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Sample records for 1,4-dioxane

  1. Butallylonal 1,4-dioxane hemisolvate

    Ulrich J. Griesser

    2010-10-01

    Full Text Available The asymmetric unit of the title compound [systematic name: 5-(1-bromoprop-2-en-1-yl-5-sec-butylpyrimidine-2,4,6-trione 1,4-dioxane hemisolvate], C11H15BrN2O3·0.5C4H8O2, contains one half-molecule of 1,4-dioxane and one molecule of butallylonal, with an almost planar barbiturate ring [largest deviation from the mean plane = 0.049 (5 Å]. The centrosymmetric dioxane molecule adopts a nearly ideal chair conformation. The barbiturate molecules are linked together by an N—H...O hydrogen bond, giving a single-stranded chain. Additionally, each dioxane molecule acts as a bridge between two antiparallel strands of hydrogen-bonded barbiturate molecules via two hydrogen bonds, N—H...O(dioxaneO...H—N. Thus, a ladder structure is obtained, with the connected barbiturate molecules forming the `stiles' and the bridging dioxane molecules the `rungs'.

  2. Thermophysical study of 1,4-dioxane with cycloalkane mixtures

    Romero, C. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Ciudad Universitaria, 50009 Zaragoza (Spain); Giner, B. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Ciudad Universitaria, 50009 Zaragoza (Spain); Haro, M. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Ciudad Universitaria, 50009 Zaragoza (Spain); Artigas, H. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Ciudad Universitaria, 50009 Zaragoza (Spain); Lafuente, C. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Ciudad Universitaria, 50009 Zaragoza (Spain)]. E-mail: celadi@unizar.es

    2006-07-15

    Densities, refractive indices, and surface tension for the binary mixtures 1,4-dioxane with cyclopentane or cylohexane have been determined at ambient pressure and at T = (283.15, 298.15, and 313.15) K. Excess volumes and refractive index and surface tension deviations have been calculated from the experimental data. Several relations between the thermophysical properties studied here have been tested using our experimental results.

  3. Stable Isotopic and Molecular Biological Tools to Validate Biodegradation of 1,4-Dioxane

    2014-01-01

    1,4-Dioxane, a probable human carcinogen, is a heterocyclic ether increasingly found as a contaminant in water supplies. Recent studies have reported that 1,4-dioxane can be biodegraded by a variety of microorganisms, and bioremediation may be an effective strategy for 1,4-dioxane contaminated sites. However, reliable monitoring tools to validate biodegradation of 1,4-dioxane are still lacking. Molecular biological tools and stable isotope-based tools have been previously applied as diagno...

  4. Biodegradation of 1,4-dioxane: effects of enzyme inducers and trichloroethylene.

    Hand, Steven; Wang, Baixin; Chu, Kung-Hui

    2015-07-01

    1,4-Dioxane is a groundwater contaminant and probable human carcinogen. In this study, two well-studied degradative bacteria Mycobacterium vaccae JOB5 and Rhodococcus jostii RHA1 were examined for their 1,4-dioxane degradation ability in the presence and absence of its co-contaminant, trichloroethylene (TCE), under different oxygenase-expression conditions. These two strains were precultured with R2A broth (complex nutrient medium) before supplementation with propane or 1-butanol to induce the expression of different oxygenases. Both propane- and 1-butanol-induced JOB5 and RHA1 were able to degrade 1,4-dioxane, TCE, and mixtures of 1,4-dioxane/TCE. Complete degradation of 1,4-dioxane/TCE mixture was observed only in propane-induced strain JOB5. Inhibition was observed between 1,4-dioxane and TCE for all cells. Furthermore, product toxicity caused incomplete degradation of 1,4-dioxane by 1-butanol-induced JOB5. In general, the more TCE degraded, the greater extent of product toxicity cells experienced; however, susceptibility to product toxicity was found to be both strain- and inducer-dependent. The findings of this study provide fundamental basis for developing an effective in-situ remediation method for 1,4-dioxane-contaminated ground water and the first known study of 1,4-dioxane degradation by wild-type strain RHA1.

  5. Phytoremediation of 1,4-dioxane-containing recovered groundwater.

    Ferro, Ari M; Kennedy, Jean; LaRue, James C

    2013-01-01

    The results of a pilot-scale phytoremediation study are reported in this paper. Small plots of trees established on a closed municipal waste landfill site were irrigated with recovered groundwater containing 1,4-dioxane (dioxane) and other volatile organic compounds (VOCs). The plots were managed to minimize the leaching of irrigation water, and leaching was quantified by the use of bromide tracer. Results indicated that the dioxane (2.5 microg/L) was effectively removed, probably via phytovolatilization, and that a full-scale phytoremediation system could be used. A system is now in place at the site in which the recovered groundwater can be treated using two different approaches. A physical treatment system (PTS) will be used during the winter months, and a 12 ha phytoremediation system (stands of coniferous trees) will be used during the growing season. The PTS removes VOCs using an air-stripper, and destroys dioxane using a photo-catalytic oxidation process. Treated water will be routed to the local sewer system. The phytoremediation system, located on the landfill, will be irrigated with effluent from the PTS air-stripper containing dioxane. Seasonal use of the phytoremediation system will reduce reliance on the photo-catalytic oxidation process that is extremely energy consumptive and expensive to operate.

  6. Fate of 1,4-dioxane in the aquatic environment: from sewage to drinking water.

    Stepien, Daria K; Diehl, Peter; Helm, Johanna; Thoms, Alina; Püttmann, Wilhelm

    2014-01-01

    Potential health effects of 1,4-dioxane and the limited data on its occurrence in the water cycle command for more research. In the current study, mobility and persistence of 1,4-dioxane in the sewage-, surface-, and drinking water was investigated. The occurrence of 1,4-dioxane was determined in wastewater samples from four domestic sewage treatment plants (STP). The influent and effluent samples were collected during weekly campaigns. The average influent concentrations in all four plants ranged from 262 ± 32 ng L(-1) to 834 ± 480 ng L(-1), whereas the average effluent concentrations were between 267 ± 35 ng L(-1) and 62,260 ± 36,000 ng L(-1). No removal of 1,4-dioxane during water treatment was observed. Owing to its strong internal chemical bonding, 1,4-dioxane is considered non-biodegradable under conventional bio-treatment technologies. The source of increased 1,4-dioxane concentrations in the effluents was identified to originate from impurities in the methanol used in the postanoxic denitrification process in one of the STPs. In view of poor biodegradation in STPs, surface water samples were collected to establish an extent of 1,4-dioxane pollution. Spatial and temporal distribution of 1,4-dioxane in the Rivers Main, Rhine, and Oder was examined. Concentrations reaching 2200 ng L(-1) in the Oder River, and 860 ng L(-1) in both Main and Rhine River were detected. The average monthly load of 1,4-dioxane in the Rhine River was calculated to equal to 172 kg d(-1). In all rivers, concentration of 1,4-dioxane increased with distance from the spring and was found to negatively correlate with the discharge of the river. Additionally, bank filtration and drinking water samples from two drinking water facilities were analyzed for the presence of 1,4-dioxane. The raw water contained 650 ng L(-1)-670 ng L(-1) of 1,4-dioxane, whereas the concentration in the drinking water fell only to 600 ng L(-1) and 490 ng L(-1), respectively. Neither of the purification

  7. Enhanced decomposition of 1,4-dioxane in water by ozonation under alkaline condition.

    Tian, Gui-Peng; Wu, Qian-Yuan; Li, Ang; Wang, Wen-Long; Hu, Hong-Ying

    2014-01-01

    1,4-Dioxane is a probable human carcinogenic and refractory substance that is widely detected in aquatic environments. Traditional wastewater treatment processes, including activated sludge, cannot remove 1,4-dioxane. Removing 1,4-dioxane with a reaction kinetic constant of 0.32 L/(mol·s) by using ozone, a strong oxidant, is difficult. However, under alkaline environment, ozone generates a hydroxyl radical (•OH) that exhibits strong oxidative potential. Thus, the ozonation of 1,4-dioxane in water under different pH conditions was investigated in this study. In neutral solution, with an inlet ozone feed rate of 0.19 mmol/(L·min), the removal efficiency of 1,4-dioxane was 7.6% at 0.5 h, whereas that in alkaline solution was higher (16.3-94.5%) within a pH range of 9-12. However, the removal efficiency of dissolved organic carbon was considerably lower than that of 1,4-dioxane. This result indicates that several persistent intermediates were generated during 1,4-dioxane ozonation. The pseudo first-order reaction further depicted the reaction of 1,4-dioxane. The obvious kinetic constants (kobs) at pH 9, 10, 11 and 12 were 0.94, 2.41, 24.88 and 2610 L/(mol·s), respectively. Scavenger experiments on radical species indicated that •OH played a key role in removing 1,4-dioxane during ozonation under alkaline condition.

  8. Physiologically based Pharmacokinetic Modeling of 1,4-Dioxane in Rats, Mice, and Humans

    Sweeney, Lisa M.; Thrall, Karla D.; Poet, Torka S.; Corley, Rick; Weber, Thomas J.; Locey, B. J.; Clarkson, Jacquelyn; Sager, S.; Gargas, M. L.

    2008-01-01

    ABSTRACT 1,4-Dioxane (CAS No. 123-91-1) is used primarily as a solvent or as a solvent stabilizer. It can cause lung, liver and kidney damage at sufficiently high exposure levels. Two physiologically-based pharmacokinetic (PBPK) models of 1,4-dioxane and its major metabolite, hydroxyethoxyacetic acid (HEAA), were published in 1990. These models have uncertainties and deficiencies that could be addressed and the model strengthened for use in a contemporary cancer risk assessment for 1,4-dioxane. Studies were performed to fill data gaps and reduce uncertainties pertaining to the pharmacokinetics of 1,4-dioxane and HEAA in rats, mice, and humans. Three types of studies were performed:partition coefficient measurements, blood time course in mice, and in vitro pharmacokinetics using rat, mouse, and human hepatocytes. Updated PBPK models were developed based on these new data and previously available data. The optimized rate of metabolism for the mouse was significantly higher than the value previously estimated. The optimized rat kinetic parameters were similar to those in the 1990 models. Only two human studies were identified. Model predictions were consistent with one study, but did not fit the second as well. In addition, a rat nasal exposure was completed. The results confirmed water directly contacts rat nasal tissues during drinking water under bioassays. Consistent with previous PBPK models, nasal tissues were not specifically included in the model. Use of these models will reduce the uncertainty in future 1,4-dioxane risk assessments.

  9. Physiologically based pharmacokinetic modeling of 1,4-Dioxane in rats, mice, and humans.

    Sweeney, Lisa M; Thrall, Karla D; Poet, Torka S; Corley, Richard A; Weber, Thomas J; Locey, Betty J; Clarkson, Jacquelyn; Sager, Shawn; Gargas, Michael L

    2008-01-01

    1,4-Dioxane (CAS No. 123-91-1) is used primarily as a solvent or as a solvent stabilizer. It can cause lung, liver, and kidney damage at sufficiently high exposure levels. Two physiologically based pharmacokinetic (PBPK) models of 1,4-dioxane and its major metabolite, hydroxyethoxyacetic acid (HEAA), were published in 1990. These models have uncertainties and deficiencies that could be addressed and the model strengthened for use in a contemporary cancer risk assessment for 1,4-dioxane. Studies were performed to fill data gaps and reduce uncertainties pertaining to the pharmacokinetics of 1,4-dioxane and HEAA in rats, mice, and humans. Three types of studies were performed: partition coefficient measurements, blood time course in mice, and in vitro pharmacokinetics using rat, mouse, and human hepatocytes. Updated PBPK models were developed based on these new data and previously available data. The optimized rate of metabolism for the mouse was significantly higher than the value previously estimated. The optimized rat kinetic parameters were similar to those in the 1990 models. Only two human studies were identified. Model predictions were consistent with one study, but did not fit the second as well. In addition, a rat nasal exposure was completed. The results confirmed water directly contacts rat nasal tissues during drinking water under bioassay conditions. Consistent with previous PBPK models, nasal tissues were not specifically included in the model. Use of these models will reduce the uncertainty in future 1,4-dioxane risk assessments.

  10. Organocatalytic Enantioselective Synthesis of 1,4-Dioxanes and Other Oxa-Heterocycles by Oxetane Desymmetrization.

    Yang, Wen; Sun, Jianwei

    2016-01-26

    A new asymmetric synthesis of chiral 1,4-dioxanes and other oxa-heterocycles has been developed by means of organocatalytic enantioselective desymmetrization of oxetanes. This mild process proceeds with exceedingly high efficiency and enantioselectivity to establish the quaternary stereocenters. This method complements the existing, yet limited, strategies for the synthesis of these oxa-heterocycles.

  11. FIELD STUDY: IN SITU OXIDATION OF 1,4-DIOXANE WITH OZONE AND HYDROGEN PEROXIDE

    A pilot-scale field evaluation is underway to assess the effectiveness of in situ oxidation (using ozone with and without hydrogen peroxide) for remediation of 1,4-dioxane and chlorinated volatile organic compounds in groundwater at the Cooper Drum Company Superfund Site located ...

  12. Activated Persulfate Treatment of 1,4-Dioxane in the Presence of Chlorinated Solvent Co-contaminants

    Boving, T. T.; Eberle, D. E. H.; Ball, R.

    2014-12-01

    1,4-dioxane is an emerging groundwater contaminant and a likely human carcinogen. Due to its history as a stabilizer in chlorinated solvents, 1,4-dioxane is often found as a co-contaminant at solvent releases sites such as landfills, solvent recycling facilities, vapor decreasing operations, and fire-training areas. Historically, 1,4-dioxane was not routinely analyzed for at solvent release sites. The lack of analyses and the limitations of the analyses that were performed (i.e. high reporting limits) means that the scale of 1,4-dioxane subsurface contamination is still emerging. With the number of known 1,4-dioxane sites increasing, the need for cost effective 1,4-dioxane remediation technologies is rising as well. Remediation strategies that are capable of treating both 1,4-dioxane as well as chlorinated co-contaminants are of particular importance, especially when treating mixed-waste source zones. In the present study, we examined the fate of 1,4-dioxane during the targeted remediation of aqueous phase volatile organic compounds (VOC) using an activated persulfate based ISCO method (OxyZone®). Bench scale laboratory experiments are used to evaluate the treatability of 1,4-dioxane both as a single compound and in the presence of trichloroethene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA). Possible dependencies on oxidant concentration and reaction kinetics were studied. Preliminary results are promising and show that OxyZone® is persistent and long lived, with oxidation of 1,4-dioxane continuing more than 12 days after initial dosage, even at dilute oxidant concentrations. The oxidative destruction of 1,4-dioxane, TCE and 1,1,1-TCA in single compound batch systems followed pseudo first order reaction kinetics. The rate of oxidation for each contaminant increased linearly with increasing persulfate concentration over the range of oxidant concentrations tested. The rate of oxidative destruction, from most easily degraded to least was: TCE > 1,4-Dioxane > 1

  13. Short-chain grafting of tetrahydrofuran and 1,4-dioxane cycles on vinylchloride-maleic anhydride copolymer

    2009-01-01

    Full Text Available Mass increase of vinylchloride-maleic anhydride (VC-MA copolymer samples aged in tetrahydrofuran (THF or in 1,4-dioxane results from chemical interaction of VC-MA macromolecules with 1,4-dioxane or THF. Microstructure of the products of such modification was proved by infrared spectroscopy (IR- and nuclear magnetic resonance spectroscopy (13C NMR and 1H NMR. Mechanism of modification has been proposed. The results of microstructure research of VC-MA samples aged in THF and in 1,4-dioxane coincide with already known data on the reactions of opening of these and other oxygen-containing cycles under mild conditions.

  14. Proof-of-Concept Study: Novel Microbially-Driven Fenton Reaction for In Situ Remediation of Groundwater Contaminated with 1,4-Dioxane, Tetrachloroethene (PCE) and Trichloroethene (TCE)

    2014-09-17

    1,4-dioxane is also a byproduct of surfactant and polyethylene terephthalate plastic manufacturing processes.6, 11, 12 1,4-dioxane is completely...hydrogen peroxide process. Environ Sci Technol 1998, 32, (11), 1588-1595. 2. Sun, B. Z.; Ko, K.; Ramsay, J. A., Biodegradation of 1,4-dioxane by a...Flavobacterium. Biodegradation 2011, 22, (3), 651-659. 3. Mahendra, S.; Alvarez-Cohen, L., Kinetics of 1,4-dioxane biodegradation by monooxygenase

  15. 76 FR 54225 - Draft Toxicological Review of 1,4-Dioxane: In Support of Summary Information on the Integrated...

    2011-08-31

    ... phone: 703-750-3000, ext. 6727, or toll free at 1-800-2-VERSAR (ask for Betzy Colon, the 1,4-Dioxane... noncancer health effects and cancer assessments. Combined with specific exposure information, government...

  16. A shock tube and theoretical study on the pyrolysis of 1,4-dioxane.

    Yang, X; Jasper, A W; Giri, B R; Kiefer, J H; Tranter, R S

    2011-03-07

    The dissociation of 1, 2 and 4% 1,4-dioxane dilute in krypton was studied in a shock tube using laser schlieren densitometry, LS, for 1550-2100 K with 56 ± 4 and 123 ± 3 Torr. Products were identified by time-of-flight mass spectrometry, TOF-MS. 1,4-dioxane was found to initially dissociate via C-O bond fission followed by nearly equal contributions from pathways involving 2,6 H-atom transfers to either the O or C atom at the scission site. The 'linear' species thus formed (ethylene glycol vinyl ether and 2-ethoxyacetaldehyde) then dissociate by central fission at rates too fast to resolve. The radicals produced in this fission break down further to generate H, CH(3) and OH, driving a chain decomposition and subsequent exothermic recombination. High-level ab initio calculations were used to develop a potential energy surface for the dissociation. These results were incorporated into an 83 reaction mechanism used to simulate the LS profiles with excellent agreement. Simulations of the TOF-MS experiments were also performed with good agreement for consumption of 1,4-dioxane. Rate coefficients for the overall initial dissociation yielded k(123Torr) = (1.58 ± 0.50) × 10(59) × T(-13.63) × exp(-43970/T) s(-1) and k(58Torr) = (3.16 ± 1.10) × 10(79) × T(-19.13) × exp(-51326/T) s(-1) for 1600 < T < 2100 K.

  17. Experimental and Theoretical Investigation of Valence Orbitals in 1,4-Dioxane by Electron momentum Spectroscopy

    YANG Tie-Cheng; NING Chuan-Gang; SU Guo-Lin; DENG Jing-Kang; ZHANG Shu-Feng; REN Xue-Guang; HUANG Yan-Ru

    2006-01-01

    @@ The binding energy spectrum of all valence orbitals and the momentum distributions of highest occupied molecular orbital (HOMO: 8ag), 7bu + 7ag, 4bu, 2bg + 4ag and 2au in 1, 4-dioxane are investigated by electron momentum spectroscopy (EMS) with 600 e V impact energy. The experimental results are consistent with theoretical calculations of C2h chair conformation using the Hartree-Fock method and density functional theory with 6-311++G**and A UG-CC-PVTZ basis sets.

  18. Indomethacin solubility estimation in 1,4-dioxane + water mixtures by the extended hildebrand solubility approach

    Miller A Ruidiaz

    2011-09-01

    Full Text Available Extended Hildebrand Solubility Approach (EHSA was successfully applied to evaluate the solubility of Indomethacin in 1,4-dioxane + water mixtures at 298.15 K. An acceptable correlation-performance of EHSA was found by using a regular polynomial model in order four of the W interaction parameter vs. solubility parameter of the mixtures (overall deviation was 8.9%. Although the mean deviation obtained was similar to that obtained directly by means of an empiric regression of the experimental solubility vs. mixtures solubility parameters, the advantages of EHSA are evident because it requires physicochemical properties easily available for drugs.

  19. Characterizing the intrinsic bioremediation potential of 1,4-dioxane and trichloroethene using innovative environmental diagnostic tools.

    Chiang, Sheau-Yun Dora; Mora, Rebecca; Diguiseppi, William H; Davis, Greg; Sublette, Kerry; Gedalanga, Phillip; Mahendra, Shaily

    2012-09-01

    An intrinsic biodegradation study involving the design and implementation of innovative environmental diagnostic tools was conducted to evaluate whether monitored natural attenuation (MNA) could be considered as part of the remedial strategy to treat an aerobic aquifer contaminated with 1,4-dioxane and trichloroethene (TCE). In this study, advanced molecular biological and stable isotopic tools were applied to confirm in situ intrinsic biodegradation of 1,4-dioxane and TCE. Analyses of Bio-Trap® samplers and groundwater samples collected from monitoring wells verified the abundance of bacteria and enzymes capable of aerobically degrading TCE and 1,4-dioxane. Furthermore, phospholipid fatty acid analysis with stable isotope probes (PLFA-SIP) of the microbial community validated the ability for microbial degradation of TCE and 1,4-dioxane. Compound specific isotope analysis (CSIA) of groundwater samples for TCE resulted in δ(13)C values that indicated likely biodegradation of TCE in three of the four monitoring wells sampled. Results of the MNA evaluation showed that enzymes capable of aerobically degrading TCE and 1,4-dioxane were present, abundant, and active in the aquifer. Taken together, these results provide direct evidence of the occurrence of TCE and 1,4-dioxane biodegradation at the study site, supporting the selection of MNA as part of the final remedy at some point in the future.

  20. Improvement of Lithium Interface Stability with 1,4-dioxane Pretreatment

    2007-01-01

    1,4-dioxane (DOA) was originally used to pretreat the lithium metal electrode in order to improve its interface stability. Electrochemical impedance spectra (EIS) measurements reveal that with DOA pretreatment, lithium electrode has a low and stable interracial resistance during the storage in electrolyte for a long time. And it is also found that the pretreated lithium electrode has an improved inteffacial performance in repeated charge/discharge cycles. Furthermore, it is proved by SEM that the pretreated one has smooth morphology after long-time storage or repeated charge/discharge cycles. Consequentially, because of more stable interface characteristics of lithium electrode, the rechargeable lithium cell with DOA pretreated lithium anode has an obviously enhanced discharging performance and a better cycleability, compared with that of the cell using the untreated lithium anode.

  1. SYNTHESIS AND POLYMERIZATION OF 2-OXO-3-METHYLENE-5,6-DIPHENYL-1,4-DIOXAN

    FENG Pinzhen; LU Jiantao

    1994-01-01

    A new cyclic monomer, 2-oxo-3-methylene-5, 6-diphenyl-1,4-dioxan, was synthesized. The structure of the intermediates and the monomer were determined by IR,1H NMR,13C NMR and elemental analysis. This new monomer is different from other cyclic monomers in this series,it is a solid (mp 108-109℃)and not very reactive,but still can undergo free radical ring-opening polymerization. The free radical polymerization was carried out at 130℃. The structure of the resulting polymer was discussed and charaterized by IR, 1H NMR, 13C NMR and elemental analysis. The molecular weight of the polymer was estimated by viscosity determination.

  2. Advanced Electrochemical Oxidation of 1,4-Dioxane via Dark Catalysis by Novel Titanium Dioxide (TiO2) Pellets.

    Jasmann, Jeramy R; Borch, Thomas; Sale, Tom C; Blotevogel, Jens

    2016-08-16

    1,4-dioxane is an emerging groundwater contaminant with significant regulatory implications. Because it is resistant to traditional groundwater treatments, remediation of 1,4-dioxane is often limited to costly ex situ UV-based advanced oxidation. By varying applied voltage, electrical conductivity, seepage velocity, and influent contaminant concentration in flow-through reactors, we show that electrochemical oxidation is a viable technology for in situ and ex situ treatment of 1,4-dioxane under a wide range of environmental conditions. Using novel titanium dioxide (TiO2) pellets, we demonstrate for the first time that this prominent catalyst can be activated in the dark even when electrically insulated from the electrodes. TiO2-catalyzed reactors achieved efficiencies of greater than 97% degradation of 1,4-dioxane, up to 4.6 times higher than noncatalyzed electrolytic reactors. However, the greatest catalytic enhancement (70% degradation versus no degradation without catalysis) was observed in low-ionic-strength water, where conventional electrochemical approaches notoriously fail. The TiO2 pellet's dark-catalytic oxidation activity was confirmed on the pharmaceutical lamotrigine and the industrial solvent chlorobenzene, signifying that electrocatalytic treatment has tremendous potential as a transformative remediation technology for persistent organic pollutants in groundwater and other aqueous environments.

  3. The first hyperpolarizability of p-nitroaniline in 1,4-dioxane : A quantum mechanical/molecular mechanics study

    Jensen, L; van Duijnen, PT

    2005-01-01

    In this work we have investigated the first hyperpolarizability of pNA in 1,4-dioxane solution using a quantum mechanics/molecular mechanics (QM/MM) model. The particular model adopted is the recently developed discrete solvent reaction field (DRF) model. The DRF model is a polarizable QM/MM model i

  4. Kinetics and energy efficiency for the degradation of 1,4-dioxane by electro-peroxone process

    Wang, Huijiao; Bakheet, Belal; Yuan, Shi; Li, Xiang; Yu, Gang [School of Environment, Tsinghua University, Beijing 100084 (China); Murayama, Seiichi [Power and Industrial Systems R& D Center, Toshiba Corporation, Fuchu-shi, Tokyo (Japan); Wang, Yujue, E-mail: wangyujue@tsinghua.edu.cn [School of Environment, Tsinghua University, Beijing 100084 (China)

    2015-08-30

    Highlights: • E-peroxone couples electrolysis with ozonation to driven peroxone reaction for pollutant degradation. • Significant amounts of ·OH can be efficiently produced in the E-peroxone process. • E-peroxone greatly enhances 1,4-dioxane degradation kinetics compared with ozonation and electrolysis. • E-peroxone consumes less energy for 1,4-dioxane mineralization than ozonation and electrolysis. • E-peroxone offers a cost-effective and energy-efficient alternative to degrade 1,4-dioxane. - Abstract: Degradation of 1,4-dioxane by ozonation, electrolysis, and their combined electro-peroxone (E-peroxone) process was investigated. The E-peroxone process used a carbon-polytetrafluorethylene cathode to electrocatalytically convert O{sub 2} in the sparged ozone generator effluent (O{sub 2} and O{sub 3} gas mixture) to H{sub 2}O{sub 2}. The electro-generated H{sub 2}O{sub 2} then react with sparged O{sub 3} to yield aqueous ·OH, which can in turn oxidize pollutants rapidly in the bulk solution. Using p-chlorobenzoic acid as ·OH probe, the pseudo-steady concentration of ·OH was determined to be ∼0.744 × 10{sup −9} mM in the E-peroxone process, which is approximately 10 and 186 times of that in ozonation and electrolysis using a Pt anode. Thanks to its higher ·OH concentration, the E-peroxone process eliminated 96.6% total organic carbon (TOC) from a 1,4-dioxane solution after 2 h treatment with a specific energy consumption (SEC) of 0.376 kWh g{sup −1} TOC{sub removed}. In comparison, ozonation and electrolysis using a boron-doped diamond anode removed only ∼6.1% and 26.9% TOC with SEC of 2.43 and 0.558 kWh g{sup −1} TOC{sub removed}, respectively. The results indicate that the E-peroxone process can significantly improve the kinetics and energy efficiency for 1,4-dioxane mineralization as compared to the two individual processes. The E-peroxone process may thus offer a highly effective and energy-efficient alternative to treat 1,4-dioxane

  5. Near infrared cavity enhanced absorption spectra of atmospherically relevant ether-1, 4-Dioxane

    Chandran, Satheesh; Varma, Ravi

    2016-01-01

    1, 4-Dioxane (DX) is a commonly found ether in industrially polluted atmosphere. The near infrared absorption spectra of this compound has been recorded in the region 5900-8230 cm- 1 with a resolution of 0.08 cm- 1 using a novel Fourier transform incoherent broadband cavity-enhanced absorption spectrometer (FT-IBBCEAS). All recorded spectra were found to contain regions that are only weakly perturbed. The possible combinations of fundamental modes and their overtone bands corresponding to selected regions in the measured spectra are tabulated. Two interesting spectral regions were identified as 5900-6400 cm- 1 and 8100-8230 cm- 1. No significant spectral interference due to presence of water vapor was observed suggesting the suitability of these spectral signatures for spectroscopic in situ detection of DX. The technique employed here is much more sensitive than standard Fourier transform spectrometer measurements on account of long effective path length achieved. Hence significant enhancement of weaker absorption lines above the noise level was observed as demonstrated by comparison with an available measurement from database.

  6. In-situ activation of persulfate by iron filings and degradation of 1,4-dioxane.

    Zhong, Hua; Brusseau, Mark L; Wang, Yake; Yan, Ni; Quig, Lauren; Johnson, Gwynn R

    2015-10-15

    Activation of persulfate by iron filings and subsequent degradation of 1,4-dioxane (dioxane) was studied in both batch-reactor and column systems to evaluate the potential of a persulfate-enhanced permeable reactive barrier (PRB) system for combined oxidative-reductive removal of organic contaminants from groundwater. In batch experiments, decomposition of persulfate to sulfate and degradation of dioxane both occurred rapidly in the presence of iron filings. Conversely, dioxane degradation by persulfate was considerably slower in the absence of iron filings. For the column experiments, decomposition and retardation of persulfate was observed for transport in the columns packed with iron filings, whereas no decomposition or retardation was observed for transport in columns packed with a reference quartz sand. Both sulfate production and dioxane degradation were observed for the iron-filings columns, but not for the sand column. The pH of the column effluent increased temporarily before persulfate breakthrough, and significant increases in both ferrous and ferric iron coincided with persulfate breakthrough. Multiple species of free radicals were produced from persulfate activation as determined by electron paramagnetic resonance (EPR) spectroscopy. The impact of the oxidation process on solution composition and iron-filings surface chemistry was examined using ICP-MS, SEM-EDS, and XRD analyses. A two-stage reaction mechanism is proposed to describe the oxidation process, consisting of a first stage of rapid, solution-based, radical-driven decomposition of dioxane and a second stage governed by rate-limited surface reaction. The results of this study show successful persulfate activation using iron filings, and the potential to apply an enhanced PRB method for improving in-situ removal of organic contaminants from groundwater.

  7. (2,2′-Bipyridine-κ2N,N′dichloridopalladium(II 1,4-dioxane hemisolvate

    Ricardo Alfredo Gutiérrez Márquez

    2014-06-01

    Full Text Available The asymmetric unit of the title compound, [PdCl2(C10H8N2]·0.5C4H8O2, consists of one PdII complex molecule and a half-molecule of 1,4-dioxane, the complete molecule being generated by inversion symmetry. The PdII atom has an almost square-planar coordination formed by the 2,2′-bipyridine ligand and two chloride ligands. Two intramolecular C—H...Cl hydrogen bonds occur. In the crystal, the PdII complex and 1,4-dioxane molecules are connected by C—H...O hydrogen bonds, forming a layer parallel to (10-1. Within the layer, weak π–π interactions [centroid–centroid distance = 3.817 (4 Å] are observed between the pyridine rings.

  8. Neutron Scattering of Residual Hydrogen in 1,4-Dioxane-D8 Liquid. Understanding Measurements with Molecular Dynamics Simulations

    de Almeida, Valmor F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liu, Hongjun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Herwig, Kenneth W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kidder, Michelle [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-01-25

    That incoherent scattering from protiated molecular liquids adds a constant background to the measured scattering intensity is well known, but less appreciated is the fact that coherent scattering is also induced by the presence of hydrogen in a deuterated liquid. In fact, the scattering intensity can be very sensitive, in the small-q region, with respect to the amounts and distribution of residual H in the system. We used 1,4-dioxane liquid to demonstrate that the partial structure factors of the HD and DD atom pairs contribute significantly to inter-molecular scattering and that uncertainty in the extent of deuteration account for discrepancies between simulations and measurements. Both contributions to uncertainty have similar magnitudes: scattering interference of the hydrogen-deuterium pair, and complementary interference from the deuterium-deuterium pair by virtue of chemical inhomogeneity. This situation arises in practice since deuteration of liquids is often 99% or less. A combined experimental and extensive computational study of static thermal neutron scattering of 1,4-dioxane demonstrates the foregoing. We show, through simulations, that the reason for the differences is the content of protiated dioxane (vendors quote 1%). We estimate that up to 5% (at 298K and at 343K) protiated mole fraction may be involved in generating the scattering differences. Finally, we find that the particular distribution of hydrogen in the protiated molecules affects the results significantly; here we considered molecules to be either fully protiated or fully deuterated. This scenario best reconciles the computational and experimental results, and leads us to speculate that the deuteration synthesis process tends to leave a molecule either fully deuterated or fully protiated. Although we have used 1,4-dioxane as a model liquid, the effects described in this study extend to similar liquids and similar systematic experimental/computational studies can be performed to either

  9. Acoustical Studies of Some Schiff Bases in 1,4-Dioxane and Dimethylformamide at 318.15 K

    BALUJA Shipra

    2006-01-01

    From experimental data of density, viscosity and ultrasonic velocity, the various acoustical properties, such as specific impedance (Z), isentropic compressibility (κs), Rao's molar sound function (Rm), the van der Waals constant (b), molar compressibility (W), intermolecular free length (Lf), relaxation strength (r), internal pressure (π),free volume (Vf), solvation number (Sn) etc., were calculated for three Schiff bases in 1,4-dioxane and dimethylformamide (DMF) at 318.15 K. The results are interpreted in terms of molecular interactions occurring in the solutions.

  10. The first hyperpolarizability of p-nitroaniline in 1,4-dioxane: a quantum mechanical/molecular mechanics study.

    Jensen, Lasse; van Duijnen, Piet Th

    2005-08-15

    In this work we have investigated the first hyperpolarizability of pNA in 1,4-dioxane solution using a quantum mechanics/molecular mechanics (QM/MM) model. The particular model adopted is the recently developed discrete solvent reaction field (DRF) model. The DRF model is a polarizable QM/MM model in which the QM part is treated using time-dependent density-functional theory and local-field effects are incorporated. This allows for direct computation of molecular effective properties which can be compared with experimental results. The solvation shift for the first hyperpolarizability is calculated to be 30% which is in good agreement with the experimental results. However, the calculated values, both in the gas phase and in solution, are by a factor of 2 larger than the experimental ones. This is in contrast to the calculation of the first hyperpolarizability for several small molecules in the gas phase where fair agreement is found with experimental. The inclusion of local-field effects in the calculations was found to be crucial and neglecting them led to results which are significantly larger. To test the DRF model the refractive index of liquid 1,4-dioxane was also calculated and found to be in good agreement with experiment.

  11. Probabilistic analysis of risks to US drinking water intakes from 1,4-dioxane in domestic wastewater treatment plant effluents.

    Simonich, Staci Massey; Sun, Ping; Casteel, Ken; Dyer, Scott; Wernery, Dave; Garber, Kevin; Carr, Gregory; Federle, Thomas

    2013-10-01

    The risks of 1,4-dioxane (dioxane) concentrations in wastewater treatment plant (WWTP) effluents, receiving primarily domestic wastewater, to downstream drinking water intakes was estimated using distributions of measured dioxane concentrations in effluents from 40 WWTPs and surface water dilution factors of 1323 drinking water intakes across the United States. Effluent samples were spiked with a d8 -1,4-dioxane internal standard in the field immediately after sample collection. Dioxane was extracted with ENVI-CARB-Plus solid phase columns and analyzed by GC/MS/MS, with a limit of quantification of 0.30 μg/L. Measured dioxane concentrations in domestic wastewater effluents ranged from water intakes using the iSTREEM model at mean flow conditions, assuming no in-stream loss of dioxane. Dilution factors ranged from 2.6 to 48 113, with a mean of 875. The distributions of dilution factors and dioxane concentration in effluent were then combined using Monte Carlo analysis to estimate dioxane concentrations at drinking water intakes. This analysis showed the probability was negligible (p = 0.0031) that dioxane inputs from upstream WWTPs could result in intake concentrations exceeding the USEPA drinking water advisory concentration of 0.35 μg/L, before any treatment of the water for drinking use.

  12. Synthesis of Novel Homo-N-Nucleoside Analogs Composed of a Homo-1,4-Dioxane Sugar Analog and Substituted 1,3,5-Triazine Base Equivalents

    Qiang Yu

    2008-12-01

    Full Text Available Enantioselective syntheses from dimethyl tartrate of 1,3,5-triazine homo-N-nucleoside analogs, containing a 1,4-dioxane moiety replacing the sugar unit in natural nucleosides, were accomplished. The triazine heterocycle in the nucleoside analogs was further substituted with combinations of NH2, OH and Cl in the 2,4-triazine positions.

