Abstract  The application of drug delivery systems in oral environment is relatively a new area of research with the exception of release of fluoride ions from polyalkenoate cements and their predecessor silicate cements. The present study addresses development of a novel device based on ethylene vinyl acetate copolymer (EVA), a biocompatible material which enables constant drug release over several days to treat oral infections. Drugs incorporated in EVA included tetracycline, minocycline and nystatin together with combinations (C) of nytatin-tetracycline (1 : 1) and nystatin-minocycline (1 : 1). Polymer casting solutions were prepared by dissolving EVA and the drugs in the ratio of 10 : 1 in 70 ml of dichloromethane at 38 degreesC for 6 h. Thin square films of 3x3 cm and 1 mm thickness were cut from the dry sheet obtained by solvent evaporation. Drug loaded samples were extracted for a minimum of 15 days in 10 ml medium (water or water/ethanol (1 : 2) or 0.9% saline solution) which is replaced daily. Spectral measurements were made to follow changes in optical densities (OD) during release kinetics. Analysis of the data revealed that among all the drugs tested tetracycline exhibited the highest release rate (56.15ug/cm(2)/day) and % cumulative release (27.92).The observed enhanced values may be interpreted as due to the channels formed due to changes in free volume (microvoids). In case of nystatin-minocycline combination, the observed increased values of release rates and percent cumulative release, may be attributed to the swelling component or channels or relative hydrophobic interactions. Initial "burst" effects due to liberation of surface-bound drug molecules were observed with reference to all the three drugs and the combinations of drugs studied. Among all the drugs, minocycline exhibited the least "burst" effect suggesting that the drug is more homogeneously distributed in the copolymer. Drug loaded EVA thermoplastic copolymer may provide a favorable therapeutic material for the development of a novel, local treatment for oral, mucosal and periodontal infections. (C) 2002 Kluwer Academic Publishers.

Abstract  A total of 36 compounds, which comprised 99.4% of the extract, were identified by gas chromatography and mass spectrometry (GC-MS) in the volatile dichloromethane extract obtained from Egyptian corn silk. The main constituents of the volatile extract were cis-alpha-terpineol (24.22%), 6,11-oxidoacor-4-ene (18.06%), citronellol (16.18%), trans-pinocamphone (5.86%), eugenol (4.37%), neo-iso-3-thujanol (2.59%), and cis-sabinene hydrate (2.28%). Dried Egyptian corn silk was also directly extracted with petroleum ether, ethanol, and water. All extracts from solvent extraction and the volatile extract described above exhibited clear antioxidant activities at levels of 50-400 microg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH)/linoleic acid assay. The ethanol extract inhibited DPPH activity by 84% at a level of 400 microg/mL. All samples tested via the beta-carotene bleaching assay also exhibited satisfactory antioxidant activity with clear dose responses. This study indicates that corn silk could be used to produce novel natural antioxidants as well as a flavoring agent in various food products.

Abstract  The time dependence of carbon dioxide (CO2) transport properties, such as permeability, solubility, and diffusivity, in glassy polyimide membranes was investigated in terms of membrane preparation protocols (i.e., casting solvent and thermal treatment). The polyimide used was 6FDA-TeMPD (4,4-(hexafluoroisopropylidene) diplithalic anhydride) (6FDA)-2,3,5,6-tetramethyl-1,4-phenylene-diamine (TeMPD). The time dependence of C02 permeability in the as-cast 6FDA-TeD4PD membranes prepared from tetrahydrofuran and dichloromethane showed typical CO2-induced plasticization at pressures over 10 atm. The critical plasticization pressure at which CO2-induced plasticization begins to affect the gas permeability shifted from nearly 10-30 atm after heat treatment. The increase in CO2 permeability upon plasticization is mostly caused by an increase in C02 diffusivity. Furthermore, we found that regardless of the membrane preparation protocol, there is a critical CO2 diffusivity of 73 5 x 10-8 CM2/S at the plasticization pressure in 6FDA-TeMPD membranes. (c) 2007 Elsevier B.V. All rights reserved.

