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1
Garlapalli, Ravinder Kumar. « Leaching of chalcopyrite with sodium hypochlorite ». Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11213.
Texte intégralRésumé :
Thesis (M.S.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains vii, 47 p. : ill. Includes abstract. Includes bibliographical references (p. 46-47).
2
Udeaja, Joseph Onuorah. « The chemistry of novel chromium(IV) systems and fluorinated hypochlorites ». PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3652.
Texte intégralRésumé :
Chromium(IV) has been of interest for some time because of its role as an intermediate in chromic oxidation reactions. Since there are not a great number of stable tetravalent chromium complexes known, and the use of such species as oxidizing agents has not been widely explored, the preparation, isolation and characterization of new stable tetravalent chromium species may allow chemists the opportunity to more fully understand the role which tetravalent chromium plays in oxidation reactions. The present study thus involves the synthesis of Cr(OC4H9)4 and other Cr(IV) derivatives and the use of Cr(OC4H9)4 in oxidative reactions with selected fluoridated alcohols. Interestingly, the reaction of fluoridated alcohols with Cr(OC4H9)4 or Cr(NEt2)3 was found to be a useful method for preparing products.
3
Sun, Zhenning. « Studies on fluorescent probes for the specific detection of reactive oxygen species and reactive nitrogen species in living cells ». View the Table of Contents & ; Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36845395.
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Sun, Zhenning, et 孫振宁. « Studies on fluorescent probes for the specific detection of reactive oxygen species and reactive nitrogen species in living cells ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38677490.
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5
Zoete, Vincent. « Design, synthèse et étude des propriétés antooxydantes de 4-mercaptoimidazoles dérivés des ovothiols ». Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-167.pdf.
Texte intégralRésumé :
Une série de quatorze 4-mercaptoimidazoles, dérivés d'une famille d'antioxydants naturels appelés ovothiols, fut synthétisée par formation d'un cycle imidazole diversement substitué, à partir de molécules linéaires de type 2-(N-carbonyl-N-alkyl)thioacétamide ou 2-(N-carbonyl-N-aryl)thioacétamide. La cyclisation fut obtenue par réaction des fonctions amide et thioamide du précurseur en présence de trifluorométhanesulfonate de triméthylsilyle. Les 4-mercaptoimidazoles, notamment ceux substitués par des groupement électro-attracteurs en position 2 ou 5 du noyau imidazole, révélèrent dans un premier temps une forte capacité à piéger les radicaux que sont le 2,2-diphényl-1-picrylhydrazyle et le sel de Fremy. La suite de l'étude montra que ces mêmes molécules présentent aussi une forte réactivité vis-à-vis d'oxydants naturels dérivés de l'oxygène, comme le peroxyde d'hydrogène, le radical hydroxyle ou l'hypochlorite. Le mécanisme de piégeage des radicaux par les 4-mercaptoimidazoles fut étudié par modélisation moléculaire, voltammétrie cyclique, RPE et RMN. La production d'un disulfure via la formation d'un radical thiyle put être postulée. Les potentiels de demi-réactions d'oxydation et de réduction des 4-mercaptoimidazoles furent mesurés, et l'adduit DMPO-radical thiyle fut caractérisé par RPE. L'activité des molécules étudiées en tant qu'inhibiteurs de la peroxydation lipidique fut aussi testée. Il fut montré à cette occasion que les 4-mercaptoimidazoles sont capables d'inhiber l'oxydation des LDL par piégeage des radicaux mis en jeu, et par complexation du cuivre, Cu 2+, qui intervient dans le mécanisme de peroxydation lipidique. Enfin, l'activité glutathion peroxydase-like des composés fut évaluée. Ces différents tests démontrent donc l'activité antioxydante des 4-mercaptoimidazoles, activité pouvant être modulée par substitution du noyau imidazole.
6
Ravereau-Delattre, Jennifer. « Étude du vieillissement en milieu chloré de membranes fibres creuses en poly(fluorure de vinylidène) utilisées dans le traitement de l'eau ». Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0009/document.
Texte intégralRésumé :
Les processus de lavage, et plus particulièrement l'utilisation de solutions chlorées, peuvent engendrer une dégradation prématurée des membranes de filtration d'eau. Alors que le marché des technologies membranaires en PVDF est en pleine expansion, peu de travaux portent sur l'étude de leur dégradation sur le long terme. Dans ce contexte, la thèse a porté sur l'étude du vieillissement de membranes de filtration commercialisées en PVDF. Les échantillons sont immergés dans une solution d'hypochlorite de sodium et l'effet du pH sur leur dégradation est approfondi. Les propriétés mécaniques, d'hydrophilie, les performances hydrauliques ainsi que la porosité sont étudiées. L'évolution des propriétés est mise en relation avec la structure chimique étudiée à différentes échelles : moléculaire, macromoléculaire et supramoléculaire. Cette approche n'a à ce jour jamais été utilisée dans le cas des membranes fibres creuses en PVDF. Les analyses en chromatographie d'exclusion stérique révèlent les modifications les plus importantes. La dégradation du PVDF des membranes se traduit par un phénomène prédominant de coupures de la chaîne principale du PVDF accompagné, dans une moindre mesure, d'un phénomène de réticulation. Les principales modifications sont constatées à des pHs inférieurs à 10 révélant la possible action conjointe des radicaux OH•, ClO• et Cl•. Le vieillissement d'une membrane PVDF additivée montre à la fois une dégradation du PVDF et une élimination des additifs. Alors que la membrane sans additif conserve une stabilité de ses propriétés, l'élimination des additifs entraine une évolution de la porosité et une propension au colmatage plus importante. Cependant, les membranes PVDF conservent des propriétés d'utilisation acceptables au regard des conditions extrêmes de vieillissement étudiéesThe cleaning processes, especially the use of chlorine solutions, may cause the untimely degradation of the water filtration membranes. While the market for PVDF membrane-based treatment technologies is rapidly expending, only few works deal with the study of their ageing on a long-term basis. In this context, this project focuses on the study of the ageing of two PVDF filtration membranes. Samples are immersed in a sodium hypochlorite solution and the effect of the chlorine solution pH is investigated. The properties of the membranes are characterized throughout the study by tensile tests, hydrophilicity, hydraulic performances and porosity analysis. The evolution of properties is related to the chemical structure of the membranes at a molecular, a macromolecular and a supramolecular scale. Until now, this approach has never been used in the case of PVDF membranes under chlorine conditions. The size exclusion chromatography analyses revealed the most important modifications. The degradation occurs mainly by chain scissions of the PVDF and crosslinking phenomenon in lesser extent. The main modifications occurred at pH less than 10 proving the joint action of OH•, ClO• and Cl• radicals. The ageing of the PVDF membrane containing additives showed at the same time the PVDF degradation and the elimination of the additives. Whereas the properties of the additive-free PVDF membrane were preserved, the elimination of additives led to a modification of the porosity and an increased fouling. However, even if the PVDF degradation is proved, the using properties of the PVDF membranes remain acceptable taking into consideration extreme conditions of ageing studied
7
Gorchkov, Dmitri. « Optimisation des performances de quelques micro-biocapteurs de type enfet : Utilisation de polymères pour la réalisation de membranes sensibles et additionnelles : Application à la détection de l'urée, de la pénicilline et des anions hypochlorites ». Ecully, Ecole centrale de Lyon, 1996. http://www.theses.fr/1996ECDL0053.
Texte intégralRésumé :
Ce travail concerne l'elaboration et l'etude du comportement de membranes polymeriques en vue de l'optimisation de micro-biocapteurs de type enfet (enzymatic field effect transistor) plus particulierement destines au domine du biomedical et de l'environnement. La premiere partie, etayee par une revue bibliographique, montre l'importance des divers elements constitutifs d'un biocapteur et souligne l'importance des methodes d'immobilisation de l'enzyme ainsi que le role joue par les membranes additionnelles. Ce dernier point est developpe dans le chapitre 2 ou l'influence de la charge electrique d'une telle membrane est precisee. L'etude est illustre par la detection de l'uree et de la penicilline. Dans le cas de l'uree, l'utilisation de membranes additionnelles, l'optimisation des conditions de stockage permet d'aboutir a un micro-biocapteur operationnel sur une duree de trois mois. Une derniere partie montre que la connaissance des mecanismes reactionnels se deroulant au sein de la membrane enzymatique, et en particulier ceux d'inhibition, permet la detection des especes hypochlorite
8
Burgess, Laura Margaret. « Cytotoxicity of Hypochlorite-oxidised Proteins ». Thesis, University of Canterbury. Biological Sciences, 2012. http://hdl.handle.net/10092/7041.
Texte intégralRésumé :
The role of cell death in atherosclerosis remains ill-defined, however, a growing body of evidence suggests that cell death stimulates atherogenesis through the induction of inflammation and enlargement of the necrotic core. Although there is solid evidence to suggest that lipid oxidation and toxicity are linked, indications that protein oxidation may play an important role in cytotoxicity are numerous. The abundance of dead cells in atherosclerotic plaques and their co-localization with HOCl-modified proteins provides an opening for the suggestion that the products of protein oxidation may be at the heart of oxLDL-induced cell death. Examination of the modification of LDL and albumin by HOCl, and the cytotoxicity of these oxidised molecules were the focus of this study, along with the elucidation of their cell death mechanisms toward U937 cells.
Measurement of lipid peroxidation markers, TBARS and 7-ketocholesterol, showed no significant increase in HOCl-oxLDL compared to native levels although all α-tocopherol had been lost. In contrast there was a large loss of tyrosine, of which a small percentage went to dityrosine, indicating that the protein moiety of LDL was the main target of HOCl attack. Albumin became fragmented and smeared on SDS-PAGE gels with increasing HOCl/BSA molar ratios. In addition there was significant reduction in tyrosine levels and a small increase in dityrosine.
