bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining Visible Light Catalysis and Transition Metal Catalysis for the Alkylation of Secondary Amines
Authors: Gao Xue‐Wang , Meng Qing‐Yuan , Xiang Ming , Chen Bin , Feng Ke , Tung Chen‐Ho , Wu Li‐Zhu
Published: August 2013

By combining the visible‐light catalyst, Ru(bpy)3Cl2, and transition metal salts, Cu(OTf)2, we are able to functionalize secondary amines to form Csp3Csp3 bonds with β‐keto esters efficiently by an aerobic oxidative coupling reaction under visible light irradiation at ambient conditions.

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Palladium‐Catalyzed Direct Alkoxycarbonylation of Aromatic CH Bonds via Selective CC Cleavage of α‐Keto Esters
Authors: Zhou Wei , Li Pinhua , Zhang Yicheng , Wang Lei
Published: August 2013

A novel palladium‐catalyzed direct alkoxycarbonylation of 2‐arylpyridines, 2‐arylquinolines, benzo[h]quinolines, 2‐phenylpyrimidines, N‐pyrimidine pyrroles and N‐pyrimidine indoles via aromatic CH bond activation and selective CC cleavage of α‐keto esters has been developed. The method has the advantages of wide functional group tolerance, high selectivity, broad range of substrates and good yields.

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Efficient Construction of CN Double Bonds via Acceptorless Dehydrogenative Coupling
Authors: Sun Xiang , Hu Yu , Nie Shao‐zhen , Yan Yun‐yun , Zhang Xue‐jing , Yan Ming
Published: August 2013

The efficient construction of CN double bonds has been achieved by the Ir‐catalyzed intramolecular acceptorless dehydrogenative cross‐coupling of tertiary amines and amides. An iridium/2‐hydroxypyridine complex was identified as the highly efficient catalyst. A number of quinazolinone derivatives was prepared in excellent yields. An iridium‐mediated CH activation mechanism is proposed. This finding provides an unprecedented strategy for the direct imidation of sp3 CH bonds.

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Copper(I) Iodide‐Catalysed Aerobic Oxidative Synthesis of Imidazo[1,2‐a]pyridines from 2‐Aminopyridines and Methyl Ketones
Authors: Chandra Mohan Darapaneni , Reddy Donthiri Ramachandra , Nageswara Rao Sadu , Adimurthy Subbarayappa
Published: August 2013

We report here an operationally simple copper‐catalysed synthesis of imidazo[1,2‐a]pyridines through CH activation with oxidative linkage of two CN bonds under very mild conditions using molecular oxygen as a sole oxidant. The process allows the quick assembly of imidazo[1,2‐a]pyridines including the antiulcer drug zolimidine from inexpensive and readily available 2‐aminopyridines and methyl ketones with broad range of functional group tolerance.

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Copper Acetoacetonate [Cu(acac)2]/BINAP‐Promoted Csp3N Bond Formation via Reductive Coupling of N‐Tosylhydrazones with Anilines
Authors: Aziz Jessy , Brion Jean‐Daniel , Hamze Abdallah , Alami Mouad
Published: August 2013

We report the the copper(II) acetoacetonate [Cu(acac)2]/BINAP‐catalyzed synthesis of arylamines from N‐tosylhydrazones and anilines. A fine tuning of the reaction conditions was required to accomplish the cross‐coupling successfully, including the ligands effect and the addition of small amounts of water. The characteristic feature of this protocol is its functional group compatibility and its chemoselectivity when various aminophenol derivatives were used. Taking into consideration the interest for this copper‐reductive coupling in which no stoichiometric metal hydride reagent is employed, this can be considered as an alternative to the conventional reductive amination.

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Silver‐Catalyzed Decarboxylative Acylarylation of Acrylamides with α‐Oxocarboxylic Acids in Aqueous Media
Authors: Wang Hua , Guo Li‐Na , Duan Xin‐Hua
Published: August 2013

A mild and efficient silver‐catalyzed acylarylation of activated alkenes with easily available α‐oxocarboxylic acids has been developed. The reactions provide a rapid access to a variety of functionalized oxindoles via a tandem decarboxylative radical cyclization strategy. This transformation proceeds well under mild reaction conditions and exhibits excellent functional group tolerance, affording the desired oxindoles in good to excellent yields.

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Metal‐Free Oxidative Coupling: Xanthone Formation via Direct Annulation of 2‐Aryloxybenzaldehyde using Tetrabutylammonium Bromide as a Promoter in Aqueous Medium
Authors: Rao Honghua , Ma Xinyi , Liu Qianzi , Li Zhongfeng , Cao Shengli , Li Chao‐Jun
Published: August 2013

A metal‐free intramolecular annulation of 2‐aryloxybenzaldehydes to xanthones is disclosed, which proceeds through the direct oxidative coupling of an aldehyde CH bond and aromatic CH bonds using tetrabutylammonium bromide (TBAB) as a promoter in aqueous medium. This strategy works smoothly in the presence of both electron‐donating and electron‐withdrawing groups, and displays good tolerance towards catalytically reactive substituents, thus promising further functionalizations of xanthone products.

