Fine Chemical Technologies (E-Journal) / Тонкие химические технологии
Not a member yet
1367 research outputs found
Sort by
УСТАНОВЛЕНИЕ ИЗОМЕРНОГО СОСТАВА ИНСЕКТИЦИДНОЙ СУБСТАНЦИИ ЦИПЕРМЕТРИН МЕТОДОМ ОБРАЩЕННО-ФАЗОВОЙ ВЭЖХ
Get PDFThe determination of cypermethrin, one of the most sought pyrethroid insecticides having a wide range of activities, by isocratic RP-HPLC is considered. The analysis of substances (technical products) with different content of both the geometrical (cis-, trans-) and optical (zetacypermethrin and alfacypermethrin) isomers of cypermethrin was carried out. Information about the content of the most active forms of cis- allows evaluating the effectiveness of the biological substance based only on RP-HPLC data, which in turn can be a decisive factor in the of the substance assessment supplier / manufacturer or ready commercial products. The optimum concentration range for determining the geometric isomers of cypermethrin in the working solution is from 0.2 to 1.0 mg/ml. The substance detection limit in working solutions/washings is 0.005 mg/ml.Рассмотрено определение циперметрина методом обращенно-фазовой ОФ ВЭЖХ в изократическом режиме. Проведен анализ субстанций (технических продуктов) с различным содержанием как геометрических (цис-, транс-), так и оптических (зета-циперметрин и альфа-циперметрин) изомеров циперметрина. Информация о содержании наиболее активных цис-форм дает возможность оценить биологическую эффективность субстанций только на основании данных ОФ ВЭЖХ, что, в свою очередь, может являться решающим фактором в процедуре оценки поставщика/производителя субстанции или готовых коммерческих средств. Оптимальный диапазон концентраций определения геометрических изомеров циперметрина в рабочих растворах составляет от 0.2 до 1.0 мг/мл. Предел определения субстанции в рабочих растворах/смывах составляет 0.005 мг/мл
ПОКРЫТИЕ НА ОСНОВЕ СШИТОГО ПОЛИДИМЕТИЛСИЛОКСАНА И НАНОЧАСТИЦ РАЗЛИЧНОЙ МОРФОЛОГИИ ДЛЯ ПРИДАНИЯ ТКАНЯМ СУПЕРГИДРОФОБНЫХ СВОЙСТВ
Get PDFA composition and method for applying a superhydrophobic composite coating for fabrics based on chemically crosslinked polydimethylsiloxane (PDMS), silica nanoparticles (SiO2 NP), composite nanoparticles with “polystyrene core/silica shell structure” and a fluoroalkylsilane (FAS) were proposed. It is shown that the degree of hydrophobicity and durability of the composition are the functions of NP, PDMS and FAS concentration and their ratios. The optimal concentrations of the components for the formation of a coating with a maximum degree of hydrophobicity (water static and sliding contact angle ≈ 170° and 2°, respectively) were determined. It is established that the developed composition is characterized by prolonged wear resistance to various types of abrasive action, heat treatment, exposure to acids and bases. It was experimentally determined that the observed effects are a consequence of the complex influence of all the constituents of the composition.В работе предложены состав и метод нанесения супергидрофобного композиционного покрытия для тканей на основе химически сшитого полидиметилсилоксана (ПДМС), наночастиц кремнезема (НЧ SiO2), наночастиц со структурой «полистирольное ядро/SiO2-оболочка» и фторалкилсилана (ФАС). Определены оптимальные концентрации компонентов, позволяющие получить покрытие с максимальной степенью гидрофобности (170°). Установлено, что разработанная композиция характеризуется пролонгированной износоустойчивостью к различным видам абразивного воздействия, термо-обработке, воздействию кислот и оснований. Показано, что наблюдаемые эффекты являются следствием комплексного влияния всех составляющих композиции
СВЕРХБЫСТРАЯ ПРОСВЕЧИВАЮЩАЯ ЭЛЕКТРОННАЯ МИКРОСКОПИЯ
Get PDFUltrafast laser spectral and electron diffraction methods complement each other and open up new possibilities in chemistry and physics to light up atomic and molecular motions involved in the primary processes governing structural transitions. Since the 1980s, scientific laboratories in the world have begun to develop a new field of research aimed at this goal. “Atomic-molecular movies” will allow visualizing coherent dynamics of nuclei in molecules and fast processes in chemical reactions in real time. Modern femtosecond and picosecond laser sources have made it possible to significantly change the traditional approaches using continuous electron beams, to create ultrabright pulsed photoelectron sources, to catch ultrafast processes in the matter initiated by ultrashort laser pulses and to achieve high spatio-temporal resolution in research. There are several research laboratories all over the world experimenting or planning to experiment with ultrafast electron diffraction and possessing electron microscopes adapted to operate with ultrashort electron beams. It should be emphasized that creating a new-generation electron microscope is of crucial importance, because successful realization of this project demonstrates the potential of leading national research centers and their ability to work at the forefront of modern science
