Electrocatalytic reduction and oxidation of nitrite using cobalt phthalocyanine derivatives was studied. The detection limit of 1 x 10⁻¹° mol dm⁻³ was achieved when these molecules were employed as catalysts for nitrite detection. The mechanisms for nitrite catalysis were proposed. The position of the peripheral substituents on cobalt porphyrazines (related to cobalt phthalocyanines) affected the catalytic activity of these complexes. The highest activity for nitrite reduction was observed on the cobalt(II) 2,3-tetramethyltetrapyridinoporphyrazine ([CoTm-2,3-tppa]⁴⁺), with cobalt phthalocyanine showing the lowest activity, and the cobalt(II) 3,4- tetramethyltetrapyridinoporphyrazine ([CoTm-3,4-tppa]⁴⁺), showing intermediate behaviour. A mixture of a negatively charged cobalt(II) tetrasulfophthalocyanine ([Co¹¹TSPc]⁴⁻) and a positively charged [CoTm-3,4-tppa]⁴⁺ showed better activity for nitrite reduction than did the individual components. Cobalt porphyrazines lowered the potentials for nitrite reduction in that peaking was observed, as opposed to cobalt phthalocyanine, where only the increase in currents was observed without peaking. Using the cobalt phthalocyanine derivatives, nitrite can be reduced to ammonia with high current efficiency. A glassy carbon electrode modified with [Co¹¹TSPc]⁴⁻ was employed for the determination of nitrite. Nitrate had an insignificant effect on nitrite oxidation on these modified electrodes. Electrocatalytic determination of S0₂ was studied as a function of pH at a glassy carbon electrode modified with iron(II) tetrasulfophthalocaynine. It was found that depending on pH, S0₂.xH₂0, HS0₃⁻ and/or SO₃²⁻ are the main compounds in solution and that these compounds behave differently at the electrode surface. Detection limits ranging from 4.0 ± 0.1 x 10⁻⁵ to 7.5 ± 0.1 x 10⁻⁵ mol dm⁻³ depending on pH were observed. Similar results were obtained when cobalt(II) tetrasulfophthalocaynine was employed for S0₂ catalysis under the same experimental conditions. Cysteine and histidine determination using oxidation currents was performed on glassy carbon electrodes modified with [CoTm-3,4-tppa]⁴⁺ (represented as [CoTm-3,4-tppa]⁴⁺-GCE) in pH 7 Tris buffer. The detection limit of 1.0 x 10⁻⁵ mol dm⁻³ for cysteine and 2.24 x 10⁻⁷ mol dm⁻³ for histidine were obtained. Cyanide can be detected down to 1 x 10⁻¹¹ mol dm⁻³ using [CoTm-3,4-tppa]⁴⁺-GCE in pH 10.8 buffer. Cyanide and S0₂ coordinate to the [CoTSPc]⁴⁻ species. The coordination is accompanied by oxidation of the central Co(II) metal, forming a [Co¹¹¹CoTSPc]³⁻ species. The rate constants for cyanide coordination to the [Co¹¹TSPc]⁴⁻ complex are larger than those reported for the coordination of cyanide to FePc and RuPc complexes in non-aqueous media. Autoreduction of [Co¹¹Tmtppa]⁴⁺ occurred in the presence of either histidine or cysteine, with the formation of metal reduced species, [Co¹Tmtppa(-2)]³⁺. Nitric oxide and nitrite coordinate to the [Co¹¹Tmtppa]⁴⁺ species, without auto-reduction of this species, which was observed for cysteine or histidine. The use of [Co¹¹TSPc]⁴ resulted in improved rate of interaction with nitrite when compared to the [Co¹¹Tmtppa]⁴⁺ species.

