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Utilização da técnica de fluorescência de raios X por dispersão em energia (EDXRF) na avaliação do material particulado em suspensão na cidade de Limeira - SP; Using energy dispersive X ray fluorescence (EDXRF) technique to evaluate the suspended particulate matter from Limeira city, State of São Paulo, Brazil

Moraes, Liz Mary Bueno de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/08/2009 PT
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66.14%
O objetivo principal deste trabalho foi avaliar a composição química do material particulado em suspensão na atmosfera na cidade de Limeira/SP, pela técnica de fluorescência de raios X dispersiva em energia (EDXRF). Um amostrador tipo stacker foi utilizado para coletar particulados fino (partículas com diâmetro aerodinâmico entre 2,5 e 10 'mü'm) e grosso (partículas maiores que 10 'mü'm), utilizando filtros de policarbmüonato de 47 mm de diâmetro e com diâmetros de poro de 0,4 e 8 'mü'm, respectivamente. As amostras foram coletadas em 2006 (de janeiro a dezembro), 2008 (de janeiro a abril e de julho a dezembro) e 2009 (de janeiro a março). Na excitação da técnica de EDXRF utilizou-se um tubo de Mo com filtro de Fe (análise sob vácuo) para a determinação dos elementos do Al ao Ca, e com filtro de Zr (análise sob ar atmosférico) para determinação do Sc ao Zn e também do Pb. Para a detecção dos raios X utilizou-se um detector semicondutor de Si(Li) acoplado a um analisador multicanal, com um tempo de aquisição de 300 s. Os espectros de raios X foram interpretados através do programa AXIL e a para a quantificação dos elementos químicos fez-se o uso da metodologia dos parâmetros fundamentais. Realizou-se também microanálises nas amostras utilizando-se um microscópio eletrônico de varredura acoplado a um sistema de fluorescência de raios X por dispersão em energia (SEM/EDS) para a caracterização química e morfológica das partículas coletadas no material particulado em suspensão. Determinou-se também a concentração de negro de fumo (black carbon) utilizando a técnica de reflectância. Embora a amostragem não tenha sido suficiente para indicar a contribuição de cada fonte de emissão...

Genomics and X-ray microanalysis indicate that Ca2+ and thiols mediate the aggregation and adhesion of Xylella fastidiosa

Leite,B.; Ishida,M.L.; Alves,E.; Carrer,H.; Pascholati,S.F.; Kitajima,E.W.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2002 EN
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66.15%
The availability of the genome sequence of the bacterial plant pathogen Xylella fastidiosa, the causal agent of citrus variegated chlorosis, is accelerating important investigations concerning its pathogenicity. Plant vessel occlusion is critical for symptom development. The objective of the present study was to search for information that would help to explain the adhesion of X. fastidiosa cells to the xylem. Scanning electron microscopy revealed that adhesion may occur without the fastidium gum, an exopolysaccharide produced by X. fastidiosa, and X-ray microanalysis demonstrated the presence of elemental sulfur both in cells grown in vitro and in cells found inside plant vessels, indicating that the sulfur signal is generated by the pathogen surface. Calcium and magnesium peaks were detected in association with sulfur in occluded vessels. We propose an explanation for the adhesion and aggregation process. Thiol groups, maintained by the enzyme peptide methionine sulfoxide reductase, could be active on the surface of the bacteria and appear to promote cell-cell aggregation by forming disulfide bonds with thiol groups on the surface of adjacent cells. The enzyme methionine sulfoxide reductase has been shown to be an auxiliary component in the adhesiveness of some human pathogens. The negative charge conferred by the ionized thiol group could of itself constitute a mechanism of adhesion by allowing the formation of divalent cation bridges between the negatively charged bacteria and predominantly negatively charged xylem walls.

