bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion‐controlled radiochemical oxidation of bisphenol A polysulfone
Authors: Richaud Emmanuel , Colin Xavier , Monchy‐Leroy Carole , Audouin Ludmila , Verdu Jacques 
Published: November 2010

AbstractThe radiochemical degradation of bisphenol A polysulfone was investigated under a γ‐ray dose rate of 24 kGy h−1 up to 30.7 MGy total absorbed dose at 60 °C using gel permeation chromatography, sol–gel analysis, glass transition and rheometry measurements, and oxidation profile measurements by microscopy coupled with Fourier transform infrared analysis in attenuated total reflectance mode. Thin (200 µm) and thick (2 mm) samples were compared. Thin samples undergo mainly chain scissions whereas thick ones undergo mainly crosslinking. The thickness of oxidized layers and, radiochemical yields for chain scissions, crosslinking, oxygen absorption and radical formation were tentatively determined from experimental data in order to determine the influence of oxidative processes on radiochemical ageing and to establish the nature of the crosslinking reactions. Copyright © 2010 Society of Chemical Industry
Synthesis of rosin‐based imidoamine‐type curing agents and curing behavior with epoxy resin
Authors: Wang Honghua , Wang Haiwei , Zhou Guangyuan 
Published: November 2010

AbstractRosin is an abundantly available natural product. The characteristic fused ring structure of rosin acids is analogous to that of some aromatic compounds in rigidity, and makes rosin and its derivatives potential substitutes for those aromatic compounds. In the study reported, the synthesis of biobased curing agents containing imide structure using rosin and the cure reaction were investigated. Rosin‐based imidoamine‐type curing agents were synthesized, and the chemical structure was confirmed using 1H NMR, Fourier transform infrared and electrospray ionization spectroscopy. The curing behavior with diglycidyl ether of bisphenol A epoxy was studied using differential scanning calorimetry. The thermal mechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis and thermogravimetry, respectively. The results indicate that the curing behavior of the rosin‐based curing agents is similar to that of curing agents with analogous structures. Cured products have good thermal stability due to the presence of the imide group and the bulky hydrogenated phenanthrene ring structure. Rosin acids have a great potential in the synthesis of epoxy curing agents as replacements for some of the current commercial aromatic or cycloaliphatic analogues. Copyright © 2010 Society of Chemical Industry
Novel poly(thiourea‐ether‐imide)s derived from 4,4′‐oxydiphenyl‐bis(thiourea): probing the possibility for high‐temperature applications
Authors: Kausar Ayesha , Zulfiqar Sonia , Ali Liaquat , Ishaq Muhammad , Ilyas Sarwar Muhammad 
Published: November 2010

AbstractOur interest in the fabrication of high‐performance polyimides has led to thiourea‐substituted poly(thiourea‐ether‐imide)s (PTEIs) with good retention of thermal properties along with flame retardancy. A new aromatic monomer, 4,4′‐oxydiphenyl‐bis(thiourea) (ODPBT), was efficiently synthesized and polymerized with various dianhydrides (pyromellitic dianhydride, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene)diphthalic dianhydride) via two‐stage chemical imidization to fabricate a series of PTEIs. The structural characterization of ODPBT and the polymers was carried out using Fourier transform infrared, 1H NMR and 13C NMR spectral techniques along with crystallinity, organosolubility, inherent viscosity and gel permeation chromatographic measurements. PTEIs bearing CS and Omoieties in the backbone demonstrated an amorphous nature and were readily soluble in various amide solvents. The novel polymers had inherent viscosities of 1.16–1.23 dL g−1 and molecular weights of ca 90 783–96 927 g mol−1. Their thermal stability was substantiated via 10% weight loss in the temperature range 516–530 °C under inert atmosphere. The polyimides had glass transition temperatures of 260–265 °C. Incorporation of thiourea functionalities into polymer backbones is demonstrated to be an effective way to enhance their thermal properties and flame retardancy. Thus, ODPBT can be considered as an excellent candidate for use in the synthesis of high‐performance polymeric materials. Copyright © 2010 Society of Chemical Industry
Life‐cycle greenhouse gas effects of introducing nano‐crystalline materials in thin‐film silicon solar cells
Authors: van der Meulen Rob , Alsema Erik 
Published: November 2010

