bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mixed Magnetism for Refrigeration and Energy Conversion
Authors: Dung Nguyen H. , Ou Zhi Qiang , Caron Luana , Zhang Lian , Thanh Dinh T. Cam , de Wijs Gilles A. , de Groot Rob A. , Buschow K. H. Jürgen , Brück Ekkes 
Published: September 2011

AbstractThe efficient coupling between lattice degrees of freedom and spin degrees of freedom in magnetic materials can be used for refrigeration and energy conversion. This coupling is enhanced in materials exhibiting the giant magnetocaloric effect. First principle electronic structure calculations on hexagonal MnFe(P, Si) reveal a new form of magnetism: the coexistence of strong and weak magnetism in alternate atomic layers. The weak magnetism of Fe layers (disappearance of local magnetic moments at the Curie temperature) is responsible for a strong coupling with the crystal lattice while the strong magnetism in adjacent Mn‐layers ensures Curie temperatures high enough to enable operation at and above room temperature. Varying the composition on these magnetic sublattices gives a handle to tune the working temperature and to achieve a strong reduction of the undesired thermal hysteresis. In this way we design novel materials based on abundantly available elements with properties matched to the requirements of an efficient refrigeration or energy‐conversion cycle.
Farmgate Private Standards and Price Premium: Evidence From the GlobalGAP Scheme in Kenya's French Beans Marketing
Authors: Kariuki Isaac Maina , Loy Jens‐Peter , Herzfeld Thomas 
Published: September 2011

ABSTRACTThe proliferation of private quality and assurance schemes in international trade is defining market access in high value chains. The prime concern for small‐scale producers is whether price premiums are realizable due to compliance. Using French beans marketing, the authors find that GlobalGAP certification, produce traceability, number of suppliers, competition for supplies, direct procurement, a good road network, and supply contracts have positive farmgate price effects for smallholders. Potential policy implications are drawn.
Sol–gel derived Si/C/O/N‐materials: molecular model compounds, xerogels and porous ceramics
Authors: Cheng Hui‐Jie , Lippe Katrin , Kroke Edwin , Wagler Jörg , Fester Gerrit W. , Li Ya‐Li , Schwarz Marcus R. , Saplinova Tatyana , Herkenhoff Stefanie , Ischenko Vladislav , Woltersdorf Jörg 
Published: September 2011

AbstractPolymeric Si/C/O/N xerogels, with the idealized polymer network structure comprising [SiOSi(NCN)3]n moieties, were prepared by reactions of hexachlorodisiloxane (Cl3SiOSiCl3) with bis(trimethylsilyl)carbodiimide (Me3SiNCNSiMe3, BTSC). NMR and FTIR spectra indicate the existence of ‐NCN‐ andSiOSi‐ units in the xerogels and also in the ceramic materials obtained upon pyrolysis. The feasibility of this reaction protocol was confirmed on the molecular level by the deliberate synthesis of the macrocyclic compound [SiPh2OSiPh2(NCN)]2, the crystal structure and spectroscopic data of which are reported. The influence of pyridine as a catalyst for the cross‐linking reaction was studied. The degree of cross‐linking increased within the polymers with the addition of pyridine. It was shown by the reaction of hexachlorodisiloxane with excess pyridine that the latter appears to activate only one out of the two ‐SiCl3 moieties under formation of hexacoordinated silicon compounds. The crystal structure of Cl3SiOSiCl3(pyridine)2 is presented. Quantum chemical calculations are in support of this adduct being a potential intermediate in the pyridine catalyzed sol–gel process. The ceramic yield after pyrolysis of the Si/C/O/N‐xerogels at 1000 °C, which reaches values up to 50%, was found to depend on the aging protocol (time, temperature), whereas no correlation was found with the amount of pyridine added for xerogel synthesis. The Si/C/N/O‐ceramics obtained after pyrolysis at 1000 °C under NH3 are completely amorphous. Chemically they have to be considered as hybrids between an ideal [SiOSi(NCN)3]n network and glass‐like Si2N2O. The products are mesoporous with closed pores and a broad pore size distribution. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis of novel bipyridyl ligands and application in preparation of polyketone
Authors: Guo Jintang , Gao Shan , Lv Zhenhui , Ye Yaqin 
Published: September 2011

