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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.
441

Or et alliages d'or : détermination de la teneur en or et de l'épaisseur des revêtements par méthodes de rayons X.

Castel, Albert, January 1900 (has links)
Th. 3e cycle--Spectrochim. et méthodes d'anal.--Lille 1, 1980. N°: 808.
442

Design of a Smartphone-Camera-based Fluorescence Imaging System for the Detection of Oral Cancer

Uthoff, Ross January 2015 (has links)
Shown is the design of the Smartphone Oral Cancer Detection System (SOCeeDS). The SOCeeDS attaches to a smartphone and utilizes its embedded imaging optics and sensors to capture images of the oral cavity to detect oral cancer. Violet illumination sources excite the oral tissues to induce fluorescence. Images are captured with the smartphone’s onboard camera. Areas where the tissues of the oral cavity are darkened signify an absence of fluorescence signal, indicating breakdown in tissue structure brought by precancerous or cancerous conditions. With this data the patient can seek further testing and diagnosis as needed. Proliferation of this device will allow communities with limited access to healthcare professionals a tool to detect cancer in its early stages, increasing the likelihood of cancer reversal.
443

Detecção de lesões de cárie oclusal por meio de métodos baseados na medição da fluorescência induzida pela luz /

Rodrigues, Jonas de Almeida. January 2008 (has links)
Resumo: O objetivo do presente estudo foi avaliar in vitro o desempenho dos métodos baseados na medição da fluorescência induzida pela luz para detecção de lesões de cárie oclusal em dentes permanentes. Para tanto, foram realizadas três pesquisas: (1) O objetivo dessa pesquisa foi avaliar a influência da subtração do valor de fluorescência zero no desempenho de dois aparelhos que induzem fluorescência na detecção de cárie. Desse modo, foram utilizados 119 molares permanentes, nos quais três áreas da superfície vestibular (cúspide, central e cervical) das porções mesial e distal foram selecionadas. Além disso, uma lesão de cárie oclusal por dente foi escolhida como "sítio teste". Dois examinadores mensuraram tanto as áreas nas superfícies vestibulares quanto as lesões oclusais utilizando o DIAGNOdent 2095 (DD, KaVo, Alemanha) e o DIAGNOdent 2190 (DDpen). Foi observada influência da subtração do valor de fluorescência zero no desempenho do DD, com diminuição da sensibilidade. Pode-se concluir que as mensurações com o DD podem ser realizadas sem a subtração do valor de fluorescência zero. No entanto, para o DDpen esse procedimento não pode ser eliminado. (2) Foram selecionados 119 dentes com o objetivo de comparar o desempenho na detecção de lesões de cárie oclusal de três aparelhos que induzem fluorescência, exame radiográfico convencional e sistema ICDAS II. Uma lesão de cárie por dente foi escolhida como "sítio teste". Dois examinadores realizaram duas medidas independentes utilizando o DD, DDpen, câmera VistaProof (VP, Dürr Dental, Alemanha), além de exame radiográfico convencional e exame visual através do sistema ICDAS II. Conclui-se que cada aparelho variou seu desempenho de acordo com os valores de sensibilidade e especificidade. / Abstract: The aim of this in vitro study was to asses the performance of light-induced fluorescence as auxiliary to conventional methods is detecting occlusal caries lesions in permanent teeth. For this reason, three studies were carried out: (1) The aim of this study was to evaluate the influence of zero value subtraction on the performance of two laser fluorescence devices for detecting occlusal caries. 119 permanent molars were selected. Three areas (cuspal, middle and cervical) of both mesial and distal portions and one occlusal site were assessed by two examiners using the DIAGNOdent 2095 (LF, KaVo, Germany) and DIAGNOdent 2190 (LFpen) devices. It was observed an influence of the zero value subtraction in the LF performance: the sensitivity decreased. However, because of the trend, it could be concluded that the LF readings could be performed without the zero value subtraction. Despite of that, it does not imply in wrong results clinically. For the LF pen, the zero value subtraction influences the performance though and should however not be eliminated. (2) This in vitro study compared the performance of fluorescence-based methods, radiographic examination, and ICDAS II system on occlusal surfaces. 119 molars were independently assessed twice by two experienced dentists using the laser fluorescence (LF and LFpen) and fluorescence camera (FC, Dürr Dental, Germany) devices, ICDAS II system and bitewing radiographs (BW). It can be concluded that the performance of each method changes according to the sensitivity and specificity. / Orientador: Rita de Cássia Loiola Cordeiro / Coorientador: Adrian Lussi / Banca: Lourdes Aparecida Martins dos Santos Pinto / Banca: Angela Cristina Cilense Zuanon / Banca: Denise Fonseca Cortes / Banca: Fausto Medeiros Mendes / Doutor
444

