bluuebunny/crossref_metadata_2025_split huggingface dataset:
High solubility, low‐dielectric constant, and optical transparency of novel polyimides derived from 3,3′,5,5′‐tetramethyl‐4,4′‐diaminodiphenyl‐4″‐isopropyltoluene
Authors: Wang Chen‐Yi , Li Guang , Zhao Xiao‐Yan , Jiang Jian‐Ming 
Published: May 2009

AbstractA series of novel polyimides (PIs) (3a–d) were prepared from 3,3′,5,5′‐tetramethyl‐4,4′‐diaminodiphenyl‐4″‐isopropyltoluene (1) with four aromatic dianhydrides via a one‐step high temperature polycondensation procedure. The obtained PIs showed excellent solubility, with most of them dissoluble at a concentration of 10 wt % in amide polar solvents and chlorinated solvents. Their films were nearly colorless and exhibited high‐optical transparency, with the UV cutoff wavelength in the range of 328–353 nm and the transparency at 450 nm >80%. They also showed low‐dielectric constant (2.49–2.94 at 1 MHz) and low‐water absorptions (0.44–0.65%). Moreover, these PIs possessed high‐glass transition temperatures (Tg) beyond 327 °C and excellent thermal stability with 10% weight loss temperatures in the range of 530–555 °C in nitrogen atmosphere. In comparison with some fluorinated poly(ether imide)s derived from the trifluoromethyl‐substituted bis(ether amine)s, the resultant PIs 3a–d showed better solubility, lower cutoff wavelength, and higher Tg. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3309–3317, 2009
Dual responsive poly(N‐isopropylacrylamide) hydrogels having spironaphthoxazines as pendant groups
Authors: Kulawardana Erandimala U. , Kuruwita‐Mudiyanselage Thilini , Neckers Douglas C. 
Published: May 2009

AbstractStimuli responsive hydrogels (PNIPAAm‐MSp) with a thermoresponsive backbone and photochromic pendant groups were synthesized via free radical polymerization using N‐isopropylacrylamide, modified spironaphthoxazines with a polymerizable double bond (MSp) as photochromic monomer, the crosslinker N,N′‐methylenebis(acrylamide) and the initiator 2,2′‐azobis(isobutyronitrile) in dimethylsulfoxide. The polymers are dual responsive, in that poly(N‐isopropylacrylamide) (PNIPAAm) responds to temperature changes whereas the pendant spironaphthoxazines respond to light. Irradiation enhanced the water absorption of the polymers while increases in temperature decreased it. The irradiated PNIPAAm‐MSp showed best water absorption at 0 °C (Q = 3.25) while water desorbed at higher temperatures (35 °C; Q = 0.30); where Q is the amount of water absorbed by a gram of dry polymer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3318–3325, 2009
Temperature dependent relaxation of a “solid–liquid”
Authors: Goertz M. P. , Zhu X.‐Y. , Houston J. E. 
Published: May 2009

AbstractWe have used the Interfacial Force Microscope to perform temperature dependent indentation measurements on a model viscoelastic material, Silly Putty. By transforming time dependent stress relaxations into frequency dependent modulus, we can identify the temperature dependence of the elastic and viscous response of an experimentally challenging material. This technique promises to be useful in determining the mechanical properties of composite materials with microscopic spatial resolution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1285–1290, 2009
Thermal degradation and kinetic analysis of biodegradable PBS/multiwalled carbon nanotube nanocomposites
Authors: Shih Yeng‐Fong 
Published: May 2009

AbstractIn this study, carbon nanotubes (CNTs) were first modified using N,N′‐ dicyclohexylcarbodiimide (DCC) dehydrating agents. Subsequently, the poly(butylene succinate)/multiwalled carbon nanotube (PBS/MWNTs) nanocomposites were prepared through facile melt blending. Thermal degradation of these PBS/MWNT nanocomposites was investigated; the kinetic parameters of degradation were calculated using the Coats and Redfern, Ozawa, and Horowitz and Metzger methods, respectively. It was found that the degradation reaction mechanism of PBS and the CNT‐C18 containing nanocomposites at lower temperature was likely to produce an F1 model through reaction of random chain cleavage (cis‐elimination). However, the reaction mechanism at higher temperature was likely to be a D1 model because of the dominant diffusion control effect. Moreover, it was found that the activation energies of CNT‐C18‐containing PBS nanocomposites were first increased with the content of CNT‐C18, but then decreased after the content was larger than 0.5 wt % for all models at differing heating rates. This may be due to the formation of a conductive network of CNTs in the polymer matrix at higher content of CNTs, which lead to better heat and electrical conductivity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1231–1239, 2009
Remote Plasma Device for Surface Modification at Atmospheric Pressure
Authors: Reichen Patrick , Sonnenfeld Axel , Rudolf von Rohr Philipp 
Published: May 2009

