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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.
311

Influência do ph da água de beber na gênese da alteração óssea por cádmio: estudo experimental em ratos / The influence of the pH of the drinking water in the bone alteration origin caused by cadmium: experimental study in rats

Cynthia Der Torossian Torres Neves 04 March 2015 (has links)
O cádmio (Cd) é um metal pesado e dos mais abundantes elementos encontrados no ambiente. Existem evidências de sua relação coma osteopenia, osteoporose, e osteomalacia e fragilidade do tecido ósseo. Este estudo visa avaliar o efeito do pH da água de beber na gênese da alteração óssea provocada pela intoxicação por cádmio. Neste estudo, foram utilizados90 ratosWistar (Ratus Norvegicus albinus), adultos, machos,divididos em 6 grupos, aos quais foram administrados: A -solução de cloreto de Cd(400mg/L) com pH neutro (pH 7,0); B -solução de cloreto de Cd(400mg/L) com pH ácido (pH 5,0); C -solução de cloreto de Cd(400mg/L) com pH básico (pH 8,0). D -pH ácido (pH 5,0); E -pH básico (pH 8,0); F -pH neutro (pH 7,0). Nofêmur esquerdo de cada rato avaliou-se a densidade óssea, por meio do densitômetro de dupla emissão (DEXA), ensaiosbiomecânicos e escala de HU na tomografia computadorizada espiral.Os resultados demostram que a densidade óssea reduziunos grupos que receberam cádmio e no grupo sem administração de cádmio para o pH 5 ocorreu uma redução da densidade mineral óssea (DMO) e do conteúdo mineral ósseo (CMO). A rigidez biomecânica mostrou-se aumentada para o grupocom pH 5 sem cádmio. Como conclusão geral o cádmio reduziu a densidade óssea. / The cadmium (Cd) is a heavy metal, one of the most abundant elements found in the environment. There are evidences of its relationship in osteopenia, osteoporosis e osteomalacia and fragility of the bone tissue. This study aims to evaluatethe effect of the pH of the drinking water in the bonealteration origin caused by cadmium intoxication. This study envolved90 wistar rats (Ratus Norvegicus albinus), adults, males,divided in 6groups, were witch one receved: A -cadmium choride solution (400mg/L)withneutral ph (pH 7,0); B -cadmium choride solution(400mg/L) with acid ph (pH 5,0); C -cadmium choride solution(400mg/L)with basic ph(pH 8,0); D -with acid ph (pH 5,0); E -basic ph (pH 8,0); F -neutral pH (pH 7,0).Left femurs from each rat were evaluatedbybone density,DEXA,biomechanictest,HU scale from computerized tomography. The results shows that bone density became lower in the groups that received cadmium. In that wich received no cadmium with pH 5 ocurred an lower level of bone mineral density (BMO) andbone mineral content (BMC).The bone rigidity proved increased in the pH 5 with no cadmium. As a general conclusion, cadmium reduced the bone density.
312

Estudo comparativo da eficiência de diferentes técnicas de mensuração da concentração espermática em suínos / Efficiency of different measurement techniques of sperm concentration in swine