Development of a high-throughput bioassay to determine the rate of antimalarial drug action using fluorescent vitality probes

Laming, Dustin January 2016 (has links)
Malaria is one of the most prevalent diseases in Africa and the Plasmodium falciparum species is widely accepted as the most virulent, with a fatality rate of 15 – 20 % of reported cases of infection. While various treatments have been accepted into early stage clinical trials there has been little progress towards a proven vaccine. Pending a long term solution, endemic countries rely heavily on the development of innovative drugs with acute efficacy coupled with rapids mode of action. Until recently the rate of drug action has been measured by light microscopic examination of parasite morphology using blood slides of drug treated parasite cultures at regular time intervals. This technique is tedious and, most importantly, subject to interpretation with regards to distinguishing between viable and comprised parasite cells, thus making it impossible to objectively quantitate the rate of drug action. This study aimed to develop a series of bioassays using the calcein-acetoxymethyl and propidium iodide vitality probes which would allow the rate of drug action on Plasmodium falciparum malaria parasites to be assessed and ranked in relation to each other. A novel bioassay using these fluorescent vitality probes coupled with fluorescence microscopy was developed and optimized and allowed the rate of drug action on malaria parasites to be assessed i) rapidly (in relation to current assay techniques) and ii) in a semi-quantitative manner. Extrapolation to flow cytometry for improved quantification provided favourable rankings of drug killing rates in the pilot study, however, requires further development to increase throughput and approach the ultimate goal of producing a medium-throughput assay for rapidly assessing the rate of action of antimalarial drugs. Attempts to adapt the assay for use in a multiwell plate reader, as well as using ATP measurements as an indication of parasite vitality after drug treatment, was met with erratic results. The viability probes assay as it stands represents an improvement on other assay formats in terms of rapidity and quantification of live/compromised parasites in cultures.
445

Attenuation correction techniques for tissue fluorescence

Bradley, Robert Stephen January 2006 (has links)
Fluorescence intensity measurements have the potential to facilitate the diagnoses of many pathological conditions. However, accurate interpretation of the measurements is complicated by the distorting effects of tissue scattering and absorption. Consequently, different techniques have been developed to attempt to compensate for these effects.
446

Development of a thiol-reactive fluorescent probe for the identification of human spermatozoa

Adams, Shannon Michele 01 November 2017 (has links)
Current methods of identifying semen include preliminary methods such as an alternate light source (ALS) and color tests which test for the presence of acid phosphatase (AP). Confirmatory methods for identifying semen include the microscopic identification of spermatozoa which typically use staining methods such as the Christmas Tree Stain (KPIC) or hematoxylin and eosin stain (H&E). Other methods include immunoassay cards that test for the components of semen such as prostate specific antigen (PSA) and semenogelin (Sg). One common fluorescent staining method used to identify the presence of spermatozoa is SPERM HY-LITERTM which uses an anti-human sperm-specific mouse monoclonal antibody coupled to an AlexaFluor 488 dye. This causes the entire head of the sperm cell to fluoresce when a FITC filter is used. It also utilizes a 4,6-diamidino-2- phenylindole (DAPI) fluorescent dye that stains all cell nuclei non-specifically. This allows the analyst to easily identify whether sperm is present in the sample. A drawback of the antibody labeling procedure is that there are many washing and transfer steps that can lead to sample loss; thus a need for a new, optimized staining method exists. During spermiogenesis, protamines replace histones to further condense the DNA of the sperm nucleus. Humans express two proamines, protamine 1 (P1) and protamine 2 (P2). The protamines contain an arginine-rich core as well as cysteine residues. The high levels of arginine create a net positive charge that allows for stronger binding to DNA. The cysteine residues allow for the formation of inter and intra-protamine disulfide bonds which allow for the chromatin compaction. If the disulfide bonds found in protamines can be reduced to produce free thiols, a thiol-reactive probe can bind and label the protamines in the sperm nucleus. Reduction of the disulfide bonds can be performed by use of reagents such as dithiothreitol (DTT) or tris-(2-carboxyethyl)phosphine (TCEP). From the literature on thiol-reactive probes, it is suggested that TCEP be used as a reducing agent due to its structure. DTT contains thiol groups and when removed from the sample, thiol groups may be oxidized back into disulfide bond. In addition, TCEP is more stable than DTT at a higher pH and higher temperatures. Once disulfide bonds have been reduced, a thiol-reactive probe may be introduced. There are many different types of probes that may be used. Maleimides are commonly used for thiol modification and quantitation. When the compound encounters a thiol group, the thiol group is added across the double bond, yielding a thioether. The reagent used is N-7-dimethylamino-4-methylcoumarin-3-yl)maleimide (DACM). It absorbs light at 376 nm and emits light at 476 nm, producing a blue fluorescence. The dye is nonfluorescent until it reacts with a thiol group. In this research, both sperm and epithelial cells were added to the slides in order to develop a novel staining procedure. The initial protocol used TCEP to break the disulfide bonds followed by DACM to bind free thiol groups. Sodium dodecyl sulfate (SDS) was then added to the protocol to lyse cells. DTT was tested for use as a reducing agent as well. The purpose of establishing this protocol was to design a procedure for rapid labeling of sperm that does not require antibody labeling. In the antibody labeling procedure, there are many washing and transfer steps. The proposed method may limit the number of procedural steps resulting in less loss of biological material. It can also help to limit the time-consuming methods of the current staining techniques, such as KPIC and H&E.
447