  13. Method 522 - Determination of 1,4-Dioxane in Drinking Water by Solid Phase Extraction (SPE) and Gas Chromatography Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM)

    1,4-Dioxane has been identified as a probable human carcinogen and an emerging contaminant in drinking water. The National Exposure Research Laboratory (NERL) has developed a method for the analysis of 1,4-dioxane in drinking water at ng/L concentrations. The method consists of...

  14. A Fenton-like degradation mechanism for 1,4-dioxane using zero-valent iron (Fe0) and UV light.

    Son, Hyun-Seok; Im, Jong-Kwon; Zoh, Kyung-Duk

    2009-03-01

    In this study, the degradation mechanism of 1,4-dioxane using zero-valent iron (Fe0) in the presence of UV light was investigated kinetically. The degradation of 1,4-dioxane in Fe0-only, photolysis, and combined Fe0 and UV reactions followed the kinetics of a pseudo-first-order model. The degradation rate constant (19 x 10(-4)min(-1)) in the combined reaction with UV-C (4.2 mW cm(-2)) and Fe0 (5 mg L(-1)) was significantly enhanced compared to Fe0-only (4.8 x 10(-4) min(-1)) and photolytic reactions (2.25 x 10(-4)min(-1)), respectively. The removal efficiency of 1,4-dioxane in combined reaction with Fe0 and UV within 4 h was enhanced by increasing UV intensity at UV-C region (34% at 4.2 mW cm(-2) and 89% at 16.9 mW cm(-2)) comparing with the removal in the combined reaction with Fe0 and UV-A (29% at 2.1 mW cm(-2), and 33% at 12.6 mW cm(-2)). It indicates that 1,4-dioxane was degraded mostly by OH radicals in the combined reaction. The degradation patterns in both Fe(0)-only and combined reactions were well fitted to the Langmuir-Hinshelwood model, implying that adsorption as well as the chemical reaction occurred. The transformation of Fe0 to Fe2+ and Fe3+ was observed in the Fe0-only and combined reactions, and the transformation rate of Fe0 was improved by UV irradiation. Furthermore, the reduction of Fe3+ was identified in the combined reaction, and the reduction rate was enhanced by an increase of UV energy. Our study demonstrated that the enhancement of 1,4-dioxane removal rate occurred via an increased supply of OH radicals from the Fenton-like reaction induced by the photolysis of Fe0 and H2O, and with producing less sludge.

  15. Volumetric Properties of the Mixture Trichloromethane CHCl3 + C4H8O2 1,4-Dioxane (VMSD1211, LB3413_V)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Trichloromethane CHCl3 + C4H8O2 1,4-Dioxane (VMSD1211, LB3413_V)' providing data from direct low-pressure dilatometric measurement of molar excess volume at variable mole fraction and constant temperature.

  16. Volumetric Properties of the Mixture Trichloromethane CHCl3 + C4H8O2 1,4-Dioxane (VMSD1212, LB3579_V)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Trichloromethane CHCl3 + C4H8O2 1,4-Dioxane (VMSD1212, LB3579_V)' providing data by calculation of molar excess volume from low-pressure density measurements at variable mole fraction and constant temperature.

  17. Speeds of Sound and Excess Molar Volume for Binary Mixture of 1,4-Dioxane with 1-Heptanol at Five Temperatures

    Anil Kumar Koneti

    2014-01-01

    Full Text Available Speed of sound and density data for dilute liquid solutions of cyclic ether 1,4-dioxane with 1-heptanol was obtained using the Anton-Paar DSA 5000 at five temperatures  T = (298.15, 303.15, 308.15, 313.15, and 318.15 K at atmospheric pressure. The excess parameters were calculated from experimental data and fitted with a Redlich-Kister polynomial function and concluded the presence of weak molecular interactions.

  18. Simultaneous correlation of the excess enthalpy and W-shaped excess heat capacity of 1,4-dioxane+n-alkane systems by PRSV-HVOS CEOS

    SLOBODAN P. SERBANOVIC

    2003-01-01

    Full Text Available In this work the Peng-Robinson-Stryjek-Vera (PRSV equation of state coupled with the Huron-Vidal-Orbey-Sandler (HVOS rule was tested for the correlation of the excess enthalpy (HE and the excess heat capacity (cpE alone and simultaneously. The HVOS mixing rule incorporates the NRTL equation as the GE model. All calculations were performed using the linear and reciprocal forms of the temperature dependent parameters of the models. For all the evaluations the 1,4-dioxane+n-alkane systems were chosen having in mind the unusually W-shaped concentration dependence of cpE for these systems. The correlation of the HE and cpE data alone for all the investigated systems using four coefficients and for the simultaneous correlation of HE+cpE data using six coefficients of the temperature dependent parameters of the PRSV-HVOS models could be considered as being very satisfactory.

  19. Spectrophotometric and conductometric study of the complexation of N-salicylidene-2-aminophenol with Cu2+ in methanol + 1,4-dioxane binary solutions

    Biswas Rashmidipta

    2014-01-01

    Full Text Available The complexation reaction between N-salicylidene-2-aminophenol, abbreviated as SAP, with Cu2+ ion was studied in binary mixtures of methanol and 1,4-dioxane by using conductometric and spectrophotometric method at different temperatures. The stability constants (Kf for the 1:1 complex, Cu2+-SAP, were calculated from computer fitting of absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM in different binary solvent mixtures. A non-linear behaviour was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (ΔH, ΔS and ΔG for the formation of Cu2+-SAP complex were determined from the temperature dependence of stability constants (Kf. The overall results showed that the complexation reaction is entropy driven and is affected by the nature and composition of the mixed solvents.

  20. Enzymatic synthesis and characterization of novel biodegradable copolymers of 5-benzyloxy-trimethylene carbonate with 1,4-dioxan-2-one.

    He, Feng; Jia, Hua-Li; Liu, Gang; Wang, Yan-Ping; Feng, Jun; Zhuo, Ren-Xi

    2006-08-01

    Enzymatic ring-opening copolymerization of 5-benzyloxy-trimethylene carbonate (BTMC) and 1,4-dioxan-2-one (DON) was investigated for the first time. Immobilized porcine pancreas lipase (IPPL) on silica particles was selected to perform the copolymerization. A series of novel biodegradable copolymers with different compositions were characterized by (1)H NMR, (13)C NMR, and GPC. The influences of reaction conditions such as polymerization time and catalyst concentration on the yield and molecular weight of the copolymers were also studied. The copolymerizations of different monomer feed ratios were carried out in bulk at 150 degrees C with 4.5 wt per thousand IPPL as a catalyst for 24 h. With the increase of the BTMC molar feed ratio from 20% to 79%, the M(n) of the resulting copolymers increased from 5600 to 63400. Water uptake and static contact angle experiments showed that the hydrophilicity of copolymers could be improved with increasing DON content in the copolymers. Moreover, the in vitro drug release rate (ibuprofen as the model drug) of the resulting copolymers also increased along with the DON content in the copolymers.

  1. Solvent inclusion in the crystal structure of bis-[(adamantan-1-yl)methanaminium chloride] 1,4-dioxane hemisolvate monohydrate explained using the computed crystal energy landscape.

    Mohamed, Sharmarke

    2016-09-01

    Repeated attempts to crystallize 1-adamantane-methyl-amine hydro-chloride as an anhydrate failed but the salt was successfully crystallized as a solvate (2C11H20N(+)·2Cl(-)·0.5C4H8O2·H2O), with water and 1,4-dioxane playing a structural role in the crystal and engaging in hydrogen-bonding inter-actions with the cation and anion. Computational crystal-structure prediction was used to rationalize the solvent-inclusion behaviour of this salt by computing the solvent-accessible voids in the predicted low-energy structures for the anhydrate: the global lattice-energy minimum structure, which has the same packing of the ions as the solvate, has solvent-accessible voids that account for 3.71% of the total unit-cell volume and is 6 kJ mol(-1) more stable than the next most stable predicted structure.

  2. Influence of temperature and organic solvents (isopropanol and 1,4-dioxane) on the micellization of cationic gemini surfactant (14-4-14).

    Das, Sibani; Naskar, Bappaditya; Ghosh, Soumen

    2014-04-28

    The micellar properties of gemini surfactant, tetramethylene-1,4-bis(dimethyltetradecylammonium bromide) (14-4-14) in binary aqueous mixtures of isopropanol (IP) and 1,4-dioxane (DO) were investigated by tensiometric, conductometric and microcalorimetric methods in the temperature range of 298 to 323 K. The values of both critical micelle concentration (cmc) and degree of dissociation increase with increasing temperature and concentration of cosolvent. The energetics of micellization was determined from the temperature dependence of critical micelle concentration values. The standard Gibbs free energy of micellization (ΔG) was found to be negative and the negative value decreases with both temperature and concentration of cosolvent. The Gibbs free energy of micellization (ΔG) is mainly controlled by tail transfer free energy. The enthalpy of micellization obtained from direct calorimetry, Gibbs-Helmholtz equation and van't Hoff methods are presented and compared. Entropic contribution is found to be larger than the enthalpy and for all the systems, an enthalpy-entropy compensation phenomenon was obtained. Some interfacial parameters, e.g., Gibbs surface excess (Γmax), minimum area per surfactant molecule (Amin), surface pressure (Πcmc) were been calculated. The fluorimetric technique was used to understand the microenvironment of the solution under the influence of cosolvent. The micellar aggregation number of 14-4-14 in a binary mixed solvent was also determined from fluorimetry using pyrene as a probe. Two fluorophores, fluorescein and curcumin delivered the information of the peripheral region of the micellar interface and palisade region. The self-diffusion coefficients of the micellar media were evaluated using the cyclic voltammetry (CV) method. Such multi-technique investigation provides a new look into the role of solvation in micellization.

  3. (Vapour + liquid) equilibrium of binary mixtures (1,3-dioxolane or 1,4-dioxane + 2-methyl-1-propanol or 2-methyl-2-propanol) at isobaric conditions[(Vapour+liquid) equilibrium; Cyclic ethers; Butanols; ASOG; UNIFAC

    Reyes, Antonio; Lafuente, Carlos; Minones, Jose; Kragl, Udo; Royo, Felix M. E-mail: femer@posta.unizar.es

    2004-02-01

    Isobaric (vapour + liquid) equilibrium of (1,3-dioxolane or 1,4-dioxane + 2-methyl-1-propanol or 2-methyl-2-propanol) at 40.0 kPa and 101.3 kPa has been studied with a dynamic recirculating still. The experimental VLE data are thermodynamically consistent. From these data, activity coefficients were calculated and correlated with the Margules, van Laar, Wilson, NRTL and UNIQUAC equations. The VLE results have been compared with the predictions by the UNIFAC and ASOG methods.

  4. Biodegradation of 1,4-Dioxane

    2007-08-01

    transferred to 950 mL QA/QC bottles with Teflon™-lined lids, and stored at 4 oC until used in microcosm set up. Site ground water from the two 1,4...P. Wackett and M. J. Sadowsky. 1997. Toluene 2-monooxygenase-dependent growth of Burkholderia cepacia G4-PR1 on diethyl ether. Appl. Environ...United States and elsewhere. Because of its miscibility in water , its low Henry’s Law constant (4.9 x 10-6 atm m3/mol), and low octanol/ water

  5. Determination of 1, 4-Dioxane Residues in Synthetic Detergents and Cosmetics by Headspace/Gas Chromatography-Tandem Mass Spectrometry%顶空/气相色谱-串联质谱法测定合成洗涤剂及化妆品中二(噁)烷残留

    崔进; 杨佳玲; 刘祥; 洪育春; 佟丽丽

    2012-01-01

    A headspace/gas chromatography - tandem mass spectrometric ( HS/GC -MS/MS) method was established for the determination of 1, 4-dioxane residues in synthetic detergents and cosmetics. The samples were mixed with water, then sodium chloride was added to produce the " salting -out" effect. After oscillation, 1, 4-dioxane in sample was dissolved completely. The sample mixed with water was oscillated for 30 min at 80℃ to get gas - liquid balance state and then the upper clear gas was prepared. The detection was carried out by GC - MS/MS under the multiple-reaction monitoring (MRM) mode. Good linearity in the concentration range of 0. 1 - 100 mg/L was obtained, with a correlation coefficient of 0. 999 8. The limit of detection ( LOD) was 0. 010 mg/kg and the limit of quantitation ( LOQ) was 0. 035 mg/kg. The average recoveries were in the range of 98% - 103% , with relative standard deviations( RSDs) of 0. 44% -2. 1% . The accuracy, reliability and sensitivity of the method made it suitable for the determination of 1, 4-dioxane in synthetic detergents and cosmetics.%建立了顶空/气相色谱-串联质谱(HS/GC-MS/MS)测定合成洗涤剂和化妆品中二(口恶)烷含量的分析方法.将样品与适量的水混溶,加入固体氯化钠产生“盐析”效应后再通过超声振荡,使样品中的二(口恶)烷充分溶解.此后将样品瓶于80℃混合摇振30 min达到气液平衡,顶空进样,在GC-MS/MS多反应监测模式(MRM)下测定,二(口恶)烷在质量浓度0.1~100 mg/L范围内呈良好线性,相关系数为0.9998,检出限(S/N=3)为0.010 mg/kg,定量下限(S/N=10)为0.035 mg/kg,平均加标回收率为98%~103%,相对标准偏差为0.44%~2.1%.该方法能有效消除复杂基质的干扰,结果准确可靠,灵敏度高,重现性好,适用于合成洗涤剂和化妆品中痕量二(口恶)烷的测定.

  6. The replacement of the 2-methoxy substituent of N-((6,6-diphenyl-1,4-dioxan-2-yl)methyl)-2-(2-methoxyphenoxy)ethan-1-amine improves the selectivity for 5-HT1A receptor over α1-adrenoceptor and D2-like receptor subtypes.

    Del Bello, Fabio; Bonifazi, Alessandro; Giannella, Mario; Giorgioni, Gianfabio; Piergentili, Alessandro; Petrelli, Riccardo; Cifani, Carlo; Micioni Di Bonaventura, Maria Vittoria; Keck, Thomas M; Mazzolari, Angelica; Vistoli, Giulio; Cilia, Antonio; Poggesi, Elena; Matucci, Rosanna; Quaglia, Wilma

    2017-01-05

    N-((6,6-diphenyl-1,4-dioxan-2-yl)methyl)-2-(2-methoxyphenoxy)ethan-1-amine (3) is a potent 5-HT1A receptor and α1d-adrenoceptor (α1d-AR) ligand. Analogues 5-10 were rationally designed and prepared to evaluate whether electronic and/or lipophilic properties of substituents in the ortho position of its phenoxy moiety exert any favorable effects on the affinity/activity at 5-HT1A receptor and improve selectivity over α1-ARs. To rationalize the experimental observations and derive information about receptor-ligand interactions of the reported ligands, docking studies, using 5-HT1A and α1d-AR models generated by homology techniques, and a retrospective computational study were performed. The results highlighted that proper substituents in position 2 of the phenoxy moiety of 3 selectively address the ligands toward 5-HT1A receptor with respect to α1-ARs and D2-like receptor subtypes. Methoxymethylenoxy derivative 9 showed the best 5-HT1A selectivity profile and the highest potency at 5-HT1A receptor, behaving as a partial agonist. Finally, 9, tested in light/dark exploration test in mice, significantly reduced anxiety-linked behaviors. Therefore, it may be considered a lead for the design of partial agonists potentially useful in the treatment of disorders in which 5-HT1A receptor is involved.

  7. ER-1422: Biodegradation of 1,4-Dioxane

    2007-08-01

    transferred to 950 mL QA/QC bottles with Teflon™-lined lids, and stored at 4 oC until used in microcosm set up. Site ground water from the two 1,4...2-monooxygenase-dependent growth of Burkholderia cepacia G4-PR1 on diethyl ether. Appl. Environ. Microbiol. 63:1606-1609. 6. Janssen, D. B., J...United States and elsewhere. Because of its miscibility in water , its low Henry’s Law constant (4.9 x 10-6 atm m3/mol), and low octanol/ water

  8. Studies on Metabolism of 1,4-Dioxane

    2010-03-01

    Porapak™ is a registered trademark of Waters Corporation; Aroclor® Monsanto Chemical Company.) (4) In direct contradiction to the position taken...the molar mass of the lactone. C-5 Toxicology Report No. 87-XE-08WR-09, Oct 07-Mar 10 In identifying HEM as the primary metabolite of dioxane, Braun

  9. Oligonucleotides with 1,4-dioxane-based nucleotide monomers

    Madsen, Andreas S; Wengel, Jesper

    2012-01-01

    An epimeric mixture of H-phosphonates 5R and 5S has been synthesized in three steps from known secouridine 1. Separation of the epimers has been accomplished by RP-HPLC, allowing full characterization and incorporation of monomers X and Y into 9-mer oligonucleotides using H-phosphonates building ...

  10. Oxygenase-Catalyzed Biodegradation of Emerging Water Contaminants: 1,4-Dioxane and N-Nitrosodimethylamine

    2012-02-01

    Technologies 6410 tandem triple quadrupole (QQQ) mass spectrometer (Santa Clara, CA). The LC solvents used were Solvent A: aqueous buffer and Solvent B...molecular techniques by knocking out or heterologously expressing putative monooxygenase genes. The effect of the common co-contaminants 1,1,1-TCA and 1,1...monooxygenases was also verified with molecular techniques by knocking out or heterologously expressing putative monooxygenase genes. The effect of the

  11. Acute Inhalation Toxicity Study of 1, 4-Dioxane in Rats (Rattus norvegicus)

    2012-07-01

    of degenerative and/or toxic nephropathy . Degenerative nephropathy is not uncommon in rats and is due to the predisposing factors of age, sex...was attributed to early and more acute progression of chronic progressive glomerular nephropathy . 4.2.6 Statistical Analysis: A statistical...0.6084 Degeneration 1 day M - - - - - - - F 0.0011 - - 0.0256 - 0.0256 0.0256 2 wk M - - - - - - - F - - - - - - - Kidney Nephropathy

  12. Solubility and phase separation of benzocaine and salicylic acid in 1,4-dioxane-water mixtures at several temperatures.

    Peña, M Angeles; Bustamante, Pilar; Escalera, Begoña; Reíllo, Aurora; Bosque-Sendra, Juan Manuel

    2004-11-15

    The solubilities of benzocaine and salicylic acid were determined in water-dioxane mixtures at several temperatures (5-40 degrees C for benzocaine and 10-40 degrees C for salicylic acid). The solubility curves as a function of dioxane ratio showed a maximum at 90% dioxane at all temperatures. Above 25 degrees C, the homogeneous mixture splits into two liquid immiscible phases. For benzocaine, the initial dioxane concentration range at which phase separation takes place increased with temperature (50-60% at 25 degrees C, 50-70% at 30-35 degrees C and 40-70% at 40 degrees C). For salicylic acid, the dioxane concentration required for phase separation (40-60% dioxane) did not change with temperature. Phase separation was not related to solid phase changes (polymorphism or solvates). The phase composition and drug extraction at the drug-rich phase were determined. The apparent enthalpies of the solution process were a nonlinear function of the dioxane ratio for both drugs. The apparent enthalpy of solution of benzocaine was larger than that expected at the upper limit of phase separation (70% dioxane), whereas for salicylic acid the apparent enthalpy of solution decreased abruptly at the region corresponding to phase separation (40-70% dioxane). Both drugs showed a nonlinear pattern of enthalpy-entropy compensation.

  13. COPOLYMERIZATION AND DETERMINATION OF MONOMER REACTIVITY RATIOS OF DL-LACTIDE WITH 3-BENZYLOXYMETHYL-1,4-DIOXANE-2,5-DIONE

    Ji-yuan Yang; Jian Yu; Mei Li; Zhong-wei Gu; Xin-de Feng

    2002-01-01

    The copolymerization of DL-LA and 3-BMG was carried out in bulk with stannous 2-ethylhexanoate as the catalyst. A series of copolymers with pendant protected groups were obtained and characterized by 1H-NMR and GPC to be rBMG = 1.96 and rLA = 0.37, respectively.

  14. Developing and Validating Genetic Catabolic Probes for Monitored Natural Attenuation of 1,4-Dioxane with a One-Year Timeframe

    2014-04-01

    concentrations were determined by Nanodrop ND-1000 from Nanodrop products Inc. (Wilmington, NE). cDNA was synthesized using High-Capacity cDNA Reverse...ACG CCT ATT - (ZEN) - ACA TCC AGC AGC TCG A - (IABkFQ) -3’. The amplicons were approximately 115 bp in length. All primers and probes were synthesized ...MC09 − + - - - Escherichia coli K12 − + - - - Bacteriophage λ − − amo Ammonia MO - Nitrosomonas europaea Winogradsky − + tod Toluene DO

  15. Solvothermal synthesis of strontium phosphate chloride nanowire

    Lam, W. M.; Wong, C. T.; Li, Z. Y.; Luk, K. D. K.; Chan, W. K.; Yang, C.; Chiu, K. Y.; Xu, B.; Lu, W. W.

    2007-08-01

    Strontium phosphate chloride nanowire was synthesized via a solvothermal treatment of strontium tri-polyphosphate and Collin salt in 1,4-dioxane at 150 °C. The effects of 1,4-dioxane concentration on particle morphology, crystallinity and phase purity were investigated in this study. The specimen morphology was analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). When the concentration of 1,4-dioxane was below 10%, micron-sized whisker was the dominant form. At 20-25% concentration of 1,4-dioxane, strontium phosphate chloride single-crystalline nanowire was 31±12 nm in diameter and 1.43±0.6 μm in length with an aspect ratio of 52.28±29.41. X-ray diffraction (XRD) pattern of this nanowire matched with that of strontium phosphate chloride (JCPDS #083-0973). When 1,4-dioxane concentration exceeded 25%, nanorod aggregate was the dominant form instead of nanowire. At 20-25% 1,4-dioxane concentration suitable strontium concentration combine with high chemical potential environment favors the formation of nanowires. By adding 1,4-dioxane impure phase such as β-strontium hydrogen phosphate, nanorod formation was suppressed. This method provides an efficient way to synthesize high aspect ratio strontium phosphate chloride nanowire. It has potential bioactive nanocomposite, high mechanical performance bioactive bone cement filler and fluorescent material applications.

  16. Used Solvent Testing and Reclamation. Volume 2. Vapor Degreasing and Precision Cleaning Solvents

    1988-12-01

    Dependence of the 1,3-Dioxolane/AlCI 3 Reaction Using Arrhenius’ Law 88 36 Effect of 1,4-Dioxane on Reactor Pressure 91 67 Effect of 1,4-Dioxane on HCI...and spent solvent. This process was performed for all of the three solvents. Inhibitor Kinetic Studies Batch Reactions. Batch reactor kinetic studies...acceptor in chlorinated solvents. It is an 4 80. Levenspiel , Chemical Reaction Engineering, 2nd ed. (John Wiley and Sons, 1972), pp 41-86. 490

  17. Cellulose decomposition behavior in hot-compressed aprotic solvents

    BAO GuiRong; Shiro SAKA; WANG Hua

    2008-01-01

    Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390℃. The corresponding densities of the solvent are 0.25-1.26 g/cm3 and 0.21-1.03 g/cm3 for sulfolane and 1,4-dioxane, respectively. As a result, in both solvents, more than 90% of cellulose is found to be de-composed to the solvent-soluble portion in which levoglucosan is the main component with the high-est yield of about 35% on original cellulose basis. The decomposition rate to levoglucosan is, however, faster in sulfolane than in 1,4-dioxane, while levoglucosan is more stable in 1,4-dioxane. In addition, its yield is found to be solvent-density dependent to be highest around 0.4-0.5 g/cm3 for both solvents. To elucidate these decomposition behaviors, the results obtained in this study with aprotic solvents are compared with protic solvents such as water and methanol in previous works.

  18. Effect of the Solvent on the Microstructure of Bi2Te3 Obtained Solvothermal Microwave-assisted Synthesis

    R.A. Lyubushkin

    2014-04-01

    Full Text Available In the present work, nanoparticles and nanowires have been prepared by solvothermal microwave-assisted synthesis using isopropyl alcohol, dimethylformamide (DMF and 1,4-dioxane respectively as the solvents. The microstructures of the synthesized powders have been characterized and the relationship with the solvent has been investigated.

  19. Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids

    Stuhr-Hansen, Nicolai; Padrah, Shahrokh; Strømgaard, Kristian

    2014-01-01

    An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order...

  20. Non-steady-state living polymerization: a new route to control cationic ring-opening polymerization (CROP) of oxetane via an activation chain end (ACE) mechanism at ambient temperature.

    Bouchékif, Hassen; Philbin, Marcia I; Colclough, Eamon; Amass, Allan J

    2005-08-14

    Well-defined polyoxetane with low polydispersivity has been synthesized via a novel living polymerisation process using 3-phenoxypropyl 1,4-dioxanium hexafluoroantimonate (3-PPD) as a model of a living "monomeric polyoxetane" initiator, in 1,4-dioxane at 35 degrees C.

  1. Cellulose decomposition behavior in hot-compressed aprotic solvents

    Shiro; SAKA

    2008-01-01

    Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents,sulfolane and 1,4-dioxane,using a batch-type reaction system with a molten tin bath in a range from 290 to 390℃. The corresponding densities of the solvent are 0.25-1.26 g/cm3 and 0.21-1.03 g/cm3 for sulfolane and 1,4-dioxane,respectively. As a result,in both solvents,more than 90% of cellulose is found to be de-composed to the solvent-soluble portion in which levoglucosan is the main component with the high-est yield of about 35% on original cellulose basis. The decomposition rate to levoglucosan is,however,faster in sulfolane than in 1,4-dioxane,while levoglucosan is more stable in 1,4-dioxane. In addition,its yield is found to be solvent-density dependent to be highest around 0.4-0.5 g/cm3 for both solvents. To elucidate these decomposition behaviors,the results obtained in this study with aprotic solvents are compared with protic solvents such as water and methanol in previous works.

  2. Water-Promoted Kinetic Separation of trans- and cis-Limonene Oxides

    徐招兵; 渠瑾

    2012-01-01

    The efficient hydrolytic kinetic separation of trans/cis-(R)-(+)-limonene oxides was realized in a 1 : 1 mixed solvent of water and 1,4-dioxane without additional catalyst. Optically pure trans-(R)-(+)-limonene oxide was recovered in high yield (77%).

  3. 21 CFR 74.3206 - D&C Green No. 6.

    2010-04-01

    ... coloring poly(glycolic acid-co-trimethylene carbonate) sutures (also referred to as 1,4-dioxan-2,5-dione... suture material for coloring polyglycolic acid surgical sutures with diameter greater than U.S.P. size 8... material for coloring polyglycolic acid surgical sutures with diameter not greater than U.S.P. size...

  4. Solid–liquid equilibria for binary and ternary systems with the Cubic-Plus-Association (CPA) equation of state

    Fettouhi, André; Thomsen, Kaj

    2010-01-01

    A systematic investigation of the CPA model's performance within solid-liquid equilibria (SLE) in binary mixtures (methane + ethane, methane + heptane, methane + benzene, methane + CO2, ethane + heptane, ethane + CO2, 1-propanol + 1,4-dioxane, ethanol + water, 2-propanol + water) is presented...

  5. Hydrolysis of 4-Acetoxystyrene Polymers Prepared by Atom Transfer Radical Polymerization

    Chen, Xianyi; Jankova, Katja; Kops, Jørgen

    1999-01-01

    Hydrolysis of 4-acetoxystyrene polymers prepared by atom transfer radical polymerization was carried out under various reaction conditions. It was found that hydrazinolysis of 4-acetoxystyrene homopolymers, random and block copolymers with styrene in 1,4-dioxane, afforded the corresponding narrow...

  6. ANALYSIS OF THE KINETICS OF SOLVOLYSIS OF P-NITROPHENYLSULFONYLMETHYL PERCHLORATE IN BINARY ALCOHOLIC MIXTURES IN TERMS OF THE THERMODYNAMIC PROPERTIES OF THE SOLVENT MIXTURES

    WIJNEN, JW; ENGBERTS, JBFN; BLANDAMER, MJ

    1993-01-01

    Rate constants are reported for the solvolysis of p-nitrophenylsulfonylmethyl perchlorate in binary ethanolic and methanolic mixtures at 298.2 K. Co-solvents include hydrocarbons, chlorinated hydrocarbons and 1,4-dioxane. The kinetic data are examined in terms of the effect of decreasing mole fracti

  7. Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

    Dorin, Rachel Mika

    2012-05-15

    Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

  8. Regulation gel formation, hierarchical structures and surface wettability via isomeride effect in supramolecular organogel system.

    Cao, Xinhua; Ding, Qianqian; Gao, Aiping; Lv, Haiting; Zhao, Na; Liu, Dan

    2017-05-15

    A new serial of gelators with two cholesteryl groups based on o-phenylenediamine, m-phenylenediamine and p-phenylenediamine were synthesized, and their organogelation ability was evaluated. We found that G-o could form gels in DMF, DMSO and ethyl acetate, G-m and G-p could only gel DMF and 1,4-dioxane. The organogels were thoroughly characterized using various microscopic techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Vis spectrum, FT-IR spectrum and contact angle. The gelation ability, morphology, self-assembly mode and materials surface wettability all could be tuned via isomeride effect in self-assembly system. Interestingly, superhydrophobic surface was formed via the self-assembly of compound G-p in 1,4-dioxane and exhibited very high adsorption capacity for water. This gel system provided new method for modulation self-assembly process in supramolecular field.

  9. Electron-ion dissociative recombination rate constants relevant to the Titan atmosphere and the Interstellar Medium

    Osborne, David; Lawson, Patrick; Adams, Nigel, E-mail: ngadams@uga.edu [University of Georgia, Department of Chemistry, 101 Cedar St., Athens, Georgia 30602 (United States)

    2014-01-21

    Following the arrival of Cassini at Titan in 2004, the Titan atmosphere has been shown to contain large complex polycyclic-aromatic hydrocarbons. Since Cassini has provided a great deal of data, there exists a need for kinetic rate data to help with modeling this atmosphere. One type of kinetic data needed is electron-ion dissociative recombination (e-IDR) rate constants. These data are not readily available for larger compounds, such as naphthalene, or oxygen containing compounds, such as 1,4 dioxane or furan. Here, the rate constants for naphthalene, 1,4 dioxane, and furan have been measured and their temperature dependencies are determined when possible, using the University of Georgia's Variable Temperature Flowing Afterglow. The rate constants are compared with those previously published for other compounds; these show trends which illustrate the effects which multi-rings and oxygen heteroatoms substitutions have upon e-IDR rate constants.

  10. Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination

    Almon Fisher

    2010-03-01

    Full Text Available We report on the development of a microelectromechanical systems (MEMS-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm-1 to 1240 cm-1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infrared spectra for acetic acid, acetone, 1,4-dioxane, and vinyl acetate was observed. Partial least-squares (PLS regression was used to develop an algorithm for classification of these compounds based solely on photoacoustic spectra.

  11. Terahertz Metamaterial Sensor Based on Electromagnetically Induced Transparency Effect

    Shao-Xian Li; Hong-Wei Zhao; Jia-Guang Han

    2015-01-01

    A terahertz metamaterial sensor adopting the metamaterial-based electromagnetically induced transparency (EIT) effect is presented for determining the 1,4-dioxane concentration in its aqueous solution. The metamaterial sensor, which consists of an EIT element unit with a cut-wire metallic resonator and two split-ring metallic resonators fabricated on a 490-µm thick silicon substrate, operates in a transmission geometry. The EIT peak was red-shifted and decreased with the increase of the water volume. A maximum red- shift about 54GHz of the EIT peak was detected between the 1,4-dioxane and water. The presented linear behavior and high sensitivity of the EIT peak depending on the water concentration pave a novel avenue for sensor applications.

  12. Low-Absorption Liquid Crystals for Infrared Beam Steering

    2013-10-22

    stirbar was dissolved 4-bromo-3- chloroiodobenzene (3.17 g, 10.0 mmol) in a mixture of 16 ml HiO and 40 ml 1,4-dioxane to give a colorless solution...The reaction was quenched with 40 ml HiO and the mixture was extracted with ether 100 ml twice. The organic portion was dried with MgSC>4, condensed

  13. Effect of hydrostatic pressure, temperature, and solvent on the rate of the Diels-Alder reaction between 9,10-anthracenedimethanol and maleic anhydride

    Kiselev, V. D.; Kornilov, D. A.; Anikin, O. V.; Latypova, L. I.; Konovalov, A. I.

    2017-03-01

    The rate of the reaction between 9,10-anthracenedimethanol and maleic anhydride in 1,4-dioxane, acetonitrile, trichloromethane, and toluene is studied at 25, 35, 45°C in the pressure range of 1-1772 bar. The rate constants, enthalpies, entropies and activation volumes are determined. It is shown that the rate of reaction with 9,10-anthracenedimethanol is approximately one order of magnitude higher than with 9-anthracenemethanol.

  14. Duloxetine hydrochloride

    Mohan Bhadbhade

    2009-09-01

    Full Text Available The title compound [systematic name: N-methyl-3-(1-naphthyloxy-3-(2-thienylpropan-1-aminium chloride], C18H20NOS+·Cl−, was crystallized from 1,4-dioxane. Twofold rotational disorder exhibited by the thiophene ring in a 0.580 (5:0.420 (5 ratio represents two different conformations of the molecule that exist in the same crystal form. The crystal structure contains strong N—H...Cl hydrogen bonds.

  15. Surface study of mixtures containing cyclic ethers and isomeric chlorobutanes

    Royo, F.M. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza (Spain); Villares, A. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza (Spain); Martin, S. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza (Spain); Giner, B. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza (Spain); Lafuente, C. [Departamento de Quimica Organica-Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza (Spain)]. E-mail: celadi@unizar.es

    2007-05-15

    Experimental surface tensions and the corresponding surface tensions deviations for the mixtures containing 1,3-dioxolane or 1,4-dioxane and 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane or 2-chloro-2-methylpropane, measured with a drop volume tensiometer, are reported at the temperatures of 298.15 K and 313.15 K. The excess surface concentrations of isomeric chlorobutanes are also evaluated using a monolayer model.

  16. Dielectric relaxation and hydrogen bonding studies of 1,3-propanediol–dioxane mixtures using time domain reflectometry technique

    Madhukar N Shinde; Ravindra B Talware; Pravin G Hudge; Yogesh S Joshi; Ashok C Kumbharkhane

    2012-02-01

    The complex permittivity, static dielectric constant and relaxation time for 1,3-propanediol, 1,4-dioxane and their mixtures have been studied using time domain reflectometry (TDR). The excess permittivity, excess inverse relaxation time and Kirkwood correlation factor have also been determined at various concentrations of dioxane. Hydrogen bonded theory was applied to compute the correlation terms for the mixtures. The Bruggeman model for the nonlinear case has been fitted to the dielectric data for mixtures.

  17. 77 FR 74192 - Availability of Final Toxicological Profiles

    2012-12-13

    ... . Toxicological profile CAS No. 1. Acrylamide 79-06-1 2. 1,3-Butadiene 106-99-0 3. Cadmium 7440-43-9 4. Carbon Monoxide 630-08-0 5. Chromium 7440-47-3 6. 1,4-Dioxane 123-91-1 7. Manganese 7439-96-5 8. Phosphate Ester... substances'' under CERCLA Section 104(i)(1)(B), to respond to requests for consultation under section...

  18. Surface tension isotherms of the dioxane-acetone-water and glycerol-ethanol-water ternary systems

    Dzhambulatov, R. S.; Dadashev, R. Kh.; Elimkhanov, D. Z.; Dadashev, I. N.

    2016-10-01

    The results of the experimental and theoretical studies of the concentration dependence of surface tension of aqueous solutions of the 1,4-dioxane-acetone-water and glycerol-ethanol-water ternary systems were given. The studies were performed by the hanging-drop method on a DSA100 tensiometer. The maximum error of surface tension was 1%. The theoretical models for calculating the surface tension of the ternary systems of organic solutions were analyzed.

  19. Applicability of an electrochemical Fenton-type process to actual wastewater treatment.

    Kishimoto, Naoyuki; Kitamura, Takuya; Nakamura, Yu

    2015-01-01

    The applicability of an electrochemical Fenton-type process (EF-HOCl-ReFe) to the treatment of three actual wastewaters, namely wastewater from an automobile factory (automobile wastewater), metal scrap-cleansing wastewater, and municipal wastewater, is discussed in this research. The EF-HOCl-ReFe successfully removed the chemical oxygen demand (COD) from automobile wastewater pre-treated by a coagulation process without any inhibition. The apparent current efficiency reached 86%, 46% of which was ascribed to the electrochemical Fenton-type mechanism. The metal scrap-cleansing wastewater had a yellow colour and high concentrations of COD (6550 mg/L) and Cl(-) (1560 mM). The EF-HOCl-ReFe could achieve almost complete COD removal and decolourization after 48 h of treatment, although a temporary intensification of colour was observed before the decolourization. The EF-HOCl-ReFe was also effective in the removal of 1,4-dioxane from municipal wastewater pre-treated by activated sludge and coagulation processes, which were unable to remove 1,4-dioxane. The 1,4-dioxane removal efficiency after 30 min of treatment reached 68.5%. Thus, the EF-HOCl-ReFe was applicable to the treatment of these actual wastewaters.

