Dissertations / Theses on the topic 'Decontamination'
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Chilcott, Robert Peter. "Vesicant prophylaxis and decontamination." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325530.
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Redzuan, Norizah. "Cold plasma air decontamination." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/2286/.
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Cold Plasma Discharges offer wide decontamination scenarios relevant to environmental, food and drink or clean room applications. The option to operate the discharge system in atmospheric or sub-atmospheric condition provides an opportunity to investigate a lowcost and simple system design. UV to NIR (200nm to 700nm) can be emitted by pulsed cold plasma discharge systems that operate at atmospheric pressure. Different wavelengths emitted from the discharge depend on the pressure and the type of gas mix used in the systems. The scope of the work involved in this research was to design and develop a prototype cold plasma system for air at atmospheric pressure. The prototype was used for air decontamination by passing seeded and unseeded air between the electrodes gap. Modelling of the discharge and pulse forming network circuit systems was carried out in MultiSim to investigate the circuit characteristic. The components values ie: capacitors, stray inductors and resistors in the model system are interchangeable which enabled simulation of individual component effects on the output pulse shape and magnitude. The optimum component properties from the modelling were used as a guide to designing the system. The main discharge system contained a pair of Chang Uniform Field Electrodes which were manufactured in-house, and provided a discharge area of 1.0cm x 60.0 cm. The discharge volume is varied depending on the gap between of the anode and cathode. Preionisation was achieved via trigger wire, built within the discharge system. This promotes the ionisation of the gas in between the electrodes in enhancing uniform discharge characteristics. Different types of electrodes were made from aluminium with the discharge size 300mm x 200mm, laser marked and unmarked surface were also used in the system in order to obtain wider discharge surface and reduce manufacturing costs.
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Discepolo, Dakota Rose. "WORKING CANINE DECONTAMINATION: EFFECT OF CLEANSER & SERIAL DECONTAMINATION ON DERMAL BARRIER FUNCTION." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2809.
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Working canines provide a key service to society. During their work, they may be exposed to various environmental contaminants. Unfortunately, previous work has shown that current working canine decontamination protocols are lacking in efficacy (Venable et al., 2017). Furthermore, little work has been done to explore cleanser options and serial decontamination. Therefore, we designed two studies to investigate the impact of cleanser on contaminant removal, and the impact of serial cleanser application on canine dermal health and skin barrier function when applied daily for 14 days. Both studies were approved by the Southern Illinois University Institutional Animal Use and Care Committee (#15-032, #19-031) prior to initiation of the work. Treatments for analysis of cleansers for canine decontamination included Dawn, povidone surgical scrub, chlorohexidine surgical Scrub, or water. Each treatment was balanced by coat type (long; short). A fluorescent marker was used to determine efficacy in contaminant reduction. Significant decreases associated with coat type (P < 0.0082) and cleanser (P < 0.0001) were measured for dermal pH. Additionally, treatment impacted TEWL (P = 0.0049). Yet, TEWL was unaffected by coat type (P = 0.4881). Visual scoring of images revealed that all cleansers were more successful at reduction when compared to control (P < 0.0001). However, software analysis software, yielded no differences in treatment (P = 0.5567). Interestingly, we found a significant correlation between the visual scores and the Image J (P = 0.0006). Repeated decontamination on 8 (n= 8) Labrador retrievers significantly increased TEWL (P< 0.0001) through day 21 and then decreasing the remainder of the study. Similarly, sebum data was also impacted by repeated daily decontamination efforts, decreasing during bathing and then increasing (P =0.0387). Higher sebum values are seen later in the study and may be associated with recovery. In contrast, moisture content (P = 0.3842) and pH (P = 0.7462), were unaffected by repeated decontamination. Interestingly, dander scores assessed on the back were worsened by repeated decontamination (P = 0.0222) but dander scores assessed across the whole body were unaffected (P = 0.1804). Coat shine was unaffected by decontamination (P = 0.1156) similar to coat softness (P = 0.3418). Overall coat condition remained unchanged as a result of repeated decontamination efforts (P= 0.9466). These data reveal that daily decontamination impacts dermal function, potentially increasing the animal’s health risk.
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Yassine, Daadaa. "Network Decontamination with Temporal Immunity." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20633.
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Network decontamination is a well known mobile agent problem with many applications. We assume that all nodes of a network are contaminated (e.g., by a virus) and a set of agents is deployed to decontaminate them. An agent passing by a node decontaminates it, however a decontaminated node can be recontaminated if any of its neighbours is contaminated. In the vast literature a variety of models are considered and different assumptions are made on the power of the agents.
In this thesis we study variation of the decontamination problem in mesh and tori topologies, under the assumption that when a node is decontaminated, it is immune to recontamination for a predefined amount of time t (called immunity time). After the immunity time is elapsed, recontamination can occur.
We focus on three different models: mobile agents (MA), cellular automata (CA), and mobile cellular automata (MCA). The first two models are commonly studied and employed in several other contexts, the third model is introduced in this thesis for the first time. In each model we study the temporal decontamination problem (adapted to the particular setting) under a variety of assumptions on the capabilities of the decontaminating elements (agents for MA and MCA, decontaminating cells for CA). Some of the parameters we consider in this study are: visibility of the active elements, their ability to make copies of themselves, their ability to communicate, and the possibility to remember their past actions (memory). We describe several solutions in the various scenarios and we analyze their complexity. Efficiency is evaluated slightly differently in each model, but essentially the effort is in the minimization of the number of simultaneous decontaminating elements active in the system while performing the decontamination with a given immunity time.
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Rakotomalala, Livaniaina Hary. "Network Decontamination Using Cellular Automata." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34095.
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We consider the problem of decontaminating a network where all nodes are infected by a virus. The decontamination strategy is performed using a Cellular Automata (CA) model in which each node of the network is represented by the automata cell and thus, the network host status is also mapped to the CA state (contaminated, decontaminating, decontaminated). All hosts are assumed to be initially contaminated and the status of each cell is synchronously updated according to a set of local rules, based on the state of its neighbourhood. Our goal is to find the set of local rules that will accomplish the decontamination in an optimal way. The metrics used to define optimality is the minimization of three metrics: the maximum number of decontaminating cells at each step, the required value of the immunity time of each cell and the number of steps to complete the sanitization algorithm.
In our research, we explore the designing of these local decontamination rules by refining the concept of the neighbourhood radius of CA with the addition of two new dimensions: Visibility Hop and Contamination Distance. Additionally, a research tool that help us manage our study have been developed.
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Qiu, Jun. "Best effort decontamination of networks." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27908.
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In this thesis we consider the problem to find the optimal strategy to decontaminate the maximum possible number of nodes in a contaminated network with a fixed number of agents. We are given a team of mobile agents located on a node in a contaminated network and the number of agents is not enough to decontaminate the whole network to reach a state in which all nodes are simultaneously clean. We want to find what the maximum number of decontaminated nodes is and how to decontaminate them. In this thesis we consider meshes (regular, octagonal, and hexagonal) and trees and give optimal strategies for those topologies. We also analyze the performance of our strategies according to the number of decontaminated nodes, number of agents' movement and time.
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Maktabi, Siavash. "Combination methods for microbial decontamination." Thesis, University of Glasgow, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433618.
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Mine, Takashi. "Laser and plasma air decontamination." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/2276/.
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This research investigated novel decontamination methods of airborne microorganisms in enclosed public spaces. There are many ways the pathogenic micro-organisms can be transmitted from one body to another, which includes for example, physical contact between the contaminated surface to another, transfer of infected blood from a donor to another medium, or respiratory infections where the large droplets containing micro-organisms caused by talking, sneezing or coughing can infect another whether by direct or close contact, and airborne transmission where the tiny aerosol droplets containing the micro-organisms remain in the air for a long period of time thus spreading to wider areas, making this mode of transmission the most effective and thus dangerous. There are many technique and systems in the market today in the field of air cleaning, and many more under development, these include: ozone, plasma, UV, IR, microwave irradiation, passive solar exposure, pulsed light, electrostatic precipitation, photo-catalytic oxidation etc. However air decontamination using a laser is an unexplored approach. In general two different mechanisms are studied in detail in this research. The possibility of using radiation from the laser and also using plasma and its bi-products were investigated. Many variations and techniques were evaluated for both mechanisms to optimise each decontamination effect. Two types of lasers were used to investigate the concept of using lasers to decontaminate air: a CO2 laser producing a beam at 10.6 μm in the IR region and a KrF excimer laser producing a beam at 248 nm in the UV region. This research was to investigate and make use of the power that is available in the laser in a certain way to decontaminate the air. The effect of laser beam absorption in the presence of microorganisms was modelled in Matlab and this could be used to analyse any wavelength. Two variations of creating a plasma were investigated, one method used a Chang profiled, uniform field electrode and the other used an increased size flat electrode. The plasma produced from these systems emitted radiation around 200 nm to 900 nm. The Chang profiled electrode, which was manufactured in house, was originally designed to be used as a Nitrogen air laser. However, experiments with a purchased Nitrogen laser (detailed in Chapter 3) did not show any significant bacterial killing so the system was modified to be used as a plasma air decontamination device. The electrode was sized 60 mm x 10 mm, and the discharge volume was varied by altering the discharge gap. The effects of various parameters were investigated including: the discharge voltage, type of pre-ionisers to optimise the discharge and air flow shaping through the discharge region. Microbiological experiments conducted using air seeded with microorganisms was used to test the system’s decontamination efficiency. The second plasma system used larger 200 mm x 30 mm aluminium electrodes. Again various parameters were investigated to maximise the discharge stability which included, type of dielectric medium, type of power source, electrical circuit setup, use of laser marked electrodes, air flow shaping and using multiple electrode pairs running off the same power supply. Again, microbiological experiments conducted using air seeded with microorganisms was used to test the system’s decontamination efficiency. Two further systems were built using the results obtained from testing the 200 mm x 30 mm aluminium electrodes, an Industrial Based Air Decontamination Unit and a Ozone Shock Plasma System. Both systems were comprised with multiple pairs of laser marked electrodes with dielectric media and possible addition of flow shaping. The two systems were tested as before with good effect. The developed prototypes can be applied to most applications where air cleanliness is required.