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Copper(I)‐Catalyzed Boron Addition Reactions of Alkynes with Diboron Reagents
Authors: Yun Jaesook
Published: August 2013

The development of catalytic Cu‐B additions to carbon–carbon unsaturated bonds (borylcupration) with high regio‐ and stereoselectivity has enabled facile and direct syntheses of alkenylboronic esters, which are versatile synthetic intermediates in organic synthesis. An increasing number of relevant reactions have been reported over the past several years, which can be categorized based on the electrophilic reagent that reacts with the common alkenylcopper intermediates that are generated in situ by Cu‐B addition to alkynes. In this Focus Review, recent advances in copper‐catalyzed boron addition reactions for the synthesis of alkenylboronic esters with diboron reagents are summarized.
Death of the (traveling) salesman: Primates do not show clear evidence of multi‐step route planning
Authors: Janson Charles
Published: August 2013

Several comparative studies have linked larger brain size to a fruit‐eating diet in primates and other animals. The general explanation for this correlation is that fruit is a complex resource base, consisting of many discrete patches of many species, each with distinct nutritional traits, the production of which changes predictably both within and between seasons. Using this information to devise optimal spatial foraging strategies is among the most difficult problems to solve in all of mathematics, a version of the famous Traveling Salesman Problem. Several authors have suggested that primates might use their large brains and complex cognition to plan foraging strategies that approximate optimal solutions to this problem. Three empirical studies have examined how captive primates move when confronted with the simplest version of the problem: a spatial array of equally valuable goals. These studies have all concluded that the subjects remember many food source locations and show very efficient travel paths; some authors also inferred that the subjects may plan their movements based on considering combinations of three or more future goals at a time. This analysis reexamines critically the claims of planned movement sequences from the evidence presented. The efficiency of observed travel paths is largely consistent with use of the simplest of foraging rules, such as visiting the nearest unused “known” resource. Detailed movement sequences by test subjects are most consistent with a rule that mentally sums spatial information from all unused resources in a given trial into a single “gravity” measure that guides movements to one destination at a time. Am. J. Primatol. Am. J. Primatol. 76:410–420, 2014. © 2013 Wiley Periodicals, Inc.
Entwicklung struktureller Komplexität durch Selbstorganisation in flüssigkristallinen Systemen
Authors: Tschierske Carsten
Published: August 2013

Seit der Entdeckung erster Flüssigkristalle vor 125 Jahren haben sich diese zu einem Wissenschaftsgebiet mit vielseitigen Facetten entwickelt. Dieser Aufsatz beleuchtet aktuelle Entwicklungen auf diesem Gebiet mit dem Schwerpunkt auf dem molekularen Design flüssigkristalliner Materialien und ihrer Selbstorganisation. Im Fokus stehen neue und ungewöhnliche Organisationsformen mit erhöhter Komplexität, wie zelluläre Strukturen, “mehrfarbige” Kompartimentierungen, komplexe periodische und quasiperiodische Anordnungen von sphärischen Aggregaten und Nanopartikeln, sowie resultierende Phänomene wie Ferroelektrizität und Symmetriebruch. Diese werden in Zusammenhang mit anderen geordneten Strukturen in selbstorganisierten Monoschichten, in Multiblock‐Copolymeren und periodischen Nanopartikel‐Arrays diskutiert. Als Maß der strukturellen Komplexität dienen die Größe der resultierenden periodischen Gitter, der Grad der Kompartimentierung des Raumes und die “logische Tiefe” der Überstrukturen.
Sulfoximine: Eine vernachlässigte Chance in der medizinischen Chemie
Authors: Lücking Ulrich
Published: August 2013

Innovation ist häufig als der Schlüssel zur Wirkstoff‐Findung beschrieben worden. Doch in der täglichen Routine neigen Medizinalchemiker dazu, nur das Instrumentarium der funktionellen Gruppen und Strukturelemente zu verwenden, das sie bereits kennen und lieben. Das Blockbuster‐Krebsmedikament Velcade (Bortezomib) wurde beispielsweise von mehr als 50 Unternehmen abgelehnt, vermutlich wegen seiner ungewöhnlichen Boronsäuregruppe (“Only a moron would put boron in a drug!”). Auch im Entwicklungsprozess des pan‐CDK‐Inhibitors BAY 1000394 sorgte der unkonventionelle Vorschlag, eine Sulfoximingruppe in die Leitstruktur einzuführen, zunächst für Spott und Stirnrunzeln, da Sulfoximine selten in der medizinischen Chemie verwendet worden sind. Jedoch war es gerade die Sulfoximingruppe, die es schließlich ermöglichte, die fundamentalen Probleme des Projekts zu überwinden, und so zur Identifizierung des klinischen pan‐CDK‐Inhibitors BAY 1000394 führte. Der vorliegende Kurzaufsatz gibt einen Überblick über eine weithin vernachlässigte Chance in der medizinischen Chemie – die Sulfoximingruppe.
Sulfoximines: A Neglected Opportunity in Medicinal Chemistry
Authors: Lücking Ulrich
Published: August 2013

Innovation has frequently been described as the key to drug discovery. However, in the daily routine, medicinal chemists often tend to stick to the functional groups and structural elements they know and love. Blockbuster cancer drug Velcade (bortezomib), for example, was rejected by more than 50 companies, supposedly because of its unusual boronic acid function (as often repeated: “only a moron would put boron in a drug!”). Similarly, in the discovery process of the pan‐CDK inhibitor BAY 1000394, the unconventional proposal to introduce a sulfoximine group into the lead series also led to sneers and raised eyebrows, since sulfoximines have seldom been used in medicinal chemistry. However, it was the introduction of the sulfoximine group that finally allowed the fundamental issues of the project to be overcome, culminating in the identification of the clinical sulfoximine pan‐CDK inhibitor BAY 1000394. This Minireview provides an overview of a widely neglected opportunity in medicinal chemistry—the sulfoximine group.
Vertically aligned carbon nanotube‐based composite: Elaboration and monitoring of the nanotubes alignment
Authors: Huard Mickael , Roussel Florent , Rouzière Stéphan , Patel Stéphanie , Pinault Mathieu , Mayne‐L'Hermite Martine , Launois Pascale
Published: August 2013

