Irradiation

The objective of this investigation is to develop a shear punch testing (SPT) procedure and standardize it to evaluate the mechanical properties of irradiated fuels in a hot-cell so that the tensile behavior can be predicted using small volumes of material and at greatly reduced irradiation costs. This is highly important in the development of low-enriched uranium fuels for nuclear research and test reactors. The load-displacement data obtained using SPT can be interpreted in terms of and correlated with uniaxial mechanical properties. In order to establish a correlation between SPT and tensile data, sub-size tensile and microhardness testing were performed on U-Mo alloys. In addition, efforts are ongoing to understand the effect of test parameters (such as specimen thickness, surface finish, punch-die clearance, crosshead velocity and carbon content) on the measured mechanical properties, in order to rationalize the technique, prior to employing it on a material of unknown strength.

The effect of gamma radiation on the dyeing of cotton with extract of turmeric (Curcuma longa L.) powder has been investigated. Cotton fabric and turmeric powder were irradiated to absorbed doses of 1, 2, 3, 4 and 6 kGy using Co-60 gamma irradiator. Dyeing parameters such as temperature, pH and mordant concentration were optimized. Dyeing was performed using un-irradiated and irradiated cotton with the extracts of un-irradiated and irradiated turmeric powder in order to investigate the effect of radiation treatment on the colour strength of dyed fabric. The reported data of un-irradiated and irradiated fabrics dyed with un-irradiated and irradiated dyes were obtained using the spectraflash SF-650. The colourfastness to light, rubbing-and washing-fastness properties showed that gamma irradiation has improved the dyeing characteristics from fair to good.

The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic matter content. Soils were spiked with the diphenyl-ether herbicide and irradiation experiments were performed either in the laboratory with a solar simulator (xenon lamp) or outside, under natural sunlight irradiation; other soil samples were kept in the dark to control the retention reaction. Kinetic parameters of both retention and photochemical reactions were calculated using zero-, first- and second- (Langmuir-Hinshelwood) order equations, and best fit was checked through statistical analysis. The soil behaviors were qualitatively similar but quantitatively different, with the soil sampled from the Nea Malgara region much more sorbent as compared with Preveza soil. All studied reactions followed second-order kinetics and photochemical reaction...

The safety of irradiated pork packed in 25% CO2:75% N2 and stored at abuse temperature (10 or 15°C) was assessed by inoculation studies involving Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Yersinia enterocolitica and Clostridium perfringens. Irradiation to a dose of 1.75 kGy reduced pathogen numbers to below the detection limit of 102 cells g-1. When higher inoculum levels were used (106 cells g-1) irradiation at 1.75 kGy reduced pathogen numbers by 1 –>5 log10 cycles depending on strain. Clostridium perfringens was the most resistant, and Y. enterocolitica the most sensitive of the pathogens studied.In all cases when high numbers (106 to 107g-1) of spoilage and/or pathogenic bacteria were present initially on the pork the meat appeared spoiled, and although irradiation reduced the number of microorganisms, the meat was still unacceptable from a sensory viewpoint after treatment.It was concluded that the microbiological safety of irradiated, modified atmosp...

In the frame of a project aimed at developing a new type of optical solar reflectors we present the scientific and technological issues addressed during irradiations of nano-hybrid polyimide films deposited on quartz by using 20 keV electron beam from a modified use of Scanning Electron Microscope and with ultraviolet (UV) dose equal to 300 space-equivalent Sun hours.

Two aspects critical to the fracture behavior of three-wire stainless steel cladding were investigated by the Heavy-Section Steel Technology (HSST) Program: (1) radiation effects on cladding strength and toughness, and (2) the response of mechanically loaded, flawed structures in the presence of cladding (clad plate experiments).

