60Co y-ray

Solution in D2S04,60Co y-ray source, 77 K. d Reference 33 electrochemical oxidation in CH2C12, 268 K. 

First-derivative X-band e.s.r. spectra for dilute solutions of methylcobaloxime after exposure to 60Co y-rays at 77 K ... 

From ref. 79 for fast electrons generated by 60Co y-rays. h From ref. 80 for fast electrons generated by °Co y-rays. 

Ionizing radiation. Further studies on the effects of ionizing radiation such as 60Co y-ray radiation and ion beams on polysilanes have been reported.295 304-306 Both positive and negative resist properties can be shown, depending on the side-chain type, branch density, and the presence or absence of radical initiators. 

In the presence of alcohols, photoreduction occurs more easily. Ketones like acetone can act as a sensitizer in this case (9). Surfactants can be used as protective colloids instead of polymers (10). Irradiation with 60Co y-rays is more effective for the reduction of metal ions (11). 

TABLE 3. Yields of oxidized nucleosides0 in the DNA of human monocytes THP1 upon exposure to 60Co y-rays and 120+6 heavy ions ... 

Co y-rays cis-2-Butene trans-2-butene ambient 28... 

The monomer 1 was polymerized by heating the crystals in a vacuum vessel below the melting point or by y-ray or UV irradiation of the crystals at room temperature. 60Co y-ray irradiation with a dose rate of 0.1 Mrad h 1 or a high-pressure mercury lamp (200 W) without filter was used as the radiation sources for the polymerization the conversion ratio was determined by extraction of residual monomer with ethanol. A comparison of the polymerization rates indicates that 60C y-ray irradiation is much more efficient than UV irradiation in inducing polymerization. 

Table 2.1. Radiation-chemical yields (G values units 10-7 mol J-1) of water radicals, ions and molecular products at a scavenger capacity of ca. 2 x 10s s-1 under the conditions of sparsely ionizing radiation (60Co-y-rays, high-energy electrons) in the presence of different saturating gases (von Sonntag 1987)...

Cyclic poly(methyl acrylate) with controlled ring size and its narrow distribution was synthesized by the 60Co y -ray-induced polymerization of methyl acrylate at - 30 °C in the presence of cyclic initiator without specific purification procedure as depicted in Fig. 5 [38]. The key point for synthe-... 

Organomercury radicals have been obtained from the 60Co y-ray irradiation of alkylmercuric halides and dimethylmercury at 77 K.171 For example, irradiation of... 

Similarly Abou Zeid and co-workers made a detailed study on LDPE film, irradiated with different types of radiation such as 60Co y-rays, thermal and fast neutrons, and electron beam irradiation [19]. The structural changes of PE films with thickness varying from 8 to 24 pm, were characterised by FT-IR spectroscopy. The characteristic FT-IR absorption bands of unirradiated, y-irradiated and reactor irradiated LDPE film are presented in Table 5.1. 

The chlorination of methylchlorosilanes is realised by free chlorine in the liquid or gaseous phase. The reaction takes place by the radical chain mechanism its initiators (substances capable of generating free radicals) can be peroxides (benzoyl, kumyl, etc.), the dinitrile of 2,2 -azobis(isobutyric) acid, fluorine, 60Co y-rays, as well as UV rays. 

Butyl chloride (BC) + Cl2 On being cooled to 77 K, a solution of Cl2 in BC (mole ratio 1 3) completely vitrifies (Tg 100 K). The irradiation of the system by 60Co y rays leads to the accumulation of stabilized active centers. The chain chlorination reaction, not observed during radiolysis, is initiated only on heating up the irradiated system, starting from the devitrification region. The heat of reaction is 138 + 12kJ/mole.27... 

The color of the burk crystals of monomer 1 changed to dark blue from light yellow after exposure to UV with a low-pressure mercury lamp (4 W) or 60Co y-ray irradiation. 

The monomer sample (ca. 1.5 mg) was sealed in a Pyrex tube (inside diameter 10 mm) in a vacuum or nitrogen atmosphere and irradiated with 60Co y rays (1.0 to 3.0 Mrad) in liquid N2 at -196 °C. The y-ray irradiation was carried out at the Japan Atomic Energy Institute at Takasaki. Solid-state postpolymerization was carried out at various temperatures (30, 25, 20, 10, 5, 0, -10, -20, and -83.6°C). The samples, polymerized for various time periods (0.5, 1, 2, 3, 6, 12, and 24 h), were dissolved in 10 ml of THF, and then the solutions were poured into 100 ml of cold acetone to separate polymer and monomer. The precipitate of the polymer was isolated on a glass filter, and the conversions were determined from the weights of polymer obtained after drying under vacuum at room temperature. 

Radiolysis of 1,2,4,5-tetrazines with 60Co y-rays at 77 K affords radical cations. All but the A,Af,./V, 7V -tetramethyl-l,2,4,5-tetrazine-3,6-diamine form rr-cations with the SOMO confined to the four ring nitrogen atoms (cf. Introduction).451,452... 

The first six samples were irradiated at 77°K with Linac electron beams for 50 s (6.5 Mrad). The remaining four samples were irradiated at 77 K with 60Co y rays (10 MR). 

Samples were irradiated at the Nuclear Center of Mol with 60Co y-rays. The dose rate was about 0.5 X 106 rads per hour, and the absorbed doses ranged from 106 to 12 X 10° rads. During irradiation, the samples were maintained in a Dewar flask containing liquid nitrogen. After irradiation, the temperature of the samples was raised to ambient temperature. 

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