scholarly journals THEORETICAL SUBSTANTIATION OF THE PHYSICAL MECHANISM OF ULTRASONIC CAVITATION DESTRUCTION OF MACROMOLECULES

Author(s):  
Р.Н. Голых ◽  
В.Н. Хмелёв ◽  
В.Д. Минаков ◽  
И.А. Маняхин ◽  
Д.А. Ильченко

Многообещающее направление исследований, которое потенциально может служить базой для создания эффективной технологии управления свойствами полимеров – воздействие механическими колебательными возмущениями на высокомолекулярную среду. В реальных неотверждённых полимерах механические колебательные возмущения, как правило, представляют собой кавитационно-акустическое воздействие, т.е. линейные синусоидальные колебания, создаваемые в среде, инициируют вторичное явление – кавитационные пузырьки. Пузырьки при кавитационно-акустическом воздействии периодически расширяются и схлопываются, формируя микроударные волны. Таким образом, механические колебательные возмущения имеют две составляющие – линейная синусоидальная и нелинейная ударно-волновая. Основное воздействие на структуру полимеров оказывает ударно-волновая составляющая. Для реализации данного процесса с максимальной энергетической эффективностью необходимо выявить оптимальные режимы воздействия. Для выявления оптимальных режимов воздействия в статье теоретически обоснован физический механизм разрушения макромолекул, основанный на их соударении со скоростью, превышающей критическую за счёт формирования экстремальных условий по температуре и давлению в окрестности схлопывающегося кавитационного пузырька. A promising area of research that can potentially serve as a basis for creating an effective technology for controlling the properties of polymers is the effect of mechanical oscillatory disturbances on a high–molecular medium. In real uncured polymers, mechanical oscillatory disturbances, as a rule, represent a cavitation-acoustic effect, i.e. linear sinusoidal vibrations created in the medium initiate a secondary phenomenon - cavitation bubbles. Bubbles under cavitation-acoustic action periodically expand and collapse, forming micro-shock waves. Thus, mechanical oscillatory disturbances have two components – linear sinusoidal and nonlinear shock wave. The main effect on the structure of polymers has a shock-wave component. To implement this process with maximum energy efficiency, it is necessary to identify optimal exposure modes. In order to identify optimal exposure modes, the article theoretically substantiates the physical mechanism of destruction of macromolecules based on their collision with a velocity exceeding the critical one due to the formation of extreme conditions for temperature and pressure in the vicinity of a collapsing cavitation bubble.

2021 ◽  
Vol 2094 (2) ◽  
pp. 022068
Author(s):  
Roman N Golykh

Abstract The known preliminary experimental results of ultrasonic dispersing of suspension were presented and analyzed. The need for determination optimum modes providing maximum energy efficiency of ultrasonic wet dispersing is justified. The physical mechanism and the theoretical model of ultrasonic dispersing were proposed. The model allows to calculate fraction composition of dispersed particles and to evaluate, that the maximum of energy efficiency exists at fixed intensity for different materials of solid particles.


2021 ◽  
Vol 26 (2) ◽  
pp. 33-39
Author(s):  
V.A. Bocharov ◽  
V.V. Bocharova ◽  
M.M. Lebediuk ◽  
A.A.S. Sarayreh ◽  
L.V. Kuts

According to the decisions of international scientific forums, the problem of phenomenon of rosacea (acne rosacea), a common dermatosis with numerous unexplained aspects of etiopathogenesis is a promising area of modern medical research. The aim of the study was theoretical substantiation of the essential features of the mechanisms of occurrence, development and clinical manifestations of the first signs of rosacea in women of reproductive age. The use of a systematic analytical methodical approach to assess the data of clinical and laboratory examinations of women with rosacea, conducted in different regions of the world, allowed to establish the originality of such manifestations of dermatosis as the appearance of unexpected rushes to limited areas of the face, accompanied by local redness and local heat areas of the skin differring significantly from similar rushes in other diseases or syndromes (menopause, migraine, etc.). It is established that the peculiarity of the relationship of these clinical characteristics (from English: rush, ruddy, redness, rosacea, reproductive age of women, reaction) allows to indicate the first signs of dermatosis as a phenomenon inherent in this disease Rush-Ruddy-Rosacea-Reproduce-Reaction (abbreviated – «5-R»), the key pathophysiological target of which (as well as the disease as a whole) is a disorder of a set of hierarchically dependent mechanisms of the evolutionarily determined motivational need to ensure reproductive function in women (both at the cellular level and extracellular structures of the ovaries, and at different levels of subcortical formations and centers of the cortex of the cerebral hemispheres). The phenomenon of rosacea rush is closely related to other phenomena of this dermatosis – hypersensitivity of bradykinin receptors, actinic elastosis, development of post erythematous telangiectasia. The prospect of further research on the problem of rosacea is to study the relationship of disorders in the functional systems of molecules of signaling compounds of different classes (hormones, eicosanoids, neuropeptides, kinins, cytokines and others) in the pathogenesis of the disease.


2019 ◽  
pp. 285-290
Author(s):  
Elena Olegovna Bobkova ◽  
Nataliya Garrievna Kostukevich ◽  
Дмитрий Николаевич Ведерников

The article describes the option of intensification extraction process from the birch inner bark. The influence of acoustic action (tensile-pulse modulation) on an increase in the yield of extractive substances on an aqueous solution of alkali (1% NaOH) is discussed. The extraction results were evaluated by the solid residue, the optical density of the solution, and the content of tannins. The yield of extractive substances is increased in 1.5 time with the help of  a  certain generator signal (meander) with  a  certain  frequency (in the range of 170–190 kHz) and amplitude (2.7–2.9 V). The acoustic effect makes it possible to increase the yield of extractive substances by 17% if compared with the yield with mechanical stirring. The purity of tannin can be improved by adding ethyl alcohol to the extractant. The effect of background regulation with signal power less than 1.5 mW, exceeds the effect of mechanical mixing.  A meander has the greatest effect in a series of electromagnetic signals: a meander, a sine, a triangle, a rectangle. The extraction time is determined. All counterparts taken into consideration the effect occurs. The cause of this phenomenon is examined. An explanation of the results is given.


