The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Lewis Semprini - One of the best experts on this subject based on the ideXlab platform.
-
bioaugmentation with butane utilizing microorganisms to promote in situ cometabolic treatment of 1 1 1 trichloroethane and 1 1 dichloroethene
Journal of Contaminant Hydrology, 2009Co-Authors: Lewis Semprini, Mark E Dolan, Gary D Hopkins, Perry L MccartyAbstract:Abstract A field study was performed to evaluate the potential for in-situ aerobic cometabolism of 1,1,1-trichloroethane (1,1,1-TCA) through bioaugmentation with a butane enrichment culture containing predominantly two Rhodococcus sp. strains named 179BP and 183BP that could cometabolize 1,1,1-TCA and 1,1-dicholoroethene (1,1-DCE). Batch tests indicated that 1,1-DCE was more rapidly transformed than 1,1,1-TCA by both strains with 183BP being the most effective organism. This second in a series of bioaugmentation field studies was conducted in the saturated zone at the Moffett Field In Situ Test Facility in California. In the previous test, bioaugmentation with an enrichment culture containing the 183BP strain achieved short term in situ treatment of 1,1-DCE, 1,1,1-TCA, and 1,1-dichloroethane (1,1-DCA). However, transformation activity towards 1,1,1-TCA was lost over the course of the study. The goal of this second study was to determine if more effective and long-term treatment of 1,1,1-TCA could be achieved through bioaugmentation with a highly enriched culture containing 179BP and 183BP strains. Upon bioaugmentation and continuous addition of butane and dissolved oxygen and or hydrogen peroxide as sources of dissolved oxygen, about 70% removal of 1,1,1-TCA was initially achieved. 1,1-DCE that was present as a trace contaminant was also effectively removed (∼ 80%). No removal of 1,1,1-TCA resulted in a control test leg that was not bioaugmented, although butane and oxygen consumption by the indigenous populations was similar to that in the bioaugmented test leg. However, with prolonged treatment, removal of 1,1,1-TCA in the bioaugmented leg decreased to about 50 to 60%. Hydrogen pexoxide (H 2 O 2 ) injection increased dissolved oxygen concentration, thus permitting more butane addition into the test zone, but more effective 1,1,1-TCA treatment did not result. The results showed bioaugmentation with the enrichment cultures was effective in enhancing the cometabolic treatment of 1,1,1-TCA and low concentrations of 1,1-DCE over the entire period of the 50-day test. Compared to the first season of testing, cometabolic treatment of 1,1,1-TCA was not lost. The better performance achieved in the second season of testing may be attributed to less 1,1-DCE transformation product toxicity, more effective addition of butane, and bioaugmentation with the highly enriched dual culture.
-
bioaugmentation of butane utilizing microorganisms for the in situ cometabolic treatment of 1 1 dichloroethene 1 1 dichloroethane and 1 1 1 trichloroethane
European Journal of Soil Biology, 2007Co-Authors: Lewis Semprini, Mark E Dolan, Gary D Hopkins, Maureen A Mathias, Perry L MccartyAbstract:Bioaugmentation of microbial cultures is a potential method to enhance the performance of in situ bioremediation. In this study we evaluated the bioaugmentation of aerobic microorganisms that grow on butane that can transform chlorinated aliphatic hydrocarbon (CAH) mixtures, such as 1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichhloroethane (1,1-DCA) and 1,1-dichloroethene (1,1-DCE). This mixture of contaminants is of interest, since 1,1,1-TCA was a frequently used solvent at Department of Defense (DoD) facilities in the United States, and 1,1-DCE and 1,1-DCA are abiotic and biotic transformation products of 1,1,1-TCA. Kinetic studies with butane grown enrichment cultures and pure cultures isolated from the enrichment culture showed effective transformation of mixtures of these contaminants, with 1,1-DCE most rapidly transformed, followed by 1,1-DCA, and 1,1,1-TCA. In laboratory microcosm batch experiments, with aquifer material and groundwater from the field site, microcosms bioaugmented with mixed and pure cultures outperformed microcosms where indigenous butane-utilizing microorganisms were stimulated. The microcosm tests were consistent with the kinetics from mixed and pure cultures. Field studies were conducted in the saturated zone at the Moffett Field In Situ Test Facility in California. Tests were performed in an indigenous test leg along with a bioaugmented test leg, and the bioaugmented test leg outperformed the indigenous test leg. In the bioaugmented leg, 1,1-DCE was more effectively transformed, followed by 1,1-DCA, and 1,1,1-TCA, consistent with the results from laboratory kinetic studies and microcosm studies.
