Analytical method for 14C in urine / 中华放射医学与防护杂志

Objective:To improve the analytical method of radionuclide 14C, and estimate the internal dose caused by 14C to human, in order to protect the health of workers and the public in workplaces involving potential 14C exposure. Methods:Urine samples were pretreated by wet oxidation. In the analysis, potassium persulfate was used as an oxidant to decompose urea into carbon dioxide, which was absorbed by 1 mol/L sodium hydroxide, and the absorption solution was converted into calcium carbonate precipitation. After calcium carbonate powder was prepared into sample source by suspension method, the low background liquid scintillation counter was applied to measure the radioactivity, which can be used for calculating the result.Results:The reaction time optimized by using carbamide as carrier was 1 h. For 80 ml urine, the amount of potassium persulfate used was 10 g. The method recovery rate reached about 100%. Four real urine samples were tested using the optimized method, and the result of activity concentration 14C was 0.32, 0.60, 0.86 and 0.74 Bq/L, respectively. Conclusions:The optimized method had good stability, high accuracy and stable experimental result, which could meet the needs of routine radiological detection. The establishment of a quantitative method for 14C in urine sample has improved the methodological system for 14C monitoring.

Determination of α-radionuclides in environmental samples by large area grid ionization chamber / 中华放射医学与防护杂志

Objective To develop the method of analyzing α-radionuclides using large area grid ionization chamber.Methods Ultrasonic dispersion and vacuum drying system was used to prepare sample source,large standard thin source and plutonium plane source were used to optimize the working condition of spectrometer,and calibrate the instrument for analyzing α emitters.The certified reference materials (GBW04127) were used to verify the accuracy of the method.Results The non-linearity of calibration curve for standard thin sources of neptunium,plutonium and americium was less than 0.2％,and the resolution were 112,84 and 106 keV,respectively.The counting efficiency was 31.2％ for the large standard thin source.The values of specific activity measured in this way were in good agreement with those of the certified reference materials.232Th,238U,230Th,234U/226Ra,210Po,222Rn and 218Po were analyzed in a uranium mineral sample,and their specific radioactivity values were 5.3,3.8,35.6,21.4,27.0,19.6 and 11.1 Bq/g,respectively.Conclusions The method can be used to analyze α spectrum quickly in low-level radioactive environmental samples.

Gotejadores aplicando proporções de tempo de irrigação com efluente da suinocultura e água de abastecimento / Drippers applying proportions of irrigation time with swine wastewater and water supply

Este trabalho objetivou analisar os efeitos de proporções de tempo de irrigação com água residuária da suinocultura (ARS) e água de abastecimento (AA) na alteração de indicadores de desempenho hidráulico de sistemas de irrigação com três modelos de gotejadores (G1 - não autocompensante de 2,0 L h-1, G2 - não autocompensante de 1,7 L h-1 e G3 - autocompensante de 3,6 L h-1). O experimento foi realizado junto ao Departamento de Engenharia Agrícola (DEA/UFV) em Viçosa-MG, tendo os seguintes tratamentos: i) 1E3A(1 h de ARS e 3 h de AA); ii) 2E2A (2 h de ARS 2 h de AA); iii) 3E1A (3 h de ARS e 1 h de AA); e iv 4E (4 h de ARS). As características físico-químicas e biológicas da ARS e AA foram determinadas a cada 20 h e 80 h, respectivamente. Os valores do coeficiente de variação de vazão (CVq), coeficiente de uniformidade estatística (Us) e coeficiente de vazão relativa média (DRA) foram obtidos a cada 20 h, durante 160 h de operação do sistema. Após 160 h, gotejadores e linhas laterais foram dissecados para investigação do material ocasionar de obstrução. A obstrução por biofilme foi mais acentuada nas combinações G1 x 2E2A e G1 x 3E1A, enquanto as combinações G2 x 1E3A e G3 x 4E apresentaram os maiores valores de desempenho hidráulico, minimizando a obstrução nas unidades de irrigação com biofilme.

This study aimed to analyze the effects of irrigation time with swine wastewater (ARS) and water supply (AA) on alteration of hydraulic performance indicators in irrigation systems with three models drippers (G1 - non pressure compensating for 2.0 L h-1, G2 ­ non pressure compensating for 1.7 h L-1 and G3 - pressure compensating for 3.6 h L-1). The experiment was conducted at the Agricultural Engineering Department (DEA/UFV) in Viçosa-MG, with the following treatments: i) 1E3A (ARS 1 h and 3 h AA); ii) 2E2A (ARS 2 h and 2 h AA); iii) 3E1A (ARS 3 h and 1 h of AA); and iv 4E (ARS 4 h). The physico-chemical and biological characteristics of ARS and AA were determined every 20 h and 80 h, respectively. The coefficient of variation of discharge (CVq), coefficient of statistical uniformity (Us) and coefficient of relative mean flow (Dra) were obtained every 20 h, during 160 h of operation. After 160 h, drippers and lateral lines were dissected to investigate the material cause of obstruction. The obstruction by biofilm was more pronounced in combinations G1 x 2E2A and G1 x 3E1A, while the combinations G2 x 1E3A and G3 x 4E showed higher hydraulic performance, minimizing the obstruction on irrigation units with biofilm.

