile residues. Guided by the computational results, we used chemical protein synthesis to prepare three ShK polypeptide chain analogues, each containing either an allo‐Thr or an allo‐Ile residue. The three allo‐Thr or allo‐Ile‐containing ShK polypeptides were able to fold into defined protein products, but with different folding propensities. Their relative thermal stabilities were measured and were consistent with the MD simulation data. Structures of the three ShK analogue proteins were determined by quasi‐racemic X‐ray crystallography and were similar to wild‐type ShK. All three ShK analogues retained ion‐channel blocking activity.
Enantioselective Dearomatization of Naphthol Derivatives with Allylic Alcohols by Cooperative Iridium and Brønsted Acid Catalysis
Authors: Shen Dan , Chen Qiliang , Yan Peipei , Zeng Xiaofei , Zhong Guofu 
Published: February 2017

AbstractThe combination of a transition‐metal catalyst and organocatalyst was designed to achieve a highly enantioselective system for the allylic dearomatization reaction of naphthols with racemic secondary allylic alcohols. The desired β‐naphthalenones, bearing an all‐carbon quaternary center, were obtained in good yields with high chemo‐ and enantioselectivities. The cooperative catalytic system, involving a chiral iridium complex and phosphoric acid, provided measurable improvements in yields, and chemo‐ and enantioselectivities relative to single‐catalyst systems. Control experiments indicated that the chiral iridium complex functions as a key species in the control of the absolute configuration, thus enabling the formation of both β‐naphthalenone enantiomers by simply employing opposite enantiomeric ligands.
Spongy Gels by a Top‐Down Approach from Polymer Fibrous Sponges
Authors: Jiang Shaohua , Duan Gaigai , Kuhn Ute , Mörl Michaela , Altstädt Volker , Yarin Alexander L. , Greiner Andreas 
Published: February 2017

AbstractUltralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel‐like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom‐up process. In contrast, the spongy gels are formed by a top‐down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel‐like material. The spongy gels are independent of a time‐consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non‐wetting liquids dispersed in the sponge.
Zum Nachweis der Abtragung von Vertikalkräften bei Verbauwänden
Authors: Becker Patrick 
Published: February 2017

AbstractBei der Abtragung von Vertikalkräften bei Verbauwänden werden Erddruck und Erdwiderstand mit unterschiedlichen Mobilisierungsgraden für die Bemessung im Grenzzustand der Tragfähigkeit (ULS) beim Nachweis gegen Versinken berücksichtigt. Auf der Erdseite wird die Vertikalkomponente des Erddrucks an den aus der Biegebemessung und der Ermittlung der Einbindetiefe resultierenden mobilisierten erhöhten aktiven oder aktiven Erddruck gekoppelt. Die Festlegung des aktiven Erddruckneigungswinkels erfolgt dabei in der Regel ohne Berücksichtigung der aus der Vertikalkraft resultierenden Relativverschiebung. Es hat sich zwischenzeitlich herausgestellt, dass mit Umstellung vom Global‐ auf das Teilsicherheitskonzept der Nachweis der äußeren vertikalen Tragfähigkeit vermehrt bemessungsrelevant werden kann. In diesem Beitrag wird die Abtragung von Vertikalkräften bei Verbauwänden mit numerischen Methoden untersucht und gezeigt, dass für den Nachweis gegen Versinken im Grenzzustand der Tragfähigkeit eine Entkopplung der vertikalen Widerstände von den horizontalen Beanspruchungen aus der Biegebemessung möglich ist. Darüber hinaus werden Ansätze zur Berücksichtigung der mobilisierten Widerstände bei der Nachweisführung zur Diskussion gestellt.
Staging of pancreatic cancer based on the number of positive lymph nodes
Authors: Tarantino I , Warschkow R , Hackert T , Schmied B M , Büchler M W , Strobel O , Ulrich A 
Published: February 2017

