Alcides López

Water disinfection was reached by using solar radiation. It uses the effect of the UV-A component of the solar radiation (310 – 400 nm) impinging onto a specific designed reactor and driving two effects for bacteria inactivation, the so called photolysis and photocatalysis. Designed system works under bath conditions, it was optimized under laboratory conditions and tested on site. Preliminary results indicate us that is possible treat volumes of the order of 200 L in just one day. 1. Introduccion La tecnologia de desinfeccion solar de agua “SODIS” [1-7] se basa en la exposicion al sol por algunas horas de botellas de plastico conteniendo el agua contaminada a potabilizar. Los rayos solares actuan contribuyendo con la radiacion UV-A (310 – 400 nm), para la cual el agua es completamente transparente mientras que es muy absorbente de la radiacion infrarroja. La tecnologia SODIS viene siendo aplicada con exito en zonas rurales de diversos paises de la region, pues asegura una reduccion...

It has been synthesized ZnO rods with transversal dimensions in the nanometer range and micrometer size. Nanorods were growth onto a flat glass substrate following the next procedure: First ZnO films with different thicknesses were prepared by spray pyrolysis and were used as a seeds, these films were prepared using zinc acetate solutions at defined pHs (3.5 to 5.5) and a ratio 3:1 of ethanol to water acting as a solvent. Then in order to obtain the rods, the obtained films were then placed in a bath treatment with 2.1 M Zn(NO3)2 and 15 M NaOH at 90 C at different times. The resulting material was characterized morphologically by scanning electron microscopy and transmission electron microscopy; X-ray diffraction was used to study its microstructure and spectroscopic studies in the ultraviolet-visible range were performed in order to characterize its optical absorbance. Prepared rods were studied for the photocatalytic degradation of E-coli bacterias in water under UV-A radiation, a...

We report the enhanced compression resistant and decrement of the annealing temperature of clay bricks, reiforced with recycled soda-lime glass. The Mc Lean and Anderson algorithm was used for three components mixture with restrictions, obtaining 12 mixtures and a pattern without glass, the reactive was prepared previous granular analysis and following the hand makers parameter and using a metallic mold, samples were annealed at 900 °C by 5 hours. Reactive and annealed samples were characterized determining physic and chemical properties by granular analysis, humidity rate, Atterberg limit, density, mineralogical analysis by X-ray diffraction, contraction rate, water absorption, morphology by optic microscopy and compression resistance. This research confirm the possibility of the use of soda-lime recycled glass as a component in the clay bricks production, working as reinforcing material, mixing 30 % glass, 50 % farm ground and 20 % of clay and annealed at 900 °C. At these conditio...

The present work studies the improvement of the physical properties wood-polymer composites obtained by means of infiltration in vacuum of styrene-polyester, methyl methacrylate, and their mixtures. The polymerization was done by gamma radiation and microwaves. Capirona, Oje Blanco and Cumala woods, were used in this study. The polymerization by microwaves depends on the working power. High power produces bubbles, deformation and fractures of the obtained polymer. The minimum dose to provoke the polymerization by gamma radiation is 14 kGy. The wood-polymer composites show low water absorption in comparison with the non-treated wood.

In this work the results of a quantitative analysis by Neutron Activation (NAA), qualitative analysis by Electron Diffraction (ED) and Transmission Electron Microscopy (TEM) of samples from Carancass Meteorite (Puno) is presented. It was found, with exception of Si, a high percentage of Fe (26%), Mg (12,5%), Ni (1,8%), Ca (1,1%) and Al (1%), while in the terrain sample a high amount of Mg (9,2%), Al (5,17%), Ca (6.4%), La, and Sm, as well low amounts of Fe (2,64%) and Mn (955 ppm) were observed, clearly different from meteorite samples. By Electron Diffraction, in meteorites samples high crystallization was observed and monocrystalline diffraction patterns showed concordances with Quartz, Piroxene, Kamacite, Pheldesphat, Contrite and Troilite. We conclude that the meteorite is a silicated phase like Condrite. Radioactive materials were not found.

Solar cells deposited on SnO2:F conductive substrates and TiO2 working as electrode of nanostructured P25 and commercial Dyesol, were sensitized with cis-bis(isotiocianato)bis(2,2’bipiridil-4,4’dicarboxilato)rutenio(II)bistetrabutil ammonia, (N719), the counter electrode was of SnO2:F platinized and an electrolyte constituted by the I-/I3redox couple. Morphological characterizations, crystalline and molecular were made by Transmission and Scanning Electron Microscopy, Electron Diffraction, X-ray Diffraction and FTIR. The coating consists basically of anatase and rutile in smaller proportion, thickness was on the order of micrometers, average grain size of 40 nm. For the characterization of the currentvoltage response of sensitized cells was designed and constructed a solar radiation simulator with a 250W light source, dark camera, an optical bench, IR filter and spectrum analyzer.

