• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 3
  • 1
  • Tagged with
  • 10
  • 10
  • 5
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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

Capillary electrophoresis as a fast and universal tool in soil analysis

Howald, Markus, Elsenbeer, Helmut, Laczko, Endre, Schlunegger, Urs Peter January 1995 (has links)
Fast analysis of different species of molecules in soils is investigated by capillary electrophoresis (CE). Several CE techniques for the analysis of inorganic ions and carbohydrates have been tested. With regard to the intents of pedologists and the usually large number of soil analyses a bundle of CE systems is proposed, capable of effecting time-saving soil analyses. Adapted electrolyte systems recently published and new separation systems are described. Examples of the application of these methods to two different soil samples are presented.
2

Síntese e caracterização de trocadores iônicos inorgânicos a base de óxidos mistos estanho-titânio para utilização na recuperação de cádmio e níquel e estudos fotoluminescentes

PAGANINI, PAULA P. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:53:26Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:38Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
3

Hodnocení základních ukazatelů termálních vod pomocí separačních metod / Evaluation of basic characteristics of thermal water with separation methods

Skálová, Lucie January 2011 (has links)
The presence of inorganic ions is one of the criteria for thermal water assessing. The most important anions that affect the water quality and allow their use for therapeutic purposes, include sulfates, chlorides, nitrates and bicarbonates. Ions (as sodium, potassium, calcium and magnesium) are the significant cations. The ion chromatography is used for separation of these substances and also some methods based on electrophoretic migration of ions in an electric field. The electromigration method of isotachophoresis was chosen for determination of selected ions in water samples collected from thermal boreholes in Pasohlávky.
4

Surface Water Quality and Aquatic Ecological Health in Central Appalachian Streams

Cook, Nicholas Alexander 10 September 2015 (has links)
The Central Appalachian region is home to several resource-extraction industries, a host of globally unique aquatic wildlife species, and region-wide poverty. These overlapping circumstances make solving environmental issues in the region challenging. Of particular focus is the coal mining industry, both because of its prevalence and because of controversial methods of practice such as mountain top mining. One of the primary concerns in the region is the extirpation of sensitive aquatic macroinvertebrate species. Several studies have suggested the primary driver of this loss of biodiversity is due to increased conductivity in streams impacted by these mining practices. The reality is that several pollutant sources coexist in these Central Appalachian watersheds. Because of geographic isolation, many headwater communities lack proper sewerage and discharge directly into nearby waterways, compounding potential effects of upstream mining activities. Additionally, several legacy sites exist throughout the Appalachian region, both underground and surface mining in nature. To best mitigate ecological impacts of all of these pollutant types, relative contributions of each must be understood, as well as the nature of the pollution contributed by each. As a contribution towards this region-wide need for better information on pollution, the studies comprising this dissertation seek to better understand the composition of these different pollutant sources and their in-stream contributions to conductivity. The first paper found that these sources are indeed distinct in their inorganic ion make-up: surface coal mining was found to contribute primarily Ca, K, Ni, Se, and SO₄⁻², while untreated household waste (UHW) was primarily associated with P. HCO₃⁻ Mn, and Si were found to be associated with a legacy underground discharge. The second and third scientific studies included here analyzed conductivity's effect on Virginia Stream Condition Index (VSCI) versus other water quality and habitat parameters as well as the effect of specific ion suites on VSCI score. Findings indicated that excellent habitat extends species resilience against elevated conductivity, with passing VSCI scores found at conductivity in the 600-800 µs/cm range in cases of excellent habitat metric scores. Meanwhile, VSCI score suppression was highly related to surface mining-related inorganic ions (Ca, K, Mg, Ni, and SO₄⁻²), but also negatively correlated with ions related to UHW (P and Na). These results indicate the need for quantification of biological responses to specific ions in order to initiate targeted mitigate of pollutants in Central Appalachian watersheds. / Ph. D.
5

Elektroforetické stanovení inhibitorů koroze v chladicích kapalinách / Electrophoretical determination of corrosion inhibitors in engine coolants

