Доклады Академии наук Республики Таджикистан, том 62, №03-04, 2019 г.
|Article title and abstract||Pages|
|Rakhmonov Z.Kh., Aminov A.S.|
On the zeros of an odd order of the Davenport-Heilbron function in short intervals of the critical line
In this paper, the problem of the number of zeros of the Davenport-Heilbronn function in short intervals of the critical line reduces to the problem of finding exponential pairs for estimating special exponential sums.
Key words: Davenport-Heilbronn function; exponential pair; Riemann hypothesis; Selberg's soothing factors.
|Iskhokov S.A., Yakushev I.A.|
On smoothness of a solution of variational Dirichlet problem for elliptic operators with uncoordinated degenercy
in a bounded domain
We investigate smoothness of a solution of the variational Dirichlet problem for a class of higher-order elliptic operators in a bounded domain of the n-dimension euclidian space with uncoordinated degeneracy of coefficients along the entire boundary of the domain. Integro-differential forms associated with differential equations under consideration may not satisfy the condition of coercivity.
Key words: variational Dirichlet problem; elliptic operator; power degeneration; bounded domain; noncoercive form; smoothness of solution.
About the neighboring zeros of the derivative of n-th order function Hardy
A new estimate for the length of the interval of the critical line, which contains a zero of odd order of the derivatives of the n-th order of the Hardy function is obtained.
Key words: Hardy function; exponential pair; the Riemann zeta function; critical line; trigonometric sum.
|Madimarova F.M., Akobirshoev M.O.|
The extremal problems of the theory aproximation function of two variables and exact inequalities of Kolmogorov type for operators
In this paper, a series of extremal two variables with a Chebyshev weight function are solved and exact Kalmagorov-type inequalities are found for the Chebyshev differential operator of the second regiment.
Key words: Generalized shift operator; Chebyshev polynomial; Chebyshev quasi-polinomial; two Chebyshov operators; Kolmogorov's inequality.
|Kabilov M.M., Khalimov I.I.|
Features of combustion of a methane-air mixture in an inert porous medium
The combustion of a methane-air mixture in an inert porous medium is considered within the framework of an equivalent filtration model for gases. The condition on the boundary of the porous block, where the gas mixture is fed, has been studied. The calculated temperatures profiles of the porous medium, the gas mixture and the fraction of the fuel concentration are presented and analyzed. In addition, the following parameters of the combustion wave, such as the maximum and equilibrium temperature, the velocity and thickness, the characteristic length and time of exit of the wave to a stationary mode are investigated.
Key words: combustion wave; gas mixture; concentration; ignition temperature; equilibrium temperature; maximum temperature; wave velocity; wave structure; fuel excess ratio.
|Kokhirova G.I., Babadzhanov P.B., Khamroev U.Kh., Latipov M.N., Faizov Sh.B.|
Perseids meteoroids by observations of the Tajikistan fireball network:
II. Physical properties
The data on physical properties of 29 Perseids fireballs observed by the Tajikistan fireball network in 2006-2011, namely, light curves and features of luminosity, photometric masses and densities of meteoroids are given. Preatmospheric masses range from 1 g to 100 g. The dependencies of the brightness on the preatmospheric masses as well as the beginning/terminal heights on the preatmospheric masses are shown. The light curves are typical for cometary bodies and indicate their intensive fragmentation in the Earths atmosphere. According to the empirical criterion of end heights the majorities of fireballs belongs to IIIA and IIIB fireballs groups and, consequently, were produced by the meteoroids consisting of porous cometary material. However 12 fireballs belong to II group and therefore were produced by the bodies of more dense asteroidal matter. The existence such bodies among the cometary Perseids meteoroids confirms the suggestion on non-homogenous composition of the parent comet.