Both HOCl-oxLDL and oxidised albumin (oxALB) caused concentration-dependent cell viability loss in U937 cells following a significant drop in intracellular GSH concentration, coinciding with a peak in oxidative stress. Removal of chloramines with methionine significantly reduced the toxicity of oxALB, but at higher concentrations this effect was reduced. This was in contrast to HOCl-oxLDL where the removal of chloramines had no effect on its toxicity. Morphological observations of cell swelling, cell membrane integrity loss and rupture, along with flow cytometry results indicate that U937 cells underwent necrosis, but only after intracellular GSH was lost. Intracellular GSH and cell viability loss were prevented by 200 μM extracellular 7,8-dihydroneopterin (78NP), indicating that 78NP scavenging of ROS generated in response to the oxidised proteins was sufficient to prevent cell death.
This study demonstrates the cytotoxicity of HOCl-damaged LDL and albumin is likely due to a common oxidative product or structural motif which may be active within atherosclerotic plaques.
9
Li, Wei. « Coal desulfurization with sodium hypochlorite ». Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3546.
Texte intégralRésumé :
Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains vii, 32 p. : ill. Includes abstract. Includes bibliographical references (p. 32).
10
Pellillo, Sonni. « Effects of sodium hypochlorite on enamel composition ». Thesis, NSUWorks, 2015. https://nsuworks.nova.edu/hpd_cdm_stuetd/66.
Texte intégralRésumé :
The purpose of this study was to evaluate the effects of sodium hypochlorite on the organic and inorganic composition of enamel. Background: With the advent of enamel bonding for orthodontic appliances in the late 1970s, it has been shown that traditional phosphoric acid etching affects the inorganic portion of the enamel.1, 2 In an attempt to enhance the acid etching pattern and, furthermore, the bond strength, additional pretreatment techniques that target the organic components of the enamel biofilm have been proposed. One such method is the non-invasive enamel pretreatment with 5.25% sodium hypochlorite (NaOCl) prior to phosphoric acid etching.3, 4 It has been suggested that the mechanism by which sodium hypochlorite enhances the etching pattern is enamel deproteinization, in which organic elements, including the acquired film, are removed from the enamel surface.3, 5 This presumption is based on the multitude of endodontic literature supporting the use of NaOCl as an effective irrigant in root canal therapy6-13. In contrast to dentin and pulpal tissue, enamel is comprised of minimal organic matter.14, 15 As a result of this fact and the limited amount of experimentation of the effect of NaOCl on the enamel surface, the true mechanism by which sodium hypochlorite enhances the etching pattern of enamel is questionable.5, 16 The objective of this study was to determine the compositional effects of sodium hypochlorite on human enamel. Methods: Following IRB approval, 120 enamel sections from 22 extracted human premolar teeth were randomly divided into three experimental groups and one control group.17 The control group (E = enamel) received no treatment. The first experimental group (A = phosphoric acid) received a 15-second treatment with 37% phosphoric acid, rinsed with distilled water and air sprayed for 20 seconds, then dried with oil free compressed air. The second experimental group (H = sodium hypochlorite) received a treatment of 5.25% sodium hypochlorite for 60 seconds, washed with distilled water for 10 seconds, and dried. The third experimental group (HA = sodium hypochlorite + phosphoric acid) received a treatment of 5.25% sodium hypochlorite for 60 seconds, washed with distilled water for 10 seconds, dried, then receive the 15-second treatment with 37% phosphoric acid as in Group A.3 Following treatment preparations of the four groups, scanning electron microscopy (SEM)/energy-dispersive X-ray spectrometer (EDX) analysis was performed for all groups.18 For elemental concentration, a one-way ANOVA and Tukey’s post hoc statistical tests were applied.17, 19, 20 ANOVA and Tukey tests were performed at a significance level of p ≤ 0.05. Results: There were no significant effects of treatment on the enamel elements carbon (C), calcium (Ca) sodium (Na), oxygen (O), and phosphorous (P). There was a significant effect of treatment on the amount of chlorine (Cl) in enamel between groups acid (A) and hypochlorite + acid (HA) as well as between groups hypochlorite (H) and hypochlorite + acid (HA) (p = 0.004). The amount of variation of iodine (I) in the enamel composition between untreated enamel (E) and enamel treated with sodium hypochlorite + phosphoric acid (HA) was significant (p = 0.004). Additionally, there was a significant decrease in the quantity of antimony (Sb) found in the control group (E) versus the hypochlorite + acid (HA) experimental group (p = 0.002). Lastly, tin (Sn) was significantly reduced from the enamel surface (E) when treated with hypochlorite + acid (HA) (p = 0.008). Conclusions: The various treatments minimally affected the elemental concentrations of C, Ca, Na, O, and P. The amount of chlorine present in enamel significantly increased following treatment with sodium hypochlorite (H) alone and even more so following treatment with phosphoric acid and sodium hypochlorite (AH). In contrast, elements I, Sb, and Sn demonstrated a congruent reduction in concentration after treatment with hypochlorite and acid (HA). Although it has been hypothesized that sodium hypochlorite targets the organic pellicle present on the surface of enamel via a process known as deproteinization, the findings presented here suggest that pre-treatment with NaOCl impacts the inorganic components of enamel more so than the organic constituents. These quantitative findings corroborate the enhanced etching pattern that can be visualized under scanning electron microscopy in this as well as previous studies.
11
Praisarnti, Chonrada. « Low-cycle fatigue of NiTi rotary instruments in hypochlorite ». Thesis, View the Table of Contents & ; Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38727365.
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Abduljabbar, Fouad Abdulbaky. « Low-cycle fatigue of NiTi rotary instruments in hypochlorite ». Thesis, Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43224039.
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Van, Zyl Nadine (Nadine Nicole) 1975. « Sodium hypochlorite generation for household water disinfection in Haiti ». Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84292.
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Pitanga, Fernanda Luna. « The effect of sodium hypochlorite in different aquatic organisms ». Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/8703.
Texte intégralRésumé :
Mestrado em Biologia Aplicada - Toxicologia e EcotoxicologiaOs desinfectantes são substâncias utilizadas em determinadas superfícies ou áreas com o objectivo de matar microorganismos. O hipoclorito de sódio (HS) é um produto químico usado em larga escala, frequentemente como substância lixiviante ou desinfectante. O HS é usado em hospitais, várias indústrias (química, farmacêutica, de papel, de tratamento de águas residuais, entre outras), bem como nos lares sob a forma de lixívia. Os desinfectantes baseados em cloro reagem com a matéria orgânica em águas residuais, formando compostos organoclorados. Estes, são persistentes no ecossistema e tóxicos para os organismos aquáticos. No presente estudo, a toxicidade do HS foi avaliada em organismos pertencentes a diferentes níveis tróficos. Na primeira parte deste trabalho foi-se analisado o efeito do HS a curto prazo em diferentes organismos aquáticos para avaliar as suas diferentes sensibilidades. Os efeitos do HS foram estimados no crescimento das algas Pseudokirchneriella subcapitata e Chlorella vulgaris, na mortalidade do microcrustáceo Thamnocephalus platyurus, nos embriões de peixe-zebra Danio rerio e nos D. rerio adultos. A espécie mais sensível foi T. Platyurus com um LC50 de 0.2 mg/L, seguido por P. subcapitata (EC50 =1.6 mg/L), C. vulgaris (EC50= 5.1 mg/L), zebrafish adultos (LC50= 5.5 mg/L) e finalmente embriões de zebrafish (LC50= 14.9 mg/L). Os resultados obtidos neste estudo estão de acordo com o que está descrito na literatura científica actual. T. platyurus se destacou como o organismo modelo mais sensível à exposição. Na segunda parte do trabalho os efeitos crónicos e subletais do HS foram avaliados em D. rerio. Os biomarcadores lactato desidrogenase (LDH), glutationa-S-tranferase (GST), colinesterase (ChE) e catalase (CAT) foram analisados após exposição de curto prazo de embriões e adultos para avaliar efeitos ao nível bioquímico em teste agudo com embriões de D. rerio e em teste agudos e crónicos com adultos. Parâmetros de desenvolvimento embrionário também formam incluídos no ensaio com embriões. Um ensaio de longo prazo (14 dias) também foi feito com peixes adultos onde os mesmos biomarcadores foram avaliados e comprimento e peso total foram medidos. Os biomarcadores foram úteis em detectar os efeitos do HS em ambos os testes (de curto e longo prazo), apesar do padrão de resposta não ter sido sempre o mesmo. No teste de curto prazo, o biomarcador mais sensível parece ter sido GST (em adultos) e ChE (em embriões) enquanto no teste de logo prazo uma resposta inicial da ChE, GST e LDH foi observada. Na exposição de longo prazo uma diminuição no factor de condição do D. rerio adulto também foi observada. Exposição a longo prazo parece ter contribuído com resultados mais consistentes no efeito do SH nos peixes-zebra. Trabalhos complementares são necessários para elucidar os diferentes padrões de resposta entre os testes de curto e longo prazo; no entanto, como foram obtidas respostas em níveis de HS encontrados no ambiente, este trabalho indica que HS (bem como outros químicos usados nos processos de branqueamento que contêm HS na sua composição), ao entrarem em contacto com corpos de águas sem tratamento prévio, podem ter graves efeitos deletérios nos ecossistemas aquáticos.