To obtain a polymer based composite for industrial and domestic applications requires an extruder, but this commercial equipment is expensive. The equipment for research requires small capacity and preferable should be portable. It has therefore been developed a cheap and portable laboratory extruder, it was tested by extrusion of high density polyethylene (HDPE) and polypropylene (PP). The equipment has been adapted to fabricate polymer based composite probes using wood waste Capirona (Calycophyllum spruceanum Be) and HDPE. The composites were gamma irradiated in the Gammacell 220-Excel with a dose of 100 kGy, then were tested the tensile, bending, hardness, and biodegradation properties. The results were satisfactory and will serve as the basis for a design of an industrial extruder.

Copper oxide (CuO) nanoparticles have been synthesized using gamma irradiation or ultrasound. The antimicrobial activity of CuO nanoparticles was determined by excavation method in plate culture in three microbial strains: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. The initial bacterial concentration was 1x10 CFU / mL and seeded onto Muller Hinton Agar and incubated at 37 °C for 24 h. The CuO nanoparticles obtained by ultrasound are nanospheres with a higher antimicrobial activity for S. aureus than for E. coli and no activity against P. aeruginosa, while CuO nanoparticles obtained by gamma irradiation with a dose of 8 kGy have antimicrobial activity similar to S. aureus and E. coli and those obtained at doses of 15 and 25 kGy only have antimicrobial activity against E. coli.

This investigation show the work developed in the characterization of the density of woods by means of the study of the Attenuation Coefficients of the gamma radiation, using a source of cobalt 60 of 75 mCi of activity and neutrons using the Reactor RP10 as source of neutrons working at 320 kW and using a flow of 5,6*10 (n s cm), the results of the measurement of the Attenuation Coefficients show that the density is influenced by the humidity and the type of wood mainly, so for, the measurements of the density are in agreement with referential and experimental values. As the density has strong influence with important related factors with wood quality, this work being part of big projects that seek to develop autonomous and portables systems of nuclear technology that can identify the type of wood, properties and characteristics for an adequate control in the exploitation and trade.

Neutrography is a non destructive essay, their principal characteristics are the high neutron absorption by light elements and the high contrast of materials of similar thickness, the typical applications that we can mention are the analysis of nuclear fuels, detection of hydrogenated and organic materials, detection of flaws in turbine blades, corrosion in airships components, ceramic materials quality control, drugs and explosive materials detection (useful in the pyrotechnic industry and ammunitions), study of archaeological materials, detection of lubricating film in bearing systems as well as dynamic processes of lubrication and combustion and so for. In the present work, varied examples of applications obtained with the RP-10 reactor are shown.

The reinforcing effects of gamma radiation in a high density polyethylene and wood waste white Bolaina (Guazumacrinita) compounds from Pucallpa region are presented. Samples were mixed with maleic anhydride and extruded at a temperature between 170 and 200 °C, yielding small cylindrical pellets; were subsequently pressed through thermic process between 180 and 200 °C, in a time range between 15 to 20 minutes. The produced samples were exposed to gamma radiation between 50 and300 kGy, and then subjected to mechanical testing of hardness and roughness. It was observed that the hardness and the roughness increases in direct proportion to the increase of the dose of gamma radiation, but the samples subjected to doses in the range of 100 to 150 kGy, had a slight inverse behavior.

Se describe los estudios de inmersion, monitoreo, remocion y analisis de cupones de corrosion asi como los sedimentos de corrosion despues de 407 dias de exposicion en las inmediaciones de los cementerios de elementos combustibles gastados, localizados en la pileta auxiliar del reactor nuclear RP-10 del Centro Nuclear RACSO. Los resultados de la inspeccion visual de estos cupones, indican que la corrosion ocurre aun cuando la calidad de agua de los contenedores sea controlada y mantenga los parametros adecuados. Esta corrosion, originados principalmente por picado, es fuertemente influenciada por la presencia de sedimentos en la superficie, los mismos que forman resquicios que favorecen la formacion de celdas de aireacion diferencial. En una etapa avanzada, la corrosion localizada (picadura) puede conducir a la perforacion de la vaina y liberar material radioactivo durante el largo periodo de almacenamiento en humedo en los cementerios. Teniendo en cuenta que la iniciacion de la cor...