ФИТОПРЕПАРАТЫ ДЛЯ ЛЕЧЕНИЯ И ПРОФИЛАКТИКИ УРАТНОГО НЕФРОЛИТИАЗА
Get PDFThe composition, structure and specific features of urate calculi are discussed in the article. It was shown that they consist of 95% of uric acid and its salts on an average by the X-ray phase and energy dispersive analysis of a number of samples extracted from the urinary tract of 24 urological patients. The mechanism of formation of urate stones is considered. It is noted that urate stones are formed at a urine under pH below 5.5. The factors reducing the development of urinary urolythiasis and uraturia are indicated. The drugs commonly used for the treatment and prevention of urate nephrolithiasis are listed. The role of phytotherapy is underlined in the treatment of urolithiasis in general and urate nephrolithiasis in particular. It is concluded that the composition of plant compositions should include natural compounds of the alkaloid class. The most promising compositions of medicinal plants were determined, and the effect of herbal extracts of various compositions on the pH of the solution and the loss of stone mas
СИНТЕЗ СХЕМ РЕКТИФИКАЦИИ СО СВЯЗАННЫМИ ТЕПЛОВЫМИ И МАТЕРИАЛЬНЫМИ ПОТОКАМИ
Get PDFApproaching a hypothetical thermodynamically reversible process is one of the main directions of energy saving in distillation. In practice, this is achieved by the use of systems with coupled thermal and material flows (STMP). Such systems have long been used in the separation of zeotropic mixtures. As follows from the analysis of literature data, they save energy costs by up to 30%. Recently, it has been revealed that the use of such systems is possible, expedient and energetically advantageous for separating the close-boiling and azeotropic mixtures by extractive distillation (ED). The article considers the main approaches to the synthesis of distillation schemes, including systems with STMP: 1) a method based on the construction of a "superstructure"; 2) a method based on the concept of thermodynamically equivalent configurations; 3) an evolutionary algorithm; 4) a method based on the transformation of distillation scheme graphs. As the analysis of the literature has shown, the first three methods are sufficiently well developed only for the synthesis of distillation schemes with STMP to separate zeotropic mixtures. There are a relatively small number of publications that consider the generation of ED schemes with STMP based on the concept of thermodynamically equivalent configurations for distillation of specific binary mixtures. The only current system approach to the synthesis of ED schemes with coupled thermal and material flows for multicomponent mixtures is the method of graphs (algorithm 4). At present, the first step has been taken to implement it in the form of a computer program. Thus, the article presents the current state of the problem of synthesizing highly effective, energy-saving distillation technologies, including extractive distillation, based on the analysis of publications over the past 20-25 years
ВЛИЯНИЕ ПРИРОДЫ ЭМУЛЬГАТОРА НА ДИСПЕРСНОСТЬ И УСТОЙЧИВОСТЬ ИСКУССТВЕННЫХ ЛАТЕКСОВ
Get PDFIn this paper, we consider methods for producing artificial latexes based on butadiene-styrene thermoplastic elastomer in the presence of cationic surfactants, as well as their mixtures with nonionic and silicone surfactants. The obtained results are compared for the particle size distribution, and conclusions are drawn about the stability of the polymer suspension. The size of particles of polymer suspensions was determined by the method of photon correlation spectroscopy (dynamic light scattering) using a laser particle analyzer. This method allows us to consider the properties of the resulting polymer suspensions and directly draw conclusions about the effect of nature and the concentration of surface active substances on the stability of the resulting latexes. It can be assumed that in this case, structural- mechanical and electrostatic barriers form in the surface layers of the particles. The combined action of these barriers has made it possible to obtain stable polymer emulsions. Thus, it can be concluded that the used surfactant mixtures make it possible to increase the stability of artificial latexes in the stages of emulsification and distillation
К ВОПРОСУ О ПРИЧИНАХ ТОПЛИВНОГО КРИЗИСА В РОССИЙСКОЙ ИМПЕРИИ В НАЧАЛЕ ХХ ВЕКА