Disinfectants are substances used in specific surfaces or areas with the objective of killing microorganisms. Sodium hypochlorite (SH) is a chemical used in large scale, frequently as disinfect or bleaching agent. This chemical is preset in hospitals, several industries (chemical, pharmaceutical, paper, wastewater treatment, among others) as well as a household bleach. Chlorine based disinfectants when in residual water react with organic matter forming organochlorine compounds. Those chemicals are persistent in the ecosystem and are toxic to aquatic organisms. In the present study, SH toxicity was evaluated in organisms belonging to different trophic levels and the long term effects were studied in the model organism Danio rerio. In the first part of this work the short term effect of SH in different aquatic organisms was analyzed to evaluate their different sensibilities. SH effects were estimated in the growth of the algae Pseudokirchneriella subcapitata and Chlorella vulgaris, in the mortality of the microcrustacean Thamnocephalus platyurus and of the D. rerio (zebrafish) embryos and adults. The most sensitive species was T. platyurus with a LC50 of 0.2 mg/L, followed by P. subcapitata (EC50 =1.6 mg/L), C. vulgaris (EC50= 5.1 mg/L), adult zebrafish (LC50= 5.5 mg/L) and finally zebrafish embryo (LC50= 14.9 mg/L). The results obtained in this study agreed with what is described in the current scientific literature. T. platyrus stood out as the most sensitive to exposure model organism. In the second part of the work, SH sub lethal and chronic effects were evaluated in D. rerio. Biomarkers (lactate dehydrogenase (LDH), glutathione-S-tranferase (GST), cholinesterase (ChE) and catalase (CAT) were analysed after short term exposures of embryos and adults to evaluate effects at biochemical level. Embryo development parameters were also included in the embryo assay. A long term (14 days) assay was also performed with adult fish where the same biomarkers were evaluated, and total length and weight measured. Biomarkers were useful in detecting SH effects in both tests (short term and long term) although the pattern of responses was not always the same. In the short term test, the most sensitive biomarkers seemed to be GST (in adults) and ChE (in embryos) while in long term test an early response of ChE, GST and LDH was observed. In the long term exposure, a decrease in the condition factor of adult D. rerio was also observed. Long term exposure seems to have contributed with more consistent results on SH effects to adult zebrafish. Further work is needed to elucidate different patterns of responses between short and long term tests; however, as responses were obtained at SH levels found in the environment, this work indicates that SH (as well as other chemicals used in the disinfection and bleaching process that contains SH in its composition), by reaching water bodies without previous treatment, can have serious deleterious effects in the aquatic ecosystems.
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Relli-Dempsey, Vincent M. T. Relli-Dempsey. « A Thermometric Titration Study of Acetaminophen and Sodium Hypochlorite ». Ohio Dominican University Honors Theses / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=oduhonors152621864170557.
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Halliburton, Brendan William. « Investigation of spontaneous combustion phenomenology of bagasse and calcium hypochlorite ». Phd thesis, Australia : Macquarie University, 2002. http://hdl.handle.net/1959.14/36863.
Texte intégralRésumé :
Thesis (PhD)--Macquarie University, Division of Environmental and Life Sciences, Department of Chemistry, 2002.Bibliography: leaves 234-240.
Introduction, theoretical descriptions of spontaneous combustion phenomena and aims of this thesis -- Laboratory measurements of the self-heating phenomenology of bagasse -- Field experiments investigating the self-heating behaviour of large scale stockpiles of low symmetry -- Self-heating and thermal ignition of calcium hypochlorite -- Experimental methods and procedures used for the critical ambient temperature of HCH -- Results of critical ambient temperature measurements upon single containers of hydrated high strength HCH -- Experiments on the interaction of self-heating drums -- Conclusions.
The hazard of spontaneous combustion is a problem that confronts any industry that transports or stores a reactive material. Bagasse is a reactive material that presents an expensive spontaneous combustion hazard for the sugar industry since this material is the principal fuel used at sugar mills. Calcium Hypochlorite is another such material presenting a significant industrial spontaneous combustion hazard for the transport and insurance industry as it has been linked to a number of expensive maritime conflagrations. The investigation of fundamental self-heating phenomenon is critical for the understanding, control and prevention of spontaneous ignition with these materials. -- By way of isothermal calorimetry techniques and fundamental thermal ignition measurements, this study has provided improved understanding into the oxidative self-heating phenomenology of bagasse and thermal ignition phenomenology of calcium hypochlorite. Both substances have been shown to possess unusual and previously unknown self-heating behaviour at temperatures below 100°C, with water being a principal component of each mechanism. -- The outcomes of this study have provided a platform which has enabled current mathematical models to predict large scale self-heating phenomena for industrially stored quantities of these materials.
Mode of access: World Wide Web.
240 leaves, bound ill
17
Fuerst, Georgia Brook. « INVESTIGATING PERACETIC ACID AS AN ALTERNATIVE TO SODIUM HYPOCHLORITE DISINFECTION ». Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470144930.
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Taylor, Nicholas Allen. « In-vitro evaluation of dye leakage of an MTA apical barrier after irrigation with 3% soldium hypochlorite, 2% chlorhexidine, MTAD, or 17% EDTA/3% sodium hypochlorite ». Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5240.
Texte intégralRésumé :
Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains vii, 40 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 30-34).
19
Betancourt, Henríquez Pablo Andrés. « Irrigation with Laser-Activated sodium hypochlorite : An antimicrobial alternative in endodontics ». Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/670016.
Texte intégralRésumé :
Bacteria and their sub-products are the main cause of the occurrence and perpetuation of endodontic infection. However, only a few bacterial species are seen as responsible of persistent endodontic infections, among them Enterococcus faecalis is the most frequently isolated species. It has several virulence factors, such as aggregation substances, enterococcal surface protein (Esp), “endocarditis and biofilm-associated pili” (ebp) and cytolysin. Moreover, its high resistance to antibacterial agents is emhanced by its ability to form biofilm.
Due to the complex and unpredictable root canal morphology, the complete removal of smear layer and bacterial biofilm is difficult. Recently, laser-activated irrigation (LAI) has been introduced as an alternative to achieve a deeper cleaning and disinfection of the root canal system. Its mechanism of action is based on the generation of cavitation bubbles, through the absorption of laser energy by the irrigant. The most used lasers are from the Erbium family, Er, Cr: YSGG (2780nm) and Er: YAG (2980nm).
Sodium hypochlorite (NaOCl) is considered the "gold standard" of endodontic irrigators. It has a broad antibacterial spectrum and is capable of dissolving organic tissue. It is used in a range between 0.5% and 6%, varying its degree of effectiveness. Nevertheless, at high concentrations it is toxic, causing damage to endothelial cells and the periodontal ligament cells, which generates an acute inflammatory reaction and pain.
Hence, the aim of this thesis was to explore the bactericidal effect of low concentration of NaOCl activated by Er, Cr: YSGG laser-activated irrigation against E. faecalis biofilms in root canals in order to decipher if it may be similar to the one achieved by high concentrations of NaoCl.
IN IN VITRO ROOT CANAL MODEL:
The main objective of the first stage of this thesis was to build a laboratory model to simulate the conditions inside a single-tooth root canal. The Pasteur pipettes were inoculated with E. faecalis ATCC 29212 for 24 hours bacterial colonization and the subsequent formation of biofilm in the proposed in vitro model was demonstrated by atomic force microscope.
The second essential point of this part was to determine antimicrobial capacity of Er,Cr:YSGG laser against E.faecalis. In addition, passive ultrasonic irrigation was also tested. Laser-activated irrigation demonstrated higher antimicrobial activity than passive ultrasonic irrigation.
The final stage of this first part consisted in the analysis and measurement of the nano-roughness by atomic force microscopy of the cells treated and its comparison with that of untreated cells.
EXTRACTED TEETH:
This part was focused on the endodontic preparation of extracted human teeth. The root canals were instrumented by a crown-down / step-back technique using conventional sequence of 0.02 taper files up to the master # 55. The teeth were inoculated with E. faecalis ATCC 29212 for 10 days.
The following stage was focused on the study of the antibacterial action of low concentration of NaOCl activated by Er,Cr: YSGG laser in extracted human teeth. The antimicrobial effectiveness of laser-activated irrigation was compared with passive ultrasonic irrigation activation and conventional manual irrigation. Er,Cr:YSGG laser and 0.5% NaOCl showed a considerable synergistic action.
Finally, the last part was focused on the microscopic visualization of the samples, to complement the results of the microbiological count. The scanning electron microscope was used to determine the degree of effectiveness of bacterial biofilm and smear layer removal both on the dentin surface and inside the dentinal tubules. Additionally, the confocal scanning electron microscope was used to visualize the proportion of alive and dead bacteria after treatment.
The results obtained in this thesis show that laser-activated irrigation is a therapeutic alternative for infections caused by E. faecalis inside of root canals.Las bacterias y sus subproductos son la principal causa de la infección endodóntica y su perpetuación. E. faecalis es la especie más frecuentemente aislada de los fracasos endodónticos. Su alta resistencia a los agentes antibacterianos viene incrementada por la capacidad para formar biofilms. Recientemente, el riego activado por láser (LAI) se ha propuesto como una alternativa para lograr una limpieza y desinfección más profunda del sistema de canales radiculares. Su mecanismo de acción se basa en la generación de burbujas de cavitación, a través de la absorción de energía láser por parte del irrigante. El objetivo de esta tesis fue explorar si el efecto bactericida de una baja concentración de NaOCl activado por el láser Er, Cr: YSGG, puede ser similar al alzanzado por altas concentraciones de NaOCl contra biofilms de E. faecalis en canales radiculares. MODELO DE CANAL RADICULAR IN VITRO: El objetivo principal de la primera etapa de esta tesis fue construir un modelo de laboratorio para simular las condiciones al interior de un canal radicular. Las pipetas Pasteur fueron inoculadas con E. faecalis ATCC 29212 durante 24 horas. Luego se determinó la capacidad antimicrobiana del láser Er, Cr: YSGG contra E.faecalis. La irrigación activada por láser demostró una mayor actividad antimicrobiana que la irrigación ultrasónica pasiva. Finalmente se realizó el análisis y la medición de la nano rugosidad mediante microscopía de fuerza atómica de las células tratadas y no tratadas. DIENTES EXTRAÍDOS: Los dientes fueron inoculados con E. faecalis ATCC 29212 durante 10 días. El láser Er, Cr: YSGG y 0,5% de NaOCl mostraron una acción sinérgica considerable. Finalmente, el microscopio electrónico de barrido se utilizó para determinar el grado de efectividad en la remoción de biofilms bacterianos y de barro dentinario. Además, se utilizó el microscopio electrónico de barrido confocal para visualizar la proporción de bacterias vivas y muertas después del tratamiento. Los resultados obtenidos en esta tesis muestran que la irrigación activada por láser es una alternativa terapéutica para las infecciones causadas por E. faecalis dentro de los canales radiculares.