AbstractIn this article, novel 2,2′‐bipyridyl derivatives were synthesized and the excellent bipyridyl ligands were chosen as catalyst to apply in the copolymerization of carbon monoxide (CO) and styrene (ST) to prepare polyketone. 4,4′‐Dicarboxyl‐2,2′‐bipyridine(4,4′‐dcpy) was synthesized by use of synthesized 4,4′‐dimethyl‐2,2′‐bipyridine(4,4′‐dmpy). The products (4,4′‐dmpy and 4,4′‐dcpy) were characterized by melting point, NMR, IR, GC‐MS, and elemental analysis. The effects of different ligands and various reaction conditions incuding the usage of ligand, p‐toluenesulfonic acid, solvent, p‐benzoquinone, the CO pressure, and reaction temperature on catalytic activity of the copolymerization were investigated. The catalytic activity of 4,4′‐dmpy, 4,4′‐dcpy and 2,2′‐bipyridine were compared. The results showed that the addition of the electron‐donating substituent can enhance catalytic activity, with the sequence as follows: 4,4′‐ dimethyl‐2,2′‐bipyridine > 2,2′‐bipyridine > 4, 4′‐carboxy 2,2′‐ bipyridine. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2012
Deoxycholate‐chitosan nanospheres fabricated by γ‐irradiation and chemical modification: Nanoscale synthesis and controlled studies
Authors: Pasanphan Wanvimol , Choofong Surakarn , Rimdusit Pakjira 
Published: September 2011

AbstractA systematic protocol to fabricate self‐assembly deoxycholate‐chitosan nanospheres (DC‐CsNS) by γ‐ray pre‐irradiation and chemical modification was studied. Hydrophobic deoxycholic acid moieties were chemically conjugated to pre‐irradiated chitosan. The influences of chitosan physical forms (i.e., colloid and flake) during irradiation, radiation doses, and the reaction system (heterogeneous or homogeneous) on the chemical modification and the particle shape and size were investigated. Pre‐irradiation of chitosan in colloidal form produced smaller DC‐CsNS particle size than that of flake form. In the heterogeneous reaction, the pre‐irradiated dose influenced the DC‐CsNS particle size, whereas in the homogeneous reaction all pre‐irradiation doses gave an identical average size range of 30–50 nm. By pre‐irradiation (10 kGy) of chitosan in colloidal form before heterogeneous chemical conjugation, it is possible to obtain DC‐CsNS with an average size of 46 nm. DC‐CsNS of about 50 nm in size could also be synthesized using homogeneous chemical conjugation onto non‐irradiated chitosan with the addition of N‐hydroxysuccinimide (NHS). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A functional monomer to synthesize sulfonated poly(ether ether ketone) with sulfonic acid group in the pendant side chain
Authors: Krishnan Palanichamy , Advani Suresh G. , Prasad Ajay K. 
Published: September 2011

AbstractA functional monomer which enables the synthesis of sulfonated poly(ether ether ketone) (SPEEK) polymer with the sulfonic acid group in the pendant side chain has been successfully developed. 1, 3‐propane sultone was used as the model compound to introduce the side chain moiety in the monomer. The above sulfonated monomer (0.50 mol) along with 4, 4′‐difluorobenzophenone (0.50 mol) were reacted with bisphenol‐A (1.0 mol) to obtain the SPEEK polymer with the sulfonic acid group in the pendant side chain. All the intermediates and the SPEEK polymer were characterized using 1H‐NMR. The SPEEK polymer is expected to have improved mechanical and electrical properties for PEM fuel cell application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of montmorillonite on orientation of drawn polypropylene films
Authors: Zhou Bing , Liu Yi‐Liao , Xu Jun‐Ting , Fan Zhi‐Qiang 
Published: September 2011