Orientador: Nelson Adami Andreollo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-13T09:17:24Z (GMT). No. of bitstreams: 1 Modena_SergioFerreira_M.pdf: 1827923 bytes, checksum: 65534a0b51b23922df11c4977531952b (MD5) Previous issue date: 2009 / Resumo: Os compostos de nitrito e nitrato são sais há muito empregados como conservantes de alimentos, que neste atual contexto de aumento acentuado da população mundial e escassez de alimentos, será cada vez mais empregado. Por outro lado, o perfil da sociedade é, cada vez mais, se utilizar de alimentos industrializados prontos para consumo, nos quais estão embutidos vários conservantes na sua elaboração. Estes sais, por sua vez, têm ação danosa ao organismo em situações específicas, como demonstram vários experimentos. A Doença do Refluxo Gastro-Esofágico tem crescido em incidência por todo mundo e em especial em países desenvolvidos como os Estados Unidos e Europa, onde são relatados índices alarmantes do crescimento da freqüência dos carcinomas da junção esôfago-gástrica. O objetivo desta pesquisa foi analisar o modelo experimental de refluxo duodeno-esôfago-gástrico e a ingestão de solução de nitrito de sódio na gênese do adenocarcinoma associado ao esôfago de Barrett. Sessenta ratos machos Wistar foram divididos em quatro grupos, com vinte animais controles não operados (10 animais ingeriram somente água e 10 animais ingeriram água mais solução de nitrito de sódio) e quarenta animais submetidos a anastomose duodeno-esôfago-gástrico látero-lateral (20 animais ingeriram somente água e 20 animais ingeriram água mais solução de nitrito de sódio). A classificação de Viena para displasia e adenocarcinoma foi empregada na análise dos resultados. Após 42 semanas de observação, nos animais operados sem ingestão de nitritos o esôfago de Barrett foi registrado em 26,3% (5/19) dos animais, enquanto no grupo operado associado à ingestão de nitritos, foi encontrado em 72,3% (13/18) dos animais, sendo que neste grupo também foi encontrado seis adenocarcinomas (33,3%). Nenhum animal não operado apresentou o esôfago de Barrett. As categorias 2, 3 e 5 da classificação de Viena somente foram encontradas nos animais operados que ingeriram nitrito de sódio (66,7%). Concluem que a ingestão de nitrito de sódio associado ao refluxo duodeno-esôfago-gástrico têm importante participação na gênese do adenocarcinoma associado ao esôfago de Barrett. / Abstract: The nitrates and nitrites are salts has been using a lot as conservants and chemical additives of foods, that in this current context of accentuated increase of the world population and shortage of foods, they will be used more. On the other hand, the profile of the society is more and more to use industrialized foods ready for consumption, which they utilize several conservants in its elaboration. These salts have harmful action to the organism in specific situations, as demonstrated in many experiments. The gastroesophageal reflux disease has been growing in incidence all over the world mainly in the United States and Europe and related to the alarming indexes of growth of the frequency of carcinomas of the esophagogastric junction. The objective of this research was to analyze the experimental model of duodenum-gastro- esophagic reflux and the ingestion of a solution of sodium nitrite in the genesis of the adenocarcinoma associated to the Barrett's esophagus. Sixty Wistar male rats were divided in four groups: twenty animals controls not operated (10 animals ingested only water and 10 animals ingested water plus sodium nitrite) and forty animals submitted to the side-to-side duodenum-gastro-esophagic anastomosis (20 animals ingested only water and 20 animals ingested water plus solution of sodium nitrite). The Vienna Classification for dysplasia and adenocarcinoma was used in the analysis of the results. After 42 weeks of observation, in the group operated without nitrite ingestion the Barrett's esophagus was found in 26,3% (5/19) of the animals, while in the group operated associate to the nitrite ingestion, it was found in 72,3% (13/18) of the animals, and in this last group it was also found six adenocarcinomas (33,3%). Any animal no operated presented Barrett's esophagus. The categories 2, 3 and 5 of the Vienna Classification were only found in the animals operated that they ingested sodium nitrite (66,7%). The final conclusion is that the ingestion of sodium nitrite associated to duodenum-gastro-esophagic reflux has important participation in the genesis of the adenocarcinoma associated to the Barrett's esophagus. / Mestrado / Cirurgia / Mestre em Cirurgia

