Irradiation external

Edwards et al. (1980) used a Cm-242 source to irradiate externally a thin film of blood. The energy of 4 9 MeV of the alpha particles were almost entirely absorbed by the blood. The dicentrics yield was linear from 0.11 to 4 2 Gy. From this resulted a RBE of 17.9 with respect to Co-60 gamma rays. It was, however, only 6.0 at the initial slope. To explain this RBE, which was low compared to that expected from neutron experiments, a model is presented taking into account cell killing and mitotic delay. 

When the entire body or parts of the body are irradiated externally, individual tissues and organs receive different absorbed doses. In order to relate the absorbed doses in tissue from non uniform irradiation to radiation detriment in humans, a quantity is required which reflects the relative effects of different types of radiation and the relative radiosensitivity of the irradiated organs and tissues. 

Source of exposure Cloud Passage Inhalation Activity deposed Internal irradiation External irradiation Total... 

Powdered crystals of 1 a (50 mg, 0.29 mmol) sandwiched between two cover glasses and placed in a polyethylene bag, were irradiated externally for 20 h with a 400 W high-pressure mercury lamp in an ice-water bath (ca. 0 °C) through a Pyrex filter. Conversion of 1 a to the photodimer 3 a was quantitative, which was confirmed from the H NMR spectrum of the irradiated crystals. They showed the exact spectrum corresponding to 3 a without purification and even traces of la and the rearrangement product 2a could not be detected. In a similar manner, 3c and 3d were prepared in quantitative yield with complete conversion from lc and Id, respectively. 

Irradiations of solid samples are carried out in various manners, depending on the researcher [1], For example, in the author s group, solid samples are usually ground into powders and are irradiated externally in a specially designed apparatus (Fig. 2) [1],... 

Papillon 1990 Rectal cancer T1 2 Rectal cancer T2 3 Intracavitary irradiation External beam plus intracavitary radiotherapy Crude local failure rate 5%, pelvic lymph node metastases 4% 5-Year cancer-specific survival 84%... 

The ionising radiations encountered in industry are principally a, p, y and X-rays, bremsstrahlung and neutrons. Persons can be irradiated by sources outside the body (external irradiation) or from radionuclides deposited within the body (internal irradiation). External irradiation is of interest when the radiation is sufficiently penetrating to reach the basal layer of the epidermis (i.e. the living cells of the skin). Internal irradiation arises following the intake of radioactive material by ingestion, by inhalation or by absorption through the skin or open wounds. 

General experimental procedure was as follows. A solution of 1 (10 mM) in CH2CI2 (10 ml) with KCN (30 mM) and PEG (1 M) [ 200 (2 g) to 1000 (3 g)] or 15-crown-5 was Irradiated externally with a high-pressure mercury lamp (Eikosha PlH-300 300W) through a water-cooled quartz or Pyrex cell. Experiments were carried out in the presence or absence of 2 (15 mol. equiv.). The irradiated solution was analysed by GLC after washed with a certain amount of water and the results are given in the Table 1. 

The concentration of Mn in steel can be determined by a neutron activation analysis using the method of external standards. A 1.000-g sample of an unknown steel sample and a 0.950-g sample of a standard steel known to contain 0.463% w/w Mn, are irradiated with neutrons in a nuclear reactor for 10 h. After a 40-min cooling period, the activities for gamma-ray emission were found to be 2542 cpm (counts per minute) for the unknown and 1984 cpm for the standard. What is the %w/w Mn in the unknown steel sample ... 

External Control. The use of external control to govern the release of dmgs from dehvery systems has largely been experimental. A number of mechanisms have been explored, and include external sources such as electrical currents, magnetism, ultrasound, temperature changes, and irradiation. 

Brandyberry, M. D. and H. E. Wingo, 1990, External Events Analysis for the Savannah River Site K Reactor, ANS Topical Meeting, The Safety, Status and Future of Non Commercial Reactors and Irradiation Facilities, Boise ID, Sept. 31 - October 4, 1990... 

