Stable Isotope Abundance and Fractionation in Human Diseases

The natural abundance of heavy stable isotopes (13C, 15N, 18O, etc.) is now of considerable importance in many research fields, including human physiology. In fact, it varies between tissues and metabolites due to isotope effects in biological processes, that is, isotope discriminations between heavy and light isotopic forms during enzyme or transporter activity. The metabolic deregulation associated with many diseases leads to alterations in metabolic fluxes, resulting in changes in isotope abundance that can be identified easily with current isotope ratio technologies. In this review, we summarize the current knowledge on changes in natural isotope composition in samples (including various tissues, hair, plasma, saliva) found in patients compared to controls, caused by human diseases. We discuss the metabolic origin of such isotope fractionations and highlight the potential of using isotopes at natural abundance for medical diagnosis and/or prognostic.

Peculiarities of Neutron-Transmutation Phosphorous Doping of SiC Enriched with 30Si Isotope: Electron Paramagnetic Resonance Study

High concentration of two types of P donors up to 1017 cm-3 in SiC enriched with 30Si after neutron transmutation doping (NTD) has been achieved. It was established that annealing at sufficiently low temperature of 1300oC, that is 500-600°C lower compared with annealing of NTD SiC with natural isotope composition, gives rise to the EPR signal of shallow P donors, labeled sPc1, sPc2 and sPh. The correlated changes of the EPR spectra of the three sP centres in all the experiments and the qualitative similarities with spectra of shallow N donors prove that these centres have shallow donor levels and a similar electronic structure and belong to different lattice sites. The annealing at 1700°C results in a transformation of one type of P donors (sPc1, sPc2 and sPh) into another type having low temperature EPR spectra labeled dP.

Single Pulse Carbon-13 Enrichment of CF3 Under IR MPD in A Short Gas Dynamic Flow

An experimental approach is described for obtaining highly enriched residual gas under IR multiphoton dissociation (MPD) of molecules in one cycle of irradiation. The approach is based on utilization of a pulsed molecular flow of small length (Δxfl≤1cm). The use of a short flow length leads to high values of the dissociation yield of molecules (β≃1) in the whole volume of the flow. Owing to this, high enrichment of the residual gas is achieved in one cycle of irradiation. The isotopically-selective dissociation of CF3I+ in the pulsed gasdynamic flow of a small length was studied. About 400-fold enrichment of the 13C isotope in the residual gas was obtained following irradiation of a molecular flow of CF3I of natural isotope composition by a single laser pulse. The selectivity of dissociation was measured to be α≥10

Atom-gJ -Faktoren und Lebensdauern der z3 F-Terme im Titan I-Spektrum / Atomic gJ-Values and, Lifetimes of the z 3F-States in the Titanium I-Spectrum

Stimulated by a complete theoretical investigation of the odd configurations in the Titanium Ispectrum the optical double resonance method has been applied to measure the atomic gJ-values and lifetimes of the excited 3d2 4s 4p z 3F2,3,4-states. Using a Titanium atomic beam in natural isotope composition the following values were deduced from the position and the width of the radiofrequency transition signals:.The experimental results shall be discussed with respect to other experimental and theoretical values.