AbstractHere, a novel atmospheric plasma device is presented, which applies the (remote) afterglow of micro‐barrier discharges. The study evaluates its applicability to surface modification of temperature‐sensitive particulates. As such, cylindrical samples have been placed in the remote treatment zone of the device, and the effects of treatment time and variable gas mixtures on the surface wettability are investigated. Furthermore, the influence of the excess voltage in He discharge with admixtures of O2, CO2 and N2 and the effect thereof on the water contact angle is described.
Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc
Authors: Endrino Jose Luis , Horwat D. , Anders A. , Andersson J. , Gago R. 
Published: May 2009

AbstractThe influence of annealing in argon at 300 °C on the conductivity, phase stability and electronic structure of hydrogen‐free amorphous carbon (a‐C) films containing copper (a‐C:Cu) and gold (a‐C:Au) nanoclusters was investigated. The motivation of this work is twofold: (1) to study the thermal stability of a‐C:Cu and a‐C:Au films and (2) to point out the relevance of X‐ray absorption near edge structure (XANES) technique to study the structural evolution of metal‐doped a‐C nanocomposites. The films were produced at room temperature using a selective‐bias pulsed dual‐cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas grazing incidence X‐ray diffraction (GIXRD) was used to monitor phase transformation and identify the dispersion or agglomeration of the crystallites within the carbon matrix. XANES spectra at the C‐K was used to investigate the effect of annealing in argon on the electronic structure of the a‐C matrix, while Cu K and Au L‐edges were investigated on a‐C:Cu and a‐C:Au samples, respectively, to study the nanocluster evolution. XANES showed that the a‐C host matrix increased its graphitic character and that stress was relieved upon annealing. No relevant changes were observed in the Au arrangements in a‐C:Au films. In the case of the a‐C:Cu samples, the Cu‐K XANES spectra indicated the formation of Cu2O crystals which correlated well with GIXRD spectra and the decrease in conductivity.
SiOx‐Based Multilayer Barrier Coatings Produced by a Single PECVD Process
Authors: Patelli Alessandro , Vezzù Simone , Zottarel Lorenzo , Menin Enrico , Sada Cinzia , Martucci Alessandro , Costacurta Stefano 
Published: May 2009

AbstractMultilayer organic/inorganic gas barrier coatings on plastics are needed for high performance demanding applications from OLEDs to packaging. In order to simplify the multilayer deposition process, we developed a single step vacuum process where silicon oxide‐based PECVD multilayers are obtained by the modulation of the hexamethyldisiloxane (HMDSO) precursor inlet and interfaces are controlled by pumping speed. In this way, depending on O2/HMDSO ratio, ‘ceramic’ or ‘polymeric’ layers are deposited, with nanometre control of thickness of layers and interfaces. Permeability behaviour of the multilayer structures obtained is described as a function of the number of layers and their thickness.
Molecular modeling of flexible arm‐mediated interactions between bacterial chemoreceptors and their modification enzyme
Authors: Muppirala Usha K. , Desensi Susan , Lybrand Terry P. , Hazelbauer Gerald L. , Li Zhijun 
Published: May 2009