A role is also played by the temperature and frequency dependence of the photocurrent, the variable surface sensitivity at various parts of the cathode and the vector effect of polarized radiation [40]. All the detectors discussed below are electronic components whose electrical properties vary on irradiation. The effects depend on external (photocells, photomultipliers) or internal photo effects (photoelements, photodiodes). 

Plutonium has a much shorter half-life than uranium (24.000 years for Pu-239 6,500 years for Pu-240). Plutonium is most toxic if it is inhaled. The radioactive decay that plutonium undergoes (alpha decay) is of little external consequence, since the alpha particles are blocked by human skin and travel only a few inches. If inhaled, however, the soft tissue of the lungs will suffer an internal dose of radiation. Particles may also enter the blood stream and irradiate other parts of the body. The safest way to handle plutonium is in its plutonium dioxide (PuOj) form because PuOj is virtually insoluble inside the human body, gi eatly reducing the risk of internal contamination. 

Various types of intermediate behaviour embodying features of more than one of these effects can be visualized. In addition to the considerations (i)—(iii) above, the interface may behave as a source or sink for the creation and/or annihilation of imperfections such as lattice defects and electrons, which can be important participants in the overall change (for clarity, such effects have not been included in Fig. 8). The decomposition characteristics of many solids are influenced by externally supplied energy such as irradiation, cold working, etc. 

The nature of the first type of thermal reactions is as yet only speculative. The two obvious possibilities seem to be (1) reaction of an incomplete molecule (radical) with an unbound nearby ligand, made available by recoil fragmentation, radiolysis, chemical dissociation, or the presence of an external atmosphere and (2) reaction of the moiety with a nearby molecule to abstract a ligand. The first type with an external source of CO has been clearly demonstrated for the case of the Group VI carbonyls which, when heated in an atmosphere of CO (up to 100 atm pressure) showed a marked increase in yield. A much smaller enhancement of yield in vacuo was attributed (99) to radiolytic dissociation, because of the influence of irradiation at various y-fluxes. The alternative possibility—that of equilibrium dissociation of Cr(CO)6 in the solid state—has not been investigated. 

These devices have special function, namely to irradiate the liquid phase with light to induce a photoreaction or photoinduced reaction. Hence the characteristic feature is a transparent section within the reactor, often in the visible or commonly in the UV spectral region. The devices may have integrated photo energy sources or on-line analysis units. Otherwise, this is performed by external instruments. 

This definition of electrochemistry disregards systems in which nonequilibrium charged species are produced by external action in insulators for example, by electric discharge in the gas phase (electrochemistry of gases) or upon irradiation of liquid and sohd dielectrics (radiation chemistry). At the same time, electrochemistry deals with certain problems often associated with other fields of science, such as the structure and properties of sohd electrolytes and the kinetics of ioific reactions in solutions. 

Despite the potential impact of novel photosynthetic routes based on these developments, the most ambitious application remains in the conversion of solar energy into electricity. Dvorak et al. showed that photocurrent as well as photopotential response can be developed across liquid-liquid junctions during photoinduced ET reactions [157,158]. The first analysis of the output power of a porphyrin-sensitized water-DCE interface has been recently reported [87]. Characteristic photocurrent-photovoltage curves for this junction connected in series to an external load are displayed in Fig. 22. It should be mentioned that negligible photoresponses are observed when only the platinum counterelectrodes are illuminated. Considering irradiation AM 1, solar energy conversions from 0.01 to 0.1% have been estimated, with fill factors around 0.4. The low conversion... 

Some minerals, on being irradiated or acted upon by other external factors, can radiate light the ability to do so is called luminescence. In the case of minerals the natural colour... 

Nechev H, Sulovski P, Shopova Y, et al. 1982. Particularities in the metabolism of americium-241 after intratracheal application and in combination with external irradiation. Sci Works Higher Med Inst-Pleven 4(l) 37-43. 

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