  20. Proposing nanofiltration as acceptable barrier for organic contaminants in water reuse

    Yangali-Quintanilla, Victor

    2010-10-01

    For water reuse applications, " tight" nanofiltration (NF) membranes (of polyamide) as an alternative to reverse osmosis (RO) can be an effective barrier against pharmaceuticals, pesticides, endocrine disruptors and other organic contaminants. The use of RO in existing water reuse facilities is addressed and questioned, taking into consideration that tight NF can be a more cost-effective and efficient technology to target the problem of organic contaminants. It was concluded that tight NF is an acceptable barrier for organic contaminants because its removal performance approaches that of RO, and because of reduced operation and maintenance (O&M) costs in long-term project implementation. Average removal of neutral compounds (including 1,4-dioxane) was about 82% and 85% for NF and RO, respectively, and average removal of ionic compounds was about 97% and 99% for NF and RO, respectively. In addition, " loose" NF after aquifer recharge and recovery (ARR) can be an effective barrier against micropollutants with removals over 90%. When there is the presence of difficult to remove organic contaminants such as NDMA and 1,4-dioxane; for 1,4-dioxane, source control or implementation of treatment processes in wastewater treatment plants will be an option; for NDMA, a good strategy is to limit its formation during wastewater treatment, but there is evidence that biodegradation of NDMA can be achieved during ARR. © 2010 Elsevier B.V.

  1. Strong impact of the solvent on the photokinetics of a 2(1H)-pyrimidinone.

    Ryseck, G; Villnow, T; Hugenbruch, S; Schaper, K; Gilch, P

    2013-08-01

    Pyrimidinones are part of the (6-4) photolesions which may be formed from two pyrimidine bases adjacent on a DNA strand. In relation to the secondary photochemistry of the (6-4) lesion, i.e. its transformation into a Dewar valence isomer, photophysical and photochemical properties of 1-methyl-2(1H)-pyrimidinone (1MP) in water, acetonitrile, methanol, and 1,4-dioxane are reported here. As deduced from steady state fluorescence and femtosecond transient absorption spectroscopy the S1 lifetime of 1MP is strongly affected by the solvent. The lifetimes range from 400 ps for water to 40 ps for 1,4-dioxane. Internal conversion (IC) and intersystem crossing (ISC) contribute to the S1 decay. The solvent effect on the IC rate constant is more pronounced than on the ISC constant. The quantum yields for the consumption of 1MP (values for nitrogen purged solvents) are large for methanol (0.35) and 1,4-dioxane (0.24) and small for acetonitrile (0.02) and water (0.003). Hydrogen abstraction from the solvent by the triplet state of 1MP may rationalize this.

  2. Equivalent circuit model analysis on electrochemical impedance spectroscopy of lithium metal batteries

    Gao, Peng; Zhang, Cuifen; Wen, Guangwu

    2015-10-01

    Lithium metal electrode is pretreated with 1,3-dioxolane or 1,4-dioxane to improve its properties. The components and morphology of the surface films formed in the above two pretreatment liquids are studied using FTIR and SEM respectively. Li-LiCoO2 coin cells are then fabricated and their cycle and discharge performance are tested. It is found that the battery performance is greatly improved by such pretreatment. Interestingly, the 1,4-dioxane pretreatment is more effective than 1,3-dioxolane in improving the lithium metal electrode performance. To explore the mechanism(s) behind, the electrochemical impedance spectroscopy (EIS) is employed and an equivalent circuit model is designed for EIS analysis. The fitting curves are aligned well with the experimental curves, suggesting that the proposed equivalent circuit model is an ideal model for lithium battery. Next, the corresponding relationship between the impedance components and every individual semicircle in the Nyquist curves is inferred theoretically and the result is satisfying. Based on the analysis using this model, we conclude that the structural stability of SEI film is increased and the interfacial compatibility between the lithium substrate and the SEI film is improved by 1,3-dioxolane or 1,4-dioxane pretreatment.

  3. An Investigation of the Behavior of Solvent based Polycaprolactone ink for Material Jetting.

    He, Yinfeng; Wildman, Ricky D; Tuck, Chris J; Christie, Steven D R; Edmondson, Steven

    2016-02-12

    An initial study of processing bioresorbable polycaprolactone (PCL) through material jetting was conducted using a Fujifilm Dimatix DMP-2830 material printer. The aim of this work was to investigate a potential solvent based method of jetting polycaprolactone. Several solvents were used to prepare a PCL solvent based ink and 1, 4-dioxane was chosen with the consideration of both solubility and safety. The morphology of PCL formed under different substrate temperatures, droplet spacings were investigated. Multi-layer PCL structures were printed and characterized. This work shows that biodegradable polycaprolactone can be processed through material jetting.

  4. SERDP and ESTCP Workshop on Long Term Management of Contaminated Groundwater Sites

    2013-11-01

    field scale approaches are lacking Processes being evaluated: - Chemical oxidation - Electrochemical treatment - Catalytic - Bioremediation (AFCEC BAA...DiChristina (Georgia Tech) ER-2306 In Situ Bioremediation of 1,4-Dioxane by Methane Oxidizing Bacteria In Coupled Anaerobic-Aerobic Zones Charles Schaefer...Effective Methods for Amendment Delivery (Critical) ............................ 27  6.1.2  Promote Use of CSIA to Determine Degradation  Mechanisms  and Track

  5. The effect of solvent on the kinetics of the oxidation of 3-methyl-2,6-diphenyl-piperidin-4-one by quinolinium fluorochromate in aqueous organic media

    KUPPANAGOUNDER P. ELANGO

    2001-06-01

    Full Text Available The kinetics of the oxidation of 3-methyl-2,6-diphenyl-piperidin-4-one by quinolinium fluorochromate (QFC have been investigated in aqueous solutions of dimethyl sulphoxide, 1,4-dioxane, tert-butanol and acetone. The influence of the added co-solvent on the reactivity were analysed in the light of various simple and multiple regression equations, viz the Laidler-Eyring, Grunwald-Winstein, Swain and Kamlet-Taft equations. The obtained results showed that the solvation phenomenon plays a dominant role on the reactivity.

  6. CuI/Proline-catalyzed N-Arylation of Nitrogen Heterocycles

    2006-01-01

    Ma's CuI/proline procedure for the catalytic cross coupling between nitrogen heterocycles and aryl halides was markedly improved. The key finding was that K3PO4 was a much better base than K2CO3 for the reaction. With this new reaction condition the cross coupling with aryl iodides could be accomplished in 1,4-dioxane instead of DMSO. This reactin also could be carried out in DMF. Furthermore, the coupling yields under the new conditions are usually higher than in Ma's original methods.

  7. Synthesis and biological activity of some heterocyclic compounds containing quinoxaline and coumarin moieties

    M. E. ABD EL-FATTAH

    2000-02-01

    Full Text Available 2,3-Dichloroquinoxaline (2 condensed with 7,8-dihydroxy-4-methylcoumarin to give the 1,4-dioxane derivative 4. 2.3-Dichloroquinoxaline (2 reacted with 4-hydroxycoumarin, 7-hydroxy-4-methylcoumarin and acyl hydrazide 13 to give either the 2,3-(dicoumarin-4-yloxyquinoxaline (6 or the 2,3-di-(4-methylcoumarin-7-yloxyquinoxaline (7 or the 2-chloro-3-(coumarin-4-yloxyquinoxaline (8 or the 2-chloro-3-(4-methylcoumarin-7-yloxy quinoxaline (9 or the ditriazoloquinoxaline 14 or the oxa-diazinoquinoxaline 16, depending on the relative ratios of the reactants and the reaction conditions.

  8. Recent progress in electron scattering from atoms and molecules

    Brunger, M. J. [Centre for Antimatter-Matter Studies, CAPS, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia and Institute of Mathematical Sciences, University of Malaya, Kuala Lumpur (Malaysia); Buckman, S. J. [Institute of Mathematical Sciences, University of Malaya, Kuala Lumpur, Malaysia and Centre for Antimatter-Matter Studies, AMPL, Australian National University, Canberra, ACT 0200 (Australia); Sullivan, J. P.; Palihawadana, P. [Centre for Antimatter-Matter Studies, AMPL, Australian National University, Canberra, ACT 0200 (Australia); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Chiari, L.; Pettifer, Z. [Centre for Antimatter-Matter Studies, CAPS, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Silva, G. B. da [Centre for Antimatter-Matter Studies, CAPS, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia and Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Lopes, M. C. A. [Centre for Antimatter-Matter Studies, CAPS, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia and Departamento de Fisica, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Duque, H. V. [Departamento de Fisica, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Masin, Z.; Gorfinkiel, J. D. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); Garcia, G. [Instituto de Fisica Fundamental, CSIC, Madrid E-28006 (Spain); Hoshino, M.; Tanaka, H. [Department of Physics, Sophia University, Tokyo, 102-8554 (Japan); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2014-03-05

    We present and discuss recent results, both experimental and theoretical (where possible), for electron impact excitation of the 3s[3/2 ]{sub 1} and 3s′[1/2 ]{sub 1} electronic states in neon, elastic electron scattering from the structurally similar molecules benzene, pyrazine, and 1,4-dioxane and excitation of the electronic states of the important bio-molecule analogue α-tetrahydrofurfuryl alcohol. While comparison between theoretical and experimental results suggests that benchmarked cross sections for electron scattering from atoms is feasible in the near-term, significant further theoretical development for electron-molecule collisions, particularly in respect to discrete excitation processes, is still required.

  9. UV Curable Epoxy-Based Second Order Nonlinear Optical Materials; Synthesis and Characterization

    1992-05-14

    Ether of Bisphenol A and 4(4’-nitrophenylazo) phenylamine (Disperse Orange 3)( DGEBA -DO3C) is described in reference 10. The chemical structure of the...C-CH=CH ; R’ -a N= NO2 Figure 2. The structure of DGEBA -DO3C DGEBA -DO3C was dissolved in propylene glycol methyl ether acetate and 1,4 dioxane (volume...polymers Ts(°C) Td(OC)a epoxy prepolymer 105 237 DGEBA -DO3Cb 115 278 (76.5% functionalization of hydroxyl groups

  10. Desenvolvimento de um método de MEFS com CG-DIC para determinação de 1,4 dioxana em amostras de cosméticos

    Silva Fernando C.

    2001-01-01

    Full Text Available A headspace solid-phase microextraction (HS-SPME for the determination of 1,4 dioxane in cosmetics by gas chromatography is described. A manual SPME holder with 85 µm polyacrylate coating is utilized. The method is determined to have good resolution, satisfactory linerity (correlation coefficient r=0.997 for 0.20-10.00 mg Kg-1 range, a relative standard deviation of 6.3% and a detection limit of 5.00 µg Kg-1. Some cosmectic products were analyzed.

  11. Effect of organic solvents on peroxidases from rice and horseradish: prospects for enzyme based applications.

    Singh, Priyanka; Prakash, Rajiv; Shah, Kavita

    2012-08-15

    A feasibility test for rice peroxidase (RP) enzyme as a substitute for horseradish peroxidase (HRP) was carried out. The activity of HRP was maximum at 30 °C with pH 6.0-7.0. The purified rice peroxidase showed optimum activity at 30 °C with pH 7-8 and was thermostable till 68 °C, which is higher than the temperature reported for HRP. RP obeyed Michaelis-Menten kinetics. With increasing substrate concentrations, RP and HRP had V(max) as 8.23 μM min(-1) and 4.21 μM min(-1) and K(m) as 5.585 and 3.662 mM, respectively. In 10% 1,4-dioxane and ethanol, RP exhibited 2 and 1.3 times higher activity, respectively than HRP. Shelf life studies show RP to be significantly stable till 60 h in 20% 1,4-dioxane and till 12 h in ethanol. The activity of RP/HRP increased gradually with 0%-40% ethanol or 0%-30% 1,4-dioxane till 20 h with a sharp decline thereafter. The stability of HRP and RP reduced with increasing storage period. Enzyme efficiencies compared as V(m)/K(m) showed water miscible organic solvents, viz.1,4-dioxane and ethanol, to exhibit a regular decrease in V(m)/K(m) with increase in organic solvent concentration whereas, a reverse trend was observed with water-immiscible solvent like chloroform. The relative activity of RP and HRP enzymes upon immobilization on poly-5-carboxy-indole shows increasing enzyme activity with time and with guaiacol/dopamine hydrochloride as substrates. Immobilized RP had a better relative activity with dopamine as substrate than immobilized HRP, whereas with guaiacol both RP and HRP had a comparable activity upon immobilization. Results suggest rice peroxidase to be a cheaper and convenient enzyme system for immobilization using organic solvents. The high thermal stability, more stability in organic solvents and longer shelf life of RP over the immobilizing matrix suggest conducting polyindole having carboxyl functional groups to be a suitable matrix for the covalent entrapment of rice peroxidase through amide linkage. Good

  12. SYNTHESIS OF NOVEL HYDROPHILIC BIODEGRADABLE POLYESTER WITH FUNCTIONALIZED SIDE CHAIN GROUPS

    Ji-yuan Yang; Jian Yu; Huai-zhong Pan; Zhong-wei Gu; Wei-xiao Caoa; Xin-de Feng

    2001-01-01

    A substituted glycolide, 3-benzyloxymethyl-1,4-dioxane-2,5-dione, was synthesized. It is a suitable precursor for the preparation of a new hydrophilic biodegradable poly(a-hydroxy acid). The polymerizations were carried out in bulk in the presence of Sn(Oct)2 at 120-140℃. The resulting polymers were subjected to hydrogenolysis with a Pd/C catalyst in a mixed solvent to remove the protecting benzyl groups. A novel poly(a-hydroxy acid) with pendant hydroxy groups was obtained. The hydrophilicity of the resulting polymer was evaluated preliminarily.``

  13. Synthesis and biological activity of some heterocyclic compounds containing quinoxaline and coumarin moieties

    M. E. ABD EL-FATTAH; I. M. EL-DEEN

    2000-01-01

    2,3-Dichloroquinoxaline (2) condensed with 7,8-dihydroxy-4-methylcoumarin to give the 1,4-dioxane derivative 4. 2.3-Dichloroquinoxaline (2) reacted with 4-hydroxycoumarin, 7-hydroxy-4-methylcoumarin and acyl hydrazide 13 to give either the 2,3-(dicoumarin-4-yloxy)quinoxaline (6) or the 2,3-di-(4-methylcoumarin-7-yloxy)quinoxaline (7) or the 2-chloro-3-(coumarin-4-yloxy)quinoxaline (8) or the 2-chloro-3-(4-methylcoumarin-7-yloxy) quinoxaline (9) or the ditriazoloquinoxaline 14 or the oxa-diazi...

  14. Synthesis and antibacterial activity of some Schiff bases derived from 4-aminobenzoic acid

    JIGNA PAREKH

    2005-10-01

    Full Text Available The following Schiff bases have been synthesized: (1 4-[(2-chlorobenzylidene amino]benzoic acid [JP1], (2 4-[(furan-2-ylmethyleneamino]benzoic acid [JP2], (3 4-[(3-phenylallylideneamino]benzoic acid [JP3], (4 4-[(2-hydroxybenzylidene amino]benzoic acid [JP4], (5 4-[(4-hydroxy-3-methoxybenzylideneamino]benzoic acid [JP5] and (6 4-[(3-nitrobenzylideneamino]benzoic acid [JP6]. They were screened as potential antibacterial agents against a number of medically important bacterial strains. The antibacterial activity was studied against A. faecalis ATCC 8750, E. aerogenes ATCC 13048, E. coli ATCC 25922, K. pneumoniae NCIM 2719, S. aureus ATCC 25923, P. vulgaris NCIM 8313, P. aeruginosa ATCC 27853 and S. typhimurium ATCC 23564. The antibacterial activity was evaluated using the Agar Ditch method. The solvents used were 1,4-dioxane and dimethyl sulfoxide. Different effects of the compounds were found in the bacterial strains investigated and the solvents used, suggesting, once again, that the antibacterial activity is dependent on the molecular structure of the compound, the solvent used and the bacterial strain under consideration. In the present work, 1,4-dioxane proved to be a good solvent in inhibiting the above stated bacterial strains.

  15. Studies on percutaneous penetration of chemicals - Impact of storage conditions for excised human skin.

    Dennerlein, Kathrin; Schneider, Désirée; Göen, Thomas; Schaller, Karl Heinz; Drexler, Hans; Korinth, Gintautas

    2013-03-01

    According to international guidelines skin penetration experiments can be carried out using freshly excised or frozen stored skin. However, this recommendation refers to data obtained in experiments with human cadaver skin. In our study, the percutaneous penetration of the occupationally relevant chemicals anisole, cyclohexanone and 1,4-dioxane was investigated for freshly excised as well as for 4 and 30 days at -20°C stored human skin using the diffusion cell technique. As indicator for the impairment of skin barrier by freezing cholesterol dissolution was determined in the solvents in exposure chambers of diffusion cells. Considering the percutaneously penetrated amounts, the following ranking was determined: 1,4-dioxane>anisole>cyclohexanone (decline to a factor of 5.9). The differences of fluxes between freshly excised and frozen stored skin (4 and 30 days) were not significant (p>0.05). Cholesterol dissolved from the skin indicates no significant differences between freshly excised and frozen stored skin. This study shows that freezing of human skin for up to 30 days does not alter the skin barrier function and the permeability of chemicals.

  16. Transferable potentials for phase equilibria-united atom description of five- and six-membered cyclic alkanes and ethers.

    Keasler, Samuel J; Charan, Sophia M; Wick, Collin D; Economou, Ioannis G; Siepmann, J Ilja

    2012-09-13

    While the transferable potentials for phase equilibria-united atom (TraPPE-UA) force field has generally been successful at providing parameters that are highly transferable between different molecules, the polarity and polarizability of a given functional group can be significantly perturbed in small cyclic structures, which limits the transferability of parameters obtained for linear molecules. This has motivated us to develop a version of the TraPPE-UA force field specifically for five- and six-membered cyclic alkanes and ethers. The Lennard-Jones parameters for the methylene group obtained from cyclic alkanes are transferred to the ethers for each ring size, and those for the oxygen atom are common to all compounds for a given ring size. However, the partial charges are molecule specific and parametrized using liquid-phase dielectric constants. This model yields accurate saturated liquid densities and vapor pressures, critical temperatures and densities, normal boiling points, heat capacities, and isothermal compressibilities for the following molecules: cyclopentane, tetrahydrofuran, 1,3-dioxolane, cyclohexane, oxane, 1,4-dioxane, 1,3-dioxane, and 1,3,5-trioxane. The azeotropic behavior and separation factor for the binary mixtures of 1,3-dioxolane/cyclohexane and ethanol/1,4-dioxane are qualitively reproduced.

  17. Lactational transfer of volatile chemicals in breast milk.

    Fisher, J; Mahle, D; Bankston, L; Greene, R; Gearhart, J

    1997-06-01

    Lactational transfer of chemicals to nursing infants is a concern for occupational physicians when women who are breast-feeding return to the workplace. Some work environments, such as paint shops, have atmospheric contamination from volatile organic chemicals (VOCs). Very little is known about the extent of exposure a nursing infant may receive from the mother's occupational exposure. A physiologically based pharmacokinetic model was developed for a lactating woman to estimate the amount of chemical that a nursing infant ingests for a given nursing schedule and maternal occupational exposure. Human blood/air and milk/air partition coefficients (PCs) were determined for 19 VOCs. Milk/blood PC values were above 3 for carbon tetrachloride, methylchloroform, perchloroethylene, and 1,4-dioxane, while the remaining 16 chemicals had milk/blood PC values of less than 3. Other model parameters, such as solid tissue PC values, metabolic rate constants, blood flow rates, and tissue volumes were taken from the literature and incorporated into the lactation model. In a simulated exposure of a lactating woman to a threshold limit value concentration of an individual chemical, only perchloroethylene, bromochloroethane, and 1,4-dioxane exceeded the U.S. Environmental Protection Agency non-cancer drinking water ingestion rates for children. Very little data exists on the pharmacokinetics of lactational transfer of volatile organics. More data are needed before the significance of the nursing exposure pathway can be adequately ascertained. Physiologically based pharmacokinetic models can play an important role in assessing lactational transfer of chemicals.

  18. 纤维素酶催化与三液相萃取偶联制备盾叶薯蓣皂苷元%Preparation of diosgenin by integrated bioprocess of cellulase catalysis and extration in three-liquid-phase system

    魏夺; 董悦生; 韩松; 修志龙

    2012-01-01

    Using coupling biotech of cellulase-catalysis and extrusion in three-liquid-phase system that composed of n-hexane, 1,4-dioxane and ammonium sulfate to hydrolyze dioscin in Chinese yan and glucose connected to steroidal saponins, and extration separation to collect diosgenin. The distribution of several steroidal saponins, hydrolyzed glucose, enzyme and its activity in the three-phase system were studied, and catalytic conversion by cellulase-enzyme and formation of diosgenin in three-liquid, organic and aqueous phases were compared. The results showed that diosgenin yield in the three-liquid-phase system could compare with that in organic phase and aqueous phase. The three-liquid-phase system could be suitable for simultaneous enzymatic hydrolysis of steroidal saponins and extration of diosgenin and glucose. The substrate and enzyme were held in the middle phase of 1,4-dioxane, whiles the products, diosgenin and glucose, were partitioned into the top and bottom phase, respectively. The yields of diosgenin was 69. 4% at 96 h in the three-liquid-phase system, which was twice and 27. 6 folds obtained in organic phase and aqueous phase respectively.

  19. Optimized and Validated Spectrophotometric Methods for the Determination of Enalapril Maleate in Commercial Dosage Forms

    Sk Manirul Haque

    2008-01-01

    Full Text Available Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO3 and iodide (KI to form yellow colored product in aqueous medium at 25 ± 1°C .The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beer’s law is obeyed in the concentration ranges of 2.5–50, 20–560, 5–75 and 10–200 μg mL−1, respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically.

  20. Advanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identification.

    Alvarez-Corena, Jose R; Bergendahl, John A; Hart, Fred L

    2016-10-01

    The extent and kinetics of degradation of 1,4 dioxane, n-nitrosodimethylamine (NDMA), tris-2-chloroethyl phosphate (TCEP), gemfibrozil, and 17β estradiol in a prepared aqueous matrix by means of UV/TiO2 (ultraviolet light/titanium dioxide) oxidation was evaluated. Degussa P25 TiO2 was employed as a photocatalyst excited by UV light in a 1 L water-jacketed batch photoreactor. The rate of degradation was modeled using a pseudo-first order rate model and the Langmuir-Hinshelwood rate model with a high correlation. Degradation rate constants were found to be maximum at pH 5.0 and 1.5 g L(-)(1) TiO2 dose. For these conditions first order rate constants, values were as follows: 0.29 min(-1) for 1,4 dioxane, 0.50 min(-1) for NDMA, 0.12 min(-1) for TCEP, 0.61 min(-1) for gemfibrozil, and 0.53 min(-1) for 17β estradiol. While for the Langmuir-Hinshelwood rate model, the following constants were found: 0.11 Lmg(-1) and 2.81 mgL(-1) min(-1) for 1,4 dioxane, 0.12 Lmg(-1) and 4.35 mgL(-1) min(-1) for NDMA, 0.06 Lmg(-1) and 1.79 mgL(-1) min(-1) for TCEP, 0.21 Lmg(-1) and 3.27 mgL(-1) min(-1) for gemfibrozil, and 0.15 Lmg(-1) and 3.43 mgL(-1) min(-1) for 17β estradiol. In addition, specific byproducts of degradation were identified using GC/MS analysis. The results obtained from the kinetics analysis showed that UV/TiO2 oxidation is a promising process for treating trace organic contaminants in water, but further research is needed to better understand how to incorporate these findings into pilot and full-scale designs. The toxicity of oxidation byproducts, and their potential for interacting with other compounds should be considered in the treatment of contaminated waters using the UV/TiO2 oxidation process.

  1. Halogen-bonded network of trinuclear copper(II 4-iodopyrazolate complexes formed by mutual breakdown of chloroform and nanojars

    Stuart A. Surmann

    2016-11-01

    Full Text Available Crystals of bis(tetrabutylammonium di-μ3-chlorido-tris(μ2-4-iodopyrazolato-κ2N:N′tris[chloridocuprate(II] 1,4-dioxane hemisolvate, (C16H36N2[Cu3(C3H2IN23Cl5]·0.5C4H8O or (Bu4N2[CuII3(μ3-Cl2(μ-4-I-pz3Cl3]·0.5C4H8O, were obtained by evaporating a solution of (Bu4N2[{CuII(μ-OH(μ-4-I-pz}nCO3] (n = 27–31 nanojars in chloroform/1,4-dioxane. The decomposition of chloroform in the presence of oxygen and moisture provides HCl, which leads to the breakdown of nanojars to the title trinuclear copper(II pyrazolate complex, and possibly CuII ions and free 4-iodopyrazole. CuII ions, in turn, act as catalyst for the accelerated decomposition of chloroform, ultimately leading to the complete breakdown of nanojars. The crystal structure presented here provides the first structural description of a trinuclear copper(II pyrazolate complex with iodine-substituted pyrazoles. In contrast to related trinuclear complexes based on differently substituted 4-R-pyrazoles (R = H, Cl, Br, Me, the [Cu3(μ-4-I-pz3Cl3] core in the title complex is nearly planar. This difference is likely a result of the presence of the iodine substituent, which provides a unique, novel feature in copper pyrazolate chemistry. Thus, the iodine atoms form halogen bonds with the terminal chlorido ligands of the surrounding complexes [mean length of I...Cl contacts = 3.48 (1 Å], leading to an extended two-dimensional, halogen-bonded network along (-110. The cavities within this framework are filled by centrosymmetric 1,4-dioxane solvent molecules, which create further bridges via C—H...Cl hydrogen bonds with terminal chlorido ligands of the trinuclear complex not involved in halogen bonding.

  2. Studies on Excess Volume, Viscosity, and Speed of Sound of Binary Mixtures of Methyl Benzoate in Ethers at T=(303.15,308.15, and 313.15 K

    M. V. Rathnam

    2013-01-01

    Full Text Available Densities, viscosities, and speed of sound have been determined at T = (303.15, 308.15, and 313.15 K for the binary mixtures of methyl benzoate with tetrahydrofuran, 1,4-dioxane, anisole, and butyl vinyl ether over the entire range of composition. Using these measured values, excess volume VE, deviation in viscosities Δη, excess Gibb’s free energy of activation for viscous flow ΔG*E, and deviation in isentropic compressibility Δks have been calculated. These calculated binary data have been fitted to Redlich-Kister equation to determine the appropriate coefficients. The values of excess volume VE and deviation in viscosities Δη are negative over the entire range of composition for all the binary systems at the studied temperatures. The behavior of these parameters with composition of the mixture has been discussed in terms of molecular interactions between the components of liquids.

  3. Comparison of UVC/S2O8 2- with UVC/H2O2 in terms of efficiency and cost for the removal of micropollutants from groundwater

    Antoniou, Maria; Andersen, Henrik Rasmus

    2015-01-01

    This study compared the UVC/S2O8(2-) system with the more commonly used AOP in water industry, UVC/H2O2, and examined whether the first one can be an economically feasible alternative technology. Atrazine and 4 volatile compounds (methyl tert-butyl ether, cis-dichlorethen, 1,4-dioxane and 1......' concentrations were tested with atrazine alone and in the micropollutants' mixture and it was decided to use 11.8mgL(-1) S2O8(2-) and 14.9mgL(-1) H2O2 for further testing since is closer to industrial applications and to minimize the residual oxidant concentration. Changes of the matrix composition...... with the mixture of micropollutants gave better insights to their efficiency than atrazine alone and UVC/S2O8(2-) is recommended for selective oxidation of challenging matrices....

  4. Synthesis and characterization of luminescent organic-inorganic hybrid nanocomposite from polyhedral oligomeric silsesquioxane

    Yan

    2010-01-01

    A novel polyhedral oligomeric silsesquioxane (POSS)-based organic-inorganic hybrid nanocomposite (EF-POSS) was prepared by Pt-catalyzed hydrosilylation reaction of octahydridosilsesquioxane (T8H8, POSS) with a luminescent substituted acetylene (2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-dioctyl-9H-fluorene (EF)) in high yield. The hybrid nanocomposite was soluble in common solvents such as CH2Cl2, CHCl3, THF and 1,4-dioxane. Its structure and property were characterized by FTIR, NMR, TGA, UV and PL, respectively. The results show that the hybrid nanocomposite with high thermal stability emits stable blue light as a result of photo excitation and possesses high photoluminescence quantum efficiency (φfL).

  5. SYNTHESIS AND CHARACTERIZATION OF A METHACRYLATE POLYMER WITH SIDE CHAIN KETONE AND ITS DERIVATIVES

    Ibrahim Erol; Cemal Cifci

    2011-01-01

    A new type of methacrylate monomer, 2-(4-benzoylphenoxy)-2-oxoethyl methylacrylate (BOEMA) was synthesized. The radical homopolymerization of BOEMA was performed at 65℃ in a 1,4-dioxane solution with benzoyl peroxide as an initiator. The oxime and thiosemicarbazone derivatives of poly[2-(4-benzoylphenoxy)-2-oxoethyl methylacrylate] poly(BOEMA) were prepared with hydroxylamine hydrochloride, and thiosemicarbazone hydrochloride,respectively. The monomer and its homopolymer were characterized with Fourier transform infrared and NMR techniques.The thermal stabilities of poly(BOEMA) and its derivatives were investigated with thermogravimetric analysis and differential scanning calorimetry. The ultraviolet stability of the polymers was compared. The antibacterial and antifungal effects of the monomer and the polymer and its derivatives were also investigated on various bacteria and fungi. The activation energies of the thermal degradation of the polymers were calculated with the Ozawa and Kissinger methods.

  6. 利用二元体系的C-H红外光谱推算汽液平衡数据%Prediction of Vapor-Liquid Equilibrium Data from C-H Band Shift of IR Spectra in Some Binary Systems

    朱霄; 姚加; 李浩然; 韩世钧

    2007-01-01

    Prediction of vapor-liquid equilibrium (VLE) is extremely necessary to separate liquid mixture in chemical production, especially when the required experimental data are difficult to measure, or the measurement is not economical. The infinite dilution activities can be used to predict VLE. However, it needs both thc ends of the activities that are difficult to obtain for many systems. In the present study, a new model is proposed for correlating the frequency shift of C-H stretching band of IR spectra over the whole concentration. Investigated mixtures include water/2-propanol, water/N, N-dimethylformamide (DMF), water/methanol, water/ethanol, water/1, 4-dioxane,and water/dimethylsulfoxidc (DMSO) systems. Simultaneous correlations of C-H frequency shift and VLE data arc made. Furthermore, the VLE data were predicted with satisfactory results by the parameters obtained from IR spectra coupled with one of the infinite dilution activity coefficients.

  7. Studies of linear correlation factor of dielectric polarization and excess dipolar free energies of amides in apolar solvents

    M Malathi; R Sabesan; S Krishnan

    2005-09-01

    The Kirkwood–Frohlich correlation factor (), Eyring's parameters and * and the dipolar excess free energies of dilute solutions of formamide, acetamide, -methyl acetamide, , -dimethyl formamide and , -dimethyl acetamide in 1,4-dioxan/benzene were obtained from a measurement of their static dielectric permittivities at 308 K. The fluid structure of these amides is discussed. Both in formamide and acetamide a dimeric linear chain with the individual dipoles more or less parallely oriented is preferred. In -methyl acetamide, the antiparallel orientation of dipoles at lower concentrations turns into a parallel orientation with increase of concentration. In tertiary amides, with increase of concentration, parallel orientation of dipoles with global value of tending to unity is observed. The dipolar excess free energy of mixing in a given solvent is of the order primary amide > secondary amide > tertiary amide.

  8. Selective hydrogenation of maleic anhydride over Pd/Al2O3 catalysts prepared via colloid deposition

    Hongjing Yuan; Chunlei Zhang; Weitao Huo; Chunli Ning; Yong Tang; Yi Zhang; Dequan Cong; Wenxiang Zhang; Jiahuan Luo; Su Li; Zhenlu Wang

    2014-01-01

    Pd/Al2O3 catalysts were prepared via colloid deposition and the performance of the catalysts was examined in the selective hydrogenation of maleic anhydride to succinic anhydride. When the reaction was carried on in a batch system with 1,4-dioxane as the solvent (353K and 1.0MPa), high conversion of maleic anhydride (>98%) and high selectivity (>99%) for succinic anhydride were observed after 5 h. The as-prepared Pd/Al2O3 catalyst also showed excellent performance in solvent-free system and fixed-bed systems. The maleic anhydride (MA) conversion was greater than 98%, and high selectivity (>99%) for succinic anhydride was obtained after 1600 h in a fixed bed reacter. The results showed that the activity of the Pd/Al2O3 catalysts was excellent due to its high active surface area.

  9. Isothermal (vapour + liquid) equilibrium of (cyclic ethers + chlorohexane) mixtures: Experimental results and SAFT modelling

    Bandres, I.; Giner, B.; Lopez, M.C.; Artigas, H. [Departamento de Quimica Organica y Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Lafuente, C. [Departamento de Quimica Organica y Quimica Fisica, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain)], E-mail: celadi@unizar.es

    2008-08-15

    Experimental data for the isothermal (vapour + liquid) equilibrium of mixtures formed by several cyclic ethers (tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 1,4-dioxane) and chlorohexane at temperatures of (298.15 and 328.15) K are presented. Experimental results have been discussed in terms of both, molecular characteristics of pure compounds and potential intermolecular interaction between them using thermodynamic information of the mixtures obtained earlier. Furthermore, the influence of the temperature on the (vapour + liquid) equilibrium of these mixtures has been explored and discussed. Transferable parameters of the SAFT-VR approach together with standard combining rules have been used to model the phase equilibrium of the mixtures and a description of the (vapour + liquid) equilibrium of them that is in excellent agreement with the experimental data are provided.

  10. Application of Solubility Parameter Theory to Organosolv Extraction of Lignin from Enzymatically Hydrolyzed Cornstalks

    Yueyuan Ye

    2014-04-01

    Full Text Available The Hildebrand solubility parameter (delta-value was applied to explain the effect of organic solvent concentration on lignin removal during organosolv extraction of lignin from enzymatically hydrolyzed cornstalks under atmospheric pressure and low temperature (≤ 75 °C without additional catalyst. The -value of lignin, calculated using the group-contribution method, was 13.70 (cal/cm31/2. The proximity of the delta-value between organic solvent-water and lignin explained the delignification capacity of the organic solvent-water. The concentration of organic solvent in the aqueous mixture that led to the highest delignification (i.e., 34.5%, 41.8%, and 53.7% delignification for ethanol-water, 1,4-dioxane-water, and tetrahydrofuran-water, respectively was around 65 to 75% vol., which was in keeping with the prediction by the solubility parameter theory.

  11. Laboratory shake flask batch tests can predict field biodegradation of aniline in the Rhine

    Toräng, Lars; Reuschenbach, P.; Müller, B.

    2001-01-01

    The aim of this study was to compare degradation rates of aniline in laboratory shake flask simulation tests with field rates in the river Rhine. The combined events of a low flow situation in the Rhine and residual aniline concentrations in the effluent from the BASF treatment plant...... in Ludwigshafen temporarily higher than normal, made it possible to monitor aniline at trace concentrations in the river water downstream the wastewater outlet by means of a sensitive GC headspace analytical method. Aniline was analyzed along a downstream gradient and the dilution along the gradient...... was calculated from measurements of conductivity, sulfate and a non-readily biodegradable substance, 1,4-dioxane. Compensating dilution, field first-order degradation rate constants downstream the discharge of BASF were estimated at 1.8 day(-1) for two different dates with water temperatures of 21.9 and 14...

  12. Gold(I-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl ethers: synthesis of 3-iodo-2H-chromene derivatives

    Pablo Morán-Poladura

    2013-10-01

    Full Text Available An efficient entry to the preparation of elusive 4-unsubstituted-3-iodo-2H-chromenes has been accomplished as result of a catalytic cyclization. Thus, upon exposition of [(3-iodoprop-2-yn-1-yloxy]arenes to IPrAuNTf2 (3 mol %, in 1,4-dioxane at 100 °C, the desired heterocyclic motif is readily assembled. This process nicely tolerates a variety of functional groups and, interestingly, it is compatible with the presence of strong electron-withdrawing groups attached to the arene. The overall transformation can be termed as a new example of a migratory cycloisomerization and, formally, it involves well-blended 1,2-iodine shift and hydroarylation steps.

