bluuebunny/crossref_metadata_2025_split huggingface dataset:
A 3D Hybrid Praseodymium–Antimony–Oxochloride Compound: Single‐Crystal‐to‐Single‐Crystal Transformation and Photocatalytic Properties
Authors: Zou Guo‐Dong , Zhang Gui‐Gang , Hu Bing , Li Jian‐Rong , Feng Mei‐Ling , Wang Xin‐Chen , Huang Xiao‐Ying 
Published: October 2013

AbstractA 3D organic–inorganic hybrid compound, (2‐MepyH)3 [{Fe(1,10‐phen)3}3][{Pr4Sb12O18(OH) Cl11.5}(TDC)4.5({Pr4Sb12O18(OH)Cl9.5} Cl)]⋅3 (2‐Mepy)⋅28 H2O (1; 2‐Mepy=2‐methylpyridine, 1,10‐phen=1,10‐phenanthroline, H2TDC=thiophene‐2,5‐dicarboxylic acid), was hydrothermally synthesized and structurally characterized. Unusually, two kinds of high‐nuclearity clusters, namely [(Pr4Sb12O18 (OH)Cl11)(COO)5]5− and [(Pr4Sb12O18 (OH)Cl9)Cl(COO)5]4−, coexist in the structure of compound 1; two of the latter clusters are doubly bridged by two μ2‐Cl− moieties to form a new centrosymmetric dimeric cluster. An unprecedented spontaneous and reversible single‐crystal‐to‐single‐crystal transformation was observed, which simultaneously involved a notable organic‐ligand movement between the metal ions and an alteration of the bridging ion in the dimeric cluster, induced by guest‐release/re‐adsorption, thereby giving rise to the interconversion between compound 1 and the compound (2‐MepyH)3[{Fe(1,10‐phen)3}3][{Pr4Sb12O18(OH)Cl11.5}(TDC)4({Pr4Sb12O18Cl10.5(TDC)0.5(H2O)1.5}O0.5)]⋅ 25 H2O (1′). The mechanism of this transformation has also been discussed in great detail. Photocatalytic H2‐evolution activity was observed for compound 1′ under UV light with Pt as a co‐catalyst and MeOH as a sacrificial electron donor.
Synthesis of Catechol‐, Pinacol‐, and Neopentylglycolborane through the Heterogeneous Catalytic BB Hydrogenolysis of Diboranes(4)
Authors: Braunschweig Holger , Guethlein Frank , Mailänder Lisa , Marder Todd B. 
Published: October 2013

AbstractA new synthetic approach to hydroboranes catechol‐, pinacol‐, and neopentylglycolborane has been developed. Starting from diboranes(4) B2cat2, B2pin2, or B2neop2, the respective boranes were obtained by heterogeneously catalyzed cleavage of the BB bond in the respective diboranes with hydrogen. Group 10 metals were found to be effective catalysts for this reaction.
Asymmetric Conjugate Addition of Malonate Esters to α,β‐Unsaturated N‐Sulfonyl Imines: An Expeditious Route to Chiral δ‐Aminoesters and Piperidones
Authors: Espinosa Miguel , Blay Gonzalo , Cardona Luz , Pedro José R. 
Published: October 2013

AbstractThe asymmetric conjugate addition of malonate esters to α,β‐unsaturated N‐sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 Å MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ‐aminoesters and piperidones.
ChemInform Abstract: A New Prenylated Stilbene Derivative from the Roots of Cudrania tricuspidata
Authors: Shan Wei‐Guang , Shi Ling‐Ling , Ying You‐Min , Hou Xiao‐Rong , Zhan Zha‐Jun 
Published: October 2013

Abstractisolation, structure and cytotoxicity of the new prenylated stilbene, cudrastilbene (I), along with five known compounds
Incidence and prognostic impact of KRAS and BRAF mutation in patients undergoing liver surgery for colorectal metastases
Authors: Karagkounis Georgios , Torbenson Michael S. , Daniel Hubert D. , Azad Nilofer S. , Diaz Luis A. , Donehower Ross C. , Hirose Kenzo , Ahuja Nita , Pawlik Timothy M. , Choti Michael A. 
Published: October 2013