The purpose of this research was to establish the dose of UV light (253.7 nm) needed to inactivate Listeria monocytogenes in distilled water, fresh brine (9% NaCl), spent brine, and diluted (5, 35, and 55%) spent brine, using uridine as a chemical actinometer. Strains N1-227 (isolated from hot dog batter), N3-031 (isolated from turkey franks), and R2-499 (isolated from meat) were mixed in equal proportions and suspended in each solution prepared so as to contain 10(-4) M uridine. Samples were irradiated in sterile quartz cells for 0, 5, 10, 15, 20, 25, or 30 min. Inactivation was evaluated by serially diluting samples in 0.1% peptone, by surface plating in duplicate onto modified Oxford agar and Trypticase soy agar with yeast extract, and by enrichment in brain heart infusion broth, followed by incubation at 37 degrees C for 24 to 48 h. For dose measurements, the absorbance (262 nm) was measured before and after irradiation. Differences were observed in population estimates dependin...

The content of reducing sugars and asparagine, responsible for the formation of acrylamide, was determined in eight Indian potato varieties. Among these, Kufri chipsona-2 and Kufri lavkar showed the lowest level of reducing sugar (680.68 ± 56.50 mg/kg) and asparagine (2074.36 ± 122.27 mg/kg), respectively. The acrylamide content in potato chips prepared from Kufri chipsona-2, the variety that is used commercially in India for making potato chips was also the lowest. Irradiation of this variety of potatoes at the sprout inhibition dose of 60 Gy and subsequent storage for six months showed a 10.7% lower content of reducing sugars at both 14 and 4 °C. The acrylamide content was 8.41% and 6.95% lower in chips from irradiated potatoes stored at 14 and 4 °C than the corresponding non-irradiated controls. The colour of the chips was also better in irradiated potatoes as judged from the L∗ and a∗ values.► Indian varieties of potatoes were screened for their ability to form acrylamide. ► Irradiation reduces sprouting, and hence the reducing sugars. ► Irradiated potatoes showed lower content of acrylamide in potato chips.

Starch isolated from lotus stem was treated by gamma-irradiation at different doses of 5, 10 and 20 kGy. Physicochemical, morphological and pasting properties of irradiated lotus stem starches were investigated and these properties differed significantly. Carboxyl content, water absorption capacity, amylose leaching, and transmittance increased, whereas swelling power, apparent amylose content, syneresis, and pasting properties decreased after the modification in a dose dependent manner. Observation under scanning electron microscope (SEM) showed that some of the starch granules were destroyed by gamma-irradiation and the breakage was much greater at a higher dose (20 kGy). X-ray diffraction pattern remained the same upon irradiation but a dose dependent decrease in relative crystallinity was observed.

mA new solar map, based on the latest average irradiation of 37 cities and hours of bright sunshine in 40 other Venezuelan places published by the Venezuelan Air Force, has been plotted. For all places where both values were reported, the linear regression correlation between global clearness index (Kt = H/Ho) and hours of bright sunshine relative to day length (s/S) has been calculated and later used to predict irradiation where only hours of bright sunshine are known. This extended set of points has been introduced in a surface regression model to obtain isolines of irradiation for each month and the average year and plotted on a digitiiized map of Venezuela. The results obtained by this method correspond to the knowledge of climate zones of this country.

High quality inoculants used as bio-fertilisers and bio-pesticides depend on having high concentrations of the microorganism(s), long shelf-life and a formulation appropriate for field delivery. To maintain the microorganisms in a viable state, commercially available carrier materials are typically based on milled peat, clays, rice, bran, seeds, or other complex organic matrices. To manufacture a high quality microbial product, it is essential that the carrier material is pre-packaged and pre-sterilised. This allows for non-competitive multiplication and maintenance of the microorganisms in a nutrient rich environment. This paper reports on the efficacy and problems inherent in the sterilisation of complex carbon-based carrier materials such as peat. Resident microbial survivors of gamma irradiation doses in excess of 50 kGy, commonly Gram positive spore-formers such as Bacillus or actinomycetes were consistently observed.

