60Co y-ray

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

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

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 

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

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

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. 

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

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- 

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. 

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. 

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

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. 

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 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). 

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). 

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. 

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