Search Results

1 - 10 of 89 items :

  • "gamma radiation" x
Clear All

Abstract

The aim of this study is to exploit a suitable chitosan extraction method from the chitin of indigenous shrimp shells by employing different physicochemical treatments and to improve different bioactive properties of this extracted chitosan (CS) by applying gamma radiation. Chitin was prepared from shrimp shell by pretreatment (deproteination, demineralization and oxidation). Chitosan was extracted from chitin by eight different methods varying different physicochemical parameters (reagent concentration, temperature and time) and assessed with respect to the degree of deacetylation, requirement of time and reagents. The method where chitin was repeatedly treated with 121°C for 30 min with 20 M NaOH, produced the highest degree of deacetylation (DD) value (92%) as measured by potentiometric titration, with the least consumption of time and chemicals, and thus, selected as the best suitable extraction method. For further quality improvement, chitosan with highest DD value was irradiated with different doses (i.e., 5, 10, 15, 20 and 50 kGy) of gamma radiation from cobalt-60 gamma irradiator. As the radiation dose was increased, the molecular weight of the wet irradiated chitosan, as measured by the viscosimetric method, decreased from 1.16 × 105 to 1.786 × 103, 1.518 × 103, 1.134 × 103, 1.046 × 103 and 8.23 × 102 dalton, respectively. The radiation treatment of chitosan samples increased the antimicrobial activity significantly in concentration dependent manner on both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, as determined by the well-diffusion method. Four to five percent wet chitosan treated with a radiation dose range of 5.0–10.0 kGy rendered the highest antimicrobial activity with least energy and time consumption. Solubility, water binding capacity (WBC) and fat binding capacity (FBC) also improved due to irradiation of chitosan.

Abstract

During the operation of large industrial installations, a very important task is to maintain the proper technical state. In the event of an emergency, it is vital to locate the place of occurrence as soon as possible. In solving this type of problem, it often helps to apply the methods of measurement associated with ionizing radiation. One of these methods is the gamma scanning. The purpose of this type of measurement is the detection and localization of disturbance of technological processes which may result in incorrect decomposition the fl owing medium and workpiece (sediments, congestion) as well as damage to the internal constructions. A particularly: (i) preventive diagnosis - early detection of installation failure; (ii) rationalization of repairs and renovations - to determine the need to take or not to take remedial action; (iii) quick and precise installation inspections - to gain knowledge of the technical condition and technological installations; (iv) indication of worn parts and posing a threat - diagnostics of the technical condition installation; (v) forecasting the useful lifetime of equipment.

;312:293-304. doi: 10.1016/0165-1161(94)90039-6 28. Liu L, Liu Y, Ni G, Liu S. Flow cytometric scoring of micronucleated reticulocytes as a possible high-throughput radiation biodosimeter. Environ Mol Mutagen 2010;51:215-21. doi: 10.1002/em.20523 29. Li MJ, Wang WW, Chen SW, Shen Q, Min R. Radiation dose effect of DNA repair-related gene expression in mouse white blood cells. Med Sci Monit 2011;17:BR290-7. doi: 10.12659/ MSM.881976 30. Maurya DK, Devasagayam TP. Ferulic acid inhibits gamma radiation-induced DNA strand breaks and enhances the survival of mice. Cancer Biother

) test procedure. In Test method standard microcircuits . MIL-STD-883E, method 1019.4. Available from http://scipp.ucsc.edu/groups/fermi/electronics/mil-std-883.pdf . 24. Rossi, P., Ferri deCollibus, M., Florean, M., Monti, C., Mugnaini, G., Neri, C., Pillon, M., Pollastrone, F., Baccaro, S., Piegari, A., Damiani, C., & Dubus, G. (2013). IVVS actuating system compatibility test to ITER gamma radiation conditions. Fusion Eng. Des. , 88 (9/10), 2084–2087. DOI: 10.1016/j.fusengdes.2013.03.030. 25. Attix, F. H., & Roesch, W. (Eds). (1968). Radiation dosimeter. Vol. 1

in human peripheral leukocytes after a gamma radiation incident. Radiat Prot Dosimetry 2002; 98(4): 407-16. Gajski G, Garaj-Vrhovac V, Orescanin V. Cytogenetic status and oxidative DNA-damage induced by atorvastatin in human peripheral blood lymphocytes: Standard and Fpg-modified comet assay. Toxicol Appl Pharmacol 2008; 231: 85-93. Piperakis SM, Visvardis EE, Tassiou AM. Comet assay for nuclear DNA damage. Methods Enzymol 1999; 300: 184-94. Collins AR. The comet assay for DNA damage and repair: principles, applications, and limitations. Mol Biotechnol 2004