Brazilian gutta-percha points: Part I: chemical composition and X-ray diffraction analysis

Maniglia-Ferreira,Cláudio; Silva Jr,João Batista Araújo; Paula,Regina Célia Monteiro de; Feitosa,Judith Pessoa Andrade; Cortez,Douglas Giordani Negreiros; Zaia,Alexandre Augusto; Souza-Filho,Francisco José de
Fonte: Sociedade Brasileira de Pesquisa Odontológica - SBPqO Publicador: Sociedade Brasileira de Pesquisa Odontológica - SBPqO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2005 EN
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76.38%
Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP and Dentsply FM) were analysed chemically and by X-ray diffraction, and their chemical compositions were compared. The organic fraction (gutta-percha polymer and wax/resin) of the gutta-percha points was separated from the inorganic fraction (ZnO and BaSO4) by dissolving them in chloroform. The gutta-percha polymer was precipitated with acetone. The inorganic fraction was analysed by elemental microanalysis. Energy-dispersive X-ray microanalysis (EDX) and X-ray diffraction were employed to identify the chemical elements and compounds (barium sulfate and zinc oxide). The barium sulfate content was calculated based on the percentage of sulfur found in the elemental microanalysis. All analyses were repeated three times. The means and standard deviations of the percentage by weight of gutta-percha in the points were: Konne (17.6 ± 0.30), Tanari (15.2 ± 0.30), Endopoint (16.7 ± 0.23), Odous (18.8 ± 0.20), Dentsply 0.04 (15.7 ± 0.17), Dentsply 0.06 (16.6 ± 0.17), Dentsply TP (21.6 ± 0.15) and Dentsply FM (16.3 ± 0.23). The means and standard deviations of the zinc oxide content were: Konne (79.9 ± 0.10)...

Distribution of calcium and other elements in cryosectioned Bacillus cereus T spores, determined by high-resolution scanning electron probe x-ray microanalysis.

Stewart, M; Somlyo, A P; Somlyo, A V; Shuman, H; Lindsay, J A; Murrell, W G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1980 EN
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The distribution of a number of key elements in Bacillus cereus T spores was determined by high-resolution scanning electron probe X-ray microanalysis. To circumvent the redistribution of soluble or weakly bound elements, freeze-dried cryosections of spores, which had been rapidly frozen in 50% aqueous polyvinyl pyrrolidone, were employed. The sections were examined by using a modified Philips EM400 electron microscope fitted with a field emission gun, scanning transmission electron microscopy attachment, and a computer-linked energy-dispersive X-ray microanalysis system. X-ray maps for selected elements and the corresponding electron image were produced simultaneously by scanning the cryosections with a fine electron beam in a raster pattern, using the scanning transmission electron microscopy attachment. The results indicated that almost all of the calcium, magnesium, and manganese, together with most of the phosphorus, was located in the core region. An unexpectedly high concentration of silicon was found in the cortex/coat layer. Granules containing high concentrations of calcium, manganese, and phosphorus were demonstrated in spores containing reduced levels of dipicolinic acid. Spot mode analyses, in which a stationary beam was located over the region of interest in the spore cryosection...

Ion Distribution in Roots of Barley Seedlings Measured by Electron Probe X-Ray Microanalysis 1

Pitman, Michael G.; Läuchli, André; Stelzer, Ralf
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1981 EN
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66.17%
The distribution of ions, particularly K and Na, was studied in roots of barley seedlings grown on various ionic solutions. Analyses were made by means of electron probe x-ray microanalysis using frozen, fractured bulk specimens. By this technique, it was demonstrated that there can be variability in the ratio K/Na measured in the vacuoles of cortical cells, with this ratio often being lower in epidermal cells of the root than in the inner cortex. A sharp difference in the K/Na ratio was also found between cells of the endodermis and those of the adjacent cortex, and generally higher ratios of K/Na occurred in the stele than in the cortex. Estimation of the concentrations in the cytoplasm was at the limit of resolution of this technique, but it can be shown that the K/Na ratio in the cytoplasm was higher than that in the vacuole. In low salt roots, the K concentration in the cytoplasm was higher than that in the vacuoles. The results with the x-ray microprobe confirm other measurements based on flux analysis or analysis of small samples of the root.

Scanning electron microscopy and x-ray microanalysis of mineral deposits in lungs of a patient with pleural mesothelioma.

Ophus, E M; Mowé, G; Osen, K K; Gylseth, B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1980 EN
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66.13%
Scanning electron microscopy of lung tissue, ashed at low temperature, and obtained from an insulation worker who had died of pleural mesothelioma, showed the presence of numerous inorganic particles and fibres. A regional variation in fibre concentration in different tissue samples was found, and the size distribution of naked fibres and asbestos bodies was determined. By energy dispersive x-ray microanalysis the fibres were identified mainly as amphibole asbestos. This method also showed the presence of particles containing titanium and of fragments of diatom shells. Despite a mean concentration of 33 x 10(6) fibres per gram of dry tissue no significant lung fibrosis was found.

