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Dissertations / Theses on the topic 'Chloraren'

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Published: 4 June 2021

Last updated: 15 February 2022

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Couture, Estelle. "Chlorate and chlorite analysis in seawater, chlorate sinks, and toxicity to phytoplankton." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0023/MQ36420.pdf.

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Jakobsson, Elsa. "Particle Removal from Chlorate Electrolyte." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59489.

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This master thesis project was carried out as a part of the chlorate research conducted at the Process RD&I department for bleaching chemicals at AkzoNobel Pulp and Performance Chemicals AB in Bohus. During the project already implemented filter cloths as well as new types of filters were studied and compared by experimental trials. The results were then examined in an attempt to evaluate existing filtration systems as well as investigate if there are other, better alternatives. The impurities found in a chlorate plant account for an efficiency loss in the process and a reduction of impurities would hence result in an energy reduction and a cleaner product. The trials were conducted at one of AkzoNobel’s chlorate plants. Six filters were studied and evaluated by measuring turbidity of the electrolyte and pressure over the filter during the experiments. Samples of the electrolyte were analyzed to obtain the metal content, and thereby the impurity content, of the electrolyte. The structures of the filters were studied by optical microscopy. The results from the trials show that all filter types except one, a needle felt filter, seem to be suitable for chlorate electrolyte filtration (including the filter types already used in the plants). The other filters all reach turbidity values below 0.1 FNU immediately or within 90 minutes of filtration, which is considered good enough. The results from the metal content analysis show a similar trend where the metal concentrations decrease to levels below the detection limits immediately or within 90 minutes of filtration. Apart from the lab trials performed some measurements were made on the existing filtration equipment in the chlorate plant. The measurements show varying results, partly similar to those achieved during the lab filter trials but also results showing a higher turbidity value and metal content, indicating that full scale operation are more complicated than lab scale operation. The lab trial results obtained with the filter types already used in the plants show that lower impurity content is possible to achieve. However, this would require closer monitoring of the filtration systems in the plants. Apart from the filtration trials, an attempt to determine the sizes of the particles present in the electrolyte using laser diffraction was performed. However, too little was known of the chlorate electrolyte’s optical data for the measurements to be reliable. Further work is needed before a method for size determination of the particles in a chlorate electrolyte can be achieved. Also, an Optical Filtration Test was tried on the electrolyte but was not sensitive enough for utilization on electrolyte with low (below 1 FNU) turbidity values. The project concluded that a switch to another filtration system is unmotivated, unless a change in the product requirements would occur. Since the impurities have proven to affect the efficiency of the process, it is recommended to make an effort into utilizing the filtration system to its full extent.

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Cornell, Ann. "Electrode reactions in the chlorate process." Doctoral thesis, KTH, Kemiteknik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3442.

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Hummelgård, Christine. "Nanoscaled Structures of Chlorate Producing Electrodes." Doctoral thesis, Mittuniversitetet, Institutionen för tillämpad naturvetenskap och design, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-17206.

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Sodium chlorate is mainly used for production of chlorine dioxide (a pulp bleaching agent). Sodium chlorate is produced by an electrochemical process where chloride ions (from sodium chloride dissolved in water) are oxidized to chlorine on the anodes and hydrogen is evolved on the cathodes. The anode of this process consists of a metal plate coated with a catalytically active metal oxide film. The electrocatalytic properties of the anode coating film have been widely investigated due to the great importance of these electrodes in the electrochemical industry. The material properties are, however, not as well investigated, and the studies described in this thesis are an attempt to remedy this. Several standard material characterization methods were used, such as SEM, TEM, AFM, EDX, XRD, porosimetry and DSC. Also, a novel model system based on spin coated electrode films on smooth substrates was developed. The model system provided a way to design samples suitable for e.g. TEM, where the sample thickness is limited to maximum of 100 nm. This is possible due to the ability to control the film thickness by the spinning velocity when using the spin coating technique. It was shown here that the anode coating has a nanostructure. It consists of grains, a few tens of nanometers across. The nanostructure leads to a large effective area and thus provides an explanation of the superior catalytic properties of these coatings. The grains were also shown to be monocrystalline. The size of these grains and its origin was investigated. The calcination temperature, the precursor salt and (if any) doping material all affected the grain size. A higher calcination temperature yielded larger grains and doping with cobalt resulted in smaller grains and therefore a larger real area of the coating. Some preparation conditions also affected the microstructure of the coating; such as substrate roughness. The microstructure is for example the cracked-mud structure. A smoother substrate gave a lower crack density. The cathode of chlorate production is usually an uncoated metal plate, therefore 'less catalytically active'. It is, however, possible to activate the cathode by for example in situ additions to the electrolyte. It was shown here that sufficient addition of molybdate to the electrolyte resulted in a molybdenum film deposited on the cathode and thereby an increase of its surface area and an activation the hydrogen evolution reaction.

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Smedja, Bäcklund Anna. "Electron transport in microbial chlorate respiration." Licentiate thesis, Karlstad University, Faculty of Technology and Science, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-3777.

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Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. Microbial respiration of oxochlorates is important for biotreatment of effluent from industries where oxochlorates are produced or handled. One of these species, the Gram-negative Ideonella dechloratans, is able to reduce chlorate but not perchlorate. Two soluble enzymes, chlorate reductase and chlorite dismutase, participate in the conversion of chlorate into chloride and molecular oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase. Soluble c cytochromes were investigated for their ability to serve as electron donors to chlorate reductase. The results show that a 6 kDa c cytochrome serves as electron donor for chlorate reductase. This cytochrome also serves as electron donor for a terminal oxidase in the reduction of oxygen that is produced in the course of chlorate respiration. A gene encoding a soluble c cytochrome was found in close proximity to the gene cluster for chlorate reduction. This gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.

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Smedja, Bäcklund Anna. "Electron transport in microbial chlorate respiration /." Karlstad : Faculty of Technology and Science, Chemistry, Karlstads University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-3777.

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Hellberg, Lindqvist Miriam. "Oxygen-dependent regulation of key components in microbial chlorate respiration." Doctoral thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-40698.

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Contamination of perchlorate and chlorate in nature is primarily the result of various industrial processes. The microbial respiration of these oxyanions of chlorine plays a major role in reducing the society’s impact on the environment. The focus with this thesis is to investigate the oxygen-dependent regulation of key components involved in the chlorate respiration in the gram‑negative bacterium Ideonella dechloratans. Chlorate metabolism is based on the action of the enzymes chlorate reductase and chlorite dismutase and results in the end products molecular oxygen and chloride ion. Up‑regulation of chlorite dismutase activity in the absence of oxygen is demonstrated to occur at the transcriptional level, with the participation of the transcriptional fumarate and nitrate reduction regulator (FNR). Also, the chlorate reductase enzyme was shown to be regulated at the transcriptional level with the possible involvement of additional regulating mechanisms as well. Interestingly, the corresponding chlorate reductase operon was found to be part of a polycistronic mRNA which also comprises the gene for a cytochrome c and a putative transcriptional regulator protein.

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Bohlin, Jan. "Enzymes and electron transport in microbial chlorate respiration." Doctoral thesis, Karlstad : Faculty of Technology and Science, Chemistry, Karlstads University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-2805.

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Smedja, Bäcklund Anna. "c Cytochromes as Electron Carriers in Microbial Chlorate Respiration." Doctoral thesis, Karlstads universitet, Avdelningen för kemi och biomedicinsk vetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-8038.

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Microbial respiration of oxochlorates is important for the biotreatment of effluents from industries where oxochlorates are produced or handled. Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase, in the gram-negative bacterium Ideonella dechloratans. Both chlorate reductase and the terminal oxidase of I. dechloratans were found to utilize soluble c cytochromes as electron donors. For further investigation, two major heme-containing components were purified and characterized. The most abundant was a 9 kDa c-type cytochrome (class I), denoted cytochrome c-Id1. This protein was shown to serve as electron donor for both chlorate reductase, and for a terminal oxidase. The other major component was a 55 kDa homotetrameric cytochrome c', (class II). A function for this cytochrome could not be demonstrated but it does not appear to serve as electron donor to chlorate reductase. A gene predicted to encode a soluble c cytochrome was found in close proximity to the gene cluster for chlorate reduction. The predicted sequence did not match any of the cytochromes discussed above. The gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.

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Nylén, Linda. "Critical potential and oxygen evolution of the chlorate anode." Licentiate thesis, KTH, Chemical Engineering and Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3957.

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In the chlorate process, natural convection arises thanks to the hydrogen evolving cathode. This increases the mass transport of the different species in the chlorate electrolyte. There is a strong connection between mass transport and the kinetics of the electrode reactions. A better knowledge about these phenomena and their interactions is desirable in order to understand e.g. the reasons for deactivation of anode coatings and what process conditions give the longest lifetime and the highest efficiency.One of the aims of his work was to understand how the chlorate process has to be run to avoid exceeding the critical anode potential (Ecr) in order to keep the potential losses low and to achieve a long lifetime of the DSAs. At Ecr anodic polarisation curves in chlorate electrolyte bend to higher Tafel slopes, causing increasing potential losses and accelerated ageing of the anode. Therefore the impact on the anode potential and on Ecr of different electrolyte parameters and electrolyte impurities was investigated. Additionally, the work aimed to investigate the impact of an addition of chromate on oxygen evolution and concentration profiles under conditions reminiscent of those in the chlorate process (high ionic strength, 70 °C, ruthenium based DSA, neutral pH), but without chloride in order to avoid hypochlorite formation. For this purpose a model, taking into account mass transport as well as potential- and concentration-dependent electrode reactions and homogeneous reactions was developed. Water oxidation is one of the side reactions considered to decrease the current efficiency in chlorate production. The results from the study increase the understanding of how a buffer/weak base affects a pH dependent electrode reaction in a pH neutral electrolyte in general. This could also throw light on the link between electrode reactions and homogeneous reactions in the chlorate process.It was found that the mechanism for chloride oxidation is likely to be the same for potentials below Ecr as well as for potentials above Ecr. This was based on the fact that the apparent reaction order as well as αa seem to be of the same values even if the anode potential exceeds Ecr. The reason for the higher slope of the polarisation curve above Ecr could then be a potential dependent deactivation of the active sites. Deactivation of active ruthenium sites could occur if ruthenium in a higher oxidation state were inactive for chloride oxidation.Concentration gradients of H+, OH-, CrO4 2- and HCrO4 - during oxygen evolution on a rotating disk electrode (RDE) were predicted by simulations. The pH dependent currents at varying potentials calculated by the model were verified in experiments. It was found that an important part of the chromate buffering effect at high current densities occurs in a thin (in the order of nanometers) reaction layer at the anode. From comparisons between the model and experiments a reaction for the chromate buffering has been proposed. Under conditions with bulk pH and chromate concentration similar to those in the chlorate process, the simulations show that the current density for oxygen evolution from OH- would be approximately 0.1 kA m-2, which corresponds to about 3% of the total current in chlorate production.