We present the different elaboration steps of a composite formed of carbon nanotubes (CNT) carpet embedded in an epoxy polymer. Detailed characterization at each step of the elaboration process is performed. The good alignment of CNT in as‐grown carpets is kept all along the elaboration process of the composite, as it is measured at both macro and microscopic scales by X‐ray scattering. We also ensured by X‐ray fluorescence measurements that the iron‐based catalyst particles used for the synthesis were removed from the carpet after a high temperature post‐annealing treatment. These measurements give valuable information for further applications involving unidirectional nanotube composites and membranes, where CNT alignment is a key parameter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39730.
Reactive red 120 and NI(II) derived poly(2‐hydroxyethyl methacrylate) nanoparticles for urease adsorption
Authors: Türkcan Ceren , Uygun Deniz Aktaş , Akgöl Sinan , Denizli Adil
Published: August 2013

Non‐porous poly(2‐hydroxyethyl methacrylate) [p(HEMA)] nanoparticles were prepared by surfactant free emulsion polymerization. The p(HEMA) nanoparticles was about 200 nm diameter, spherical form, and non‐porous. Reactive Red 120 (RR 120) was covalently attached to the p(HEMA) nanoparticles and Ni(II) ions were incorporated to attach dye molecules. Urease was immobilized onto RR120‐Ni(II) attached p(HEMA) nanoparticles via adsorption. The maximum urease adsorption capacity of RR120‐Ni(II) attached p(HEMA) nanoparticles was 480.01 mg g−1 nanoparticles at pH 7.0 in phosphate buffer. It was observed that urease could be repeatedly adsorbed and desorbed without significant loss in adsorption amount. Km values were 21.50 and 34.06 mM for the free and adsorbed enzyme. The Vmax values were 4 U for the free enzyme and 3.3 U for the adsorbed enzyme. The optimum pH was 25 mM pH 7 phosphate buffer for free and adsorbed enzyme. The optimum temperature was determined at 35°C and 55°C for the free and adsorbed enzyme, respectively. These findings show considerable promise for this material as an adsorption matrix in biotechnological applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39757.
Properties and phase segregation of crosslinked PCL‐based polyurethanes
Authors: Güney Aysun , Hasirci Nesrin
Published: August 2013

Polyurethane (PU) films were prepared from different types of poly(ε‐caprolactone) glycols and hexamethylene diisocyanate without using any other ingredients such as solvent, catalyst, or chain extender. Polymers were stabilized by crosslinking formed as allophanate and/or biuret linkages during the curing process. The effects of different components on the product properties such as chemical structure, microphase segregation, mechanical strength, thermo‐mechanical, thermal properties, and surface hydrophilicities were investigated by FTIR‐ATR, atomic force microscope, mechanical tester, dynamic mechanical analyses, thermogravimetric analyzer, differential scanning calorimetry, and contact angle measurements. Phase separation of hard and soft segments significantly varied depending on the type and molecular weight of diol and triol. Films containing urethane‐urea bonds displayed the maximum phase separation and the highest mechanical strength. Polyols having higher molecular weight increased hydrophilicity while urea bonds caused a reverse effect resulted by bidentate hydrogen bonds. Results showed PUs with various properties can be synthesized via environmentally friendly process without using any solvent or catalyst. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39758.
A redox‐mediator‐doped gel polymer electrolyte applied in quasi‐solid‐state supercapacitors
Authors: Yu Fuda , Huang Miaoliang , Wu Jihuai , Qiu Zhaoyuan , Fan Leqing , Lin Jianming , Lin Yibing
Published: August 2013

Methylene blue (MB) redox mediator was introduced into polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend host to prepare a gel polymer electrolyte (PVA‐PVP‐H2SO4‐MB) for a quasi‐solid‐state supercapacitor. The electrochemical properties of the supercapacitor with the prepared gel polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and self‐discharge measurements. With the addition of MB mediator, the ionic conductivity of gel polymer electrolyte increased by 56% up to 36.3 mS·cm−1, and the series resistance reduced, because of the more efficient ionic conduction and higher charge transfer rate, respectively. The electrode specific capacitance of the supercapacitor with PVA‐PVP‐H2SO4‐MB electrolyte is 328 F·g−1, increasing by 164% compared to that of MB‐undoped system at the same current density of 1 A·g−1. Meanwhile, the energy density of the supercapacitor increases from 3.2 to 10.3 Wh·kg−1. The quasi‐solid‐state supercapacitor showed excellent cyclability over 2000 charge/discharge cycles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39784.
Designing oligomeric ethylene terephtalate building blocks by chemical recycling of polyethylene terephtalate
Authors: Geyer Björn , Röhner Stefan , Lorenz Günter , Kandelbauer Andreas
Published: August 2013

The intelligent recycling of plastics waste is a major concern. Because of the widespread use of polyethylene terephtalate, considerable amounts of PET waste are generated that are ideally re‐introduced into the material cycle by generating second generation products without loss of materials performance. Chemical recycling methods are often expensive and entail environmentally hazardous by‐products. Established mechanical methods generally provide materials of reduced quality, leading to products of lower quality. These drawbacks can be avoided by the development of new recycling methods that provide materials of high quality in every step of the production cycle. In the present work, oligomeric ethylene terephthalate with defined degrees of polymerization and defined molecular weight is produced by melt‐mixing PET with different quantities of adipic acid as an alternative pathway of recycling PET with respect to conventional methods, offering ecofriendly and economical aspects. Additionally, block‐copolyesters of defined block length are designed from the oligomeric products. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39786.
Multimethod Geophysical Survey at the Iron Age Iberian Site of El Molí d'Espígol (Tornabous, Lleida, Catalonia): Exploring Urban Mesh Patterns Using Geophysics
Authors: Sala Roger , Principal Jordi , Olmos Pau , Tamba Robert , Garcia Ekhine
Published: August 2013

