bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and electrochemical characterization of sulfonated polysulfone cation‐exchange membranes: Effects of the solvents on the degree of sulfonation
Authors: Nagarale R. K. , Gohil G. S. , Shahi Vinod K. , Rangarajan R. 
Published: April 2005

AbstractSulfonated polysulfone cation‐exchange membranes with various degrees of sulfonation were prepared by a treatment with chlorosulfonic acid in different solvents of various polarities, and the effect of the solvent polarity on the degree of sulfonation was explored. These membranes were characterized by their ion‐exchange capacity, volume fraction of water, and electrochemical properties. The counterion transport numbers, permselectivity, and fixed charge densities of these membranes were estimated from membrane potential data and varied with the degree of sulfonation, concentration, and external salt concentration. The counterion mobility in the membrane phase was also estimated from membrane conductance measurements. These membrane were found to have good electrochemical properties and are suitable for various types of electromembrane processes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2344–2351, 2005
Synthetic Approaches to Sterically Hindered N‐Arylimidazoles through Copper‐Catalyzed Coupling Reactions
Authors: Alcalde Ermitas , Dinarès Immaculada , Rodríguez Sandra , Garcia de Miguel Cristina 
Published: April 2005

AbstractOptimization studies allowed the efficient synthesis of a simple structural motif based on meta‐bis(1‐imidazolyl)benzenes 1 through copper‐catalyzed coupling of 1,3‐diiodobenzene and imidazole under mild reaction conditions. This protocol was then used to prepare a representative sterically hindered N‐arylimidazole 2a, the most common structural motif among N‐heterocyclic carbenes (NHC). Having optimized the main variables governing CuI‐catalyzed imidazole N‐arylation, the first Ullmann‐type synthesis of N‐mesitylimidazole (2a) is reported. Moreover, the coupling between boronic acids as the aryl donor partners and either imidazole or benzimidazole was examined; in all cases the reactions proceeded in very low yield. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
NMR Spectroscopic and Molecular Modelling Studies on Cyclodextrin–Dipeptide Inclusion Complexes
Authors: Kahle Claudia , Deubner Ralph , Schollmayer Curd , Scheiber Josef , Baumann Knut , Holzgrabe Ulrike 
Published: April 2005

AbstractCyclodextrins (CDs) are often used to separate the enantiomers of chiral drugs by HPLC, GC, and capillary electrophoresis (CE). For dipeptides containing one aromatic amino acid, a reversal of the migration order is observed in CE upon increasing the pH value of the background electrolyte from 2.5 to 3.5. In order to understand the mechanism of chiral recognition of this phenomenon, NMR experiments, namely complexation‐induced chemical shifts (CICS) and ROESY, were performed. Comparing the CICSs obtained for the pairs Diac‐β‐CD/Ala‐Phe and HDAS‐β‐CD/Ala‐Phe and Diac‐β‐CD/Ala‐Tyr and HDAS‐β‐CD/Ala‐Tyr revealed very small changes, thereby indicating a rather weak interaction of the respective guest molecules with their host. The CICS for β‐CD and HS‐β‐CD confirmed an inclusion of the aromatic moiety into the CD cavity. It is shown that, at pH 2.5, the D,D‐enantiomer of Ala‐Tyr immerses deeper into the cavity of β‐cyclodextrin than the L,L‐enantiomer, and this was subsequently confirmed by molecular dynamics simulations. Furthermore, at pH 3.5 the immersion is shallower, as shown by the 1H and ROESY NMR findings and confirmed by the molecular dynamics simulations. The immersion depths of the dipeptides were calculated by defining a plane in the cavity to gain information about the different behaviour of the studied chemical species. The employed procedure is easily generalised to other host‐guest complexes and is expected to improve data evaluation in other cases, too. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
An Efficient Asymmetric Synthesis of 2‐Substituted 1,4‐Benzodiazepin‐3‐one as a Potential Molecular Scaffold
Authors: Cabedo Nuria , Pannecoucke Xavier , Quirion Jean‐Charles 
Published: April 2005

