bluuebunny/crossref_metadata_2025 huggingface dataset:
Water and alcohol(s): what's the difference? A proton NMR and DFT study of hetero‐association with pyridine
Authors: Lomas John S. , Maurel François
Published: May 2008

Hetero‐association of water and some simple aliphatic alcohols with pyridine in benzene has been studied by 1H nuclear magnetic resonance (NMR) spectroscopy at very low donor concentration, where self‐association is negligible. Association constants for the formation of 1:1 and 2:1 pyridine:water complexes can then be determined without recourse to ad hoc computer programmes. That for association of a second pyridine with water is about 10 times lower than for the first. Reaction parameters for the first association with water are very similar to those for the alcohols, whereas the reaction enthalpy for the second association is somewhat smaller. The chemical shift of the OH protons and the HCOH coupling constants for alcohols at high dilution in benzene are almost identical with gas‐phase data. The change in chemical shift upon association with pyridine correlates with the free energy of the reaction. Quantum mechanical calculations [BPE0 functional, 6‐311+G(d,p) basis set and a polarized continuum model of the solvent (IEFPCM)] have been run on complexes of pyridine with water, both 1:1 and 2:1, and with four alcohols. Calculated reaction enthalpies are in qualitative and, in some cases, almost quantitative agreement with the experimental data. The association constants for 1:1 complexation of pyridine with alcohols follow a rough Taft correlation in terms of polar substituent constants. Substituent size, even in the case of very bulky groups, seems to be unimportant. Copyright © 2008 John Wiley & Sons, Ltd.
Comparative nucleophilic reactivities in carboxylate, phosphinate, and thiophosphate esters cleavage
Authors: Ghosh Kallol K. , Bal Sunita , Kolay Sancheeta , Shrivastava Ashish
Published: May 2008

Nucleophilic substitution reaction of p‐nitrophenyl acetate (PNPA), p‐nitrophenyldiphenyl phosphinate, and pesticide parathion with different α‐nucleophiles [I] have been studied at 27 °C in different pH in the presence of a novel cationic surfactant. The kinetic study was performed spectrophotometrically under pseudo‐first order conditions with the α‐nucleophile in excess. The pKa of nucleophiles have also been determined by kinetic method. In the presence of surfactant, the rate constant increased with increasing surfactant concentration up to a limiting value. This behavior has been analyzed in quantitative terms on the basis of pseudo‐phase model of micellar catalysis. Finally the nucleophilic reactivity of hydroxamate ions has been compared with other α‐nucleophiles, like oxime, hydroxybenzotriazole, and 2‐iodosobenzoic acid (IBA). The order of cleavage of electrophilic centers, that is, CO, PO, and PS have also been discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Changes of electron density in the OHN hydrogen bond upon proton transfer in complexes of phenols with trimethylamine: DFT study
Authors: Kwiatkowska Emilia , Majerz Irena
Published: May 2008

The intermolecular hydrogen bonds in phenol–trimethylamine complexes were investigated by Bader Atom in Molecules (AIM) theory. The AIM parameters of the bond critical points (BCPs) of the O···H, N···H, and CO bonds as well as those of the phenol ring critical point (RCP) were analyzed as functions of the proton‐transfer degree. Transfer of the proton from donor to acceptor changes not only the electron density of the hydrogen bridge, but also the electron cloud in the proton donor. The differences between the proton donors in relation to their pKavalues are seen in the systematic changes of the AIM parameters. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and characterization of amphiphilic cationic symmetrical ABCBA pentablock terpolymer networks: Effect of hydrophobic content
Authors: Triftaridou Aggeliki I. , Loizou Elena , Patrickios Costas S.
Published: May 2008

Group transfer polymerization was employed for the preparation of six amphiphilic terpolymer networks comprising the hydrophilic, pH‐responsive 2‐(dimethylamino)ethyl methacrylate (DMAEMA), the neutral hydrophilic methoxy hexa(ethylene glycol) methacrylate (HEGMA), and the hydrophobic n‐butyl methacrylate (BuMA). 1,4‐Bis(methoxytrimethylsiloxymethylene)cyclohexane was used as a bifunctional initiator, whereas ethylene glycol dimethacrylate served as the crosslinker to interconnect the linear terpolymer precursors to three‐dimensional terpolymer network structures. Five of the terpolymer networks were model, with linear chains between crosslinks of precise length. Four of the five model networks were based on ABCBA pentablock terpolymers with theoretical structure DMAEMA5‐b‐BuMAn/2‐b‐HEGMA10‐b‐BuMAn/2‐b‐DMAEMA5 with n values equal to 5, 10, 20, and 30. The model network based on the equimolar statistical terpolymer and the nonmodel randomly crosslinked terpolymer network were also prepared. The molecular weights and compositions of the linear pentablock terpolymer precursors to the networks were found to be close to the theoretically expected, while the network sol fractions were found to be relatively low. The degrees of swelling of the networks in water were found to decrease with increasing the hydrophobic content, whereas those in THF exhibited the opposite trend. Small‐angle neutron scattering in deuterium oxide indicated structural organization in the most hydrophobic pentablock terpolymer networks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4420–4432, 2008
Substituents effect on the properties of sulfonated polyimide copolymers
Authors: Miyatake Kenji , Yasuda Tomohiro , Watanabe Masahiro
Published: May 2008

