bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural characterization and thermal behaviour of block copolymers of polydimethylsiloxane and polyamide having trichlorogermyl pendant groups
Authors: Gill Rohama , Mazhar Muhammad , Siddiq Muhammad 
Published: July 2010

AbstractBlock copolymers having a pendant trichlorogermyl group as a part of polyamide segment(COR′CONHArNH)xCOR′COand polydimethylsiloxane of general formula [(COR′COHNArNH)xCOR′CONH(CH2)3SiO(CH3)2 ((CH3)2SiO)ySi(CH3)2(CH2)3 NH]n (where R′ = CH2CH(GeCl3), CH(CH3)CH(GeCl3), CH(GeCl3)CH(CH3); Ar = C6H4, (C6H3CH3)2, (C6H3OCH3)2, 2,5‐(CH3)2C6H2, C6H4OC6H4) were prepared by a polycondensation reaction and characterized using CHN and Ge analysis, Fourier transform infrared (FTIR) and 1H NMR spectroscopy, thermogravimetric analysis (TGA) and molecular weight determination. They have a lamellar structure with weight‐average molecular weight in the range 1.21 × 105–4.79 × 105 g mol−1. These copolymers display two glass transition temperatures and have an average decomposition temperature of 489 °C. TGA, FTIR and gas chromatography/mass spectrometry studies indicate that degradation of these block copolymers results in carbon monoxide, oligomeric siloxanes and polyamide fragments. They are thermally stable due to the hydrogen bonded interlinked chains of polyamide, while they absorb water due to the presence of GeCl bonding. Copyright © 2010 Society of Chemical Industry
Proteomic and morphological analysis of early stages of wheat grain development
Authors: Nadaud Isabelle , Girousse Christine , Debiton Clément , Chambon Christophe , Bouzidi Mohamed Fouad , Martre Pierre , Branlard Gérard 
Published: July 2010

AbstractThe identification of 249 proteins in the first 2 wks of wheat grain development enabled the chronological description of the early processes of grain formation. Cell division involved expression of the enzymes and proteins of the cytoskeleton and structure, DNA repair and replication enzymes and cellular metabolism enzymes (synthesis of amino acids, cell wall initiation, carbon fixation and energy production, cofactors and vitamins) with a peak expression at 125°Cday (degrees day after anthesis). After the first synthesis of amino acids, protein transport mechanisms, translation signals, sugar metabolism (polymerization of protein) and stress/defence proteins were activated with stable expression between 150 and 280°Cday. Proteins responsible for folding and degradation, including different subunits of proteasome, were highly expressed at 195°Cday. Proteins associated with starch granules (GBSS type 1) were present at the beginning of grain formation and increased regularly up to 280°Cday. Heat shock proteins (HSP70, 80, 90) were expressed throughout the early grain development stages.
Effect of substituent groups of porphyrins on the electroluminescent properties of porphyrin‐doped OLED devices
Authors: Zhu Lin‐Jian , Wang Jian , Reng Tie‐Gang , Li Chun‐Yan , Guo Dong‐Cai , Guo Can‐Cheng 
Published: July 2010

AbstractSix tetraphenylporphyrins (TRPPH2) with different horizontal substituents R (R = H, CH3, OH, F, Cl, Br) were synthesized, and the organic light‐emitting diode (OLED) devices with a general configuration of ITO/TPD/Alq3:2%TRPPH2/Alq3/Al were prepared. The substituted TRPPH2 was used as the host dopant, 4,4‐bis‐(m‐tolyphenylamino)biphenyl (TPD) was used as a hole‐transporting material, and aluminum tris(8‐quinolinolato) (Alq3) was used as an electron‐transporting material. The electroluminescent (EL) properties of these devices were studied to understand the light emitting properties of the substituted TRPPH2. Previous studies have found that the color emitted by the devices was dependent on the TRPPH2 dye concentration. The electronic effect of the horizontal substituents R of TRPPH2 influenced the turn‐on voltage, brightness, and power efficiency of the devices. Also, the electroluminescence performance of the porphyrin‐doped OLED devices depended on the effectual overlaps between the emission of electron‐transporting material and the absorption of the dopants. This means that it is possible to evaluate the electroluminescence performance of the porphyrin‐doped OLED devices based on the emission of electron‐transporting material and the absorption of the dopants. Copyright © 2009 John Wiley & Sons, Ltd.
Matrix isolation and magnetic parameters of septet 3,5‐dicyanopyridyl‐2,4,6‐trinitrene
Authors: Chapyshev Sergei V. , Neuhaus Patrik , Grote Dirk , Sander Wolfram 
Published: July 2010