Smrž, Dominik January 2019 (has links)
A determination of corrosion inhibitors in engine coolants represent a difficult analytical problem due to their different physicochemical properties. Nowadays a lot of instrument methods are needed to determine them. The aim of this work was the development of methods for their determination using only one instrumentation. Capillary zone electrophoreses was chosen as a suitable technique. Three electrophoretic methods for three groups of corrosion inhibitors were developed. Firstly, method for determination of inorganic anions was developed in range from 5 to 50 ppm with limit of detection around 1 ppm. Background electrolyte contains sodium chromate, CTAB and CHES solution. Analytes were detected indirectly at 450 nm. Another method was for determination of organic acids anions. They were determined in range from 5 to 500 ppm. Limit of detection for each analyte was around 1 ppm. Measurement was made with PDC a CTAC water solution. Indirect detection was used for this determination at 350 nm. Last developed method can be use for determination of aryltrizoles in range from 5 to 500 ppm. Limit of detection was around 1 ppm. As a background electrolyte was used sodium tetraborate solution. The developed methods were validated and their suitability for determination of corrosion inhibitors in real...
6

Optimalizace metody pro stanovení anorganických iontů za využití kapilární elektroforézy / Optimization of a method for the determination of inorganic ions using capillary electrophoresis

Špačková, Simona January 2021 (has links)
Inorganic ions are one of the most important group chemicals. Their importance is crucial for all living organisms on the planet and monitoring of their content is essential for this purpose in clinical or environmental analysis but also in the food industry, agriculture or many other industries. Many analytical methods for ion detection have been designed and used, depending on the area of their use. Recently, numerous methods have been adapted to areas where not primarily intended. One such methods may be, for example, laser ablation with inductively coupled plasma mass spectrometry, which has recently begun to affect the analysis of biological samples. As a complementary method, able to detect also non-metallic ions is capillary electrophoresis. In this master thesis, the possibility of applying capillary electrophoresis with indirect photometric detection for the separation of inorganic ions in cell lysates of HeLa cells by capillary electrophoresis was verified. Main attention was paid to chloride ions. The ability to separate inorganic compounds in cellular material using salicylic acid as an absorbing anion in the base electrolyte was tested.
7

Vývoj elektroforetické metody stanovení fosfátů a borátů v nemrznoucích směsích / Development of the electrophoretic method for determination of phosphates and borates in cooling mixtures

Listakhava, Iryna January 2021 (has links)
In this diploma thesis, a method of routine analysis of commercial coolants was developed, focused on the simultaneous determination of inorganic anions - phosphates and borates - as corrosion inhibitors in fresh mixtures and the markers of recycling quality. The method was developed for the instrumental technique of capillary zone electrophoresis with indirect detection at 254 nm. The following were optimized: background electrolyte (its composition, concentration, pH), measured samples (coolant dilution, suitable internal standard) and measurement conditions (capillary length, sample dosing). The influence of the sample matrix on the measurement results, the robustness of the calibration line (or the agreement of the response with the actual analyte concentration) and also the repeatability of the method were tested. Optimizations and tests resulted in a method based on a standard addition with the following parameters: background electrolyte of pH = 11.50 containing sodium chromate at 10 mmol l-1 concentration and CTAB at 1 mmol l-1 concentration; dilution of the coolant sample 20-50×, addition of internal standard MES at 0,1 mmol l-1 concentration, electrokinetic sample injection at -5 kV for 10 s, capillary length 50.0 cm, inner diameter 75 μm. The repeatability of the method expressed as a...
8

PHYSIOLOGICAL RESPONSES AND CORN PLANT BIOCHEMICAL (Zea mays L.) inoculated with arbuscular mycorrhizal fungi UNDER SALT STRESS. / RESPOSTAS FISIOLÃGICAS E BIOQUÃMICAS DE PLANTAS DE MILHO (Zea mays L.) INOCULADAS COM FUNGOS MICORRÃZICOS ARBUSCULARES SOB ESTRESSE SALINO