-
laboratory field and modeling studies of bioaugmentation of butane utilizing microorganisms for the in situ cometabolic treatment of 1 1 dichloroethene 1 1 dichloroethane and 1 1 1 trichloroethane
Advances in Water Resources, 2007Co-Authors: Lewis Semprini, Mark E Dolan, Gary D Hopkins, Maureen A Mathias, Perry L MccartyAbstract:Abstract A series of laboratory, field, and modeling studies were performed evaluating the potential for in situ aerobic cometabolism of chlorinated aliphatic hydrocarbon (CAH) mixtures, including 1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichloroethane (1,1-DCA) and 1,1-dichloroethene (1,1-DCE) by bioaugmented microorganisms that grew on butane. A butane-grown bioaugmentation culture, primarily comprised of a Rhodococcus sp., was developed that effectively transformed mixtures of the three CAHs, under subsurface nutrient conditions. Microcosm experiments and modeling studies showed rapid transformation of 1,1-DCE with high transformation product toxicity and weak inhibition by butane, while 1,1,1-TCA was much more slowly transformed and strongly inhibited by butane. Field studies were conducted in the saturated zone at the Moffett Field In-Situ Test Facility in California. In the bioaugmented test leg, 1,1-DCE was most effectively transformed, followed by 1,1-DCA, and 1,1,1-TCA, consistent with the results from the laboratory studies. A 1-D reactive/transport code simulated the field responses during the early stages of testing (first 20 days), with the following extents of removal achieved at the first monitoring well; 1,1-DCE (∼97%), 1,1-DCA (∼77%), and 1,1,1-TCA (∼36%), with little or no CAH transformation observed beyond the first monitoring well. As time proceeded, decreased performance was observed. The modeling analysis indicated that this loss of performance may have been associated with 1,1-DCE transformation toxicity combined with the limited addition of butane as a growth substrate with longer pulse cycles. When shorter pulse cycles were reinitiated after 40 days of operation, 1,1-DCE transformation was restored and the following transformation extents were achieved; 1,1-DCE (∼94%), 1,1-DCA (∼8%), and 1,1,1-TCA (∼0%), with some CAH transformation occurring past the first monitoring well. Modeling analysis of this period indicated that the bioaugmented culture was likely not the dominant butane-utilizing microorganism present. This was consistent with observations in the indigenous leg during this period that showed effective butane utilization and the following extents of transformation: 1,1-DCE (∼86 %), 1,1-DCA (∼5%), and 1,1,1-TCA (∼0%). The combination of lab and field scale studies and supporting modeling provide a means of evaluating the performance of bioaugmentation and the cometabolic treatment of CAH mixtures.