Abstract2‐Substituted 1,4‐benzodiazepine‐2‐one compounds (9–12) were obtained by a highly diastereoselective alkylation of a seven‐membered ring benzolactam (8) in the presence of (R)‐phenylglycinol as a chiral inductor. The corresponding acid derivative (16) afforded a conformationally constrained structure suitable for preparing peptidomimetic analogues useful as a novel molecular scaffold. After cleavage of the chiral appendage this approach might also lead efficiently to enantiomerically pure 2‐substituted benzodiazepines (15). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Dipyridoimidazolium Salt from Phenylchlorocarbene and 2,2'‐Bipyridyl: Synthesis, Reaction Mechanism, and Effect of Rotamerism
Authors: Bonneau Roland , Liu Michael T. H. 
Published: April 2005

AbstractPhenylchlorocarbene, generated by photolysis or thermolysis of the phenylchlorodiazirine, reacts with 2,2'‐bipyridyl to give, in alkane solvents, the 6‐phenyldipyrido[1,2‐c:2',1'‐e]imidazolium chloride. We investigated the mechanism of the reaction by flash photolysis. Like the mechanism of formation of 3‐phenylindolizine from phenylchlorocarbene + 2‐vinylpyridine, the process involves generation of the carbene, formation of a pyridinium ylide, and cyclization of the syn rotamer of this ylide, with the two N atoms of the bipyridyl in a syn relationship. The cyclization product then eliminates Cl– to give a stable aromatic cation. We observed and identified all the intermediate species and measured the rate constants for the successive elementary reactions. This enabled us to define experimental conditions under which the reaction is nearly quantitative (the chemical yield of isolated product is >90 %). By contrast, use of a polar solvent such as dichloromethane yields a mixture of the products resulting from the cyclization of both the syn‐ and the anti‐bipyridylium ylide rotamers. Semiempirical calculations qualitatively account for the effect of solvent polarity on the relative rates of cyclization of the syn‐ and anti‐bipyridylium ylide rotamers and thus on the nature of the products. These calculations predict that, in the presence of o‐phenanthroline, a model for the syn bipyridyl rotamer, phenylchlorocarbene should not give the expected diazacyclopentaphenanthrene, in agreement with the experiment findings. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Thio‐ and Dithioesters as Dipolarophiles in Reactions with Thiocarbonyl Ylides
Authors: Urbaniak Katarzyna , Mloston Grzegorz , Gulea Mihaela , Masson Serge , Linden Anthony , Heimgartner Heinz 
Published: April 2005

AbstractThe thiocarbonyl S‐methylides 3a–c, generated in situ by thermal decomposition of the corresponding 2,5‐dihydro‐1,3,4‐thiadiazoles, undergo [3+2] cycloadditions with diphenyl trithiocarbonate (5a) to give 1,3‐dithiolanes. The regioselectivity of the reaction of the cycloaliphatic dipoles 3b and 3c is reversed in comparison with that of the aromatic 3a. A mixture of both regioisomeric cycloadducts is formed in the reaction between 3b and methyl dithiobenzoate (6a), whereas only one regioisomer is obtained with thiophthalide (7). Dialkyl phosphonodithioformates 8 are shown to be efficient C=S dipolarophiles in reactions with thiocarbonyl S‐methylides 3a–3d, affording 1,3‐dithiolane‐4‐phosphonates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Conformation‐Directed Macrocyclization Reactions
Authors: Blankenstein Jörg , Zhu Jieping 
Published: April 2005

AbstractThe importance of conformational pre‐organization in successful macrocyclization reactions has been recognized ever since Eschenmoser’s synthesis of vitamin B12 and Woodward’s synthesis of erythromycin. Different approaches to productive preorganization are possible depending mainly on the degree of freedom in the choice of the structural elements. In diversity‐oriented synthesis, in which it is not imperative that the molecular framework has a fixed structure, matching building blocks can be used to assemble a macrocycle. In target‐oriented synthesis, more subtle structural elements have to be considered in order to pre‐organize the linear substrate into a folded conformer suitable for ring closure. In this microreview, some selected examples of macrocyclization reactions are presented to illustrate the different rational approaches. Special attention is paid to the role of intramolecular weak forces and protecting groups in the conformational pre‐organization that facilitates macrocyclization reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cycloadditions and Methylene Transfer in Reactions of Substituted Thiocarbonyl S‐Methylides with Thiobenzophenone: A Computational Study
Authors: Sustmann Reiner , Sicking Willi , Huisgen Rolf 
Published: April 2005