The effect of c-irradiation on the quality of chives was evaluated. The samples were irradiated at 1.0 and 2.0 kGy, stored at 4°C for 10 days and used for microbiological (aerobic mesophilic, moulds and yeasts, E. coli and Salmonella sp), biochemical (vitamin C and lipoperoxide (MDA) contents and superoxide dismutase (SOD) and guaiacol peroxidase (POX) activity) and sensorial evaluation. For irradiated samples, the total counts of aerobic mesophilic and moulds and yeasts showed a reduction of 6 log cycles during storage, and colour analysis showed no significant difference (P > 0.05) for the b*-value. The contents of vitamin C were not significantly affected by irradiation and storage time. The MDA contents and SOD activity changed insignificantly at both c-irradiation levels after storage, while POX was significantly increased (P 0.05) at 1 kGy. Samples irradiated at 2.0 kGy presented sensorial acceptance after the storage. These results show that c-irradiation increases the shelf life of chives without significant changes in their quality.

The aim of this work was to analyze by means of simple mathematical models the effect of different integral doses of g irradiation on the mechanical properties of blends of polypropylene (PP) with virgin and recycled high density polyethylene (v-HDPE, r-HDPE), with and without woodflour-type filler. Analysis of the results at an integral irradiation dose between 0 and 50 kGy shows that crosslinking predominates in the PP/v-HDPE blend whereas degradation is predominant in the PP/r-HDPE blend, due to the characteristics of the recycled material. For the 50-70 kGy interval, both blends (PP/v-HDPE, PP/r-HDPE) suggest the possibility of competing processes, chain breaking being the most marked in the PP/r-HDPE blend. For the 0-50 kGy range in the blends with woodflour, the behavior of the PP/v-HDPE/woodflour composite was more complex since the polynomial equations are of third order for both tensile properties analyzed: Young's modulus and elongation at break. The behavior of the PP/r-HDPE/woodflour composite is complex suggesting simultaneous crosslinking and degradation. Both composites show a bimolecular process within the 50-70 kGy range which signifies a second-order dependence.

Aqueous solutions of humic substances (humic and fulvic acids) were irradiated with light at ~, = 254 nm followed by analyses of total organic carbon (TOC), ultraviolet (UV) absorbance and molecular weight distribution. A degradation of the dissolved humic compounds by up to 50% after 6 h was observed. The average molecular weight decreased (from 1800 to approx. 300) as well as the UV absorbance of the remaining organic fraction. Low molecular weight organic acids were formed during the irradiation and tentatively identified by capillary electrophoresis (formic, acetic, succinic, and oxalic acids). The low molecular organic acids continued to degrade by further irradiation; the loss of TOC is assumed to be due to COz formation. Indications of a large-scale photo degradation process in nature was observed as a seasonal variation of the ratio humic substances/TOC related to the length of the day. Weekly sampling and analysis of UV absorbance and TOC in the Kalix River in northern Sweden indicate a higher humic fraction of the TOC during winter (dark period) than during summer.

A preliminary study was performed on fresh and irradiated Tuber aestivum black truffles to investigate the presence of mutagenic and antimutagenic activities in the fresh product and to examine the possible effects of treatment with gamma rays. The study was performed on aqueous and ethanolic extracts from truffles, untreated or irradiated with a final dose of 1.5 kGy. Two Salmonella typhimurium His À strains, TA 98 and TA100, were used. The preliminary results indicate that black truffles may contain compounds having an inhibitory effect against direct and indirect acting mutagenic compounds. The irradiation did not lead to the formation of mutagenic compounds, but the level of antimutagenic activity was slightly decreased after the treatment.

Electron-beam initiated crosslinking of a poly(vinyl chloride)/epoxidized natural rubber blend (PVC/ENR), which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20 -200 kGy) and concentrations of TMPTA (1-5 phr). The gelation dose was determined by a method proposed by Charlesby. It was evident from the gelation dose, resilience, hysteresis, glasstransition temperature (T g ), IR spectroscopy, and scanning electron microscopy studies that the miscible PVC/ENR blend underwent crosslinking by electron-beam irradiation. The acceleration of crosslinking by the TMPTA was further confirmed in this study. Agreement of the results with a theory relating the T g with the distance between crosslinks provided further evidence of irradiation-induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR is also proposed.