AbstractFilms of polypropylene/organically modified montmorillonite (PP/OMMT) nanocomposites were drawn at two different temperatures with various draw ratios. The effect of OMMT on the orientations of the crystalline and amorphous phases was studied using polarized infrared spectroscopy. It is found that OMMT layers always retard the orientation of the crystalline phase. The higher the OMMT loading, the stronger the retardance effect. In contrast, the effect of OMMT layers on the orientation of the amorphous phase depends on draw temperature and OMMT loading. A favorable effect on the orientation of the amorphous phase is observed at low OMMT loading and high draw temperature, but the retardance prevails at high OMMT loading and low draw temperature. The favorable effect on orientation at high draw temperature is attributed to the stabilization effect of OMMT layers on the conformation of amorphous PP chains. Such an effect was further verified by comparing the crystallization behavior and the morphologies of drawn PP and PP/OMMT films crystallized from 180°C. Memory effect is observed for crystallization of drawn PP/OMMT film, but it is not obvious for the drawn film of neat PP. Spherulites are formed for orientated neat PP films cooled from 180°C, but cylindrites are still formed after the drawn PP/OMMT films undergo melting at 180°C and recrystallization. The stabilization effect disappears at higher temperature (230°C). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Implicit “Motion” in Non‐verbal Art: Transmission and Transformation of Affect
Authors: Rose Gilbert J. 
Published: September 2011

ABSTRACTThis paper traces (1) the transformation of the subjective affective expressiveness that accompanies the making of non‐verbal art into (2) the aesthetic forms that embody implicit “motion” (3) that stimulates an immediate disparate affective response on the part of a person sensitive to art or music. Implicit “motion” reflects primary process forms interplaying with the slow discharge of secondary process, thus allowing entry into consciousness. Any cognitive meanings, conscious and unconscious, subsequently attributed to the non‐verbal art are personal, variable and subject to the flow oftime and the spirit of the times. Copyright © 2011 John Wiley & Sons, Ltd.
Balancing on the Borderline – a Low‐cost Approach to Visualize the Red‐edge Shift for the Benefit of Aerial Archaeology
Authors: Verhoeven Geert , Doneus Michael 
Published: September 2011

ABSTRACTScientists from different research disciplines have provided essential information that relates the biophysical characteristics of plants to their spectral reflectance. This fundamental understanding has facilitated the development of various non‐destructive sensing methods for detecting vegetation stresses, monitoring plant growth and calculating crop yield. Aerial archaeologists flying in small aeroplanes have only partially exploited this knowledge. Instead of basing archaeological interpretation on only direct visual inspection of the conventionally acquired colour photographs, this contribution briefly reviews the reflectance properties of plants and uses them to present a new low‐cost imaging technique beneficial for the detection of (faint) archaeologically induced vegetation marks. The new approach consists of three simultaneously operated digital still cameras, each of them capturing information in a different spectral waveband: the visible, near‐infrared and red‐edge spectral region. The latter two bands are used in the calculation of a R700/R800 vegetation index. Besides a theoretical underpinning, real‐world examples will assess the potential of this new approach in detection of vegetation marks and prove that this low‐cost, multispectral method might be beneficial in identifying and enhancing weak crop stresses that are lost when taking only the broad visible spectrum into account. In the final discussion, some thoughts on future archaeological aerial research are given. Copyright © 2011 John Wiley & Sons, Ltd.
Verbal problem‐solving in autism spectrum disorders: A problem of plan construction?
Authors: Alderson‐Day Ben 
Published: September 2011

AbstractChildren with autism spectrum disorders (ASD) adopt less efficient strategies than typically developing controls (TD) on verbal problem‐solving tests such as the Twenty Questions Task. This study examined the hypotheses that this can be explained by differences in (i) planning processes or (ii) selective attention. Twenty‐two children with ASD and 21 TD controls matched for age (Mage = 13:7) and cognitive ability (MFSIQ = 96.42) were tested on an adapted version of Twenty Questions and two planning tasks. ASD participants could recognize effective questions as well as TD participants on a forced‐choice question discrimination task, but were observed to construct plans that were significantly less efficient. ASD performance was also specifically reduced when items could not be physically removed from the testing array, although this effect could be ameliorated by keeping a written record of participant questions during search. These findings indicate that ASD participants are sensitive to the within‐task executive demands of Twenty Questions, but that their inefficiency in strategy relates to planning processes and question selection pretask. The implications for understanding ASD problem‐solving skills and their impact on everyday functioning are discussed. Autism Res 2011,4:401–411. © 2011 International Society for Autism Research, Wiley Periodicals, Inc.
Superresolution imaging of biological nanostructures by spectral precision distance microscopy
Authors: Cremer Christoph , Kaufmann Rainer , Gunkel Manuel , Pres Sebastian , Weiland Yanina , Müller Patrick , Ruckelshausen Thomas , Lemmer Paul , Geiger Fania , Degenhard Sven , Wege Christina , Lemmermann Niels A. W. , Holtappels Rafaela , Strickfaden Hilmar , Hausmann Michael 
Published: September 2011