In this work we have evaluated the temperature effect (65, 75, 85 and 95 °C) and type of homogenization (ultrasonic and magnetic agitation) in the solution of cetyltrimethylammonium bromide (CTAB), used as a stabilizer in the synthesis process of Au nanospheres by the wet chemistry method. Sodium borohydride (NaBH4) was used as reducing agent. The understanding and control of experimental parameters during synthesis are the key for a successful production of Au nanospheres. The x-ray diffraction patterns (XRD) showed peaks (111) and (200) characteristic of the gold structure at temperatures of 75, 85 and 95 °C. Absorbance spectra show optical peaks at 528, 527 and 537 nm at temperatures of 75, 85 and 95 °C respectively, typical of the nanospheres of gold, whose intensities were increased with higher temperature of dissolution of CTAB. The plasmonic peak of CTAB at 65 °C was not observed. Analysis by Dynamic Light Scattering in colloidal solutions, shown low dispersity and nanometer ...

We show the process of optical axis alignment of the neutrography device and the optical axis of the neutron beam from the radial duct number 4 of the RP-10 Nuclear Reactor, using optical methods, assisted by radiography, which facilitates the location of the optical axis of the neutron beam by the photographic recording of the space, allowing the alignment of the neutrography plate later. In the process, the location and orientation of the source depends on the placement of the fuel elements immersed inside the duct and between the core and the collimator in the Nuclear Reactor wall. This part of the process depends on the reactor operating personnel who calculate optimally the fuel burn and perform the analysis of the spatial distribution of radiation. The power measurement and the final adjustment of the optical axis of the neutron beam with the optical axis of the instrument are shown in this paper, which will make possible neutrography experiments, as well as neutron diffractio...

In this work, nanoparticles based on magnetite have been synthesized by thermal decomposition via solvent-controlled synthesis in polyols, using triethylene glycol (TREG). The starting precursor were solutions of nitrate and acetatylacetonate of Fe. The samples have been characterized by X-ray diffraction technique (XRD), adsorptiondesorption of N (BET equation model), scanning electronic microscopy (SEM), 2 thermogravimetric analysis (TGA), vibration sample magnetometry (VSM) and Mossbauer

This paper presents a breakthrough in the study of the most important effective parameters, alternative to the standards, of the neutrography acquisition system, considering an irradiation point source and an effective register distance, as well as the dispersive effect that some kind of materials can produce when free neutrons impact them. It was observed that they do not only depend on the shape and distance from the object to the photographic screen or the neutron beam divergence, but also on the constitution of these materials. Hydrogenated materials as well as micro and nano structured solids are capable to produce significant neutron scattering. The study is developed through the analysis of images obtained by neutrography using the neutron beam of the RP-10 nuclear reactor. False color applications to the intensity of the neutron flux which gives a color contrast and simulation of 3D images intensities have helped to interpret the obtained information.

A morphological and microscopic study of the paste from Nasca pottery has been performed. A stereo microscope (x20) and a digital camera were used to study the morphology of the paste while a transmission electron microscope and electron diffraction were used for the study of the microcrystal presents in the paste. The main component of the paste were determined and also some insight about the quality of the paste preparation and calcinations.

We present the gamma radiation effect on a ZnO colloidal suspension prepared from Zn(CH3COO)2.2H2O, LiOH.H2O and ethyl alcohol, and in a second preparation from Zn(CH3COO)2.2H2O, NaHO and propyl alcohol. These colloids were irradiated with gamma rays at 30, 50, 75 and 100 kGy. These irradiated colloids were characterized by Transmission Electron Microscopy and UV-Vis spectroscopy. Also were prepared ZnO films by spraypyrolysis from irradiated colloids, these films were characterized by X-ray diffraction. To evaluate the electrical properties of ZnO films, these films were prepared on alumina substrates with gold electrodes printed and the system was used as gas sensor. The study of the dependence of the conductivity with the temperature of the air and a gas, shows that the electrical conductivity of the sensors varies depending on the crystalline phase, operating temperature and gamma radiation dose. Typical response patterns of n-type and p-type semiconductor sensors have been foun...