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Mair, Garet Richard. "Intelligent control of remote decontamination equipment." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415945.
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Lang, Adam. "Contamination and decontamination of steel components." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/contamination-and-decontamination-of-steel-components(32951cc3-b259-4e0b-b97e-fcc45c507bb7).html.
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Nuclear plant stainless steel can become contaminated by radionuclides during normal operation whereby the final disposition of these materials then becomes a major decommissioning challenge to address. Characterisation of the chemical and metallurgical processes that underpin contamination is essential in consideration of developing cost effective decontamination and prevention methods, as are in situ measurement techniques that allow assessment of contamination. To address these issues, contamination experiments to simulate the nitric acid-based reprocessing streams of the PUREX (Plutonium Uranium Redox Extraction) process, and alkaline spent fuel storage ponds were investigated. Solution and surface spectroscopic measurements were performed to characterise the sorption behaviour of stable analogues of two high yield fission products, Sr-90 and Cs-137, on as received and 30 % cold rolled AISI Type 304 stainless steel, respectively. In addition Laser Induced Breakdown Spectroscopy (LIBS) was also investigated as a standoff contamination assessment technique. Fission product accumulation was modelled to a second order kinetic fit that considers chemisorption, typically to a hydrous metal oxide surface, as rate controlling. This process is observed to be independent of solution composition and strain processing regime. This behaviour reflects complexation to the passivating surface chromium oxide film, and as determined by depth elemental analysis, effectively inhibits contaminant migration into the bulk material. Environment chemistry and microstructural variables that destabilise the Cr-rich passive film however reduces the passive layer capabilities to effectively inhibit fission product bulk diffusion. The importance of corrosion phenomena towards radionuclide sorption processes necessitates the consideration of metallurgical and chemical factors during the implementation of decontamination approaches to treat affected plant material at nuclear licenced sites. LIBS was found to be a satisfactory technique for measurement of Sr sorbed to steel but Cs could not be detected at the concentrations used in this experimentation. Furthermore, EDX and TOF-SIMS elemental mapping indicated ablated material may be redistributed into the crater profile during elemental analysis. This process has clear implications for the deployment of LIBS for in situ characterisation of nuclear materials as the uncontrolled redistribution of radioactive material certainly violates decommissioning principles.
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Watt, Kathryn Elizabeth. "Decontamination techniques in ancient DNA analysis /." Burnaby B.C. : Simon Fraser University, 2005. http://ir.lib.sfu.ca/handle/1892/2446.
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Lapatto-Reiniluoto, Outi. "Acute poisonings : epidemiology and gastric decontamination." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/lapatto-reiniluoto/.
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GOEDERT, ANNICK. "Desinsectisation et decontamination des plantes medicinales." Strasbourg 1, 1992. http://www.theses.fr/1992STR15059.
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Demmer, Rick. "Decontamination method comparison testing using simulated contamination." Thesis, Lancaster University, 2016. http://eprints.lancs.ac.uk/80223/.
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Radiological decontamination of surfaces is challenging. Cleanup tasks are typically visual or even chemically measured, but radioactive contamination is invisible and measured at extremely low levels. Different contamination events have lead to the development of hundreds of decontamination processes. Their selection balances criteria such as cost effectiveness and waste minimization. While testing on the actual system where the contaminations arises (as "field" radioactive specimens) is appropriate, doing so is expensive and time consuming. Simulating contamination with substitute contaminants requires a unique understanding of the system. This provides a less expensive, more controlled and often more informative selection method. However, not all simulation methods are reliable, reproducible, have a useful range nor are relevant to the target activity. To address these needs, a range of simulated contamination systems have been developed: ·SIMCON 1 – to simulate loose contamination on stainless steel; ·SIMCON 2 – to simulate fixed contamination on oxide coated stainless steel; ·A radiological dispersal device (RDD) or so-called “dirty bomb” contaminant to simulate fixed contamination on urban material surfaces. Over 400 individual decontamination tests have been performed with these simulants, using a range of contaminants (Cs, Zr, Am, Sr, Co) and substrates (steel, concrete, marble, limestone, granite). Review and data mining of the results of these tests has allowed for the development of an understanding of the fundamental mechanisms of interaction between contamination and surface and their role in determining decontamination efficiency. Detailed analysis of the SIMCON results demonstrates that the availability of a deliberately designed contamination simulant system allows for the comparative assessment of a wide range of decontamination methods in a common frame of reference on a “level playing field”. Though somewhat intuitively obvious, the SIMCON methods evaluation unambiguously demonstrated that chemically different contaminants may behave quite differently during a decontamination action. The exact nature of this behavior depends upon the nature of applications (loose or fixed) and the decontamination method itself. If a wide range of decontamination methods are deployed on a well-designed contamination simulant, comparison of the results of the decontamination tests may provide insight into the mechanism of contamination e.g. how it is held (loose, fixed etc.), where it is held (on the surface, in a protective oxide layer etc.) and so forth. These conclusions are reinforced by detailed consideration of the urban RDD simulant decontamination data. With respect to the contaminants themselves, it is found that cations that exhibit a pH dependent speciation, such as americium or cobalt, can demonstrate radionuclide / material substrate specific chemistry that results in contaminant precipitation at the substrate surface, especially if the material has an intrinsically alkaline surface pH. For example, in the case of Am and Co, this results in the precipitation of Am and Co oxyhydroxide species at the outer surface of materials such as concrete with consequently high percentage removal efficiencies. For cationic radionuclides such as Cs+ that do not exhibit any nuclide/material surface specific chemistry the principal material property controlling the tenacity of that nuclide during decontamination from urban material substrates is the permeability of that substrate. For substrates of similar permeability, net surface negative charge on the material substrate plays a major role in determining the tenacity of non-reactive cations such as cesium; the larger the net negative charge on the substrate surface, the more tenacious the contamination. Finally, with respect to the decontamination agents themselves, harsh, high concentration chemical agents that utilize multiple decontamination processes (acids, bases, chelants) typically have an effectiveness advantage over more dilute, one component solutions. Strongly acidic solutions achieve the highest overall % removal decontamination results. This is partly because they tend to dissolve small amounts of the substrate surface and liberate imbibed contaminants. Finally, some strippable coating based methods are found to be surprisingly effective; likely because of their chelant/absorbtive character.
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McCann, MaÌireÌad Susan. "Surface decontamination of foods using thermal processes." Thesis, Ulster University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438806.
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Lin, Yichao. "Decontamination from Black Viruses Using Parallel Strategies." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38237.
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In this thesis, we consider the problem of decontaminating networks from black viruses (BVs) with a team of mobile agents, using parallel strategies. The BV is a harmful process whose initial location is unknown a priori. It destroys any agent arriving at the network site where it resides and, once triggered, it spreads to all the neighboring sites, creating copies of itself, thus increasing its presence in the network. To eliminate a virus present in a node, an agent has to move on that node; however, once the disinfection is performed, the agent is destroyed (i.e., it becomes inactive and cannot operate anymore). Existing literature has proposed sequential strategies that minimize the spread of the virus, such techniques are however quite inefficient in terms of time complexity. Instead of exploring the network sequentially, we propose to employ a group of agents that cooperate to follow a collective protocol to explore the network simultaneously. In this way, we dramatically reduce the decontamination time, still keeping the spread (and the number of agents loss) asymptotically optimal. In the thesis, various protocols are proposed in meshes, tori, and chordal rings following the monotonicity principle (i.e., once a node is disinfected we prevent it from being recontaminated). Finally, a solution is proposed also for the general case of the arbitrary topology. We analyze theoretically the cost of all our solutions for special topologies showing the advantages of our strategies with respect to the existing ones. In the case of the arbitrary topology, we conduct experimental analysis to assess the performance of our solution, confirming its efficiency. In all cases, our strategies significantly improve time while maintaining asymptotically optimal spread and agent losses.
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McAnoy, Andrew M. Sait Michelle Pantelidis Sue. "Establishment of a vaporous Hydrogen Peroxide bio-decontamination capability." Fishermans Bend, Victoria : Defence Science and Technology Organisation, 2007. http://hdl.handle.net/1947/8654.
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Hawas, Ahmed. "Peri-implantis : associated microbiota, biofilm formation and decontamination." Thesis, King's College London (University of London), 2014. https://kclpure.kcl.ac.uk/portal/en/theses/periimplantis-associated-microbiota-biofilm-formation-and-decontamination(a8d44329-c073-4359-a2cf-d8866c5cc84b).html.
