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Detectors for medical radioisotope imaging: demands and perspectives

Lopes, M. I.; Chepel, V.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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Radioisotope imaging is used to obtain information on biochemical processes in living organisms, being a tool of increasing importance for medical diagnosis. The improvement and expansion of these techniques depend on the progress attained in several areas, such as radionuclide production, radiopharmaceuticals, radiation detectors and image reconstruction algorithms. This review paper will be concerned only with the detector technology.; http://www.sciencedirect.com/science/article/B6TVT-4CP680G-1/1/4fc260df1037b7b471dbcc77052dccaf

O emprego de radioisótopo na avaliação da permeabilidade dentinária intracanal tendo como variáveis as soluções irrigadoras e a irradiação com diferentes lasers; Polietileneglycol 400 marked with Technetium-99m to evaluate the intracanal dentin permeability taking variables as the irrigation solutions and irradiation with different lasers

Yamamoto, Angela Toshie Araki
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 12/02/2008 PT
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O objetivo deste experimento foi avaliar as variações da permeabilidade dentinária do sistema endodôntico produzidas pelo protocolo de irrigação intracanal: ácido cítrico a 15%, EDTA-T a 17%, MTAD, Smear Clear e NaCl 0,9% e a influência de diferentes lasers: Diodo, Er:YAG, Nd:YAG, utilizando para isso o radioisótopo Tecnécio-99m (99m Tc) (PARTE a) e o polietilenoglicol 400 (PEG 400) marcado 99m Tc (PARTE b). Foram selecionadas 150 raízes palatinas de molares superiores, divididas em 5 grupos, com 10mL/amostra para realizar a irrigação. Inicialmente analisou-se 10 raízes de cada grupo, introduzindo-se 5?L de 99m Tc no canal radicular, sendo então imersos em NaCl 0,9%, com exceção da superfície da entrada do canal para realizar a contagem da quantidade de radioisótopo dissociado para o meio externo (salina), sendo que se realizou os mesmos procedimentos com a introdução de PEG marcado (5?ci) no canal radicular. Posteriormente, cada um dos grupos experimentais foram subdivididos em outros 3 para irradiação com os diferentes lasers: Diodo (1,5W, modo contínuo, fibra de 300?m de diâmetro); Er:YAG [100mJ (42mJ output),1W, 10Hz, fibra com 0,375?m]; Nd:YAG (100mJ, 1,5Hz, 15W, fibra com 300?m). Repetindo-se os mesmos procedimentos primeiramente com 99m Tc livre e posteriormente o PEG400 marcado com 99m Tc para a realização para a contagem do radioisótopo dissociado na solução salina. Os dados obtidos foram tabulados e a analisados estatisticamente pelo teste Tukey com 95% de confiança. Pôde-se concluir que a irradiação com laser Nd:YAG + irrigação com ácido cítrico...

Estudo da permeabilidade, limpeza e contaminação do sistema de canais radiculares, após o preparo químico-cirúrgico e aplicação de laser de alta intensidade; Study of the variation of permeability, cleaning and contamination of the root canal system after preparation and application of highintensity laser

Salgado, Ricardo Julio Cabrales
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 17/04/2009 PT
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A importância do aumento da permeabilidade e da limpeza da dentina radicular está ligada à melhora da sanificação e obturação do sistema de canais radiculares. Este estudo teve como objetivo, avaliar as variações da permeabilidade dentinária radicular de dentes humanos, após o preparo químico-cirúrgico e irradiação com laseres de Er: YAG, Nd:YAG, por meio da utilização do radioisótopo 99mTc livre, assim como, analisar, valendo-se da microscopia eletrônica de varredura (MEV) a limpeza, contaminação e aderência bacteriana valendo-se de inoculação de Enterococcus faecalis. Trinta raízes palatinas de primeiros pré-molares superiores humanos hígidos e foram preparadas pela técnica seriada. Posteriormente, foram divididas, aleatoriamente, em 3 grupos experimentais com 10 raízes cada: G1 - controle, G2 - irradiação com laser de Er:YAG e G3 - irradiação com laser de Nd:YAG. As amostras preparadas receberam quantidade suficiente de 99mTc livre no interior do canal radicular para o prenchimento do mesmo e colocadas em tubos de ensaio contendo 1mL de solução salina. Após 1 hora, a contagem do isótopo radioativo (99mTc) foi realizada. Findo esse período, 3 raízes foram processadas para análise da limpeza dentinária radicular por MEV e os canais radiculares das 7 raízes restantes foram contaminados com Enterococcus faecalis por 21 dias. A presença e aderência microbiana foram constatadas e avaliadas por fotomicrografias eletrônicas. O tratamento estatístico dos dados permitiu concluir que a o G3 provocou uma diminuição significativa da permeabilidade dentinária radicular; o G2 e o G1...

