689 research outputs found

    Quantum theory of electric polarization nonlinearity in metal nanofilms

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    We develop a quantum theory of electron confinement in metal nanofilms. The theory is used to compute the nonlinear response of the film to a static or low-frequency external electric field and to investigate the role of boundary conditions imposed on the metal surface. We find that the sign and magnitude of the nonlinear polarizability depends dramatically on the type of boundary condition used.Comment: Accepted to PRB in this for

    Diurnal variations of cosmic ray geomagnetic cut-off threshold rigidities

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    The spectrographic global survey method was used to investigate the rigidity variations Rc of geomagnetic cut-off as a function of local time and the level of geomagnetic disturbance for a number of stations of the world wide network. It is shown that geomagnetic cut-off threshold rigidities undergo diurnal variations. The diurnal wave amplitude decreases with increasing threshold rigidity Rc, and the wave maximum occurs at 2 to 4 hr LT. The amplitude of diurnal variations increases with increasing geomagnetic activity. The results agree with those from trajectory calculations made for an asymmetric model of the magnetosphere during different geomagnetic disturbance conditions

    STUDY OF FATTY ACID COMPOSITION OF MILK FOR CHEESE PRODUCTION

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    The article shows that the studied samples of raw milk in terms of composition (mass fraction of fat, protein, lactose and milk solids-not-fat) met the criteria of suitability for cheese, and its physic-chemical properties (titratable acidity, density, freezing point) were within acceptable limits. Moreover, rennet sample corresponded to the first and second classes. It was proved that the number of spores of lactating fermenting microorganisms met the requirements for milk for the production of any kind of cheese. It was established that the fatty acid composition of raw cow’s milk used to produce cheeses at various enterprises varied significantly. The data indicate the variability of the content of all groups of fatty acids — low molecular weight, saturated, monounsaturated and polyunsaturated. As a result of gas chromatography studies using the chromatographic complex «Chromos GX-1000» with a flame ionization detector and a CP 88 quartz capillary column — Sil 88 for FAME100 m × 0.25 mm × 0.2 µm, it was found that the largest absolute fluctuations were for saturated (± 7.03 % of the average value) and monounsaturated fatty acids (± 3.77 % of the average value). Absolute fluctuations in the group of low molecular weight fatty acids amounted to ± 2.62 %, and in the group of polyunsaturated — ± 1.02 % of the average value. The calculation of the relative deviation showed that the most varied groups were the ones of low molecular weight fatty acids (± 28.40 rel.%) and polyunsaturated fatty acids (± 25.11 rel.%). At the same time, a relatively high content of certain fatty acids: myristoleic, palmitic, palmitoleic and low levels of stearic and oleic fatty acids, was revealed in individual milk samples.The article shows that the studied samples of raw milk in terms of composition (mass fraction of fat, protein, lactose and milk solids-not-fat) met the criteria of suitability for cheese, and its physic-chemical properties (titratable acidity, density, freezing point) were within acceptable limits. Moreover, rennet sample corresponded to the first and second classes. It was proved that the number of spores of lactating fermenting microorganisms met the requirements for milk for the production of any kind of cheese. It was established that the fatty acid composition of raw cow’s milk used to produce cheeses at various enterprises varied significantly. The data indicate the variability of the content of all groups of fatty acids — low molecular weight, saturated, monounsaturated and polyunsaturated. As a result of gas chromatography studies using the chromatographic complex «Chromos GX-1000» with a flame ionization detector and a CP 88 quartz capillary column — Sil 88 for FAME100 m × 0.25 mm × 0.2 µm, it was found that the largest absolute fluctuations were for saturated (± 7.03 % of the average value) and monounsaturated fatty acids (± 3.77 % of the average value). Absolute fluctuations in the group of low molecular weight fatty acids amounted to ± 2.62 %, and in the group of polyunsaturated — ± 1.02 % of the average value. The calculation of the relative deviation showed that the most varied groups were the ones of low molecular weight fatty acids (± 28.40 rel.%) and polyunsaturated fatty acids (± 25.11 rel.%). At the same time, a relatively high content of certain fatty acids: myristoleic, palmitic, palmitoleic and low levels of stearic and oleic fatty acids, was revealed in individual milk samples

    Bullying as a social phenomenon in the modern world

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    Тhe article discusses approaches to the interpretation and the content of bullying, defines its types and distinguishes the forms of direct and indirect bullying. A comparative analysis of the results of domestic and foreign studies has revealed the spread scale of the bullying phenomenon in modern society, which causes the development of destructive socialization processes. It is emphasized that regular aggressive behavior towards one or a group of persons is a global problem, that is common for all countries of the world. The authors focus on the phenomenon of bullying in the socio-demographic groups of children and youth, which are among the most vulnerable in terms of socialization processes. At the same time, the consequences of bullying for its participants may be not only the deterioration of the physical and mental health of the younger generation, but also a lower socio-economic status in the stratification structure of society. In conclusion, the article concludes that in modern conditions it is necessary to actively develop and implement relevant initiatives of social institutions, which can serve as the basis for the formation of a legislative framework and state programs for the prevention and counteraction of bullying. Consequently, such initiatives will contribute to the formation of a healthy generation

