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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The oxidizing action of potassium dichromate as compared with that of pure iodine

McCrosky, Carl Raymond, January 1918 (has links)
Thesis (Ph. D.)--Ohio state University, 1918.
2

Oxidation and reduction without the addition of acid I. The reaction between ferrous sulfate and potassium dichromate. II. The reaction between stannous chloride and potassium dichromate ...

Witt, Joshua Chitwood, January 1916 (has links)
Thesis (Ph. D.)--University of Pittsburgh, 1915. / Vita.
3

Acute dichromate poisoning following the use of toxic purgatives

Wood, Robin 12 July 2017 (has links)
During the last ten years, several patients have presented to the Renal Unit of Groote Schuur Hospital with acute renal failure following the use of traditional (N'anga or Gqirha) medication. The history together with abnormal liver-function tests and renal failure was thought to be suggestive of a toxic aetiology. The specific toxin however remained unknown, until during the admission of one patient, a relative brought in the medication, analysis of which revealed a high concentration of potassium dichromate. Subsequently elevated levels of chromium were demonstrated by atomic absorption spectrometry in the blood and urine of this patient. Following this case there have been six further cases of acute renal failure resulting from use of dichromate containing traditional remedies. These remedies were obtained from a variety of sources including street-hawkers, herbal chemists, and traditional healers. Clinical and laboratory data relating to these seven patients will be presented.
4

Acute dichromate poisoning following the use of toxic purgatives

Wood, Robin 29 April 2020 (has links)
During the last ten years, several patients have presented to the Renal Unit of Groote Schuur Hospital with acute renal failure following the use of traditional (N'anga or Gqirha) medication. The history together with abnormal liver-function tests and renal failure was thought to be suggestive of a toxic aetiology. The specific toxin however remained unknown, until during the admission of one patient, a relative brought in the medication, analysis of which revealed a high concentration of potassium dichromate. Subsequently elevated levels of chromium were demonstrated by atomic absorption spectrometry in the blood and urine of this patient. Following this case there have been six further cases of acute renal failure resulting from use of dichromate containing traditional remedies. These remedies were obtained from a variety of sources including street-hawkers, herbal chemists, and traditional healers. Clinical and laboratory data relating to these seven patients will be presented.
5

Desenvolvimento de teste ecotoxicológico com o fungo Alternaria cassiae: toxicidade aguda de agrotóxicos e avaliação de risco ambiental