Avaliação in vitro da infiltração de fluidos pela interface implante-pilar intermediário de três sistemas com conexão do tipo cone Morse e da capacidade de vedação de um material; In vitro evaluation of fluid penetration at the implant-abutment interface of three cone Morse systems and sealing ability of a material

Moraes, Flavia Maria Lopes de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/09/2010 PT
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A infiltração de fluido e bactérias nos espaços internos dos implantes foi observada em pilares intermediários parafusados, tanto em situações in vitro quanto in vivo devido à microfenda existente entre o implante e o pilar intermediário. Esse fato pode estar relacionado com a inflamação dos tecidos periimplantares e também com a produção de mau odor. O objetivo do presente estudo in vitro foi avaliar e comparar a ocorrência de infiltração de fluidos pela interface implante-pilar intermediário em três sistemas de implante com conexão do tipo cone Morse, e a capacidade de vedação de um adesivo anaeróbico, utilizando o radioisótopo Tecnécio-99m como marcador. Na primeira etapa, dez conjuntos implante-pilar intermediário de cada sistema foram imersos em solução contendo esse marcador, após a aplicação do torque recomendado pelo fabricante, e foram mantidos em pressão constante de 2 atm por um minuto. Na segunda etapa, um adesivo anaeróbico foi aplicado no pilar intermediário antes do mesmo ser parafusado ao seu respectivo implante. Após a aplicação da pressão, o infiltrado presente no interior dos implantes foi coletado com pontas de papel. Esse material foi depositado em tubos de ensaio para posterior leitura da radioatividade presente. A infiltração de fluido pela interface implante-pilar intermediário mostrou ser um fenômeno mensurável em todas as amostras dos três sistemas de implante com conexão do tipo cone Morse testados. A quantidade de infiltrado variou entre os sistemas e entre as amostras. A inconstância das amostras foi observada em todos os sistemas...

Avaliação da variabilidade espacial do fallout do 'ANTPOT.7Be'; Evaluation of 'ANTPOT.7Be' fallout spatial variability

Pinto, Victor Meriguetti
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/09/2011 PT
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O radioisótopo cosmogênico 'ANTPOT.7Be' é produzido por interações de partículas cósmicas com átomos da atmosfera, e vem sendo usado como traçador em estudos de erosão do solo e de processos climáticos. Após a formação, o 'ANTPOT.7Be' liga-se as partículas dos aerossóis presentes na atmosfera e é depositado na superfície terrestre com outras espécies de isótopos cosmogênicos pelas chuvas. Devido à grande afinidade com as partículas do solo e a meia vida curta de 53,2 dias, este radioisótopo acompanha os processos erosivos do solo e pode ser usado como traçador para estimar taxas de erosão e deposição de sedimentos durante um evento de chuva isolado ou conjunto de eventos de chuva erosivos de curta duração. Uma hipótese fundamental para a avaliação da redistribuição do solo através do 'ANTPOT.7Be' é a uniformidade da distribuição espacial do seu fallout. O método do 'ANTPOT.7Be' foi elaborado recentemente e por isso aplicado em poucas situações, de forma que muitos assuntos em relação ao método ainda não foram propriamente estudados, e algumas hipóteses, como da uniformidade do fallout do 'ANTPOT.7Be', precisam ser avaliadas. O principal objetivo deste estudo foi avaliar a distribuição espacial do fallout do 'ANTPOT.7Be' analisando-se as atividades dos 5 mm iniciais da água da chuva de eventos isolados. Os eventos de chuva foram amostrados em doze pontos de coleta distribuídos em uma área experimental de aproximadamente 300 m² e localizada no campus da Universidade de São Paulo...

