bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic Investigations of Phase‐Separated Thermotropic Layers Based on UV Cured Acrylate Resins
Authors: Resch Katharina , Wallner Gernot M. , Lang Reinhold W. 
Published: May 2008

AbstractSummary: In this paper spectroscopic techniques were adapted and applied to characterize the optical and morphological properties of thermotropic resins. Thermotropic films were prepared by variation of resin base and thermotropic additives. By UV/Vis/NIR spectroscopy the solar optical properties, the switching temperature, the switching process and the residual transmittance in the opaque state were determined. To control the sample temperature from ambient to 100 °C a conventional UV/Vis/NIR spectrophotometer equipped with an Ulbricht‐sphere was adapted by a heating stage. Additive content, distribution and scattering domain size were characterized by Differential Scanning Calorimetry, Attenuated Total Reflectance spectroscopy and microscopic techniques. For the investigated film types hemispheric solar transmittance values ranging from 80 to 87% and 75 to 85% were obtained in the clear and the scattering state, respectively. The diffuse solar transmittance values increased significantly from 14 to 40% below the switching temperature to 36 to 70% at elevated temperatures. The thermotropic resins exhibit a steep and rapid switching process with switching temperatures between 45 and 70 °C. The materials with the best switching properties are characterized by distinct differences in refractive index between the components, a uniform additive distribution and scattering domains with diameters below 1000 nm.
In situ ATR‐FTIR and SFM Studies on the Influence of Adsorption time on Deposition and Nanostructure of Poly(ethyleneimine)/Poly(acrylic acid) Multilayers
Authors: Muller M. , Paulik S. 
Published: May 2008

AbstractSummary: The deposition and the nanostructure of polyelectrolyte multilayers (PEM) of branched poly(ethyleneimine)/poly(acrylic acid) (PEI/PAC) was studied in dependence of the adsorption time (tADS) of the individual steps. PEM were reproducibly deposited applying up to z = 20 adsorption steps at the fixed pH combination of 10/4 and polyelectrolyte concentration cPEL = 0.005 M in a flow cell using an automated valve system. in situ ATR‐FTIR spectroscopy and SFM were used for quantitative determination of deposited amount and thickness, respectively. A linear relation between PEL band integrals and thickness of thin PEM films was found. Varying tADS from 0.5 to 5 min in each of the adsorption steps resulted in a steep rise of the deposited PEM amount. For tADS > 5 min the deposition did only marginally increase. Evidence for the release of outermost located PEI upon PAC immersion (even step) and of outermost PAC upon PEI immersion (odd step) was obtained. SFM images on consecutively deposited PEM‐6 showed a slight increase in structure size and roughness for increasing tADS. These studies help to prepare polyelectrolyte based films with controlled thickness for the interaction with biofluids in the biomedical and food field.
Rheo‐optical FT‐IR Spectroscopy of LLDPE: Effect of Comonomer and Composite Materials
Authors: Plass M. , Streck R. , Nieto J. , Siesler H. W. 
Published: May 2008