Orientador: Yoshitaka Gushikem / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-11T20:31:08Z (GMT). No. of bitstreams: 1 Canevari_ThiagodaCruz_M.pdf: 626518 bytes, checksum: a33704384d49a883c4ca32c883b2ad0d (MD5) Previous issue date: 2008 / Resumo: Este trabalho descreve a síntese do óxido misto SiO2/SnO2 nas composições 3%, 8,6% e 12% (% em massa de SnO2) obtido pelo processo sol-gel. As informações sobre a formação do SiO2/SnO2, foram obtidas utilizando as técnicas disponíveis para tal finalidade como área superficial pela técnica de BET, espectroscopia de fluorescência de raios X e difração em pó de raios X. O óxido misto SiO2/SnO2 foi utilizado como substrato para síntese in situ da ftalocianina de cobalto devido ser mecanicamente resistente, possuir alta área superficial e apresentar uma condutividade elétrica alta. A formação da ftalocianina de cobalto no material, SiO2/SnO2/CoPc, foi confirmada utilizando as técnicas de espectroscopia UV-VIS, espectroscopia IV e espectroscopia de fotoelétrons excitados por de raios X (XPS). Sendo assim, o material SiO2/SnO2/CoPc, foi utilizado na construção de eletrodos quimicamente modificados, no qual um eletrodo de pasta de carbono foi preparado para estudar a eletrooxidação do ácido oxálico e um eletrodo de disco rígido prensado foi preparado para estudar a eletrooxidação dos íons nitrito. Os estudos eletroquímicos foram realizados em solução aquosa de KCl 1 mol L utilizando as técnicas de voltametria cíclica, voltametria de pulso diferencial e cronoamperometria / Abstract: This work describes the synthesis on SiO2/SnO2 mixed oxide at compositions 3%, 8,6% and 12% (% in weight of SnO2) obtained sol-gel process. The information above the formation of SiO2/SnO2 were obtained use the available techniques for such objective like area superficial BET technique, ray X fluorescence spectroscopic and ray X diffraction. The SiO2/SnO2 mixed oxide was use like matrix for in situ synthesis cobalt phthalocyanine due be resistant mechanically, hold high superficial area and present high electric conductive. The formation of cobalt phthalocyanine on matrix, SiO2/SnO2/CoPc, was confirm used the techniques UV-Vis spectroscopic, IV spectroscopic and ray X spectroscopic photoelectron excited (XPS). Like this, the material SiO2/SnO2/CoPc was use for construction modified chemically electrodes, be the carbon paste electrode prepared for study the oxalic acid electooxidation and the rigid disc press electrode prepared for study the nitrite ions electooxidation. The electrochemical study were carry out in 1mol L KCl solution use the techniques cyclic voltammetric, differential pulse voltammetric and chronoamperometric / Mestrado / Quimica Inorganica / Mestre em Química

Orientador: Matthieu Tubino / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T22:36:15Z (GMT). No. of bitstreams: 1 Khan_Sabir_D.pdf: 2190472 bytes, checksum: ec78a6d1fe85286454f1d38855c36cb5 (MD5) Previous issue date: 2013 / Resumo: Foi desenvolvido um método simples, de baixo custo, sensível e seletivo para a determinação de nitrito em queijo e carne curada. Foi empregada a técnica de refletância difusa na região do ultravioleta-visível. O método se baseia na reação entre nitrito, a sulfadiazina e o naftol em meio básico. A reação foi realizada diretamente na célula de medição. Para o queijo o limite de detecção em termos de NaNO2 foi estimado em ca. 2,01 mg L (2,91mol L). O desvio padrão relativo variou de 5% a 8% dependendo da amostra. Os resultados do método foram comparados com os do método oficial empregando o t de Student e o teste F. (2) O objetivo deste trabalho é propor um método que permita a análise de pesticidas organofosforados por meio de um sistema com biossensor enzimático baseado na enzima acetilcolinesterase acoplado à técnica de injeção de análise em fluxo (FIA). A técnica FIA associada ao biossensor enzimático mostrou-se como uma ferramenta analítica para realização de determinação dos pesticidas paraoxon, clorpirifos, diclorvos e malation em procedimento de varredura. Para aumento dos limites de detecção foi feita a oxidação desses organofosforados para a formação de compostos com maior poder inibitório da enzima acetilcolinesterase. A reação de oxidação foi realizada com água de bromo, sendo este um procedimento simples. Este método é específico para inibidores da colinesterase, além de apresentar excelente sensitividade, apesar de sua relativa simplicidade. Além disso, é rápido e de baixo custo se comparado às técnicas geralmente utilizadas, como a cromatografia. (3) O método proposto para se realizar a determinação de metóxido de sódio é simples e sensível. O reagente empregado neste método é muito seletivo para metóxido de sódio em presença do