shear field
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2022 ◽  
Author(s):  
Aisling Field ◽  
Brijesh Tiwari ◽  
James F Curtin ◽  
Julie Rose Mae Mondala ◽  
Janith Wanigasekara

Ultrasound is a sound wave with frequencies ranging between 20 kHz and 20 MHz. Ultrasound is able to temporarily and repeatedly open the BBB safely and enhance chemotherapeutic delivery without adverse effects.(Deprez et al., 2021). This novel technique in drug delivery benefits from the powerful ability of ultrasound to produce cavitation activity. Cavitation is the generation and activity of gas-filled bubbles in a medium exposed to ultrasound. As the pressure wave passes through the media, gas bubbles expand at low pressure and contract at high pressure. This leads to oscillation which produces a circulating fluid flow known as microstreaming around the bubble with velocities and shear rates proportional to the amplitude of the oscillation. At high amplitudes the associated shear forces can cut open liposomes (Wanigasekara et al., 2021; Deprez et al., 2021). Vesicles denser than the surrounding liquid are drawn into the shear field surrounding an oscillating bubble. If the shear stress is greater than the strength of the vesicle, it will burst and spill its contents. In a liposome, the vesicle will reform, often at a smaller size than before meeting the shear field. Hence, some interior liquid must be released during the break down. (Pitt et al., 2004) This protocol describes the use of an ultrasound probe to trigger the release of liposomes in glioblastoma cells. This method uses an ultrasound device which is set to the following parameters: Time = 3 min, Pulse = 59 /01, Amplitude = 20%. The ultrasound technique is an easy and reliable technique making it useful in the study of a variety of areas such as oncology. When applied to an ultrasonic transducer, the Pulser part of the instrument generates short, large amplitude electric pulses of controlled energy, which are transformed into short ultrasonic pulses. The VCX 750 is the ultrasonic liquid processor used for this experiment. It is powerful and versatile and can process a wide range of sample types and volumes for many different applications.


2021 ◽  
Vol 22 (24) ◽  
pp. 13208
Author(s):  
Anna Rył ◽  
Piotr Owczarz

Polysaccharide matrices formed via thermoinduced sol–gel phase transition are promising systems used as drug carriers and minimally invasiveness scaffolds in tissue engineering. The strong shear field generated during injection may lead to changes in the conformation of polymer molecules and, consequently, affect the gelation conditions that have not been studied so far. Chitosan (CS) and hydroxypropyl cellulose (HPC) sols were injected through injection needles (14 G–25 G) or sheared directly in the rheometer measuring system. Then the sol–gel phase transition conditions were determined at 37 °C using rheometric, turbidimetric, and rheo-optical techniques. It was found that the use of low, respecting injection, shear rates accelerate the gelation, its increase extends the gelation time; applying the highest shear rates may significantly slow down (HPC) or accelerate gelation (CS) depending on thixotropic properties. From a practical point of view, the conducted research indicates that the use of thin needles without preliminary tests may lead to an extension of the gelation time and consequently the spilling of the polymeric carrier before gelation. Finally, an interpretation of the influence of an intensive shear field on the conformation of the molecules on a molecular scale was proposed.


2021 ◽  
pp. 708-713
Author(s):  
Ya Nan Ye ◽  
Md Anamul Haque ◽  
Akane Inoue ◽  
Yoshinori Katsuyama ◽  
Takayuki Kurokawa ◽  
...  
Keyword(s):  

Author(s):  
Christian Mittelstedt
Keyword(s):  

GEODYNAMICS ◽  
2020 ◽  
Vol 2(29)2020 (2(29)) ◽  
pp. 66-78
Author(s):  
K. Bezruchko ◽  
◽  
N. Diachenko ◽  