Dyeing behavior of gamma irradiated cotton fabric using Lawson dye extracted from henna leaves has been investigated. Cotton and dye powder are irradiated to different absorbed doses of 2, 4, 6, 8 and 10 kGy using Cs-137 gamma irradiator. The dyeing parameters such as dyeing time, electrolyte (salt) concentration and mordant concentrations using copper and iron as mordants are optimized. Dyeing is performed using un-irradiated and irradiated cotton with dye solutions and their color strength values are evaluated in CIE Lab system using Spectraflash -SF650. Methods suggested by International Standard Organization (ISO) have been employed to investigate the colourfastness properties such as colourfastness to light, washing and rubbing of irradiated dyed fabric. It is found that gamma ray treatment of cotton dyed with extracts of henna leaves has significantly improved the color strength as well as enhanced the rating of fastness properties.

This study deals with extraction of vanillin from cured vanilla pods using conventional soxhlet extraction and ultrasound assisted extraction. Effect of various extraction parameters such as type of the solvent (6 different solvents viz. ethanol, methanol, acetonitrile, acetone, chloroform and hexane), quantity of beans (1–3 g), operating temperature (in the range 90–100 °C) for soxhlet extraction and pre-leaching time (in the range of 30–90 min) for ultrasound assisted extraction, on the extent of extracted vanillin has been investigated in this work. It has been conclusively established that the use of polar solvents resulted in maximum extent of extraction for both the types of extraction operations. For soxhlet extraction, an increase in operating temperature from 90 °C to 100 °C was found to increase extent of extraction by 30% whereas for ultrasound assisted extraction, pre-leaching stage for 30 min duration was found to be beneficial in enhancing the extent of extraction by about 20%. The use of ultrasonic irradiation resulted in intensification of the extraction operation of vanillin significantly as confirmed from the results that in soxhlet extraction, an operating temperature of 95 °C and solvent to solute proportion of 66.67 ml/g (most commonly used conditions) resulted in release of around 180 ppm in 8 h whereas ultrasonic assisted extraction required only 1 h for release of around 140 ppm vanillin concentration at similar proportions of solvent to solute and under ambient operating temperature.

Space-based solar power has conventionally used solar panel arrays on satellites to harness light energy from the Sun, the authors of this communication suggest the innovative utilization of mirrors to support solar power generation for lunar missions. The existence of peaks of eternal light (PELs) on the lunar surface can be used to our advantage in a novel design allowing for continuous, unlimited access to a light source. However, this has yet to be tested and this may prove to have further limitations in practice. (

Mixtures of starch, xanthan gum and either polyvinyl alcohol, epichlorohydrin, valeric acid or adipoyl chloride were extruded. Properties of extrudates including apparent viscosity, water solubility, water absorption indices and exrudate expansion were measured for different proportions of xanthan gum, 70% amylose starch (with or without irradiation) and chemical agents. Extrusion with chemical agents and irradiation changed physical properties of both starch and xanthan gum. Expansions of extrudates were higher than that of starch. Viscosity of extrudates increased with xanthan gum concentration. The addition of 1% (w/w) polyvinyl alcohol had the greatest effect of the chemical agents. Irradiation increased the apparent viscosity of starch-xanthan gum mixtures.

Mechanical and thermal properties of devulcanized rubber (DR)/polypropylene (PP)/ethylene propylene diene monomer blends (EPDM) were studied at various concentrations of dicumyl peroxide (DCP) and gamma radiation doses. The blends showed improved mechanical properties for vulcanized sample. The coupling of DR/PP/EPDM with different proportions of DCP was investigated by X-ray diffraction and scanning electron microscopy techniques. Evaluation of the developed blends, unirradiated and gamma irradiated, was carried out using elastic modulus, tensile strength, elongation at break, thermogravimetric analysis, kinetic analysis, and DSC measurements.

ABSTRA ABSTRA ABSTRA ABSTRA ABSTRACT CT CT CT CT: : : : : The ubiquitous natur L. monocytogenes L. monocytogenes L. monocytogenes L. monocytogenes and the quality of RTE meat is discussed. and the quality of RTE meat is discussed. and the quality of RTE meat is discussed. and the quality of RTE meat is discussed. and the quality of RTE meat is discussed.

