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1
Ranmuthugala, Geethanjali Piyawadani. "Disinfection by-products in drinking water and genotoxic changes in urinary bladder epithelial cells." View thesis entry in Australian Digital Theses Program, 2001. http://thesis.anu.edu.au/public/adt-ANU20011207.110344/index.html.
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2
Leung, Kai-shing Alex. "Control of disinfection by-products." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41549429.
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3
梁啟承 and Kai-shing Alex Leung. "Control of disinfection by-products." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41549429.
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4
Szomolay, Barbara. "Analysis and control of a biofilm disinfection model." Diss., Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/szomolay/SzomolayB1206.pdf.
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5
Nguyen, Ha Thi. "Effect of transmittance and suspended soils on the efficacy of UV disinfection of bacterial contaminants in water." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09AS/09ash111.pdf.
Повний текст джерелаАнотація:
Errata pasted onto front end-paper. Bibliography: leaves 113-120. To obtain robust and quantitative data on the influence of UV absorption and suspended solids on UV disinfection an experimental study using commercial disinfection technology was undertaken.
6
Whyte, Rebecca Mary. "Changing approaches to disinfection in England, c.1848-1914." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610597.
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7
Chiruta, Juliana. "Thermal sterilisation kinetics of bacteria as influenced by combined temperature and pH in continuous processing of liquid." Title page, contents and summary only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phc5416.pdf.
Повний текст джерелаАнотація:
Errata sheet has been pasted onto the front end-paper. Bibliography: leaves 208-217. Outlines a systematic synthesis and testing of continual sterilization design. Principal aim is to evaluate and develop mathematical models for sterilization, undertake experimental studies for determining thermal inactivation effects on continuous processing of a liquid containing contaminant bacteria and compare the data obtained with those predicted by a selected model.
8
Leung, Wai Kin. "Smart hygienic coating for a healthier living environment /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202007%20LEUNG.
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9
McFarlane, Margaret R. "Glutaraldehyde hazard assessment and risk control in a hospital setting /." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998mcfarlanem.pdf.
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10
Castro, Luis Fernando. "Inactivation of Cronobacter (Enterobacter) sakazakii using different antimicrobial agents and the effect of sanitizers on biofilm formation properties." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/l_castro_102709.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in food science)--Washington State University, December 2009.Title from PDF title page (viewed on Jan. 20, 2010). "School of Food Science." Includes bibliographical references (p. 55-59).
11
THURMAN, ROBERT BRUCE. "THE CHARACTERIZATION OF VIRUS INTERACTION WITH SELECTED SURFACE CONTACT DISINFECTANTS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184104.
Повний текст джерелаАнотація:
The search for alternative water disinfectants to those commonly used, such as chlorine, probably began when the disadvantages of those disinfectants became known. Soluble disinfectants have short half-lives and need to be replenished periodically which requires monitoring the determination of appropriate concentrations for waters being treated. This disadvantage may be balanced by the ability to alter dose concentrations of soluble disinfectants to meet changes in demands. Maintenance of a residual disinfectant concentration which can act throughout a water distribution system is another advantage of soluble disinfectants. Disadvantages due to reaction of organic materials include the loss of disinfecting capability, health hazards related to the disinfectant and the potential loss of aesthetic water qualities such as taste, smell and color. The purpose of this study was to investigate different surface contact disinfectants which, while having an inflexible dose concentration capability and releasing no residual disinfectant concentration, do not require monitoring and do not significantly leach into the waters they contact. Powdered aluminum when mixed with a loamy sand reduces virus concentration 3-4 orders of magnitude better than controls while not significantly altering the pH or aluminum concentration of waters that pass through the soil columns. Labeled poliovirus 1 was found to adsorb onto the aluminum surface in batch experiments and undergo degradation or dissociation of the capsid proteins with release of viral fragments and clumps within 76 hours. Freon dispersion of the viral clumps showed the clumps to be non-infective. Polyacrylamide gel electrophoresis of poliovirus 1 incubated with aluminum for 76 hours suggested degradation or dissociation of viral capsid proteins 1, 2 and 3. Magnesium peroxide and magnesium oxide, while effectively inactivating viruses, significantly increase the pH of water which they contact. Polyhalex resin and I5 resin reduce virus concentration, but release functional groups into the surrrounding water. Contact disinfectants such as aluminum, may find point-of-use application for drinking water, use in septic tank leachfields or sewage treatment infiltration basins to reduce the threat of spreading potential disease-causing organisms.
12
Ko, Chi-mei. "Interaction of Legionella Pneumophila and selected algae and response to disinfectants." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc798089/.
Повний текст джерелаАнотація:
Two species of cyanobacteria (Fischeralla sp. 29161 and Phormidium autumnale) and one species of green algae (Fritschiella tuberosa) were found to promote survival of Legionella pneumophila in mineral salts medium cocultures. During the early stage of incubation Fischerella sp. supported growth of Legionella pneumophila even though the bacteria would not grow in the algae-free basal medium.
13
Li, Lijie. "Effects of initial microbial density on disinfection efficiency in a continuous flow system and validation of disinfection batch kinetics in a continuous flow system /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/266.
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14
Pratt, Michael D. "Differential response of various spore species to sporicidal disinfectants /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2068.pdf.
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15
Malan, Cheryl. "The efficiency of drinking water treatment plants in removing immunotoxins." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5762_1308732795.
Повний текст джерелаАнотація:
The aim of this study was to evaluate the effectiveness of water treatment processes of two drinking water plants to remove immunotoxins and steroid hormones. Raw and treated drinking water was screened for effects on inflammatory activity using the biomarker IL-6, humoral immunity using the biomarker IL-10 and cell mediated immunity using the biomarker IFN-&gamma
. In vitro human whole blood culture assays were used in order to elucidate potential immunotoxicity.
16
Nitschke, Monika. "Glutaraldehyde exposures and health effects among South Australian hospital nurses /." Title page, table of contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09MPM/09mpmn732.pdf.
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17
Karnik, Bhavana Sushilkumar. "The use of ozonation and catalytic ozonation combined with ultrafiltration for the control of natural organic matter (NOM) and disinfection by-products (DBPS) in drinking water." Diss., Connect to online resource - MSU authorized users, 2006.
Знайти повний текст джерелаАнотація:
Thesis (Ph. D.)--Michigan State University. Dept. of Civil and Environmental Engineering, 2006.Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references. Also issued in print.
18
Sexton, Diane Lynne. "Analysis of disinfection by products in drinking water by solid phase extraction." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040321/.
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19
Liu, Meilin. "Effects of the antimicrobial agent Triclosan on bacterial resistance to disinfection in wastewater treatment processes." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5996.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains viii, 55 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-55).
20
Zhu, Changyun Worley Shelby D. "Synthesis and application of novel biocidal materials." Auburn, Ala, 2008. http://hdl.handle.net/10415/1428.
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21
Han, A. Reum. "Effectiveness of aerosolization as a novel disinfection method to inactivate foodborne pathogens on fresh produce." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/ar_han_1041609.pdf.
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22
Bundy, Jonathan. "Disinfection by-product analysis and modeling in the Gwinnett County, Georgia, water distribution system." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/21267.
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23
Huhman, Brett M. "Cold-fog based disinfection of an office environment using electrostatic-induction and ultraviolet light-enhancement." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4588.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 21, 2009) Includes bibliographical references.
24
Mosteller, Tracy M. "Sanitizer efficacy towards attached bacteria in a simulated milk pipeline system using pure and mixed cultures." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08062007-094410/.
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25
Velez, Rivera Edwin. "A review of chemical disinfection methods for minimally processed leafy vegetables." Thesis, Manhattan, Kan. : Kansas State University, 2005. http://hdl.handle.net/2097/103.
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26
Ginart, Rachelle. "COMPARISON OF THE EFFECTIVENESS OF ALTERNATIVE FERRATE (VI) SYNTHESIS FORMULAS AS DISINFECTANTS FOR WASTEWATER AND RIVER WATER." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2734.