Abstract  The study has been done on the effect of heat treatment of activated carbon at 1573-1773 K on its structural and electronic properties as a catalyst support. The X-ray diffraction result indicated that a partly graphitized structure was formed when the activated carbon was heated to a high temperature (1673 K). From the X-ray photoclectron spectroscopy result, it was found that Pt degrees concentration was increased, but PtO and PtO2 concentrations were decreased with an increase in the heat treatment temperature. From the van Dam's model applied to this result, it might be concluded that more "pi-sites" are created as the heat treatment temperature becomes higher. From the CO-chemisorption result, the highest loading was observed in case of Pt/AC1673 sample. This improved loading ability could be explained by the special interaction of the graphitic planes (pi-sites) with the metal particles. Based on the catalytic activity, CO-chemisorption and XPS results, it is concluded that the well-loaded Pt degrees species mainly contribute to the catalytic activity. Moreover, it was found that different degrees of graphitization of heat treated activated carbon Could cause different surface Pt degrees and improve the resistance of carbon support against gasification under air oxidation. (c) 2005 Elsevier Ltd. All rights reserved.

Abstract  In view of developing new drug-delivery systems, microparticles of biocompatible polymer loaded with protein were produced using a supercritical antisolvent technique. As the polymer, poly(lactic acid) (PLA) of about 100 000 Da was used, whereas insulin was chosen as the protein model. To achieve microencapsulation, we started from a homogeneous solution of protein and polymer, to which the supercritical antisolvent is added; mixtures of dichloromethane and dimethyl sulfoxide were used to ensure the solubility of both the polymer and the protein. All experiments were performed in semicontinuous mode. A preliminary study with PLA alone was done in order to select the best operative condition and to control the particle dimension and their diameter distribution range, especially with mixtures of the two solvents. Then, the microspheres of PLA charged with insulin were produced; the average diameters ranged from 0.5 to 2 mum The composition of these particles was determined analytically, and the protein bioactivity was checked.

Abstract  Polymers of lactic and glycolic acid are often used for the production of injectible microparticles with controlled drug release. In the variety of processes used for the microparticle formulation, the Aerosol Solvent Extraction System (ASES) is rather special. Microparticle formation and drying take place in one step by precipitating a methylene chloride solution of the polymer in supercritical CO2. This process sets special requirements to the polymers in crystallinity, solubility, and thermal behavior that are best fulfilled by blocked copolymers. This study investigates a number of lactide-co-glycolide polymers with blocked distribution of the co-monomers by NMR spectroscopy and powder diffraction. The molar ratios are determined by H-1-NMR spectroscopy to verify the manufacturer's declarations of the purchased specimens. Additionally, the block length is determined by application of C-13-NMR. Therefore, a method reported in the literature was modified and evaluated in order to calculate the length of lactide and glycolide sequences in the polymer. Furthermore, this study looks at the impact of synthesis conditions on block length and crystallinity, and the impact of the blocking on both, crystallinity and solubility of the polymers. (C) 2000 Elsevier Science Ltd. All rights reserved.

Abstract  In this research, char was prepared from Switchgrass (Panicum virgatum) cave-in-rock species and characterized from the perspective of value addition either as a soil amendment or as a feedstock for energy production. Char from torrefaction/pyrolysis was produced in a fixed bed lab-scale reactor, using a N-2 flow at three temperatures (300, 400, and 500 degrees C) and for two residency times (2.5 and 5 minutes). Proximate and ultimate analyses as well as calorific value tests were done on each of the chars obtained. Chars scanning electron microscopy (SEM) pictures were taken. Organic composition of char leachates was characterized using gas chromatography-mass spectrometry (GC-MS) following a Soxhlet extraction with dichloromethane. Char was analyzed using FTIR-ATR. No significant difference was observed in most char characteristics between 2.5 and 5 min residency times, for each temperature studied. Among the compounds identified, two may be of particular interest with respect to the biochar domain. 1-undecanol, a compound commonly used as a growth regulator in agriculture, was observed in 300 and 400 degrees C chars for 5 and 2.5 min residence time, respectively. Naphthalene, commonly used as an ingredient in pesticide products, was the only polycyclic aromatic hydrocarbon (PAH) observed in chars and was found solely in the extracts obtained from the char produced at 500 degrees C (for both residency times).