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Duckhouse, H. L. « The effect of sonication at different frequencies on microbial disinfection using hypochlorite ». Thesis, Coventry University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436296.
Texte intégral
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Vu, Van Loi [Verfasser]. « Redox-sensing mechanisms under hypochlorite stress in Staphylococcus aureus / Van Loi Vu ». Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1159900639/34.
Texte intégral
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Nuanualsuwan, Suphachai. « Inactivation of human picornaviruses and feline calicivirus by ultraviolet, hypochlorite, and heat / ». For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
Texte intégral
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Mahovic, Michael. « Sodium hypochlorite and alternative sanitizers for sanitation of simulated packinghouse water systems ». [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008400.
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Morganti, Luca 1975. « Sodium hypochlorite generation for household water disinfection : a cast study in Nepal ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84803.
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Alajmi, Shikhah. « IN VITRO EFFECT OF SODIUM HYPOCHLORITE ON STREPTOCOCCUS MUTANS MONO-SPECIES BIOFILM ». Master's thesis, Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/481095.
Texte intégralRésumé :
Oral BiologyM.S.
Objectives: Bacterial biofilms are ubiquitous, found in a variety of sites within the human body, and are associated with the pathogenesis of dental caries. They are formed when free-floating microorganisms attach to a surface. One such organism, Streptococcus mutans, has adhesins allowing its attachment to tooth surfaces. S. mutans is associated with all forms of human dental caries. S. mutans can rapidly metabolize dietary sugars to acid, locally creating a low pH on tooth surfaces, where it can optimally grow and become more competitive in dental plaque biofilms, in contrast to acid-sensitive bacterial species associated with sound non-carious tooth surfaces. Commensal and natural biofilm aggregates contain multiple microbial species that are believed to co-exist, interact, and form families with high bacteria and niche diversity. In contrast, most biofilms that are chronically infectious tend to have low bacterial diversity with sovereign mono-species such as S. mutans. Hence, it is advantageous to study mono-species biofilms of dental caries-associated bacteria. Although dental biofilms cannot be completely eliminated, their pathogenicity can be lessened through effective oral hygiene measures. Continuous and regular disruption of dental biofilms is imperative for prevention and management of oral infectious diseases. Mechanical methods, most notably tooth brushing and flossing, are required to regularly and effectively disrupt dental plaque biofilms in the human oral cavity. Antiseptics, such as mouth rinses, can also help control dental plaque biofilms, and may gain access to oral sites inaccessible by mechanical methods. Among available antiseptics, sodium hypochlorite is a particularly potent agent against bacteria, fungi, and viruses. Sodium hypochlorite occurs naturally within phagocytic cells (neutrophils, monocytes, and macrophages) participating in the human innate immune response to microbial infection. Several randomized controlled clinical trials support the efficacy of rinsing twice weekly with 0.25 % sodium hypochlorite to improve periodontal health. To date, no studies have been reported concerning the effect of sodium hypochlorite rinsing on dental caries incidence or progression. Several in vitro studies have addressed the effect of dilute sodium hypochlorite on various oral bacteria species. However, there are no literature reports addressing the effect of sodium hypochlorite on bacteria attached to solid surfaces in biofilms. Hence, the objective of this study is to compare the in vitro antimicrobial effect of sodium hypochlorite to another antiseptic agent, chlorhexidine, on the acidigenic and aciduric bacterial species, S. mutans and Lactobacillus casei, both in a free-form (planktonic) state, and as a biofilm attached to two hard surfaces (glass and hydroxyapatite). Methods: The effect of sodium hypochlorite on S. mutans and L. casei was determined by finding the minimum inhibitory concentration (MIC) by broth dilution assays. The MIC was considered to be the lowest concentration of the agent that prevented bacterial growth, resulting in a clear test tube in a broth dilution assay. Experiments with sodium hypochlorite were repeated twice against each bacterial species, and compared to chlorhexidine in similar assays. The effect of a 20-second exposure of MIC concentration (1.0%) of sodium hypochlorite on the growth of S. mutans planktonic cells was measured. Finally, the effect of a 20-second exposure of 1% hypochlorite on S. mutans single-species biofilms was assayed using sterile microplates and the MBEC Biofilm Inoculator (Innovatech). Results: Values for inhibition of growth of planktonic cells were as follows: sodium hypochlorite (MIC = 0.1%; MBC = 0.1%); chlorhexidine (MIC = 0.0015%; MBC = 0.0025%). A 20-second exposure to either solution at the MBC inhibited growth of planktonic cells in refreshed media. Cells adherent to glass or hydroxyapatite pegs were growth-inhibited, but not detached, in refreshed media by a 20-second exposure to 0.2% and 0.4% sodium hypochlorite, and 0.01% and 0.12 % chlorhexidine, but not by more dilute solutions. Conclusions: Chlorhexidine is more potent than sodium hypochlorite, but dilute solutions of both antimicrobial agents inhibited growth of S. mutans mono-species biofilm cells without detachment of cells.
Temple University--Theses
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Blattes, Gabriela Bess Ferraz. « Migração celular, viabilidade e reação tecidual de soluções irrigadoras à base de hipoclorito de cálcio : estudo in vitro e in vivo ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/128202.
Texte intégralRésumé :
Introdução: O objetivo do presente estudo foi analisar a citotoxicidade e biocompatibilidade de soluções de hipoclorito de cálcio (Ca(OCl)2) comparadas a soluções de hipoclorito de sódio (NaOCl) in vitro em cultura de fibroblastos 3T3 e in vivo em ratos. Metodologia: Culturas de fibroblastos 3T3 foram expostas a diferentes concentrações de hipoclorito de cálcio e sódio e foi realizado um ensaio de “scratch”. Além disso, a taxa de viabilidade foi analisada utilizando o teste Azul de Trypan. As soluções a 1 e 2,5% foram, também, injetadas no tecido conjuntivo de 18 ratos Wistar de 18 semanas de idade. A reação inflamatória tecidual foi avaliada em 2h, 24h e 14 dias após as injeções e as amostras foram qualitativamente analisadas em microscópio óptico. Análise estatística foi realizada utilizando teste ANOVA e post hoc de Tukey para testes in vitro e Kruskal‐Wallis e post hoc de Dunn para o teste in vivo (α=.05). Resultados: No ensaio de “scratch”, Ca(OCl)2 não apresentou diferença estatística em relação ao controle no período de 24h (p<0.05). NaOCl e Ca(OCl)2 a 0.0075% e 0.005% apresentaram resultados de viabilidade similar ao grupo controle positivo (p > 0.05) no ensaio Azul de Trypan. No teste in vivo, Ca(OCl)2 1% mostrou uma diminuição significativa de neutrófilos entre 2h e 24h (p=0.041) e entre 2h e 14d (p=0.017). Não houve diferença estatística entre os grupos para linfócitos/plasmócitos e macrófagos. Conclusão: Ca(OCl)2 mostrou resultados favoráveis de viabilidade e induziu um baixo nível de resposta inflamatória tecidual, apresentando, assim, citotoxicidade e biocompatibilidade aceitáveis para uma solução irrigadora.Introduction: The aim of the present study was to analyze cytotoxicity in vitro on cultured 3T3 fibroblasts and inflammatory tissue reaction in vivo on rats to calcium hypochlorite (Ca(OCl)2) solutions compared with sodium hypochlorite (NaOCl) solutions. Methods: Cultured 3T3 fibroblasts were exposed to different concentrations of calcium and sodium hypochlorite and a scratch assay was performed. The viability rate was analyzed with Trypan Blue assay. A. The 1 and 2.5% solutions were still injected into the subcutaneous tissues of eighteen male Wistar rats aged 18 weeks. Inflammatory tissue reaction was evaluated at 2h, 24h and 14 days after the injections and the samples were qualitatively analyzed through a light microscope. Statistical analysis was assessed by ANOVA and Tukey post hoc test for in vitro assays and by Kruskal-‐Wallis and Dunn post hoc test for in vivo assay (α=.05). Results: In scratch assay, Ca(OCl)2 showed no statistically significant difference to control group at 24h (p<0.05). 0.0075% and 0.005% NaOCl and Ca(OCl)2 presented results similar to positive control group (p > 0.05) on Trypan Blue assay. In in vivo assay, 1% calcium hypochlorite group showed a significant decrease of neutrophils at 2h and 24h (p=0.041) and 2h and 14d (p=0.017). There was no statistically significant difference for lymphocytes/plasmocytes and macrophages among groups. Conclusions: Ca(OCl)2 showed favorable results of viability and induced an low level of inflammatory response, thus presenting an acceptable cytotoxicity and biocompatibility for an irrigant solution.
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Criser, Gavin L. « The effect of cannula design upon apically extruded sodium hypochlorite during endodontic therapy ». Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11205.
Texte intégralRésumé :
Thesis (M.S.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains iii, 29 p. : col. ill. Includes abstract. Includes bibliographical references (p. 24-29).
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Nio, Stefanie. « The effectiveness of heated sodium hypochlorite on Enterococcus faecalis in infected dentinal tubules ». Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62174.
Texte intégralRésumé :
Introduction: The goal of chemical irrigation in endodontics is to maximize the reduction of microbes and necrotic tissue remnants in the root canal system. Enterococcus faecalis is most frequently associated with persistent endodontic infections. Sodium hypochlorite (NaOCl) is the most commonly used root canal irrigant. Heating NaOCl has a positive effect on the tissue dissolving abilities of the solution.