). Degradation of chlorophenols by means of advanced oxidation processes: A general review. Appl. Catal. B-Environ. , 47 (4), 219–256. DOI: 10.1016/j.apcatb.2003.09.010. 22. Taghipour, F., & Evans, G. J. (1997). Radiolytic dechlorination of chlorinated organics. Radiat. Phys. Chem ., 49 (2), 257–264. DOI: 10.1016/S0969-806X(96)00065-5. 23. He, Y., Liu, J., Lu, Y., & Wu, J. (2002). Gamma radiation treatment of pentachlorophenol, 2,4-dichlorophenol and 2-chlorophenol in water. Radiat. Phys. Chem. , 65 (4/5), 565–570. DOI: 10.1016/S0969-806X(02)00364-X. 24. Klanova, J

, L. (1978). Calculation of exposure rates from gamma sources in walls of dwelling rooms. Health Phys., 34, 459-463. 18. Risica, S., Bolzan, C., & Nuccetelli, C. (2001). Radioactivity in building materials: room model analysis and experimental methods. Sci. Total. Environ., 272, 119-126. 19. Maduar, M. F., & Hiromoto, G. (2004). Evaluation of indoor gamma radiation dose in dwellings. Radiat. Prot. Dosim., 111, 221-228. 20. Beck, H. L. (1975). The physics of environmental gamma radiation fi elds. In The natural radiation environment II. Oak Ridge: United States

solitary tract via the left nodose ganglion and a small part via the right nodose ganglion. Spinal sensory stimuli are transmitted through spinal nerves 7–13 to the thoracic spinal cord. Vagal sensory nerve cell bodies are located in the nodose ganglion (NG), and spinal sensory nerve cells are found in the dorsal root ganglion (DRG) ( 5 ). In this study, we aimed to investigate the NOS isoforms (nNOS, eNOS, and iNOS) immunohistochemically in the spinal cord and nodose ganglion of rats exposed to ionising gamma radiation of the liver. Material and Methods Experimental

Abstract

This paper is a part of a natural dye solar cell project. Conductive transparent oxide (CTO) films have been deposited onto preheated glass substrates using a spray pyrolysis technique. The optical, electrical, structural properties as well as thermal annealing and gamma radiation response were studied. The average optical energy gap of doped films for direct allowed and direct forbidden transitions were found to be 3.92 and 3.68 eV, respectively. The plasmon frequency and plasmon energy after doping were found to be 3.48 × 1014 s −1 and 0.23 eV. The negative absorbance of the doped film was observed in UV-Vis range after applying both thermal annealing and γ-dose irradiation with 22 kGy. The negative refractive index of the doped film in UV range (220 – 300 nm) is promising for optical applications. The electron mobility μe reached a maximum of 27.4 cm2 V−1 s−1 for Sb concentration of 10 %. The corresponding resistivity ρ, and sheet resistance Rs reached their minimum values of 1.1 × 10−3 Ω cm and 35 Ω sq−1, respectively. The dopant concentration has been increased from 4.13 × 1019 to 2.1 × 1020cm−3. The doped film was found to exhibit three diffraction peaks associated with (2 2 2), (2 0 0), and (2 1 1) reflection planes, of which the peak of (2 2 2) of Sb2O3 and the peak of (2 0 0) were very close.

Abstract

Smoke from gamma irradiated 1R1 Reference cigarettes was compared to smoke from the non-irradiated cigarettes. Total particulate matter, nicotine, and tar levels decreased with increasing radiation dose. Nicotine was determined by gas chromatography, using 7-methyl- quinoline as an internal standard. Yields of solvent partition fractions of the smoke condensate and of chromatographic fractions of the condensate neutrals did not indicate significant changes in smoke composition resulting from gamma irradiation of the precursor cigarette tobacco. The composition of refined polycyclic aromatic hydrocarbon (PAH) fractions of smoke from irradiated cigarettes appeared to be identical to that of standard cigarettes. The expected decrease in PAH did not occur. It was concluded that gamma irradiation of cigarettes had no major effects on smoke composition.