Antimalarial drug susceptibility testing of Plasmodium falciparum in Brazil using a radioisotope method

Cerutti Junior,Crispim; Marques,Christiane; Alencar,Filomena EC de; Durlacher,Rui Rafael; Alween,Anna; Segurado,Aluísio AC; Pang,Lorrin W; Zalis,Mariano G
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/1999 EN
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From March 1996 to August 1997, a study was carried out in a malaria endemic area of the Brazilian Amazon region. In vivo sensitivity evaluation to antimalarial drugs was performed in 129 patients. Blood samples (0.5 ml) were drawn from each patient and cryopreserved to proceed to in vitro studies. In vitro sensitivity evaluation performed using a radioisotope method was carried out with the cryopreserved samples from September to December 1997. Thirty-one samples were tested for chloroquine, mefloquine, halofantrine, quinine, arteether and atovaquone. Resistance was evidenced in 96.6% (29/30) of the samples tested for chloroquine, 3.3% (1/30) for quinine, none (0/30) for mefloquine and none for halofantrine (0/30). Overall low sensitivity was evidenced in 10% of the samples tested for quinine, 22.5% tested for halofantrine and in 20% tested for mefloquine. Means of IC 50 values were 132.2 (SD: 46.5) ng/ml for chloroquine, 130.6 (SD: 49.6) ng/ml for quinine, 3.4 (SD: 1.3) ng/ml for mefloquine, 0.7 (SD: 0.3) ng/ml for halofantrine, 1 (SD: 0.6) ng/ml for arteether and 0.4 (SD: 0.2) ng/ml for atovaquone. Means of chloroquine IC 50 of the tested samples were comparable to that of the chloroquine-resistant strain W2 (137.57 ng/ml) and nearly nine times higher than that of the chloroquine-sensitive strain D6 (15.09 ng/ml). Means of quinine IC 50 of the tested samples were 1.7 times higher than that of the low sensitivity strain W2 (74.84 ng/ml) and nearly five times higher than that of the quinine-sensitive strain D6 (27.53 ng/ml). These results disclose in vitro high resistance levels to chloroquine...

Radioisotope Assay for the Quantification of Sulfate-Reducing Bacteria in Sediment and Water

Sand, Mark D.; LaRock, Paul A.; Hodson, Robert E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1975 EN
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A radioisotope enrichment culture method was developed to estimate the physiologically active component of a population of sulfate-reducing bacteria in environmental water and sediment samples. Aliquots of water or sediment were added to 50-ml serum bottles filled with 35S-sulfate broth incubated for approximately 30 h. After incubation, the disintegration rate per milliliter of spent medium was measured, and the percentage of loss of activity resulting from bacterial sulfate reduction was determined. This loss of sulfate from the medium was then translated to a specific number of Desulfovibrio desulfuricans cells that would reduce an equivalent amount of sulfate in the same incubation time. This comparison was done using a series of growth curves of D. desulfuricans covering a range of inoculum densities between 102 and 107 cells. The radioassay was used to follow the effects of a pulp mill on a small anoxic river in Florida. The activity of the sulfate-reducing bacteria in the river was greatly suppressed when the mill was closed for annual maintenance. The initiation of waste treatment resulted in improved water quality in 1 week, but the river sediments required a month to show a 10-fold reduction in the population of sulfate-reducing bacteria.

INTRACORPOREAL HEAT DISSIPATION FROM A RADIOISOTOPE-POWERED ARTIFICIAL HEART

Huffman, Fred N.; Hagen, Kenneth G.; Whalen, Robert L.; Fuqua, John M.; Norman, John C.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //1974 EN
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The feasibility of radioisotope-fueled circulatory support systems depends on the ability of the body to dissipate the reject heat from the power source driving the blood pump as well as to tolerate chronic intracorporeal radiation. Our studies have focused on the use of the circulating blood as a heat sink. Initial in vivo heat transfer studies utilized straight tube heat exchangers (electrically and radioisotope energized) to replace a segment of the descending aorta. More recent studies have used a left ventricular assist pump as a blood-cooled heat exchanger. This approach minimizes trauma, does not increase the area of prosthetic interface with the blood, and minimizes system volume. Heat rejected from the thermal engine (vapor or gas cycle) is transported from the nuclear power source in the abdomen to the pump in the thoracic cavity via hydraulic lines. Adjacent tissue is protected from the fuel capsule temperature (900 to 1200°F) by vacuum foil insulation and polyurethane foam. The in vivo thermal management problems have been studied using a simulated thermal system (STS) which approximates the heat rejection and thermal transport mechanisms of the nuclear circulatory support systems under development by NHLI. Electric heaters simulate the reject heat from the thermal engines. These studies have been essential in establishing the location...