    Parental Control in Modern Society: Priorities and Forms of Implementation

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    The problem of parental control as one of the basic characteristics of parent-child relationships is considered. The authors believe that the singularity of the modern era is determined by the dominance of prefigurative culture society with its characteristic fracture of patterns of behaviour established in previous generations. The results of empirical study of parental control in modern society are presented. The main spheres of its application and methods of implementation are characterized. It is shown that the priority sphere of control of today’s parents is the child’s state of health. The authors note that at the same time many parents underestimated the importance of control in the sphere of children’s interaction with the Internet and other modern means of mass communication. It is emphasized that in the present context “trust” control in these areas is tantamount to acquiescence and failure to take responsibility for the child. It is shown that in the information society one cannot apply to the former, traditional forms of parental control, which characterize the society of postfigurative culture. The obtained data indicate a lack of understanding of the parents the global changes of the whole sphere of social interaction related to the formation of fundamentally new communication culture of the modern society. The question of the elaboration of new methods of parental control that meet the requirements of the modern era is raised

    IMPROVEMENT OF ORGANOLEPTIC INDICATORS OF CHEESE PRODUCTS BY CORRECTING FATTY ACID COMPOSITION OF FAT PHASE

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    The aim of the study was to establish the possibility of improving the organoleptic characteristics of cheese products by introducing butyric acid into the composition of the used vegetable fat composition. Cheese products made using two fat compositions consisting of refined, deodorized vegetable fats, including those modified by interesterification, were studied. The experimental fat composition contained in its composition additional butyric acid added to the composition of triglycerides. The study of cheese products was carried out in the process of ripening and storage for 120 days in comparison with cheese, the fat phase of which is represented by milk fat. It was found that the degree of proteolysis, estimated by the ratio of total water-soluble nitrogen to total nitrogen, does not depend on the nature of the fat in the protein matrix. Milk fat in cheeses is more subjected to lipolysis than vegetable fats in cheese products. The addition of butyric acid to the vegetable composition in an amount of 0.8% increased the acidity of the fat phase by 0.1 mmol/100 g. According to the assessment of organoleptic characteristics, cheese with milk fat had the most pronounced cheese flavor and aroma, cheese product without butyric acid in fat phase had the least pronounced ones. A cheese product with a fat composition containing added butyric acid was close to cheese with milk fat in terms of the severity of cheese taste, rheological characteristics and the spectrum of volatile flavoring substances. It is concluded that the taste and aroma of cheese products have a positive effect on adjusting the fatty acid composition of vegetable fat compositions by introducing butyric acid into their composition.The aim of the study was to establish the possibility of improving the organoleptic characteristics of cheese products by introducing butyric acid into the composition of the used vegetable fat composition. Cheese products made using two fat compositions consisting of refined, deodorized vegetable fats, including those modified by interesterification, were studied. The experimental fat composition contained in its composition additional butyric acid added to the composition of triglycerides. The study of cheese products was carried out in the process of ripening and storage for 120 days in comparison with cheese, the fat phase of which is represented by milk fat. It was found that the degree of proteolysis, estimated by the ratio of total water-soluble nitrogen to total nitrogen, does not depend on the nature of the fat in the protein matrix. Milk fat in cheeses is more subjected to lipolysis than vegetable fats in cheese products. The addition of butyric acid to the vegetable composition in an amount of 0.8% increased the acidity of the fat phase by 0.1 mmol/100 g. According to the assessment of organoleptic characteristics, cheese with milk fat had the most pronounced cheese flavor and aroma, cheese product without butyric acid in fat phase had the least pronounced ones. A cheese product with a fat composition containing added butyric acid was close to cheese with milk fat in terms of the severity of cheese taste, rheological characteristics and the spectrum of volatile flavoring substances. It is concluded that the taste and aroma of cheese products have a positive effect on adjusting the fatty acid composition of vegetable fat compositions by introducing butyric acid into their composition

    Spectroscopic studies of fractal aggregates of silver nanospheres undergoing local restructuring

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    We present an experimental spectroscopic study of large random colloidal aggregates of silver nanoparticles undergoing local restructuring. We argue that such well-known phenomena as strong fluctuation of local electromagnetic fields, appearance of "hot spots" and enhancement of nonlinear optical responses depend on the local structure on the scales of several nanosphere diameters, rather that the large-scale fractal geometry of the sample.Comment: 3.5 pages, submitted to J. Chem. Phy
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