-
kinetic and inhibition studies for the aerobic cometabolism of 1 1 1 trichloroethane 1 1 dichloroethylene and 1 1 dichloroethane by a butane grown mixed culture
Biotechnology and Bioengineering, 2002Co-Authors: Young Hoon Kim, Daniel J Arp, Lewis SempriniAbstract:Batch kinetic and inhibition studies were performed for the aerobic cometabolism of 1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichloroethylene (1,1-DCE), and 1,1-dichloroethane (1,1-DCA) by a butane-grown mixed culture. These chlorinated aliphatic hydrocarbons (CAHs) are often found together as cocontaminants in groundwater. The maximum degradation rates (k(max)) and half-saturation coefficients (K(s)) were determined in single compound kinetic tests. The highest k(max) was obtained for butane (2.6 micromol/mg TSS/h) followed by 1,1-DCE (1.3 micromol/mg TSS/h), 1,1-DCA (0.49 micromol/mg TSS/h), and 1,1,1-TCA (0.19 micromol/mg TSS/h), while the order of K(s) from the highest to lowest was 1,1-DCA (19 microM), butane (19 microM), 1,1,1-TCA (12 microM) and 1,1-DCE (1.5 microM). The inhibition types were determined using direct linear plots, while inhibition coefficients (K(ic) and K(iu)) were estimated by nonlinear least squares regression (NLSR) fits to the kinetic model of the identified inhibition type. Two different inhibition types were observed among the compounds. Competitive inhibition among CAHs was indicated from direct linear plots, and the CAHs also competitively inhibited butane utilization. 1,1-DCE was a stronger inhibitor than the other CAHs. Mixed inhibition of 1,1,1-TCA, 1,1-DCA, and 1,1-DCE transformations by butane was observed. Thus, both competitive and mixed inhibitions are important in cometabolism of CAHs by this butane culture. For competitive inhibition between CAHs, the ratio of the K(s) values was a reasonable indicator of competitive inhibition observed. Butane was a strong inhibitor of CAH transformation, having a much lower inhibition coefficient than the K(s) value of butane, while the CAHs were weak inhibitors of butane utilization. Model simulations of reactor systems where both the growth substrate and the CAHs are present indicate that reactor performance is significantly affected by inhibition type and inhibition coefficients. Thus, determining inhibition type and measuring inhibition coefficients is important in designing CAH treatment systems.
Mariana Teodorescu - One of the best experts on this subject based on the ideXlab platform.
-
isothermal vapour liquid equilibria for pentan 3 one 1 4 dichlorobutane trichloromethane 1 1 1 trichloroethane 1 1 2 2 tetrachloroethane binary mixtures
Fluid Phase Equilibria, 1998Co-Authors: Mariana Teodorescu, Karel Aim, Ivan WichterleAbstract:Abstract Isothermal vapour–liquid equilibrium data are reported for binary mixtures containing pentan-3-one with 1,4-dichlorobutane from 343.15 to 373.15 K, trichloromethane from 313.15 to 343.15 K, 1,1,1-trichloroethane from 323.15 to 353.15 K, and 1,1,2,2-tetrachloroethane from 343.15 to 373.15 K. A modified equilibrium still is described. The experimental data were correlated using the Redlich–Kister, Wilson and NRTL models by means of the maximum likelihood method.
-
densities and excess volumes of pentan 3 one 1 2 dichloroethane 1 3 dichloropropane 1 4 dichlorobutane trichloromethane 1 1 1 trichloroethane 1 1 2 2 tetrachloroethane binary mixtures at 298 15 k
Fluid Phase Equilibria, 1998Co-Authors: Mariana Teodorescu, J LinekAbstract:Abstract Densities and excess molar volumes, VE, of pentan-3-one+1,2-dichloroethane, +1,3-dichloropropane, +1,4-dichlorobutane, +trichloromethane, +1,1,1-trichloroethane, +1,1,2,2-tetrachloroethane are presented at 298.15 K and atmospheric pressure over the whole composition range. These measurements were performed in order to complement the data on VLE [M. Teodorescu, A. Barhala, O. Landauer, ELDATA: Int. Electron. J. Physico-Chem. Data 3 (1997) 101–108; M. Teodorescu, K. Aim, I. Wichterle, Fluid Phase Equilibria, in press] and to investigate the influence of molecular structure of these chloroalkanes on VE in their mixtures with pentan-3-one. At this temperature, VE was found to be slightly positive at high mole fractions and slightly negative at low mole fractions of 1,2-dichloroethane in case of the first system. For all the other systems, VE was negative. The VE experimental results were correlated using the fourth-order Redlich–Kister equation, and the maximum likelihood procedure was applied for evaluating the adjustable parameters.
Perry L Mccarty - One of the best experts on this subject based on the ideXlab platform.