The study is about how the addition of ionizing radiation affects the growth and
development of Phaseolus vulgaris. The main objective of this study was to determine
whether the irradiation process on the seed samples affect their growth specifically in
terms of the weekly numbers of germinated seeds, numbers of leaves present, stem
lengths, leaf widths, and leaf lengths.

Solar panels are gaining importance as a major alternate source of energy in the prevailing condition of depleting non renewable energy sources. Photovoltaic (PV) modules are being increasingly used in large as well as small scale installations. The performance of PV panels is affected by the shading effect due to trees, passing of clouds, neighboring buildings and any other means. This paper is an attempt to carry out systematic study of the effect of shading on the Power output, Fill factor and Efficiency of solar panel. A direct correlation was found between short circuit current and solar irradiation under uniform shading conditions. On the other hand, non uniform shading conditions yielded a variety of performance behavior. Such shading conditions should be avoided for better performance of solar panels.

Assessment of the viability for different types of solar PV tracking technologies rely on the assessment of whether the annual production of the different tracking technologies is increased enough relative to a benchmark Fixed Tilt system to compensate for the higher installation and operational costs incurred by the tracking systems. To investigate this issue, we use the PVsyst software to simulate electricity production from three representative solar PV systems at Karnataka. In these simulations we use hourly solar irradiance, weather and surface albedo data, technical data relating to both module and inverter characteristics and impacts associated with module soiling and shading.

The type of produce, process conditions, and prior temperature management will all affect the mix of microorganisms found on fresh produce. Normally, fresh produce will be covered by a complex mix of bacteria, fungi and yeasts that are characteristic of that fruit or vegetable. For example, carrots typically have large numbers of Lactobacillus and other lactic acid bacteria while apples may have relatively large numbers of yeasts. Which of these microorganisms will come to dominate the population will be a function of the make-up of the original population on the product in the field, distribution time, distribution temperature and the atmosphere within the package. Another chief determinant of microbial populations will be the physiological condition of the product. Factors that injure or weaken the plant tissues may be expected to encourage microbial growth while conditions that maintain the physiological integrity of the tissues may be expected to discourage microbial growth. Each of these factors can be expected to affect the make-up of the microbial population in characteristic ways but always constrained by the initial condition of original population makeup. This paper describes which microorganisms are favored by given conditions in order to develop a concept of microbial management designed to favor desirable microbes at the expense of undesirable ones. Particular emphasis will be placed on the effects of modified atmospheres on microorganisms, especially human pathogens.

Spices are food additives that are used in many different area of food technology. Production of
meat products, for instance, cannot be imagined without utilization of spices as additives.
Oregano, red papers, black papers, clove, garlic, basil and many other plant spices are frequently
used for both taste improvement and food safety reasons. Most of the spices contain essential oils
that are sensitive to thermal degradation processes. Thus, an alternative to conventional
preservation processes for enabling microbial safety of the spices should be considered. Gamma
irradiation technology is such a technology that enables guarantying of the microbial safety while
preserving the chemical stability of the thermo sensitive essential oils.
In this work a microbiological method for testing the efficiency was developed. As test materials
black papers and red papers were used. The preliminary investigation showed that the irradiation
resulted in several orders of magnitude lower number of the total cell count of microbial cells.

Irradiation doses currently applied to sterilize Mexican fruit ßies, Anastrepha ludens (Loew) (Diptera: Tephritidae), for release under the sterile insect technique eradication campaign in Mexico, were reviewed in an effort to increase sterile male performance in the Þeld. A dose maximizing sterility induction into wild populations was sought by balancing somatic Þtness with genetic sterility. Doses of 40, 60, and 80 Gy induced 95% or more sterility in all males, which in turn induced similar degrees of sterility into a cohort of wild ßies in the laboratory. However, a low dose of 40 Gy was sufÞcient to completely suppress egg production in females. Similarly, a mild carryover of genetic damage might have been transferred to the F1 progeny of males irradiated at 40 Gy crossed with fertile wild females. Our results suggest that the 80-Gy dose currently applied in Mexico can be lowered substantially without jeopardizing program goals. This view could be strengthened by comparing performance of males irradiated at different doses under more natural settings. In general, we discuss the value of determining irradiation doses for pest species where females are more radiosensitive than males, by selecting the dose that causes 100% sterility in females.

