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Biomedical subjects

T Mineva

Publications and source records attributed to T Mineva.

11 recordsLinked to original sources
PubMed2006

Two bonding configurations of acetylene on Si(001)-(2 x 1): a combined high-resolution electron energy loss spectroscopy and density functional theory study.

Two coexisting adsorption states of molecularly adsorbed acetylene on the Si(001)-(2 x 1) surface have been identified by a combined study based on the high-resolution electron energy loss spectroscopy and density functional computations. Seven possible adsorbate-substrate structures are considered theoretically including their full vibrational analysis. Based on a significantly enhanced experimental resolution, the assignment of 15 C2H2- and C2D2-derived vibrational modes identifies a dominant di-sigma bonded molecule adsorbed on top of a single Si-Si dimer. Additionally there is clear evidence for a second minority species which is di-sigma bonded between two Si-Si dimers within the same dimer row (end-bridge geometry). The possible symmetries of the adsorbate complexes are discussed based on the specular and off-specular vibrational measurements. They suggest lower than ideal C(2v) and C(s) symmetries for on-top and end-bridge species, respectively. At low coverages the symmetry reductions might be lifted.

Journal Article↗
PubMed2005

Selectivity descriptors for the Michael addition reaction as obtained from density functional based approaches.

Density functional (DF) based numerical approaches for computing orbital and atomic reactivity indices were employed in the study of selectivity descriptors for the 1,4 Michael addition reaction. To this aim, atomic and orbital Fukui indices and atomic softnesses for 2-arylmethylene-1,4-butanolides and N,N-disubstituted phenylacetamides were computed. Further on, these local selectivity descriptors have been rationalized in terms of the Pearson's hard-soft-acid-base principle to explain the observed regioselectivity. It is shown that the methods employed for local (atomic and orbital) reactivity index computations are useful and reliable for prediction of the regioselectivity upon conjugate addition of ambident nucleophiles to 2,3-unsaturated carboxylic esters. All the results reveal similar degree of localization/hardness of the 1,4-butanolides C4 and active alpha-carbon belonging to the N,N-dimethyl-phenylacetamide, while the soft alpha-carbon in LiCH2CN reacts with the soft C2 1,4-butanolide center.

Journal Article↗
PubMed2002

On the hardness evaluation in solvent for neutral and charged systems.

The influence of water on the hardness values of a series of neutral and charged molecules has been studied in the framework of density functional theory using the polarizable continuum model to take into account solvent effects. Three working formulas already widely tested in gas-phase have been used and the results compared. Two of the methods employed going from gas phase to solvent phase give values that do not change, while the results of the third method show remarkable changes. To check the reliability of the hardness behavior found, a test based on the hard-soft/acid-base principle and the calculation of the free energy of reaction has been applied using the adopted procedures.

Journal Article↗
PubMed1994

[The impact of the hostel life style on the health status of students].

The work aims at studying the specificity of the social living conditions, organization, regimen, psychosocial and other factors of life and their effect on the health status of students from the hostels of the students' town in Sofia. An inquiry is used, including 69 questions, connected with the organization and the conditions of living and education in the hostels. A statistical method for examining the chronic somatic morbidity is applied. By the inquiry method are investigated 1034 young people (boys and girls), living in the hostels of the Student's town. The statistical method assists in studying the chronic morbidity of 10.051 students, living in the hostels and of 9.562 students living in other places. The results show that in the hostel form of living there are infringements of the conditions and organization of the living standard, daily regimen, nutrition etc. The registered negative deviations correlate with the presence of higher chronic somatic morbidity, higher prevalence in spreading of socially important diseases-cardio-vascular, gastro-intestinal, renal. A hygiene-preventive program for improving the living standard, extending the dispensarization, carrying of prophylactic and treatment undertakings, etc. was recommended.

Bulgaria↗
PubMed1990

[Problems of the health status of the youth from a student town].

Studies are carried out on the health status and morbidity of students from the territory of the student town and health-hygienic undertakings are recommended for improving the health of the students and formation of health habits. For 8000 students were traced the following data: prophylactic examinations, acute morbidity, morbidity according to medical registrations studied from the statistical cards, the follow-up care of patients with chronic diseases. A scientific statistical method for studying the medical documentation is used for examining the acute and chronic morbidity. The basic moments in the structure of the students pathology are described, stimulated by the new moments of life in the conditions of the students town and the peculiarities in the health status of the students as special age group of the population. Conclusions are made concerning the carrying out of directed hygiene-preventive undertakings.

Bulgaria↗
PubMed1990

[Health and hygiene research on constructive toys intended for children over 7 under natural conditions].

Physiological and questionnaire investigations are carried out on 10 constructive toys, with the participation of 38 children 7 to 12 years old. A testimonial of the toys is made according to mass, dimensions, technological treatment, packing etc. A number of discrepancies with the hygienic requirements were established: 1) imperfection of the technological treatment (sharp edges, tops and holes, difficult assembling and disassembling of details, not fitting some details at construction, presence of odour, dust in the packings); 2) discrepancy with the announced age destination; 3) faults (incongruity of colours, small dimensions of models and not clear and contrast models, absence of age destination); 4) unphysiological strain and fatigue during play with part of the toys. On the basis of the results are developed hygiene recommendations to the manufacturing of constructive toys for children over 7 years.

Child↗
PubMed1989

[Health status of schoolchildren under five-day-week school program].

The effect of a five-day educative programme is studied with respect to the health status and morbidity of schoolchildren--from entering VIIth class in the Unified secondary professional school to completion Xth class. The data received are compared with the results from health exam on children, trained on six-day week. The results from the investigation show more favorable dynamics of the chronic, acute and neuro-psychic morbidity, the per cent of those frequently taken ill and is increased the number of healthy schoolchildren. In comparison with the traditional educative organization the five-day week programme has higher prophylactic effectiveness in the health protection of schoolchildren.

Bulgaria↗
PubMed1980

[Thermoregulation changes in secondary vocational and technical school students during the summer job experience].

Ninety pupils from a secondary polytechnical school for non-ferrous metallurgy, studying locksmith-mounter specialty, were examined during their summer industrial practice. The changes in body temperature, skin temperature and skin-electric resistance (SER) were studied. It was found that the diurnal and weekly variations in body and skin temperature and SER follow the diurnal and weekly biorhythm of these parameters and directly reflect the environment temperature changes and the duration and intensity of the work performed.

Adolescent↗
PubMed1976

[Health status and morbidity in schoolchildren from villages in Silistra and Tutrakan Districts].

This is study of the health state and morbidity rate in a group comprising 408 schoolchildren from the Silistra and Tutrakan regions, aged 7 to 14 years. The results of the research demonstrate a slight lagging behind of the school-children's physical development relative to children of comparable ages from the urban areas. Their health state is estimated as good, and the somatic neurotic morbidity--rather low. The most frequently encountered affections include diseases of the upper airways, infectious and dental diseases. A considerable number of slightly hypochromic anemias are also recorded.

Adolescent↗