Developing a methodology for the non-destructive analysis of British soft-paste porcelain

Dunster, Joanna Margaret January 2016 (has links)
Soft-paste porcelain was produced in Britain in great quantities between the mid-18th and early 19th centuries. Due to industrial secrecy and the complexities of creating a product that would survive high-temperature firing, a range of paste recipes was employed by dozens of factories. This has resulted in an array of porcelains which vary in their elemental composition and mineralogy. This research carries out a meta-analysis of the published data for porcelain bodies and glazes and concludes that some discrimination can be achieved using the major and minor elemental composition of the bodies, and that for the glazes intra-factory variation is often greater than inter-factory variation in composition. A pilot investigation of the trace elemental composition of British porcelain is carried out using Laser Ablation Inductively Coupled Plasma Mass Spectroscopy, which finds compositional groups corresponding to different sources of clay and silica raw materials. In the interests of preserving intact objects, there is recognised a need for a non-destructive method for analysing British porcelain, in order to provenance and date objects. Such a method would rely on data from the surface of the object, which is typically covered by glaze and over-glaze coloured enamels, and this research demonstrates that the formulae used for the glaze and enamels are in some cases characteristic of the factory, or workshop, and period at which they were created. Hand-Held XRF analysis is used to analyse the glaze, underglaze blue and polychrome enamels on a selection of porcelain objects from different factories, and compositional traits are identified that allow some factories and periods to be distinguished. Glass standards are developed, which are representative of the glaze and enamel composition, and which could allow X-ray fluorescence (XRF) data to be calibrated for fully quantitative results.
448

Resonance fluorescence of self-assembled quantum dots

Santana, Ted Silva January 2016 (has links)
Resonance fluorescence from solid state devices have been motivated by the capability to obtain a bright source of antibunched and indistinguishable photons from a semiconductor chip. Such a photon source would be a strong candidate for applications in the quantum information field. In this thesis, an experimental setup to obtain high signal to noise resonance fluorescence from a single quantum dot is first presented. I then discuss the photon statistics, power spectrum, second-order correlation function and two-photon interference of the stream of resonance fluorescence. Particular emphasis is placed on a throughout investigation of spectral fluctuations caused by charge noise and Overhauser field generated by fluctuating nuclear spins in the quantum dot. In each case, it is found that noise can be overcome to generate single photons that exhibit high visibility two-photon interference. Finally, an interference effect caused by the interaction of a quantum dot and a nearby metal surface is presented. Preliminary analysis yields quantitative agreement with the data.
449

Vliv vodního deficitu na fyziologické charakteristiky vybraných druhů listové zeleniny / Influence of water deficit on physiological characteristics of selected species of green leafy vegetables