  13. 40 CFR Appendix V to Part 266 - Risk Specific Doses (10−5)

    2010-07-01

    ...−04 4.5E−02 1,4-Dioxane 123-91-1 1.4E−06 7.1E+00 Epichlorohydrin 106-89-8 1.2E−06 8.3E+00 Ethylene.... Unit risk (m3/μg) RsD (μg/m3) Acrylamide 79-06-1 1.3E−03 7.7E−03 Acrylonitrile 107-13-1 6.8E−05 1.5E−01 Aldrin 309-00-2 4.9E−03 2.0E−03 Aniline 62-53-3 7.4E−06 1.4E+00 Arsenic 7440-38-2 4.3E−03 2.3E−03...

  14. PDMS/glass microfluidic cell culture system for cytotoxicity tests and cells passage

    Ziolkowska, K.; Jedrych, E.; Kwapiszewski, R.

    2010-01-01

    microdevice was developed and successfully tested. The MCCS microdevice is fully reusable, i.e. it can be used several times for various cell culture and cytotoxic experiments. The suitability of designed MCCS for cell-based cytotoxicity assay application was verified using 1,4-dioxane as a model toxic agent....... The series of cytotoxicity tests in the microdevice as well as in classic way using 96-well cell culture plates were performed to compare results obtained in micro- and macroscale. Fluorescein dibutyrate (FDB) and iodide propidine (PI) were used as viable and dead cells' markers, respectively. Fabricated...... MCCS microdevices were reproducible and apart from cell culture for long period of time, including cell passaging, it allowed cell-based cytotoxicity assays performance. The MCCS can be applied in high-throughput cell-based assays providing important informations on potential drug targets, substances...

  15. Ammonium Y zeolite applied as a thermochemolysis reagent for identification of polyethers and polyesters.

    Blazsó, Marianne; Bozi, János

    2013-01-04

    A potential thermochemolysis reagent has been tested for the pyrolysis gas chromatographic identification of polyether, polyester and polyether- or polyester-based thermoplastic polyurethane. The main advantage of ammonium Y zeolite over liquid reagents is that it does not react prior to pyrolysis, and its reactions have no incomplete products. The procedure of the thermochemolysis is as simple as running a pyrolysis-GC/MS analysis sampling a powder mixture of roughly equal mass of polymer and ammonium Y zeolite. The GC/MS chromatograms obtained show that the products of thermochemolysis are specific to the diol and dicarboxylic units of the polymer. It was observed that ethanal or 1,4-dioxane forms from ethylene oxide components of polyethers and polyesters, tetrahydrofuran from butylene oxide units, hexanedinitrile from adipate groups, and benzodinitrile from terephthalate groups.

  16. Heterocyclic Analogues of Xanthone and Xanthione. 1H-Pyrano[2,3-c:6,5-c]dipyrazol-4(7H-ones and Thiones: Synthesis and NMR Data

    Wolfgang Holzer

    2010-09-01

    Full Text Available The synthesis of the title compounds is described. Reaction of 1-substituted 2-pyrazolin-5-ones with 5-chloro-1-phenyl-1H-pyrazole-4-carbonyl chloride or 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbonyl chloride, respectively, using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-heteroaroylpyrazol-5-ols, which were cyclized into 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H-ones by treatment with K2CO3/DMF. The latter were converted into the corresponding thiones upon reaction with Lawesson’s reagent. Detailed NMR spectroscopic investigations (1H, 13C, 15N of the ring systems and their precursors are presented.

  17. Systematic investigation of thorium(IV)- and uranium(IV)-ligand bonding in dithiophosphonate, thioselenophosphinate, and diselenophosphonate complexes.

    Behrle, Andrew C; Barnes, Charles L; Kaltsoyannis, Nikolas; Walensky, Justin R

    2013-09-16

    Homoleptic soft-donor actinide complexes of the general form An[E2PROR']4 were synthesized from salt metathesis between ThCl4(DME)2 or UI4(1,4-dioxane)2 and M[E2PROR'], M = Na, K, to yield 2 (An = Th, E = S, R = 4-MeOC6H4, R' = Me), 3 (An = Th, E = S, R = 4-MeOC6H4, R' = (t)Bu), 4 (An = U, E = S, R = 4-MeOC6H4, R' = Me), 5 (An = Th, E = Se, R = C6H5, R' = Me), and 6 (An = U, E = Se, R = C6H5, R' = Me). In addition thorium and uranium thioselenophosphinate complexes 7 and 8 were produced from the reaction of ThCl4(DME)2 and UI4(1,4-dioxane)2 and Na[SSePPh2], respectively. All compounds were characterized using elemental analysis, (1)H and (31)P NMR, and IR spectroscopy, and the U(IV) compounds were also examined with UV-vis spectroscopy. The (77)Se NMR spectrum of 5 reveals the first reported resonance with a Th-Se bond. The solid-state structures of 2, 5, 7, and 8 were determined by X-ray crystallography. The actinide-ligand bonding was examined using density functional theory calculations in conjunction with quantum theory of atoms-in-molecules analysis and shows slightly increased covalency in actinide-selenium bonds than actinide-sulfur.

  18. Anti-inflammatory activity of extracts from leaves of Phyllanthus emblica.

    Ihantola-Vormisto, A; Summanen, J; Kankaanranta, H; Vuorela, H; Asmawi, Z M; Moilanen, E

    1997-12-01

    Leaves and fruits of Phyllanthus emblica L. have been used for the anti-inflammatory and antipyretic treatment of rural populations in its growing areas in subtropical and tropical parts of China, India, Indonesia, and the Malay Peninsula. In the present study, leaves of Ph. emblica were extracted with ten different solvents (n-hexane, diethyl ether, methanol, tetrahydrofuran, acetic acid, dichloromethane, 1,4-dioxane, toluene, chloroform, and water). The inhibitory activity of the extracts against human polymorphonuclear leukocyte (PMN) and platelet functions was studied. Methanol, tetrahydrofuran, and 1,4-dioxane extracts (50 micrograms/ml) inhibited leukotriene B4-induced migration of human PMNs by 90% and N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-induced degranulation by 25-35%. The inhibitory activity on receptor-mediated migration and degranulation of human PMNs was associated with a high proportion of polar compounds in the extracts as assessed by normal phase thin layer chromatography. Diethyl ether extract (50 micrograms/ml) inhibited calcium ionophore A23187-induced leukotriene B4 release from human PMNs by 40%, thromboxane B2 production in platelets during blood clotting by 40% and adrenaline-induced platelet aggregation by 36%. Ellagic acid, gallic acid and rutin, all compounds isolated earlier from Ph. emblica, could not explain these inhibitory activities on PMNs or platelets by Ph. emblica extracts. These results show that the leaves of Ph. emblica have inhibitory activity on PMNs and platelets, which confirm the anti-inflammatory and antipyretic properties of this plant as suggested by its use in traditional medicine. The data suggest that the plant leaves contain as yet unidentified polar compound(s) with potent inhibitory activity on PMNs and chemically different apolar molecule(s) which inhibit both prostanoid and leukotriene synthesis.

  19. Aqueous foam toxicology evaluation and hazard review

    Archuleta, M.M.

    1995-10-01

    Aqueous foams are aggregates of bubbles mechanically generated by passing air or other gases through a net, screen, or other porous medium that is wetted by an aqueous solution of surface-active foaming agents (surfactants). Aqueous foams are important in modem fire-fighting technology, as well as for military uses for area denial and riot or crowd control. An aqueous foam is currently being developed and evaluated by Sandia National Laboratories (SNL) as a Less-Than-Lethal Weapon for the National Institute of Justice (NIJ). The purpose of this study is to evaluate the toxicity of the aqueous foam developed for the NIJ and to determine whether there are any significant adverse health effects associated with completely immersing individuals without protective equipment in the foam. The toxicity of the aqueous foam formulation developed for NIJ is determined by evaluating the toxicity of the individual components of the foam. The foam is made from a 2--5% solution of Steol CA-330 surfactant in water generated at expansion ratios ranging from 500:1 to 1000:1. SteoI CA-330 is a 35% ammonium laureth sulfate in water and is produced by Stepan Chemical Company and containing trace amounts (<0.1%) of 1,4-dioxane. The results of this study indicate that Steol CA-330 is a non-toxic, mildly irritating, surfactant that is used extensively in the cosmetics industry for hair care and bath products. Inhalation or dermal exposure to this material in aqueous foam is not expected to produce significant irritation or systemic toxicity to exposed individuals, even after prolonged exposure. The amount of 1,4-dioxane in the surfactant, and subsequently in the foam, is negligible and therefore, the toxicity associated with dioxane exposure is not significant. In general, immersion in similar aqueous foams has not resulted in acute, immediately life-threatening effects, or chronic, long-term, non-reversible effects following exposure.

  20. Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes.

    Uzelac, Marina; Borilovic, Ivana; Amores, Marco; Cadenbach, Thomas; Kennedy, Alan R; Aromí, Guillem; Hevia, Eva

    2016-03-24

    By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3 ⋅C6 H6}2] (2) and [{NaMn(CH2SiMe3)3}2 (dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2 (CH2SiMe3)6 (DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2 (CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.

  1. 脱氢松香基有机小分子凝胶因子的合成及其性能%Synthesis and Properties of Organic Gelator Based on Dehydroabietate Derivative

    童碧海; 张曼; 李剑飞; 马鹏; 王恒山; 张千峰

    2014-01-01

    A novel low-molecular-mass organic gelator (DBNPM) was synthesized from 12-bromine-13, 14-dinitro dehydroabietic acid methyl ester. The title compound was characterized by 1H NMR, 13C NMR, IR and MS techniques. The assembly behavior of the prepared organogelator in solution was investigated. The organogelator induced gelation in a wide variety of organic solvents. With methanol as solvent, the critical gelation concentration (CGC) of the prepared gelator was the minimum, 0. 5 g/L. But the gelatination property was the most stable in 1, 4-dioxane. Scanning eletron microscope (SEM) images indicated that the xerogels from methanol solution presented flaky structure and the xerogels from 1, 4-dioxane solution were net-like structure. Infrared spectra ( FT-IR) and XRD showed that hydrogen bond was the main driving force for the formation of organogels.%用12-溴-13,14-双硝基脱氢松香酸甲酯合成了一种新型的有机小分子凝胶因子1,4a-二甲基-6-溴-1,2,3,4,4a,17,18,18a-八氢萘基[2,1-h]二吡啶并[3,2-a:2,3-c]吩嗪甲酸甲酯( DBNPM),通过1H NMR,13C NMR, MS和IR等表征手段对产物结构进行了表征。为了考察此小分子凝胶因子的自组装行为,研究了该分子在不同有机溶剂中的成胶性能和形貌。研究发现,在甲醇中临界成胶浓度(CGC)最低,为0.5 g/L;但是在二氧六环中凝胶性质最为稳定。扫描电镜(SEM)照片显示,从甲醇溶剂中得到的干胶呈片状结构,从二氧六环溶剂中得到的干胶呈网状结构;通过红外光谱和XRD测试研究证实,该化合物分子间的氢键是凝胶化的重要驱动力之一。

  2. Caging and solvent effects on the tautomeric equilibrium of 3-pyridone/3-hydroxypyridine in the ground state: a study in cyclodextrins and binary solvents.

    Abou-Zied, Osama K; Al-Shihi, Othman I K

    2009-07-14

    The tautomeric equilibrium between 3-pyridone (3Py) and 3-hydroxypyridine (3HP) shows characteristic absorption peaks for the zwitterion form of 3Py in water that may be used as a probe of the hydrophobic nature inside macromolecules such as proteins and other biologically related systems. We studied this equilibrium in the ground state in aqueous cyclodextrins (CDs) and in binary solvent mixtures of 1,4-dioxane and water by absorption spectroscopy, and by ab initio calculations. Upon the addition of alpha-CD or beta-CD to an aqueous solution of the 3Py/3HP system, the absorbance intensity of the zwitterion tautomer decreases with a concomitant increase in the intensity of the enol tautomer of 3HP. The results reflect the nature of the tautomeric equilibrium and point to the hydrophobic environment inside the CD cavities. The effect of inclusion is noticeably less in the case of alpha-CD. This is attributed to the small cavity size of alpha-CD which sustains only partial inclusion. Upon the addition of gamma-CD, the intensity of the zwitterion tautomer slightly increased over that in water which is attributed to the direct interaction between the charged sides of the tautomer with the outer primary or secondary hydroxyls of the glycopyranose units of gamma-CD. This interaction is a result of the large cavity size of gamma-CD which does not support a stable complex. The largest caging effect was observed in 2,6-di-O-methyl-beta-CD (DMbeta-CD) which is an indication of a more hydrophobic environment around the guest. The large hydrophobicity of DMbeta-CD is due to the presence of the two methyl groups in the beta-CD derivative which reduce the amount of water inside the cavity upon encapsulation. In the binary mixtures of 1,4-dioxane and water, the change in the absorbance intensity of the enol and the zwitterion tautomers was analyzed quantitatively and three water molecules were found to solvate the polar centers of each tautomer. Ab initio calculations of the

  3. Studies in reactive extrusion processing of biodegradable polymeric materials

    Balakrishnan, Sunder

    Various reaction chemistries such as Polymerization, Polymer cross-linking and Reactive grafting were investigated in twin-screw extruders. Poly (1,4-dioxan-2-one) (PPDX) was manufactured in melt by the continuous polymerization of 1,4-dioxan-2-one (PDX) monomer in a twin-screw extruder using Aluminum tri-sec butoxide (ATSB) initiator. Good and accurate control over molecular weight was obtained by controlling the ratio of monomer to initiator. A screw configuration consisting of only conveying elements was used for the polymerization. The polymerization reaction was characterized by a monomer-polymer dynamic equilibrium, above the melting temperature of the polymer, limiting the equilibrium conversion to 78-percent. Near complete (˜100-percent) conversion was obtained on co-polymerizing PDX monomer with a few mol-percent (around 8-percent) Caprolactone (CL) monomer in a twin-screw extruder using ATSB initiator. The co-polymers exhibited improved thermal stability with reduction in glass transition temperature. The extruder was modeled as an Axial Dispersed Plug Flow Reactor for the polymerization of CL monomer using Residence Time Distribution (RTD) Analysis. The model provided a good fit to the experimental RTD and conversion data. Aliphatic and aliphatic-aromatic co-polyesters, namely Polycaprolactone (PCL) and Poly butylenes (adipate-co-terephthalate) (Ecoflex) were cross-linked in a twin-screw extruder using radical initiator to form micro-gel reinforced biodegradable polyesters. Cross-linked Ecoflex was further extrusion blended with talc to form blends suitable to be blown into films. A screw configuration consisting of conveying and kneading elements was found to be effective in dispersion of the talc particles (5--10 microns) in the polyester matrix. While the rates of crystallization increased for the talc filled polyester blends, overall crystallinity reduced. Mechanical, tear and puncture properties of films made using the talc filled polyester blends

  4. Innovative Protocols for in SITU MTBE Degradation by Using Molecular Probes-An Enhanced Chemical-Bio Oxidation Technique

    Paul Fallgren

    2009-02-20

    In situ chemical oxidation (ISCO) is a common technology to cleanup petroleum hydrocarbon-contaminated soils and groundwater. Sodium percarbonate (SPC) is an oxidant which is activated by iron (Fe) to produce Fenton-like reactions. Western Research Institute, in conjunction with Regenesis and the U.S. Department of Energy, conducted a study that investigated the performance of a 'safe' oxidant, SPC, to cleanup groundwater and soils contaminated with petroleum hydrocarbons and associated contaminants (e.g., MTBE). Results from a field pilot test in Frenchglen, Oregon showed VOC concentrations in groundwater decreased substantially within 2 weeks after injecting activated SPC (RegenOx). A protocol was established for determining RegenOx TOD in soils and groundwater. Total oxidant demand tests were necessary to determine the correct dosage of RegenOx to apply in the field and sufficiently degrade the contaminants of concern. Bench studies with RegenOx showed this technology was effective in degrading diesel fuel and 1,4-dioxane. The Fe-silica activator (RegenOx Part B) was tested with another oxidant, sodium persulfate. Bench tests results showed the combination of sodium persulfate and RegenOx Part B was effective in reducing PCE, MTBE, benzene, and n-heptane concentrations in water. Overall, the results of this project indicated that most petroleum contaminants in soil and groundwater can be sufficiently degraded using the RegenOx technology.

  5. 2H-WS2 Quantum Dots Produced by Modulating the Dimension and Phase of 1T-Nanosheets for Antibody-Free Optical Sensing of Neurotransmitters.

    Kim, Man-Jin; Jeon, Su-Ji; Kang, Tae Woog; Ju, Jong-Min; Yim, DaBin; Kim, Hye-In; Park, Jung Hyun; Kim, Jong-Ho

    2017-03-28

    Modulating the dimensions and phases of transition metal dichalcogenides is of great interest to enhance their intrinsic properties or to create new physicochemical properties. Herein, we report an effective approach to synthesize 2H-WS2 quantum dots (QDs) via the dimension and phase engineering of 1T-WS2 nanosheets. The solvothermal reaction of chemically exfoliated 1T-WS2 nanosheets in N-methyl-2-pyrrolidone (NMP) under an N2 atmosphere induced their chopping and phase transition at lower temperature to produce 2H-WS2 QDs with a high quantum yield (5.5 ± 0.3%). Interestingly, this chopping and phase transition process showed strong dependency on solvent; WS2 QDs were not produced in other solvents such as 1,4-dioxane and dimethyl sulfoxide. Mechanistic investigations suggested that NMP radicals played a crucial role in the effective production of 2H-WS2 QDs from 1T-WS2 nanosheets. WS2 QDs were successfully applied for the selective, sensitive, and rapid detection of dopamine in human serum (4 min, as low as 23.8 nM). The intense fluorescence of WS2 QDs was selectively quenched upon the addition of dopamine and Au(3+) ions due to fluorescence resonance energy transfer between WS2 QDs and the quickly formed Au nanoparticles. This new sensing principle enabled us to discriminate dopamine from dopamine-derivative neurotransmitters including epinephrine and norepinephrine, as well as other interference compounds.

  6. Preparation and characterization of biopolymers comprising chitosan-grafted-ENR via acid-induced reaction of ENR50 with chitosan

    M. R. H. Mas Haris

    2014-02-01

    Full Text Available This paper describes the first detailed tailored-approach for the preparation of biopolymers comprising chitosan (CTS grafted onto the backbone of epoxidized natural rubber (CTS-g-ENR. In a typical experiment, appropriate amount of CTS and AlCl3•6H2O was added to a specified amount of ENR50 (ENR with about 50% epoxy content dissolved in a dual-solvent consisting of 1,4-dioxane and water (97.5:2.5% v/v and the resulting mixture refluxed with continuous stirring for 6 hours. Nuclear magnetic resonance (NMR spectral analysis of a biocomposite, CTS-g-ENR-P1, revealed that its epoxy content is 22.36% which is considerably lower than 44.93% as determined for ENR50-control (ENR50 derivative obtained under similar experimental condition but in the absence of CTS. This means that the grafting of CTS onto the backbone of ENR had occurred. The revelation is affirmed by the presence of the characteristic absorption bands of CTS and ENR, and the appearance of new bands at 1219, 902 and 733 cm–1 in the Fourier transform infrared (FTIR spectrum of CTS-g-ENR-P1. Further evidence that CTS had been successfully grafted onto the backbone of ENR can be deduced and described in this paper from the data obtained by means of Differential Scanning Calorimetric analysis, Thermogravimetric analysis and Variable Pressure Scanning Electron Microscopy.

  7. Supramolecular Assemblies from Poly(styrene-block-poly(4-vinylpyridine Diblock Copolymers Mixed with 6-Hydroxy-2-naphthoic Acid

    Jean-François Gohy

    2013-06-01

    Full Text Available Supramolecular assemblies involving interaction of a small organic molecule, 2-hydroxy-6-Naphthoic acid (HNA, with poly(styrene-block-poly(4-vinylpyridine (PS-b-P4VP diblock copolymers are utilized to obtain micellar structures in solution, nanostructured thin films on flat substrates and, finally, nanoporous thin films. The formation of hydrogen bonds between HNA and the poly(4-vinylpyridine (P4VP blocks is confirmed by spectroscopic measurements. The accordingly P4VP/HNA hydrogen-bonded complexes are poorly soluble in 1,4-dioxane, resulting in the formation of micellar structures with a P4VP/HNA core and a polystyrene (PS corona. Those micelles have been spin-coated onto silicon wafers, resulting in nanostructured thin films consisting of P4VP/HNA dot-like features embedded in a PS matrix. The morphology of those films has been tuned by solvent annealing. Selective dissolution of HNA by methanol results in the formation of a nanoporous thin film. The P4VP/HNA nanodomains have been also cross-linked by borax, and the thin films have been further dissolved in a good solvent for PS, leading to micelles with a structure reminiscent of the thin films.

  8. Epistemology of Contaminants of Emerging Concern and Literature Meta-analysis

    Halden, Rolf U.

    2014-01-01

    A meta-analysis was conducted to inform the epistemology, or theory of knowledge, of contaminants of emerging concern (CECs). The CEC terminology acknowledges the existence of harmful environmental agents whose identities, occurrences, hazards, and effects are not sufficiently understood. Here, data on publishing activity were analyzed for 12 CECs, revealing a common pattern of emergence, suitable for identifying past years of peak concern and forecasting future ones: dichlorodiphenyltrichloroethane (DDT; 1972, 2008), trichloroacetic acid (TCAA; 1972, 2009), nitrosodimethylamine (1984), methyl tert-butyl ether (2001), trichloroethylene (2005), perchlorate (2006), 1,4-dioxane (2009), prions (2009), triclocarban (2010), triclosan (2012), nanomaterials (by 2016), and microplastics (2022 ± 4). CECs were found to emerge from obscurity to the height of concern in 14.1 ± 3.6 years, and subside to a new baseline level of concern in 14.5 ± 4.5 years. CECs can emerge more than once (e.g., TCAA, DDT) and the multifactorial process of emergence may be driven by inception of novel scientific methods (e.g., ion chromatography, mass spectrometry and nanometrology), scientific paradigm shifts (discovery of infectious proteins), and the development, marketing and mass consumption of novel products (antimicrobial personal care products, microplastics and nanomaterials). Publishing activity and U.S. regulatory actions were correlated for several CECs investigated. PMID:25294779

  9. RING OPENING COPOLYMERIZATION OF SUCCINIC ANHYDRIDE-ETHYLENE OXIDE BY Al (Ⅲ) ORGANOMETALLIC CATALYSTS

    CHEN Xianhai; ZHANG Yifeng; SHEN Zhiquan

    1997-01-01

    Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at 62±2℃. The results showed that in-situ AlR3-H2O (R=ethyl, iso-butyl) catalysts gave higher molecular weight ((-M)w ~ 104), while Al(OR)3 catalysts gave the higher alternating copolymer structure with slightly lower molecular weight. The in-situ AlR3-H2O systems have been evaluated in more detail for the reaction which showed the optimum H2O/Al molar ratio to be 0.5. The copolymers with different composition (FSA/FEO = 36/64 to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melting point (Tm), glass transition temperature (Tg) and enthalpy of fusion (ΔHf) of these copolymers are depended on the copolymer composition and in the range of 87~ 102℃,-12 ~ -18℃, and 37 ~ 66J/g, respectively. The second heating scan of DSC also indicated that the higher alternating copolymer was more easily recrystallized. The onset decomposition temperature was more than 300℃ under nitrogen and influenced by the copolymer composition.

  10. Cultivation conditions and properties of extracellular crude lipase from the psychrotrophic fungus Penicillium chrysogenum 9'.

    Bancerz, R; Ginalska, G; Fiedurek, J; Gromada, A

    2005-06-01

    Among 97 fungal strains isolated from soil collected in the arctic tundra (Spitsbergen), Penicillium chrysogenum 9' was found to be the best lipase producer. The maximum lipase activity was 68 units mL(-1) culture medium on the fifth day of incubation at pH 6.0 and 20 degrees C. Therefore, P. chrysogenum 9' was classified as a psychrotrophic microorganism. The non-specific extracellular lipase showed a maximum activity at 30 degrees C and pH 5.0 for natural oils or at pH 7.0 for synthetic substrates. Tributyrin was found to be the best substrate for lipase, among those tested. The Km and Vmax were calculated to be 2.33 mM and 22.1 units mL(-1), respectively, with tributyrin as substrate. The enzyme was inhibited more by EDTA than by phenylmethylsulfonyl fluoride and was reactivated by Ca2+. The P. chrysogenum 9' lipase was very stable in the presence of hexane and 1,4-dioxane at a concentration of 50%, whereas it was unstable in presence of xylene.

  11. Stabilization and prolonged reactivity of aqueous-phase ozone with cyclodextrin

    Dettmer, Adam; Ball, Raymond; Boving, Thomas B.; Khan, Naima A.; Schaub, Tanner; Sudasinghe, Nilusha; Fernandez, Carlos A.; Carroll, Kenneth C.

    2017-01-01

    Recalcitrant organic groundwater contaminants, such as 1,4-dioxane, may require strong oxidants for complete mineralization. However, their efficacy for in-situ chemical oxidation (ISCO) is limited by oxidant decay and reactivity. Hydroxypropyl-β-cyclodextrin (HPβCD) was examined for its ability to stabilize aqueous-phase ozone (O3) and prolong oxidation potential through inclusion complex formation. Partial transformation of HPβCD by O3 was observed. However, HPβCD proved to be sufficiently recalcitrant, because it was only partially degraded in the presence of O3. The formation of a HPβCD:O3 clathrate complex was observed, which stabilized decay of O3. The presence of HPβCD increased the O3 half-life linearly with increasing HPβCD:O3 molar ratio. The O3 half-life in solutions increased by as much as 40-fold relative to HPβCD-free O3 solutions. Observed O3 release from HPβCD and indigo oxidation confirmed that the formation of the inclusion complex is reversible. This proof-of-concept study demonstrates that HPβCD can complex O3 while preserving its reactivity. These results suggest that the use of clathrate stabilizers, such as HPβCD, can support the development of a facilitated-transport enabled ISCO for the O3 treatment of groundwater contaminated with recalcitrant compounds.

  12. Stabilization and prolonged reactivity of aqueous-phase ozone with cyclodextrin

    Dettmer, Adam; Ball, Raymond; Boving, Thomas B.; Khan, Naima A.; Schaub, Tanner; Sudasinghe, Nilusha; Fernandez, Carlos A.; Carroll, Kenneth C.

    2017-01-02

    Recalcitrant organic groundwater contaminants, such as 1,4-dioxane, may require strong oxidants for complete mineralization. However, their efficacy for in-situ chemical oxidation (ISCO) is limited by oxidant decay and reactivity. Hydroxypropyl-β-cyclodextrin (HPβCD) was examined for its ability to stabilize aqueous-phase ozone (O3) and prolong oxidation potential through inclusion complex formation. Partial transformation of HPβCD by O3 was observed. However, HPβCD proved to be sufficiently recalcitrant, because it was only partially degraded in the presence of O3. The formation of a HPβCD:O3 clathrate complex was observed, which stabilized decay of O3. The presence of HPβCD increased the O3 half-life linearly with increasing HPβCD:O3 molar ratio. The O3 half-life in solutions increased by as much as 40-fold relative to HPβCD-free O3 solutions. Observed O3 release from HPβCD and indigo oxidation confirmed that the formation of the inclusion complex is reversible. This proof-of-concept study demonstrates that HPβCD can complex O3 while preserving its reactivity. These results suggest that the use of clathrate stabilizers, such as HPβCD, can support the development of a facilitated-transport enabled ISCO for the O3treatment of groundwater contaminated with recalcitrant compounds.

  13. Experimental and theoretical study of the products from the spontaneous dimerization of DL- and D-glyceraldehyde

    Garcia-Jimenez, Federico; Collera Zuniga, Ofelia; Cuevas, Gabriel [Universidad Nacional Autonoma de Mexico, (Mexico). Inst. de Quimica]. E-mails: fedgar@servidor.unam.mx; gecgb@servidor.unam.mx; Castells Garcia, Yolanda [Universidad Nacional Autonoma de Mexico (Mexico). Escuela Nacional Preparatoria; Cardenas, Julio [Universidad La Salle, Mexico D.F. (Mexico). Escuela de Ciencias Quimicas

    2005-05-15

    The predominant molecular structure of DL and D-glyceraldehyde has been studied with infrared and nuclear magnetic resonance spectroscopies. Both techniques show that these compounds at room temperature have a minor percentage of the aldehydic form. These studies showed that D-(+)-glyceraldehyde coexists in a minor proportion as a component of a complex mixture of diastereoisomers of the 2,5-dihydroxy-3,6-dihydroxymethyl-1,4-dioxane, while the racemic mixture is made of two main compounds. The stability of the isolated diastereoisomers is controlled by the formation of intramolecular hydrogen bonds that are formed under the control of the anomeric effect which defines the favored position for the hydroxyl group. The endo and exo-anomeric interactions have their origin in the stereo electronic interaction n{sub o} {yields} {sigma}{sup *}{sub c-o}. Using theoretical calculations at B3LYP/6-31G(d,p) level, it was possible to establish the structure of the favored conformers. (author)

  14. 稀土络合催化二氧化碳合成脂肪族聚碳酸酯%Study on synthesis of aliphatic polycarbonate from carbon dioxide by rare earth coordinated catalyst

    郭锦棠; 王新英; 许涌深; 孙经武

    2001-01-01

    利用稀土磷酸酯盐和三异丁基铝组成的催化剂催化二氧化碳和环氧氯丙烷(ECH)共聚反应,合成出新型高分子材料脂肪族聚碳酸酯(ECHCO2)。考察不同稀土元素对组成的催化剂活性和共聚物分子量的影响。同时还研究了催化剂用量、1,4-二氧六环的用量、溶剂种类、反应温度、反应时间、水量及加水方式等对该反应的影响。%The catalyst composed of rare earth phosphonate and triisobutylaluminum was used to catalyze copolymerization of CO2 and epichlorohydrin(ECH)to synthesize polymer ECHCO2.The effects of the different rare earth in catalyst on catalytic activity and molecular weight of copolymer were studied.The reaction conditions such as dosages of catalyst,1,4-dioxane and water,solvent type,reaction temperature and time,adding method were also studied.

  15. EFFECT OF SOLVENT ON THE BETA-O-4 BOND CLEAVAGE OF A LIGNIN MODEL COMPOUND BY TERT-BUTOXIDE UNDER MILD CONDITIONS

    Yuji Matsumoto

    2011-11-01

    Full Text Available The beta-O-4 bond cleavage of a non-phenolic β-O-4 type dimeric lignin model compound, 2-(2-methoxyphenoxy-1-(3,4-dimethoxyphenyl-ethanol (III, was examined in systems using potassium tert-butoxide as a base (0.5 mol/l and tert-butanol (tBuOH, dimethylsulfoxide, 1,4-dioxane, or tetrahydrofuran as a solvent. The β-O-4 bond of compound III was cleaved in any system at 30°C, and 2-methoxyphenol (II was liberated. The amount of compound II liberated was close to the quantitative yield on the basis of the amount of compound III that disappeared, except for the treatment in the t-BuOH system. The reaction rate was dependent on what solvent was used. Half-life periods for these systems were roughly about 6.0, 3.0, 0.7, and 0.2h, respectively. It seemed that the rates were very high when the polarity of the solvents was low. Two reaction products generated from the aromatic ring with two methoxyl groups of compound III, 4-acetyl-1,2-dimethoxybenzene and 3,4-dimethoxybenzoic acid, were detected in all the systems. A peculiar reaction product, 1,2-dimethoxybenzene, was detected in a fairly large quantity, only when the latter two solvents with low polarities were applied.

  16. Reverse osmosis followed by activated carbon filtration for efficient removal of organic micropollutants from river bank filtrate.

    Kegel, F Schoonenberg; Rietman, B M; Verliefde, A R D

    2010-01-01

    Drinking water utilities in Europe are faced with a growing presence of organic micropollutants in their water sources. The aim of this research was to assess the robustness of a drinking water treatment plant equipped with reverse osmosis and subsequent activated carbon filtration for the removal of these pollutants. The total removal efficiency of 47 organic micropollutants was investigated. Results indicated that removal of most organic micropollutants was high for all membranes tested. Some selected micropollutants were less efficiently removed (e.g. the small and polar NDMA and glyphosate, and the more hydrophobic ethylbenzene and napthalene). Very high removal efficiencies for almost all organic micropollutants by the subsequent activated carbon, fed with the permeate stream of the RO element were observed except for the very small and polar NDMA and 1,4-dioxane. RO and subsequent activated carbon filtration are complementary and their combined application results in the removal of a large part of these emerging organic micropollutants. Based on these experiments it can be concluded that the robustness of a proposed treatment scheme for the drinking water treatment plant Engelse Werk is sufficiently guaranteed.

  17. Development and validation of an ultra high-performance liquid chromatographic method for the determination of a diastereomeric impurity in (+)-pinoresinol diglucoside chemical reference substance.

    Song, Jing-Zheng; Cheung, Lok Man; Liu, Xin; Qiao, Chun-Feng; Zhou, Yan; Li, Song-Lin; Chen, Shi-Lin; Xu, Hong-Xi

    2010-07-01

    (+)-Pinoresinol 4,4'-di-O-beta-D-glucopyranoside ((+)-PDG) is one of the major lignans with various pharmacological activities which could be isolated from Duzhong and other plant species. In this study, a diastereomeric impurity, (-)-pinoresinol 4,4'-di-O-beta-D-glucopyranoside ((-)-PDG), the main impurity was identified in (+)-PDG chemical reference substance (CRS) and a reliable chromatographic method for rapid purity determination of (+)-PDG CRS was firstly developed. The optimal chromatographic condition was found to be using ACN/1,4-dioxane-water (2.5:6:91.5, v/v/v) as mobile phase on a Waters Acquity UPLC HSS T3 column (2.1 mm x 100 mm, 1.8 microm) with column temperature of 37 degrees C. The method was validated and applied to determine the chromatographic purity of five (+)-PDG CRS samples. The content of (-)-PDG in four commercial (+)-PDG CRS was 8.47-20.30%, whereas no (-)-PDG was detected in our in-house prepared (+)-PDG CRS in which purity was confirmed to be 99.80%. The above results confirmed that this method is fast and highly efficient for purity determination of the (+)-PDG CRS.

  18. Effects of polar and nonpolar groups on the solubility of organic compounds in soil organic matter

    Chiou, C.T.; Kile, D.E.

    1994-01-01

    Vapor sorption capacities on a high-organic-content peat, a model for soil organic matter (SOM), were determined at room temperature for the following liquids: n-hexane, 1,4-dioxane, nitroethane, acetone, acetonitrile, 1-propanol, ethanol, and methanol. The linear organic vapor sorption is in keeping with the dominance of vapor partition in peat SOM. These data and similar results of carbon tetrachloride (CT), trichloroethylene (TCE), benzene, ethylene glycol monoethyl ether (EGME), and water on the same peat from earlier studies are used to evaluate the effect of polarity on the vapor partition in SOM. The extrapolated liquid solubility from the vapor isotherm increases sharply from 3-6 wt % for low-polarity liquids (hexane, CT, and benzene) to 62 wt % for polar methanol and correlates positively with the liquid's component solubility parameters for polar interaction (??P) and hydrogen bonding (??h). The same polarity effect may be expected to influence the relative solubilities of a variety of contaminants in SOM and, therefore, the relative deviations between the SOM-water partition coefficients (Kom) and corresponding octanol-water partition coefficients (Kow) for different classes of compounds. The large solubility disparity in SOM between polar and nonpolar solutes suggests that the accurate prediction of Kom from Kow or Sw (solute water solubility) would be limited to compounds of similar polarity.