Quantitative x ray microanalysis of pulmonary mineral particles in a patient with pneumoconiosis and two primary lung tumours.

Anttila, S; Sutinen, S; Pääkkö, P; Alapieti, T; Peura, R; Sivonen, S J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1984 EN
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66.17%
The right upper lung lobe of a 74 year old man was resected for a central tumour. Two primary cancers were found; a central small cell carcinoma and a peripheral squamous cell carcinoma. In addition, the peripheral lung tissue showed generalised peribronchiolar fibrosis extending from the non-respiratory bronchioles to the level of the alveolar ducts. Abundant asbestos bodies and large amounts of black dust were seen around the bronchioles. Pulmonary mineral particles were studied by quantitative energy dispersive x ray microanalysis (EDS) using scanning transmission electron microscopy (STEM). The x ray spectra for mineral particles were measured in thin sections, and the characteristic peak intensities of the elements were converted to weight fractions (in oxides). The results enabled the minerals present to be identified and their presence confirmed by calculating the mineral formula. These originated from nine natural minerals, anthophyllite and chrysotile asbestos, talc, and quartz, feldspars, and muscovite, which are components of sand, and also from two artificial mullites used in fire clay. The exposure history of the patient explained the most likely origins of the minerals detected. The patient had been a mason for 23 years...

Identification of thorium dioxide in human liver cells by electron microscopic x-ray microanalysis.

Odegaard, A; Ophus, E M; Larsen, A M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1978 EN
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66.17%
Thirty-two years after injection of thorium dioxide (Thorotrast) for diagnostic x-ray studies in a female patient deposits were found by light microscopy in the liver macrophages (Kupffer cells). They were shown by electron microscopy to be located inside secondary lysosomes, and by autoradiography and x-ray microanalysis they were identified as thorium.

Hydrogen peroxide changes in ischemic and reperfused heart. Cytochemistry and biochemical and X-ray microanalysis.

Slezak, J.; Tribulova, N.; Pristacova, J.; Uhrik, B.; Thomas, T.; Khaper, N.; Kaul, N.; Singal, P. K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1995 EN
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66.17%
Active oxygen species including hydrogen peroxide (H2O2) play a major role in ischemia-reperfusion injury. In the present study, changes in myocardial H2O2 content as well as its subcellular distribution were examined in rat hearts subjected to ischemia-reperfusion. Isolated perfused rat hearts were made globally ischemic for 20 or 30 minutes and were reperfused for different durations. H2O2 content in these hearts was studied biochemically and changes were correlated with the recovery of function. These hearts were also analyzed for subcellular distribution of H2O2. Optimal conditions of tissue processing as well as incubation medium were established for reacting cerium chloride with H2O2 to form cerium perhydroxide, an insoluble electron-dense product. The chemical composition of these deposits was confirmed by x-ray micro-analysis. Global ischemia caused complete contractile failure in minutes and after 30 minutes of ischemia, these was a > 250% increase in the myocardial H2O2 content. Depressed contractile function recovery in the early phase of reperfusion was accompanied by approximately a 600% increase in the myocardial H2O2 content. Brief pre-fixation with low concentrations of glutaraldehyde, inhibition of alkaline phosphatase...

Three stages of copper accumulation in hepatocellular lysosomes: X-ray microanalysis of copper-loaded golden hamsters.

Yagi, A.; Hayashi, H.; Higuchi, T.; Hishida, N.; Sakamoto, N.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1992 EN
Relevância na Pesquisa
66.17%
Male golden hamsters were loaded with copper by supplying them for up to 12 weeks with drinking water containing 0.5% cupric acetate. The copper feeding increased hepatic copper to widely varying levels. Energy dispersive X-ray microanalysis could always identify a copper-sulphur complex in the hepatocyte lysosomes of copper-loaded hamsters and the X-ray intensity of copper was found to be a reliable parameter to measure in-situ copper accumulation. Combining this parameter with the copper binding ratio expressed by delta Cu/delta S enabled us to discern two stages of sub-histochemical copper accumulation. The first stage was marked by low levels of both lysosomal copper and binding ratio, which suggested that this initial copper transfer was mediated by unsaturated cuproproteins. The second stage was characterized by median amounts of lysosomal copper and a binding ratio of more than 0.50. At the third stage, histochemically detectable copper appeared in animals whose lysosomal copper was extraordinarily high in later experimental periods. With the copper binding ratio being in the same range of 0.50-0.83, it seemed that saturated cuproproteins were the main mediator of copper transport in the later two stages.