Wagner Loesch Vianna 31 October 2006 (has links)
A inseminação artificial (IA) é uma técnica cada vez mais utilizada na suinocultura moderna, pois propicia ao suinocultor vantagens quanto ao desempenho dos reprodutores, ao controle dos cruzamentos e à facilidade na introdução de material genético. Entretanto, a produção de doses inseminantes com qualidade é um dos principais fatores envolvidos no sucesso da técnica. Nesse contexto, a adequada mensuração da concentração espermática do ejaculado suíno é parte fundamental da rotina de trabalho de Centrais de Inseminação Artificial em Suínos. Foram realizados dois experimentos onde se objetivou: Experimento 1 - avaliar a acurácia, a precisão e a robustez do volume do ejaculado do Espermiodensímetro de Karras (ESPM) e do Espectrofotômetro (ESPT), em comparação à Câmara de Neubauer (CN), técnica padrão e também produzir uma tabela de correção de escala do ESPM; Experimento 2 - avaliar o tempo gasto e a repetibilidade de cada técnica, além de comparar a tabela ajustada do ESPM produzida no Experimento 1 com a tabela padrão do ESPM. Utilizaram-se 141 ejaculados, que revelaram concentrações espermáticas médias (milhões de sptz/mL) e número médio de doses que poderiam ser produzidas, respectivamente de 229,1 e 22,6; 185,0 e 18,5; 283,6 e 28,0 para a CN, o ESPT e o ESPM. O viés médio (acurácia) obtido através da média da diferença do resultado da técnica alternativa e da técnica padrão, e o desvio-padrão do viés médio (precisão) do ESPT, em comparação à CN, foram, respectivamente de - 44,1 e 52,6, enquanto que para o ESPM foram de 54,5 e 44,8 (milhões de sptz/mL). Observou-se que o ESPT tende a subestimar e o ESPM a superestimar a concentração espermática, em comparação à CN. O ESPT foi igualmente preciso e mais acurado que o ESPM. Houve pouca influência do volume do ejaculado sobre os resultados do ESPM e do ESPT através dos resultados de robustez para o volume do ejaculado. O ESPM apresentou maior repetibilidade e menor tempo gasto para a realização dos exames, seguido do ESPT e, por último, da CN (P<0,05). A tabela produzida com os dados do Experimento 1 apresentou resultados mais aproximados aos da CN, em comparação com a tabela padrão do ESPM (2,96 bilhões de espermatozóides vivos/dose vs 2,36 bilhões de espermatozóides vivos/dose, respectivamente). Maiores informações de outras Centrais de Inseminação Artificial em Suínos (CIAS) sobre o uso a campo da tabela ajustada produzida, denominada \"Tabela Ajustada para o Espermiodensímetro LPS-FMVZ-USP\", seriam úteis para comprovar a sua eficiência a campo. / Artificial Insemination (AI) in swine is a rising technique that has been used during the last years at the swine production systems, because it furnish several advantages to the producers just like boar high efficiency, better breeding control and easiness in introducing foreign genetic materials. Nevertheless, high quality insemination doses output is one of the most important factors involving the technique success. In this manner, a correct measurement of the spermatic concentration of boars is a basic work routine of the Swine Artificial Insemination Centers (CIAS). Two trials had been performed, whose objectives were: Experiment 1 - evaluate the accuracy, precision and robustness for ejaculation volume of Spermdensimeter (ESPM) and Spectrofotometer (ESPT) in relation to the Neubauer Count chamber (CN), designed as the standard technique. Moreover, produce a scale correction of the ESPM table; Experiment 2 - evaluate the spent time and repetitiousness of each technique, and compare the ESPM adjusted table produced in Experiment 1 with the ESPM standard table. A total of 141 boar ejaculation was used for spermatic concentration measurement by the techniques described above. The average spermatic concentrations (106 sptz/mL) and average doses number were, respectively: 229.1 and 22.6, 185.0 and 18.5, 283.6 and 28.0 for CN, ESPT and ESPM. ESPT mean bias (accuracy) and standard deviation bias (precision), in relation to the CN were, respectively -44.1 and 52.6, while ESPM were 54.4 and 44.8 (106 sptz/mL). Through these results its possible to conclude that ESPT has a tendency to subestimate and ESPM to superestimate the spermatic concentration in relation to the CN. ESPT was more accurate and equally precise than ESPM. Little effect of ejaculation volume on accuracy and precision in both techniques (ESPM and ESPT) was confirmed by the robustness results. ESPM presented a minor coefficient of variation and timeless, followed by ESPT, and finally by CN (P<0,05). The adjusted table produced with Experiment 1 data presented similar results to CN, in relation to the ESPM standard table (2.96 billion of lives sptz/dose vs 2.36 billion of lives sptz/dose, respectively). Complementary data from others CIAS about field use of the ESPM adjusted table produced, named \"Adjusted Table for Karras Spermdensimeter LPS-FMVZ-USP\", would be useful to prove it efficiency.
313

