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    ABSTRACT: Ozonation is one of the common methods for pollutant removal and disinfection in water treatment. The reaction between the ozone and organic pollutants involves complex oxidation pathway which may lead to the formation of various ozonation by-products. In some cases, toxic ozonation by-products may be produced. In this study, the ozonation by-products of acebutolol, one of the common β-blockers, were identified. The mechanisms for the transformation of acebutolol during ozonation were elaborated. In this study, ozonation was carried out at pH 2 (with the presence of radical scavenger), 7 and 12, in order to study the role of the ozone (O3) and hydroxyl radical (•OH) in the transformation of acebutolol. Structure elucidation of the ozonation by-products was carried out using HPLC coupled with quadrupole time-of-flight high resolution mass spectrometry. Sixteen ozonation by-products were identified, of which fifteen have never been reported elsewhere. Based on the detected ozonation by-products, acebutolol can be degraded by both O3 and •OH. When the O3 itself becomes a reactive species, the transformation of the acebutolol proceeded via the reaction between the O3 and the aromatic ring of the acebutolol to form the aromatic ring hydroxylated and aromatic ring opening by-products. Without the radical scavenger, ozonation at pH 7 and 12 showed that the transformation of the acebutolol proceeded via the involvement of the •OH and different aliphatic chain degraded and hydroxylated by-products were detected.(http://www.sciencedirect.com/science/article/pii/S1383586614004766)
    Separation and Purification Technology 08/2014; 135:48-63.
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    ABSTRACT: Abstract The effects of extrusion processing temperature on the rheological, dynamic mechanical analysis and tensile properties of kenaf fiber/high-density polyethylene (HDPE) composites were investigated for low and high processing temperatures. The rheological data showed that the complex viscosity, storage and loss modulus were higher with high processing temperature. Complex viscosities of pure HDPE and 3.4 wt% composite with zero shear viscosity of ⩽2340 Pa s were shown to exhibit Newtonian behavior while composites of 8.5 and 17.5 wt% with zero shear viscosity ⩾30,970 Pa s displayed non-Newtonian behavior. The Han plots revealed the sensitivity of rheological properties with changes in processing temperature. An increase in storage and loss modulus and a decrease in mechanical loss factor were observed for 17.5 wt% composites at high processing temperature and not observed at low processing temperature. Processing at high temperature was found to improve the tensile modulus of composites but displayed diminished properties when processed at low processing temperature especially at high fiber content. At both low and high processing temperatures, the tensile strength and strain of the composite decreased with increased content of the fiber. Keywords B. Rheological properties; D. Mechanical testing; E. Extrusion; Kenaf fiber composites
    Composites Part B Engineering 03/2014; 58:259-266.
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    ABSTRACT: Apparent catalytic effects of varying concentration of CTABr/MX/H2O nanoparticles (at a constant [CTABr] and [Piperidine]) on pseudo-first-order rate constants (kobs) for the reaction of piperidine with ionized phenyl salicylate have been measured as kobs/k0 where kobs and k0 represent rate constants in the presence and absence of MX, respectively. Symbols CTABr and MX represent respectively cetyltrimethylammonium bromide and 2,3- or 3,5-Cl2BzNa with Bz− = C6H3CO2−. At 6 mM CTABr, the maximum values of kobs/k0 are 7.9 and 9.0 at 300 mM 2,3-Cl2BzNa and 80 mM 3,5-Cl2BzNa respectively. Several-fold larger catalytic effects of 3,5-Cl2Bz− than that of 2,3-Cl2Bz− are attributed to ∼8-fold larger CTABr binding constant of 3,5-Cl2Bz− than that of 2,3-Cl2Bz−. Origin of CTABr/MX/H2O nanoparticles catalytic effects is related to the ability and efficiency of the expulsion of another counterion S− by the counterion X− from the cationic nanoparticles to the aqueous phase by means of the ion exchange process X−/S− at the cationic surface of nanoparticles.
    Journal of the Taiwan Institute of Chemical Engineers 01/2014;
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    ABSTRACT: Carbon nanotube (CNT) filled fluoroelastomer (FE) nanocomposites, were prepared and and their properties were compared with those of carbon black (CB) filled- or unfilled-FE. Dynamic mechanical analysis (DMA) and Differential Scanning Calorimetry (DSC) showed that the glass transition temperature (Tg) of CNT/FE increased when compared to CB/FE or FE. For the CNT/FE and in comparison to others (in their glassy and rubbery states), the storage modulus is higher. However tan δ in the glassy state is lower, but higher in the rubbery state. The DSC and DMA results confirmed that the FE and filler/FE is partially crystalline. The results showed that the crystalline part of FE and CB/FE were mostly in the α-form. However, CNT together with shear and high temperature, induced γ-crystallinity in the FE. X-ray diffraction (XRD) results also confirmed the DSC and DMA results and showed that CNT caused an increase in the γ-crystallinity in FE and decreased α-phase crystallinity compared to others. XRD, DSC and DMA results for FE and filler/FE corroborated these observations.
    Composites Part B Engineering 01/2014; 58:166–174.
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    ABSTRACT: Graphical abstract The reactions of the Schiff base ligand (E)-4-chloro-N′-(2-hydroxy-4-methoxybenzylidene)benzohydrazide with substituted dibenzyltin dichlorides afforded either monobenzyltin or dibenzyltin complexes, depending on the reaction conditions and the benzyl substituents. The subsequent reaction of a monobenzyltin complex with 4,4-bipyridine yielded a co-crystal containing the methanol coordinated monobenzyltin complex and 4,4-bipyridine.
    Polyhedron 01/2014; 81:370–381.