AbstractSolar PV is widely considered as a “green” technology. This paper, however, investigates the environmental impact of the production of solar modules made from thin‐film silicon. We focus on novel applications of nano‐crystalline Silicon materials (nc‐Si) into current amorphous Silicon (a‐Si) devices. Two nc‐Si specific details concerning the environmental performance can be identified, when we want to compare to a‐Si modules. First, in how far the extra (and thicker) silicon layer (s) affects upstream material requirements and energy use. Second, in how far depositing an extra silicon layer may increase emissions of greenhouse gases as additional emissions of Fluor gases (F‐gases) are associated to this step. The much larger global warming potential of F‐gases (17 200–22 800 times that of CO2) may lead to higher environmental burdens. To date, no study has yet analyzed the effect of F‐gas usage on the environmental profile of thin‐film silicon solar modules. We performed a life‐cycle assessment (LCA) to investigate the current environmental usefulness of pursuing this novel micromorph concept. The switch to the new micromorph technology will result in a 60–85% increase in greenhouse gas emissions (per generated kWh solar electricity) in case of NF3 based clean processing, and 15–100% when SF6 is used. We conclude that F‐gas usage has a substantial environmental impact on both module types, in particular the micromorph one. Also, micromorph module efficiencies need to be improved from the current 8–9% (stabilized efficiency) toward 12–16% (stab. eff.) in order to compensate for the increased environmental impacts. Copyright © 2010 John Wiley & Sons, Ltd.
Radiation induced oxidation of hydroxy indoles by NO and Br radicals: effect of pH
Authors: Gaikwad P. , Naik G. H. , Priyadarsini K. I. , Mohan H. , Rao B. S. M. 
Published: November 2010

AbstractThe reactions of NOand Brradicals with 5‐hydroxyindole (HIn), 5‐hydroxytryptophol (HTpl), 5‐hydroxytryptophan (HTpn) and 5‐hydroxytryptamine (HTpe) were studied using pulse radiolysis. The rate constants for their reaction with NOradical were found to vary from 105to 107 dm3 mol−1 s−1in the pH range 5–9 but a higher value (k = 1.4 ± 0.01 × 108 dm3 mol−1 s−1) was noticed in HTpe at pH 9. The gradual increase in reactivity with pH is due to the decrease in the reduction potentials of indoloxyl radicals withE = 0.55 V at pH 9. In contrast, the rate constants with Brradical were found to be diffusion controlled and remained unaffected by the pH. The transient spectra measured are attributed to the indoloxyl radical formed on oxidation withλmaxat 420 nm. The indoloxyl radicals further react with the parent hydroxy indole derivative forming the radical adduct and their decay was found to be pH dependent in derivatives containing an amino group. At pH 5, no decay of the radical adducts was seen in all derivatives up to 5 ms whereas those with the amino group decayed faster at pH 9. The total yields of the oxygen centred and carbon centred radicals formed in the reaction of NOradical with hydroxy indoles were found to be nearly equal to G(NO). Our results suggest that NOradical is inefficient in oxidizing hydroxy indoles under physiological conditions preventing the formation of toxic dimers of indole derivatives. Copyright © 2010 John Wiley & Sons, Ltd.
Conformational analysis of N‐phenyl‐ and N‐trifyl‐4,4‐dimethyl‐4‐silathiane 1‐sulfimides
Authors: Shainyan Bagrat A. , Suslova Elena N. , Kleinpeter Erich 
Published: November 2010

AbstractN‐Substituted 4,4‐dimethyl‐4‐silathiane 1‐sulfimides [R = Ph (1), CF3 (2)] were studied experimentally by variable temperature dynamic NMR spectroscopy. Low temperature 13C NMR spectra of the two compounds revealed the frozen ring inversion process and approximately equal content of the axial and equatorial conformers. Calculations of the 4‐silathiane derivatives 1, 2 and the model compound [R = Me (3)] as well as their carbon analogs, the similarly N‐substituted thiane 1‐sulfimides [R = Ph (4), CF3 (5), Me (6)] at the DFT/B3LYP/6–311G(d,p) level in the gas phase and in chloroform solution using the PCM model at the same level of theory showed a strong dependence of the relative stability of the conformer on the solvent. The electronegative trifluoromethyl group increases the relative stability of the axial conformer. Copyright © 2010 John Wiley & Sons, Ltd.
Enhanced Autohesive Bonding of Polyetheretherketone (PEEK) for Biomedical Applications Using a Methane/Oxygen Plasma Treatment
Authors: Awaja Firas , Zhang Shengnan , James Natalie , McKenzie David R. 
Published: November 2010

