Abstract  BIOSIS COPYRIGHT: BIOL ABS. The objective of this research was to identify chemical, physical, bacteriological, and viral contaminants, and their sources, which present the greatest health threat in public ground water supplies in the USA; and to classify (prioritize) such contaminants and relative to their health concerns. The developed contaminant prioritization methodology was based on frequency of occurrence and adverse health effects. Adverse health effects were based on carcinogenic potency, toxicity, hazardous chemical priorities and drinking water standards. Application of the methodology for wellhead protection areas, (WHPAs) revealed that approximately 200 different contaminants have been detected in the nation's public ground water supplies. The seven chemical constituents with the highest priority were arsenic, chromium, cadmium, carbon tetrachloride, chloroform, 1, 1-dichloroethylene, and ethylene dibromide. Other contaminants of concern were trichloroethylene, nitrates, barium, 1,1,

Abstract  Low-field proton NMR was evaluated as a nondestructive and rapid technique for measuring ethanol-soluble extractives in southern pine wood. Matchstick-sized wood specimens were steeped in extractive-containing solutions to generate extractive-enriched samples for analysis. Decay curves obtained by the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence were analyzed with Contin, a constrained regularization program used to generate continuous distributions of transverse (spin-spin) relaxation times. Air-dry wood samples gave maximum signal amplitudes that did not clearly reflect differences in extractives content. Oven drying removed signals for bound water that were superposed with those for the extractives. Relaxation times and the corresponding amplitudes were then positively correlated with the added extractives. Treatment of air-dry samples with dichloromethane-d(2) prior to analysis increased the mobility of the extractives, thereby resulting in a shift of the corresponding signals to longer relaxation times. This provided the opportunity to quantify the added extractives in the presence of bound water.

Abstract  One of today's leading packaging concepts in microelectronics and microsystems is the technology of Low Temperature Cofiring Ceramics (LTCC). It is based on ceramic tapes that sinter at low temperatures (< 950 degrees C) and are capable of fine-line wiring by use of high-conductivity metals, preferably silver (theta(m) = 961 degrees C).

To lower sintering temperatures of crystalline powders, glass powder is added. Depending on the amount of glass added, two mechanisms of sintering are possible: reactive or nonreactive liquid phase sintering. Reactive sintering requires small amounts (< 10 vol.%) of a very low softening glass (theta(soft) < 400 degrees C). If the glass amount is increased to more than 50 vol.%, nonreactive sintering occurs in the glass softening range. According to the microstructure observed for each case, the respective types of materials are called Glass Bonded Ceramics (GBC) and Glass Ceramic Composites (GCC).

Integration of microwave filters in LTCC multilayers requires inner dielectric layers with medium, temperature-stable permittivities (epsilon(r) = 30 to 60) and low dielectric loss (tan delta < 2.10(-3)). Up to now, appropriate materials have been realized only by GBC sintering at 900degreesC and above. Hence, pure silver metallization is not possible. To overcome this limitation, GCC are a promising way. Therefore, crystalline substances possessing epsilon(t) of about 100 and low dielectric loss - for example Ba(La, Nd)(2)Ti(4)Ol(2) - were combined with special high-permittivity glasses. A development of such glasses is presented in this work. Addition of oxides of easily polarizable elements (e. g. Nb2O5, La2O3, TiO2) effects an increase in permittivity of selected basis compositions from the systems BaO-Al2O3-B2O3-SiO2 (epsilon(r) up to 15) and La2O3-Ba2O3-TiO2 (epsilon(r) up to 20). GCC mixtures made of 65 vol.% of these glasses and 35 vol.% BaLa2Ti4O12 showing microwave properties and sintering temperatures below 900degreesC are introduced.

Abstract  A new series of subphthalocyanine-borondipyrromethene scaffolds containing N-ethylcarbazole moiety have been successfully designed and synthesized. The identities of synthesized compounds were confirmed by using H-1, C-13 NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The photophysical properties of the newly synthesized subphthalocyanine-borondipyrromethene conjugates were investigated via absorption and fluorescence spectroscopies in dichloromethane, tetrahydrofuran, benzene, and toluene solution (1 x 10(-5) M). The targeted compounds exhibit a highly efficient energy transfer process, either from the excited borondipyrromethene to the subphthalocyanine core or from the excited subphthalocyanine to the mono or distyryl borondipyrromethene unit. The time resolved fluorescence studies of the subphthalocyanine-borondipyrromethene conjugates were also examined. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  Development of a novel fixed site carrier membrane (FCM), supported by PET fabric for metal ion separation is reported. The membranes were prepared by dipping PET fabric into the methylene chloride solution of Poly(5-vinyl-m-phenylene-m'-phenylene-32-crown-10) (P(VCE)), a polymeric metal ion carrier. It was found that the flux of mono-valent metal ion transported across the membrane is significantly differed from each other and the flux decreases in the order Cs+ > Rb+ > K+ > Na+ > Li+ irrespective to the anion except perchlorate anion. It was explained in terms of the stability of the complex, formed by crown ether unit of the P(VCE) and the various metal ions, meanwhile, the lower rate of transport in the presence of perchlorate anion was ascribed to its low hydrophilicity.