BACKGROUNDMolecular biomarkers offer the potential for refining prognostic determinants in patients undergoing cancer surgery. Among patients with colorectal cancer, KRAS and BRAF are important biomarkers, but their role in patients undergoing surgical therapy for liver metastases is unknown. In this study, the incidence and prognostic significance of KRAS and BRAF mutations were determined in patients undergoing surgical therapy of colorectal liver metastases (CRLM).METHODSKRAS and BRAF analysis was performed on 202 patients undergoing surgery for CRLM between 2003 and 2008. Tumor samples were analyzed for somatic mutations using sequencing analysis (KRAS, codon12/13, BRAF, V600E). The frequency of mutations was ascertained, and their impact on outcome was determined relative to other clinicopathologic factors.RESULTSKRAS gene mutations were detected in 58/202 patients (29%). In contrast, mutation in the BRAF gene was identified in very low frequency in this surgical cohort, found in only 4/202 (2%) patients. On multivariate analysis, KRAS mutation was associated with worse survival (hazard ratio [HR], 1.99; 95% confidence interval [CI], 1.21‐3.26), as well as recurrence risk (HR, 1.68; 95% CI, 1.04‐2.70). Although other clinicopathologic features, including tumor number, carcinoembryonic antigen, and primary stage were also associated with survival, KRAS status remained independently predictive of outcome. The low incidence of BRAF mutation limited assessment of its prognostic impact.CONCLUSIONWhereas KRAS mutations were found in approximately one third of patients, BFAF mutations were found in only 2% of patients undergoing surgery for CRLM. KRAS status was an independent predictor of overall and recurrence‐free survival. Molecular biomarkers such as KRAS may help to refine our prognostic assessment of patients undergoing surgical therapy for CRLM. Cancer 2013;119:4137–4144. ©2013 American Cancer Society.
Composite Polymer Electrolytes for Fuel Cell Applications: Filler‐Induced Effect on Water Sorption and Transport Properties
Authors: Mecheri Barbara , Felice Valeria , D'Epifanio Alessandra , Tavares Ana C. , Licoccia Silvia 
Published: October 2013

AbstractNafion‐ and sulfonated polysulfone (SPS)‐ based composite membranes were prepared by incorporation of SnO2 nanoparticles in a wide range of loading (0${ \div }$35 wt. %). The composites were investigated by differential scanning calorimetry, dynamic vapor sorption and electrochemical impedance spectroscopy to study the filler effect on water sorption, water mobility, and proton conductivity. A detrimental effect of the filler was observed on water mobility and proton conductivity of Nafion‐based membranes. An increase in water mobility and proton conductivity was instead observed in SPS‐based samples, particularly at low hydration degree. Analysis of the water sorption isotherms and states of water revealed that the presence of SnO2 in SPS enhances interconnectivity of hydrophilic domains, while not affecting the Nafion microstructure. These results enable the design of suitable electrolyte materials that operate in proton exchange membrane fuel cell conditions.
Enhanced Visible‐Light Hydrogen‐Production Activity of Copper‐Modified ZnxCd1−xS
Authors: Zhang Jun , Xu Quanlong , Qiao Shi Zhang , Yu Jiaguo 
Published: October 2013

AbstractCopper modification is an efficient way to enhance the photocatalytic activity of ZnS‐based materials; however, the mechanisms of Cu2+ surface and bulk modifications for improving the activity are quite different. In this work, two different synthetic pathways were devised to prepare surface and bulk Cu2+‐modified ZnxCd1−xS photocatalysts through cation‐exchange and coprecipitation methods, respectively. Different Cu2+ modifications brought different effects on the phase structure, morphology, surface area, optical property, as well as the photocatalytic H2‐production activity of the final products. The optimized Cu2+‐surface‐modified ZnxCd1−xS photocatalyst has a high H2‐production rate of 4638.5 μmol h−1 g−1 and an apparent quantum efficiency of 20.9 % at 420 nm, exceeding that of Cu2+‐bulk‐modified catalyst at the same copper content. Cu2+ surface modification not only brings a new electron‐transferring pathway (interfacial charge transfer), but also produces new surface active sites for H2 evolution, reducing the recombination rate of photogenerated charge carriers.
Determination of N and O – Atom and N2(A) Metastable Molecule Densities in the Afterglows of N2 and N2‐O2 Microwave Discharges
Authors: Zerrouki H. , Ricard A. , Sarrette J. P. 
Published: October 2013

