Recently Published Documents
The analysis of existing models of stress in thin films and coatings was carried out. While reaching critical value, stress can lead to defects, cracks, delamination of coating from substrate, etc. The task of prediction and controlling of the direction and magnitude of the stress of coating-substrate system is relevant nowadays regardless of coating and thin films deposition methods. Different types of coatings and thin films are widely used in almost all industries: optics, mechanical engineering, measuring technology, medicine, micro- and nanoelectronics, etc. Development and investigation of new promising methods for the formation of nanostructures, such as nanowires in a plasma environment, requires a sufficient theoretical basis for the origin and growing of stresses. Depending on the mechanism, the causes of stress in thin films and coatings can be: chemical reactions, phase transformations, inclusions and impurities, particle bombardment (the cause of internal stress during coating growing); temperature changes (the cause of thermal stress due to different values of coefficients of thermal expansion of coating and substrate materials); deformation of coating-substrate system, etc. Models of stress development in coatings and thin films can be divided into the following groups: stress that occur at the coating-substrate interface, internal coating stress, and stress at the coating-environment interface. The study presents methods of stress measuring in thin films and coatings. Based on the results of the current research, it can be concluded that the existing models of stress in the process of growth of coatings and films, as well as stress arising under the action of external forces, describe only the causes of the stress and unfortunately do not give an understanding of their complex effect on stress-strain state of coating-substrate system and need further development and improvement. Stress relaxation is also important to obtain new structures and certain properties of coatings. The development of stress management tools can be considered as one of the ways to increase the lifetime of products with coatings and thin films.
IMPACT OF THE HIGH-SPEED FLOW OF POWDER PARTICLES ON THE STRUCTURE OF POLYMER MATERIALS AND METAL-POLYMER COMPOSITES
The problem of protecting spacecraft from cosmic dust has recently come to the fore. There is still no enough data on the complex effect of short-term high-energy, dynamic loading on materials, including polymer materials and multilayer polymer-metal composites. The use of dynamic alloying in the super-deep penetration (SDP) mode by high-speed flows of powder particles allows assessing the effect on the material under dynamic action. Previous studies on steel and aluminum samples have shown a significant effect of high-speed flows of powder particles on the structure and properties of materials. As a result of a study of samples made of aliphatic polyurethane with steel reinforcement elements, it was found that there are traces of the penetration of high-speed particles into both metal and polymer layers. However, the number of flow elements detected in the polymeric part is significantly less than the number of elements in the metal reinforcing part. Thus, it is possible to assume that or the polymer material is a more effective barrier to the high-speed flow compared to the metal, or the “self-healing” effect is observed.
Hybrid Microporous Polymeric Materials with Outstanding Permeability and Increased Gas Transport Stability: PTMSP Aging Prevention by Sorption of the Polymerization Catalyst on HCPS
The influence of hyper-crosslinked polystyrene (HCPS) MacronetTM MN200 on the gas transport properties and aging of the highly permeable glassy polymer poly(1-trimethylsilyl-1-propyne) (PTMSP) was studied and analyzed in detail. The gas transport characteristics of dense PTMSP membranes containing 0–10.0 wt % HCPS were studied. It was shown that the introduction of a small amount of HCPS into the PTMSP matrix led to a 50–60% increase of the permeability coefficients of the material for light gases (N2, O2, CO2) and slowed down the deterioration of polymer transport properties over time. The lowest reduction in gas permeability coefficients (50–57%) was found for PTMSP containing HCPS 5.0 wt % after annealing at 100 °C for 300 h. It was found that HCPS sorbed residues of tantalum-based polymerization catalyst from PTMSP. In order to investigate the influence of catalysts on transport and physical properties of PTMSP, we purified the latter from the polymerization catalyst by addition of 5 wt % HCPS into polymer/chloroform solution. It was shown that sorption on HCPS allowed for almost complete removal of tantalum compounds from PTMSP. The membrane made of PTMSP purified by HCPS demonstrated more stable transport characteristics compared to the membrane made of the initial polymer. HCPS has a complex effect on the aging process of PTMSP. The introduction of HCPS into the polymer matrix not only slowed down the physical aging of PTMSP, but also reduced chemical aging due to removal of active reagents.