Abstract  The removal of hydrogen sulfide (H2S) from airstreams was studied in a biotrickling filter (BTF) packed with plastic Pall rings operating with counter-current flows of the air and liquid streams. Experiments were performed at different inlet H2S concentrations, air and/or liquid volumetric flow rates, and sulfate concentrations in the recirculating liquid to check their effect on the performance of the BTF. Conversion of H2S never dropped below 80% at the highest concentration and reached 100% at low concentrations. A maximum removal rate of 22.5 g H2S m(-3) reactor h(-1) was observed with 100% removal efficiency. The shortest empty bed retention time studied at which complete H2S removal was observed was around 11 s. Conversion of H2S was found to slightly increase as the liquid flow rate decreased and as the air flow rate increased. (c) 2005 Society of Chemical Industry.

Abstract  Ultra-low density porous polystyrene monoliths have been prepared via using water/styrene gel-emulsions, which were stabilized by a low-molecular mass gelator (LMMG), as templates. It was demonstrated that the porous materials as prepared possess a number of superior features such as highly adjustable internal structure and density, the lowest density could be lower than 0.01 g cm(-3). Moreover, such materials can be used as excellent absorbents for many organic liquids including viscous oils like mineral oil and high-density oils such as dichloromethane. In particular, the absorption process is fast, selective and efficient when they are used in the purification of oil contaminated water. Importantly, the oils absorbed in the absorbent can be easily squeezed out, and furthermore the wet absorbent as obtained can be reused by suitable washing and natural drying. More importantly, the LMMG-based gel-emulsions employed as templates are simple in preparation, only mixing and agitation at ambient temperature are required. Moreover, further treatment of the wet porous materials as prepared from the templates is just washing and natural drying, which is completely different from those such as freeze-drying or supercritical drying widely adopted by others in the preparation of low density materials via routine approaches. It is believed that the LMMG-based gel-emulsion template method developed in the present work may have created a novel and facile way for preparing low density materials with ideal properties.

Abstract  A rapid and simple analytical procedure allowing accurate quantification of aliphatic and aromatic hydrocarbons in sediments and petroleum has been developed. Sediments were Soxhlet extracted using methylene chloride for 48h. Oil maltene fractions were isolated by asphaltene precipitation in pentane. Sediment and oil extracts were first purified using alumina micro-columns. Saturated fractions were then separated from aromatic ones by fractionation on silica gel. Alkanes and polycyclic aromatic hydrocarbons (PAHs) were analyzed separately by gas chromatography coupled to mass spectrometry (GC-MS). PAHs and alkanes were quantified relative to perdeuterated PAHs and alkanes introduced prior to extraction. For accurate quantification, it is important to use several perdeuterated alkanes that cover the volatility range of alkanes of interest and at least one perdeuterated PAH per class of aromaticity. This analytical procedure has been validated on a reference material sediment (SRM 1941a) and a reference material crude oil (SRM 1582). This analytical procedure was then applied to the study of the contamination of marine sediments collected along the Atlantic coast after the Erika oil spill (December 1999).

Abstract  Studies were carried out on the influence of Prunus africana heartwood extractives on the growth of selected wood decay fungi. Also, wood chemical and mineral content, dimensional stability and anatomical features of P. africana were studied. Heartwood extractives were tested in 100 ppm and 500 ppm concentrations on white, brown rot, and blue stain fungi and growth inhibition was determined as a factor of time. Dimensional stability was determined by computing the swelling coefficient after the blocks were saturated with moisture. Klason lignin, Kurschner cellulose, extractive and ash contents were determined by standard procedures. Infrared analyses were performed using Perkin Elmer FTIR spectrometer. Microscopic examination was peiformed using an environmental scanning electron microscope. The results showed that the wood is dimensionally stable, and contains 12.7 % extractives, 37.6 % cellulose and 30.4 % lignin. Extractives deposited in vessels are highly soluble in dichloromethane and mainly composed of terpenes. Extractives were able to inhibit the growth of white rot fungi Coriolus versicolor, brown rot fungi Poria placenta and blue stain fungi Aureobasidium pullulans at different concentrations tested and could explain the high durability of Prunus africana wood species.

