bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of Body‐Centered Cubic Gold Nanocluster
Authors: Liu Chao , Li Tao , Li Gao , Nobusada Katsuyuki , Zeng Chenjie , Pang Guangsheng , Rosi Nathaniel L. , Jin Rongchao 
Published: July 2015

AbstractThe structure of nanoparticles plays a critical role in dictating their material properties. Gold is well known to adopt face‐centered cubic (fcc) structure. Herein we report the first observation of a body‐centered cubic (bcc) gold nanocluster composed of 38 gold atoms protected by 20 adamantanethiolate ligands and two sulfido atoms ([Au38S2(SR)20], where R=C10H15) as revealed by single‐crystal X‐ray crystallography. This bcc structure is in striking contrast with the fcc structure of bulk gold and conventional Au nanoparticles, as well as the bi‐icosahedral structure of [Au38(SCH2CH2Ph)24]. The bcc nanocluster has a distinct HOMO–LUMO gap of ca. 1.5 eV, much larger than the gap (0.9 eV) of the bi‐icosahedral [Au38(SCH2CH2Ph)24]. The unique structure of the bcc gold nanocluster may be promising in catalytic applications.
Formkontrollierte Synthese und Selbstsortierung kovalent‐organischer Käfigverbindungen
Authors: Klotzbach Stefanie , Beuerle Florian 
Published: July 2015

AbstractDas Konzept der direktionalen Bindungen ist ein leistungsstarkes Hilfsmittel zur präzisen Kontrolle von Form und Stöchiometrie für dreidimensionale Objekte, die aus starren Baueinheiten unter dynamisch‐kovalenten Bedingungen aufgebaut werden. Cokondensationen von Catechol‐funktionalisierten Tribenzotriquinacen‐Derivaten mit einem jeweiligen Winkel von 90° zwischen den reaktiven Positionen und Diboronsäuren mit Bisswinkeln von jeweils 60°, 120° und 180° führten zu einer effizienten und vorhersagbaren Bildung von bipyramidalen, tetraedrischen und kubischen kovalent‐organischen Käfigverbindungen. Untersuchungen zur Selbstsortierung von ternären Mischungen, die jeweils zwei konkurrierende Boronsäuren enthielten, zeigten in Abhängigkeit von der relativen Stabilität der getrennten Käfige im Vergleich mit möglichen Drei‐Komponenten‐Systemen entweder narzisstisches oder soziales Verhalten.
NiSe Nanowire Film Supported on Nickel Foam: An Efficient and Stable 3D Bifunctional Electrode for Full Water Splitting
Authors: Tang Chun , Cheng Ningyan , Pu Zonghua , Xing Wei , Sun Xuping 
Published: July 2015

AbstractActive and stable electrocatalysts made from earth‐abundant elements are key to water splitting for hydrogen production through electrolysis. The growth of NiSe nanowire film on nickel foam (NiSe/NF) in situ by hydrothermal treatment of NF using NaHSe as Se source is presented. When used as a 3D oxygen evolution electrode, the NiSe/NF exhibits high activity with an overpotential of 270 mV required to achieve 20 mA cm−2 and strong durability in 1.0 M KOH, and the NiOOH species formed at the NiSe surface serves as the actual catalytic site. The system is also highly efficient for catalyzing the hydrogen evolution reaction in basic media. This bifunctional electrode enables a high‐performance alkaline water electrolyzer with 10 mA cm−2 at a cell voltage of 1.63 V.
Biomineralization of a Cadmium Chloride Nanocrystal by a Designed Symmetrical Protein
Authors: Voet Arnout R. D. , Noguchi Hiroki , Addy Christine , Zhang Kam Y. J. , Tame Jeremy R. H. 
Published: July 2015