Abstract  The sorption and transport properties of small molecules in a glassy liquid crystalline random copolyester, composed of 73 mol% p-hydroxybenzoic acid and 27 mol% 6-hydroxy-2-naphthoic acid (HBA/HNA), are reported. Acetone and methylene chloride sorption levels were extraordinarily low in HBA/HNA, and isotherms were convex to the activity axis, suggesting plasticization of the region of polymer accommodating penetrant sorption. These composite observations suggested that penetrant solubility may be limited to disclination regions between liquid crystalline domains. The gravimetric sorption kinetics were described by the Fickian model at low penetrant activities but exhibited non-Fickian protracted drifts at high penetrant activities, despite low overall penetrant concentrations. The values of acetone and methylene chloride diffusion coefficients in HBA/HNA were comparable to diffusion coefficient values of these penetrants in conventional glassy polymers.

Abstract  The development of potassium fluoride as a practical non-covalent support for a carboxylic acid containing a pyrrolidine substituent with organocatalytic activity in the asymmetric Michael addition is described. The immobilization is carried out by simply treating the catalytic ligand in dichloromethane (DCM) solution with non-anhydrous potassium fluoride (KF). XRD and FTIR results suggest that the organocatalyst is efficiently loaded onto KF through strong hydrogen bond (SHB) formation, affording the KF-supported catalyst (KF-supCAT, 8) for the direct asymmetric Michael addition of carbonyl compounds to trans-beta-nitrostyrenes. Good yields, excellent diastereoselectivities (up to 99:1 syn:anti) and excellent enantioselectivities (up to 97% ee for the syn diastereomer) are recorded in the Michael additions of cyclohexanone to trans-beta-nitrostyrenes, considerably improving previous results obtained with a closely related catalyst covalently immobilized onto polystyrene. The KF-supCAT could be recovered and recycled three times by increasing the supersaturation degree of the solution. (C) 2013 Elsevier Inc. All rights reserved.

Abstract  Deposits from different sections of a newsprint paper mill, using 100% recovered paper, were analyzed following an analytical procedure based on scaning electron microscopy-electron dispersive X-ray and consecutive solvent extraction steps with Fourier-transform infrared spectroscopy (FTIR) analyses of the different fractions. Polyvinyl acetate, polyacrylates, styrene butadiene rubber, and derivatives of fatty acids/resin acids are the main stickies-related components identified in the deposits. The removal efficiency of these contaminants along the deinking line was studied by determining the composition of the dichloromethane extractives in the pulp by FTIR analyses. Although the total stickies content is reduced considerably during the process, some compounds, which are found in the deposits, are not removed selectively in the process, indicating their recalcitrant nature. FTIR analyses of unusable materials coming with the raw material (mainly board and mixed office waste) have demonstrated that these materials are one of the main sources of these types of recalcitrant stickies.