AbstractHigh performance polymers such as PEEK are currently considered unsuitable for the encapsulation of biomedical implants, partly because of a lack of a strong and durable bonding technology. Strong autohesive bonds were achieved between semi‐crystalline PEEK surfaces using a treatment in RF plasma with a mixture of methane and oxygen (CH4/O2) gases. The surfaces were bonded under pressure above the glass transition temperature (Tg) and below the melting point (Tm). The treatment with CH4/O2 gases produced significantly higher bond strength than untreated samples and samples treated with CH4 only. The CH4/O2 plasma treatments generated a higher polar component of surface energy than observed for the untreated surfaces and also higher than that observed for surfaces plasma treated in CH4 alone. XPS analysis of surfaces treated with CH4/O2 plasma for more than 3 min showed that oxygenated nano‐films were deposited that contained CO groups and these showed the highest bonding strength. Free radical induced cross‐linking of the deposited nano‐film is proposed as a mechanism to explain the high bond strength achieved.
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Chemical and Morphological Characterization of Low‐k Dielectric Films Deposited From Hexamethyldisiloxane and Ethylene RF Glow Discharges
Authors: Coclite Anna Maria , Milella Antonella , Palumbo Fabio , Fracassi Francesco , d'Agostino Riccardo 
Published: November 2010

AbstractLow‐k dielectric films were deposited by PECVD from mixtures of hexamethyldisiloxane (HMDSO), ethylene, and oxygen. After deposition the films were thermally annealed in order to reduce their permittivity. Different deposition conditions were investigated in order to accomplish the best trade‐off between low permittivity and low thickness loss upon annealing. Soft plasma conditions were required in order to allow organic species incorporation in the film and achieve dielectric constant as low as 2.2 with a thickness loss of 14% upon thermal annealing treatment. Results were also compared to those obtained with divinyltetramethyldisiloxane, which is similar in structure to HMDSO but with two vinyl groups replacing methyl ones. The morphological analysis showed that feeding the plasma with a large amount of ethylene, CHx‐enriched nanodomains were obtained over a siloxane matrix. Finally, the plasma phase composition was also investigated by infrared spectroscopy and correlated with the film chemistry.
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Characterising metabolic resistance in pyrethroid‐insensitive pollen beetle (Meligethes aeneus F.) from Poland and Switzerland
Authors: Philippou Despina , Field Linda M , Wȩgorek Pawel , Zamojska Joanna , Andrews Melanie C , Slater Russell , Moores Graham D 
Published: November 2010

AbstractBACKGROUND: Pollen beetle (Meligethes aeneus F.) has become the most important pest of oilseed rape in Europe, but its control has been greatly hindered by pyrethroid resistance. Target‐site resistance has been implicated previously, and, whilst synergism has been found with piperonyl butoxide (PBO), the exact nature of metabolic resistance has remained unknown. The use of PBO, in conjunction with its analogue EN 16/5‐1, has allowed the characterisation of metabolic resistance.RESULTS: In vitro assays in combination with in vivo studies using PBO and EN 16/5‐1 showed that high synergism of pyrethroids was primarily correlated with an oxidative mechanism, although a limited contribution by esterases was implicated in one population.CONCLUSION: Differential synergism has enabled the characterisation of pyrethroid resistance in populations of M. aeneus. It was found to be principally due to an oxidative‐based mechanism, and, if a synergist were to be used to inhibit this enzyme group, renewed control against resistant pests could be achieved. Copyright © 2010 Society of Chemical Industry
Synthesis of D‐glucosamine quaternary ammonium derivatives and evaluation of their antifungal activity together with aminodeoxyglucose derivatives against two wood fungi Coriolus versicolor and Poria placenta: structure–activity relationships
Authors: Muhizi Théoneste , Coma Véronique , Grelier Stéphane 
Published: November 2010

