The irradiation of monolayer graphene, combined with chemical functionalization, could be an effective method for modifying its electronic structure and for achieving specific physical properties ...adjusted to different applications. A difficulty arising during planning and studying the irradiation in this system is that many of the models of interaction of the radiation with the substance cannot be applied to the two-dimensional structure of graphene. In particular, the mathematical expressions available to calculate the number of atoms displaced during the bombardment with particles can be applied only to 3D isotropic solids. In the present work, an alternative analytic expression is presented for the irradiation of graphene with heavy ions or with protons and other light charged particles. The expression was obtained on the basis of the classic theory of dispersion, using a Coulomb potential for the light charged particles and one of Inverse Square for heavy ions. For medium values of the energy of the incident particle a decreasing dependence of the number of displaced atoms with energy is obtained. This behavior, related with the two-dimensional structure of the target, had been observed in other authors’ works using computational simulation.
Pretreated silica sand labeling using varying concentrations of tin(II) fluoride and chloride as reducing agents and different times labeling was performed in order to develop a methodology for ...labeling silica sand with .sup.99mTc for using as solid radiotracer. Influence of different sand pretreatment parameters on the sorption yield (R.sub.ret%) was statistically evaluated. The effectiveness of the methods used to reduce pertechnetate (.sup.99mTcO.sub.4.sup.-) by ascending paper chromatography was confirmed. Results show relatively high values of .sup.99mTc sorption yields on silica sand. It was possible to establish a methodology for obtaining solid .sup.99mTc labeled radiotracers in support of silica sand.
En la actualidad la contaminación de las aguas terrestres es un grave problema ambiental. La industria farmacéutica es una de las que produce un mayor impacto por la gran variedad de químicos que ...aporta al agua; sus efluentes generalmente tienen asociadas elevadas cargas orgánicas no biodegradables. La preservación de la calidad de las aguas terrestres es un tema regulado por la legislación nacional, donde se exige la caracterización de las aguas residuales antes de su vertimiento con vistas a evaluar el impacto ambiental que producen y diseñar el sistema adecuado para su tratamiento. El Instituto Finlay de Vacunas, pertenece al grupo de BioCubaFarma, es una empresa de ciclo completo, cuenta con nueve instalaciones, cinco de ellas son generadoras de grandes volúmenes de aguas residuales industriales. El presente trabajo tiene el objetivo de presentar los resultados obtenidos en la evaluación de los parámetros físico-químico de los residuales líquidos del proceso productivo de conjugados monovalentes, para esto se muestrearon los residuales líquidos generados al final de cada etapa del proceso. Se determinaron los indicadores de contaminación: pH, temperatura, conductividad eléctrica, demanda química y bioquímica de oxígeno, fósforo total, nitrógeno total y sólidos sedimentables; los ensayos fueron realizados en el laboratorio de la Empresa Nacional de Servicios Técnicos de la Habana, acreditado para la realización de las caracterizaciones de aguas residuales. Los resultados fueron comparados con los límites máximos permisibles establecidos en la Norma Cubana NC-27:2012 de vertimiento de aguas residuales al alcantarillado, además se calculó el índice de biodegradabilidad. Se demostró que el pH, la conductividad eléctrica, demanda química de oxígeno y demanda bioquímica de oxígeno no cumplen con el vertido para la descarga al alcantarillado pudiendo impactar de manera negativa en los recursos hídricos.
Pretreated silica sand labeling using varying concentrations of tin(II) fluoride and chloride as reducing agents and different times labeling was performed in order to develop a methodology for ...labeling silica sand with
99m
Tc for using as solid radiotracer. Influence of different sand pretreatment parameters on the sorption yield (R
ret%
) was statistically evaluated. The effectiveness of the methods used to reduce pertechnetate (
99m
TcO
4
−
) by ascending paper chromatography was confirmed. Results show relatively high values of
99m
Tc sorption yields on silica sand. It was possible to establish a methodology for obtaining solid
99m
Tc labeled radiotracers in support of silica sand.
To obtain 99mTc solid radiotracers, new porous supports are currently needed. Previous studies carried out by other authors showed the possibility of 99mTc labeling of sediments from rivers with a ...high content of aluminosilicates. In the present work a methodology for labeling of silica sand with 99mTcO4- as a prospective solid radiotracer was developed. Labeling of the previously treated and untreated silica sand was carried out using variable concentrations of chloride and stannous fluoride as reducing agents and different labeling times. The influence of the pre-treatment stage of the sand on the obtained Tc retention yields was evaluated. The changes in the composition of the silica sand after its previous treatment could be verified from the Scanning Electron Microscopy (SEM-EDS). The results suggested the use of previously treated silica sand and stannous fluoride as a reducing agent, modifications were proposed to the initial methodology of previous treatment of the sand. It was possible to confirm from the SEM-EDS technique that the increase in the percentage of retention of Tc in the sand after its treatment is mainly due to the observed changes in its chemical composition and structure. It was possible to obtain a 99mTc solid radiotracer on support of silica sand with an estimated preparation time of 4 hours and a retention yield of 74%.
This paper deals with the application of different experimental and theoretical tools to study nanomaterials as well as research aimed at combining the use of nano- and nuclear technologies carried ...out at the Higher Institute of Technologies and Applied Sciences. The wide participation of students in the research is highlighted, thus contributing to the assimilation of concepts and methods of nanosciences by the graduates of nuclear careers.
PDF
