scholarly journals COMPARISON OF THEORETICAL FOUNDATIONS AND EXPERIMENTAL DATA OF THE REACTION FOR OBTAINING N-METHYL-D-GLUCOSIMINE

2020 ◽  
pp. 16-26
Author(s):  
Степан Петрович Михайлов ◽  
Михаил Геннадьевич Сульман ◽  
Валентин Юрьевич Долуда ◽  
Валентина Геннадьевна Матвеева
Keyword(s):  
Experimental Data ◽  
Comparative Analysis ◽  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Chemical Processes ◽  
Thermodynamic Calculations ◽  
Schiff’S Base ◽  
Energy Equilibrium ◽  
Attainable Yield ◽  
Theoretical Foundations

Представленная статья посвящена сравнительному анализу теоретических основ синтеза N-метилглюкамина (основание Шиффа) и экспериментальных данных. N-метил-D-глюкозимин, это промежуточный продукт получения N-метил-D-глюкозамина, широко используемого в фармацевтике, в качестве балластного вещества или противоиона, улучшающего биодоступность основного лекарственного средства. Проведена оценка кинетических параметров синтеза, рассчитан максимальный достигаемый выход. Применение термодинамических расчетов позволяет оценить влияния условий проведения химических процессов на выход целевых продуктов, а это способствует более глубокому пониманию механизмов протекания химических реакций. В представленной статье приводятся результаты термодинамических расчётов реакции синтеза N-метил-D-глюкозимина методом Ван-Кравлена - Черемнова. Рассчитаны энергия Гиббса, константы равновесия и конверсия глюкозы при единичной активности реагирующих веществ. Показано, что увеличение температуры реакционной массы с 20 до 160°С способствует увеличению конверсии глюкозы с 3 до 32%, в связи с чем можно рекомендовать проведение этой реакции при повышенных температурах. The presented article is devoted to a comparative analysis of the theoretical foundations of the synthesis of N-methylglucamine (Schiff's base) and experimental data. N-methyl-D-glucosimine is an intermediate in the preparation of N-methyl-D-glucosamine, which is widely used in pharmaceuticals, as a ballast or counter-ion to improve the bioavailability of the main drug. The kinetic parameters of the synthesis were estimated, and the maximum attainable yield was calculated. The use of thermodynamic calculations makes it possible to evaluate the influence of the conditions of chemical processes on the yield of target products, and this contributes to a deeper understanding of the mechanisms of chemical reactions. This article presents the results of thermodynamic calculations of the reaction for the synthesis of N-methyl-D-glucosimine by the Van Cravlen - Cheremnov method. The Gibbs energy, equilibrium constants, and glucose conversion were calculated for a single activity of the reacting substances. It was shown that an increase in the temperature of the reaction mixture from 20 to 160 ° C promotes an increase in the conversion of glucose from 3 to 32%, and therefore it is possible to recommend carrying out this reaction at elevated temperatures.

scholarly journals N-Methyl-D-Glucoseimine Synthesis Reaction Thermodynamic Properties Calculation

2020 ◽  
Vol 6 (11) ◽  
pp. 40-46
Author(s):  
S. Mikhailov ◽  
R. Brovko ◽  
S. Mushinskii ◽  
M. Sulman
Keyword(s):  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Thermodynamic Calculations ◽  
Process Conditions ◽  
Reaction Conditions ◽  
Formation Reaction ◽  
Reaction Proceeds ◽  
Energy Equilibrium ◽  
Reversible Formation ◽  
Pharmaceutical Practice

The presented article is devoted to thermodynamic calculations of the N-methyl-D-glucosimine reversible formation reaction, an intermediate product for N-methyl-D-glucosamine synthesis, which is widely used in pharmaceutical practice as a ballast or counterion that improves the bioavailability of the main active substance. N-methyl-D-glucosimine is synthesized as a result of the interaction of D-glucose with methylamine in organic solvents, the reaction is reversible, and the yield of the target product depends entirely on the reaction conditions. The use of thermodynamic calculations makes it possible to evaluate the influence of the chemical process conditions on the yield of target products, which in turn contributes to a deeper understanding of the chemical reactions mechanisms. In chemical equilibrium, direct and reverse reactions proceed at equal rates, while the concentrations of products and reagents remain constant. When the reaction proceeds in a closed system, after a certain time, a state of equilibrium occurs, while the reaction does not proceed with a complete transformation of the reagents. This article presents the results of thermodynamic calculations of the reaction for the synthesis of N-methyl-D-glucosimine by the Van Kravlen – Cheremnov method. The Gibbs energy, equilibrium constants, and D-glucose conversion were calculated as activity function of reacting substances. It was shown that an increase in the temperature of the reaction mixture from 20 to 160 °C promotes an increase in the conversion of D-glucose from 3 to 32%, and therefore it is possible to recommend carrying out this reaction at elevated temperatures.