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Nylén, Linda. "Critical potential and oxygen evolution of the chlorate anode /." Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3957.

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Steven, Barbara. "Isolation and characterisation of chlorate resistant mutants of barley." Thesis, University of St Andrews, 1986. http://hdl.handle.net/10023/2910.

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The object of this study has been to characterise barley mutants which lack the functional nitrate reductase (NR) enzyme system. In the long term it is hoped that such studies will lead to improved nitrate utilisation and ultimately to improved quality barley protein. The progeny of nine chlorate resistant selections, in the barley cultivars Mavis Mink and Golden Promise, were studied. Four (R9201, R11301, R12202 and R12801) lacked NADH-NR and FMNH2-NR activities, the rest had the NR+ phenotype. None of the four were nitrate uptake mutants since they all possesed wild type or greater levels of nitrate. R9201, R11301 and the previously characterised R9401 (Bright et al, 1983) were not molybdenum uptake or Mo-accumulation mutants. R9201, R11301 and R12202 lacked xanthine dehydrogenase (XDH) (an enzyme which contains the same molybdenum-containing cofactor, MoCo) activity suggesting that these lines have defective MoCo's, whilst R12801 possessed XDH activity indicating that it might have defective apoprotein subunits. These four lines are similar to R9401 since they lack "NR activity and are unlike other previously selected ' barley NR mutants (Kleinhofs ' et al, 1980) which are leaky and possess up to 5% of the wild type (cv. Steptoe) in vitro NR activity. R9201 and R11301, like R9401, were all caused by single recessive nuclear gene mutations. The MoCo mutants, R9201, R9401, R11301 and R12202, could be divided into two groups on the basis of i) allelism, ii) presence or absence of wild type levels of dimeric NR and iii) the ability of their extracted MoCo's to reconstitute NADPH-NR in an extract of N. crassa nitl mutant (which supplies NR monomers) in the presence of excess molybdate. R11301 is not allelic to R9201, whilst R9201 and R9401 are allelic. R9401 is also thought to be allelic to Az 34, a barley MoCo mutant isolated and characterised by Kleinhofs et al (1980). Az 34 has been designated nar2a and it is proposed that the allelic R9401 and R9201 should be classified as nar2b and nar2c respectively. It is possible that R11301 is either allelic with one of the other barley MoCo lines, nar3, nar4 or it is defective in a different MoCo gene. The same is also true for R12202. R11301 was shown to possess inactive NR dimer at wild type concentrations, whilst R9201, R9401 and R12202 had little or no NR (inactive dimer) present under these conditions. R12801 possessed no dimer. The MoCo extracted from R11301 was able to reconstitute the same level of NADPH-NR in the Hill extract as MoCo extracted from-the wild types. R9201, R9401 and R12202 lacked this ability.

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Garcia, Jorge David S. M. Massachusetts Institute of Technology. "Sodium chlorate oxygen generation for fuel cell power systems." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112489.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 95-97). In this thesis we experimentally investigated the use of sodium chlorate as an oxygen storage medium for use in underwater fuel cell power systems. Research into improving hydrogen storage systems is the primary concern when designing fuel cell systems with access to atmospheric oxygen. However, in an underwater environment, performance of the oxygen storage system cannot be overlooked. Oxygen candles using sodium chlorate offer gravimetric storage densities similar to compressed gas storage while also offering volumetric storage densities greater than both gas and cryogenic liquid oxygen storage. Unfortunately, this technology does not allow for controllable rates of oxygen production and is known to cause fires and occasionally explosions when contaminated with organic materials or exposed to external sources of heat. Though useful as an emergency source of oxygen, sodium chlorate will not be viable for use in power systems until safer and more controllable methods of releasing its oxygen are implemented. During this project we developed a batch method for releasing oxygen from sodium chlorate. Two grams of sodium chlorate with nanoscale cobalt oxide catalyst were loaded into a reaction chamber and heated until decomposition. Afterwards a piston was used to eject the materials from the reaction chamber. This method proved to be safer and more reliable than similar chlorate-based oxygen systems as the primary modes of failure, those associated with the buildup of solid residue at the inlets and exits of the reaction chamber, were removed. Aside from preventing the flow of oxygen to a fuel cell, the over-pressurization caused by these problems could compromise the reaction chamber and potentially result in catastrophic failures. The achieved rate of oxygen production, 0.21 L/min with a heating rate between 25 W and 33 W, was below the target 1.13 L/min needed to operate a 200 W PEM fuel cell. Further assessment of this method will require the use of a more active cobalt oxide catalyst, a system with a larger reaction chamber capable of decomposing increased amounts sodium chlorate per cycle and a reduction in heat losses through the use of improved insulation and thermal isolation techniques. by Jorge David Garcia. S.M.

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Kalu, Eric Egwu. "Simultaneous electrosynthesis of alkaline hydrogen peroxide and sodium chlorate." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28391.

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Simultaneous electrosynthesis of alkaline hydrogen peroxide and sodium chlorate in the same cell was investigated. The alkaline hydrogen peroxide was obtained by the electroreduction of oxygen in NaOH on a fixed carbon bed while the chlorate was obtained by the reaction of anodic electrogenerated hypochlorite and hypochlorous acid in an external reactor. An anion membrane, protected on the anode side with an asbestos diaphragm was used as the separator between the two chambers of the cell. The effects of superficial current density (1.2 - 2.4 kA m⁻²), sodium hydroxide concentration (0.5 - 2.0 M) and catholyte flow (0.1 x 10⁻⁶ - 0.5 x 10⁻⁶ m³ s⁻¹) on the chlorate and peroxide current efficiencies were measured. The effect of peroxy to hydroxy mole ratio on the chlorate current efficiency was measured too. The cell was operated at fixed anolyte flow of 2.0 x 10⁻⁶ m³ s⁻¹, inlet and outlet temperatures of 27/33°C (anode side), 20/29°C (cathode side), cell voltages of 3.0 - 4.2 V (current density of 1.2 - 2.4 kA -m⁻²) and a fixed temperature of 70°C in the anolyte tank. Depending on the conditions, alkaline peroxide solution and sodium chlorate were cogenerated at peroxide current efficiency between 20% and 86%, chlorate current efficiency between 51.0% and 80.6% and peroxide concentration ranging from 0.069 M to 0.80 M. The cogeneration of the two chemicals was carried out at both concentrated (2.4 - 2.8 M) and dilute (0 - 0.5 M) chlorate solutions. A relative improvement on the current efficiencies at concentrated chlorate was observed. A chloride balance indicated negligible chloride loss to the catholyte. The results are interpreted in terms of the electrochemical and chemical kinetics and the hydrodynamics of the cell . Applied Science, Faculty of Chemical and Biological Engineering, Department of Graduate

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ZEHNER, FABRICE. "Intoxication par le chlorate de soude : a propos d'une observation." Toulouse 3, 1988. http://www.theses.fr/1988TOU31289.

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Obijeski, Todd James. "The effect of silver catalyst on the chloride-chlorate reaction." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/10193.

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Feldman, Kenneth A. "Isolation and characterization of chlorate-resistant mutants in Arabidopsis thaliana /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260135358163.

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Indu, Bhart. "Kinetics and mechanism of methanol-chlorate reaction in the formation of chlorine dioxide." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/10956.

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Woodward, Emma Louise. "Crosstalk of lysosomes, autophagy and apoptosis in dioxin-induced chloracne in vitro." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3849.

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Chloracne is a hyperkeratotic acneform skin disease caused by exposure to 2,3,7,8-tetrachlorodibenzo–p-dioxin (TCDD), a potent agonist of the aryl-hydrocarbon receptor (AhR). Despite the known role of TCDD exposure in the pathogenesis of chloracne, the molecular mechanisms mediating the disease remain poorly defined. Using a previously optimised in vitro primary human keratinocyte epidermal equivalent model, we demonstrated the temporal regulation and development of a significantly reduced viable cell layer and compacted stratum corneum over 7 days with 10nM TCDD. These morphological changes were paralleled by cumulative AhR protein degradation and increased mRNA levels of CYP1A1. One of the key findings was a significant increase in the expression of the apoptotic marker, caspase-3 whilst there was no significant effect on Ki67 staining. Furthermore, TCDD treatment caused de-regulated epidermal differentiation as evidenced by increased mRNA expression but decreased protein expression of late differentiation markers. Treatment with TCDD also resulted in an induction of LC3 lipidation and endogenous LC3 protein expression as well as decreased P62 protein expression, well-established markers of autophagy induction. Interestingly, co-treatment of epidermal equivalents with TCDD and the lysosomal inhibitor, bafilomycin or cathepsin D inhibition (by pepstatin A or shRNA knockdown) resulted in restoration of the viable cell layer and reduction in TCDD-induced caspase-3 expression. Similar results were also seen after blockade of the autophagy pathway by ATG7 knockdown. Results also demonstrated lysosomal function and autophagy are required for TCDD-induced AhR degradation, indicating a potential role for chaperone-mediated autophagy. Collectively these data suggest exposure to TCDD results in deregulated epidermal differentiation, induction of autophagy, reduction of a viable cell layer and caspase-3 dependent cell death, likely mediated via lysosomal processing. Results provide an insight into the pathophysiology of chloracne, and demonstrate novel findings including TCDD-induced autophagy and potential role of lysosomal function in TCDD-induced death and AhR degradation.