AbstractSeptet 3,5‐dicyanopyridyl‐2,4,6‐trinitrene was synthesized together with quintet 2‐azido‐3,5‐dicyanopyridyl‐4,6‐dinitrene, quintet 4‐azido‐3,5‐dicyanopyridyl‐2,6‐dinitrene, triplet 2,6‐diazido‐3,5‐dicyanopyridyl‐4‐nitrene, and triplet 2,4‐diazido‐3,5‐dicyanopyridyl‐6‐nitrene by photolysis of 2,4,6‐triazido‐3,5‐dicyanopyridine in solid argon at 4 K. The electronic and magnetic properties of the matrix‐isolated nitrenes were studied using electron paramagnetic resonance (EPR) spectroscopy in combination with density functional theory (DFT) calculations. The fine‐structure parameters of the nitrenes were determined with high accuracy from spectral simulations. All signals in the EPR spectra of the nitrenes, randomly oriented in the solid phase, were unambiguously assigned based on eigenfield calculations of the Zeeman energy levels and angular dependences of resonance fields. Copyright © 2009 John Wiley & Sons, Ltd.
Degradation and adsorption of terbuthylazine and chlorpyrifos in biobed biomixtures from composted cotton crop residues
Authors: Kravvariti Konstantina , Tsiropoulos Nikolaos G , Karpouzas Dimitrios G 
Published: July 2010

AbstractBACKGROUND: Biobeds have been well studied in northern Europe, whereas little is known regarding their use in southern Europe. The degradation and adsorption of terbuthylazine (TA) and chlorpyrifos (CP) were studied in three different biomixtures composed of composted cotton crop residues, soil and straw in various proportions, and also in sterilised and non‐sterilised soil.RESULTS: Compost biomixtures degraded the less hydrophobic TA at a faster rate than soil, while the opposite was evident for the more hydrophobic CP. These results were attributed to the rapid abiotic hydrolysis of CP in the alkaline soil (pH 8.5) compared with the lower pH of the compost (6.6), but also to the increasing adsorption (Kd = 746 mL g−1) and reduced bioavailability of CP in the biomixtures compared with soil (Kd = 17 mL g−1), as verified by the adsorption studies.CONCLUSIONS: Compost had a dual but contrasting effect on degradation that depended on the chemical nature of the pesticide studied: a positive effect towards TA owing to increasing biodegradation and a negative effect towards CP owing to increasing adsorption. Overall, composted cotton crop residues could be potentially used in local biobed systems in Greece, as they promoted the degradation of hydrophilic pesticides and the adsorption of hydrophobic pesticides. Copyright © 2010 Society of Chemical Industry
Young caregiving and HIV in the UK: caring relationships and mobilities in African migrant families
Authors: Evans Ruth 
Published: July 2010

AbstractRecent research in Sub‐Saharan Africa has revealed the importance of children's caring roles in families affected by HIV and AIDS. However, few studies have explored young caregiving in the context of HIV in the UK, where recently arrived African migrant and refugee families are adversely affected by the global epidemic. This paper explores young people's socio‐spatial experiences of caring for a parent with HIV, based on qualitative research with 37 respondents in London and other urban areas in England. In‐depth semi‐structured interviews were conducted with young people with caring responsibilities and mothers with HIV, who were predominantly African migrants, as well as with service providers. Drawing on their perspectives, the paper discusses the ways that young people and mothers negotiate the boundaries of young people's care work within and beyond homespace, according to norms of age, gender, generational relations, and cultural constructions of childhood. Despite close attachments within the family, the emotional effects of living with a highly stigmatised life‐limiting illness, pressures associated with insecure immigration status, transnational migration, and low income undermined African mothers' and young people's sense of security and belonging to homespace. These factors also restricted their mobility and social participation in school/college and neighbourhood spaces. While young people and mothers valued supportive safe spaces within the community, the stigma surrounding HIV significantly affected their ability to seek support. The paper identifies security, privacy, independence, and social mobility as key dimensions of African young people's and mothers' imagined futures of ‘home’ and ‘family’. Copyright © 2009 John Wiley & Sons, Ltd.
From urban wastelands to new‐build gentrification: The case of Swiss cities
Authors: Rérat Patrick , Söderström Ola , Piguet Etienne , Besson Roger 
Published: July 2010