AbstractEarly afterglows of N2 and N2‐O2 flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atom and N2(A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N‐atoms and measurements of NO and N2 band intensities for O‐atoms and N2(A) metastable molecules. By using N2 tanks with 50 and 10 ppm impurity, it is determined in the afterglow an O‐ atom impurity of 150‐200 ppm. Variations of the N and O‐atom and N2(A) metastable molecule densities are obtained in the early afterglow of N2–(9·10–5–3·10–3)O2 gas mixtures. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Role of the Field Emission Effect in the Breakdown Mechanism of Direct‐Current Helium Discharges in Micrometer Gaps
Authors: Matejčik Š. , Klas M. , Radjenović B. , Durian M. , Savić M. , Radmilović‐Radjenović M. 
Published: October 2013

AbstractThis paper contains results of experimental studies of the direct current breakdown voltage curves and volt‐ampere characteristics of discharges generated in a system consisting of two plane‐parallel tungsten and molybdenum electrodes at separations from 100 µ m to 1 µ m. The measurements were performed in the pressure range from 22.5 Torr to 738 Torr. The results are presented in the form of Paschen curves. Based on the measured breakdown voltage curves, the effective yields have been estimated in the case of different cathode materials. Differences between them are attributed to the influence of the work function of the cathode material on the current‐voltage characteristics due to field emission effect in small gaps and high pressures. At low‐pressures, however, vaporation of impurities from the electrodes material becomes significant. The present paper delivers new data on DC breakdown under these experimental conditions and conditions on the validity of the Paschen law in helium and provides better insight into the role of the field emission and the electrode materials on the breakdown voltage. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improving energy efficiency of incremental relay based cooperative communications in wireless body area networks
Authors: Deepak K.S. , Babu A.V. 
Published: October 2013

SUMMARYIn this paper, we investigate the energy efficiency of an incremental relay based cooperative communication scheme in wireless body area networks (WBANs). We derive analytical expressions for the energy efficiency of direct and cooperative communication schemes taking into account the effect of packet error rate. The following communication scenarios specific to a WBAN are considered: (i) in‐body communication between an implant sensor node and the gateway, and (ii) on‐body communication between a body surface node and the gateway with line‐of‐sight (LOS) and non‐LOS channels. The results reveal a threshold behavior that separates regions where direct transmission is better from regions where incremental relay cooperation is more useful in terms of energy efficiency. It is observed that, compared with direct communication, incremental relay based cooperative communication schemes improves the energy efficiency significantly. Further, cooperation extends the source‐to‐destination hop length over, which energy efficient communication can be achieved as compared with direct communication. We also observe that, for both direct as well as cooperative transmission schemes in error prone channels, an optimal packet size exists that result in maximum energy efficiency. Copyright © 2013 John Wiley & Sons, Ltd.
Achievable rate region with secrecy constraints for secure communication in two‐way relay networks
Authors: Yang Yunchuan , Wang Wenbo , Zhao Hui 
Published: October 2013