This paper presents the results of a multisystem survey using magnetometry and dual frequency ground‐penetrating radar (GPR) carried out at the Iron Age Iberian site of El Molí d'Espígol, Tornabous, Catalonia, dated from the seventh to third centuries bce. The surroundings of the current urban area were explored with magnetometry in order to describe possible features related to the settlement. In the non‐excavated part of the urban area was surveyed by GPR in order to describe the urban mesh. The interpretation of the data has allowed not only the identification of new areas of archaeological interest and priority action, but also the proposal of a new hypotheses on the evolution of the town planning and the defensive system of the site. Copyright © 2013 John Wiley & Sons, Ltd.
Estimation of convective precipitation mass from lightning data using a temporal sliding‐window for a series of thunderstorms in Southeastern Brazil
Authors: Garcia João V. C. , Stephany Stephan , d'Oliveira Augusto B.
Published: August 2013

Some studies have proposed the estimation of convective rainfall from lightning observations by the computation of the rainfall–lightning ratio (RLR). However, as such ratio may depend on season, convective regime and other factors, known approaches failed to provide values of RLR with low variability. An accurate RLR would allow estimating rainfall from lightning data in areas that lack weather radar coverage. This work proposes a straightforward approach for the computation of RLR, based on a temporal sliding‐window and a fitting function. It was tested for thunderstorms observed in the Southeastern Brazil with good results.
Les mystères du point critique
Authors: Yvon Jacques
Published: August 2013

Cette introduction au programme de la conférence sur les phénomènes critiques propose une définition expérimentale de la région critique. Un rappel des résultats de l'étude thermostatique traditionnelle précède la présentation qualitative des singularités qui ont été mises en évidence ces dernières années, ce qui conduit à revoir, mais en partie seulement, les conceptions théoriques. Au cœur même de la région critique, des effets de type capillaire viennent troubler l'observation de milieux qui autrement présentent des phases homogènes. Les phénomènes dynamiques — écoulement, transfert de chaleur, diffusion des rayons X, de la lumière, des neutrons — révèlent de nouvelles singularités. Ces phénomènes suscitent un très vif intérêt. Les résultats en fonction de la température sont exprimés dans chaque cas à l'aide d'un repère qui est la “température critique”: il serait souhaitable que ce repère soit défini avec moins d'arbitraire qu'actuellement.
Tunnelling Processes at Highly Doped ZnO‐Electrodes in Aqueous Electrolytes Part II: Electron Exchange with the Valence Band
Authors: Pettinger B. , Schöppel H.‐R. , Yokoyama T. , Gerischer H.
Published: August 2013

Highly doped ZnO‐electrodes show a blocking region of only about 3 V. Above this region anodic breakdown currents set in which rise steeply with increasing potentials. The currents are attributed to the generation of holes by field emission of valence electrons into the conduction band. The generation of holes is shown by surface reactions, like the oxidative lattice decomposition, or by the current multiplication in particular oxidation reactions of organic substances which are well known as being caused by holes. Another indication of hole generation is the light emission during anodic breakdown currents caused by recombination of holes with electrons.

On the polar ZnO surfaces (〈0001〉 and 〈0001〉 surface) considerable differences are observed in the anodic currents and in the composition of reaction products.
Drug‐coated balloon treatment of coronary artery disease: A position paper of the Italian Society of Interventional Cardiology
Authors: Cortese Bernardo , Berti Sergio , Biondi‐Zoccai Giuseppe , Colombo Antonio , Limbruno Ugo , Bedogni Francesco , Cremonesi Alberto , Silva Pedro Leon , Sgueglia Gregory A.
Published: August 2013

Drug‐coated balloons are a new tool for the treatment of patients with coronary artery disease. The main feature of this technology is a rapid and homogenous transfer of an antiproliferative drug (paclitaxel) to the vessel wall just at the time of balloon inflation, when neointimal proliferation, in response to angioplasty, is the highest. Moreover, drug‐coated balloons share adjuntive advantages over stents: the absence of permanent scaffold and polymer, the respect of the original coronary anatomy, and limited inflammatory stimuli, thereby allowing for short‐term dual antiplatelet therapy. To this day, a lot of devices are available in the market, with limited scientific data for the vast majority of them. Thus, the Italian scientific society of interventional cardiologists GISE decided to coordinate the efforts of a group of reknown experts on the field, in order to obtain a Position Paper on the correct use of drug‐coated balloons in all the settings of coronary artery disease, giving a class of indication to each one, based on the clinical evidence. This Position Paper represents a quick reference for operators, investigators, and manufactures to promote the understanding and the correct use of the drug‐coated balloon technology in everyday clinical practice. © 2013 Wiley Periodicals, Inc.
Ruthenium‐Catalyzed Hydrogenation of Oxygen‐Functionalized Aromatic Compounds in Water
Authors: Jantke Dominik , Cokoja Mirza , Drees Markus , Herrmann Wolfgang A. , Kühn Fritz E.
Published: August 2013

