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enhancement of electric Conductivity in Transparent Glasse—Ceramic Nanocomposites of Bi_2O_3—BaTiO_3 Glasses

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Journal of Materials Science & Technology 2013年第12期29卷 1166-1176页

作者： A.A.Bahgat M.G.Moustafa e.e.Shaisha Department of Physics Faculty of ScienceAl-Azhar University

The frequency and temperature dependent electrical conductivity measurements for heat-treated binary glass system with composition of （lO0-x）Bi203-xBaTi03 （x = 20, 30, 40 and 50, in mol%） were carried out. The glass was prepared by melt quenching technique and their corresponding glass-ceramic nanocomposites were obtained by suitable heat treatment. Nanostructured behavior and electrical properties of these glasses and their corresponding glass-ceramic nanocomposites were studied. X-ray diffraction （XRD） and differential scanning calorimetry confirmed the amorphous nature of the glasses. Moreover, XRD patterns of the samples indicate nanocrystallites embedded in the glass matrix. The Fourier transform infrared spectroscopy （FT-IR） spectral analysis showed that the band positions of glass system are within the wave number range of Bi06, Bi03 and Ti06 structural units. It is observed that the electrical conductivity is enhanced by 102-103 times in the transparent glass-ceramic nanocomposite phase. With further heat treatment, the conductivity decreased considerably in the stage of glass-ceramic nanocomposite phase as compared with the glassy phase sample. Therefore, partially devitrified phase is more suitable as cathode material in secondary batteries compared to its vitreous or fully crystalline counterpart. The conduction mechanism was confirmed to obey the adiabatic small polaron hopping （SPH）. AC conductivity measurements were performed as a function of temperature and frequency, showing a very slow increasing rate at low temperatures and then a fast rate at higher temperatures.

关键词： Barium titanat Transparent glass--ceramic nanocomposites DC electrical conductivity AC electrical conductivity Smallpolaron hopping

Toxicity for Aquatic Organisms of Antiretroviral Tenofovir Disoproxil

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Journal of environmental Protection 2019年第12期10卷 1565-1577页

作者： S.R.Silva F.A.R.Barbosa M.P.G.mol S.M.S.Magalhaes Department of Social Pharmacy Pharmacy SchoolFederal University of Minas GeraisBelo HorizonteMinas GeraisBrazil Department of General Biology Institute of Biological SciencesFederal University of Minas GeraisBelo HorizonteMinas GeraisBrazil Research and Development Board Ezequiel Dias FoundationBelo HorizonteMinas GeraisBrazil

Tenofovir disoproxil fumarate is a prodrug, i.e. inative substance converted in vivo, after absorption to the active form deesterified tenofovir, which acts as an inhibitor of viral reverse transcriptase. To better understand the toxic effects of these drugs in the environment, three organisms were tested, the effective concentration (eC50) and inhibitory concentration (IC50) of tenofovir disoproxil that resulted in 50% growth inhibition of Microcystis novacekii, 50% immobilization of Artemia salina, and 50% loss of bioluminescence of Aliivibrio fischeri were evaluated. The eC50 value after 96 h of treatment for the cyanobacterium was 161.01 (156.81 - 165.21) mg·L-1;the IC50 value for A. salina after 24 h of treatment was 111.82 (103.18 - 120.45) mg·L-1;and the IC50 at 15 min for A. fischeri was 14.83 (13.87 - 15.79) mg·L-1. The test organism most sensitive to the drug was A. fischeri, indicating the importance of using representative models at different trophic levels to assess the potential risk of drugs for environmental toxicity. These results highlight the possible effect of tenofovir disoproxil on decomposer organisms, which may contribute to the environmental persistence of this drug.

关键词： emerging Contaminant Aliivibrio fischeri Artemia salina Microcystis novacekii

Improvement of sintering,nonlinear electrical,and dielectric properties of ZnO-based varistors doped with TiO2

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Chinese Physics B 2016年第6期25卷 575-580页

作者： Osama A Desouky K e Rady Bilbis Higher Institute of engineering (BHIe) Bilbis Sharqia Egypt engineering Basic Sciences Department Faculty of engineering Menoufia University Shebin EI-Kom Egypt

The effects of TiO2 on sintering and nonlinear electrical properties of（98.5-x）ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2（x = 0.3,0.5,0.7,0.9 mol%） ceramic varistors prepared by the ceramic technique are investigated in this *** optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption *** optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water *** minimum water absorption appears in a sample of x = 0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase *** crystal size of ZnO decreases with increasing TiO2 *** addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x = 0.7 mol% of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 *** temperature and composition dependences of the dielectric constant and AC conductivity are also *** increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.

