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Objective: The objective was to investigate the law of three-dimensional thermal field radiation of ceramic slot microwave (CSMW) ablation antenna. Materials and Methods: First, microwave ablation experiments were performed with phantom and temperature data were collected. Second, the specific absorption rate distribution function of microwave (MW) ablation antenna was fit. Third, the MW ablation thermal field morphology was simulated based on the rapid simulation method. In addition, to determine the thermal field simulation accuracy, comparative analysis on the ablation morphology of forty clinical patients with liver cancer receiving percutaneous treatment was conducted. Results: Regarding the ablation morphology, the CSMW ablation antenna had greater long and transverse diameters and ablation volume than the polytetrafluoroethylene slot microwave (PSMW) ablation antenna (P < 0.05). Compared with the actual ablation morphology in clinical practice, the error rate in long and transverse diameters of the simulated morphology of thermal field was up to 5% and the minimum was 1.2%, whereas the maximum volume error rate was up to 9.8%. Conclusion: The CSMW ablation antenna had a greater long diameter, transverse diameter, and volume regarding the ablation morphology than the PSMW ablation antenna, and the thermal field morphology obtained based on the rapid simulation algorithm had a high accuracy
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This article aimed to evaluate land surface temperature using MOD11A2 (Terra satellite) with spatial resolution of one kilometre, compares its findings with land surface temperature data gathered by conventional meteorological stations, and, finally, investigates relations between land surface temperature and synoptic systems events that occurred in Rio de Janeiro State between January until December of 2009. The highest surface temperatures recorded by the MOD11A2 product, derived from the MODIS sensor, were found in the Metropolitana, Baixadas Litorâneas, Norte Fluminense and Noroeste Fluminense regions of Rio de Janeiro State and were recorded during the summer, winter and spring seasons. Autumn was the only exception, and this was due to the influence of the coastal environment. The following synoptic systems interfered with the estimated surface temperature produced by the MOD11A2 product for Rio de Janeiro State in 2009: the Madden Julian Oscillation and South Atlantic Convergence Zone in the summer; and Frontal Systems, the South Atlantic Convergence Zone, the Madden Julian Oscillation and the Upper Tropospheric Cyclonic Vortex in spring. The land use and occupation types with the highest surface temperature are: forest, urban area and pasture land in the summer; forest, urban area, agriculture and pasture land in autumn; and urban area and agriculture during spring. The MOD11A2 product showed a drastic decrease of the surface temperature for all land types during winter, especially for forested land.
Este artigo teve como objetivo avaliar a temperatura da superfície do solo usando o satélite MOD11A2 com resolução espacial de um quilômetro, comparar seus resultados com dados de temperatura da superfície terrestre adquiridas por estações meteorológicas convencionais, e, por fim, investigar as relações entre a temperatura da superfície da terra e eventos sistemas sinóticos que ocorreram no Estado do Rio de Janeiro entre janeiro até dezembro de 2009. As temperaturas mais elevadas da superfície obtidas pelo produto MOD11A2, derivado do sensor MODIS, foram encontrados nas regiões Metropolitana, Baixadas Litorâneas, Norte Fluminense e Noroeste Fluminense do Estado do Rio de Janeiro e foram registradas durante as estações de verão, inverno e primavera. O outono foi a única exceção devido à influência do ambiente costeiro. Os seguintes sistemas sinóticos interferiram na temperatura da superfície estimada pelo produto MOD11A2 para Estado do Rio de Janeiro em 2009: a Madden Julian Oscillation e Zona de Convergência do Atlântico Sul no verão; Sistemas frontais, a Zona de Convergência do Atlântico Sul, o Madden Julian Oscillation e o Alto Ciclone Vortéx Troposférico na primavera. Os tipos de uso e ocupação do solo com a temperatura da superfície mais alta são: floresta, área urbana e terras de pastagem no verão; floresta, área urbana, agricultura e pastagens no outono; área urbana e na agricultura durante a primavera. O produto MOD11A2 mostrou diminuição drástica da temperatura da superfície para todos os tipos de solo durante o inverno, especialmente para terrenos florestais.