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Peri-implantitis is a bacterially induced inflammatory condition that results in resorption of the bone supporting an implant. The methods for treating it are mainly empirical, and none have been shown to be universally successful. The first part of this research aimed to identify and compare the composition of the microbiota around dental implants with and without peri-implantitis. Subgingival plaque samples were collected from twenty-one subjects and samples were cultured using non-selective media and bacterial identification was carried out using 16S rRNA PCR. The second phase of the study investigated surface characteristics of implants that could influence the formation of a biofilm. Using a clinically relevant organism (Streptococcus oralis), an in vitro biofilm was developed and biofilm formation on four titanium implant surfaces exhibiting varying degrees of roughness with and without fluoride ions incorporated was evaluated using confocal laser scanning electron microscopy, bacterial culturing and scanning electron microscopy. The final phase examined the effects of mechanical debridement and air-polishing using glycine or 45S5 bioactive glass powders in re-establishing biocompatibility of the previously contaminated implant surfaces. Biocompatibility of the surfaces was tested using cell culture with alveolar human osteoblasts for cell viability, proliferation and cell differentiation. Results showed that a complex subgingival microbiota was found around dental implants. Peri-implantitis was associated with an increased bacterial load. Filifactor alocis, Streptococcus constellatus, Parvimonas micra and Actinomyces meyeri were significantly more prevalent in peri-implantitis, while Veillonella parvula/ dispar and Neisseria elongata were more prevalent in healthy sites. There were no significant differences in biofilm volume, surface area covered by the biofilm, nor number of bacteria found on any of the surfaces tested or at different levels within the biofilm suggesting that once colonization has been established, the effect of the surface diminishes with maturation of the biofilm. Although cleaning efficiency was different, all decontamination methods tested were shown to yield a biocompatible implant surface.
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Jaafar, Weaam. "Laser decontamination and detection of bacteria and microalgae." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6172/.
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There are many harmful airborne microorganisms which can be breathed in by animals or humans and lead to illness or even death. Such organisms can land on surfaces or in liquid leading to other opportunistic routes to infection such as touch and ingestion. Consequently, there is a need to develop novel forms of decontamination and detection of pathogens in air, on surfaces and in liquids. The present work investigates these areas and in particular assesses the impact of novel laser and plasma decontamination systems on inactivation of Bacillus atropheaus spores, an anthrax simulant, in aerosols and on surfaces. To further evaluate the performance of the methods, it was necessary to identify how the spores flowed through the systems. Experiments were devised to quantify the effect of flow shaping and the electrode’s surface roughness, on the spore deposition. The spatial distribution of B. atropheaus spores on the electrodes was determined by using two methods, either a membrane filter or an imprinting (pressing) technique. Rougher surfaces allowed a higher level of microorganisms adhesion compared to smooth surfaces. The angle of incidence of the flowshaping on the spore distribution was investigated by using two angles, 10° and 30°. The capture was quantified by the number of spores that were counted on agar plates following incubation. The number of colony forming unit CFU was greatest near the entry point, and generally reduced along the electrodes’ length and was also greater for the 30° inlet angle. Computational Fluid Dynamics (CFD) techniques were applied to model the particular flow through the electrode geometry and for the laser decontamination system. Methods of spatial detection of microorganisms on surface were further developed using microscopy methods. Three methods were used in this research: optical microscopy examination to find the minimum detectable level of B. atrophaeus spores on surfaces, a fluorescence technique using LEDs was developed to investigate the spatial detection of spores and microalgae and a flow chamber system was developed that was used for cell counting of microalgae in liquid. The effect of excimer laser radiation on Escherichia coli vegetative cells and Bacillus atrophaeus spores was investigated. E. coli or B. atrophaeus spores were lawned onto agar plates and treated with pulsed excimer laser radiation at 248 nm. The plates were incubated overnight at 37 °C and assessed for areas of clearing or inactivation. The applied pulse energy was 37 mJ, the pulse repetition frequency (PRF) was either 20 or 100 Hz, exposures were from 1-10 pulses, or up to 1 min. The range of applied energy densities was from 0.31 to 18500 Jcm-2. Image processing techniques were developed to determine the cleared area, major and minor axis and fractional clearing away from the region directly exposed to the laser beam. The area of clearing was approximately linear for treatment against E. coli, and was non-linear against B. atrophaeus. Increasing the PRF increased the area of clearing, as did increasing the exposure time. Interestingly, these areas of clearing were much greater than the beam area (2 x 6 mm), suggesting that scattering of the radiation played a significant role in contributing towards inactivation away from the directly laser exposed region. The results showed that excimer lasers offer the potential for rapid decontamination of microorganisms and spores on surfaces. Simple protocols allow direct comparison of the inactivation efficacy of different laser sources and image processing techniques can be applied to accurately quantify these results. Growing and harvesting microalgae is important for sustainable and secure biofuel and food production. There is a wide spread interest in growing and exploiting the microalgae. The lipid, protein, carbohydrate and vitamin content of microalgae are not only species dependent but are also a function of their growth parameters such as nutrient, light, temperature and CO2. The importance of detection of microalgae on assessing optimal growth conditions was investigated, along with the impact of harvesting and lipid extraction. Image processing systems were developed to quantify the size distribution of microalgae as a determinant of growth efficiency.
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Shariatmadari, Nader. "Decontamination of zinc-polluted kaolinite with electrokinetic process." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq21016.pdf.
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Goeksoy, E. O. "Decontamination of poultry meat by intense heat treatment." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297810.
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QUINIO, BERTRAND. "La decontamination digestive selective : etude chez le polytraumatise." Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX20819.
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Flynn, Julie M. "Decontamination of Central Venous Access Device Needleless Connectors." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/403241.
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Needleless connectors (NCs) are medical devices which connect to the end of vascular access devices. Since their introduction in the 1990s, in response to the increasing incidence of needle stick injuries experienced by nurses, they have become standard equipment for accessing venous access devices. The central venous access device (CVAD) is a specialised vascular device placed into a large vein leading to the heart for the administration of intravenous fluids, medications, blood products and specialised treatments. While NCs significantly reduced the occurrence of needle stick injuries, they also contributed to a rise in catheter-associated bloodstream infections (CABSI). This is largely due to inadequate cleaning and decontamination of microorganisms from the external surface of the NC by nurses prior to use. Over 1,000 cases of CABSI are reported in Australia annually. A CABSI can have a significant impact on patient morbidity and mortality, contributing to extended hospitalisation and affecting long-term health and lifestyle. Current research into NC decontamination practices is generally of low quality and indicates that current approaches remain ineffective, particularly in clinically vulnerable patients and those requiring long-term CVAD use.
Aim: The overarching aim of this project was to investigate the role of NC decontamination products in preventing CABSI and to assess the feasibility of conducting a superiority randomised controlled trial (RCT).
Methods: This research was underpinned by the United Kingdom Medical Research Council Framework for Developing and Evaluating Complex Interventions and Casadevall and Pirofski’s Damage-Response Framework of Microbial Pathogenesis and Infectious Diseases. This research was conducted in two phases: an in vitro study and a pilot RCT. A systematic review and meta-analysis were undertaken to inform the two research phases. In Phase One, the in vitro study compared three decontamination products (70% alcohol wipe; 2% chlorhexidine in 70% alcohol wipe; and a 70% alcohol-impregnated cap) for comparative efficacy. Six hundred and forty-eight NCs were used in the experiments consisting of three different types of NC designs, plus a contaminated and uncontaminated control. The connectors were contaminated with microorganisms commonly associated with CABSI, specifically Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans. Half of the NCs were pre-treated with human serum to mimic real-life use of the connector. In Phase Two, a pilot RCT was undertaken to assess the feasibility of a large, multi-site superiority trial comparing the same three decontamination products used in the in vitro phase. Recruitment for this pilot RCT occurred from 31 August 2017 to 8 March 2018. Participants were recruited from the surgical (general elective, emergency, vascular and orthopaedic), oncology (medical, surgical, haematological) and general medical units of RBWH. Elective surgical patients made up the largest cohort. Orthopaedic, medical oncology, and general medical patients were the least likely to be recruited. Overall, the average rate of recruitment across all admission types was 10 participants per month (range 1–17). Patients with a current bloodstream infection were excluded. The primary outcomes of feasibility were defined as: > 80% of patients screened were eligible; > 80% of eligible participants agreed to enrol; > 80% of participants in the study groups received their allocated treatment; < 5% of participants were lost to follow-up; there was < 5% missing outcome data. Based on these feasibility criteria, the hypothetical conclusions would be interpreted as: (i) all criteria will be met and trial is feasible without modification; (ii) one criterion not be met and trial is feasible with close monitoring; (iii) two or three criteria not be met and trial is feasible with modification; (iv) four or more criteria not be met and trial is not feasible. Secondary outcomes were rates of CABSI and microbial colonisation of the internal surface of NCs following removal of the CVAD.
Results of the in vitro study: The 2% chlorhexidine in 70% alcohol wipe resulted in a greater reduction of microorganisms than either the 70% alcohol wipe (t(70) = 74.32, p < 0.01) or the alcohol-impregnated cap (t(70) = 28.25, p < 0.01). The alcohol-impregnated cap was more effective than the alcohol wipe (t(70) = 5.01, p < 0.01). In the presence of human serum, all three products were effective in reducing colony counts of microorganisms, with the difference between the 2% chlorhexidine in 70% alcohol wipe and the other two products remaining statistically significant.