AbstractSensory adaptation in bacterial chemotaxis is mediated by methylation and demethylation of specific glutamyl residues in the cytoplasmic domain of chemoreceptors. Methylation is catalyzed by methyltransferase CheR. In E. coli and related organisms, methylation sufficiently rapid to be physiologically effective requires a carboxyl terminal pentapeptide sequence on the receptor being modified or, via adaptational assistance, on a neighboring homodimer in a receptor cluster. Pentapeptide‐enhanced methylation is thought to be mediated by a ∼30 residue, potentially disordered sequence that serves as a flexible arm connecting the receptor body and pentapeptide‐bound methyltransferase, thus allowing diffusionally restricted enzyme to reach methyl‐accepting sites. However, it was not known how many or which sites on the same or neighboring receptors were accessible to the tethered enzyme. We investigated using molecular modeling and found that, in a hexagonal array of trimers of receptor dimers, CheR tethered to a dimer of chemoreceptor Tar by its native 30‐residue flexible‐arm sequence could reach all methyl‐accepting sites on the dimer to which it was tethered plus 48 methyl‐accepting sites distributed among nine neighboring dimers, equivalent to the total sites carried by six receptors. This modeling‐determined methylation neighborhood of one enzyme‐binding dimer and six neighbors corresponds precisely with the experimentally identified neighborhood of seven. Thus, the experimentally observed adaptational assistance can occur by docking of pentapeptide‐bound, diffusionally restricted enzyme to methyl‐accepting sites on neighboring receptors. Our analysis introduces the notion that physiologically relevant adaptational assistance could occur even if only a subset of sites on a particular receptor are within reach.
Vibrational spectroscopic investigation of the ligand binding domain of kainate receptors
Authors: Du Mei , Rambhadran Anu , Jayaraman Vasanthi 
Published: May 2009

AbstractFourier transform infrared spectroscopy has been used to probe the agonist‐protein interactions in the ligand binding domain of the GluR6 subunit, one subunit of the kainate subtype of glutamate receptors. In order to study the changes in the interactions over a range of activations the investigations were performed using the wild type, N690S, and T661E mutations. These studies show that the strength of the interactions at the α‐amine group of the agonist, as probed by studying the environment of the nondisulphide bonded Cys 432, acts as a switch with weaker interactions at lower activations and stronger interactions at higher activations. The α‐carboxylate interactions of the agonist, however, are not significantly different over the wide range of activations, as measured by the maximum currents mediated by the receptors at saturating concentrations of agonists. Previous investigations of AMPA receptors show a similar dependence of the α‐amine interactions on activation indicating that the roles of the α‐amine interactions in mediating receptor activation are similar for both subtypes of receptors; however, in the case of the AMPA receptors a tug of war type of change was observed between the α‐amine and α‐carboxylate interactions and this is not observed in kainate receptors. This decoupling of the two interactions could arise due to the larger cleft observed in kainate receptors, which allows for a more flexible interaction for the α‐amine and α‐carboxylate groups of the agonists.
Development of insect‐resistant transgenic rice with Cry1C*‐free endosperm
Authors: Ye Rongjian , Huang Haiqun , Yang Zhou , Chen Taiyu , Liu Li , Li Xianghua , Chen Hao , Lin Yongjun 
Published: May 2009

AbstractBACKGROUND: Yellow stem borer (Tryporyza incertulas Walker), striped stem borer (Chilo suppressalis Walker) and leaf folder (Cnaphalocrocis medinalis Guenec) are three lepidopteran pests that cause severe damage to rice in many areas of the world. In this study, novel insect‐resistant transgenic rice was developed in which Bt protein expression was nearly absent in the endosperm. The resistant gene, cry1C*, driven by the rice rbcS promoter (small subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase), was introduced into Zhonghua 11 (Oryza sativa L. ssp. japonica) by Agrobacterium‐mediated transformation.RESULTS: A total of 83 independent transformants were obtained, 19 of which were characterised as single‐copy foreign gene insertion. After preliminary screening of the T1 families of these 19 transformants in the field, six highly insect‐resistant homozygous lines were selected. These six homozygous transgenic lines were field tested for resistance to leaf folders and stem borers, and for their agronomic performance. The Cry1C* protein levels in leaves and endosperm were measured by ELISA. Subsequently, the elite transgenic line RJ5 was selected; this line not only possessed high resistance to leaf folders and stem borers, normal agronomic performance, but also Cry1C* expression was only 2.6 ng g−1 in the endosperm.CONCLUSION: These results indicated that RJ5 has the potential for widespread utility in rice production. Copyright © 2009 Society of Chemical Industry
Susceptibility to insecticides in the Q biotype of Bemisia tabaci is correlated with bacterial symbiont densities
Authors: Ghanim Murad , Kontsedalov Svetlana 
Published: May 2009