Abstract  Some new 5-substituted 8-hydroxyquinoline derivatives and their Al(III) complex dyes (Al(2)(3)-Al(9)(3)) have been synthesised. The compounds were characterized by H-1, C-13, mass and elemental analysis. The aluminium complexes retain the spectroscopic properties of the parent compound, namely, tris(8-hydroxyquinolinato) aluminium (III) (AlQ(3)). In dichloromethane solution, these aluminium complexes show absorption maxima in the range of 390-395 nm, strong green luminescence in the range 527-536 nm and aluminium complexes show high fluorescence quantum yield in solution and thin films. The fluorescence decay in solution as well as in thin film is fitted to biexponential with tau(av) ranging from 3 to 9 ns. Electroluminescence (EL) of the spin-cast film of Al(3)(3) (3 = 5-(2-ethylhexyloxymethyl)-8-hydroxyquinoline) as the emitting layer was performed and the turn-on voltage for the EL device is about 11 V. (c) 2004 Elsevier Ltd. All rights reserved.

Abstract  Electron paramagnetic resonance spectroscopy (X-band, 9.3 GHz) was used to characterize paramagnetic centres of reductively ethylated and butylated Polish flame coal (70.8 wt% C) in a potassium-liquid ammonia system. The processes of reduction and reductive alkylation decreased total concentration of paramagnetic centres in this coal. The decrease in the total amount of paramagnetic centres with the increase in H/C atomic ratio of the sample was observed for multistage reduced and butylated coa;. Different correlations between total concentration of free radicals in 1-4 times reduced and reductively butylated coal and their yield of dichloromethane extract were demonstrated. Numerical analysis of the lineshape of the e.p.r. spectra proved existence of two groups of paramagnetic centres with narrow and broad lines in the studied coal samples. Paramagnetic centres responsible for the broad e.p.r. components were the most active during reductive alkylation of the coal. (C) 1998 Elsevier Science Ltd. All rights reserved.

Abstract  In response to producer reports of poor efficacy using published treatments against Ichthyophthirius multifiliis (ich) infestations of channel catfish Ictalurus punctatus, we initiated a preliminary study to see which of the compounds that are permissible in food-fish aquaculture were efficacious under what we judged to be ideal laboratory conditions. We planned to use the results of this work as a basis for further study in the field. In our studies we used fingerling catfish in glass aquariums with stable water quality and daily treatments in both static and flow-through water systems. In some experiments, infested fish and healthy fish were stocked together so that the ability of the treatment to eliminate preexisting infestations could be examined separately from the treatment's ability to block transmission. Malachite green and methylene blue were used as positive controls, and untreated fish were used as the negative control for efficacy. Treatments with sodium chloride, hydrogen peroxide, potassium permanganate, elevated temperatures, chloramine-T, povidone iodine, and high flow rates were ineffective under all conditions and concentrations tested. Alternate-day treatments with formalin at 25 and 50 mg/L in static water or 100 mg/L in flow-through water aquariums were not effective at eliminating infestations or preventing fish-to-fish transmission. Daily treatments with 50 mg/L formalin in static water or 100 mg/L formalin in flow-th-rough water aquariums were toxic to channel catfish. Formalin at 25 mg/L in static water aquariums was effective at eliminating infestations and reducing fish-to-fish transmission when used as a daily treatment. Copper sulfate was effective in blocking the infestation of healthy fish, but it did not eliminate established infestations on channel catfish, even after 20 daily treatments under static conditions. Malachite green and methylene blue eliminated established infestations on fish, whereas copper only prevented transmission; this suggests that the dyes are able to penetrate deeply or act systemically, allowing them to kill subcutaneous stages of ich. Further field trials were not pursued because none of the legal or economically viable treatments showed efficacy under presumably ideal laboratory conditions.

Abstract  Mated and virgin female and virgin male tobacco budworm moths, Heliothis virescens (F.), responded via directed upwind flight in wind-tunnel bioassays to volatiles from floral extracts of cotton, Gossypium hirsutum L. Significantly more male and female moths landed on cloth dispensers treated with a methylene chloride extract of debracted flowers than on control dispensers treated only with methylene chloride. Only mated females landed in significant numbers on the dispensers treated with extract of cotton squares, flowers (including bracts), or flower petals. After landing, most of the moths examined the dispensers by probing with their antennae, proboscis, and/or ovipositor.