Objective: The aim of this study was to compare the killing effectiveness of two different sodium hypochlorite concentrations (2 % vs. 5.25 %) at two different temperatures (20 °C vs. 60 °C) against two strains of E. faecalis biofilm at different ages of maturation (3 days vs. 3 weeks), in a previously described dentin block model.
Hypotheses:
Temperature, concentration, the exposure time, the age of the biofilm nor the strain of E. faecalis have no effect on the killing efficacy of NaOCl on E. faecalis.
Methods: Dentin blocks were prepared from human root dentin. Two E. faecalis strains were introduced into dentinal tubules by centrifugation and incubated to form biofilms. After 3 days and 3 weeks of growth, the E. faecalis dentin biofilm samples were exposed to sterile water, 2 %, and 5.25 % NaOCl for 3 and 10 minutes at room temperature (20 °C) and at 60 °C. After the exposure, the proportions of killed bacteria in dentin canals were assessed by viability staining and confocal laser scanning microscopy.
Results: The killing efficacy of E. faecalis in dentin tubules was affected by an increase in temperature of the NaOCl solution. The concentration of the NaOCl solution and exposure time to the irrigant played a role in the killing efficacy of NaOCl. Overall, 5.25 % NaOCl demonstrated a greater effect on the killing efficacy on E. faecalis, except when NaOCl is used at 60 °C with an exposure time of 10 minutes. There was no significant difference (p>0.5) between the two different strains of E. faecalis or between the 3-day and 3-week old biofilms in their sensitivity to the bactericidal effect of NaOCl.
Conclusion: Bacterial killing by NaOCl is enhanced by an increase in temperature and concentration.Dentistry, Faculty of
Graduate
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Pellegrin, Bastien. « Analyse multi-échelle de la dégradation de membranes d'ultrafiltration en polyethersulfone - poly(N-vinyl pyrrolidone) en conditions d'usage ». Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2084/.
Texte intégralRésumé :
Ces travaux portent sur l'étude du vieillissement de membranes d'ultrafiltration en PES / PVP. Ils sont motivés par le constat industriel de l'endommagement des membranes au cours de leur utilisation. Il est démontré que l'hypochlorite de sodium utilisé lors des procédures de lavages sur site de production d'eau potable est le principal responsable du vieillissement des membranes. Cette dégradation chimique conduit à une oxydation radicalaire de la PVP (avec et sans rupture de chaînes), entraînant son élimination partielle de la structure de la membrane. Ce phénomène provoque une augmentation de la perméabilité à l'eau pure, une diminution de la sélectivité et une altération des propriétés mécaniques de la membrane. Une relation directe entre l'évolution de l'allongement à la rupture (déterminé par essais de traction) et la quantité de PVP contenue dans les 40 premiers microns en dessous de la surface de la membrane est notamment établie. Nous mettons également en évidence la relative stabilité de la PES. L'exposition de la PES à l'hypochlorite provoque la formation de phénols ortho-substitués (sans rupture de chaînes), uniquement en présence de PVP. En plus de l'altération de la sélectivité et des propriétés mécaniques, d'un point de vue applicatif, ces modifications chimiques donnent lieu à une augmentation de la sensibilité au colmatage. Les résultats de cette étude de vieillissement accéléré en laboratoire sont supportés par l'analyse de membranes issues de modules ayant opéré durant plusieurs années sur site de production d'eau potable. En effet, les marqueurs macroscopiques et moléculaires de la dégradation présentent, dans les deux cas, les mêmes évolutions. Cependant, l'accent est mis sur l'invalidité du concept de dose, très largement utilisé pour quantifier l'avancement de la dégradation. En effet, nous démontrons que, dans la gamme de concentrations et de temps que nous avons étudié, il existe un effet prépondérant de la concentration par rapport au tempsMotivated by drinking water production plants reporting membrane failure issues, this study investigates the ageing of a commercially available PES / PVP UF hollow fiber. Proof is given that membrane degradation is mainly induced by sodium hypochlorite exposure. The effects on the PES chemical structure are limited, very low extend of chain scission occurs and the formation of an ortho-substituted phenol is observed as the main modification. Experiments show that the presence of PVP and/or PVP degradation products is a required condition for the PES oxidation to occur. On the other hand, PVP appears to be very sensitive to hypochlorite exposure. PVP radical oxidation mechanisms are identified presenting a maximal reaction rate for neutral to slightly basic pH and leading to the partial removal of the PVP degradation products from the membrane structure. Correlation of macroscopic and molecular characterizations demonstrates that PVP degradation is responsible for the membrane integrity loss (impairing selectivity and mechanical performance), while hypochlorite exposure also induces enhanced membrane / solutes interactions, leading to an accentuated fouling. The representativeness of static continuous hypochlorite exposure regarding the actual on-site membrane ageing is confirmed by the analysis of membranes extracted from an industrially operated module. Nevertheless, the hypochlorite dose parameter, widely used in the literature, is demonstrated to be inappropriate to describe the degradation rate: the hypochlorite concentration impact is shown to be dominating the exposure time impact on the degradation rate
30
Davis, Shannon Lisa. « The effect of agitation on the penetration depth of sodium hypochlorite into dentinal tubules ». Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44678.
Texte intégralRésumé :
Objective: The aim of this study was to compare the difference in irrigant penetration into dentinal tubules of 6% NaOCl using the EndoActivator®, ProUltra® PiezoFlow™ and EndoVac® and to compare them with the standard side-vented ProRinse® needle.
Methods: Sixty extracted anterior teeth with single canals were accessed conventionally, the pulp tissue removed and canal patency verified using minimal instrumentation. Crystal Violet dye was placed in the canals for 5 days followed by instrumentation of the canals to standard shape with ProTaper rotary files to size F4 using 1ml of 6% NaOCl used between each file. The teeth were divided into four groups and each agitation system was used with 6% NaOCl as per manufacturers recommendations. Each tooth was mounted in acrylic and cut into 1 mm thick section perpendicular to the long axis of the tooth using the Isomet® Linear Precision Saw (Censico International Pvt. Ltd.) The sections were analyzed with a Nikon® Eclipse® Microscope at 40x magnification and NaOCl penetration was measured with the NIS Elements™ Software (Nikon Corporation).
Results: The maximum penetration depth for the ProRinse® side-vented needle, EndoActivator and EndoVac irrigation methods occurred in the coronal third of the canal. However, the maximum penetration depth for the ProUltra® PiezoFlow™ Ultrasonic System occurred in the middle third. With regard to NaOCl Penetration area, the coronal and middle thirds showed better area penetration than the apical third in all irrigation groups.
Conclusions: The irrigation methods may affect the highest penetration depth of NaOCl into dentinal tubules at different areas of the root canal position.
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Krause, Trisha Ann. « The Antimicrobial Effect of MTAD, Sodium Hypochlorite, Doxycycline, and Citric Acid on E. faecalis ». VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd_retro/151.
Texte intégralRésumé :
The purpose of this study was to compare the antimicrobial effect of MTAD, two of its components, doxycycline and citric acid, and NaOCl on E. faecalis in two in vitro models: the bovine tooth model and the agar diffusion model. In the tooth model, the lumens of thirty bovine dentin discs were standardized, autoclaved and infected with E. faecalis for 14 days. The infected dentin discs were treated with either MTAD, doxycycline 100mg/ml, 10% citric acid, 5.25% NaOCl or saline for 10 minutes. Dentinal shavings were collected using sterile 037 and 040 round burs. The number of bacteria in the shavings was enumerated by overnight CO2 culturing on TSA agar plates. For the agar diffusion model, E. faecalis was plated before placing paper discs wetted with three dilutions of each irrigant. The zone of inhibition was recorded after overnight culture. The data were analyzed with a two-way ANOVA and Tukey-Kramer post-hoc test. In the bovine tooth model, NaOCl and doxycycline were more effective than control in killing E. faecalis at the shallow bur depth but at the deeper bur depth, only NaOCl was significantly more effective (psE. faecalis.
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Coudron, Jonathan. « The Antimicrobial Effect of STERIPLEX HC in comparison with Sodium Hypochlorite on Enterococcus faecalis ». VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2654.
Texte intégralRésumé :
The study objective was to compare the antimicrobial activity of STERIPLEX™ HC with 5.25% sodium hypochlorite (NaOCl) at different dilutions (50%, 25%, 10%, 1%, 0.1%) and different time intervals (1, 3, 5 minutes) on Enterococcus faecalis. All data was analyzed using an ANOVA. The 50%, 25%, and 10% dilutions of both disinfectants reduced the colony forming unit (CFU) count to below the limit of detection (50 CFU/ml) after one minute. The 1% dilutions at each of the time intervals show NaOCl was significantly more effective than STERIPLEX™ HC (all Ps < .0001) in reducing the CFU/ml count. The 0.1% dilutions of NaOCl and STERIPLEX™ HC at 1 minute, were not different (P = 0.7808), while at 3 minutes and 5 minutes NaOCl was significantly more effective (P = 0.0098 and P < .0001, respectively).
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Harris, Jesse. « Comparison of STERIPLEX™ HC and Sodium Hypochlorite Cytotoxicity on Primary Human Gingival Fibroblasts ». VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2662.
Texte intégralRésumé :
This study examined the cytotoxic effects of STERIPLEX™ HC (sBioMed, Orem, UT) and sodium hypochlorite (NaOCl) on human fibroblast cells in vitro. Fibroblasts exposed to various concentrations of NaOCl or STERIPLEX™ HC were visualized via light microscopy. Dilutions of either NaOCl or STERIPLEX™ HC that did not appear to disrupt the integrity of the cells were recorded for further analysis. Cells were then cultured and grown to confluence in five separate plates. A void was created down the middle of each plate. If the cells were viable, cellular confluence was seen. If nonviable, confluence of the cells did not occur. Both disinfectants showed absolute kill at all concentrations above 1%. The cells treated with 0.1% NaOCl were found to be nonviable. However, at 0.1% STERIPLEX™ HC, the cells were viable and able to replicate, filling the void and returning to confluence.
