Effect of Silver Nanoparticles on the Optoelectronic Properties of Graphene Oxide Films

The effect of Ag nanoparticles (NPs) on the optical and optoelectronic properties of films based on graphene oxide has been studied. In the presence of Ag NPs, the morphology, as well as the thickness of graphene oxide films, were not changed. When Ag NPs were added, a change in the shape and position of the absorption bands and Raman spectra of graphene oxide was observed. It is shown that with the addition of Ag NPs, the G band of graphene oxide shifts to low frequencies, which may be the result of the absence of separate double bonds, while the ID/IG ratio was not changed, as did the number of Gr layers. In the absorption spectrum of the films, along with the absorption band of graphene oxide, a shoulder was registered, which can be associated with the absorption of Ag NPs. The optical density of Gr films with plasmonic NPs is higher than without them. Measurements of the optoelectronic characteristics showed that, in the presence of Ag NPs, an increase in the values of the photocurrent of graphene oxide is observed. The sensitivity of graphene oxide films was increased by almost 20 times when plasmonic NPs were added to them, and the detection ability increased by 25 times. The results obtained can be used in the development of new photosensitive devices for optoelectronic and photocatalytic applications

The Results of Plant Monitoring in the Semistozhki Area of Stavropol Region

Preserving biodiversity is a global problem that was reflected in the Convention on Biological Diversity which appeared in 1992. The adoption of the Convention was an answer to the intensified problem of a significant reduction in the diversity of genetic resources. Botanical gardens are the main centres for preserving the biodiversity of plants that solve the problem of preserving the gene pool. One of the main tasks of botanical gardens is to monitor plant populations in their natural habitats in situ. This paper describes the monitoring of the current state of peonies and sedges in the Semistozhki area of the Andropov district in the Stavropol region. The research determines the growing locations and the belongingness of species to plant associations in the vegetation variety of the Stavropol region. It also determines the species that may be treated as rare due to their limited distribution area. The territory is marked by the presence of Paeonia tenuifolia L., which is a tertiary relict, and Paeonia biebersteiniana Rupr., which is subendimic for Stavropol region. Rear species with low numbers that are not threatened by grave danger of extinction are also present. Carex hordeistichos Vill. and c. otrubae Podp. species in the area are small in number. Their populations in the area are inadequate with young, vegetative and strong specimens lacking. The limiting factors are represented by human agricultural activities. Several specimens of a narrow-leaved peony of pink colour and a big number of petals were planted on an experimental stretch of the botanical garden to continue the analysis ex-situ

Analysis of Optical Properties of Posterior Surface of Cornea in Patients after Anterior Radial Keratotomy

Taking into account the constant increase in patients with age-related cataracts after radial keratotomy, a careful analysis of both the optical and anatomical properties of the cornea with the examination of the posterior surface is of particular importance.Aim. To analyze the optical properties of the posterior surface of the cornea in patients after anterior radial keratotomy. Materials and methods. An examination of 24 patients (48 eyes) with age-related cataracts of varying degrees of density, myopia and the presence of a previous anterior radial keratotomy or radial-tangential keratotomy in history. The average age of patients was 59.5 years (from 47 to 68), there were 19 women and 5 men.Results. The radius of curvature of the anterior surface in patients after anterior radial keratotomy was 9.45 ± 0.91 mm on average along the meridians, which is significantly more in comparison with these indices in control patients – 7.70 ± 0.19 mm (p = 0.0001). The ratio of the radii of the posterior cornea curvature to the anterior radius on average along the meridians in patients after anterior radial keratotomy was 1.07 ± 0.70, and in control patients – 1.20 ± 0.02 (p = 0.0001). The keratometric index in patients after anterior radial keratotomy was 1.3538 ± 0.0239, and in the control group – 1.3372 ± 0.0003 (p = 0.23).Conclusion. In patients after anterior radial keratotomy, keratometry of the posterior surface of the cornea is significantly higher than in the control. The ratio of the radius of curvature of the posterior cornea to the radius of curvature of the anterior cornea varies significantly after anterior radial keratotomy, which is due to a more pronounced flattening of the posterior cornea. The standard keratometric index (1.3375) is invalid for patients after anterior radial keratotomy and must be calculated individually for each patient when deciding on the operative treatment of cataracts

Plasmon effect on triplet-singlet energy transfer in the dye-doped Langmuir-Blodgett films