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Byrne, Philip. "Mathematical modelling and experimental simulation of chlorate and chlor-alkali cells." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3182.

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Ledder, Tracey. "Comparison of ion chromatography and flow injection analysis methods for monitoring chlorite and chlorate ions in drinking water." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-03172010-020312/.

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Burke, Michael A. "Kinetics of the chlorate-hydrogen peroxide reaction in the formation of chlorine dioxide." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/11817.

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McReynolds, Jackson Lee. "The effects of an experimental chlorate product on the microbial ecology in Gallus gallus var. domesticus." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/544.

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Previous reports have shown that some bacteria utilize a dissimilatory nitrate reductase enzyme (NR) in anaerobic environments. This enzyme reduces nitrate to nitrite and also has been shown to co-metabolize chlorate to cytotoxic chlorite. A commercially available competitive exclusion (CE) product was evaluated for its nitrate reductase activity and therefore its experimental chlorate product (ECP) sensitivity. Of the 29 constituent bacteria of the CE culture, 11 had slight utilization of NR, 3 had moderate utilization of NR; the remaining were NR negative (with slight and moderate utilization: >0.1 to < 1.0 mM and > 1.0 mM nitrate utilized within 6 h, respectively). In vivo studies utilizing CE and ECP showed significant reductions in Salmonella. Although some of the bacteria were affected by ECP, the combined effect of the CE culture and ECP were effective in reducing Salmonella. Clostridium perfringens (CP) is a pathogen in the commercial poultry industry, which is the etiologic agent of necrotic enteritis (NE). Day-of-hatch broilers were fed a wheat diet and assigned to the following groups: control, commercial coccidia vaccine, commercial bursal disease vaccine, or the combination of the two, and challenged with CP in order to develop a disease model. Broilers in each treatment group had significant increases (P≤ 0.05) in lesion scores, mortality, and CP incidence. As pressure mounts for discontinuing the use of antibiotics in the agriculture industry, it is important to develop new strategies to combat these costly enteric pathogens. In vitro investigations evaluated a mixed gut culture with CP and the ECP at 5 mM or a 10 mM concentrations, over time. By 3 h there was a reduction (P≤ 0.05) in the 5 mM ECP and 10 mM ECP treatment groups. In vivo studies showed significant reductions in the incidence of CP and populations of intrinsic E. coli in all of the chickens provided ECP in the drinking water. Birds administered ECP in the feed showed significant reductions in lesion scores, incidence of CP and also had reduced E. coli log10 values. These results show that an ECP could provide the industry with a new management tool for controlling NE.

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Desai, Unmesh Jeetendra. "Comparative Analytical Methods for the Measurment of Chlorine Dioxide." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34134.

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Four commercially available methods used for the analysis of low-level Chlorine Dioxide (ClO2) concentrations in drinking water were evaluated for accuracy and precision and ranked according to cost, efficiency and ease of the methods under several conditions that might be encountered at water treatment plants. The different analytical methods included: 1.The DPD (N, N-diethyl-p-phenylenediamine) method 2.Lissamine Green B (LGB) wet-chemical method 3.PalintestÂ® kit LGB 4.Amperometric titration All these tests were performed with standard 1.0 mg/L ClO2 either alone or in the presence of different chlorine species, including chlorite ion (ClO2-, 0.5 mg/L), chlorate ion (ClO3-, 0.5 mg/L) and chlorine (Cl2, 1.0 mg/L). The tests were performed with four different matrices, with different concentrations of 0.1 mg/L ClO2, 0.5 mg/L ClO2 and 1.0 mg/L ClO2 at a constant temperature of 20oC and at different temperatures of 0oC, 10oC and 20oC at a fixed ClO2 concentration of 1.0 mg/L. None of the four methods produced the desired level of either accuracy or precision. For all four methods, interference to the measured ClO2 concentration from the addition of ClO2-, ClO3-, and Cl2 was minimal when the methods were performed according to specifications. The PalintestÂ® was the best all-round method because it was easy to perform, performed well at all concentrations tested, and its colored product was stable. The HACHÂ® DPD method was also easy to perform and gave the best results when measuring concentrations of 1.0 mg/L ClO2. The DPD method was less accurate than the PalintestÂ® at lower concentrations. The DPD colored product that formed upon reaction of ClO2 and DPD was unstable, making it necessary to measure the intensity of the colored product at exactly 1 minute. The amperometric titration and lissamine green methods were more cumbersome and time-consuming to perform than either the DPD or PalintestÂ® methods; for this reason they are less desirable for routine use. Master of Science

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Nylén, Linda. "Influence of the electrolyte on the electrode reactions in the chlorate process." Doctoral thesis, KTH, Tillämpad elektrokemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4681.

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The chlorate process is very energy intensive and a major part of the production costs are for electrical energy. Since the electricity prices are constantly increasing and may also vary periodically, the chlorate plants may be forced to adjust their production rate to the price at each moment in order to minimise their costs. Variation of current load requires increased knowledge regarding the electrode behaviour in a wide current range. In this thesis, the aim was to study the impact of the electrolyte on the electrode reactions in order to reduce the energy consumption. The work has mainly been experimental and additionally mathematical modelling has been carried out. A wide current range has been investigated in order to increase the understanding of the phenomena and to obtain results useful for low-load operation during the periods of high electricity cost. To operate the anode as energy efficiently as possible, the anode potential should not exceed the critical potential (Ecr), where the slope of the anodic polarisation curve increases, most likely due to ruthenium(VIII)-formation, and where the side reaction of oxygen evolution increases. In this work, the influence of different electrolyte parameters on Ecr has been studied. It was shown that a higher chloride concentration and an increased temperature lowered Ecr, which was expected to increase the risk of exceeding Ecr. However, this was not observed due to a simultaneous favouring of the chloride oxidation. Hence it was concluded that the electrolyte parameters should be optimised so that the lowest possible anode potential is obtained, which would enable higher current densities without exceeding Ecr. A further conclusion is that the increased slope of the polarisation curve at Ecr was possibly related to the lower activity for chloride oxidation on ruthenium oxidised to ruthenium(VIII). At full-load operation, the cathode potential was shown to be rather independent of the electrolyte composition despite a large variation of electrolyte parameters. The cathode composition appears to be more critical than the electrolyte composition when aiming at reducing the energy consumption. A strategy to increase the cathode activity could be to in situ apply a catalytic film onto the electrode surface. Therefore, Y(III) was added to a chloride electrolyte in order to form a yttrium hydroxide film on the alkaline cathode surface during hydrogen evolution. The yttrium-hydroxide film activated reduction of water (hydrogen evolution) and hindered hypochlorite reduction, proton reduction and nitrate reduction. The inhibiting properties are important for the prevention of side reactions, which currently are avoided by reducing Cr(VI) of the electrolyte on the cathode, producing an inhibiting chromium-hydroxide film. The studies on Y(III) increase the expectations for finding alternatives to the toxic Cr(VI). The addition of chromate to the chlorate electrolyte gives a high cathodic current efficiency and chromate has buffering properties in the electrolyte. The role of the buffer has been investigated for the oxygen evolution from water (one possible anodic side reaction), as well as cathodic hydrogen evolution. Models have been developed for these systems to increase the understanding of the interaction between buffer, electrode reactions and mass transport; the results have been verified experimentally. The chromate buffer increased the limiting current significantly for the cathodic H+ reduction and the cathodic overpotential was reduced drastically at currents lower than the limited current. A too low overpotential could result in the cathodic protection being lost. The presence of chromate buffer increased the limiting current for the oxygen evolution from OH-. The modelling of these systems revealed that the homogeneous reactions connected to the electrode reactions were not in equilibrium at the electrode surface. Further, a good resolution of the interface at the electrode surface was crucial since the, for the electrode reactions, important buffering takes place in an nm-thick reaction layer. Framställning av klorat är mycket energiintensiv och kräver stora mängder elenergi. Stigande elpriser, som dessutom ofta varierar under dygnet eller säsongsvis, gör att man vill reducera onödiga förluster samt ibland försöka anpassa produktionen så att man när elpriset är högt minskar den, för att sedan öka produktionen igen då elpriset sjunker. Denna flexibla drift kräver ny kunskap om hur elektroderna beter sig i ett större strömintervall än vad som tidigare varit av intresse. Målet med detta arbete var att, med fokus på elektrolytens betydelse, identifiera möjliga förbättringar för kloratprocessen och därmed minska energiförbrukningen. Studierna har i huvudsak varit experimentella men även matematisk modellering har använts. Ett brett strömintervall har undersökts för att bättre förstå fenomenen och för att även kunna använda resultaten då höga elpriser gör att man vill köra processen vid lägre laster än normalt. För att driften av anoden ska vara så energieffektiv som möjligt bör anodpotentialen inte överskrida den kritiska potentialen (Ecr), där den anodiska polarisationskurvan får en högre lutning (troligtvis pga Ru(VIII)-bildning) och bireaktionen syrgasutveckling ökar. I detta arbete har påverkan av olika elektrolytparametrar på Ecr undersökts. Det visade sig att en ökad kloridkoncentration och ökad temperatur sänkte Ecr. Trots att detta borde göra att Ecr lättare överskrids, blev inte detta fallet eftersom kloridoxidationen samtidigt gynnades. Slutsatsen blir därför att elektrolytparametrarna bör optimeras så att lägsta möjliga anodpotential uppnås, vilket då även gör att strömtätheten kan ökas utan att Ecr överskrids. Slutsatsen är vidare att polarisationskurvans högre lutning vid Ecr kan ha att göra med att rutenium oxiderat till rutenium(VIII) har lägre aktivitet för kloridoxidation. Vid full last visade sig katodens potential vara relativt oberoende av elektrolytsammansättningen trots att denna varierades kraftigt. Katodens sammansättning verkar vara viktigare att ta hänsyn till än elektrolytens för kunna åstadkomma en större energibesparing. Ett alternativ till att öka katodens aktivitet skulle vara att in-situ belägga elektrodytan med en katalytisk film. Försök gjordes att sätta till Y(III) till kloridelektrolyt för att under vätgasutveckling fälla ut en yttriumhydroxidfilm på den alkaliska katodytan. Yttriumhydroxidfilmen aktiverade vattenreduktion (vätgasutveckling) och inhiberade hypokloritreduktion, protonreduktion och nitratreduktion. De inhiberande egenskaperna är viktiga för att förhindra bireaktioner, vilka idag hindras av att Cr(VI) i elektrolyten reduceras på katoden och bildar en hindrande kromhydroxidfilm. Försöken med Y(III) visar att det finns goda möjligheter att hitta alternativ till det miljöfarliga Cr(VI). Kromattillsatsen i kloratelektrolyt ger förutom ett högt katodiskt strömutbyte även en buffrande effekt till elektrolyten. Effekten av buffert har undersökts för en av de anodiska bireaktionerna, syrgasutveckling ur vatten, samt för vätgasutvecklingen på katoden. Dessa system har modellerats för att bättre förstå samspelet mellan buffert, elektrodreaktioner och materietransport och resultaten har verifierats experimentellt. Kromatbufferten ökade gränsströmmen för katodisk H+-reduktion betydligt och katodöverpotentialen sjönk kraftigt vid lägre strömmar än gränsströmmen. Detta kan vara ett problem om överpotentialen sjunker så lågt att elektroden inte är katodiskt skyddad. För syrgasutvecklingen ökade närvaron av kromatbuffert gränsströmmen för syrgasutveckling ur OH-. Modellering av dessa system visar att de homogena reaktioner som var kopplade till elektrodreaktionerna inte var i jämvikt vid elektrodytan. Vidare visade det sig vara mycket viktigt med en bra upplösning av gränsskiktet vid elektrodytan, då den buffring som är viktig för elektrodreaktionerna sker i ett mycket tunt reaktionsskikt (nanometertjockt). QC 20100901