AbstractFor the improved understanding of biological systems on the nanoscale, it is necessary to enhance the resolution of light microscopy in the visible wavelength range beyond the limits of conventional epifluorescence microscopy (optical resolution of about 200 nm laterally, 600 nm axially). Recently, various far‐field methods have been developed allowing a substantial increase of resolution (“superresolution microscopy”, or “lightoptical nanoscopy”). This opens an avenue to ‘nano‐image’ intact and even living cells, as well as other biostructures like viruses, down to the molecular detail. Thus, it is possible to combine light optical spatial nanoscale information with ultrastructure analyses and the molecular interaction information provided by molecular cell biology. In this review, we describe the principles of spectrally assigned localization microscopy (SALM) of biological nanostructures, focusing on a special SALM approach, spectral precision distance/position determination microscopy (SPDM) with physically modified fluorochromes (SPDMPhymod. Generally, this SPDM method is based on high‐precision localization of fluorescent molecules, which can be discriminated using reversibly bleached states of the fluorophores for their optical isolation. A variety of application examples is presented, ranging from superresolution microscopy of membrane and cytoplasmic protein distribution to dual‐color SPDM of nuclear proteins. At present, we can achieve an optical resolution of cellular structures down to the 20‐nm range, with best values around 5 nm (∼1/100 of the exciting wavelength).
Enhancing the 3‐hydroxyvalerate component in bioplastic PHBV production by Cupriavidus necator
Authors: Berezina Nathalie 
Published: September 2011

AbstractIn the current context of global warming, the substitution of conventional plastics with bioplastics is a challenge. To take up this challenge, we must meet different technical and economic constraints. In the case of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), the technical properties can be modulated by varying the 3‐hydroxyvalerate content. 3‐Hydroxyvalerate (3‐HV) enhancement is an issue; therefore, simultaneous evaluation of several 3‐hydroxyvalerate‐enhancing substrates through fractional factorial design of experiments is described. Eight substrates citric, valeric, propionic, and levulinic acids; propanol; pentanol; and sodium propionate were studied for 3‐HV enhancement, and sodium glutamate was studied for biomass and polyhydroxyalkanoate (PHA) enhancement. The most efficient 3‐hydroxyvalerate‐enhancing factors were levulinic acid, sodium propionate, and pentanol; however, pentanol, at a concentration of 1 g/L, had an extremely negative influence on biomass production and the PHA content of cells. The effect of the inoculum nutrient composition on the final 3‐HVcontent was also evaluated. These results showed that the most efficient combination for the production of high 3‐HVcontent in PHBV was primary inoculum growth on mineral medium followed by fermentation for 48 h with levulinic acid and sodium propionate (at 1 g/L) as the only carbon sources. This allowed us to produce PHBV with a 3‐HVcontent of 80 mol % and overall volumetric and specific productivities of 2 mg/L/h and 3.9 mg/gCDW/h, respectively, with the addition of only 2 g/L of inducing substances.
Correlation of second virial coefficient with solubility for proteins in salt solutions
Authors: Mehta Chirag M. , White Edward T. , Litster James D. 
Published: September 2011

AbstractIn this work, osmotic second virial coefficients (B22) were determined and correlated with the measured solubilities for the proteins, α‐amylase, ovalbumin, and lysozyme. The B22 values and solubilities were determined in similar solution conditions using two salts, sodium chloride and ammonium sulfate in an acidic pH range. An overall decrease in the solubility of the proteins (salting out) was observed at high concentrations of ammonium sulfate and sodium chloride solutions. However, for α‐amylase, salting‐in behavior was also observed in low concentration sodium chloride solutions. In ammonium sulfate solutions, the B22 are small and close to zero below 2.4 M. As the ammonium sulfate concentrations were further increased, B22 values decreased for all systems studied. The effect of sodium chloride on B22 varies with concentration, solution pH, and the type of protein studied. Theoretical models show a reasonable fit to the experimental derived data of B22 and solubility. B22 is also directly proportional to the logarithm of the solubility values for individual proteins in salt solutions, so the log‐linear empirical models developed in this work can also be used to rapidly predict solubility and B22 values for given protein–salt systems. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Sterically Demanding Hetero‐Substituted [2]Borametallocenophanes of Group IV Metals: Synthesis, Structure and Reactivity
Authors: Braunschweig Holger , Dörfler Rainer , Mies Jan , Oechsner Andreas 
Published: September 2011