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    ABSTRACT: Glycolipids, namely heptyl-β-D-glucopyranoside (HG), octyl-β-D-glucopyranoside (OG) and dodecyl-β-D-glucopyranoside (DG), incorporated in sodium decanoate–decanoic acid (SD–DA) aggregates have been found to affect the critical vesicular concentration (CVC) values and electrophoretic mobility behaviour of their vesicles. Titration of the solutions has shown that the buffering capacity from COO−…COOH interaction and multilamellar vesicles was predominantly observed under polarized light microscope for the solutions that have been brought down to neutral pH. CVC of the decanoic acid was reduced to half the initial value (0.02 M) when 4% DG was introduced into the solution, while only a slight change was observed when shorter glycolipids were mixed with the decanoic acid. The glycolipids reduced the electrophoretic mobility of the vesicles possessing a strong interaction between the head groups, which belong to the carboxylate of the fatty acid and hydroxyl of the glycolipids, probably suggesting partial neutralization. Thus, the presence of glycolipids in small amounts promotes the formation of decanoic acid vesicles by enhancing the bilayer curvature through hydrogen bonding within the polar region.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 01/2014; 443:96–101.
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    ABSTRACT: Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. In this study, multivariate strategy was used to determine the significance of the factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) using a randomised factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticide residues were evaluated using 2(3) factorial designs. The analytes were extracted with 100μm PDMS fibres according to the factorial design matrix and desorbed into a gas chromatography-mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limits of detection were between 0.01 and 0.2μgkg(-)(1), which were lower than the MRLs for apples. The relative standard deviations (RSD) were between 0.1% and 13.37% with average recovery of 80-105%. The linearity ranges from 0.5-50μgkg(-)(1) with correlation coefficient greater than 0.99.
    Food Chemistry 12/2013; 141(4):4344-8.
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    ABSTRACT: In the present study, we investigated the effect of long-acyl chain SFA, namely palmitic acid (16 : 0) and stearic acid (18 : 0), at sn-1, 3 positions of TAG on obesity. Throughout the 15 weeks of the experimental period, C57BL/6 mice were fed diets fortified with cocoa butter, sal stearin (SAL), palm mid fraction (PMF) and high-oleic sunflower oil (HOS). The sn-1, 3 positions were varied by 16 : 0, 18 : 0 and 18 : 1, whilst the sn-2 position was preserved with 18 : 1. The HOS-enriched diet was found to lead to the highest fat deposition. This was in accordance with our previous postulation. Upon normalisation of total fat deposited with food intake to obtain the fat:feed ratio, interestingly, mice fed the SAL-enriched diet exhibited significantly lower visceral fat/feed and total fat/feed compared with those fed the PMF-enriched diet, despite their similarity in SFA-unsaturated fatty acid-SFA profile. That long-chain SFA at sn-1, 3 positions concomitantly with an unsaturated FA at the sn-2 position exert an obesity-reducing effect was further validated. The present study is the first of its kind to demonstrate that SFA of different chain lengths at sn-1, 3 positions exert profound effects on fat accretion.
    The British journal of nutrition 11/2013;
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    ABSTRACT: Through atomistic molecular dynamic simulations using a GROMOS53a6 force field for the carbohydrate, we studied the lyotropic reverse hexagonal phase HII from a glycolipid, namely the Guerbet branched-chain β-d-glucoside, at 14% and 22% water concentrations. Our simulations showed that at low water concentration (14%) the sugar head group overlapped extensively and protruded into the water channel. In contrast, in the 22% concentration system a water column free from the sugar headgroup ('free' water) was formed as expected for the system close to the limit of maximum hydration. In both concentrations, we found anomalous water diffusion in the xy-plane, i.e. the two-dimensional space confined by the surface of the cylinder. On the other hand, along the z-axis, the water diffusion obeyed the Einstein relation for the 22% system, while for the 14% system it was slightly anomalous. For the 22% system, the diffusion along the z-axis of the 'free' water obeyed the Einstein relation, while that of the 'bound' water is slightly anomalous. The xy-plane displacement of the 'bound' water was higher than that for the 'free' water at times longer than 200 ps, as a consequence of the exchange of water molecules between the two regions. Based on our findings, we proposed an alternative explanation to the observed spatial heterogeneity in the HII phase from probe diffusion by Penaloza et al. (Phys. Chem. Chem. Phys., 2012, 14(15), 5247-5250). We found the extent of contact with water was different at different oxygen atoms within the sugar ring. Generally, a higher probability of hydrogen bonding but a shorter lifetime was found in 22% water compared to the case of 14% water. Finally, we examined the extension and compression of the alkyl chain of a columnar.
    Physical Chemistry Chemical Physics 11/2013;
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    ABSTRACT: A cationic Schiff base ligand, TSB (L) and its Zn (II) complex (1) were synthesized and characterized by using CHN, (1)H-NMR, FT-IR, UV, LC-MS, and X-ray methods. Their ability to inhibit topoisomerase I, DNA cleavage activities, and cytotoxicity were studied. X-ray diffraction study shows that the mononuclear complex 1 is four coordinated with distorted tetrahedral geometry. The singly deprotonated Schiff base ligand L acts as a bidentate ON-donor ligand. Complexation of L increases the inhibitory strength on topoisomerase I activity. Complex 1 could fully inhibit topoisomerase I activity at 250μM, while L did not show any inhibitory effect on topoisomerase I activity. In addition, L and complex 1 could cleave pBR322 DNA in a concentration and time dependent profile. Surprisingly, L has better DNA cleavage activity than complex 1. The cleavage of DNA by complex 1 is altered in the presence of hydrogen peroxide. Furthermore, L and complex 1 are mildly cytotoxic towards human ovarian cancer A2780 and hepatocellular carcinoma HepG2.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2013; 121C:101-108.
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