Nonlinear current-voltage characteristics of conductive polyethylene composites with carbon black filled pet microfibrils

Current-voltage electrical behavior of in situ microfibrillar carbon black (CB)/poly(ethylene terephthalate) (PET)/polyethylene (PE) (m-CB/PET/PE) composites with various CB concentrations at ambient temperatures was studied under a direct-current electric field. The current-voltage (I-V) curves exhibited nonlinearity beyond a critical value of voltage. The dynamic random resistor network (DRRN) model was adopted to semi-qualitatively explain the nonlinear conduction behavior of m-CB/PET/PE composites. Macroscopic nonlinearity originated from the interfacial interactions between CB/PET micro fibrils and additional conduction channels. Combined with the special conductive networks, an illustration was proposed to interpret the nonlinear I-V characteristics by a field emission or tunneling mechanism between CB particles in the CB/PET microfibers intersections.     

Correlation of SiO x layer thickness and properties of BOPP/SiO x composite films with spin coating process parameters

The effects of the spin coating process parameters on the thickness of the SiOx layer of the BOPP/SiOx composite film were investigated. When the concentration of tetraethoxysilane (TEOS) increased from 12.5 vol% to 55% vol%, the SiOx thickness increased from about 80 nm to 470 nm. In the sol time range of 1.5 h to 5 h the SiOx layer thickness reached a maximum at about 4 h and the change of the thickness roughly matched the change of the silica colloidal sphere sizes in sol. When the spin-coating speed of the dispensing stage increased from 450 r/min to 500 r/min, the SiOx layer thickness drastically decreased from about 1.67 μm to 400 nm. While the spin-coating speed of the thinning and drying stage went up to 1200 r/min, the SiOx layer thickness was in the range of 330 nm to 390 nm. It was also found that the SiOx layer thickness was almost increased linearly from about 500 nm to 1.02 μm with the ratio of the commercial silica colloidal to the TEOS from 0.2 to 1.0. The water contact angles decreased to about 23.0° for the BOPP/Si-Sol composite film with 1.67 μm SiOx layer and about 4.0° for the BOPP/mixing Si-Sol composite film with 1.02 μm SiOx layer. Compared to BOPP, the light transparency of the BOPP/Si-Sol composite films decreased by about 5.5% with the SiOx layer from about 80 nm to 1.67 μm and by 7.0% for the BOPP/mixing Si-Sol composite film with the SiOx layer from about 350 nm to 1.02 μm respectively.     

Synthesis and Crystal Structure of （E）-2-phenyl-6,7dihydrobenzofuran-4（5H）-one O-cyanomethyl Oxime

A pair of E/Z-isomers of 2-phenyl-6,7-dihydrobenzofuran-4（5H）-one O-cyanomethyl oxime,C16H14N2O2,as potential drugs for treating peptic ulcer and other acid-related diseases have been synthesized and characterized by IR,MS and NMR spectra.Meanwhile,the crystal of IIIa was obtained and determined by X-ray single-crystal diffraction.Crystal data： monoclinic system,space group P21 /c,a = 8.423（8）,b = 19.596（16）,c = 8.770（8）,β = 107.750（12）°,V = 1379（2）3,Z = 4,F（000） = 560,Dc = 1.283 g/cm3,μ = 0.086 mm 1,R = 0.0681 and wR = 0.2029 for 14472 independent reflections（Rint = 0.0782） and 2428 observed ones（I 2σ（I））.     

Liquid crystalline behaviour of hydrazide derivatives containing alkoxyazobenzene

Two series of dissymmetric hydrazide derivatives containing alkoxyazobenzene with nitro terminal group and octyloxy terminal group, N-4-alkoxyphenyl-N′-4-((4-nitrophenyl)azophenyl) benzohydrazide (Bn-NO₂, n indicates the number of carbon atoms) and N-4-octyloxyphenyl-N′-4-((4-octyloxyphenyl)azophenyl) benzohydrazide (B8-B8), were designed and synthesised, and their liquid crystalline properties were investigated by means of differential scanning calorimetry, polarised optical microscopy and wide-angle X-ray diffraction. It was found that B8-B8 with octyloxy terminal chains displayed monolayer smectic C phase, whereas Bn-NO₂ with nitro terminal group displayed SmA_d phase, and intermolecular hydrogen bonding was confirmed as the driving force. In addition, the effect of hydrogen bonding, dipole–dipole interactions and steric hindrance effect on the liquid crystalline structures were also discussed.     

Dynamic Changes in Xylanases and β-1,4-Endoglucanases Secreted by Aspergillus niger An-76 in Response to Hydrolysates of Lignocellulose Polysaccharide

Aspergillus niger is an effective secretor of glycoside hydrolases that facilitate the saprophytic lifestyle of the fungus by degrading plant cell wall polysaccharides. In the present study, a series of dynamic zymography assays were applied to quantify the secreted glycoside hydrolases of A. niger cultured in media containing different carbon sources. Differences in the diversity and concentrations of polysaccharide hydrolysates dynamically regulated the secretion of glycoside hydrolases. The secretion of β-1,4-endoglucanase isozymes was observed to lag at least 24 h behind, rather than coincide with, the secretion of xylanase isozymes. Low concentrations of xylose could induce many endoxylanases (such as Xyn1/XynA, Xyn2, and Xyn3/XynB). High concentrations of xylose could sustain the induction of Xyn2 and Xyn3/XynB but repress Xyn1/XynA (GH10 endoxylanase), which has a broad substrate specificity, and also triggers the low-level secretion of Egl3/EglA, which also has a broad substrate specificity. Mixed polysaccharide hydrolysates sustained the induction of Egl1, whereas the other β-1,4-endoglucanases were sustainably induced by the specific polysaccharide hydrolysates released during the hydrolysis process (such as Egl2 and Egl4). These results indicate that the secretion of glycoside hydrolases may be specifically regulated by the production of polysaccharide hydrolysates released during the process of biomass degradation.     