AbstractSummary: In order to further evaluate the potential of FT‐IR spectroscopic investigations on molecular processes during tensile testing experiments, the behavior of monolayer LLDPE films, made with ethylene‐butene and ethylene‐octene copolymers, was studied. Additionally, multilayer LLDPE films based on the same C4 and C8 copolymers were investigated. The stress‐strain data obtained from the monolayer films indicate differences in the strain hardening region. It seems that the film samples PE 469‐30‐2 (C4‐gas phase process) and PE 469‐30‐5 (C8 solution process) behave similarly whereas the strain hardening for the PE 469‐30‐3 (C4 solution process) requires lower stress values. The orientation function changes during the stretching of the films indicating that unfolding of the polymer chains occurs at lower strain for PE 469‐30‐5 (C8) than in the C4 materials. In the multilayer systems the Primplast 44 material (C8) shows a lower tendency for reorientation in the strain hardening region than the Coex 82 (C4) material. In this region of the stress‐strain curve the lamellar structure is already transformed into the fibrillar arrangement. Regarding the orientation behavior of the material above 200% strain, a small increase in fb was observed, which led to a decrease of fc. In the octene product possibly the bulky side chains influence the unfolding significantly, producing a higher resistance to unfolding and alignment along the stretching direction. In part, this is potentially caused by the more perfect lamellae in the octene copolymer, which do not include the side chains, while the butene copolymer may have weaker lamellae because they contain a fraction of the side chains which create defects. Consequently, the octene copolymer requires higher stress values to be stretched and finally results in a lower stretchability of this material, as observed on an industrial scale during pallet wrapping tests. Based on the ratio of the structural absorbance parameters of the signals at 729 and 719 cm−1 changes in the crystallinity were studied. For the continuous stretching experiment, no monoclinic phase was detected even after Fourier self‐deconvolution and peak fitting approaches. Literature data, however, describe that this crystalline transformation takes place as a result of mechanical deformation. Therefore, stepwise stretching experiments which allow an improvement of the spectral resolution to 1 cm−1 were carried out. In the deconvoluted spectra the monoclinic, orthorhombic and amorphous LLDPE modifications could be assigned. Ultimate stretchability and stretching force of the films, both monolayer and multilayer, was well correlated to the development of crystalline orientation in the films upon stretching. Other mechanical properties like Elmendorf tear and dart impact can also be better understood with these results.
The transcription factor Egr1 regulates the HIF‐1α gene during hypoxia
Authors: Sperandio Sabina , Fortin Jessyka , Sasik Roman , Robitaille Lynda , Corbeil Jacques , de Belle Ian 
Published: May 2008

AbstractUsing oligonucleotide expression microarrays we have examined the modulation of gene expression in the DU145 prostate cancer cell line. Our findings confirm that the Egr1 transcription factor is rapidly and transiently upregulated by hypoxia. Furthermore, we have demonstrated that HIF‐1α mRNA is also transiently upregulated, as is its target gene VEGF. To elucidate the mechanism of the transcriptional upregulation of the HIF‐1α gene, we have shown that Egr1 is able to directly bind to the HIF‐1α promoter using chromatin immunoprecipitation. We also provide evidence that the binding of Egr1 is necessary for the trans‐activation of the HIF‐1α promoter. These studies highlight the importance for the Egr1 transcription factor in the hypoxic response in cultured prostate cancer cell lines, and indicate that the response of Egr1 is upstream of HIF‐1 in these cells. These studies are the first demonstration that the HIF‐1α transcription factor is targeted directly by Egr1 in hypoxia. © 2008 Wiley‐Liss, Inc.
Monitoring and verifying cloud forecasts originating from operational numerical models
Authors: Zingerle Christoph , Nurmi Pertti 
Published: May 2008

AbstractWeather satellites produce large amounts of observational data in real time. This information has high temporal and spatial resolution covering almost every region of the globe. The infrared (IR) window channels of operational meteorological satellites are sensitive to the clouds and to the underlying surface. Comparing the IR channel observations with synthetic satellite images is an effective way to evaluate the quality of cloud forecasts produced by numerical models. Assessment of potentially problematic features in the early stages of the forecast is essential in not only nowcasting and very short‐range forecasting but also in a reliability check of a given numerical weather prediction model (NWP). A pre‐operational real‐time monitoring system is set up in the Finnish Meteorological Institute, using the observed and synthetic satellite images, and applying an entity‐based verification method. Copyright © 2008 Royal Meteorological Society
A Comparison of Modeling Approaches for Dispersion Homopolymerization of MMA and Styrene in Supercritical CO2
Authors: Quintero‐Ortega Iraís A. , Jaramillo‐Soto Gabriel , García‐Morán Pedro R. , Castellanos‐Cárdenas M. Luz , Luna‐Bárcenas Gabriel , Vivaldo‐Lima Eduardo 
Published: May 2008

AbstractA comparison of kinetic models for dispersion polymerization of MMA and styrene in supercritical CO2 is presented. The limiting case of solution polymerization, as a simplified case, was also addressed. Calculation of the partition of components between the continuous and dispersed phases was emphasized. Experimental data for the solution and dispersion polymerizations of styrene and MMA, using different types of stabilizers, were used to guide the study. Although all the models analyzed can be considered as “adequate” in representing the behavior of the system, some of their strengths and drawbacks have been highlighted.magnified image
Changes in utilisation of hormone replacement therapy in Australia following publication of the findings of the Women's Health Initiative
Authors: Main Penelope , Robinson Maxine 
Published: May 2008