AbstractBACKGROUND: The presence of symbiotic microorganisms may influence an insect's ability to tolerate natural and artificial stress agents such as insecticides. The authors have previously shown that Rickettsia in the B biotype of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) increases this insect's susceptibility to several insecticidal compounds. This communication reports a comparison of the susceptibilities of three isofemale strains of the Q biotype of B. tabaci harbouring different bacterial complements to major insecticides from different chemical groups: one strain harboured only Arsenophonus, one harboured Rickettsia and Arsenophonus and one harboured Arsenophonus and Wolbachia.RESULTS: The presence of different symbiont combinations in the three strains had a significant influence on their susceptibility to most of the insecticides tested. Thiamethoxam, imidacloprid, pyriproxyfen and spiromesifen had a significant influence on strains that had the double infections Rickettsia–Arsenophonus and Wolbachia–Arsenophonus, which also carried higher amounts of symbionts as assessed by quantitative real‐time PCR. No significant differences in mortality rates were observed when the tested strains were treated with diafenthiuron.CONCLUSION: The results suggest a correlation between the presence of high bacterial densities in B. tabaci and the insect's ability to detoxify toxic compounds such as insecticides. Copyright © 2009 Society of Chemical Industry
Depth profiles of ceramic tiles by using orthogonal double‐pulse laser induced breakdown spectrometry
Authors: Čtvrtníčková T. , Fortes F. J. , Cabalín L. M. , Kanický V. , Laserna J. J. 
Published: May 2009

AbstractThe potential of a double pulse (DP) excitation scheme for in‐depth characterization of ceramic samples using laser induced breakdown spectrometry (LIBS) has been demonstrated. For this purpose, two Q‐switched Nd:YAG lasers in orthogonal configuration were employed, the first one to ablate the sample (1064 nm) and the second one (532 nm) to excite the ablated material. Light emission was collected by a spectrograph and detected by an intensified charge‐coupled device (CCD) detector. Optimal conditions such as relative laser beam positions, laser pulse energies, inter‐pulse separation and CCD delay time were studied. Depth profiles were evaluated on the basis of various elemental compositions in both layers of ceramic samples. The depth resolution with DP configuration was improved by almost twofold as compared to the single‐pulse approach. The reproducibility of the depth profiles is also twice better with double pulse LIBS. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of maleic anhydride‐grafted polytetrafluoroethylene on the tensile and tribological properties of blending polytetrafluoroethylene with polyamide‐6
Authors: Li J. , Xia Y. C. 
Published: May 2009

AbstractBlending polytetrafluoroethylene (PTFE) to polyamide‐6 (PA6) with and without maleic anhydride‐grafted polytetrafluoroethylene (PTFE‐g‐MA) was produced in a corotating twin screw extruder, where PTFE acts as the polymer matrix and PA6 as the dispersed phase. The effect of PTFE‐g‐MA on the tensile properties and tribological propertiesof PTFE/PA6 polymer blends is studied. Results show that the structural stability and morphology of the blends were greatly improved by PTFE‐g‐PA6 grafted copolymers, which were formed by the in situ reaction of anhydride groups with the amino end groups of PA6 during reactive extrusion forming an imidic linkage. The presence of PTFE‐g‐PA6 in the PTFE continuous phase improves the interfacial adhesion, as a result of the creation of an interphase that was formed by the interaction between the formed PTFE‐g‐PA6 copolymer in situ and both phases. Compared with thePTFE/PA6 without PTFE‐g‐MA, the PTFE/PA6 with PTFE‐g‐MAhad the lowest friction coefficient and wear under given applied load and reciprocating sliding frequency. The interfacial compatibility of the composite prevented the rubbing‐off of PA6, accordingly improved the friction and wear properties of the composite. Copyright © 2009 John Wiley & Sons, Ltd.
Adsorption and separation of light alkane hydrocarbons by porous hexacyanocobaltates (III)
Authors: Autie‐Castro G. , Autie M. , Reguera E. , Santamaría‐González J. , Moreno‐Tost R. , Rodríguez‐Castellón E. , Jiménez‐López A. 
Published: May 2009

AbstractThe adsorption and separation of light n‐alkane hydrocarbons (propane, butane, pentane, hexane and heptane) by zinc and cadmium hexacyanocobaltates (III) were studied from inverse gas chromatographic data. These two solids are representative of the porous frameworks found for transition metals hexacyanometallates. For cadmium, the porous framework is related to the presence of systematic vacancies for the building block, [Co(CN)6], while for Zn it is a consequence of a tetrahedral coordination for the Zn atom. These linear light hydrocarbons (paraffins) are effectively separated by these two porous frameworks. The involved differential adsorption heats and the related separation coefficients were estimated from the recorded chromatographic data. No significant differences for the separation ability of light n‐alkane hydrocarbons by the evaluated materials were observed. Copyright © 2009 John Wiley & Sons, Ltd.
Fetal anatomic evaluation in the overweight and obese gravida
Authors: Thornburg L. L. , Miles K. , Ho M. , Pressman E. K. 
Published: May 2009