AbstractBACKGROUND: Structure–activity relationships are often reported in scientific studies. These may be employed in searching for new acceptable biocides to use against harmful microorganisms, because the biocides used hitherto encounter various problems, including lack of efficiency, high toxicity and persistence. Nowadays, scientists are trying to find new, environmentally acceptable biocides to replace these earlier biocides. Different compounds from renewable materials have been studied and have shown pronounced antifungal activity against wood fungi. These include aminopolysaccharide derivatives and different quaternary ammonium polymers. A biological study carried out with these products indicated a possible relationship between amino groups and differences in biological activity observed.RESULTS: In this study, an amino group was successively fixed to different carbon atoms of glucose, and glucosamine was also modified by both N‐alkylation and quaternisation. The impact of the amino group position on antifungal activity against two wood decay fungi was investigated. The amino group at the anomeric position showed the highest antifungal activity against both Coriolus versicolor Quel. and Poria placenta (Fr.) Cooke. Furthermore, the positive impact of both N‐alkylation and quaternisation on the growth of both strains was demonstrated.CONCLUSION: The anomeric position of the amino group and the N‐alkylation and quaternisation of amino sugars considerably increase the antifungal activity of these compounds. Copyright © 2010 Society of Chemical Industry
Immobilisation of bifenthrin for termite control
Authors: Guan Yan‐Qing , Chen Jia Mei , Li Zhi Bin , Feng Qi Li , Liu Jun‐Ming 
Published: November 2010

AbstractBACKGROUND: Termites are worldwide pests causing considerable damage to agriculture, forestry and buildings. While various approaches have been tried to eliminate termite populations, the relevant toxicants are associated with certain risks to the environment and human health.RESULTS: In this study, to combine the merits of effective chemical control by bifenthrin and a drug photoimmobilisation technique, silk fibroin was used as a carrier to embed bifenthrin, which was then photoactively immobilised by ultraviolet treatment on the surface of wood (cellulose). The immobilised bifenthrin embedded in the photoactive silk fibroin was characterised by Fourier transform infrared spectroscopy (FTIR), ultraviolet absorption spectroscopy (UV), fluorescence measurement and CHN analysis. The surface structures and biological activity were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), electron spectroscopy for chemical analysis (ESCA) and bioassays respectively.CONCLUSIONS: The results indicate that the embedded and immobilised bifenthrin has been very well protected from free release and has a long‐term stability allowing slow release with a high efficiency against termites at a low dose of 1.25 µg cm−2. This study provides a novel and environmentally benign technique for termite control by photoimmobilising silk‐fibroin‐embedded bifenthrin on the surface of materials that are otherwise easily attacked by termites. Copyright © 2010 Society of Chemical Industry
Effect of pesticide fate parameters and their uncertainty on the selection of ‘worst‐case’ scenarios of pesticide leaching to groundwater
Authors: Vanderborght Jan , Tiktak Aaldrik , Boesten Jos JTI , Vereecken Harry 
Published: November 2010

AbstractBACKGROUND: For the registration of pesticides in the European Union, model simulations for worst‐case scenarios are used to demonstrate that leaching concentrations to groundwater do not exceed a critical threshold. A worst‐case scenario is a combination of soil and climate properties for which predicted leaching concentrations are higher than a certain percentile of the spatial concentration distribution within a region. The derivation of scenarios is complicated by uncertainty about soil and pesticide fate parameters. As the ranking of climate and soil property combinations according to predicted leaching concentrations is different for different pesticides, the worst‐case scenario for one pesticide may misrepresent the worst case for another pesticide, which leads to ‘scenario uncertainty’.RESULTS: Pesticide fate parameter uncertainty led to higher concentrations in the higher percentiles of spatial concentration distributions, especially for distributions in smaller and more homogeneous regions. The effect of pesticide fate parameter uncertainty on the spatial concentration distribution was small when compared with the uncertainty of local concentration predictions and with the scenario uncertainty.CONCLUSION: Uncertainty in pesticide fate parameters and scenario uncertainty can be accounted for using higher percentiles of spatial concentration distributions and considering a range of pesticides for the scenario selection. Copyright © 2010 Society of Chemical Industry
Assessing departure from dose linearity under a repeated measures incomplete block design
Authors: Cheng Bin , Chow Shein‐Chung 
Published: November 2010