X-ray Microanalysis of Pyroantimonate Complexes in Rat Kidney

Tisher, C. Craig; Weavers, Barry A.; Cirksena, W. J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1972 EN
Relevância na Pesquisa
66.26%
X-ray microanalysis was employed to define the cation content of electron-dense pyroantimonate complexes that occur in the proximal tubule of the rat kidney, along the intracellular aspect of plasma membranes and within the interchromatin regions of cell nuclei, when exposed to potassium pyroantimonate [KSb(OH)6] in vivo. Standard micropuncture technics were utilized to perfuse single proximal tubules in vivo with KSb(OH)6 before fixation with a glutaraldehyde-formaldehyde fixative. Unstained, 1000 Å-thin sections cut from Epon-embedded material were viewed directly with transmission electron microscopy and then subjected to x-ray microanalysis to determine their elemental content. Calcium, magnesium and potassium ions, in addition to sodium ions, were also present within the electron dense pyroantimonate complexes. Heavy concentrations of potassium and antimony in unrinsed tissue, presumably in the form of KSb(OH)6. complexes, probably resulted from nonspecific precipitation secondary to exposure to alcohol solutions during dehydration, since KSb(OH)6, is insoluble in alcohol.

Cytochemical and electron probe X-ray microanalysis studies on the distribution change of intracellular calcium in columella cells of soybean roots under simulated microgravity

Hayatsu, Manabu; Ono, Manami; Hamamoto, Chieko; Suzuki, Suechika
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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66.26%
The columella cells of soybean roots grown under gravity and simulated microgravity induced by a clinostat were examined using potassium pyroantimonate (PA) and quantitative X-ray microanalysis of cryosections to determine the role of Ca in the regulation of the gravitropic response. Amyloplasts in the columella cells were localized exclusively at the bottom under gravity, but diffusely distributed in the cytoplasmic matrix under simulated microgravity, thus supporting the statolith theory. In the columella cells, PA precipitates containing Ca were diffusely distributed in the cytoplasmic matrix under gravity. Under simulated microgravity, however, they decreased in number and size in the cytoplasmic matrix, whereas increased only in number in the vacuole, indicating that Ca moved from the cytoplasmic matrix into the vacuole. The vacuole of columella cells contained mostly electron-dense granular structures localized along the inner surface of tonoplasts, which closely resembled the tannin vacuole reported in Mimosa pulvinar motor cells. Under simulated microgravity, their configuration changed dramatically from a granular shape to a flat plate. The quantitative X-ray microanalysis of cryosections showed that the vacuolar electron-dense structures contained a large amount of Ca. Under simulated microgravity...

12.141 Electron Microprobe Analysis, January (IAP) 2003; Electron Microprobe Analysis

Chatterjee, Nilanjan; Grove, Timothy L.
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
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EN-US
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Introduction to the theory of x-ray microanalysis through the electron microprobe including ZAF matrix corrections. Techniques to be discussed are wavelength and energy dispersive spectrometry, scanning backscattered electron, secondary electron, cathodoluminescence, and X-ray imaging. Lab sessions involve hands-on use of the electron microprobe.

A unified Monte Carlo approach for quantitative standardless x-ray fluorescence and electron probe microanalysis inside the scanning electron microscope; Ein Vereinheitlichter Monte-Carlo-Ansatz zur Quantitativen Standardfreien Röntgenfluoreszenz - und Elektronenstrahlmikroanalyse im Rasterelektronenmikroskop