Kinetic equations of creep and damage for description of materials with non-monotonic dependence of fracture strain on stress

2021 ◽  
Vol 23 (3) ◽  
pp. 139-154
Author(s):  
Inna Banshchikova ◽  
Keyword(s):  
Experimental Data ◽  
Comparative Analysis ◽  
Damage Accumulation ◽  
Elevated Temperatures ◽  
Fracture Strain ◽  
Least Squares Method ◽  
Kinetic Equations ◽  
Steel 12Kh18n10t ◽  
Static Mode ◽  
Creep Curves

Introduction. Reducing the level of damage accumulation during pressure treatment of materials at elevated temperatures in creep and close to superplasticity modes in the manufacture of parts can significantly increase its service life in the cold state. Finding temperature and power conditions leading to a reduction in damage of material during the production process and operation is an important task. The purposes of the work: 1) to show the possibility of using the Sosnin-Gorev creep and damage model for alloys with a non-monotonic dependence of strain at fracture on diagrams with creep curves; 2) to carry out comparative analysis of damage accumulation under conditions of uniaxial tension at constant stress and at constant strain rates for alloy with such a dependence. Research methods. Used scalar damage parameter is equated to the normalized deformation, i.e. to the ratio of the current strain to the fracture strain. To find the coefficients of relations creep and damage, the similarity of the creep curves in the normalized values “normalized strain – normalized time”, i.e. the presence of single normalized curve of damage accumulation is checked. The least squares method is used to approximate the experimental data. Numerical integration methods are used for comparative analysis of deformation modes. Results and discussion. Determination of the parameters of the creep and damage equations by the method of a single normalized curve is carried out on the example of experimental data for steel 12Kh18N10T (12Cr18Ni10Ti) at 850 °C, which has a minimum of fracture strain in diagrams with creep curves. Analysis of the static and kinematic modes of deformation for studied material showed that damage accumulation in both cases is practically the same for stresses close to the stress at which this minimum is reached. If the stresses are lower, then the lower level of damage accumulation will be in the kinematic mode; if the stresses above the minimum value, then the static mode will lead to a lower level of damage accumulation. Application. The obtained results can be useful when choosing rational modes of forming structural elements from alloys with a non-monotonic dependence of the fracture strain on stress, as well as in evaluating it for long-term strength during operation.

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

Dielectric Breakdown in Printed Circuit Boards at Elevated Temperatures

1996 ◽  
Author(s):  
P. Singh ◽  
G.T. Galyon ◽  
J. Obrzut ◽  
W.A. Alpaugh
Keyword(s):  
Experimental Data ◽  
Thermal Degradation ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Elevated Temperatures ◽  
Dielectric Breakdown ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Data Matching

Abstract A time delayed dielectric breakdown in printed circuit boards, operating at temperatures below the epoxy resin insulation thermo-electrical limits, is reported. The safe temperature-voltage operating regime was estimated and related to the glass-rubber transition (To) of printed circuit board dielectric. The TG was measured using DSC and compared with that determined from electrical conductivity of the laminate in the glassy and rubbery state. A failure model was developed and fitted to the experimental data matching a localized thermal degradation of the dielectric and time dependency. The model is based on localized heating of an insulation resistance defect that under certain voltage bias can exceed the TG, thus, initiating thermal degradation of the resin. The model agrees well with the experimental data and indicates that the failure rate and truncation time beyond which the probability of failure becomes insignificant, decreases with increasing glass-rubber transition temperature.

Comparative analysis and verification of engineering methods of shallow cracks effect for fracture toughness prediction for reactor pressure vessels

2020 ◽  
pp. 140-165
Author(s):  
V. I. Kostylev ◽  
B. Z. Margolin
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Comparative Analysis ◽  
Nuclear Reactor ◽  
Probabilistic Approach ◽  
Pressure Vessels ◽  
Local Methods ◽  
European Method ◽  
Shallow Crack ◽  
Reactor Pressure

The main features of shallow cracks fracture are considered, and a brief analysis of methods allowing to predict the temperature dependence of the fracture toughness KJC (T) for specimens with shallow cracks is given. These methods include DA-method, (JQ)-method, (J-T)-method, “local methods” with its multiparameter probabilistic approach, GP method uses power approach, and also two engineering methods – RMSC (Russian Method for Shallow Crack) and EMSC (European Method for Shallow Crack). On the basis of 13 sets of experimental data for national and foreign steels, a detailed verification and comparative analysis of these two engineering methods were carried out on the materials of the VVER and PWR nuclear reactor vessels considering the effect of shallow cracks.

scholarly journals Comparative analysis of methods to determine deflection in steel beams: theoretical analysis, finite element and experimental