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Wojciechowski, Krzysztof. "Studies of the growth kinetics and habit modification of sodium chlorate crystals." Thesis, University of Strathclyde, 1989. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21966.

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The thesis describes the results of studies on the morphology, growth kinetics and defect structure of sodium chlorate crystals grown from aqueous solutions at temperatures near the ambient. For the investigation of the growth morphology and habit modification of the crystals as a function of supersaturation and concentration of Na₂S₂0₆·2H₂0 impurity, experimental data on the morphological importance of different faces were supplemented by examination of the surface topography, the dislocation structure land changes in the lattice parameter of the crystals. The results showed that the habit of the crystals grown from pure solutions is cubic at high supersaturations, while it is cuboid with relatively small {110} and {111} faces at low supersaturations. Optical examination of the as-grown surfaces did not reveal the presence of growth spirals or hillocks, but screw, edge and mixed dislocations were identified by Lang topography at both low and high values of supersaturations (undercooling). Addition of the impurity to the growth solution led to the development of tetrahedral faces with randomly situated hillocks of different sizes at the expense of cubic faces, and to an increase in the lattice parameter of the grown crystals. The influence of the impurity was also studied on the nucleation kinetics of the compound. Effects of applied supersaturation on the regeneration process at the seed and the dislocation structure at the seed-crystal interface, and of the strain, applied externally on large crystals and inherently present in small crystals of dimensions 50 - 150 µm, on growth rates were investigated by using X-ray diffraction topography. It was found that the strain generated at the newly-grown interface and the numerical density of dislocations formed therefrom increase with the value of the supersaturation used for the refacetting process. It was unequivocally established that the growth rates of crystals decrease with an increase in the strain applied externally on large crystals and inherently present in small crystals.

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Schindler, Manon. "Deracémisation du chlorate de sodium avec et sans l’influence du dithionate de sodium." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR004.

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Dans le domaine pharmaceutique, la séparation des énantiomères est souvent effectuée par des méthodes de cristallisation. L’avantage de la déracémisation est la possibilité d’obtenir un rendement théorique de 100% grâce à la conversion du contre énantiomère en l’énantiomère désiré en solution. Le mécanisme de la déracémisation par cycles de température (TCID), a été étudié dans ce manuscrit. Les recherches se sont concentrées sur le développement d’un procédé de TCID pour NaClO3. Ce composé modèle pour la déracémisation est achiral à l’état solvate, ce qui permet de se focaliser sur les mécanismes de cristallisation impliqués dans le procédé de déracémisation. Après la caractérisation complète de l’état solide de Na2S2O6, ce composé a été utilisé comme une impureté nonchirale dans le procédé de TCID du NaClO3 et a permis de mettre en évidence le rôle important de la nucléation secondaire dans le procédé. Ainsi, le succès du TCID dépend d’un bon équilibre entre la croissance des cristaux et la nucléation secondaire. A des fins industrielles, les réacteurs du type Couette Taylor sont des appareils prometteurs pour le développement de procédés de déracémisation en continu. Les premiers tests de déracémisation réalisés dans ce type de réacteur ont montré que la brisure de symétrie et la déracémisation du NaClO3 ont été réalisés avec succès. Néanmoins, le ≪ recyclage de cristaux ≫, soit par attrition soit par la nucléation secondaire, doit être amélioré pour obtenir un procédé de déracémisation plus performant avant de considérer l’implémentation d’un procédé en continu In the field of pharmaceutical chemistry, crystallization based methods are used to obtain pure enantiomers. The advantage of deracemization is the conversion of the unwanted enantiomer into the desired enantiomer by means of racemization in liquid phase, giving rise to a theoretical yield of 100%. The mechanism of Temperature Cycling Induced Deracemization (TCID) process, still matter of debate, has been investigated in this thesis. Research was focused on the development of the TCID process for sodium chlorate (NaClO3). This model compound is achiral at the solvated state which enables to focus investigation on crystallization mechanisms involved during deracemization. After the full solid state characterization of sodium dithionate (Na2S2O6), this compound has been used as a nonchiral impurity in the TCID process of NaClO3 and highlighted the key role of secondary nucleation in the process. Thus, the success of the TCID process depends on the right balance between growth and secondary nucleation. From an industrial perspective, the Couette Taylor reactor has been considered as a promising device for the development of continuous deracemization process. Attempts to deracemize NaClO3 in this kind of reactor showed that symmetry breaking and deracemization of NaClO3 were successful. Nonetheless, crystal recycling, via either attrition or secondary nucleation, has to be improved to enhance deracemization process before considering the execution of continuous process

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Ellenberger, Christine Spada. "Water Quality Impacts of Pure Chlorine Dioxide Pretreatment at the Roanoke County (Virginia) Water Treatment Plant." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/30807.

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Chlorine dioxide (ClO₂) was included in the Spring Hollow Water Treatment Plant (Roanoke County, Virginia) to oxidize manganese and iron, prevent tastes and odors, and avoid the formation of excessive halogenated disinfection by-products. A state-of-the-art, gas:solid ClO₂ generation system manufactured by CDG Technology, Inc. was installed at the plant and is the first full-scale use of this technology in the world. The ClO₂ generator produces a feed stream free of chlorine, chlorite ion (ClO₂⁻), and chlorate ion (ClO₃⁻), resulting in lower by-product concentrations in the treatment system The objectives of this project were to study ClO₂ persistence and by-product concentrations throughout the treatment plant and distribution system and to evaluate granular activated carbon (GAC) columns for removing ClO₂⁻ from the finished water. The ClO₂ dosages applied during this study were relatively low (<0.75 mg/L), and, as a result, ClO₂⁻ concentrations never approached the maximum contaminant level (MCL) (1.0 mg/L). Likewise, the plant effluent ClO₂ concentration never approached the maximum residual disinfectant level (MRDL) (0.80 mg/L), but concentrations as high as 0.15 mg/L reformed in the distribution system by ClO₂⁻ reaction with chlorine. Chlorate ion was monitored despite the fact that no ClO₃⁻ MCL has been proposed, and concentrations were quite low (never greater than 0.10 mg/L) throughout the treatment plant and in the distribution system. The reasons for the low concentrations are that ClO₃⁻ is not produced by the gas-solid generator used at the facility and ClO₂⁻ concentrations in the clearwell prior to chlorination were uniformly low. The average ClO₂⁻ reduction upon passage of treated water through the GAC contactor was approximately 64 percent, but the GAC effectiveness was declining over the six-month study period. Apparently, GAC effectiveness, as shown by others, is short-lived, and if higher ClO₂ dosages are ever applied at the Roanoke County facility, the ClO₂⁻ concentrations will have to be reduced by either ferrous coagulants or reduced-sulfur compounds. Regenerated ClO₂ concentrations in the distribution system were below 0.2 mg/L, but concentrations as low as 0.03 mg/L were found at homes of customers who complained of odors. During this study, twelve complaints were received from eight customers, and each complainant had recently installed new carpeting, which has been shown to contribute volatile organics that react with ClO₂ to produce odors similar to kerosene and cat urine. While meeting the Cl₂ MCL likely will be no problem if the ClO₂ dose at the plant remains below 1.0 mg/L, the problem of offensive odors in the distribution system will likely continue as long as any ClO₂ is in the finished water when chlorine is present. Master of Science

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Lan, Zhipeng. "The structural role of sodium dithionate impurity in the habit modification of sodium chlorate single crystals." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/6311/.