Basile, Aritana Gil [UNESP] 23 July 2008 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-23Bitstream added on 2014-06-13T19:37:07Z : No. of bitstreams: 1 basile_ag_me_jabo.pdf: 453267 bytes, checksum: 5548cfe22a8e4806904cc2253ea1c709 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / No Brasil os testes ecotoxicológicos são realizados com diversos organismos, porém para a avaliação da poluição dos solos apenas as minhocas são utilizadas como organismo-teste ou bioindicador e não há normas de testes para os outros organismos. Assim, o objetivo deste trabalho foi determinar a sensibilidade e a variação da resposta do fungo A. cassiae ao dicromato de potássio como substância de referência. Para a determinação da concentração efetiva (CE (I)50;7d), foram realizados sete testes com as concentrações 0,0; 50,0; 90,0; 130,0; 170,0; 210,0; e 250,0 mg.L-1 de dicromato de potássio no meio de cultivo BDA, mantido em placas de Petri. O dicromato de potássio foi adicionado ao meio após a autoclavagem, quando este ainda apresentava consistência líquida. Após o resfriamento e solidificação do meio, nas placas, foi colocado um disco com 6,5 mm de A. cassiae. As placas inoculadas foram incubadas a 25ºC com fotoperíodo de 12 horas, durante sete dias. O crescimento do fungo foi avaliado por meio de medidas transversais do diâmetro da colônia. A CE (I)50;7d estimada foi de 65,97 ± 9,48 mg.L-1. No controle não ocorreu inibição do crescimento. Em 50 mg.L-1 a inibição foi de 29%; em 90 mg.L-1, de 72%; em 130 mg.L-1, de 86%; em 170 mg.L-1, de 92%; em 210 mg.L-1, de 95%; e em 250 mg.L-1. de 94%. Assim, há viabilidade na utilização do fungo A. cassiae como representante dos microorganismos do solo em testes ecotoxicológicos e o dicromato de potássio pode ser utilizado como substância de referência. / In Brazil the ecotoxicological tests are conducted with various organisms, but among the soil organisms only earthworms have standardized tests. For other soil organisms there are not standard methods for these studies. The objective of this study was to evaluate the adequacy of potassium dichromate as substance reference to the fungus Alternaria cassiae. To determine the effective concentration (EC (I)50;7d), seven tests were conducted using the concentrations (0.0, 50.0, 90.0, 130.0, 170.0, 210.0, and 250 , 0 mg.L-1) in the BDA media. The respective potassium dichromate concentrations were introduced in the BDA medium while it had liquid consistency. After cooling and solidification of the medium was placed on each plate, a disc with 6.5 mm of A. cassiae, which were incubated at 25 °C with photoperiod of 12 hours for seven days. The EC (I)50;7d estimated was 65.97 ± 9.48 mg.L-1. In concentration of 0.0 mg.L-1 there was no growth inhibition. In 50 mg.L-1 inhibition was 29%, in 90 mg.L-1, 72%; in 130 mg.L-1, 86%; in 170 mg.L-1, 92%; in 210 mg.L-1, of 95% and in 250 m.L-1 was 94%. Thus, it is feasible using the fungus A. cassiae as the representative of microorganisms in the soil ecotoxicological tests and the potassium dichromate as reference substance.
6

Desenvolvimento de teste ecotoxicológico com o fungo Alternaria cassiae : toxicidade aguda de agrotóxicos e avaliação de risco ambiental /

Basile, Aritana Gil. January 2008 (has links)
Resumo: No Brasil os testes ecotoxicológicos são realizados com diversos organismos, porém para a avaliação da poluição dos solos apenas as minhocas são utilizadas como organismo-teste ou bioindicador e não há normas de testes para os outros organismos. Assim, o objetivo deste trabalho foi determinar a sensibilidade e a variação da resposta do fungo A. cassiae ao dicromato de potássio como substância de referência. Para a determinação da concentração efetiva (CE (I)50;7d), foram realizados sete testes com as concentrações 0,0; 50,0; 90,0; 130,0; 170,0; 210,0; e 250,0 mg.L-1 de dicromato de potássio no meio de cultivo BDA, mantido em placas de Petri. O dicromato de potássio foi adicionado ao meio após a autoclavagem, quando este ainda apresentava consistência líquida. Após o resfriamento e solidificação do meio, nas placas, foi colocado um disco com 6,5 mm de A. cassiae. As placas inoculadas foram incubadas a 25ºC com fotoperíodo de 12 horas, durante sete dias. O crescimento do fungo foi avaliado por meio de medidas transversais do diâmetro da colônia. A CE (I)50;7d estimada foi de 65,97 ± 9,48 mg.L-1. No controle não ocorreu inibição do crescimento. Em 50 mg.L-1 a inibição foi de 29%; em 90 mg.L-1, de 72%; em 130 mg.L-1, de 86%; em 170 mg.L-1, de 92%; em 210 mg.L-1, de 95%; e em 250 mg.L-1. de 94%. Assim, há viabilidade na utilização do fungo A. cassiae como representante dos microorganismos do solo em testes ecotoxicológicos e o dicromato de potássio pode ser utilizado como substância de referência. / Abstract: In Brazil the ecotoxicological tests are conducted with various organisms, but among the soil organisms only earthworms have standardized tests. For other soil organisms there are not standard methods for these studies. The objective of this study was to evaluate the adequacy of potassium dichromate as substance reference to the fungus Alternaria cassiae. To determine the effective concentration (EC (I)50;7d), seven tests were conducted using the concentrations (0.0, 50.0, 90.0, 130.0, 170.0, 210.0, and 250 , 0 mg.L-1) in the BDA media. The respective potassium dichromate concentrations were introduced in the BDA medium while it had liquid consistency. After cooling and solidification of the medium was placed on each plate, a disc with 6.5 mm of A. cassiae, which were incubated at 25 °C with photoperiod of 12 hours for seven days. The EC (I)50;7d estimated was 65.97 ± 9.48 mg.L-1. In concentration of 0.0 mg.L-1 there was no growth inhibition. In 50 mg.L-1 inhibition was 29%, in 90 mg.L-1, 72%; in 130 mg.L-1, 86%; in 170 mg.L-1, 92%; in 210 mg.L-1, of 95% and in 250 m.L-1 was 94%. Thus, it is feasible using the fungus A. cassiae as the representative of microorganisms in the soil ecotoxicological tests and the potassium dichromate as reference substance. / Orientador: Robinson Antonio Pitelli / Coorientador: Claudinei da Cruz / Banca: Joaquim Gonçalves machado Neto / Banca: Pedro Antonio Zagatto / Mestre
7