A series of sulfonated polyimide (SPI) copolymers containing methyl, methoxy, or fluorine groups were synthesized to elucidate the substituents effect on their proton conducting properties as well as thermal, hydrolytic, and oxidative stability for polymer electrolyte membrane fuel cell applications. SPIs of high molecular weight (Mw > 200 kDa, Mn > 80 kDa) along with the ion exchange capacity (IEC) varying between 1.34 and 1.91 mequiv/g were obtained, which gave tough, ductile, and flexible membranes by solution casting. The thermal properties of the SPIs were dominated by the electronic structure of the sulfonated aromatic rings. The electron‐donating methyl groups lowered the thermal decomposition temperature. The hydrolytic and oxidative stability was roughly in the order of IEC (the higher IEC membranes were less stable). Fluorine groups, either as F or CF3, had negative effect on the hydrolytic and oxidative stability. In the water uptake and proton conductivity, hydrophobic components are rather more influential than the substituents. It was found out that the SPI(5, 8, 0.7) containing bis(phenoxy)biphenylene sulfone moieties as a rigid hydrophobic component showed the best balanced properties in terms of the stability and the proton conductivity for its rather low IEC. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4469–4478, 2008
Synthesis of proton‐conducting block copolymer membranes composed of a fluorinated segment and a sulfonic acid segment
Authors: Matsumoto Kozo , Ozaki Fumiaki , Matsuoka Hideki
Published: May 2008

Diblock copolymer membranes having a fluorinated segment and a sulfonic acid segment were prepared by living radical polymerization, solution casting, and crosslinking, followed by heat treatment. Diblock copolymers of 2,3,4,5,6‐pentafluorostyrene (PFS)/4‐(1‐methylsilacyclobutyl)styrene (SBS) and neopentyl styrenesulfonate (SSPen) (poly(PFS‐co‐SBS)‐b‐polySSPen)s were synthesized by nitoroxy‐mediated living radical polymerization. Self‐standing crosslinked membranes were obtained by casting a THF solution of the block copolymer with Pt catalyst. Heat treatment of the membrane at 230 °C induced decomposition of the neopentyl sulfonate esters to provide block copolymer membranes having a fluorinated segment and a free sulfonic acid segment. It was confirmed that the block copolymer with a high sulfonic acid content exhibited high ion exchange capacity and high proton conductivity as well as high thermal stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4479–4485, 2008
Living cationic polymerization of dihydrofuran and its derivatives
Authors: Yonezumi Motomasa , Kanaoka Shokyoku , Aoshima Sadahito
Published: May 2008

Cationic polymerization of 2,3‐dihydrofuran (DHF) and its derivatives was examined using base‐stabilized initiating systems with various Lewis acids. Living cationic polymerization of DHF was achieved using Et1.5AlCl1.5 in toluene in the presence of THF at 0 °C, whereas it has been reported that only less controlled reactions occurred at 0 °C. Monomer‐addition experiments of DHF and the block copolymerization with isobutyl vinyl ether demonstrated the livingness of the DHF polymerization: the number–average molecular weight of the polymers shifted higher with low polydispersity as the polymerization proceeded after the monomer addition. Furthermore, this base‐stabilized cationic polymerization system allowed living polymerization of ethyl 1‐propenyl ether and 4,5‐dihydro‐2‐methylfuran at −30 and −78 °C, respectively. In the polymerization of 2,3‐benzofuran, the long‐lived growing species were produced at −78 °C. The obtained polymers have higher glass transition temperatures compared to poly(acyclic alkyl vinyl ether)s. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4495–4504, 2008
Synthesis and properties of fluorene or carbazole‐based alternating copolymers containing Si and vinylene units in the main chain
Authors: Naga Naofumi , Tagaya Nanae , Noda Hiroyuki , Imai Takahiro , Tomoda Haruhiko
Published: May 2008

Alternating copolymerization of 9,9‐dihexyl‐2,7‐dibromofluorene (HFl), N‐hexyl‐2,7‐dibromocarbazole (2,7‐HCz) or N‐hexyl‐3,6‐dibromocarbazole (3,6‐HCz) with Si‐containing divinyl or diallyl compounds, divinyldimethylsilane, divinyldiphenylsilane, 1,3‐divinyltetramethyldisiloxane, 1,4‐bis(dimethylvinylsilyl)benznene, diallyldimethylsilane, or diallyldiphenylsilane has been investigated using Mizoroki‐Heck reaction with a Pd catalyst. The corresponding alternating copolymers were obtained in good yield. The alternating copolymers from HFl or 2,7‐HCz showed good solubility in typical organic solvents. On the other hand, the copolymer with 3,6‐HCz became insoluble due to the crosslinking. Photophysical properties of the resulting copolymers were investigated with UV–vis absorption and photoluminescence spectroscopy. All the copolymers showed absorption peak derived from π–π* transition at around 340 nm, which was blue shifted in comparison with that of the corresponding homopolymer. Whereas emission peaks of the copolymers of the cast film were red shifted in comparison with that of the homopolymers. Multiple broad absorption peaks, which would be derived from intramolecular charge transfer through σ–π moiety, were also detected in the range from 390 to 450 nm in the spectra of the copolymers containing Si‐vinylene unit. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4513–4521, 2008
Monodisperse ultrafine polystyrene nanoparticles prepared by a semicontinuous microemulsion polymerization
Authors: Kong Xuanfeng , Wu Qian , Hu Wancheng , Wang Zhaoqun
Published: May 2008