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A detailed study into the crystal habit modification of the NaClO3 / Na2S2O6 (host / impurity) system is presented. Ordinary morphology of NaClO3 present faces of {001}, {110} and {111} types. The presence of impurity Na2S2O6 has led to rapid development of new faces of {111} type on the NaClO3 crystals grown from solution. Above 70ppm doping concentration, the morphology of NaClO3 crystal is dominated by {111} faces. Crystal twinning occurred under 800ppm doping concentration and above. X-ray topography was used to investigate the growth history and defect configuration of the pure and doped crystals. Lattice distortions at various lattice planes within the pure and doped crystals were determined using X-ray multiple-wave diffraction (XRMD). The local structure of S2O6 2- in NaClO3 crystal was determined using X-ray absorption fine structure (XAFS). Molecular modelling was applied to investigate the molecular similarity between the impurity and the host. Strong impurity incorporation in the {111} sectors was revealed by X-ray topography. The growth history of doped crystal was reconstructed and interpreted with respect to the inhibiting effect of S2O6 2-. Disturbance in lattice planes of doped crystals was investigated, which was attributed to the incorporation of S2O6 2- on { 111} faces. It also revealed different types of local strain on the { 111 } faces along two different directions. The three-dimensional orientation and the actual structure of S2O6 2- impurity on the {111} faces of NaClO3 crystal were obtained. A structural model for the impurity incorporation was established, showing good consistency with the experimental results. In addition, the segregation coefficient of the impurity was determined by elemental mapping, indicating strong impurity incorporation on the {111} faces rather than others. The incorporated S2O6 2- was concluded to be capable of disrupting the proper packing structure of the {111} faces, obstructing the generation and propagation of growth steps, and decreasing of driving force for crystal growth.

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Sorour, Nabil. "Organic addittives in zinc electrowinning and electrodeposition of Fe-Mo-P alloys as cathodes for chlorate production." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26774.

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Ce projet de travail est divisé en deux études principales: (a) l'influence des certains additifs organiques sur la consommation d'énergie et la pureté du métal de zinc déposé dans le processus d'extraction électrolytique, et (b) l’électrodéposition des alliages binaires et ternaires de Fe-Mo et Fe-Mo-P sur des substrats d’acier doux afin d’agir comme cathodes pour la production de chlorate. (a) Parmi les sept différents additifs organiques examinés, les sels des liquides ioniques ont réussi à augmenter le rendement du courant jusqu'à 95,1% comparé à 88,7% qui a obtenu à partir de l'électrolyte standard en présence des ions de Sb3+. La réduction maximale de la consommation d'énergie de ~173 kWh tonne-1 a été obtenue en ajoutant de 3 mg dm-3 du chlorure de 1-butyl-3-méthylimidazolium dans le même électrolyte. La teneur en plomb dans le dépôt de zinc est réduite de 26,5 ppm à 5,1-5,6 ppm en utilisant les sels des liquides ioniques. (b) Des différents binaires Fe-Mo et ternaires Fe-Mo-P alliages ont été électrodéposés sur des substrats d’acier doux. Les alliages préparés ont une tenure en Mo entre 21-47 at.% et une tenure en P de 0 à 16 at.%. L'activité électrocatalytique de ces alliages vers la réaction de dégagement d'hydrogène (RDH) a été étudiée dans des solutions de chlorure de sodium. La réduction maximale de la surtension de RDH de ~313 mV a été obtenue par l’alliage ternaire préparé Fe54Mo30P16 par rapport à celle obtenue pour l'acier doux. La rugosité de surface et l'activité intrinsèque des revêtements de Fe-Mo-P peuvent être l'origine du comportement prometteur de ces électrocatalyseurs vers la RDH. This work project is divided into two main studies: (a) the influence of certain organic additives on the power consumption and the purity of deposited zinc during electrowinning process, and (b) the electrodeposition of binary and ternary alloys of Fe-Mo and Fe-Mo-P on mild steel substrates to act as cathodes for chlorate production. (a) Among seven different examined organic additives, the ionic liquid salts succeeded to increase the current efficiency up to 95.1% compared to 88.7% obtained from standard electrolyte in presence of Sb3+ ions. Maximum reduction of power consumption of ~173 kWh ton-1 was observed by addition of 3 mg dm-3 of 1-butyl-3-methylimidazolium chloride to the same electrolyte. Lead content in the zinc deposit is reduced from 26.5 ppm to 5.1-5.6 ppm by using the ionic liquid salts. (b) Different binary Fe-Mo and ternary Fe-Mo-P alloys have been electrodeposited on mild steel substrates. The prepared alloys have Mo content between 21-47 at.% and P content from 0 to 16 at.%. The electrocatalytic activity of these alloys towards the hydrogen evolution reaction (HER) was investigated in sodium chloride solutions. The maximum reduction of HER overpotential of ~313 mV was achieved from the prepared ternary alloy Fe54Mo30P16 compared to that obtained from mild steel. The surface roughness and intrinsic activity of Fe-Mo-P coatings could be the origin of the promising behavior of these electrocatalysts towards the HER.

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Gabard, Jérome. "Sélection et caractérisation de mutants déficients pour la nitrate réductase chez Nicotiana plumbaginifoliaTransformation du tabac par un gène de résistance aux herbicides, via Agrobacterium tumefaciens." Paris 11, 1989. http://www.theses.fr/1989PA112071.

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Sélection et caractérisation de mutants deficients pour la nitrate réductase chez nicotiana plumbaginifolia : Deux cent onze mutants déficients pour la nitrate réductase ont été isolés à partir de protoplastes haploïdes de Nicotiana plumbaginifolia, irradiés aux rayons gamma ou UV, en utilisant le chlorate de potassium comme agent de sélection. Les plantules, régénérées à partir des cals résistants, ont été testées pour leur incapacité à croitre sur un milieur à base de nitrate comme seule source azotée, et pour leur absence d'acitivité de la nitrate réductase. Une analyse biochimique et génétique a montré que les mutations sont transmises à la descendance comme un caractère monogénique récessif. Les mutants sont affectés, soit dans le gène codant pour l'apoenzyme de la nitrate réductase : nia, soit dans un des six gènes impliqués dans la biosynthèse du cofacteur à molybdène : cnxA/B/C/D/E et F. De la complémentation intragénique partielle a été observée entre certains mutatns nia, vraisemblablement causée par l'association de deux sous-unités mutées d'apoenzyme, rétablissant l'activité de la nitrate réductase. La croissance des mutatns cnxA est partiellement restaurée sur un milieu à base de nitrate, additionné d'une forte concentration de molybdène. Ce gène est probablement impliqué dans l'étape d'intégration du molybdène dans le cofacteur Transformation du tabac par un gène de résistance aux herbicides, via agrobacterium tumefaciens : L'acétolactate synthase est la cible de deux familles d'herbicides : les sulfonylurées et les imidazolinomes. Un gène d'acétolactate synthase d'un mutant d'Arabidopsis thaliana, résistant à deux herbicides sulfonylurée, a été transféré au tabac, via Agrobacterium tumefaciens. Plusieurs platules transgéniques ont été isolées. Des southern blots et une analyse génétique ont montré que la résistance est exprimée dans la descendance comme un caractère monogénique dominant. L'activité de l'acétolactale synthase est résistante à certains des sulfonylurées, mais pas aux imidazolinones. Le niveau d'enzyme résistante est suffisant pour permettre une croissance normale de semis, en présence de concentrations de deux herbicides sulfonylurées qui inhibibent complètement la croissance du témoin. La résistance est aussi exprimée au niveau da la plante entière Selection and characterization of nitrate reductase deficient mutants of nicotiana plumbaginifolia : Two hundred and eleven nitrate reductase deficient mutants were isolated from gamma or UV irradiated nicotiana plumbaginifolia haploid protoplast cultures, using potassium chlorate as a selective agent. Plantlets were regenerated from resistant calli and tested for their lack of nitrate reductase activity and their inhabillity to grow on an medium with nitrate as sole nitrogen source. Biochemical and genetic analysis showed all mutants to be homozygous for nitrate reductase mutations. Mutations were transmitted as a single recessive mendelien character. Mutants were affected either in the gene coding for nitrate reductase apoenzyme ; nia, or in one of six molybdenum cofactor biosynthesis genes : cnxA/B/C/D/E and F. Some nia mutants showed partial intragenic complementation, probably because of the ability of two different nitrate reductase mutant apoenzyme to restore an almost normal catalytic activity. Growth of cnxA mutants was partially restored on a medium containing unphysiologically high level of molybdenum. This gene is probably involved in the step of integration of molybdenum in the cofactor Transformation of tobacco with a sulfonylurea herbicide resistant gene via agrobacterium tumefaciens : Acetolactate synthase is the target of two herbicide families : sulfonylureas and imidazolinones. An acetolactate syntase gene from an Arabidopsis thaliana mutant, resistant to two different sulfonylurea herbicides was transferred to tobacco via Agrobacterium tumefaciens. Southern blots and genetic analysis showed the resistance to be expressed and transmitted to the progeny as a single dominant mendelien trait. Cross resistance to five sulfonylureas and to three imidazolinones was tested. Acetolactate synthase activity from both clones was signigicantly resistant to three of the sulfonylureas herbicides but sensitive to the two others and to imidazolinones. The level of resistant enzyme was sufficient to allow normal seedling growth in the presence of two sulfonylurea herbicide concentrations which completely inhibit growth of the control. Resistance was also expressed at the whole plant level

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Yu, Jiefei. "Coupled Nitrate Reduction and Ammonium Oxidation in Electrochemical Treatment for Nitrate Brine Wastes." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289943689.