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Soil , Temperature , Remote Sensing TechnologyABSTRACT
Objective To compare the features of different heating modes cauterization mode and standard ablation mode of Cool-tip on coagulation zone and thermal field distribution in order to provide references for focused and accurate vascular occlusion and explore the primary efficacy of Cool-tip applied to intrahepatic vascular occlusion in living dogs Methods Ex-vivo porcine livers were ablated for 2 4 6 8 minites with cauterization mode and standard ablation mode respectively and the long- and short-axis diameters in the greatest dimension were compared The tissue temperature around the tip midpoint and end of the exposed part of radiofrequency electrode were measured under the circumstance of 4 min ablation by the two modes respectively Animal experiment the intrahepatic vessels of 2 Beagles were ablated with cauterization mode one procedure for each animal and contrast-enhanced ultrasound was used to evaluate the perfusion change of liver tissue Gross anatomy and pathological examination of the liver was performed after 1 week Results In the 2 min 4 min 6 min and 8 min ablation the coagulation volume of cauterization mode and standard ablation mode were 1 01 ± 0 41 cm 3 vs 2 95 ± 0 74 cm 3 1 47 ± 0 33 cm 3 vs 5 03±1 06 cm 3 2 29±0 49 cm 3 vs 9 23±2 53 cm 3 2 70±0 24 cm 3 vs 1 5 89±0 77 cm 3 The coagulation volume was significant smaller in cauterization mode than in standard ablation mode P <0 05 for all The peak temperature of cauterization mode presented on the tip of electrode which averaged 94 4℃ in maximum and maintain around 70 ℃ in the equilibrium phase The peak temperature of standard mode presented on the midpoint of the electrode which periodically variated between 70 ℃- 100 ℃ The result of the animal experiment showed that cauterization mode could be used to occlude the intrahepatic vessel in vivo which induced the ischemia and necrosis in the corresponding area Conclusions Cauterization mode and standard alation mode of Cool-tip have different characteristic in terms of coagulation zone and thermal distribution and carterization mode may have a promising application in intrahepatic vascular occlusion.
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Objective To explore mechanical property changes of methyl vinyl silicone rubber modified by ferric nanoparticles and its dispersed phase.Methods Mechanical properties such as Shore A hardness,tensile strength,elongation at break,tearing rate of permanent deformation and tearing strength of pre-prepared ironic nanoparticle enhanced silicone rubber and carbon-coated ferric particle reinforced silicone rubber were tested according to national standards.A thermal field emission scanning electron microscope (TFE-SEM) was used to investigate the morphology of both surface and fracture of the composite materials and to observe the dispersion of ferric nanoparticles in them.Results Mean values of Shore A hardness,tensile strength,elongation at break,tearing permanent deformation rate and tear strength of modified composites increased with the increasing amounts of ferric nanoparticles,however,when the quota of ironic nanoparticles in the composite formula were greater than 17 phr,carbon-coated ferric nanoparticles more than 19 phr,the mean values of tensile strength of two composites stopped increasing and presented the declining trend.When the quota of ferric nanoparticles in the formula exceeding 15 phr,the mean values of elongation at break and tear strength began to decrease in the formula ratio of silicone rubber/ferric nanoparticles up to 85:15,while the Shore A hardness of samples increased all the way.Ferric nanoparticles dispersed evenly on the surface of composites.Nanopowder aggregation in the fracture surface of both composites could be observed at the formula ratio of 85:15 of silicone rubber/iron nanoparticle and 87:13 of silicone rubber/carbon-coated iron specimen.Conclusion Effect of iron nanapareticles and carbon-coated ferric nanoparticles on the mechanical properties of the reinforced methyl vinyl silicone rubber depends on the nanoparticle size,additive amount and agglomeration.
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Objective To study the laws of heating and thermal field of heating seed arrays in different magnetic field intensity during the magnetic induction hyperthermia.Methods 3.0 cm×3.0 cm ×2.6 cm and 5.0 cm ×5.0 cm×2.6 cm of magnetic heating seed was implanted respectively in 10.0 cm×10.0 cm ×10.0 cm pure agar phantom.The regions was divided into one file per 5 Gs in the range of 60-120 Gs magnetic induction.The temperature measurement experiments were implemented in each sub-file.Muscle-agar mixture model was used in the magnetic induction 60 Gs and 90 Gs to implement GTV-heating simulation experiments and thermal field analysis.Results The pure agar phantom heating experiments show that the heating is of basically the same rule when seeds with various diameters were implanted in the magnetic thermal array.Along with the increase of magnetic induction,the final temperature of the focal point heated for 40 min increased accordingly.and time required for heating to 50℃ was shortened correspondingly.The thermal field analysis of muscle-a mixture agar mixture model showed that the implantation density of magnetic heating seed is closely associated with the temperature of the target area and thermal field in difierent magnetic field intcnsity.Conclusions The magnetic induction has a significant impact on heating of the seeds,as the magnetic modium,and this impact is trending downwards when the magnetic field reaches a certain intensity.Within a certain size,adequate magnetic heating seed density is necessary to achieve the desired temperature required for the temperature value.The heating seeds should be put in a certain order to heat the venue evenly,not in a simply order,but in line with the principle of outer dense and inner sparse.
