ABSTRACT
Ionizing radiation has been used for decades and expanded to several applications in multivariate sectors, becoming an important tool to promote controlled chemical reactions in polymeric structures, according to their chemical properties for developing new materials. In addition, the use of radiation can also be applied in order to reduce or eliminate compounds from solutions that may be harmful or of low interest. In this review, we overviewed the chemistry behind material irradiation and the attractive use of ionizing radiation in scientific and industrial development. In this regard, the review was divided into three main sections titled (1) chemical kinetics intermediated by radiation, (2) chemical bonds intermediated by radiation, and (3) radiation chemistry on polymers. We concluded that graft polymerization, crosslinking and chain scission reactions induced by ionizing radiation are very efficient and green strategies for developing new materials with improved properties. Furthermore, water radiolysis plays a key role in the degradation of several contaminants, including pharmaceuticals and microplastics, in aqueous solutions. However, more studies must be conducted to complement the existing theory about the proposed mechanisms responsible for modifying the chemical, mechanical, thermal, optical, and so forth properties of irradiated materials.
Subject(s)
Plastics , Polymers , Polymers/chemistry , Kinetics , Radiation, Ionizing , WaterABSTRACT
BACKGROUND: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to update the readership on trends in the field of radiopharmaceutical development. RESULTS: This commentary of highlights has resulted in 23 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals and also a contribution in relation to MRI-agents is included. CONCLUSION: Trends in (radio)chemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry.
ABSTRACT
Metal-organic frameworks (MOFs) are known for their versatility in terms of their crystalline structure, porosity, resistance to temperature, radiation damage, and luminescence among others. Gadolinium (Gd) is one of the elements with the highest reported cross-section for low energy neutron capture, producing internal conversion electrons and γ rays as a result of the neutron absorption. The development of Gd-BTC films (BTC=1,3,5-benzenetricarboxylate) is shown that were deposited on Si and Al substrates by airbrushing, and characterized by profilometry, Raman, EDX and X-ray diffraction. Radiation damage, thermal decomposition and neutron absorption of these films were studied as well. Gd-BTC films were attached to CMOS devices (Complementary Metal-Oxide-Semiconductor), which are sensible to the internal conversion electrons, in order to build a neutron detector. The devices Gd-BTC/CMOS could selectively detect neutrons in the presence of γ rays with a thermal neutron detection efficiency of 3.3±0.1 %, a signal to noise ratio of 6 : 1, and were suitable to obtain images.
ABSTRACT
RESUMEN El presente trabajo muestra el desarrollo que ha tenido la formación de profesionales nucleares en Cuba durante más de treinta y ocho años. Se exponen las características principales de los programas de estudio de las carreras nucleares acreditadas por el sistema nacional de acreditación de la educación superior cubana. Algunos indicadores de la calidad de la formación en ingeniería nuclear, física nuclear y radioquímica, la presencia de la mujer, así como, la contribución de estas carreras al desarrollo de la provincia La Habana a partir de un análisis de la ubicación de sus egresados son presentados.
ABSTRACT This work shows the development that has taken the education of nuclear professionals in Cuba for more than thirty-eight years. The main features of the curriculum for undergraduate specialty for nuclear matters, accredited by the national accreditation system of higher education in Cuba are introduced. Some quality indicators, the women presence and the contribution of the nuclear careers to the development of Havana province beginning from the analysis of graduated distribution in the labor market are discussed.