Abstract  A novel procedure for the manufacture of celecoxib-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles is described that is based upon combining salting out and emulsion-evaporation steps. An entrapment efficiency, a measure of the actual to theoretical drug content, of 97.3% was achieved, being superior to that achieved when these popular techniques were used separately (emulsion evaporation, 40.1%; salting out, 10.0%). The ratio of a water miscible solvent (acetone) to a non water-miscible solvent (dichloromethane) was shown to be the primary determinants of size and drug loading. Once optimized, using an organic phase of 3 : 1 acetone : dichloromethane vol : vol ratio, further control on particle parameters could be exerted using modification of acetone diffusion by alterations in MgCl2 x 6H2O concentration. This step was shown to have a small effect on both the mean nanoparticle size and entrapment efficiency, but found to reduce the polydispersity considerably. Diffusion control using a 45% w/v MgCl2 x 6H2O solution produced nanoparticles with a mean size of 151.4 nm, a polydispersity index of 0.023 and 98.1% entrapment efficiency. Electron microscopy showed the particles to be smooth and spherical. Sheer homogenization during the emulsification step was shown to be not as effective as sonication, with the latter technique able to produce nanoparticles after 1 min of application. Drug release studies across a semi-permeable membrane demonstrated a reduction in the burst effect as the ratio of acetone in the organic phase was increased. Calorimetry studies suggested that celecoxib existed in the nanoparticle as a molecular dispersion, with additional evidence for a strong interaction between the PLGA and the absorbed poly(vinyl alcohol) stabilizer. Formation of a strong interaction between celecoxib and PLGA, together with the formation of a radial drug gradient give a release profile that does not possess the prevalent burst effect seen with other nanoparticulate drug-loaded systems.

Abstract  It is investigated whether composite particles composed of waste polymer and solid powder are able to be prepared by using a semi-chemical recycle method. In the experiment, polystyrene pellets as waste polymer, dichloromethane as the solvent and magnetite as the solid powder are adopted. This solution of the dispersed phase was dispersed into fine droplets in the continuous water phase. In the case of the lower impeller speed and the lower temperature for removing the solvent, composite particles coated with solid powder can be prepared. However, with increasing impeller speed and temperature, the dispersion became unstable and then the composite particles can not be prepared.

Abstract  Mosquito repellent textile materials are being increasingly in demand as a preventive measure to protect the consumers from mosquito-borne diseases like malaria, dengue, etc. Many of these agents are applied in post-colouration operation to the fabric. Although initially they show good repellency against mosquitoes, upon repeated washing cycles, this effect gets diminished considerably. In the present work, nylon fabric is imparted mosquito repellent finish in one, single operation of dyeing cum finishing. This approach is based on the modification of commonly used mosquito-repellent N,N-diethyl-m-toluamide (DEET) and synthesizing a reactive dye based on this important ingredient. A reactive dye was synthesized in order to impart mosquito repellency to the nylon 6 fabric, DEET was first subjected to nitration using Potassium nitrate and dichloromethane (DCM). This nitrated product was reduced in the presence of water: ethanol (30:70) and the amine, thus, produced was then condensed with 2, 4, 6-trichloro-1, 3, 5-triazine (cyanuric chloride) a reactive group. The resultant product was finally reacted with an amino group present in 6-Amino-2-naphthalenesulphonic acid (Bronner's acid) to obtain Sodium6-((4-(diethylcarbamoyl)-2-methylphenyl) amino)-1, 3, 5-triazin-2-yl) amino) naphthalene-2-sulfonate (reactive dye). This reactive dye was then applied on nylon 6 fabric by covalent bonding to provide mosquito-repellent material. The chemical structures of the dye were characterized using FTIR and H-1-NMR spectroscopy. The melting point of the dye was characterized by Differential Scanning Calorimetry. The fastness properties of the dyed cum finished fabric were measured to evaluate the performance of the dye. Efficacy of mosquito repellency of the treated nylon 6 fabric was studied using standard methods. The nylon 6 fabric reacted with the mosquito-repellent dye and showed very good durable mosquito-repellent activity.

Abstract  Experimental data for the phase behavior of poly(L-lactic acid) (PLA) in mixtures of dichloromethane and carbon dioxide over a range of external conditions are presented. Cloud point pressures were measured using a variable-volume view cell as functions of temperature, dichloromethane-to-carbon dioxide ratio, and concentration of PLA. A high-molecular-weight (M-w 189 000) PLA was used in all studies and at mass fractions of 0.01, 0.02, and 0.03. For adequate control of the carbon dioxide-to-dichloromethane ratio, a new experimental procedure was employed that allows for good control of the composition. To ascertain the validity of the new experimental procedure, the binary system of carbon dioxide + dichloromethane was studied, and its results were compared to literature values.

