Some problems concerning the use of automated radiochemical separation systems in destructive neutron activation analysis

The present state of a long term program is reviewed. It was started to elaborate a remote controlled automated radiochemical processing system for the neutron activation analysis of biological materials. The system is based on wet ashing of the sample, followed by reactive desorption of some volatile components. The distillation residue is passed through a series of columns filled with selective ion screening materials to remove the matrix activity. The solution is thus “stripped” from the interfering radioions, and it is processed to single-elements through group separations using ion-exchange chromatographic techniques. Some special problems concerning this system are treated. (a) General aspects of the construction of a (semi)automated radiochemical processing system are discussed; (b) Comparison is made between various technical realizations of the same basic concept; (c) Some problems concerning the “reconstruction” of an already published processing system are outlined.     

FLUORESCENCE SPECTRA IN LUNG WITH PORPHYRIN INJECTION

The fluorescence emission spectra from human bronchial mucosa and tumors, before and after injection of dihematoporphyrin ether/ester, have been measured with an optical multichannel analyzer from 500 to 750 nm. Fluorescence was excited with a violet krypton ion laser (average wavelength 410 nm). The autofluorescence spectra decrease monotonically with increasing wavelength except for a small broad peak near 600 nm. The spectra from tumor sites, after injection of the fluorescent porphyrin, exhibit the characteristic fluorescence emission at 630 and 690 nm, added to the autofluorescence spectrum. The spectra from control or nontumor sites are similar but the magnitude of the component due to the injected porphyrin is smaller than at a tumor site. The magnitude ratio of tumor to control site fluorescence depends on concentration of the porphyrin, tumor thickness, and time after injection. Autofluorescence degrades contrast and thus makes very thin tumors difficult to image. Subtraction of the autofluorescence background is desirable.     

The selective chlorination of organohydridesilanes

Conclusions A convenient method of preparing organochlorohydridesilanes by selective chlorination of organohydridesilanes with stannic chloride was proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2114–2117, September, 1967.     

Production of the oxyfluorides of holmium,erbium, and ytterbium and study of their crystal-chemical properties

Journal of Structural Chemistry -     

DSC study of charge-transfer complexes of polynuclear aromatic hydrocarbons with nitroaromatic acceptors

Charge-transfer, crystalline complexes of 1,3,5-trinitrobenzene (TNB), 2,4,7- trinitro-9-fluorenone (TNF). and 2,4,5,7-tetranitro-9-fluorenone (TENF) with eleven polynuclear aromatic hydrocarbons were compared for thermal stability, ΔH and ΔS of melting. Factors possibly influencing the above parameters are discussed.Melting does not induce separation of the components; these complexes can be repeatedly crystallized and melted without variation of the ΔH of melting, thereby indicating high thermal stability.With a few exceptions, melting temperatures of the complexes increase in the order TNB<TNF<TENF: so do ΔH and ΔS of melting. A number of crystal transitions were observed.