ABSTRACT
BACKGROUND: Glycine N-methyltransferase is an enzyme overexpressed in some neoplastic tissues. It catalyses the methylation of glycine using S-adenosyl methionine (SAM or AdoMet) as substrate. SAM is involved in a great variety of biochemical processes, including transmethylation reactions. Thus, [11C]SAM could be used to evaluate transmethylation activity in tumours. The only method reported for [11C]SAM synthesis is an enzymatic process with several limitations. We propose a new chemical method to obtain [11C]SAM, through a one-pot synthesis. METHOD: The optimization of [11C]SAM synthesis was carried out in the automated TRACERlab® FX C Pro module. Different labelling conditions were performed varying methylating agent, precursor amount, temperature and reaction time. The compound was purified using a semipreparative HPLC. Radiochemical stability, lipophilicity and plasma protein binding were evaluated. RESULTS: The optimum labelling conditions were [11C]CH3OTf as the methylating agent, 5 mg of precursor dissolved in formic acid at 60 °C for 1 minute. [11C]SAM was obtained as a diastereomeric mixture. Three batches were produced and quality control was performed according to specifications. [11C]SAM was stable in final formulation and in plasma. Log POCT obtained for [11C]SAM was (-2,01 ± 0,07) (n=4), and its value for plasma protein binding was low. CONCLUSION: A new chemical method to produce [11C]SAM was optimized. The radiotracer was obtained as a diastereomeric mixture with a 53:47 [(R,S)-isomer: (S,S)-isomer] ratio. The compound was within the quality control specifications. In vitro stability was verified. This compound is suitable to perform preclinical and clinical evaluations.
Subject(s)
Carbon Radioisotopes/chemistry , Radiochemistry/methods , Radiopharmaceuticals/chemical synthesis , S-Adenosylmethionine/chemical synthesis , Automation , Isotope Labeling , MethylationABSTRACT
Se analizaron muestras de un suelo ferralítico rojo de la Estación Experimental Juan Tomás Roig de la Universidad de Ciego de Ávila, sometido a dos rotaciones de cultivo y cuatro sistemas de fertilización fosfórica. El objetivo fue evaluar, mediante la dilución isotópica del 32P, los parámetros estáticos del fósforo (P) en un suelo que recibió fertilizante fosfórico por dos métodos de aplicación (en bandas y a voleo) durante varios años. Se utilizó un método radioquímico de laboratorio usando una disolución marcada con 32P libre de portador, basado en el intercambio isotópico entre los fosfatos de los sólidos y la solución del suelo. Las muestras de suelo se analizaron en los laboratorios del Departamento del Comisariado de Energía Atómica, Francia. Se determinaron los factores cantidad (E1) como el P isotópicamente intercambiable en un minuto, intensidad (Cp) como la concentración de P en la solución del suelo y capacidad como la relación E1/Cp. La evaluación isotópica mediante 32P indicó que el suelo necesita de aplicaciones de P altas y en bandas para alcanzar valores de E1 y Cp adecuados para la nutrición de los cultivos agrícolas. Con la fertilización en bandas se logró un efecto acumulativo del P en el suelo después de tres ciclos de rotación de cultivos, que permitió incrementar su disponibilidad para las plantas. El factor capacidad resultó muy alto en todas las muestras de suelo, lo cual indica que el suelo mantiene una reserva de P que es difícilmente intercambiable con el P de la solución del suelo
Soil samples from a red ferralitic soil from the "Juan Tomás Roig" Experimental Station, belonging to Ciego de Avila University were analyzed under two crop rotations and four phosphoric fertilization systems. The objective was to evaluate, through the 32P isotopic dilution, phosphor (P) static parameters in a soil that has received P fertilizer through two placement methods (banding and broadcasting) for several years. A radiochemical laboratory method using a 32P free-carrier solution as a tracer based on isotopic exchange between solid phase and soil solution phosphate ions was used. Soil samples were analyzed at the CEA Department laboratories, in Francia. Quantity (E1), as isotopic exchangeable P at one minute, intensity (Cp), as P concentration in soil solution, and capacity, as (E1/Cp), factors were determined. 32P isotopic evaluation indicated that the soil needs high banding P application to reach adequate E1 and Cp values for crop nutrition. A cumulative P effect in the soil through banding fertilization after three crop rotation cycles was obtained, which allows to increase plant P availability. The capacity factor was very high in all soil samples, indicating that soil maintains a P reserve that is difficult to exchange with the phosphor present in the soil solution