The schlieren-diffusion method of determining the turbulence characteristics of a carrier medium in rarefied gas suspension streams

1972 ◽  
Vol 22 (1) ◽  
pp. 45-50
Author(s):  
F. E. Spokoinyi ◽  
Z. R. Gorbis
Keyword(s):  
Rarefied Gas ◽  
Diffusion Method ◽  
Gas Suspension ◽  
Carrier Medium ◽  
Turbulence Characteristics

Kinetic equations for a finely dispersed rarefied gas suspension

1994 ◽  
Vol 29 (2) ◽  
pp. 285-290 ◽  
Author(s):  
M. Yu. Gladkov ◽  
V. Ya. Rudyak
Keyword(s):  
Rarefied Gas ◽  
Kinetic Equations ◽  
Gas Suspension

NUMERICAL SIMULATION OF THE PROPAGATION OF A GAS SHOCK WAVE IN ELECTRICALLY CHARGED AND NEUTRAL GAS SUSPENSION IN A FLAT CHANNEL

2020 ◽  
Vol 2 ◽  
pp. 9-18
Author(s):  
D.A. TUKMAKOV
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Shock Wave ◽  
Solid Particles ◽  
Grid Function ◽  
Heat Conducting ◽  
Gas Suspension ◽  
Carrier Medium ◽  
The Mathematical Model ◽  
Electrically Charged

In this paper, we consider the propagation of a shock wave from a pure gas into a heterogeneous mixture consisting of solid particles suspended in a gas and having an electric charge. The applied mathematical model takes into account the speed and thermal interaction of the carrier and dispersed components of the mixture. The force interaction of particles and gas was described by the Stokes force. The carrier medium was described as a viscous compressible heat–conducting gas. The equations of the mathematical model were solved by the explicit finite–difference method of the second order of accuracy, using the non–linear correction of the grid function. The system of equations of the mathematical model was supplemented by boundary and initial conditions for the desired functions. As a result of numerical simulation, it was found that in an electrically charged gas suspension there is a difference in gas pressure and velocity, “average density” and velocity of the dispersed component, compared with similar values in a gas suspension with an electrically neutral dispersed component. The revealed differences in the dynamics of neutral and electrically charged dusty media can be explained by the fact that the dispersed component of an electrically charged gas suspension is affected by both aerodynamic drag forces and Coulomb forces. Due to interfacial interaction, the dynamics of the carrier medium changes.

scholarly journals NUMERICAL STUDY OF THE INFLUENCE OF DISPERSED INCLUSIONS SIZE ON THE GAS-SUSPENSION SPLITTING PROCESS IN VACUUM

2020 ◽  
pp. 109-119
Author(s):  
Д.А. Тукмаков ◽  
Н.А. Тукмакова
Keyword(s):  
Mathematical Model ◽  
Particle Size ◽  
Inhomogeneous Medium ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Momentum Conservation ◽  
System Of Equations ◽  
Gas Suspension ◽  
Carrier Medium ◽  
The Mathematical Model

В работе моделируется течение однородного газа и неоднородной среды. Целью работы является изучение влияния размера частиц дисперсной компоненты смеси на истечение дисперсной среды в вакуум и выявление отличий от процесса истечения в вакуум однородного газа. Математическая модель, примененная в данной работе, реализует континуальную методологию моделирования течения неоднородной среды, такого рода методика моделирования движения смеси предполагает решение полной гидродинамической системы уравнений движения для каждой из компонент смеси, системы уравнений движения компонент смеси связаны слагаемыми, отвечающими за межфазное силовое и тепловое взаимодействие. Система уравнений включает уравнения непрерывности для плотности несущей среды и средней плотности дисперсной компоненты смеси. Для описания сохранения импульса несущей среды решалось уравнение Навье-Стокса, для дисперсной компоненты смеси также записывалось уравнение сохранения импульса с учетом слагаемых отвечающих за межкомпонентное взаимодействие. Уравнения сохранения энергии компонент смеси решались с учётом межкомпонентного теплообмена. Система уравнений математической модели дополненная краевыми условиями решалась явным конечно-разностным методом второго порядка точности. В результате моделирования выявлены отличия в распределении параметров сплошной среды при распространении в вакуум чистого газа и газовой взвеси частиц. Также выявлено влияние размера частиц дисперсной фазы на процесс истечение несущей среды и дисперсной компоненты газовзвеси в вакуум. The work simulates the flow of a homogeneous gas and an inhomogeneous medium. The aim of the work is to study the influence of the particle size of the dispersed component of the mixture on the outflow of the dispersed medium into vacuum and to identify differences from the process of outflow of a homogeneous gas into the vacuum. The mathematical model used in this work implements a continuous methodology for modeling the flow of an inhomogeneous medium, this kind of methodology for modeling the mixture motion involves solving the complete hydrodynamic system of equations of motion for each of the components of the mixture, the systems of equations of motion of the components of the mixture are connected by terms responsible for the interphase force and thermal interaction. The system of equations includes continuity equations for the density of the carrier medium and the average density of the dispersed component of the mixture. To describe the momentum conservation of the carrier medium, the Navier-Stokes equation was solved for the dispersed component of the mixture, the equation of momentum conservation was also written taking into account the terms responsible for the intercomponent interaction. The energy conservation equations for the mixture components were solved taking into account inter-component heat transfer. The system of equations of the mathematical model supplemented by boundary conditions was solved by an explicit finite-difference method of the second order of accuracy. As a result of the simulation, differences in the distribution of the parameters of a continuous medium during the propagation of pure gas and gas suspension of particles into a vacuum are revealed. The effect of the particle size of the dispersed phase on the process of the outflow of the carrier medium and the dispersed component of the gas suspension into vacuum was also revealed.