Monodisperse ultrafine polystyrene nanoparticles have been successfully prepared under low levels of surfactant through a novel semicontinuous microemulsion polymerization, in which the first part of monomer (St1) is added dropwise while the subsequent supply to the polymerizing system is delivered in one potion. Polystyrene nanoparticles with number‐average diameter of 17.4 nm and polydispersity index of 1.06 were obtained using low level of surfactant/monomer weight ratio of 0.20. Influencing of parameters including amount of St1, solid content, initiator, reaction temperature, and cosurfactant on the resultant particle size and size distribution were investigated. The mechanism of nucleation and particle growth was discussed as well. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4522–4528, 2008
Synthesis and self‐assembly in water of coil‐rod‐coil amphiphilic block copolymers with central π‐conjugated sequence
Authors: de Cuendias Anne , Ibarboure Emmanuel , Lecommandoux Sébastien , Cloutet Eric , Cramail Henri
Published: May 2008

The purpose of this study is to correlate the nano‐organization in water of coil‐rod‐coil amphiphilic block copolymers constituted of a conjugated segment to their optoelectronic properties. The ABA block copolymer structures, easily achieved via coupling reactions, are based on conjugated rod of dihexylfluorene and 3,4‐ethylenedioxythiophene units linked to two flexible poly(ethylene oxide) or poly[(ethylene oxide)‐ran‐(propylene oxide)] chains. These well‐defined copolymers exhibited a range of specific morphologies in water, a good solvent of coil blocks and a bad solvent of the conjugated rod. Particularly, vesicles and micelles with spherical, cylindrical, or elongated shape were noticed. Correlations were attempted to be established between the weight percent of the conjugated sequence contained in the copolymers, the morphology of the nanostructures obtained by self‐assembly in solution and the resulting optical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4602–4616, 2008
Fingerprinting the degradation product patterns of different polyester‐ether networks by electrospray ionization mass spectrometry
Authors: Höglund Anders , Hakkarainen Minna , Kowalczuk Marek , Adamus Grazyna , Albertsson Ann‐Christine
Published: May 2008

Fingerprinting of the degradation product patterns by electrospray ionization mass spectrometry (ESI‐MS) was evaluated as a tool to monitor the degree of degradation in polyester‐ether networks. Four different crosslinked caprolactone (CL) and/or 1,5‐dioxepan‐2‐one (DXO) networks were subjected to hydrolytic degradation in aqueous solution at 37 °C for up to 147 days. After predetermined time periods, the water‐soluble degradation products were analyzed by ESI‐MS and tandem ESI‐MS. In addition, changes in pH, mass loss, and copolymer composition were determined. In the case of more slowly hydrolyzed CL‐rich (co)polymers, CL and/or DXO oligomers terminated by hydroxyl and carboxyl end groups were predominantly formed as degradation products. However, on prolonged hydrolysis oligomers with attached crosslinking agent dominated the degradation product patterns of more easily hydrolyzed DXO‐rich (co)polymers. It was shown that in the recorded mass spectra the variation of intensities in the series of ions corresponding to DXO and CL/DXO oligomers with or without attached crosslinking agent could be utilized to monitor the extent of hydrolytic degradation in the polyester matrix and the disruption of the network structure. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4617–4629, 2008
Preliminary results of a longitudinal study of changes in cognitive function in breast cancer patients undergoing chemotherapy with doxorubicin and cyclophosphamide
Authors: Jansen Catherine E. , Dodd Marylin J. , Miaskowski Christine A. , Dowling Glenna A. , Kramer Joel
Published: May 2008

Objectives: Recent studies suggest that standard dose chemotherapy for breast cancer may cross the blood–brain barrier. However, the evidence for chemotherapy‐induced cognitive impairments in breast cancer patients is inconsistent. The purposes of this study in a sample of newly diagnosed patients with breast cancer were to (1) evaluate cognitive function prior to the administration of chemotherapy; (2) assess changes in cognitive function over time; and (3) evaluate potential relationships between cognitive function and anxiety, depression, fatigue, hemoglobin level, menopausal status, and perception of cognitive function.

Methods: Thirty women with breast cancer completed neuropsychological testing before the initiation of chemotherapy and after four cycles of doxorubicin and cyclophosphamide. Descriptive statistics were used to summarize sample characteristics, and paired t‐tests were carried out to evaluate for changes in neuropsychological test scores prior to and following completion of chemotherapy. Linear mixed model analyses were used to determine whether significant changes in neuropsychological test scores remained after controlling for anxiety, depression, fatigue, hemoglobin level, menopausal status, and perceived cognitive function.

Results: Significant decreases in visuospatial skill (p<0.001) and total cognitive scores (p=0.001) were found following chemotherapy. In addition, a significant improvement was found in executive function (p=0.014). Of note, these changes remained significant even after controlling for anxiety, depression, fatigue, hemoglobin level, menopausal status, and perceived cognitive function.