Kraus, Kamil January 2016 (has links)
The harmful influences on plants are called stress factors. The stress itself does not slow down only vital functions of plants but influences directly the size and quality of final product as well. Worldwide, we count the so called abiotic stresses as the most significant crop production stressors. These include in recent years extremely high temperatures and unequal rainfall distribution both areal and during vegetation period. The water deficit (drought) belongs to the most important stress factors in agriculture. It influences crop production all over the world. Also vegetables are responsive to water deficit, especially the species with huge amount of water in their tissue. Therefore, the goal of this thesis is to assess the impact of water stress on gas exchange and photosynthetic activity of mangold "Beta vulgaris", salad rocket "Eruca sativa" and lettuce "Lactuca sativa", which were placed at water deficit. The plants - mangold, salad rocket and lettuce - were grown in a partly controlled greenhouse conditions under the Department of Botany and Plant Physiology FAPPZ ČZU in Prague. The plants were grown at a temperature of 25°C in daytime and 18°C at night under natural light conditions. They were grown in containers of size of 11x11 cm in a mixture of garden substrate A and silica sand in the ration 2:1. The experimental scheme included two variants - control and stressed. The control group of plants was watered, and the second half of plants was left under stress for 22 days, when the water deficit was induced by gradual drying for one month, the experiment took place from 1.6 2015 to 22.6 2015. The speed of gas exchange by plants was measured by apparatus LCpro+. From the values of photosynthesis and transpiration water use efficiency (WUE) and chlorophyll fluorescence were calculated. The gained results proved difference at reaction to water stress between observed kinds of leaf vegetables. The speed of photosynthesis and transpiration of observed plant species was measured, which decreased due to impact of water deficit. The average speed of photosynthesis of stressed plants was the lowest by lettuce (11,16 "mikro"mol CO2.m-2.s-1), contrarily the highest by mangold (13,2"mikro"mol CO2.m-2.s-1). In case of control plants was the lowest speed of photosynthesis noticed by lettuce (12,03"mikro"mol CO2.m-2.s-1) and the highest by mangold (14,00"mikro"mol CO2.m-2.s-1). In comparison with control group, the speed of photosynthesis of lettuce decreased significantly by impact of water deficit (difference make 7,23 %). On the other hand the lowest decrease of photosynthesis from stressed plants 5,93% was noticed for mangold. In case of speed of transpiration, it is possible to note, that the lowest transpiration of control group shows mangold with the average speed of transpiration 1,82 mmol H2O.m-2.s-1, by contrast the highest transpiration was measured by lettuce 3,20 mmol H2O. m-2.s-1. In the case of stressed plants moved the average speed of transpiration between 1,54 mmol H2O.m-2.s-1 for lettuce and 1,79 (mmol H2O.m-2.s-1) for mangold. Also, between control and stressed plants of the same species were found differences, and salad rocket reacted to stress of drought more sensitively and mangold less sensitively. For these two plant species was noted decrease of transpiration in the amount of 23,80% and 1,76%. From the measured value of photosynthesis and transpiration was calculated water use efficiency (WUE). The calculated values show that stressed plants have higher value of WUE in comparison to control plants. The lowest water efficiency from control plants produced salad rocket (6.51 x 10-3), while the highest mangold (10.31 x 10-3). In the case of stressed plants was the lowest value of WUE noted for salad rocket (8.96 x 10-3), while for mangold was the highest (10.71 x 10-3). Chlorophyll fluorescence of the experimental plants was also measured. This characteristic was not influenced by plant species, because in case of control plants, there were no differences found between observed plant species. The lowest difference in value of fluorescence had plants of lettuce (0,69) while the highest mangold and salad rocket (0,7). In conclusion it is possible to note, that more sensitive to water deficit are plants of lettuce. As more tolerant to water deficit seems mangold and salad rocket.
450

Vliv vodního stresu na rychlost výměny plynů a fluorescence vybraných druhů tribu Panicoideae / Effect of water stress on gas exchange and fluorescence of selected species of tribe Panicoideae

Hrkotová, Kristýna January 2016 (has links)
Summary The thesis studied the effect of water deficit on gas exchange in young plants sorghum and foxtail. These crops could replace maize cultivation in some areas, because their use is similar. Our country is currently facing shortage of rainfall. In 2015, this phenomenon was very noticeable. Therefore, it is appropriate to see how the plants of sorghum and foxtail respond to water deficit during their ontogenetic development. On the water deficit are very sensitive plants in the early stages of growth, and therefore the influence of water deficit was observed on young plants of sorghum and foxtail. Plant genotypes 121, 304, Ruzrok Red and Plant foxtail were divided into four variants: KK (fully irrigated throughout the experiment) KS (14 days full of grout, 10 days water deficit, 4 days full dressing), SK (10 days water deficit, 18 days full of dressing), SS (10 days water deficit, four days filled with grout, water deficit 10 days, four days full of topping). The speed of exchange of gases were measured in the greenhouse device LCpro+ and chlorophyll fluorescence apparatus OS1 - FL. The rate of photosynthesis and transpiration and chlorophyll fluorescence were measured in the morning. The difference between the measured values of the rate of photosynthesis and transpiration value was calculated water use efficiency (WUE). Most sensitive to water deficit responded genotype 121 which had a value of water use efficiency (WUE) 9.95 (10-3) and also had the genotype and the lowest value of chlorophyll fluorescence and 0.765. Resistant to water deficit seems foxtail plants, which had the lowest photosynthesis difference between control and stressed variant in the range of 14.59 mikromol CO2.m-2.s-1 (SS) to 15.38 mikromol CO2.m-2.s-1 (KK). At the same time it also foxtail lowest difference between chlorophyll fluorescence variant KK (0.814) and SS variant (0.781). From the perspective of transpiration as most resistant to water deficit appeared foxtail (0.08 mmol H2O.m-2.s-1 (SS) to 2.13 mmol H2O.m-2.s-1 (KS)). Conversely, the least resistant genotype was 121, which was in the control variant 1.17 mmol H2O.m-2.s-1 and stressed 1.50 mmol H2O.m-2.s-1.

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