AbstractBackgroundThe International Study Group on Pancreatic Surgery has stated that at least 12 lymph nodes should be evaluated for staging of pancreatic cancer. The aim of this population-based study was to evaluate whether the number of positive lymph nodes refines staging.MethodsPatients who underwent pancreatectomy for stage I–II pancreatic cancer between 2004 and 2012 were identified from the Surveillance, Epidemiology, and End Results database. The predictive value of the number of positive lymph nodes for survival was assessed by generalized receiver operating characteristic (ROC) curve analysis and propensity score-adjusted Cox regression analysis.ResultsSome 5036 patients were included, with a median of 18 (i.q.r. 15–24) lymph nodes examined. Positive lymph nodes were found in 3555 patients (70·6 per cent). The median duration of follow-up was 15 (i.q.r. 8–28) months. ROC curve analysis revealed that two positive lymph nodes best discriminated overall survival. Patients with one or two positive lymph nodes (pN1a) and those with three or more positive lymph nodes (pN1b) had an increased risk of overall mortality compared with patients who were node-negative (pN0): hazard ratio (HR) 1·47 (95 per cent c.i. 1·33 to 1·64) and HR 2·01 (1·82 to 2·22) respectively. These findings were confirmed by propensity score-adjusted Cox regression analysis. The 5-year overall survival rates were 39·8 (95 per cent c.i. 36·5 to 43·3) per cent for patients with pN0, 21·0 (18·6 to 23·6) per cent for those with pN1a and 11·4 (9·9 to 13·3) per cent for patients with pN1b disease.ConclusionThe number of positive lymph nodes in the resection specimen is a prognostic factor in patients with pancreatic cancer.
Construction of Hierarchical Copper‐Based Metal–Organic Framework Nanoarrays as Functional Structured Catalysts
Authors: Zhang Tianyu , Liu Wenxian , Meng Ge , Yang Qiu , Sun Xiaoming , Liu Junfeng 
Published: February 2017

AbstractThe immobilization of metal–organic framework (MOF) materials in a three‐dimensional (3 D) and oriented arrangement is critical for their application in heterogeneous catalysis. In this work, a coordination replication strategy was developed to construct Cu‐based MOFs into 3 D hierarchical nanoarray architectures by using Cu(OH)2 nanorod arrays as a sacrificial template. The Cu(OH)2 nanorod arrays served as the Cu source and coordinated with an organic ligand to form MOF crystals, and they also served as the 3 D substrate to support the growth of the Cu‐based MOFs. This strategy could also be applied to synthesize various hierarchical Cu‐based MOF arrays, which demonstrated the general efficacy of the method. Owing to their unique structural advantages (hierarchical porosity, large surface area, and intimate contact with the 3 D substrate), these MOF nanoarrays exhibit excellent catalytic activity and cycling stability in heterogeneous catalysis as structured catalysts. This strategy opens up new possibilities for the construction of immobilized MOF‐based 3 D nanoarrays for multipurpose applications.
NiMn2O4 Nanosheet‐Decorated Hierarchically Porous Polyaromatic Carbon Spheres for High‐Performance Supercapacitors
Authors: Kim Mi Ri , NaiduKalla Reddi Mohan , Kim Seok , Kim Mi‐Ra , Kim Il 
Published: February 2017

AbstractWe have designed and synthesized hierarchically porous and spherical carbons decorated with a nickel manganese oxide (NiMn2O4) and utilized them as a pseudocapacitor electrode. The polyanthracene (PAT)‐based carbon materials were firstly synthesized by the self‐polymerization of bromomethylated anthracene in the presence of zinc bromide as a catalyst and bromomethyl methyl ether as a crosslinker. The carbon materials with a 3D network were fabricated by direct carbonization and activation of the as‐prepared PAT. The micro‐, meso‐, and macroporous 3D carbon materials are characterized by a large specific surface area, an electrolyte−electrode interface area, and a continuous electron transport path. To produce high‐performance pseudocapacitor electrodes, NiMn2O4‐decorated carbon hybrid materials (C@NiMn2O4) have also been synthesized by using a hydrothermal method. The C@NiMn2O4 composites exhibit a maximum specific capacitance of 470.7 F g−1 at a current density of 1 A g−1, good rate capability of 74.6 %, and excellent capacitance retention of 89.6 % at a current density of 10 A g−1 following 5000 cycles. Based on these results, the electrode shows good potential for future supercapacitor applications.
Facile Synthesis of a Carbon Nitride/Reduced Graphene Oxide/Nickel Hydroxide Nanocomposite for Oxygen Reduction in Alkaline Media
Authors: Amiri Mona , Konda Suresh K. , Chen Aicheng 
Published: February 2017