The application of a ruthenium complex, bearing a sulfonated bis‐N‐heterocyclic carbene (NHC) ligand as catalyst precursor for the hydrogenation of aromatic compounds is reported. The reaction proceeds under mild conditions in aqueous phase. The treatment of the Ru complex with 40 bar H2 at 60 °C in water (0.1 M KOH solution) leads to the formation of a catalytically active species, which can be stored and used in catalysis experiments. The catalyst is responsible for the hydrogenation of functionalized aromatic substrates exhibiting endo‐ and exo‐CO bonds, which are relevant products in biomass conversion. Acetophenone is quantitatively reduced to 1‐cyclohexyl ethanol with a selectivity of 100 %. Various other oxygen‐functionalized aromatic substrates were also hydrogenated in moderate to quantitative conversions. To elucidate the nature of the catalytically active species, NMR, UV/vis, and ESI‐MS experiments were undertaken, showing the presence of a mononuclear Ru hydride complex. TEM measurements of a sample of the catalyst solution did not indicate the presence of nanoparticles. Mechanistic investigations point towards a homogenous mechanism.
Identification of Molecular Crystals Capable of Undergoing an Acyl‐Transfer Reaction Based on Intermolecular Interactions in the Crystal Lattice
Authors: Tamboli Majid I. , Krishnaswamy Shobhana , Gonnade Rajesh G. , Shashidhar Mysore S.
Published: August 2013

Investigation of the intermolecular acyl‐transfer reactivity in molecular crystals of myo‐inositol orthoester derivatives and its correlation with crystal structures enabled us to identify the essential parameters to support efficient acyl‐transfer reactions in crystals: 1) the favorable geometry of the nucleophile (OH) and the electrophile (CO) and 2) the molecular assembly, reinforced by CH⋅⋅⋅π interactions, which supports a domino‐type reaction in crystals. These parameters were used to identify another reactive crystal through a data‐mining study of the Cambridge Structural Database. A 2:1 co‐crystal of 2,3‐naphthalene diol and its di‐p‐methylbenzoate was selected as a potentially reactive crystal and its reactivity was tested by heating the co‐crystals in the presence of solid sodium carbonate. A facile intermolecular p‐toluoyl group transfer was observed as predicted. The successful identification of reactive crystals opens up a new method for the detection of molecular crystals capable of exhibiting acyl‐transfer reactivity.
Butterfly‐Shaped Pentanuclear Dysprosium Single‐Molecule Magnets
Authors: Tian Haiquan , Zhao Lang , Lin Haifeng , Tang Jinkui , Li Guangshe
Published: August 2013

Two new “butterfly‐shaped” pentanuclear dysprosium(III) clusters, [Dy5(μ3‐OH)3(opch)6(H2O)3]⋅3 MeOH⋅ 9 H2O (1) and [Dy5(μ3‐OH)3(Hopch)2(opch)4(MeOH)(H2O)2]⋅(ClO4)2⋅ 6 MeOH⋅4 H2O (2), which were based on the heterodonor‐chelating ligand o‐vanillin pyrazine acylhydrazone (H2opch), have been successfully synthesized by applying different reaction conditions. Single‐crystal X‐ray diffraction analysis revealed that the butterfly‐shaped cores in both compounds were comparable. However, their magnetic properties were drastically different. Indeed, compound 1 showed dual slow‐relaxation processes with a transition between them that corresponded to energy gaps (Δ) of 8.1 and 37.9 K and pre‐exponential factors (τ0) of 1.7×10−5 and 9.7×10−8 s for the low‐ and high‐temperature domains, respectively, whilst only a single relaxation process was noted for compound 2 (Δ=197 K, τ0=3.2×10−9 s). These significant disparities are most likely due to the versatile coordination of the H2opch ligands with particular keto–enol tautomerism, which alters the strength of the local crystal field and, hence, the nature or direction of the easy axes of anisotropic dysprosium ions.
Alkaline Earth Metallocenes Coordinated with Ester Pendants: Synthesis, Structural Characterization, and Application in Metathesis Reactions
Authors: Li Heng , Zhang Wen‐Xiong , Xi Zhenfeng
Published: August 2013

A variety of ester‐substituted cyclopentadiene derivatives have been synthesized by one‐pot reactions of 1,4‐dilithio‐1,3‐butadienes, CO, and acid chlorides. Direct deprotonation of the ester‐substituted cyclopentadienes with Ae[N(SiMe3)2]2 (Ae=Ca, Sr, Ba) efficiently generated members of a new class of heavier alkaline earth (Ca, Sr, Ba) metallocenes in good to excellent yields. Single‐crystal X‐ray structural analysis demonstrated that these heavier alkaline earth metallocenes incorporated two intramolecularly coordinated ester pendants and multiply‐substituted cyclopentadienyl ligands. The corresponding transition metal metallocenes, such as ferrocene derivatives and half‐sandwich cyclopentadienyl tricarbonylrhenium complexes, could be generated highly efficiently by metathesis reactions. The multiply‐substituted cyclopentadiene ligands bearing an ester pendant, and the corresponding heavier alkaline earth and transition‐metal metallocenes, may have further applications in coordination chemistry, organometallic chemistry, and organic synthesis.
Nucleoside Analogues with a 1,3‐DieneFe(CO)3 Substructure: Stereoselective Synthesis, Configurational Assignment, and Apoptosis‐Inducing Activity
Authors: Hirschhäuser Christoph , Velcicky Juraj , Schlawe Daniel , Hessler Erik , Majdalani André , Neudörfl Jörg‐Martin , Prokop Aram , Wieder Thomas , Schmalz Hans‐Günther
Published: August 2013