Results of the pilot randomised controlled trial: Two of the feasibility criteria were not met; therefore, it was decided that a superiority RCT would be feasible to proceed with modification. For the primary predefined feasibility outcomes, 152 patients were screened for eligibility, 53 were excluded; therefore, 99 patients were eligible for inclusion in the study. This proportion (72%) did not meet the feasibility criteria of 80% eligible for recruitment. Of the 99 patients eligible to participate, 91 patients were recruited; therefore, this criterion was met, with 92% of eligible patients recruited. Over the course of the study, 239 protocol checks were conducted on 74 of the 90 participants of which 78% were compliant. Hence, the criteria that > 80% of participants would receive their allocated treatment was not met. No participants were lost to follow-up and there was no missing outcome data, so both of these criteria were met. Five patients had blood cultures collected during the study; none were diagnosed as CABSI. Of the 12 NC’s assessed for microbial growth, all were contaminated.
Discussion: In the in vitro study the 2% chlorhexidine in 70% alcohol wipe out-performed the other products for NC decontamination. The pilot RCT established feasibility of the larger superiority trial, with modifications. It is recommended that to address the two unmet criteria a superiority multisite RCT may be needed to increase the proportion of potentially eligible participants. Recruitment should focus on the patient admission types of elective, emergency and oncology surgery, and haematology. Outpatients related to these groups should also be included. Trial fidelity may be enhanced through the adoption of a minimum of second daily checks and implementation of strategies such as bedside information indicating allocated treatment and increased engagement with clinical staff. Although no CABSI was recorded during the pilot RCT, secondary outcomes suggest that microbial colonisation of the internal surface of the NC may occur despite current decontamination practices which, coupled with extended CVAD dwell time, may contribute to infection. Follow-up of CVAD dwell time would facilitate quantification of rates of CABSI per 1,000 catheter days.
Overall, the results of this doctoral research suggest that the 2% chlorhexidine in 70% alcohol wipe may be the most effective approach to NC decontamination. However, further factors may impact its clinical efficacy to prevent CABSI, such as a 30-second duration of active decontamination, which may be difficult to achieve in practice. Neither are the results of in vitro research directly translatable to practice. This emphasises the need for a fully powered RCT to directly compare NC decontamination products and practice issues such as decontamination and drying times to determine the most effective approach. The pilot RCT detailed the protocol and design modifications required to optimise recruitment and trial fidelity to undertake such research.
Conclusion: This doctoral research has demonstrated the possibility of effective NC decontamination for CVADs and the need for, and feasibility of, further research to provide high-level evidence on the most efficacious and cost-effective product for NC decontamination. The resulting reduction in the occurrence of CABSI would have a significant impact on patient outcomes, patient quality of life, and healthcare-related costs.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Nursing & Midwifery
Griffith Health
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Cabello, Ernesto David. "Decontamination studies of simulated PWR primary coolant system components." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14092.
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Hardie, Ailsa Ghillaine. "Decontamination of soils by activation with acids and bases." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49901.
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Thesis (MSc)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: New, more receptive surfaces can be generated in soils by a partial dissolution of existing, crystalline solids followed by re-precipitation as poorly crystalline colloids with a larger capacity to adsorb ionic and molecular contaminants. This priming process can be carried out by treating the soil with strong acid or base and then neutral ising it again. The aim of this study was to investigate the effectiveness of acid and base treatments in reducing inorganic contaminant availability in different soil types. The first study involved investigating the change in cation (cadmium[II], copper[II]) and anion (phosphate) sorption of four different soils before and after priming. Hydrochloric acid and KOH were used to adjust the pH of soils to below pH 2 or above pH 12 in the dissolution stage of the priming treatment. After neutralisation it was found that base priming resulted in an increase in metal cation adsorption in all the soils, most notably in the sesquioxidic (increase from 19.5 to 73.5 mmol Cd.kg-1 soil) and kaolinitic soils (from 16.9 to 38.3 mmol Cd.kg-1 soil), whereas acid priming decreased it or had little effect on cation sorption. However, acid priming increased anion sorption in all soil types, to a greater extent than base priming, most notably in the organic soil (from 6.3 to 14.7 mmol P04.kg-1 soil). This can be attributed to the differences in the nature of the precipitate (more aluminous or alumino-siliceous) depending on whether the dissolution was carried out in acid or basic conditions, and the final pH of the soil solution, as the hydroxyaluminium and hydroxyaluminosilicate precipitates which form are known to enhance pH-dependent sorption of metals. In the second study, the soil was suspended in Cd or Cu solutions and then the pH was adjusted to below 2 or above 12 using HCI or KOH. After 5 days of shaking the pH was adjusted to a neutral pH again. The availability of the Cd and Cu was determined at each of the stages in the treatment, and it was found that both the acid and base treatments were effective in removing Cu from solution, whereas only the base treatment was effective in removing Cd. Determinations were also carried out using H2S04 and Ca(OH)2 and it was found that they were equally effective. It can be proposed that this acid-base pair would be of most practical importance as the salt generated is gypsum which is generally considered benign, and can actually help to improve the soil structure. Activation of soils by acid or base conditioning could have some useful applications in decontaminating soils or decreasing the mobility of inorganic contaminants in soils. Primed soils could also be used as cheap absorbents for decontaminating water.
AFRIKAANSE OPSOMMING: DEKONT AMINERING VAN GROND DEUR AKTIVlERING MET SURE EN BASISE Nuwe, meer ontvanklike oppervlakke kan in gronde gegenereer word deur middel van gedeeltelike oplossing van bestaande, kristallyne vaste stowwe gevolg deur herpresipitasie as swak kristallyne kolloïede met 'n groter kapasiteit om ioniese en molekulêre kontaminante te adsorbeer. Hierdie behandelingsproses kan uitgevoer word deur die grond met sterk suur of basis te behandel en dit daarna te neutraliseer. Die doel van hierdie studie was om die effektiwiteit van suur- of basisbehandelings om anorganiese kontaminante te verminder, in verskillende grond tipes te ondersoek. Die eerste studie het die ondersoek na die verandering in katioon- (kadmium[II], koper[lI]) en anioon- sorpsie (fosfaat) van vier verskillende gronde voor en na suur of basis voorbehandeling behels. Soutsuur en KOH was gebruik om die pH van die gronde tot onder pH 2 of bo pH 12 aan te pas gedurende die oplosstadium van die behandelingsproses. Na neutralisasie is dit gevind dat basis voorbehandeling tot 'n toename in metaal katioonadsorpsie in al die gronde gelei het, en dit was veral waarneembaar in die seskwioksied (toename van 19.5 tot 73.5 mmol Cd.kg" grond) en kaolinitiese (van 16.9 tot 38.3 mmol Cd.kg-1 grond) gronde, terwyl suur voorbehandeling dit verlaag het of 'n klein effek op katioonsorpsie gehad het. Suur voorbehandeling, egter, het anioonsorpsie in al die gronde verhoog, tot 'n groter mate as basis voorbehandeling, veral in die organiese grond (van 6.3 tot 14.7 mmol fosfaat.kg' grond). Dit kan toegeskryf word aan die verskille in die aard van die neerslag wat meer alurninium- of alurniniumsilika-ryk kan wees afhangede of die oplossing uitgevoer was in suur of basis kondisies, en ook die finale pH van die grondoplossing omdat die hidroksi-aluminium en hidroksi-aluminiumsilikaat presipitate wat vorm bekend daarvoor is om pH-afhanklike sorpsie van metale te bevorder. In die tweede studie, was die grond in Cd- of Cu-oplossings gesuspendeer en die pH was aangepas tot onder 2 of bo 12 met HCI of KOH. Na vyf dae van skud was die pH weer aangepas tot by neutraal. Die beskikbaarheid van Cd en Cu was bepaal by elke stadium in die behandeling, en dit is gevind dat beide suur- en basisbehandeling meer effektief was in die verwydering van Cu uit oplossing, terwyl slegs die basisbehandeling effektief was in die verwydering van Cd. Bepalings was ook uitgevoer met die gebruik van H2S04 en Ca(OH)2 en dit is gevind dat dit net so doeltreffend was soos HCI en KOH. Dit kan voorgestel word dat hierdie suur-basis paar in die praktyk belangriker sal wees omdat die sout wat gegenereer word, nl. gips, as 'n gunstige sout beskou word. Aktivering van grond deur suur- of basis-kondisionering kan sekere bruikbare toepassings in die dekontaminering van gronde hê of dit kan gebruik word om die mobiliteit van anorganiese kontaminante te verlaag. Suur of basis voorbehandelde gronde kan ook gebruik word as goedkoop absorbante vir die dekontaminering van water.
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Calvillo, Anthony. "Evaluation of Water-only Decontamination for Firefighters’ Turnout Gear." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1530880114309489.
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FUMAGALLI, FRANCESCO. "Protein thin films plasma removal: application to biological decontamination." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28155.
