Статьи журнала - Вестник Бурятского государственного университета. Химия. Физика
Все статьи: 156
Activated carbon of Nariin Sukhait high rank bituminous coal
Статья научная
Mongolian high rank coal was used as raw material to prepare activated carbon by physical activation method. The proximate, ultimate, and thermogravimetric analysis (TGA), scanning electron microscopy, surface area, and pore size distribution analysis were used to characterize the surface properties of activated carbons and initial raw coal of Nariin Sukhait. The effect of coal grade on the adsorption properties of the carbons was studied. The carbonization experiment was performed using TGA instrument in argon, at a temperature range of 25-1120°C, with heating rate of 40°C/min in case of carbonization. The mass loss for Nariin Sukhait coal was 30.6%. Activated carbon obtained from Nariin Sukhait coal had highest yield (66.1%), lowest ash content (7.1%), high iodine adsorption (420 mg/g), surface area (402 m2) and highest total pore volume(0.54 ml/g).
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Atomic displacement energy in amorphous compounds
Статья научная
Atomic displacement energy in multicomponent sheet and lead-silicate glasses is calculated from the free activation energy of a viscous flow. The value of Δεe is shown to remain constant in a rather wide range of temperatures in the glass transition region. Satisfactory agreement with calculations of displacement energy using the current formula incorporating the glass transition temperature and the fluctuation volume fraction frozen at this temperature is obtained. The validity of the above formula is confirmed not only at the glass transition temperature but also in the temperature region adjacent to it.
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Cyclic voltammetric study of copper in alkaline solution
Статья научная
The electrochemical reactions of a copper electrode in Na2S solutions were studied using cyclic voltammetry. Purification of working electrodes is determined by X-ray fluorescence. Also a surface examination and morphological studies were applied using scanning electron microscopy and X-ray diffractometer. There are three anodic peaks and, the cathodic branch also contains three peaks. These peaks correspond to the reduction of copper oxide and copper sulfide formed on the anode branch. These peaks may be corresponding successively to the formation of Cu2S, CuS, Cu2O respectively. On the other hand are compounds formed by oxidation of the sulfide of metals using ethylenediaminetetraacetic acid.
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Helical parameters of regular -helices in proteins
Статья научная
The α-helix, 310-helix, π-helix and -helix have been observed in protein structures; they account for 32% of residues, 4%, 0.3% and 0.2%, respectively. However these percentages depend on resolution of solved structures and method for assignment of secondary structures. Culled data set, containing 2901 protein chains with less than 25% sequence identity and 1.6Å resolution (R-value 0.25), was used in this analysis. Secondary structure assignments are performed byDSSP, STRIDE, and SECSTR for π-helices.HELFIT program determines the helical parameters-pitch, residues per turn, radius, and handedness and p = rmsd/(N-1)1/2 for π-helices, where RMSD is the root mean squares deviation from the best fit helix and N is helix length. p-value, estimates helical regularity and all regular π-helices with p 0.10Å were identified. Helical parameters of π-helices are compared with the helical parameters of canonical π-helices and other types of protein helices.
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In sale salus: health provision from salt and saline wetlands in Europe
Статья научная
Among the often cited 14,000 uses of salt, many are related to wellness and health. Its different physical-chemical properties allow many health-related applications of salt itself, brine, mother lay and saline muds. Salt can be used as skin rubs or in blocks, for building halochambers; inhaled as aerosols or even ionised by lamps. Brine can be ingested or used for bathing and exercising in it. Mother lay is usually employed as a basis for cosmetics and skin treatments and muds are traditionally applied directly on the skin for similar ailments. Many of these applications have been known since the Antiquity and are still in use today. Some have disappeared or are only known at local scale, while others are growing in popularity, amid the surge of spa and wellness facilities worldwide. The also increasingly popular natural and alternative treatments have included salt-related healing. In this contribution, we will review among others the traditional uses of brine and salt for health provision; the therapeutic and wellness uses of mother lay and mud as a side activity for traditional salinas, some of which have built ad hoc spa and wellness centres; the now widespread phenomenon of salt caves and mines for halotherapy and the historical spas built around saline lakes, now in disuse. Some treatments can also be applied away from the source of salt, in homes, clinics or urban wellness centres. Examples from many European saline sites, be it mines, solar evaporation salinas, graduation and seething sites, as well as saline lakes, will be drawn. A distinction will be made among those treatments that have been acknowledged by medical science and are applied under professional supervision, as opposed to those that have a weaker scientific support, as well as those that mainly rely on popular belief or superstition.
