bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantiocontrolled Total Synthesis of (−)‐Mersicarpine
Authors: Iwama Yusuke , Okano Kentaro , Sugimoto Kenji , Tokuyama Hidetoshi 
Published: May 2013

AbstractA racemic synthesis of mersicarpine (1) was achieved by the Mizoroki–Heck reaction and a DIBALH‐mediated reductive ring‐expansion reaction. Based on a first‐generation synthesis, a second‐generation enantiocontrolled total synthesis of (−)‐mersicarpine (1) was achieved by an 8‐pot/11‐step sequence in 21 % overall yield from commercially available 2‐ethylcyclohexanone. Subjection of a ketoester, which was prepared by an asymmetric Michael addition (according to the protocol by d’Angelo and Desmaële), and phenylhydrazine to modified Fischer indole conditions provided a six‐membered tricyclic indole. Benzylic oxidation and subsequent oxime formation provided a ketoxime, which was treated with diisobutylaluminum hydride (DIBALH) to construct the characteristic azepinoindole skeleton in good yield. In the DIBALH‐mediated reductive ring‐expansion reaction, gradually increasing the reaction temperature and in situ‐protection of the nitrogen in an oxygen‐sensitive azepinoindole with a benzyloxycarbonyl (Cbz) group were crucial for the high‐yielding process. With these methodologies, the short‐step and efficient synthesis of (−)‐mersicarpine was accomplished. Several synthetic efforts are also described.
Untersuchungen zur Zitronenbatterie
Authors: Peper‐Bienzeisler Renate , Bröll Leena , Pöhls Christin , Jansen Walter 
Published: May 2013

AbstractDie Zitronenbatterie ist ein wohlbekannter Versuch aus vielen Versuchsanleitungen für Kinder. Er wird aber auch oft eingesetzt, um älteren Schülern und Studenten Grundzüge der Elektrochemie aufzuzeigen. Ein Zinkblech und ein Kupferblech werden dabei in eine Zitrone gesteckt. Die Metalle werden über einen Draht und ein Voltmeter miteinander verbunden, um die Spannung (etwa 0,9 V) zu messen. Doch gewöhnlich ist der Strom zu gering, um eine Leuchtdiode oder einen anderen Verbraucher zu betreiben. Die meisten Lehrbücher und Lehrkräfte präsentieren die folgende Erklärung: Zinkatome werden als positiv geladene Zink‐Ionen gelöst, die Elektronen wandern durch den Draht zum Kupfer. Hier werden Wasserstoff‐Ionen aus der Zitronensäure durch die Elektronen zu Wasserstoff reduziert. Aber ist das wirklich richtig? Dieser Beitrag zeigt, dass die Hauptreaktion an der Kupferelektrode die Reduktion des Sauerstoffs ist. Daher ist die Zitronenbatterie eine Art von Zink/Luft‐Batterie.The lemon battery is a well‐known experiment in many science textbooks for children but also often used for older pupils und students to illustrate electrochemical principles. A piece of zinc and a piece of copper are inserted into a lemon. The metals are connected by a wire and a multimeter to measure the voltage (about 0.9 V). But usually the current is too low to power an LED or another device. Most of the textbooks and most of the teachers present the following explanation: Zinc atoms are dissolved as positive charged zinc ions. The electrons are moving through the wire to the copper. Here hydrogen ions from the citric acid are reduced by the electrons to form hydrogen. But is it really true? We now show here that the main reaction at the copper electrode is the reduction of oxygen. Therefore the lemon battery is a type of a zinc air battery.
An Interpretation of the “Anomalous” Changes in the Low‐Wavenumber Range of the Raman Spectra of L‐Alanine Crystals
Authors: Kolesov Boris A. , Boldyreva Elena V. 
Published: May 2013

Abstract“Anomalous changes” in the temperature‐ and pressure‐ dependences of the intensities and wavenumbers of the two low‐wavenumber modes in Raman spectra of single‐crystals of L‐alanine have been interpreted in terms of a change in relative contributions of stretching and deformational components into the intermolecular vibrational bands. The relative contributions of the two components into a lattice vibration result from a change of relative orientations of molecules linked by hydrogen bonds in a three‐dimensional network on variations of temperature or pressure.
Individual heterogeneity in reproductive rates and cost of reproduction in a long‐lived vertebrate
Authors: Chambert Thierry , Rotella Jay J. , Higgs Megan D. , Garrott Robert A. 
Published: May 2013

