Hygroscopy as an Indicator of Specific Surface Area in Polymer Materials.

Specific surface area (SSA) is an integral characteristic of the interfacial surface in poly-disperse systems, widely used for the assessment of technological properties in polymer materials and composites. Hygroscopic water content () is an obligate indicator of dispersed materials prior to any analysis of their chemical composition. This study links both indicators for the purpose of the express assessment of SSA using widely available data, on the example of natural (starch, cellulose) and synthetic (acrylic hydrogels) polymer materials.

Biodegradability of Gel-Forming Superabsorbents for Soil Conditioning: Kinetic Assessment Based on CO Emissions.

Quantification of the biodegradability of soil water superabsorbents is necessary for a reasonable prediction of their stability and functioning. A new methodological approach to assessing the biodegradability of these polymer materials has been implemented on the basis of PASCO (USA) instrumentation for continuous registration of kinetic CO emission curves in laboratory incubation experiments with various hydrogels, including the well-known trade brands Aquasorb, Zeba, and innovative Russian Aquapastus composites with an acrylic polymer matrix. Original kinetic models were proposed to describe different types of respiratory curves and calculate half-life indicators of the studied superabsorbents.

Gel-Forming Soil Conditioners of Combined Action: Field Trials in Agriculture and Urban Landscaping.

The article summarizes multivariate field trials of gel-forming soil conditioners for agriculture and urban landscaping in various climatic conditions from arid (O.A.E.

Gel-Forming Soil Conditioners of Combined Action: Laboratory Tests for Functionality and Stability.

The research analyzes technological properties and stability of innovative gel-forming polymeric materials for complex soil conditioning. These materials combine improvements in the water retention, dispersity, hydraulic properties, anti-erosion and anti-pathogenic protection of the soil along with a high resistance to negative environmental factors (osmotic stress, compression in the pores, microbial biodegradation). Laboratory analysis was based on an original system of instrumental methods, new mathematical models, and the criteria and gradations of the quality of gels and their compositions with mineral soil substrates.

Synthetic gel structures in soils for sustainable potato farming.

Anti-pathogenic protection of potatoes remains one of the most pressing problems of sustainable agronomy and plant protection. For this purpose, we propose to use a new type of synthetic hydrogels filled with amphiphilic recipients (dispersed peat, humates) and modern plant protection products. We assumed that the introduction of swollen gel structures into the rhizosphere of potatoes will allow us: to optimize the water supply and productivity of potatoes; to protect the fertile layer and potato tubers from the main pathogens; to fix modern plant protection products in the rhizosphere, keeping them from leaching and entering the environment.

Biodegradation of Some Organic Materials in Soils and Soil Constructions: Experiments, Modeling and Prevention.

The decomposition of natural and synthetic polymeric materials (peat, humates, biochar, strongly swelling hydrogels and other soil conditioners) in a biologically and chemically active soil environment inevitably leads to a reduced ability to improve the structure, water-retention, absorptive capacity and fertility of artificial soil constructions in urbanized ecosystems and agro landscapes (constructozems). Quantitative assessment of the biodegradation process using field and laboratory incubation experiments, as well as mathematical modeling, showed the possibility of significant (up to 30⁻50% per year) losses of organic matter of constructozems and a corresponding deterioration of soil quality. Incubation experiments that track the carbon dioxide emission rates of polymeric materials under given thermodynamic conditions allow for the estimation of decomposition rates in addition to an exploration on the dependence of such rates on additions of microbial inhibitors.

[Investigation of the threshold characteristics of visual information perception by operator controlling the illumination parameters in the 105-day experiment in isolation].

The investigations of threshold frequency characteristics (TFC) of the visual analyzer and labor productivity were carried out during 105-d isolation of volunteers in an airtight module illuminated by LED lamps adjustable to personal psychophysiological needs. Software and calculation procedure were devised to assist the chromatic TFC-based determination of photometric parameters. Data of analysis of actual mood and vision contrast sensitivity when looking at a three-color image suggested that visual performance could be improved by achieving light color adequacy to TFC of individual vision.

[Role of space-frequency characteristics of vision organ in the human psychophysiological state and performance].

Light conditions and color scheme of closed environments should be favorable to human performance. Space station lighting system should ensure visual comfort during work and be appropriate for crew health and well-being. To be successful in solving these problems, it is important to have objective data about luminosity and chromaticity distribution in closed environments.

Strategy and tactics of instrumental examination of patients with thoracic and thoracoabdominal aortic aneurysm.

The paper gives a detailed characterization and describes the importance of instrumental methods for examination of patients in the diagnosis of thoracic and thoracoabdominal aortic aneurysms. Provides a differentiated protocol of the examination of patients as dependent on the clinical course, disease stage and nemodynamic stability of the patient's status. Delineates the tactics of the examination of patients with acute and chronic dissection of the proximal and distal segments of the aorta as dependent on hemodynamic stability.

Identification of novel tumor markers in hepatitis C virus-associated hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common primary cancer associated frequently with hepatitis C virus (HCV). To gain insight into the molecular mechanisms of hepatocarcinogenesis, and to identify potential HCC markers, we performed cDNA microarray analysis on surgical liver samples from 20 HCV-infected patients. RNA from individual tumors was compared with RNA isolated from adjacent nontumor tissue that was cirrhotic in all of the cases.

[Insulinotropic factors in health and disease].