  19. Theoretical insight into oxidative decomposition of propylene carbonate in the lithium ion battery.

    Xing, Lidan; Wang, Chaoyang; Li, Weishan; Xu, Mengqing; Meng, Xuliang; Zhao, Shaofei

    2009-04-16

    The detailed oxidative decomposition mechanism of propylene carbonate (PC) in the lithium ion battery is investigated using density functional theory (DFT) at the level of B3LYP/6-311++G(d), both in the gas phase and in solvent. The calculated results indicate that PC is initially oxidized on the cathode to a radical cation intermediate, PC(*+), and then decomposes through three pathways, generating carbon dioxide CO(2) and radical cations. These radical cations prefer to be reduced on the anode or by gaining one electron from PC, forming propanal, acetone, or relevant radicals. The radicals terminate by forming final products, including trans-2-ethyl-4-methyl-1,3-dioxolane, cis-2-ethyl-4-methyl-1,3-dioxolane, and 2,5-dimethyl-1,4-dioxane. Among all the products, acetone is most easily formed. The calculations in this paper give detailed explanations of the experimental findings that have been reported in the literature and clarify the role of intermediate propylene oxide in PC decomposition. Propylene oxide is one of the important intermediates. As propylene oxide is formed, it isomerizes forming a more stabile product, acetone.

  20. Occupational exposure to airborne chemical substances in paintings conservators

    Anna Jeżewska

    2014-02-01

    Full Text Available Background: This paper presents the results of the quantitative study of the airborne chemical substances detected in the conservator's work environment. Material and Methods: The quantitative tests were carried out in 6 museum easel paintings conservation studios. The air test samples were taken at various stages of restoration works, such as cleaning, doubling, impregnation, varnishing, retouching, just to name a few. The chemical substances in the sampled air were measured by the GC-FID (gas chromatography with flame ionization detector test method. Results: The study results demonstrated that concentrations of airborne substances, e.g., toluene, 1,4-dioxane, turpentine and white spirit in the work environment of paintings conservators exceeded the values allowed by hygiene standards. It was found that exposure levels to the same chemical agents, released during similar activities, varied for different paintings conservation studios. It is likely that this discrepancy resulted from the indoor air exchange system for a given studio (e.g. type of ventilation and its efficiency, the size of the object under maintenance, and also from the methodology and protection used by individual employees. Conclusions: The levels of organic solvent vapors, present in the workplace air in the course of painting conservation, were found to be well above the occupational exposure limits, thus posing a threat to the worker's health. Med Pr 2014;65(1:33–41

  1. NEW POLY(METHACRYLATE)S CONTAINING OXIME ESTERS MOIETIES BASED ON CYCLOHEXANON AND CYCLOPENTANON

    Ibrahim Erol

    2008-01-01

    The synthesis of two new methacrylates such as 2-[(cyclohexylideneamino)oxy]-2-oxoethyl methylacrylate (CHOEMA) and 2-[(cyclopentylideneamino)oxy]-2-oxoethyl methylacrylate (CPOEMA) are described. The monomers produced from the reaction of corresponding cyclohexanone O-(2-chloroacetyl) oxime and cyclopentanone O-(2-chloroacetyl) oxime with sodium methacrylate was polymerized in 1,4-dioxane solution at 65℃ using AIBN as an initiator. The monomers and their polymers were characterized by IR, 1H- and 13C-NMR spectroscopy. The glass transition temperature of the polymers was investigated by DSC and the apparent thermal decomposition activation energies (ED) were calculated by Ozawa and multiple heating rate kinetics (MHRK) method using the Shimadzu TGA thermobalance. By using gel permeation chromatography, weight-average (Mw) and number-average (Mn) molecular weights and polydispersity indices of the polymers were determined. The antibacterial and antifungal effects of the monomers and polymers were also investigated on various bacteria and fungi. The photochemical properties of the polymers were investigated by UV and FTIR spectra.

  2. Structural and functional characterization of the CAP domain of pathogen-related yeast 1 (Pry1) protein

    Darwiche, Rabih; Kelleher, Alan; Hudspeth, Elissa M.; Schneiter, Roger; Asojo, Oluwatoyin A.

    2016-06-01

    The production, crystal structure, and functional characterization of the C-terminal cysteine-rich secretory protein/antigen 5/pathogenesis related-1 (CAP) domain of pathogen-related yeast protein-1 (Pry1) from Saccharomyces cerevisiae is presented. The CAP domain of Pry1 (Pry1CAP) is functional in vivo as its expression restores cholesterol export to yeast mutants lacking endogenous Pry1 and Pry2. Recombinant Pry1CAP forms dimers in solution, is sufficient for in vitro cholesterol binding, and has comparable binding properties as full-length Pry1. Two crystal structures of Pry1CAP are reported, one with Mg2+ coordinated to the conserved CAP tetrad (His208, Glu215, Glu233 and His250) in spacegroup I41 and the other without divalent cations in spacegroup P6122. The latter structure contains four 1,4-dioxane molecules from the crystallization solution, one of which sits in the cholesterol binding site. Both structures reveal that the divalent cation and cholesterol binding sites are connected upon dimerization, providing a structural basis for the observed Mg2+-dependent sterol binding by Pry1.

  3. Fabricating a pearl/PLGA composite scaffold by the low-temperature deposition manufacturing technique for bone tissue engineering

    Xu Mingen; Li Yanlei; Suo Hairui; Wang Qiujun; Ge Yakun; Xu Ying [Center Laboratory of Biomanufacture and Tissue Engineering, Hang Zhou Dianzi University, Hangzhou 310018 (China); Yan Yongnian; Liu Li, E-mail: xumingen@tsinghua.edu.c, E-mail: xumingen@hdu.edu.c [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education and Center of Organ Manufacturing, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2010-06-15

    Here we developed a composite scaffold of pearl/poly(lactic-co-glycolic acid) (pearl/PLGA) utilizing the low-temperature deposition manufacturing (LDM). LDM makes it possible to fabricate scaffolds with designed microstructure and macrostructure, while keeping the bioactivity of biomaterials by working at a low temperature. Process optimization was carried out to fabricate a mixture of pearl powder, PLGA and 1,4-dioxane with the designed hierarchical structures, and freeze-dried at a temperature of -40 deg. C. Scaffolds with square and designated bone shape were fabricated by following the 3D model. Marrow stem cells (MSCs) were seeded on the pearl/PLGA scaffold and then cultured in a rotating cell culture system. The adhesion, proliferation and differentiation of MSCs into osteoblasts were determined using scanning electronic microscopy, WST-1 assay, alkaline phosphatase activity assay, immunofluorescence staining and real-time reverse transcription polymerase chain reaction. The results showed that the composite scaffold had high porosity (81.98 +- 3.75%), proper pore size (micropores: <10 mum; macropore: 495 +- 54 mum) and mechanical property (compressive strength: 0.81 +- 0.04 MPa; elastic modulus: 23.14 +- 0.75 MPa). The pearl/PLGA scaffolds exhibited better biocompatibility and osteoconductivity compared with the tricalcium phosphate/PLGA scaffold. All these results indicate that the pearl/PLGA scaffolds fulfill the basic requirements of bone tissue engineering scaffold.

  4. Dielectric behaviour of some amides and formamides dissolved in nonpolar solvents under static electric field

    S Sahoo; S K Sit

    2011-08-01

    Structural and associational aspects of polar amides () like formamide, acetamide, Nmethyl acetamide (NMA), N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA) and acetanilide dissolved in the nonpolar solvent () benzene or 1,4-dioxan have been estimated from the measured static relative permittivity 0 and high-frequency permittivity ∞ at different weight fractions s of polar solute at 35°C under static electric field using Debye model of polar liquid molecule. The static dipole moments s are compared with s reported from conductivity method and theoretical theos to get exact cal $\\cdot$ theos of the molecules are predicted from the available bond angles and bond moments where difference in electron affinity exists between two adjacent atoms of a polar group due to inductive, mesomeric and electromeric effects in them. Solute–solute molecular association for NMA in benzene and solute–solvent association for other amides are ascertained to arrive at their conformational structures.

  5. NANOBIOCATALYTIC SYSTEMS BASED ON LIPASE-Fe3O4 AND CONVENTIONAL SYSTEMS FOR ISONIAZID SYNTHESIS: A COMPARATIVE STUDY

    V. M. Costa

    Full Text Available Abstract Superparamagnetic nanomaterials have attracted interest in many areas due to the high saturation magnetization and surface area. For enzyme immobilization, these properties favor the enzyme-support contact during the immobilization reaction and easy separation from the reaction mixture by use of low-cost magnetic processes. Iron oxide magnetic nanoparticles (Fe3O4, MNPs, produced by the co-precipitation method, functionalized with 3-aminopropyltriethoxysilane (APTES and glutaraldehyde (GLU, were evaluated as a solid support for Candida antarctica lipase B (CALB immobilization. The nanomagnetic derivative (11nm obtained after CALB immobilization (MNPs/APTES/GLU/CALB was evaluated as biocatalyst in isoniazide (INH synthesis using ethyl isonicotinate (INE and hydrazine hydrate (HID as substrates, in 1,4-dioxane. The results showed that MNPs/APTES/CALB had a similar performance when compared to a commercial enzyme Novozym 435, showing significant advantages over other biocatalysts, such as Rhizhomucor miehei lipase (RML and CALB immobilized on non-conventional, low-cost, chitosan-based supports.

  6. Epistemology of contaminants of emerging concern and literature meta-analysis.

    Halden, Rolf U

    2015-01-23

    A meta-analysis was conducted to inform the epistemology, or theory of knowledge, of contaminants of emerging concern (CECs). The CEC terminology acknowledges the existence of harmful environmental agents whose identities, occurrences, hazards, and effects are not sufficiently understood. Here, data on publishing activity were analyzed for 12 CECs, revealing a common pattern of emergence, suitable for identifying past years of peak concern and forecasting future ones: dichlorodiphenyltrichloroethane (DDT; 1972, 2008), trichloroacetic acid (TCAA; 1972, 2009), nitrosodimethylamine (1984), methyl tert-butyl ether (2001), trichloroethylene (2005), perchlorate (2006), 1,4-dioxane (2009), prions (2009), triclocarban (2010), triclosan (2012), nanomaterials (by 2016), and microplastics (2022 ± 4). CECs were found to emerge from obscurity to the height of concern in 14.1 ± 3.6 years, and subside to a new baseline level of concern in 14.5 ± 4.5 years. CECs can emerge more than once (e.g., TCAA, DDT) and the multifactorial process of emergence may be driven by inception of novel scientific methods (e.g., ion chromatography, mass spectrometry and nanometrology), scientific paradigm shifts (discovery of infectious proteins), and the development, marketing and mass consumption of novel products (antimicrobial personal care products, microplastics and nanomaterials). Publishing activity and U.S. regulatory actions were correlated for several CECs investigated.

  7. On the temperature dependence of amide I frequencies of peptides in solution.

    Amunson, Krista E; Kubelka, Jan

    2007-08-23

    The temperature dependence of the amide I vibrational frequencies of peptides in solution was investigated. In D2O, the amide I' bands of both an alpha-helical oligopeptide, the random-coil poly(L-lysine), and the simplest amide, N-methyl acetamide (NMA), exhibit linear frequency shifts of approximately 0.07 cm(-1)/degrees C with increasing temperature. Similar amide I frequency shifts are also observed for NMA in both polar (acetonitrile and DMSO) and nonpolar (1,4-dioxane) organic solvents, thus ruling out hydrogen-bonding strength as the cause of these effects. The experimental NMA amide I frequencies in the organic solvents can be accurately described by a simple theory based on the Onsager reaction field with temperature-dependent solvent dielectric properties and a solute molecular cavity. DFT-level calculations (BPW91/cc-pVDZ) for NMA with an Onsager reaction field confirm the significant contribution of the molecular cavity to the predicted amide I frequencies. Comparison of the computations to experimental data shows that the frequency-dependent response of the reaction field, taken into account by the index of refraction, is crucial for describing the amide I frequencies in polar solvents. The poor predictions of the model for the NMA amide I band in D2O might be due, in part, to the unknown temperature dependence of the refractive index of D2O in the mid-IR range, which was approximated by the available values in the visible region.

  8. Electrooptical Absorption Measurements (EOAM) Testify Existence of two Conformers of Prodan and Laurdan with Different Dipole Moments in Equilibrium Ground and Franck-Condon Excited State.

    Nemkovich, N A; Detert, H; Roeder, N

    2016-09-01

    The results from the electrooptical absorption measurements (EOAM) on the equilibrium ground and excited Franck-Condon state dipole moments of Prodan and Laurdan in 1,4-dioxane are presented. As follows from experiments Prodan and Laurdan in the equilibrium ground and excited Franck-Condon state have two conformers with considerably different dipole moments. The electrical dipole moments and the transition dipole moment, obtained from the short-wavelength region of the absorption spectrum are parallel. The electrical dipole moments measured at the long-wavelength spectral region are parallel to each other but not parallel to the transition dipole moment m a. The angle θ between the transition dipole moment m a and the dipole moment in the equilibrium ground state μ g of the long-wavelength conformer is about 30(0) for both probes. Obtained results evidence that donor-acceptor pairs of the short-wavelength and long-wavelength conformers are not located on the same axis. Two low-energy conformers of Prodan have been found by density functional theory (DFT) calculations, differing in the orientation of the carbonyl group towards the naphthalene system.

  9. Spectral studies of safranin-O in different surfactant solutions.

    Göktürk, Sinem; Tunçay, Melda

    2003-06-01

    The interaction of Safranin-O (SO), a cationic dye, with various surfactants viz., anionics; Sodiumdodecylsulfate (SDS) and Sodiumdodecylsulfonate (SDSo), nonionics; polyoxyethylenesorbitanmonolaurate (Tween 20) and polyoxyethylenedodecylether (Brij 35), cationic; Dodecyltrimethylammoniumbromide (DTAB) and zwitterionic; Laurylsulfobetaine (LSB) was studied spectrophotometrically as a function of surfactant concentration ranging from premicellar to postmicellar region in aqueous media in the absence and presence of cosolvents. The binding constants (K(b)) and fraction of bound SO to micelles (f), were calculated by means of Benesi-Hildebrand Equation. The binding tendency of SO to micelles followed the order as; Tween 20>Brij 35>SDS>SDSo>LSB. The presence of cosolvents, such as Methanol, Dimethylformamide (DMFA) and 1,4 Dioxan (DX) at various volume percentages, increased the CMC of both SDS and Tween 20 and at a certain concentration totally inhibited the micellization. The binding of SO to micelles decreased as the concentration of the cosolvents increased. This inhibitory effect of cosolvents on binding of SO to micelles followed the order as; Methanol>DMFA>DX.

  10. Chemoselective C-4 aerobic oxidation of catechin derivatives catalyzed by the Trametes villosa laccase/1-hydroxybenzotriazole system: synthetic and mechanistic aspects.

    Bernini, Roberta; Crisante, Fernanda; Gentili, Patrizia; Morana, Fabio; Pierini, Marco; Piras, Monica

    2011-02-04

    Catechin derivatives were oxidized in air in the presence of the Trametes villosa laccase/1-hydroxybenzotriazole (HBT) system in buffered water/1,4-dioxane as reaction medium. The oxidation products, flavan-3,4-diols and the corresponding C-4 ketones, are bioactive compounds and useful intermediates for the hemisynthesis of proanthocyanidins, plant polyphenols which provide beneficial health properties for humans. Determinations of oxidation potentials excluded that catechin derivatives could be directly oxidized by laccase Cu(II), while it resulted in the H-abstraction from benzylic positions being promptly promoted by the enzyme in the presence of the mediator HBT, the parent species producing in situ the reactive intermediate benzotriazole-N-oxyl (BTNO) radical. A remarkable and unexpected result for the laccase/HBT oxidative system has been the chemoselective insertion of the oxygen atom into the C-4-H bond of catechin derivatives. Mechanistic aspects of the oxidation reaction have been investigated in detail for the first time in order to corroborate these results. Since the collected experimental findings could not alone provide information useful to clarify the origin of the observed chemoselectivity, these data were expressly supplemented with information derived by suitable molecular modeling investigations. The integrated evaluation of the dissociation energies of the C-H bonds calculated both by semiempirical and DFT methods and the differential activation energies of the process estimated by a molecular modeling approach suggested that the observed selective oxidation at the C-4 carbon has a kinetic origin.

  11. Theoretical characterization of McReynolds' constants

    Rajko, Robert [Department of Unit Operations and Environmental Engineering, College Faculty of Food Engineering, University of Szeged, H-6701 Szeged, P.O. Box 433 (Hungary)]. E-mail: rajko@sol.cc.u-szeged.hu; Koertvelyesi, Tamas [Department of Physical Chemistry, University of Szeged, H-6701 Szeged, P.O. Box 105 (Hungary)]. E-mail: kortve@chem.u-szeged.hu; Sebok-Nagy, Krisztina [Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17 (Hungary); Goergenyi, Miklos [Department of Physical Chemistry, University of Szeged, H-6701 Szeged, P.O. Box 105 (Hungary)

    2005-12-04

    The properties of McReynolds' constants were studied by a detailed statistical/chemometric analysis. The electronic structure, geometries and hydrophobicity of the McReynolds' test compounds (benzene, 1-butanol, 2-pentanone, 1-nitropropane, pyridine, 2-methyl-2-pentanol, 1-iodobutane, 2-octyne, 1,4-dioxane and cis-hidrindane) were calculated at the level of PM3 semiempirical quantum chemical method and empirical formulas. The predominant pattern was revealed using cluster and principal component analyses (CA and PCA). Dependence of McReynolds' constants on the calculated chemical descriptors was modeled by multiple linear regression (MLR) with stepwise selections, principal component regression (PCR) and partial least-square regression (PLSR). A novel statistical approach was developed for case-and-variable selection using the PCR and PLSR methods for characterizing and modeling the polarity of 25 gas chromatography (GC) stationary phases (phthalates, adipates, sebacates, phosphates, citrates and nitrils). Highest occupied molecular orbital energy, dipole moment, averaged isotropic polarizability and the apolar solvent accessible surface area; and energy of the lowest unoccupied molecular orbital and total solvent accessible surface area were suitable to describe the McReynolds' constants based on the results obtained using Q {sup 2} and adjusted-Q {sup 2}. Six of the 10 test compounds were found to be sufficient for the description of the polarity of the columns studied.

  12. 2D simulation of transport and degradation in the River Rhine.

    Teichmann, L; Reuschenbach, P; Müller, B; Horn, H

    2002-01-01

    A simple 2D model has been developed for the simulation of mass transport and degradation of substances in the river Rhine. The model describes mass transport in the flow direction with a convective and a dispersive term. Transversal transport is described by segmenting the river and formulating a transversal exchange coefficient between the segments. Degradation can be formulated with any kinetics from first order to complex enzyme kinetics. The model was verified with monitoring data from the river Rhine. The hydrodynamic parameters such as dispersion coefficients and exchange coefficients were fitted to the conductivity, which was assumed to be non-degradable. The degradation term was fitted to ammonia values. The model was used to simulate measured concentrations of a readily (Aniline) and a poorly biodegradable substance (1,4-Dioxan) 10 m from the left river bank. It was the objective of this research program to develop a model which allows a realistic estimation of the locally and regionally predicted environmental concentration of chemical substances in the EU risk assessment scheme.

  13. Laboratory shake flask batch tests can predict field biodegradation of aniline in the Rhine.

    Toräng, Lars; Reuschenbach, Peter; Müller, Britta; Nyholm, Niels

    2002-12-01

    The aim of this study was to compare degradation rates of aniline in laboratory shake flask simulation tests with field rates in the river Rhine. The combined events of a low flow situation in the Rhine and residual aniline concentrations in the effluent from the BASF treatment plant in Ludwigshafen temporarily higher than normal, made it possible to monitor aniline at trace concentrations in the river water downstream the wastewater outlet by means of a sensitive GC headspace analytical method. Aniline was analyzed along a downstream gradient and the dilution along the gradient was calculated from measurements of conductivity, sulfate and a non-readily biodegradable substance, 1,4-dioxane. Compensating dilution, field first-order degradation rate constants downstream the discharge of BASF were estimated at 1.8 day(-1) for two different dates with water temperatures of 21.9 and 14.7 degrees C, respectively. This field rate estimate was compared with results from 38 laboratory shake flask batch tests with Rhine water which averaged 1.5 day(-1) at 15 degrees C and 2.0 day(-1) at 20 degrees C. These results indicate that laboratory shake flask batch tests with low concentrations of test substance can be good predictors of degradation rates in natural water bodies--at least as ascertained here for short duration tests with readily degradable compounds among which aniline is a commonly used reference.

  14. Real-time mass spectroscopy analysis of Li-ion battery electrolyte degradation under abusive thermal conditions

    Gaulupeau, B.; Delobel, B.; Cahen, S.; Fontana, S.; Hérold, C.

    2017-02-01

    The lithium-ion batteries are widely used in rechargeable electronic devices. The current challenges are to improve the capacity and safety of these systems in view of their development to a larger scale, such as for their application in electric and hybrid vehicles. Lithium-ion batteries use organic solvents because of the wide operating voltage. The corresponding electrolytes are usually based on combinations of linear, cyclic alkyl carbonates and a lithium salt such as LiPF6. It has been reported that in abusive thermal conditions, a catalytic effect of the cathode materials lead to the formation fluoro-organics compounds. In order to understand the degradation phenomenon, the study at 240 °C of the interaction between positive electrode materials (LiCoO2, LiNi1/3Mn1/3Co1/3O2, LiMn2O4 and LiFePO4) and electrolyte in dry and wet conditions has been realized by an original method which consists in analyzing by mass spectrometry in real time the volatile molecules produced. The evolution of specific gases channels coupled to the NMR reveal the formation of rarely discussed species such as 2-fluoroethanol and 1,4-dioxane. Furthermore, it appears that the presence of water or other protic impurities greatly influence their formation.

  15. Hierarchical polymeric scaffolds support the growth of MC3T3-E1 cells.

    Akbarzadeh, Rosa; Minton, Joshua A; Janney, Cara S; Smith, Tyler A; James, Paul F; Yousefi, Azizeh-Mitra

    2015-02-01

    Tissue engineering makes use of the principles of biology and engineering to sustain 3D cell growth and promote tissue repair and/or regeneration. In this study, macro/microporous scaffold architectures have been developed using a hybrid solid freeform fabrication/thermally induced phase separation (TIPS) technique. Poly(lactic-co-glycolic acid) (PLGA) dissolved in 1,4-dioxane was used to generate a microporous matrix by the TIPS method. The 3D-bioplotting technique was used to fabricate 3D macroporous constructs made of polyethylene glycol (PEG). Embedding the PEG constructs inside the PLGA solution prior to the TIPS process and subsequent extraction of PEG following solvent removal (1,4-dioaxane) resulted in a macro/microporous structure. These hierarchical scaffolds with a bimodal pore size distribution (300 μm) contained orthogonally interconnected macro-channels generated by the extracted PEG. The diameter of the macro-channels was varied by tuning the dispensing parameters of the 3D bioplotter. The in vitro cell culture using murine MC3T3-E1 cell line for 21 days demonstrated that these scaffolds could provide a favorable environment to support cell adhesion and growth.

  16. AMEC GEOMATRIX/ARA GROUNDWATER REMEDIAITON TRIP REPORT

    SIMMONS SA

    2008-08-07

    City of Rialto, Well No.3 Demonstration System Integration Project, and Baldwin Park Operable Unit, Baldwin Park, California. The groundwater remediation contractors are AMEC Geomatrix and ARA. The sites were visited on July 22, 2008. Fluor Hanford and the U.S. Department of Energy are currently looking at a variety of alternatives to capture carbon tetrachloride, nitrates, and other COCs from 200-ZP-l groundwater. A few of the more important objectives of our visits were to: (1) Evaluate the treatment systems being used by AMEC Geomatrix to address VOCs, perchlorate, NDMA, 1,4,-Dioxane, and 1,2,3 TCP in a drinking water source; (2) Evaluate how effective these treatment methods have been; (3) Determine the types of problems they have encountered with these treatment systems and how they addressed these problems; (4) Determine the types of secondary wastes being generated by the system; (5) Determine how clean of an operation these companies run; and (6) Determine if the site is worth being visited by DOE-RL at a later date.

  17. POLYMERIZATION OF p-DIETHYNYLBENZENE INITIATED BY Ni(C≡CC6H4C≡CH)2(PPH3)2

    Mu-jie Yang; Xiao-wei Zhan

    2001-01-01

    Homogeneous polymerization ofp-diethynylbenzene initiated by nickel acetylide Ni(C≡CC6H4C≡CH)2(PPh3)2 has been investigated in terms of different solvents, addition agents, atmosphere gases, catalyst concentrations, monomer concentrations and polymerization temperatures. The yield and catalytic efficiency approach 88% and 11.1 kg polymer/mol Ni, respectively, under the optimum conditions: [cat] = 0.01 mol/L, [M] = 1.0 mol/L, NEt3/cat (mol ratio) = 3~5, 1,4dioxane/toluene (volume ratio) = 1 and T = 25℃ for 5 h. The polymerization rate equation can be expressed as Rp = kp[M][cat]2, where kp = 0.47 L2 * mol-2 * S-1 (25 ℃ ). The overall polymerization activation energy was found to be 203 kJ * mol-1. Poly(p-diethynylbenzene) so obtained is soluble in THF, CHCl3 and toluene with weight-average molecular weights as high as 27, 100 and a rich-trans extended π-conjugated polyene chain structure with pendent groups of p-C6H4C≡CH.

  18. Synthesis of Functional Polyester Based on Polylactic Acid and Its Effect on PC12 Cells after Coupling with Small Peptides

    Na Qiang

    2016-01-01

    Full Text Available Polyesters containing functional groups are a suitable candidate matrix for cell culture in tissue engineering. Three types of semicrystalline copolymer poly(L-lactide-co-β-malic acid [P(LA-co-BMD] with pendent carboxyl groups were synthesized in this study. The functional monomer 3(S-[(benzyloxycarbonylmethyl]-1,4-dioxane-2,5-dione (BMD was synthesized using L-aspartic acid. The copolymer P(LA-co-BMD was then synthesized through ring-opening copolymerization of L-LA and BMD, with dodecanol as initiator and stannous octoate as catalyst. Copolymer structure was characterized by 1H nuclear magnetic resonance (1H NMR, gel permeation chromatography (GPC, and differential scanning calorimetry (DSC analyses. Results of 1H NMR and GPC analyses showed that the copolymers were synthesized successfully. DSC curves showed that the crystal melting peak and enthalpy decreased with increased BMD. The crystallinity of the copolymer was destroyed by the presence of the functional monomer. After deprotection, carboxyl groups were coupled with the isoleucine-lysine-valine-alanine-valine peptide through N-hydroxysuccinimide/dicyclohexylcarbodiimide method. The small peptide was beneficial to the axon growth of PC12 cells.

  19. Enthalpy characteristics of L-proline dissolution in certain water-organic mixtures at 298.15 K

    Badelin, V. G.; Smirnov, V. I.

    2017-01-01

    A thermochemical study of the processes of L-proline dissolution in aqueous solutions of acetonitrile, 1,4-dioxane, acetone, dimethyl sulfoxide, nitromethane and tetrahydrofuran at T = 298.15 K in the range of organic solvent concentrations x2 = 0-0.25 mole fractions is performed. Standard values of the enthalpies of solution and transfer of L-proline from water to mixed solvent, and the enthalpy coefficients of pairwise interactions between L-proline and molecules of organic solvents, are calculated. The effect the composition of a water-organic mixture and the structure of organic solvents have on the enthalpy characteristics of L-proline dissolution and transfer is examined. The effect the energy properties of intermolecular interactions between components of a mixed solvent has on the intermolecular interactions between L-proline and molecules of cosolvent is estimated. The correlation between the enthalpy characteristics of L-proline dissolution and electron-donor properties of organic cosolvent in aqueous solutions is determined.

  20. Polar organic solvent added to an aqueous solution changes hydrolytic property of lipase.

    Tsuzuki, Wakako; Ue, Akemi; Nagao, Akihiko

    2003-08-01

    For developing further uses of lipase as a biocatalyst, its hydrolytic activity toward some esters was investigated in a miscible solution composed of a buffer and a polar organic solvent. Twenty percent dimethylformamide, 35% dimethylsulfoxide, 15% 1,4-dioxane, 15% dimethoxyethane, and 2% diethoxyethane promoted the hydrolysis by a lipase from Rhizomucor miehei toward some hydrophobic substrates, 4-methylumbelliferyl oleate, 4-methylumbelliferyl palmitate, and monoolein. While hydrolysis by this lipase toward the substrates with a relatively weak hydrophobicity (4-metylumbelliferyl heptanoate and 4-methylumbelliferyl nanoate) was suppressed by these solvents. A fluorometric analysis showed that the polar organic solvent in the buffer induced some conformational change around a tryptophan residue of R. miehei lipase. In addition to the influence of the miscible solvent on the solubility of the substrates, the conformational change of the protein induced by the miscible solvent would also affect the reactive properties of the lipase. Adding a polar organic solvent to an aqueous solution will be an efficient method for changing hydrolytic performance of lipases.

  1. Phosphazene-catalyzed ring-opening polymerization of ε-caprolactone: Influence of solvents and initiators

    Alamri, Haleema

    2014-01-01

    Phosphazene base (t-BuP2) catalysed metal-free ring-opening polymerization of ε-caprolactone (ε-CL) at room temperature with various protic initiators in different solvents was investigated. The polymerization proceeded, in most cases, in a controlled manner to afford poly(ε-caprolactone) with low dispersities and expected molecular weights. Kinetic studies showed that when a primary alcohol was used as an initiator the polymerization rate in different solvents followed the order of dichloromethane ≫ toluene > 1,4-dioxane ≈ tetrahydrofuran. Extremely fast polymerization of l-lactide (LLA), which was added as a second monomer, was observed in different solvents giving rise to poly(ε-caprolactone)-b- poly(l-lactide) diblock copolymers with neat PLLA blocks despite incomplete conversion of ε-CL. The dependence of polymerization rate on the concentrations of ε-CL and t-BuP2 was also revealed. In addition to primary alcohol, the feasibility of using other protic initiators, such as secondary alcohol (either on a small molecule or a polymer chain-end), (aliphatic/aromatic) amide, carboxylic acid, phenol and thiophenol, was also investigated. These studies provided important information for designing a metal-free route towards polyester-based (bio)materials. © 2014 the Partner Organisations.

  2. Picosecond dynamics of proton transfer of a 7-hydroxyflavylium salt in aqueous-organic solvent mixtures.

    Freitas, Adilson A; Quina, Frank H; Maçanita, António A L

    2011-10-13

    The intermediacy of the geminate base-proton pair (A*···H(+)) in excited-state proton-transfer (ESPT) reactions (two-step mechanism) has been investigated employing the synthetic flavylium salt 7-hydroxy-4-methyl-flavylium chloride (HMF). In aqueous solution, the ESPT mechanism involves solely the excited acid AH(+)* and base A* forms of HMF as indicated by the fluorescence spectra and double-exponential fluorescence decays (two species, two decay times). However, upon addition of either 1,4-dioxane or 1,2-propylene glycol, the decays become triple-exponential with a term consistent with the presence of the geminate base-proton pair A*···H(+). The geminate pair becomes detectable because of the increase in the recombination rate constant, k(rec), of (A*···H(+)) with increasing the mole fraction of added organic cosolvent. Because the two-step ESPT mechanism splits the intrinsic prototropic reaction rates (deprotonation of AH(+)*, k(d), and recombination, k(rec), of A*···H(+)) from the diffusion controlled rates (dissociation, k(diss), and formation, k(diff)[H(+)], of A*···H(+)), the experimental detection of the geminate pair provides a wealth of information on the proton-transfer reaction (k(d) and k(rec)) as well as on proton diffusion/migration (k(diss) and k(diff)).

  3. Photoinduced intramolecular charge transfer of sodium 4-(N,N-dimethylamino)benzenesulfonate

    林丽榕; 江云宝

    2000-01-01

    A new dual fluorescent N,N-dimethylaniline derivative, sodium 4-(N,N-dimethylamino)-benzenesulfonate (SDMAS), is reported. In SDMAS, the electron acceptor is linked to the phenyl ring via a sulfur atom at the para-position of the electron donor. It was found that SDMAS emits dual fluorescence only in highly polar solvent water but not in organic solvents such as formamide, methanol and acetonitrile. In organic solvents only a single-band emission at ca.360 nm was observed in the short wavelength region. The dual fluorescence of SDMAS in water was found at 365 and 475 nm, respectively. Introduction of organic solvent such as ethanol, acetonitrile, and 1,4-dioxane into aqueous solution of SDMAS leads to blue-shift and quenching of the long-wavelength emission. Measurements of steady-state and picosecond time-resolved fluorescence indicate that the long wavelength fluorescence is emitted from a charge transfer (CT) state that is populated from the locally excited (LE) state, with the latter giving off the

  4. Development of surrogate correlation models to predict trace organic contaminant oxidation and microbial inactivation during ozonation.

    Gerrity, Daniel; Gamage, Sujanie; Jones, Darryl; Korshin, Gregory V; Lee, Yunho; Pisarenko, Aleksey; Trenholm, Rebecca A; von Gunten, Urs; Wert, Eric C; Snyder, Shane A

    2012-12-01

    The performance of ozonation in wastewater depends on water quality and the ability to form hydroxyl radicals (·OH) to meet disinfection or contaminant transformation objectives. Since there are no on-line methods to assess ozone and ·OH exposure in wastewater, many agencies are now embracing indicator frameworks and surrogate monitoring for regulatory compliance. Two of the most promising surrogate parameters for ozone-based treatment of secondary and tertiary wastewater effluents are differential UV(254) absorbance (ΔUV(254)) and total fluorescence (ΔTF). In the current study, empirical correlations for ΔUV(254) and ΔTF were developed for the oxidation of 18 trace organic contaminants (TOrCs), including 1,4-dioxane, atenolol, atrazine, bisphenol A, carbamazepine, diclofenac, gemfibrozil, ibuprofen, meprobamate, naproxen, N,N-diethyl-meta-toluamide (DEET), para-chlorobenzoic acid (pCBA), phenytoin, primidone, sulfamethoxazole, triclosan, trimethoprim, and tris-(2-chloroethyl)-phosphate (TCEP) (R(2) = 0.50-0.83) and the inactivation of three microbial surrogates, including Escherichia coli, MS2, and Bacillus subtilis spores (R(2) = 0.46-0.78). Nine wastewaters were tested in laboratory systems, and eight wastewaters were evaluated at pilot- and full-scale. A predictive model for OH exposure based on ΔUV(254) or ΔTF was also proposed.

  5. Copolymers of N-(4-bromophenyl-2-methacrylamide with 2-hydroxyethyl methacrylate

    2007-09-01

    Full Text Available The radical-initiated copolymerization of N-(4-bromophenyl-2-methacrylamide (BrPMAAm with 2-hydroxyethylmethacrylate (HEMA was carried out in 1,4-dioxane solution at 70°C using 2,2’-azobisisobutyronitrile (AIBN as an initiator with different monomer-to-monomer ratios in the feed. The copolymers were characterized by FTIR, 1H- and 13C-NMR spectral studies. Gel permeation chromatography was employed for estimating the weight average (Mw and number average (Mn molecular weights and polydispersity index (PDI of the copolymers. The copolymer composition was evaluated by nitrogen content (N for BrPMAAm-units in polymers, which allowed the determination of reactivity ratios. Monomer reactivity ratios for BrPMAAm (M1-HEMA (M2 pair were determined by the application of conventional linearization methods such as Fineman-Ross (F-R, Kelen-Tüdõs (KT and Extended Kelen-Tüdõs (EKT and a nonlinear error invariable model method using a computer program RREVM. The characterizations were done thermogravimetric analysis (TGA. The antimicrobial effects of polymers were also tested on various bacteria, and yeast.

  6. Conventional and atom transfer radical copolymerization of phenoxycarbonylmethyl methacrylate-styrene and thermal behavior of their copolymers

    2007-08-01

    Full Text Available The atom transfer radical polymerization (ATRP of phenoxycarbonylmethyl methacrylate (PCMMA with styrene (St were performed in bulk at 110°C in the presence of ethyl 2-bromoacetate, cuprous(Ibromide (CuBr, and N,N,N’,N”,N”-pentamethyldiethyltriamine. Also, a series conventional free-radical polymerization (CFRP of PCMMA and styrene were carried out in the presence of 2,2’-azobisisobutyronitrile in 1,4-dioxane solvent at 60°C. The structure of homo and copolymers was characterized by IR, 1H and 13C-NMR techniques. The composition of the copolymers was calculated by 1H-NMR spectra. The average-molecular weight of the copolymers were investigated by Gel Permeation Chromatography (GPC. For copolymerization system, their monomer reactivity ratios were obtained by using both Kelen-Tüdõs and Fineman-Ross equations. Thermal analysis measurements of homo- and copolymers prepared CFRP and ATRP methods were measured by TGA-50 and DSC-50. Blends of poly(PCMMA and poly(St obtained via ATRP method have been prepared by casting films from dichlorormethane solution. The blends were characterized by differential scanning calorimetry. The initial decomposition temperatures of the resulting copolymers increased with increasing mole fraction of St.