Therapeutic efficacy of some extracts of hot pepper fruits (Capsicum annuum) and Sumac seeds (Rhus coriaria) on the growth of some isolated dermatophytes species

2018 ◽  
Vol 1 (3) ◽  
pp. 52-62
Author(s):  
Sara Omran ◽  
Abdulghani Alsamarai ◽  
Firas Razzzaq
Keyword(s):  
Antifungal Activity ◽  
Fungal Infection ◽  
Aqueous Extract ◽  
Plant Extracts ◽  
Therapeutic Efficacy ◽  
Diffusion Method ◽  
Quantitative Detection ◽  
Hot Pepper ◽  
Alcoholic Extract ◽  
Dermatology Clinic

Background: Fungal infections are one of the common skin diseases with difficulty in their treatment approach. The present efficient drugs for fungal infection are limited. Aim: To determine the therapeutic efficacy of plant extracts as alternative antifungal agents. Materials and methods: 100 clinical samples [68 from female and 32 from male] were collected during the period from March to July 2017 from subjects attending Dermatology Clinic in Salah Uldean General Hospital. Fungal infection was diagnosed with using KOH wet preparation. Fungal species identified by using conventional approach. The active ingredients existing in the plant extracts were detected and analyzed through qualitative and quantitative detection technique of chemical compounds using a high performance liquid chromatographic device (HPLC). Agar diffusion method was used to determine antifungal activity of plant extracts. Results: Direct microscopic examination showed that there were (75%) positive samples, while culture shows (67%) positive samples. The isolated dermatophytes belong to Epidermophyoton, Microsporum, and Trichophyton genus. The predominant dermatophytes were T. rubrum (25%) species. The highest frequency of infection was in the age group of 11-20 years. The sensitivity of the tested fungi to the aqueous and alcoholic plant extracts varies. Alcoholic extract of the hot pepper plant was more effective as antifungal than the aqueous extract of the same plant. However, aqueous hot pepper extracts was more effective against T. mentagrophyte than that of alcoholic extract. Additionally, alcoholic Sumac extract shows higher efficacy that aqueous extract. Conclusion: Hot pepper and Sumac extracts show antifungal activity against Microsporum canis, Trichophyton rubrum and T. mentagrophyte.

ANTIMICROBIAL SUSCEPTIBILITY IN CULTURE POSITIVE ENTERIC FEVER

2019 ◽  
Vol 3 (7) ◽  
Author(s):  
Dr. Manish Kulshrestha ◽  
Dr. Anjali Kulshrestha
Keyword(s):  
Bone Marrow ◽  
Blood Culture ◽  
Nalidixic Acid ◽  
Antimicrobial Susceptibility ◽  
Salmonella Enterica ◽  
Enteric Fever ◽  
Multidrug Resistant ◽  
Bone Marrow Culture ◽  
Diffusion Method ◽  
Culture Positive

INTRODUCTION: Enteric fever includes typhoid and paratyphoid fever. Peak incidence is seen in children 5–15 years of age; but in regions where the disease is highly endemic, as in India, children younger than 5 years of age may have the highest infection rates. There are about 22 million new typhoid cases occur each year. Young children in poor, resource limited areas, who make up the majority of the new cases and there is a mortality figures of 215,000 deaths annually. A sharp decline in the rates of complications and mortality due to typhoid fever is observed as a result of introduction of effective antibiotic therapy since 1950s. MDR-ST became endemic in many areas of Asia, including India soon after multidrug-resistant strains of Salmonella enterica serotype typhi (MDR-ST) that were resistant to all the three first-line drugs then in use, namely chloramphenicol, amoxycillin and co-trimoxazole emerged in early 1990s. MATERIAL AND METHODS: Only blood culture or bone marrow culture positive cases were included. The patients with culture isolated enteric fever were included in the study. Antimicrobial susceptibility testing was carried out by disk diffusion method using antibiotic discs. The analysis of the antimicrobial susceptibility was carried out as per CLSI interpretative guidelines. RESULTS: A total of 82 culture positive cases were included in the present study. 80 culture isolates were from blood culture and 2 from the bone marrow culture. Salmonella entericasubspecies enterica serovartyphi (S typhi) was isolated from 67 (81.70%) patients while Salmonella enterica subspecies entericaserovarparatyphi (S paratyphi A) was isolated from 13 (15.85%) cases and 2 (2.44%) were Salmonella enterica subspecies entericaserovarschottmuelleri (S paratyphi B). Of the 82 cases 65(79.3%) isolates were resistant to ciprofloxacin, 17 (20.7%) were resistant to nalidixic acid, one (1.2%) case each was resistant to Cefotaxime and ceftriaxone, 2 (2.4%) were resistant to chloramphenicol, 10 (12.2%) were resistant and to cotrimoxazole 3 (3.7%) were resistant. CONCLUSION: In a culture positive cases 65(79.3%) isolates were resistant to ciprofloxacin and 17 (20.7%) were resistant to nalidixic acid. Multidrug resistant isolates were 65(79.3%).