A simple and green method has been used to develop beads that are able to adsorb textile dyes. Chitosan is known as the product of deacetylation of chitin, which are harvested from the shells of crustaceans such as crabs, prawns and seashells. The advantages of using chitosan include its versatility, abundance, biodegradable, non-toxic, low-cost and high performances. It has been widely used in the
environmental applications, especially for the adsorption of metal ions, dyes and organic compounds. In this study, chitosan was grafted with polyethyleneimine (CS-PEI) and crosslinked with glutaraldehyde to
improve its adsorption capacity and mechanical strength. The grafting process only took about 20 minutes under the irradiation of a domestic microwave, without the use of any radical initiator or catalyst. The
modified beads could completely remove Amaranth Red dye (ARD), as a model pollutant, from the aqueous solution. In fact, its adsorption also increased by double as compared to the unmodified beads. The modified beads were also tested on samples of wastewater from a batik factory and was proven to be effective. The performance of the CS-PEI beads were optimized by varying its pH (3 – 12), adsorbent dosage (0.25 – 2.00 g), contact time (0 – 24 h) and initial dye concentration (20 – 100 mg/L) in a batch system.

Alloying has been very common practice in materials engineering to fabricate metals of desirable properties for specific applications. Traditionally, a small amount of the desired material is added to the principal metal. However, a new alloying technique emerged in 2004 with the concept of adding several principal elements in or near equi-atomic concentrations. These are popularly known as high entropy alloys (HEAs) which can have a wide composition range. A vast area of this composition range is still unexplored. The HEAs research community is still trying to identify and characterize the behaviors of these alloys under different scenarios to develop high-performance materials with desired properties and make the next class of advanced materials. Over the years, understanding of the thermodynamics theories, phase stability and manufacturing methods of HEAs has improved. Moreover, HEAs have also shown retention of strength and relevant properties under extreme tribological conditions and radiation. Recent progresses in these fields are surveyed and discussed in this review with a focus on HEAs for use under extreme environments (i.e., wear and irradiation) and their fabrication using additive manufacturing.

This study was designed to evaluate the potential uses of a natural biomaterial-Chitosan as plant growth promoter and anti-fungal agent. Chitosan treated with Co-60 gamma radiation at different doses, were used to evaluate the efficiency of irradiated chitosan on tea plants. The aim of this study was to measure the effects of various concentrations of irradiated chitosan (300, 500, 1000 ppm) solutions in order to get best response of tea plants in terms of various attributes. Chitosan were applied through foliar spraying at 7 days interval. The growth attributes like-total number of buds, fresh and dry weight of buds, average leaf area, and weight per bud and anti-fungal activities were determined at 10 days interval after foliar application of biomaterials for 11 weeks. The results showed increase in productivity (about 38%, based on fresh weight of tea leaves) and it reduced the total fungal count dramatically (more than 100 times in contrast with the control).

Radioactive sources are used throughout the world including consumer products, food and agriculture, industry, medicine and scientific research, transport, and water resources and the environment. However, management has been lost over a tiny low fraction of these sources, generally leading to accidents of that some had serious consequences. Today there is a growing concern that terrorist or criminal groups could be used to build a bomb with radioactive material commonly known as radiological dispersal device (RDD) or "dirty bomb" and it can be used explosive force to disperse the radioactive material over an enormous territory. There is a clear need to reinforce the Physical Protection System to keep radioactive sources from any malignant use or coincidental abuse. This paper presents one of the basic elements of Physical Protection system for detection function, which combined Arduino microcontroller, magnetic sensors, motion detection sensors, and vibration sensors with IoT platform. This system is intended for Gamma Irradiation Facility that contains Co 60 highly radioactive sources, for security, and detection by using various sensors and Arduino MKR Wifi 1010 microcontroller. When the microcontroller detects the signal from magnetic sensors and vibration sensors, the system will inform the central alarm station (CAS) by activating the buzzer for sounding the alarm. Motion detection sensors will identify the presence of infrared light produced from a warm object. If the movement is detected by the sensor within the motion detection range, the message provides by Blynk is send to a smartphone, able to get the real-time notification to the people in the community. The main preferences of such a system include conclusive securities, lower costs, and low maintenance.