AbstractAn efficient electrocatalyst, based on a nanocomposite involving nickel hydroxide, carbon nitride, and reduced graphene oxide, is synthesized through a facile one‐step electrochemical process for the oxygen reduction reaction in alkaline media. As this novel nanocomposite is comprised of low‐cost, earth‐abundant materials, the good catalytic activity, high stability, and methanol tolerance make this non‐precious‐metal‐based catalyst promising for practical applications.
Asymmetric Oxidative Cycloetherification of Naphtholic Alcohols
Authors: Jain Nikita , Xu Sanjia , Ciufolini Marco A. 
Published: February 2017

AbstractThe catalytic, enantioselective oxidative cyclization of naphthol‐derived carboxylic acids mediated by chiral hypervalent iodine reagents has been studied extensively in the recent past, but analogous reactions of non‐carboxylic substrates are yet unknown. This paper describes a catalytic, enantioselective, hypervalent iodine‐promoted oxidative cycloetherification reaction of naphtholic alcohols. The new process relies on a variant of the Uyanik–Ishihara catalyst, in which the stereogenic centers have been relocated closer to the iodine atom. The new catalyst design affords optical yields comparable to those available with Uyanik–Ishihara iodides, but chemical yields are sensibly higher, at least with the tests substrates. An even more problematic reaction is the catalytic, enantioselective oxidative cyclization of naphtholic sulfonamides. In this case, the new catalyst affords significantly higher optical inductions than Uyanik–Ishihara iodides. The kinetic resolution of particular naphtholic alcohols is demonstrated. The absolute configuration of a numver of enantioenriched compounds obtained in this study was ascertained by X‐ray diffractometry.
Sexual and relationship health among survivors of oropharyngeal or oral cavity squamous cell carcinoma
Authors: D'Souza Gypsyamber , Robbins Hilary A. 
Published: February 2017

Six months after diagnosis, some patients with oral squamous cell carcinoma have decreased their sexual behavior, whereas others have stopped having sex, highlighting a patient group that could benefit from more relationship‐oriented support. However, most patients remain sexually active and report strong relationship dynamics, and they indicate that having a human papillomavirus‐related diagnosis does not appear to add additional marital stress or change sexual intimacy beyond that experienced by patients with human papillomavirus‐unrelated oral squamous cell cancer.See also pages 1156‐65.
Molecule Counts in Localization Microscopy with Organic Fluorophores
Authors: Karathanasis Christos , Fricke Franziska , Hummer Gerhard , Heilemann Mike 
Published: February 2017

AbstractSingle‐molecule localization microscopy (SMLM) can be used to count fluorescently labeled molecules even when they are not individually resolved. We demonstrate SMLM molecule counting for nucleic acids labeled with the organic fluorophore Alexa Fluor 647 and imaged under photoswitching conditions. From the observed distributions of the number of fluorophore blinking events, we extract the number of fluorophores per spot using a statistical model. We validate the molecule counting method for single Alexa Fluor 647 fluorophores, and for trimers of Alexa Fluor 647 constructed on a DNA origami structure. This simple counting strategy enables quantitative super‐resolution imaging with organic fluorophores.
Analysis of downlink power control and cooperation scheme for two‐tier heterogeneous cellular network
Authors: Swami Pragya , Mishra Mukesh Kumar , Trivedi Aditya 
Published: February 2017