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Pambet, Thomas. "Les intoxications au chlorate de sodium : à propos de trois observations et d'une revue de la littérature : intoxications volontaires." Saint-Etienne, 1988. http://www.theses.fr/1988STET6018.

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Stein, Anke [Verfasser], Wolfgang [Akademischer Betreuer] Pfister, Bernd W. Akademischer Betreuer] Sigusch, and Thomas [Akademischer Betreuer] [Hoffmann. "Die antimikobielle Wirksamkeit von Chloramin im Vergleich zu anderen Antiseptika im Wurzelkanal / Anke Stein. Gutachter: Wolfgang Pfister ; Bernd W. Sigusch ; Thomas Hoffmann." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2011. http://d-nb.info/1016391579/34.

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Bräutigam, Franziska [Verfasser], Bernd [Gutachter] Sigusch, Eike [Gutachter] Glockmann, and Holger [Gutachter] Jentsch. "In-vitro-Suppression von Enterococcus faecalis in den Dentintubuli mit Chloramin-T / Franziska Maria Bräutigam ; Gutachter: Bernd Sigusch, Eike Glockmann, Holger Jentsch." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/1170396844/34.

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Uwaha, Makio. "The Classical Nucleation Model : Entire Process of Crystal Growth and Application to Chirality Conversion." AIP, 2010. http://hdl.handle.net/2237/20569.

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Soma, Arpita. "Electrochemical oxidation of Phenol –A Comparative Study Using Pulsed and Non-pulsed Techniques." Cincinnati, Ohio : University of Cincinnati, 2009. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1267718359.

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Thesis (M.S.)--University of Cincinnati, 2009. Advisor: Margaret J. Kupferle. Title from electronic thesis title page (viewed Apr. 26, 2010) Includes abstract. Keywords: phenol; electrochemical oxidation; chlorate; boron doped diamond anode. Includes bibliographical references.

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Srinivasan, Rangesh. "Treatment of Microcontaminants in Drinking Water." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1242775351.

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Goldblatt, Nicholas Zalmon. "The characterisation of manganese (IV) compounds and the study of the thermal decomposition of potassium chlorate alone and with Mn(IV) and other oxides and salts." Thesis, Brunel University, 1998. http://bura.brunel.ac.uk/handle/2438/5260.

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Manganese dioxide compounds are preferred curing agents for Polysulphide resins used as sealants in industry. These are required to have consistent setting characteristics and the investigation was initiated to characterise a number of proffered compounds of this type an to establish criteria by which an informed choice could be made of an optimum curing ages for a specific set of conditions. Several different chemical and physical properties were examined and critical parameters were established. A compound - sodium birnessite- was identified as a significant agent in the determination of curing properties. It was synthesised and its curing properties alone and in combination with other manganese dioxide compounds was evaluated. In an effort to find a specific reaction which might be used to characterise manganese dioxide curing agents it was decided to examine the classical reaction between these compounds and potassium chlorate. A literature search revealed major contradictions in the reported conditions under which potassium chlorate undergoes thermal decomposition as result of which it was decided to study the decomposition of potassium chlorate alone and in the presence of manganese dioxide and other catalysts. During this investigation a hitherto unreported high temperature structural change in potassium chlorate at 341° C was identified. The existence of this reversible change was confirmed by Powder Diffraction X-Ray analysis and an orthorhombic (near tetragonal) more open structure was assigned to it. It is suggested that the rapid decomposition of potassium chlorate in the solid state presence of catalysts is related to this change to a more open structure.

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Gustavsson, John. "In-situ activated hydrogen evolution from pH-neutral electrolytes." Doctoral thesis, KTH, Tillämpad elektrokemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95369.

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The goal of this work was to better understand how molybdate and trivalent cations can be used as additives to pH neutral electrolytes to activate the Hydrogen Evolution Reaction (HER). Special emphasis was laid on the chlorate process and therefore also to some of the other effects that the additives may have in that particular process. Cathode films formed from the molybdate and trivalent cations have been investigated with electrochemical and surface analytical methods such as polarization curves, potential sweep, Electrochemical Impedance Spectroscopy (EIS), current efficiency measurements, Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Fluorescence (XRF) and Inductively Coupled Plasma (ICP) analysis. Trivalent cations and molybdate both activate the HER, although in different ways. Ligand water bound to the trivalent cations replaces water as reactant in the HER. Since the ligand water has a lower pKa than free water, it is more easily electrochemically deprotonated than free water and thus catalyzes the HER. Sodium molybdate, on the other hand, is electrochemically reduced on the cathode and form films which catalyze the HER (on cathode materials with poor activity for HER). Molybdate forms films of molybdenum oxides on the electrode surface, while trivalent cation additions form hydroxide films. There is a risk for both types of films that their ohmic resistance increases and the activity of the HER decreases during their growth. Lab-scale experiments show that for films formed from molybdate, these negative effects become less pronounced when the molybdate concentration is reduced. Both types of films can also increase the selectivity of the HER by hindering unwanted side reactions, but none of them as efficiently as the toxic additive Cr(VI) used today in the chlorate process. Trivalent cations are not soluble in chlorate electrolyte and thus not suitable for the chlorate process, whereas molybdate, over a wide pH range, can activate the HER on catalytically poor cathode materials such as titanium. Målsättningen med detta doktorsarbete har varit att bättre förstå hur trivalenta katjoner och molybdat lösta i elektrolyten kan effektivisera elektrokemisk vätgasproduktion. Tillämpningen av dessa tillsatser i kloratprocessen och eventuella sidoeffekter har undersökts. De filmer som bildas på katoden av tillsatserna har undersökts med både elektrokemiska och fysikaliska ytanalysmetoder: polarisationskurvor, potentialsvep, elektrokemisk impedansspektroskopi (EIS), strömutbytesmätningar, svepelektronmikroskopi (SEM), energidispersiv röntgenspektroskopi (EDS), röntgenfotoelektronspektroskopi (XPS), röntgenfluorensens (XRF) och induktivt kopplat plasma (ICP). Både trivalenta katjoner och molybdat kan aktivera elektrokemisk vätgasutveckling, men på olika sätt. Vatten bundet till trivalenta katjoner ersätter fritt vatten som reaktant vid vätgasutveckling. Eftersom vatten bundet till trivalenta katjoner har lägre pKa-värde, går det lättare att producera vätgas från dessa komplex än från fritt vatten. Natriummolybdat däremot reduceras på katoden och bildar filmer som kan katalysera vätgasutvecklingen på substratmaterial som har låg katalytisk aktivitet för reaktionen. Molybdat bildar molybdenoxider på ytan medan trivalenta katjoner bildar metallhydroxider. Båda typerna av film riskerar att bilda filmer som är resistiva och deaktiverar vätgasutvecklingen. Laboratorieexperiment visar att problemen minskar med minskad molybdathalt. Båda filmerna kan öka selektiviteten för vätgasutveckling genom att hindra sidoreaktioner. Filmerna är dock inte lika effektiva som de filmer som bildas från den ohälsosamma tillsatsen Cr(VI), vilken används i kloratprocessen idag. Trivalenta katjoner är inte lösliga i kloratelektrolyt och är därför inte en lämplig tillsats i kloratprocessen. Molybdat har god löslighet och kan aktivera vätgasutveckling i ett stort pH‑intervall på titan och andra substratmaterial som själva har betydlig sämre aktivitet för vätgasutveckling. QC 20120530 c6839

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Supriatna, Asep. "Zur Herstellung der Erdalkalimetallchlorate und zu den Lösungsgleichgewichten in den reziproken Salzpaaren MCl2 + 2NaClO3 = M(ClO3)2 + 2NaCl/H2O (M = Mg2+, Ca2+, Sr2+, Ba2+)." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola&quot, 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-3181333.

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Die vorliegende Arbeit befasst sich mit Untersuchungen zur Herstellung der Erdalkalimetallchlorate und zu den Lösungsgleichgewichten in den reziproken Salzpaaren MCl2 + 2NaClO3 = M(ClO3)2 + 2NaCl/H2O (M = Mg2+, Ca2+, Sr2+, Ba2+) bei 25°C, 50°C und 75°C. Neben den Löslichkeiten und Bodenkörperparagenesen sind die Dichten und Viskositäten bestimmt worden. Auf der Basis der erarbeiten Daten erfolgte die Bilanzierung der Herstellungsprozesse der Erdalkalimetallchlorate durch reziproke Umsetzung. Zusammenfassend kann eingeschätzt werden, dass mit etwa 0,2 bis 0,5 kg wasserfreies Chlorat pro kg Umlauflösung durchaus effektive Prozesse der polythermen reziproken Umsetzung vorliegen. Über die IR- und Raman-Spektroskopie und die Thermoanalyse wurden die Erdalkalimetallchlorate bzw. Erdalkalimetallchlorat-Hydrate näher charakterisiert, u.a. bezüglich ihres Zersetzungsverhaltens bis zum Erdalkalimetallchlorid.

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Malmgren, Christine. "Nanoscaled Structures in Ruthenium Dioxide Coatings." Licentiate thesis, Mid Sweden University, Department of Natural Sciences, Engineering and Mathematics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-8728.