Emanuelle Sampaio Almeida Pinto 30 August 2011 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Many studies have shown that inoculation with arbuscular mycorrhizal fungi improved plant growth under salt stress. Considering that the salinity is a serious problem that directly affects the productivity of plants, the aim of this study was to evaluate the effects of inoculation of AMF in maize plants under salt stress in the presence or absence of phosphorus. The experiment was run in a greenhouse of the Department of Biochemist and Molecular Biology of the Federal University of the Cearà (Campus of the Pici, Fortaleza - CearÃ), with four replicates per treatment. The experimental design was completely randomized in factorial arrangement 2 (inoculated and not inoculated plants) x 3 (levels of salinity 0.5, 4.0 and 8.0 dS m-1) x 2 (presence or absence of phosphorus), total of 48 experimental units. During the experiment measurements were made of net photosynthesis, transpiration rate, stomatal conductance and SPAD index. At 40 days after sowing the plants, they were collected, and determined leaf area, shoot dry matter (after drying the material under glass), the relative water content, the osmotic potential, microbiological variables (dependency and mycorrhizal colonization), mineral levels (N, P, K+, Ca2+, Mg2+, Na+, and Cl-) and organic solutes (soluble carbohydrates, N-aminosolubles, proline and soluble protein). The mycorrhizal fungi did not provide an increase in the growth of corn plants, but elevated levels of salinity reduced leaf area and shoot dry matter of plants. Generally, the salinity reduced the photosynthesis, stomatal conductance and transpiration in all treatments. The relative water content was not influenced by any of the factors studied. The SPAD index and relative water content were not influenced by any of the factors studied. The osmotic potential was significantly reduced in treatments with 4.0 and 8.0 dS m-1 salinity compared with the level of 0.5 dS m-1. Mycorrhizal colonization decreased with increasing levels of saline. The levels of glomalin were not influenced by the presence of P and not by increasing levels of salinity. The mycorrhizal fungi did not cause increases in levels of inorganic solutes. The presence of P promoted maize cultivation in non-inoculated plants, increased levels of phosphorus in the leaves and stems, at all levels of salinity. Increased salinity levels decreased the levels of N and Mg2+, but promoted increased levels of Na+ and Cl- in corn plants. The water-soluble carbohydrate showed no significant differences for any of the factors. In general, the levels of N-aminosolubles and proline increased with increasing salinity. Since the levels of soluble proteins showed different responses according to the factors. These results suggest that the mycorrhizal fungi did not minimize the effects of salinity in maize plants (hybrid AG 1051), at least under the conditions employed here. / Muitos estudos tÃm demonstrado que a inoculaÃÃo de