Purpose. The purpose of the paper is the reconstruction of the geodynamic development of the shear dislocation zone (shear stress fields) of the Krasnoarmiiska monocline (KM) of Donbas (Eastern Ukraine) and determining the relationships of their impact on the emergence of gas-dynamic phenomena (GDP) in coal sediments. Methodology. Methods of digital geological cartography, mining-geometric simulation, geological-structural analysis, and structural-geomorphological reconstruction are used for the analysis of structural-geological information. A complex of methods for statistical processing of data on the tectonic disturbance is used – estimation of the frequency of azimuth orientations by the roses-diagram method. Techniques of morphotectonic analysis of the coal bed (a mathematical technique for identifying the gradient structures) are applied. Results. A tectonic model of formation of pull-aparts in the mode of transtension on the territory of KM (on the example of “Dobropilska” mine) is proposed, which results in manifestations of GDP (in particular “wet blowers”) in the form of a small kettle of subsidence in zones of en echelon overlapping of shears. The latter ones are formed under the action of the shear field of tectonic stresses (the axis of space shortening is (σ1) due to the horizontal shear is oriented in azimuth 160-170° (340-350°), the axis of elongation is (σ3) – 70-80° (250-260°). At this, the combination of fringing Y and T faultings in the conditions of transtension, most likely, provides gas permeability and water permeability of the zone. Structure-kinematic relationships of formation and development of shear dislocations of KM at Donbas are researched. Originality. The structural-kinematic relationships in the formation and development of shear dislocations of the Krasnoarmiiskyi district of Donbas and their impact on the formation of GDP zones were studied firstly. They based on the developed digital model of the actual tectonic disturbance of the rock massif on the example of the mining allotments group of KM. It is established for the first time: a) subparallel disjunctives of the NE orientation (15-30°), regardless of morphology, are as the boundaries of parallelogram-like blocks, forming either scaly packets or packets of fault scarps (depending on the morphology of the faultings), limited in the strike by the fault planes of N-NE and SW fall; in the case of scaly packets in the orientation of the fall of the fault plane it is dominated by the E-SE direction, the faultings limiting the fault scarps are characterized by the opposite WN direction of the fall; b) faultings of SE orientation are morphologically represented by shear-thrusts, and with depth change not only the angle of incidence from 35° to 85°, but also the azimuth of strike (from 20-25° to 50°), forming a fanlike feathering of the main faulting in the plan; c) faultings of different morphology are represented not by a single fault plane, but by a series of disturbances on all stratigraphic horizons, which form a zone of faulting formation – a vertical "tectonic strip"; d) in the SE part of the mine "Pioner" a duplex of compression (transpression mode) was found, it is expressed by a folded system (F), up to 287 m wide and fragments of sloping, changing the strike of the Novoiverskyi thrusts; e) the zone of tension duplexes located in the chain, which have a characteristic broken-step configuration at the "Dobropilska" mine, to which “wet blowers” are connected with, develops due to local strike (transtension); f) paragenesis of deformations in the study area corresponds to the shear field of tectonic stresses with north-northwest direction of compression and east-northeast tension, in which fault-shear displacement occurs along with the disjunctive breaks. Practical significance. The established relationships of the impact of shear tectonics on the formation of GDP in coal beds are important both by clarifying the mechanism of tectonogenesis and the nature of pull-aparts formation (en echelon zones of tension), and by the possibility of using additional prognostic criteria for searching for accumulations of free methane and its sudden manifestations (GDP) in coal beds. The application of knowledge of these relationships at mining enterprises will allow reducing the costs for the struggle against dangerous GDP manifestations and predicting them reliably.


2020 ◽  
Vol 38 (12) ◽  
pp. 1426-1434
Author(s):  
Yan-Long Luo ◽  
Xiao-Hui Duan ◽  
Bin Li ◽  
Xian-Ling Chen ◽  
Yang-Yang Gao ◽  
...  

Author(s):  
Shigehiro Hashimoto

Abstract The experimental methodology has been designed for evaluation of the cyclic deformation of an erythrocyte in the pulsatile shear field in vitro. To observe the deformation of the suspended erythrocytes in the Couette type of the shear flow, a rheoscope system has been manufactured. The system consists of a pair of counter-rotating parallel disks and an inverted phase-contrast microscope. The human erythrocytes were suspended in the dextran aqueous solution of high viscosity. The rotating speed varies sinusoidally to make the pulsatile shear field. The deformation of each erythrocyte was measured at the video image of the rheoscope. The experimental results show that the system is available to measure the following behavior of an erythrocyte. The ellipsoidal shape of each erythrocyte varies cyclically to follow the pulsatile cyclic shear field. The delay of deformation phase of each erythrocyte in the cycle is related to the frequency of the cyclic variation of the shear field. The delay is also related to deformability of the erythrocyte.


Polymer ◽  
2020 ◽  
Vol 201 ◽  
pp. 122610
Author(s):  
Yingxiong Wang ◽  
Minjing Liu ◽  
Jin Chen ◽  
Jiaxu Luo ◽  
Jie Min ◽  
...  
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