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An essential ingredient in the generation of environmentally compatible pulp bleaching chemicals is sodium chlorate. Chlorate is produced in electrochemical cells, where the electrodes are the key components. In Sweden the so-called DSA !R electrodes with catalytic coatings have been produced for more than 35 years. The production of chlorate uses a large amount of electric energy, and a decrease of just five percent of this consumption would, globally, decrease the consumption of electrical energy corresponding to half a nuclear power reactor. The aim of this project is to improve the electrode design on the nanoscale to decrease the energy consumption. The success of the DSA!R depends on the large catalytic area of the coating, however, little is known about the actual structure at the nanometer level. To increase the understanding of the nanostructure of these coatings, we used a number of methods, including atomic force microscopy, transmission electron microscopy, X-ray diffraction, porosimetry, and voltammetric charge. We found that the entire coating is built up of loosely packed rutile mono-crystalline 20 − 30 nm sized grains. The small grain sizes give a the large area, and consequently, lower cell-voltage and reduced energy consumption. A method to control the grain size would thus be a way to control the electrode efficiency. To alter the catalytically active area, we made changes in the coating process parameters. We found a dependency of the crystal-grain sizes on the choice of ruthenium precursor and processing temperature. The use of ruthenium nitrosyl nitrate resulted in smaller grains than ruthenium chloride and lowering the temperature tended to favour smaller grains. A more radical way would be to create a totally different type of electrode, manufactured in another way than using the 1965 DSA !R recipe. Such new types of electrodes based on, for example, nanowires or nanoimprint lithography, are discussed as future directions.

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Malandrini, Harold. "Une étude thermodynamique de l'énergie superficielle des solides divisés. Détermination de la tension superficielle de poudres talco-chloriteuses." Montpellier 2, 1995. http://www.theses.fr/1995MON20238.

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Etude de l'energie superficielle de charges minerales industrielles, en l'occurrence des melanges de talc et de chlorites. Nous les avons caracterises par calorimetrie d'immersion. Cette experience est une mesure de l'enthalpie de creation d'une interface solide-liquide a partir d'un solide parfaitement degaze. A l'aide d'un formalisme thermodynamique rigoureux, un lien peut etre etabli entre l'enthalpie d'immersion et les angles de contact. Des lors il devient possible de relier les modeles de determination de la tension superficielle des solides, utilises pour traiter les angles de contact, a nos resultats experimentaux. L'analyse des enthalpies d'immersion, pour divers couples solide/liquides, montre qu'elles resultent de differentes contributions energetiques, chacune etant associee a un type d'interaction (apolaire et polaire) entre le solide et le liquide a l'interfacens. Il apparait que les solides etudies sont relativement polaires, ils presentent une forte acidite superficielle que l'on peut attribuer aux oxydes metalliques qu'ils contiennent

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Palm, Eva-Lotta. "c-cytokromer hos den (per)kloratreducerande bakterien GR-1 : samt en jämförande studie av c-cytokromer från GR-1, Ideonella dechloratans och Dechloromonas aromatica." Thesis, Karlstad University, Faculty of Technology and Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-775.

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Arbetet beskriver en analys av innehållet av membranbundna och periplasmiska c-cytokromer hos perkloratodlade GR-1 och jämförelser med c-cytokrominnehållet hos Ideonella dechloratans och andra kända c-cytokromer, samt med genomet för Dechloromonas aromatica. Den jämförande studien av c-cytokromer gjordes med syftet att undersöka en hypotes om att bakterierna använder olika vägar för elektronöverföring till det periplasmiska enzymet (per)kloratreduktas. Cellmembran från GR-1 renframställdes genom ultracentrifugering och periplasma preparerades fram med hjälp av osmotisk chock. Fraktionerna analyserades sedan med SDS-PAGE och peptider med kovalent bundet hem (c-cytokromer) detekterades med hjälp av en specifik färgreaktion. Även Touchdown PCR med degenererade primrar genomfördes på isolerat DNA från GR-1 i ett försök att finna en gen kodande för ett NapC/NirT-liknande protein. Slutligen kolmonoxidbubblades reducerade membran för att undersöka förekomsten av cbb3-typ oxidas.Separation och infärgning av periplasmiska och membranbundna proteiner från GR-1 resulterade i sju respektive åtta peptidband med molekylvikter mellan 8-60 kDa. Inget som framkommit under arbetet talar emot hypotesen om att GR-1 och D. aromatica skulle använda ett NapC/NirT-liknande protein som elektronöverförare till det periplasmiska (per)kloratreduktaset. PCR-analysen resulterade i en produkt som troligtvis är en sekvens från en gen som kodar för ett NapC/NirT-liknande protein och två, eventuellt tre, kandidater för ett NapC/NirT-liknande protein hittades i membranet hos GR-1. Dessutom framkom att GR-1 troligtvis använder cbb3-typ oxidas som terminalt oxidas vid reduktion av syrgas under mikroaerofila förhållanden.Vad gäller I. dechloratans och hypotesen om att denna bakterie använder ett lösligt cytokrom c för elektronöverföring till sitt kloratreduktas så har inget framkommit under arbetet som talar emot detta. Tre kandidater för lösliga cytokrom c-proteiner hittades. För teorin talar även att de försök som tidigare gjorts med att påvisa genen för ett NapC/NirT-liknande protein hos denna bakterie gett negativt resultat. This work describes an analysis of membrane-anchored and periplasmic c-type cytochromes of perchlorate grown GR-1, and a comparison with the c-type cytochrome content of Ideonella dechloratans, other known c-type cytochromes and the genome of Dechloromonas aromatica. The aim of the comparison was to investigate a hypothesis that the bacteria use different routes for electron transfer to the periplasmic enzyme (per)chlorate reductase. Cell membrane from GR-1 was prepared through ultracentrifugation and periplasm was prepared through osmotic chock. The fractions were separated by SDS-PAGE and peptides containing covalently bound heme (c-type cytochromes) were detected by a specific staining reaction. In an attempt to probe a gene coding for a NapC/NirT-like protein Touchdown PCR was performed on isolated DNA from GR-1, using degenerate primers. Finally, reduced membranes were treated with carbon monoxide to investigate the presence of cbb3-type oxidase.Separation and detection resulted in seven periplasmic peptides and eight membrane anchored peptides, all with molecular weights in a range of 8-60 kDa. Nothing has been revealed during this work that opposes the hypothesis of GR-1 and D. aromatica using a NapC/NirT-like protein as an electron carrier to their periplasmic (per)chlorate reductase. The PCR resulted in a product that most likely is a sequence from a gene coding for a NapC/NirT-like protein and two, maybe three, candidates for a NapC/NirT-like protein were also found in the membrane of GR-1. Analysis also revealed that GR-1 most likely makes use of a cbb3-type oxidase for reduction of oxygen during microaerofilic conditions.Concerning I. dechloratans, nothing has been revealed during this work that opposes the hypothesis of this bacterium using a soluble cytochrome c as an electron carrier to its chlorate reductase. Three candidates for a soluble cytochrome c protein were found. The theory is also supported by the negative result from earlier attempts to probe a gene coding for a NapC/NirT-like protein in this bacterium.

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Nývltová, Barbora. "Posouzení účinnosti úpravny pitné vody prostřednictvím ekotoxikologických testů a screeningové analýzy." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316248.

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The quality of raw water is deteriorating with the continuous increase in environmental pollution. Raw water is being modified to drinking water by technological processes, and it is therefore necessary to put increased demands on the efficiency of these technological processes and their possible innovation. Due to the fact that raw water is contaminated with different types of pollutants, it is necessary to continuously control the drinking water supplied to the public distribution network in order to ensure its quality. Drinking water treatment is still unable to treat the raw water perfectly, its pollution is only reduced to acceptable standards. For this reason, it is indispensable that the quality of drinking water is being checked regularly and at the same time the efficiency of individual technological processes of drinking water treatment is assessed. This includes screening analysis or eventually ecotoxicological tests. The thesis focuses on the efficiency of technological processes of drinking water treatment. Within the experimental part, samples of raw water and samples of water after each separation stage have been collected at the drinking water treatment plant in the Czech Republic. These samples have been subjected to ecotoxicological tests and screening analysis. Based on the ecotoxicological tests carried out on Thamnocephalus platyurus, Lemna minor and Vibrio fischeri, we can assume the emergence of harmful chlorinated by-products, resulting to nearly 100% mortality in T. platyurus. The results of the screening analysis carried out indicate, after the extraction of specimens by the SPE method using HPLC/MS, that the most effective method for the removal of hormonal substances is ozonization.

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Lima, Phabyanno Rodrigues. "Investigação da formação e efeitos do clorato sobre a reação de desprendimento de hidrogênio no processo de cloro-soda com tecnologia de diafragma." Universidade Federal de Alagoas, 2006. http://repositorio.ufal.br/handle/riufal/1082.