AbstractWe have engineered a metal‐binding site into the novel artificial β‐propeller protein Pizza. This new Pizza variant carries two nearly identical domains per polypeptide chain, and forms a trimer with three‐fold symmetry. The designed single metal ion binding site lies on the symmetry axis, bonding the trimer together. Two copies of the trimer associate in the presence of cadmium chloride in solution, and very high‐resolution X‐ray crystallographic analysis reveals a nanocrystal of cadmium chloride, sandwiched between two trimers of the protein. This nanocrystal, containing seven cadmium ions lying in a plane and twelve interspersed chloride ions, is the smallest reported to date. Our results indicate the feasibility of using rationally designed symmetrical proteins to biomineralize nanocrystals with useful properties.
Deutlich unterschiedliche Mechanismen der Wasserstoffatomabstraktion aus Methan und Wasser durch den heteronuklearen Oxidcluster [Ga2MgO4].+
Authors: Li Jilai , Wu Xiao‐Nan , Zhou Shaodong , Tang Shiya , Schlangen Maria , Schwarz Helmut 
Published: July 2015

AbstractDie thermischen Reaktionen des heteronuklearen Oxidclusters [Ga2MgO4].+ mit Methan und Wasser wurden mit modernsten Gasphasenexperimenten und quantenchemischen Rechnungen untersucht. Im Gegensatz zur H‐Abstraktion aus Methan folgt die Aktivierung von Wasser einem protonengekoppelten Elektronentransfermechanismus (proton‐coupled electron transfer, PCET); ihm ist die deutlich höhere Reaktivität gegenüber der starken O‐H‐Bindung geschuldet. Die Erkenntnisse dieser Studie vertiefen das mechanistische Verständnis, wie inerte R‐H‐Bindungen durch Metalloxide gespalten werden können.
Inhibiting an Epoxide Hydrolase Virulence Factor from Pseudomonas aeruginosa Protects CFTR
Authors: Bahl Christopher D. , Hvorecny Kelli L. , Bomberger Jennifer M. , Stanton Bruce A. , Hammock Bruce D. , Morisseau Christophe , Madden Dean R. 
Published: July 2015

AbstractOpportunistic pathogens exploit diverse strategies to sabotage host defenses. Pseudomonas aeruginosa secretes the CFTR inhibitory factor Cif and thus triggers loss of CFTR, an ion channel required for airway mucociliary defense. However, the mechanism of action of Cif has remained unclear. It catalyzes epoxide hydrolysis, but there is no known role for natural epoxides in CFTR regulation. It was demonstrated that the hydrolase activity of Cif is strictly required for its effects on CFTR. A small‐molecule inhibitor that protects this key component of the mucociliary defense system was also uncovered. These results provide a basis for targeting the distinctive virulence chemistry of Cif and suggest an unanticipated role of physiological epoxides in intracellular protein trafficking.
Enhanced Hydrogen Production from DNA‐Assembled Z‐Scheme TiO2–CdS Photocatalyst Systems
Authors: Ma Ke , Yehezkeli Omer , Domaille Dylan W. , Funke Hans H. , Cha Jennifer N. 
Published: July 2015

AbstractA wide range of inorganic nanostructures have been used as photocatalysts for generating H2. To increase activity, Z‐scheme photocatalytic systems have been implemented that use multiple types of photoactive materials and electron mediators. Optimal catalysis has previously been obtained by interfacing different materials through aggregation or epitaxial nucleation, all of which lowers the accessible active surface area. DNA has now been used as a structure‐directing agent to organize TiO2 and CdS nanocrystals. A significant increase in H2 production compared to CdS or TiO2 alone was thus observed directly in solution with no sacrificial donors or applied bias. The inclusion of benzoquinone (BQ) equidistant between the TiO2 and CdS through DNA assembly further increased H2 production. While the use of a second quinone in conjunction with BQ showed no more improvement, its location within the Z‐scheme was found to strongly influence catalysis.
A pH‐Responsive Carrier System that Generates NO Bubbles to Trigger Drug Release and Reverse P‐Glycoprotein‐Mediated Multidrug Resistance
Authors: Chung Ming‐Fan , Liu Hung‐Yi , Lin Kun‐Ju , Chia Wei‐Tso , Sung Hsing‐Wen 
Published: July 2015

