O Fluoreto de sódio 18F (Na18F) é um radiofármaco empregado para diagnóstico através da Tomografia por Emissão de Pósitrons (PET). Cintilografias ósseas são normalmente obtidas utilizando-se 99mTc-MDP. Entretanto, o interesse pelo Na18F é crescente, principalmente devido à obtanção de imagens de elevada resolução. Com o objetivo de tornar disponível uma ferramenta mais específica para estudos de tumores e doenças não-oncológicas do tecido ósseo, o grupo da UPPR/CDTN implementou a produção e o controle de qualidade da solução injetável de Na18F com as características físico-química, microbiológica e biológica preconizadas pela farmacopéia. Sua pureza radioquímica foi de 96,7 ± 1,3 %, com Rf= 0,026 ± 0,006. O produto apresentou pH igual a 5,3 ± 0,6, tempo de meia-vida de 109,0 ± 0,8 minutos, limite de endotoxinas < 5,0 EU.mL-1 e ausência de microrganismos. O perfil de biodistribuição em camundongos foi semelhante ao disponível na literatura, com depuração igual a 0,19 mL.min-1 e volume de distribuição igual a 18,76 mL. A concentração máxima (5,0 ± 0,5 % DI.g-1) foi observada no osso 20 minutos após a injeção. O Na18F produzido na UPPR do CDTN apresentou os parâmetros de qualidade definidos na farmacopéia americana e pode ser usado com segurança para uso clínico em cintilografia óssea.

18F-Sodium fluoride (Na18F) is a radiopharmaceutical used for diagnosis in nuclear medicine by positron emission tomography (PET) imaging. Bone scintigraphy is normally performed using 99mTc-MDP. However, 18F PET scans promise high quality imaging with increased resolution and improved sensitivity and specificity. In order to make available a tool for more specific studies of tumors and non-oncological diseases of bone tissue, the UPPR/CDTN team undertook the production and quality control of Na18F injectable solution with the physical-chemical, microbiological and biological characteristics recommended in the U.S. Pharmacopeia. Na18F radiochemical purity was 96.7 ± 1.3 %, with Rf= 0.026 ± 0.006. The product presented a pH of 5.3 ± 0.6, half life of 109.0 ± 0.8 minutes, endotoxin limit < 5.0 EU.mL-1 and no microbial contaminants. The biodistribution of Na18F was similar to that described in the literature, with a clearance of 0.19 mL.min-1 and distribution volume of 18.76 mL. The highest bone concentration (5.0 ± 0.5 %ID.g-1) was observed 20 minutes after injection. Na18F produced at the UPPR presented all the quality assurance requirements of the U.S. Pharmacopeia and can be safely used for clinical bone imaging.

The TRIGA IPR-R1 nuclear reactor at the Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN, Belo Horizonte, Brazil, has three irradiation facilities: a rotary specimen rack outside the reactor core with 40 irradiation channels which provide large scale isotope irradiation; the central tube placed at the center of the reactor core which permits sample irradiation with maximum neutron flux, as well as neutron beam extraction; a pneumatic transfer tube which makes possible the analysis of short half-life radioisotopes. The aim of this work is to evaluate the thermal and epithermal neutron fluence rates in the three irradiation facilities of the IPR-R1. Al-0.1%Au reference materials were irradiated bare and Cd-covered, at 100 kW thermal power, and gamma spectrometry was applied with an HPGe detector. For the rotary specimen rack, the values obtained for thermal and epithermal neutron fluence rates are (8.2 ± 0.2) × 10(11)n.cm-2.s-1 and (3.5 ± 0.1) × 10(10)n.cm-2.s-1, respectively. For the pneumatic transfer tube and the central tube, epithermal neutron fluence rate values are respectively (3.3 ± 0.2) ×10(9)n.cm-2.s-1 and (2.6 ± 0.1) x 10(11)n.cm-2.s-1. For these facilities, thermal neutron fluence rate values are (2.5 ± 0.2) × 10(11)n.cm-2.s-1 and (2.8 ± 0.1) × 10(12)n.cm-2.s-1, respectively. Knowledge of these parameters will be fundamental in the planning of sample irradiation for analysis or radioisotope production in a more accurate way.