Повний текст джерелаАнотація:
Ferrate (VI) has been studied as an alternative chemical to disinfect water and wastewater in recent years. The disinfection effectiveness of two different wet oxidation ferrate (VI) synthesis formulas in wastewater and Econlockhatchee River water was evaluated. Ferrate (VI) is synthesized by addition of ferric chloride to a mixture of sodium hydroxide and calcium hypochlorite (refer to U.S. Patent 6,790,429). One ferrate (VI) synthesis formula uses below the stoichiometric requirement of hypochlorite (Low Chlorine Formula) while the other ferrate (VI) synthesis formula uses more than the stoichiometric requirement of hypochlorite (Standard Chlorine Formula). For applications requiring low chlorine residual effluent quality, the Low Chlorine Formula intuitively is a more suitable disinfectant than the Standard Formula. For applications where chlorine residual is of little or no significance, the Standard Formula is logically a more suitable disinfectant due to lower production cost and production of higher ferrate (VI) concentrations than the Low Chlorine Formula. The total chlorine concentration, unfiltered and filtered ferrate (VI) concentration, and dissolved organic carbon concentration before and after treatment using both ferrate (VI) formulas in wastewater and Econ River water was measured at a contact time of 30 minutes. Disinfection capabilities were measured by comparing the quantity of Heterotrophic bacteria, Total Coliform, Escherichia coli, and Enterococcus bacteria pre-ferrate (VI) to post-ferrate (VI) at dosages of 2, 4, and 7.5 mg/L as ferrate (VI) using both ferrate (VI) formulas. The rate of disappearance of both ferrate (VI) formulas in wastewater at an unadjusted pH and pH of 6.0-6.35 was determined. In addition the total oxidant absorbance and total chlorine concentration were measured over a 30-minute period. Both ferrate (VI) formulas were effective at inactivating Total Coliform, E. Coli, Enterococcus, and heterotrophic bacteria at a 30-minute contact time and lowering DOC concentrations in Econlockhatchee River water and secondary wastewater. The Standard Formula demonstrated better disinfection at lower dosages than the Low Chlorine Formula. In both ferrate (VI) formulas, there was a presence of an instantaneous demand of ferrate (VI) and a first-order reaction rate of ferrate (VI) over 30 minutes. The chlorine residual of 7.5 mg/L ferrate (VI) dose in wastewater at a 30-minute contact time was 0.2 to 0.6 mg/L Cl2 for the Low Chlorine Formula and 0.8 to 1.4 mg/L Cl2 for the Standard Formula. These experiments indicate that both ferrate (VI) formulas can serve as effective environmentally friendly disinfectants for wastewater and Econ River water.M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engr MSEnvE
27
Johnstone, David W. "Drinking water disinfection byproduct formation assessment using natural organic matter fractionation and excitation-emission matrices." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1247802154.
Повний текст джерелаАнотація:
Dissertation (Ph. D.)--University of Akron, Dept. of Civil Engineering, 2009."August, 2009." Title from electronic dissertation title page (viewed 9/30/2009) Advisor, Christopher M. Miller; Committee members, William Brian Arbuckle, George G. Chase, Annabelle M. Foos, William H. Schneider IV; Department Chair, Wieslaw Binienda; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
28
Cheung, Lok Man. "Investigation of virus inactivation and by-products formation under sequential disinfection using UV irradiation and free chlorine/monochloramine /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20CHEUNG.
Повний текст джерелаАнотація:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 106-124). Also available in electronic version. Access restricted to campus users.
29
Baek, Nak-hyun. "The impact of a change in disinfectants on the water quality of a distribution system." Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/902475.
Повний текст джерелаАнотація:
Chloramine is a widely used alternative disinfectant for chlorine in potable distribution water. This alternative was investigated and employed to show its effect for suppressing coliforms, trihalomethanes(THMs), disinfection by-products (DBPs), and corrosivity.Coliform analyses were performed with m-Endo(total coliform) and m-T7 agar(injured coliform) by using a standard Membrane Filtration method. Heterotrophic bacteria were monitored with HPC agar(PCA) and R2A agar (nutrient limited agar). EPA methods 502.2, 524.2, and 504 were used to determine levels of Trihalomethanes(THMs) and Disinfection by-products(DBPs).In our study, we observed no significant differences in coliform counts, that could be attributed to the switch in disinfectant. The most common coliform identified was Enterobacter cloacae. We also noted that m-T7 performed better than m-Endo in the detection of coliforms. We also observed a low level of corrosion (0.4-3.8 mils/year) in the distribution system (DS). Higher counts of heterotrophic bacteria were enumerated on R2A when compared to HPC. DBP values decreased two fold when compared with DBP values for the two previous years during which chlorine was used as the disinfectant.Department of Biology
30
Ye, Zhengcai. "UV Disinfection between Concentric Cylinders." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14641.
Повний текст джерелаАнотація:
Outbreaks of food-born illness associated with the consumption of unpasteurized juice and apple cider have resulted in a rule published by the U.S. Food and Drug Administration (FDA) in order to improve the safety of juice products. The rule (21 CFR120) requires manufacturers of juice products to develop a Hazard Analysis and Critical Control Point (HACCP) plan and to achieve a 5-log reduction in the number of the most resistant pathogens. Ultraviolet (UV) disinfection is one of the promising methods to reach this 5-log reduction of pathogens. The absorption coefficients of juices typically vary from 10 to 40 1/cm and can be even higher depending on brand and processing conditions. Thin film reactors consisting of two concentric cylinders are suitable for inactivating pathogens in juices. When the two concentric cylinders are fixed, the flow pattern in the gap can be laminar Poiseuille flow or turbulent flow depending on flow rates. If the inner cylinder is rotating, and the rotating speed of the inner cylinder exceeds a certain value, the flow pattern can be either laminar or turbulent Taylor-Couette flow. UV disinfection between concentric cylinders in laminar Poiseuille flow, turbulent flow and both laminar and turbulent Taylor-Couette flow was investigated experimentally and numerically. This is the first systematic study done on UV disinfection between concentric cylinders in all three flow patterns. The present work provides new experimental data for pathogen inactivation in each of the three flow patterns. In addition, the present study constitutes the first systematic numerical CFD predictions of expected inactivation levels. Proper operating parameters and optimum gap widths for different flow patterns are suggested. It is concluded that laminar Poiseuille flow provides inferior (small) inactivation levels while laminar Taylor-Couette flow provides superior (large) inactivation levels. The relative inactivation levels are: laminar Poiseuille flow < turbulent flow < laminar Taylor-Couette flow.
31
Verdugo, Edgard Manuel. "Reaction of carbon nanotubes with chemical disinfectants: Byproduct formation and implications for nanotube environmental fate and transport." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1922.
Повний текст джерелаАнотація:
Nanomaterials (materials which have at least one dimensional feature with length less than 100 nanometers), and carbon nanotubes (CNTs) specifically, have exhibited great potential in water treatment. CNTs are cylindrical structures comprising single or multiple concentric graphene sheets and have diameters from less than 1 nanometer (nm) up to 50 nm (one nm is one millionth of a millimeter). Due to their unique and tunable structural, physical, and chemical properties, CNTs are used in environmental remediation as absorbents, catalysts or catalyst supports, membranes, and electrodes. However, a poorly understood determinant of the role of CNTs in water treatment is their interaction with chemical disinfectants (e.g., chlorine, chloramine, and ozone). To address these existing gaps in the environmental fate and reactivity of CNTs, this work establishes whether CNTs represent precursors for halogen and nitrogen containing disinfection byproducts (DBPs), which are products that form during a reaction of a disinfectant with organic matter in the water. In addition, we seek to understand how reaction with disinfectants alters CNT surface chemistry, and in turn impacts their environmental mobility and cytotoxicity. Finally, we determine how NOM and other aquatic variables known to impact DBP formation (e.g., Br−, NOM, and pH) influence the rate and products of CNT reaction with disinfectants. Outcomes of this work contribute to the current understanding of the role of carbon-based species as DBP precursors in disinfection and provide new context as to the environmental significance and implications of CNTs in natural and engineered aquatic systems.
32
McAuley, Kimberley. "Disinfection by-products and public health concerns." University of Western Australia. School of Population Health, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0070.
Повний текст джерелаАнотація:
Disinfection by-products (DBPs) are a major group of water contaminants and their role in causing adverse health outcomes, including adverse pregnancy outcomes, endocrine disruption, respiratory related adverse health outcomes and cancer has been subject to extensive epidemiological and toxicological research and review. Determination of safe exposure to DBPs, particularly within drinking water supplies, has been a topic of extensive debate, with a wide range of acceptable levels set across the industrialized world. The focus of the research in this thesis was on two of the main health outcomes associated with DBP exposure, namely adverse pregnancy outcomes and asthma related symptoms. To assess adverse pregnancy outcomes in Perth, an extensive classification quantification of the major DBPs in Perth drinking water was conducted. A registrybased prevalence study was carried out to assess birth defects in relation to high, medium and low DBP areas (defined by the water sampling and analysis). It was found that women living in high THM areas are 22% (odds ratio (OR) 1.22, 95% confidence interval (95% CI) 1.01-1.48) more likely of having a baby with any birth defect. High exposure was also strongly associated with an increased risk of having a baby with a cardiovascular defect (62% increased risk). Low birth weight and prematurity were also assessed; however these outcomes were not associated with an increased risk through an increase in exposure. Following on from this analysis, a population risk assessment model was developed for DBPs in high exposure environments. This involved a three step process: (i) Firstly a questionnaire-based validation and reliability study was used to assess water consumption patterns of a population of pregnant women in Perth. (ii) Secondly a prediction model for teratogenic burden of DBPs in Perth was developed, related to the exposure patterns of the population of pregnant women involved in the validation and reliability study. (iii) Finally, combining the information collected in (i) and (ii), along with the regression slope estimates for birth weight from the prevalence study (defined in Section 2.2.1), a dose-response model for THMs and birth weight was developed. Predictive simulations for birth weights at given THM levels were then conducted. It was estimated that pregnant women in Perth are exposed to between 0.3 4.10 µg/day ingested TTHM, and of this, the more toxic brominated forms accounted for between 0.27 3.69 µg/day. Based on a dose-response model used, birthweights calculated for the hypothetical exposures ranged from 3403.2g for the highest exposure to 3503.5g in the lowest exposure, which is a difference of over 100g. Although the resulting reduction in birth weight is not extreme, there is still a significant reduction in birth weight present as exposure to TTHMs increases. This is the first doseresponse model to be developed to assess an adverse pregnancy outcome based on pregnant women exposure data, and will be a useful tool for assessing varying exposures throughout not only Australia but also throughout the industrialised world, where DBP exposure is highly prevalent.