plantas com fungos micorrÃzicos arbusculares (FMA) melhora o crescimento das plantas sob estresse salino. Tendo em vista que a salinidade à um problema sÃrio e que afeta de forma direta a produtividade das plantas, o objetivo deste trabalho foi avaliar os efeitos da inoculaÃÃo dos FMA em plantas de milho sob estresse salino, na presenÃa ou ausÃncia de fÃsforo. O experimento foi conduzido na casa de vegetaÃÃo do Departamento de BioquÃmica e Biologia Molecular da Universidade Federal do Cearà (Campus do Pici, Fortaleza - CearÃ), com quatro repetiÃÃes. O delineamento experimental foi o inteiramente casualizado, em arranjo fatorial 2 (plantas inoculadas e nÃo inoculadas) x 3 (nÃveis de salinidade 0,5; 4,0 e 8,0 dS m-1) x 2 (presenÃa ou ausÃncia de fÃsforo), totalizando 48 unidades experimentais. Durante a conduÃÃo do experimento foram realizadas mediÃÃes da fotossÃntese lÃquida, da taxa de transpiraÃÃo, da condutÃncia estomÃtica e do Ãndice SPAD. Aos 40 dias apÃs a semeadura das plantas, as mesmas foram coletadas, sendo determinados a Ãrea foliar, a matÃria seca da parte aÃrea (apÃs secagem do material em estufa), o teor relativo de Ãgua, o potencial osmÃtico, as variÃveis microbiolÃgicas (dependÃncia e colonizaÃÃo micorrÃzica), os teores de alguns elementos minerais (N, P, K+, Ca2+, Mg2+, Na+ e Cl-) e solutos orgÃnicos (carboidratos solÃveis, N-aminossolÃveis, proteÃna solÃvel e prolina). A associaÃÃo micorrÃzica nÃo proporcionou incremento no crescimento das plantas de milho, porÃm os aumentos nos nÃveis de salinidade reduziram a Ãrea foliar e a matÃria seca da parte aÃrea das plantas. De maneira geral, a salinidade reduziu a fotossÃntese, a condutÃncia estomÃtica e a transpiraÃÃo em todos os tratamentos. O Ãndice SPAD e o teor relativo de Ãgua nÃo foram influenciados por nenhum dos fatores estudados. O potencial osmÃtico foi significativamente reduzido nos tratamentos com 4,0 e 8,0 dS m-1 de CE em comparaÃÃo com o nÃvel de 0,5 dS m-1. A colonizaÃÃo micorrÃzica decresceu com o incremento dos nÃveis salinos. Os teores de glomalina nÃo foram influenciados pela presenÃa de P e nem pelos nÃveis crescentes de salinidade. A associaÃÃo micorrÃzica nÃo acarretou incrementos nos teores de solutos inorgÃnicos. A presenÃa de P no cultivo do milho promoveu, nas plantas nÃo inoculadas, aumento nos teores de fÃsforo nas folhas e nos colmos, em todos os nÃveis de salinidade. O aumento dos nÃveis de salinidade reduziu os teores de N e Mg2+, porÃm promoveram o aumento nos teores de Na+ e Cl- nas plantas de milho. Os teores de carboidratos solÃveis nÃo apresentaram diferenÃas significativas para nenhum dos fatores analisados. De modo geral, os teores de N-aminossolÃveis e de prolina aumentaram com o incremento da salinidade. Jà os teores de proteÃnas solÃveis apresentaram respostas diferenciadas de acordo com os fatores analisados. Esses resultados sugerem que a associaÃÃo micorrÃzica nÃo minimizou os efeitos da salinidade nas plantas de milho (hÃbrido AG 1051), pelo menos nas condiÃÃes aqui empregadas.
9

