Gamma irradiations

Irradiation of PH3(PD3) in low-temperature Kr or Xe matrices yielded PH2(PD2) (see also Section 1.2.1.1, p. 50) along with atomic species H(D) and P [4] see also [5]. PH4 was detected after irradiation of PH3 In an Xe matrix at 77 K [5]. Formation of PH4(PD4) was confirmed by y-irradiation of a neopentane/5% PH3(PD3) mixture [8]. Analogously, PH3F [5, 9] or PD3F molecules [5] were detected at 133 K after y-irradiation of an SFg matrix (at 77 K) which contained 1% PH3(PD3) [5] or 5% PH3 [9]. The PHJ radical cation is the major product of y-irradiation of a frozen, solid sulution of PH3 in concentrated aqueous H2SO4 [6, 7]. The formation of PH2 (PD2 and traces of PHD in concentrated D2SO4 in D2O) under the above condition was also observed [6]. 

Steady-state 7-irradiation of any explosive has not been known to initiate a detonation. The effect of such irradiation appears to result in slow decomposition with, in the case of primary explosives, a deterioration in the functional properties of the samples. 

A continued evolution of gas from lead azide after the radiation source had been removed suggested that either gas trapped in the sample during irradiation or that decomposition continued after irradiation [74]. When samples was irradiated at 71 °C and cooled, no such gasing occurred. In all cases more gas was evolved than could have resulted from heat alone. 

With detonators which included lead azide in the explosive train, the work of Warren et a [72] also revealed that long-term gamma irradiation affected the functioning in stab tests. 

Bowden and Singh [37] irradiated lead and cadmium azides with a-particles and 7-radiation at 290°C when mixed with uranium oxide without initiations occurring. 

A dose of 10 R Co gamma rays reduced the diamagnetic susceptibility of a-lead azide more than threefold [53]. Colloidal lead azide, irradiated with a Co gamma source with exposures of 2.5, 7.5, and 22.5 X lO R, had its impact sensitivity increased from 12 to 6 in. with the Picatinny impact test [57,58]. 

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The neutrons in a research reactor can be used for many types of scientific studies, including basic physics, radiological effects, fundamental biology, analysis of trace elements, material damage, and treatment of disease. Neutrons can also be dedicated to the production of nuclear weapons materials such as plutonium-239 from uranium-238 and tritium, H, from lithium-6. Alternatively, neutrons can be used to produce radioisotopes for medical diagnosis and treatment, for gamma irradiation sources, or for heat energy sources in space. 

Similar to pure polyglycoHc acid and pure polylactic acid, the 90 10 glycolide lactide copolymer is also weakened by gamma irradiation. The normal in vivo absorption time of about 70 days for fibrous material can be decreased to less than about 28 days by simple exposure to gamma radiation in excess of 50 kGy (5 Mrads) (35). 

Polydioxanone (PDS) is completely elirninated from the body upon absorption. The mechanism of polydioxanone degradation is similar to that observed for other synthetic bioabsorbable polymers. Polydioxanone degradation in vitro was affected by gamma irradiation dosage but not substantially by the presence of enzymes (39). The strength loss and absorption of braided PDS, but not monofilament PDS, implanted in infected wounds, however, was significantly greater than in noninfected wounds. 

Cittadini [60] and Corso [61] found that azo-initiated polymer liberates HCI more rapidly than peroxide-initiated material. Stromberg et al. [62] confirmed these findings and in addition found that PVC prepared by gamma irradiation was still more stable. Talamini and coworkers... 

Production Test. In a small-scale production test, tinplate containers with two commercially available enamels and two end-sealing compounds, which were selected from the results of this study, performed satisfactorily when packed with beef and ham. Beef was irradiated with 4.5-5.6 Mrad at 5, —30, and —90°C ham was irradiated with 3-4 Mrad and 6-7.5 Mrad at —30°C. For this production test, beef and ham were packaged in round tinplate containers and ham in Pullman tinplate containers, frozen and refrigerated products were shipped 1,200 miles by truck, and were gamma irradiated at various doses and temperatures. Irradiated products were shipped 1,200 miles in a non-refrigerated truck and stored at selected temperatures and humidities. The integrity of the cans was evaluated after storage for 10 days, 3 months, and 6 months. 

Korobeinikova and coworkers61 studied the extractability of petroleum sulfides (PSO) and their closest analog, tetramethylene sulfoxide (TMSO) upon gamma irradiation. The... 

Siloxane-(methyl methacrylate) networks showing high oxygen permeabilities were prepared by gamma-irradiation of tx,(o-methacryloyl terminated tetramethyl-disiloxanes and methyl methacrylate 325). Due to the utilization of very low molecular weight disiloxane modifier, no phase separation was observed in the networks produced. DSC studies showed only one Tg around 120 °C. These materials were evaluated... 