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Surgical instruments are intended to come into direct contact with the patients’ tissue and therefore need to be sterilized and decontaminated in order to prevent infections, inflammations and transmission of diseases. In the last years low-pressure plasma discharges have been successfully applied to remove various biomolecules from surfaces. However, the knowledge of the physical-chemical interaction mechanisms between plasma and biomolecules is still rather poor, which is a major limiting factor for the optimization of this type of plasma treatment. In this work an original contribution to the field is presented, either in terms of process development, of physical mechanisms investigation and process diagnostic protocols assessment. Experimental results were obtained with a low pressure double coil planar inductively coupled plasma reactor.
Plasma interactions with low bio-contamination levels (less than 5 μg/mm2) typical of biological residuals present after standard hospital sterilization protocols were studied. Removal mechanisms of biological thin films during plasma treatment with oxygen and water vapor containing discharge mixtures were characterized in-situ by means of quartz crystal microbalance (QCM), time resolved mass spectrometry and optical emission spectrometry. A novel QCM measurement technique was developed in this work as a quasi-online diagnostic tool in pulsed plasma operation. After plasma treatment, surfaces analysis techniques (XPS and AFM and profilometry) have been used to investigate ex-situ chemical and morphological changes at the surface of the protein films.
Moreover mass removal rates as measured by QCM were found to depend on treatment time, showing a self limiting etching kinetics. Removal rates dynamics has been characterized in different plasma conditions by a set of descriptive parameters and correlated with plasma induced chemical composition changes and morphological modification of the protein film.
The interaction mechanism between plasma and protein films have been studied in-situ. In the last years several authors presented experimental investigations devoted to isolate potential agents effective in plasma decontamination (UV, radicals, ions, heat) and to identify possible synergic mechanisms between them, but in most cases particle fluxes have been produced outside plasma environments (beam experiments) or the effect on protein films was studied by physically decoupling the effects of single mechanisms (UV screen, afterglows). In this work experiments were designed to quantitatively measure the fluxes of different potentially sterilizing species in the plasma phase (ions, radicals, UV and heat) and their interaction effects with a model protein film. Particle fluxes have been calculated using data from Langmuir probe, mass spectrometry, optical emission actinometry and infrared pyrometry measurements. Different experiments have been performed using plasma internal parameters (e.g. fluxes) as independent variables for the decontamination treatments, modifying one flux component at time while keeping the others constant the influence of synergetic effects between decontamination agents have been measured.
Furthermore the control of the DC bias applied on the sample holder allows changing the energy of the ions (moderate voltages from 10 to 150 V were applied) interacting with the surface.
Within the confidence limits of the statistical method implemented for validation, ion assisted chemical etching operating in an ion limited regime proved to be the mechanism which describes more accurately the etching rates for our biological substrates.
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FUKUMORI, DAVID T. "Contaminacao radioativa das roupas protetoras feitas de tecido e sua decontaminacao em solucoes aquosas." reponame:Repositório Institucional do IPEN, 1989. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9917.
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Made available in DSpace on 2014-10-09T12:32:49Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:08:33Z (GMT). No. of bitstreams: 1 03529.pdf: 1961648 bytes, checksum: e06abd1b76cadfd53cd1f77421b2f96e (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Dostie, Sébastien. "Chemotherapeutic decontamination of dental implants colonized by multispecies oral biofilm." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53472.
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Objectives: A recent meta-analysis reported that 18.8% of patients treated with dental implants are affected by peri-implantitis. Chemotherapeutic agents are often used during surgical decontamination of the dental implant despite limited evidence to support their efficacy. It is also known that mature biofilms are more resistant to antimicrobial agents. No studies have tested disinfectants on mature multispecies oral biofilms on titanium substrata. The aim of this study is to develop a multispecies oral biofilm implant model and to determine its susceptibility to antimicrobial agents. The null hypothesis is that no chemical agent is more effective than saline rinse to decontaminate sandblasted acid etched (SLA) titanium dental implant.
Methods: Collagen-coated SLA titanium discs were inoculated with dispersed dental plaque with minimum bacterial cell concentration of 3.2 × 10⁷ CFU/ml. After 21 days of anaerobic incubation, discs were rinsed with 0.9% NaCl to remove unattached biofilm, and exposed for 2 minutes to tetracycline paste, 1% chlorhexidine (CHX) gel, 35% phosphoric acid gel. Discs were rinsed again to remove the chemical agents. Bacterial counts were quantified from standardized scanning electron micrographs of the implant surface. Disinfectants were compared within each other and with the control groups (rinse and double-rinse).
Results: After three weeks, the biofilm thickness on SLA discs was approximately 30 µm and showed the presence of multitude of rod and coccoid organisms. Rinsing the surfaces with 0.9% NaCl removed the majority of the biofilm. However, bacteria persisted in all specimens regardless of the treatment and none of the disinfectants was superior to the saline double-rinse group. CLSM analysis showed that CHX and Etch groups had a statistically significant reduction of viable bacteria within the biofilms, although small. New chemical and peeling-off techniques were also tested but did not remove significantly more bacteria than the double-rinse group.
Conclusions: This mature multispecies biofilm model may be useful for the evaluation of decontamination of SLA implant surface. The tested chemical agents and the peeling-off techniques did not improve the decontamination effect when compared with the 0.9% NaCl rinse. CHX and Etch may provide a slight advantage in killing some of the remaining bacteria.Dentistry, Faculty of
Graduate
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Schulz, Arno. "Decontamination of arbitrary networks with multiple mobile agent home bases." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27292.
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In this thesis we consider the problem of searching for an intruder in arbitrary networks. A team of mobile software agents is deployed to capture the intruder (i.e., a virus) and decontaminate the network. These agents follow a common protocol, derived from the Breadth-First Search (BFS) algorithm, that is independent of the intruders' speed or knowledge and is designed to prevent any further re-contamination. To measure the efficiency of our protocols and find the ones which give the best results, we conduct experiments on arbitrary synchronous and asynchronous networks. In each experiment, we study a different aspect of the impact multiple starting locations and different levels of visibility have on minimizing the number of mobile software agents required to decontaminate the network and the time used in the process.
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Paul, Joydip. "NANOMATERIALS FOR THE DECONTAMINATION OF WASTE WATER CONTAINING PHARMACEUTICAL DRUGS." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177558.
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The existent of pharmaceutical drugs in our aquatic media is a preeminent burden for the environment effect including health fitness issues. The presence of tiny amount of organic and inorganic pharmaceutical drugs including hormones, birth control pills, NSAID, antibodies can causes a huge destruction for our living entity now a days. According to the report of WHO (World Health Organization), it is a matter of concern about the alarming existence of pharmaceutical drugs in our daily water supply systems because of these small portion of Pharmaceutical activated compound can cause enormous health effect for both animals and human being. The photocatalytic degradation of Ibuprofen and cetirizine has been chosen according to their large scale presence with waste water and also creating a benchmark with our conventional and nonconventional treatment processes of our waste water treatment plants to obtain pristine water. Even though our meticulous environmental regulation policy, Ibuprofen and Cetirizine both are vastly used by large portion of community in our society and they are major pharmaceutical contaminant of WWTP (waste water treatment plant) for their enormous uses by human being. TiO2, ZnO and several clay nanopowder with photocatalytic compounds are familiar as photocatalyst and their uses under UV light generator can able to degrade both pharmaceutical drugs. Three different types of TiO2 components (Anatase, Rutile and mixture of Anatease and Rutile) were used to determine the best efficient material among photocatalyst chemical nanopowder. ZnO and montmorillonite clay particles were tested for further verification of photocatalytic characteristics. The entire experiment was accomplished by batch reaction under several operating parameters consideration such as changing pH values, time and concentration. All parameters have very important influence on ibuprofen and cetirizine degradation was verified. Recently many efforts have been made to increase the efficiency of photocatalytic materials. By addition of MWCNT (Multi Walled Carbon Nano Tube) with photocatalyst nano powder can increase the photocatalytic efficiency by increasing recombination time was demonstrated here after examination. The entire goal of this thesis was to develop a suitable, sustainable and efficient hybrid nanofiber composite also successfully investigated. Using photocatalytic nanopowders to degrade the PhACs (Pharmaceutical Active Compounds) in WWTP are not very easy to separate after execution. Therefore, the idea of hybrid nanofibers was fabricated here to get remedy from separation problem. Hybrid nanofibers assembled by PAN (Polyacrylonitrile)/TiO2 where TiO2 were immobilized over electrospun PAN nanofibers. The nanofiber has been fabricated appropriately with electrospinning process by using N, N-dimethyl formamide (DMF), PAN and tetrabutyl titanate [Ti(OBu)4] sol-gel composites. TiO2 immobilized on PAN nanofiber after implementing hydrothermal process. The fabricated hybrid nanofibers were scrutinized with different characterization tools such as X-ray diffraction, field emission scanning electron microscopy, thermo gravimetric analysis and energy dispersive X-ray (EDX) spectroscopy. The outcome of fiber analysis represents the flexibility and large surface area of the hybrid nanofibers. The as-fabricated nanofibers were tested with ibuprofen solution under UV light irradiation. Impressive performances by fabricated nanofibers were examined for ibuprofen degradation after several minutes’ photocatalytic reaction.
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Cassar, Claire. "Bacterial survival and decontamination in relation to food contact surfaces." Thesis, King's College London (University of London), 1999. https://kclpure.kcl.ac.uk/portal/en/theses/bacterial-survival-and-decontamination-in-relation-to-food-contact-surfaces(376ed8d4-39c1-439e-9eb4-90a9700266f0).html.