关键词： ZnO varistors water absorption nonlinear electrical properties dielectric constant

Nutritional and microbiological evaluations of chocolate-coated Chinese chestnut (Castanea mollissima) fruit for commercial use

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第9期9卷 675-683页

作者： Mahamadou e. GOUNGA State Key Laboratory of Food Science & Technology School of Food Science & Technology Jiangnan University

In recent years, China has become an increasingly important and the largest chestnut producer in the world. This study aimed to evaluate the nutritional value and microbiological quality of the roasted freeze-dried Chinese chestnut (Castanea mollissima) (RFDC) coated with dark chocolate (DCC) and milk chocolate (MCC) for industrial use and commercial consumption. Chocolate coating significantly improved the nutritional value of chestnut. RFDC had high levels of starch (66.23%) and fibers (3.85%) while DCC and MCC contained significantly high amounts of sucrose, protein, fat and minerals. Furthermore, the protein content doubled in MCC rather than in DCC. This could be attributed to the different formulations in the two products. Milk powder and whey protein constituted the source of protein in MCC while cocoa powder added to MCC formulation constituted an additional source of minerals. The amino acid profile showed differences in amino acid composition related to the sample’s protein content, indicating their good nutritional quality. The moisture contents in all RFDC, DCC and MCC were suitable for industrial processing. These results provide information about the additional nutrients of chocolate-coated chestnut and confirm that the product is an interesting nutritional food. The combination of freeze-drying and chocolate-coating generally results in greater reductions on microbiological loads, extending shelf life of harvested chestnut for commercial application. This is an alternative strategy to add value to chestnut, minimizing the significant losses in harvested fruits and providing a wider range of choices of new products to the consumer disposal.

关键词： Chestnut Coating Dark chocolate Milk chocolate Nutritional qualities Microbiological analysis

Remaining Phosphorus estimate Through Multiple Regression Analysis

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Pedosphere 2006年第5期16卷 566-571页

作者： M.e.ALVeS A.LAVOReNTI Departamento de Ciencias exatas Escola Superior de Agriculture‘Luiz de Queiroz’-ESALQ/USPPiracicaba (SP) 13418-900 (Brazil)

The remaining phosphorus (Prem), P concentration that remains in solution after shaking soil with 0.01 mol L-1 CaCl2 containing 60μg mL-1 P, is a very useful index for studies related to the chemistry of variable charge soils. Although the Prem determination is a simple procedure, the possibility of estimating accurate values of this index from easily and/or routinely determined soil properties can be very useful for practical purposes. The present research evaluated the Prem estimation through multiple regression analysis in which routinely determined soil chemical data, soil clay content and soil pH measured in 1 mol L-1 NaF (pHNaF) figured as Prem predictor variables. The Prem can be estimated with acceptable accuracy using the above-mentioned approach, and pHNaF not only substitutes for clay content as a predictor variable but also confers more accuracy to the Prem estimates.

关键词： anionic adsorption pHNaF pedotransfer functions tropical soils

Chemical forms and extractability of iron in sediments of three contrasting lakes of China and UK

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Journal of environmental Sciences 2003年第6期15卷 728-733页

作者： Gibson C.e.,Stewart B.M. Key Laboratory of Terrestrial ecological Process Institute of Applied ecology Chinese Academy of Sciences Department of Agricultural and environmental Science Queen's University Belfast Shenyang 110016 China Newforge Lane Belfast BT9 5PX UK

Iron is a limiting factor for the eutrophication of lakes, especially those lakes that are enriched with phosphorus. extractability of iron in sediments of West Lake and Taihu Lake in China and Lower Lough erne in Northern Ireland of UK was comparatively investigated on the basis of analysing chemical forms of iron using different extractants. It was shown that extractable iron in sediments of the lakes was greatly different using various extractants. Reactive iron or easily released iron such as “active" iron oxides, total free iron oxide and water-soluble iron was not high, only accounting for 0.01%—0.15% of total iron. The efficiency of the extractants for exchangeable iron was decreased in the sequence 0.1 mol/L HCl DTPA+TeA mixed solution > 1 mol/L NH 4OAc > 0.5 mol/L MgCl 2 = 0.5 mol/L CaCl 2. It seems that the complexion of iron by organic matter was not strong because the concentration of organically bound iron was significantly lower than the concentration it was forecasted. extractable iron is not entirely consistent with or dependent on total iron in lake sediments. To a certain extent, phosphate can inhibit the release of iron in sediments of the lakes. The selection of extractants is thus the first key step to evaluate bioavailability of iron in lake sediments.