AbstractObjectivesTo evaluate the rate of completion of anatomic surveys of fetuses in overweight and obese gravid patients as compared with normal controls.MethodsThis was a retrospective review of anatomic ultrasound scans performed between 2004 and 2007. Women were stratified by prepregnancy body mass index (BMI) into normal weight (BMI, 18.5–24.9 kg/m2), overweight (BMI, 25.0–29.9 kg/m2) and obese Class I (BMI, 30.0–34.9 kg/m2), Class II (BMI, 35.0–39.9 kg/m2) and Class III (BMI ≥ 40.0 kg/m2) groups. Rates of completion of basic and comprehensive scans, gestational age at completion and number of scans required were compared.ResultsFor the 7140 patients included, completion rates for both the basic (normal weight, n = 2253 (79%); overweight, n = 1771 (76%); obese Class I, n = 767 (72%), Class II, n = 323 (61%) and Class III, n = 171 (49%)) and comprehensive (normal weight, n = 1234 (43%); overweight, n = 930 (40%); obese Class I, n = 404 (38%), Class II, n = 215 (41%) and Class III, n = 108 (31%)) surveys decreased significantly with increasing BMI (P < 0.00001). For surveys completed, the mean number of scans required was significantly higher for obese patients (basic: normal weight 1.3 vs. obese Class III 1.9; comprehensive: normal weight 1.7 vs. obese Class III, 2.2)(P < 0.00001). The overall completion rate improved at each gestational week, but was best between 20 and 23 weeks for obese patients.ConclusionsAs maternal BMI increases, the rate of completion of anatomic surveys decreases and the number of scans required increases. Delaying the initial survey until 20 weeks' gestation may improve the capacity to complete the examination in a single visit. It should be noted that these results represent completion rates at a tertiary referral center, and therefore may not reflect community experience. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Rotatable Magnetron Sputter Technologyfor Large Area Glass and Web Coating
Authors: Blondeel Anja , Persoone Peter , De Bosscher Wilmert 
Published: May 2009

AbstractOver the last few decades, magnetron sputtering has become a major coating technology for depositing high quality thin films. The ease of scalability, while maintaining excellent control of all crucial layer parameters, made it appropriate for large area substrates and high mass productivity. The introduction of the rotating cylindrical magnetron concept in the nineties has further contributed to the success of sputtering in large area coating of rigid and flexible substrates. The rotatable sputtering technology does not only contribute significantly to a reduction in cost‐of‐ownership (higher target material consumption, more system throughput and up‐time …), it opens new perspectives in advanced coating applications where tolerances are narrow and requirements are high.In this paper, we will discuss the advantages of using rotatable target technology in large area coaters, whereby we will focus on the issues related to the sputter deposition on rigid and flexible substrates.
The Effect of BRCA Gene Testing on Family Relationships: A Thematic Analysis of Qualitative Interviews
Authors: Douglas Heather A. , Hamilton Rebekah J. , Grubs Robin E. 
Published: May 2009

AbstractDiscovery of mutations in the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2 can have emotional consequences for both the tested individual and his or her relatives. This secondary analysis study investigated how BRCA testing impacts family dynamics and relationships. For the original study, a grounded theory inquiry, participants were recruited from a hereditary breast/ovarian cancer syndrome support website and open‐ended interviews were performed asking about individual and family experiences after BRCA testing. All 12 participants whose interviews were included in the secondary analysis had a BRCA mutation. For the secondary analysis, thematic analysis was conducted and revealed three main themes characterizing the effect of BRCA testing on family relationships: 1. That the first in the family to have testing or seek genetic counseling takes on a special family role that can be difficult for them; 2. That discussions in the family often change; and 3. That individuals may feel more or less connected to certain family members. These changes seemed to relate to family cancer history, relationships, coping strategies, communication patterns, and mutation status. Genetic counselors might find it useful to explore these issues in order to prepare clients before BRCA testing and to support them through shifts in family dynamics after disclosure of results.