A composite containing TiO2 nanoparticles immobilized in a polyvinyl alcohol (PVA) matrix, which was partially crosslinked by gamma radiation, was prepared. The colloidal suspension of TiO2 introduced in the polymeric matrix was characterized by UV-VIS, transmission electronic microscopy and X ray diffraction (XDR), whereas the composite PVA-TiO2 was characterized by UV-VIS and XRD. The efficiency of this material in photocatalysis has been evaluated against methylene blue. A fast fotodegradation of the dyestuff has been observed in different pH values.

In this work we show the study of aging of the materials applied on neutron instrumentation system, by performing comparative morphological analysis of the plastics used as insulation, in a new and irradiated coaxial cable in its working position, close to the core of the Nuclear Reactor RP-10, for a time approximately of one year. Macroscopic analysis of the exterior surfaces fractography was performed by scanning and transmission electron microscopy, also microscopic cross sections were analyzed, showing that higher doses of radiation induce vitrification of the plastics, with internal bubbles that grow, producing internal stress, fracture and reducing their insulator properties of the matrix, these important results serve to decision making, about repair or replacement of the components affected by ageing caused by the neutron induced radiation. 1. Introduccion

El análisis por Fluorescencia de Rayos X (FRX) Dispersiva en Energía, ha permitido la caracterización elemental de algunos pigmentos aplicados en la decoración de recipientes utilizados por nuestros antepasados de la Cultura Chincha. Complementariamente, mediante la Microscopía Electrónica de Transmisión (MET) ha sido posible la caracterización morfológica y cristalina. Los resultados han permitido identificar la presencia de sulfuro de mercurio (HgS) (cinabrio) en el pigmento rojo sobre mate; los pigmentos negro y blanco están constituidos por materiales de aspecto orgánico; en el caso de colores como el marrón oscuro se observó constituidos por materia orgánica y óxido férrico. Este trabajo también muestra que un equipo portátil de Fluorescencia de Rayos X, es el más indicado para el estudio de bienes de nuestro patrimonio cultural, sobre todo de aquellos que por sus dimensiones y estado de conservación sean difíciles de trasladar de un sitio arqueológico o museo a un laboratorio ...

We have been prepared composite materials based on powder of Capirona wood waste and low density polyethylene, the samples have been pressed in equal proportions and heat treated in an oven at 170 oC. Later, they were tested for biodegradation using Polyporus sanguineus fungus (for 10 weeks), water absorption, fire resistance and flammability. The obtained composite based on polymer-wood dust has shown durability, better resistance to degradation, lower water absorption and lower flammability than the untreated wood, increasing the economic value of this native wood.

Ultrasound has been applied to cotton fibers with a solution of copper sulphate to obtain copper oxide nanoparticles impregnated in the fibers. The electron diffraction characterizations show that the formed material consists of phases of Cu64O, Cu4O and CuO, by X ray diffraction the material is basically CuO. The transmission electron microscopy shows a micro and nanostructured copper oxide particles, changing from filiform nanostructures to ball nanoparticles, also it appreciates the formation of microparticles, porous and monocrystalline growths, having adhered to the cotton fibers, these materials presented antimicrobial activity against to the S. aureus bacteria in major grade than E. coli.

Hydroxyapatite is a material that is used for orthopaedic surgery and traumatology as well as for odontology and maxilo-facial surgery due to its biocompatibility, bioactivity and osteoconduction. To be used in patients, hydroxyapatite must be sterile and thus, previously should undergo an sterilization process. This work aims to characterize a biohydroxyapatite (BHA) sterilized by gamma radiation, treated at doses of 25, 50, 100, 200 y 500 kGy, using gravimetric techniques, FT-IR spectroscopy, X-ray diffraction and fluorescence, scanning electron microscopy as well as organoleptic tests. For product irradiation, dosimetric tests were performed and the sterility of the product was verified through microbiological tests. Results of characterization tests concluded that the BHA irradiated at 25 kGy is appropriate for medical applications.

In this work we show the characterization results of the wood-polymer composite, obtained by Capirona particulate at 710 microns with high density polyethylene and polypropylene. These have been mixed with maleic anhydride and extruded at a temperature between 150 and 180 °C, yielding small cylindrical pellets. Subsequently, the pellets were pressed into test pieces and heat treated at 170 °C. Some of those pieces have been gamma-irradiated with a cobalt-60 source. The samples were subjected to mechanical tests and biodegradation tests with the Polyporus sanguineus and Schizophyllum commune fungus, changes were observed in mechanical properties, especially when it has as input polypropylene, improving bending the compound, also polyethylene have noticed an improvement in resistance to degradation and reduced water absorption.