Conclusions: Data from this study supported the hypothesis that chemotherapy may have a negative impact on select domains of cognitive function. Copyright © 2008 John Wiley & Sons, Ltd.
Carbon Nanotube Synthesis in Atmospheric Pressure Glow Discharge: A Review
Authors: Nozaki Tomohiro , Okazaki Ken
Published: May 2008

This review presents recent developments of formation techniques related to atmospheric pressure glow discharge. The description specifically emphasizes their application to carbon nanotube (CNT) synthesis based on our recent work. High‐purity vertically aligned single‐walled CNTs are producible only when an atmospheric pressure glow discharge is applied: even moderate pressure such as 20 kPa preferentially synthesizes multi‐walled CNTs. Lower operating pressures are known to produce carbon nanofibers exclusively. A tentative reaction mechanism is discussed based on plasma‐induced substrate heating and on‐line gas analysis in the plasma sheath. Finally, concluding and prospective remarks are presented briefly.

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Recent contributions to the study of past permafrost
Authors: French Hugh
Published: May 2008

This paper reviews recent literature, published between 2002 and 2007, concerning the previous existence of permafrost (past permafrost) that formed during the cold periods of the Pleistocene in the northern mid‐latitudes. Some past permafrost continues to be preserved today as relict permafrost in the higher northern latitudes. Given that global climate warming models predict widespread thaw of permafrost in the coming century, it is surprising that little attention has been given to the insights that past and relict permafrost offer as to the nature and duration of permafrost thaw. Copyright © 2008 John Wiley & Sons, Ltd.
Response of citrus peelminer Marmara gulosa Guillén and Davis (Lepidoptera: Gracillariidae) stages to various insecticides
Authors: Grafton‐Cardwell Elizabeth E , Montez Gregory M , Reagan Christopher A , Dunn Richard A , Ouyang Yuling
Published: May 2008

BACKGROUND: Egg and larval stages of citrus peelminer Marmara gulosa Guillén and Davis infesting zucchini squash Cucurbita pepo L. var ‘Revenue’ were exposed in the laboratory to a wide range of insecticide classes used in California citrus (organophosphate, carbamate, pyrethroid, neonicotinoid, insect growth regulator, fermentation products and sulfur) to determine peelminer response with and without a non‐ionic adjuvant or oil.

RESULTS: All of the insecticides tested except sulfur reduced egg hatch and mine initiation. When the larval stage was treated, only buprofezin failed to reduce larval and pupal development. Cyfluthrin and spinosad, with the addition of adjuvant or oil, and abamectin combined with oil allowed no survivors at 7 days after treatment (DAT). The slower‐acting insect growth regulators pyriproxyfen and diflubenzuron applied in combination with adjuvant or oil allowed no survival of peelminer 21 DAT. A field trial showed 62.6–68.5% reduction in mined citrus fruit after two applications of diflubenzuron and no significant improvement of control with the addition of cyfluthrin.

CONCLUSION: Bioassays indicate that M. gulosa is relatively susceptible to a wide range of insecticide classes in the laboratory. Lack of efficacy experienced in field trials would then be due to characteristics of the fruit or canopy that limit coverage, rather than to the effectiveness of the insecticides. Copyright © 2008 Society of Chemical Industry
Quantum‐corrected Monte Carlo analysis of scaling behavior of nano‐scale InGaAs high electron mobility transistors
Authors: Fujishiro Hiroki I. , Kawabata Takahiro , del Alamo Jesús A.
Published: May 2008

The performance of InGaAs HEMTs with gate length (Lg) scaled down to 10 nm is estimated using quantum‐corrected Monte Carlo (MC) simulations. Thinner gate barrier results in better scaling properties. A nearly universal relationship of subthreshold slope (S) and DIBL on a scaling parameter (γ) that represents the aspect ratio of Lg and characteristics length (λ) can be seen. After further optimization to reduce λ, through a reduction in barrier and/or channel thickness, the InGaAs HEMT could become a likely candidate to enter the CMOS roadmap beyond Si. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Drive current of ultrathin Ge‐on‐insulator n‐channel MOSFETs
Authors: Azuma Y. , Mori T. , Tsuchiya H.
Published: May 2008

In this paper, we study a drive current of ultrathin Ge‐on‐Insulator (GOI) n ‐channel MOSFETs based on a quantum‐corrected Monte Carlo device simulation. We found that the drive current of GOI n ‐channel MOSFETs significantly decreases by considering electron transfer to the higher X valleys from the lowest L valleys due to the phonon scattering. However, under quasi‐ballistic transport, the GOI n ‐channel MOSFETs with Ge (111) surface orientation are demonstrated to provide substantially higher drive current than the Si‐based MOSFETs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoelastic damping in GaAs micromechanical resonators
Authors: Okamoto Hajime , Ito Daisuke , Onomitsu Koji , Yamaguchi Hiroshi
Published: May 2008