-
bioaugmentation with butane utilizing microorganisms to promote in situ cometabolic treatment of 1 1 1 trichloroethane and 1 1 dichloroethene
Journal of Contaminant Hydrology, 2009Co-Authors: Lewis Semprini, Mark E Dolan, Gary D Hopkins, Perry L MccartyAbstract:Abstract A field study was performed to evaluate the potential for in-situ aerobic cometabolism of 1,1,1-trichloroethane (1,1,1-TCA) through bioaugmentation with a butane enrichment culture containing predominantly two Rhodococcus sp. strains named 179BP and 183BP that could cometabolize 1,1,1-TCA and 1,1-dicholoroethene (1,1-DCE). Batch tests indicated that 1,1-DCE was more rapidly transformed than 1,1,1-TCA by both strains with 183BP being the most effective organism. This second in a series of bioaugmentation field studies was conducted in the saturated zone at the Moffett Field In Situ Test Facility in California. In the previous test, bioaugmentation with an enrichment culture containing the 183BP strain achieved short term in situ treatment of 1,1-DCE, 1,1,1-TCA, and 1,1-dichloroethane (1,1-DCA). However, transformation activity towards 1,1,1-TCA was lost over the course of the study. The goal of this second study was to determine if more effective and long-term treatment of 1,1,1-TCA could be achieved through bioaugmentation with a highly enriched culture containing 179BP and 183BP strains. Upon bioaugmentation and continuous addition of butane and dissolved oxygen and or hydrogen peroxide as sources of dissolved oxygen, about 70% removal of 1,1,1-TCA was initially achieved. 1,1-DCE that was present as a trace contaminant was also effectively removed (∼ 80%). No removal of 1,1,1-TCA resulted in a control test leg that was not bioaugmented, although butane and oxygen consumption by the indigenous populations was similar to that in the bioaugmented test leg. However, with prolonged treatment, removal of 1,1,1-TCA in the bioaugmented leg decreased to about 50 to 60%. Hydrogen pexoxide (H 2 O 2 ) injection increased dissolved oxygen concentration, thus permitting more butane addition into the test zone, but more effective 1,1,1-TCA treatment did not result. The results showed bioaugmentation with the enrichment cultures was effective in enhancing the cometabolic treatment of 1,1,1-TCA and low concentrations of 1,1-DCE over the entire period of the 50-day test. Compared to the first season of testing, cometabolic treatment of 1,1,1-TCA was not lost. The better performance achieved in the second season of testing may be attributed to less 1,1-DCE transformation product toxicity, more effective addition of butane, and bioaugmentation with the highly enriched dual culture.
-
bioaugmentation of butane utilizing microorganisms for the in situ cometabolic treatment of 1 1 dichloroethene 1 1 dichloroethane and 1 1 1 trichloroethane
European Journal of Soil Biology, 2007Co-Authors: Lewis Semprini, Mark E Dolan, Gary D Hopkins, Maureen A Mathias, Perry L MccartyAbstract:Bioaugmentation of microbial cultures is a potential method to enhance the performance of in situ bioremediation. In this study we evaluated the bioaugmentation of aerobic microorganisms that grow on butane that can transform chlorinated aliphatic hydrocarbon (CAH) mixtures, such as 1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichhloroethane (1,1-DCA) and 1,1-dichloroethene (1,1-DCE). This mixture of contaminants is of interest, since 1,1,1-TCA was a frequently used solvent at Department of Defense (DoD) facilities in the United States, and 1,1-DCE and 1,1-DCA are abiotic and biotic transformation products of 1,1,1-TCA. Kinetic studies with butane grown enrichment cultures and pure cultures isolated from the enrichment culture showed effective transformation of mixtures of these contaminants, with 1,1-DCE most rapidly transformed, followed by 1,1-DCA, and 1,1,1-TCA. In laboratory microcosm batch experiments, with aquifer material and groundwater from the field site, microcosms bioaugmented with mixed and pure cultures outperformed microcosms where indigenous butane-utilizing microorganisms were stimulated. The microcosm tests were consistent with the kinetics from mixed and pure cultures. Field studies were conducted in the saturated zone at the Moffett Field In Situ Test Facility in California. Tests were performed in an indigenous test leg along with a bioaugmented test leg, and the bioaugmented test leg outperformed the indigenous test leg. In the bioaugmented leg, 1,1-DCE was more effectively transformed, followed by 1,1-DCA, and 1,1,1-TCA, consistent with the results from laboratory kinetic studies and microcosm studies.
