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Search Results: 1 - 10 of 1481 matches for " SE Murialdo "
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Effect of pH and inoculum size on pentachlorophenol degradation by Pseudomonas sp.
EA Wolski, SE Murialdo, JF Gonzalez
Water SA , 2005,
Abstract: Pentachlorophenol (PCP) is a toxic compound which is used as a fungicide, bactericide, herbicide and chemical intermediate. Because of its toxicity, there is a need to decontaminate the PCP-laden soils and bioremediation is a very useful alternative to conventional clean-up methods. The success of this depends on finding strains able to degrade PCP in a changeable environment. The aim of this work was to study the influence of pH of the medium and the effect of inoculum size on pentachlorophenol degradation by Pseudomonas sp. A study of PCP degradation kinetics was performed to assess such effects. PCP was degraded rapidly at pH values from 6.3 to 8, but the maximum rate of PCP degradation by Pseudomonas sp. was at pH 6.3. In contrast, the PCP degradation kinetics at pH 5.5 were significantly lower, although PCP was totally depleted. These results show the broad range of pHs for PCP degradation for this strain. PCP was degraded at every inoculum size tested and PCP degradation increased with the increasing inoculum size, but cultures inoculated with the lowest inoculum showed the highest specific consumption rate. This reveals a lower consumption of PCP per CFU at a high population density. These results are useful to understand the physiological and biochemical properties of Pseudomonas sp. before its optimum use in environmental application and these data will assist in choosing the right PCP-degrader for a changeable environment. Water SA Vol 32(1)pp:93-98
Degradation of phenol and chlorophenols by mixed and pure cultures
SE Murialdo, R Fenoglio, PM Haure, JF Gonzalez
Water SA , 2003,
Abstract: The enrichment of mixed cultures for species capable of degrading phenol and chlorophenols, as well as the isolation of pure cultures are investigated. The cultures obtained are capable of degrading phenol and chlorophenols (pentachlorophenol 2, 3, 5, 6 tetrachlorophenol and 2, 4, 6 trichlorophenol) but not 2, 4, 5 trichlorophenol. The results suggest the feasibility of the use of toxic chemicals as phenols, hexadecane and other chlorophenols as co-substrates in field decontamination processes. The inhibitory effect of PCP is shown, and the influence of a readily degradable ancillary carbon source on the performance of pure cultures is reported, as well as the preliminary identification of the bacteria that showed higher PCP degrading activity. WaterSA Vol.29(4) 2003: 457-463
Degradation of chlorophenol mixtures in a fed-batch system by two soil bacteria
I Durruty, E Okada, JF González, SE Murialdo
Water SA , 2011,
Abstract: This work was undertaken to investigate the effect of variations of the feed rate on a fed-batch set-up used to degrade xenobiotics. The mixture of substrates was composed of PCP, 2,4,6 TCP and 2,3,5,6 TeCP (pentachlorophenol, 2,4,6 trichlorophenol and 2,3,5,6 tetrachlorophenol respectively). Two acclimated bacteria isolated from soil were used: Pseudomonas aeruginosa and Achromobacter sp. nov. The different flow rates tested were: I: 0.5 m min-1, II: 1.67 m min-1 and III: 2.00 m min-1. Our results show that during fed-batch operation the 2,4,6 TCP exhibits an earlier degradation than the other compounds, for all of the flow rates tested. This indicates that in this case the degradation of the most recalcitrant compounds (PCP and 2,3,5,6 TeCP) is benefited by the increase in biomass of bacteria, due to the metabolisation of a less recalcitrant compound (2,4,6 TCP). The defined parameter, specific degradation rate (SDR), was demonstrated to be very useful for comparing the degradation abilities at different flow rates of a fed-batch system. The degradation efficiencies were shown to be higher than 90% for all of the cases and to decrease as the feed rate increases. However, the SDR, a parameter that involves the rate of degradation and the biomass, increases as the flow rate increases. At a feed flow rate of 2 m min-1 SDR reaches a maximum of 12.476 x 10-10 mgCP h-1 CFU-1. Finally, among the feed flows tested, taking into account both the degradation efficiency and the SDR, 2 m min-1 is the most convenient flow rate for chlorophenol degradation in fed-batch systems. An even higher degradation efficiency (97%) can be achieved by using the feed rate of 2 m min-1 followed by an additional batch post-treatment of 2 h, with a SDR of 13.136 x 10-10 mg CP h-1 CFU-1.
The Bacteriophage lambdaDNA packaging enzyme: Identification of four structural domains of the gpNu1 subunit using limited proteolysis
ARAYA,PAMELA; ROSEMBLATT,MARIO; VALENZUELA,PABLO; MURIALDO,HELIOS;
Biological Research , 2001, DOI: 10.4067/S0716-97602001000300008
Abstract: lambda dna terminase, the enzyme that cleaves virion-length chromosomes from multigenomic concatemers and packages them into the bacteriophage head, is composed of two subunits, gpnu1 and gpa. direct determination of the structure of gpnu1, the smaller subunit, has not been possible because of its insolubility in aqueous solutions. therefore, to identify smaller and potentially water-soluble domains of gpnu1, we analyzed the nature of the products obtained by limited digestion of the protein with several proteases. the gpnu1 subunit was obtained from e.coli cells transfected with the plasmid ph6-nu1 that overproduces the protein. incubation of gpnu1 solubized in 2.5 m guanidinium chloride with chymotrypsin resulted in the formation of at least eight discrete protein bands, while treatment with endoproteinase glu-c and bromelain yielded three and one major bands, respectively. the peptides generated by digestion with the various proteases were separated by two-dimensional gel electrophoresis and transferred to immobilon membranes. amino acid sequencing of the peptides allowed for the precise assignment of their n-terminal amino acid, while their estimated molecular weights permitted the identification of their c-terminal ends. the results reveal that in the presence of 2.5 m guanidinium chloride, gpnu1 is partially folded in at least four distinct structural domains that correspond to functional domains as determined by previously reported genetic experiments. this information is key to design new plasmids to overproduce these domains for further structural analysis.