Abstract  A flat flame simulation was performed to model experimental data from a dichloromethane/methane/air flame. A detailed elementary reaction mechanism was used to carry out the simulation and to obtain insights about key chemical processes occurring in various regions of the flame. The flame was at stoichiometric conditions with a Cl/H ratio of 0.34. The PREMIX flat flame program was used to obtain the calculated results. Comparisons between calculation and experiment were good for the three reactants and five of the seven stable intermediates for which experimental data were available. Calculated CO2 and CO profiles were also good, but were found to be offset from experiment by 0.02 cm, with the calculated profiles occurring too late in the flame. A reaction rate analysis found that the flame developed in three stages, an initiation stage, a chlorine inhibited oxidation stage, and finally CO burnout by the reaction CO + OH. The initiation stage was dominated by chlorine abstraction of H atoms from the fuel species and recombination of dichloromethyl, chloromethyl and methyl radicals to C-2's. This initiation stage was found to occur in the flame at temperatures of 1070 K to 1500 K. The oxidation stage was characterized by temperatures between 1500 K and 1660 K. CO2 formation from CO + OH was found to be inhibited in the initiation stage and oxidation stage. Once the temperature reached 1660 K OH radicals became available through the endothermic reactions O + H2O and O + HCl, and CO + OH became the dominant pathway for CO2 formation.

Abstract  Nymphal lone star ticks, Amblyomma americanum, were allowed to engorge on domestic rabbits that had received diets containing 0, 5 or 10% perennial snakeweed foliage. Tick attachment was reduced 39 and 35% on rabbits ingesting 5 and 10% snakeweed foliage, respectively. Adult ticks reared from engorged nymphs showed no treatment differences in survivability, engorgement weight or hatchability of egg masses. In a study conducted on sheep, adult ticks, confined in cells to an area with half of the skin surface treated with methylene chloride extracts of snakeweed foliage, attached significantly less often to treated skin compared to cells half-treated with acetone. When confined in cells to an area totally treated with snakeweed foliage extracts, a mean of 12.5, 4.5 and 0 ticks (out of 40 ticks per cell) attached to skin treated with acidic, basic or neutral extracts, respectively, compared to a mean of 16.7 in acetone-treated cells.

Abstract  V(x)-SBA-15 materials (vanadium content in the 0.7-4.8 wt.% range) were prepared by direct synthesis and tested in the catalytic decomposition of dichloromethane: a SBA-15 silica and a V/SBA-15 prepared by impregnation were used as reference samples. The structural and surface properties of all samples were characterized by means of complementary physico-chemical techniques. V(x)-SBA-15 materials containing isolated vanadium sites were catalytically active towards dichloromethane conversion, with maximum conversion obtained by the catalyst having 2.2 wt.% vanadium. In V(x)-SBA-15 materials prepared by direct synthesis, vanadium occurs mainly as isolated sites with tetrahedral coordination as far as its content does not reach the theoretical monolayer capacity (ca. 4 wt.%): unlike catalysts prepared by traditional impregnation method, oligomeric VOx species form only at high vanadium content. (C) 2010 Elsevier Inc. All rights reserved.