SummaryThe traditional cellular network cannot keep pace with the dramatic growth in data traffic due to exponentially increasing number of multimedia applications and mobile subscribers. Recently, femto base stations (FBSs) are deployed with the macro base station (MBS) tier for off‐loading the data traffic and to improve the indoor coverage of the heterogeneous cellular network. However, FBS deployment also increases the cross‐tier interference of the heterogeneous cellular network resulting in outage performance degradation of MBS tier. This work develops an analytical framework to limit the cross‐tier interference of MBS tier using power control scheme (PCS). The proposed PCS works on path loss inversion and location‐based power level rule for FBS. Moreover, a cooperation scheme and an association policy with MBS (CSAPM) are introduced to improve the outage performance of the FBS tier. Tools from the stochastic geometry are used for deriving the signal to interference and noise ratio outage probability, total outage probability, and area spectral efficiency (ASE) of MBS tier and FBS tier. Additionally, ASE maximization problem is formulated to evaluate the optimal density of FBSs. The effectiveness of the proposed PCS and CSAPM on outage performance and ASE are numerically demonstrated. It is noted from the results that the proposed CSAPM can compensate the loss in outage performance of FBS tier due to PCS. Finally, simulation results validate the analytical results.
Uninterrupted Ethernet using failure‐adaptive spanning trees
Authors: Chu Hung‐Mao , Chen Chang‐Teng , Wang Pi‐Chung 
Published: February 2017

SummaryFailure recovery is a critical performance issue in large‐scale Ethernet networks. The standard mechanisms of link‐failure recovery in spanning tree protocol (STP) and rapid STP may cause interruptions of data transmission because of long recovery time. Several previous approaches construct multiple alternative trees to avoid such interruptions caused by single or multiple failed links based on multiple STP. However, the prototypical protocol of standard root election would result in the same root switch for different spanning trees. Hence, the alternative trees may become invalid if a failed link appears in more than 1 spanning tree. Our scheme, failure‐adaptive spanning trees (FAST), improves the resilience of Ethernet with multiple spanning trees. It avoids simultaneous faults of multiple spanning trees by incorporating a new approach to electing an appropriate root switch for each spanning tree. Failure‐adaptive spanning trees also use active links of alternative spanning trees for data transmission. The paths of different spanning trees can thus act as shortcuts to shorten frame paths. The experimental results demonstrate that FAST can sustain network throughput under multiple link failures. The FAST also balances both link and switch loads.
Contribution to the Study of the Reduction of Energy Consumption through the Exchanger Coupled Conventional Air‐Ground‐Air Conditioner. Application to the Building
Authors: Benhamza Mohamed E. , Brima Abdelhafid , Houda Saddok , Moummi Noureddine 
Published: February 2017

AbstractIn this study, a new method of using the earth‐air heat exchangers to reduce energy consumption in buildings is discussed. The idea is to couple the EAHE with the condenser of a residential air conditioning system to enhance the effectiveness of the latter. Under the climatic conditions of high temperature in summer (south‐eastern region of Algeria), which can sometimes exceed 50 °C, what makes the heat exchange between the air conditioner and the external environment very difficult in addition to the problem of thermal comfort and the cost of energy consumption. Conducting a simulation by the TRNSYS software that allows to couple the model of the EAHE with the condenser of a residential air conditioner and connect the system with a building. The results show a clear reduction in the energy consumed by this system in connection with the direct use of the air conditioner and increase air conditioning efficiency, coefficient of performance, and energy efficiency rating. In this paper the Hollmuller model was ameliorated and the obtained results are in concord with it. The system is capable of resolving the problem of mal cooling of buildings by air conditioners under critical climate conditions, in addition to lowering the heat output of the condenser, and reducing its effect on the environment.
An investigation into the freshwater variability in West Africa during 1979‐2010
Authors: Andam‐Akorful S. A. , Ferreira V. G. , Ndehedehe C. E. , Quaye‐Ballard J. A. 
Published: February 2017