SSB and genetic instability

Andreoni, Federica January 2009 (has links)
Genome stability has great importance in maintaining cell viability and optimal functionality of cellular processes. Loss of genome stability can lead to cell death in the simplest organisms and to deregulation of the cell proliferation machinery in higher organisms, potentially causing cancer or morbid states. The Single Stranded DNA Binding (SSB) protein of Escherichia coli is an essential protein that binds and stabilises ssDNA stretches. Its role is particularly crucial during DNA replication, recombination and repair processes and it has therefore been predicted to play a prominent role in the maintenance of genome stability. The role of SSB in genome instability was investigated using an E. coli strain in which, the expression of the ssb gene was placed under the control of the arabinose promoter. The level of SSB protein present in the cell could therefore be tuned by varying the arabinose concentration in the medium. A wide characterisation of the behaviour of the strain at low SSB level was carried out. Viability and growth tests showed that a threshold level of protein is required to allow normal growth. Microscopy analyses were carried out to follow cell division, nucleoid morphology and SOS response activation. Cells grown at low SSB level, showed a phenotype consistent with impaired cell division and altered nucleoid morphology. The SOS response was activated at low SSB levels and cell elongation was detected. Lowering the arabinose concentration in solid medium allowed the selection of suppressor strains that could form colonies under the new conditions. Sequencing of the entire genome of one such suppressor strain was carried out revealing a possible candidate for the phenotype change. The stability of a 105bp and of a 246bp DNA imperfect palindromes and the stability of CAG·CTG trinucleotide repeat arrays, inserted in the E. coli chromosome, were investigated in correlation to the SSB cellular level. Lowering the SSB level in cells grown on solid medium, increased the instability of the 105bp palindrome presumably by increasing the number of slippage events. On the other hand, SSB overexpression did not have an effect on the stability of the 246bp palindrome. The stability of a leading strand (CAG)75 repeat array was highly increased by overexpressing SSB, while the same effect was not observed for a leading strand (CTG)137 repeat array. Furthermore, excess SSB caused a change in the deletion size distribution profile for the leading strand (CAG)75 strain, lowering the bias towards big deletions. This is consistent with SSB being able to preferentially impede the formation of big DNA hairpins. Also, SbcCD nuclease was shown to have an effect on the deletion size distribution profile of the leading strand (CTG)137 strain. The lack of SbcCD led to a slight reduction of the number of big deletions.
314

Determining H<sub>2</sub>O Vapor Temperature and Concentration in Particle-Free and Particle-Laden Combustion Flows Using Spectral Line Emission Measurements

Tobiasson, John Robert 01 July 2017 (has links)
There is a growing need for the clean generation of electricity in the world, and increased efficiency is one way to achieve cleaner generation. Increased efficiency may be achieved through an improved understanding of the heat flux of participating media in combustion environments. Real-time in-situ optical measurements of gas temperature and concentrations in combustion environments is needed. Optical methods do not disturb the flow characteristics and are not subject to the temperature limitation of current methods. Simpler, less-costly optical measurements than current methods would increase the ability to apply them in more circumstances. This work explores the ability to simultaneously measure gas temperature and H2O concentration via integrated spectral intensity ratios in regions where H2O is the dominant participating gas. This work considered combustion flows with and without fuel and soot particles, and is an extension of work previously performed by Ellis et al. [1]. Five different combustion regimes were used to investigate the robustness of the infrared intensity integral method first presented by Ellis et al. [1]. These included Post-Flame Natural Gas (PFNG), Post-Flame Medium Wood (PFMW), Post-Flame Fine Wood (PFFW), In-Flame Natural Gas (IFNG), and In-Flame Fine Wood (IFFW). Optical spectra were collected as a function of path length for each regime. Methods for processing the spectra to obtain gas temperature, gas concentration, broadband temperature, and broadband emissivity were developed. A one-dimensional spectral intensity model that allowed for specular reflection, and investigated differences between measured and modeled spectral intensities was created. It was concluded that excellent agreement (within 2.5%) was achieved between optical and suction pyrometer gas temperatures as long as 1) the optical probe and cold target used were well-aligned 2) the path length was greater than 0.3 m and 3) the intensity from broadband emitters within the path was smaller than the gas intensity. Shorter path lengths between 0.15 – 0.3 m produced reasonable temperatures with 7 % error while path lengths of 0.05 m or less were as much as 15% in error or the signal would not effectively process. Water vapor concentration was less accurate being at best within 20% (relative) of expected values. The accurate determination of concentration requires first an accurate temperature concentration as well low broadband participation. Some optical concentrations were in error as much as 85%. The 1-D model was compared to the measurement and it was found that the model peaks were sharper and shifted 0.167 cm-1 compared to the measured data. The reason for the shift can be attributed to the uncertainty of the reference laser frequency used in the FTIR. No conclusion was found for the cause of the sharper peaks in the model. The integrated area of bands used to find temperature and concentration matched well between the model and measured spectrum being typically within 3%.
315