The Crystal Structures of CsCH₃SO₃, LiN₂H₅SO₄, and K₂Cr₂O₇

Brandon, James Kenneth 10 1900 (has links)
X-ray diffraction experiments have been used to determine the structure of cesium methylsulfonate (CsCH₃SO₃), lithium hydrazinium sulfate (LiN₂H₅SO₄), above 160ºC and triclinic potassium dichromate (K₂Cr₂O₇). The solved CsCH₃SO₃ structure is compared with BaSO₄ and the CsCH₃SO₃⁻¹ ion stereochemistry is dicussed in terms of a current theory of bonding for such groups. The previously known structure of room temperature ferroelectric LiN₂H₅SO₄ has recieved additional refinement and a comparison is made with the structure determined above 160ºC. The symmetry and structure found for K₂Cr₂O₇ are compared with similar compounds and predictions are given for the yet unsolved structures of other K₂Cr₂O₇ phases. The first accurate data for the Cr₂O₇⁻² ion stereochemistry is presented. This ion is compared to similar ones, and the possibility of extending a bonding theory to such ions involving chromium is discussed. / Thesis / Doctor of Philosophy (PhD)
8

Efeitos do meio de cultivo sobre a sobrevivência, reprodução e sensibilidade de Ceriodaphnia dubia / Effects of culture water on survival, reproduction and sensitivity of Ceriodaphnia dubia