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Balderson, Debra Susan. "The mechanical properties of skeletal allografts : preservation and decontamination effects." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313855.
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Datar, Joseph Nikki Abrogar. "Decontamination of titanium surfaces with air polishing and glycine powder." Thesis, University of Colorado at Denver, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10113174.
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Background: As the utilization of dental implants to replace missing teeth becomes more common, so does the incidence of peri-implant diseases, peri-implant mucositis and implantitis, caused by bacterial biofilm. The aim of this study was to evaluate the efficacy of removing bacteria from smooth-surface titanium using an air-polishing device with glycine powder abrasive.
Methods: Smooth-surface titanium discs were inoculated individually with Aggregatibacter actinomycetemcomitans, Streptococcus oralis, Streptococcus mutans, and Tannerella forsythia. Discs were treated with an air-polishing device with glycine powder and water, glycine powder alone, water alone, or tetracycline and water. Bacteria remaining on the surface of the titanium disks were removed and quantified.
Results: Compared with untreated control discs, all treatment types saw a statistically significant reduction in bacteria (p <0.01) regardless of bacterial species. There were no statistically significant differences in bacterial reduction between treatment types. Although not statistically significant, air polishing with glycine powder alone tended to be least effective in reducing total residual bacteria, while Tannerella forsythia showed the least amount of bacterial reduction.
Conclusions: For smooth surface titanium, air polishing with glycine powder and water, glycine powder alone, water alone, or tetracycline and water significantly reduces the amount of Streptococcus oralis, Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Tannerella forsythia.
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Li, Sirui. "Atmospheric non-thermal plasma discharges for cleaning and bio-decontamination." Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27572.
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It has been shown that non-thermal plasma has great potential for chemical oxidation and bacterial inactivation. However, the mechanism of plasma-induced oxidation and bactericidal effects is not fully understood, and optimisation of the non-thermal plasma treatment is required to improve the efficiency of this technology. This research presents an investigation into the oxidation and bio-decontamination capabilities of steady-state corona discharges and impulsive transient plasma discharges in atmospheric air. Degree of decolorisation of blue dye by plasma discharges was obtained and used for evaluation of the oxidation efficiency of these discharges. The Gram-positive and Gram-negative bacteria, Staphylococcus aureus and Escherichia coli, respectively, were used for investigation of the bio-decontamination capability of the plasma discharges. It has been shown that conditions such as air humidity, electrode topology, and voltage levels may affect the efficiency of plasma treatment. The obtained results show that the oxidation and inactivation effects depend on the amount of charge delivered by the plasma. The charge-dependent decolorisation and inactivation rates of plasma discharge treatment, which indicate the oxidation efficiency and inactivation efficiency, were obtained and analysed. Different decolorisation and inactivation rates were achieved with various electrode topologies and energisation polarities. This study also investigated the production of reactive species by atmospheric plasma discharges. Ozone concentration was measured during the decolorisation and inactivation tests. The production of OH radicals by the plasma discharges have also been obtained in this study using terephthalic acid as the chemical probe. The obtained results confirm that the reactive oxygen species play a major role in the plasma discharge treatment. In addition, an attempt of using TiO2 as a catalyst to enhance oxidation and bio-decontamination effects of the plasma discharge treatment has been made. TiO2 was revealed to have the potential to improve the oxidation efficiency of atmospheric plasma discharges. The results obtained and presented in this thesis will help in optimisation of non-thermal plasma systems for chemical and biological decontamination.
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Ketusky, Edward. "Remediation of spent oxalic acid nuclear decontamination solutions using ozone." Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/123625/.
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The Savannah River Site (SRS) has forty-three remaining very large underground tanks containing significant quantities of nuclear waste generated primarily from cold-war radiochemical separations. All of the tanks eventually must be closed. As part of decommissioning/closing the nuclear waste tanks, even residual quantities of the waste must be removed. Although most sludge can be removed mechanically, chemically cleaning (i.e. decontamination) with oxalic acid is used to aid in the removal of residual quantities. Although oxalic acid works for cleaning the tanks, its downstream impacts are considered detrimental. To better understand and quantify the impacts, detailed models were developed to account for different potential processing strategies for handling the spent oxalic acid nuclear decontamination slurries. Although the results vary, the models show that regardless of the oxalate handling strategies: 1) significant washing to decrease sodium concentration/solids concentration in vitrification feed will be required, and 2) the creation of copious future additions of feed for salt processing will be unavoidable. Using a Theory of Inventive Problem Solving (TRIZ) approach, a modified form of the Chemical Oxidation Reduction Decontamination (CORD) ultraviolet (UV) light was identified as being used with an analogous but already resolved problem that could be adapted to SRS HLW tank cleaning. A novel preliminary process called Enhanced Chemical Cleaning (ECC) was envisioned. As part of maturing the technology, the literature review identified three possible oxalate decomposition mechanisms associated with ECC. They are: 1)A heterogeneous non-Advanced Oxidation Process (AOP) mechanism where the target organic adsorbs onto the surface of a solid, often particulate, metal oxide at a so-called active site, followed by ozone attack on the sorbed organic; 2)A homogeneous non-AOP mechanism that operates under low pH acidic conditions and which involves complexation of the catalysing metal ion with the oxalate followed by ozone attack on the complex; and, 3)A homogeneous AOP mechanism that operates at a high basic pH and which involves metal ions catalysing the formation of hydroxyl radicals from ozone, with the said hydroxyl radicals then driving the oxalate decomposition. Process testing was conducted using slurries made from simulants designed to be chemically similar to real High-Level Waste (HLW) sludge types. Testing using slurries made from real HLW sludge was also performed, but because of safety limitations associated with handling HLW, only a much smaller scale test apparatus could be used. With the much smaller scale test apparatus, the purpose of the real HLW based testing was confirmatory. Each of the simulant decomposition test slurry was created using an Fe-rich or an Al/Mn-rich sludge simulant using either 1 wt% or 2.5 wt% oxalic acid. The real HLW based slurries were formed using 2 wt% oxalic acid. As part of the main postulate of this effort, both the simulant decomposition test slurries and real HLW based slurries demonstrate that UV light increased the decomposition rate. Even without UV, by adding only ozone, the oxalate decomposition was completed on an industrially relevant timescale. Also using simulant based testing, the overall oxalate decomposition exhibited four distinct stages related to the metal catalysts: Stage One – At short ozonation times, ozone decomposes Fe oxalates and solubilise Fe from ozone action on the metal oxide constituents of the sludge. Stage Two – At intermediate ozonation times, as a result of the loss of the solution capacity to complex (and so solubilise) Fe, Mn, and Ni ions due to O3 driven oxalate decomposition, as well as the pH increase that accompanies that decomposition, Fe begins to precipitate. Oxalate decomposition is still primarily catalysed by Fe ions during this stage. Stage Three – At intermediate ozonation times, Fe precipitation is near complete, and oxalate decomposition is now driven by ozone and Mn catalysis – Mn playing a major role in determining the final time to process endpoint of 1.1 × 10-3 M oxalate in solution. Stage Four – At long ozonation times, the process endpoint with Mn precipitation now near completion with Ni being the dominant metal ion in solution. Constructed plots compare the pH and remaining oxalate concentration, both as a function of time, suggesting some relationship. Regression analysis of the negative log of the oxalate concentration shows the R2 values are all greater than 0.80, confirming correlation. Thus, pH can be used as a field measure for confirming when oxalate decomposition is complete. As a principal hypothesis of this effort, using simulant based testing, both the scavenging effects of “all-ready present” nitrite (a soluble component of the sludge simulants) and oxalate mineralisation-derived carbonate are advantageously used in lieu of introducing hydroxyl radical probe compounds to the process. Specifically, differing nitrite concentrations between slurries showing no impact on the decomposition rates, and the build-up of carbonate not inhibiting the decomposition process strongly suggest that the decomposition is not the result of radicals. Instead, the oxalate decomposition is likely the result of a direct reaction of ozone with metal complexed oxalate (i.e. mechanism 2 discussed above).
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Smith, Jeffrey V. "Evaluation of Levulinic Acid for Topical Decontamination of Meat Surfaces." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1009.
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Experiments were performed to investigate the effects of wash treatments, consisting of hot water, 2% lactic, 2% acetic, or 2% levulinic acid, for decontamination of pathogenic bacteria previously inoculated onto meat surfaces, to inhibit growth of pathogenic bacteria inoculated onto previously washed meat surfaces, and on the organoleptic quality of sliced turkey roll and beef trim. Acid washes were no more effective at reducing Escherichia coli O157:H7 on beef plate, Listeria monocytogenes on sliced turkey roll, and Salmonella on pork belly than was water wash. Only lactic acid treatment was more effective than water at reducing Salmonella on chicken skin, but by less than 1 log CFU/cm2. Increasing wash temperatures with 2% levulinic acid did not reduce E. coli O157:H7 on beef plate. Organic acid washes did not protect against growth of L. monocytogenes and E. coli O157:H7. Acetic acid prevented growth of Salmonella, but only on chicken skin. Organic acid spray treatments of sliced turkey roll and beef trim did not affect consumer liking of turkey roll or cooked ground beef patties. Acid treatments had some effect on instrumental color measurements, but these appear to have little practical significance. Overall, washing with 2% organic acid solutions was no more effective at reducing pathogenic bacteria on meat surfaces than washing with water.