AbstractIndividual variation in reproductive success is a key feature of evolution, but also has important implications for predicting population responses to variable environments. Although such individual variation in reproductive outcomes has been reported in numerous studies, most analyses to date have not considered whether these realized differences were due to latent individual heterogeneity in reproduction or merely random chance causing different outcomes among like individuals. Furthermore, latent heterogeneity in fitness components might be expressed differently in contrasted environmental conditions, an issue that has only rarely been investigated. Here, we assessed (i) the potential existence of latent individual heterogeneity and (ii) the nature of its expression (fixed vs. variable) in a population of female Weddell seals (Leptonychotes weddellii), using a hierarchical modeling approach on a 30‐year mark–recapture data set consisting of 954 individual encounter histories. We found strong support for the existence of latent individual heterogeneity in the population, with “robust” individuals expected to produce twice as many pups as “frail” individuals. Moreover, the expression of individual heterogeneity appeared consistent, with only mild evidence that it might be amplified when environmental conditions are severe. Finally, the explicit modeling of individual heterogeneity allowed us to detect a substantial cost of reproduction that was not evidenced when the heterogeneity was ignored.
Benzo[c]thiophene Chromophores Linked to Cationic Fe and Ru Derivatives for NLO Materials: Synthesis Characterization and Quadratic Hyperpolarizabilities
Authors: Silva Tiago J. L. , Mendes Paulo J. , Garcia M. Helena , Robalo M. Paula , Prates Ramalho J. P. , Palace Carvalho A. J. , Büchert Marina , Wittenburg Christian , Heck Jürgen 
Published: May 2013

Abstractη5‐Monocyclopentadienyliron(II)/ruthenium(II) complexes of the general formula [M(η5‐C5H5)(PP)(L1)][PF6] {M = Fe, PP = dppe; M = Ru, PP = dppe or 2PPh3; L1 = 5‐[3‐(thiophen‐2‐yl)benzo[c]thiophenyl]thiophene‐2‐carbonitrile} have been synthesized and studied to evaluate their molecular quadratic hyperpolarizabilities. The compounds were fully characterized by NMR, FTIR and UV/Vis spectroscopy and their electrochemical behaviour studied by cyclic voltammetry. Quadratic hyperpolarizabilities (β) were determined by hyper‐Rayleigh scattering measurements at a fundamental wavelength of 1500 nm. Density functional theory calculations were employed to rationalize the second‐order non‐linear optical properties of these complexes.
Optical and Electrical Properties of Hierarchical Nanostructured Al‐Doped ZnO Powders Prepared through a Mild Solution Route
Authors: Chen Ruiqiang , Zhu Pengli , Zhao Tao , Fu Xianzhu , Zhou Fengrui , Sun Rong 
Published: May 2013

AbstractHierarchical nanostructured Al‐doped ZnO (AZO) powders were successfully prepared through a mild solution route. The crystal structure and morphology of AZO were determined by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The morphology of the samples changed from random flower‐like nanostructures to uniform flower‐like hierarchical nanostructures with different Al doping contents. The optical and electrical properties of AZO were studied by UV/Vis spectroscopy and four‐point probe. The optical band gap of AZO increased initially but then decreased as the Al content was increased owing to the Burstein–Mass effect and the many‐body effect. Conversely, the electrical resistivity of the AZO powders first decreased and then increased with the Al doping content increasing because of changes in the electron and dopant concentrations. AZO exhibited the smallest electrical resistivity with an Al doping content of 1.0 at‐%, which is two orders of magnitude smaller than the electrical resistivity of ZnO.
Synthesis of [Cp′Fe(η3‐BH4)] and Its Conversion to [Cp′FeBH2]3
Authors: Maekawa Miyuki , Daniliuc Constantin G. , Jones Peter G. , Hohenberger Johannes , Sutter Jörg , Meyer Karsten , Walter Marc D. 
Published: May 2013