Abstract  Data from infrared analyses are presented on the functional groups present in dichloromethane-soluble polycyclic aromatic hydrocarbon (PAH) material sampled from sooting flames as a function of height above the burner. The trends in the data indicate that PAH become progressively more aromatic (and less aliphatic) in nature as they grow up to the point of soot nucleation. At the soot nucleation point, the aromatic-to-aliphatic ratio drops dramatically. These changes are occurring in a zone of the flame in which the temperature is rapidly rising. A hypothesis is presented in which the cleavage of aliphatic groups or loss of aliphatic hydrogens from PAH coincides with the reactive coagulation of PAH to form soot nuclei.

Abstract  The synthesis and characterization of two new uranyl-salen complexes, 1-2, based on a 1,2-diaminomaleonitrile unit, is described. Spectroscopic studies to evaluate their potential as colorimetric probes for fluoride detection in chloroform and dichloromethane were undertaken. Compound 2 exhibits a 'turn-on' response characterized by a naked-eye colorimetric change for the selective recognition of fluoride in both solvents. DFT calculations show that the stabilization energy for the formation of the host:guest complex follows the trend F- > Cl- > Br- hence supporting the experimental data. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  This paper describes the electrodeposition of tetrabutylammonium bis(1,3-dithiol-2-thione-4,5-dithiolate) nickelate (Bu4NNi(dmit)(2)) onto platinum, gold interdigitated and fluoride-doped tin oxide electrodes. The effects of adding pyrrole, thiophene, 3-methylthiophene and furan to the deposition solution on the film morphology were investigated. The bulk conductivity of the deposited films was found to be 4 x 10(-2) S cm(-1) irrespective of the heterocycle added. Cyclic voltammetry was carried out using the three electrodes: the gold and platinum electrodes showed similar electrochemical behaviour, with the peaks assigned to the redox properties of the metal-dmit; the SnO2 electrode did not yield any distinct peaks. It is suggested that this was because the rate of electron transfer to the SnO2 electrode was the rate-limiting step rather than the rate of diffusion to the electrode surface as in the case of the platinum and gold electrodes. The films deposited onto the interdigitated gold electrodes were exposed to sulphur dioxide and changes in the film resistance were monitored. Films deposited in dichloromethane had a much lower surface area than those deposited from nitrobenzene, and the magnitude of the change in resistance on exposure to sulphur dioxide was a factor of four tower than for the films deposited in nitrobenzene. Studies were also carried out on copper and cobalt dmit analogues; the copper-dmit behaved in a similar manner to the nickel-dmit, although the films were of very low conductivity,whereas the cobalt-dmit showed no reversible redox behaviour. (C) 1997 Elsevier Science S.A.

Abstract  A feasibility study has been carried out of the analysis of total condensate (at -50-degrees-C) of smoke from smoldering combustion of wood. All of the phenol and furan components in the aqueous condensate were extracted into methylene chloride and the extract was analyzed by GC/MS. The same homologues of guaiacol and syringol derived from lignin were detected as have been described in earlier studies, but in addition, a series of furan derivatives were found. The latter are believed to arise from pyrolysis of polysaccharides. The carboxylic acids in the condensates were analyzed by titration and subsequent GC/MS. Acetic acid was the dominant volatile acid found, with a trace of propanoic, but no significant formic acid.

Abstract  Novel cationic gemini surfactants, 1,3-bis[(acyloxyalkyl)dimethylammonio]-2-hydroxypropane dichloride, which possess hydrolyzable oxycarbonyl moieties in the lipophilic portions, were prepared. These surfactants showed much better micelle-forming ability, ability to lower surface tension, foaming ability, and foam stability than corresponding single-chain surfactants. Their surface properties were largely influenced by changing the position of the oxycarbonyl group in the lipophilic moiety. The critical micelle concentration decreased with a decreasing number of methylene units in the linking moiety between the ammonio and the oxycarbonyl groups within the comparison of lipophilic chains of the same length. These cationic gemini surfactants also showed good biodegradability.