AbstractRegiochemistry and methylene transfer reactions in cycloadditions of aliphatic thiocarbonyl S‐methylides and thiobenzophenone are analyzed by ab initio [(U)HF/3‐21G*] and DFT calculations [(U)B3LYP/6‐31G*//(U)HF/3‐21G* and (U)B3LYP/6‐31G*]. The formation of regioisomeric 1,3‐dithiolanes is explained by the competition of concerted (2,4‐substituted 1,3‐dithiolane) and stepwise cycloaddition via C,C‐biradicals (4,5‐substituted 1,3‐dithiolane). Aliphatic thiocarbonyl S‐methylides with sterically demanding substituents undergo substantial methylene transfer in the reaction with thiobenzophenone. This process involves dissociation of the C,C‐biradical intermediate with liberation of thiobenzophenone S‐methylide which, in turn, combines with a second molecule of thiobenzophenone. Calculated activation parameters for the different processes are in agreement with the experimental observations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Novel [6]‐ and [7]Helicene‐Like Quinones via Mono‐ and Bidirectional Chromium‐Templated Benzannulation of Bridged Binaphthyl Carbene Complexes
Authors: Schneider Jochen F. , Nieger Martin , Nättinen Kalle , Lewall Burhanshah , Niecke Edgar , Dötz Karl Heinz 
Published: April 2005

AbstractA new organometallic approach to novel, functionalised, helicene‐like quinones and bisquinones has been developed based on the chromium‐templated [3+2+1] benzannulation reaction. The [5]helicene‐analogous monocarbene chromium complexes 4, 5, 17 and 19, derived from dibromo‐substituted methylene‐ or silylene‐tethered binaphthols 2 and 3, react with various alkynes to give [6]helicene‐like quinones 6–13 and 20–29 after oxidative work‐up. A rare competition of angular vs. linear annulation is observed for the incorporation of phenylacetylene that affords quinones 21/22 and 28/29. Protection of the phenolic benzannulation product with camphanic acid chloride 14, followed by chromatographic separation, provides access to enantiopure [6]helicene‐like derivatives. Bidirectional benzannulation of helical biscarbene complexes 16 and 18 results in bisangular and angular‐linear bisquinones 30–36 after oxidative work‐up. X‐ray crystal structures of the heterocyclic [5]‐, [6]‐ and [7]helicene‐derivatives and the angular‐linear annulation products indicate an increasing distortion of the helical framework with progressive annulation. The CD spectra of the methylene‐tethered biaryls (3, 9, 14, 36) reflect the different interactions between the aryl chromophores; cyclovoltammetric studies of bisangular bisquinones 30 and 33 reveal three reversible, one‐electron reduction steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Growth Tolerance of Rhizobia Isolated from Sand Dune Legumes of the Southwest Coast of India
Authors: Arun A. B. , Sridhar K. R. 
Published: April 2005

AbstractThis paper describes the properties of rhizobia from extreme soil environments which are characterized by high temperatures, salt concentrations and also rather extreme pH values due to the contamination by spray water from the sea. Coastal sand dunes are such extreme habitats which support a variety of microorganisms. To explore stress‐tolerant rhizobia, ten rhizobial strains were isolated from five wild legumes from two dune systems of the southwest coast of India. They were tested for growth performance or tolerance at a wide range of temperatures (30–55 °C), salinity (0.1–4.5 % w/v) and initial pH values (3.5–11). Growth of five isolates was highest between 30–40 °C, while four isolates showed considerable growth up to 2.5 % salinity (at 35 °C). All isolates demonstrated elevated growth at an initial pH of between 5–6 (at 35 °C and 2 % salinity), while five isolates had additional growth peaks at an initial pH of between pH 7.5–9 indicating alkaline tolerance and were suitable for efficient phosphate solubilization. The stress tolerance traits of these rhizobia are of potential value for strain improvement in agriculture or the bioremediation of soils at elevated temperatures, salinity and extreme pH values, and thus are of high biotechnological importance.
Transformation of Recalcitrant Melon (Cucumis melo L.) Cultivars is Facilitated by Wounding with Carborundum
Authors: Çürük S. , Çetiner S. , Elman C. , Xia X. , Wang Y. , Yeheskel A. , Zilberstein L. , Perl‐Treves R. , Watad A. A. , Gaba V. 
Published: April 2005

