UV/ozone degradation of gaseous hexamethyldisilazane (HMDS).

As a carcinogen, hexamethyldisilazane (HMDS) is extensively adopted in life science microscopy, materials science and nanotechnology. However, no appropriate technology has been devised for treating HMDS in gas streams. This investigation evaluated the feasibility and effectiveness of the UV (185+254nm) and UV (254nm)/O(3) processes for degradation of gaseous HMDS. Tests were performed in two batch reactors with initial HMDS concentrations of 32-41mgm(-3) under various initial ozone dosages (O(3) (mg)/HMDS (mg)=1-5), atmospheres (N(2), O(2), and air), temperatures (28, 46, 65 and 80 degrees C), relative humilities (20%, 50%, 65%, 99%) and volumetric UV power inputs (0.87, 1.74, 4.07 and 8.16Wl(-1)) to assess their effects on the HMDS degradation rate. Results indicate that for all conditions, the decomposition rates for the UV (185+254nm) irradiation exceeded those for the UV (254nm)/O(3) process. UV (185+254nm) decompositions of HMDS displayed an apparent first-order kinetics. A process with irradiation of UV (185+254nm) to HMDS in air saturated with water at temperatures of 46-80 degrees C favors the HMDS degradation. With the condition as above and a P/V of around 8Wl(-1), k was approximately 0.20s(-1) and a reaction time of just 12s was required to degrade over 90% of the initial HMDS. The main mechanisms for the HMDS in wet air streams irradiated with UV (185+254nm) were found to be caused by OH free-radical oxidation produced from photolysis of water or O((1)D) produced from photolysis of oxygen. The economic evaluation factors of UV (185+254nm) and UV (254nm)/O(3) processes at different UV power inputs were also estimated.

Situación epidemiológica del cáncer de próstata en España / Epidemiological situation of prostate cancer in Spain

El cáncer de próstata es el tercer tumor más frecuente en varones españoles y la tercera causa de muerte por cáncer. Su incidencia aumenta con la edad. Un 90% de casos se diagnostican en mayores de 65 años. La etiología es poco conocida relacionándose con exposiciones ambientales, estilos de vida, antecedentes familiares y factores genéticos. En el año 2002 la tasa de mortalidad (situada entre las más bajas de Europa) fue 21,5 casos por 100.000 habitantes, superándose las 5.000 defunciones. La tendencia de mortalidad ha ido en aumento hasta 1998, año en el que empieza a disminuir en relación con mejoras en el diagnóstico y tratamiento. Al estudiar la incidencia del cáncer de próstata nos encontramos con la dificultad debida a la escasez de registros poblacionales de cáncer. Se han realizado estimaciones a partir de los datos disponibles, detectándose una tasa de incidencia de 45,33 por 100.000 habitantes, también entre las más bajas de Europa. La incidencia anual de cáncer de próstata ha aumentado en todos los registros españoles debido a mejoras en los mismos, pero también al desarrollo de las pruebas diagnósticas, que han condicionado una mejor supervivencia desde principios de los 90 (86% al año del diagnóstico y 65,5% a los cinco años) comparable a la de otros países de nuestro entorno. Es necesario ampliar el sistema de registro de cáncer para conocer la incidencia y la prevalencia, evaluar la supervivencia y la eficacia de los programas de detección precoz y mejorar en el conocimiento de los factores de riesgo

Prostate cancer is the third most frequent neoplasms in Spanish men and the third cause of cancer death. Incidence grows up with the increase of age. 90% of cases are diagnostic in people over 65 years old. Etiology is quite unknown and has been associated with environmental exposure, life style, family sign and genetic factors. In 2002 mortality rate was 21.5/ 100.000 (situated among the lowest in Europe), with more than 5.000 deaths. Trend of mortality has grown up until 1998, from this year it has decreased due to improve on diagnostic and treatment. In order to study prostate cancer incidence we find a difficulty due to shortage of population cancer register. Estimations have found incidence rates of 45.33/100.000 which are among the lowest in Europe. Annual incidence of prostatic cancer has grown up in all Spanish registers, not only improve in register systems explains it, but also the development of diagnosis tests with a higher survival from the beginning of 90s (86% the first year after diagnosis and 65,5% five years after diagnosis), similar to other European countries. Blow up the cancer register system is necessary to know the incidence and prevalence, to assess survival and effectiveness of screening programs and to improve the knowledge of risk factors

Stability of fumonisins at different storage periods and temperatures in gamma-irradiated maize.

The effect of gamma-irradiation on fumonisin B1 (FB1) and fumonisin B2 (FB2) occurring in maize materials has been investigated together with the stability of fumonisins in gamma-irradiated maize stored at different temperatures (-18 to +40 degrees C) for different periods (2, 4, 13 and 26 weeks). Fifteen KGy gamma-irradiation was required to sterilize efficiently maize flour. This process caused a decrease in fumonisin content of about 20%. The stability studies showed that fumonisins are stable in gamma-irradiated maize for at least 6 months at 25 degrees C or at least 4 weeks at 40 degrees C. These data indicate that gamma-irradiation is an appropriate technique for obtaining sterilized maize materials to be used for intercomparison studies on analytical procedures for the measurement of the fumonisin content.