Fungicidal and Bactericidal Activity of the Alkyl-Substituted Guanidine-Containing Oligomers

2020 ◽  
Vol 82 (6) ◽  
pp. 54-63
Author(s):  
M.Ya. Vortman ◽  
◽  
Yu.B. Pysmenna ◽  
A.I. Chuenko ◽  
D.R. Abdulina ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Trichoderma Viride ◽  
Rhodococcus Erythropolis ◽  
Biological Action ◽  
Molar Ratio ◽  
Diffusion Method ◽  
Klebsiella Pneumonia ◽  
Alkyl Bromides ◽  
Base Form ◽  
Two Stages

Biocides are widely used in medicine and various industries to protect against a number of harmful microorganisms. Organic quaternary ammonium and guanidine-containing compounds, the biological action of which is based on membrane-toxic properties, are used as bactericidal preparations. The aim of this work was to study the bactericidal and fungicidal activities of the synthesized oligomeric alkylsubstituted guanidinium bromides with different radicals -C3H7, -C7H15, -C10H21, against different isolates of heterotrophic bacteria and microscopic fungi. Methods. The synthesis of alkyl-substituted guanidiniumcontaining oligomers was performed in two stages. In the first stage, alkyl-substituted guanidine was obtained by the reaction of guanidine, previously converted by alkali from the salt form to the base form by the base and alkyl bromides (Alk=-C3H7 (propyl), -C7H15 (heptyl), -C10H21 (decyl)) in methanol at a temperature of 50°C and a molar ratio of 1:1. The second carried out the reaction between aromatic oligoepoxide DER-331 and alkyl-substituted guanidine in methanol at a temperature of 50°C for 2–3 hours and a molar ratio of 1:2. Bacteria were grown on meat-peptone agar for 48 hours at a temperature of 28±2°С. Test cultures of micromycetes were cultured on agar beer wort (6°B), incubated for 14 days in a thermostat at a temperature of 28±2°C. Antimicrobial activity of newly synthesized alkyl-substituted guanidinium-containing oligomers was determined by standard disco-diffusion method (method of disks on agar) and fungicidal activity was determined by the method of holes in agar. Results. Oligomeric alkylsubstituted guanidinium bromides with different radicals composed -C3H7, -C7H15, -C10H21- synthesized by the reaction of guanidine alkyl bromides with aromatic oligoepoxydes. It was found that alkyl-substituted guanidinium-containing oligomers at a concentration of 1–3% inhibited the growth of Escherichia coli 475, Pseudomonas aeruginosa 465, Klebsiella pneumonia 479, Pseudomonas pseudoalcaligenes 109, Staphylococcus aureus 451, E. faecalis 422, Rhodococcus erythropolis 102, Bacillus subtilis 138 and most of the studied micromycetes – Aureobasidium pullulans F-41430, Paecilomyces variotii F-41432, Penicillium funiculosum F-41435, Penicillium ochrochloron F-41431, Scopulariopsis brevicaulis F-41434, Trichoderma viride F-41437, Candida albicans F-41441, Aspergillus flavus F-41442, Aspergillus niger F-41448, Penicillium sp. F-41447. Conclusions. Antimicrobial and fungicidal properties significantly depend on the length of the alkyl radical, with increasing of its length the diameter of the zone of bacterial and micromycetes growth retardation increases.10.15407/microbiolj82.06.054

Concerning Stabilization of Heat Transfer of a Gas-Suspension Flow in a Tube

2003 ◽  
Vol 34 (7-8) ◽  
pp. 6 ◽  
Author(s):  
Yu. Ya. Pechenegov ◽  
O. Yu. Pechenegova
Keyword(s):  
Heat Transfer ◽  
Suspension Flow ◽  
Gas Suspension
Sign in / Sign up

Export Citation Format

Share Document