AbstractTransformation of the recalcitrant melon (Cucumis melo L.) cultivars Kιrkağaç 637 and Noi Yarok was accomplished by wounding cotyledon explants by vortexing with carborundum prior to inoculation with Agrobacterium tumefaciens. The addition of silver nitrate to the regeneration‐selection medium reduced the transformation efficiency, as the percentage of the explants forming putative transgenic calli and bud‐like protuberances was decreased and no transgenic shoots were produced. Chimeric transgenic plants were obtained after the regeneration of putatively transformed callus, bud‐like protuberances, buds and shoots on selective medium with kanamycin. The treatments producing the most buds or shoots from explants after 30–40 days of cultivation were the most successful for the production of transgenic plants. Only treatments where explants were vortexed with carborundum produced transgenic melon shoots of either cultivar. Subculture every 18–20 days on fresh regeneration‐selection medium containing 50 mg/L kanamycin after either a relatively high (100 mg/L) or low level (50 mg/L) of kanamycin in the first regeneration‐selection medium was necessary for the successful transformation of cultivar Kιrkağaç 637. These techniques are now being used in breeding programs for the production of melon lines bearing resistances to zucchini yellow mosaic virus and cucumber mosaic virus, important viruses limiting agricultural production.
Phospholipid transfer protein (PLTP) mRNA expression is stimulated by developing embryos in the oviduct
Authors: Lee Kai‐Fai , Kwok Ka‐Leung , Chung Man‐Kin , Lee Yin‐Lau , Chow Judy F.C. , Yeung William S.B. 
Published: April 2005

AbstractIn mammal, fertilization and early preimplantation embryo development occurs in the oviduct. Evidence is accumulating that the oviductal epithelia secrete various biomolecules to the lumen during the secretory phase of the estrus cycle to enhance embryo development. This secretory activity of the oviduct is under the regulation of steroid hormones. Observations also suggested that the gametes and embryos modulate the physiology and gene‐expressing pattern of the oviduct. However, the underlying molecular changes remain elusive. We hypothesize that the developing embryos interact with the surrounding environment and affect the gene expression patterns of the oviduct, thereby modulating the oviductal secretory activity conducive to the preimplantation embryo development. To test this hypothesis, suppression subtractive hybridization (SSH) was used to compare the gene expressions in mouse oviduct containing transferred in vitro cultured preimplantation embryos with that of oviduct containing oocytes during the preimplantation period. We reported here the identification and characterization of phospholipids transfer protein (PLTP), which is highly expressed in the embryo‐containing oviduct and localized at the oviductal epithelium by in situ hybridization. PLTP contains signal peptide putative for secretory function. More importantly, PLTP mRNA increases in the oviductal epithelia of pregnant, but not pseudo‐pregnant mice when assayed by real‐time PCR. Taken together, our data suggested that PLTP may play important role(s) during in vivo preimplantation embryo development. This molecule would be a target to delineate the mechanisms and the roles of oviductal secretory proteins on early embryonic development. © 2005 Wiley‐Liss, Inc.
e‐Innovation and trust dynamics
Authors: Smid Gerhard , Bijlsma‐Frankema Katinka , Derksen Hans , Bernaert George 
Published: April 2005

AbstractThe creation of sustained change and innovation in large ‘old’ organizations is a challenge for innovators and we contend, not well supported by rather static models for innovator–actor interactions in handbooks.This paper proposes a dynamic trust‐related approach of innovator–actor interactions, based on literature and the findings of a case study of innovation processes in a Dutch multinational.The paper concludes that effectiveness can be enhanced if innovators understand the dynamics of the field and their development over time and focus on the risks the actors perceive, which shape their areas of relevance.If innovators create a situation in which mutual risks are curbed, mutual learning is promoted and value‐congruence becomes possible and can be the basis for a well‐monitored process of trust‐based cooperation.Copyright © 2005 John Wiley & Sons, Ltd.
The effect of future redeployment on organizational trust
Authors: Ferres Natalie , Connell Julia , Travaglione Anthony 
Published: April 2005

Abstract

This study compares levels of organizational trust and connected variables between two groups of employees from an Australian public health organization.

One group (N = 123) is based in a hospital that will close as part of the organization's transformational strategy, and the other group (N = 152) is based in other hospitals that will remain open. The first group will become redeployed amongst departments in the remaining hospitals.

The relationships between trust, transformational leadership, fairness, perceived organizational support (POS), commitment, organizational citizenship behaviour (OCB conscientiousness) and intention to turnover were investigated, in addition to the relative levels of these variables between the two cohorts of employees.