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Webb, Bettine Constance. « Laboratory and clinical studies on the treatment of candida-associated denture stomatitis with sodium hypochlorite or microwave irradiation ». University of Sydney, 1996. http://hdl.handle.net/2123/4466.
Texte intégralRésumé :
Doctor of PhilosophyThis thesis describes experiments which were carried out at the Institute of Dental Research in Sydney and within the Department of Prosthetic Dentistry at the United Dental Hospital of Sydney between February 1991 and May 1996. The study is concerned with finding practical means of treating chronic atrophic candidosis, also referred to as Candida-associated denture stomatitis and to this purpose two methods of denture disinfection are investigated, namely, sodium hypoclorite denture soak and microwave irradiation. Although the aetiology of denture stomatitis is generally considered to be multifactorial, there is sufficient evidence that Candida species and in particular C. albicans play an important role in the aetiology of the condition. In Chapter 1, therefore, the literature review, which provides relevant background information for the experiments to be described in later chapters, is primarily concerned with Candida species. The characteristics and distribution of Candida species are described and factors affecting the distribution of or Candida are discussed. The literature relating to the cause of chronic atrophic candidosis is vast and consequently a detailed description is given of Candida-associated denture stomatitis in the section concerned with oral diseases caused by Candida and their treatment. Each of the subsequent chapters, contains a brief literature review of material relevant to the subject of the particular chapter. Chapter 2 describes laboratory work to assess the effect of sodium hypochlorite on the adhesion of Candida species to oral surfaces and the ability of Candida to coaggregate with oral streptococci. The results showed that sodium hypochlorite decreased the ability of Candida species to adhere to both inert surfaces and BECs. However, coaggregation of Candida with streptococci was increased. Thus, hypochlorite if used as a denture soak may initially reduce the ability of Candida species to adhere to the denture surface and may therefore assist the treatment of denture stomatitis. The effects of hypochlorite on the characteristics of Candida species that are associated with tissue invasion are described in Chapter 3. The production of acid proteinase, the formation of germ tubes and presence of major cell wall proteins at 43 and 27 kDa are demonstrated. The ability of the whole cells of certain species of Candida to aggregate human platelets was assessed. The results showed that sodium hypochlorite did not affect proteinase production by Candida species but the rate of germ tube formation and the production of Candida cell wall proteins were increased. Hypochlorite did not affect the ability of certain Candida species to aggregate human platelets. Mechanisms to defend the host against candidal invasion are discussed and include platelet aggregation where aggregated platelets release antimicrobial factors that are active against Candida. Chapter 4 describes an in vitro study to test the effects of sodium hypochlorite and microwave irradiation on the survival of Candida species and oral streptococci on denture surfaces. The results showed that 0.02% sodium hypochlorite denture soak for 8 h will eliminate Candida species and reduce the growth of streptococci. However, microwaving of dentures at medium setting for 6 min will eliminate both Candida and streptococci. This information servers as baseline data for clinical assessments described in Chapters 7 and 8. Denture hygiene is an important factor in the prevention and treatment of Candida-associated denture stomatitis. Hence, a clinical study to assess the microbiology of denture plaque is described in Chapter 5. The results showed that denture plaque was composed mainly of Gram-positive streptococci with varying proportions of Gram-positive rods, Gram-negative cocci and rods and is similar to dental plaque. Candida was not always isolated and when detected constituted a very small proportion (< 1%) of the total aerobic bacterial count. The results of an investigation to test the effect of soft denture liners in lower dentures on the colonization of denture surfaces by Candida species and aerobic bacteria are given in Chapter 6. There was no significant difference in Candida /bacterial colonization of dentures with soft denture liners and those without liners. Chapter 7 describes a clinical study to test the efficiency of sodium hypochlorite (0.02%) over-night denture soak as an effective denture disinfecting agent. Treatment of dentures with hypochlorite over a trial period resulted in reductions of Candida and aerobic bacteria and although the reductions were not significant the effect over the trial period could be assessed. A significant finding was that for the palate, treatment with hypochlorite over the trial period prevented an increase in candidal load. Thus, sodium hypochlorite may function as an effective disinfecting agent when used as 0.02% denture soak for a prolonged period. A pilot study to assess the effectiveness of microwaving dentures for ten min (350 W, 240 MHz) as a potential method of denture disinfection is described in Chapter 8. For practical reasons the dentures were microwaved only once only and therefore the effect over a trial period could not be assessed. However, one treatment resulted in significant reductions in the levels of Candida and aerobic bacteria. These findings have indicated that future research should be carried out to test the effect of daily consecutive microwave treatments on candidal and bacterial growth. The general discussion in Chapter 9 summarizes the data presented in the previous chapters and from the findings conclusions are made concerning the prevention and treatment of Candida-associated denture stomatitis. The limitations of this thesis are recognized and some important aspects of the study are recommended for future research.
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Hawkins, Clare. « Detection and identification of radicals generated during the degradation of cartilage ». Thesis, University of York, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319457.
Texte intégral
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Smith, Michael Shane. « SODIUM HYPOCHLORITE'S EFFECT ON NICKEL-TITANIUM ROTARY INSTRUMENTS AND ITS EFFECT ON RESISTANCE TO FRACTURE ». VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/941.
Texte intégralRésumé :
The purpose of this study was to examine the effect of partial and total immersion in sodium hypochlorite on nickel-titanium rotary files and to determine whether resistance to fracture was influenced by the immersion time. One hundred K3 and 100 ProFile® rotary files were either partially or totally immersed in 5.25% sodium hypochlorite for zero, one, five, thirty, or sixty minutes. After immersion, files were subjected to cyclic fatigue testing. Time to fracture was recorded and analyzed by a two-way ANOVA. Tukey's honest significant difference was used to identify any differences in immersion times. Within all ProFile groups and partial immersion K3 groups, there was no significant decrease in time to fracture with increased immersion time in sodium hypochlorite. Only the K3 total immersion groups revealed a significant decrease in time to fracture with increased immersion time in sodium hypochlorite.
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Small, David Andrew. « Comparison of toxicogenomic effects of sodium hypochlorite, hydrogen peroxide, and peracetic acid on Pseudomonas aeruginosa ». College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6748.
Texte intégralRésumé :
Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Chemical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Thompson, Ina Sharon. « Optimisation of sodium hypochlorite dosing at Wylfa Power Station : an experimental study with Mytilus edulis ». Thesis, Bangor University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263175.
Texte intégral
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Chung, Young Ho. « An evaluation of factors impacting optimum repulping and minimum chloroform generation during sodium hypochlorite repulping ». Oxford, Ohio : Miami University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1059075420.
Texte intégralRésumé :
Thesis (M.S.)--Miami University, Dept. of Paper Science and Engineering, 2003.Title from first page of PDF document. Document formatted into pages; contains xii, 90 p. Includes bibliographical references (p. 88-90).
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Coetzee, Emile. « The use of topical sodium hypochlorite in the management of Pseudomonas aeruginosa burn wound infection ». Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10298.
Texte intégralRésumé :
The aim of the study is: 1. To undertake a meta-analysis of Pseudomonas aeruginosa burn wound infection. 2. To undertake a retrospective audit of Pseudomonas aeruginosa burn wound infection at the Red Cross War Memorial Children's Hospital. 3. To investigate the local effects of sodium hypochlorite solutions in Pseudomonas aeruginosa burn wound infection with regards to efficacy and toxicity.
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CHUNG, YOUNG HO Mr. « An evaluation of factors impacting optimum repulping and minimum chloroform generation during sodium hypochlorite repulping ». Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1059075420.
Texte intégral
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Leonardo, Natália Gomes e. Silva. « Efeito da condição de armazenamento sobre o ph e a concentração de cloro ativo de soluções de hipoclorito de cálcio ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131266.