The synthesis and stereochemical assignment of two classes of iron‐containing nucleoside analogues, both of which contain a butadieneFe(CO)3 substructure, is described. The first type of compounds are Fe(CO)3‐complexed 3′‐alkenyl‐2′,3′‐dideoxy‐2′,3′‐dehydro nucleosides (2,5‐dihydrofuran derivatives), from which the second class of compounds is derived by formal replacement of the ring oxygen atom by a CH2 group (carbocyclic nucleoside analogues). These compounds were prepared in a stereoselective manner through the metal‐assisted introduction of the nucleobase. Whilst the furanoid intermediates were prepared from carbohydrates (such as methyl‐glucopyranoside), the carbocyclic compounds were obtained by using an intramolecular Pauson–Khand reaction. Stereochemical assignments based on NMR and CD spectroscopy were confirmed by X‐ray structural analysis. Biological investigations revealed that several of the complexes exhibited pronounced apoptosis‐inducing properties (through an unusual caspase 3‐independent but ROS‐dependent pathway). Furthermore, some structure–activity relationships were identified, also as a precondition for the design and synthesis of fluorescent and biotin‐labeled conjugates.
Growth of Au@Ag Core–Shell Pentatwinned Nanorods: Tuning the End Facets
Authors: Zhang Weiqing , Goh Hao Ying Johnny , Firdoz Shaik , Lu Xianmao
Published: August 2013

Au@Ag core–shell nanorods with tunable end facets are obtained by coating Au bipyramids (BPs) with Ag. The resultant nanorods exhibit a pentatwinned crystal structure with tips terminated with either {110} or {111} facets. The control over the end facets is achieved by varying the capping agents and tuning the reduction rate of Ag. Specifically, when Ag is reduced slowly, Au@Ag nanorods with flat {110} end facets are formed with cetyltrimethylammonium bromide (CTAB) as the capping agent. If CTAB is replaced with cetyltrimethylammonium chloride (CTAC), Au@Ag nanorods with tips terminated with {111} facets are obtained. However, at a high Ag reduction rate, dumbbell‐shaped Au@Ag nanorods are formed, with either CTAB or CTAC as the capping agent. The morphological evolution of the nanorods in each case is closely followed and a growth mechanism is proposed.
Adsorption and catalytic ozonation performance of activated carbon and cobalt‐supported activated carbon derived from brewing yeast
Authors: Wu Guiping , Wei Wei , Cui Longzhe
Published: August 2013

Activated carbon (AC) was prepared from brewing yeast by NaCO activation, and cobalt was supported on activated carbon (Co/AC) by the adsorption–activation method. The XPS test indicated that supported cobalt was Co(II). The total BET surface areas of prepared AC and Co/AC were 957.7 and 847.9 m/g, with total pore volumes of 0.81 and 0.80 cm/g, respectively. The average pore diameters of AC and Co/AC were found to be 3.8 and 3.3 nm. The contact time required for equilibrium of methylene blue (MB) adsorption onto prepared AC and Co/AC was about 120 min. The maximum uptake of MB by AC and Co/AC was estimated to be 372.1 and 213.5 mg/g, respectively. The presence of prepared AC or Co/AC was advantageous for TOC reduction compared with UV/O system, and the greatest TOC removal was obtained in the presence of Co/AC. The kinetics of the degradation of MB fitted the Langmuir‐first‐order model well. The rate constants of Langmuir first‐order were determined to be 0.0096 min−1 for UV/O/AC and 0.0143 min−1 for UV/O/Co/AC, respectively.
Background Features of Schumann Resonances Observed in Yunnan, Southwestern China
Authors: Xin‐Yan OUYANG , Xue‐Min ZHANG , Xu‐Hui SHEN , Wen‐Yu LOU , Yuan‐Qing MIAO
Published: August 2013

This paper presents the background features of Schumann resonances (SR) observed at the Yongsheng observatory in Yunnan, southwestern China. We calculated the hourly average of the frequency and power spectral density (PSD) of the lowest three SR modes, and analyzed diurnal variation of SR frequency and PSD both in BNS and BEW components around equinoxes and solstices. Diurnal variation of SR PSD is found to be related to the dominant intervals of Asian, African and American thunderstorm centers and the relative position of the observatory to three thunderstorm centers. Diurnal variation of SR frequency is more complicated. SR frequency and PSD at the lowest three modes around the summer solstice and autumn equinox are more variable than that in the spring equinox and winter solstice. The daily median of SR peak frequency in 2011 shows that seasonal variation of peak frequency is blurry, while annual variation of daily median of PSD shows a clear seasonal variation which resembled half a period of a sine curve and symmetrically distributed about July. The seasonal variation of PSD is in accordance with that of lightning activities. Frequency of the first mode is about at 7.5 Hz both in BNS and BEW components. However, with the higher mode, SR frequency in BNS component is 0.5 Hz larger than that in BEW component. The cause of this frequency shift is not clear yet.
The Exhumation Process of Mufushan Granite in Jiangnan Uplift Since Cenozoic: Evidence from Low‐Temperature Thermochronology
Authors: Hong‐Cai SHI , Xiao‐Bin SHI , Xiao‐Qiu YANG , Hai‐Yan JIANG
Published: August 2013

Jiangnan uplift located in the collision zone between Yangtze and Cathaysia block is the key to interpret the tectonic evolution of South China block. The Cenozoic thermal history and the uplift processes of Mufushan pluton are constrained by the combination of analysis of apatite fission track and (U‐Th‐Sm)/He ages with modeling of fission track length distribution. Based on the analysis of thermochronological dating and regional tectonic setting, the authors probed into the relationship between the thermochronological evolution and the tectonic development. The exhumation of plutons arrived at about 4800 m since 80 Ma, and the uplift processes were not uniform in space, and different plutons had somewhat different uplift processes. Thermal history modeling of the AFT data shows that the Mufushan pluton experienced three episodes of cooling event, two rapid exhumation events happened in Upper Cretaceous‐Paleocene (about 80∼50 Ma) and Upper Miocene (since 10 Ma). There is a period of relative thermal stability between 50 and 10 Ma. The first stage of rapid uplifting during 80∼50 Ma in this region is coeval with extension episode of Mid‐Upper Yangtze during Himalayan which resulted in the formation of fault basin and exhumation of shoulder block; the Upper Miocene rapid cooling since 10 Ma is attributed to the westward movement and subduction of Pacific plate. The uplift and exhumation of Mufushan pluton since Late Yanshanian led to a good deposition response in basins and the cooling events of three phases just coincided with the regional tectonic settings of study area.
A Study on Parallel Computation for 3D Magneto‐Telluric Modeling Using the Staggered‐Grid Finite Difference Method
Authors: Yan LI , Xiang‐Yun HU , Wen‐Cai YANG , Wen‐Bo WEI , Hui FANG , Bo HAN , Rong‐Hua PENG
Published: August 2013

