Utilization of a multimembrane inlet and a cyclic sudden sampling introduction mode in membrane inlet mass spectrometry.

Sudden sampling introduction into a membrane inlet mass spectrometer (MIMS) considerably improves the selectivity of the membrane inlet and is therefore applicable even for compounds with low permeabilities through a silicone membrane. In this study the basics of cyclic non-steady-state sudden increase sample injection were studied using a three-membrane inlet and a portable sector double-focusing mass spectrometer. The operational parameters of the inlet system providing the most efficient enrichment of volatile organic compounds (VOCs) in air were defined. Simulation of the diffusion process following sudden sample introduction into the three-membrane inlet was also carried out. Experimental testing of the three-membrane inlet system with the cyclic sudden sample injection mode for benzene, toluene, styrene, and xylene in air was performed. The simulation and the experimental results demonstrated that, when this mode is used, the VOCs/nitrogen relative enrichment factor of samples introduced into the mass spectrometer equipped with a three-membrane inlet is increased by a factor of approximately 10(5) compared with a direct introduction method. This effect may be used to decrease detection limits of compounds obtained with mass spectrometry to decrease matrix flow through the inlet at the same detection limits.

[Clinical differences in senile dementia of the Alzheimer's type and in multi-infarct dementia]. / O klinicheskikh razlichiiakh senil'noi dementsii al'tsgeimerovskogo tipa i mul'tiinfarktnoi dementsii.

Impoverished grasp of the abstract and the essential notions (IG) and delusion of stealing (DS) were investigated in Alzheimer's senile dementia (ASD) and multi-infarction dementia (MID). IG severity was evaluated in impairment of memory and disorientation in 67 ASD and 70 MID patients. DS was studied in 24 ASD and 56 MID patients. It was found that in similar impairment of memory and disorientation, IG was more distinct in ASD, especially at early stages of the disease. DS occurred more frequently in ASD than in MID. In MID the IG and DS symptoms were more common and severe in patients over 80. No age-specific relations were recorded in ASD. The findings suggest involvement of cerebral senile-atrophic processes in IG and DS genesis in MID patients.

[Results of a pharmacological and toxicological study of pentagastrin]. / Rezul'taty farmakologicheskogo i toksikologicheskogo izucheniia pentagastrina

Pentagastrin is found to be a highly active stimulator of the gastric glands secretion. With its intraperitoneal introduction to albino rats the drug displays a low acute toxicity. On its re-administration to rabbits and albino rats in doses significantly exceeding the diagnostic ones no substantial influence on the growth of the animals, hematological, enzymological, proteinological blood indices and morphological condition of internal organs was noted.