ABSTRACTAfter the frequent and long drought episodes of the 1980s, a plethora of case studies have shown that West Africa remains a hot spot in the continent where despite its numerous water resources, extreme rainfall variability remains a profound challenge to the availability of freshwater for agriculture and ecosystem services. In this paper, we assess the recent flux in water availability over West Africa by investigating variations in net‐precipitation (i.e. the maximum available freshwater flux) using wavelet analysis. Net‐precipitation was obtained as a residual of the atmospheric water balance, and its variability compared to precipitation, temperature, evaporation, soil moisture and normalized difference vegetation index using wavelet power transforms and coherence analysis. Results from the study indicate that the variance in water flux over the region has been progressively reducing, suggesting a relative reduction in extreme hydrological conditions. Also, the wavelet coherence analysis revealed that the observed decreasing rate of available freshwater is highly coupled to a low frequency modulating El‐Niño activity that induced lower changes in rainfall variance, as well as higher evaporation variance. Spatial trends in the annual‐scaled average wavelet power indicated that the south‐western parts of the region experienced the most reduction in rainfall flux. The highest deficit in net‐precipitation flux was found in the dry sub‐humid climatic zone, which is drained by major regional rivers, including the Niger and Volta. Considering the long‐term variability in freshwater (i.e. from 1979 to 2010), we found the 1980s to be the driest decade and the 1990s being its recovery period, while the 2000s proved to be a considerably dry decade, suggesting a strong multi‐decadal variability.
Strontium accumulation in whole grain of Aegilops and Triticum species
Authors: Kastori Rudolf , Maksimović Ivana , Denčić Srbislav , Kádár Imre , Putnik-Delić Marina , Momčilović Vojislava 
Published: February 2017

AbstractPlant species differ in their ability to accumulate mineral elements. Differences also exist among genotypes, lines, and varieties within species. Strontium (Sr) enters the food chain primarily via plants, and wheat products are amongst the most important pathways by which Sr enters the human body. The aim of this study was to analyze the accumulation of Sr in whole grain of various Aegilops and Triticum species with different genomes (AA, BB, BBAA, BBAADD, and DD). During three experimental years plants were grown in temperate continental climate on a calcareous, gleyic chernozem soil. The results reveal that the studied species and genomes differed significantly in Sr accumulation in the grains. The average Sr concentration of the grains ranged, depending on the year of study and genotype, from 0.70 to 3.89 mg kg−1 DM. The grain of wild diploid Aegilops speltoides with BB genome contained significantly more Sr than all of the other analyzed genotypes. Grains of wild and cultivated tetraploid wheat genotypes had the lowest Sr concentration. The modern cultivated hexaploid wheat varieties displayed substantial variation in Sr concentration in the grains. The examined genotypes also differed significantly with respect to their mass of 1000 grains, which was the smallest in Aegilops speltoides. There was a significantly negative correlation between the average mass of a 1000 grains and concentration of Sr. The results show that even when the background concentration of Sr was relatively low, wheat genotypes accumulated it in the grains, although to a different extent. Therefore, selection of wheat genotypes which accumulate less Sr in the grain could contribute to improve food quality.
Clinical outcome of using gastric remnant or jejunum or colon conduit in surgery for esophageal carcinoma with previous gastrectomy
Authors: Jun Wang , Wei Wen , Weibing Wu , Jing Xu , Fuxi Zhen , Xiaoxiang Xi , Bihong Lu , Tong Zhou , Liang Chen , Jinhua Luo 
Published: February 2017

BackgroundFor esophageal carcinoma patients with early gastrectomy, individualized surgical plans—including selection of replacement conduit and operation route based on patient's new lesion and surgical history—can achieve the desired therapeutic effect and improve postoperative life quality. We investigated the outcomes at our institution.MethodsThe clinical data of 42 esophageal carcinoma patients with early gastrectomy were analyzed retrospectively.ResultsEsophagectomy was performed combining replacement with remnant stomach in 16 patients, jejunum in 17, and colon in 9. Esophagectomy combining replacement with gastric remnant got advantages of shorter operation time and less bleeding over that of replacement with jejunum or colon. Gastric remnant group scored higher on the QLQ‐C30 questionnaire than jejunum or colon group with respect to overall quality of life, physical function, and social relationships. In QLQ‐OES18 questionnaire, the scores of appetite recovery and reflux mitigation were more favorable in remnant stomach group than those in jejunum or colon group. Survival analysis showed no significant difference in survival rate among the patients undergoing replacement with gastric remnant, jejunum, or colon.ConclusionsFor esophageal carcinoma patients with early gastrectomy, esophagus‐gastric remnant anastomosis possesses advantages of shorter operation time, less surgical trauma, and greater life quality after surgery.