Comparison of Agricultural Area Source Ammonia Gas Concentration and Flux Measurements

Reese, Emyrei 01 May 2010 (has links)
This study was conducted in order to compare and evaluate a variety of ammonia (NH3) measurement techniques for determination of ambient gas phase concentration and evaluation of system fluxes. This was accomplished by measuring NH3 emitted from area sources within two dairies, one located in south-central Idaho and another in central California. The measurement techniques utilized included: an array of passive diffusion samplers, a single annular denuder system, a single or paired Fourier transform infrared spectrometer(s) (FTIR), a paired (upwind and downwind) set of differential optical absorption spectrometers (DOAS), and a portable wind tunnel in conjunction with a chemiluminescence monitor. The concentrations measured were manipulated by methods of inverse modeling using the ISCST3, AERMOD, and WindTrax models to yield estimated emission rates for individual sources, as well as an overall dairy emission rate. Furthermore, a comparison of the different techniques took place, and it was concluded that in the context of measuring agricultural area sources, the spectroscopy techniques, FTIR and DOAS, were likely the most desirable systems. This conclusion was based on the systems' ability to yield high precision, path integrated concentration measurements that do not require actual collection of sample. However, as long as a proper deployment scheme is utilized, the passive diffusion samplers also offered a viable option, especially when funding is limited.
316

Arsenic Analysis: Comparative Arsenic Groundwater Concentration in Relation to Soil and Vegetation

Valentine Vecorena, Rominna E 01 March 2016 (has links)
Arsenic (As) is a toxic semi-metallic element found in groundwater, soils, and plants. Natural and anthropogenic sources contribute to the distribution of arsenic in the environment. Arsenic’s toxic and mobile behavior is associated with its speciation ability. There are two types of arsenic available to the environment, inorganic and organic arsenic. Of the two, inorganic arsenic is more toxic to humans and more mobile in the environment. Two inorganic compounds responsible for arsenic contamination are trivalent arsenite, As (III), and pentavalent arsenate, As (V). Trivalent arsenate is considered to be more soluble, toxic, and mobile than pentavalent arsenate. Arsenic’s absorptive properties in plant cells and ability to attach to minerals causing secondary contamination are due to environmental factors such as pH, redox potential, and solubility. The current maximum contaminant level for arsenic in water is 10 µg/L (or ppb). Research on arsenic involving high concentrations already present in groundwater (>300ppb) are compared either with crops irrigated with such water or a human indicator (such as; hair, nails, blood, or urine) in order to determine exposure limits. In this current research, relationships between the area in the studies and the contaminated media (water, soil, vegetation) were tested to determine if arsenic in water was correlated with arsenic concentrations present in soil and vegetation. Commercially obtained ITS Quick Rapid Arsenic Test Kits were used to measure arsenic concentrations for the media tested. A method for analysis of arsenic in vegetation was developed, with an estimated 80% recovery. The pH and conductivity were also taken for water and soil samples as a means of correlative comparison. The development of faster and portable methods for arsenic concentration may provide means for predicting the relationship between all contaminated media. The purpose of the study was to determine the correlation between arsenic water concentration and pH for water, soil, or vegetation and whether it plays an overall role in the amount of arsenic present. As a result, water and soil pH played a significant role in the presence of arsenic in the water and vegetation, respectively. A moderate negative correlation between arsenic in water and water pH was discovered to have a Spearman’s rho value of -0.708 with a p ≤ 0.05. In addition, a significant negative correlation between soil pH and arsenic in vegetation was also discovered to have a Spearman’s rho of -0.628 at a p ≤ 0.05. Even though, pH was significantly correlated with arsenic concentrations in different media, there is evidence that pH plays a role also in the amount of arsenic available in the soil and vegetation. Further studies are recommended.
317