33
Lutz, Theresa Marie. "A Study of the Precursors for Disinfection By-Products on the CAP Avra Valley Recharge Project." Thesis, The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0114_sip1_w.pdf&type=application/pdf.
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34
Kim, Dongjin. "Large eddy simulation of flow in water and wastewater disinfection reactors." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41089.
Повний текст джерелаАнотація:
Hydrodynamic behavior in reactors used for water treatment, particularly in ozone contactors with serpentine flow, is known to strongly affect the process efficiency. However, exact flow characteristics inside these reactors are not well understood, as traditional approach either considers these reactors as black box or relies on less accurate Reynolds-Averaged Navier-Stokes (RANS) simulation. In order to provide a deep understanding of the hydrodynamics and solute transport phenomena in these reactors, high resolution numerical studies using the Large Eddy Simulation (LES) method are performed. The reactor geometries investigated in this research are Constant Baffle Spacing Multi-Chamber (CBSMC) ozone contactors and a Variable Baffle Spacing ozone contactor Model (VBSM). The LES results in two multi-chamber ozone contactors (CBSMC -Normal-Width and -Half-Width) suggest that the flow through these reactors is characterized by the presence of extensive short-circuiting and large internal recirculation. The results also suggest that the flow is highly three dimensional with a pair of symmetric counter-rotating secondary vortices. LES studies based on VBSM, the baffle spacing of which varies between 0.5 times to 5 times the size of the base chamber; suggest that the width of the recirculation zone grows at about the same rate as the baffle spacing. Instantaneous turbulent eddies are prevalent in the chamber and increase turbulent mixing. The elevated levels of turbulence are found in the short-circuiting flow path. The tracer is dispersed along the short-circuiting path and strongly into the recirculation zone due to turbulent diffusion. Baffle spacing greater than the entrance gate height, but also smaller baffle spacing, worsens the disinfection efficiency. Finally, the turbulent Schmidt number of RANS simulation was investigated by employing the previously validated LES simulation. Due to the presence of very strong turbulent diffusion in the reactors, the turbulent Schmidt number is found out to be much less than the values commonly used, and is also specific to the baffle spacing.
35
Artico, Gabriela. "Eficácia do ácido peracético na desinfecção de instrumentos contaminados." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-02012008-114342/.
Повний текст джерелаАнотація:
Esta pesquisa foi realizada com o objetivo de avaliar a eficácia do ácido peracético ou peroxiacético (APA) a 0,2% na desinfecção de instrumentos contaminados pela microbiota oral. Uma coleta foi realizada com instrumento termolábil usado comumente em alguns procedimentos odontológicos. A coleta foi realizada em quatro sítios da cavidade oral: mucosa jugal (lados direito e esquerdo), palato duro e dorso da língua em trinta pacientes, com quatro instrumentos diferentes para cada local. Cada um dos quatro instrumentos passou por quatro tratamentos diferentes, sendo divididos em quatro grupos: A (sem nenhum tratamento), B (tratamento com APA), C (lavagem com água e detergente) e D (lavagem com água e detergente e tratamento com APA). Após os tratamentos, cada instrumento foi colocado em solução salina estéril para extração dos microrganismos. Diluições da solução salina foram colocadas em placas de Petri contendo meio ágar caseína de soja ou ágar Sabouraud dextrose e incubadas de modo a favorecer, respectivamente, a anaerobiose e aerobiose ou o crescimento de bolores e leveduras. Foi realizada a contagem das unidades formadoras de colônia (UFC) e aplicados o teste ANOVA e o Teorema de Bonferroni para todas as culturas separadamente e conjuntamente para toda a microbiota oral Concluiu-se que o APA foi eficaz na desinfecção desses instrumentos.This research was realized to evaluate of the of peracetic or peroxiacetic acid (PAA), at 0,2%, efficacy in the disinfection of instruments contaminated by oral microbiota. A collect was realized with heat sensitive instruments used commonly in some procedures in Dentistry in four sites of the oral cavity: buccal mucosa (left and right sides), hard palate and tongue\'s dorsum from thirty patients using four instruments for each site. Each instrument was treated by different methods, and was divided in four groups: A (without any treatment), B (with APA treatment), C (washed by detergent and water) and D (washed by detergent and water and followed by APA treatment). After each treatment, the instruments were put in a sterile salt solution to extract the microorganism. Dilutions of this salt solution were put on Petri plaques with Tryptic soy agar or Sabouraud dextrose Agar and incubated to favor the respective anaerobiosis and aerobiosis or the growing of moulds and yeasts. The units were counted by colonies (CFU) and introduced the ANOVA test and the Theorem of Bonferroni to every separated culture and every oral microbiota. It was concluded that the APA was efficient on the disinfection of the tools instruments.
36
Gandhi, Varun N. "Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45895.
Повний текст джерелаАнотація:
The validation of UV reactors is currently accomplished by biodosimetry, in which the reactor is treated as a "black-box" and hence cannot account for the dependence of the dose delivery on the complex hydrodynamics and the spatial variation in UV intensity. Alternative methods, such as fluorescent microspheres as non-biological surrogates and computational fluid dynamics (CFD) simulations, have been developed; however, each method has its shortcomings.
In this study, a novel technique for the spatial and temporal assessment of the hydrodynamics and the UV dose delivered and the link between these two factors in a lab-scale UV reactor using three dimensional laser induced fluorescence (3DLIF) is developed. This tool can also be utilized for the optimization of UV reactors and to provide data for validation of CFD-based simulation techniques. Regions of optimization include areas around the UV lamp where short-circuiting occurred, a longer inlet approach section that enhances the performance of the reactor by reducing short circuiting paths and a longer outlet region to provide greater mixing.
3DLIF allows real time characterization of mixing and dose delivery in a single lamp UV reactor placed perpendicular to flow by capturing fluorescence images emitted from a laser dye, Rhodamine 6G, using a high speed CCD camera. In addition to three-dimensional mixing, the technique successfully visualized the two-dimensional, transient mixing behaviors such as the recirculation zone and the von Karman vortices and the fluence delivery within the reactor, which has not been possible with traditional tracer test techniques. Finally, a decomposition technique was applied to the flow and fluence delivery based concentration data to reveal similar structures that affect these phenomena. Based on this analysis, changing the flow in the reactor, i.e. the Reynolds number, will directly affect the fluence delivery.
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Oliveira, Derly Tescaro Narcizo de [UNESP]. "Efeito da polimerização e desinfecção na resistência flexural e na topografia da superfície de resina acrílica." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/95782.
Повний текст джерелаАнотація:
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A ação dos produtos desinfetantes sobre as propriedades físico-químicas da resina acrílica norteia sua seleção para a higienização de aparelhos ortodônticos removíveis. Avaliou-se a resistência à fratura de resina acrílica ativada quimicamente após ciclagem em diferentes soluções desinfetantes. Foram confeccionados quarenta corpos de prova com resina acrílica autopolimerizável incolor (Clássico,Ind.&Com.Ltda./Brasil) utilizando-se matriz metálica retangular e circular, seguindo-se às técnicas de polimerização sob pressão úmida (imersão em água/n=20) e sob pressão seca (sem água/n=20) foram subdivididos em 4 grupos (n=5), conforme a solução utilizada para ciclagem: água destilada (Controle), bicarbonato de sódio, hipoclorito de sódio 1% e Corega®Tabs. A ciclagem consistiu em imersão em 100 ml da solução por 10 minutos três vezes ao dia e, em seguida, manutenção em recipiente fechado contendo saliva artificial a 37ºC. Este ciclo foi realizado durante 30 dias, trocando-se as soluções e a saliva a cada procedimento executado. Na sequência os espécimes foram submetidos ao ensaio de resistência flexural a três pontos foi utilizada máquina EMIC DL3000, à velocidade de 5mm/min, dispondo-se as amostras em suporte contendo dois apoios de sustentação, sendo aplicada força axial e equidistante aos dois outro pontos até a ruptura do corpo-de-prova. Os espécimes circulares foram levados para leitura em Microscópio de Força Atômica (AFM - V Nanoscope Veeco). Os resultados, submetidos à análise de variância (P<0,001 ) e o Teste de Tuckey (P<0,05) não apontaram diferenças significantes para a resistência flexural. Conclui-se que os métodos de polimerização e as soluções testadas não modificaram a resistência flexural...