AbstractPurposeTo examine the impact of publication of the findings of the Women's Health Initiative (WHI) on the utilisation of hormone replacement therapy (HRT) in Australia with particular reference to the influence that media may have had on prescriber and consumer behaviour.MethodsRetrospective data from the Australian Government Department of Health, Ageing DUSC Database and media hits from Factiva were reviewed to obtain prescription numbers, total cost and cost to the pharmaceutical benefits scheme and number of media hits from the year before publication of the combined HRT arm of the WHI.ResultsPrescribing of HRT products decreased significantly immediately following publication of the combined HRT arm of the WHI and continued to decline at a slower rate following publication of the memory and oestrogen only arms of the study.ConclusionsThese results represent a more accurate national estimate of the change in HRT use in Australian women relative to previous findings from surveys carried out in Australia. Copyright © 2008 John Wiley & Sons, Ltd.
Complexation of niflumic acid with native and hydroxypropylated α‐ and β‐cyclodextrins in aqueous solution
Authors: Zielenkiewicz Wojciech , Terekhova Irina V. , Koźbiał Małgorzata , Wszelaka‐Rylik Małgorzata , Kumeev Roman S. 
Published: May 2008

AbstractInteractions between niflumic acid and native and hydroxypropylated α‐ and β‐cyclodextrins (CDs) were investigated by 1H NMR, UV‐vis spectroscopy, densimetry, and calorimetry at pH = 7.4 (phosphate buffer) and T = 298.15 K. Thermodynamic parameters of 1:1 complex formation were calculated and discussed in terms of influence of cavity size and availability of hydroxypropyl substituents on the complex stability. The 1H NMR data indicated the inclusion of niflumic acid into macrocyclic cavity of all CDs under study. It was found that both phenyl and pyridine rings of niflumic acid molecule can be included in the cyclodextrin cavity. The co‐existence of two different kinds of 1:1 inclusion complexes in the solution was suggested. In spite of the fact that binding of niflumic acid with α‐cyclodextrin is more enthalpically favorable, stability of the inclusion complexes is very low due to the enthalpy–entropy compensation effect. Complex formation of β‐CDs with niflumic acid is characterized by the higher enthalpy and entropy changes caused by more intense dehydration. Introduction of hydroxypropyl groups in the cyclodextrin molecule was found to promote the binding with niflumic acid. Copyright © 2008 John Wiley & Sons, Ltd.
Frost weathering: recent advances and future directions
Authors: Matsuoka Norikazu , Murton Julian 
Published: May 2008

AbstractThis paper reviews frost‐weathering studies in the last five years and proposes key questions to be answered. New techniques have enabled us to monitor moisture contents and crack movements in near‐surface hard jointed bedrock and to evaluate seasonal rockfall activity in high mountains. Field monitoring has highlighted the roles of diurnal and annual frost cycles in controlling the timing and magnitude of frost weathering. In the laboratory, bidirectional freezing in soft, porous rocks has produced fractures containing segregated ice layers near the permafrost table, which imply the development of ice‐filled fractures in permafrost bedrock over long time‐scales. This finding, combined with numerical modelling of the thermal regime in permafrost rock slopes, contributes to the prediction of large‐scale rockfalls and rock avalanches triggered by permafrost degradation. Future studies should also focus on explosive shattering, frost weathering of hard‐intact rocks, field monitoring of ice segregation and bedrock heave, and the role of frost weathering in landscape evolution. Copyright © 2008 John Wiley & Sons, Ltd.
Buprofezin susceptibility survey, resistance selection and preliminary determination of the resistance mechanism in Nilaparvata lugens (Homoptera: Delphacidae)
Authors: Wang Yanhua , Gao Congfen , Xu Zhiping , Zhu Yu Cheng , Zhang Jiushuang , Li Wenhong , Dai Dejiang , Lin Youwei , Zhou Weijun , Shen Jinliang 
Published: May 2008