The IPR-R1 TRIGA nuclear reactor at Nuclear Technology Development Center, CDTN/CNEN, Belo Horizonte, Brazil, has a rotary specimen rack, RSR, outside the reactor core, and it is composed for forty irradiation channels in a cylindrical geometry. The aim of this work is to evaluate the neutron fluence rate distribution at the RSR and its variation under different irradiation conditions by means of specific induced activity measurements. Al-0.1 % Au reference materials were irradiated simultaneously at 100 kW in these irradiation channels and gamma spectrometry was applied with HPGe detector to determine the specific induced activity. This procedure was repeated six times. The results show an asymmetrical neutron fluence rate distribution at the RSR. The variation between the minimum and the maximum specific induced activity values in the RSR channels is about 14%.

As propriedades do cimento Portland estão diretamente relacionadas às concentrações de suas fases constituintes, principalmente a alita, a belita, a fase ferrítica e o aluminato. A alita, de composição 3CaO.SiO2 e abreviada por C3S, deve ser o constituinte majoritário do clínquer após o processamento, pois é sua reação de hidratação que confere a resistência mecânica ao cimento curado. A belita, de composição 2CaO.SiO2 e abreviada por C2S, está presente como o primeiro complexo de cal e sílica formado no aquecimento e, sendo mais estável a baixas temperaturas que o C3S, volta a se formar no resfriamento. O aluminato está presente principalmente na forma de 3CaO.Al2O3, abreviado por C3A, enquanto a ferrita aparece como constituinte principalmente na forma 4CaO.Al2O3.Fe2O 3, abreviada por C4AF. Os teores de ferrita e alumina, no entanto, alteram a estabilidade da alita, com conseqüentes alterações na reatividade do cimento. O presente trabalho estuda os efeitos de adições de Fe2O3 e Al2O3 sobre a estabilidade da alita e apresenta diagramas CCT para a decomposição da alita na presença desses compostos.

The properties of Portland cement are directly related to the concentrations of its major phases, i.e., alite, belite, the ferritic phase and the aluminate phase. Alite, with the composition 3CaO.SiO2, known as C3S, should be the major component of the clinker after processing, once its hydration produces the high yield strengths of cured cement. Belite, with the composition 2CaO.SiO2, known as C2S, is the first lime and silica complex, formed during the heating process. It presents higher stability at low temperatures than C3S, so that it tends to be formed again during the cooling cycle, from the decomposition of alite. The aluminate phase appears mainly with the composition 3CaO.Al2O3, known as C3A, and the ferritic phase appears with the composition 4CaO.Al2O3.Fe2O 3, known as C4AF. However, the ferrite and alumina contents affect the alite stability, and consequently, its reactivity. This paper studies the effects of Fe2O3 and Al2O3 additions over the alite stability and presents CCT diagrams for the alite decomposition in the presence of these compounds.

As propriedades mecânicas do cimento Portland estão intrinsecamente relacionadas à composição química do clínquer, em especial à concentração de silicato tricálcico 3CaO.SiO2, ou C3S. No processo produtivo industrial, o clínquer deve ser resfriado rapidamente, para evitar a decomposição do silicato tricálcico em silicato dicálcico e cal. Esse trabalho estuda a cinética de decomposição térmica do C3S puro. A decomposição do C3S puro em resfriamento contínuo apresentou uma velocidade mais elevada do que a tradicionalmente aceita na literatura.

The mechanical properties of Portland cement are closely related to the chemical composition of the clinker, and particularly to the concentration of tricalcium silicate, 3CaO.SiO2, or C3S. In the industrial production process, the clinker must be rapidly quenched, to avoid its decomposition into dicalcium silicate and lime. This work studies the kinetics of thermal decomposition of pure C3S. The continuous cooling transformation of pure C3S showed a decomposition rate higher than the values traditionally accepted in the literature.