SUBJECTS radiation damage

Not every molecular crystal can be resolved at 3A resolution, especially not ones built of aliphatic nonconjugated molecules, which have lower electron densities and are more subject to radiation damage. The final aim of obtaining a direct three-dimensional picture of the chiral molecule itself thus cannot yet be pursued. Assignment of absolute configuration by lattice imaging, however, may be achieved even at lower resolutions (129). 

DNA is subject to damage by electromagnetic radiation or reactive chemicals, many of which have been introduced into the environment as a by-product of industrial activity. Some chemicals may not be dangerous per se, but may be metabolised to products which are dangerous. There are three major classes of such chemicals07 . 

Radiation induced changes in the electronic structure of all samples were evident as changes in energy loss spectrum with increased exposure to the electron beam. The spectrum of radiation induced chromophores could thus be studied (1 ). Spectra recorded at the earliest exposure times compared favorably with optical results and are believed to contain primarily intrinsic electronic excitations (1, 2, 4). An analysis of these intrinsic spectra is the subject of the bulk of this paper. The spectra of radiation damaged polymers are described briefly after the intrinsic excitations are discussed. 

In 1969, I became Visiting Professor at the Chemistry Department of Salford University. This was at the invitation of Glyn Phillips, a great Welsh patriot who had recently moved from Cardiff to Salford to head the Chemistry Department. We collaborated for many years on projects related to radiation damage of polysaccharides, like heparin, hyaluronan and other polysaccharides. I had been interested in this subject since 1948 when I discovered the... 

When quartz or other suitable mineral detector is deposited into a matrix of minerals containing the radioactive nuclides of the U, U, and Th decay series, and the detector mineral is subject to radiation damage. If the grain had been cleared of all memory of radiation damage prior to deposition, then the extent of damage is a function of the time the detector mineral has been immersed in the radiation-producing matrix. 

Fouling-need for chemical cleaning or backflushing Organic membranes subject to radiation damage... 

Scaling diffraction data from separate crystals, or scaling observed and calculated intensities or structure amplitudes is even more fraught with problems. Consider two separate crystals whose data were collected in two separate experiments, and remember that there are frequently several crystals. First of all, the independent data set from each crystal is subject to all the factors recounted above, and it is unlikely that any two will be identically affected. The two crystals may have had different geometrical properties, different amounts of liquid around them, different rates or allowances of radiation damage, or they... 

In the first application, acoustic intensities of thousands of W/cm2 and tempera-tures in excess of 98°C are often used to coagulate cancerous tissues. This form of hyperthermia is often referred to as thermal therapy because of its extreme temperature and energy.43 Alternatively, lower ultrasound intensities (0.2 to several W/cm2) produce a mild increase in temperature (41 to 45°C), and enhance the cytotoxicity of radiation therapy and chemotherapy. The enhancing effect of ultrasound on radiation therapy has been linked to the radiosensitization effect of hyperthermia, which increases radiation damage and prevents subsequent repair.28 However, the precise mechanism for ultrasound-enhanced chemotoxicity is still the subject of debate. 

Nine explosives and propellants were subjected to a transient burst of about 1 msec duration which resulted from fission of about 10 atoms of [62]. The materials were tested with 3.6-g samples of TATB, DATE, TACOT, HNS, lead styphnate, black powder, and three composite propellants. The lead styphnate sample detonated, but since the samples were hurled 500 ft by the nuclear excursion there was some question whether this resulted from impact rather than irradiation. The melting point was lowered from 216 to 208°C and the 5-sec explosion temperature (Table XI) was lowered from 299 to 268°C. None of the other materials tested showed evidence of gross radiation damage. 

Lil(Eu). Lil(Eu) is an efficient thermal-neutron detector through the reaction jLKn, a)jH. The alpha particle and the triton, both charged particles, produce the scintillations. Lil has a density of 4.06 X 10 kg/m, decay time of about 1.1 /i,s, and emission spectrum peaking at 470 nm. Its conversion efficiency is about one-third of that for Nal. It is very hygroscopic and is subject to radiation damage as a result of exposure to neutrons. 

LUMINESCENCE OF Ge/Si QUANTUM DOTS SUBJECTED TO RADIATION DAMAGE AND HYDROGEN PASSIVATION... 

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