The hypothesis that future redeployment would result in comparatively negative evaluations of organizational trust and associated constructs was not supported, whereas the hypothesis that traditional exchange relationships would be relevant regardless of an employee's situation was partially upheld.

The theoretical and managerial implications of these findings are discussed.

Copyright © 2005 John Wiley & Sons, Ltd.
Thermal effects in partially saturated soils: a constitutive model
Authors: Bolzon Gabriella , Schrefler Bernhard A. 
Published: April 2005

AbstractThe present paper is centred on the assessment of an elastic–plastic model for partially saturated soils, earlier proposed by the authors, for its predictive capability with respect to temperature changes, on the light of available experimental results. The model is cast within a constitutive framework that uses Bishop's stress and suction as main variables governing the volumetric response of the material. Some enhancement to the original temperature‐independent formulation is proposed. In particular, functions describing the yield surface and the compressibility modulus are modified to account for the shrinking of the elastic domain and for the increase of irreversible volumetric strain with heating. Some examples illustrate the main features of the present proposal. Comparison with some experimental results is also included. Copyright © 2005 John Wiley & Sons, Ltd.
Photonic quasicrystals for application in WDM systems
Authors: Romero‐Vivas J. , Chigrin D. N. , Lavrinenko A. V. , Sotomayor Torres C. M. 
Published: April 2005

AbstractPhotonic quasicrystals can possess an isotropic (complete) photonic bandgap even in the case of low refractive indices of the constitutive materials, which makes them attractive optical materials with important technological applications. In this work, several aspects related to the design of waveguides and cavities using the two‐dimensional (2D) octagonal quasiperiodic lattice are investigated numerically. As an example, the integration of waveguides and a resonating cavity to design an add/drop filter for wavelength division multiplexing applications is briefly described. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
SESAG: an object‐oriented application framework for real‐time systems
Authors: Hsiung Pao‐Ann , Lee Trong‐Yen , Fu Jih‐Ming , See Win‐Bin 
Published: April 2005

AbstractAdvancements in hardware and software technologies have made possible the design of real‐time systems and applications where stringent timing constraints are imposed on critical tasks. The design of such systems is more complex than that of temporally unrestricted systems because system correctness depends on the satisfaction of functional as well as temporal requirements. To aid users in correctly and efficiently designing systems, object‐oriented frameworks provide a useful environment for significant reuse and reduction in design effort. In contrast to other application domains, there has been relatively little work on an application framework for the design of real‐time systems. Facing the growing need for real‐time applications, we propose a novel application framework called SESAG, which consists of five components, namely Specifier, Extractor, Scheduler, Allocator, and Generator. Within SESAG, several design patterns are proposed and used for the development of real‐time applications. A new evaluation metric called relative design effort is proposed for evaluating SESAG. Experiences in using SESAG show a significant increase in design productivity through design reuse and a significant decrease in design time and effort. Two complex application examples have been developed using SESAG and evaluated using the new evaluation metric. The examples demonstrate relative design efforts of at most 18% of the design efforts required by conventional methods. Copyright © 2005 John Wiley & Sons, Ltd.
Environmental models for predicting oceanic dolphin habitat in the Northeast Atlantic
Authors: Hastie Gordon D. , Swift René J. , Slesser George , Thompson Paul M. , Turrell William R. 
Published: April 2005

AbstractDolphin distributions have been related to a range of oceanographic determinants. The complex topography and hydrography of the Faroe-Shetland Channel have a significant influence on the distribution of many species. However, there is no published detail on how dolphin distributions there are influenced by either topography or hydrography. The study therefore aims to relate dolphin distributions in the Faroe-Shetland Channel to environmental variables, using a general additive modelling framework applied to passive acoustic survey data. Models were created using data from 2001, and were cross-validated to test their predictive power. Predictions were calculated at each stage in the model-building process, and were tested against data from 2002. The results suggest that water noise level, time of day, month, water depth, and surface temperature were significant influences on the probability of detecting dolphins acoustically during 2001. Furthermore, the model was a significant predictor of dolphin distribution in 2002. The model with the greatest predictive power included the terms water noise level, time of day, month, and water depth. The results provide information of potential use in understanding the determinants of dolphin distributions, and hopefully will help managers address concerns about the potential impacts on dolphins of anthropogenic activity.