Key words: fireball; meteoroid; absolute magnitude; light curve; preatmospheric mass; height; density.
|Umar Z., Qurbonien M.S., Tomoyuki Yamamoto, Rahimi F.|
Theoretical investigathion of the electronic structure of LaScO:Mn within density functionality theory
In this work, the results of quantum mechanical simulations of the electronic structure of LaScO:Mnare presented by means of various calculation schemes - GGA, GGA+U, mBJ and mBJ+U. All the electronic structure calculations were carried out using the full-potential (linearized) augmented plane-wave (L)APW ) + local orbitals (lo) method. It is shown that the results of quantum-mechanical calculations in the framework GGA+U and mBJ+U are in good agreement with experimental dates.
Key words: LaScO nanocrystal; electronic structure; method DFT; schemes of calculation; GGA; mBJ; DFT+U.
|Toshhodzhaev H.A., Levandovsky B.I.|
Main characteristics of martencite transformations and shape memory effect in alloys NiFeGaCo
The article deals with research of peculiarities of martensitic transformations, shape memory effect in alloys NiFeGaCoand features of diagrams of deformation of alloys. Analysis of the behavior of the alloy NiFeGaCo depending on the deformation temperature is produced. It was revealed, that alloy of NiFeGaCo possesses characteristic properties of martensitic transformations.
Key words: smartmaterials; alloys; shape memory effect; martensite; austenite; deforming; temperature.
|Abdulloev Kh.O., Rakhmonov S.S.|
Nonlinear wave formations in dispersing media
Nonlinear waves in dispersive media in the one dimensional case are studied. Nonlinearity generating harmonics with large wave numbers, embanks dissipation of wave packets. Disperse mixing phase suppresses this process.
Key words: nonlinear; wave packets; evolutions; perturbation; dispersive media; dispersions; Langmuir waves; plasma; turbulent.
|Qasuria T.A.Kh., Alam S., Fatima N., Karimov Kh.S., Akhmedov Kh.M.|
Research of invert solar element on the basis of perovskite and cadmium sulfide
The work describes the fabrication and study of the properties of an invert solar cell based on perovskite and cadmium sulfide containing new layers with electron and hole conductivity. The dark and current-voltage characteristics (I - V) of a perovskite solar cell (PSE) were measured. It is shown that the IVC is diode, i.e. with the characteristic of the device characteristic of the solar cell. It is shown that although PSE has a broad absorption spectrum from 350 nm to 750 nm, however, its conversion efficiency is only 1.01%, which is mainly due to the degradation of perovskite films under the influence of oxygen, air moisture, and UV radiation.
Key words: perovskite; solar cell; current-voltage characteristic; conversion efficiency; film degradation.
|Salimov А.М., Sharopov F.S., Sangov Z.G., Mirzoev S.О., Salimov Т.М., Khaidarov К.Kh.|
The composition of essential oil of Аrtemisia annua growing wild in Tajikistan
There are studied aboveground part of the medicinal plant L., growing wild in Tajikistan. It is shown presence of essential oil (0.9%). The chemical composition of the essential oil was studied by gas chromatography / mass spectrometry (GC/MS) method, there are identified 38 components, main components are camphor (32.5%), 1,8-cineole (17.8%), camphene (8.4%), α-pinene (7.33%), myrcene (3.3%), β-caryophyllene (3.3%).
Key words: Artemisia annua L.; essential oil; composition.
|Umarovа T.M., Dzhalolov F.N., Ganiev I.N.|
Influence of european on phase composition and microstructure of aluminum-iron alloy AlFe1.8
The results of a study of X-ray phase and microstructural analyzes of aluminum alloy АЖ1.8 eutectic composition, modified by europium (up to 0.10 wt.%) are presented.
Key words: aluminum alloy АЖ1.8; europium; X-ray phase analysis; diffractogram; microstructure.
|Ismailov I.B., Malikov T.S., Nasriddinov A.S., Dzоnmurodov A.S., Muhidinov Z.K.|
Preparation and chracterization of the biodegradble films from zein and glucomannan
In this article results of the formation of biodegradable composites (films) based on zein (Z) and glucomannan (GM), as well as the study of their interaction using FTIR spectroscopy are presented. It was established that due to the cluster structure of the protein fraction and the linearity of the polysaccharide macromolecule, their interaction occurs through hydrogen and hydrophobic bonds. The results of the study showed the possibility of the formation of Zein-GM films at an optimal ratio of Z/GM equal to 1.5, which can be used as a biodegradable film for long-term storage and transportation of fruits and vegetables.