  7. Tautomerism of 4-hydrazinoquinazolines: vibrational spectra and computational study

    Tetiana Yu. Sergeieva

    2014-03-01

    Full Text Available The tautomerism of 4-hydrazinoquinazoline and its derivatives was investigated. Geometry and thermodynamic parameters were computed theoretically using Gaussian 03 software. All calculations were performed at the MP2 level of theory using the standard 6-31G(d basis. Energetics and relative stabilities of tautomers were compared and analyzed in a gas phase. The effect of solvents (1,4-dioxane, acetic acid, ethanol and water on the tautomeric equlibria was evaluated using PCM. It was determined that solvents induced slight changes in the relative stability. In all cases 4-hydrazinoquinazoline exists predominantly as the amino form. The variation of dipole moments was studied. The anharmonic vibrational wavenumbers for unsubstituted 4-hydrazinoquinazoline were calculated at MP2/6-31G(d level and compared with experimental data. The modes of IR spectra were assigned. The calculated herein wavenumbers and intensities of amino form are in good agreement with those observed experimentally.      

  8. Role of intermolecular interaction in crystal packing: A competition between halogen bond and electrostatic interaction

    Chen, Peng-Yuan; Zhang, Lin; Zhu, Shun-Guan; Cheng, Guang-Bin

    2017-03-01

    To investigate the competition between halogen bond and electrostatic interaction and their influence on the crystal packing, four novel solvates of 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) and 1,3,5-tribromo-2,4,6-trinitrobenzene (TBTNB) were synthesized while the intermolecular forces and the contribution of each interaction were analyzed quantitatively. The electrostatic interaction is the main link between TCTNB, TBTNB and 1,4-dioxane respectively, while π-π interaction dominates in these two solvates of TCTNB/1,4-dimethylbenzene (PX) and TCTNB/mesitylene. The solvate interaction changes and varieties were illuminated by Hirshfeld surface analysis, and the group contributions were illustrated respectively. Molecular electrostatic potential surface (MEPs) with density functional theory (DFT) calculation was performed to compare the relative strength of electrostatic interaction and halogen bond. The result shows that MEPs can be used as a descriptor for determining the most possible intermolecular interaction under certain circumstances. The study presented here may provide the guidance for the design and synthesis of the complex with desired properties.

  9. Solvated crystals based on [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) with the hexagonal structure and their phase transformation.

    Zheng, Lidong; Han, Yanchun

    2012-02-09

    This work focuses on the structural exploration of micro-sized crystals based on a well-known methanofullerene, [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). We have succeeded in producing PCBM crystals with the hexagonal symmetry through the liquid-liquid interfacial precipitation (LLIP) method. We found that smaller but more regular PCBM crystals tend to form in the oversaturated PCBM solutions with solvents of lower solubility for PCBM, such as tetrahydrofuran (THF) and 1,4-dioxane. The structure of the produced crystals also shows a dependence on the solvents, which can be attributed to the incorporation of different solvent molecules into PCBM crystals. Under thermal annealing, for the first time, we have observed a crystalline to crystalline phase transformation of these hexagonal PCBM crystals. Along with the phase transformation, the morphology of the crystals has also been transformed from the hexagon to long needles. In addition, the needlelike crystals arrange themselves with a relative angle of 60° to each other, which implies an intrinsic structural correlation between needlelike and hexagonal crystals.

  10. The proton affinities of saturated and unsaturated heterocyclic molecules

    Kabli, Samira; van Beelen, Eric S. E.; Ingemann, Steen; Henriksen, Lars; Hammerum, Steen

    2006-03-01

    The proton affinities derived from G3-calculations of 23 five-membered ring heteroaromatic molecules agree well with the experimentally determined values available in the literature. The calculated local proton affinities show that the principal site of protonation of the heteroaromatic compounds examined is an atom of the ring, carbon when there is only one heteroatom in the ring, and nitrogen where there are two or more heteroatoms. The experimental proton affinities of non-aromatic cyclic ethers, amines and thioethers are also in excellent agreement with the calculated values, with two exceptions (oxetane, N-methylazetidine). The literature proton affinities of the four simple cyclic ethers, oxetane, tetrahydrofuran, tetrahydropyran and oxepane were confirmed by Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry, in order to examine the disagreement between the values predicted by extrapolation or additivity for tetrahydrofuran and tetrahydropyran and those determined by experiment and by calculation. The proton affinity differences between the pairs tetrahydropyran/1,4-dioxane, piperidine/morpholine and related compounds show that introduction of an additional oxygen atom in the ring considerably lowers the basicity.

  11. Synthesis and Characterization of Periodate-Oxidized Polysaccharides: Dialdehyde Xylan (DAX).

    Amer, Hassan; Nypelö, Tiina; Sulaeva, Irina; Bacher, Markus; Henniges, Ute; Potthast, Antje; Rosenau, Thomas

    2016-09-12

    The cleavage of the C2-C3 bond in the building units of 1 → 4-linked polysaccharides by periodate formally results in two aldehyde units, which are present in several masked forms. The structural elucidation of such polysaccharide dialdehydes remains a big challenge. Since polysaccharide derivatives are increasingly applied in materials technology, unveiling the exact structure is of utmost importance. To address this issue for xylan, dialdehyde xylan (DAX, oxidation degree of 91.5%) has been synthesized as water-soluble polymer. The ATR-FTIR spectrum of DAX showed free aldehyde to be absent and exhibited a characteristic absorption at 858 cm(-1) related to hemiacetal groups. By a combination of 1D and 2D NMR techniques, it was confirmed that oxidized xylan is present as poly(2,6-dihydroxy-3-methoxy-5-methyl-3,5-diyl-1,4-dioxane). Based on GPC analysis, the DAX polymer shows a slightly lower molar mass (6.6 kDa) compared to the starting material (7.7 kDa) right after oxidation, and degraded further after one month of storage in 0.1 M NaCl solution (4.3 kDa). The oxidized xylan demonstrated lower thermal stability upon TGA analysis and a greater amount of residual char (20.6%) compared to the unmodified xylan (13.7%).

  12. Preparation and properties of cellulose triacetate forward osmosis membrane%三乙酸纤维素正渗透膜的制备与性能

    解利昕; 辛婧; 解奥

    2014-01-01

    Cellulose triacetate based membranes for forward osmosis were prepared by immersion precipitation. The polymer solution consisted of cellulose triacetate as the membrane material, 1,4-dioxane and acetone as solvent,methanol and lactic acid as additives. Casting composition and preparation conditions-1,4-dioxane/acetone ratio,lactic acid content,evaporation time,casting thickness and annealing temperature-were tested for their effects on membrane performance. The optimized membrane showed 14.10L/(m2·h) water flux and 0.031mol/(m2·h) reverse solute flux using a feed solution of pure water and draw solution of 0.56mol/L CaCl2. When 0.1mol/L NaCl was used as the feed solution and 4mol/L glucose was used as the draw solution,water flux was above 5L/(m2·h) and rejection for NaCl was above 99%. The optimized membrane had a more hydrophilic surface, higher water flux,higher salt resistance and better membrane performance than the HTI membrane.%以三乙酸纤维素(CTA)为膜材料,1,4-二氧六环、丙酮为溶剂,甲醇、乳酸为添加剂,采用相转换法制备了三乙酸纤维素正渗透膜。研究了不同1,4-二氧六环/丙酮配比、添加剂乳酸含量、挥发时间、膜厚度、热处理温度条件下正渗透膜性能的变化规律。研究表明,当采用纯水为原料液,0.56mol/L CaCl2为汲取液时,优化制备的CTA正渗透膜的水通量达到14.10L/(m2·h),溶质反扩散量为0.031mol/(m2·h);采用0.1mol/L NaCl为原料液,4mol/L葡萄糖为汲取液时,优化制备的CTA正渗透膜的水通量保持在5L/(m2·h)以上,对NaCl的截留率大于99%。CTA正渗透膜相比于HTI膜,具有较高的亲水性、水通量、截留率,稳定性更好。

  13. Dithio- and Diselenophosphinate Thorium(IV) and Uranium(IV) Complexes: Molecular and Electronic Structures, Spectroscopy, and Transmetalation Reactivity.

    Behrle, Andrew C; Kerridge, Andrew; Walensky, Justin R

    2015-12-21

    We report a comparison of the molecular and electronic structures of dithio- and diselenophosphinate, (E2PR2)(1-) (E = S, Se; R = (i)Pr, (t)Bu), with thorium(IV) and uranium(IV) complexes. For the thorium dithiophosphinate complexes, reaction of ThCl4(DME)2 with 4 equiv of KS2PR2 (R = (i)Pr, (t)Bu) produced the homoleptic complexes, Th(S2P(i)Pr2)4 (1S-Th-(i)Pr) and Th(S2P(t)Bu2)4 (2S-Th-(t)Bu). The diselenophosphinate complexes were synthesized in a similar manner using KSe2PR2 to produce Th(Se2P(i)Pr2)4 (1Se-Th-(i)Pr) and Th(Se2P(t)Bu2)4 (2Se-Th-(t)Bu). U(S2P(i)Pr2)4, 1S-U-(i)Pr, could be made directly from UCl4 and 4 equiv of KS2P(i)Pr2. With (Se2P(i)Pr2)(1-), using UCl4 and 3 or 4 equiv of KSe2P(i)Pr2 yielded the monochloride product U(Se2P(i)Pr2)3Cl (3Se-U(iPr)-Cl), but using UI4(1,4-dioxane)2 produced the homoleptic U(Se2P(i)Pr2)4 (1Se-U-(i)Pr). Similarly, the reaction of UCl4 with 4 equiv of KS2P(t)Bu2 yielded U(S2P(t)Bu2)4 (2S-U-(t)Bu), whereas the reaction with KSe2P(t)Bu2 resulted in the formation of U(Se2P(t)Bu2)3Cl (4Se-U(tBu)-Cl). Using UI4(1,4-dioxane)2 and 4 equiv of KSe2P(t)Bu2 with UCl4 in acetonitrile yielded U(Se2P(t)Bu2)4 (2Se-U-(t)Bu). Transmetalation reactions were investigated with complex 2Se-U-(t)Bu and various CuX (X = Br, I) salts to yield U(Se2P(t)Bu2)3X (6Se-U(tBu)-Br and 7Se-U(tBu)-I) and 0.25 equiv of [Cu(Se2P(t)Bu2)]4 (8Se-Cu-(t)Bu). Additionally, 2Se-U-(t)Bu underwent transmetalation reactions with Hg2F2 and ZnCl2 to yield U(Se2P(t)Bu2)3F (6) and U(Se2P(t)Bu2)3Cl (4Se-U(tBu)-Cl), respectively. The molecular structures were analyzed using (1)H, (13)C, (31)P, and (77)Se NMR and IR spectroscopy and structurally characterized using X-ray crystallography. Using the QTAIM approach, the electronic structure of all homoleptic complexes was probed, showing slightly more covalent bonding character in actinide-selenium bonds over actinide-sulfur bonds.

  14. Thin nanostructured crystalline TiO{sub 2} films and their applications in solar cells

    Cheng Yajun

    2007-06-15

    Research on thin nanostructured crystalline TiO{sub 2} films has attracted considerable interests because of their intriguing physical properties and potential applications in photovoltaics. Nanostructured TiO{sub 2} film plays an important role in the TiO{sub 2} based dye-sensitized solar cells because they act as a substrate for the adsorption of dye molecules and a matrix for the transportation of electrons as well. Thus they can influence the solar cell performance significantly. Consequently, the control of the morphology including the shape, size and size distribution of the TiO{sub 2} nanostructures is critical to tune and optimize the performance of the solar cells. To control the TiO{sub 2} morphology, a strategy using amphiphilic block copolymer as templating agent coupled with sol-gel chemistry has been applied. Especially, a good-poor solvent pair induced phase separation process has been developed to guide the microphase separation behavior of the block copolymers. The amphiphilic block copolymers used include polystyrene-block-poly (ethylene oxide) (PS-b-PEO), poly (methyl methacrylate)-block-poly (ethylene oxide) (PMMA-b-PEO), and poly (ethylene oxide)-block-polystyrene-block-poly (ethylene oxide) (PEO-b-PS-b-PEO). The block copolymer undergoes a good-poor-solvent pair induced phase separation in a mixed solution of 1, 4-dioxane or N, N-dimethyl formamide (DMF), concentrated hydrochloric acid (HCl) and Titanium tetraisopropoxide (TTIP). Specifically, in the system of PS-b-PEO, a morphology phase diagram of the inorganic-copolymer composite films was mapped by adjusting the weight fractions among 1, 4-dioxane, HCl, and TTIP in solution. The amorphous TiO{sub 2} within the titania-block copolymer composite films was crystallized by calcination at temperatures above 400 C, where the organic block copolymer was simultaneously burned away. This strategy is further extended to other amphiphilic block copolymers of PMMA-b-PEO and PEO-b-PS-b-PEO, where the

  15. 毛细管气相色谱法测定佐米曲普坦中6种残留溶剂量%Determination of 6 Residual Organic Solvents in Zolmitriptan by Capillary Gas Chromatography

    谢华; 刘峰; 周振兴

    2012-01-01

    目的:建立佐米曲普坦原料药中6种残留有机溶剂(甲醇、异丙醇、二氯甲烷、乙酸乙酯、二氧六环、甲苯)量的测定方法.方法:采用气相色谱法.色谱柱为Agilent DB-624毛细管柱,载气为氮气,氢火焰离子化检测器,程序升温,进样口温度为200℃,检测器温度为250℃,分流直接进样,外标法计算残留溶剂的量.结果:甲醇、异丙醇、二氯甲烷、乙酸乙酯、二氧六环、甲苯检测浓度的线性范围分别为9.07× 10-2~4.54、9.92× 10-2~4.96、1.35× 10-2~0.68、9.54×10-2~4.77、8.33×10-3~0.42、1.77×10-2~0.88 mg·nL-1(r=0.996 9~0.998 9);平均回收率为97.53%~103.49%,RSD均≤1.35%.结论:本方法简单准确、灵敏度好,可用于控制佐米曲普坦原料药中残留溶剂量.%OBJECTIVE: To develop a method for the determination of 6 residual organic solvents (methanol, isopropanol, methylene chloride, ethyl acetate, 1, 4-dioxane, methylbenzene) in zolmitriptan. METHODS: GC method was adopted. The determination was performed on a Agilent DB-624 capillary column with FID detector. The carrier gas was nitrogen gas. The injector temperature was 200 ℃ and the detector temperature was 250 ℃ by temperature programming. Through direct splitting sample introduction, the content of residual solvents was calculated by external standard method. RESULTS: The linear ranges of methanol, isopropanol, methylene chloride, ethyl acetate, 1,4-dioxane, methylbenzene were 9.07×10-2~4.54, 9.92×10-2~4.96, 1.35×10-2~ 0.68, 9.54×10-2~4.77, 8.33×10-3~0.42, 1.77×10-2~0.88 mg·mL-1 (r=0.996 9-0.998 9). The average recoveries were 97.53%~103.49% (all RSD≤1.35%). CONCLUSION: The method is simple, accurate and sensitive, and can be used for the detection of residual organic solvents in zolmitriptan.

  16. A Systematic Approach to Evaluate Herb-Drug Interaction Mechanisms: Investigation of Milk Thistle Extracts and Eight Isolated Constituents as CYP3A Inhibitors

    Brantley, Scott J.; Graf, Tyler N.; Oberlies, Nicholas H.

    2013-01-01

    Despite increasing recognition of potential untoward interactions between herbal products and conventional medications, a standard system for prospective assessment of these interactions remains elusive. This information gap was addressed by evaluating the drug interaction liability of the model herbal product milk thistle (Silybum marianum) with the CYP3A probe substrate midazolam. The inhibitory effects of commercially available milk thistle extracts and isolated constituents on midazolam 1′-hydroxylation were screened using human liver and intestinal microsomes. Relative to vehicle, the extract silymarin and constituents silybin A, isosilybin A, isosilybin B, and silychristin at 100 μM demonstrated >50% inhibition of CYP3A activity with at least one microsomal preparation, prompting IC50 determination. The IC50s for isosilybin B and silychristin were ∼60 and 90 μM, respectively, whereas those for the remaining constituents were >100 μM. Extracts and constituents that contained the 1,4-dioxane moiety demonstrated a >1.5-fold shift in IC50 when tested as potential mechanism-based inhibitors. The semipurified extract, silibinin, and the two associated constituents (silybin A and silybin B) demonstrated mechanism-based inhibition of recombinant CYP3A4 (KI, ∼100 μM; kinact, ∼0.20 min−1) but not microsomal CYP3A activity. The maximum predicted increases in midazolam area under the curve using the static mechanistic equation and recombinant CYP3A4 data were 1.75-fold, which may necessitate clinical assessment. Evaluation of the interaction liability of single herbal product constituents, in addition to commercially available extracts, will enable elucidation of mechanisms underlying potential clinically significant herb-drug interactions. Application of this framework to other herbal products would permit predictions of herb-drug interactions and assist in prioritizing clinical evaluation. PMID:23801821

  17. Investigation of the factors influencing the preparation process of cellulose triacetate forward osmosis membrane%三醋酸纤维素正渗透膜制备过程中影响因素的研究

    刘蕾蕾; 王铎; 汪锰; 高从堦

    2011-01-01

    Cellulose triacetate forward osmosis membrane was prepared by phase inversion method. The polymer solution consisted of cellulose triacetate as the membrane material, 1, 4-dioxane and acetone as solvent, and lactic acid as additives. The effects of support materials, solvent evaporation time and the additive content on the membrane performance were investigated. 0. 1 mol/L NaCl was used as the feed solution and 4 mol/L glucose was used as the draw solution. The water flux was between 6 and 7 L/(m2 · h) and the rejection for NaCl was above 95%.%以三醋酸纤维素为膜材料,以1,4-二氧六环和丙酮为溶剂,乳酸为添加剂.采用相转化法制备三醋酸纤维素正渗透膜.研究了不同支撑材料以及膜制备过程中溶剂挥发时间和添加剂的含量对正渗透膜性能的影响.结果表明,在原料液为0.1 mol/L NaCl,汲取液为4 mol/L葡萄糖,原料液面向分离层,室温的测试条件下,采用180目(80 μm)的筛网为支撑体材料,挥发时间为180 s,乳酸含量为6.6%所制备的三醋酸纤维素正渗透膜的水通量为6~7 L/(m2·h),NaCl截留率在95%以上.

  18. Combined use of titration calorimetry and spectrofluorimetry for the screening of the acidity of solid catalysts in different liquids

    Gervasini, Antonella, E-mail: antonella.gervasini@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano, via Camillo Golgi, 19, 20133 Milano (Italy); Auroux, Aline, E-mail: aline.auroux@ircelyon.univ-lyon1.fr [Université Lyon 1, CNRS, UMR 5256, Institut de Recherches sur la Catalyse et l‘Environnement de Lyon (IRCELYON), 2 Avenue A. Einstein, 69626 Villeurbanne (France)

    2013-09-10

    Graphical abstract: Measurements of acidity of oxides of catalytic importance in various liquids open the possibility to know their effective acidity, which is related with their activity in liquid-heterogeneous catalysis. Titration-calorimetry alone or in connection with spectrofluorimetry is efficient for this scope. - Highlights: • Measurements of acidity of oxides of catalytic importance in various liquids. • Titration-calorimetry alone or in connection with spectrofluorimetry is efficient for this scope. • Effective acidities are expressed by given sample in various liquids. • Nb-containing samples are able to maintain acidity in protic liquids. - Abstract: The effective acid and base surface properties of selected acidic and basic samples of catalytic interest (alumina, titania, zirconia, silica–alumina, niobium oxide, niobium phosphate, boron nitride, and hydrotalcite) were measured by titration with basic and acidic molecular probes (aniline, 2-phenylethylamine, and phenol) in various liquids (cyclohexane, 1,4-dioxane, isopropanol, n-decane, and toluene) with different polar and protic characteristics. The combined use of a reaction calorimeter and a spectrofluorimeter has been performed. The set-up of the coupled technique and the most interesting results are shown here. The study confirmed that the acid–base properties of solids are deeply affected by the nature and properties of the liquid surrounding the samples. Few oxides are able to maintain their surface acidity in highly polar and protic solvents, in particular whose containing niobium. In general, the solvating and coordinative ability of the most polar and protic liquids caused remarkable loss of acidity/basicity of the oxide surfaces.

  19. SYNTHESIS AND CHARACTERIZATION OF AN ACRYLATE POLYMER CONTAINING CHLORINE-1,3-DIOXALANE GROUPS IN SIDE CHAINS

    Zulfiye (I)lter; Ferhat Alhanl(ι); Fatih Do(g)an; (I)smet Kaya

    2012-01-01

    Poly[2-(4-chlorophenyl)-l,3-dioxolan-4-yl]methyl acrylate,poly(CPhDMA),was synthesized with radical polymerization process using 2,2′-azobisisobutyronitrile as radical initiator in 1,4-dioxane at 60℃.The structure of poly(CPhDMA) was confirmed by means of UV-Vis,FT-IR,1H-NMR,and 13C-NMR spectral techniques.The molecular weight distribution values of the polymer were determined with gel permeation chromatography (GPC).The number-average molecular weight (Mn),weight-average molecular weight (Mw) and polydispersity index (PDI) values of poly(CPhDMA) were determined to be 10300,21600 and 2.097,respectively.The thermal degradation kinetics of the polymer was investigated by using TG/DTG-DTA and DSC analyses at different heating rates in dynamic nitrogen atmosphere.The apparent activation energy values obtained by Flynn-Wall-Ozawa and Friedman methods were found to be 91.68 and 85.23 kJ mol-1,respectively,for thermal decomposition of poly(CPhDMA).Also,the thermal degradation activation energy value of poly(CPhDMA) was calculated by using the Kissinger method based on the DTG,DTA and DSC data.Then the mechanism function of it was determined by master plots method.Finally,electrical and optical properties of poly(CPhDMA) were determined by four-point probe and UV-Vis techniques,respectively.

  20. Polymeric cobalt porphyrin complex film catalytic oxidation of styrene with molecular oxygen%聚卟啉钴配合物膜催化氧化苯乙烯性能研究

    李晓东; 朱元成; 王小芳; 王晓峰

    2013-01-01

    利用聚卟啉金属钴配合物[PCo(Ⅱ)TPP]在一定条件下催化分子氧氧化苯乙烯,氧化产物以苯甲醛(1)和1,2-环氧苯乙烷(2)为主,比较了小分子钴卟啉配合物TPPCo(Ⅱ)和PCo(Ⅱ)TPP,发现PCo(Ⅱ)TPP具有更高的催化活性,考察了影响氧化反应的反应温度、反应时间、溶剂和重复使用性等因素.结果表明,较为理想的反应温度和时间为90℃和9h,非极性的溶剂1,4-二氧六环能提高苯乙烯的转化率和产物选择性,而且催化剂PCo(Ⅱ)-TPP在重复使用5次后催化活性没有明显的下降.%Styrene oxidation using polymeric metalloporphyrin complexes [ PCo ( II) TPP ] catalyst in the presence of molecular oxygen were studied. The benzaldhyde (1) and styrene oxide (2) were obtained as the major products. Compared with the cobalt porphyrin complex TPPCo( E ) and PCo( E )TPP,the PCo( II )TPP has the higher catalytic activity,the effect of reaction temperature,reaction time,solvents and reusability on the oxidation were also investigated. The results showed that the conversion and selectivity to styrene were improved under reaction temperature at 90 ℃ , reaction time at 9 h and unpolar solvent (1,4-dioxane) was added to reaction system. Furthermore, the catalyst PCo( E )TPP could be efficiently reused five times.

  1. Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

    Abaji Gaikwad

    2011-01-01

    The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone (HAA) containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions (10^-2 to 10^-4 mol.L^-1) in the source solution, mixed solvent composition [for exampl, e, acetylacetone, (2,4-pentanedione), (HAA) 20% (by volume), 1,4-dioxane 10% to 60% and HC1 0.25 to 2 mol.L^-1] in the receiving phase and stirring speed (50-130 r.min ) of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction (CIESE) was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be(II), Ti(IV), AI(III) Ca(II), Mg(II), K (I), La(III) and Y(III) was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

  2. New reversed phase dispersive liquid-liquid microextraction method for the determination of phenolic compounds in virgin olive oil by rapid resolution liquid chromathography with ultraviolet-visible and mass spectrometry detection.

    Godoy-Caballero, M P; Acedo-Valenzuela, M I; Galeano-Díaz, T

    2013-10-25

    The determination of phenolic compounds in virgin olive oil using a new reversed phase dispersive liquid-liquid microextraction (RP-DLLME) procedure coupled with rapid resolution liquid chromatography-diode array and mass spectrometry detection (RRLC-DAD-MS) have been performed. A rapid resolution Zorbax Eclipse XDB-C18 column (4.6 mm × 50 mm, 1.8 μm particle size) has been employed and eighteen phenolic compounds belonging to different families have been identified and quantified spending a total time of 26 and 13 min with UV-visible and MS detection, respectively. Response surface methodology has been applied by means of a central composite design for the optimization of the variables affecting the extraction procedure searching for the best recovery. The validation of the methods was performed through the establishment of the external standard calibration curves and the analytical figures of merit. Limits of detection ranging from 10 to 400 ng mL(-1) and 1 to 200 ng mL(-1) were achieved using UV-visible and MS detection, respectively. The extraction of phenolic compounds from virgin olive oil was performed in a simple and rapid way by RP-DLLME with ethanol:water 60:40 (v/v) as extracting solvent and 1,4-dioxane as disperser solvent. The quantification of the phenolic compounds in virgin olive oils from different olive varieties was carried out by means of the standard addition method and, finally the procedure for the sample treatment was validated using the well established solid phase extraction procedure with Diol cartridges.

  3. Phase behavior and molecular dynamics simulation studies of new aqueous two-phase separation systems induced by HEPES buffer.

    Taha, Mohamed; Khoiroh, Ianatul; Lee, Ming-Jer

    2013-01-17

    Here, for the first time, we show that with addition of a biological buffer, 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), into aqueous solutions of tetrahydrofuran (THF), 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone, the organic solvent can be excluded from water to form a new liquid phase. The phase diagrams have been determined at ambient temperature. In order to understand why and how a zwitterion solute (HEPES) induced phase separation of the investigated systems, molecular dynamics (MD) simulation studies are performed for HEPES + water + THF system. The MD simulations were conducted for the aqueous mixtures with 12 different compositions. The reliability of the simulation results of HEPES in pure water and beyond the phase separation mixtures was justified by comparing the densities obtained from MD with the experimental values. The simulation results of HEPES in pure THF and in a composition inside the phase separation region were justified qualitatively. Interestingly, all HEPES molecules entirely aggregated in pure THF. This reveals that HEPES is insoluble in pure THF, which is consistent with the experimental results. Even more interestingly, the MD simulation for the mixture with composition inside the phase separation region showed the formation of two phases. The THF molecules are squeezed out from the water network into a new liquid phase. The hydrogen bonds (HBs), HB lifetime, HB Gibbs energy (ΔG), radial distribution functions (RDFs), coordination numbers (CNs), electrostatic interactions, and the van der Waals interactions between the different species have been analyzed. Further, MD simulations for the other phase separation systems by choosing a composition inside the two liquids region for each system were also simulated. Our findings will therefore pave the way for designing new benign separation auxiliary agents.

  4. Amorphous solid dispersion of cyclosporine A prepared with fine droplet drying process: Physicochemical and pharmacokinetic characterization.

    Suzuki, Hiroki; Moritani, Tatsuru; Morinaga, Tadahiko; Seto, Yoshiki; Sato, Hideyuki; Onoue, Satomi

    2017-03-15

    The present study aimed to develop an amorphous solid dispersion (ASD) of cyclosporine A (CsA) by a fine droplet drying (FDD) process for improvement in oral absorption of CsA. CsA and hydroxypropyl cellulose-SSL were dissolved in 1,4-dioxane, and the solution was powdered by the FDD process to obtain the ASD formulation of CsA (ASD/CsA). The ASD/CsA was characterized in terms of morphology, particle size distribution, crystallinity, dissolution behavior, physicochemical stability, and pharmacokinetic behavior in rats. The ASD/CsA was obtained in the form of uniform spherical particles, and the span factor was calculated to be ca. 0.4. CsA in the formulation existed in an amorphous state. The ASD/CsA exhibited a higher dissolution behavior of CsA than amorphous CsA, whereas storage of the ASD/CsA under accelerated conditions led to impairment in the dissolution behavior. The constant release of CsA from non-aged ASD/CsA was observed during dissolution testing. After oral administration of CsA samples (10mg-CsA/kg) in rats, the ASD/CsA showed a high and sustained plasma concentration of CsA as evidenced by a 18-fold increase in the oral bioavailability of CsA compared with amorphous CsA. From these findings, the FDD process might be an efficacious option for the ASD formulation of CsA with enhanced biopharmaceutics properties.

  5. Generation of ROS mediated by mechanical waves (ultrasound) and its possible applications.

    Duco, Walter; Grosso, Viviana; Zaccari, Daniel; Soltermann, Arnaldo T

    2016-10-15

    The thermal decomposition of 9,10 diphenylanthracene peroxide (DPAO2) generates DPA and a mix of triplet and singlet molecular oxygen. For DPAO2 the efficiency to produce singlet molecular oxygen is 0.35. On the other hand, it has shown that many thermal reactions can be carried out through the interaction of molecules with ultrasound. Ultrasound irradiation can create hydrodynamic stress (sonomechanical process), inertial cavitation (pyrolitic process) and long range effects mediated by radicals or ROS. Sonochemical reactions can be originated by pyrolytic like process, shock mechanical waves, thermal reactions and radical and ROS mediated reactions. Sonolysis of pure water can yield hydrogen or hydroxyl radicals and hydrogen peroxide (ROS). When DPAO2 in 1,4 dioxane solution is treated with 20 or 24kHz and different power intensity the production of molecular singlet oxygen is observed. Specific scavengers like tetracyclone (TC) are used to demonstrate it. The efficiency now is 0.85 showing that the sonochemical process is much more efficient that the thermal one. Another endoperoxide, artemisinin was also studied. Unlike the concept of photosensitizer of photodynamic therapy, in spite of large amount of reported results in literature, the term sonosensitizer and the sonosensitization process are not well defined. We define sonosensitized reaction as one in which a chemical species decompose as consequence of cavitation phenomena producing ROS or other radicals and some other target species does undergo a chemical reaction. The concept could be reach rapidly other peroxides which are now under experimental studies. For artemisinin, an important antimalarian and anticancer drug, was established that ultrasound irradiation increases the effectiveness of the treatment but without any explanation. We show that artemisinin is an endoperoxide and behaves as a sonosensitizer in the sense of our definition.

  6. A Convenient Approach to Heterocyclic Building Blocks: Synthesis of Novel Ring Systems Containing a [5,6]Pyrano[2,3-c]pyrazol-4(1H-one Moiety

    Wolfgang Holzer

    2007-01-01

    Full Text Available Starting from commercially available educts, a straightforward synthetic route to new heterocyclic building blocks is exemplified with the one- or two-step synthesis of tri-, tetra-, or pentacyclic ring systems. Representatives of the following novel ring systems are prepared from 3-methyl-1-phenyl-2-pyrazolin-5-one and the corresponding o-halo-arenecarbonyl chloride using calcium hydroxide in refluxing 1,4-dioxane: pyrimidino[4',5':5,6]pyrano[2,3-c]pyrazol-4(1H-one, thieno[3',2':5,6]pyrano[2,3c]pyrazol- 4-(1H-one, thieno[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H-one, thieno[3'',2'':4',5']thieno[2',3':5,6]-pyrano[2,3-c]pyrazol-4(1H-one, [1,3]dioxolo[5',6'][1]benzothieno[2',3':5,6]pyrano-[2,3-c]- pyrazol-4(1H-one, pyridazino[4',3':5,6]pyrano[2,3-c]pyrazol-4(1H-one and pyrazolo-[4'',3'':5',6']pyrido[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H-one. While the latter two ring systems are directly obtained due to a spontaneous intramolecular substitution reaction, in the other reactions uncyclised 4-aroylpyrazol-5-ols are produced, which are cyclised into the target heterocycles in a subsequent synthetic step (i.e. treatment with NaH in DMF. Detailed NMR spectroscopic investigations (1H-, 13C-, 15N- with the obtained compounds were undertaken to unambiguously prove the new structures.

  7. 3d-4f Metal-Organic Framework with Dual Luminescent Centers That Efficiently Discriminates the Isomer and Homologues of Small Organic Molecules.

    Zeng, Guang; Xing, Shanghua; Wang, Xiuru; Yang, Yulin; Ma, Dingxuan; Liang, Hongwei; Gao, Lu; Hua, Jia; Li, Guanghua; Shi, Zhan; Feng, Shouhua

    2016-02-01

    A 3d-4f luminescent metal-organic framework (MOF), [Tb2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (4), and three analogues {[La2(Cu8I8)(C12H8NO2)6(C4H8O2)2(H2O)2]·3C4H8O2·2H2O (1), [Ce2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (2), and [Eu2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (3)}, were self-assembled from copper(I) halide clusters and lanthanide metal ions with an organic linker [3-(pyridin-4-yl)benzoic acid] under solvothermal conditions. Compound 4 with high quantum yield (Φ = 68%) exhibits reversible luminescence behavior, accompanying the removal and recovery of guest molecules (1,4-dioxane). Because of the unique porous structure and dual luminescent centers of compound 4, it can efficiently differentiate benzene series with different sizes and provide readouts in corresponding optical signals. Furthermore, it also can unambiguously discriminate the isomers, homologues, and other small molecules with similar structural motifs from one another. The luminescent color of the MOF sensor in different guest solvents has obvious changes that can be clearly distinguished by the naked eye. This multicolor luminescence originates from emissions of the dual luminescent centers, and the emissions have shifted, enhanced, weakened, or quenched to different degrees.

  8. A review of quality surveillance projects on cosmetics in Taiwan

    Meng-Hsuan Chung

    2014-12-01

    Full Text Available The Food and Drug Administration in Taiwan is responsible for the quality regulation and control of cosmetics. In order to have a clear understanding of the trends in the product quality monitoring outcomes and the regulatory control measures over the past years, this study has put together the reports of nine cosmetic surveillance projects conducted between 1982 and 2012. The findings can be used as a reference in developing a more solid quality monitoring plan and management system for cosmetic products. Results show that permanent wave products, hair dye products, and phthalate esters in cosmetic products have the highest average noncompliance rates at 39.2%, 14.2%, and 11.2%, respectively. These are followed by the average noncompliance rates of mercury in products, sunscreen products, and microorganisms in products, at 8.5%, 7.1%, and 5.5%, respectively, and the remaining three projects averaging below 4.1%. Since 1997, when new standards were announced and assistance to manufacturers was reinforced, the noncompliance rates of permanent wave products decreased annually, until 2007, when it was fully qualified for the standards. Overall, the study showed that the noncompliance rates of permanent wave products and for levels of phthalate esters, mercury, and hydroquinone in cosmetic products have all decreased in the previous years. The results of surveillance projects conducted after 2005 revealed only one noncompliance sample with lead, arsenic, and cadmium, whereas the surveillance projects on permanent wave products and chloroform- and 1,4-dioxane-containing products revealed full compliance with regulation standards. However, the noncompliance rates for microorganisms in cosmetics and the ingredients in hair dye products and sunscreen products were still high. These high-risk products must be monitored. These surveillance projects are conducted to ensure the safety of cosmetics in the market.

  9. Study on the Chemical Compositions of Valeriana Jatamansi%蜘蛛香的化学成分研究

    李元旦; 李蓉涛; 李海舟

    2011-01-01

    目的:对蜘蛛香根中的化学成分进行研究.方法:采用硅胶柱色谱,羟丙基葡萄糖凝胶柱层析Sephadex LH-20及HPLC(高效液相色谱)等分离纯化手段,从蜘蛛香(Valeriana jatamansi)根中分离出了17个化合物,通过理化性质和光谱数据分析.结果:分别被鉴定为(3S,4R,5S,7S,8S,9S)-3,8-epoxy-7-hydroxy-4,8-dimethylper-hydrocyclopenta[c]pyran(1),(3S,4S,5S,7S,8S,9S)-3,8-ethoxy-7-hydroxy-4,8-dimethylperhydrocyclopenta[c]pyran(2),4-β-hydroxy-8-β-methoxy-10-methylene-2,9-dioxatricyclo[4.3.1.03.7]decan(3),6-hydroxy-7-(hydroxymethyl)-4-methyl-enehexahydrocyclopenta[c]pyran-1-(3H)-one(4),jatamansi A(5),jatamansi G(6),8-hydroxypinoresinol(7),2,5-di(4-hydroxy-3-methoxyphenyl)-1,4-dioxan(8),pinoresinol(9),(+)-2-(3,4-dimethoxyphenyl)-6-(3,4-dihydroxyphenyl)-2,7-dioxabi-cyclo[3,3,0]octane(10),pinoresinol monomethyl ether(11),prinsepoil(12),(-)-massoniresinol(13),cinnamolide(14),valeriananoid A(15),valeriananoid C(16)和volvatrate A(17).结论:化合物3、4和17与化合物7~14为首次在该植物中发现.