AbstractGentrification represents an important aspect of the transformation of socio‐demographic structures in many cities around the world. The definition of this concept has been extended in recent years to cover different processes of social upgrading and to incorporate a plurality of forms, protagonists, and spaces. The notion of ‘new‐build gentrification’ is part of this process of redefinition. Because of its strong connections with global socioeconomic trends, the adoption of regeneration and densification policies along with the emergence of numerous new urban districts, Switzerland offers a particularly interesting case in which to study this specific form of gentrification. In this paper, we first provide an assessment of the residential attractiveness of Swiss core cities for the middle to upper class. We then study new housing projects in Zurich and Neuchâtel. Our focus on the actors involved in these projects brings original results to the debates surrounding the driving forces behind new‐build gentrification. Empirical material is drawn from official statistics, questionnaires relating to inhabitant profiles, interviews concerned with the strategies of actors in the real‐estate market, and planning policy documents. Copyright © 2009 John Wiley & Sons, Ltd.
Luminescent and scintillation properties of CsI:Tl films grown by the liquid phase epitaxy method
Authors: Zorenko Yu. , Voznyak T. , Turchak R. , Fedorov A. , Wiesniewski K. , Grinberg M. 
Published: July 2010

AbstractCsI:Tl films have been crystallized by the liquid phase epitaxy (LPE) method from CsI:Tl (0.3 mol.%) crystalline salt onto CsI substrates. The luminescent and scintillation properties of CsI:Tl films are systematically compared with the corresponding properties of CsI:Tl (0.3 and 0.03%) crystals grown from the melt. The luminescence of CsI:Tl films and CsI:Tl (0.03%) crystals in the bands peaked at 2.52 and 2.22 eV is related to the radiative relaxation from the weak‐off and strong‐off configurations of excitons localized around Tl+ ions, respectively. Apart from single Tl+ centers, in highly doped CsI:Tl (0.3%) crystals creation of Tl+ dimer centers occurs. These centers form the additional emission bands peaked at 2.42 and 1.98 eV related to the weak‐off and strong‐off configurations of excitons localized around Tl+ dimer centers. We found that the dominant mechanism of excitation of the strong‐off luminescence of localized excitons in CsI:Tl films and crystals is the charge‐transfer transition between I– anions and Tl+ ions in single and dimer centers.
Enhancements of emission rates and efficiencies by surface plasmon coupling
Authors: Okamoto Koichi , Kawakami Yoichi 
Published: July 2010

AbstractSurface plasmon (SP) coupling technique was applied to several InGaN/GaN‐based single and multiple quantum wells (QWs) which have various emission wavelengths to understand detail mechanism and consider the possibility of plasmonic light‐emitting diodes (LEDs). The coupling efficiencies from exciton to SP and from SP to photon were estimated by the time‐resolved photoluminescence (TRPL) measurements. We found that the SP enhanced internal quantum efficiencies (IQEs) of emission reached almost 100% at the best matched wavelength. This should be applicable to super bright LEDs at any wavelength by optimizing the best SP coupling condition. Possible device structures of plasmonic LEDs were also proposed and discussed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependence of normally off mode AlGaN/GaN heterostructure field‐effect transistors with p‐GaN gate
Authors: Sugiyama Takayuki , Iida Daisuke , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu 
Published: July 2010

AbstractWe demonstrated high‐temperature operation of normally off‐mode junction‐heterostructure‐field‐effect transistors (JHFETs) with a p‐GaN gate that shows a very small shift of the threshold voltage against ambient temperature. Distinct normally off‐mode operation with a maximum drain current of 93.2 mA/mm at 300 °C was realized. Therefore, normally off‐mode GaN‐based JFETs are greatly superior to Si‐based devices as high‐temperature switching devices. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A scalable EE_HEMT based large signal model for multi‐finger AlGaN/GaN HEMTs for linear and non‐linear circuit design
Authors: Zomorrodian Valiallah , Pei Yi , Mishra Umesh K. , York Robert A. 
Published: July 2010