AbstractWe report the synthesis and characterisation of unprecedented unstrained [2]diborametallocenophanes of zirconium and hafnium that bear the bulky octamethylfluorenyl (η5‐C29H36) system, the proligands of which were pre‐constructed by a two‐step synthesis. The compounds were fully characterised by NMR spectroscopy, MALDI‐TOF mass spectrometry and X‐ray diffraction analysis. Typical reactivities relevant to olefin polymerisation such as methylation and chloride abstraction were also investigated. Finally, a sterically demanding bis(octamethylfluorenyl) metallocene was prepared.
Oxidation State Changes and Electron Flow in Enzymatic Catalysis and Electrocatalysis through Wannier‐Function Analysis
Authors: Sit Patrick H.‐L. , Zipoli Federico , Chen Jia , Car Roberto , Cohen Morrel H. , Selloni Annabella 
Published: September 2011

AbstractIn catalysis by metalloenzymes and in electrocatalysis by clusters related in structure and composition to the active components of such enzymes transition‐metal atoms can play a central role in the catalyzed redox reactions. Changes to their oxidation states (OSs) are critical for understanding the reactions. The OS is a local property and we introduce a new, generally useful local method for determining OSs, their changes, and the associated bonding changes and electron flow. The method is based on computing optimally localized orbitals (OLOs). With this method, we analyze two cases, superoxide reductase (SOR) and a proposed hydrogen‐producing model electrocatalyst [FeS2]/[FeFe]P, a modification of the active site of the diiron hydrogenase enzymes. Both utilize an under‐coordinated Fe site where a one‐electron reduction (for SOR) or a two‐electron reduction (for [FeFe]P) of the substrate occurs. We obtain the oxidation states of the Fe atoms and of their critical ligands, the changes of the bonds to those ligands, and the electron flow during the catalytic cycle, thereby demonstrating that OLOs constitute a powerful interpretive tool for unraveling reaction mechanisms by first‐principles computations.
Highly Luminescent Octanuclear AuI–CuI Clusters Adopting Two Structural Motifs: The Effect of Aliphatic Alkynyl Ligands
Authors: Koshevoy Igor O. , Lin Chia‐Li , Karttunen Antti J. , Jänis Janne , Haukka Matti , Tunik Sergey P. , Chou Pi‐Tai , Pakkanen Tapani A. 
Published: September 2011

AbstractReactions of the homoleptic (AuC2R)n precursors with stoichiometric amount of diphosphine ligand PPh2C6H4PPh2 (P^P) and Cu+ ions lead to an assembly of a new family of bimetallic clusters [Au6Cu2(C2R)6(P^P)2]2+ (type I; R=9‐fluorenolyl (1), diphenylmethanolyl (2), 2,6‐dimethyl‐4‐heptanolyl (3), 1‐cyclohexanolyl (4), Cy (5), tBu (6)). In the case of R=1‐cyclohexanolyl, a structurally different complex [Au6Cu2(C2C6H11O)6(P^P)3]2+ (7, type II) could be obtained by treatment of 4 with one equivalent of the diphosphine, while for R=isopropanolyl only the latter type of cluster [Au6Cu2(C2C3H7O)6(P^P)3]2+ (8) was detected. Steric bulkiness of the alkynyl ligands and O⋅⋅⋅HO hydrogen bonding are suggested to play an important role in stabilizing the type I and type II cluster structural motif, respectively. All the complexes exhibit intense photoluminescence in solution with emission parameters that depending on the geometrical arrangement of the octanuclear metal core. The clusters 1–4 and 6 show single emission band in a blue region (469–488 nm) with maximum quantum yield of 94 % (4), while structurally different 7 and 8 emit yellow‐orange (590 nm) with unity quantum efficiency. The theoretical DFT calculations of the electronic structures have been carried out to demonstrate that the metal‐centered triplet emission within the heterometallic core plays a key role for the observed phosphorescence.