Reviews in brief the studies of the effects of some non-glucose regulators of various origins on pancreatic insulin secretion mediated by endocrine, paracrine, and neurocrine mechanisms, carried out in this laboratory. Model experiments with primary monolayer cultures of isolated islet cells have helped demonstrate a direct insulinotropic effect of STH, TRH, C-terminal tetrapeptide cholecystokinin, opioid peptides and blood plasma of patients with insulin-dependent diabetes mellitus. The findings evidence that the insulinotropic effect of the blood serum of patients with type I diabetes may be associated with both stimulation and suppression of the functional activity of the cultivated islet cells.

[Hypoinsulinemia, hyperglycemia and circulating antibodies to the islet cells during the development of streptozotocin diabetes in rats].

The time course of metabolic parameters and islet cell surface antibodies (ICSA) in low-dose streptozotocin (STZ)-induced diabetes in rats was studied, a total STZ dose being 160 mg/kg body weight. Two-phase diabetes development was observed. Initial mild hypoinsulinemia and hyperglycemia turned to more severe diabetes after day 24 which was preceded by the first ICSA peak at day 13.

The effects of sera obtained from children with insulin-dependent diabetes mellitus on cultivated islet cells: cytotoxicity and insulin release.

Sera were obtained from 24 patients with newly-diagnosed insulin-dependent diabetes mellitus (IDDM) and 14 children with a high risk of diabetes. The influence of the decomplementated sera on basal and stimulated insulin secretion was studied in a mixed culture of newborn rat islet cells. In addition, complement-dependent antibody-mediated cytotoxicity (C'AMC) was measured by 51Cr-release from pre-labelled islet cells.

Islet cell transplantation in type I diabetes mellitus: evaluation of humoral immune response.

Four males and three females ranging in age from 20 to 35 years and afflicted with complicated Type 1-diabetes for more than 8 years underwent islet cell allotransplantation (ATx, 6 cases) and xenotransplantation (XTx, 1 case). Precultured islet cells derived from human or bovine fetal pancreata were injected into the m. rectus abdominis.

[Mechanisms of the regulation of insulin secretion].

The endocrine, paracrine, and neurocrine influences of the non-glucose insulin secretion regulators on the pancreatic islets are analysed. Experiments on rats using the primary monolayer culture of isolated islet cells proved that insulin secretion is directly modulated by the growth hormone (GH), C-terminal tetrapeptide of cholecystokinin, thyroliberin, and met-enkephalin, and by certain blood plasma factors of diabetes I patients. In addition, GH is showed to stimulate the islet cell proliferation by intensifying 3H-thymidine incorporation into DNA synthesis.

[Simulation of diabetes mellitus in rats: Latent and manifest forms].

The paper is concerned with the investigation of problems of the etiology and pathogenesis of diabetes mellitus and simulation of this disease in animals in order to study its preclinical stages. Experiments were performed on adult male rats using i.v.

[Effect of fibroblast growth factor and nerve growth factor on the cellular proliferation and functional activity of isolated islands of Langerhans].

The effects of fibroblast growth factor (FGF) and nerve growth factor (NGF) on DNA synthesis and insulin secretion were studied in 4-5-day cultures of the isolated neonatal rat islets. FGF (0.1 ng/ml) stimulated significantly the incorporation of 3H-thymidine into DNA of the isolated islets, but failed to change either insulin content in the islets or the rate of insulin secretion.

[Immunoenzyme detection of autoantibodies to the surface of pancreatic islet cells in diabetes mellitus and in increased risk of its development].

The authors described the use of an enzyme-linked immunosorbent assay to determine islet cell surface antibodies (ICSA) in persons at high risk of developing insulin dependent diabetes (IDD) and different types of manifest disease. Among I degree healthy relatives of probands with IDD antibodies were detected in 16%. In disorder of the oral GTT (a small group) ICSA were found in 57% of examinees.

[Effect of nutrient medium perfusion on the secretory activity of rat hepatocytes and pancreatic islet cells].

The data are reported on albumin secretion by rat hepatocytes and insulin secretion by pancreatic beta-cells of newborn rats during cell cultivation on flat synthetic membrane in conditions of continuous medium perfusion. Albumin and insulin secretion by the appropriate cultures was higher in continuous medium perfusion than in the control. Enhanced sensitivity of pancreatic beta-cells to glucose, as compared to the control was revealed.

[Properties of (Ala5, Orn9)-somatostatin. The inhibition of pancreatic and hypophyseal hormone secretion in cell culture].

Ability of Ala5, Orn9-somatostatin to inhibit the secretion of insulin, glucagon, somatotropic hormone (STH) and prolactin was tested on the model of primary monolayer culture of isolated insular pancreatic and adenohypophyseal cells. Chemical substitution performed between positions 5 and 9 in somatostatin molecule failed to change essentially hormone's biologic activity in suppression of insulin and glucagon in the culture of pancreatic insular cells isolated from newborn rats. Somatostatin analog revealed its natural hormonal ability to inhibit STH secretion but failed to affect that of prolactin.

[Immunoenzyme determination of antibodies to the surface of islands of Langerhans in autoimmune destruction of the insular apparatus].

Enzyme-linked immunosorbent assay (ELISA) was applied for detection of human islet cell surface antibodies (ICSA) to rat islet target cells. In 23 healthy controls without hereditary diabetes the findings were on the upper normal limit (mean value of optical density + 3 SEM). The results above the limit were considered positive.

[Natural peptides and their analogs. XXXV. Synthesis and properties of [Ala5, Orn9]somatostatin].

A total chemical synthesis of [Ala5, Orn9]somatostatin has been performed. This structural analogue of natural somatostatin inhibits the release of somatotropin, insulin and glucagon, but shows no inhibitory effect on secretion of prolactin.