Irradiation techniques

Table III presents the relative rates of H2 transfer reactions from cyclo-C5H10 and C5H12 to propylene, ethylene, acetylene, and cyclopropane. These values were obtained by irradiating pentane-CwDm-02 mixtures with gamma rays, or with the argon resonance lines at 1048-1067 A. The results obtained by the two irradiation techniques are in fair agreement.

Radiation methods, pulse radiolysis (22, 23), and 7 irradiation techniques (24) prove to be elegant and versatile methods not only for generation of unstable radicals, but also for the study of their physical properties and reactivity. 

A related development that had profound impact on heterogeneous reactions is the use of microwave (MW) irradiation techniques for the acceleration of organic reactions. Since the appearance of initial reports on the application of microwaves for chemical synthesis in polar solvents [11], the approach has blossomed into a useful... 

Conformal Radiation Therapy Photon Irradiation Techniques... 

Powerful irradiation techniques are now available or under development for photons intensity-modulated radiation therapy (IMRT), tomotherapy, gamma knife, cyberknife, radiosurgery, etc. These techniques make it possible to irradiate any volume of any complex shape with minimum irradiation of critical normal structures. 

A uniform-irradiation technique is commonly used for ion beam applications in materials science and biotechnology, and for biomedical application such as cancer therapy. Uniformity of the irradiated-particle density distribution is essential to bring about the same... 

The peroxidation procedure, which is the least often used of all the irradiation techniques, involves irradiation of the substrate in the presence of air or oxygen. This produces diperoxides and hydroperoxides on the surface of fhe subsfrafe, which are stable, and the substrate can be stored until the combination with a monomer is possible. Monomer, with or without solvent, is then reacted with the activated peroxy trunk polymer in air or under vacuum at elevated temperatures to form the graft copolymer. The advantage of this method is the relatively long shelf life of fhe infermediate peroxy trunk polymers before the final grafting step. ... 

The three principal irradiation techniques used to produce graft copolymers by irradiation are ... 

From the graphic representations of the results it is obvious that the preparation method has a pronounced influence on the form of the molecular weight distribution of the grafted side chains. The distribution of the sample prepared by the mutual irradiation technique is very broad with the emphasis on the low molecular weight side. The calculated values of the molecular weight yielded a ratio as high as MJMn = 9.2. 

The differential form of the molecular weight distribution of the sample prepared by the pre-irradiation technique shows distinctly that the overall distribution can be described by the superposition of two distributions. The one distribution, including the low molecular weight part, is again very broad with M,JMn = 15.0. The second distribution, which comprises about 80% of the total weight, is quite narrow with MJMn = 1.09. 

In conclusion, the decomposition of seawater into H2 and 02 is expected to be accomplished using the sonophotocatalytic reaction. Furthermore, H2 and 02 were obtained separately by the alternating irradiation technique, as described in section 12.2.1G. 

Sharifi, A., Mojtahedi, M.M. and Saidi, M.R., Microwave irradiation techniques for the Cannizzaro reaction, Tetrahedron Lett., 1999,40, 1179-1180. 

As well as qualitative identification of irradiation, doses received by bones have also been estimated in three of the collaborative trials using the re-irradiation technique (Desrosiers etal., 1990 Raffi etal., 1992 Scotter etal., 1990). Although the differences between the applied and estimated doses were sometimes quite large and there were differences between laboratories, it was possible to distinguish between samples given low, medium and high doses of irradiation. 

Pulse Irradiation Techniques for Ordnance Items and Burning Miniature Rocket Motors , Ibid, paper 3.1, pp 401-50 (1975) 240) R. Finnet... 

U. Relative sensitivity factors for atomic ions out of a given matrix vary by only one, in extreme cases by about two, orders of magnitude at least for the high irradiance techniques (J ). This holds even for ions f only+one polarity, i.e. under suitable conditions ions such as F or Cl are detected in positive ion spectra. This contrasts favourably with e.g. SIMS where sensitivity factors vary by several orders of magnitude. 

Radiation grafting [83, 84, 85, 86, 87, 88, 89] is a very versatile and widely used technique by which surface properties of almost all polymers can be tailored through the choice of different functional monomers. It covers potential applications of industrial interest and particularly for achieving desired chemical and physical properties of polymeric materials. In this method, the most commonly used radiation sources are high-energy electrons, y-radiation, X-rays, U.V.-Vis radiation and, more recently, pulsed laser [90], infrared [91], microwave [92] and ultrasonic radiation [93]. Grafting is performed either by pre-irradiation or simultaneous irradiation techniques [94, 95]. In the former technique, free radicals are trapped in the inert atmosphere in the polymer matrix and later on the monomer is introduced into... 

Tanizaki, Y., Maeno, T., Nakamura, M. and Yamazaki, M. (1996) Use of an ultrafiltration and gamma-ray irradiation technique for studying the speciation of trace elements in river waters./. Environ. Sci. Health, A31, 913-940. 

Microwave irradiation considerably improved the reaction speed and yields of 2,4-disubstituted quinolines in a MCR of aldehydes, anilines and alkynes [111]. The cyclocondensation was catalyzed by montmorillonite clay doped with copper bromide and was completed within 3-5 minutes (pulsed irradiation technique—1 min with 20 s off interval), when performed in a household microwave oven. Oil-bath heating at 80 °C for 3-6 hours was necessary to achieve comparable yields of quinolines (71-90%) (Scheme 42). 

Grafting can also be achieved by means of high energy irradiation techniques. However, in many cases, side reactions such as cross-linking, fragmentation, and homopolymerization may also occur... 

---