762 research outputs found
Differentiation circuits for amplitude modulated signal envelopes
Differentiation circuits for amplitude modulated signal envelope
Semileptonic transition in three--point QCD sum rules and HQET with gluon condensate corrections
Taking into account the gluon condensate contributions, the form factors of
the semileptonic transition with are
calculated in the framework of the three point QCD sum rules. The heavy quark
effective theory limit of the form factors are also computed. The relevant
total decay width as well as the branching ratio are evaluated and compared
with the predictions of the other non-perturbative approaches.Comment: 27 Pages, 4 Figures and 4 Table
Phonon mode softening and elastic properties of hafnium under pressure
The effect of pressure on the zone-center optical phonon modes and the
elastic properties of hafnium has been studied by both experimental (Raman
scattering) and theoretical (DFT) approaches. It was found an anomaly
dependence of the phonon frequency of E mode in the pressure range from
0 to 67 GPa. The calculated electronic structure of hafnium shows significant
changes under pressure, which have a pronounced spatial anisotropy similar to
the anisotropy of the observed phonon properties. The dependencies of the
elastic properties on pressure including the components of the elasticity
tensor, bulk and shear modulus, Poisson ratio and Universal anisotropy index
obtained during the calculations has characteristic features indicating the
occurrence of the structural phase transition.Comment: 8 pages, 12 figure
Elaboration of mathematical model of flight trajectory of material point in atmosphere
In the article, the flight trajectory of a material point in the atmosphere is considered. For its calculation the Runge-Kutta method and the system of the equations of external ballistics are used. Moreover, the approximation of the resistance function according to the 1943-year law for subsonic and supersonic speeds is made. The expansion of dependences of the excess above the line of aiming and flight time from the distance in Taylor’s series is implemented. The results of researches are used in solving the direct problem of external ballistics for the definition of trajectory parameters with an increased accuracy
Ammonium hexafluorosilicates: a new type of anti-caries agents
It is known that dental caries is one of the most common diseases; for children, this pathology ranks first among chronic diseases and has the character of a pandemic. In the modern arsenal of means for the treatment and prevention of caries, fluoride preparations – sodium, potassium fluoride, tin difluoride, sodium monofluoridephosphate, diammine silver fluoride – occupy the leading positions. In recent decades, ammonium hexafluorosilicate and hexafluorosilicates of organic ammonium cations, which have certain advantages over traditional fluoride preparations, have been actively studied as promising anti-caries and hypo-sensitive agents.
The aim of this review is to systematize and analyze literature data, reflecting existing experience in the field of synthesis methods, studying the structure, physicochemical properties and biological activity of ammonium hexafluorosilicates as potential anti-caries agents.
The general method for the synthesis of ammonium hexafluorosilicates is the interaction of the corresponding base, or its salt, in methanol, ethanol or another solvent with stoichiometric or excess amount of hydrofluoric acid. The structure of ammonium hexafluorosilicates, which are typical supramolecular compounds, is described. Using the example of pyridinium hexafluorosilicates, the relationship between water solubility and structural characteristics of salts was demonstrated. Identification methods have been proposed for the combination of cetylpyridinium hexafluorosilicate. The results of determination of acute toxicity for a number of hexafluorosilicates in animal experiments are given. Studies of the antibacterial activity of hexafluorosilicates are described. It is shown that hexafluorosilicates significantly reduce the number of carious lesions and their depth, and significantly exceed sodium fluoride in all indicators. The feasibility of their use for the prevention of periodontitis is demonstrated. A technological scheme for obtaining a gel containing cetylpyridinium hexafluoro silicate has been proposed.