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In this work, the formation and effects of chlorate ion were studied over hydrogen evolution reaction (HER), focusing for the chlorine and alkalis production by diaphragm process, using a pilot and bench cells, respectively. Studies in pilot cell revealed that chlorate formation is dependent of NaOH concentration in liquor and brine dwelling time. It was also observed that the NaOH concentration increase in the cathodic side provoked decreasing of diaphragm structure lifetime. This phenomenon reduced the blockage efficiency to back migration and consequently, increasing NaOH concentration in the anodic chamber, further increase in the undesirable parallels reaction rate, for example, the chlorate formation. After formation of chlorate in the anodic chamber the migration to the cathodic side is inevitable. Therefore to complete the studies we decided to verify the influence the chlorate, in bench cell, in the cathodic side, specifically for HER process. Potential polarization experiments in presence of chlorate, evidenced effects of HER wave displacement over SAE1020 mild steel carbon steel plate employed in industrial cells for chlorine and alkalis production using diaphragm process. Alternatively to SAE1020, other duplex alloys like SAF2205, SAF2304 and SAF2507 were also investigated. SAF2205 alloy presented a very interesting electrocatalytic response for HER. Pilot cell results pointed for the problem detected with the NaOH migration to the anodic side of cell, and invoked the single possibility to solve this problem - the changing of diaphragm cell separator. Bench experiments revealed chlorate influence on HER over SAE1020 carbon steel, claiming for urgent developing of alternative materials/cathodes with chlorate-immune character. Conselho Nacional de Desenvolvimento Científico e Tecnológico Esse trabalho estuda a formação e os efeitos de íon clorato sobre a reação de desprendimento de hidrogênio (RDH) com ênfase para a produção de cloro-soda por processo de diafragma, com a utilização de célula piloto e de bancada, respectivamente. Os estudos em célula piloto revelaram que a formação de clorato é dependente da concentração de hidróxido de sódio no licor de célula e do tempo de residência da salmoura. Observou-se também que o aumento da concentração de hidróxido de sódio no lado catódico provoca envelhecimento prematuro da estrutura do diafragma, e este fenômeno reduz a eficiência do bloqueio à back migration de forma mais intensa. Esta perda de eficiência promove uma maior alcalinização do anólito, e consequentemente, um aumento nas velocidades das reações paralelas indesejáveis, como por exemplo, a formação de clorato. Uma vez formado clorato no compartimento anódico, sua percolação para o lado catódico é inevitável. Por essa razão, optou-se por fazer estudos de bancada do processo catódico, particularmente na região de RDH. Os dados de polarização revelaram a dependência da RDH em presença de clorato sobre o aço carbono SAE1020, atualmente empregado nas células industriais no processo de diafragma para produção de cloro-soda. Alternativamente ao SAE1020, foram estudadas as ligas duplex SAF2205, SAF2304 e SAF2507. Os estudos de polarização mostraram a dependência da RDH para as ligas SAF2304 e SAF2507, por outro lado, a liga SAF2205 apresentou resposta eletrocatalítica para o desprendimento de hidrogênio. Os estudos em célula piloto mostram que a queda de rendimento de produção é observada de forma mais imediata na parte anódica do processo, e fica evidenciada a importância de otimização do separador de diafragma. Nos experimentos de bancada foi constatada a influência do clorato sobre a RDH para o SAE1020, mostrando a necessidade de materiais alternativos que não apresentem susceptibilidade em presença de clorato.

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Kučera, Vladimír. "Studium fotochlorace polyolefinů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217048.

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This Master´s thesis deals with heterogeneous photochlorination of polyolefins and especially with the photochlorination of polypropylene itself. In the theoretical part the available information about properties, manufactory and application of chlorinated polyolefins, specifically polyethylene and polypropylene, is provided. The basic principles of the photochemistry are described, which are further applied to the issue of photochemistry chain reactions and photochemical halogenations, mainly photochlorinations. The practical part includes design and realization of few types of equipment for the heterogeneous photochlorination of polypropylene done at low temperatures (to 50° C) by gaseous chlorine in bulk or chlorine suspended in suspension of PP in CCl4. Series of chlorination was accomplished, which was varied in the type of PP, in the way of dosage Cl2 and in the period of high pressure mercury lamp irradiation (1–90 minutes). The chlorine content in prepared samples was determined by the gravimetry with ATR-FTIR spectroscopy, as well as by the Shöniger combustion method. Their accuracies were than compared. The chlorine content dependence on the period of chlorination and on the porosity of initial PP was established.

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Buzzato, Cristiano Roberto. "Estudos taxonômicos filogenéticos e biossistemáticos em orquídeas terrestres (orchidaceae:orchidoideae) brasileiras." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/106417.

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Dentre as orquídeas terrícolas brasileiras, dois grupos são particularmente importantes do ponto de vista taxonômico, sistemático e biogeográfico: as orquídeas das subtribo Chloraeinae e Spiranthinae. Na sua atual delimitação, Chloraeinae compreende aproximadamente 70 espécies em três gêneros: Chloraea, Bipinnula e Gavilea. Por outro lado, Spiranthinae compreende cerca de 470 espécies exclusivamente neotropicais, distribuídas em 42 gêneros. As análises filogenéticas mais recentes suportam a existência de quatro grupos: os clados Stenorhynchos, Pelexia, Eurystyles+Lankesterella e Spiranthes. Assim, os objetivos deste estudo são: 1) realizar um estudo taxonômico e nomenclatural das orquídeas brasileiras do clado Pelexia; 2) documentar a morfologia floral e vegetativa, com ênfase nos caracteres diagnósticos; 3) realizar um estudo taxonômico e nomenclatural das espécies brasileiras de Chloraeinae; 4) construir uma filogenia molecular mais completa e representativa do clado Pelexia; 5) estabelecer se os gêneros do clado Pelexia são monofiléticos; 6) construir uma filogenia molecular mais completa e representativa de Chloraeinae, com a inclusão de táxons brasileiros; 7) estabelecer um conjunto de caracteres diagnósticos para os gêneros envolvidos neste estudo e, se necessário, propor uma nova delimitação genérica; e 8) propor cenários para a provável evolução de caracteres de importância ecológica. Os resultados de um estudo detalhado, bem como de análises morfológicas e moleculares são: 1) propostas de 48 tipificações, novas sinonímias e notas taxonômicas para as espécies de Goodyerinae e Spiranthinae descritas por José Velloso e Barbosa Rodrigues; 2) novos registros de Pteroglossa e Lyroglossa para o Rio Grande do Sul; 3) uma correção nomenclatural de Spiranthes bicolor e 4) uma sinopse taxonômica das Chloraeinae brasileiras; 5) uma análise filogenética molecular para testar a monofilia dos gêneros atualmente circunscritos no clado Pelexia; 6) uma atualização das relações filogenéticas de Chloraeinae, incluindo espécies Pampeanas de Bipinnula e a espécie tipo do gênero, B. biplumata; 7) um panorama sobre a biologia reprodutiva de duas espécies de Pachygenium e dados adicionais sobre Brachystele e Cyclopogon s.l.; e 8) um estudo detalhado da morfologia floral, biologia da polinização e sistema reprodutivo de Chloraea membranacea (Chloraeinae). Among the Brazilian terrestrial orchids, two groups are particularly important from a taxonomic, systematic and biogeographical aspects: orchids of subtribe Chloraeinae and Spiranthinae. In its current delimitation, Chloraeinae comprises approximately 70 species distributed in three genera: Chloraea, Bipinnula and Gavilea. On the other hand, Spiranthinae comprises about 470 exclusively neotropical species distributed in ca. 42 genera. The most recent phylogenetic analyses support the existence of four clades: Stenorrhynchos, Pelexia, Eurystyles+Lankesterella and Spiranthes clade, respectively. Thus, the aims of this study are: 1) to make a taxonomic and nomenclatural study of Brazilian orchids of Pelexia clade; 2) to document the floral and vegetative morphology, with emphasis on diagnostic features; 3) to make a taxonomic and nomenclatural study of the Brazilian species of Chloraeinae; 4) to assemble a more complete and representative molecular phylogeny of the Pelexia clade; 5) to establish if the genera of the Pelexia clade are monophyletic; 6) to construct a more complete and representative molecular phylogeny of the Chloraeinae, with the inclusion of Brazilian taxa; 7) to establish sets of diagnostic characters for the genera involved in this study and, if necessary, propose a new generic delimitation; and 8) to propose scenarios for the evolution of characters of ecological importance. The main results are: 1) 48 typifications, new synonymies and taxonomic notes for Spiranthinae and Goodyerinae species described by José Velloso and Rodrigues Barbosa; 2) new records of Pteroglossa and Lyroglossa to Rio Grande do Sul; 3) a nomenclatural correction of Spiranthes bicolor and 4) a taxonomic synopsis of Brazilian Chloraeinae; 5) molecular phylogenetic analyses to test the monophyly of the currently circumscribed genera in the Pelexia clade; 6) an update of the phylogenetic relationships of the Chloraeinae, including Pampean species of Bipinnula, and the type species of the genus, B. biplumata; 7) an overview on the reproductive biology of two Pachygenium species and additional data on Brachystele and Cyclopogon s.l.; and 8) a detailed study of the floral morphology, pollination biology and reproductive system of Chloraea membranacea (Chloraeinae).

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Senatore, Sébastien. "Contribution du modèle drosophile à l'étude des mécanismes de régulation du couplage excitation/contraction cardiaque." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX22076.

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Pour mieux comprendre les mécanismes impliqués dans la genèse et la régulation de l'activité rythmique cardiaque, une bonne connaissance des gènes impliqués dans ces mécanismes et de leur fonction est nécessaire.J'ai mis au point les conditions expérimentales d'un crible génétique et identifié deux gènes régulateur du rythme cardiaque : ork1, code pour un canal potassique à deux pores, pur régulateur du rythme cardiaque ; painless, code pour un canal TRPA, régulateur du rythme cardiaque et acteur essentiel de la réponse cardiaque au stress mécanique. Du fait de l'importance de la régulation de l'activité cardiaque par le stress acide, le rôle de NDAE, échangeur Cl/HCO3, a été recherché. Il est requis pour une meilleure récupération après un stress acide et couplé à l'échangeur Na/Ca.Ces travaux ont permis de valider le modèle Drosophile pour identifier de nouveaux gènes et pour étudier le rôle des gènes encore mal connu dans l'activité cardiaque A good knowledge of genes implicated in genesis of cardiac activity and in its regulation is crucial for a better understanding of arrhythmia.In this study, I have developed experimental conditions to perform a genetic screen and identified two gens implicated in cardiac activity : ork1, encoding a two-pore potassium channel is a pure regulator of cardiac rhythm ; painless, encoding a TRPA channel, regulates cardiac frequency and mediates the cardiac response to mechanical stress. We know that cardiac activity is particulary sensitive to acidic stress and the study of NDAE, the unique Drosophila Cl/HCO3 exchanger, has shown that NDAE is required for cardiac activity recovery after acidic stress and displayed the genetic link with the Na/Ca exchanger.This work validates Drosophila as a good system to found new genes implicates in cardiac activity, particularly in genetic screen, and to precise the role of genes still unknown in cardiac activity

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Pisarenko, Aleksey N. "Analytical Measurements and Predictions of Perchlorate Ion Concentration in Sodium Hypochlorite Solutions and Drinking Water: Kinetics of Perchlorate Ion Formation and Effects of Associated Contaminants." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1258154594.

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