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Investigation of Shivee-Ovoo coal and it's pyrolysis products
Статья научная
The characterization of the initial of Shivee-Ovoo coal of Mongolia, it’s hard and liquid pyrolysis products was performed. Shivee-Ovoo coal is oxidized brown coal of lignite type with B2 mark. The yields of obtained hard, liquid and gas products of pyrolysis at different heating temperatures was determined. The porosity of raw coal, char of pyrolyzed coal and activated carbon of pyrolyzed char was determined by SEM analysis. The pyrolysis products of coal was investigated by IR-spectroscopy and GC/MS chromatography.
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Investigation on humic acids of Shivee-Ovoo coal
Статья научная
The coal of Shivee-Ovoo deposit was analyzed by proximate and ultimate analysis and have been confirmed that the Shivee-Ovoo coal is a low-rank lignite coal of B2 mark and it is suitable raw material for humic acids. A humic acids with higher yield - 23,22% have been isolated from the Shivee-Ovoo coal. The solubility of humic acids of Shivee-Ovoo coal in ethanol - 43,0% and water - 78,5% was determined and the yield of ethanol soluble fraction (hematimilanic acid) and the yield of water soluble fraction are comparatively higher and these fractions are most important biologically active components in the humic acids with higher penetration ability in soil higher bioawilability by plants. The IR spectra of humic acids of Shivee-Ovoo coal and it’s humic acids show that the organic matter of humic acids consists mainly aliphatic and aromatic compounds with carboxylic (-COOH), carbonyl (>CO), hydroxyl (-OH) and etheric (-O-) groups which are characteristics of highly oxidized organic matter.
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Investigation on pyrolysis of coal from Ulan-Ovoo deposit in Mongolia
Статья научная
The technical characteristics, organic elemental composition of coal and inorganic elemental composition of coal ash of Ulaan-Ovoo deposit have been determined. The thermal stability of coal organic mass has been investigated by thermogravimetric analysis: the mechanisms of the thermal decomposition of the coal organic mass have been explained and the thermal stability indices (T5%, T15% and T25%) has been determined. The coal of Ulaan-Ovoo deposit processed by pyrolysis under vaarious heating temperatures and determined the yields of pyrolysis products such as hard residue, condensed liquid (tar and pyrolysis water) and uncondensed gas products. On the basis of proximate, ultimate, thermogravimetric and FTIR analysis results have been confirmed that the Ulaan-Ovoo coal is a middle rank subbituminous D mark. The liquid tar product of pyrolysis of Ulaan-Ovoo coal was investigated by FTIR and GC/MS analysis. Also the pyrolysis hard residue and activated carbon were characterized.
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Microbiological study of aquatic ecosystem of Mongolia
Статья научная
We have studied microbial ecology of aquatic environments of Mongolia several years randomly, and still our data is not complete till now. Here, we indicated basic microbiological parameters of major lakes and rivers representing Mongolia's aquatic ecosystems. Lakes and rivers water were sampled twice a year, and analyzed for microbiological (total number of bacteria and coliforms, fecal coliforms, enzymatic activity, antibiotic sensitivity and molecular biological analysis) and chemical-physical (ammonia and temperature etc.) parameters. Coliforms were highly correlated with each other and withammonia, temperature and pH, suggesting that the simultaneous determination of all variables currently in use in the evaluation of the microbiological quality of waters is probably redundant, and could be simplified, and that coliform should be tested as a sentinel parameter of the microbiological pollution load of lakes and rivers.