Damping of the mechanical motion is one of the factors that limit the sensitivity of mechanical resonators. For the development of high‐sensitivity transducers, it is important to understand the damping mechanism of the resonators and minimize the damping effect. Here, we show that the damping of a GaAs microcantilever strongly depends on the temperature and it is minimized at around 50 K. This temperature dependence of the damping is mainly caused by the thermoelastic damping effect, which is generated by the strain‐induced temperature gradient in the GaAs cantilever. The minimization of the mechanical damping at around 50 K is due to the suppression of the thermal expansion of GaAs at this temperature, which eliminates the temperature gradient in the cantilever. This result indicates that the sensitivity of GaAs resonators can be improved by adjusting the operating temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Complete basis set extrapolations of dispersion, exchange, and coupled‐clusters contributions to the interaction energy: a helium dimer study
Authors: Jeziorska Małgorzata , Cencek Wojciech , Patkowski Konrad , Jeziorski Bogumił , Szalewicz Krzysztof
Published: May 2008

Effectiveness of various extrapolation schemes in predicting complete basis set (CBS) values of interaction energies has been investigated for the helium dimer as a function of interatomic separation R. The investigations were performed separately for the leading dispersion and exchange contributions to the interaction energy and for the interaction energy computed using the coupled cluster method with single and double excitations (CCSD). For all these contributions, practically exact reference values were obtained from Gaussian‐type geminal calculations. Sequences of orbital basis sets augmented with diffuse and bond functions or augmented with two sets of diffuse functions have been employed, with the cardinal numbers up to X = 7. The functional form EX = ECBS + A(X − k)−α was applied for the extrapolations, where EX is the contribution to the interaction energy computed with a basis set of cardinal number X. The main conclusion of this work is that CBS extrapolations of an appropriate functional form generally improve the accuracy of the interaction energies at a very small additional computational cost (of the order of 10%) and should be recommended in calculations of interatomic and intermolecular potentials. The effectiveness of the extrapolations significantly depends, however, on the interatomic separation R and on the composition of the basis set. Basis sets with midbond functions, well known to provide at a given size much more accurate nonextrapolated results than bases lacking such functions, have been found to perform best also in extrapolations. The X−1 extrapolations of dispersion energies computed with midbond function turned out to be very efficient (except at large R), reducing the errors by an order of magnitude for small X and a factor of two for large X (where the errors of nonextrapolated results are already very small). If midbond functions are not used, the X−3 formula is most appropriate for the dispersion energies. For the exchange component of the interaction energy, the best results are obtained—in both types of basis sets—with the X−4 extrapolation, which leads (in both cases) to almost an order of magnitude reduction of the error. The X−3 and (X − 1)−3 extrapolations work also well, but give smaller improvements. The correlation component of the CCSD interaction energy extrapolates best with α between 2 and 3 for bases with midbond functions and between 3 and 4 for bases without such functions. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Ultra‐high accuracy calculations for hydrogen molecule and helium dimer
Authors: Cencek Wojciech , Szalewicz Krzysztof
Published: May 2008

Large basis sets of explicitly correlated Gaussian (ECG) functions with carefully optimized nonlinear parameters have been used to calculate the binding energies of H2 and He2 at their equilibrium internuclear distances R. In the case of the helium dimer, the wave function includes a product of two helium atom functions, which accounts for the main part of the total energy. At R = 1.4 bohr, a strict upper bound to the H2 total energy in the Born‐Oppenheimer approximation is equal to −1.174 475 714 220 363 hartree and the complete basis set (CBS) limit is estimated as −1.174 475 714 220 44(6) hartree. At R = 1.4011 bohr, the corresponding values are −1.174 475 931 400 135 and −1.174 475 931 400 21(6). A strict upper bound to the interaction energy of He2 at R = 5.6 bohr is −11.00035 K and the CBS limit is −11.0006(2) K. The results for both systems are significantly more accurate than any results reported in literature. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Addition of spawning gravel—a means to restore spawning habitat of atlantic salmon (Salmo salar L.), and Anadromous and resident brown trout (Salmo trutta L.) in regulated rivers
Authors: Barlaup Bjørn T. , Gabrielsen Sven Erik , Skoglund Helge , Wiers Tore
Published: May 2008

In regulated rivers, canalization and reduced water discharge may lead to loss or impairment of salmonid spawning areas, and thereby negative effects on stock recruitment. We discuss the possibility of mitigating such effects through establishing new spawning areas by addition of gravel. We monitored the occurrence of nests in seven gravel deposition sites in five different Norwegian rivers. The total area covered by each of the depositions spanned from 25 m2 to 300 m2. The areas were examined for nests during a 2–5 year period following the addition of gravel, that is, a total of 27 spawning periods. The fish were found to spawn at all localities and years with the exception of two occasions when gravel was lost during floods. Spawning success measured as egg survival was generally high (>80%). These results show that the additions met the criteria for successful spawning. Nests of Atlantic salmon were found to be aggregated in the area with the highest water current. However, successful nests were also found in areas with added gravel where the water current was much reduced. This unusual selection of spawning site most likely reflects the lack of other, more favourable spawning areas. The results therefore suggest that gravel additions can be successful even if the only available areas are suboptimal with respect to water flow and water depth. Three of the seven localities were unsuitable as the gravel was partly or totally displaced downstream during floods. At two of these localities, nests were probably lost because the floods occurred after the spawning season. This shows that large floods can be a major drawback. Monitoring of the spawning success and displacement of gravel is therefore essential to evaluate the method. Subsequently, stable areas, favoured by the spawners, can be expanded by supplementary addition of gravel. In sum, the results show that the careful addition of gravel areas can be used to provide suitable spawning locations for salmonids in regulated rivers. Copyright © 2008 John Wiley & Sons, Ltd.
Long‐term brown trout populations responses to flow manipulation
Authors: Sabaton Catherine , Souchon Yves , Capra Herve , Gouraud Veronique , Lascaux Jean‐Marc , Tissot Laurence
Published: May 2008

Despite the many habitat simulations that have been undertaken around the world, not enough biological monitoring has been performed following flow manipulations. It is difficult, however, to refine flow management decisions without a better understanding of the links between amounts, durations and seasonality of flow deliveries and population dynamics.