Relationship of Bicarbonate Concentration of Plant Tissue to that of the Growth Media as a Factor in Chlorosis

Carlsen, Gary H. 01 May 1957 (has links)
Throughout the years lime-induced chlorosis has contributed to untold economic losses. Although this disease has challenged the technical ingenuity of outstanding plant and soil scientists, the exact cause has never been determined; consequently, no preventative measures or permanent cures can, as yet, be recommended. This physiological malady, unchecked, continues its rampage in regions where the disease is prevalent.
318

Aerosol spatial and temporal variability as seen by Mobile Aerosol Monitoring System (MAMS) / Variabilité spatiale et temporelle des aérosols vue par le système mobile MAMS

Popovici, Ioana Elisabeta 18 December 2018 (has links)
Les aérosols sont une composante variable de l'atmosphère, ayant un rôle important et complexe sur la qualité de l'air et le climat. La plupart des observations d'aérosols au sol sont limitées à des emplacements fixes, ce qui réduit la connaissance sur leur variabilité spatiale. Afin de compléter cette information, un système mobile d’observation des aérosols (MAMS - Mobile Aerosol Monitoring System) a été mis au point pour explorer la variabilité verticale et spatiale des propriétés optiques et microphysiques des aérosols. MAMS est un « laboratoire » conçu sur un véhicule, se distinguant des autres plateformes transportables par sa capacité à effectuer des mesures au cours du mouvement. Equipé d'instruments de télédétection et in situ, MAMS a exploré la variabilité des aérosols au travers de campagnes mobiles sur routes dans diverses situations. Ce travail présente les études de variabilité et des événements remarquables observés en France et en Chine. L’une des variables aérosols recherchée est leur concentration massique et leur distribution verticale. Ce défi est relevé dans ce travail. Le système mobile offre une grande flexibilité, et un bon rapport coût-efficacité, car il permet de réagir rapidement en cas d’événements aérosols soudains, tels que des épisodes de pollution, poussières, incendies ou éruptions volcaniques, démontrant son utilité pour les réseaux d’observation recherche et opérationnels. Les applications de la plateforme d'exploration mobile pour les activités de validation des missions spatiales d’observation de la Terre et de l’atmosphère, pour l’évaluation des modèles et les campagnes d’intercomparaison d’instruments sont présentées. Des nouvelles perspectives, tant au niveau instrumental que méthodologique, sont introduites, laissant la place à des améliorations dans les observations mobiles des aérosols. / Aerosols are a variable component of the atmosphere, having an important and complex role on air quality and climate. Most of the ground-based aerosol observations are limited to fixed locations, narrowing the knowledge on their spatial variability. In order to overcome this issue, a compact Mobile Aerosol Monitoring System (MAMS) has been developed to explore the vertical and spatial variability of aerosol optical and microphysical properties. MAMS is a vehicle-based laboratory, distinguished by other transportable platforms through its ability to perform measurements during the movement. Equipped with remote sensing and in situ instruments, MAMS explored the aerosol variability through mobile on-road campaigns in various situations. This work presents variability studies and remarkable events observed both in France and in China. One of the researched aerosol variables is their mass concentration and vertical distribution. This challenge is taken up in this work. The mobile system presents a great flexibility and is cost-effective, being able to respond quickly in case of sudden aerosol events such as pollution episodes, dust, fire or volcano outbreaks, proving to be a useful platform for aerosol observation and operational networks. Applications of the mobile exploratory platform for validation activities of space missions observing the Earth and the atmosphere, for models’ evaluation and for instrument intercomparison campaigns are presented. New perspectives, both on instrumental and methodology levels are introduced, leaving place for improvements in the mobile aerosol observations.
319