2010 ◽  
Vol 127 (3) ◽  
pp. 1827-1827 ◽  
Author(s):  
Vera A. Khokhlova ◽  
Olga V. Bessonova ◽  
Mikhail V. Averiyanov ◽  
Joshua E. Soneson ◽  
Robin O. Cleveland

2020 ◽  
Vol 222 (2) ◽  
pp. 735-742
Author(s):  
Michele Dragoni ◽  
Dalila Santoro

SUMMARY Atmospheric shock waves are a common phenomenon in explosive volcanic eruptions. We consider the motion of a spherical shock wave generated by a point source in the strong shock approximation. The shock front corresponds to discontinuities in the gas velocity, density, pressure and temperature, which are calculated as functions of the energy of the explosion. The problem is solved analytically for the distributions of velocity, density, pressure and temperature in the atmosphere as functions of the distance from the source. The motion of the shock wave being supersonic, the solution is valid for a few seconds after the explosion, corresponding to a distance of few kilometres. The acoustic effect of the shock wave, expressed by the peak sound pressure level, is calculated and may reach hundreds of decibels. The pressure waveform that could be recorded in the vicinity of the volcano is calculated and compared with typical waveforms in weak shock conditions. The change in the refractive index of air due to density inhomogeneity is calculated and the conditions under which a condensation cloud is formed behind the shock front are investigated.


2014 ◽  
Vol 3 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Jagdev Singh ◽  
Devendra Kumar ◽  
Sunil Kumar

Abstract In this paper, we present a numerical algorithm based on new homotopy perturbation transform method (HPTM) to solve a time-fractional nonlinear shock wave equation which describes the flow of gases. The fractional derivative is considered in the Caputo sense. The HPTM is combined form of Laplace transform, homotopy perturbation method and He’s polynomials. The nonlinear terms can be easily handled by the use of He’s polynomials. The technique finds the solution without any discretization or restrictive assumptions and avoids the round-off errors. The obtained results are in good agreement with the existing ones in open literature and it is shown that the technique introduced here is robust, efficient, easy to implement and computationally very attractive.


2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040114
Author(s):  
Jia-Lei Yu ◽  
Jing Jin ◽  
Chun Shao ◽  
Miao Zhang ◽  
Tie-Jun Liu

Aiming at accurate decomposition and identification of drag, the drag prediction technology based on the mid/far-field integral method is developed. The method decomposes the far-field drag into entropy drag and induced drag according to its physical mechanism, and introduces an appropriate entropy correction to eliminate the numerical dissipation by analyzing the influence of the trailing integral section position on the entropy drag calculation. Based on the analysis of thermodynamic reversible processes and irreversible processes, the drag is refined into viscous drag, shock wave drag, induced drag and pseudo-drag. The mid-field integral method is used to calculate the separate contribution of viscous drag, shock wave drag and induced drag by calculating the limited integral domain. Numerical results show that the developed method is feasible in accurately reflecting the physical mechanism and predicting the drag ratio. Thus, it provides a reliable tool for drag reduction of large passenger aircraft.


2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040117
Author(s):  
Jin-Duo Chen ◽  
Ai-Ming Shi ◽  
Tong Shen

An entropy decrease phenomenon in the shock wave is studied. The statistical entropy of a unit mass system (UMS) is constructed based on statistical mechanics. Two terms in the microscopic statistical entropy are connected with the macroscopic entropy increment. In order to obtain the number density and velocity distribution function of argon gas, the direct simulation Monto Carlo method is adopted. The physical mechanism for entropy decrease phenomenon in the shock layer is revealed as compression work winning internal energy to produce the heat loss of a UMS.


2021 ◽  
Vol 1 (193) ◽  
pp. 366-371
Author(s):  
Tetiana Hromko ◽  

Expressing the definition of speech in the paradigm of modern Ukrainian dialectological studies is not only a promising area of scientific work in terms of linguistic terminology apparatus, but also the unification of the description and stratigraphy of the study of dialects in Ukraine, generalization of modern scientific knowledge, creation of scientific picture of the world, etc. The general scientific definition of speech as "a functioning linguistic system that may differ from other words by the features of phonetic, grammatical, word-forming and lexical features" has changed somewhat in modern conditions. To express the definition of speech in this plan, according to the author, the following positions should be added: establishment of its origin (taking historical evidence into account); material and spiritual culture taking into account; detection of nuclear and peripheral features of speech; definition of diachronic and synchronous aspects of speech functioning; establishment of traditional differential and relevant features of speech as a linguistic portrait of a settlement; study of the composition of the city as a conglomerate of surrounding dialects, etc. Modern theoretical substantiation of speech implies unification of the differential system of dialect units "idiom - dialect - subdialect". Today, the three-stage system of dialect units in the direction of multilevel is required to be refined. Retrospective and modern studies of speech as a linguistic system show that the process offorming a dialectological base in terms of expressing its definition by virtue of the philosophical laws of stability and variability is not absolutely complete, since in this compulsory component of dialectological research is taken into account as constant information and so constant information that there is in a state of dynamic development and need constant updating with new data, which is seen in the perspective of the methodology of Ukrainian dialectology.


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