AbstractBACKGROUND: Buprofezin has been used for many years to control Nilaparvata lugens (Stål). Assessment of susceptibility change in the insect is essential for maintaining control efficiency and resistance management.RESULTS: Eleven‐year surveys showed that most field populations were susceptible before 2004. However, substantially higher levels of resistance (up to 28‐fold) were found in most of the rice fields in China after 2004. A field population was collected and periodically selected for buprofezin resistance in the laboratory. After 65 generations (56 were selected), the colony successfully obtained 3599‐fold resistance to buprofezin. Synergism tests showed that O,O‐diethyl‐O‐phenyl phosphorothioate (SV1), piperonyl butoxide (PBO) and diethyl maleate (DEM) increased buprofezin toxicity in the resistant strain by only 1.5–1.6 fold, suggesting that esterases, P450‐monooxygenases and glutathione S‐transferases had no substantial effect on buprofezin resistance development.CONCLUSION: The results from this study indicate that N. lugens has the potential to develop high resistance to buprofezin. A resistance management program with rotation of buprofezin and other pesticides may efficiently delay or slow down resistance development in the insect. Further investigation is also necessary to understand the resistance mechanisms in N. lugens. Copyright © 2008 Society of Chemical Industry
Residues of 14C‐metsulfuron‐methyl in Chinese paddy soils
Authors: Wang Haizhen , Wu Jianjun , Yates Scott , Gan Jay 
Published: May 2008

AbstractBACKGROUND: Metsulfuron‐methyl is widely used for controlling many annual grasses and broadleaf weeds in cereal crops. Nonetheless, increasing evidence has demonstrated that even extremely low levels of metsulfuron‐methyl residues in soil can be toxic to subsequent crops or non‐target organisms. The behavior of herbicides in soils is mostly related to their residual forms. The intent of the present study was to investigate the dynamics of extractable residues (ERs) and non‐extractable residues (NERs) of 14C‐metsulfuron‐methyl in twelve Chinese paddy soils and their relationships to soil properties.RESULTS: ERs decreased gradually after application, whereas NERs increased rapidly during the initial 28 days, and gradually decreased thereafter. ERs and NERs were respectively 10.1–67.9% and 5.6–28.7% of applied radioactivity in soils at 224 days after application. ERs correlated positively with soil pH and silt fractions, and negatively with microbial biomass carbon (MBC) and clay fractions, but the opposite was observed for NERs.CONCLUSION: Both ERs and NERs may be present in the soil at the time of planting following rice crops, and the risk of phytotoxic effects needs to be considered. Soil pH, MBC and clay/silt fractions were the main factors in affecting the amounts of both ERs and NERs of metsulfuron‐methyl in the tested soils. Copyright © 2008 Society of Chemical Industry
Elastic and inelastic tunneling through one‐electron and two‐electron states in a vertical double quantum dot
Authors: Kodera T. , Ono K. , Amaha S. , Tokura Y. , Arakawa Y. , Tarucha S. 
Published: May 2008

AbstractWe study the magnetic field dependence of tunnelling current through the two triplet states as well as the two single‐particle states in a double quantum dot. The single‐particle state tunnelling occurs between a discrete state and three nearly degenerate states. The resonance current shows a large variation for the three states at zero‐field, and becomes equivalent as the field increases to lift the degeneracy. This can be assigned to coherent mixing of the degenerate states. The other tunnelling occurs between a triplet having one electron in each dot and that having two electrons in one of the two dots. The resonance width is much smaller than that for the single‐particle tunnelling at zero‐field, and gradually increases as the field increases. This reflects that conservation of the spin z‐component is crucial for the inter‐dot tunnelling. Particularly in the small field range, the resonance can be significantly disturbed by fluctuating nuclear spin field. For the triplet state tunnelling, we also observe gradual increase of inelastic current with phonon emission as the field increases. This is consistent with theory of electron‐phonon scattering whose contribution increases as the inter‐dot tunnel coupling increases. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of spontaneous and piezoelectric polarizations on carrier confinement at the Zn0.88Mn0.12O/ZnO interface
Authors: Masuko K. , Sakiyama H. , Ashida A. , Yoshimura T. , Fujimura N. 
Published: May 2008

AbstractFor Zn1‐x Mnx O/ZnO heterostructures pseudomorphically grown on ZnO (000$ \bar 1 $) single‐crystal substrates, spontaneous and piezoelectric polarization‐induced sheet charges were investigated. The sheet carrier concentration of a Zn0.88Mn0.12O/ZnO heterostructure with a 10‐nm‐thick ZnMnO spacer layer was determined to be 5.6×1012 cm–2 by Hall measurement. For x = 0.12, the number of free electrons induced by spontaneous and piezoelectric polarizations was calculated to be 1.8×1012 cm–2, which is less than the experimental value. This discrepancy can be explained by considering an additional electric field generated by the ZnMnO/ZnO conduction band offset and ZnMnO spacer layer. Therefore, for ZnMnO/ZnO heterostructures, the effect of electric field should also be considered together with spontaneous and piezoelectric polarizations in carrier confinement. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wet chemical etching behavior of β‐Ga2O3 single crystal
Authors: Ohira Shigeo , Arai Naoki 
Published: May 2008