Characterisation of Prebiotic Compounds from Plant Sources and Food Industry Wastes: Inulin from Jerusalem Artichoke and Lactulose from Milk Concentration Permeate

Paseephol, Tatdao, s3102901@student.rmit.edu.au January 2008 (has links)
The development of processes for the preparation of prebiotic compounds, namely inulin from tubers of Jerusalem artichoke (JA-Helianthus tuberosus L.), and lactulose from milk concentration permeate (MCP) was examined. Inulin was extracted from the whole JA tubers using hydrothermal extraction process, followed by clarification and concentration. The concentrate was fractionated using two different procedures i.e. ethanol fractionation and cold precipitation (+4 and/or -24C) into high- and low-molecular-weight components. The most satisfactory method was cold fractionation wherein the insoluble heavier inulin fractions were found to settle to the bottom and were separated and spray-dried to obtain inulin powder. Lactose in MCP was isomerised into lactulose using carbonate-based catalysts (oyster shell and egg shell powders) followed by clarification and concentration. The high-performance liquid chromatography with refractive index detector (HPLC-RID) chr omatograms and changes in pH and colour values confirmed the conversion of lactose into lactulose and decomposition of lactulose into by-products. The results obtained showed the suitability of oyster shell powder for lactose isomerisation in lieu of egg shell powder. For preparing lactulose-enriched MCP with acceptable lactulose yield of 22%, the optimum reaction conditions were found to be catalyst loading of 12 mg per mL of MCP and isomerisation time of 120 min at 96C. The resulting products i.e. JAI concentrate and powder and lactulose-enriched MCP syrup (40B) were tested for their prebiotic power in media broth and in fermented milk models. Prebiotic properties of these compounds were observed as supplementation levels increased from 0-2% to 3-4%. Based on the growth and acidification abilities of the probiotic strains tested, the combination of Lactobacillus casei LC-01 with JAI, and Lactobacillus acidophilus LA-5 with lactulose-enriched MCP syrup were found to be the best for development of synbiotic yoghurt. The prebiotic effect of JAIP was then compared with the two commercial chicory inulin products (Raftiline GR and Raftilose P95). Probiotic yoghurts supplemented with 4% inulin powders were prepared from reconstituted skim milk using mixed cultures of Lactobacillus casei LC-01, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (1:0.5:0.5, w/w). The survival and acidifying activity of probiotic and lactic acid cultures were investiga ted during the shelf life of 28 days at 4C. Incorporation of JAIP and chicory inulins resulted in a significant improvement in viability of LC-01 compared with non-supplemented yoghurt, maintaining more than 107 CFU g-1 throughout storage time. Additionally, the suitability of JAIP as fat replacer was determined in a set of fat-free yoghurt in comparison to three commercial chicory inulin products. Results of large deformation tests revealed that the firmness of JAIP-supplemented yoghurt was reduced to a similar level as the full-fat control yoghurt. However, small deformation results showed that the JAIP could not fully mimic milk fat to the same extent as Raftiline HP with an average DP of 23. The rheological effects of JAIP addition were comparable to those of short-chain (Raftilose P95 with an average DP of 4) and medium-chain inulins (Raftiline® GR with an average DP of 12).
320

Does ownership affect performance? : Evidence from Chinese listed companies

Zhou, Meng Meng January 2009 (has links)
No description available.

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