The disinfectant products action on the physicochemical properties of acrylic resin guides its selection to the cleaning of removable orthodontic appliances. The fracture resistance of acrylic resin after cycling in different disinfectant solutions was evaluated. Forty specimens were made with colorless acrylic resin (Clássico, Ind. & Com.Ltda. / Brazil), using matrix, followed by the techniques of polymerization under wet pressure (immersion in water / n = 20) and dry pressure (no water / n = 20). The samples were divided into 4 groups (n = 5) as the solution used for cycling: distilled water (Control), sodium bicarbonate, sodium hypochlorite 1% and Corega®Tabs. The cycling consisted of immersion in 100 ml of solution for 10 minutes three times a day and then maintained in a closed container containing artificial saliva at 37 º C. These cycles were conducted during 30 days, changing the solutions and artificial saliva for each procedure performed. Latter, the specimens were submitted to surface analysis with Atomic Force Microscope (AFM - Veeco Nanoscope V). A machine, EMIC DL3000, was used for the three-point flexural strength test, speed of 5mm/min, providing the sample in medium containing two restraints support. After that axial force was applied and equidistant to the two other points to the body to break the specimens. The results were submitted to analysis of variace(P<0,001) and Tuckey Test (P<0,05) showed no significant differences in flexural strength test. The Atomic Force Microscopy analysis revealed less topographical roughness for the group Corega®Tabs. We conclude that the polymerization methods and solutions tested did not alter the flexural strength of the material studied except the comparation between... (Complete abstract click electronic access below)
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Abreu, Laura Figueiredo. "Avaliação de processo de sanificação quimica de garrafas plasticas para sistemas assepticos." [s.n.], 2001. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254553.
Повний текст джерелаАнотація:
Orientador : Jose de Assis Fonseca FariaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Através da metodologia de planejamento experimental foram feitas variações de tempo de contato, temperatura e concentração de três diferentes sanificantes para embalagem. Estas variações tiveram como objetivo reduzir de 5 a 6 ciclos logarítmicos a população inicial de esporos de Bacillus subtilis varo globigii(ATCC 9372), no menor espaço de tempo, quando aplicados à superfície interna de garrafas de polietileno tereftalato (PET). Foram testados como agentes sanificantes o peróxido de hidrogênio, o ácido peracético e o álcool etílico, aplicados na forma de spray, através de um sistema de sanificação desenvolvido especialmente para este tipo de teste. O peróxido de hidrogênio e o etanol não apresentaram ação esporicida significativa, sendo adotado como sanificante ideal soluções diluídas de ácido peracético enriquecida com peróxido de hidrogênio. O ácido peracético mostrou ação esporicida entre as concentrações de 0,05% e 1,5%, em um intervalo de temperatura de 30 a 50.C, causando de 1 a 7 reduções decimais. As concentrações de 0,35 a 1,25%, de ácido peracético, não conferiuram sabor estranho à água mineral envasada nas garrafas sanificadas, não diferindo, significativamente (p~O,05),do padrão. O residual de peróxido de hidrogênio das garrafas sanificadas com soluções contendo de 0,05% a 1,5% de ácido peracético, não foi superior a 0,5ppm. Contudo, aquelas sanificadas com soluções contendo 18 e 35% de peróxido de hidrogênio, apresentaram residuais acima de 0,5ppm, chegando a 2ppm. Os dados obtidos forneceram um modelo matemático quadrático, representativo da ação do ácido peracético, em função do tempo e da temperatura, sobre esporos de B. subtilis. Tal modelo, com um R2 de 0,9048, limita-se ao uso de uma concentração máxima de 1,2% de ácido peracético. Garrafas sanificadas com soluções de 0,8% de ácido peracético a 40.C, por 6 segundos e outras com soluções de 0,4% a 36.C por 11 segundos, não apresentaram residual de peróxido maior que 0,2ppm, e não apresentaram crescimento microbiano, quando preenchidas com caldo nutriente e incubadas. O sistema de sanificação testado, utilizandocomo sanificante o ácido peracético, apresentou desempenho satisfatório, podendo ser perfeitamente utilizado por indústrias de pequeno e médio porte na sanificação de garrafas em geral, sendo capaz de promover até 7 reduções decimais na população de esporos bacterianos, por garrafa,coma vantagem do baixocusto do processo
Abstract: The variables: contact time, temperature and concentration were used to study the efficiency of three packing sanitation agents, with the objective to reduce, 5 to 6 logarithmical cycles of Bacillus subtilis varo globigii (ATCC 9372) spores, when applied to the internal surface of the plastic bottles. The hydrogen peroxide, the peracetic acid and the etil alcohol were applied in spray using a sanitation system designed for this study. The hydrogen peroxide and ethanol did not show any significant sporicidal action. The most efficient sanificant agent was the diluted solution of peracetic acid enriched with hydrogen peroxide. Peracetic acid showed sporicidal action in from 0.05 to 1.50% of solution concentration, with a temperature variation of 28 to 50°C, causing from 1 to 7 decimal reductions. From 0.35 to 1.25% concentration of sanificant solution, no off-taste was found, as well as no significant difference from the standard was observed. The hydrogen peroxide residual bottles after sanitation with peracetic acid solution concentration was less than O,50ppm. Nevertheless, the bottles after sanitation with 18 to 35% solution concentration of hydrogen peroxide showed residuais from 0.50 to 2.00ppm. The quadratic model, with R2of 0.9048, is restricted to 1.2% of peracetic acid solution. Neither bottles sanitized with peracetic acid solutions of 0.80% for 6 seconds in a 40°C temperature, or 0.40% at 36°C for 11 seconds, showed peroxide residuais above 0.20ppm, as well as no microbiological growth after filling with nutrient broth and incubated: The sanification system tested, using peracetic acid solution showed satisfactory performance, effective to be used in small and medium industries, with the advantage of cost reductions
Mestrado
Mestre em Tecnologia de Alimentos
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Калиберда, Я. Г. "Значение дезинфекционных средств для здоровья человека". Thesis, Сумский государственный университет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/64174.
Повний текст джерелаАнотація:
The focus of the paper is on three components of the disinfection process:
disinfectants introduced in the environment, infectious agents in it and human
health as an object of protection. It has been established that for the preservation of
human health the most significant are the characteristics of disinfectants, such as
high efficiency and low toxicity.Uwzględnia się trzy składniki procesu dezynfekcji: dezynfekcja wprowadzana do środowiska, czynników zakaźnych i zdrowia człowieka jako przedmiot ochrony. Ustalono, że w celu zachowania zdrowia ludzi najważniejsze są właściwości środków dezynfekujących, takich jak wysoka skuteczność i niska toksyczność.
На сегодняшний день основной целью применения дезинфекционных средств (ДС) в медицине и в быту является уничтожение возбудителей и переносчиков заболеваний, поэтому их значимость в комплексе противоэпидемических и профилактических мероприятий для нейтрализации путей и факторов передачи инфекционных и паразитарных заболеваний неоспорима. При этом современные ДС, обладая способностью убивать живую клетку, не могут быть абсолютно безвредными для организма человека, который состоит из множества клеток.
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Kadry, Ahmed Y. "Removal of selected water disinfection byproducts, and MTBE in batch and continuous flow systems using alternative sorbents." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3285/.
Повний текст джерелаАнотація:
A study was conducted to evaluate the sorption characteristics of six disinfection byproducts (DBPs) on four sorbents. To investigate sorption of volatile organic compounds (VOCs), specially designed experimental batch and continuous flow modules were developed. The investigated compounds included: chloroform, 1,2-dichloroethane (DCE), trichloroethylene (TCE), bromodichloromethane (BDCM), methyl tertiary butyl ether (MTBE), bromate and bromide ions. Sorbents used included light weight aggregate (LWA), an inorganic porous material with unique surface characteristics, Amberlite® XAD-16, a weakly basic anion exchange resin, Amberjet®, a strongly basic anion exchange resin, and granular activated carbon (GAC). Batch experiments were conducted on spiked Milli-Q® and lake water matrices. Results indicate considerable sorption of TCE (68.9%), slight sorption of bromate ions (19%) and no appreciable sorption for the other test compounds on LWA. The sorption of TCE increased to 75.3% in experiments utilizing smaller LWA particle size. LWA could be a viable medium for removal of TCE from contaminated surface or groundwater sites. Amberlite® was found unsuitable for use due to its physical characteristics, and its inability to efficiently remove any of the test compounds. Amberjet® showed an excellent ability to remove the inorganic anions (>99%), and BDCM (96.9%) from aqueous solutions but with considerable elevation of pH. Continuous flow experiments evaluated GAC and Amberjet® with spiked Milli-Q® and tap water matrices. The tested organic compounds were sorbed in the order of their hydrophobicity. Slight elevation of pH was observed during continuous flow experiments, making Amberjet® a viable option for removal of BDCM, bromate and bromide ions from water. The continuous flow experiments showed that GAC is an excellent medium for removal of the tested VOCs and bromate ion. Each of the test compounds showed different breakthrough and saturation points. The unique design of the continuous flow apparatus used in the study proved to be highly beneficial to assess removal of volatile organic compounds from aqueous solutions.
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Molina, Paulo Duran dos Santos. "Eficácia de desinfetantes frente bactérias sobreviventes a higienização de equipamentos de matadouro-frigorífico de bovinos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16140.
