Neutron intensities

It has been estimated that using available neutron intensities such as 10 neutrons/(cm -s) concentrations of B from 10—30 lg/g of tumor with a tumor cell to normal cell selectivity of at least five are necessary for BNCT to be practical. Hence the challenge of BNCT ties in the development of practical means for the selective deUvery of approximately 10 B atoms to each tumor cell for effective therapy using short neutron irradiation times. Derivatives of B-enriched /oj o-borane anions and carboranes appear to be especially suitable for BNCT because of their high concentration of B and favorable hydrolytic stabiUties under physiological conditions. 

ISIS is only one pulsed source available for the study of liquids. Both the USA and Japan have facilities similar to SANDALS and GEM for studying liquids, but with slightly lower neutron intensity in the forms of the IPNS (Intense Pulsed Neutron Source) at the Argonne National Eab. on the instrument GEAD, and the KEK Neutron Scattering Eacility (KENS) on the instrument ELit II, respectively. 

The fractional loss in energy when a neutron collides with an atom is greatest for the H atom. Thus, by passing a beam of fast neutrons thru a series of samples, of the same material, but with varying moisture contents, a relationship is observed between moisture content and measured thermal neutron intensity. Using a small. radioisotope fast neutron source and a lithium iodide thermal neutron detector, this neutron... 

P21212i Z = 4 D = 1.663 R = 0.024 for 1,863 neutron intensities at 123 K. This is a neutron-diffraction, low-temperature refinement of a partially deuterated molecule. The undeuterated molecule had previously been studied by neutron diffraction at room temperature.10 The experiment was performed in order to seek evidence of favored replacement of hydrogen by deuterium at the anomeric hydroxyl group, but no evidence therefor was observed. 

P212121 Z = 4 Dn = 1.540 R = 0.032 for 1,051 neutron intensities at 123 K. This was an experiment similar to that of the partially deuterated / -L-arabinopyranose already described. The results here were also negative. The room-temperature, neutron-diffraction structure of the un-deuterated compound had been determined previously.11... 

PI Z = 1 Dn = 1.475 R = 0.05 for 961 neutron intensities. This is a neutron-diffraction refinement of a structure previously determined by X-ray diffraction.56 All of the hydroxyl groups are involved in inter-molecular hydrogen-bonds which form infinite chains, with H O distances ranging from 175.5 to 200.2 pm, and O-H O angles... 

Figure 12. Simulation of the temperature dependence of the neutron intensities of the first and third harmonics of the incommensurate satellite reflection of copper metaborate at zero magnetic field.

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