AbstractMultidrug resistance (MDR) resulting from the overexpression of drug transporters such as P‐glycoprotein (Pgp) increases the efflux of drugs and thereby limits the effectiveness of chemotherapy. To address this issue, this work develops an injectable hollow microsphere (HM) system that carries the anticancer agent irinotecan (CPT‐11) and a NO‐releasing donor (NONOate). Upon injection of this system into acidic tumor tissue, environmental protons infiltrate the shell of the HMs and react with their encapsulated NONOate to form NO bubbles that trigger localized drug release and serve as a Pgp‐mediated MDR reversal agent. The site‐specific drug release and the NO‐reduced Pgp‐mediated transport can cause the intracellular accumulation of the drug at a concentration that exceeds the cell‐killing threshold, eventually inducing its antitumor activity. These results reveal that this pH‐responsive HM carrier system provides a potentially effective method for treating cancers that develop MDR.
Catalytic Ring Expansion of Cyclic Hemiaminals for the Synthesis of Medium‐Ring Lactams
Authors: Zhao Wanxiang , Qian Hui , Li Zigang , Sun Jianwei 
Published: July 2015

AbstractA mild and efficient intermolecular ring‐expansion approach was developed for the synthesis of medium‐ring lactams by using siloxy alkynes. Key to success is the suitable combination of a superior catalyst and an exceptional nitrogen‐protecting group. Control experiments indicated that the reaction is remarkably selective toward the desired lactam formation, even with many possible non‐productive pathways.
α‐Peptide–Oligourea Chimeras: Stabilization of Short α‐Helices by Non‐Peptide Helical Foldamers
Authors: Fremaux Juliette , Mauran Laura , Pulka‐Ziach Karolina , Kauffmann Brice , Odaert Benoit , Guichard Gilles 
Published: July 2015

AbstractShort α‐peptides with less than 10 residues generally display a low propensity to nucleate stable helical conformations. While various strategies to stabilize peptide helices have been previously reported, the ability of non‐peptide helical foldamers to stabilize α‐helices when fused to short α‐peptide segments has not been investigated. Towards this end, structural investigations into a series of chimeric oligomers obtained by joining aliphatic oligoureas to the C‐ or N‐termini of α‐peptides are described. All chimeras were found to be fully helical, with as few as 2 (or 3) urea units sufficient to propagate an α‐helical conformation in the fused peptide segment. The remarkable compatibility of α‐peptides with oligoureas described here, along with the simplicity of the approach, highlights the potential of interfacing natural and non‐peptide backbones as a means to further control the behavior of α‐peptides.
Switching and Conformational Fixation of Amides Through Proximate Positive Charges
Authors: Bartuschat Amelie L. , Wicht Karina , Heinrich Markus R. 
Published: July 2015

AbstractTertiary amides, which usually occur as cis/trans mixtures, can be effectively shifted to the cis conformation by placing a positive charge in close proximity to the amide carbonyl. This effect was used to prepare cis‐configured prolyl amides and to facilitate a strongly rotamer‐dependent radical cyclization.
Direct Observation of the Reversible Two‐State Unfolding and Refolding of an α/β Protein by Single‐Molecule Atomic Force Microscopy
Authors: He Chengzhi , Hu Chunguang , Hu Xiaodong , Hu Xiaotang , Xiao Adam , Perkins Thomas T. , Li Hongbin 
Published: July 2015