AbstractDose proportionality/linearity is a desirable property in pharmacokinetic studies. Various methods have been proposed for its assessment. When dose proportionality is not established, it is of interest to evaluate the degree of departure from dose linearity. In this paper, we propose a measure of departure from dose linearity and derive an asymptotic test under a repeated measures incomplete block design using a slope approach. Simulation studies show that the proposed method has a satisfactory small sample performance in terms of size and power. Copyright © 2010 John Wiley & Sons, Ltd.
Dietary quinic acid supplied as the nutritional supplement AIO + AC‐11® leads to induction of micromolar levels of nicotinamide and tryptophan in the urine
Authors: Pero Ronald W. , Lund Harald 
Published: November 2010

AbstractHippuric acid is synthesized and produced primarily by the gastrointestinal (GI) microflora. However, there is no known health benefit for hippuric acid except its catabolic conjugation of benzene‐type compounds via glycine and subsequent excretion in the urine. For years the GI tract microflora were known to metabolize quinic acid to hippuric acid. Recently it was also proposed that DNA repair was strongly enhanced by quinic acid. In order to explain these quinic acid effects, Pero and colleagues have examined whether tryptophan and nicotinamide were also enhanced by quinic acid levels in urine. They were indeed, and so another study was designed using a natural supplement source of quinic acid called AIO + AC‐11®, and then the effects of intervention were measured after only 21 days. It was possible to show profound increases in quinic acid that were again paralleled by increases in tryptophan and nicotinamide urinary levels. Because the high pressure liquid chromatography (HPLC) methods differed greatly between the two studies, differences in chemical analyses probably did not contribute to the data base. Copyright © 2010 John Wiley & Sons, Ltd.
Flexible Field Emission of Nitrogen‐Doped Carbon Nanotubes/Reduced Graphene Hybrid Films
Authors: Lee Duck Hyun , Lee Jin Ah , Lee Won Jong , Kim Sang Ouk 
Published: November 2010

AbstractThe outstanding flexible field emission properties of carbon hybrid films made of vertically aligned N‐doped carbon nanotubes grown on mechanically compliant reduced graphene films are demonstrated. The bottom‐reduced graphene film substrate enables the conformal coating of the hybrid film on flexible device geometry and ensures robust mechanical and electrical contact even in a highly deformed state. The field emission properties are precisely examined in terms of the control of the bending radius, the N‐doping level, and the length or wall‐number of the carbon nanotubes and analyzed with electric field simulations. This high‐performance flexible carbon field emitter is potentially useful for diverse, flexible field emission devices.
Fluorescent Polymeric Nanoparticles: Aggregation and Phase Behavior of Pyrene and Amphotericin B Molecules in Nanoparticle Cores
Authors: Kumar Varun , Adamson Douglas H. , Prud’homme Robert K. 
Published: November 2010

AbstractThe state of aggregation of compounds, especially drugs, in the cores of nanoparticles (NPs) formed by rapid precipitation is a significant unresolved issue. The state can control the dissolution kinetics from the NP, bioavailability, and chemical stability of the compound. A block‐copolymer‐directed rapid precipitation process is used to form ≈100 nm NPs comprising mixtures of hydrophobic species including fluorescent probe molecules. Fluorescence measurements are used to probe the state of aggregation and dynamics of rearrangement of pyrene (Py), Hostasol Yellow (HosY), and amphotericin B (AmpB) in NP cores. The Flory–Huggins theory of mixing is used to predict the miscibility or phase separation of the fluorophores from the host NP core material (polystyrene, cholesterol, or polycaprolactone). For Py, excimer fluorescence shows an initial microphase separation in the polystyrene core. Over time the Py redistributes more uniformly with a decrease in excimer and increase in monomer fluorescence. The Flory–Huggins theory predicts the miscibility. For HosY, the fluorescence quenching is not time‐dependent, thus indicating stability of the microphase‐separated fluorophores, which is consistent with the Flory–Huggins theory calculations. For the drug compound AmpB, the amphiphilic character of the molecule creates unusual “anti‐Ostwald” ripening behavior in which the size distribution decreases and narrows over time, and the fluorescence demonstrates an increased ordering in the NP core over time—opposite to the behavior observed for Py.