AbstractSalt metathesis of [Cp′FeI]2[1, Cp′ = η5‐1,2,4‐(Me3C)3C5H2] and NaBH4(2 equiv.) in tetrahydrofuran yields the low‐spin iron complex [Cp′Fe(η3‐BH4)] (2), which is thermally unstable and degrades slowly to the trimeric complex [Cp′FeBH2]3(3) and H2. Both molecules have been fully characterized by various spectroscopic techniques. An X‐ray structure analysis of3confirms its nature and reveals rather long B–B distances of 1.883(9) Å. DFT methods in combination with three complementary approaches [Wiberg bond indices (WBI), atoms in molecules (AIM) and compliance constants] have been used to explain the bonding in these iron(II) complexes. All methods predict a weak bonding interaction between the boron atoms in3.
CO Activation by (Diphosphane)platinum(0): Carbonate and Acetone Formation – Experimental and Mechanistic Study
Authors: Nicolas Emmanuel , Nocton Grégory , Mézailles Nicolas 
Published: May 2013

AbstractThe platinum(II) complex [(dcpp)Pt(C7H7)H] (1) [dcpp = 1,3‐bis(dicyclohexylphosphanyl)propane] reacts under 1 atm of CO to form the bis(carbonyl) complex of Pt0, [(dcpp)Pt(CO)2] (2). Complex2slowly crystallizes in toluene solution to form crystals of the Pt0dimer [(dcpp)(η1‐CO)Pt{μ‐C(O)}Pt(dcpp)] (3) in which one Pt atom is only three‐coordinated with the diphosphane dcpp and one μ‐C(O), while the other is coordinated in a tetrahedral arrangement with one μ‐C(O) and one η1‐CO. Complexes2and3were characterized in solution by31P NMR spectroscopy, and complex3readily reacts with O2to form the carbonate complex, [(dcpp)Pt(CO3)] (4). The reaction of the dimeric complex3with MeI allows the insertion of a methyl group into the carbonyl group to form the PtIIcomplex [(dcpp)Pt(C(O)Me)I] (5). Reaction of another equivalent of MeI with complex5leads to the formation and elimination of acetone and the bis(iodide) complex [(dcpp)PtI2] (6). X‐ray crystal structures of complexes3and4are reported along with DFT calculations and mechanistic studies of the formation of3,4,5, and6.
Periodate as an Oxidant for Catalytic Water Oxidation: Oxidation via Electron Transfer or O‐Atom Transfer?
Authors: Hetterscheid Dennis G. H. , Reek Joost N. H. 
Published: May 2013

AbstractTreatment of Ir(OH)2 with sodium periodate in aqueous solution results in formation of dioxygen following the rate law v = kobs[Ir]0.65[IO4]0.5, with kobs = 1.5 × 10–3 {Ir(OH)2 = [IrCp*(Me2NHC)(OH)2], where Me2NHC = N‐dimethylimidazolin‐2‐ylidene and Cp* = cyclopentadienyl}. In situ ESI‐MS experiments in combination with DFT calculations show that [IrIII(IO3)]+ and [IrV(=O)(IO3)]+ species are present in the reaction mixture. On the basis of the presence of these species, a mechanistic pathway was calculated illustrating that water is not necessarily the source of the oxygen. A low‐lying pathway exists wherein O2 production proceeds via two consecutive O‐atom‐transfer reactions from periodate to the catalyst. The resulting iodite ligand is further oxidized to close the catalytic cycle. The rate‐determining step in this process is formation of the O–O bond. For this transition a 21.8 kcal/mol barrier was found. This value fits very well with the observed turnover frequency of 0.27 s–1. Although it is difficult to prove that this is the dominant pathway, these data clearly illustrate that one has to be very careful with interpretation of catalytic results in periodate‐driven water oxidation reactions.
A Strictly Dinuclear MnIII–GdIII Complex: Synthesis and Magnetic Properties
Authors: Costes Jean‐Pierre , Tuchagues Jean‐Pierre , Vendier Laure , Garcia‐Tojal Javier 
Published: May 2013

AbstractA strictly heterodinuclear MnIII–Gd complex was prepared from a tripodal ligand and characterized by positive fast‐atom bombardment mass spectrometry, which evidenced replacement of a nitrato counterion by a monoethylcarbonato anion. Variable‐temperature direct current and alternating current studies confirm that the MnIII–Gd magnetic interaction is antiferromagnetic. Fitting of the magnetic susceptibility data yields an extremely weak interaction parameter JMnGd equal to –0.04 cm–1, along with a weak axial zero‐field splitting parameter DMn = 0.1 cm–1. This result confirms that a change in the manganese oxidation state, from MnII to MnIII, corresponds to a radical transformation of the magnetic behavior of Mn–Gd, from a ferromagnetic to an antiferromagnetic interaction. In accordance with the magnetic behavior of CoII–Gd complexes previously studied (high‐spin and low‐spin CoII ions), the observed magnetic behavior change may be explained by the difference in the electronic occupancy of the Mn 3d orbital, which is singly occupied for MnII and vacant for MnIII.
Fourth order finite volume solution to shallow water equations and applications
Authors: Erduran K. S. 
Published: May 2013