SUMMARYIn this paper, we consider a two‐way relay network consisted of two sources and multiple relays in the presence of an eavesdropper, where the cooperative beamforming strategy is applied to exploit the cooperative diversity to support the secure communication as illustrated in Figure 1. Naturally, we are interested in the beamforming strategy and power allocation to maximize the achievable sum secrecy rate. However, the corresponding problem is equivalent to solve a product of three correlated generalized Rayleigh quotients problem and difficult to solve in general. Because of the openness of wireless medium, the information rate leakage to the eavesdropper cannot be canceled perfectly. To some extent, ‘almost perfect secrecy’, where the rate leakage to the eavesdropper is limited, is more interesting from the practical point of view. In this case, we concern ourself mainly the achievable rate region for general case where the rate at the eavesdropper is regarded as the measurement of secrecy level. Two beamforming approaches, optimal beamforming and null space beamforming, are applied to investigate the achievable rate region with total power constraint and the rate constraint at the eavesdropper, which can be obtained by solving a sequence of the weighted sum inverse‐signal‐to‐noise‐ratio minimization (WSISM) problem. Because of the non‐convexity of WSISM problem, an alternating iteration algorithm is proposed to optimize the relay beamforming vector and two sources' transmit power, where two subproblems need to be solved in each iteration. Meanwhile, we provide the convergence analysis of proposed algorithm. Through the numerical simulations, we verify the effectiveness of proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd.
Asynchronous responses of soil microbial community and understory plant community to simulated nitrogen deposition in a subtropical forest
Authors: Wu Jianping , Liu Wenfei , Fan Houbao , Huang Guomin , Wan Songze , Yuan Yinghong , Ji Chunfeng 
Published: October 2013

AbstractAtmospheric nitrogen (N) deposition greatly affects ecosystem processes and properties. However, few studies have simultaneously examined the responses of both the above‐ and belowground communities to N deposition. Here, we investigated the effects of 8 years of simulated N deposition on soil microbial communities and plant diversity in a subtropical forest. The quantities of experimental N added (g of N m−2 year−1) and treatment codes were 0 (N0, control), 6 (N1), 12 (N2), and 24 (N3). Phospholipid fatty acids (PLFAs) analysis was used to characterize the soil microbial community while plant diversity and coverage were determined in the permanent field plots. Microbial abundance was reduced by the N3 treatment, and plant species richness and coverage were reduced by both N2 and N3 treatments. Declines in plant species richness were associated with decreased abundance of arbuscular mycorrhizal fungi, increased bacterial stress index, and reduced soil pH. The plasticity of soil microbial community would be more related to the different responses among treatments when compared with plant community. These results indicate that long‐term N deposition has greater effects on the understory plant community than on the soil microbial community and different conservation strategies should be considered.
Biogenic Manganese–Calcium Oxides on the Cell Walls of the Algae Chara Corallina: Elemental Composition, Atomic Structure, and Water‐Oxidation Catalysis
Authors: Schöler Andreas , Zaharieva Ivelina , Zimmermann Sebastian , Wiechen Mathias , Manke Anne‐Marie , Kurz Philipp , Plieth Christoph , Dau Holger 
Published: October 2013

AbstractChara corallina freshwater algae produce brown deposits of manganese oxides on their cell wall surfaces when growing in manganese‐rich media. We report on the formation, topology, composition, atomic structure, and catalytic activities of these biogenic manganese oxides (BMOs). The deposits are volcano shaped and exhibit 3–5 μm craters in their centers. Microfocus X‐ray irradiation and detection of characteristic X‐ray fluorescence lines allowed elemental mapping at 5 μm spatial resolution and the identification of the volcano‐shaped deposits as a Mn–Ca oxide. X‐ray absorption spectroscopy (XAS) revealed a high‐valent MnIII/IV oxide. The structural analysis involved XAS spectra collected for a single volcano at room temperature and for single cells at 20 K. On the basis of the XAS data, the oxides were identified as members of the birnessite family of layered manganese oxides containing di‐μ‐oxido‐bridged MnIII/IVO6 octahedra as central building units. The deposits share structural motifs with synthetic water‐oxidizing Mn–Ca oxides and with the Mn4Ca complex of photosystem II, the biological water‐oxidation catalyst. Model reactions demonstrate low, but clearly detectable, activity of the manganese deposits for water‐oxidation catalysis. The biogenic manganese oxides on the cell walls of Chara corallina thus represent an intriguing object to study how manganese‐based catalysts for water oxidation are formed in a biological environment. The formation of BMOs in relation to cellular ion transport and the possibility of BMOs to fulfill a detoxification function in plants were also examined.
Synthesis, Cellular Uptake and Biological Activity Against Pathogenic Microorganisms and Cancer Cells of Rhodium and Iridium N‐Heterocyclic Carbene Complexes Bearing Charged Substituents
Authors: Simpson Peter V. , Schmidt Claudia , Ott Ingo , Bruhn Heike , Schatzschneider Ulrich 
Published: October 2013