AbstractDirectly observing protein folding in real time using atomic force microscopy (AFM) is challenging. Here the use of AFM to directly monitor the folding of an α/β protein, NuG2, by using low‐drift AFM cantilevers is demonstrated. At slow pulling speeds (<50 nm s−1), the refolding of NuG2 can be clearly observed. Lowering the pulling speed reduces the difference between the unfolding and refolding forces, bringing the non‐equilibrium unfolding–refolding reactions towards equilibrium. At very low pulling speeds (ca. 2 nm s−1), unfolding and refolding were observed to occur in near equilibrium. Based on the Crooks fluctuation theorem, we then measured the equilibrium free energy change between folded and unfolded states of NuG2. The improved long‐term stability of AFM achieved using gold‐free cantilevers allows folding–unfolding reactions of α/β proteins to be directly monitored near equilibrium, opening the avenue towards probing the folding reactions of other mechanically important α/β and all‐β elastomeric proteins.
Shape‐Controlled Synthesis and Self‐Sorting of Covalent Organic Cage Compounds
Authors: Klotzbach Stefanie , Beuerle Florian 
Published: July 2015

AbstractThe directional bonding approach is a powerful tool to rationally control both shape and stoichiometry of three‐dimensional objects built from rigid building blocks under dynamic covalent conditions. Co‐condensation of catechol‐functionalized tribenzotriquinacene derivatives which have 90° angles between the reactive sites and diboronic acids with bite angles of 60°, 120°, and 180°, led to the efficient formation of, respectively, bipyramidal, tetrahedral, or cubic covalent organic cage compounds in a predictable manner. Investigations on the self‐sorting of ternary mixtures containing two competitive boronic acids revealed either narcissistic or social self‐sorting depending on the stability of the segregated cages relative to feasible three‐component assemblies.
Host–Guest Complexation of Perethylated Pillar[5]arene with Alkanes in the Crystal State
Authors: Ogoshi Tomoki , Sueto Ryuta , Yoshikoshi Kumiko , Sakata Yoko , Akine Shigehisa , Yamagishi Tada‐aki 
Published: July 2015

AbstractActivated perethylated pillar[5]arene crystals show an unexpected alkane‐shape‐ and ‐length‐selective gate‐opening behavior. Activated crystals were obtained upon removing solvents from perethylated pillar[5]arene crystals by heating. The activated crystals could quantitatively take up n‐alkanes with carbon chains containing more than five carbon atoms as a consequence of their gate‐opening pressure. As the chain length of the n‐alkanes increased, the gate pressure decreased. A transformation into a herringbone structure was induced when n‐hexane was used as a guest. By contrast, cyclic and branched alkanes were not taken up and could not induce a crystal transformation because they were too large to fit in the cavities of the pillar[5]arene. Alkane‐shape‐selective molecular recognition of pillar[5]arenes in the solution state was translated into the vapor/crystal state.
Distinct Mechanistic Differences in the Hydrogen‐Atom Transfer from Methane and Water by the Heteronuclear Oxide Cluster [Ga2MgO4].+
Authors: Li Jilai , Wu Xiao‐Nan , Zhou Shaodong , Tang Shiya , Schlangen Maria , Schwarz Helmut 
Published: July 2015

AbstractThe thermal reactions of the heteronuclear oxide cluster [Ga2MgO4].+ with methane and water have been studied using state‐of‐the‐art gas‐phase experiments in conjunction with quantum‐chemical calculations. The significant reactivity differences, favoring activation of the strong OH bond, can be ascribed to a proton‐coupled electron transfer (PCET) mechanism operative in the activation of water. This study deepens our mechanistic understanding on how inert RH bonds are cleaved by metal oxides.
N‐Heterocyclic Olefins as Organocatalysts for Polymerization: Preparation of Well‐Defined Poly(propylene oxide)
Authors: Naumann Stefan , Thomas Anthony W. , Dove Andrew P. 
Published: July 2015