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Leontyev, Anton. "Laser decontamination and cleaning of metal surfaces : modelling and experimental studies." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00661695.
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Metal surface cleaning is highly required in different fields of modern industry. Nuclear industry seeks for new methods for oxidized surface decontamination, and thermonuclear installations require the cleaning of plasma facing components from tritium-containing deposited layer. The laser ablation is proposed as an effective and safe method for metal surface cleaning and decontamination. The important factor influencing the laser heating and ablation is the in-depth distribution of laser radiation. The model of light propagation in a scattering layer on a metal substrate is developed and applied to analyse the features of light distribution. To simulate the contaminated surfaces, the stainless steel AISI 304L was oxidized by laser and in a furnace. Radioactive contamination of the oxide layer was simulated by introducing europium and/or sodium. The decontamination factor of more than 300 was demonstrated with found optimal cleaning regime. The decreasing of the corrosion resistance was found after laser cleaning. The ablation thresholds of ITER-like surfaces were measured. The cleaning productivity of 0.07 m2/hour∙W was found. For mirror surfaces, the damage thresholds were determined to avoid damage during laser cleaning. The possibility to restore reflectivity after thin carbon layer deposition was demonstrated. The perspectives of further development of laser cleaning are discussed.
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Hanson, P. J. V. "The decontamination of endoscopes in AIDS patients : implications for infection control." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603667.
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Gill, James. "An investigation into the decontamination of carbon-14 from irradiated graphite." Thesis, University of Central Lancashire, 2014. http://clok.uclan.ac.uk/11145/.
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The decommissioning of nuclear power plants around the world will produce a major waste stream of irradiated graphite. Graphite has been used extensively as a reactor moderator and reflector material that becomes irradiated and contaminated over time. In the coming years ~250,000 tonnes of irradiated graphite will require management making this a significant waste management issue worldwide. Irradiated graphite is categorised as Intermediate Level Waste mostly due to its content of Carbon-14 (C-14) which is a long-lived radioisotope which could be released into the biosphere. In addition the Low Level Waste (LLW) repository at Drigg has very strict guidelines regarding C-14 authorisation and there is currently no deep geological repository available in the UK. Varying amounts of carbonaceous deposits have been identified on irradiated graphite samples removed from reactor cores. If these deposits are rich in C-14, treatment of the waste graphite by oxidation could reduce the C-14 inventory of the remaining graphite. This is the primary focus of this research. In order to investigate a technique that would decontaminate graphite from the carbonaceous deposits it was necessary to produce a range of carbonaceous deposits on virgin graphite material to act as a simulant for the deposits present on reactor graphite. Two deposition techniques were investigated: microwave plasma assisted chemical vapour deposition and a combination of solution deposition and charring. C-13 precursors were used as they facilitate the study of the selective removal of the deposit by mass spectrometry and spectroscopy. Using C-13 analogues instead of C-14 prevents the need to work in active laboratories and allows higher concentrations of deposit to be used which is beneficial when developing a technique for selective removal. A thermal treatment which utilised the application of a vacuum was investigated to determine whether the carbonaceous deposits could be selectively removed with minimal oxidation to the underlying graphite. As carbon deposits were more amorphous than crystalline graphite it was thought that they would oxidise quicker at lower temperatures than graphite. Virgin graphite and samples with deposits were characterised before and after thermal treatment using Scanning Electron Microscopy, Raman Spectroscopy, Thermal Gravimetric Analysis and Mass Spectrometry. An additional area of investigation was conducted using thermogravimetric studies of the oxidation of irradiated graphite which was carried out at the National Nuclear Laboratory’s Preston Lab. This would determine the distribution of C-14 in the carbonaceous deposits and underlying irradiated graphite which could be a key factor in the determination of possible treatments and eventual storage/disposal routes of the waste graphite.
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Tejowulan, Raden Sri. "Remediation of trace metal contaminated soils." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0030/NQ64679.pdf.
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Arrepia, Carlos Manuel Araújo. "Estudo crítico do processo de fabrico de sorbet artesanal. Processo de descontaminação do morango." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5260.
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Mestrado em Engenharia Alimentar - Segurança e Qualidade Alimentar - Instituto Superior de AgronomiaThe present study took place at Santini, S.A., a home made ice cream company, during the transfer layout for the new installations. The main objective was to delineate the manufacturing process of Sorbet, to can determinate the critical points of preparation of fruit (in particular strawberries), in order to optimize the process conditions in the new factory. Initially, still at the old installations, was carried on, the manual mode of strawberry descontamination, where was analysed different binomials time and concentration of sodium hypochlorite, in order to understand those that are more effective. Once defined the best results, it was possible to improve the choosen conditions to the descontamination operation in automatic mode. At the new plant, already at the automatic wash fruit machine 90 ppm solution of sodium hypochlorite was used at different times. Following the temperature, pH solution and % loss of soluble solids (SST) on strawberry, were monitored. It was concluded that for the test conditions in manual mode, the largest logarithmic reduction for microorganisms at 30º C was 2,15 log cycles for the conditions of 81 ppm at 1 minute and 116 ppm at 5 minutes. The application in automatic mode of 90 ppm for 5 minutes proved to be effective in reducing the microbial load present in the strawberry. The SST of the strawberry is inversely proportional to the duration of decontamination unit operation.
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Collazo, Cordero Cyrelys. "Novel preservation strategies for microbial decontamination of fresh-cut fruit and vegetables." Doctoral thesis, Universitat de Lleida, 2018. http://hdl.handle.net/10803/663375.
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La bioconservació, així com els mètodes químics i físics, es van avaluar per controlar patògens de transmissió alimentària en productes vegetals mínimament processats. La investigació dels mecanismes d'acció de Pseudomonas graminis CPA-7 va revelar que la seva activitat bioconservadora s'exerceix a través de la combinació de la competència, el deteriorament de les capacitats de colonització dels patògens i l'activació de la resposta defensiva de l'hoste vegetal. Com enfocament físic, es va avaluar la llum ultraviolada C acoblada a immersió (WUV), en aigua i en àcid peroxiacètic (PAA), per descontaminar vegetals mínimament processats. WUV va reduir la microbiota nativa i els patògens inoculats del bròquil i de verdures de fulla, així com va millorar les propietats bioactives del bròquil. Una altra tecnologia física avaluada per a la descontaminació del bròquil va ser la llum polsada, sense mostrar idoneïtat. Finalment, es va avaluar la combinació de WUV, PAA i CPA-7 per a la descontaminació de verdures de fulla, millorant sinergísticament l'efecte inhibidor sobre el creixement de Salmonella enterica depenent de la matriu. En resum, la biopreservació i l’aplicació de WUV són tecnologies prometedores, alternatives al clor, que actuen a través de múltiples mecanismes i es poden implementar per millorar la qualitat microbiològica i les propietats bioactives dels productes mínimament processats.La bioconservación, así como métodos químicos y físicos, se evaluaron para controlar patógenos transmitidos por los alimentos en productos vegetales mínimamente procesados. La investigación de los mecanismos de acción de Pseudomonas graminis (CPA-7) reveló que su actividad bioconservadora se ejerce a través de la combinación de la competencia, del deterioro de las capacidades de colonización de los patógenos y de la activación de la respuesta defensiva del hospedante vegetal. Como enfoque físico, se evaluó la luz ultravioleta C acoplada a inmersión (WUV), en agua y en ácido peroxiacético (PAA), para descontaminar vegetales mínimamente procesados. WUV redujo la microbiota nativa y los patógenos inoculados en brócoli y verduras de hoja, y además mejoró las propiedades bioactivas del brócoli. Otra tecnología física: la luz pulsada, se ensayó para la descontaminación del brócoli sin mostrar idoneidad. Finalmente, se evaluó la combinación de WUV, PAA y CPA-7 para la descontaminación de verduras de hoja. Esta estrategia mejoró sinergísticamente el efecto inhibidor de CPA-7 sobre el crecimiento de Salmonella enterica dependiendo de la matriz. En resumen, la biopreservación y la aplicación de WUV son tecnologías prometedoras, alternativas al cloro, que actúan a través de múltiples mecanismos y que pueden implementarse para mejorar la calidad microbiológica y bioactiva de los vegetales mínimamente procesados.
Biopreservation as well as chemical and physical methods were essayed to control foodborne pathogens in fresh-cut fruit and vegetables. The investigation of the action mechanisms of Pseudomonas graminis (CPA-7) revealed that its biopreservative activity is exerted through the combination of competition, the impairment of pathogen’s colonization abilities and the activation of the plant-host's defense response. As a physical approach, water-assisted UV-C (WUV) was evaluated, alone and combined with peroxyacetic acid (PAA), for the decontamination of fresh-cut vegetables. It was effective for reducing native microbiota and inoculated pathogens in fresh-cut broccoli and leafy greens, as well as for enhancing the bioactive content in broccoli. Another physical technology: pulsed light was essayed for decontamination of broccoli, showing no suitability. Finally, the combination of WUV, PAA and CPA-7 was evaluated for decontamination of leafy greens, showing a synergistic enhancement of the inhibitory effect of CPA-7 on S. enterica growth depending on the matrix. In summary, biopreservation and WUV are promising alternative-to-chlorine technologies, which act via multiple mechanisms, and can be implemented to improve the microbiological and nutritional quality of fresh-cut produce.