AbstractFour new N‐heterocyclic carbene (NHC) rhodium and iridium complexes decorated with anionic or cationic pendant groups to increase their water solubility and biological activity have been synthesised and characterised. The lipophilicity of the complexes was determined and the complexes that contained cationic phosphonium groups can be considered delocalised lipophilic cations (DLCs). All complexes were tested for their antibacterial, antiparasitic and anticancer activity, with only the phosphonium‐functionalised complexes showing moderate to high activity, whereas the exchange of metal from rhodium to iridium had a negligible effect. Most promising was the activity on Trypanosoma brucei, with IC50 values in the range of 150–400 nM and a selectivity index (SI) of up to 50. General toxicity on mammalian cell lines was a general problem, though, and needs to be mitigated in future work. Cellular uptake studies clearly confirmed that the cationic phosphonium groups facilitated uptake, which was linked with higher biological activity.
The Oxonitridoborate Eu5(BO2.51(7)N0.49(7))4 and the Mixed‐Valent Borates Sr3Ln2(BO3)4 (Ln = Ho, Er)
Authors: Höppe Henning A. , Kazmierczak Karolina , Grumbt Christine , Schindler Lisa , Schellenberg Inga , Pöttgen Rainer 
Published: October 2013

AbstractThe crystal structures of the mixed borates Sr3Er2(BO3)4 [Pnma, no. 62, Z = 4, a = 738.08(2), b = 1588.94(4), c = 867.81(2) pm, 683 reflections, 70 parameters, R1 = 0.037, wR2 = 0.077] and Sr3Ho2(BO3)4 [Pnma, no. 62, Z = 4, a = 738.45(7), b = 1591.55(12), c = 871.03(9) pm, 691 reflections, 59 parameters, R1 = 0.069, wR2 = 0.098] and europium oxonitridoborate Eu5(BO2.51(7)N0.49(7))4 [Pnma, no. 62, Z = 12, a = 2232.2(5), b = 1603.1(3), c = 879.59(18) pm, 2880 reflections, 313 parameters, R1 = 0.027, wR2 = 0.059] were solved from single‐crystal X‐ray diffraction data. Eu5(BO2.51(7)N0.49(7))4 adopts a threefold superstructure of the structure of Sr3Ln2(BO3)4 (Ln = Ho, Er). In both structure types, the different cations are situated on common sites with a pronounced preferential occupation but no complete ordering. These conclusions are based on the crystal structure refinement, 151Eu Mössbauer spectroscopy and MAPLE (Madelung part of lattice energy) calculations. The proposed Eu5(BO3)4 contains nitrogen and has a formula Eu5(BO2.51(7)N0.49(7))4 as confirmed by 151Eu Mössbauer spectroscopy. The optical reflectance spectrum of Eu5(BO2.51(7)N0.49(7))4 is in accordance with the yellow colour of the compound.
Convenient Preparation of Ternary Carbidoaluminates – The Example MgAl2C2
Authors: Kubus Mariusz , Meyer H.‐Jürgen 
Published: October 2013

AbstractA new synthesis route for β‐MgAl2C2 is presented. The synthesis of this carbide compound was based on a solid‐state metathesis reaction. The material was prepared at 900 °C from aluminium powder, MgCl2 and Li2C2. The reaction product was inspected by X‐ray powder diffraction and 13C NMR spectroscopy.
Synthesis, Structure, Gas‐Phase Reactivity, and Catalytic Relevance of Trinuclear Mo3S4 Clusters Bearing Terminal Hydroxo and Hydrosulfido Groups
Authors: Beltrán Tomás F. , Feliz Marta , Llusar Rosa , Safont Vicent S. , Vicent Cristian 
Published: October 2013