Повний текст джерелаАнотація:
Na indústria da carne, a eficaz desinfecção das superfícies de contato com o alimento é uma importante barreira sanitária para evitar que os microrganismos deteriorantes e potencialmente patogênicos degradem o alimento ou ponham em risco a saúde dos consumidores. Com objetivo de monitorar a atividade antimicrobiana, pelo teste de suspensão, os desinfetantes quaternário de amônio, ácido peracético, clorhexidina, iodofor e hipoclorito de sódio foram confrontados com Escherichia coli, Staphylococcus aureus e dois pools de bactérias, todos organismos sobreviventes à higienização de um matadouro-frigorífico de bovinos com alta capacidade de abate. Os desinfetantes foram diluídos em graus geométricos com fator 0,5 formando cinco concentrações. Usaram-se os tempos de contato 5, 10, 15 e 20 minutos, e para simular deficiência de limpeza, à solução desinfetante foi adicionada 1% de matéria orgânica na forma de soro bovino estéril. Para análise estatística foi realizada a análise da variância com distribuição binomial para variável resposta. Com o delineamento da investigação e os organismos indicadores usados, as menores concentrações/tempo de contato para inativação de todas as bactérias foram: quaternário de amônio 25 ppm/20min. e 50 ppm/5min., ácido peracético 6,25 ppm/10min. e 25 ppm/5min., clorhexidina 200 ppm/5min. e 12,5 ppm/15min., iodofor 50 ppm/5min. e hipoclorito de sódio 200 ppm/5min. Todos os desinfetantes avaliados podem ser usados para inativar as bactérias sobreviventes no matadouro-frigorífico. Por outro lado, a simulação indica que a manipulação in loco dos fatores concentração, tempo de contato e matéria orgânica, entre outros, podem permitir a sobrevivência dos microrganismos no ambiente.In the meat-processing industry, the efficient disinfection of meat contact surfaces is an important sanitary barrier to avoid deteriorating and potentially pathogenic microorganisms degrading the meat or pose a health hazard to consumers. Aiming to monitor antimicrobial activity through suspension test, the disinfectants ammonium quaternary, peracetic acid, chlorhexidine, iodophor and sodium hipochlorite were confronted with Escherichia coli, Staphylococcus aureus and two bacterial pools, all surviving organisms to hygienization in a bovine slaughterhouse with high slaughtering capability. The disinfectants were diluted in geometric degrees with factor 0,5, compounding five concentrations. Contact times were 5, 10, 15 and 20 minutes and, in order to simulate cleanliness deficiency to the disinfecting solution, 1% of organic matter in the form of sterile bovine serum was added. For statistical analysis, a variance analysis was effectuated with binomial distribution to variable response. Through this investigative line and the aforementioned indicator organisms, the lesser concentration per contact time to inactivate all bacterial culture were: ammonium quaternary 25 ppm/20min and 50 ppm/5min.; peracetic acid 6,25 ppm/10min and 25 ppm/5min.; chlorhexidine 200 ppm/5min and 12,5 ppm/15min.; iodophor 50 ppm/5 min and sodium hipochlorite 200 ppm/5 contact minutes. All evaluated disinfectants can be utilized to inactivate surviving bacterial cultures in the slaughterhouse. On the other hand, the simulation indicates that the in loco manipulation of factors concentration, contact time and organic matter, besides others, can allow the microorganisms survival in the medium.
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Park, Sang Hyuck. "Effect of amine-based water treatment polymers on the formation of N-nitrosodimethylamine (NDMA) disinfection by-product." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22549.
Повний текст джерелаАнотація:
In recent years, a compound N-nitrosodimethylamine (NDMA), a probable human carcinogen, has been identified as an emerging disinfection by-product (DBP) since its formation and detection were linked to chlorine-based disinfection processes in several water utilities in the U.S. and Canada. Numerous organic nitrogen compounds present in water may impact the formation of NDMA during disinfection. Amine-based water treatment polymers used as coagulants and flocculants have been suggested as potential NDMA precursors due to the presence of amine functional groups in their structures, as well as the possible presence of dimethylamine (DMA) residues in polymer products. To minimize the potential risk of NDMA associated with water treatment polymers, the mechanisms of how the polymers behave as NDMA precursors and their contribution to the overall NDMA formation under actual water treatment conditions need to be elucidated.
This research involved a systematic investigation to determine whether amine-based water treatment polymers contribute to NDMA formation under drinking water and wastewater treatment conditions, to probe the involved reaction mechanisms, and to develop strategies to minimize the polymers NDMA formation potential. The investigation included five research tasks: (1) General screening of NDMA formation potential of commonly used amine-based water treatment polymers, (2) NDMA formation from amine-based water treatment polymers under relevant water treatment conditions, (3) Probing the mechanisms of NDMA formation from polyamine and PolyDADMAC, (4) Effect of water treatment processes on NDMA formation from amine-based water treatment polymers, and (5) Developing strategies to reduce polymers NDMA formation potential. Direct chloramination or chlorination of high doses of polymers in deionized water at longer than typical contact time was used in the general screening of the NDMA formation potential of water treatment polymers and in the studies to identify reaction mechanisms. On the other hand, realistic dosages of chloramines and polymers and contact time were used in simulating representative water treatment conditions to evaluate the contribution of polymers to the overall NDMA formation in real systems. On the basis of the study results, strategies were developed to reduce the NDMA formation potential of amine-based water treatment polymers, which include modification of polymer structures and treatment parameters.
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Oliveira, Derly Tescaro Narcizo de. "Efeito da polimerização e desinfecção na resistência flexural e na topografia da superfície de resina acrílica /." Araçatuba : [s.n.], 2011. http://hdl.handle.net/11449/95782.
Повний текст джерелаАнотація:
Orientador: Francisco Antonio BertozCoorientador: Maria Cristina Rosifini Alves Rezende
Banca: Marcelo Coelho Goiato
Banca: Kurt Faltin Júnior
Resumo: A ação dos produtos desinfetantes sobre as propriedades físico-químicas da resina acrílica norteia sua seleção para a higienização de aparelhos ortodônticos removíveis. Avaliou-se a resistência à fratura de resina acrílica ativada quimicamente após ciclagem em diferentes soluções desinfetantes. Foram confeccionados quarenta corpos de prova com resina acrílica autopolimerizável incolor (Clássico,Ind.&Com.Ltda./Brasil) utilizando-se matriz metálica retangular e circular, seguindo-se às técnicas de polimerização sob pressão úmida (imersão em água/n=20) e sob pressão seca (sem água/n=20) foram subdivididos em 4 grupos (n=5), conforme a solução utilizada para ciclagem: água destilada (Controle), bicarbonato de sódio, hipoclorito de sódio 1% e Corega®Tabs. A ciclagem consistiu em imersão em 100 ml da solução por 10 minutos três vezes ao dia e, em seguida, manutenção em recipiente fechado contendo saliva artificial a 37ºC. Este ciclo foi realizado durante 30 dias, trocando-se as soluções e a saliva a cada procedimento executado. Na sequência os espécimes foram submetidos ao ensaio de resistência flexural a três pontos foi utilizada máquina EMIC DL3000, à velocidade de 5mm/min, dispondo-se as amostras em suporte contendo dois apoios de sustentação, sendo aplicada força axial e equidistante aos dois outro pontos até a ruptura do corpo-de-prova. Os espécimes circulares foram levados para leitura em Microscópio de Força Atômica (AFM - V Nanoscope Veeco). Os resultados, submetidos à análise de variância (P<0,001 ) e o Teste de Tuckey (P<0,05) não apontaram diferenças significantes para a resistência flexural. Conclui-se que os métodos de polimerização e as soluções testadas não modificaram a resistência flexural... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The disinfectant products action on the physicochemical properties of acrylic resin guides its selection to the cleaning of removable orthodontic appliances. The fracture resistance of acrylic resin after cycling in different disinfectant solutions was evaluated. Forty specimens were made with colorless acrylic resin (Clássico, Ind. & Com.Ltda. / Brazil), using matrix, followed by the techniques of polymerization under wet pressure (immersion in water / n = 20) and dry pressure (no water / n = 20). The samples were divided into 4 groups (n = 5) as the solution used for cycling: distilled water (Control), sodium bicarbonate, sodium hypochlorite 1% and Corega®Tabs. The cycling consisted of immersion in 100 ml of solution for 10 minutes three times a day and then maintained in a closed container containing artificial saliva at 37 º C. These cycles were conducted during 30 days, changing the solutions and artificial saliva for each procedure performed. Latter, the specimens were submitted to surface analysis with Atomic Force Microscope (AFM - Veeco Nanoscope V). A machine, EMIC DL3000, was used for the three-point flexural strength test, speed of 5mm/min, providing the sample in medium containing two restraints support. After that axial force was applied and equidistant to the two other points to the body to break the specimens. The results were submitted to analysis of variace(P<0,001) and Tuckey Test (P<0,05) showed no significant differences in flexural strength test. The Atomic Force Microscopy analysis revealed less topographical roughness for the group Corega®Tabs. We conclude that the polymerization methods and solutions tested did not alter the flexural strength of the material studied except the comparation between... (Complete abstract click electronic access below)
Mestre
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Cervero, Aragó Sílvia. "Eficàcia deIs desinfectants de I'aigua sobre Legionel·la spp. i les seves amebes hostes = Efficiency of water disinfectants against Legionella spp. and their amoeba hosts." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/128960.
Повний текст джерелаАнотація:
Les infeccions causades per Legionella són un greu problema de salut pública al nostre país. La majoria de casos esporàdics i de brots epidèmics es relacionen amb aigües de consum que han estat sotmeses a un o més processos de desinfecció. Tot i això, Legionella spp. no només és capaç de sobreviure a aquests tractaments sinó que es multiplica al llarg dels sistemes de distribució convertint-se en un risc ambiental.
