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Visible Spectrophotometry (visible + spectrophotometry)
Selected AbstractsEffect of orientation and crystallinity on the photodegradation of poly(ethylene terephthalate) fibersPOLYMER ENGINEERING & SCIENCE, Issue 5 2008H. Fashandi In this research, photodegradation of poly(ethylene terephthalate) (PET) fibers was investigated with emphasis on the morphological state of yarns. Two kinds of yarns, FDY (Fully Drawn Yarn) and POY (Partially Oriented Yarn), with different molecular orientation and crystallinity were applied in this research. FDY is spun in the same way as POY and subsequently drawn at high speed and then entangled before winding up. This sample has higher molecular orientation and crystallinity than the POY sample. Several analytical methods were applied in this study: viscometry, X-ray diffraction, FTIR spectroscopy, UV,Visible spectrophotometry, and mechanical testing. Viscometry was used to determine molecular weight as a monitoring factor for degradation. X-ray diagrams showed higher crystallinity for FDY samples during weathering process by irradiation. Results of mechanical testing indicated that the tenacity of the FDY fibers had less deterioration in comparison with the POY ones. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Application of the biodegradable diblock copolymer poly(L -lactide)- block -poly(L -cysteine): Drug delivery and protein conjugationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Jing Sun Abstract A novel approach to self-assembled and shell-crosslinked (SCL) micelles from the diblock copolymer poly(L -lactide)- block -poly(L -cysteine) to be used as drug and protein delivery carriers is described. Rifampicin was used as a model drug. The drug-loaded SCL micelles were obtained by self-assembly of the copolymer in the presence of the drug in aqueous media. Their morphology and size were studied with dynamic light scattering and field emission scanning electron microscopy. The rifampicin loading capacity and encapsulation efficiency were studied with ultraviolet,visible spectrophotometry. The drug-release rate in vitro depended on the oxidizing and reducing environment. Moreover, a straightforward approach to the conjugation of the copolymer with bovine serum albumin (BSA) was developed, and a gel electrophoresis test demonstrated that this conjugated BSA could be reversibly released from the copolymer substrate under reducing conditions. In conclusion, this L -cysteine copolymer can be used in drug delivery and in protein fixation and recovery. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] The addition reaction of diamides to 1,2,5-thiadiazole 1,1-dioxide derivatives,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 12 2004José A. Caram Abstract The reactions of several derivatives of 1,2,5-thiadiazole 1,1-dioxide [3,4-diphenyl-(1a), 3,4-bis(p -methoxyphenyl)-(1b), phenanthro[9,10- c]-(1c) and acenaphtho[1,2-c]-1,2,5-thiadiazole 1,1-dioxide (1d), 3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide (2a) and 4-ethoxy-5-methyl-3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide (2b)], with reagents possessing two nucleophilic nitrogen atoms (urea, N,N,-dimethylurea, thiourea, N -methylthiourea, N -ethylthiourea, N -allylthiourea, N,N,-diethylthiourea, N,N,-diphenylthiourea, dithioxamide and sulfamide), were followed by cyclic voltammetry (CV) and UV,visible spectrophotometry in aprotic solvent solution. The products were isolated, characterized by IR, 1H NMR and 13C NMR methods and their structure was confirmed by single-crystal x-ray diffraction. Several substrate,nucleophile combinations (1a,d and 2a with some ureas and thioureas) reacted to give good yields of new compounds formed by the addition reaction of the two nitrogen atoms of the nucleophile to the two >CN, double bonds of the 1,2,5-thiadiazole 1,1-dioxide ring. Some systems (1a,dithioxamide and 2b,thiourea) did not react, whereas in others (e.g. 1a,sulfamide) a monoaddition equilibrium reaction was observed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Analysis of carotenoids in ripe jackfruit (Artocarpus heterophyllus) kernel and study of their bioconversion in ratsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2005UG Chandrika Abstract Vitamin A deficiency is of public health importance in Sri Lanka. Carotenoids are a significant source of provitamin A. The objective of this study was to analyse the carotenoid composition of jackfruit (Artocarpus heterophyllus sinhala: Waraka) kernel using MPLC and visible spectrophotometry and to determine the bioavailability and bioconversion of carotenoids present in jackfruit kernel by