Abstract  Nineteen plant extracts from 16 medicinal plants were assayed for their antifungal activity against rice pathogenic fungi on PDA plates containing plant extracts. Among the plants tested. Aegle marmelos, Desmos chinensis, and Micromelum minutum revealed moderate to strong activities against 5 tested fungal species with more than 65.1% inhibition. The dichloromethane extract from D. chinensis leaves showed high antifungal activity against all 6 fungi. The dichloromethane extract possessed antifungal activity against Bipolaris oryzae, Pyricularia oryzae, and Sclerotium rolfsii with minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values ranging from 3.9 to 31.2 mu g/ml and 31.2 to 500 mu g/ml, respectively. Bioautography assay on TLC plates with Bipolaris setariae, Curvularia lunata, Fusarium moniliforme, P. oryzae, and S. rolfsii displayed high antifungal activity with RI-value ranging from 0.32 to 0.37. Effects of the extract on the morphology of B. setariae, C. lunata, F. moniliforme, P. oryzae, and S. rolfsii were observed by scanning electron microscopy. The micrographs of mycelia and spores treated with the extract at 4MIC illustrated aberrant surface morphology and reduced conidial formation in 4 fungal species. The results demonstrated that D. chinensis extract possess antifungal activity against phytopathogenic fungi and the activity might lead to irreversible cellular disruption. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  We explored the potential of Burma rosewood, Dalbergia oliveri in dengue fever vector control by evaluating various extracts as larvicides and growth disruptors of Aedes aegypti Linnaeus (Diptera: Culicidae) under laboratory conditions. Third instars and pupae of the mosquito were tested using WHO guidelines. Highest larvicidal effect was obtained with dichloromethane and hexane extracts (LC50 = 289.1 and 325.3 ppm, respectively) within 24 h post-treatment. However, toxicity was about 1.78-fold more in dichloromethane extracts than hexane extract, if treatment was given for longer duration of 48 h (LC90 = 5048.5 ppm for hexane and 2848.1 ppm for dichloromethane extracts, respectively). In these treatments moderate inhibition of pupation was also seen with some larvae staying as 4th stage larvae for 8 days before dying. There were no significant differences in the sex ratio of emerged adults compared with the controls. Dichloromethane extract, being most active, was subjected to sequential chemical separation to obtain series of isoflavonoids. Three compounds (+)-medicarpin, formononetin and (+/-)-violanone were identified as active larvicides of Ae. aegypti. Significant pupal mortality was observed with dichloromethane extract treatment of 1-3 h old pupae after 48 h post-treatment (LC50 = 1004.5 ppm). Isoflavonoid medicarpin (LC50 = 296.72 ppm) was most active compound against pupae. Eclosion inhibition (EI) was also observed in pupae treated with dichloromethane extract (EI50 of 668.7 ppm). Thus, naturally occurring larvicides can be particularly effective where larval habitats are readily identifiable. Results obtained should be of value in the search for new natural larvicidal compounds from other extracts as well and represent the first report of this plant species being used to control a mosquito vector. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  A novel dimethylglyoxime (DMG)/poly(caprolactone) (PCL) blend was electrospun into fibers to serve as an optical sensor for the nickel detection based on the formation of a red Ni(DMG)(2) complex. DMG was mixed with PCL at 10, 20 and 30% (w/w) in a mixture of N, N-dimethylformamide (DMF) and dichloromethane (DCM) (50/50, v/v) prior electrospunning process. The best fibers were prepared under an electric field of 20 kV and a distance between needle and collector of 20cm. From scanning electron microscopy (SEM), the average diameter of the fibers remained nearly constant with increasing amount of DMG. The optimum mass ratio of DMG and PCL was found to be 20:80 as it produced fibers with the smallest diameter distribution and the best sensing property. The formation of the Ni(DMG)(2) complex was confirmed by Fourier transform infrared spectroscopy (FT-IR). The colorimetric response of the PCL/DMG electrospun fibers were then tested against the nickel ions over a concentration range of 1-10 ppm using reflectance spectroscopy. Good linearity between the reflectance values at 547 nm and the concentrations was obtained (R(2) = 0.9925). These proposed DMG and PCL fibers could be used as the naked-eye sensor for nickel in waste water. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  Mass spectrometry is a major tool for analysing organic pollutants. However, scientists often complain about laborious sample preparation. The development of new commercial high-resolution mass spectrometers gives a chance to improve simultaneously speed, reliability, and sensitivity of the analysis. Here, we used the time-of-flight high-resolution mass spectrometer Pegasus GC-HRT to identify and quantify 55 priority organic pollutants in water samples. This mass spectrometer has a high resolution of 50,000, a high mass accuracy of about 1 ppm and a very high acquisition rate of up to 200 full mass range spectra per second. 1 mL water samples were extracted with 1 mL dichloromethane. Results show that the sample preparation and analysis are achieved 30 times faster, requiring 1,000 times less water and 350 times less solvent than the classic 8270 method of the United States Environmental Protection Agency. The detection limit is 1 mu g/L. The quantification limit is 10 mu g/L. Our procedure, named accelerated water sample preparation, is simpler, faster, cheaper, safer and more reliable than 8270 Method.