Studying in addition the effect of irradiation temperature, presence or absence of air, gamma irradiation, and thermal annealing, Grossmann found results which can be summarized as follows ... 

The effect of oxidative irradiation on mechanical properties on the foams of E-plastomers has been investigated. In this study, stress relaxation and dynamic rheological experiments are used to probe the effects of oxidative irradiation on the stmcture and final properties of these polymeric foams. Experiments conducted on irradiated E-plastomer (octene comonomer) foams of two different densities reveal significantly different behavior. Gamma irradiation of the lighter foam causes stmctural degradation due to chain scission reactions. This is manifested in faster stress-relaxation rates and lower values of elastic modulus and gel fraction in the irradiated samples. The incorporation of O2 into the polymer backbone, verified by IR analysis, conftrms the hypothesis of... 

Kamat, A. et al.. Potential application of low dose gamma irradiation to improve the microbiological safety of fresh coriander leaves. Food Control, 14, 529, 2003. 

Sandoli RL, WC Ghiorse, EL Madsen (1996) Regulation of microbial phenanthrene mineralization in sediment samples by sorbent-sorbate contact time, inocula and gamma irradiation-induced sterilization artifacts. Environ Toxicol Chem 15 1901-1907. 

Ito and Matsuda studied the y-radiolysis of 2-methyltetrahydrofuran (MTHF) solutions of diphenyl sulfone and dibenzothiophene-S,S-dioxide (DBTSD) at 77 K. They found that the radical anions of these sulfone compounds are formed and have intense absorption bands at 1030 nm and 850 nm, respectively. The blue glassy solution of y-irradiated diphenyl sulfone has absorption bands at both 1030 nm and 360 nm while the absorption spectrum of the benzenesulfonyl radical formed by UV irradiation of diphenyl sulfone solution at 77 K showed only a peak at 382 nm. Gamma-irradiated phenyl methyl sulfone solution showed an absorption band only at 385 nm. Consequently the appearance of the absorption bands in 800-1030 nm of diphenyl sulfone and DBTSD may suggest that the unpaired electron is delocalized on two phenyl rings. The same authors studied the radiolysis of MTHF solutions of disulfones (diphenyl and dihexyl disulfones). They found a blue coloring of the solution by the y-radiolysis of diphenyl disulfone and dihexyl disulfone due to absorption peaks at 695 nm and 690 nm respectively, besides smaller absorptions at 300-400 nm. Comparing these results to the previous observation, that phenyl methyl sulfone solution absorbs only at 398 nm, results in the conclusion that the absorption band at 690 nm is due to the linked two sulfone moieties. The authors found that substituents on the phenyl ring lead to shifts in the absorption maxima of the... 

Deshpande, S. N., Aguilar, A. A., Effects of roasting temperatures and gamma-irradiation on the content of chlorogenic acid, caffeic acid and soluble carbohydrates of coffee, Int. J. Appl. Radiat. Isot., 26, 656, 1975. (CA84 57527r)... 

Polyethylene and polystyrene are examples of plastics subject to environmental stress cracking. Crack resistance tests have shown that surfactants, alcohols, organic acids, vegetable and mineral oils, and ethers provide an active environment for stress cracking of polyethylene. Table 6 lists typical sterile devices and plastic materials used to fabricate them, while Tables 7-9 list the potential effects of sterilization processes on polymeric materials. The effect of gamma irradiation on elastomeric closures has been studied by the Parenteral Drug Association [15]. 

Fewer extractables Greater biocompatibility Cleaner materials Specialty laminates Gamma irradiation resistance... 

Effects of gamma irradiation on elastomeric closures. Technical Report No. 16. Parenter. Sci. Technol., 50, 1 (1992). 

Early in the program, critical components (e.g.,the turbomolecular pump) and circuit boards were tested for their ability to survive neutron and gamma irradiation rates and doses similar to those that would be received from exposure to the detonation of a tactical nuclear device. All components were powered up at the start of the gamma irradiation tests but not during the neutron irradiation tests. Circuit boards were protected by circumvention circuits that powered down critical circuits in 10 to lOOps upon detecting radiation. All components survived the nuclear radiation tests. This unusual performance was noted with positive commendations by the staff at the White Sands Missile Range, where the tests were performed. Tests of the fully integrated CBMS II system, installed in a reconnaissance vehicle, will be conducted in the future. 

Sato K, Takimoto K, Tsuda S (1978) Degradation of aqueous phenol solution by gamma irradiation. J Am Chem Soc 12(9) 1043-1046... 

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