Mendes, Sandra Valéria Buratini 08 April 2002 (has links)
A espécie Ceriodaphnia dubia tem sido amplamente utilizada em testes de toxicidade crônica. Como a água constitui um fator essencial à sua manutenção, procurou-se avaliar a influência de três tipos de meio no cultivo e na resposta toxicológica deste microcrustáceo a três substâncias de referência. Foram acompanhadas, durante 13 a 18 gerações, a sobrevivência e a reprodução dos organismos em água natural (Reservatório de Ribeirão do Piraí, município de Salto, São Paulo, Brasil) e em dois meios reconstituídos (um simples - água mole reconstituída acrescida de selênio - e um complexo, denominado MS), avaliando-se, a cada 4 ou 5 gerações, as condições e a sensibilidade de cada cultura em testes com cloreto de sódio, dicromato de potássio e fenol. Os resultados evidenciaram um desempenho similar nos meios reconstituídos (em que padrões mínimos para sobrevivência e fecundidade nem sempre foram atendidos) e diferenciado do obtido em água natural - a mais eficiente para manutenção das culturas, onde tais padrões foram, geralmente, superados. Constatou-se a similaridade entre organismos provenientes da água natural e do meio OMS. Observou-se, também que a variabilidade dos resultados do teste ecotoxicológico difere conforme a água de diluição e a substância química utilizada, permitindo reconhecer o NaCI como substância de referência mais apropriada à avaliação da precisão deste método de ensaio, cujo coeficiente de variação máximo aceitável poderia ser estabelecido em 35%. / The species Ceriodaphnia dubia has been widely used in chronic toxicity tests. As water represents as essential factor to its maintenance, as evaluation was made of the influence of three different media in the culture and toxicological response of this microcrustacean to three reference toxicants. Survival and reproduction of this organism, reared in natural water (from Ribeirão do Piraí Reservoir), São Paulo State, Brazil) and in two reconstituted media (a simple one - reconstituted soft water, supplemented with selenium - and a complex one, called MS), were accompanied during 13 to 18 generations; at each 4 or 5 generations such cultures were evaluated in relation to health and sensitivity in toxicity tests with sodium chloride, potassium dichromate and phenol. The results indicated a similar performance in the reconstituted media (where the minimum patterns for survival and fecundity were not always reached) and differentiated from that obtained in natural water - the most suitable culture medium, where such patterns were, usually, exceeded. It was found a comparable sensitivity between natural water and MS cultures. It was also verified that the variability of the results among ecotoxicological test differs according to dilution water and chemical substance, allowing to recognize NaCl as the most suitable reference toxicant to measure the precision of this test method, whose maximum coefficient of variation could be established in 35%.
9

Toxikologisk tillväxtstudie av sötvattenalgen Raphidocelis subcapitata : En jämförelse mellan flödescytometer NovoCyte och automatisk cellräknare TC20 / Study of toxic growth inhibition with unicellular fresh water green algae Raphidocelis subcapitata : Comparison between flow cytometer NovoCyte and automatic cell counter TC20

Andersson, Eva January 2018 (has links)
Biologiska toxicitetstester utförs genom att exponera en testorganism för olika koncentrationer av kemikalier under en bestämd period. Det finns akuta toxicitetstester och kroniska. Resultat från akuta studier presenteras som EC50-värde (Effect Concentration, affecting 50 % of the population). Tester som används som underlag för riskbedömningar ska utföras på kvalitetsmässigt acceptabelt sätt som grundas på International Organization for Standardization (ISO) och Good Labaratory Practice (GLP). Syftet med studien var att studera toxisk inverkan av kaliumdikromat på encellig sötvattenalg, R. subcapitata, genom att räkna cellantal med två olika instrument: flödescytometer och automatisk cellräknare. Vidare att jämföra testernas EC50 medelvärde mot ISO 8692 angivet värde i precisions syfte och att utvärdera de båda räknemetoderna gällande precision och analystid. Kaliumdikromat användes för tillväxtinhibering vid toxicitetstest. EC50-resultaten visade ingen statistiskt signifikant skillnad mellan de båda instrumenten (p=0,47). Den akuta toxicitetsanalysens precision kunde bekräftas som giltig då båda mätmetoders EC50 medelvärden vid jämförelse med ISO 8692 värde befanns inom bestämda 95% konfidensintervallet. Vid jämförelse av studiens två mätningsmetoder, observerades större spridning kring medelvärdet i cellräknarens resultat, där tre EC50 värden hamnade utanför 95% CI. Däremot visade resultatet från flödescytometern mindre spridning och högre noggrannhet jämfört med cellräknarens. Studien visade att flödescytometer skulle kunna användas i framtida toxikologiska tester med encelliga alger, men det krävs flera upprepade försök för att bekräfta fördelar med analysen i flödescytometern. / Biological toxicity tests are performed by exposing a test organism to different concentrations of chemicals over a certain period of time. Results from acute studies are presented as EC50 (Effect Concentration, affecting 50% of the population). Tests used as a basis for risk assessments shall be performed in a quality acceptable way based on the International Organization for Standardization (ISO) and Good Laboratory Practice (GLP). The aim of this study was to study the toxic effect of potassium dichromate on unicellular green algae R. subcapitata, by counting cells with two different apparatus: flow cytometer and automatic cell counter. Additionally, to compare the EC50 mean values against the ISO 8692 value for control of test precision and to compare accuracy and analytical time of two methods. Potassium dichromate was used for growth inhibition in toxicity tests. The EC50 results showed no statistically significant difference between the two instruments (p = 0.47). The accuracy of acute toxicity analysis was confirmed as valid as both EC50 average measurement values compared to ISO 8692 value were found within the 95% confidence interval. When comparing the two methods of the study, greater spread was observed around the mean value in the cell count's results, where three EC50 values were outside 95% CI. The result of the flow cytometer had less spread and higher accuracy compared to the cell count. The study showed that flow cytometers could be used in future toxicological tests with algae, but several repeated tests are required to confirm the benefits of analysis with the flow cytometer.
10

