of National Academy of Sciences
of Tajikistan

News of the National Academy of Sciences of Tajikistan.
Department of physical, mathematical, chemical, geological and technical sciences

Известия Национальной академии наук Таджикистана. Отделение физико-математических, химических, геологических и технических наук, №1(182), 2021 г.

Article title and abstractPages
Полный текст статьи

N.Rajabov , Kh.Firdavsi
To theory of one class of supersingular Volterra-type integral equation
In this paper, for a class of a supersingular integral equation of the Volterra-type, a variety of a general solution is obtained, via arbitrary constants. For integral equation, which is model integral equation for integral equation (1), in depend of the roots of characteristic equation (7), integral repetition manifold solution is obtained, by arbitrary constants. From obtained integral representation is folios, that in other cassis, homogeneous equation (5) has non zero solution, that is in this case theory this integral equation does not match with theory classic Volterra-type integral equation. Found condition too parameters equation (5), at fulfillment its, non homogeneous integral equation is has unique solution, that is in this case theory integral equation (5) matches whis theory classical Volterra-type integral equation

Ключевые слова: representation manifold solution; supersingular kernels; general solution; model equation; boundary fixed singularity; Volterra-type singular integral equation.

Полный текст статьи

On the noetherian and index of one model of singular integral operator
In this article the issue of Noetherian and the index of one model of singular integral operator and calculated its index are investigated.

Ключевые слова: singular integral operators; noetherian operators; simbol operator; index of operator.

Полный текст статьи

G.I.Kokhirova , A.M.Buriev , S.N.Safarov
Coordinates and orbit of the potentially hazardous asteroid 2003 SD220 from observations in the Hissar astronomical observatory
The results of astrometric processing of optical observations of potentially hazardous asteroid (163899) 2003 SD220 performed in the Hissar Astronomical Observatory in December 2018 are presented. The objects coordinates were determined and it was shown that the accuracy of astrometric measurements is less than 0.01 arcseconds both for the right ascension and the declination. The trajectory was obtained and the orbit of the asteroid was calculated. The results obtained are in good agreement with the available dynamic data. It was shown that the approach of the asteroid to the Earth in December 2018 did not cause a change in the orbit.

Ключевые слова: asteroid; observations; astrometry; coordinates; accuracy; trajectory; orbit.

Полный текст статьи

S.Odinaev , D.M.Akdodov , R.S.Mahmadbegov
Study of the frequency dispersion of the dielectric permeability coefficients and the dielectric losses of a water solution of cesium iodide
On the basis of previously obtained analytical expressions for the coefficients of the permittivity and dielectric losses of electrolyte solutions, the region of frequency dispersion of these coefficients of an aqueous solution of CsI was investigated in a wide range of changes in the concentration c, density ρ and temperature T. With a certain choice of the solution model, the interaction energy and the radial distribution function of ions of the a and b type, the friction coefficients and, the relaxation times , , and , as well as the coefficients and in a wide range of changes in the state parameters were calculated. The obtained theoretically calculated results , and the Cole-Cole diagram are in satisfactory agreement with the experimental data.

Ключевые слова: coefficients of dielectric constant and dielectric losses; coefficients of friction of ions; relaxation times; interaction energy; radial distribution function.

Полный текст статьи

I.R.Rahmonov , Yu.M.Shukrinov
Dynamics of the magnetic moment in the coupled system of long josephson junction and nanomagnet
We have investigated the dynamics of a nanomagnet coupled with a long Josephson junction. The manifestation of ferromagnetic resonance (FMR) on the voltage dependence of the maximum amplitude of magnetic moment oscillations is shown. It is demonstrated that in the region of the I - V characteristic corresponding to the fluxon branches, an additional peak is observed associated with the magnetic field of the fluxon in the long Josephson junction.

Ключевые слова: Josephson junction; fluxon; nanomagnet; FMR.

Полный текст статьи

Z.Umar , F.Shokir , F.Rahimi , M.Subhoni , T.Yamamoto
The electronic structure of MnDOPED SrZrO and SrHfO phospor materials
The electronic structure of two phosphor materials SrZrO:Mn and SrHfO:Mn are investigated in the framework of density functional theory using various calculation schemes: LDA, GGA, mBJ, and mBJ+U. LDA and GGA-calculated value of the band gap of "pure" perovskites SrZrO3 is significantly less than the experimental ones. However, calculations by mBJ method improve this problem. Hybridization between 3d-Mn and 2p-O for both systems is considered. The d-d orbital interactions of the Mn ion in SrZrO and SrHfO are considired by taking into account the Hubbard-U parameter. The dependence of the crystal field parameter-10Dq on the Hubbard parameter-U is studied with different values of the parameter U. The calculated crystal field parameter-10Dq of the Mn ion in SrZrO by mBJ+U (U=2.91 eV) method is equal to the experimental one.