AbstractA scalable non‐linear large signal model based on the ADS EE_HEMT model was developed for AlGaN/GaN HEMTs for use in linear and non‐linear circuit design. Excellent agreement between simulations and measurements was obtained for the DC, small signal and large signal power and efficiency performance including load‐pull and source‐pull contours. Excellent scalability of the model was also demonstrated (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and performance analysis of high‐speed, low‐power InAs nanowire field‐effect transistors
Authors: Khayer M. Abul , Lake Roger K. 
Published: July 2010

AbstractThe performance metrics of InAs nanowire (NW) field‐effect transistors (FETs) are investigated using an analytical 2‐band model and a semiclassical ballistic transport model. The analysis of the diameter dependence of the current, gate delay, power‐delay product, and energy‐delay product of InAs NW FETs are presented. Because of their small density of states, relatively large diameter, ≤ 60 nm, InAs NW FETs operate in the quantum capacitance limit (QCL). Both the energy‐delay and power‐delay products are reduced as the diameter is reduced, and optimum designs are obtained for diameters in the range of 10 – 40 nm. Power‐delay product varies from 2 × 10–20 J to 63 × 10–20 J for all devices with a source Fermi level range of 0.1 – 0.2 eV. The gate delay time for all devices varies from 4 – 16 fs and decreases as the NW diameter increases. These NW FETs provide both ultra‐low power switching and high‐speed (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High frequency performance of Ga free barrier AlInN/GaN HEMT
Authors: Crespo A. , Bellott M. , Chabak K. , Gillespie J. K. , Jessen G. H. , Kossler M. , Trimble V. , Trejo M. , Via G. D. , Winningham B. , Smith H. E. , Walker D. , Cooper T. , Gao X. , Guo S. 
Published: July 2010

AbstractIn this work we present the highest frequency performance reported to date of an AlInN/GaN HEMT with a 2×150 μm configuration. The frequency performance reached was of a measured fT of 107 GHz and an fmax of 89.5 GHz. The device has an IDSS of 1.1 A/mm at a VGS of 0 V, an Imax of 1.3 A/mm at VGS of 1 V, and a gm‐peak of 395 mS/mm. The gate length, LG, was 122 nm and a total barrier thickness, tbar, of 10.1 nm. This gives us an LG/tbar ratio of 12.1 with a high ft·LG product of 13 GHz·μm. The thin barrier thickness greatly contributed to the high frequency performance of the device by reducing the short channel effects. The contact resistance of a TLM structure next to the tested device is 0.42 Ω·mm. The epitaxial layer was grown by MOCVD on a 3” SiC substrate. Hall measurements, after passivation, revealed an average material sheet resistance, Rsheet, of 219 Ω/□, a sheet carrier concentration of 2.2×1013cm‐2, and a mobility of 1320 cm2/V‐s. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cryptolepine, isolated from Sida acuta, sensitizes human gastric adenocarcinoma cells to TRAIL‐induced apoptosis
Authors: Ahmed Firoj , Toume Kazufumi , Ohtsuki Takashi , Rahman Mahmudur , Sadhu Samir Kumar , Ishibashi Masami 
Published: July 2010

AbstractBioassay guided separation of Sida acuta whole plants led to the isolation of an alkaloid, cryptolepine (1), along with two kaempferol glycosides (2–3). Compound 1 showed strong activity in overcoming TRAIL‐resistance in human gastric adenocarcinoma (AGS) cells at 1.25, 2.5 and 5 μm. Combined treatment of 1 and TRAIL sensitized AGS cells to TRAIL‐induced apoptosis at the aforementioned concentrations. Copyright © 2010 John Wiley & Sons, Ltd.
Testing for qualitative interactions between stages in an adaptive study
Authors: Parker Robert A. 
Published: July 2010