Caracterização do material particulado fino e grosso e composição da fração inorgânica solúvel em água em São José dos Campos (SP)

Souza, Patrícia Alexandre de 24 October 2017 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-10-24T12:57:59Z No. of bitstreams: 1 PATRICIA_DISSETAÇÃO_MESTRADO_GEOQUIMICA_2009.pdf: 4047978 bytes, checksum: b2a1f62ef245a5a0d8afcc3ae828bf17 (MD5) / Made available in DSpace on 2017-10-24T12:57:59Z (GMT). No. of bitstreams: 1 PATRICIA_DISSETAÇÃO_MESTRADO_GEOQUIMICA_2009.pdf: 4047978 bytes, checksum: b2a1f62ef245a5a0d8afcc3ae828bf17 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / A cidade de São José dos Campos localizada no Vale do Paraíba é considerada uma área altamente suscetível à poluição do ar devido à geografia desta região, caracterizada por cadeias montanhosas que dão origem a Serra do Mar e Mantiqueira, dificultando a circulação geral da atmosfera e comprometendo a dispersão de poluentes atmosféricos bem como às emissões industriais de alto potencial poluidor proveniente dos parques industriais existente na região e suas vizinhanças. O objetivo do trabalho é caracterizar o material particulado atmosférico fino (PM2,5) e grosso (PM2,5-10) e determinar a composição química dos constituintes inorgânicos solúveis em água associados a estas partículas. As amostras de PM2,5 e PM2,5-10 foram coletadas semanalmente, em período contínuo de 24 h, por intermédio de um amostrador Dicotômico PM10 Sierra-Andersen em São José dos Campos entre fevereiro de 2004 a fevereiro de 2005 totalizando 60 amostragens. As concentrações médias anuais ± desvio padrão de PM2,5 e PM2,5-10 foram respectivamente iguais a 15,7 ± 7,9 e 14,8 ± 8,4 μg m-3. As maiores concentrações de particulado fino e grosso ocorreram no período de estiagem, enquanto que as concentrações mais baixas no período de chuvas, evidenciando o papel fundamental das chuvas na limpeza da atmosfera . Os íons NH4 + e SO4 2- ocorreram predominantemente no particulado fino correspondendo a 62% do total dos constituintes e 20 % da massa; por outro lado, os íons Cl-, Na+ e NO3 - predominaram no particulado grosso equivalendo, juntos, a 54 % dos íons inorgânicos e 11% da massa. Em média, 96% do SO4 2- associado ao PM2,5 equivale ao excesso de SO4 2-, ou seja, a outras fontes naturais e/ou antrópicas não provenientes do sal do mar. A razão NH4 +/ (Exc-SO4 2- + NO3 -) encontrada no PM2,5 igual a 1,08 sugere a formação de aerossóis de (NH4)2SO4 e NH4NO3 provenientes de atividades antrópicas. O déficit médio de cloreto foi de 42% para o PM2,5 e de 39% para o PM2,5-10. O déficit de Cl- para o PM2,5 durante o período de estiagem foi 4 vezes maior do que no período de chuvas, sendo o mesmo não observado para o PM2,5-10. Mais de 90% do K+, Ca2+ e Mg2+ encontrados em ambas as frações finas e grossas representa a parcela não-marinha (natural e/ou antrópica) destes íons. A modelagem hysplit para as retrotrajetórias de massas de ar auxiliou na identificação de episódios de transporte a longa distância, de material particulado de procedência continental e marítima em amostras que apresentaram composição química extremamente alta. A distribuição de chuvas ao longo do período de estudo, foi fundamental para o entendimento do comportamento sazonal das partículas atmosféricas finas e grossas em São José dos Campos. / São José dos Campos, located in the Paraíba Valley, is an area considered highly susceptible to air pollution because of its geography, characterized by mountain ranges that result in Serra do Mar and Mantiqueira, disturbing the general circulation of the atmosphere and threatening the dispersion of air pollutants as well as the high pollution potential emissions from industrial parks that exist in the region and in neighborhood. The objective of this study is to characterize the atmospheric fine (PM2,5) and coarse particulate (PM2,5-10) matter and determine the chemical composition of water-soluble inorganic constituents of these particles. The samples of PM2,5 and PM2,5-10 were weekly collected, in a continuous period of 24 hours with a PM10 dichotomic Sierra-Andersen sampler in São José dos Campos between February 2004 and February 2005, totalizing 60 samples. The annual average concentrations ± standard deviation of PM2,5 and PM2,5-10 were, respectively, 15,7 ± 7,9 and 14,8 ± 8,4 μg m-3. The highest concentrations of fine and coarse particulate matter occurred in the period of drought while lower concentrations were found in rainy period, highlighting the fundamental role of rain in cleaning the atmosphere. NH4 + and SO4 2- ions occurred predominantly in fine particulate matter corresponding to 62% of all constituents and 20% of the mass, on the other hand, Cl-, Na+ and NO3 - ions predominated in coarse particulate matter together amounting 54% of inorganic ions and 11% of the mass. On average 96% of the SO4 2- associated with PM 2,5 equal the Exc-SO4 2-, i.e. other natural and/or anthropic sources not from saltwater. The reason NH4 + / (Exc-SO4 2- + NO3 -) found in PM2,5 equals 1.08 suggesting the formation of (NH4)2SO4 and NH4NO3 aerosols from human activities. The average deficit of chloride was 42% for PM2,5 and 39% for PM2,5-10. The deficit of Cl- for PM2,5 during the drought period was 4 times higher than the one found in the rainy period, the same was not observed for PM 2,5-10. Over 90% of K+, Ca2+ and Mg2+ found in both fine and coarse fractions represent the non-marine parcel (natural and/or antropic) of those ions. The modeling hysplit for air masses retrotrajectories helped identifying long-distance transport episodes, particulate matter of continental and marine origin in samples that showed extremely high chemical composition. The distribution of the rain throughout the study was fundamental for understanding the seasonal behavior of atmospheric fine and coarse particles in Sao Jose dos Campos.
10