The Bacteriophage lambdaDNA packaging enzyme: Identification of four structural domains of the gpNu1 subunit using limited proteolysis
PAMELA ARAYA,MARIO ROSEMBLATT,PABLO VALENZUELA,HELIOS MURIALDO
Biological Research , 2001,
Abstract: Lambda DNA terminase, the enzyme that cleaves virion-length chromosomes from multigenomic concatemers and packages them into the bacteriophage head, is composed of two subunits, gpNu1 and gpA. Direct determination of the structure of gpNu1, the smaller subunit, has not been possible because of its insolubility in aqueous solutions. Therefore, to identify smaller and potentially water-soluble domains of gpNu1, we analyzed the nature of the products obtained by limited digestion of the protein with several proteases. The gpNu1 subunit was obtained from E.coli cells transfected with the plasmid pH6-Nu1 that overproduces the protein. Incubation of gpNu1 solubized in 2.5 M guanidinium chloride with chymotrypsin resulted in the formation of at least eight discrete protein bands, while treatment with endoproteinase glu-C and bromelain yielded three and one major bands, respectively. The peptides generated by digestion with the various proteases were separated by two-dimensional gel electrophoresis and transferred to Immobilon membranes. Amino acid sequencing of the peptides allowed for the precise assignment of their N-terminal amino acid, while their estimated molecular weights permitted the identification of their C-terminal ends. The results reveal that in the presence of 2.5 M guanidinium chloride, gpNu1 is partially folded in at least four distinct structural domains that correspond to functional domains as determined by previously reported genetic experiments. This information is key to design new plasmids to overproduce these domains for further structural analysis.
The Measurement and Prediction of Flash Point for Binary Mixtures {C1 ~ C3 Alcohols + p-Xylene} at 101.3 kPa  [PDF]
Kyu Jin Han, Se Jin In
Open Journal of Safety Science and Technology (OJSST) , 2017, DOI: 10.4236/ojsst.2017.71001
Abstract: The flash point of flammable liquid mixture is very important parameter to characterize the ignition and explosion hazards. Flash points at 101.3 kPa were measured for several binary systems containing p-xylene, including {methanol + p-xylene}, {ethanol + p-xylene}, and {2-propanol and p-xylene}. Experimental measurements were performed using a SETA closed cup flash point tester. The measured flash points were compared with the predicted values calculated using the following activity coefficient models: Wilson, Non-Random Two Liquid (NRTL), and UNIversal QUAsi-Chemical (UNIQUAC). The results from the NRTL model provided the best comparison to the experimentally determined values.
Use of MRI fusion second-look ultrasound in breast cancer: can MRI US fusion reduce the need for MRI-guided biopsy?
SE McWilliams
Breast Cancer Research , 2012, DOI: 10.1186/bcr3253
Abstract: At our institution we have introduced an MRI breast biopsy service which is time consuming and expensive. We looked at 10 patients with MRI US fusion technology on our new Hitachi US MRI scanner to see whether lesions were easier to identify combining the MRI and US images, enabling US biopsy to be performed.Ten patients with a known breast cancer had a further incidental lesion seen on MRI. The patients had an additional supine series on contrast MRI images in addition to the standard prone protocol. The supine images were loaded on the US machine and enabled confident detection of the lesion on US in nine out of 10 patients.Using MRI US fusion with one additional MRI series of supine images reduces the need for MRI-guided biopsy enabling US biopsy to be performed, which is cheaper, quicker and more patient acceptable.
Conceptual and practical issues in the management of chronic pain
SE Baumann
Continuing Medical Education , 2003,
Abstract:
Women as Iconic Paradox The Ebira-Ekuechi Facekuerade Performance Example
SE Ododo
Creative Artist: A Journal of Theatre and Media Studies , 2009,
Abstract:
The impact of forest reserves on livelihoods of fringe communities in Ghana
SE Edusah
Journal of Science and Technology (Ghana) , 2011,
Abstract: This study looked at how the livelihoods of forest fringe communities have been affected by the constitution of four forest reserves in Brong Ahafo and Ashanti Regions of Ghana. The selection of the reserves for study was based on the fact that the reserves were surrounded by a number of relatively new and old settlements and have potential for socio-economic activities (agricultural production and ecotourism). Two main research approaches, structured questionnaire and semi-structured interviews were used in the data collection. A structured questionnaire together with open-ended questions was used to collect quantitative and qualitative information on household and community characteristics, including household incomes, farm sizes and tenancy arrangements. An open-ended questionnaire was designed for selected groups and community leaders to solicit their views and perceptions. The study found that farming was the main occupation of the people with cocoa and oil palm being the major cash crops grown in the area. Food crops grown include plantain, maize, cocoyam, cassava and rice. The major tenancy arrangements include family lands, outright purchase and sharecropping. Environmental problems in the area are decline in soil fertility, soil erosion, deforestation, bush fires and depletion of game and wildlife. Incomes were found to be low resulting in high poverty levels. The study shows that the communities have little role to play in the management of forest reserves.
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