Trout populations were monitored before and after flow alterations in five trout streams, involving 17 study sites over a 4‐ to 12‐year period, depending on the sites.

A comparison of the trout populations observed to theoretical habitat/population models pointed up several helpful lessons. Various factors slow increases in population size, including the availability and quality of spawning grounds, the general connectivity of the bypass section (BPS) and severe spate events. In addition to these site‐dependent factors, hydrological dynamics may explain why it is so difficult to clearly identify relationships between habitat availability and real fish stocks. Moreover, opportunities to observe population changes are improved when the pre‐enhancement instream flow value is very low, and when there is a considerable difference between pre‐ and post‐enhancement values. A population dynamics model that incorporates different habitat limitations and demographic background can be a very precious tool to improve understanding of the different situations and to build scenarios of population recovery. Copyright © 2008 John Wiley & Sons, Ltd.
Changes in riparian habitats along five major tributaries of the saint Lawrence river, QuÉbec, Canada: 1964–1997
Authors: Charron Isabelle , Lalonde Olivier , Roy André G. , Boyer Claudine , Turgeon Samuel
Published: May 2008

This paper investigates spatiotemporal changes over a 30‐year period within the riparian landscapes of five major tributaries of the Saint Lawrence River (Québec, Canada). Aerial photographs from 1964(1967) for the Saint Maurice, Saint François, Richelieu, Batiscan and Yamachiche Rivers were compared with 1997 photographs to quantify changes in vegetation and land use. The riparian zones were divided into five cover types to create landscape cover maps: herbaceous vegetation, woody vegetation, agriculture, urban and water. The maps were converted into a geographic information system to quantify landscape changes, which were attributed to either natural processes, such as sediment deposition and bank erosion, or anthropogenic influences, such as human settlement. The results show that both natural and anthropogenic changes were limited over the 30‐year study period and that natural processes dominated over human‐caused impacts. Overall, riparian vegetation patches became more fragmented and isolated with time due to the disturbances. However, important differences were observed between and within rivers. Fluvial processes resulted in riparian vegetation losses on three rivers (Richelieu, Saint François and Batiscan) and gains on the other two rivers (Yamachiche and Saint Maurice) while anthropogenic influences resulted in vegetation gains on four rivers, except the Richelieu where gains and losses were equivalent. Thus, while riparian landscapes are sensitive to both fluvial and anthropogenic processes, there is great variability in sensitivity among the tributaries. By providing a better understanding of past changes, studies such as this can help make better predictions of future changes that are expected to occur with climate change. Copyright © 2008 John Wiley & Sons, Ltd.
An environmental scanning electron microscopy study of aqueous gibbsite suspensions
Authors: Houghton H.A. , Donald A.M.
Published: May 2008

Synthetic gibbsite has been used as a model system for study in the environmental scanning electron microscopy (ESEM), to probe its utility as a tool to study clay dispersions under different conditions of aggregation. We have been able to show that we can study the nature of the platelet interactions as the pH is altered, by imaging the dispersions after water evaporation from the surface to permit the surface of the platelets to be clearly seen. It has been possible to show that at alkaline pH there are very few face–edge contacts between the platelets, consistent with what is known about the charges at high pH on the faces and edges of the gibbsite. In contrast, at lower pHs, when faces and edges have opposite sign charges, there are significantly more platelets touching with edge and faces in contact. Finally, when the salt lithium chloride is added to a dispersion at approximately neutral pH, the plates appear to stack suggesting face–face interactions in the dispersion. Thus, ESEM has been able to demonstrate the variability of packing in gibbsite dispersions and to correlate the structures observed with the known charge distribution on the gibbsite platelets. SCANNING 30: 223–227, 2008. © 2008 Wiley Periodicals, Inc.
Making sense of argumentation and explanation
Authors: Berland Leema Kuhn , Reiser Brian J.
Published: May 2008

Constructing scientific explanations and participating in argumentative discourse are seen as essential practices of scientific inquiry (e.g., R. Driver, P. Newton, & J. Osborne, 2000). In this paper, we identify three goals of engaging in these related scientific practices: (1) sensemaking, (2) articulating, and (3) persuading. We propose using these goals to understand student engagement with these practices, and to design instructional interventions to support students. Thus, we use this framework as a lens to investigate the question: What successes and challenges do students face as they engage in the scientific practices of explanation and argumentation? We study this in the context of a curriculum that provides students and teachers with an instructional framework for constructing and defending scientific explanations. Through this analysis, we find that students consistently use evidence to make sense of phenomenon and articulate those understandings but they do not consistently attend to the third goal of persuading others of their understandings. Examining the third goal more closely reveals that persuading others of an understanding requires social interactions that are often inhibited by traditional classroom interactions. Thus, we conclude by proposing design strategies for addressing the social challenges inherent in the related scientific practices of explanation and argumentation. © 2008 Wiley Periodicals, Inc. Sci Ed 93:26–55, 2009
Surface characteristics of AZ91D alloy anodized with various conditions
Authors: Park Il Song , Jang Yong Seok , Kim Yu Kyoung , Lee Min Ho , Yoon Jeong Mo , Bae Tae Sung
Published: May 2008