Key words: zein; glucomannan; biodegradable film; FTIR spectroscopy.
New species of devonian foraminifera of Zeravshan range (Central Tajikistan)
One new genus and four new species of calcareous Foraminifera belonging to the families Parathuramminidae, Bisphaeridae and Earlandiidae have been identified and described in the Devonian deposits of Zeravshan Ridge.
Key words: Foraminifera; Devonian system; Emsian stage; Fraznian stage; Famennian stage.
|Sharofova M.U., Aldibiat I., Saidov Kh.B., Sagdieva Sh.S., Khakimov F.R., Rahimi F.K., Mirshahi M.|
Plastic biodegradation by wax moth larvae of Galleria mellonella from Darvaz
During the incubation of fragments of plastic material in containers with larvae of the wax moth Galleria mellonella from Darvaz, the fact of plastic biodegradation was noted. G. mellonella from Darvaz region can be used in the future for development of a biotechnological system for the elimination of plastic bags and microparticles that pollute the human microenvironment.
Key words: wax moth; Galleria mellonella; larval stage; plastic biodegradation; Darvaz district of Tajikistan; scanning electron microscopy.
|Hisoriev H., Kurbonova P.A., Khudjaev M., Ysupova F.|
A new floristic findings of algae from Sarband water reservoir
In this article the dates of a new floristic findings of Euglenophyta, Chlorophyta, and Streptophyta algae for Tajikistan algae flora, which were found in Sarband water reservoir along Vakhs river are given.
Key words: algae; new floristic findings; Tajikistan.
|Iskandarov F.M., Habirov Z., Komilova S.R., Mirzorajabzoda N.|
Species composition and distribution of bloodsucking (Diptera: Ceratopogonidae, Culicidae) of Gissar and Darvaz mouintain ranges
In the is article the data about two families of bloodsucking - mosquitoes (Dipter: Ceratopogonidae, Culicidae), their species composition and distribution in the Gissar and Darvaz mountain Ridges are presents.
Key words: bloodsucking dipterans; dominant species; biting midges; mosquitoes; gadflies; Gissar and Darvaz ridge.
|Norkulov N.Kh., Norkulova Z.Kh., Solieva B.A., Kasparova I.S., Oyzoda N.Kh., Dilovarova N.S., Khakimova R.Sh., Aliev K.A., Abdullaev Kh.A.|
Contents of malon dialdehyde and activity of a superoxide dismutase in a cotton under stress
In this paper the results of the content of components of the oxidant and activity of the antioxidant systems in cotton plants under stress are presents. It is shown that when leaves are removed, the level of malondialdehyde (MDA) as a product of lipid peroxidation in the remaining leaves of defoliated plants is higher than in the leaves of control plants. It was found that as a result of complete defoliation in the newly formed leaves, increased activity of the antioxidant enzyme superoxide dismutase is observed.
Key words: long steble cotton; defoliation; oxidizing agent; antioxidant; malondialdehyde; superoxide dismutase; oxidative stress.
|Pirmatova D.A., Dodkhoeva M.F., Abdusamatova Z.A., Salieva N.H.|
Perinatal outcomes in women with gestational diabetes mellitus in combination with anemia
The results of the study showed an adverse effect of gestational diabetes mellitus (GDM) on perinatal outcomes, especially in the group of GDM in combination with anemia. So, on fond of GDM in combination with anemia, the birth rate of newborns with a mass <2500 g was 15.8%, and macrosomia - 7.9% of cases. At the same time, the birth of newborns in asphyxia was 26.3%, central nervous system dysfunction - 26.3% and neonatal hypoglycemia - in 26.3% cases, which was significantly higher from those in the comparison group.
Key words: gestational diabetes mellitus; anemia; perinatal outcomes; macrosomia.