Get PDFThe study of problems related to the modernization of the oil industry at the end of the 19th - beginning of the 20th centuries allows asserting that the rapid technical re-equipment of oil refineries was due to the targeted state scientific and technical policy that was being implemented at that time, as well as to the highly effective system of privileges (patents) and mass promotion of technical knowledge and achievements. Besides, the role of entrepreneurs that supported individual inventors and research companies providing "brain gain" and investment in Russia was also significant. This contributed to the rapid introduction of technical innovations in production. Thus, the transition to extensive use of oil as industrial fuel contributed to a more intensive development of the factory industry. Modernization of the oil industry became a powerful incentive and, at the same time, a part of Russian industrialization. One of the most successful and quickly implemented innovations that were at the same time crucial for the changing nature of the Russian energy sector and the economy in general was the invention of "Nobel burner". It seemed that this solved the problem of oil residues. However, it proved to be extremely uneconomical to burn large amounts of oil fuel under the boilers of steam engines. Thus, "oil" energetics formed. The "oil imbalance" resulted in the suppression of the coal industry of the country. At the same time identifying the causes of the fuel crisis as one of the most important factors that led to the collapse of the Russian Empire allowed us to formulate a conclusion that the decline in oil production and increased demand for fuel oil in the First World War by the military and metallurgical industries, railways, the shortage of fuel and rising prices led to the disorganization of the whole economy, disruptions in the supply of food, raw materials and weapons
ВЫБОР ЯДЕР РЕЛАКСАЦИИ ПРИ ОПИСАНИИ МЕХАНИЧЕСКИХ ХАРАКТЕРИСТИК ВЫСОКОТЕМПЕРАТУРНОЙ ОБЛАСТИ ФОНА ДИССИПАТИВНЫХ ПОТЕРЬ НА СПЕКТРЕ ВНУТРЕННЕГО ТРЕНИЯ
Get PDFThe analysis of experimental internal friction spectrum tgδ - f(T) shows that monocrystalline metallic materials possess the simplest spectrum. For those materials, dissipation of a part of the energy of external power impact exists in a form of internal friction background. The background increases slightly and monotonously at homologous temperatures θ < 0.2 ÷ 0.4, and it increases exponentially at θ ˃ 0.4. Taking into consideration the fact that monocrystalline systems may contain defects in the form of disturbance, and the concentration of point defects related to implantation atoms is minimal, one can suppose that this monocrystalline system consists of one aggregate subsystem having flat defects. Different analytical functions, which are often used in describing the inelasticity phenomenon, were studied as relaxation cores for describing the inelastic response of such subsystem in the area of increasing relaxation background of dissipative loss. It is shown that Rabotnov’s, Rzhanitsin’s and Havriliak-Negami’s cores don’t satisfy the asymptotic conditions for the convergence of series with positive values of incoming characteristics. In this case they cannot be used as relaxation functions describing the response of the aggregative subsystem in the temperature range which is higher than homologous temperature 0.4. Description of the viscoelastic response of the high-temperature background internal friction and, accordingly, of the temperature-frequency change of shear modulus is possible only when using Maxwell’s or Kolrausсh’s function which transforms into Maxwell’s function only at a single value of fractionality parameter
ОПРЕДЕЛЕНИЕ МАРГАНЦА(II) МЕТОДОМ СПЕКТРОСКОПИИ ДИФФУЗНОГО ОТРАЖЕНИЯ
Get PDFResults of testing a prototype light-emitting diod miniphotometer for rapid and sensitive elements determination both in laboratory and in field conditions are presented. The new photometer consists of two devices providing measurements of absorbance and diffuse reflectance, having a joint system of data management, registration and presentation of the results. The measurements of absorbance were registered in the visible spectrum. The explored reaction of Mn(II) with 1-(2-pyridylazo)-2-naphthol and the new reaction with 2-(2-quinolinazo)-5-diethylaminophenol were used to verify the device’s metrological parameters. Spectra obtained by means of the proposed photometer were compared to those for commercial photometers. A computer algorithm considering the difference in light-emitting intensity between diods was developed. The possibility of determination down to 1 mkg/ml metal ions in liquid samples was shown
КОЛИЧЕСТВЕННОE ОПРЕДЕЛЕНИЕ ХОРИОНИЧЕСКОГО ГОНАДОТРОПИНА В ЦЕЛЯХ АНТИДОПИНГОВОГО КОНТРОЛЯ
Get PDFThe article presents the results of the first stage of development of a new quantitative method for human chorionic gonadotropin (hCG) determination by means of ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) to uncover doping abuse by athletes. The identified tryptic peptides correspond to the most abundant hCG isoforms: the α- and β-subunits, the nicked and β-core fragment of the hormone. Identification and sequencing of specific fragments were performed with the use of nanoLC-MS/MS. A high resolution / high accuracy hybrid mass-spectrometer was applied. Optimization of mass-spectrometric determination of selected specific peptides was accomplished by UPLC-MS/MS. Quantitative evaluation of hCG using specific fragments determination by UPLC-MS/MS allows to detect corresponding hCG isoforms. This significantly increases the method specificity and decreases the probability of false-positive results