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Aronu, Ugochukwu Edwin. "Absorption Mats for Oil Decontamination- Towards Sustainable End-of-Life Tyre Management." Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-18555.
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It has become imperative globally that we build a more sustainable society. Part of the drive towards attaining this includes finding an environmentally friendly solution to materials we use including materials from automobile vehicles. This research is focused on finding a sustainable solution to end-of-life tyres through material recycling into useful products; in this case absorption mats for oil decontamination from tyre rubber granulate.The research consisted of two parts. Firstly, theoretical reviews which involved an extensive literature review of oil decontamination practice and methods of doing it. Review of tyre rubber granulate properties and consultations with experts/agencies involved in oil decontamination operations in Sweden where mostly physical methods such as use of absorbents on land and booms on water. The second component of the research is an experimental part which involved laboratory test of the absorption properties of tyre rubber granulate at University College of Borås (HB) in which granules of sizes 0.50, 1.00 and 2.00 mm were tested on different oil samples; gasoline, diesel and motor oils. Environmental properties tests were also conducted at the Swedish Technical Research Institute (SP) where metal and organic contents of the granules and its leachate were tested.Results from the study showed that tyre rubber granules have the ability to absorb different types of oil. It was found that factors such as exposure time, granulate size, temperature and type of oil have effect on the absorption capacity of granulate. Highest absorption (2.518 g/g) was experienced with the least viscous oil; gasoline. Absorption was found to increase with an increase in temperature and decrease in granulate size with the smallest granulate size (0.50 mm) having the highest absorption at 30oC. It was equally observed that the presence of water does not have significant effect on oil absorption by granulate. The results also showed that tyre rubber granules are quick absorbents; absorption rate was highest within 5 minutes.Environmental properties test on granulate indicated the presence of organics (PAHs, phthalates, phenols) and metals (Pb, Zn, Cr, Cd) in granulate and its leachate. PAHs content of the granules and its leachate exceeded the Swedish guideline. Metal content of the granules and its leachate were below the guideline value with the exception for zinc (Zn) which content in granules exceeded guideline value. It should be noted however that the test conditions are too extreme to be experienced under normal condition of use of granulate for oil decontamination.It is concluded that tyre rubber granulate can be developed into absorption mats for oil decontamination due to its good oils absorption properties and benefits to the society in solving two key environmental problems; oil spill and tyre waste problems. Equally the use of tyre granules for this application will not pose human health and/or environmental risk if used adequately.Uppsatsnivå: D
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Al-Saleh, Ibra. "Tracer-based decontamination approach for gas condensates contaminated with oil-based mud." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/2078.
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Snyder, Nathan. "Evaluation of a nontidal riparian wetland as a naturally occurring decontamination zone." Thesis, Virginia Tech, 1995. http://hdl.handle.net/10919/45067.
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The potential harmful effects of agricultural chemicals on human health and the Chesapeake Bay have led to the need to identify economical practices that limit the chemicals impact on surface and ground water contamination. The agricultural practices of the Atlantic Coastal Plain in Virginia have resulted in many bottom land areas of forests and wetlands being left uncultivated, while the upland areas are being utilized for intensive agriculture that may act as a source of chemicals in the environment. The capacity of a riparian wetland to act as a buffer zone between an intensively managed agricultural field, located in Westmoreland Co., Virginia, and a riparian stream that borders the field was investigated in this study.
The ground-water chemistry was evaluated using water samples from ground-water wells and the stream. Seventeen ground-water wells were installed and three surface-water sample locations were stablished. Samples were collected bi-weekly for an 18 month period. Samples were analyzed for nutrient and pesticide constituents. A tracer study was used, unsuccessfully, to determine flowrates at the study site. A ground-water model was used to estimate flowrates at the study site using measured site characteristics. Pesticides were not detected in samples. Results from this study revealed that the elevated levels of nitrate in ground-water, resulting from fertilizer application, were reduced by 48% by the riparian zone, from an average level of 9.0 mg/l in the agricultural field to an average level of 4.68 mg/l in the stream. Reductions of nitrate were as great as 57% between ground-water samples from the agricultural field and ground-water samples from the riparian wetlands.
The reduction in nitrate concentration was less than has previously been reported by other investigators, primarily due to differences in site characteristics. This study demonstrates the role that buffer zones along streams may play in reducing the influence of agricultural fertilizers on surface waters and the need to manage riparian forests as a beneficial part of the agroecosystem. The data collected from this study will aid in the proper design and implementation of riparian forest corridors as decontamination zones.Master of Science
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MARTIN, HARNAY PATRICIA. "Decontamination intestinale par la norfloxacine en reanimation : etude randomisee sur 65 malades." Lyon 1, 1992. http://www.theses.fr/1992LYO1M265.
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Buchanan, Glynn Dale. "Decontamination and use of endodontic hand files in dental practice in Pretoria." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/65863.
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The risk of cross-contamination validated the need to assess the adequacy of cleanliness of dental instruments following decontamination procedures. Neither the extent of single-use nor the efficacy of decontamination of endodontic hand files following routine cleaning and sterilisation procedures in South Africa was known. The first aim of this study was to determine the amount of visible debris left on endodontic hand files collected from dental practice in Pretoria, South Africa, following the application of routine decontamination procedures. Secondly, the study aimed to determine the prevalence and attitudes regarding the single-use of these instruments. Twenty-seven dental practices voluntarily took part in this study. Each participant was requested to submit 15 previously used and decontaminated endodontic hand files. A short questionnaire regarding the single-use of endodontic files was completed by participants. A coding system was used to guarantee the anonymity of the participants. Files were examined for the presence or absence of remnant debris using a stereomicroscope at ten and 40 times magnification. A novel scoring system was used to rate the position of the debris. Statistical evaluation of the data estimated the frequency and proportions of debris on the endodontic hand files, in each scoring position. Cohen’s Kappa statistic was used to assess the repeatability of the scoring system. Four hundred and one endodontic hand files were collected from 27 participants. It was found that 94% of the samples were contaminated with debris. Examiner agreement was found to be fair to moderate over the entire dataset. No participants reported practising the single-use of endodontic hand files. Great variation existed in the way that endodontic hand files were decontaminated. The primary reason provided by participants for the re-use of endodontic hand files was financial concerns regarding single-use protocols.Dissertation (MSc)--University of Pretoria, 2017.
Odontology
MSc
Unrestricted
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BEN, SLIMANE-TOURKI AMEL. "Decontamination des esters organophosphores au moyen de nouveaux nucleophiles en milieu micellaire." Paris 7, 1993. http://www.theses.fr/1993PA077016.
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La destruction chimique de toxines organophosphores paraoxon et parathion a ete realisee en milieu micellaire d'abord par l'emploi d'une nouvelle serie de nucleophiles a effet alpha et a fonction oxime, acide hydroxamique ou hydrazide renfermant un systeme cage, l'adamante, puis par des composes oxydants et/ou a chlore positif, et enfin, au moyen d'agents reducteurs tels que les borohydrures stables en milieux aqueux. En optimisant les conditions operatoires, des facteurs d'acceleration des reactions de destruction de 40 a 100 ont ete observes avec ces nouvelles structures, ce qui correspond a des temps de demi-reaction de l'ordre de 1 a 2 minutes au lieu de 40 minutes a plusieurs heures avec les decontaminants conventionnels
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Miller, Brendon Mark. "A Nanoparticle/enzyme System For The Simultaneous Detection And Decontamination Of Organophosphates." ScholarWorks @ UVM, 2016. http://scholarworks.uvm.edu/graddis/576.
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The need for a direct visual response system for the detection of organophosphorus compounds stems from the continued threat and use of these toxic agents in military and terrorist conflicts. The development of an enzyme-inhibitor triggered release system allows for direct visual detection with high specificity. Mesoporous silica nanoparticles (MSNs) have physical features that make them attractive as scaffolds for the construction of these systems, such as pore diameters (20-500 Á) that can be synthetically controlled, large surface areas (300-1500 m2g-1), large pore volumes, chemical inertness, stability at elevated temperatures, and surfaces that can be easily functionalized. In our studies, the dye Congo Red was loaded into the pores of MSNs, which were then capped by tethering an enzyme (organophosphorus hydrolase (OPH) or acetylcholinesterase (AChE)) to the external surfaces of MSNs through a competitive inhibitor (diethyl 4-aminobenzyl phosphonate (DEABP) or tacrine, respectively). OPH has been extensively studied for its ability to hydrolyze a wide range of organophosphorus compounds, rendering them non-toxic. AChE has been commonly used for organophosphate detection resulting from its sensitivity to phosphorylation. Upon addition of organophosphorus compounds to suspensions of the modified MSNs, the enzymes detached from the MSN surface, releasing the dye and providing a visual confirmation of organophosphate presence. Enzyme kinetics were studied using 31P NMR or UV-Visible spectroscopy; Congo Red release was also monitored by UV-Visible spectroscopy. The system was sensitive and specific for organophosphorus compounds both in phosphate-buffered saline and in human serum. The rate of dye release directly correlated with the rate of organophosphorus conversion for OPH and the rate of phosphorylation for AChE.