Steinbrecher, Stefan
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
66.17%
The implementation of standardless quantitative X-ray fluorescence analysis to a conventional scanning electron microscope equipped with an X-ray spectrometer is subject of the present work. For this purpose, an optimised sample holder was designed, constructed, successfully characterised and tested, which transfers the operation principle of a transmission-type end-window X-ray tube into the specimen chamber of a scanning electron microscope. The device allows a fast and easy exchange of target, filter, and sample and therefore offers flexible excitation conditions and a high sample throughput. As modifications of the microscope hardware are not necessary, switching between electron microprobe analysis and X-ray fluorescence analysis is easily accomplished. X-ray fluorescence analysis inside the scanning electron microscope offers significantly improved detection limits compared to electron excitation of the X-ray emission spectrum. The analytical results show that in common alloys composed of first row transition metals a two to seven fold decrease of detection limits is achieved. Standardless quantitative trace analysis of heavy elements in a light element matrix is even shown to be possible down to mass concentrations of approximately 3 ppm lead in aluminium corresponding to an atom fraction of only 400 ppb. A Monte Carlo procedure to predict the spectral response of X-ray excited samples is described. An expansion of this procedure to simulate subsequent electron-photon interactions is presented...

Evaluaci??n de la viabilidad celular y patrones apopt??ticos en c??lulas madre aisladas de la pulpa dental humana

Mart??n-Piedra, Miguel A.; Garz??n, Ingrid; S??nchez-Quevedo, Mar??a Carmen; Alaminos, Miguel
Fonte: Real Academia de Medicina y Cirug??a de Andaluc??a Oriental; Universidad de Granada Publicador: Real Academia de Medicina y Cirug??a de Andaluc??a Oriental; Universidad de Granada
Tipo: Artigo de Revista Científica
SPA
Relevância na Pesquisa
66.15%
Introducci??n: El desarrollo de sustitutos biol??gicos mediante Ingenier??a Tisular requiere de la utilizaci??n de una fuente de c??lulas madre que, adem??s de ser capaz de autorenovarse y diferenciarse, mantengan una funcionalidad y viabilidad ??ptima justo en el momento de su uso. El estudio de la viabilidad celular constituye un importante control de calidad, especialmente en aquellas poblaciones celulares con un alto potencial para su utilizaci??n en Ingenier??a Tisular, como son las c??lulas madre de la pulpa dental (DPSC). El objetivo de este trabajo es la evaluaci??n de la viabilidad durante los tres primeros subcultivos de c??lulas madre de la pulpa dental humana (hDPSC). Material y m??todos: Se obtuvieron 3 subcultivos consecutivos de hDPSC de terceros molares humanos sanos (N = 3) mediante un proceso de digesti??n enzim??tica. La concentraci??n intracelular de los iones sodio (Na), potasio (K), y cloro (Cl) fue determinada mediante microscop??a anal??tica por energ??a dispersiva de rayos X (EPXMA). El porcentaje de c??lulas en apoptosis (fragmentaci??n de DNA) fue determinado mediante el ensayo de fluorescencia TUNEL en el primer y tercer subcultivo. Resultados: En el segundo subcultivo se detect?? un descenso significativo del potasio (p = 0...

Estudo comparativo de isolados de Cercospora coffeicola: análises moleculares, bioquímicas e processo infeccioso na interação com cafeeiro

Andrade, Camila Cristina Lage de
Fonte: Universidade Federal de Lavras; Programa de Pós-Graduação em Agronomia/Fitopatologia; UFLA; brasil; Departamento de Fitopatologia Publicador: Universidade Federal de Lavras; Programa de Pós-Graduação em Agronomia/Fitopatologia; UFLA; brasil; Departamento de Fitopatologia
Tipo: Tese de Doutorado
Publicado em 19/10/2015 POR
Relevância na Pesquisa
66.15%
There are few studies on different symptoms of the “common” and the “black” brown eyespot (BE), in field conditions.Thus, the goals this study were 1) characterize strains by phylogenetic studies, to assess the cercosporin production in vitro, aggressiveness and distribution of nutrients in the leaves infected by strains; 2) to assess the reproducibility of lesion type of the “common BE” and the “black BE” disease in greenhouse conditions, through infection process using scanning electron microscopy and quantitative RT-PCR; 3)to investigate whether the biochemical defense response in coffee leaves is similarly induced by the common BE and the black BE. The first study, eight strains were collected from different regions of Brazil and were inoculated in two coffee cultivars under greenhouse conditions. Based on the nucleotide sequence of the elongation factor genes and actin, it was observed that the isolates used in phylogenetic studies grouped into one similar group to the C coffeicola. It was observed that there was difference in the incubation period, area under the curve of disease severity and cercosporin production in vitro regardless of the lesion induced by strains. From these results...