Efeitos do meio de cultivo sobre a sobrevivência, reprodução e sensibilidade de Ceriodaphnia dubia / Effects of culture water on survival, reproduction and sensitivity of Ceriodaphnia dubia

Sandra Valéria Buratini Mendes 08 April 2002 (has links)
A espécie Ceriodaphnia dubia tem sido amplamente utilizada em testes de toxicidade crônica. Como a água constitui um fator essencial à sua manutenção, procurou-se avaliar a influência de três tipos de meio no cultivo e na resposta toxicológica deste microcrustáceo a três substâncias de referência. Foram acompanhadas, durante 13 a 18 gerações, a sobrevivência e a reprodução dos organismos em água natural (Reservatório de Ribeirão do Piraí, município de Salto, São Paulo, Brasil) e em dois meios reconstituídos (um simples - água mole reconstituída acrescida de selênio - e um complexo, denominado MS), avaliando-se, a cada 4 ou 5 gerações, as condições e a sensibilidade de cada cultura em testes com cloreto de sódio, dicromato de potássio e fenol. Os resultados evidenciaram um desempenho similar nos meios reconstituídos (em que padrões mínimos para sobrevivência e fecundidade nem sempre foram atendidos) e diferenciado do obtido em água natural - a mais eficiente para manutenção das culturas, onde tais padrões foram, geralmente, superados. Constatou-se a similaridade entre organismos provenientes da água natural e do meio OMS. Observou-se, também que a variabilidade dos resultados do teste ecotoxicológico difere conforme a água de diluição e a substância química utilizada, permitindo reconhecer o NaCI como substância de referência mais apropriada à avaliação da precisão deste método de ensaio, cujo coeficiente de variação máximo aceitável poderia ser estabelecido em 35%. / The species Ceriodaphnia dubia has been widely used in chronic toxicity tests. As water represents as essential factor to its maintenance, as evaluation was made of the influence of three different media in the culture and toxicological response of this microcrustacean to three reference toxicants. Survival and reproduction of this organism, reared in natural water (from Ribeirão do Piraí Reservoir), São Paulo State, Brazil) and in two reconstituted media (a simple one - reconstituted soft water, supplemented with selenium - and a complex one, called MS), were accompanied during 13 to 18 generations; at each 4 or 5 generations such cultures were evaluated in relation to health and sensitivity in toxicity tests with sodium chloride, potassium dichromate and phenol. The results indicated a similar performance in the reconstituted media (where the minimum patterns for survival and fecundity were not always reached) and differentiated from that obtained in natural water - the most suitable culture medium, where such patterns were, usually, exceeded. It was found a comparable sensitivity between natural water and MS cultures. It was also verified that the variability of the results among ecotoxicological test differs according to dilution water and chemical substance, allowing to recognize NaCl as the most suitable reference toxicant to measure the precision of this test method, whose maximum coefficient of variation could be established in 35%.

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