Comparison of the radioisotope dilution-coated charcoal method and a microbiological method (L. leichmannii) for measuring vitamin B12 in serum

Raven, J. L.; Walker, P. L.; Barkhan, P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1966 EN
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A comparison has been made of the radioisotope dilution-coated charcoal method and a microbiological assay (with L. leichmannii as test organism) for determining the concentration of vitamin B12 in serum. A satisfactory correlation was found between the results of the two methods. Under appropriate conditions the reproducibility of the radioisotope method compared favourably with that of the microbiological method.

Forms of vitamin B12 in radioisotope dilution assays.

Begley, J A; Hall, C A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1981 EN
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Since the presence of analogues of vitamin B12 (B12, cobalamin, Cbl) has been postulated as the basis for the high values obtained by some radioisotope dilution assays (RIDA) of serum Cbl we examined serum for analogues. None could be demonstrated in the extracts of serum prepared for RIDA as sought by both direct and indirect techniques. The natural forms of serum Cbl were converted to cyanocobalamin (CN Cbl) by this process of extraction which included cyanide (CN). The correctly performed RIDA for Cbl based on R binder gave higher values than a RIDA based on intrinsic factor or than by bioassay. By exclusion, the difference appeared to be due to unidentified factors rather than the presence of analogues.

d-3-Hydroxybutyrate dehydrogenase from Rhodopseudomonas spheroides. Kinetics of radioisotope redistribution at chemical equilibrium catalysed by the enzyme in solution

Preuveneers, M. J.; Peacock, D.; Crook, E. M.; Clark, J. B.; Brocklehurst, K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1973 EN
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1. The reversible NAD+-linked oxidation of d-3-hydroxybutyrate to acetoacetate in 0.1m-sodium pyrophosphate buffer, pH8.5, at 25.0°C, catalysed by d-3-hydroxybutyrate dehydrogenase (d-3-hydroxybutyrate–NAD+ oxidoreductase, EC 1.1.1.30), was studied kinetically at chemical equilibrium by monitoring radioisotope redistribution with sodium dl-hydroxy[3-14C]butyrate and [4-3H]NAD+(labelled in the nicotinamide ring). 2. When all substrates are maintained at concentrations approaching saturation (approx. 3–50 times the Km values) the first-order rate constant for the enzyme-catalysed interconversion of NAD+ and NADH is much smaller than that for the enzyme-catalysed interconversion of d-3-hydroxybutyrate and acetoacetate. 3. The rate of interconversion of NAD+ and NADH increases initially with increasing concentrations of d-3-hydroxybutyrate and acetoacetate (ratio of concentrations maintained constant), passes through a maximum and approaches closely to zero at saturating concentrations of the latter substrates. 4. The rates of interconversion of NAD+ and NADH and of d-3-hydroxybutyrate and acetoacetate increase with increasing concentration of NAD+ (up to 66 times its Km value) and NADH (up to 180 times its Km value) (ratio of the concentrations of the nicotinamide nucleotides maintained constant). 5. These findings support the description of this catalysis as an ordered Bi Bi mechanism with no detectable alternative pathway...

The estimation of galactose, mannose and fucose in glycoproteins by radioisotope dilution

Graham, E. R. B.; Neuberger, A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1968 EN
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1. The principle of radioisotope dilution, as used previously for the estimation of mannose in egg albumin, was applied on a semi-micro scale to the estimation of fucose, mannose and galactose in some glycoproteins. The sugars were separated by partition chromatography on columns of Celite 545. 2. The release of mannose from egg albumin in 2n-hydrochloric acid at 100° after various times was determined by the radioisotope-dilution method and found to have a half-time of 7min. 3. The destruction of mannose in 2n-hydrochloric acid after 3hr. at 100° was found to be small if air was excluded. The destruction was slightly increased by the presence of lysozyme containing tryptophan in an amount equimolar with the mannose. The same amount of free tryptophan caused considerable loss of mannose. 4. Analytical values are reported for the non-amino sugar contents of egg albumin, rabbit γ-globulin and some samples of blood-group-specific substances. The values found were similar to the most reliable estimates published previously.