Els principals factors que afavoreixen la supervivència i multiplicació de Legionella als sistemes d’aigua resideixen en la pròpia biologia del bacteri, que ha demostrat en moltes ocasions ser resistent a condicions físico-químiques extremes, així com les interrelacions que estableix amb altres microorganismes com els protozous, amb els que comparteix hàbitat. Els protozous, i en concret les amebes de vida lliure dels gèneres Acanthamoeba o Hartmannella s’han descrit en els últims anys com habitants freqüents dels sistemes de distribució d’aigua. Aquestes sobreviuen a condicions adverses mitjançant la formació d’estructures de resistència anomenades cists. La font nutricional de les amebes són els bacteris els qual fagocita i digereix. Tot i això, alguns d’aquests bacteris han desenvolupat estratègies per sobreviure la digestió amebiana i no sols això sinó que com en el cas de Legionella, poden fins i tot aprofitar els resursos cèl•lula hoste per multiplicar-se. A més, en estat endosimbiont Legionella queda protegida de l’efecte de desinfectants fet que podria originar una ràpida recolonització dels sistemes d’aigua un cop acabats els tractaments de desinfecció.
Tres dels desinfectants més utilitzats a nivell europeu per tractar l’aigua de consum són el clor, la temperatura i la radiació UV. Tot i que el seu ús està regulat en nombroses normatives estatals, aquestes s’apliquen sense tenir en compte les amebes de vida lliure i les interrelacions que aquestes poden tenir amb altres microorganismes. L’objectiu principal d’aquest treball va ser estudiar l’eficàcia d’aquests tres desinfectants de l’aigua aplicant les mateixes condicions d’estudi sobre Legionella spp.; amebes de vida lliure en els dos estats de vida, trofozoïts i cists; i sobre els simbionts que estableixen Legionella i Acanthamoeba.
En primer lloc es van obtenir soques de Legionella spp., i amebes de vida lliure de diferents orígens, tant ambientals com de col•lecció i es van optimitzar els protocols de cultiu dels diferents microorganismes, especialment pel que fa a les amebes. A continuació es van posar a punt mètodes quantitatius que ens permetessin comparar la viabilitat cel•lular després de cada tractament amb els tres desinfectants. I es van establir les condicions d’assaig per a cada un dels desinfectants. Finalment es van establir co-cultius per observar si l’associació entre Legionella i Acanthamoeba modificava d’alguna manera l’eficàcia dels desinfectant envers aquests dos microorganismes. La formació de co-cultius i el seu monitoreig mitjançant la tècnica del FISH ens va permetre observar com la soca de Legionella passava d’un estat plactònic a un estat d’emdosimbiont a l’interior dels trofozoïts.
Analitzant la susceptibilitat de les diferents soques de Legionella, d’amebes de vida lliure, tan en estat de trofozoït com de cist, així com de Legionella com a endosimbiont d’Acanthamoeba per cadascun dels tractaments aplicats, es van proposar diferents models per descriure’n la cinètica d’inactivació. A partir d’aquí els resultats obtinguts es van comparar amb altres estudis publicats i se’n van extreure unes conclusions finals.
Els resultats mostraren que clor, temperatura i radiació UV tenen un efecte desinfectant diferent pel que fa a les diferents soques de Legionella i amebes de vida lliure. Les diferències observades entre els diferents tractaments poden ser atribuïbles a la concentració de desinfectant, el temps d’exposició i a les diferències intrínseques de cada soca per cada microorganisme utilitzat. Pel que fa a la susceptibilitat de les amebes, trofozoïts i cists es van comportar de maneres diferents, sent els trofozoïts més sensibles que els cists. Finalment, L. pneumophila va resultar ser més resistent als tractaments amb desinfectants aplicats associada a trofozoïts d’Acanthamoeba en comparació amb el bacteri en condicions axèniques. Per tant, a l’hora d’aplicar tractaments de desinfecció, cal tenir en compte la complexa ecologia de Legionella com a endosimbiont d’amebes perquè aquests siguin eficaços i evitar així processos de recolonització.Legionella infections are serious problem which causes concern to health public services in our country. Despite all measures and controls realized, most sporadic cases and outbreaks have been related to drinking water systems that have been subjected to one or more disinfection processes. Legionella spp., not only survive these treatments but multiplied over the distribution system becoming a potential environmental hazard. The main factors that promote Legionella survival and proliferation in water systems are the bacteria biology itself, since Legionella is able to survive under a wide range of environmental conditions, as well as the relationship that Legionella establishes with other microorganisms that live in the same habitat as protozoa. Protozoa, and specifically free-living amoebae of the genera Acanthamoeba and Hartmannella have been described as common inhabitants of drinking water distribution systems. These amoebae survive in front harsh environmental conditions by forming resistant structures called cysts. Amoebae feed mainly on bacteria which are engulfed by phagocitosis and digested intracellularly. However, some of these bacteria have developed some strategies to survive amoebae digestion and some of them, as Legionella are able to use host cellular resources to multiply within it. In addition, as an endosimbiont, Legionella remains protected from disinfectants which could lead to a rapid recolonization of water distribution systems once disinfection treatments have been applied. Three of the most commonly used water disinfectants in Europe for drinking water treatment are chlorine, temperature and UV radiation. Although its use is regulated by many national guidelines, its efficacy relies mainly on bacterial inactivation without considering other microorganisms such as free living amoebae and its relationships with other microorganisms as Legionella. Therefore, the main objective of this work was to study the effectiveness of these three water disinfectants applying the same study conditions, on Legionella spp.; free-living amoebae considering its two life stages; and on the simbionts between Legionella and Acanthamoeba. First of all, several strains of Legionella spp., and free-living amoebae from different origins (environmental and from culture collections) were obtained and culture protocols were optimized, especially for free-living amoebae. Second, test conditions were established for each of the disinfectants and a quantitative method was implemented in order to compare cell viability after every disinfection treatment. Finally, to see whether the association between Legionella and Acanthamoeba modifies the effectiveness of the three disinfectants towards these two types of microorganisms, co-cultures of Legionella and Acanthamoeba were realized. Co-culture formation was monitored by using a FISH method, which led us observe how axenic Legionella changed to an intracellular state within Acanthamoeba trophozoites. Analyzing the susceptibility of the Legionella spp. strains; free-living amoebae strains, either trophozoites and cysts stages; as well as Legionella as an Acanthamoeba endosymbiont, for each of the treatments applied, inactivation kinetics models were proposed. Results obtained were compared with studies published by other authors and final conclusions were considered. Results showed that, chlorine, temperature and UV radiation have a disinfectant effect on the different Legionella strains used, as well as on free living amoebae. Differences on the disinfectant effect could be atributted to disinfectant concentration, exposure time and strain intrinsic characteristics. Regarding free living amoeba, trophozoites and cysts had a significantly different behaviour, being trophozoites more sensitive to disinfectants than cysts. Finally, L. pneumophila as and endosymbiont of amoeba strains showed a greater resistance to disinfectant compared with the axenic state. Because of that, when applying disinfections treatments, the complex ecology of Legionella as an amoeba endosymbiont should be considered in order to prevent a system recolonization.
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Altieri, Karen Tereza [UNESP]. "Efetividade de duas soluções desinfetantes e da irradiação por micro-ondas na desinfecção de próteses totais contaminadas com staphylococcus aureus resistente à meticilina (MRSA)." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/97284.
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Infecções causadas por bactérias resistentes a antibióticos são consideradas causa principal de mortalidade entre indivíduos imunocomprometidos e aproximadamente 50 % destas infecções tem sido relacionadas ao Staphylococcus aureus resistente à meticilina (MRSA). Estes microrganismos, quando presentes no biofilme das próteses dentarias, podem se dispersar nas secreções salivares e se disseminar pelo trato respiratório, causando pneumonia aspirativa. Assim, o presente estudo comparou a efetividade do hipoclorito de sódio a 1 %, digluconato de clorexidina a 2 % e irradiação por micro-ondas na desinfecção de próteses totais e corpos-de-prova circulares de resina acrílica para base de prótese (10 x 2 mm) contaminados com MRSA. Para isso, 36 próteses totais simuladas e 36 corpos-de-prova circulares foram confeccionados, esterilizados, inoculados com MRSA (107 ufc/mL) e incubados a 37 °C (por 24 e 48 h, respectivamente). Após incubação, próteses totais e corpos-de-prova foram distribuídos em 4 grupos de estudo (n=9): GC - não foi realizado nenhum método de desinfecção; GH - foi realizada a imersão em solução de hipoclorito de sódio a 1 % por 10 min; GCl -foi realizada a imersão em solução de digluconato de clorexidina a 2 % por 10 min; GM - foi realizada a desinfecção por irradiação em forno de micro-ondas a 650 W por 3 min. A efetividade dos procedimentos de desinfecção foi avaliada por meio de quantificação de colônias viáveis e da viabilidade celular. Para a quantificação de colônias viáveis, alíquotas de 25 μL da solução resultante das diluições seriadas (10-3 a 10-6 para GC e 100 a 10-3 para os grupos experimentais) foram semeadas em placas de Petri em duplicata e todas as placas foram incubadas por 48 h a 37 °C. As colônias foram quantificadas em ufc/mL. Para verificar a efetividade da desinfecção por micro-ondas em longo prazo...