SUMMARYThis study presents the fourth order accurate finite volume solution to shallow water equations. Fourth order accuracy in space was provided by using the Monotone Upstream‐centered Schemes for Conservation Laws–Total Variation Diminishing scheme, whereas fourth order accurate solution in time was achieved by using the third order predictor scheme of Adams–Basforth followed by the fourth order corrector scheme of Adams–Moulton. The applicability and accuracy of the solution algorithm were explored on complex flow conditions. These flow conditions cover a theoretical well‐known partial two‐dimensional dam break problems and an experimental flow in a compound channel with or without a bridge. The applicability limits of the solution algorithm were discussed. The overall performance of the solution was found to be reasonably good. Copyright © 2013 John Wiley & Sons, Ltd.
Noble gas composition in rainwater and associated weather patterns
Authors: Warrier Rohit B. , Clara Castro M. , Hall Chris M. , Lohmann Kyger C. 
Published: May 2013

AbstractThis work represents the first comprehensive noble gas study in rainwater. It was carried out in southeast Michigan. Results show that all rainwater samples are in disequilibrium with surface conditions. Two noble gas patterns are identified. The first one, associated with low‐pressure systems, presence of fog and light rainfall, displays a relative Ar enrichment together with Ne, Kr, and Xe depletion. The second one, associated with the passage of frontal systems, displays a mass‐dependent depletion pattern. Precipitation is characterized by thunderstorms, heavy rainfall, and high cloud ceiling heights. A diffusion mass‐transfer model suggests that noble gas patterns originate from ice. Complete re‐equilibration with surface conditions should occur within hours. For the first time, this study establishes a direct correlation between the noble gas composition in rainwater and weather patterns and highlights their potential to identify timing and location of recharge in shallow aquifer systems where infiltration is rapid.
The Chemistry of PCR Primers: Concept and Application
Authors: Takei Fumie , Nakatani Kazuhiko 
Published: May 2013

AbstractDNA is a typical organic compound with marked differences from other chemicals and biopolymers because DNA can be amplified by the enzyme polymerase. DNA can be, in principle, amplified from a single copy by the polymerase chain reaction (PCR). In this review, we focus our attention on the chemistry of PCR primers. Because PCR is basic technology in biology research fields, we sometimes use chemically labeled primers without any awareness of the chemistry they leave behind. We would like to emphasize that chemically labeled primers contain a lot of potential for different chemistry ideas and much study is still necessary to advance PCR for single‐nucleotide polymorphism (SNP) typing, genetic diagnosis, and other fields. Two categories of primers, affinity‐capture primers and signaling primers, are discussed from the viewpoints of their chemical concepts and applications. Affinity‐capture primers are used for purification, isolation, and manipulation of PCR products by high specificity and affinity to the cognate molecules by moleculemolecule interactions, whereas signaling primers report the hybridization and/or progress of PCR amplification by a signal change, in most cases by a fluorescence change. The content of this review may be useful for a better understanding of the chemistry of PCR primers and, more importantly, for the invention of novel PCR chemistry.
IMPROVED EFFICIENCY OF IRRIGATION WATER USE: A SOUTH AFRICAN FRAMEWORK
Authors: Reinders Felix B , van der Stoep Isobel , Backeberg Gerhard R 
Published: May 2013

