Effect of the Target Size in the Calculation of the Energy Deposited Using PENELOPE Code

The specific and linear energy was calculated in target sizes of 10 μm, 5 μm, 1 μm, 60 nm, 40nm and 20 nm by taking into account the contribution of the primary photon beams and the electrons generated by them in LiF: Mg, Ti (TLD-100). The simulations were carried out by the code PENELOPE 2011. Using different histories of primary particles, for each energy beams the mean deposited energy is the same, but to achieve a statistical deviation lower than 1% the value of 108was fixed. We find that setting the values C1 = 0.1 C2 = 0.1 and Wcc = Wcr = 50 eV the time of simulation decreases around the 25%. The uncertainties (1 SD) in the specific energy increases with energy for all target sizes and decreases with target size, with values from 1.7 to 94% for 20 nm and between 0.1 and 0.8% for 10 μm. As expected, the specific and linear energies decrease with target size but not in a geometrical behavior

Simultaneous Grafting of Poly(Acrylic Acid) and Poly(Ethylene Glycol) onto Chitosan using Gamma Radiation: Polymer Networks for Removal of Textile Dyes

Chitosan is a bio-based polyelectrolyte with high potential for wastewater treatment. Chitosan can remove anionic dyes by adsorption but it has low performance in the removal of cationic dyes. In this work, we report the synthesis of chitosan-based graft-copolymers using gamma radiation. Acrylic acid and poly(ethylene glycol) were grafted successfully onto chitosan applying a radiation dose of 12 kGy at a dose rate of 8 kGyh-1. The grafted-copolymers have improved adsorptive properties for the removal of basic dyes reaching a maximum adsorption capacity higher than 300 mgg-1. The Lanmguir’s isotherm model described satisfactorily the interaction between the grafted copolymers and basic dyes. Freundlich’s isotherm model described the adsorption of anionic dye acid orange 52. The grafted copolymers removed successfully textile dyes from wastewater of the dyeing process. The best results were obtained in the removal of direct and basic dyes. Further, poly(ethylene glycol) grafted on the copolymer conferred better swelling behavior making easy the separation of the adsorbent after dye removal. The results showed that the adsorbent materials synthesized by radiochemical graftcopolymerization are more efficient than the beads, composite materials, and blends of chitosan

Graft-Copolymerization of Acrylate Monomers onto Chitosan Induced by Gamma Radiation: Amphiphilic Polymers and Their Behavior at The Air-Water Interface

Graft polymerization induced by ionizing radiation is a powerful tool in materials science to modifying the physical properties of polymers. Chitosan is a biocompatible, biodegradable, antibacterial, and highly hydrophilic polysaccharide. In this work, we report the obtaining of amphiphilic polymers through graft polymerization of acrylic monomers (methyl acrylate, t-butyl acrylate, and hexyl acrylate) onto chitosan. The polymerization reaction was carried out by simultaneous irradiation of monomers and chitosan using a gamma radiation source of 60Co. The formation of Langmuir films of amphiphilic polymers was studied at the air-water interface through surface pressure versus main molecular area isotherms (Π-A) and hysteresis cycles of compression and decompression. Finally, it was analyzed the transferring of Langmuir films towards solid substrates to obtaining Langmuir-Blodgett films with potential application as an antibacterial coating. The microstructure of the Langmuir-Blodgett films was characterized by AFM microscopy observing a regular topography with roughness ranging between 0.53 and 0.6 μm

DISEÑO DE UN PROTOTIPO FERMENTADOR DE LECHE SEMIAUTOMÁTICO PARA LA ELABORACIÓN DE SUERO COSTEÑO

El Suero Costeño es un producto lácteo fermentado, artesanalmente en la costa atlántica colombiana. Para cumplir con las normas sanitarias el fermentador está constituido por un tanque diseñado y fabricado en acero inoxidable 304, con un volumen neto de 30 L. Se garantizó una temperatura de 35°C en la fermentación de la leche, con un sistema de enfriamiento mediante una chaqueta. La temperatura se medió con un sensor de temperatura, tipo PT-100, con el sistema microcontrolado se programó su set-point, para separar el espiche del suero se utilizó una válvula; la finalización de la fermentación se determinó con la medición del pH con un pH-metro. La cantidad de materia prima y producto se mide con un sensor de nivel y se muestra de manera continua en la pantalla LCD del panel de control

Perinatal characteristics and retinoblastoma

PURPOSE: The etiology of retinoblastoma remains poorly understood. In the present study, we examined associations between perinatal factors and retinoblastoma risk in California children. METHODS: We identified 609 retinoblastoma cases (420 unilateral, 187 bilateral, and 2 with laterality unknown) from California Cancer Registry records of diagnoses 1988–2007 among children <6 years of age. We randomly selected 209,051 controls from California birthrolls. The source of most study data was birth certificates. Multivariable logistic regression was used to examine associations between retinoblastoma and perinatal characteristics. RESULTS: Bilateral retinoblastoma was associated with greater paternal age [for fathers over 35, crude Odds Ratio (OR)=1.73, 95% Confidence Interval (CI) 1.20, 2.47] and with twin births (OR=1.93, 95% CI 0.99, 3.79). Among unilateral cases, we observed an increased risk among children of US-born Hispanic mothers (OR=1.34, 95% CI 1.01, 1.77) while a decreased risk was observed for infants born to mothers with less than 9 years of education (OR=0.70, 95% CI 0.49–1.00), a group that consisted primarily of mothers born in Mexico. We observed that maternal infection in pregnancy with any STD (OR=3.59, 95% CI 1.58, 8.15) was associated with bilateral retinoblastoma. CONCLUSIONS: This study supports the findings of previous investigations reporting associations between parental age, HPV infection and retinoblastoma

La reforma de los servicios de salud en México y la dinamización y politización de los intereses: una aproximación Health care reform in Mexico and the dynamics and politicization of interests: an approach

La propuesta de este artículo es discutir el proceso de reforma en los servicios de salud puesta en práctica en México a partir de 1982 y que todavía está en curso. Ese proceso de reforma será estudiado como un fenómeno socio-político cuya dinámica y naturaleza son resultados de conflictos pasados y presentes que se articulan alrededor de proyectos técnico-asistenciales, expresión de determinadas visiones del futuro. El trabajo empezó por considerar la propia estructura de poder históricamente constituida a través de la acción del Estado en el sector salud la cual promovió a determinados grupos sociales, estimuló su desarrollo y los incorporó en sus estructuras de poder, al mismo tiempo que marginó y reprimió a otros. En un segundo momento, el trabajo reconstituyó empíricamente la 'historia social' de la reforma, esto es, la dinamización de los intereses y de los conflictos en torno de la mejor configuración del sector salud.<br>The article discusses the health care reforms that have been underway in Mexico since 1982. The process is examined as a socio-political phenomenon whose dynamics and nature are the products of past and present conflicts regarding technical and social-work projects, which constitute reflections of certain views of the future. The text first looks at the government-engendered power structure that has dominated the health care sector and that has benefited certain social groups, encouraged their development, and incorporated them into its power structures while simultaneously marginalizing or repressing others. The article next offers an empirical reconstruction of the "social history" of this reform, that is, of the dynamics of interests and conflicts surrounding the question of how the health care sector might best be shaped