Abstract  Petroleum asphaltenes exhibit strong structural similarities to their parent kerogen. Thus, they can be used to help determine the source rock characteristics of active kitchen areas and to reconstruct the filling histories of reservoirs. The analysis of asphaltenes from compartmentalised reservoirs with complex charging and alteration histories presents a particularly difficult challenge because the in situ compositional variations are sometimes subtle. It is, therefore, of paramount importance that asphaltene separation methods be Utilised which are highly reproducible and linear, thereby minimising experimental uncertainty and providing high resolution interpretative capability. The asphaltene separation method described here is built on many that have been proposed before. Different parameters for asphaltene separation were investigated, which influence the asphaltene amount and properties, with the main focus on reproducibility and linearity. Gravimetric and thermal analysis techniques were used to evaluate yield and quality. The developed asphaltene separation method described in detail has four sequential steps: (1) dissolution of the oil in dichloromethane/l vol% methanol, (2) addition of an excess of n-hexane, (3) settling time and (4) filtration, purging and weighing; this sequence of steps is repeated three times. Results concerning the reproducibility depending on solvent type, solvent amount and aging time, as well as the linearity depending on sample amount, are presented. (c) 2008 Elsevier Ltd. All rights reserved.

Abstract  Dipolar compounds containing both quinoxaline/pyridopyrazine acceptors and arylamine/carbazole donors have been prepared by palladium catalyzed C-C coupling (Stille) reactions in good yields and have been characterized by spectroscopic, electrochemical and thermal methods. The charge transfer character of these molecules can be changed by modification of the acceptor or donor ends. They are green emitting with moderate quantum yields in toluene solutions. However, in dichloromethane the emission maximum is red shifted and the quantum yield diminishes appreciably. High glass transition temperatures were realized for these compounds (143-162 degreesC). The quinoxaline derivatives effectively function as a hole-transporting and emitting layer in yellow/orange emitting double layer electroluminescent devices. We also demonstrate the possibility of using these materials in single layer devices.

Abstract  The ethanolic, dichloromethane and lyophilized aqueous extracts of Cassia occidentalis root bark, Morinda morindoides leaves and whole plants of Phyllanthus niruri were evaluated for their antimalarial activity in vivo, in 4-day, suppressive assays against Plasmodium berghei ANKA in mice. No toxic effect or mortality was observed in mice treated, orally, with any of the extracts as a single dose, of 500 mg/kg body weight, or as the same dose given twice weekly for 4 weeks (to give a total dose of 4 g/kg). No significant lesions were observed, by eye or during histopathological examinations, in the hearts, lungs, spleens, kidneys, livers, large intestines or brains of any mouse. At doses of 200 mg/kg, all the ethanolic and dichloromethane extracts produced significant chemosuppressions of parasitaemia (of > 60% for C. occidentalis root bark and Ph. niruri whole plant, and of 30% for M. morindoides leaves) when administered orally. The most active ethanolic extract, that of Ph. niruri, reduced parasitaemia by 73%. The dichloromethane extracts of M. morindoides and Ph. niruri produced similar reductions (74% and 72% chemosuppression, respectively), whereas that of C. occidentalis was slightly less active (60% chemosuppression). Each lyophilized aqueous extract was less active than the corresponding ethanolic extract.