General methods for the synthesis of ammonium hexafluorosilicates include the interaction of an organic base or the corresponding hydrochloride in a solvent medium with an excess of hydrofluoric acid silica. In the crystal structures of hexafluorosilicates, hydrogen bond systems with the participation of fluorine ligands and H-donor fragments of cations perform the main structure-forming and stabilizing function. The solubility of hexafluorosilicates in water varies widely, which is determined by the nature of the ammonium cation and, in the case of pyridinium salts, is antibatically correlated with the number of strong and medium H-bonds in the salt structure. The degree of hydrolysis of hexafluoro silicates in 1×10–4 М aqueous solutions is high and in some cases reaches practically quantitative values. The results of the determination of the acute toxicity of ammonium hexafluorosilicates make it possible to classify these compounds as moderately toxic substances. All studied ammonium hexafluorosilicates exhibit high caries preventive activity, significantly reducing the number and depth of carious lesions, while simultaneously significantly improving the biochemical parameters of dental pulp and periodontal bone tissue. Ammonium hexafluorosilicates can be used as new effective anti-caries and hypo-sensitive agents
Вторжение международного права в национальную правовую систему
The subject of the research is the peculiarities of the implementation of international law in national legal systems, the law enforcement practice of the implementation of international legal obligations of the state, doctrinal approaches to the interaction of the norms of international and domestic law. The purpose of the article is to confirm or disprove the hypothesis that the limits, forms and methods of the ex-ante intrusion of international law into the national legal system are determined not only as a result of the agreed will of States, but also against such will, under the influence of the interests of individual States or their political blocs that occupy a dominant position in an international organization. Methodology. The authors use such general theoretical and specific scientific methods as comparative analysis, generalization, interpretation and classification as well as systemic analysis and formal logical methods. The main results. The forms and methods of intrusion of international law into the legal systems are diversified. International law is not limited to interstate relations. Global processes require the development of new scientific approaches to understanding the processes of intrusion of international law into the legal systems of States. These processes require the study of the forms and methods of the impact of international law and international institutions on the national legal order. States are sometimes forced to implement measures developed in the international implementation mechanism (due to the need for international financial assistance as well as the inability to single-handedly defeat internal corruption, create a favorable international image, etc.). The international legal invasion exist already ex – post through the decisions of international judicial bodies or the assertive recommendations of international organizations. Their demands are made not just to comply with international obligations, but to change national legislation. The implementation of the norms of international law in national legal systems should be carried out at the domestic level just as much as it is necessary to fulfill these international obligations. The law enforcement practice in the state is based solely on national principles of law, and it is unacceptable to comply with the requirements from the outside to change them from the point of view of the independence of the state. It is the exclusive right of each State to determine the content of acts of interpretation of international bodies in relation to the decisions and actions of specific States from the point of view of their national interests. We prove that every state has the important right to determine the limits of the invasion of international law in their national legal system: the contents of implementing legislation; the completeness of implementation of the decisions and recommendations of international bodies and courts; the recognition of the extraterritorial validity of foreign law and forms of its implementation. Conclusions. The fundamental principle of international law- pacta sunt servanda – is transforming into a practical imperative – national legislation must change. This is due to the recognition of the jurisdiction of international judicial bodies. This is due to the extraterritorial effect of foreign law; it is connected with the transnational character of the law of international integration entities. This is due to the inability of individual States to resist exponential corruption. The continuous nature of the intrusion of international law into national legal systems is reflected in the various methods of such interference. The article proves the importance of each state having the right to independently determine the limits of the intrusion of international law into their national legal system.Неограниченность международного права только межгосударственными отношениями в результате глобальных процессов требует разработки новых научных подходов к осмыслению процессов вторжения международного права в правовые системы государств, воздействия норм международного права и международных институтов на национальный правопорядок, что и стало целью данной статьи. Опираясь на результаты, в том числе, проводимой в нашей стране конституционной реформы 2020 г., авторами сформулирован ряд выводов, которые охватывают: обоснование трансформации основополагающего принципа международного права – договоры должны соблюдаться – в практически императив – национальное законодательство должно изменяться; определение разнообразия форм вторжения международного права в национальные правовые системы, связанных с признанием юрисдикции международных судебных органов, экстерриториального действия зарубежного права, наднационального характера права интеграционных образований, с невозможностью отдельных государств противодействовать экспоненциальной коррупции исключительно национальными институтами власти. Доказывается значение наличия у каждого государства права самостоятельно определять пределы вторжения международного права в их национальную правовую систему: содержание имплементационного законодательства; полноты исполнения решений и выполнения рекомендаций международных органов и судов; признания экстерриториального действия зарубежного права и выбора форм его исполнения
- …