AbstractThe metal‐free polymerization of propylene oxide (PO) using a special class of alkene—N‐heterocyclic olefins (NHOs)—as catalysts is described. Manipulation of the chemical structure of the NHO organocatalyst allows for the preparation of the poly(propylene oxide) in high yields with high turnover (TON>2000), which renders this the most active metal‐free system for the polymerization of PO reported to date. The resulting polyether displays predictable end groups, molar mass, and a low dispersity (ĐM<1.09). NHOs with an unsaturated backbone are essential for polymerization to occur, while substitution at the exocyclic carbon atom has an impact on the reaction pathway and ensures the suppression of side reactions.
Cationic Iridium/S‐Me‐BIPAM‐Catalyzed Direct Asymmetric Intermolecular Hydroarylation of Bicycloalkenes
Authors: Shirai Tomohiko , Yamamoto Yasunori 
Published: July 2015

AbstractHighly enantioselective cationic iridium‐catalyzed hydroarylation of bicycloalkenes, by carbonyl‐directed CH bond cleavage, was accomplished using a newly synthesized sulfur‐linked bis(phosphoramidite) ligand (S‐Me‐BIPAM). The reaction provides alkylated acetophenone or benzamide derivatives in moderate to excellent yields and good to excellent enantioselectivities. Notably, the hydroarylation reaction of 2‐norbornene with N,N‐dialkylbenzamide proceeds with excellent enantioselectivity (up to 99 % ee) and high selectivity for the mono‐ortho‐alkylation product.
Regulation of the NADH pool and NADH/NADPH ratio redistributes acetoin and 2,3‐butanediol proportion in Bacillus subtilis
Authors: Bao Teng , Zhang Xian , Zhao Xiaojing , Rao Zhiming , Yang Taowei , Yang Shangtian 
Published: July 2015

AbstractBacillus subtilis produces acetoin as a major product along with several NADH‐dependent byproducts, especially 2,3‐butanediol. In this study, the down‐regulation of the NADH pool and the redistribution of NADH/NADPH were targeted using external and genetic processes, as a means by which to redistribute the metabolic flux in favor of acetoin synthesis. First, it was found that the use of carbon sources of different oxidation states resulted in very different intracellular NADH/NAD+ ratios that dictated the total process yield of acetoin. A mixture of glucose and gluconate as substrate produced a relatively low NADH/NAD+ ratio, and resulted in an increase in acetoin production while byproducts significantly decreased. Metabolic engineering methods using glucose as a substrate could yield a similar effect. Acetoin production was significantly enhanced by overexpression of the oxidative pentose phosphate pathway: increased expression of glucose‐6‐phosphate dehydrogenase resulted in a decrease in the intracellular NADH/NADPH ratio (1.9‐fold) and NADH/NAD+ ratio (1.7‐fold). In fed‐batch culture the engineered strain yielded an acetoin concentration of 43.3 g L–1, while the production of 2,3‐butanediol was only 1.7 g L–1. The concept of the manipulation of cofactor levels to redistribute carbon flux by external and genetic means as explored in this paper provides a novel strategy for improving industrial acetoin fermentation.
Five-year results of a randomized clinical trial of conventional surgery, endovenous laser ablation and ultrasound-guided foam sclerotherapy in patients with great saphenous varicose veins
Authors: van der Velden S K , Biemans A A M , De Maeseneer M G R , Kockaert M A , Cuypers P W , Hollestein L M , Neumann H A M , Nijsten T , van den Bos R R 
Published: July 2015

Abstract

Background
A variety of techniques exist for the treatment of patients with great saphenous vein (GSV) varicosities. Few data exist on the long-term outcomes of these interventions.

Methods
Patients undergoing conventional surgery, endovenous laser ablation (EVLA) and ultrasound-guided foam sclerotherapy (UGFS) for GSV varicose veins were followed up for 5 years. Primary outcome was obliteration or absence of the treated GSV segment; secondary outcomes were absence of GSV reflux, and change in Chronic Venous Insufficiency quality-of-life Questionnaire (CIVIQ) and EuroQol – 5D (EQ-5D™) scores.