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Objective To observe the extent of bone coagulation and the thermal field distribution created in ablating the swine vertebral bodies in vitro with multi-polar radiofrequency and to discuss the correlation between the electrode position in the vertebral body and the safety of the spinal cord as well as the soft tissue injury around the vertebral body. Methods Thirty fresh adult porcine vertebrae, were randomly and equally divided into two groups. The depth of the electrode needle was 10 mm or 20 mm. When the ablation process reached to a stable state, the temperature at the scheduled spots was estimated. Twenty minutes after ablation, the vertebral body was cut along the electrode needle plane and also along the plane perpendicular to the electrode needle to observe the extent of bone coagulation. Results The temperature at the scheduled spots reached to a stable state in 3.5 minutes. The more close to the electrode the spot was,the more quickly the temperature rose. No soft tissue injury around the vertebral body was observed in both groups and no spinal cord injury occurred when the electrode needle was 10 mm or 20 mm deep in the vertebral body. Conclusion In treating vertebral metastases, the radiofrequency ablation is safe and reliable if the posterior wall of the vertebral body remains intact.
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INTRODUÇÃO: O ultra-som é um recurso bastante utilizado em Fisioterapia. Entretanto, a aplicação inadequada pode promover aquecimento insuficiente ou causar danos aos tecidos biológicos. Por isso, é importante que se conheçam os parâmetros ótimos para atingir a temperatura adequada, dentro dos limites seguros. A geração de calor é função dos parâmetros do equipamento e das propriedades físicas dos tecidos. Este trabalho apresentou um software que simula a variação da energia e da temperatura nos tecidos ao longo do tempo, permitindo ao usuário visualizar o padrão de aquecimento nos tecidos em função dos parâmetros. MATERIAIS E MÉTODOS: O software foi implementado com base na equação biotérmica, supondo quatro camadas (pele, gordura, músculo e osso), das quais o usuário pode alterar espessura e propriedades acústicas e térmicas. Pode-se também escolher intensidade, freqüência e tempo de aplicação. São apresentados gráficos com o percentual de energia absorvida ao longo da profundidade e a respectiva variação de temperatura por cada milímetro de tecido. RESULTADOS: Foram realizadas simulações exemplificando situações de interesse para a terapia, variando tempo de aplicação, espessura e freqüência do ultra-som. Podem ser observadas as diferenças do padrão de aquecimento, em especial nas fronteiras das interfaces. CONCLUSÕES: O software permitiu o estudo do aquecimento de tecidos biológicos por ultra-som e pode ser usado tanto para fins didáticos como para planejamento de doses de aquecimento, para ondas contínuas. Numa próxima etapa, pretende-se adequá-lo para estimar qual dose deve ser regulada no aparelho, para manter a temperatura desejada pelo tempo escolhido. Software disponível em: http://www.peb.ufrj.br/lus.htm.
INTRODUCTION: Ultrasound is a resource commonly used in Physical Therapy. However, its inadequate application may produce insufficient heating or cause damage to biological tissues. Therefore, the knowledge on the optimum parameters for achieving the appropriate temperature, within safe limits, is necessary. Heat generation depends on equipment parameters and the physical properties of tissues. This study presented a software that simulates the energy and temperature variation in tissues over time, thus allowing users to view the heating patterns in tissues as a function of these parameters. METHODS: The software was implemented based on the bioheat transfer equation for four layers (skin, fat, muscle and bone), in which the user can change the thickness and thermal or acoustic properties of these tissues. The intensity, frequency and time of application can also be chosen. Graphs showing the percentage energy absorption in relation to depth and the respective temperature variation per millimeter of tissue are presented. RESULTS: Simulations were produced to give examples of situations of interest for therapy, by varying the time of application, thickness and ultrasound frequency. Differences in heating patterns are seen, especially at the interfaces. CONCLUSIONS: The software made it possible to study the heating of biological tissues by ultrasound and can be used both for teaching purposes and for planning heating doses for continuous waves. In the future, the software will be adapted, in order to estimate which dose should be regulated in the apparatus to maintain the desired temperature for the time chosen. Software available in: http://www.peb.ufrj.br/lus.htm.