Ключевые слова: the nanocrystal SrMO (M=Zr; Hf); DFT method; electronic structure; mBJ and mBJ+U; schemes of calculation.

Полный текст статьи

H.Z.Karambakhov , Sh.R.Samihov , M.Gh.Bobomulloev , Z.A.Safarova , Saydy Rahila , Rahmani Abdulhalim , A.M.Nematov , N.M.Jamolov , S.Sh.Safarov
Methods of chemical cleaning and conservation of historical copper materials, found from archaeological site Mes Aynak (Afghanistan)
In this paper the results of cleaning and removing of patina from surface of finds by using trilon B, citric and formic acids are presented and comparative estimate, preference and disadvantage used methods are conducted. The chemical composition is determined and conservation of finds by using copolymer polymethyl methacrylate (PMMA) is conducted.

Ключевые слова: copper finds; methods of chemical cleaning; determination of chemical composition of finds and conservation.

Полный текст статьи

Y.J.Kholov , I.N.Ganiev , J.H.Jayloev , N.I.Ganieva
Kinetics oxidation aluminum conductive of alloy E-AlMgSi (aldrey) with calcium in the solid state
The kinetics of oxidation of the aluminum conductive alloy E-AlMgSi (aldrey) with calcium was investigated by thermogravimetry. It has been established that calcium additions to the E-AlMgSi alloy (aldrey) reduce its resistance to oxidation in the solid state. It is shown that the oxidation of alloys proceeds according to a hyperbolic mechanism and is of the order of 10 kg∙m∙s.

Ключевые слова: aluminum alloy E-AlMgSi ("aldrey"); calcium; thermogravimetry; high-temperature oxidation; oxidation rate; activation energy.

Полный текст статьи

L.Soliev , M.T.Jumaev , R.O.Turaev , N.V.Olimdzonova , Kh.R.Makhmadov
Solubility in the system NaSO-NaCO-NaHCO-HO at 75°С temperature
In manuscript the investigation of solubility at invariant points in the system NaSO-NaCO-NaHCO-HO at 75°С is presented. The solubility diagram of the title system is modeled according to the obtained evidences.

Ключевые слова: solubility; balance; liquid phase; firm phase; chemical analysis; cristallooptical the analysis; diagram; geometrical images.

Полный текст статьи

A.S.Sodatdinova , S.M.Safarmamadzoda , M.M.Sangov , B.F.Abdurakhmonov , M.Z.Edalieva
Silver complex compounds with 1-methyl-2-mercaptoimidazole: stability, thermodynamic properties, practical application
The process of complexation of silver (I) with 1-methyl-2-mercaptoimidazole in an aqueous solution with an ionic strength of 0.1mol/l, created by NaNO at 273-318K was studied by potentiometric titration. It was found that silver with 1-methyl-2-mercaptoimidazole in the range 273 -318K forms two complex forms. General constants of stability of complexes and thermodynamic functions are calculated. It is shown that the stability constants decrease with increasing temperature. It was revealed that the negative value of ∆S upon complexation is a consequence of the greater hydration of the resulting complex particles in comparison with the initial ones. The ∆H value is negative when both complex forms are formed and is dominant in the spontaneous occurrence of the complexation reaction. An electrolyte for electrochemical deposition of silver based on [Ag(MI)(HO)] has been developed.

Ключевые слова: silver (I); 1-methyl-2-mercaptoimidazole; constant stability; complexation.

Полный текст статьи

N.S.Beknazarova , J.O.Shoalifov
Coordination compounds of rhenium (V) with 6-benzoylthiophene
The synthesis of rhenium (V) coordination compounds with 6-benzoylthioquinoline of the composition [ReOLHal] and [ReOLHal] in a medium of 6 mol/l Hhal, where Hal - Cl, Br is realized. The composition and structure of the obtained coordination compounds was established by elemental analysis and various physical and chemical methods.

Ключевые слова: coordination compounds; rhenium (V); 6-benzoylthioquinoline; synthesis; analysis.