Quantitative histochemistry of phosphorus in the vestibular gelatinous membrane, an electron probe X-ray microanalytical study

López-Escámez, J.A.; Crespo, P.V.; Cañizares, F.J.; Campos, A.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
76.01%
Electron probe X-ray microanalysis was used to study the phosphorus concentration in the otolithic gelatinous membrane of the saccule and the utricle with scanning electron microscopy. The otolithic membranes were plunge-frozen in liquid N2 and freeze-dried. Quantitative analysis was carried out with an energy dispersive detector using the peak-to-background ratio method and different concentrations of KH2P04 salts dissolved in dextran solutions. The otolithic gelatinous membrane consists of a 25- 30 pm-thick layer overlying the cilia of the hair cells. Elements detected in the gelatinous membrane are : Na, P, S, CI, K and Ca. Although Student's t-test did not show significant differences between saccular and utricular concentrations of phosphorus, the distribution of this element in the two organs was different. Regresssion analysis established that the concentrations of phosphorus in the saccular and utricular gelatinous membrane were dependent. The regression equation was: y = 18.02x2 + 133.9 (r = 0.83, P < 0.05) where y is the concentration of phosphorus in the utricle, and x2 the concentration of phosphorus in the saccule. The findings obtained in the present study could be related to structural differences in organic phosphate residues of the phosphoproteins associated to collagen...

X-ray microanalysis as applied to fungal tissues.

Thibaut, M.; Ansel, M.; de Azevedo Carneiro, J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1977 EN
Relevância na Pesquisa
66.28%
Analytical electron microscopy combines the techniques of high-resolution electron microscopy and high-sensitivity X-ray microanalysis of samples. Spectrometry of the elements (characteristic X-rays produced by a scanning electron microprobe) was employed to detect some elements of Mendeleev's classification in pathogenic fungi for humans. X-ray microanalysis applied in wavelength dispersive spectrometry was used to study Coccidioïdes immitis, Paracoccidioïdes brasiliensis and Trichosporum cutaneum.

Scanning Electron Microscopy and X-Ray Microanalysis [Book Review]

Albee, Arden L.
Fonte: American Geophysical Union Publicador: American Geophysical Union
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 23/11/1982
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66.17%
This outstanding volume has managed the nearly impossible task of combining the expertise of all six authors in a lucid and homogeneous style of writing. Subtitled ‘A Text for Biologists, Material Scientists and Geologists,’ the book has evolved from a short course taught each summer at Lehigh University. The book provides a basic knowledge of (1) the electron optics for these instruments a nd their controls, (2) the characteristics of the electron beam-sample interactions, (3) image formation and interpretation, (4) X ray spectrometry and quantitative X ray microanalysis with separate detailed sections on wavelength dispersive and energy dispersive techniques, and (5) specimen preparation, especially for biological materials.

UNDERSTANDING THE CORROSION BEHAVIOR OF 35Ni19Cr ALLOY USING X-RAY MICROANALYSIS

Wong-Moreno,A; López-López,D; Martínez,L
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2001 EN
Relevância na Pesquisa
96.39%
X-ray microanalysis of corroded specimens of 35Ni19Cr austenitic steel was performed in order to understand its oil-ash corrosion behavior. Corrosion testing involved the exposure of the alloy at temperatures in the range of 600°C - 900°C, to a sulfate-rich oil ash, which is also constituted by low melting point sodium vanadates. The curve describing the corrosion behavior as a function of temperature exhibits two relative maximums at 715°C and around 800°C, suggesting that there is an evolution of corrosion mechanisms as temperature is increased. X-ray microanalysis of the corrosion product scale and of the metal subjacent to the interface metal/scale let characterize three corrosion mechanisms prevailing along the temperature range: metallic dissolution caused by molten vanadium compounds, accelerated oxidation and sulfidation. Microanalysis also provided evidence of internal degradation at temperatures above 675°C consisting in internal oxidation, sulfidation or both. It was concluded that the resultant corrosion behavior depends on both: the oxidation, oil-ash corrosion and sulfidation resistance of the alloy, and the stability of the oil ash, which determines the chemical compounds responsible for the corrosion process observed.