Texte intégralRésumé :
O objetivo do presente estudo foi avaliar e comparar pH e concentração de cloro ativo de soluções de hipoclorito de sódio [NaOCl] e de hipoclorito de cálcio [Ca(OCl)2] armazenadas sob diferentes condições de temperatura e períodos de tempo. Soluções de NaOCl e Ca(OCl)2 foram preparadas nas concentrações 0,5%, 1%, 2,5% e 5,25%. O pH e a concentração de cloro ativo de soluções recém manipuladas e de soluções armazenadas por 30, 60 e 90 dias em temperatura ambiente (+/- 25°C), geladeira (4°C) e estufa (37°C) foram avaliados em pHmetro digital e através de titulação, respectivamente. Análise descritiva e analítica foram realizadas de acordo com a características dos dados. As soluções de NaOCl e Ca(OCl)2 demostraram pH extremamente alcalino logo após a manipulação. Soluções mais concentradas apresentaram maior pH e concentração de cloro ativo. Soluções de NaOCl 0,5% e 1% tendem a apresentar menor pH em comparação ao Ca(OCl)2 nas mesmas concentrações. NaOCl 5,25% mostrou maior pH em comparação ao Ca(OCl)2 de mesma concentração. NaOCl e Ca(OCl)2 0,5% e 1% tendem a reduzir pH, entretanto nas concentrações 2,5% e 5,25% houve aumento do pH. Soluções de Ca(OCl)2 apresentaram maior concentração de cloro ativo em comparação ao NaOCl, e soluções de NaOCl e Ca(OCl)2 2,5% e 5,25% apresentaram redução na concentração de cloro ativo em comparação as soluções de mesma concentração, recém manipuladas. O armazenamento a 37°C afeta negativamente a estabilidade das soluções. As soluções de Ca(OCl)2 2,5% e 5,25% apresentaram formação de precipitado que não se dissolveu em água, observada no fundo dos tubos de plástico, com o passar do tempo. Concluiu-se que soluções de Ca(OCl)2 são extremamente alcalinas e tendem a apresentar maior conteúdo de cloro em comparação ao NaOCl. Em relação ao cloro ativo, essas soluções tendem a ser estáveis até 30 dias de armazenamento sob refrigeração ou em temperatura ambiente.The aim of this study was to evaluate and compare pH and available chlorine content of sodium hypochlorite [NaOCl] and calcium hypochlorite [Ca(OCl)2] solutions on different storage conditions and time periods. NaOCl and Ca(OCl)2 solutions were prepared at 0.5%, 1%, 2.5% and 5.25% concentrations. pH and available chlorine content of freshly prepared solutions and solutions stored for 30, 60 and 90 days at room temperature (+/- 25°C), 4°C and 37°C were evaluated in digital pHmeter and by titration, respectively. Descriptive and analytical statistical analysis were performed. NaOCl and Ca(OCl)2 demonstrate highly pH after preparation. 2.5% and 5.25% solutions demonstrated the highest pH and available chlorine content. 0.5% and 1% NaOCl tend to have lower pH compared to 0.5% and 1% Ca(OCl)2. 5.25% NaOCl showed higher pH compared to 5.25% Ca(OCl)2. NaOCl and Ca(OCl)2 in 0.5% and 1% concentration tend to reduce pH, while 2.5% and 5.25% solutions showed an increase in pH. Ca(OCl)2 showed higher concentration of available chlorine than NaOCl. Both 2.5% and 5.25% NaOCl and Ca(OCl)2 solutions had a decrease in the available chlorine content when compared to freshly prepared solutions The storage at 37°C contributed to the instability of the solutions. 2.5% and 5.25% Ca(OCl)2 solutions showed a precipitate formation that was observed over time in the bottom of the plastic tubes. In conclusion, Ca(OCl)2 solutions are extremely alkaline and tend to have more available chlorine content than NaOCl. Regarding available chlorine content, these solutions tend to be stable to 30 days of storage, when kept at 4°C or at room temperature.
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Hanafi, Yamina. « Étude de la dégradation de membranes en polyéthersulfone / polyvinylpyrrolidone au contact de l’hypochlorite de sodium ». Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S170.
Texte intégralRésumé :
Lors de leur utilisation à l’échelle industrielle, les membranes polymères de filtration sont régulièrement soumises à des sollicitations chimiques lors des étapes de nettoyage et de désinfection. Bien que ces opérations restent inévitables pour restaurer les performances des membranes et prévenir la prolifération des micro-organismes, il s’avère néanmoins qu’elles conduisent à un vieillissement prématuré des membranes en conduisant à l’altération de leurs performances de filtration. L’objectif de cette thèse était d’étudier l’impact de l’hypochlorite de sodium, agent de nettoyage et de désinfection largement utilisé en industrie, sur les membranes en polyéthersulfone (PES) / polyvinylpyrrolidone (PVP). Des mesures électrocinétiques ont mis en évidence la dégradation du PES bien qu’il soit considéré comme un polymère très résistant chimiquement. Cette dégradation se produit par deux mécanismes distincts en fonction du pH de la solution d’hypochlorite de sodium : (i) la coupure de chaines du PES, principalement sous l’action de l’espèce HClO et (ii) l’hydroxylation du cycle aromatique du PES par les radicaux °OH formés au sein de la solution d’hypochlorite de sodium. La dégradation de la PVP par ouverture du cycle et son départ partiel de la membrane ont également été confirmés. Les expériences menées conjointement sur des membranes en PES pur et en PES/PVP avec différentes concentrations de PVP ont montré que la dégradation du PES par coupure de chaines se produit indépendamment de la concentration de la PVP dans la membrane. Par contre, la présence de la PVP favorise le mécanisme d’hydroxylation des cycles aromatiques du PES. Par ailleurs, le mécanisme de coupure de chaines du PES se révèle être le principal responsable de la détérioration des performances de filtration des membranes. Dans les conditions de vieillissement appliquées dans cette étude, ni l’hydroxylation du PES ni la dégradation de la PVP ne semblent jouer un rôle important dans la dégradation des propriétés de rétention des membranes. Enfin, la structure des membranes est fortement altérée sous l’action de l’hypochlorite de sodium, les modifications structurales étant plus importantes pour les membranes contenant de la PVPDuring industrial operations, filtration polymer membranes are regularly chemically-stressed during cleaning and disinfection steps. Although these latter are still unavoidable to restore the membrane performance and to prevent the proliferation of microorganisms, they lead, however, to membrane premature ageing, which impairs the membrane separation properties. The aim of this thesis was to investigate the impact of sodium hypochlorite, a widely used cleaning and disinfection agent, on polyethersulfone (PES) / polyvinylpyrrolidone (PVP) membranes. Electrokinetic measurements highlighted the degradation of PES, although the chemical resistance of this latter is well-acknowledged. The degradation of PES occurred through two distinct mechanisms depending on the pH of the sodium hypochlorite solution: (i) the PES-chain scission, which was found to result mainly from the HClO species, and (ii) the hydroxylation of the PES aromatic rings by the °OH free radicals that are formed in the sodium hypochlorite solution. Moreover, the degradation of PVP by a ring opening mechanism and its partial release from the membrane were confirmed. Experiments carried out with pure PES membranes as well as with PES / PVP membranes with different PVP contents showed that the PES-chain scission mechanism occurred whatever the PVP concentration. On the other hand, the presence of PVP was found to promote the hydroxylation of the PES aromatic rings. Furthermore, the PES-chain scission mechanism appeared to play the major role in the worsening of the membrane filtration performance. Under the ageing conditions of this study it seems that neither the PES hydroxylation nor the PVP degradation play a significant role in the worsening of the membrane rejection properties. Finally, the membrane structure was found to be substantially altered by the action of sodium hypochlorite, especially for membranes containing PVP
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Yadav, Kuldeep. « Diagnosis of the Failure of Ultrafiltration Membranes Used in the Dairy Industry ». Thesis, University of Canterbury. Chemical and Process Engineering, 2009. http://hdl.handle.net/10092/4439.
Texte intégralRésumé :
The long term degradation of polyethersulfone (PES) based ultrafiltration membranes used in the dairy industry has been investigated. The main aim of the study was to identify characterisation techniques which could give an indication
of the condition and performance of ultrafiltration membranes after long term exposure to sodium hypochlorite solution. Membranes were degraded using
sodium hypochlorite solution at pH 9, 10, 11 and 12, and with 5000 ppm-days to 25,000 ppm-days of exposure at 55°C. The degraded membranes were studied
using the following characterisation techniques: dynamic mechanical analysis
(DMA), thermogravimetric analysis (TGA), tensile testing, field emission
scanning electron microscopy with energy dispersive x-ray spectroscopy
(FESEM-EDS), Fourier transform infrared-attenuated total reflectance
spectroscopy (FTIR-ATR), contact angle, drop absorption, zeta potential, liquid-liquid displacement porosimetery (LLDP), protein separation, and colour measurement. The protein separation test included membrane throughput measurements (using casein-whey as feed), with size exclusion chromatography and gel electrophoresis to analyse the feed, permeate and retentate. Also a membrane disinfection experiment was performed to study the effect of sodium
hypochlorite pH on disinfection of mixed dairy culture.
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Tiong, Timm Joyce. « Sonochemical and ultrasonic output analyses on dental endosonic instruments ». Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558866.
Texte intégralRésumé :
Ultrasonic instruments are used with the aid of an irrigant such as NaOCl in endodontic treatments to remove dentin debris and calculus from infected root canals. This cleaning process may be assisted by various factors, such as acoustic streaming, and the production of radicals and microjets from the collapse of transient cavitation bubbles. The aim of this project is to understand the principal factors affecting the performance of a number of different endosonic files in order to correlate to their cleaning efficiencies. Characterisation includes detecting transient cavitation activity, mapping the areas of cavitation, assessing the file vibration movements and the streaming effects produced by the files. Experiments to assess the cleaning efficiencies of the files include: emulsification, dye removal with a dental irrigant, ink and hydroxyapatite paste removal from model systems designed to mimic the structure of a tooth. The results show that there is a correlation between the sonochemical output and the cleaning efficiencies, and this brings in further study on the possible factors that may affect the production of transient cavitation and the vibration profiles of the endosonic files. Lastly, a series of computational simulation of the acoustic pressure fields from different endosonic files were performed. Correlations of the simulated and experimental results showed the difference in ultrasonic output of the endosonic files is strongly related to their design. This work provides the basis and techniques necessary to perform a comprehensive study on the design of the endosonic files in order to enhance and optimise their cleaning efficiencies during clinical use and to inform future endodontic practice.
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Graça, Bárbara Pinto. « O hipoclorito de sódio em endodontia ». Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4380.