monitoring (i) the growth and (ii) levels of retinol and carotenoids in the liver and serum of Wistar rats provided with jackfruit incorporated into a standard daily diet. Carotenoid pigments were extracted using petroleum ether/methanol and saponified using 10% methanolic potassium hydroxide. Six carotenoids were detected in jackfruit kernel. The carotenes ,-carotene, ,-carotene, ,-zeacarotene, ,-zeacarotene and ,-carotene-5,6-epoxide and a dicarboxylic carotenoid, crocetin, were identified, corresponding theoretically to 141.6 retinol equivalents (RE) per 100 g. Our study indicated that jackfruit is a good source of provitamin A carotenoids, though not as good as papaya. Serum retinol concentrations in rats supplemented with jackfruit carotenoids were significantly higher (p = 0.008) compared with the control group. The same was true for liver retinol (p = 0.006). Quantification was carried out by RP-HPLC. These results show that the biological conversion of provitamin A in jackfruit kernel appears satisfactory. Thus increased consumption of ripe jackfruit could be advocated as part of a strategy to prevent and control vitamin A deficiency in Sri Lanka. Copyright © 2004 Society of Chemical Industry [source] Polypyrrole/polyaniline conductive films obtained electrochemically on polycarbonate-coated platinum electrodesPOLYMER INTERNATIONAL, Issue 12 2002Meral Karak Abstract In this study, two-component free-standing films were obtained by coating a polycarbonate (PC)-coated Pt electrode first with polypyrrole (PPy) in an organic medium and then polyaniline (PAn) in an aqueous medium using an electrochemical technique. The amount of PPy and PAn contained in the films was controlled by varying the electrolysis time. The PC/PPy/PAn films were characterized by cyclic voltammetry, conductivity, FTIR and UV,visible spectrophotometry, and thermogravimetric analysis. The resistance change of the films was determined in the temperature range of ,15 to 120,°C and their temperature sensor properties were investigated. © 2002 Society of Chemical Industry [source] Oxidative polymerization of N -vinylcarbazole in polymer matrixPOLYMER INTERNATIONAL, Issue 6 2001Belkis Ustamehmeto Abstract A new class of soluble conductive poly(N -vinylcarbazole) (PVCz) compounds has been developed by oxidative matrix polymerization of N -vinylcarbazole (NVCz) by Ce(IV) in the presence of poly(ethylene glycol) (PEG). PEG was found to be a more suitable matrix with which to obtain a stable homogenous ternary complex solution when compared with poly(acrylic acid) (PAA) and poly(vinylpyrrolidone) (PVP). The role of PEG, NVCz and Ce(IV) concentration, order of component addition, the structure of the polymer matrix, molecular weight of polymer and the effect of solvent have been investigated. Obtaining soluble PEG,Ce(III),PVCz ternary complexes was shown by cyclic voltammetric measurements, and the initial rate of formation NVCz cation radicals as calculated using UV,visible spectrophotometry. Advantageously with these soluble complexes, conductivities could be measured both in solution and in the solid state. © 2001 Society of Chemical Industry [source] Reactive azo dye reduction by Shewanella strain J18 143BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2006Carolyn I. Pearce Abstract A bacterial isolate designated strain J18 143, originally isolated from soil contaminated with textile wastewater, was shown to reduce intensely coloured solutions of the reactive azo dye, Remazol Black B to colourless solutions. Phylogenetic placement based on 16S rRNA gene sequence homology identified the bacterium as a Shewanella species. Based on results from analyses of the end products of dye decoloration of Remazol Black B and the simpler molecule, Acid Orange 7, using capillary electrophoresis, UV,visible spectrophotometry and liquid chromatography-mass spectrometry, we suggest that colour removal by this organism was a result of microbially mediated reduction of the chromophore in the dye molecules. Anaerobic dye reduction by Shewanella strain J18 143 was 30 times more efficient than the reduction carried out by aerated cultures. Whole cells used a range of electron donors for dye reduction, including acetate, formate, lactate, and nicotinamide adenine dinucleotide (NADH), with formate being the optimal electron donor. The impact of a range of process variables was assessed (including nitrate, pH, temperature, substrate concentration, presence of an extracellular mediator) and results suggest that whole cells of Shewanella J18 143 offer several advantages over other biocatalysts with the potential to treat azo dyes. © 2006 Wiley Periodicals, Inc. [source] | |||||||||||||