Microaspersores entupidos devido a problemas de ferro na água / Microsprinkler clogged due to iron problems in the water

Um dos aspectos relevantes a ser considerado no manejo da irrigação é a uniformidade de distribuição de água pelo sistema. Este trabalho foi desenvolvido com o objetivo de avaliar a eficiência da cloração com a utilização de hipoclorito de sódio na desobstrução de microaspersores devido à utilização de águas com elevado teor de ferro. Um sistema com dez meses de uso apresentava setores com vazões de 5 por cento a 57 por cento menores que a vazão de projeto. Foi feito o tratamento químico da água de irrigação, utilizando-se hipoclorito de sódio com 12 por cento de cloro livre na dosagem de 100 mg L-1 e ácido sulfúrico, na concentração de 98 por cento, para manter o pH da água de irrigação em torno de 4,5. O resultado indicou que houve aumento significativo nas vazões médias dos microaspersores em todos os setores avaliados e diminuição na variação da vazão dos mesmos com relação à estimada no projeto.

An important aspect to be considered in irrigation managment is the uniformity distribution of water through the irrigation system. This research had the objective to evaluate the efficiency of chlorination in the use of sodium hypochlorite in clearing of microsprinkler due to the presence of high iron concentration in water. The equipment with less than a year of use presenting sectors with 5 percent and 57 percent lower flow than the original project flow. The chemical treatment of water irrigation utilized sodium hypochlorite with 12 percent free chlorine on 100mg L-1 concentration, and sulphuric acid 98 percent to maintain the pH of water irrigation about 4.5. The result demonstrated a significant increase in the average flow of the microsprinkler's variation in all evaluted setors, and decrease in their flow variation related to the estimated in the project.

The role of electron-emitting radiopharmaceuticals in the palliative treatment of metastatic bone pain and for radiosynovectomy: applications of conversion electron emitter Tin-117m

A variety of radionuclides continue to be investigated and/or clinically used for different therapeutic applications in nuclear medicine. The choice of a particular radionuclide with regard to appropriate emissions, linear energy transfer (LET), and physical half-life, etc., is dictated to a large extent by the character of the disease (e.g., solid tumor or metastatic disease), and by the carrier to selectively transport the radionuclide to the desired site. An impressive body of information has appeared in the recent literature that addresses many of these considerations. This article summarizes and discusses the role of high-LET electron emitters and their advantage in the treatment of cancer or for other disorders in specific situations. Areas such as bone pain palliation, bone malignancy therapy, and radiation synovectomy are covered in greater detail. Projections are made as to the future directions and progress in these areas. A discussion of the various issues related to the selection criteria that are useful for choosing the appropriate radionuclide for a particular application is included. Use of high-LET electron emitters is discussed in greater detail, with particular emphasis on the use of conversion electron emitter tin-117m for various therapeutic applications.

Uma variedade de radionuclídeos continua a ser investigada e/ou clinicamente utilizada para diferentes aplicações terapêuticas em medicina nuclear. A escolha de um radionuclídeo, considerando-se sua emissão apropriada, transferência linear de energia (LET) e meia-vida física é determinada na maior parte pelo caráter da doença (p.ex., tumor sólido ou doença metastática), e pelo carreador que transporta o radionuclídeo seletivamente para o sítio desejado. Um notável conjunto de informações voltadas para essas considerações tem aparecido na literatura recente. Esse trabalho resume e discute o papel de emissores de elétrons de alta-LET e sua vantagem no tratamento do câncer ou para outras doenças em situações específicas. Abordagens relacionadas com o alívio da dor óssea, a terapia da doença óssea e a sinovectomia por radiação são apresentadas detalhadamente. Projeções para o futuro e os progressos nessas áreas são indicadas. Uma profunda discussão relacionada aos critérios de seleção que são úteis para escolher o radionuclídeo apropriado para que uma aplicação particular seja incluída. O uso de emissores de elétrons de alta-LET é discutido em grande detalhe, com particular ênfase no uso do estanho-117m, um emissor de elétron de conversão, para várias aplicações terapêuticas.