Computation time and memory requirements are two common problems for magnetotelluric (MT) modeling of three‐dimensional conductivity structure. We develop a new parallel processing scheme that can efficiently improve the computational speed of 3D MT modeling. The scheme of 3D MT modeling based on the staggered‐grid finite difference method is implemented in the frequency domain, and the calculation process of the EM field for each frequency is independent. Therefore, considering the naturally parallelizable character, the whole computation task of all frequencies can be divided into many minor calculation tasks for single or multiple frequencies, which will be assigned to different computing nodes and calculated in a parallel manner. In this work, by adopting master‐slave parallel mode and parallel computation with frequencies scheme, we have implemented the parallel computation of 3D MT modeling using MPI on the Dawn TC5000A high‐performance parallel platform. Furthermore, we tested our parallel algorithm of 3D MT modeling using two 3D theoretical models and analyzed the calculation efficiency on a multiple‐nodes computer, and the results show that the parallel algorithm is effective and efficient, which lays a solid foundation for subsequent three‐dimensional parallel MT inversion.
Correlation Between Space and Ground‐Based Observational Data in Their Near Direct Current Electric Field Background Characteristics
Authors: Rui YAN , Lan‐Wei WANG , Shi‐Zhong ZHANG , Zhe HU , Xing‐Guo ZHANG , Da‐Peng LIU , Xu ZHU , Yu ZHANG
Published: August 2013

Study of the characteristics of space‐ and ground‐based electromagnetic observational data, as well as the correlation between them, has important scientific significance for the combined application of both data to earthquake monitoring and research. In this paper, the near DC electromagnetic data recorded by the DEMETER satellite, vertical and horizontal geoelectric field data recorded at the Hongshawan station, and horizontal geoelectric field data recorded at the Chengdu station were comprehensively studied. The results show that observational data of the ULF electric field recorded directly by the DEMETER satellite do not indicate any significant annual change trends; the observational data from along the velocity vector direction on both the day and night sides present longer‐term cyclical characteristics, but no correlation or synchronization with the geoelectric field observational data. The magnitude of the electric field data in the ionosphere after removing the additional electric field values caused by the satellite cutting the magnetic line are consistent with the geoelectric field data, and concentrated at about 10−1∼ 10−2 mV/m. The concave annual seasonal change trends are displayed from the observation data along the normal to the orbit direction, and along the velocity vector direction on the night side, showing a relatively stable annual variation period, which is consistent with the trend of the annual variation of the horizontal geoelectric field. Therefore, it may be concluded that both the magnitude and annual trends have exhibited correlation and synchronization every year.
Seismic Imaging of Complex and Steep Structures in the Kuqa Depression
Authors: Li‐Yun FU , You‐Jun XIAO , Wei‐Jia SUN , Chao WU , Xi‐Zhu GUAN , Jing‐Zhou ZHANG
Published: August 2013

Seismic imaging generally relies on data quality, velocity reliability, and migration operator performance. Complex near‐surface geological conditions in Kuqa depression cause extremely low signal‐to‐noise (S/N) ratios of seismic data. Salts penetrating into overthrust structures are widely distributed, vary in thickness and shape of complex geometries, and distort the imaging of subsalt faults, leading to complicated imaging problems. This article studies three key issues. In the preprocessing of prestack data, some innovative techniques combined with commercial techniques are employed by three levels to improve data quality and reconstruct the reflections from depths. Three‐stage migration velocity analyses, subtle DMO velocity analysis, prestack time‐migration, and prestack depth‐migration velocity analyses are implemented to build a topology‐preservation prestack‐migration velocity model. The time‐depth conversion of the prestack time‐migration velocity model is performed based on the Kuqa‐depression modeling of salt‐related overthrust complex structures combined with the velocity‐varying mapping technique. The well‐constrained seismic inversion for low‐frequency velocities is conducted to handle the syncretization of the well‐building and migration‐building velocity fields. Finally, prestack time and depth migrations are performed by a semi‐analytic degenerate Fourier migrator that improves the imaging of high‐wavenumber components. Applications to the Dabei, Bozi, Quele, Xiqiu10, and Xiqiu4 structures result in well‐positioned images for salt‐related overthrust complex structures.
Is FapyG Mutagenic?: Evidence from the DFT Study
Authors: Jena Nihar Ranjan , Mishra Phool Chand
Published: August 2013