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Neutron diffraction study of magnetic materials
Статья научная
Neutron time-of-flight diffractometry provides an effective and rapidly developing method for current neutron diffraction studies. The article it devoted to specific potentialities of the method for structural studies in material science. Special attention is paid to the application of neutron diffraction method to study some magnetic materials. Use of the method of neutron powder diffraction to study crystal and magnetic structure, microstructure, texture analysis, magnetic domains, quantitative phase analysis, stresses, strains, and elastic constants of materials, and many other problems related to materials science has beed revealed.
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New synthetic procedure for synthesis of dimethyl 1,4-diaminocyclohexane-1,4-dicarboxylate
Статья научная
The third step of the synthesis deriving dimethyl-1,4-diamino cyclohexane-1,4- dicarboxylate (III) proved to be a difficult task due to its old synthetic route with a few major problems including use of very expensive reagent, mainly hydrogen chloride and ammonia gases. The main purpose of this research was to either optimize/improve the esterification reaction in the original synthetic procedure or in this instance to develop an alternative which improves the yield and reaction time.The result of this research is that dimethyl-1,4-diamino cyclohexane-1,4- dicarboxylate (III) was prepared from 1,4-diamino-1,4-cyclohexane dicarboxylic acid (II) by Fischer etherification using sulfuric acid instead of hydrogen chloride. To remove the sulfate anion from compound III the anion exchange resin DOWEX Monosphere 550A was used. The resulting white suspension was dried using the rotary evaporator to obtain white solid (compound III) with a 42% yield. The product was characterized by TLC, melting point, FT-IR and H-NMR.
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![Organic solvents as pyridine and imidazolium based ionic liquid [BMIM]Cl affecting functional groups and paramagnetic properties of low rank Nalaikh coal](/file/thumb/148317779/organic-solvents-as-pyridine-and-imidazolium-based-ionic-liquid-bmim-cl-affecting.png "Organic solvents as pyridine and imidazolium based ionic liquid [BMIM]Cl affecting functional groups and paramagnetic properties of low rank Nalaikh coal")
Статья научная
This work considers experimental results of low rank Nalaikh coal dissolution in organic solvents as pyridine and imidazolium based ionic liquid of [Bmim]Cl. The low rank coal and its treated samples were therefore analyzed by Fourier transformation infrared and electron paramagnetic resonance spectroscopy. Different paramagnetic centers are good resolved in the electron paramagnetic resonance electron paramagnetic resonance spectra of the extraction samples.
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Статья научная
The phase and physicochemical properties diagrams of the quaternary system (Li+, K+//Cl-, SO4 -H2O) at 288.15 K were constructed using the solubilities, densities, and refractive indices measured. In the phase diagrams of the system there are three invariant points, seven univariant isotherm dissolution curves, and five crystallization regions corresponding to3lithium chloride monohydrate (LiCl∙H2O), lithium sulfate monohydrate (Li2SO4∙H2O), potassium chloride (KCl), potassium sulfate (K2SO4), and double salt lithium potassium sulfate (Li2SO4∙K2SO4), where the double salt lithium potassium sulfate (Li2SO4∙K2SO4) is an incongruent double salt. The crystallization area of potassium sulfate (K2SO4) is the largest, and the crystallized zone of lithium chloride monohydrate (LiCl∙H2O) is the smallest. These results indicate that potassium sulfate is easy to saturate and crystallize from solution and that lithium chloride has a high solubility during isothermal evaporation. The solution density and refractive index of the quaternary system change regularly with the increase of K+ concentration.
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Статья научная
Activated carbon supported with silver nanoparticles was synthesized in supercritical water condition at 673 K and 30.0 MPa in a batch reactor. The reaction time was 30 min with concentration of silver acetate solution at 0.02 M. Synthesized activated carbon-Ag particles were characterized by X-ray diffraction, Fourier transformation confirmed infrared spectroscopy and scanning electron microscopy. X-ray diffraction measurement indicated the presence of metallic silver. Fourier transformation infrared spectroscopy traces of primary activated carbon, activated carbon treated in supercritical water condition and synthesized activated carbon-Ag showed slight shift near 1629 cm-1 due to silver bonding to activated carbon via carbonyl and carboxyl groups. There was also observed chain-like structure of activated carbon-Ag with size of around 100 nm when sScanned by electron microscopy.