The effect of silver plasmonic nanoparticles on triplet-singlet energy transfer in the donor-acceptor pair of organic dyes was studied. Layered dye films were prepared on the surface of glass and island silver films using the Langmuir-Blodgett method. Amphiphilic analogs of Rose bengal and polymethine dye were used as donor and acceptor of energy. A polymer monolayer was deposited between monolayers of donor and acceptor molecules to exclude the competing triplet-triplet energy transfer. The spectra of delayed fluorescence and phosphorescence of donor-acceptor films and the delayed luminescence lifetime of donor in these films have been measured. It is shown that a threefold increase in the fluorescence intensity and a twofold increase in the donor phosphorescence intensity are observed on silver island films. The successful triplet-singlet energy transfer is evidenced by both the quenching of donor centers and appearance of sensitized delayed fluorescence of the acceptor with the duration close to the donor triplet lifetime. In the presence of silver nanoparticles, in addition to enhancement in the intensity of the donor emission, an increase in the efficiency of tripletsinglet energy transfer was observed. The obtained results can be used in various optical devices

SEVERE ASTHMA IN CHILDREN

The definition of severe asthma is based on the criteria for clinical control, the treatment received, as well as the response to therapy, the assessment of future risk. In severe bronchial asthma, control can be achieved only at the highest possible level of therapy, namely, in treatment corresponding to the 4th or 5th stage. The article highlights the features of the clinical phenotype of severe bronchial asthma in children. Purpose: to identify the predictors of severe phenotype in children, the analysis of clinical and anamnestic features, to study the dynamics of disease control. Materials and methods: a group of patients with different degrees of severity of bronchial asthma aged 3 to 12 years, both sexes, was studied. The clinical aspects of the disease, the dynamics of control over bronchial asthma have been studied. Functional tests were carried out: examination of the function of external respiration, pyclofometry. Data of a specific allergic diagnosis (skin tests with non-bacterial allergens, detection of specific IgE antibodies), self-monitoring tests were studied. Statistical methods used a nonparametric method, a c2 distribution, a Pearson test, using conjugacy tables. Results and discussion: the family female phenotype is a predictor of severe bronchial asthma in patients in this group. The severity of the disease on the background of therapy for five years in a group of patients was revised only in a third of children. With this phenotype, partial control over the disease was achieved. The ineffectiveness of control is associated with the presence of a comorbid background: the pathology of the nervous system, the gastrointestinal tract, endocrine disorders. The severe phenotype of bronchial asthma, independently of age debut, was significantly less frequent than in the case of moderate disease

ASSOCIATION OF CC16 POLYMORPHISM WITH RISK FACTORS OF FORMATION OF BRONCHO-OBSTRUCTIVE SYNDROME IN CHILDREN

Syndrome of bronchial obstruction is a symptomatic complex arising on the background of constriction or occlusion of bronchial tubes of different caliber due to bronchospasm, edema and inflammation of the bronchial mucosa, hypersecretion of mucus or compression by surrounding structures. Bronchoobstructive syndrome (BOS) is one of the most common pathological conditions in pediatric practice. The outcome of BOS can be different: from the complete disappearance of clinical manifestations to the process, disability or even death. Accordingly, the study of this problem and the search for methods for early diagnosis and prediction of the outcome of BOS is a very urgent problem. In order to identify risk factors for BOS and to clarify the association with polymorphism of the CC16 gene, 126 children belonging to the main group and 58 from the comparison group were examined. In the course of the study, the triggers influence on the formation of the BOS of concomitant ENT pathology, burdened personal and family allergic anamnesis, and also the recurrent nature of respiratory infections in the first year of life was proved. The association of polymorphism of AA gene of CC16 with the presence of weighed allergic anamnesis and frequent episodes of ARVI, as well as the influence of this genotype on the early debut of respiratory diseases in children, has been revealed. The relationship of the GG genotype with the concomitant ENT pathology among patients with recurrent BOS has been proved

EVALUATION OF CLINICAL AND FUNCTIONAL OUTCOME OF MULTIFOCAL CORRECTION BY CONTACT LENS IN PATIENTS WITH PRESBYOPIA AND MYOPIA REFRACTION

The aim of the study was to evaluate the effectiveness of multifocal contact lens correction in patients with presbyopia and myopic refractive error. The study involved 45 patients with myopia ranging in age from 43 to 56 years in conditions of habitual monofocal contact lens correction, a month after the selection and wearing multifocal contact lenses. Contact correction was carried out according to standard procedures taking into account the accuracy of contact lens fitting, with carrying out functional tests for the "dry eye" syndrome and evaluation of corneal epithelial thickness (Optovue, USA). The assessment of the following parameters of visual perception was made: far, near and middle distance (monocular and binocular) visual acuity, the spatial contrast sensitivity, stereovision (I & II Lang test), the area of binocular interaction field (binarymeter), the quality of vision (VF-14 test ). The use of multifocal contact lenses for the correction of presbyopia with the initial myopic refraction ensures high functional results at different distances. Patients with a myopic refraction, previously used contact lenses, easy pass to multifocal correction option. The greatest satisfaction by achieved vision noted in those patients who had achieved refraction (-)0.5 diopters. In the selection of contact lenses in older patients the thickness of the corneal epithelium and tear film validity must be taken into account