Texte intégralRésumé :
Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina DentáriaNos últimos anos, a Endodontia tem sido das áreas da Medicina Dentária que mais tem evoluído, de forma a apresentar melhores resultados nos tratamentos a que se propõe. Sabemos atualmente que um dos principais objetivos da Endodontia é devolver ao sistema de canais radiculares (SCR) as condições ideais de assépsia, eliminando os microorganismos patogénicos e restabelecendo a função do dente. Deste modo, o insucesso do tratamento endodôntico atribui-se, hoje em dia, à permanência dos microorganismos no SCR, não só devido à possibilidade de ocorrer uma desinfeção deficitária, mas também devido à possível re-infeção, durante o tratamento, ou devido a um selamento coronal insuficiente. A eliminação de microorganismos do SCR infetados é uma tarefa complicada, que envolve o uso de várias técnicas de instrumentação, esquemas de irrigação e medicamentos intracanalares. Deste modo, os irrigantes endodônticos têm um papel importante na otimização do preparo do canal radicular, apesar dos desafios morfológicos da anatomia radicular. De todas as substâncias utilizadas atualmente, o hipoclorito de sódio (NaOCl) parece ser o ideal, pois cobre mais requisitos para irrigante endodôntico do que qualquer outro composto conhecido. Há diversos fatores que podem influenciar o modo de atuação do NaOCl, tais como: a concentração, a temperatura, o pH, o tempo/volume de irrigação, a agitação do irrigante, os métodos de introdução do irrigante, a conicidade apical e a profundidade de colocação da agulha. Pareceu-nos pertinente a realização desta pesquisa bibliográfica para esclarecer a forma como o NaOCl atua, as suas características, vantagens e desvantagens e os efeitos da sua associação com outras soluções irrigantes. Para tal foi realizada uma pesquisa bibliográfica nos principais motores de busca: PubMed, B-On e Science Direct, utilizando as palavras-chave “sodium hypochlorite”, “irrigant solutions” e “irrigant extrusion”, que foram associadas de várias formas. Foram incluídos artigos em português, espanhol e inglês, publicados entre 1990 e 2013. A pesquisa foi efetuada entre Setembro de 2013 e Maio de 2014. Como principais conclusões, podemos afirmar que o NaOCl apresenta grandes vantagens se for usado corretamente e, a sua associação com outros compostos, pode potenciar os seus efeitos benéficos. Throughout time, Endodontics has been one of Dentistry’s areas that have evolved the most, so it can present better results in the treatments proposed. We know currently that one of the main objectives in Endodontics are to give back to the root canal system (RCS) the ideal conditions of asepsis, eliminating the pathogenic microorganisms and reestablishing tooth function. Therefore the failure of an endodontic treatment is due to the permanency of microogarnisms in the RCS not only due to the possibility of a deficit in disinfection, but also to the chance that there might be a reinfection during treatment, or to an insufficient coronal seal. The elimination of microorganisms in the infected RCS is a complicated task that involves the use of many instrumentation techniques, irrigation schemes and intracanal medicaments. Hence the important role of endodontic irrigants in the optimization of the root canal preparation despite the morphological challenges of the root canal anatomy. Of all the currently used substances, sodium hypochlorite (NaOCl) seems to be ideal, considering it covers more requirements than any other known compound. There are several factors that can influence the mode of action of NaOCl, such as: concentration, temperature, pH, time/volume of the irrigation, methods by which the irrigant is introduced, apical taper and needle insertion depth. It seemed pertinent the realization of this bibliographic research, to enlighten the way NaOCl acts, its characteristics, the advantages, disadvantages and the effect of its association with other irrigant solutions. To this end a bibliographic research was performed on the main search engines: PubMed, B-On and Science Direct, using the key-words “sodium hypochlorite”, “irrigant solutions” and “irrigant extrusion” which were associated in many forms. Were included articles in portuguese, spanish and english, published between 1990 and 2013. The research was done between September 2013 and May 2014. As our main conclusions, we can state that NaOCl presents great advantages, if used correctly, and its association with other compounds can enhance their beneficial effects.
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Rebelo, Pedro Filipe Dias. « Soluções irrigantes em endodontia ». Master's thesis, [s.n.], 2015. http://hdl.handle.net/10284/5246.
Texte intégralRésumé :
Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina DentáriaA evolução constante da Endodontia tem proporcionado novas formas e melhores resultados no tratamento de canais radiculares infectados. Sabemos que o sucesso endodôntico está dependente da limpeza e remoção dos microorganismos, devolvendo ao sistema de canais radiculares (SCR) condições ideais de assepsia, restabelecendo a função do dente. Assim, o sucesso endodôntico está dependente de uma correta conformação, desinfeção e selamento do SCR. A desinfeção do SCR inclui procedimentos de limpeza mecânica e química, existindo atualmente várias técnicas de instrumentação, esquemas de irrigação e medicação intracanalar. Apesar da complexidade do SCR, os irrigantes desempenham um papel fundamental no sucesso da TENC. De entre todas as soluções irrigantes conhecidas, a que mais se aproxima da solução irrigante ideal é o NaOCl devido às suas propriedades demonstradas por vários estudos. A eficácia do NaOCl pode ser influenciada por diversos factores como a sua concentração e pH, a temperatura, o tempo de exposição e pelo seu modo de agitação. Além de ser utilizado isoladamente, o NaOCl pode ser associado a outras soluções irrigantes como o gluconato de clorexidina ou com o EDTA, trazendo inúmeras vantagens para um desbridamento mais eficaz do SCR. Para tal a pesquisa bibliográfica foi realizada nos motores de busca: PubMed e Science Direct, utilizando as palavras-chave “endodontic irrigation”, “endodontic irrigants” e “sodium hypochlorite”. Foram incluídos artigos em português e inglês, publicados entre 1988 e 2015. A pesquisa foi realizada entre Fevereiro de 2015 e Junho de 2015. Em suma, a utilização das diversas soluções irrigantes e a sua associação traz efeitos vantajosos para o sucesso da TENC.
The constant evolution of Edodontic has given us new ways of treatment and with those, better results in the processing of infected root canals. It is known that edodontic success is related with the removal and cleaning of microorganisms, providing perfect asepsis conditions to the system root canals (SCR) and in accordance with that re-establish tooth functions. Therefore, endodontic success depends on a correct conformation, disinfection and sealing of the SCR. SCR disinfection has different mechanical and chemical cleaning procedures, currently we have several such as irrigation schemes, instrumentation techniques or intracanalar medication. Despite of all SCR complexity, irrigators have a key role in TENC's success. Among all known irrigating solutions, several studies have proved that NaOC1 can give the best irrigating solution due to its properties. NaOC1 efficiency may be affected by many factors, for example pH concentration, temperature, exposure time and agitation mode. Besides NaOC1 could be used alone, it can also be associated to other solutions: chlorhexidine gluconate or EDTA. These associations permit us to have a considerable number of advantages for a more effective SCR debridement. A bibliographic research was made on: PubMed and Science Direct, searching for “endodontic irrigation”, “endodontic irrigants” and “sodium hypochlorite” as key words. It has been included Portuguese and English articles, published between 1988 and 2015. The research was conducted between February 2015 and June 2015. Resuming, the use of different irrigating solutions and its associations lead to a beneficial effect on the success of TENC.
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Lee, Justin Chee Vui. « Development of a predictive model for the hypochlorite bleaching of CE-prebleached Pinus radiata Kraft pulp ». Thesis, University of Canterbury. Chemical and Process Engineering, 1990. http://hdl.handle.net/10092/8782.
Texte intégralRésumé :
A study was done to determine the kinetics and stoichiometry of hypochlorite bleaching of pinus radiata kraft pulp obtained from the extraction stage of a chlorine, caustic extraction and hypochlorite (CEH) bleaching sequence. The "differential method" of experimentation was used, where bleaching chemicals are charged at the start of the experiment and allowed to decrease as bleaching proceeds. The bleaching rate is found to be dependent on temperature, chromophore concentration (approximated by the specific light absorption coefficient), hypochlorite ion concentration (OCl-) and hydroxide ion concentration (alkalinity, OH-). Bleaching rate increases with chromophore concentration and hypochlorite ion concentration but decreases with increasing alkalinity. The bleaching rate, [formula here], for the hypochlorite bleaching of CE-prebleached pinus radiata kraft pulp can be expressed by the following kinetic equation.
[formula here]
where
Ck : specific light absorption coefficient at 457 nm, [m² kg-¹].
[OH-] : hydroxide ion concentration, [mol 1-¹].
[OCl-] : hypochlorite ion concentration, [mol 1-¹]
and the Arrhenius' activation energy is approximately 64 kJ mol-¹
The stoichiometry of the bleaching reaction can be described by the following two equations.
[formulas here]
Where
Cko : initial specific light absorption coefficient, [m²kg-¹]
OCo : initial hypochlorite charge, [moles per kg O.D. pulp]
OCl : hypochlorite charge at time=t, [moles per kg O.D. pulp].
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Melton, Tyler C., et Stacy D. Brown. « The Fate of Sulfamethazine in Sodium-Hypochlorite-Treated Drinking Water : Monitoring by LC-MSN-IT-TOF ». Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/5317.
Texte intégralRésumé :
Pharmaceutical compounds represent a rapidly emerging class of environmental contaminants. Such compounds were recently classified by the U.S. Geological Survey, including several antibiotics. An LC-MS/MS screening method for the top five antibiotics in drinking water was developed and validated using a Shimadzu LC-MS-IT-TOF. The separation was performed using a Waters Acquity UPLC BEH C18 column with a gradient elution. Sulfamethazine was exposed to conditions intended to mimic drinking water chlorination, and samples were collected and quenched with excess sodium sulfite. Kinetics of sulfamethazine degradation was followed as well as the formation of the major chlorinated byproduct (m/z 313). For the screening method, all five antibiotic peaks were baseline resolved within 5 minutes. Additionally, precision and accuracy of the screening method were less than 15%. Degradation of sulfamethazine upon exposure to drinking water chlorination occurred by first order kinetics with a half-life of 5.3 × 10(4) min (approximately 37 days) with measurements starting 5 minutes after chlorination. Likewise, the formation of the major chlorinated product occurred by first order kinetics with a rate constant of 2.0 × 10(-2). The proposed identification of the chlorinated product was 4-amino-(5-chloro-4,6-dimethyl-2-pyrimidinyl)-benzenesulfonamide (C12H13N4O2SCl) using MS (n) spectra and databases searches of SciFinder and ChemSpider.
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Sanglay, Gabriel Christopher. « Inactivation and Mechanism of Electron Beam Irradiation and Sodium Hypochlorite Sanitizers against a Human Norovirus Surrogate ». The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354305401.
Texte intégral