Effective Treatment of Established Human Breast Tumor Xenografts in Immunodeficient Mice with a Single Dose of the α-Emitting Radioisotope Astatine-211 Conjugated to Anti-HER2/neu Diabodies

Robinson, Matthew K.; Shaller, Calvin; Garmestani, Kayhan; Plascjak, Paul S.; Hodge, Kathryn M.; Yuan, Qing-An; Marks, James D.; Waldmann, Thomas A.; Brechbiel, Martin W.; Adams, Gregory P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/02/2008 EN
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Successful RAIT strategies depend upon selecting radioisotopes with physical properties complementary to the biological properties of the targeting vehicle. Small, engineered anti-tumor antibody fragments are capable of rapid, highly specific tumor targeting in immunodeficient mouse models. We hypothesized that their rapid systemic elimination would make them ideal radioisotope carriers for the radioimmunotherapy (RAIT) of established tumors. The C6.5 diabody, a non-covalent anti-HER2 single-chain Fv dimer, has a T1/2 α (equilibration phase) of 0.7 hrs, a T1/2 β (elimination phase) of 6 hrs, and a T1/2 in tumor of approximately 30 hrs that favors the use of short-lived radioisotopes. In particular, the α-particle emitting radioisotope 211At (T1/2 = 7.2 hrs) was hypothesized to be very promising for diabody-directed RAIT. This hypothesis was tested in immunodeficient nude mice bearing established HER2/neu positive MDA-MB-361/DYT2 tumors treated with 211At-SAPS C6.5 diabody (N-succinimidyl N-(4-[211At]astatophenethyl)succinamate-C6.5 diabody) at or below the maximum tolerated dose. A single i.v. injection of 211At-SAPS C6.5 diabody lead to a 30 day delay in tumor growth when a 20 µCi dose was administered and a 57 day delay in tumor growth (60% tumor free after one year) when a 45 µCi dose was employed. Treatment of mice bearing the same tumors with 211At-SAPS T84.66 diabody targeting the carcinoembryonic antigen (CEA) at the same doses led to a delay in tumor growth...

PROGRESS ON 241Am PRODUCTION FOR USE IN RADIOISOTOPE POWER SYSTEMS

BAKER S.r.; BELL K.j.; BROWN J.; CARRIGAN C; CARROTT Michael; GREGSON C; CLOUGH M; MAHER C.j.; MASON C; RHODES C.j.; RICE T.g.; SARSFIELD Mark; STEPHENSON K; TAYLOR R.j.; TINSLEY T.p.; WOODHEAD D.a; WISS Thierry
Fonte: European Space Agency Publicador: European Space Agency
Tipo: Contributions to Conferences Formato: CD-ROM
ENG
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Electrical power sources used in outer planet missions are a key enabling technology for data acquisition and communications. Power sources generate electricity from the thermal energy from alpha decay of the radioisotope 238Pu via thermo-electric conversion. Production of 238Pu requires specialist facilities including a nuclear reactor and reprocessing plants that are expensive to build and operate, so naturally, a more economical alternative is attractive to the industry. Within Europe 241Am is a feasible alternative to 238Pu that can provide a heat source for radioisotope thermoelectric generators (RTGs) and radioisotope heating units (RHUs). As a daughter product of 241Pu decay, 241Am is present at 1000s kg levels within the UK civil plutonium stockpile. A chemical separation process is required to extract the 241Am in a pure form and this paper describes such a process, successfully developed to the proof of concept stage.; JRC.E.3-Materials research

Feasibility study and system architecture of radioisotope thermoelectric generation power systems for usmc forward operating bases

Langham, Ryan C.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
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Approved for public release; distribution is unlimited; This study sought to identify the feasibility of utilizing a radioisotope thermal (thermoelectric/stirling) generator to provide power to a deployed USMC Expeditionary Force. The conceptual system architecture was constructed through use of the systems engineering process, identifying necessary subsystems and integration boundaries. Radioisotope comparison was then performed, utilizing weighted design factors. It was determined that Sr-90, Cs-137, and Cm-244 would be the most effective fuel sources for this mission area. By analyzing current thermoelectric technology, it was determined that maximum system efficiency is limited to 1015 percent when utilizing available lead telluride thermoelectrics. Barriers to development of identified physical subsystem components were then identified, including health and environmental hazards of potential isotopes, as well as shielding criteria. The system development was found to be feasible and additional design work and development work is proposed.