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Spectroscopic study of gamma-irradiated Mongolian natural quartz
Статья научная
In this work we performed a spectroscopic characterization of natural quartz samples from Mongolia. These materials were examined by X-ray powder diffraction (XRD), UV-visible spectroscopy (UV-vis) and electron paramagnetic resonance (EPR). Samples were used in this study in as-received, gamma- irradiated and heat-treated conditions. The color formation in natural quartz through this procedure is explained based on XRD, EPR, and UV-VIS studies of gamma irradiated and heat-treated samples. Smoky quartz shows absorption bands in the visible region and a strong EPR signal. After heat-treatment it shows absorption bands in the near UV region with extensions into the visible region and a weak EPR signal.
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Статья научная
Graphenenanoribbons, as a typical two-dimensional nanometer material, has shown its unique application potential in electrical characteristics, thermal properties, and thermoelectric properties by virtue of its novel electronic structure. Through studies of graphene’s electrical properties in recent years, progress has been made not only in experimental testing, but also in theoretical calculation. This aspect of graphene reviewed in this paper.
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Статья научная
Fused glasses were prepared from waste window glass and fly ash of the IV thermal power station of Ulaanbaatar city (Mongolia). Raw mixtures for the glass consist of waste glass (30-40 wt.%), fly ash (55-65 wt.%), fluorite (5 wt.%). Cerium (IV) oxide was used (0.5 wt.%) as rare earth oxide additive. Mixtures with and without rare earth oxide addition were melted at 15000C temperature. The influence of cerium (IV) oxide on the crystallization behavior of glass ceramics were investigated by differential thermal analysis-thermogravimetry and x-ray diffraction (XRD) analyses.The differential thermal analysis scan results indicated that the temperature of sharp exothermic peak appearing at 8980C is increasing to 9110C in rare earth oxide containing mixture. XRD analysis showed that the crystalline phases in the glass-ceramic was albite [NaAlSi3O8].
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X-ray diffraction analysis of crystalline and amorphous rare earth (III) (Y, La, Eu) complex
Статья научная
Acylaminocarboxylato-Rare earth complex were prepared by chemical reaction method in aqueous solution. Structure and properties of the complexes were analyzed by X-ray diffraction analysis. It was shown that complex has both crystalline and amorphous states. Сhemical compositions of the rare earth complexes were determined. Comparison of three complexes shows that lanthanum complexes tend to easily crystallize, europium complexes tend to vitrify easily.
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XRD analysis on soot and ash from coal combustion
Статья научная
Products such as soot and ash emitted from coal combustion in heating stove for traditional Mongolian ger and small houses have been analyzed. The amorphous phase in soot and ash is identified by using the method of quantitative analysis based on the Rietveld method. The crystalline phases in soot and ash are mainly formed by graphitic carbon (rhombic, R3 (146), a=2.45Å, c=10.04Å, V=52.47Å3, Z=6)). Soot and ash are composed of crystal structure of elements (S, Ca, Fe, Na, Si, Al, Mg) included in combust coal and chemical compounds (CaSO4, SiO2, Fe2O3, CaSO4∙2(H2O), MgSO4∙6(H2O) formed in combustion process as well as the graphitic carbon. The results are checked by SEM-EDS analysis. By using the Debye-Scherrer equation the average crystallite size of carbon ball giving clearer XRD pattern is estimated. The results of analysis show that the content of amorphous phase in soot is greater than that of ash. Also, the temperature is the key factor formation of crystalline and amorphous phase.
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Анализ суточных вариаций измеренных координат GPS-станции ULAZ программами RTKLIB и Mathlab
Статья научная
Определены статистические характеристики суточных вариаций измеренных координат GPS-станции ULAZ. Проведена первичная обработка суточных данных, сравнение и статистический анализ данных станции ULAZ 2001 и 2017 гг. Показано некоторое различие статистических характеристик между измерениями координат за 16 лет. Выяснено, что программы RTKLIB и MATHLAB удобны при обработке первичных данных, связанных с позиционированием и навигацией с применением ГНСС. Выяснено, что необходима дальнейшая обработка данных, что потребует создания системы обработки больших объемов данных.
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