Infections caused by antibiotic-resistant bacteria have been recognized as a predominant risk factor for mortality in elderly patients and approximately 50 % of these infections have been related to methicillin-resistant Staphylococcus aureus (MRSA). This microorganism, when present in the denture biofilm, can be released into the oral fluids and aspirated into the lower respiratory tract, thus causing infections such as aspiration pneumonia. The present study compared the efficacy of 1 % sodium hypochlorite, 2 % chlorhexidine gluconate, and microwave irradiation in disinfecting simulated complete dentures and circular specimens of acrylic resin denture base material (10 x 2 mm) contaminated with MRSA. Thirty-six dentures and 36 specimens were made, sterilized, inoculated with MRSA (107 cfu/mL), and incubated at 37 °C (for 24 and 48 h, respectively). After incubation, dentures and specimens were divided into 4 groups of study (n=9): PC - positive control, consisting of dentures and specimens not disinfected; HY - soaking in 1 % sodium hypochlorite solution for 10 min; CHL - soaking in 2 % chlorhexidine gluconate solution for 10 min; and MW - irradiating by microwave for 3 min at 650W. The effectiveness of the disinfection procedures was assessed cell viability (quantification of viable cells and XTT reduction method). For quantification procedures, aliquots of suspensions were plated at dilutions (10-3 to 10-6 for PC and 100 to 10-3 for experimental groups) and incubated (37 °C/48 h). Colonies counts (cfu/mL) were quantified. Dentures disinfected were also incubated at 37 °C for 7 days to verify the long-term effectiveness of disinfection. The viability of cells in each group of specimens was evaluated by XTT reduction method. The results showed that all dentures and specimens from the PC groups showed substantial microbial growth. No evidence of microbial growth was observed... (Complete abstract click electronic access below)
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Altieri, Karen Tereza. "Efetividade de duas soluções desinfetantes e da irradiação por micro-ondas na desinfecção de próteses totais contaminadas com staphylococcus aureus resistente à meticilina (MRSA) /." Araraquara : [s.n.], 2011. http://hdl.handle.net/11449/97284.
Повний текст джерелаАнотація:
Orientador: Carlos Eduardo VerganiBanca: Ana Lucia Machado
Banca: Wander José da Silva
Resumo: Infecções causadas por bactérias resistentes a antibióticos são consideradas causa principal de mortalidade entre indivíduos imunocomprometidos e aproximadamente 50 % destas infecções tem sido relacionadas ao Staphylococcus aureus resistente à meticilina (MRSA). Estes microrganismos, quando presentes no biofilme das próteses dentarias, podem se dispersar nas secreções salivares e se disseminar pelo trato respiratório, causando pneumonia aspirativa. Assim, o presente estudo comparou a efetividade do hipoclorito de sódio a 1 %, digluconato de clorexidina a 2 % e irradiação por micro-ondas na desinfecção de próteses totais e corpos-de-prova circulares de resina acrílica para base de prótese (10 x 2 mm) contaminados com MRSA. Para isso, 36 próteses totais simuladas e 36 corpos-de-prova circulares foram confeccionados, esterilizados, inoculados com MRSA (107 ufc/mL) e incubados a 37 °C (por 24 e 48 h, respectivamente). Após incubação, próteses totais e corpos-de-prova foram distribuídos em 4 grupos de estudo (n=9): GC - não foi realizado nenhum método de desinfecção; GH - foi realizada a imersão em solução de hipoclorito de sódio a 1 % por 10 min; GCl -foi realizada a imersão em solução de digluconato de clorexidina a 2 % por 10 min; GM - foi realizada a desinfecção por irradiação em forno de micro-ondas a 650 W por 3 min. A efetividade dos procedimentos de desinfecção foi avaliada por meio de quantificação de colônias viáveis e da viabilidade celular. Para a quantificação de colônias viáveis, alíquotas de 25 μL da solução resultante das diluições seriadas (10-3 a 10-6 para GC e 100 a 10-3 para os grupos experimentais) foram semeadas em placas de Petri em duplicata e todas as placas foram incubadas por 48 h a 37 °C. As colônias foram quantificadas em ufc/mL. Para verificar a efetividade da desinfecção por micro-ondas em longo prazo... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Infections caused by antibiotic-resistant bacteria have been recognized as a predominant risk factor for mortality in elderly patients and approximately 50 % of these infections have been related to methicillin-resistant Staphylococcus aureus (MRSA). This microorganism, when present in the denture biofilm, can be released into the oral fluids and aspirated into the lower respiratory tract, thus causing infections such as aspiration pneumonia. The present study compared the efficacy of 1 % sodium hypochlorite, 2 % chlorhexidine gluconate, and microwave irradiation in disinfecting simulated complete dentures and circular specimens of acrylic resin denture base material (10 x 2 mm) contaminated with MRSA. Thirty-six dentures and 36 specimens were made, sterilized, inoculated with MRSA (107 cfu/mL), and incubated at 37 °C (for 24 and 48 h, respectively). After incubation, dentures and specimens were divided into 4 groups of study (n=9): PC - positive control, consisting of dentures and specimens not disinfected; HY - soaking in 1 % sodium hypochlorite solution for 10 min; CHL - soaking in 2 % chlorhexidine gluconate solution for 10 min; and MW - irradiating by microwave for 3 min at 650W. The effectiveness of the disinfection procedures was assessed cell viability (quantification of viable cells and XTT reduction method). For quantification procedures, aliquots of suspensions were plated at dilutions (10-3 to 10-6 for PC and 100 to 10-3 for experimental groups) and incubated (37 °C/48 h). Colonies counts (cfu/mL) were quantified. Dentures disinfected were also incubated at 37 °C for 7 days to verify the long-term effectiveness of disinfection. The viability of cells in each group of specimens was evaluated by XTT reduction method. The results showed that all dentures and specimens from the PC groups showed substantial microbial growth. No evidence of microbial growth was observed... (Complete abstract click electronic access below)
Mestre
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Pires, Marco Roberto. "Desinfecção de esgotos com radiação ultravioleta : influencia da qualidade do efluente e da fotorreativação." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258116.
Повний текст джерелаАнотація:
Orientador: Jose Euclides Stipp PaternianiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil
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Resumo: Desinfecção de esgotos com radiação ultravioleta vem sendo utilizado, principalmente, em países europeus e nos EUA. A fotorreativação dos microrganismos tem sido avaliada para determinar seu grau de interferência na desinfecção. Este trabalho teve como objetivo avaliar a radiação ultravioleta para diferentes qualidades de efluentes e estudar a fotorreativação. Foram utilizados dois reatores diferentes, sendo um com lâmpadas emersas e outro imersa. Os reatores foram testados em seis efluentes diferentes para quatro vazões diferentes para cada reator. Os coliformes totais e fecais foram analisados para avaliar a eficiência dos reatores. Ensaios de fotorreativação em condições controladas foram realizadas. De forma geral, o Reator I foi mais eficiente que o Reator TI, e a qualidade do efluente muitas vezes foi mais importante que a dose aplicada como apresentada no Ponto de Coleta 3 para coliformes fecais, em que a inativação foi maior para a vazão 4 (com menor tempo de exposição à luz) em vez de ocorrer para a vazão 1 (com maior tempo de exposição). Doses de radiação ultravioleta mais altas implicam em valores iniciais e finais de fotorreativação menores, porém para atingir o valor máximo necessita de mais tempo. Quanto maior a dose de radiação ultravioleta aplicada menor é o grau de fotorreativação; os coliformes totais tem melhor correlação para análises desta natureza quanto comparado com a E.co/i
Abstract: Disinfection of effluents with ultraviolet radiation has been used in Europeans countries and United States. The photoreactivation of microorganism have been estimated to determine the influence on the disinfection. The objective of this work had to evaluate the ultraviolet disinfection to different qualities of effluent and photoreactivation. Two different kinds of reactors were used in experimental analyzed. The reactors were tested to six different effluents for four flows. Total and fecal coliforms were analyzed to estimate the efficiency of reactors. Assays of photoreactivation were analyzed in controlled conditions. In most of case, the Reactor I was more efficient than Reactor II, and effluent quality was more important than the dose uv applied. Dose uv higher imply in initial and final values of lower photoreactivation. The total coliforms have better correlation than E.coli
Doutorado
Saneamento e Ambiente
Doutor em Engenharia Civil
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Oosthuysen, Jeanné. "Infection prevention and control audit-feedback instrument for oral health care in South Africa." Thesis, Bloemfontein: Central University of Technology, Free State, 2015. http://hdl.handle.net/11462/669.