Results
A total of 224 legs were included (69 conventional surgery, 78 EVLA, 77 UGFS), 193 (86·2 per cent) of which were evaluated at final follow-up. At 5 years, Kaplan–Meier estimates of obliteration or absence of the GSV were 85 (95 per cent c.i. 75 to 92), 77 (66 to 86) and 23 (14 to 33) per cent in the conventional surgery, EVLA and UGFS groups respectively. Absence of above-knee GSV reflux was found in 85 (73 to 92), 82 (72 to 90) and 41 (30 to 53) per cent respectively. CIVIQ scores deteriorated over time in patients in the UGFS group (0·98 increase per year, 95 per cent c.i. 0·16 to 1·79), and were significantly worse than those in the EVLA group (−0·44 decrease per year, 95 per cent c.i. −1·22 to 0·35) (P = 0·013). CIVIQ scores for the conventional surgery group did not differ from those in the EVLA and UGFS groups (0·44 increase per year, 95 per cent c.i. −0·41 to 1·29). EQ-5D™ scores improved equally in all groups.

Conclusion
EVLA and conventional surgery were more effective than UGFS in obliterating the GSV 5 years after intervention. UGFS was associated with substantial rates of GSV reflux and inferior CIVIQ scores compared with EVLA and conventional surgery. Registration number: NCT00529672 (http://www.clinicaltrials.gov).
SapWin 4.0–a new simulation program for electrical engineering education using symbolic analysis
Authors: Grasso F. , Luchetta A. , Manetti S. , Piccirilli M. C. , Reatti A. 
Published: July 2015

ABSTRACTThe paper presents the main capabilities and the possible applications in the teaching area of Electrical/Electronic Engineering of a software system developed by the authors and aimed at simulating analog linear (or linearized) circuits. The work is the enrichment, enhancement and extension of some programs developed by the same authors along the last two decades and distributed in many schools, institutions, industries, and research centers for different purposes. The feedback (in terms of suggestions, corrections, and improvement requests) has been collected to generate a completely renewed software that could definitely become a really efficient tool in the field of analog circuits, also filling the gap which still exists in the use of very famous and classical circuit simulators (as, for instance, the SPICE family). The application of the past experience involves several courses, as it will be described in the final sections of paper. © 2015 Wiley Periodicals, Inc. Comput. Appl. Eng. Educ. 24:44–57, 2016; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21671
Optimal management of cervical cancer in HIV‐positive patients: a systematic review
Authors: Ntekim Atara , Campbell Oladapo , Rothenbacher Dietrich 
Published: July 2015

AbstractThe clinical management of cervical cancer in HIV‐positive patients has challenges mainly due to the concerns on immune status. At present, their mode of management is similar to HIV‐seronegative patients involving the use of chemotherapy and radiotherapy concurrently as indicated. HIV infection, cancer, radiotherapy, and chemotherapy lower immunity through reduction in CD4 cell counts. At present there are no treatment guidelines for HIV‐positive patients. This study was done to systematically review the literature on cervical cancer management in HIV‐positive patients and treatment outcomes. A systematic literature search was done in the major databases to identify studies on the management of HIV‐positive patients with cervical cancer. Identified studies were assessed for eligibility and inclusion in the review following the guidelines of The Cochrane Handbook for Systematic Reviews and CRD's (Centre for Reviews and Dissemination) guidance for undertaking reviews in health care. Eight eligible studies were identified from the literature. Three of them were prospective while five were retrospective studies. Notably, the average age at diagnosis of cervical cancer in HIV‐positive patients was a decade lower than in seronegative patients. There was no difference in distribution of stages of disease at presentation between HIV‐positive and negative patients. Mild acute toxicity (Grades 1 and 2) was higher in HIV‐positive patients than in HIV‐negative patients in hematopoietic system. In the grades 3 and 4 reactions, anemia was reported in 4% versus 2% while gastrointestinal reactions were reported in 5% versus 2% respectively. In general, patients who were started early on HAART had higher rates of treatment completion. The study supports the suggestion that HAART should be commenced early at cervical cancer diagnosis in HIV‐positive patients diagnosed with cervical cancer to ensure less toxicity and better treatment compliance.