Ultraviolet (UV) irradiation is a common disinfection option for water treatment in the developed world. A sufficient dose of ultraviolet light inactivates most microorganisms. Ultraviolet light is produced by an electric arc struck in mercury, or more recently, xenon vapor much like ordinary florescent bulbs. The UV spectrum runs from 100 and 400 nanometers (nm) with the optimal wavelength for bacterial disinfection occurring between 200 and 280 nm. The most UV-resistant organisms are viruses, specifically Adenoviruses, and bacterial spores. The protozoon Acanthamoeba is also highly UV resistant. Bacteria and cysts of Cryptosporidium and Giardia are more susceptible. As with any disinfectant, the process consists of dose and contact time with different organisms being affected differently. The dose for UV is expressed in millijoules per square centimeter. To increase the dose, you can increase the output of the lamp, decrease the distance to the lamp, increase the transmittance of the water or slow the flow through the reaction chamber. The objective of this study was to review the literature on UV disinfection and extract quantitative information about the relation between the inactivation of micro-organisms and the applied UV fluence. The quality of the available studies was evaluated and only high-quality studies were incorporated in the analysis of water disinfection. The results show that UV is effective against all waterborne pathogens.

We discuss calculations of probability distribution functions (PDF) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPE). The PDF's are used in significance tests of the effectiveness of potential radiation shielding approaches. Uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments are considered in models of cancer risk PDF's. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. We show that the cancer risk uncertainty, defined as the ratio of the 95% confidence level (CL) to the point estimate is about 4-fold for lunar and Mars mission risk projections. For short-stay lunar missions (<180 d), SPE's present the most significant risk, however one that is mitigated effectively by shielding, especially for carbon composites structures with high hydrogen content. In contrast, for long duration lunar (>180 d) or Mars missions, GCR risks may exceed radiation risk limits, with 95% CL's exceeding 10% fatal risk for males and females on a Mars mission. For reducing GCR cancer risks, shielding materials are marginally effective because of the penetrating nature of GCR and secondary radiation produced in tissue by relativistic particles. At the present time, polyethylene or carbon composite shielding can not be shown to significantly reduce risk compared to aluminum shielding based on a significance test that accounts for radiobiology uncertainties in GCR risk projection.

Linear low-density polyethylene (LLDPE), based on butene-1 or hexene-1, was irradiated with ␥-rays under vacuum or in the presence of air. The study focused on the influence of the dose rate and the ␥-dose on the thermal properties of LLDPE. Differential scanning calorimetry, thermogravimetric analysis (TGA), and TGA/FTIR techniques were used to address the thermal behavior as a result of ␥-irradiation. During this irradiation, competition between crosslinking and scission reactions, subsequent to oxidation reactions, occurred in the polymeric material, which strongly depends on the experimental conditions. A decrease of the crystallinity for ␥-irradiated samples was observed in particular for samples irradiated under vacuum. This observation may be explained by increased hindrance of segment mobility due to crosslinking reactions that prevent crystal growth. TGA investigations revealed an enhancement of the thermal stability for samples irradiated under vacuum but not for those irradiated in air.