2,6‐diamino‐4‐oxo‐5‐formamidopyrimidine (FapyG) is an oxidatively damaged product of guanine (G), which is mainly formed through metabolic processes that produce OH radicals. It has been proposed that in bacterial cells, FapyG retains the coding properties of G, and is, therefore, not mutagenic. However, in mammalian cells, FapyG induces G to thymine (T) mutation more dominantly than another ubiquitous oxidative lesion, that is, 8‐oxoguanine (8‐oxoG). The exact reasons for these coding properties of FapyG are not properly understood. In order to rationalize the cause of FapyG‐mediated mutagenesis, all of the possible base‐pair interactions of FapyG with cytosine (C), adenine (A), and T, in both anti‐ and syn‐ conformations, are studied in detail by using density functional theory (DFT). The effects of solvation on the coding properties of FapyG are also evaluated. We demonstrate that the anti‐FapyG:C base pair has the highest binding energy, and that the base‐pair alignment is similar to that of the normal G:C base pair. Therefore, insertion of C opposite anti‐FapyG is preferred over the other DNA bases. This could be the reason for the non‐mutagenic behavior of FapyG in bacterial cells. However, as the binding patterns and energies of anti‐FpyG:A and syn‐FapyG:A base pairs are similar, and these are also similar to those of the T:A base pair, mammalian polymerases may not distinguish between FapyG and T. As a result, A would be mistakenly inserted opposite either anti‐FapyG or syn‐FapyG, resulting in G to T transverse mutation.
The immunopathogenesis of the HIV tuberculosis immune reconstitution inflammatory syndrome
Authors: Lai Rachel P. J. , Nakiwala Justine K. , Meintjes Graeme , Wilkinson Robert J.
Published: August 2013

HIV‐1 patients co‐infected with some pathogens are at risk of developing the immune reconstitution inflammatory syndrome (IRIS) when initiating antiretroviral therapy (ART). IRIS is characterized by inflammation leading to the clinical worsening of a treated infection or the unmasking of a previously undiagnosed condition or infection. It is commonly associated with tuberculosis (TB), 8–43% of the HIV‐TB co‐infected patients prescribed with antitubercular treatment and ART develop TB‐IRIS. Although IRIS has been recognized for over 20 years, relatively little was known until recently about its pathogenesis. Despite these advances in understanding IRIS, there remains no immune biomarker for diagnostic or prognostic purposes. Here, we review the risk factors associated with TB‐IRIS, the challenges in studying this syndrome, and how T lymphocytes, dysregulated cytokine responses, and innate immunity may contribute to the development of TB‐IRIS.
Ferritic Cathodes Degradation by Potassium/Chromium Poisoning and Air Humidification
Authors: Arregui A. , Rodriguez‐Martinez L. M. , Modena S. , Bertoldi M. , Sglavo V. M.
Published: August 2013

Degradation mechanisms inherent to ferritic LSF‐SDC and LSCF‐GDC cathodes are studied by post‐mortem analysis of cells which suffered the most significant performance deterioration in a set of 18 500 h tests carried out under a specific experimental design. Three cathode processing parameters (composition, thickness, and sintering temperature) were combined with five operation conditions (chromium presence, current density, operating temperature, air flow, and humidification) through this design of experiments based in a L18 Taguchi matrix. In the case of cells exposed to chromium vapors from Crofer 22 APU pieces, those cells which exhibited K2Cr2O7 deposition in the cathode/GDC barrier interface underwent the most aggressive ASR degradation. Similar deposits were also observed on the surface of LSC current collectors. Two cells exposed to highly humidified air (20%) exhibited cathode delamination and GDC barrier deterioration by crack propagation though no foreign elements diffusion to the interface could be detected.
Modifying a Stainless Steel for PEMFC Bipolar Plates via Electrochemical Nitridation
Authors: Wang H. , Turner J. A.
Published: August 2013

AISI446 stainless steel was electrochemically nitrided at room temperature. X‐ray photoelectron spectroscopy (XPS) analysis indicated that the nitrided steel was covered with surface ammonia and a layer of nitrides (mainly of mixed chromium nitrides). The nitride layer for 4 h nitrided steel at –0.9 V was about 2.5 nm thick. Dominating oxides appear on the steel's surface, so nitrogen incorporated oxides is a suitable term to describe the nitrided surface. The nitrided surface showed very low interfacial contact resistance (ICR) and excellent corrosion resistance in simulated polymer electrolyte membrane fuel cell (PEMFC) environments. The excellent stability of the nitride steel was confirmed by XPS depth profiling before and after testing in the PEMFC environments. Electrochemical nitridation provides an economic way for modifying the steel's surface to approach the U.S. Department of Energy 2015 goal for bipolar plates.
Common chromosome fragile sites in human and murine epithelial cells and FHIT/FRA3B loss‐induced global genome instability
Authors: Hosseini Seyed Ali , Horton Susan , Saldivar Joshua C. , Miuma Satoshi , Stampfer Martha R. , Heerema Nyla A. , Huebner Kay
Published: August 2013

Chromosomal positions of common fragile sites differ in lymphoblasts and fibroblasts, with positions dependent on the epigenetically determined density of replication origins at these loci. Because rearrangement of fragile loci and associated loss of fragile gene products are hallmarks of cancers, we aimed to map common fragile sites in epithelial cells, from which most cancers derive. Among the five most frequently activated sites in human epithelial cells were chromosome bands 2q33 and Xq22.1, which are not among top fragile sites identified in lymphoblasts or fibroblasts. FRA16D at 16q23 was among the top three fragile sites in the human epithelial cells examined, as it is in lymphoblasts and fibroblasts, while FRA3B at 3p14.2, the top fragile locus in lymphoblasts, was not fragile in most epithelial cell lines tested. Epithelial cells exhibited varying hierarchies of fragile sites; some frequent epithelial cell fragile sites are apparently not frequently altered in epithelial cancers and sites that are frequently deleted in epithelial cancers are not necessarily among the most fragile. Since we have reported that loss of expression of the FRA3B‐encoded FHIT protein causes increased replication stress‐induced DNA damage, we also examined the effect of FHIT‐deficiency on markers of genome instability in epithelial cells. FHIT‐deficient cells exhibited increases in fragile breaks and in γH2AX and 53BP1 foci in G1 phase cells, confirming in epithelial cells that the FHIT gene and encompassing FRA3B, is a “caretaker gene” necessary for maintenance of genome stability. © 2013 Wiley Periodicals, Inc.