Radioisotope determination of regional colonic transit in severe constipation: comparison with radio opaque markers.

van der Sijp, J R; Kamm, M A; Nightingale, J M; Britton, K E; Mather, S J; Morris, G P; Akkermans, L M; Lennard-Jones, J E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1993 EN
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Radio-opaque markers have a well established role in distinguishing between patients with normal and those with slow intestinal transit, but in the latter group their accuracy in defining the region of delay has not been established. To study regional colonic transit accurately the transit of a radioisotope labelled meal was determined and findings were compared with those of simultaneously ingested radio-opaque markers. Twelve healthy controls (mean age 33 years) and 12 severely constipated women (mean age 36 years, bowel frequency < once per week) were studied On day 1, a meal containing 10 MBq 111In bound to 0.7 mm resin microspheres was ingested. Subjects also ingested a set of radiologically distinguishable markers on three successive days. Abdominal scans were obtained three times daily for 7 days. Abdominal radiographs were obtained after 72 or 96 hours and again at 144 or 168 hours. Eight 'regions of interest' were created--one for the small bowel, six for the colon, and one for excreted stool. The constipated patients all showed colonic transit outside the normal range, with a variable site of delay demonstrated by time activity curves for each region. To provide a different measure of the effectiveness of colonic transport...

Demonstration of a new technique using radioisotope tracers to measure the backside wear rate on tibial inserts

Warner, Jacob A; Gladkis, Laura; Smith, Paul; Scarvell, Jennie; Timmers, Heiko
Fonte: Springer Science+Business Media Publicador: Springer Science+Business Media
Tipo: Artigo de Revista Científica
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Local backside wear measurements on ultrahigh molecular weight polyethylene (UHMWPE) tibial inserts in LCS mobile bearing knee prostheses have been performed using a new radioisotope tracing technique. The radioisotope tracers97Ru and101mRh were synthesiz

Probing the Indium Nitride Lattice Locally with the Radioisotope Probe 111In/Cd

Timmers, Heiko; Dogra, Rakesh; Shrestha, Santosh K; Edge, A. Vernon; Byrne, Aidan
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
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The lattice structure of both InN grains with submicron dimensions and a MBE-grown InN film have been studied with the radioisotope probe 111in/Cd and Perturbed Angular Correlation spectroscopy. The quadrupole interaction frequency of the probe in this ma

Analyse de différents facteurs conditionnant les échanges alimentaires dans une colonie d'abeilles Apis mellifica L. au moyen d'un radioisotope; A radioistope to analyse the various factors conditioning food exchanges in a colony of honeybees Apis mellifica L.

Pershad, Shobba B.
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Thesis or Academic Theses
FR; FRANçAIS ; ENGLISH
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TABLE DES MATIERES : Matériel et méthode. L'influence de l'âge sur les échanges de nourriture entre les ouvrières. L'influence de la durée et de la température sur les échange alimentaires. L'influence du nombre des abeilles présentes dans un groupe sur la répartition de la nourriture. Les échanges de nourriture entre des ouvrières appartenant à des colonies différentes. Transit intestinal et localisation du phosphore 32 dans le corps d'une abeille. Echanges de nourriture entre les ouvrières et les reines vierges et fécondes. Conclusions. /// CONTENTS: Material and method. Influence of age on food exchanges between workers. Influence of duration and temperature on food exchanges. Influence of the number of bees within a group on food dispaching. Food exchanges between workers belonging to different colonies. Intestinal transit and localisation of phosphore 32 in a bee body. Food exchanges between workers and virgin or fecund queens. Conclusions.; Thèse de Doctorat

Effects of ionizing radiation on nanomaterials and III-V semiconductor devices.

Cress, Cory
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Dissertação
EN_US
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Devices based on III-V semiconductors and nanomaterials are expected to be critical components of future microsystems as the demand for greater functionality, range of application, and robustness continue to increase. There currently is a need for small-scale power supplies which can be used to power microsystems thereby enabling autonomous functionalities. The use of III-V semiconductor-based solid state devices and nanomaterials to convert the radiant energy of a radioisotope source into electricity has been investigated as a viable option to fulfill this demand. The energy imparted to a material by incident alpha-particles, resulting in electron-hole pair formation and ionization, may be converted into usable electrical power by a radioisotope microbattery (RIMB). A model describing the spatially varying rate of ionizing energy deposited in an absorber material held in close proximity to an isotropic alpha-emitting radioisotope source has been developed. The alpha-particle energy deposition model (ADEP) allows the total energy exciting the RIMB devices to be calculated and thereby provides a means to determine the efficiency of the experimentally measured devices. Two RIMB designs are investigated including a direct conversion microbattery based on a nipi-diode structure and an indirect conversion microbattery employing radioluminescent nanophosphors. The multi-functional nature of microsystems may best be exploited by deploying them in extreme environments...