-
laboratory field and modeling studies of bioaugmentation of butane utilizing microorganisms for the in situ cometabolic treatment of 1 1 dichloroethene 1 1 dichloroethane and 1 1 1 trichloroethane
Advances in Water Resources, 2007Co-Authors: Lewis Semprini, Mark E Dolan, Gary D Hopkins, Maureen A Mathias, Perry L MccartyAbstract:Abstract A series of laboratory, field, and modeling studies were performed evaluating the potential for in situ aerobic cometabolism of chlorinated aliphatic hydrocarbon (CAH) mixtures, including 1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichloroethane (1,1-DCA) and 1,1-dichloroethene (1,1-DCE) by bioaugmented microorganisms that grew on butane. A butane-grown bioaugmentation culture, primarily comprised of a Rhodococcus sp., was developed that effectively transformed mixtures of the three CAHs, under subsurface nutrient conditions. Microcosm experiments and modeling studies showed rapid transformation of 1,1-DCE with high transformation product toxicity and weak inhibition by butane, while 1,1,1-TCA was much more slowly transformed and strongly inhibited by butane. Field studies were conducted in the saturated zone at the Moffett Field In-Situ Test Facility in California. In the bioaugmented test leg, 1,1-DCE was most effectively transformed, followed by 1,1-DCA, and 1,1,1-TCA, consistent with the results from the laboratory studies. A 1-D reactive/transport code simulated the field responses during the early stages of testing (first 20 days), with the following extents of removal achieved at the first monitoring well; 1,1-DCE (∼97%), 1,1-DCA (∼77%), and 1,1,1-TCA (∼36%), with little or no CAH transformation observed beyond the first monitoring well. As time proceeded, decreased performance was observed. The modeling analysis indicated that this loss of performance may have been associated with 1,1-DCE transformation toxicity combined with the limited addition of butane as a growth substrate with longer pulse cycles. When shorter pulse cycles were reinitiated after 40 days of operation, 1,1-DCE transformation was restored and the following transformation extents were achieved; 1,1-DCE (∼94%), 1,1-DCA (∼8%), and 1,1,1-TCA (∼0%), with some CAH transformation occurring past the first monitoring well. Modeling analysis of this period indicated that the bioaugmented culture was likely not the dominant butane-utilizing microorganism present. This was consistent with observations in the indigenous leg during this period that showed effective butane utilization and the following extents of transformation: 1,1-DCE (∼86 %), 1,1-DCA (∼5%), and 1,1,1-TCA (∼0%). The combination of lab and field scale studies and supporting modeling provide a means of evaluating the performance of bioaugmentation and the cometabolic treatment of CAH mixtures.
J Linek - One of the best experts on this subject based on the ideXlab platform.
-
densities and excess volumes of pentan 3 one 1 2 dichloroethane 1 3 dichloropropane 1 4 dichlorobutane trichloromethane 1 1 1 trichloroethane 1 1 2 2 tetrachloroethane binary mixtures at 298 15 k
Fluid Phase Equilibria, 1998Co-Authors: Mariana Teodorescu, J LinekAbstract:Abstract Densities and excess molar volumes, VE, of pentan-3-one+1,2-dichloroethane, +1,3-dichloropropane, +1,4-dichlorobutane, +trichloromethane, +1,1,1-trichloroethane, +1,1,2,2-tetrachloroethane are presented at 298.15 K and atmospheric pressure over the whole composition range. These measurements were performed in order to complement the data on VLE [M. Teodorescu, A. Barhala, O. Landauer, ELDATA: Int. Electron. J. Physico-Chem. Data 3 (1997) 101–108; M. Teodorescu, K. Aim, I. Wichterle, Fluid Phase Equilibria, in press] and to investigate the influence of molecular structure of these chloroalkanes on VE in their mixtures with pentan-3-one. At this temperature, VE was found to be slightly positive at high mole fractions and slightly negative at low mole fractions of 1,2-dichloroethane in case of the first system. For all the other systems, VE was negative. The VE experimental results were correlated using the fourth-order Redlich–Kister equation, and the maximum likelihood procedure was applied for evaluating the adjustable parameters.