hidróxido de sódio. O método desenvolvido oferece vantagens tais como: utilização de pequenas quantidades de produtos químicos, confiabilidade, simplicidade e rapidez além de custo baixo. / Abstract: We develop a simple, low cost, reliable and fast method of diffuse reflectance ultraviolet-visible for the determination of nitrite in cheese and cured meat. The method is based on the reaction between nitrite, sulfadiazine and naphthol solution in basic medium. The reaction was performed directly in the measuring cell. For cheese the limit of detection in terms of NaNO2 was estimated at ca. 2.01 mg L (2.91 mol L). The relative standard deviations ranged from 5% to 8% depending on the sample. The results of the method were compared with the official method employing T Student test and F. (2) In this work, we developed a scanning method for the determination of organophosphorus pesticides using a FIA procedure associated with an enzymatic biosensor based on acetyl cholinesterase enzyme. The FIA technique associated enzymatic biosensor showed up as an analytical tool for the determination of pesticides such as, Paraxon Chlorpyrifos, Dichlorvos and Malathion. The limits of detection of these organophosphorus compounds were increased by oxidation reaction with adding of bromine water. The method is specific for the cholinesterase inhibitors, having excellent sensitivity, and its simplicity. Furthermore, it is fast and low cost compared to the commonly used techniques such as chromatography. (3) The proposed method for the determination of sodium methoxide is simple and sensitive. The reagent used in this method is very selective for sodium methoxide even in the presence of sodium hydroxide. The method offers advantages such as: use of small amounts of chemicals, reliability, simplicity and cost effective. / Doutorado / Quimica Analitica / Doutor em Ciências

Ph. D.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2007. / Title from PDF title page (viewed on Feb. 4, 2010). Includes bibliographical references (p. 120-131).

Research report on the dynamics of nitric compounds in different water levels of shallow wells, located in Pypliai, Kaunas District, is given in the thesis. Subject of research – water quality indicators: nitrates (NO3-), nitrites (NO2-) and ammonium (NH3). Aim of research – to define variation of nitrates concentrations in different water levels of shallow wells. Methodology: analysis of scientific literature; chemical water quality analyzes methods: spectral and electrochemical methods; statistical analysis using EXCEL, STATISTICA programs. Results of research: the results of scientific research showed, that nitrates concentrations in deeper levels of shallow wells vary differently; the tendencies of these variations depend on seasons. Seasons make no impact to nitrites and ammonium concentrations in deeper levels of shallow wells. The following statistically relevant water indicators were determined to influence nitrate concentration in shallow well water: oxygen quantity and electrical conductivity. Nitrite concentrations are inversely proportional to oxygen amount. Ammonium concentrations depend on organic compound quantity. Statistically relevant links between nitrites and ammonium were estimated.

Darbo objektas - dirbtinių telkinių vandens savybės: nitratų (NO3-), nitritų (NO -2) jonų koncentracijos, organinių medžiagų kiekis (ChDS Mn), Karvių, girdytų dirbtinių telkinių vandeniu, pieno savybės: nitratų (NO3-), nitritų (NO -2) jonų koncentracijos. Darbo tikslas – įvertinti dirbtinių telkinių vandens,naudojamo gyvuliams girdyti taršą, ir jo įtaką pieno kokybei. Darbo metodas. Tyrimams pasirinktos centrinėje Lietuvos dalyje, Kauno rajone Poderiškių ir Mitkūnų kaimuose esančiose penkiose sodybose dirbtiniai vandens telkiniai. Vandens ėminiai iš dirbtinių vandens telkinių buvo imami kas mėnesį, nuo 2006 metų sausio mėnesio iki 2006 metų gruodžio mėnesio (imtinai). Ėminiai buvo imami rankiniu būdu. Pieno ėminiai buvo imami iš karvių, kurios buvo girdomos iš tirtų dirbtinių vandens telkinių tuo pačiu metu. Vandens ir pieno cheminės analizės buvo atliekamos LŽŪU Chemijos katedros neorganinės chemijos tyrimų laboratorijoje. Nitratų jonų koncentracija tiriamajame vandenyje buvo nustatoma jonometriniu metodu, nitritų jonu koncentracija - kolorimetriniu metodu, naudojant Griso reagentą. Nitratų ir nitritų koncentracijos piene buvo nustatytos pagal LST 1264 standartą. Atliktų analizių duomenys buvo vertinami pagal LR Sveikatos apsaugos ministro patvirtintą Lietuvos higienos normą HN 48:2001 Žmogaus vartojamo žalio vandens kokybės higieniniai reikalavimai . Darbo rezultatai. 