关键词： iron chemical form extractability lake sediment eutrophication

The effect of Reaction Conditions on the Synthesis of Thermoplastic elastomers Containing Polyalloocimene, Polyisobutylene and Tapered Blocks

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Chinese Journal of Polymer Science 2019年第9期37卷 884-890页

作者： Jozsef Kantor Judit e. Puskas Gabor Kaszas Department of Chemical and Biomolecular engineering The University of Akron Akron OH 44325 USA Department of Food Agricultural and Biological Engineering (1/1/2019) The Ohio State University Wooster OH 44691 USA PolyFiberMatrix LLC 2295 W. Market St. Suite D. Akron OH 44313 USA

This work investigates the effect of reaction conditions on the copolymerization of isobutylene (IB) with alloocimene (Allo) in methyl chloride (MeCl) using AlCh and ethylaluminum dichloride (etAlCh) as coinitiators and adventitious moisture as the initiator. Both AlCh and etAlCb produced high molecular weight (Mn > 1.0 x 10^5 g/mol) thermoplastic elastomers (TPes) with good mechanical properties in short reaction time (ese unique TPes have unsaturations in the end blocks, leading to easy functionalization and/or crosslinking.

关键词： Polyisobutylene Alloocimene Triblock copolymer Carbocationic polymerization

Graphene/γ-AlOOH Hybrids as an enhanced Sensing Platform for Ultrasensitive Stripping Voltammetric Detection of Pb（II）

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Chemical Research in Chinese Universities 2015年第4期31卷 590-596页

作者： FAN Wei MIAO Yue'e LIU Tianxi State Key Laboratory of molecular engineering of Polymers Department of Macromolecular Science Fudan University Shanghai 200433 P. R. China

The reduced graphene oxide（RGO）/γ-A1OOH hybrids with different γ-AlOOH contents were successfully prepared via a facile one-pot hydrothermal method. In these hybrids, RGO acts as a conductive linker for improving electron transport, and γ-AlOOH nanoplatelets help to adsorb the target metal ions on the electrode surface, thus faci- litating the electrochemical behavior of the hybrids. The sensitivity of as-prepared RGOγ-AlOOH hybrids toward Pb（II） was tested by square wave anodic stripping voltammograms（SWASV）and the mass ratio of graphene to γ-AlOOH was optimized to improve the sensing performance of RGOγ-AlOOH hybrids. Owing to the superior ab- sorbability of γ-AlOOH for heavy metal ions and excellent electrical conductivity of graphene, the detection limit of the hybrids for heavy metal ions was found to be as low as 1.5× 10^-11 mol/L with optimized γ-AlOOH content in the hybrids. The experimental conditions, such as pH value, mass of electrode material, and deposition time were also investigated and optimized. The as-prepared RGOγ-AlOOH hybrids demonstrate high electrochemical activity and good sensing performance, which offers an alternative platform for the electrochemical sensors.

关键词： Graphene γ-AlOOH Hybrid Heavy metal ion electrochemical sensor

Analysis of cellulolytic and hemicellulolytic enzyme activity within the Tipula abdominalis （Diptera： Tipulidae） larval gut and characterization of Crocebacterium ilecola gen. nov., sp. nov., isolated from the Tipula abdominalis larval hindgut

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Insect Science 2010年第3期17卷 291-302页

作者： Theresa e. Rogers Joy Doran-Peterson Microbiology Department University of Georgia Athens Georgia USA

In forested stream ecosystems of the north and eastern United States, larvae of the aquatic crane fly Tipula abdominalis are important shredders of leaf litter detritus. T. abdominalis larvae harbor a dense and diverse microbial community in their hindgut that may aide in the degradation oflignocellulose. In this study, the activities ofcellulolytic and hemicellulolytic enzymes were demonstrated from hindgut extracts and from bacterial isolates using model sugar substrates. One of the bacterial isolates was further characterized as a member of the family Microbacteriaceae. Taxonomic position of the isolate within this family was determined by a polyphasic approach, as is commonly employed for the separation of genera within the family Microbacteriaceae. The bacterial isolate is Gramtype positive, motile, non-sporulating, and rod-shaped. The G ＋ C content of the DNA is 64.9 mol%. The cell wall contains B2y type peptidoglycan, D- and L-diaminobutyric acid as the diamino acid, and rhamnose as the predominant sugar. The predominant fatty acids are 12-methyltetradecanoic acid （ai-C15：0） and 14-methylhexadecanoic acid （ai-C17：0）. The isolate forms a distinct lineage within the family Microbacteriaceae, as determined by 16S rRNA sequence analysis. We propose the name Crocebacterium ilecola gen. nov., sp. nov., to accommodate this bacterial isolate. The type species is T202T （ATCC BAA-1359; GenBank Accession DQ826511）.

关键词： cellulolytic hemicellulolytic hindgut