  10. Efficient preparation of (R)-alpha-monobenzoyl glycerol by lipase catalyzed asymmetric esterification: optimization and operation in packed bed reactor.

    Xu, J H; Kato, Y; Asano, Y

    2001-06-20

    Optically active (R)-alpha-monobenzoyl glycerol (MBG) was synthesized by Candida antarctica lipase B (CHIRAZYME L-2) catalyzed asymmetric esterification of glycerol with benzoic anhydride in organic solvents. Various conditions, such as the type and composition of the organic solvent, water content of the system, reaction temperature, and concentrations of the substrates were systematically examined and optimized in screw-capped test tubes with respect to both the reaction rate and the enzyme selectivity. 1,4-Dioxane was found to be the best solvent and no additional water was needed for the system. The optimum temperature was around 30 degrees C, while the most suitable substrate concentrations were 100 mM each for glycerol and benzoic anhydride, respectively. However, when excessive anhydride (e.g., 200 mM) was used, the produced MBG could be further transformed into 1,3-dibenzoyl glycerol (DBG) by the same enzyme with a priority to (S)-MBG, resulting in a significant improvement of the product optical purity from ca. 50-70% e.e. Under optimal conditions (100 mM glycerol, 100-200 mM benzoic anhydride, dioxane, 25-30 degrees C), the enzymatic synthesis of (R)-MBG was successfully operated in a packed-bed reactor for about 1 week, with an average productivity of 0.79 g MBG/day/g biocatalyst in the case of continuous operation and 0.94 g MBG/day/g biocatalyst in the case of semicontinuous operation. After refinement and preferential crystallization of the crude product, (R)-MBG could be obtained in an almost optically pure form (>98% e.e.).

  11. Final report on the safety assessment of PEG-25 propylene glycol stearate, PEG-75 propylene glycol stearate, PEG-120 propylene glycol stearate, PEG-10 propylene glycol, PEG-8 propylene glycol cocoate, and PEG-55 propylene glycol oleate.

    Johnson, W

    2001-01-01

    The ingredients considered in this safety assessment are polyethylene glycol ethers of either propylene glycol itself, propylene glycol stearate, propylene glycol oleate, or propylene glycol cocoate. They function in cosmetic formulations as surfactant--cleansing agents; surfactant-solubilizing agents; surfactant--emulsifying agents; skin conditioning agents--humectant; skin-conditioning agents--emollient; and solvents. Those in current use are used in only a small number of cosmetic formulations. Some are not currently used. Polyethylene Glycol (PEG) Propylene Glycol Cocoates and PEG Propylene Glycol Oleates are produced by the esterification of polyoxyalkyl alcohols with lauric acid and oleic acid, respectively. Although there is no information available on the method of manufacture of the other polymers, information was available describing impurities, including ethylene oxide (maximum 1 ppm), 1,4-dioxane (maximum 5 ppm), polycyclic aromatic compounds (maximum 1 ppm), and heavy metals-lead, iron, cobalt, nickel, cadmium, and arsenic included (maximum 10 ppm combined). In an acute oral toxicity study, PEG-25 Propylene Glycol Stearate was not toxic. An antiperspirant product containing 2.0% PEG-25 Propylene Glycol Stearate was nonirritating to mildly irritating to the eyes of rabbits. This product was also practically nonirritating to the skin of rabbits in single-insult occlusive patch tests. In a guinea pig sensitization test, PEG-25 Propylene Glycol Stearate was classified as nonallergenic at challenge concentrations of 25% and 50% in petrolatum. PEG-25 Propylene Glycol Stearate and PEG-55 Propylene Glycol Oleate were negative in clinical patch tests. Based on the available data, it was concluded that these ingredients are safe as used (concentrations no greater than 10%) in cosmetic formulations. Based on evidence of sensitization and nephrotoxicity in burn patients treated with a PEG-based antimicrobial preparation, the ingredients included in this review

  12. The prediction of selectivity of ionic liquid by COSMO-SAC model%基于COSMO-SAC模型对离子液体选择性的预测

    余冬梅; 左麦芳; 李毅; 邵先钊

    2014-01-01

    Based on the results of theσprofile of water, 1,4-dioxane, acetone, hexane, 1-octanol, cyclohexane, benzene and the ionic liquid, the activity coefficient of two-phase system of solutes and ILs were calculated using the COSMO-SAC model to predict the equilibrium. The activity coefficients at infinite dilution of cyclohexane, benzene, xylene, m-xylene and o-xylene in the ionic liquid were calculated;provide the basis for the selection of ionic liquid on separation of aliphatic / aromatic hydrocarbon mixtures, p-xylene / m-xylene mixture, p-xylene /o-xylene mixture.%以水,1,4二氧六环,丙酮,正己烷,1-辛醇,环己烷,苯以及离子液体的σprofile计算结果为基础,采用COSMO-SAC模型对各种两相系统的活度系数进行计算,以预测相平衡。预测了环己烷、苯、对二甲苯、间二甲苯和邻二甲苯在离子液体1-乙基-3-甲基咪唑四氟硼酸盐[Emim][BF4]和1-丁基-3-甲基咪唑二氰胺盐[Bmim][(CN)2N]中的无限稀释活度系数,为选择合适离子液体分离脂肪烃/芳香烃混合体系,对二甲苯/间二甲苯混合物,对二甲苯/邻二甲苯混合物提供依据。

  13. Solvent dependence of Stokes shift for organic solute-solvent systems: A comparative study by spectroscopy and reference interaction-site model-self-consistent-field theory.

    Nishiyama, Katsura; Watanabe, Yasuhiro; Yoshida, Norio; Hirata, Fumio

    2013-09-01

    The Stokes shift magnitudes for coumarin 153 (C153) in 13 organic solvents with various polarities have been determined by means of steady-state spectroscopy and reference interaction-site model-self-consistent-field (RISM-SCF) theory. RISM-SCF calculations have reproduced experimental results fairly well, including individual solvent characteristics. It is empirically known that in some solvents, larger Stokes shift magnitudes are detected than anticipated on the basis of the solvent relative permittivity, ɛr. In practice, 1,4-dioxane (ɛr = 2.21) provides almost identical Stokes shift magnitudes to that of tetrahydrofuran (THF, ɛr = 7.58), for C153 and other typical organic solutes. In this work, RISM-SCF theory has been used to estimate the energetics of C153-solvent systems involved in the absorption and fluorescence processes. The Stokes shift magnitudes estimated by RISM-SCF theory are ∼5 kJ mol(-1) (400 cm(-1)) less than those determined by spectroscopy; however, the results obtained are still adequate for dipole moment comparisons, in a qualitative sense. We have also calculated the solute-solvent site-site radial distributions by this theory. It is shown that solvation structures with respect to the C-O-C framework, which is common to dioxane and THF, in the near vicinity (∼0.4 nm) of specific solute sites can largely account for their similar Stokes shift magnitudes. In previous works, such solute-solvent short-range interactions have been explained in terms of the higher-order multipole moments of the solvents. Our present study shows that along with the short-range interactions that contribute most significantly to the energetics, long-range electrostatic interactions are also important. Such long-range interactions are effective up to 2 nm from the solute site, as in the case of a typical polar solvent, acetonitrile.

  14. Photoinduced intramolecular charge transfer of sodium 4-(N,N-dimethylamino)benzenesulfonate

    2000-01-01

    A new dual fluorescent N,N-dimethylaniline derivative, sodium 4-(N,N-dimethylamino)- benzenesulfonate (SDMAS), is reported. In SDMAS, the electron acceptor is linked to the phenyl ring via a sulfur atom at the para-position of the electron donor. It was found that SDMAS emits dual fluorescence only in highly polar solvent water but not in organic solvents such as formamide, methanol and acetonitrile. In organic solvents only a single-band emission at ca.360 nm was observed in the short wavelength region. The dual fluorescence of SDMAS in water was found at 365 and 475 nm, respectively. Introduction of organic solvent such as ethanol, acetonitrile, and 1,4-dioxane into aqueous solution of SDMAS leads to blue-shift and quenching of the long-wavelength emission. Measurements of steady-state and picosecond time-resolved fluorescence indicate that the long wavelength fluorescence is emitted from a charge transfer (CT) state that is populated from the locally excited (LE) state, with the latter giving off the short wavelength fluorescence. The fact that a highly polar solvent is required to bring out the dual fluorescence suggests that the CT process of SDMAS has a high activation energy (Ea). In supporting this assumption the time-resolved fluorescence measurements give an Ea of 15.35 kJ.mol-1. It was assumed that the participation of the sulfur atom d-orbital in the conjugation of sulfonate group with phenyl ring and the strong twisting and inverting of the dimethylamino plane relative to the phenyl ring could be the reasons for the high activation energy. A molecular configuration change upon charge transfer in water was suggested for SDMAS based on the thermodynamic data. SDMAS reported here represents the example of the dual fluorescent amine substituted aromatic sulfonate.

  15. Femtosecond and temperature-dependent picosecond dynamics of ultrafast excited-state proton transfer in water-dioxane mixtures.

    Freitas, Adilson A; Quina, Frank H; Maçanita, António A L

    2014-11-13

    Synthetic flavylium salts like the 7-hydroxy-4-methylflavylium (HMF) cation have been used as prototypes to study the chemistry and photochemistry of anthocyanins, the major group of water-soluble pigments in the plant kingdom. In this work, a combination of fluorescence upconversion with femtosecond time resolution and time-correlated single photon counting (TCSPC) with picosecond time resolution have been employed to investigate in details the excited-state proton transfer (ESPT) of HMF in water and in binary water/1,4-dioxane mixtures. TCSPC measurements as a function of temperature provide activation parameters for all of the individual rate constants involved in the proton transfer, including those for dissociation and recombination of the geminate excited base-proton pair (A*···H(+)) that can be detected in the water/dioxane mixtures (but not in water). Unlike the other rate constants, the deprotonation rate constant kd shows a non-Arrhenius dependence on temperature in both water and water/dioxane mixtures. At low temperatures kd is close to the dielectric relaxation rate of the solvent with a barrier of ca. 8 kJ mol(-1), suggesting that the solvent reorganization is the rate-limiting step. At higher temperatures (>30 °C) the proton transfer process is nearly barrierless and solvent-dependent. Fluorescence upconversion results in H2O, D2O, and water/dioxane mixtures confirm the two-step model for the ESPT of HMF and provide additional details of the early events prior to the onset of proton transfer, attributed to conformational relaxation and solvent reaccommodation around the initially formed excited state. The results are consistent with DFT calculations that indicate that charge redistribution occurs after rather than prior to the onset of the ESPT process.

  16. Inductance-based sensing technique for wireless,remote-query measurement in liquid media

    2010-01-01

    A novel inductance-based sensing technique is presented for remote query measurement in different liquid media including organic solvents and inorganic solutions.The inorganic solutions tested included salt solutions of different concentrations,and the organic solvents detected included 1,4-dioxane and tetrahydrofuran.To extend the application of the sensor,bacterial culture media were also detected,and the growth of Escherichia coli (E.coli) was controlled.The influential factors which may affect the inductance responses were studied in detail.It was found that quantitative relationships exist between the sensor’s inductance response and the physico-chemical parameters of the liquid media.The sensor’s inductance response (L) decreases with the increase of salt concentration (C) and its ionic valence (e) according to a semi-logarithmic equation LgL =-aeC + b,where a and b are constants,which is in accordance with the theoretically deduced equation.The inductance variation rate (ΔK) increases directly with the temperature (T): ΔK = a′ T + b′.As for organic solutions,the sensor’s inductance was found to increase with the increasing permittivity of the organic solution.The wireless sensor we designed is simple and easy to manipulate.It has the potential for remote determination of not only chemical substances but also microbiological species such as bacteria.Using the newly developed inductance-based sensor,the pathogenic E.coli was monitored with a limit of detection of 10 cells/mL and a linear semi-logarithmic range of 1.0 × 101 to 2.5 × 109 cells/mL.

  17. Enhanced delivery of the RAPTA-C macromolecular chemotherapeutic by conjugation to degradable polymeric micelles.

    Blunden, Bianca M; Lu, Hongxu; Stenzel, Martina H

    2013-12-09

    Macromolecular ruthenium complexes are a promising avenue to better and more selective chemotherapeutics. We have previously shown that RAPTA-C [RuCl2(p-cymene)(PTA)], with the water-soluble 1,3,5-phosphaadamantane (PTA) ligand, could be attached to a polymer moiety via nucleophilic substitution of an available iodide with an amide in the PTA ligand. To increase the cell uptake of this macromolecule, we designed an amphiphilic block copolymer capable of self-assembling into polymeric micelles. The block copolymer was prepared by ring-opening polymerization of d,l-lactide (3,6-dimethyl-1,4-dioxane-2,5-dione) using a RAFT agent with an additional hydroxyl functionality, followed by the RAFT copolymerization of 2-hydroxyethyl acrylate (HEA) and 2-chloroethyl methacrylate (CEMA). The Finkelstein reaction and reaction with PTA led to polymers that can readily react with the dimer of RuCl2(p-cymene) to create a macromolecular RAPTA-C drug. RAPTA-C conjugation, micellization, and subsequent cytotoxicity and cell uptake of these polymeric moieties was tested on ovarian cancer A2780, A2780cis, and Ovcar-3 cell lines. Confocal microscopy images confirmed cell uptake of the micelles into the lysosome of the cells, indicative of an endocytic pathway. On average, a 10-fold increase in toxicity was found for the macromolecular drugs when compared to the RAPTA-C molecule. Furthermore, the cell uptake of ruthenium was analyzed and a significant increase was found for the micelles compared to RAPTA-C. Notably, micelles prepared from the polymer containing fewer HEA units had the highest cytotoxicity, the best cell uptake of ruthenium and were highly effective in suppressing the colony-forming ability of cells.

  18. Millimeter wave and terahertz dielectric properties of biological materials

    Khan, Usman Ansar

    Broadband dielectric properties of materials can be employed to identify, detect, and characterize materials through their unique spectral signatures. In this study, millimeter wave, submillimeter wave, and terahertz dielectric properties of biological substances inclusive of liquids, solids, and powders were obtained using Dispersive Fourier Transform Spectroscopy (DFTS). Two broadband polarizing interferometers were constructed to test materials from 60 GHz to 1.2 THz. This is an extremely difficult portion of the frequency spectrum to obtain a material's dielectric properties since neither optical nor microwave-based techniques provide accurate data. The dielectric characteristics of liquids such as cyclohexane, chlorobenzene, benzene, ethanol, methanol, 1,4 dioxane, and 10% formalin were obtained using the liquid interferometer. Subsequently the solid interferometer was utilized to determine the dielectric properties of human breast tissues, which are fixed and preserved in 10% formalin. This joint collaboration with the Tufts New England Medical Center demonstrated a significant difference between the dielectric response of tumorous and non-tumorous breast tissues across the spectrum. Powders such as anthrax, flour, talc, corn starch, dry milk, and baking soda have been involved in a number of security threats and false alarms around the globe in the last decade. To be able to differentiate hoax attacks and serious security threats, the dielectric properties of common household powders were also examined using the solid interferometer to identify the powders' unique resonance peaks. A new sample preparation kit was designed to test the powder specimens. It was anticipated that millimeter wave and terahertz dielectric characterization will enable one to clearly distinguish one powder from the other; however most of the powders had relatively close dielectric responses and only Talc had a resonance signature recorded at 1.135 THz. Furthermore, due to

  19. Charge separation distance for flexible donor-bridge-acceptor systems after electron-transfer quenching.

    Zhou, Jinwei; Lukin, Leonid V; Braun, Charles L

    2008-08-21

    Photoinduced transient dipole experiments are used to measure the effective charge separation distance, which is equivalent to the photoinduced change in dipole moment divided by the electron charge of flexible electron-donor/acceptor systems, D-(CH2)n-A, where D is 4- N,N-dimethylaniline, A is 9-anthryl, and n = 3, 4. We find that the dipole moments increase strongly with solvent polarity. For the compound with n = 4 (DBA4), analysis of dipole signals indicates that the effective charge separation distances in toluene, 1,4-dioxane, ethyl acetate, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 2-methylpentanone-3, 3-pentanone, and benzonitrile are 2.2, 2.5, 4.5, 4.7, 5.5, 5.5, 4.8, and 6.3 A, respectively. These values can be understood as the root-mean-square charge separation distance in the solutions of different solvents. We assume that the folded contact configuration has a separation distance of 3.5 A, the extended, solvent-separated configuration has a separation distance of 8.0 A, and that they are the only two stable species after electron-transfer quenching. The formation efficiencies of contact radical ion pairs (CRIPs) and solvent-separated radical ion pairs (SSRIPs) are estimated in different solvents. The results indicate that a significant fraction of the ion pairs exist as solvent-separated ion pairs when the dielectric constant of the solvent is larger than 10. These results indicate that electron-transfer quenching can indeed happen at large separations in polar solvents. They also reveal that there is a barrier for ion pairs formed at large separations, hindering collapse to a contact separation of around 3.5 A.

  20. TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: phase diagrams and molecular dynamic simulations.

    Taha, Mohamed; Lee, Ming-Jer

    2013-06-28

    Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol∕acetonitrile∕acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.

  1. A Simple Spectrophotometric Method for the Determination of Copper in Some Real, Environmental, Biological, Food and Soil Samples Using Salicylaldehyde Benzoyl Hydrazone

    M. Jamaluddin Ahmed

    2012-06-01

    Full Text Available A very simple, ultra-sensitive, highly selective and non-extractive spectrophotometric method for the determination of trace amounts copper(II has been developed. Salicylaldehy debenzoyl hydrazone (SAL-BH has been proposed as a new analytical reagent for the direct non-extractive spectrophotometric determination of copper(II. SAL-BH reacts with copper in a slightly acidic (0.0001-0.005 M H2SO4 in 40% 1,4-dioxane media with copper(II to give a highly absorbent greenish yellow chelate with a molar ratio 1:1(CuII: SAL-BH The reaction is instantaneous and the maximum absorption was obtained at 404 nm and remains stable for 72 h. The average molar absorptivity and Sandell’s sensitivity were found to be 1.4×105 L mol-1 cm-1 and 5.0 ng cm-2 of copper(II, respectively. Linear calibration graphs were obtained for 0.01 – 18 mg L-1 of CuII. The detection limit and quantification limit of the reaction system were found to be 1 ng mL-1 and 10 µg L-1, respectively. A large excess of over 50 cations, anions and complexing agents (e.g., tartrate, oxalate, citrate, phosphate, thiocyanate etc. do not interfere in the determination. The method is highly selective for copper and was successfully used for the determination of copper in several standard reference materials (steels and alloys as well as in some environmental waters (portable and polluted, biological (human blood and urine, food and soil samples and solutions containing both copper(I and copper(II as well as some complex synthetic mixtures. The results of the proposed method for biological and food samples were comparable with AAS and were found to be in good agreement. The method has high precision and accuracy (s = ± 0.01 for 0.5 mg L-1.

  2. Hydrogen/deuterium exchange study of subtilisin Carlsberg during prolonged exposure to organic solvents.

    Fasoli, Ezio; Ferrer, Amaris; Barletta, Gabriel L

    2009-03-01

    It has been previously reported that prolonged exposure of an enzyme to organic solvents leads to substantial decrease of activity. This effect was found to be unrelated to the catalysts' structure or their possible aggregation in organic solvents, and up to the present day the cause for activity loss remains unclear. In the present work, the structural dynamics of the serine protease subtilisin Carlsberg (SC) have been investigated during prolonged exposure to two organic solvents by following hydrogen/deuterium (H/D) exchange of mobile protons. The enzyme, after lyophilization, was incubated in organic solvents at controlled deuteriated water activity for different times and the H/D exchange was allowed to take place. The amount of deuterium exchanged was evaluated by (2)H NMR, which in turn gave us a picture of the changing dynamics of our model enzyme during incubation and under different experimental conditions. Our results show that the flexibility of SC decreases during prolonged storage in 1,4-dioxane (Diox) and acetonitrile (ACN) as indicated by the observed 3- to 10-fold decrease in the apparent rate constants of exchange (k) of fast exchangeable protons (FEP) and slow exchangeable protons (SEP) in the protein. Our study also shows that SC is more flexible in ACN than in Diox (k 3-20 times higher in ACN for the FEP and SEP), suggesting that enzyme dynamics are affected by solvent physicochemical properties. Additionally, the enzyme dynamics are also affected by the method of preparation: decreased flexibility (k decreases 3- to 10-fold for FEP and SEP) is observed when the enzyme is chemically modified with poly ethylene glycol (PEGylated) or colyophilized with crown ethers. A possible relationship between activity, enantioselectivity (E), and structural dynamics is discussed, demonstrating that direct correlations, as have been attempted in the past, are hampered by the multi-variable nature and complexity of the system.

  3. Theoretical study of the reaction kinetics of atomic bromine with tetrahydropyran

    Giri, Binod

    2015-02-12

    A detailed theoretical analysis of the reaction of atomic bromine with tetrahydropyran (THP, C5H10O) was performed using several ab initio methods and statistical rate theory calculations. Initial geometries of all species involved in the potential energy surface of the title reaction were obtained at the B3LYP/cc-pVTZ level of theory. These molecular geometries were reoptimized using three different meta-generalized gradient approximation (meta-GGA) functionals. Single-point energies of the stationary points were obtained by employing the coupled-cluster with single and double excitations (CCSD) and fourth-order Møller-Plesset (MP4 SDQ) levels of theory. The computed CCSD and MP4(SDQ) energies for optimized structures at various DFT functionals were found to be consistent within 2 kJ mol-1. For a more accurate energetic description, single-point calculations at the CCSD(T)/CBS level of theory were performed for the minimum structures and transition states optimized at the B3LYP/cc-pVTZ level of theory. Similar to other ether + Br reactions, it was found that the tetrahydropyran + Br reaction proceeds in an overall endothermic addition-elimination mechanism via a number of intermediates. However, the reactivity of various ethers with atomic bromine was found to vary substantially. In contrast with the 1,4-dioxane + Br reaction, the chair form of the addition complex (c-C5H10O-Br) for THP + Br does not need to undergo ring inversion to form a boat conformer (b-C4H8O2-Br) before the intramolecular H-shift can occur to eventually release HBr. Instead, a direct, yet more favorable route was mapped out on the potential energy surface of the THP + Br reaction. The rate coefficients for all relevant steps involved in the reaction mechanism were computed using the energetics of coupled cluster calculations. On the basis of the results of the CCSD(T)/CBS//B3LYP/cc-pVTZ level of theory, the calculated overall rate coefficients can be expressed as kov.,calc.(T) = 4.60 × 10

  4. Synthesis, properties and applications of bio-based materials

    Srinivasan, Madhusudhan

    silanes on the polyester in short reaction times of 5 minutes. This improved the compatibility with the talc filler. This biodegradable polyester product was characterized by high tensile strength and moderate elongation. The modification method is simple is applicable to a variety of aliphatic biodegradable polyesters. Finally a rapid polymerization of 1, 4-dioxan-2-one in very short times was accomplished with titanium alkoxides as initiators. At low [monomer]/ [initiator] ratios (100:1), nearly all the alkoxide groups initiated polymerization. High conversions up to 90% were achieved even at high ratios (2400:1). The activation energy for polymerization for titanium tetraisopropoxide is the lowest reported (33.5 kJ/mol) for this monomer system.

  5. Eight new crystal structures of 5-(hydroxymethyl)uracil, 5-carboxyuracil and 5-carboxy-2-thiouracil: insights into the hydrogen-bonded networks and the predominant conformations of the C5-bound residues.

    Seiler, Vanessa Kristina; Hützler, Wilhelm Maximilian; Bolte, Michael

    2016-05-01

    In order to examine the preferred hydrogen-bonding pattern of various uracil derivatives, namely 5-(hydroxymethyl)uracil, 5-carboxyuracil and 5-carboxy-2-thiouracil, and for a conformational study, crystallization experiments yielded eight different structures: 5-(hydroxymethyl)uracil, C5H6N2O3, (I), 5-carboxyuracil-N,N-dimethylformamide (1/1), C5H4N2O4·C3H7NO, (II), 5-carboxyuracil-dimethyl sulfoxide (1/1), C5H4N2O4·C2H6OS, (III), 5-carboxyuracil-N,N-dimethylacetamide (1/1), C5H4N2O4·C4H9NO, (IV), 5-carboxy-2-thiouracil-N,N-dimethylformamide (1/1), C5H4N2O3S·C3H7NO, (V), 5-carboxy-2-thiouracil-dimethyl sulfoxide (1/1), C5H4N2O3S·C2H6OS, (VI), 5-carboxy-2-thiouracil-1,4-dioxane (2/3), 2C5H4N2O3S·3C6H12O3, (VII), and 5-carboxy-2-thiouracil, C10H8N4O6S2, (VIII). While the six solvated structures, i.e. (II)-(VII), contain intramolecular S(6) O-H...O hydrogen-bond motifs between the carboxy and carbonyl groups, the usually favoured R2(2)(8) pattern between two carboxy groups is formed in the solvent-free structure, i.e. (VIII). Further R2(2)(8) hydrogen-bond motifs involving either two N-H...O or two N-H...S hydrogen bonds were observed in three crystal structures, namely (I), (IV) and (VIII). In all eight structures, the residue at the ring 5-position shows a coplanar arrangement with respect to the pyrimidine ring which is in agreement with a search of the Cambridge Structural Database for six-membered cyclic compounds containing a carboxy group. The search confirmed that coplanarity between the carboxy group and the cyclic residue is strongly favoured.

  6. 醚-酯型季铵盐阳离子表面活性剂的合成及性能%SYNTHESIS AND PROPERTIES OF ETHER-ESTER TYPE QUATERNARY AMMONIUM SALT CATIONIC SURFACTANTS

    孟小华

    2013-01-01

    以硬脂醇、金属钠及3-氯-2-羟基丙基三甲基氯化铵为原料合成了3-烷氧基-2-羟基丙基三甲基氯化铵(OPAC),进一步与硬脂酰氯反应后得到醚-酯型双长链季铵盐阳离子表面活性剂3-烷氧基-2-酰氧基丙基三甲基氯化铵.正交实验确定的最佳合成条件为:1,4-二氧六环为溶剂,用量40 mL,n(OPAC)∶n(硬脂酰氯)∶n(吡啶)=1∶1∶1,回流加热反应5h,收率为93.0%.产物结构通过红外及核磁共振氢谱表征.产物表面活性较高,具备良好的织物柔软性及酸碱稳定性.%3-Alkoxy-2-hydroxypropyl trimethyl ammonium chloride (OPAC) was synthesized by stearyl alcohol,metal sodium and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride.Double long chain ether-ester quaternary ammonium salt cationic surfactants 3-alkoxy-2-acyloxy trimethyl ammonium chloride was further synthesized with OPAC and stearyl chloride.Through orthogonally arranged experiments,the optimal esterification conditions were obtained as follows:40 mL 1,4-dioxane was used as solvent,n(OPAC) ∶ n(stearyl chloride) ∶ n(pyridine)=l ∶ 1 ∶ 1 and refluxing time was 5 h.The yield of end product was 93.0%.The structure was confirmed by IR and 1H NMR.Performance results show that the product has high surface activity,good fabric softness and pH stability.

  7. Solvent-controlled synthesis of tetranuclear cage-like copper(II) silsesquioxanes. Remarkable features of the cage structures and their high catalytic activity in oxidation with peroxides.

    Dronova, Marina S; Bilyachenko, Alexey N; Yalymov, Alexey I; Kozlov, Yuriy N; Shul'pina, Lidia S; Korlyukov, Alexander A; Arkhipov, Dmitry E; Levitsky, Mikhail M; Shubina, Elena S; Shul'pin, Georgiy B

    2014-01-14

    Two principally different in their molecular architecture isomeric tetranuclear copper(ii) silsesquioxanes, "Globule"-like compound [(PhSiO1.5)12(CuO)4(NaO0.5)4] (1) and "Sandwich"-like derivative [(PhSiO1.5)6(CuO)4(NaO0.5)4(PhSiO1.5)6] (2), were synthesized by the partial cleavage of polymeric copper(ii) silsesquioxane [(PhSiO1.5)2(CuO)]n by tetraphenylcyclotetrasiloxanolate. The route leading to the formation of either 1 or 2 entirely depends on the nature and composition of the solvent used for this reaction. Thus, the process in an ethanol-1-butanol solution gives compound 1. When a 1,4-dioxane-methanol mixture was used, compound 2 was prepared. The structures and unusual crystal packing of the cages were confirmed by the X-ray studies. It has been found that the reaction of benzene with H2O2 in acetonitrile solution at 50 °C catalyzed by 1 requires addition of trifluoroacetic acid (TFA) in low concentration and gives phenol with a turnover number (TON) of 250 after 3 h. The initial reaction rate W0 linearly depends on the concentration of catalyst 2. The oxidation of 1-phenylethanol to acetophenone with hydrogen peroxide catalyzed by complex 1 in the presence of TFA is not efficient. In contrast, 1 exhibited excellent activity in the oxidation with tert-butyl hydroperoxide (TBHP) in the absence of any acid (the yield of acetophenone was close to the quantitative, TON attained 475 after 2 h). A kinetic study of this reaction led to the conclusion that the process occurs with the participation of radicals tert-BuO˙ produced in the Cu-promoted decomposition of TBHP. The mode of dependence of W0 on the initial concentration of TBHP indicates the formation of an intermediate adduct between the catalyst 1 and TBHP (characterized by the equilibrium constant K1≈ 2 M(-1) for the conditions of conducted experiments) followed by subsequent decomposition of the adduct (k2≈ 0.2 s(-1)) to generate an intermediate species tert-BuO˙ which induces the alcohol oxidation.

  8. Synthesis of metal-hydrazone complexes and vapochromic behavior of their hydrogen-bonded proton-transfer assemblies.

    Kobayashi, Atsushi; Dosen, Masa-aki; Chang, Mee; Nakajima, Kiyohiko; Noro, Shin-ichiro; Kato, Masako

    2010-11-03

    We synthesized and investigated a new series of metal-hydrazone complexes, including deprotonated [MX(mtbhp)] and protonated forms [MX(Hmtbhp)](ClO(4)) (M = Pd(2+), Pt(2+); X = Cl(-), Br(-); Hmtbhp = 2-(2-(2-(methylthio)benzylidene)hydrazinyl)pyridine) and hydrogen-bonded proton-transfer (HBPT) assemblies containing [PdBr(mtbhp)] and bromanilic acid (H(2)BA). The mtbhp hydrazone ligand acts as a tridentate SNN ligand and provides a high proton affinity. UV-vis spectroscopy revealed that these metal-hydrazone complexes follow a reversible protonation-deprotonation reaction ([MX(mtbhp)] + H(+) ⇋ [MX(Hmtbhp)](+)), resulting in a remarkable color change from red to yellow. Reactions between proton acceptor [PdBr(mtbhp)] (A) and proton donor H(2)BA (D) afforded four types of HBPT assemblies with different D/A ratios: for D/A = 1:1, {[PdBr(Hmtbhp)](HBA)·Acetone} and {[PdBr(Hmtbhp)](HBA)·2(1,4-dioxane)}; for D/A = 1:2, [PdBr(Hmtbhp)](2)(BA); and for D/A = 3:2, {[PdBr(Hmtbhp)](2)(HBA)(2)(H(2)BA)·2Acetonitrile}. The proton donor gave at least one proton to the acceptor to form the hydrogen bonded A···D pair of [PdBr(Hmtbhp)](+)···HBA(-). The strength of the hydrogen bond in the pair depends on the kind of molecule bound to the free monoanionic bromanilate OH group. Low-temperature IR spectra (T < 150 K) showed that the hydrogen bond distance between [PdBr(Hmtbhp)](+) and bromanilate was short enough (ca. 2.58 Å) to induce proton migration in the [PdBr(Hmtbhp)](2)(BA) assembly in the solid state. The hydrogen bonds formed not only between [PdBr(Hmtbhp)](+) and HBA(-) but also between HBA(-) and neutral H(2)BA molecules in the {[PdBr(Hmtbhp)](2)(HBA)(2)(H(2)BA)·2Acetonitrile} assembly. The H(2)BA-based flexible hydrogen bond network and strong acidic host structure result in an interesting vapor adsorption ability and vapochromic behavior in this assembly because the vapor-induced rearrangement of the hydrogen bond network, accompanied by changes in

  9. 超声辅助或无溶剂Claisen-Schmidt反应合成含胡椒环的吲哚查尔酮%A facile synthesis of 1,3-benzodioxole-bearing indole-based chalcone via ultrasound-assisted or solvent-free Claisen-Schmidt condensation reaction

    李阳

    2014-01-01

    A structurally novel 1,3-benzodioxole-bearing indole-based chalcone,namely(E)-3-(benzo[d][1,3]dioxol-5-yl)-1-(2-chloro-1-(4-chlorobenzyl)-1H-indol-3-yl) prop-2-en-1-one(3) was synthesized,involving the ultrasound-assisted or solvent-free Claisen-Schmidt condensation reaction of 3-acetyl-2-chloro-1-(4-chlorobenzyl) indole and piperonaldehyde. The ultrasound-assisted Claisen-Schmidt condensation reaction was carried out using 1,4-dioxane as solvent and KOH as catalyst at room temperature to give the product 3 in 78%yield. Alternatively,the reaction could also be conducted under solvent-free condition by physical grinding in a mortar and pestle to obtain 3 in comparable yield of 75%. The two procedures offered easy access to 1,3-benzodioxole-bearing indole-based chalcone in short reaction time and good yield under mild conditions.%3-乙酰基-2-氯-1-(4-氯苄基)吲哚与胡椒醛通过超声辅助或无溶剂的Claisen-Schmidt缩合反应首次合成含胡椒环的吲哚查尔酮,即(E)-3-(5-胡椒基)-1-(2-氯-1-(4-氯苄基)-1H-3-吲哚查尔酮(3)。超声辅助的合成方法使用5%KOH作为催化剂,1,4-二氧六环作为溶剂,以78%的收率得到产品3。另外,这一 Claisen-Schmidt反应也可以在无溶剂研磨条件下进行,同样也以类似的收率获得产品3(75%)。这两种方法具有操作简便、反应条件温和、收率高等优点。

  10. Forest Irrigation Of Tritiated Water: A Proven Tritiated Water Management Tool

    Vangelas, Karen; Blount, Gerald; Kmetz, Thomas; Prater, Phil

    2012-11-08

    Tritium releases from the Old Radioactive Waste Burial Ground (ORWBG) at the SRS in South Carolina has impacted groundwater and surface water. Tritiated groundwater plumes discharge into Fourmile Branch which is a small tributary of the Savannah River, a regional water resource. Taking advantage of the groundwater flow paths and the local topography a water collection and irrigation system was constructed and has been used at the SRS for over a decade to reduce these tritiated water releases to Fourmile Branch. The tritiated water is transferred to the atmosphere by evaporation from the pond surface, and after irrigation, wetted surface evaporation and evapotranspiration through the forest vegetation. Over the last decade SRS has irrigated over 120,000,000 gallons of tritiated water, which diverted over 6000 curies away from Fourmile Branch and the Savannah River. The system has been effective in reducing the flux of tritiated groundwater by approximately 70%. Mass balance studies of tritium in the forest soils before operations and over the last decade indicate that approximately 90% of the tritiated water that is irrigated is transferred to the atmosphere. Dose studies indicate that exposure to site workers and offsite maximally exposed individual is very low, approximately 6 mrem/year and 0.004 mrem/year, respectively. To consistently meet the flux reduction goal of tritium into Fourmile Branch optimization activities are proposed. These efforts will increase irrigation capacity and area. An additional 17 acres are proposed for an expansion of the area to be irrigated and a planting of approximately 40 acres of pine forest plantations is underway to expand irrigation capacity. Co-mingled with the tritiated groundwater are low concentrations of chlorinated volatile organic compounds (cVOCs), and 1,4-dioxane. Research studies and SRS field data indicate the forest irrigation system may have an added benefit of reducing the mass of these co-contaminants via

  11. Synthesis of (R)- and (S)-[C-11]L-365,260 for PET studies of brain cholecystokinin (CCK) receptors

    Haradahira, T. [Research Development Corporation of Japan, Tokyo (Japan); Suzuki, K.; Inoue, O. [National Institute of Radiological Sciences, Chiba (Japan)

    1994-05-01

    Cholecystokinin (CCK) is a recognized peptide hormone in the gut and proposed as a neurotransmitter or neuromodulator in the central nervous system. Two distinct CCK receptors termed CCK-A and CCK-B have been characterized. CCK-A receptor is primarily distributed in the peripheral tissues including pancreas and gallbladder and also known to be distributed in a few brain regions. CCK-B receptor is widely distributed in the brain and has been proposed to be involved in anxiety, satiety and nociception. To investigate the functional roles of the CCK receptors in the brain by positron emission tomography, we have synthesized an enantiomeric pair of C-11 labeled non-peptide antagonists against the CCK receptors. L-365,260 [3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepine-3-yl)-N`-(3-methylpheny lurea)] is a potent CCK-B selective non-peptide antagonist (CCK-A/CCK-B ratio of IC50, 140), whereas its (S)-enantiomer is selective toward CCK-A receptor (CCK-A/CCK-B ratio of IC50, 0.02). We have synthesized the (R)- and (S)-enantiomers of [C-11]-365,260 by N-methylation (50{degrees}C for 5 min) of the racemic desmethyl precursor with [C-11]iodomethane using sodium hydride as a base and subsequent optical resolution with HPLC (column: ChiraSpher, 250 x 10 mm, Merck; eluent: n-hexane / 1,4-dioxane / 2-propanol / triethylamine = 70 / 25 / 5 / 0.1). Radiochemical yields (decay corrected) and optical purities were 34%, 99% for R-enantiomer and 36%, 99% for S-enantiomer, respectively. The total synthesis time was 40 min and specific activity was about 37 GBq/{mu}mol. In PET studies on rhesus monkey (R)-enantiomer showed a high uptake of radioactivity in the cerebral cortex, region known to have a high concentration of CCK-B receptor.