Dyeing behavior of gamma irradiated cotton fabric using Lawson dye extracted from henna leaves has been investigated. Cotton and dye powder are irradiated to different absorbed doses of 2, 4, 6, 8 and 10 kGy using Cs-137 gamma irradiator. The dyeing parameters such as dyeing time, electrolyte (salt) concentration and mordant concentrations using copper and iron as mordants are optimized. Dyeing is performed using un-irradiated and irradiated cotton with dye solutions and their color strength values are evaluated in CIE Lab system using Spectraflash -SF650. Methods suggested by International Standard Organization (ISO) have been employed to investigate the colourfastness properties such as colourfastness to light, washing and rubbing of irradiated dyed fabric. It is found that gamma ray treatment of cotton dyed with extracts of henna leaves has significantly improved the color strength as well as enhanced the rating of fastness properties.

The reactions of chlorine atoms and activated carbon have been studied over the temperature range of 200–400 °C using an isothermal flow reactor in conjunction with 337 nm laser photolysis of Cl2. These studies have shown that carbon tetrachloride is the major product, with chloroform, methylene chloride, and methyl chloride being formed in progressively decreasing yields. Trace quantities of methane, ethane, and dichloroethylenes were also observed. Mechanisms of carbon fragmentation by successive addition of chlorine atoms are proposed. The formation of small chlorinated hydrocarbons by the direct reaction of chlorine with carbon may be a key link in both the de novo and precursor pathways of formation of PCDD/F.

In order to improve the compatibility between natural fibers and polypropylene (PP) and polypropylene-ethylene propylene diene terpolymer (PP-EPDM) blends, the functionalization of both matrices with maleic anhydride (MA) is investigated in this study. The morphological observations carried out by scanning electron microscopy show that the incorporation of small amounts of functionalized polymer considerably improves the adhesion at the fiber-matrix interface. In these cases, the fibers are perfectly embedded in the matrix in relation to the composites prepared with the pure homopolymers, and a significant increase in the composite strength is also observed, particularly, after the incorporation of both modified polymers (MAPP and MAEPDM). Thus, it is possible to correlate better interfacial adhesion with the improvement of mechanical properties. It is assumed that the functionalization of the matrix reduces interfacial stress concentrations and may prevent fiber-fiber interactions, which are responsible for premature composite failure. The crystallization kinetics of PP were also analyzed by differential scanning calorimetry (DSC). It was observed that both flax fiber and rubber behave as effective nucleant agents, accelerating PP crystallization. Moreover, these results are particularly relevant when the grafted matrices are added to the composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2170–2178, 2003

Maduración de frutos de aguacate hass tratados con radiación gamma Agrociencia, vol. 36, núm. 6, noviembre-diciembre, 2002, pp. 667-673 Colegio de Postgraduados Texcoco, México Disponible en: http://www.redalyc.org/articulo.oa?id=30236604 Cómo citar el artículo Número completo Más información del artículo Página de la revista en redalyc.org Sistema de Información Científica Red de Revistas Científicas de América Latina, el Caribe, España y Portugal

We and others have demonstrated that the milieu created by ionizing radiation (IR) used for conditioning plays a major role in the development of acute graft-versus-host disease (aGVHD). We reasoned that antioxidants that could inhibit IR induction of inflammatory cytokines and/or apoptosis might reduce the incidence or severity of aGVHD. Therefore, BALB/c mice were treated with amifostine, n-acetyl cysteine (NAC) or pyrrolidine dithiocarbamate (PDTC) prior to transplantation with allogeneic C57Bl/6 bone marrow and spleen cells. None of 30 amifostine-pretreated mice developed weight loss or other signs of aGVHD and they rejected their allogeneic transplants. However, pretreatment to groups of five mice each with molar equivalent doses of NAC or PDTC accelerated death, and lower doses did not prevent aGVHD. In vitro tests demonstrated that PDTC and NAC acted as pro-oxidants when incubated with isolated normal mouse lymphocytes, whereas amifostine and its active metabolite WR-1065 did not. The conclusion that amifostine protected immune function from IR in vivo was further supported by the fact that amifostine and WR-1065 preserved the response of radiated normal lymphocytes to respond to PHA and both stimulated growth of non-radiated, non-PHA-treated normal lymphocytes in vitro. Taken together, these data caution the use of amifostine in allogeneic transplantation.