Gamma Irradiation

Gamma irradiation is widely used for sterilization; however, its effect on elimination of amplifiable DNA, an issue of relevance to molecular diagnostic approaches, has not been well studied. The effect of gamma irradiation on the viability of Staphylococcus epidermidis and Escherichia coli (using quantitative cultures) and on their DNA (using quantitative 16S rRNA gene PCR) was evaluated. Viability was abrogated at 2.8 and 3.6 kGy for S. epidermidis and E. coli, respectively. The radiation dose required to reduce viable bacteria by one log10 (D10 value) was 0.31 and 0.35 kGy for S. epidermidis and E. coli, respectively. D10 values for amplifiable DNA extracted from bacteria were 2.58 and 3.09 kGy for S. epidermidis and E. coli, respectively, whereas D10 values for amplifiable DNA were significantly higher for DNA extracted from irradiated viable bacterial cells (22.9 and 52.6 kGy for S. epidermidis and E. coli, respectively; P<0.001). This study showed that gamma irradiation of ...

It is well known that polypropylene undergoes simultaneous crosslinking and degradation under irradiation. However, there are speculations regarding the formation of branching under special conditions. It is also well known that the melt-strength property of a polymer increases with molecular weight and with long-chain branching due to the increase in the entanglement level. This study was a contribution to the

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.

Bioerodible polymers used in controlled drug delivery systems, such as poly(lactic-co-glycolic acid) (PLGA) undergo radiolytic degradation during γ-irradiation. In spite of the considerable practical importance, yet only little knowledge is available on the consequences of this sterilization method on the resulting drug release patterns in a quantitative way. The major objectives of the present study were: (i) to monitor the

This study was conducted to evaluate the efficiency of physical and chemical methods to extend the shelf life of apple fruits by control the blue mold disease causing by Penicillium expansum. Apple fruits are subjected to different temperatures between 38, and 50C for 24 hr. and stored at 0C for 4 months. Increasing in temperature caused decreasing in firmness and blue mold incidence percentage (%) caused by P. expansum. At 50C the treated apple fruits gave sharp softness and inhibition of blue mold incidence (%) caused by P. expansum exposing for 4 days and cold storage at 0C for 4 months and 5 days at 20C. Dipping apple fruits in CaCl2 at 2% and 4% decreased blue mold incidence (%) caused by P. expansum and increased apple fruits firmness at 2 and 4 months storage periods. Also, CaCl2 treatments gave insignificant change in total soluble solid (TSS%) and in titratable acidity (TA%) of apple fruits. Gamma irradiation doses above 1 kGy significantly decreased firmness of apple fruits with the decrement being higher at higher doses.

A new technique was introduced in this study to utilize the prompt gamma rays, that generated from the fission process, in gamma irradiation experiments. The method de- pends on utilizing the difference of the attenuation effect of water on neutrons from that of gamma rays
The core of 22 MW power is submerged in the water of open pool type reactor and the theoretical and experimental studies have illustrated that the influence of water in attenuating the prompt neutrons is higher than the prompt gamma rays.
Based on this phenomena, the dose rate distributions for the prompt neutrons and the prompt gamma rays were studied in the water volume that surrounding the core during reactor operation. Then, the proper position, that achieves the considerable gamma dose rate as well as the minimum neutron dose rate, could be determined. An irradiation device was developed to contain the samples during the gamma irradiation process. The irradiation device would be located in the proper position that was chosen depending on the previous conditions. MAVRIC code was used to determine the dose rate distributions in the water surrounding the reactor core.

Cellular stress and DNA damage up-regulate and activate p53, fundamental for cell cycle control, senescence, DNA repair and apoptosis. The specific mechanism(s) that determine whether p53-dependent cell cycle arrest or p53-dependent apoptosis prevails in response to specific DNA damage are poorly understood. In this study, we investigated two types of DNA damage, chromium treatment and gamma irradiation (IR) that induced similar levels of p53, but that mediated two distinct p53-dependent cell fates. Chromium exposure induced a robust DNA-dependent protein kinase (DNA-PK)-mediated apoptotic response that was accompanied by the rapid loss of the cyclin-dependent kinase inhibitor 1A (p21) protein, whereas IR treatment-induced cell cycle arrests that was supported by the rapid induction of p21. Inhibition of DNA-PK effectively blocked chromium-, but not IR-induced p53 stabilization and activation. In contrast, inhibition of ATM and ATR by caffeine had the inverse effect of blocking IR-, but not chromium-induced p53 stabilization and activation. Chromium exposure ablated p21 transcription but PUMA and Bax transcription was significantly enhanced compared to non-damaged cells. In contrast, IR treatment triggered significant p21 mRNA synthesis in addition to PUMA and Bax mRNA production. While chromium treatment enhanced the binding of p53 and RNA polymerase II (RNA Pol II) to both the p21 and PUMA promoters, RNA Pol II elongation was only observed along the PUMA gene and not the p21 gene. In contrast, following IR treatment, RNA Pol II elongation was observed on both p21 and PUMA. Chromium-induced apoptosis therefore involves DNA-PK-mediated p53 activation followed by preferential transcription of pro-apoptotic PUMA over anti-apoptotic p21 genes.

Consumers increasingly demand convenience foods of the highest quality in terms of natural flavor and taste, and which are free from additives and preservatives. This demand has triggered the need for the development of a number of nonthermal approaches to food processing, of which high-pressure technology has proven to be very valuable. A number of recent publications have demonstrated novel and diverse uses of this technology. Its novel features, which include destruction of microorganisms at room temperature or lower, have made the technology commercially attractive. Enzymes and even spore forming bacteria can be inactivated by the application of pressure-thermal combinations, This review aims to identify the opportunities and challenges associated with this technology. In addition to discussing the effects of high pressure on food components, this review covers the combined effects of high pressure processing with: gamma irradiation, alternating current, ultrasound, and carbon dioxide or anti-microbial treatment. Further, the applications of this technology in various sectors—fruits and vegetables, dairy, and meat processing—have been dealt with extensively. The integration of high-pressure with other matured processing operations such as blanching, dehydration, osmotic dehydration, rehydration, frying, freezing / thawing and solid-liquid extraction has been shown to open up new processing options. The key challenges identified include: heat transfer problems and resulting non-uniformity in processing, obtaining reliable and reproducible data for process validation, lack of detailed knowledge about the interaction between high pressure, and a number of food constituents, packaging and statutory issues.

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.