  12. Acid-base formalism in dispersion-stabilized S-H···Y (Y═O, S) hydrogen-bonding interactions.

    Bhattacherjee, Aditi; Matsuda, Yoshiyuki; Fujii, Asuka; Wategaonkar, Sanjay

    2015-02-19

    The role of sulfhydryl (S-H) group as hydrogen bond donor is not as well studied as that of hydroxyl (O-H). In this work we report on the hydrogen-bonding properties of S-H donor in 1:1 complexes of H2S with diethyl ether (Et2O), dibutyl ether (Bu2O), and 1,4-dioxane (DO). The complexes were prepared in supersonic jet and investigated using infrared predissociation spectroscopy based on VUV photoionization detection. The IR spectra of all the complexes showed the presence of a broad, intensity-enhanced, and red-shifted hydrogen-bonded S-H stretching transition. The S-H stretching frequency was red-shifted by 46, 63, and 49 cm(-1) in H2S-Et2O, H2S-Bu2O, and H2S-DO complexes, respectively, suggesting that all the complexes are S-H···O bound. Computationally, two different S-H···O bound structures, namely, "coplanar" and "perpendicular", were obtained as the minimum energy structures for these complexes at the MP2/6-311++G** level, with the former being the global minimum. However, with Dunning-type basis sets (aug-cc-pVDZ and aug-cc-pVTZ) only the perpendicular structures were found to be stable at the MP2 level. The large widths of the bound S-H stretch observed in the experimental spectra (fwhm of 35 to 80 cm(-1)) were attributed to inhomogeneous broadening due to multiple conformations of the alkyl chains in the coplanar and perpendicular structures populated in the jet. The frequency shifts in the hydrogen-bonded S-H stretching mode as well as the bond dissociation energies of all S-H···Y (Y═O,S) complexes of H2S, which includes the H2S dimer and H2S-methanol (H2S-MeOH) complexes reported in our previous work (ChemPhysChem 2013, 14, 905-914), were found to scale linearly with the proton affinity of the acceptor molecule. In this regard the S-H group, like O-H, is found to conform to the widely accepted acid-base nature of hydrogen-bonding interactions.

  13. Dysprosium(III) complexes with a square-antiprism configuration featuring mononuclear single-molecule magnetic behaviours based on different β-diketonate ligands and auxiliary ligands.

    Zhang, Sheng; Ke, Hongshan; Shi, Quan; Zhang, Jangwei; Yang, Qi; Wei, Qing; Xie, Gang; Wang, Wenyuan; Yang, Desuo; Chen, Sanping

    2016-03-28

    Three mononuclear dysprosium(III) complexes derived from three β-diketonate ligands, 4,4,4-trifluoro-1-(4-methylphenyl)-1,3-butanedione (tfmb), 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione (tffb) and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (tfnb) as well as auxiliary ligands, 5-nitro-1,10-phenanthroline (5-NO2-Phen), DMF and 2,2'-bipyridine (bpy) have been synthesized and structurally characterized, namely [Dy(5-NO2-Phen)(tfmb)3] (1), [Dy(DMF)2(tffb)3] (2) and [Dy(bpy)2(tfnb)3]·0.5(1,4-dioxane) (3). The metal ions in 1-3 adopt an approximately square-antiprismatic (SAP) coordination environment with D4d axial symmetry. The magnetic properties of 1-3 have been investigated, displaying weak out-of-phase AC signals under a zero-DC field. With an applied DC field of 1200 Oe, the quantum tunnelling of the magnetization was suppressed in 1-3 with the pre-exponential factor τ0 = 5.3 × 10(-7) s and the effective barrier ΔE/kB = 83 K for 1 as well as the pre-exponential factor τ0 = 3.09 × 10(-7) s and the effective barrier ΔE/kB = 39 K for 3. Interestingly, for the frequency dependence of the out-of-phase (χ'') of the AC susceptibility of 2, two slow relaxation of the magnetization processes occurred under the applied magnetic field of 1200 Oe, corresponding to the fast relaxation (FR) phase and slow relaxation (SR) phase, respectively. Arrhenius analysis gave the effective energy barrier (ΔE/kB) of 55 K and the pre-exponential factor (τ0) of 8.23 × 10(-12) for the SR. It is thus very likely that the FR process in complex 2 results from QTM enhanced by dipolar interactions between the Dy ions or the presence of the applied field. The structure-property relationship of some Dy(III) based mononuclear SMMs with the SAP configuration was further discussed.

  14. Cefazolin-containing poly(ε-caprolactone sponge pad to reduce pin tract infection rate in rabbits

    Hirotaka Mutsuzaki

    2014-04-01

    Full Text Available In our previous study, a fibroblast growth factor-2 (FGF-2–apatite composite layer coated on titanium screws effectively prevented pin tract infection in rabbits because of enhanced wound healing; however, the FGF-2–apatite composite layers did not completely prevent pin tract infection. Thus, we recently developed a poly(ε-caprolactone (PCL sponge pad embedded with cefazolin sodium (+CEZ, which has a fast-acting bactericidal effect. The pad is placed on the skin around the screws. The purpose of this study was to determine the anti-infective efficacy of the +CEZ pad on the pin–skin interface of the FGF-2–apatite-coated titanium screws. The +CEZ pads were prepared by mixing PCL and CEZ in 1,4-dioxane, followed by freeze-drying and compaction. They were analyzed regarding their surface structure, in vitro CEZ release profile, and bactericidal activity. The FGF-2–apatite-coated screws were implanted percutaneously in bilateral rabbit proximal tibial metaphyses—with and without the +CEZ pad—for 4 weeks (n = 20. The + CEZ pads consisted of a porous matrix of PCL in which CEZ was embedded. The CEZ-release profile showed an initial burst on Day 1 and a sustained release lasting for 30 days. The +CEZ pad retained its bactericidal activity against Staphylococcus aureus after preincubation on an agar plate for 7 days. Based on visual inspection, the pin tract infection rate was successfully reduced from 72.2% to 15.0% with the +CEZ pad (p < 0.05, which reduced the bacterial count, especially S. aureus (p < 0.05. The histological inflammation rate of the soft tissues was also significantly lower with the +CEZ pad than without it (p < 0.05. The pin tract infection rate was reduced to one-fifth with the +CEZ pad. Using it as described improves infection resistance during percutaneous implantation.

  15. 含离子液体介质中酶催化糖基化合成4-羟基苯乙基β-D-葡萄糖苷%Enzymatic Glycosylation for Synthesis of 4-Hydroxyl Phenylethyl β-D-Glucoside in Medium Containing Ionic Liquids

    岳磊; 林琼妹; 许格; 林磊; 石贤爱

    2011-01-01

    The glycosylation catalyzed by β-glucosidase for synthesis of 4-hydroxyl phenylethyl β-D-glucoside (sali-droside) in mixed medium of ionic liquids/organic solvent/buffer solution was studied. The effects of some important factors on the glycosylation such as the constitution of the medium, and the reaction conditions were investigated. The results showed that 1-butyl-3-methylimidazolium hexafluorophosphate (C4MIm · PF6) /1,4-dioxane/citric acid-phosphate buffer was the proper mixed medium for biosynthesis of salidroside. When the volume proportions of these components were 17% , 68% and 15% respectively, the product concentration would reach 18.9 mg/mL under these conditions: D-( + )-glucose 100 mg/mL, 4-hydroxyphenethyl alcohol (tyrosol) 220 mg/mL, p-glucosidase 12 U/mL, pH 6.0, 50 ℃ and 275 rpm for 120 h.%探讨了β-葡萄糖苷酶在离子液体/有机溶剂/缓冲溶液介质中催化直接糖基化反应合成4-羟基苯乙基β-D-葡萄糖苷.考察了反应体系组成、反应条件等因素对反应的影响.研究结果表明,1-丁基-3-甲基咪唑六氟磷酸盐(C4MIm·PF6)/1,4-二氧六环/柠檬酸-磷酸盐缓冲溶液是糖基化反应的合适介质.当三者的体积含量分别为17%、68%和15%,底物D-(+)-葡萄糖和4-羟基苯乙醇的含量分别为100 mg/mL和220 mg/mL、酶活力为12 U/mL时,在pH 6.0、50℃、275 rpm条件下进行直接糖基化,产物浓度可达18.9 mg/mL.

  16. Biocatalytic Synthesis of Salidroside by β-Glucosidase in Ionic Liquids%离子液体中β-葡萄糖苷酶生物催化合成红景天甙

    王梦亮; 郭春侠

    2011-01-01

    比较了聚乙二醇修饰的β-葡萄糖苷酶在三种离子液体([bmim]PF6,[bmim]BF4,[bmim]Tf2N)及两种常用有机溶剂(1,4-二氧六环、正己烷)中的催化性能,确定了适宜的反应介质;考察了底物浓度、温度、体系含水量和反应时间等因素对β-葡萄糖苷酶催化合成红景天甙反应的影响.结果表明,在最佳反应介质[bmim]PF6存在下,底物酪醇浓度为70 mmol/L,体系含水量2%,于50℃,反应24 h时,高达88.5%的酪醇转化为红景天甙(即61.93 mmol/L).与有机溶剂相比,以[bmim]PF6为反应介质对酶促合成红景天甙的反应过程具有明显的强化作用.%β-Glucosidase modified with polyethylene glycol (PEG) was used as catalyst for the synthesis of salidroside from tyrosol and D-glucose, and its catalytic activity in three ionic liquids, [bmim]PF6, [bmim]BF4, and [bmim]Tf2N, and two common organic solvents, 1,4-dioxane and n-hexane, was measured. Ionic liquid [bmim]PF6 was the optimal reaction medium, and different reaction conditions were optimized in it. A yield of 88.5% (product content of 61.93 mmol/L) was obtained under the conditions of H2O content of 2%, temperature of 50 ℃, tyrosol content of 70 mmol/L, D-glucose/tyrosol molar ratio of 2, and reaction time of 24 h. The results suggest that both the modification with PEG and using ionic liquid [bmim]PF6 as reaction medium have obvious promoting effects on the enzymatic synthesis of salidroside.

  17. Final report of the amended safety assessment of PEG-5, -10, -16, -25, -30, and -40 soy sterol.

    2004-01-01

    PEGs Soy Sterol are polyethylene glycol (PEG) derivatives of soybean oil sterols used in a variety of cosmetic formulations as surfactants and emulsifying agents, skin-conditioning agents, and cleansing and solubilizing agents. When the safety of these ingredients were first reviewed, the available data were insufficient to support safety. New data have since been received and the safety of these ingredients in cosmetics has been substantiated. Current concentration of use ranges from a low of 0.05% in makeup preparations to 2% in moisturizers and several other products. PEGs Soy Sterol are produced by the reaction of the soy sterol hydroxyl with ethylene oxide. In general, ethoxylated fatty acids can contain 1,4-dioxane as a byproduct of ethoxylation. The soy sterols include campesterol, stigmasterol, and beta-sitosterol. The distribution of sterols found in oils derived from common plants is similar, with beta-sitosterol comprising a major component. Impurities include sterol hydrocarbons and cholesterol (4% to 6%) and triterpine alcohols, keto-steroids, and other steroid-like substances (4% to 6%). No pesticide residues were detected. PEGS: Because PEGs are an underlying structure in PEGs Soy Sterols, the previous assessment of PEGs was considered. It is generally recognized that the PEG monomer, ethylene glycol, and certain of its monoalkyl ethers are reproductive and developmental toxins. Given the methods of manufacture of PEGs Soy Sterol, there is no likelihood of ethylene glycol or its alkyl ethers being present. Also, the soybean oil sterol ethers in this ingredient are chemically different from the ethylene glycol alkyl ethers of concern. PEGs are not carcinogenic, although sensitization and nephrotoxicity were observed in burn patients treated with a PEG-based cream. No evidence of systemic toxicity or sensitization was found in studies with intact skin. Plant Phytosterols: Intestinal absorption of ingested plant phytosterols is on the order of 5%, with

  18. Safety assessment of poloxamers 101, 105, 108, 122, 123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 235, 237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403, and 407, poloxamer 105 benzoate, and poloxamer 182 dibenzoate as used in cosmetics.

    Singh-Joy, Subhashni D; McLain, Valerie C

    2008-01-01

    Poloxamers are polyoxyethlyene, polyoxypropylene block polymers. The impurities of commercial grade Poloxamer 188, as an example, include low-molecular-weight substances (aldehydes and both formic and acetic acids), as well as 1,4-dioxane and residual ethylene oxide and propylene oxide. Most Poloxamers function in cosmetics as surfactants, emulsifying agents, cleansing agents, and/or solubilizing agents, and are used in 141 cosmetic products at concentrations from 0.005% to 20%. Poloxamers injected intravenously in animals are rapidly excreted in the urine, with some accumulation in lung, liver, brain, and kidney tissue. In humans, the plasma concentration of Poloxamer 188 (given intravenously) reached a maximum at 1 h, then reached a steady state. Poloxamers generally were ineffective in wound healing, but were effective in reducing postsurgical adhesions in several test systems. Poloxamers can cause hypercholesterolemia and hypertriglyceridemia in animals, but overall, they are relatively nontoxic to animals, with LD(50) values reported from 5 to 34.6 g/kg. Short-term intravenous doses up to 4 g/kg of Poloxamer 108 produced no change in body weights, but did result in diffuse hepatocellular vacuolization, renal tubular dilation in kidneys, and dose-dependent vacuolization of epithelial cells in the proximal convoluted tubules. A short-term inhalation toxicity study of Poloxamer 101 at 97 mg/m(3) identified slight alveolitis after 2 weeks of exposure, which subsided in the 2-week postexposure observation period. A short-term dermal toxicity study of Poloxamer 184 in rabbits at doses up to 1000 mg/kg produced slight erythema and slight intradermal inflammatory response on histological examination, but no dose-dependent body weight, hematology, blood chemistry, or organ weight changes. A 6-month feeding study in rats and dogs of Poloxamer 188 at exposures up to 5% in the diet produced no adverse effects. Likewise, Poloxamer 331 (tested up to 0.5 g/kg day(-1

  19. Effects of polyurethane on rheology performance of poly(lactic-acid) solution%聚氨酯对聚乳酸溶液流变性能的影响

    左丹英; 易长海; 甘厚磊; 陈玉波

    2012-01-01

    The rheological behaviors of blend solutions of 1,4-dioxane/poly( L-lactic-acid)/polyurethane( DO/PLLA/PU) were investigated through the Senior rotary rheometer, and the effects of PU addition on flow curves, non-Newtonian index and apparent viscosity flow activation energy of blend solutions were discussed. It was found that blended solutions were the shear thinning non-Newtonian fluids in this experiment. PU additions made the viscosities of blend solutions increase, and the higher PU content was, the larger the blend solution viscosity was, which indicated that an increment in PU content led to the dependence enhancement on shear rate. Non-Newtonian indexes of the blend solutions showed that the non-Newtonian index showed a downward trend with the increase of PU content, and as the temperature rise, the non Newtonian index of the blended solutions with the same composition also showed a downward trend,which revealed that the dependence of the viscosity of the blended solutions on shear rate was still very strong with PU content increasing as well as the temperature rising. But, the research results of the viscous flow activation energy showed that PU made the sensitivity to temperature of blend solution drop in the high shear rate. The study on the rheological properties of PLLA/PU blend solutions suggested that it was not proper to adjust the temperature in order to improve the rheological performance of blend solution during spinning processing.%采用高级旋转流变仪研究了1,4-二氧六环/左旋聚乳酸/聚氨酯(DO/PLLA/PU)共混溶液的流变性能,探讨了PU的加入对共混溶液的流动曲线、非牛顿指数及表观粘流活化能的影响.结果表明,在实验条件下,共混溶液为剪切变稀非牛顿流体,PU含量的增加使得共混溶液的表观粘度增大;共混溶液的非牛顿指数的研究表明,随着PU含量的增加,非牛顿指数呈现下降趋势,随着温度的升高,同一组成的共混溶液非牛顿指数

  20. Ground-Water Quality Data in the Coastal Los Angeles Basin Study Unit, 2006: Results from the California GAMA Program

    Mathany, Timothy M.; Land, Michael; Belitz, Kenneth

    2008-01-01

    Ground-water quality in the approximately 860 square-mile Coastal Los Angeles Basin study unit (CLAB) was investigated from June to November of 2006 as part of the Statewide Basin Assessment Project of the Ground-Water Ambient Monitoring and Assessment (GAMA) Program. The GAMA Statewide Basin Assessment was developed in response to the Ground-Water Quality Monitoring Act of 2001, and is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The Coastal Los Angeles Basin study was designed to provide a spatially unbiased assessment of raw ground-water quality within CLAB, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 69 wells in Los Angeles and Orange Counties. Fifty-five of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study area (?grid wells?). Fourteen additional wells were selected to evaluate changes in ground-water chemistry or to gain a greater understanding of the ground-water quality within a specific portion of the Coastal Los Angeles Basin study unit ('understanding wells'). Ground-water samples were analyzed for: a large number of synthetic organic constituents [volatile organic compounds (VOCs), gasoline oxygenates and their degradates, pesticides, polar pesticides, and pesticide degradates, pharmaceutical compounds, and potential wastewater-indicators]; constituents of special interest [perchlorate, N-nitrosodimethylamine (NDMA), 1,4-dioxane, and 1,2,3-trichloropropane (1,2,3-TCP)]; inorganic constituents that can occur naturally [nutrients, major and minor ions, and trace elements]; radioactive constituents [gross-alpha and gross-beta radiation, radium isotopes, and radon-222]; and microbial indicators. Naturally occurring isotopes [stable isotopic ratios of hydrogen and oxygen, and activities of tritium and carbon-14

  1. A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities.

    Aggarwal, Varinder K; Alonso, Emma; Bae, Imhyuck; Hynd, George; Lydon, Kevin M; Palmer, Matthew J; Patel, Mamta; Porcelloni, Marina; Richardson, Jeffery; Stenson, Rachel A; Studley, John R; Vasse, Jean-Luc; Winn, Caroline L

    2003-09-10

    enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH(3)CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.

  2. Ground-Water Quality Data in the Upper Santa Ana Watershed Study Unit, November 2006-March 2007: Results from the California GAMA Program

    Kent, Robert; Belitz, Kenneth

    2009-01-01

    Ground-water quality in the approximately 1,000-square-mile Upper Santa Ana Watershed study unit (USAW) was investigated from November 2006 through March 2007 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin project was developed in response to the Groundwater Quality Monitoring Act of 2001, and is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The Upper Santa Ana Watershed study was designed to provide a spatially unbiased assessment of raw ground-water quality within USAW, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 99 wells in Riverside and San Bernardino Counties. Ninety of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study unit (grid wells). Nine wells were selected to provide additional understanding of specific water-quality issues identified within the basin (understanding wells). The ground-water samples were analyzed for a large number of organic constituents (volatile organic compounds [VOCs], pesticides and pesticide degradates, pharmaceutical compounds, and potential wastewater-indicator compounds), constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], 1,4-dioxane, and 1,2,3-trichloropropane [1,2,3-TCP]), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (tritium, carbon-14, and stable isotopes of hydrogen and oxygen in water) and dissolved noble gases also were measured to help identify sources and ages of the sampled ground water. Dissolved gases, and isotopes of nitrogen gas and of dissolved nitrate also were measured in order to investigate the sources and occurrence of

  3. Groundwater-Quality Data in the Colorado River Study Unit, 2007: Results from the California GAMA Program

    Goldrath, Dara A.; Wright, Michael T.; Belitz, Kenneth

    2010-01-01

    Groundwater quality in the 188-square-mile Colorado River Study unit (COLOR) was investigated October through December 2007 as part of the Priority Basin Project of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project was developed in response to the Groundwater Quality Monitoring Act of 2001, and the U.S. Geological Survey (USGS) is the technical project lead. The Colorado River study was designed to provide a spatially unbiased assessment of the quality of raw groundwater used for public water supplies within COLOR, and to facilitate statistically consistent comparisons of groundwater quality throughout California. Samples were collected from 28 wells in three study areas in San Bernardino, Riverside, and Imperial Counties. Twenty wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the Study unit; these wells are termed 'grid wells'. Eight additional wells were selected to evaluate specific water-quality issues in the study area; these wells are termed `understanding wells.' The groundwater samples were analyzed for organic constituents (volatile organic compounds [VOC], gasoline oxygenates and degradates, pesticides and pesticide degradates, pharmaceutical compounds), constituents of special interest (perchlorate, 1,4-dioxane, and 1,2,3-trichlorpropane [1,2,3-TCP]), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), and radioactive constituents. Concentrations of naturally occurring isotopes (tritium, carbon-14, and stable isotopes of hydrogen and oxygen in water), and dissolved noble gases also were measured to help identify the sources and ages of the sampled groundwater. In total, approximately 220 constituents and water-quality indicators were investigated. Quality-control samples (blanks, replicates, and matrix spikes) were collected at

  4. One barbiturate and two solvated thiobarbiturates containing the triply hydrogen-bonded ADA/DAD synthon, plus one ansolvate and three solvates of their coformer 2,4-diaminopyrimidine.

    Hützler, Wilhelm Maximilian; Egert, Ernst; Bolte, Michael

    2016-09-01

    A path to new synthons for application in crystal engineering is the replacement of a strong hydrogen-bond acceptor, like a C=O group, with a weaker acceptor, like a C=S group, in doubly or triply hydrogen-bonded synthons. For instance, if the C=O group at the 2-position of barbituric acid is changed into a C=S group, 2-thiobarbituric acid is obtained. Each of the compounds comprises two ADA hydrogen-bonding sites (D = donor and A = acceptor). We report the results of cocrystallization experiments of barbituric acid and 2-thiobarbituric acid, respectively, with 2,4-diaminopyrimidine, which contains a complementary DAD hydrogen-bonding site and is therefore capable of forming an ADA/DAD synthon with barbituric acid and 2-thiobarbituric acid. In addition, pure 2,4-diaminopyrimidine was crystallized in order to study its preferred hydrogen-bonding motifs. The experiments yielded one ansolvate of 2,4-diaminopyrimidine (pyrimidine-2,4-diamine, DAPY), C4H6N4, (I), three solvates of DAPY, namely 2,4-diaminopyrimidine-1,4-dioxane (2/1), 2C4H6N4·C4H8O2, (II), 2,4-diaminopyrimidine-N,N-dimethylacetamide (1/1), C4H6N4·C4H9NO, (III), and 2,4-diaminopyrimidine-1-methylpyrrolidin-2-one (1/1), C4H6N4·C5H9NO, (IV), one salt of barbituric acid, viz. 2,4-diaminopyrimidinium barbiturate (barbiturate is 2,4,6-trioxopyrimidin-5-ide), C4H7N4(+)·C4H3N2O3(-), (V), and two solvated salts of 2-thiobarbituric acid, viz. 2,4-diaminopyrimidinium 2-thiobarbiturate-N,N-dimethylformamide (1/2) (2-thiobarbiturate is 4,6-dioxo-2-sulfanylidenepyrimidin-5-ide), C4H7N4(+)·C4H3N2O2S(-)·2C3H7NO, (VI), and 2,4-diaminopyrimidinium 2-thiobarbiturate-N,N-dimethylacetamide (1/2), C4H7N4(+)·C4H3N2O2S(-)·2C4H9NO, (VII). The ADA/DAD synthon was succesfully formed in the salt of barbituric acid, i.e. (V), as well as in the salts of 2-thiobarbituric acid, i.e. (VI) and (VII). In the crystal structures of 2,4-diaminopyrimidine, i.e. (I)-(IV), R2(2)(8) N-H...N hydrogen-bond motifs are preferred and, in two

  5. Ground-Water Quality Data in the San Fernando-San Gabriel Study Unit, 2005 - Results from the California GAMA Program

    Land, Michael; Belitz, Kenneth

    2008-01-01

    Ground-water quality in the approximately 460 square mile San Fernando-San Gabriel study unit (SFSG) was investigated between May and July 2005 as part of the Priority Basin Assessment Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Assessment Project was developed in response to the Groundwater Quality Monitoring Act of 2001 and is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The San Fernando-San Gabriel study was designed to provide a spatially unbiased assessment of raw ground-water quality within SFSG, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 52 wells in Los Angeles County. Thirty-five of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study area (grid wells), and seventeen wells were selected to aid in the evaluation of specific water-quality issues or changes in water chemistry along a historic ground-water flow path (understanding wells). The ground-water samples were analyzed for a large number of synthetic organic constituents [volatile organic compounds (VOCs), pesticides and pesticide degradates], constituents of special interest [perchlorate, N-nitrosodimethylamine (NDMA), 1,2,3-trichloropropane (1,2,3-TCP), and 1,4-dioxane], naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (tritium, and carbon-14, and stable isotopes of hydrogen, oxygen, and carbon), and dissolved noble gases also were measured to help identify the source and age of the sampled ground water. Quality-control samples (blanks, replicates, samples for matrix spikes) were collected at approximately one-fifth (11 of 52) of the wells, and the results for these

  6. Status of groundwater quality in the Coastal Los Angeles Basin, 2006-California GAMA Priority Basin Project

    Goldrath, Dara; Fram, Miranda S.; Land, Michael; Belitz, Kenneth

    2012-01-01

    -concentration greater than (>) 1.0 indicates a concentration greater than a benchmark, and a relative-concentration less than or equal to (≤) 1.0 indicates a concentration equal to or less than a benchmark. Relative-concentrations of organic and special-interest constituents [perchlorate, N-nitrosodimethylamine (NDMA), 1,2,3-trichloropropane (1,2,3-TCP), and 1,4-dioxane] were classified as "high" (relative-concentration>1.0), "moderate" (0.5status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifer system with a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches-grid-based and spatially weighted-were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the CLAB study unit (within 90-percent confidence intervals). Inorganic constituents with human-health benchmarks were detected at high relative-concentrations in 5.6 percent of the primary aquifer system and moderate in 26 percent. High aquifer-scale proportion of inorganic constituents primarily reflected high aquifer-scale proportions of arsenic (1.9 percent), nitrate (1.9 percent), and uranium (1.2 percent). Inorganic constituents with secondary maximum contaminant levels (SMCL) were detected at high relative-concentrations in 18 percent of the primary aquifer system and moderate in 47 percent. The constituents present at high relative-concentrations included total dissolved solids (1.9 percent), manganese (15 percent), and iron (9.4 percent). Relative-concentrations of organic constituents (one or more) were high in 3

  7. Poly(lactic-co-glycolic acid)/tricalcium phosphate scaffolds prepared by rapid prototyping technology for the repair of radial defects in rabbits%快速成型聚乳酸-聚羟乙酸/磷酸三钙支架修复兔桡骨缺损

    孙梁; 熊卓

    2011-01-01

    背景:理想的骨修复材料除必须具有生物相容性、可吸收性、利于血管化及迅速被新生组织替代的孔隙率,还需要有与骨组织相似三维结构.目的:检验快速成型工艺制作的聚乳酸-聚羟乙酸/磷酸三钙支架复合骨形态发生蛋白修复兔桡骨缺损的效果.方法:将乳酸乙醇酸共聚物溶于1,4-二氧六环中并混合粉末状磷酸三钙制备成液态的浆料,放入生物材料快速成形机TissFormTM制备出直径5 mm,长15 mm的圆柱形人工骨载体材料.按每个材料15 mg的标准,采用预湿、负压复合骨形态发生蛋白、冻干3步处理,制备出活性人工骨材料.健康新西兰大白兔20只,制备右前肢桡骨中上段15 mm骨缺损模型,实验组和对照组分别植入复合骨形态发生蛋白的活性人工骨和未复合骨形态发生蛋白的单纯支架.通过影像学、组织学、材料降解及骨密度评价修复兔桡骨缺损的效果.结果与结论:12周时实验组骨缺损愈合,新生骨痂连接缺损断端并塑形,支架材料近于完全降解,各检测指标与对照组比较差异均有显著性意义,对照组骨缺损内未见新骨形成.结果表明复合骨形态发生蛋白的聚乳酸-聚羟乙酸/磷酸三钙支架可以很好的修复兔15 mm骨缺损,且降解速度与成骨速度匹配良好.%BACKGROUND:The ideal bone repair materials must be biocompatible and absorbable, have the porosity that is conducive to the vascularization and rapidly replaced by new tissue, as well as a three-dimensional structu re similar to bone tissue.OBJECTIVE:To test the effect of poly(lactic-co-glycolic acid )/tricalcium phosphate (PLGA/TCP) scaffolds prepared by rapid prototyping technology loaded with bone morphogenetic protein in the repair of radial defect in rabbits.METHODS:The lactic acid/glycolic acid copolymer dissolved in 1,4-dioxane and mixed with calcium phosphate powder to prepare a liquid slurry, then placing into a biomaterial rapid

  8. A Development of Rapid, Practical and Selective Process for Preparation of Z-Oximes

    Kim, Bo Ram; Sung, Gi Hyeon; Yoon, Yongjin [Gyeongsang National Univ., Jinju (Korea, Republic of); Kim, Jeumjong [Electronic and Telecommunications Research Institute, Daejeon (Korea, Republic of)

    2013-04-15

    Table 1, compound 1a was treated with hydroxylamine hydrochloride in the presence of potassium carbonate in refluxing 1,4-dioxane to afford the corresponding ketoxime 2a in excellent yield. Acetophenone oxime (2a) was also obtained by the use of ethanol or methanol as the solvent at room temperature or at reflux temperature in excellent yields (Entries 9-12 in Table 1), whereas the side reaction was detected for the reaction of 1a with hydroxylamine hydrochloride in the presence of potassium carbonate in refluxing water. According to our preliminary results, we selected the methanol as the solvent due to short reaction time and low price. As shown in Table 2, aliphatic and aromatic ketones except for benzophenone (1f) were rapidly and selectively converted to the corresponding Z-oximes in good yields. Also, various types of aromatic aldehydes 1g. with electron donating and withdrawing groups were rapidly and selectively converted to the corresponding Zaldoximes in good to excellent yields. In our condition, the oximation of aldehydes is more Z-selective than the oximation of ketones. In order to evaluate the utility of industrial process, we examined the one mole scale reaction. Treatment of one mole acetophenone (1a) and benzaldehyde (1g) with hydroxylamine hydrochloride and potassium carbonate in methanol afforded the corresponding oximes 2a (E/Z ratio = 15:85, 92%) and 2g (E/Z ratio = 10:90, 92%). The structures of the oximes were established by IR and NMR. In the case of ketoximes, we distinguished two isomers by using the carbon chemical shifts of C=NOH, that is, the chemical shifts of the Z-isomer are detected higher field than the chemical shifts of the E-isomer. In the case of aldoximes, E/Z-isomers were distinguished by using the proton chemical shifts of HC=N for aldoximes, that is, the proton chemical shifts of the Z-isomer are detected lower field than the chemical shifts of the E-isomer. In summury, we have demonstrated the rapid and convenient oximation of

  9. NTP Toxicology and Carcinogenesis Studies of Glycidol (CAS No. 556-52-5) In F344/N Rats and B6C3F1 Mice (Gavage Studies).

    1990-03-01

    Glycidol is a viscous liquid that is used as a stabilizer in the manufacture of vinyl polymers, as an additive for oil and synthetic hydraulic fluids, and as a diluent in some epoxy resins. NTP Toxicology and Carcinogenesis studies were conducted by administering glycidol (94% pure, containing 1.2% 3-methoxy-1,2-propanediol, 0.4% 3-chloro-1,2-propanediol, 2.8% diglycidyl ether, and 1.1% 2,6-dimethanol-1,4-dioxane) in water by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, Chinese hamster ovary (CHO) cells, Drosophila melanogaster, and the bone marrow of male B6C3F1 mice. Sixteen-Day Studies: Glycidol doses for groups of five rats or five mice of each sex ranged from 37.5 to 600 mg/kg; vehicle controls received distilled water. All rats that received 600 mg/kg died between days 3 and 13. Edema and degeneration of the epididymal stroma, atrophy of the testis, and granulomatous inflammation of the epididymis occurred in males that received 300 mg/kg. All mice that received 600 mg/kg and two males and two females that received 300 mg/kg died by day 4 of the studies. Focal demyelination in the medulla and thalamus of the brain occurred in all female mice that received 300 mg/kg. Thirteen-Week Studies: Doses for groups of 10 rats ranged from 25 to 400 mg/kg, and doses for groups of 10 mice ranged from 19 to 300 mg/kg; vehicle controls received distilled water. All rats that received 400 mg/kg died by week 2; three males and one female that received 200 mg/kg died during weeks 11-12. Final mean body weights of male rats that received 50, 100, or 200 mg/kg were 96%-85% that of vehicle controls; final mean body weights of female rats receiving the same doses were 95%-89% that of vehicle controls. Sperm count and sperm motility were reduced in male rats that received 100 or 200 mg/kg. Necrosis of the cerebellum, demyelineation in the medulla of the brain

  10. 羟基磷灰石/胶原/聚乳酸三维多孔储存式药物控释载体的制备及其表征%Preparation and characterization of hydroxyapatite/collagen/poly-L-lactic acid three-dimensional porous reservoir type drug carrier for controlled release

    王振林; 万涛; 闫玉华

    2006-01-01

    羟基磷灰石在胶原基质上生成并以其晶格c轴择优取向排列.②羟基磷灰石/胶原/聚乳酸药物载体具有适合药物控释的孔结构和和物理性能.③模型药物的体外释放试验表明药物在达到85%释放率之前近似为零级缓慢释放.结论:羟基磷灰石/胶原复合材料与天然骨类似,羟基磷灰石/胶原/聚乳酸储存式载体能达到控制释放的目的.%BACKGROUND: In the clinical therapy for orthopedic diseases, the traditional administration easily induces the great fluctuation of drug concentration and side effect, and implanted drug carrier material hydroxyapatite (Hap) cannot be used in human's load bearing parts due to its poor mechanical performances, and poly-L-lactic acid (PLLA) is effortlessly degraded to acid byproducts. Drug carriers made from Hap/PLLA are supposed to not only persist releasing drug onto the lesion and reduce the side effect,but also obtain strength enhancement and eliminate tissue inflammatory reaction in favor of bone regeneration.OBJECTIVE: To observe the preparation of absorbable target control-release drug carrier and simulate the application of drugs.DESIGN: Observation trial.SETTING: Chongqing Institute of Technology and Wuhan University of Technology.MATERIALS: Tails of albino rats and PLLA (offered by Biological Center of Wuhan University of Technology), pepsin (1:10 000, Sigma company), Ca(OH)2, strong phosphoric, NaOH, glacial acetic acid, phosphate buffer (pH=7.4), 1,4-dioxane, absolute alcohol (Analytical reagent available on market).METHODS: The experiment was carried out in Chongqing Institute of Technology and Wuhan University of Technology. ①Type Ⅰ collagen (Col)was prepared by acid dissolution and alkali purification methods. Hap/Col bone-like biomimetic composite was synthesized through self-assembly mechanism of materials simulating in vitro biomineralization process of nature bone. X ray diffraction analysis and transmission electron microscope were applied to observe the