AbstractWet chemical etching behavior of β‐Ga2O3 single crystal was investigated to evaluate its chemical stability and to explore etchants for β‐Ga2O3 single crystal. Undoped and Sn‐doped β‐Ga2O3 single crystals were grown by the floating zone method, and (100)‐ and (001)‐oriented samples were chemical‐mechanical‐polished to wafers. The samples were wet chemically etched in solutions such as HCl, H2SO4, HNO3, HF, H2O2:H2SO4:H2O=1:4:1, KOH, and NaOH. The samples were chemically stable against both acids and alkalis except HF and NaOH. Aqueous HF solution was found to etch β‐Ga2O3 uniformly at room temperature. The etch rate increased with increasing immersion time and HF content. Anisotropy of etch rate was observed between the (100) and (001) planes. The etch rate of Sn‐doped β‐Ga2O3 was lower than that of undoped β‐Ga2O3, and the etch rate decreased with increasing Sn doping content. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical anisotropy of strained quantum wells on high index substrates
Authors: Niki Nobuyoshi , Morita Ken , Kitada Takahiro , Isu Toshiro 
Published: May 2008

AbstractWe investigate anisotropic properties of strained InGaAs quantum wells on the high index (11n)A (n = 3,4,5) GaAs substrates. The polarization dependence of photoluminescence of strained InGaAs quantum wells were measured, and optical anisotropy was observed. We calculated anisotropy of the optical transition matrix elements based on the 4x4 and 6x6 Luttinger model for the quantum wells with uniaxial strain. The calculated anisotropy taking into account of split‐off band qualitaively agree with our experiment. This indicates that the band mixing of split‐off band into the heavy‐hole band largely contributes to the the optical anisotropy in the strained InGaAs quantum wells on the high index substrates. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction of self‐heating in AlGaN/GaN HFETs using thick AlN surface passivation films
Authors: Tanaka N. , Takita H. , Sumida Y. , Suzuki T. 
Published: May 2008

AbstractWe have fabricated and investigated AlGaN/GaN heterojunction field‐effect transistors (HFETs) with thick AlN surface passivation films. The HFETs exhibit increased drain currents and the transconductances with suppression of the self‐heating‐induced negative differential conductance at high applied voltages. Since the effects are more prominent for thicker AlN films, we conclude that the AlN films cause not only surface passivation, but also self‐heating reduction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of thick ZnO films by metal‐source vapor phase epitaxy
Authors: Duan Yao , Cui Junpeng , Wang Xiaofeng , Zeng Yiping 
Published: May 2008

AbstractMetal‐Source Vapor Phase Epitaxy (MVPE), which takes advantage of the reaction of Zn vapor and H2O vapor at high temperature, was employed to grow thick epitaxial ZnO films on c‐sapphire substrates. This method exhibits high growth rate (>120μm/h), good crystallinity and thickness uniformity. A re‐growth method is used to control the polarity of ZnO films and both Zn‐polar and O‐polar samples are obtained. The structural and electric properties and morphology of the samples were characterized by X‐ray diffraction (XRD), Hall measurements and scanning electron microscope (SEM), respectively. The samples' polarities were identified by wet etching method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement in crystalline quality of thick GaInN on m‐plane 6H‐SiC substrates using sidewall epitaxial lateral overgrowth
Authors: Senda Ryota , Miura Aya , Kawashima Takeshi , Iida Daisuke , Nagai Tetsuya , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu 
Published: May 2008

AbstractWe report the fabrication of an epitaxial lateral overgrown (ELO) GaInN layer on a high crystalline‐quality‐grooved GaN template, which is improved by a sidewall ELO (SELO) technology. The photoluminescence peak intensity of ELO‐grown GaInN layer on the SELO GaN underlying layer is twice as high as that of ELO‐grown GaInN layer on the m‐plane GaN template. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)