AbstractMolybdenum(IV) hydroxo [Mo3S4(dmpe)3(OH)3]+ (1+) and hydrosulfido [Mo3S4(dmpe)3(SH)3]+ (2+) [dmpe = 1,2‐bis(dimethylphosphanyl)ethane] trimetallic cuboidal cluster complexes have been isolated in high yields by treating their chloride precursors with sodium hydroxide or sodium hydrosulfide, respectively. The crystal structures of [1]BPh4 and [2]PF6 confirm that –QH (Q = O, S) groups are coordinated to metal centers. Both hydroxo and hydrosulfido Mo3S4 cluster complexes are fully characterized by spectroscopic, mass spectrometric, and X‐ray techniques. A comparative study of the gas‐phase dissociation of 1+ and 2+ cations using ESI tandem mass spectrometry is presented, and the results are compared with those already reported for the hydroxo tungsten analogue. The gas‐phase reactivity of 1+ and 2+ species towards ethanol and 1‐penthanethiol have been explored. The gas‐phase‐generated [Mo3S4(dmpe)2(O)(OH)]+ cation activates ethanol molecules through a similar mechanism to that proposed for its tungsten congener. The main differences in aldehyde elimination under collision‐induced dissociation (CID) conditions between molybdenum and tungsten cluster sulfides are discussed.
Synthesis and Oligomerization of Cyclodiphosph(V)azene Adducts
Authors: Bendle Martin , Kuzora Rene , Manners Ian , Rupar Paul , Schulz Axel , Villinger Alexander 
Published: October 2013

AbstractThe reaction of R1R2PCl (R1 = Me, Ph; R2 = Ph, oTol) with N,N′‐bis(trimethylsilyl)sulfur diimide in the presence of GaCl3 yields Lewis acid/base adducts of the corresponding cyclodiphosph(V)azenes: [MePhPN]2·(GaCl3)2, [Me(dmp)PN]2·(GaCl3)2 (dmp = 2,6‐dimethylphenyl), and [Ph(oTol)PN]2·(GaCl3)2. The same synthetic protocol was applied for the model compound Ph2AsCl. All isolated products were characterized spectroscopically and by single‐crystal X‐ray diffraction studies. Their ability to form oligomers/polymers induced by abstraction of the Lewis acid was investigated with the model compounds [MePhPN]2·(GaCl3)2 and [Ph2PN]2·(GaCl3)2.
Ruthenium–Triazene Complexes as Latent Catalysts for UV‐Induced ROMP
Authors: Wang Dongren , Unold Jörg , Bubrin Martina , Elser Iris , Frey Wolfgang , Kaim Wolfgang , Xu Guangjuan , Buchmeiser Michael R. 
Published: October 2013

AbstractThree novel ruthenium(II) complexes, RuX2(IMesH2)[N,N‐diethyl‐N′‐(2‐benzylidene)triazene] [IMesH2 = 1,3‐dimesitylimidazolin‐2‐ylidene; X = Cl– (2), CF3COO– (3), C6F5COO– (4)] are described. Single‐crystal X‐ray structure analysis of compounds 2–4 revealed that the triazene ligand exists in the trans form and that the aryl‐connected nitrogen atom of the triazene binds to the ruthenium atom to form a five‐membered chelate ring. Compounds 2–4 were applied to the UV‐induced ring‐opening metathesis polymerization (ROMP) of cis‐cyclooctene (5) and dicyclopentadiene (6). Whereas all three precatalysts show pronounced thermal latency in the presence of 5 or 6, only compound 2 displays significant photo‐ROMP activity. The photoreactivity of precatalysts 2–4, which decreases with increasing electron‐withdrawing character and with decreasing pKa of the X groups, is discussed and correlated with the X‐ray data of 2–4, with low‐temperature 1H NMR measurements as well as with cyclovoltammetric measurements.