The DRD2 Taq1A polymorphism moderates the effect of PTSD symptom severity on the left hippocampal CA3 volume: a pilot study
Abstract Rationale and objectives The hippocampus, especially the CA1, CA3, and dentate gyrus (DG) subfields, is reported to be associated with post-traumatic stress disorder (PTSD) after trauma. However, neuroimaging studies of the associations between PTSD and hippocampal subfield volumes have failed to yield consistent findings. The aim of this study is to examine whether the dopamine D2 receptor (DRD2) Taq1A polymorphism, which is associated with both hippocampal function and PTSD, moderated the association between PTSD severity and hippocampal CA1, CA3 and DG volumes. Methods T1-weighted images were acquired from 142 trauma survivors from the 2008 Wenchuan earthquake using a 3.0-T magnetic resonance imaging system. Hippocampal subfield segmentations were performed with FreeSurfer v6.0. We used the simple moderation model from the PROCESS v3.4 tool for SPSS 23.0 to examine the association between the rs1800497 polymorphism, PTSD severity, and hippocampal CA3 and DG volumes. Results A significant genotype × PTSD symptom severity interaction was found for the left CA3 volume (ΔF = 5.01, p = 0.008, ΔR2 = 0.05). Post hoc, exploratory analyses deconstructing the interaction revealed that severe PTSD symptomatology were associated with reduced left CA3 volume among TC heterozygotes (t = − 2.86, p = 0.005). Conclusions This study suggests that DRD2 Taq1A polymorphism moderates the association between PTSD symptomatology and left CA3 volume, which promotes an etiological understanding of the hippocampal atrophy at the subfield level. This highlights the complex effect of environmental stress, and provides possible mechanism for the relationship between the dopaminergic system and hippocampal function in PTSD.
The impact of living arrangements and intergenerational support on the health status of older people in China: are rural residents disadvantaged compared to urban residents?
Abstract Research to-date has examined the impact of intergenerational support in terms of isolated types of support, or at one point in time, failing to provide strong evidence of the complex effect of support on older persons’ wellbeing. Using the Harmonised China Health and Retirement Longitudinal Study (2011, 2013 and 2015), this paper investigates the impact of older people's living arrangements and intergenerational support provision/receipt on their physical and psychological wellbeing, focusing on rural–urban differences. The results show that receiving economic support from one's adult children was a stronger predictor for higher life satisfaction among rural residents compared to urban residents, while grandchild care provision was an important determinant for poor life satisfaction only for urban residents. Having weekly in-person and distant contact with one's adult children reduced the risk of depression in both rural and urban residents. Older women were more likely than men to receive support and to have contact with adult children, but also to report poor functional status and depression. The paper shows that it is important to improve the level of public economic transfers and public social care towards vulnerable older people in rural areas, and more emphasis should be placed on improving the psychological wellbeing of urban older residents, such as with the early diagnosis of depression.
Examining Students’ Online Course Perceptions and Comparing Student Performance Outcomes in Online and Face-to-Face Classrooms
Through the use of existing grade and student survey data, this study investigated online courses offered at a public four-year university. Specifically, the study explored differences in student success rates between online and face-to-face courses for traditional undergraduate students as well as the climate of student perceptions towards online courses. Our general results suggest that students performed better in, and had higher levels of preference toward, traditional face-to-face formats. However, overall perceptions of online courses were positive, with students viewing instructional technologies as reliable and easy to use, as well as reporting that online technologies facilitated prompt feedback, enhanced their problem-solving skills, and met their learning needs. Alongside this, students exhibited positive views towards their instructors’ skill level and use of technology to support academic success. Logistic regression analyses of differences in student success across instructional formats revealed interaction effects with variables of age (nontraditional/traditional), aid status and whether or not courses were taken to fulfill general education or major requirements, suggesting a more complex effect of instructional format across student subpopulations. The variability in the results observed in the current study warrant further exploration before definitive conclusions on the impact of instructional format on student outcomes and perceptions can be made.