AbstractI consider the underlying structure for a test of qualitative interaction of a treatment when assessing heterogeneity between stages in an adaptive trial. Since decisions about the clinical utility of a drug are based on the balance of risks and benefits, a quantitative interaction in treatment efficacy across different groups could lead to qualitatively different decisions. Thus, the difference between quantitative and qualitative interactions is not a true dichotomy. I show that the standard tests for qualitative interactions (Gail and Simon,Biometrics1985; 41:361–372; Piantadosi and Gail,Statist. Med.1993; 12:1239–1248) are very conservative in this application. Theoretical calculations in a simpler situation confirm that the published criteria are very conservative, which may help explain why the tests are known to have very low power to detect interaction. I introduce the concept of ‘minimum detectable effect’, which is the smallest effect that a study could identify as statistically significant. I propose that important heterogeneity between stages in an adaptive trial be identified when two criteria are met. First, at least one individual stage must be below the overall study mean by at least the minimum detectable effect. Second, using an appropriate critical value based on simulations, there must be statistically significant heterogeneity between the stages. Copyright © 2009 John Wiley & Sons, Ltd.
Regression analysis applied to PVC histories: A Statistical procedure for evaluating antiarrhythmic drug efficacy
Authors: Berry Donald A. , Fox Terrance L. 
Published: July 2010

AbstractSuppression of premature ventricular contractions (PVCs) is one of the goals of antiarrhythmic therapy. In a clinical trial, however, it may be difficult to distinguish antiarrhythmic drug effect from spontaneous variation in PVCs. We propose the application of linear regression to PVC histories to ascertain drug effect in individual patients. The model determines which variables are important in explaining a patient's PVCs. One such variable indicates the presence or absence of the drug; the model determines whether the drug has an effect on the patient's PVCs, while compensating for the other explanatory variables. In addition to determining the statistical significance of any drug effect, the model estimates the strength of the effect for each patient. We demonstrate the method with data from a three‐day clinical trial which used 24‐hour Holter monitoring. The method is flexible and can be modified to apply to any clinical study design. It allows for inferences concerning populations and subpopulations of patients.
A Comparison of two methods for calculating expected mortality
Authors: Hartz Arthur J. , Giefer Eldred E. , Hoffmann Raymond G. 
Published: July 2010

AbstractA number of statistics based on person‐years of survival have use in mortality studies. However, calculation of an expected number of deaths based on person‐years of survival and standard death rates cannot be justified. We derive a new method to estimate expected mortality based on a model which assumes that each individual contributes to expected mortality from the time he enters the study until the study ends, regardless of whether he dies during the study. This model shows that what is referred to as expected mortality in the person‐years method is a biased estimate of expected mortality. The variance of observed mortality under this new model is substantially less than the variance commonly used with the person‐years method.
A Method for determining the sampling ratio in epidemiologic studies
Authors: Morgenstern Hal , Winn Deborah M. 
Published: July 2010

AbstractThis paper presents a new method for determining the optimal sampling ratio and sample size in different types of study designs involving binary exposure and disease variables. The sampling ratio is optimized by maximizing cost efficiency, which is the ratio of the precision in effect estimation to the total sampling cost. One may easily compute the optimal sampling ratio with a hand calculator, and it is independent of the sample sizes of the compared groups. Optimal sample sizes obtain from use of the optimal sampling ratio in the appropriate asymptotic power function for comparing two proportions or rates with unequal sample sizes. We illustrate the method with a case‐control design, compare it with other methods for optimizing the sampling strategy, and discuss it in a practical context.
Adolescent girls' experiences of underlying social processes triggering stress in their everyday life: a grounded theory study
Authors: Haraldsson Katarina , Lindgren Eva‐Carin , Mattsson Bengt , Fridlund Bengt , Marklund Bertil 
Published: July 2010

AbstractThe aim of this study was to generate a theoretical model of underlying social processes that trigger stress in adolescent girls' everyday life. In‐depth interviews regarding the experiences of stress at home, school and during leisure time were conducted with 14 17‐year‐old schoolgirls. Data were analysed by means of the grounded theory method. Stress was triggered in the interaction between responsibility and the way in which the girls were encountered. Triggered emotional reactions took the form of four dimensions of stress included ambivalence, frustration, despair and downheartedness. These reactions were dependent on whether the girls voluntary assumed responsibility for various situations or whether they were forced, or felt they were being forced, to assume responsibility in interaction with an encounter characterized by closeness or distance. These forms of stress reactions could appear in one dimension and subsequently shift to another. From the public health perspective, the generated stress model can be used in the planning and implementation of future actions to prevent stress and promote well‐being related to stress in adolescent girls. Copyright © 2010 John Wiley & Sons, Ltd.