Повний текст джерелаАнотація:
Thesis (D. Tech. (Biomedical Technology)) -- Central University of Technology, Free State, 2015This study reviewed national and international literature to develop an audit-feedback instrument (AFI) to monitor adherence of South African oral health care facilities with compliance to infection prevention and control precautions. In a multi-phased literature search, existing infection prevention and control recommendations, guidelines and audit-feedback instruments were reviewed and broadened to include “dental audit tools”, as well as audit tools from other health care disciplines. Audit-feedback instruments were scrutinised for user friendliness, the use of simple language, electronic calculations and feedback possibilities. A new South African AFI was proposed, considering the differences between public and private oral health care facilities and also the diversity of training levels of oral health care personnel employed. Eleven focus areas supporting all aspects of infection prevention and control in oral health care facilities, including administrative controls; personnel protection controls; environmental- and work controls; surface contamination management; equipment maintenance, service or repair; air- and waterline management; personal protective equipment usage; personal and hand hygiene practices; sterilisation practices; safe sharps handling and waste management were included. The AFI was tested in a sample of 50 oral health care facilities. None of the participating facilities demonstrated 100% compliance. Personal- and hand hygiene practices and waste management performed the best, at respectively 75% and 63%, while administrative controls and air- and waterline management scored the lowest mean values; 31% and 36% respectively The general lack of compliance with infection prevention and control precautions in the participating oral health care facilities clearly poses a safety hazard to both patients and oral health care workers. Results indicate that adherence of South African oral health care facilities with compliance to infection prevention and control precautions need to be improved. The AFI should go a long way towards improving safety and the high expectations about providing quality infection prevention and control outcomes in oral health care.
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Mücke, Naieli. "Sensibilidade celular e de biofilme de Enterococcus sp. aos desinfetantes de uso industrial." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/2184.
Повний текст джерелаАнотація:
CNPQEnterococcus sp. podem ser isolados de seres humanos, animais e ambiente; possuem alta tolerância a fatores extremos como pH, temperatura e concentração salina. Desempenham papel importante como cultura starter em vários produtos como iogurtes e queijos, além de serem produtores de enterocinas. Contudo, é crescente seu potencial como agentes causadores de sérias infecções, podendo adquirir alta resistência a antimicrobianos e biocidas. Os equipamentos na indústria alimentícia estão propensos à alta contaminação microbiológica devido à presença de substratos para os microrganismos, e quando não higienizados permitem que os microrganismos se desenvolvam até formarem biofilmes, contaminando o produto final. Este estudo teve por finalidade realizar o isolamento de cepas do gênero Enterococcus de equipamentos das linhas de processos de embutidos cárneos cozidos e de iogurtes, identificar através de técnicas moleculares as espécies dos isolados, verificar a suscetibilidade biocida a sete formulações de diferentes desinfetantes de uso industrial e ação destes sobre o biofilme. Nas amostras coletadas na linha de iogurtes não houve o crescimento de colônias indicativas. Das 36 amostras coletadas nas linhas de produção de embutidos cárneos cozidos, selecionou-se 40 colônias que ao submeter à avaliação genotípica, obtivemos que 70,0% (28 isolados) possuíam o gene tuf que identifica o gênero Enterococcus sp. Identificamos que 7,1% pertenciam aos gêneros E. faecium, 7,1% E. gallinarum, 7,1% E. casseliflavus/E. flavencens e 78,7% dos isolados não foram identificados ao nível de espécie com os oligonucleotídeos iniciadores utilizados neste estudo. Ao avaliar a ação de sanitizantes sobre células de Enterococcus sp. na presença de água verificou-se que nenhum produto utilizado conseguiu ser totalmente eficiente no controle do desenvolvimento dos enterococos em presença de água. Nos testes utilizando BHI e sanitizante os isolados apresentaram menor desenvolvimento na presença do sanitizante amônia quaternária D em todos os tempos, sendo que nos tempos 15 minutos, 1, 2, 3 e 24 horas não houve desenvolvimento. O maior desenvolvimento ocorreu na presença dos produtos dióxido de cloro, hipoclorito de sódio e ácido peracético em todos os tempos, sendo que para os dois primeiros produtos todos os isolados foram resistentes em todos os tempos. Independente do tipo de sanitizantes e biofilme formado, nenhum agente químico foi eficaz na eliminação total das células de Enterococcus. Nota-se que os biofilmes formaram-se mesmo sobre as superfícies sanitizadas, mesmo que tenham sido utilizados as concentrações e tempo médios recomendados pelos fabricantes. É indispensável ressaltar que os resultados confirmam a importância de ações preventivas nas indústrias para evitar a resistência dos microrganismos a determinados compostos e maximizar a eficiência dos procedimentos de higienização aplicados.
The Enterococcus sp. may be isolated from humans, animals and environment. It presents high tolerance to extreme factors such as pH, temperature and salt concentration. It has an important role as a starter culture in different products such yogurts and cheeses, and as producers of enterocinas. However, its potential as agents of serious infections has increasing, especially because can acquire high resistance to antimicrobials and biocides. The food industry equipment’s are willing to high microbiological contamination due to the presence of substrates for microorganisms. When dirty, allow the microorganisms grow and biofilm formation, contaminating the final product. The aim of this work was isolated the genus Enterococci strains of equipment’s on pork cooked sausages and yogurts lines, identified through molecular techniques and check the biocide susceptibility of seven formulations of different industrial disinfectants and the action of these on the biofilm. On the yogurts line samples analyzed there was no grow of indicative colonies. Of the 36 samples analyzed in the sausage line, 40 colonies were selected to undergo genotypic evaluation, showing that 70.0% (28 isolates) had the tuf gene that identifies the genus Enterococcus sp. It was verified that 7.1% belonged to the genus E. faecium, 7.1% E. gallinarum, 7.1% E. casseliflavus/E. flavencens and 78.7% of the isolates were not identified to species level using the oligonucleotides used in this study. In assessing the sanitizing action on cells of Enterococcus sp. in the presence of water there was no product that could be used effectively on grow control of enterococci. In tests using BHI and sanitizing the isolates were less developed in the presence of quaternary ammonia sanitizer D at all times, and in the time 15 minutes, 1, 2, 3 and 24 hours there was no development. Further development occurred in the presence of chlorine dioxide, sodium hypochlorite and peracetic acid at all times, and for the first two products all isolates were resistant at all times. Regardless of the sanitizers and biofilm formed, no chemical agent was effective in complete elimination of Enterococcus cells. Note that biofilms were formed even on the sanitized surfaces even though the average concentration-time recommended by the manufacturer was used. Indispensable to emphasize that the results confirm the importance of preventive actions in the industries to avoid the resistance of microorganisms to certain compounds and maximize the efficiency of applied hygiene procedures.
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Mogotsi, Lerato Bonolo. "An assessment of the lipopolysaccharide toxicity of rough and smooth escherichia coli strains cultivated in the presence of zygosaccharomyces bailli." Thesis, Bloemfontein : Central University of Technology, Free State, 2011. http://hdl.handle.net/11462/151.
Повний текст джерелаАнотація:
Thesis (M. Tech. Environmental health) -- Central University of technology, Free State, 2011In nature microorganisms do not exist alone, but in association with one another. These kinds of associations can also be found in food industries, where cells of the same or different species can attach to pipes (biofilm formation) and a variety of surfaces in food processing environments and in food product such as yoghurt which can contain both yeast and bacteria originating from the starter culture as well as fruit. To control food spoilage organisms and food-borne pathogens preventative measures such as good manufacturing processes, the use of sanitizers and preservatives as well as hazard analysis critical control points (HACCP) are crucial in food industries. Sanitation of the working surface, floors, pipes, containers and equipment is a stepwise application of a detergent, acid or alkali rinse, a disinfectant treatment followed by final rinsing. If rinsing of the sanitizer is not done properly it may end up in the product in sub-lethal doses. In this study the influence of Liquid Hypochlorite (LH) and Liquid Iodophore (LI) sanitizers on organism growth and toxicity was evaluated. The organisms investigated included Escherichia coli 0113, Escherichia coli 026 and Zygosaccharomyces bailii Y-1535 in yeast malt broth, which was supplemented with LH and LI at sub-lethal concentrations 0.05% LH, 0.2% LH and 0.075% LI. Subsequently, bacterial and yeast growth responses as pure cultures and in combination (E. coli + Z. bailii) were measured as colony forming units and optical density values. Incorporation of the sanitizers in the growth media resulted in different levels of growth inhibition. Z. bailii proved more robust and the growth rate was not influence significantly by the addition of sanitizers or communal growth with either E. coli strains. The growth rate of both E. coli strains decreased where grown in combination with Z. bailii as well as in the presence of sanitizers, with the most influence exerted by LH. Changes in endotoxicity following the growth of the test samples (stressed cells) and the control (unstressed) were measured by the limulus amoebocyte lysate (LAL) and porcine IL-6 ELISA methods. Where E. coli strains were cultured together with Z. bailii the toxicity of tire mixture showed a decrease over time when measured with the limulus amoebocyte assay method. Interestingly the communal growth of the E. coli strains and Z bailii produced different toxicity profiles when the IL-6 porcine method was used, hi both cases, where E. coli strains were cultured together with Z. bailii the toxicity of the mixture showed an increase over tune when measured by this assay. Other than a similar toxicity profile for E. coli 0113 grown in pure culture, the comparison between results obtained using the LAL or porcine IL-6 methods yielded no correlation in determined toxicity. It was established that LH and LI sanitizers as well as communal growth had an influence in the toxicity of LPS/EPS and the method used to determine such toxicity should be carefully considered.