2020 ◽  
pp. 32-37
Author(s):  
Gabriela Alor-Saavedra ◽  
Francisco Alejandro Alaffita-Hernández ◽  
Beatris Adriana Escobedo-Trujillo ◽  
Oscar Fernando Silva-Aguilar
Keyword(s):  
Differential Equation ◽  
Experimental Data ◽  
Finite Element ◽  
Comparative Analysis ◽  
Theoretical Analysis ◽  
Comparative Study ◽  
Steel Beams ◽  
Physical Systems ◽  
Theoretical Part ◽  
Made In

This work makes a comparative study of two methods to determine deflection in steel beams: (a) Theoretical and (b) Finite element. For method (a) the solution of the differential equation associated with the modeling of the deflection of a beam is found, while for method (b) a simulation is made in Solidworks. Both methods are compared with experimental data in order to analyze which of the methods presents less uncertainty and show the usefulness of the theoretical part in the modeling of physical systems.

scholarly journals Equilibrium Modeling of Astaxanthin Extraction from Haematococcus pluvialis

2021 ◽  
Vol 21 (3) ◽  
pp. 554
Author(s):  
Putri Restu Dewati ◽  
Rochmadi Rochmadi ◽  
Abdul Rohman ◽  
Avido Yuliestyan ◽  
Arief Budiman
Keyword(s):  
Experimental Data ◽  
High Performance ◽  
Haematococcus Pluvialis ◽  
Equilibrium Constants ◽  
Extraction Methods ◽  
Single Step ◽  
Equilibrium Models ◽  
Extraction Equilibrium ◽  
Assisted Extraction ◽  
Solid Liquid

Astaxanthin is a natural antioxidant, and the highest content of this compound is found in Haematococcus pluvialis microalgae. Microwave-assisted extraction (MAE) is one of the environmentally friendly extraction methods and has many advantages. This study aims to investigate the extraction of astaxanthin through the MAE method using various solvents. Several equilibrium models were proposed to describe this solid-liquid equilibrium. The solid-liquid extraction equilibrium parameters were determined by minimizing the sum of squares of errors (SSE), in which equilibrium constants were needed for scaling up purposes. Previously, the microalgae were pretreated with HCl to soften their cell walls in order to improve the extraction recovery. In this study, dichloromethane, acetone, methanol, and ethanol were used as the solvents for extraction. The astaxanthin concentration was determined by high-performance liquid chromatography (HPLC) and spectrophotometry. Astaxanthin was found to attain equilibrium at 57.42% recovery in a single-step extraction. Thus, several steps were required in sequence to obtain an optimum recovery. The experimental data were fitted to three equilibrium models, namely, Henry, Freundlich, and Langmuir models. The experimental data were well fitted to all the models for the extraction in dichloromethane, methanol, ethanol and acetone, as evident from the almost same SSE value for each model.

scholarly journals Approximate Analytical Models of Shock-Wave Structure at Steady Mach Reflection

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 305
Author(s):  
Mikhail V. Chernyshov ◽  
Karina E. Savelova ◽  
Anna S. Kapralova
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Comparative Analysis ◽  
Analytical Model ◽  
Mach Reflection ◽  
Supersonic Jet ◽  
Wave Structure ◽  
Analytical Models ◽  
Analytical Prediction ◽  
Shock Wave Structure

In this study, we obtain the comparative analysis of methods of quick approximate analytical prediction of Mach shock height in planar steady supersonic flows (for example, in supersonic jet flow and in narrowing channel between two wedges), that are developed since the 1980s and being actively modernized now. A new analytical model based on flow averaging downstream curved Mach shock is proposed, which seems more accurate than preceding models, comparing with numerical and experimental data.

scholarly journals Necessary auxiliary background for efficient use of an existing computer program of non-parametric fitting of nonlinear equations

2009 ◽  
Vol 52 (2) ◽  
pp. 437-448 ◽  
Author(s):  
Emmanuel M. Papamichael ◽  
Leonidas G. Theodorou
Keyword(s):  
Experimental Data ◽  
Computer Program ◽  
Nonlinear Equations ◽  
Significant Contribution ◽  
Chemical Processes ◽  
Programming Support ◽  
Parametric Fitting ◽  
Non Parametric

This work constituted a significant contribution for more efficient use of a valuable computer program of non-parametric fitting of nonlinear multiparametric equations to experimental data. However, prerequisite in this context was the transformation of nonlinear multiparametric equations into linear hyperplane forms before their incorporation within the computer program; this latter was decisive and a matter of proper programming practice. Herein, a series of widely used equations useful in different fields of chemical processes, in biochemistry and/or in biotechnology, along with their suitable transformations as well as the appropriate programming support are being reported.

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