Double emulsion-templated microspheres with flow-through pores at micrometer scale

Two different polymers, poly(vinylbenzyl chloride) and poly(methyl methecrylate-2-hydroxyethyl methacrylate), were respectively employed as the major component of the particle material and amphiphilic polymer methoxy poly (ethylene glycol)-b-poly (D, L-lactide) was employed as an essential additive. Gigaporous microspheres which possess flow-through pores which range from submicron to micron scale were prepared by two-step emulsification, emulsion ripening, and solvent extraction. Parameters on the final morphology were particularly investigated, including the polymer component, emulsion ripening time, and osmotic gradient. The formation mechanism of gigapores was also discussed with consideration of evolution behavior of the double emulsion system. The evolution process was proved crucial to control the final pore structure. Such kind of gigaporous microspheres could be further exploited as a promising chromatographic media for the purification of bioproducts.     

A ratiometric fluorescent probe for zinc ions based on the quinoline fluorophore

A ratiometric fluorescent zinc probe 1 of carboxamidoquinoline with a carboxylic acid group was designed and synthesised. Probe 1 exhibits high selectivity for sensing Zn²⁺; about a 13-fold increase in fluorescence emission intensity and an 82?nm red-shift of fluorescence emission are observed upon binding Zn²⁺ in EtOH/H₂O (1?:?1, V/V) solution. The ratiometric fluorescence response is attributed to the 1?:?1 complex formation between probe 1 and Zn²⁺ which has been utilised as the basis for the selective detection of Zn²⁺. The analytical performance characteristics of the proposed Zn²⁺-sensitive probe were investigated. The linear response range covers a concentration range of Zn²⁺ from 2.0?×?10^?6 to 5.0?×?10^?5?mol?L^?1 and the detection limit is 2.7?×?10^?7?mol?L^?1. The determination of Zn²⁺ in both tap and river water samples shows satisfactory results.     

The impact of nitrogen fertilizers on degradation and leaching of chlorotoluron in soil

Abstract

This study presents the developed and applied methods for the determination of carbendazim in environmental samples originating from several field studies.

For water samples sample pretreatment consisted of a solid phase extraction (SPE) on cartridges packed with 200 mg SDB-1. In case of solid samples the performance of microwave assisted solvent extraction (MASE) and classical ultrasonic extraction with acetone-ethyl acetate were studied. The latter technique was selected because of the reduced time of manual operations. Instrumental analysis of extracts of water samples was performed on-line with coupled column reversed phase liquid chromatography (LC/LC) and UV detection (280 nm) allowing to assay carbendazim to a level of at least 0.1 μg/l. Improved column life time was obtained by performing the favorable LC separation of carbendazim at high pH on newly developed 5 μm Extend-pH bidentate C18 material.

The combination of a short column packed with 5 μm Inertsil ODS-5 and a mobile phase at low pH material was most adequate as the regards the robust and fast processing of extracts of solid samples and allowed in most cases the screening of carbendazim in soils and sediments to a level of 10μg/kg.

The developed procedures yield overall recoveries for carbendazim of 101, 80 and 71 % in water (levels, 0.1—1.2 μg/l: n=12), soil (levels, 10 and 100 μg/kg; n=22) and sediments (levels, 10 and 100 μg/kg; n=11), respectively, with a repeatability and reproducibility below 7 % for all method/matrix combinations. Soil samples with aged residues (level, 100 μg/kg; n=10) provided an overall recovery of 71% and no significant decrease of carbendazim was observed during nine weeks of storage in the refrigerator.     

Simultaneous extraction and determination of fluoroquinolones,tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59?kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2?g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50?µg?kg^?1 soil, and from 69% to 97% at the spiking level of 200?µg?kg^?1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.     

Determination of trace amounts of chromium (VI) by flow injection analysis with chemiluminescence detection

A new sensitive chemiluminescence (CL) method combined with continuous flow injection analysis is described for the determination of Cr(VI). Strong CL signals were generated by Cr(VI)-catalysed oxidation of gallic acid in the presence of potassium permanganate and hydrogen peroxide. Effects of reagent concentrations, temperature, pH, flow rates, mixing coil length and mixing flow sequences on the chemiluminescence intensity were studied. Under the optimised experimental conditions, the relationship between the logarithm of concentration (log?C) of Cr(VI) and the logarithm of intensity (log?I) is linear over the range of 2?×?10^?11 – 5?×?10^?4?mol?L^?1, with the detection limit (3σ) of 4?×?10^?12?mol?L^?1. Relative standard deviation of ten measurements of 1?×?10^?9?mol?L^?1 Cr(VI) is 1.7%. This flow injection analysis (FIA) system proved to be able to analyse up to 40 samples h^?1. Effects of various interferences possibly present in the water samples were investigated. Most cations and anions, as well as organic compounds, did not interfere with the determination of Cr(VI) in water samples. The experimental results obtained for chromium in reference materials were also in good agreement with the certified values.