Development of a method for producing new generation of protein snacks using the processes of cryo and mechanical distruction
The aim of research is to develop a method for the production of a new generation of protein snacks using a protein vegetable and milk base and vegetable fortifiers from spicy and carotene-containing vegetables using cryo and mechanical destruction processes. The method is based on the use of a deep processing method as an innovation, which consists in a complex effect on vegetable and protein raw materials of cryo and mechanical destruction processes in modern quick-freezing and low-temperature crushing equipment. The proposed method allows to get new protein snacks with a high content of protein, BAR and phytocomponents in an easily digestible form. A new generation of protein snacks has been developed to strengthen the immune system using cryogenic protein base and vegetable raw materials. Nano-additives from dried peas and specially processed soft brine cheese are used as a protein base. Pea nanoadditives obtained using non-enzymatic catalysis – mechanolysis, mechanical destruction contain 21.5 ... 23.0% of complete protein, which includes 49% of amino acids in a bound state and 51% in a free state. During the special processing of soft brine cheese with the help of mechanical destruction, 50 ... 55% of the bound amino acids of the protein are transformed into free α-amino acids in an easily digestible form. The proposed method makes it possible to more fully reveal the biological potential of vegetable and protein raw materials, to transform protein, BAS and phytocomponents in a bound form into easily digestible nanocomponents into a free easily digestible form. In addition, the processed protein base and raw materials acquire new properties - structure formation, gelation, coloring ability. The obtained protein snacks are natural, differ from the traditional ones by their high content of complete protein and the absence of synthetic impurities (preservatives, thickeners, colorants, etc.). In addition, 100 g of new products can satisfy the daily requirement for biologically active substances (β-carotene, L-ascorbic acid, phenolic compounds)
A Forecast Model of the Complex Negative Impact of Agricultural Production Technologies on Water Bodies
Introduction. The purpose of research is to develop a mathematical model for assessing and forecasting the complex negative impacts of agricultural technologies on water bodies. This problem is relevant because of the need to enlarge agricultural enterprises. The created model for forecasting is necessary to make an objective assessment, taking into account the complex effect of machine technologies applied to agricultural production and all biogenic elements that have a negative impact on water bodies. Materials and Methods. There was used the Spesivtsev – Drozdov method of logical-linguistic modeling, which allows giving expert knowledge a form mathematical model. Four experts were interviewed, and the obtained data became a subject of the regression analysis. The adequacy of the model was confirmed using the coefficient of determination and Fisher’s test. Results. A hierarchical system of 6 factors and 14 sub-factors was formed, including both the applied machine technologies and the management decisions on the matter. There was created a model containing a polynomial equation reflecting the influence of factors on the level of negative impact of technologies and equations that determine the influence of sub-factors on factors. Discussion and Conclusion. The created model can be used for practical purposes to support making decisions for planning, forecasting and selecting scenarios to modernize agricultural enterprises. The model equations make it possible to understand the significance of factors and sub-factors affecting the level of negative impact (diffuse load) on water bodies. This allows us to choose more effective ways to reduce the negative impact by choosing the most significant factors and/or sub-factors as objects of management.
Effect of Neuropeptide S Administration on Ultrasonic Vocalizations and Behaviour in Rats with Low vs. High Exploratory Activity
Neuropeptide S (NPS) is a peptide neurotransmitter that in animal studies promotes wakefulness and arousal with simultaneous anxiety reduction, in some inconsistency with results in humans. We examined the effect of NPS on rat ultrasonic vocalizations (USV) as an index of affective state and on behaviour in novel environments in rats with persistent inter-individual differences in exploratory activity. Adult male Wistar rats were categorised as of high (HE) or low (LE) exploratory activity and NPS was administered intracerebroventricularly (i.c.v.) at a dose of 1.0 nmol/5 µL, after which USVs were recorded in the home-cage and a novel standard housing cage, and behaviour evaluated in exploration/anxiety tests. NPS induced a massive production of long and short 22 kHz USVs in the home cage that continued later in the novel environment; no effect on 50 kHz USVs were found. In LE-rats, the long 22 kHz calls were emitted at lower frequencies and were louder. The effects of NPS on behaviour appeared novelty- and test-dependent. NPS had an anxiolytic-like effect in LE-rats only in the elevated zero-maze, whereas in HE-rats, locomotor activity in the zero-maze and in a novel standard cage was increased. Thus NPS appears as a psychostimulant peptide but with a complex effect on dimensions of affect.
Research aim: to evaluate the effectiveness of therapy aimed at preventing endometrial hyperplasia recurrence in premenopausal women.Materials and methods. Clinical and paraclinical examinations of 76 premenopausal women were carried out. Transvaginal ultrasound was performed, levels of estradiol, progesterone, homocysteine, folic acid, serum HOMA index evaluated, body mass index and blood pressure assessed. Women were divided into two groups after histological results obtained: the main group included 40 women who received oral progestins (dydrogesterone 10 mg) twice a day in combination with Depapilin® 395 mg twice a day; the comparison group included 36 women who received only oral progestins (dydrogesterone 10 mg) twice a day. Comparison of the therapy effectiveness was performed 6 and 9 months after the start of treatment.Results. Endometrial thickness stabilized within 9 months in women of the main group, and was within the physiological norm (before treatment – 22 ± 3.1 mm, 6 months after the start of treatment – 8,3 ± 0.46 mm, after 9 months – 9,7 ± 0.31 mm, p <0.05). The positive treatment effect consisted in a significant decrease in the frequency of endometrial hyperplasia recurrence, which was 17 (17.5%) cases in the main group and 16 (44.4%) cases in the comparison group (p <0.05). Women of the main group also showed stable normalization of the level of estrogen and progesterone, a steady decrease in the level of homocysteine and a synergistic increase in the level of folic acid, normalization of blood pressure and reduction of body mass index.Conclusions. Depapilin® inclusion in the basic therapy of endometrial hyperplasia in premenopausal aged women is pathogenetically justified due to the complex effect of the drug components on the extragonadal estrogens synthesis and the antiproliferative effect on the endometrium.