Полный текст статьи

S.K.Nasriddinov , A.Badalov
System analysis of thermodynamic characteristics of halogenides of 3d-elements (II) and their modeling
A systematic analysis of the thermodynamic characteristics of 3d metal halides (II) is carried out by a semi-empirical method, which takes into account the features of the electronic structure, spin and orbital angular momenta of cations. The most complete thermodynamic characteristics have been obtained - enthalpy of formation, entropy and heat capacity of 3d-metal halides (II). The regularities of changes in the properties of compounds depending on the nature of cations are complex and are divided into so-called "subgroups", with the manifestation of the "tetrad-effect", and for anions are identical. Compounds of chromium and copper fall out of the general pattern due to their special electronic structure - partial (Cr) or complete (Cu) filling of 3d-orbitals with electrons.

Ключевые слова: halides; 3d-elements (II); thermodynamic characteristics; patterns of change; "tetrad-effect".

Полный текст статьи

Sh.B.Nazarov , Sh.Kh.Savzaeva , Z.S.Turaeva , B.Sh.Nazarov
Obtaining cryolite from aluminum-containing raw materials
The article presents the results of a study on the preparation of cryolite from aluminum salts (AICI and NaAIO) obtained from local aluminum-containing ores: nepheline syenites of the Turpy deposit and Tokmak alunite ores by sintering followed by decomposition of the obtained cake with water and mineral acid races. Hydrochloric acid was used as an acid for ore processing. From a hydrochloric acid solution of aluminum, as well as sodium aluminate, cryolite was obtained by treating salts with sodium fluoride.

Ключевые слова: nepheline syenites; alunites; acid decomposition; cake; aluminum hydrochloride salts; sodium aluminate; sodium fluoride; salt treatment with sodium fluoride.

Полный текст статьи

M.M.Mamadvafoev , D.A.Davlatshoev
About correlation relationship between minerals of introsive rocrs of Kafandara ore field (Eastern Hissar)
The article as first examined the linear correlation between the normative petrogenic and accessory minerals of the rocks of the intrusive complexes of Central Tajikistan using the Kafandara ore field as an example. It has been established that inversion (C) granitoids of increased basicity and assimilation origin, as well as post-inversion orogenic (P) subvolcanic dikes of quartz latith-porphyry, are particularly distinguished by a large number of significantly and strongly correlated minerals. A smaller number of significantly correlated minerals distinguishes the rocks of lower basicity, but greater silicic acidity and alkalinity, regardless of age and geotectonic position. The revealed correlation relationships and dependences between the minerals of individual rocks and their combination most likely reflect the patterns of acid-base differentiation of components (minerals) in a crystallizing magmatic melt.

Ключевые слова: East Gissar; Kafandara ore field; rocks of intrusive complexes; standard minerals and linear correlation relationships.

Полный текст статьи

Assessment of the glaciation state of the upper river Surkhob on the example of the Kamarov river basin under climate change
This article examines the state of the glaciers in the Kamarov river basin. Glaciers in the Kamarov river basin mainly have northern and north-western exposures, and according to their morphological type they belong to karov, hanging-tar and sloping ones. The assessment has shown that glaciers are degrading in the Kamarov basin. The total area of glaciation as a whole has decreased by 27.3%. With such a trend, glaciers in the Kamarov River basin may disappear in the future, which will lead to an imbalance in the mountain ecosystem.

Ключевые слова: glaciers; degradation; glaciation area; climate; precipitation; temperature.

Полный текст статьи

G.N.Petrov , S.Rasulov , H.M.Akhmedov , M.Ilolov , A.S.Kodirov , K.Rajabov
On the construction of a derivational hydroelectric power station on the Karatag river
Under favorable topographical and engineering-geological conditions, the construction and operation of a derivational small hydroelectric power station is the most suitable and economical option for the mountain rivers of Tajikistan. The authors believe that the proposed derivational small HPPs on the river Karatag at a high utilization rate of water runoff, can satisfy all sanitary, ecological and irrigation requirements, and a stable operating small HPPs on this river can be a demonstration object for the study of construction experience, research and further development of small hydropower in the Republic of Tajikistan.

Ключевые слова: water runoff; derivation; irrigation releases; small hydroelectric power station; capacity; river feed; design head; sanitary releases; environmental releases; efficiency of water resources use.

Полный текст статьи


Ключевые слова: .