[pt] ESTUDO DA ORIGEM, COMPOSIÇÃO QUÍMICA E TRANSPORTE DE AEROSSÓIS COLETADOS NA REGIÃO OCEÂNICA DO RIO DE JANEIRO / [en] STUDY OF THE ORIGIN, CHEMICAL COMPOSITION AND TRANSPORT OF AEROSSOL COLLECTED IN THE OCEANIC REGION OF RIO DE JANEIRO

09 November 2021 (has links)
[pt] Durante o período compreendido entre junho e dezembro de 2014, foram coletadas amostras de MP2.5 e MP10 ao longo da orla marítima do Rio de Janeiro, com a finalidade de caracterizar quimicamente as espécies presentes, identificar as possíveis fontes e avaliar a influência do oceano nas amostras. As amostras foram coletadas por um período de 24 h utilizando Hi-Vol e filtros de fibra de vidro e quartzo. A massa do material particulado (MP) foi determinada por gravimetria. Os filtros com MP foram extraídos com água e/ou HNO3. O extrato ácido foi analisado por Espectrometria de Massas com Plasma Indutivamente Acoplado para a determinação de onze elementos. O extrato aquoso foi analisado por Cromatografia Iônica e Carbono Orgânico Total, para a determinação de íons inorgânicos e de ácidos orgânicos e carbono orgânico. As maiores concentrações de íons inorgânicos, foram obtidas para SO42->Na+>NO3->Cl->C2O42- na maioria das estações monitoradas. Em MP2,5 correlações acima de 0,7 foram observadas entre os íons NO3- e SO42-, além disso, estes aníons também apresentaram coeficientes de correlação significativos com o NH4+, sugerindo fontes antrópicas e a formação de aerossóis secundários. Por outro lado, no MP10 foi possível observar a contribuição marinha nas amostras, através das correlações fortes, entre o Na+, principal traçador de água de mar, com o Cl-, Mg2+ e Ca2+. Finalmente, através da fração mássica reconstituída se observou que as fontes naturais, representadas pelo aporte do solo e do sal marinho contribuem com cerca do 50 porcento dos aerossóis nas duas frações, apresentando maiores porcentagens no MP10, enquanto que, os aerossóis secundários predominam no MP2,5. / [en] During the period between June and December of 2014, was collected samples of PM2.5 and PM10 along the seafront of Rio de Janeiro, in order to chemically characterize the species present, identify the possible sources and evaluate the influence of the ocean in the samples. The samples were collected for a 24 h period using Hi-Vol and quartz and glass fiber filters. The particulate material (PM) mass was determined by gravimetry. The filters with PM were extracted with water and/or HNO3. The acid extract was analyzed by Inductively Coupled Plasma Mass Spectrometry for the determination of eleven elements. The aqueous extract was analyzed by Ionic Chromatography and Total Organic Carbon, for the determination of inorganic ions and organic acids and organic carbon. The highest inorganic ions concentrations were obtained for SO42->Na+>NO3->Cl-->C2O42- in most of the monitored stations. In PM2,5 correlations were observed above 0,7 between the ions NO3- and SO42-, furthermore, this anions also showed significant correlation coefficients with NH4+, suggesting anthropogenic sources and the formation of secondary aerossols. On the other hand, in PM10 was possible to observed the marine contribution in the samples, through the strong correlations, between o Na+, major tracer of seawater, with Cl-, Mg2+ e Ca2+. Finally, through the reconstituted mass fraction it was observed that the natural sources, represented by land and sea salt contributes about 50 percent of the aerossol in the two fractions, showing higher percentages in the PM10, while, the secondary aerossol prevail in the PM2,5.

Page generated in 0.1043 seconds