Nuclear event

Throughout the studies discussed in this review there persist a number of questions of so fundamental a nature as to preclude much further progress in the field before additional insight is available. These involve areas in which decisive experiments have not yet been done, and in which such experiments appear to be either very difficult or totally impossible. These questions arise What is the nature of the starting species What effects result from reactions extraneous to the radiochemical phenomenon— adsorption, exchange, etc. At what stage following the nuclear event do the observed chemical reactions occur ... 

Another approach to the same problem involves secondary reactions of simpler building blocks such as, in the cases mentioned, -C5H4Mn(CO)3, Ru(CO)4, Fe(CO)4, and -FeCp(CO)2. In any event, one is left with the probability that at least some part of the molecule remained intact after the nuclear event, in order to account for the high yields. 

Hirose Y, Manley JL RNA polymerase II and the integration of nuclear events. Genes Dev 2000 l4 l4l5. 

When a nuclear event takes place, some rest mass is converted to extra mass of the product particles because of their high speed or to the mass of photons of light. While the total mass is conserved in the process, some rest mass (that is, some matter) is converted to energy. 

The sensitivity to ionizing radiation is maximal in those cells able to activate a co-ordinate program of cell death (apoptosis) primed by the radiation-induced oxidative stress. Albeit apoptosis is a nuclear event and radiation-induced DNA damage is probably the most relevant mechanism of initiation of apoptosis, the control of the execution phase (and sometime also the initiation) takes place at the mitochondrial level. Radioresistance occurs... 

Chromatin organization and its relation to function in the intact cell have become part of a broader area of investigation, the organization of the cell nucleus itself. The suceess of modern molecular biology, which has focussed on the characterization of cis-elements in the DNA that affect nuclear events such as... 

As the nuclear age progresses, man will be continually exposed to radiation from the radionuclides that are produced in the nuclear events and eventually localize in him. Accordingly, one of the most critical questions is that of assessing the effects upon man of low doses of radiation delivered at low rates or moderate doses delivered at low rates. It is well-known that exposure to 25 to 50 rads may cause biological harm. But what about lower doses Is all radiation harmful Should the extrapolation to a zero-rad dose be linear or curvilinear These questions are the subject for active experimentation in this Laboratory and in others. If the correct extrapolation is linear, it will be crucial to measure accurately the amount of radiation to which a person has been exposed. Such data on gamma-emitting radionuclides can be obtained with a system of the resolution and sensitivity we have described. 

Figure 1. Correlation of the ratio 140Ba/"Mo with the ratio 156Eu/"Mo in a set of airborne-debris samples from a nuclear event. 156Eu has only refractory species for precursors the mass-99 chain exhibits volatile behavior, perhaps owing to the volatility of MoOs. The strong negative correlation indicates that 140Ba has at least some volatile precursors.

Table I. Data for 27 Species Analyzed in 42 Samples Collected from a Nuclear Event...

Results from a second nuclear event were also analyzed by this technique. Data were obtained from radiochemical analyses for 12 elements on a set of 25 samples. Since the data were not analyzed completely for errors, an estimate of 10% was used for the standard deviation of each measurement. 

Storm of Nov. 15-17, 1966. The fission product ratio data by nuclear event for this storm are given in Table VII. The storm occurred 18 days after the reported Chinese fourth nuclear weapon test of about 20 lalotons on Oct. 28, 1966 and 190 days after the Chinese third nuclear explosion of about 200 kilotons on May 9, 1966. Also listed is the series of tests conducted by the French in the Southern Hemisphere (near Tahiti) in the time period between these two Chinese tests. A further possible source of fission products was the vented U.S.S.R. underground nuclear explosion of Oct. 27, 1966 (14). The extent of venting is not reported, and contributions to the storm deposition, if any, would appear as part of the fission products from the China-3 explosion. However, the venting process may result in significant fractionation of the fission products. 

Table VII. Fission Product Ratio Data by Nuclear Event...

If the free-atom recoil energy is much greater than the characteristic energy for phonon excitation ha>h where cor is the associated lattice vibration frequency, then phonon creation represents another mode of energy loss, which destroys resonance (29, 30, 32). For R° less than or of the order of tuo, a significant fraction of the nuclear events (emission and absorption)... 

When using an HDCC accelerator, the required electric potential for having the same nuclear events is dramatically reduced. Note that for the maximum reaction rates for the D-D nuclear events, the maximum occurs at about 272 Volts (lower x-axis label). Some of the desired nuclear reactions to stabilize (transmute) specific highly radioactive species into stable elements will, of course, require that the combined HDCC be accelerated using potentials up to 70 keV. 

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