Atsuhiro Osuka - One of the best experts on this subject based on the ideXlab platform.
-
structural and aromaticity control of 34 octaphyrin 1 1 1 0 1 1 1 0 by protonation and deprotonation
Asian Journal of Organic Chemistry, 2017Co-Authors: Koji Naoda, Atsuhiro OsukaAbstract:The structural and aromaticity control of hexakis(pentafluorophenyl) [34]octaphyrin(1.1.1.0.1.1.1.0) 1 was examined by protonation and deprotonation. Protonation of 1 with methanesulfonic acid (MSA) induced a structural change from a figure-eight to a rectangular shape, accompanied by an aromaticity change from nonaromatic to strong Huckel aromatic. Deprotonation of 1 with tetrabutylammonium difluorotriphenylsilicate (TBAT) or fluoride (TBAF) produced a mono-deprotonated species with a similar figure-eight conformation and nonaromaticity.
-
neutral radical and singlet biradical forms of meso free keto and diketo hexaphyrins 1 1 1 1 1 1 effects on aromaticity and photophysical properties
Journal of the American Chemical Society, 2011Co-Authors: Masatoshi Ishida, Atsuhiro Osuka, Jae Yoon Shin, Jong Min Lim, Byung Sun Lee, Min Chul Yoon, Taro Koide, Jonathan L Sessler, Dongho KimAbstract:We have investigated the electronic structures and photophysical properties of 5,10,20,25-tetrakis(pentafluorophenyl)-substituted hexaphyrin(1.1.1.1.1.1) (1) and its meso-keto (2) and meso-diketo derivatives (3) using various spectroscopic measurements. In conjunction with theoretical calculations, these analyses revealed fundamental structure–property relationships within this series, including unusual ground-state electronic structures with neutral, monoradical, and singlet biradical character. The meso-free species 1 is a representative 26 π-electron aromatic compound and shows characteristic spectroscopic features, including a sharp Soret band, well-defined Q-like bands, and a moderately long excited state lifetime (τ = 138 ps). In contrast, the meso-keto derivative 2 displays features characteristic of a neutral monoradical species at the ground state, including the presence of lower energy absorption bands in the NIR spectral region and a relatively short excited-state lifetime (13.9 ps). The meso-d...
-
n fusion reaction sequence of heptaphyrin 1 1 1 1 1 1 1 singly doubly and quadruply n fused heptaphyrins
Chemistry: A European Journal, 2006Co-Authors: Shohei Saito, Atsuhiro OsukaAbstract:meso-Heptakis(pentafluorophenyl) heptaphyrin(1.1.1.1.1.1.1) (1) was prepared by a stepwise route in 39 % yield and its unique N-fusion reaction (NFR) sequence has been revealed; this reaction leads to singly-, doubly-, and quadruply N-fused heptaphyrins (4, 5, and 6) in good yields. These transformations are facilitated by the inherent conformational distortion of 1 as well as the distorted, folded conformations of N-fused heptaphyrins 4 and 5. The proximate arrangement of the three pyrrole units in 6 allowed for the formation of the tripyrrolylboron(III) complexes 7, 8, and 9 with unique coordination features. Molecules 1, 5, and 9 were structurally characterized by X-ray crystallography. In addition, the boron complexes 7, 8, and 9 displayed weak but distinct fluorescence in the near infrared region.