Abstract  Twenty-seven carboxamide derivatives of (+/-)-cis-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (permethrin acid) have been synthesized and evaluated in the laboratory against mosquito larvae (Aedes aegypti). These cis-cyclopropylcarboxamides, with N-(substituted)phenyl, N-(substituted)phenylmethyl, N-(substituted)phenylethyl, N-phenylpropyl, and N-phenylbutyl groups, were synthesized from the acid chloride of permethrin acid and various arylamines in methylene chloride. The samples were characterized by C-13 NMR spectroscopy and mass spectrometry. Secondary amides with electron-donating (e.g., methoxy) and electron-withdrawing (e.g., trifluoromethyl) substituents on the phenyl ring as well as nine tertiary amides were investigated. 3-(2,2-Dichloroethenyl)-2,2-dimethyl-N-(3-phenoxyphenyl)methylcyclopropanecarboxamide was the most active experimental compound and was 25 times less potent than (+/-)-cis-permethrin. Cyclopropylcarboxamides of the N-(substituted)phenyl, N-(substituted)phenylethyl, and N-phenylpropyl types were essentially inactive in the larvicidal tests.

Abstract  We present a periodic density functional theory study of the energetic profile of the fluorination of dichloromethane over the (0 0 0 1) surface of alpha-alumina. This is a model system for the industrially important fluorination process used in synthesis of fluorohydrocarbon replacements of the environmentally detrimental chlorofluorcarbons. The results indicate that HF is readily, and strongly, chemisorbed to the alumina surface producing a surface fluorine ion and a hydroxyl group. Using this model of the fluorinated surface we calculate the adsorption energy of dichloromethane and estimate the barrier to its reaction to CH2ClF through an S(N)2 scheme with the surface fluorine acting as a nucleophile. From the energy profile generated we propose a kinetic scheme and estimate the expected experimentally observed barrier for the overall process. To test the calculation results we have also carried out experimental studies of dichloromethane fluorination over alpha-alumina and show that the calculated and measured activation energies are in good agreement. (C) 2000 Elsevier Science B.V. All rights reserved.

Abstract  A 100-200-mesh methoxybenzhydrylamine resin was used as a solid carrier. The first amino acid was introduced on the resin, and all 28 amino acids of peptide A were subsequently coupled, by the carbodiimide method. The a-amino function was protected with BOC group, and the side chains were blocked with the following groups: Asp, cyclohexyl; Ser and Thr, benzyl; and Tyr 2-bromobenzyloxycarbonyl. Boc(Fmoc)Lys were added at positions 11, 12, 20, 21 and 29 to have at further steps the analog contg. hArg in these positions. Boc was removed with 55% TFA in dichloromethane, and Fmoc was removed with 50% piperidine in DMF After Fmoc was removed from Lys, the substituted guanidine group was introduced by the reaction with NN% bis(tert-butyloxycarbonyt)-S-methylisothiourea in the presence of 4-(N,N-dimethylamino)pyridine. All Boc were removed from the fully protected peptidyl polymer by the reaction with trifluoroacetic acid. The remaining protecting groups left the peptide while it was cleaved from the resin with liq. HF The HF was removed, the residue was washed with Et2O, and crude peptide was extd. with 50% AcOH and lyophilized. The acetate form was obtained on an ion-exchange resin and preparative HPLC gave 99.7% pure A. Polysulfonic filters were used during the preparation of the stable and reproducible pharmaceutical form of A, viz., an aq. lyophilizate (phosphate buffer) contg. 100 mu g peptide A and mannitol per ampule. Peptide A was about a few score times as bioactive as the hGH-RH reference peptide, completely nontoxic in doses up to 120 ig and resistant to enzymatic degradation, increased the level of hGH and the no. of somatotropic cells in animal pituitary glands, and affected no other pituitary hormones.

Abstract  Imidazole and 2-chloropyridine were used as model molecules to investigate the acid hydrolysis kinetics of agrochemicals in high-temperature water in a batch reactor system at 28MPa. Pseudo-first-order hydrolysis reaction rate constants for the acid hydrolysis of Imidazole and 2-chloropyridine were determined in the temperature ranges 200600 and 400575 degrees C, respectively, at 28MPa. Rate constants for both compounds increased with temperature with a local maximum observed at around 400 degrees C due to changes in the physical properties of the solvent. Imidazole and 2-chloropyridine conversions of 0.95 and 0.99999 were respectively attained at the highest temperature after 30min of reaction. (c) 2012 Canadian Society for Chemical Engineering

Abstract  Poly(p-phenylene) (PPP) films were synthesized by using benzene and fluorosulphonic acid (FSO3H) as a strong acid containing Ag+, Pb2+ and Cu+ ions in methylene chloride (CH,CI,) solution. Addition of Ag+ or Pb2+ ions into the polymerization medium improved the PPP films formation, but Cu+ ion did not have an effect on polymerization. PPP films were characterized by cyclic voltammetry, IR and TGA. Dry conductivities were measured by using four probe technique.