Anodic oxidation of an AZ91D magnesium alloy was carried out in an attempt to increase the corrosion resistance. The alloy was placed in an electrolyte containing 0.1 M sodium silicate (Na2SiO3), 2.0 M sodium hydroxide (NaOH) and 0.1 M sodium phosphate (Na3PO4), and treated with a current density of 100–400 mA/cm2 for 1 to 4 min. After the anodic oxidation treatment, the surface characteristics were analyzed by SEM, X‐ray diffraction (XRD) and a surface roughness tester. The corrosion resistance was determined by measuring the corrosion potential and corrosion current density using potentiodynamic polarization in a 3.5 wt% NaCl electrolyte solution. Although the anodic oxidation treatment with the base electrolyte resulted in an arrival voltage ranging from 60 to 70 V, the addition of silicate tended to reduce this arrival voltage by approximately 10–20 V and decrease the critical voltage required for the formation of a porous oxide film. The pore size and film thickness increased with increasing applied current and treatment time. The addition of silicate to the electrolyte resulted in films with a homogeneous pore size and a film thickness increasing with the increasing applied current and treatment time. XRD showed the formation of a new MgO and Mg2SiO4 phase. The formation of Mg2SiO4 was attributed to the presence of SiO44− in the film. After the addition of silicate, the corrosion potential increased and corrosion current decreased, resulting in improved corrosion resistance. Copyright © 2008 John Wiley & Sons, Ltd.
Microscopic computed tomography imaging of the cerebral circulation in mice: Feasibility and pitfalls
Authors: Abruzzo T. , Tumialan L. , Chaalala C. , Kim S. , Guldberg R.E. , Lin A. , Leach J. , Khoury J.C. , Morgan A.E. , Cawley C.M.
Published: May 2008

This study evaluates the utility and practical limitations of microcomputerized X‐ray tomography (CT) as a research tool for examination of the cerebral circulation in mice. Six micro CT angiograms of the circle of Willis (COW) from six mice were obtained by scanning whole head and brain specimen perfused with a radio‐opaque silicone contrast agent. Two‐dimensional volume rendered images were postprocessed from three‐dimensional image datasets using a partially automated high‐throughput model that generated 10 surface projections for each specimen. The image processing model employed a straightforward global thresholding and computerized component labeling software algorithm. Postprocessed images were analyzed and results correlated with microdissection. Micro CT demonstration of COW vessels and their branch anatomy was assessed. 71% of COW vessels were completely demonstrated, 26% were partially demonstrated, and 3% were not demonstrated. All cases of nondemonstration and most cases of partial demonstration resulted from scan coverage or postprocessing clip error. Thresholding effect caused pseudostenosis of 8% of COW vessels and accounted for a minority of partial demonstration cases. No imaging artifacts were caused by contrast extravasation or ineffective contrast perfusion. Volume averaging caused minor angioarchitectural distortion of 58% of COW vessels. Ninety‐five percent of COW ≥50 μm and 52% of COW vessels <50 μm were correctly identified by micro CT. Micro CT of the murine COW using a high‐throughput image processing model is feasible. Angioarchitectural distortion due to volume averaging and thresholding effect can occur and pathological findings should be confirmed. Synapse 62:557–565, 2008. © 2008 Wiley‐Liss, Inc.
Genetic and pharmacological manipulations of the CB1 receptor alter ethanol preference and dependence in ethanol preferring and nonpreferring mice
Authors: Vinod K. Yaragudri , Yalamanchili Ratnakumar , Thanos Panayotis K. , Vadasz Csaba , Cooper Thomas B. , Volkow Nora D. , Hungund Basalingappa L.
Published: May 2008

Recent studies have indicated a role for the endocannabinoid system in ethanol‐related behaviors. This study examined the effect of pharmacological activation, blockade, and genetic deletion of the CB1 receptors on ethanol‐drinking behavior in ethanol preferring C57BL/6J (B6) and ethanol nonpreferring DBA/2J (D2) mice. The deletion of CB1 receptor significantly reduced the ethanol preference. Although the stimulation of the CB1 receptor by CP‐55,940 markedly increased the ethanol preference, this effect was found to be greater in B6 than in D2 mice. The antagonism of CB1 receptor function by SR141716A led to a significant reduction in voluntary ethanol preference in B6 than D2 mice. A significant lower hypothermic and greater sedative response to acute ethanol administration was observed in both the strains of CB1 −/− mice than wild‐type mice. Interestingly, genetic deletion and pharmacological blockade of the CB1 receptor produced a marked reduction in severity of handling‐induced convulsion in both the strains. The radioligand binding studies revealed significantly higher levels of CB1 receptor‐stimulated G‐protein activation in the striatum of B6 compared to D2 mice. Innate differences in the CB1 receptor function might be one of the contributing factors for higher ethanol drinking behavior. The antagonists of the CB1 receptor may have therapeutic potential in the treatment of ethanol dependence. Synapse 62:574–581, 2008. Published 2008 Wiley‐Liss, Inc.
Application of systems engineering and information models to optimize operation of gas export systems
Authors: Stærkebye Nørstebø Vibeke
Published: May 2008