2006 m. sausio – gruodžio mėnesiais atlikus tyrimus nustatyta, kad nitratų koncentracijos... [toliau žr. visą tekstą] / The object of the work is the properties of water in the artificial basins: concentration of (ChDS Mn), nitrate (NO¯3) and nitrite (NO¯2) ions. The properties of milk milked from the cows watered from artificial water basins: concentration of nitrate (NO¯3) and nitrite (NO¯2) ions. The goal of the work is to evaluate the contamination of water in the artificial water basins used for livestock watering and its effect on milk quality. The method of work. The artificial water basins located in five homesteads located in Poderiškiai and Mitkūnai villages in Kaunas district in the central part of Lithuania were chosen for the research. The water samples from artificial water basins were taken once per month January 2006 through December 2006. The samples were taken manually. The milk samples were taken from cows that at the same time had been watered from the artificial water basins under research. The chemical analysis of water and milk were made at the Inorganic Chemistry Research Laboratory of LUA. The concentration of nitrate ions in the water under research was determined by the ionometric method and the concentration of nitrite ions was determined by the colorimetric method using the Grees reagent. The concentrations of nitrates and nitrites in milk were determined in accordance with LST 1264 standard. The results of the analysis made were evaluated in accordance with the Lithuanian Hygiene Norm HN 48:2001 “Hygienic Requirements for Raw Water Quality Used by People”... [to full text]

Darbo tikslas – įvertinti šachtinių šulinių geriamojo vandens kokybę ir jo gerinimo galimybes Pakruojo rajone. Uždaviniai: 1. Įvertinti šachtinių šulinių geriamojo vandens kokybės rodiklius. 2. Nustatyti nėščių moterų ir moterų, kurios augina kūdikius iki 6 mėn. amžiaus, požiūrį į naudojamo vandens kokybę ir tyrimo rodiklius. 3. Įvertinti šachtinių šulinių geriamojo vandens kokybės gerinimo galimybes. Tyrimo metodika. Anketinė nėščių moterų ir kūdikius iki 6 mėn. amžiaus auginančių moterų (n=167, atsako dažnis 100 proc.) apklausa. Šachtinių šulinių geriamojo vandens kokybės rodiklių tyrimo protokolų analizė (n = 270) ir visuomenės sveikatos centro ir biuro specialistų, rajono ekologo (n=3, atsako dažnis 100 proc.) interviu. Apklausos duomenys analizuoti „SPSS 15.0 for Windows“ programa. Hipotezės tikrintos, taikant χ² testą, nustatčius reikšmingumo lygį p<0,05. Rezultatai. Tyrimo metu buvo nustatyta, kad respondentės, naudojančios užterštų šachtinių šulinių vandenį, dažniausiai gyvena kaimo vietovėse, turi mažas metines pajamas, yra bedarbės. 95,8 % respondenčių gavo informaciją apie šachtinių šulinių vandens kokybę ir patarimus, kaip apsaugoti save ir kūdikius. Moterys, turinčios žemesnį išsilavinimą, informavus apie vandens tyrimo rezultatus bei riziką sveikatai, vartoja užterštą geriamąjį vandenį nitratais ir nesiima jokių veiksmų jo kokybei gerinti. Netinkamai tvarkoma šulinio aplinka, kuri gali sąlygoti užteršimą: apie šulinį auginami augalai, kurie yra tręšiami... [toliau žr. visą tekstą] / The Aim of the study. To asses the quality of the possibilities of improving of water quality. Objectives : 1. Estimate the quality of drinking water. 2. Evaluate the attitude of pregnant women and the women growing up babies sunder the age of six (6) months to the wells water quality indicators. 3. Estimate the opportunities for improvements of quality of drinking water. Research methods. Questionnaire of pregnant women and the women raising infants under six months (n=167), response rate -100 percent. The analysis of the wells for drinking water quality indicators (n=270) was done by the public health center. Interview of the public health professionals of the region: (n=3, response rate 100 percent). Survey data, was analyzed at “SPSS15.0 for Windows” program. The Hypothesis is verified by using the test χ2 , significance level p<0,05. Results. 95.8 % of respondents have received enough information concerning the quality of the water in their wells. The women with lower education were informed about the test results of their water, about health risks using the water, but they still are using contaminated by nitrates drinking water and don’t take any actions to improve it’s quality. Improperly maintenance of wells and their environment may lead to contamination of drinking water: the plants growing near the wells are fertilized with organic fertilizers, sewage is loaded on the ground. The pregnant women with higher education show better knowledge for improvement of water... [to full text]

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.