ABSTRACTIrrigated agriculture plays a major role in the livelihoods of nations all over the world and in South Africa it is not different. With the agricultural water use sector being the largest of all water use sectors in South Africa, there have been increased expectations that the sector should increase efficiency and reduce consumption in order to increase the amount of water available for other uses.In a recent study on irrigation efficiency, the approach is that irrigation efficiency should be assessed by applying a water balance to a specific situation rather than by calculating various performance indicators such as conveyance efficiency or application efficiency. Unfortunately the concept of irrigation efficiency is frequently misunderstood leading to the widespread belief that water just disappears with low irrigation efficiencies and re‐appears with improvements. The purpose of an irrigation system is to apply the desired amount of water, at the correct application rate and uniformly to the whole field, at the right time, with the least amount of non‐beneficial water consumption (losses), and as economically as possible. The fraction of the water abstracted from the source that can be utilised by the plant, can be called the beneficial water use component and optimised irrigation water supply is therefore aimed at maximising this component. It implies that water must be delivered from the source to the field both efficiently (with the least volume for production along the supply system) and effectively (at the right time, in the right quantity and at the right quality). Optimising water use at farm level requires careful consideration of the implications of decisions made during both development (planning and design), and management (operation and maintenance), taking into account technical, economic and environmental issues.The South African framework covers four levels of water management infrastructure: ‐the water source, bulk conveyance system, the irrigation scheme and the irrigation farm. The water balance approach can be applied at any level, within defined boundaries, or across all levels to assess performance within the whole Water Management Area. Copyright © 2013 John Wiley & Sons, Ltd.
Phosphorus characterization of manure composts and combined organic fertilizers by a sequential‐fractionation method
Authors: Takahashi Shigeru 
Published: May 2013

AbstractCharacterization of the forms of phosphorus (P) in organic soil amendments was conducted by sequential P fractionation. More than 60% of total P was inorganic P (Pi). The major Pi forms in the cattle‐manure composts were NaHCO3‐ and HCl‐extractable P fractions. HCl‐extractable Pi was the predominant P form and a considerable proportion of the total P was present in the HCl‐extractable organic P fraction in the poultry manure composts and combined organic fertilizers.
Climate‐strategic agriculture and the water‐soil‐waste nexus
Authors: Lal Rattan 
Published: May 2013

AbstractAdoption of input‐responsive varieties enhanced food production during the second half of the 20th century. However, even bigger challenges lie ahead because of the growing societal demands. For example, the global population of 7.2 billion in 2013 is projected to reach 9.2 billion by 2050 and stabilize at 10 billion by 2100. The growing and increasingly affluent population, with preference towards more and more meat‐based diet, is likely to jeopardize the finite, fragile, and dwindling soil and water resources which are already under great stress in densely populated countries in Asia and elsewhere. Economic growth and increase in gross domestic product also lead to generation of waste or by‐products, along with contamination and eutrophication of water resources. International trade in food/feed products also involves transfer of virtual water, which is a serious issue when water‐scarce countries export virtual water to water‐endowed countries. The problem is confounded by the present and future climate change driven by the growing energy demands of the carbon civilization. Thus, adaptation to climate change represents both a threat and an opportunity for sustainable development. Adaptive strategies must be sustainable socially and environmentally and advance the Millennium Development Goals, while buffering agroecosystems against extreme climate events (e.g., pedologic, agronomic, and ecologic drought). Thus, recognizing and addressing the water‐soil‐waste nexus is important to achieving climate‐strategic agriculture. Sustainable intensification of agroecosystems, producing more per unit consumption of essential resources, must consider judicious management of hydrological and biogeochemical cycles (C, N, P, S). The soil C pool must be managed and enhanced to offset anthropogenic emissions, and mitigate/adapt to the climate change. The pace of adoption of recommended land use and soil‐/plant‐/animal‐management practices can be kept at par with advances in scientific knowledge through continuous dialogue between scientists on the one hand and policy makers / land managers on the other to translate research data into policy and action plans.
Does Corporate Social Responsibility Hit the Mark? A Stakeholder Oriented Methodology for CSR Assessment
Authors: Calabrese Armando , Costa Roberta , Menichini Tamara , Rosati Francesco 
Published: May 2013

Is corporate social responsibility (CSR) commitment effectively disclosed through a company's sustainably report? Moreover, in what measure is a company's CSR commitment really acknowledged by its stakeholders? Because it has been observed that stakeholders' recognition of a company's social and environmental conduct highly impacts the business returns of CSR initiatives, it is therefore not surprising that measurement of the stakeholder perception is a key issue for CSR assessment.In this paper, we propose a method enabling companies to evaluate the effectiveness of their CSR policies both in terms of disclosure and capacity to fulfill both stakeholder social and environmental expectations. The method we propose compares, through a gap analysis, three measures as follows: the company commitment disclosed through its sustainability report, the company CSR commitment perceived by its stakeholders, and the CSR commitment that stakeholders require to the company. The outcome of the proposed methodology provides managerial insights for evaluating the effectiveness of ongoing CSR practices and for formulating CSR strategies. An application illustrates the use of the methodology in practice. Copyright © 2013 John Wiley & Sons, Ltd.