This paper presents the use of systems engineering in analysis and optimization of gas export system operation. The Norwegian dry gas export system is selected as the subject for the analysis. The gas export system at the Norwegian Continental Shelf is the largest offshore gas transport network in the world, and it consists of many components, such as pipelines, platforms, processing and exit terminals, and many routing possibilities. There are two important factors that a gas export system shall satisfy. First, the system shall secure that the customers receive the gas that they have ordered. Second, the system shall do this in as energy efficient way as possible, i.e., minimize operating costs and environmental emissions. For the operator of gas export systems it is of vital importance that equipments and pipelines in the system are optimally integrated. This will secure flexibility, capability, availability and energy efficiency of the system, and enhance understanding between different system operators. Operational experience shows that there is a substantial need to analyze the integration between the system components and the effects on optimum operation, energy consumption and environmental emissions. The objective of this work is to demonstrate how systems engineering and information models have been applied as tools for analyzing the integration in and overcoming the complexity of gas export systems and system operation, and further for developing models that optimize the energy efficiency of system operation. © 2008 Wiley Periodicals, Inc. Syst Eng
Mouse toxicity of Anabaena flos‐aquae from Lake Dianchi, China
Authors: Pan Xiaojie , Chang Fengyi , Liu Yongding , Li Dunhai , Xu Aihua , Shen Yinwu , Huang Zebo
Published: May 2008

Some species of the genera Anabaena can produce various kinds of cyanotoxins, which may pose risks to environment and human health. Anabaena has frequently been observed in eutrophic freshwater of China in recent years, but its toxicity has been reported only in a few studies. In the present study, the toxicity of an Anabaena flos‐aquae strain isolated from Lake Dianchi was investigated. Acute toxicity testing was performed by mouse bioassay using crude extracts from the lyophilized cultures. The mice exposed to crude extracts showed visible symptoms of toxicity and died within 10–24 h of the injection. Serum biochemical parameters were evaluated by the use of commercial diagnostic kits. Significant alterations were found in the serum biochemical parameters: alkaline phosphatase (AKP), γ‐glutamyl transpeptidase (γ‐GT), aspartate amino transferase (AST), alanine amino transferase (ALT), AST/ALT ratio, total protein content, albumin content, albumin/globulin (A/G) ratio, blood urea nitrogen (BUN), serum creatinine (Ssr), and total antioxidative capacity (T‐AOC). Histopathological observations were carried out with hematoxylin and eosin (HE) stain under light microscope. Severe lesions were seen in the livers, kidneys, and lungs of the mice injected with crude extracts. The alterations of biochemical parameters were in a dose‐dependent manner, and the severities of histological lesions were in the same manner. Based on biochemical and histological studies, this research firstly shows the presence of toxin‐producing Anabaena species in Lake Dianchi and the toxic effects of its crude extracts on mammals. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
A systematic analysis of the feasibility of four‐dimensional ultrasound imaging using spatiotemporal image correlation in routine fetal echocardiography
Authors: Uittenbogaard L. B. , Haak M. C. , Spreeuwenberg M. D. , Van Vugt J. M. G.
Published: May 2008

Objectives

To investigate the feasibility of incorporating spatiotemporal image correlation (STIC) into a tertiary fetal echocardiography program.

Methods

During the study period all pregnant women fitting our inclusion criteria were enrolled consecutively. Four sonographers participated in the study, one of whom had substantial previous experience of STIC volume acquisition and three of whom did not. STIC volumes were acquired within the time slot allocated for the usual examination and all attempts were recorded. STIC volumes were assessed on acquisition conditions, the quality (as defined by a checklist of cardiac structures that could be visualized), and the rendering abilities. Furthermore, possible learning effects and the influence of experience with STIC on volume acquisition were studied.

Results

STIC volume acquisition was successful in 75.7% (112/148) of cases in which it was attempted. The more experienced sonographer had a higher success rate in STIC volume acquisition (experienced vs. less experienced, 88.4% vs. 70.5%, P = 0.02). Of all analyzed STIC volumes, 64.8% were of high or sufficient quality. STIC volume quality and rendering ability correlated strongly with the acquisition conditions. High‐quality STIC volumes successfully rendered the intracardiac septa in 84.6% of cases. The coronal atrioventricular plane was rendered in 12/26 cases (46.2%).

Conclusions

This study shows that incorporation of STIC volume acquisition into the daily practice of a tertiary fetal echocardiography program is feasible. Sonographers do not have to be specifically experienced in three‐ or four‐dimensional ultrasound imaging to acquire high‐quality STIC volumes. For successful STIC acquisition and subsequent successful analysis, correct acquisition conditions are of major importance. Finally, our results demonstrate that STIC is as susceptible as conventional two‐dimensional ultrasound imaging to individual variations and limitations in scanning windows. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.