scholarly journals Response and Recovery Times of Elastic and Viscoelastic Capsules in Shear Flow

2015 ◽  
Vol 17 (5) ◽  
pp. 1151-1168 ◽  
Author(s):  
John Gounley ◽  
Yan Peng
Keyword(s):  
Shear Flow ◽  
Fluid Viscosity ◽  
Membrane Viscosity ◽  
Recovery Times ◽  
Shear Elasticity ◽  
Response And Recovery ◽  
Membrane Bending ◽  
The Relationship ◽  
Spherical Capsule

AbstractAmid the recent interest in the role of membrane viscosity in the deformation of a fluid-filled capsule, we consider the role of various capsule properties (shear elasticity, membrane bending stiffness and viscosity) in determining the response and recovery times of a spherical capsule in shear flow. These times are determined by fitting exponential functions to results for the Taylor deformation parameter Dxy. We focus on the relationship between the membrane and fluid viscosity ratios, as suggested by Diaz et al, and whether adjustments to the fluid viscosity ratio may be used to approximate the effects of membrane viscosity. Based on its ability to reproduce response and recovery times, our results suggest that such an approach holds promise.

Shape Recovery of Elastic Capsules from Shear Flow Induced Deformation

2014 ◽  
Vol 16 (1) ◽  
pp. 56-74 ◽  
Author(s):  
John Gounley ◽  
Yan Peng
Keyword(s):  
Shear Flow ◽  
Exponential Decay ◽  
Shape Recovery ◽  
Bending Stiffness ◽  
Immersed Boundary ◽  
Fluid Viscosity ◽  
Membrane Viscosity ◽  
Equilibrium Behavior ◽  
Shear Elasticity

AbstractRed blood cells undergo substantial shape changes in vivo. Modeled as a viscoelastic capsule, their deformation and equilibrium behavior has been extensively studied. We consider how 2D capsules recover their shape, after having been deformed to ‘equilibrium’ behavior by shear flow. The fluid-structure interaction is modeled using the multiple-relaxation time lattice Boltzmann (LBM) and immersed boundary (IBM) methods. Characterizing the capsule’s shape recovery with the Taylor deformation parameter, we find that a single exponential decay model suffices to describe the recovery of a circular capsule. However, for biconcave capsules whose equilibrium behaviors are tank-treading and tumbling, we posit a two-part recovery, modeled with a pair of exponential decay functions. We consider how these two recovery modes depend on the capsule’s shear elasticity, membrane viscosity, and bending stiffness, along with the ratio of the viscosity of the fluid inside the capsule to the ambient fluid viscosity. We find that the initial recovery mode for a tank-treading biconcave capsule is dominated by shear elasticity and membrane viscosity. On the other hand, the latter recovery mode for both tumbling and tank-treading capsules, depends clearly on shear elasticity, bending stiffness, and the viscosity ratio.

Role of membrane viscosity in the orientation and deformation of a spherical capsule suspended in shear flow

1985 ◽  
Vol 160 ◽  
pp. 119-135 ◽  
Author(s):  
D. Barthes-Biesel ◽  
H. Sgaier
Keyword(s):  
Relaxation Time ◽  
Shear Flow ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Liquid Droplets ◽  
Regular Perturbation ◽  
Shear Rates ◽  
Freely Suspended ◽  
Spherical Capsule

Red blood cells or artificial vesicles may be conveniently represented by capsules, i.e. liquid droplets surrounded by deformable membranes. The aim of this paper is to assess the importance of viscoelastic properties of the membrane on the motion of a capsule freely suspended in a viscous liquid subjected to shear flow. A regular perturbation solution of the general problem is obtained when the particle is initially spherical and undergoing small deformations. With a purely viscous membrane (infinite relaxation time) the capsule deforms into an ellipsoid and has a continuous flipping motion. When the membrane relaxation time is of the same order as the shear time, the particle reaches a steady ellipsoidal shape which is oriented with respect to streamlines at an angle that varies between 45° and 0°, and decreases with increasing shear rates. Furthermore it is predicted that the deformation reaches a maximum value, which is consistent with experimental observations of red blood cells.

scholarly journals Ekman Boundary Layers and Energy Dissipation in Rotating Drums During Spin-Down Process

1995 ◽  
Vol 2 (2) ◽  
pp. 113-121
Author(s):  
Hiroshi Ohue ◽  
Genshi Kawashima ◽  
Wen-Jei Yang
Keyword(s):  
Boundary Layer ◽  
Energy Dissipation ◽  
Fluid Motion ◽  
Light Sheet ◽  
Fluid Viscosity ◽  
Rotating Drum ◽  
Ekman Boundary Layer ◽  
Entire Flow ◽  
The Relationship

The Laser Doppler Velocimetry (LDV) is employed to investigate energy dissipation during a spin-down process inside a rotating drum. The tracer/light sheet method is applied to observe flow patterns in the entire flow field from which the instantaneous, two-dimensional velocity distribution and the formation and subsequent time wise variation of the Ekman boundary layer are determined. Results are synthesized to find the relationship between the Ekman boundary layer and the redistribution of secondary-flow induced angular momentum. The fluid viscosity, drum size and speed of rotation are varied to determine their effects on both the Ekman boundary layer and energy dissipation during spin-down process. The role of Ekman boundary layer in the reduction of rotating fluid motion is determined. Results from the study may be used to develop a method to achieve uniform mixing in an enclosed vessel.

scholarly journals Conductometric Sensing with Individual InAs Nanowires

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 2994 ◽  
Author(s):  
Valeria Demontis ◽  
Mirko Rocci ◽  
Maurizio Donarelli ◽  
Rishi Maiti ◽  
Valentina Zannier ◽  
...  
Keyword(s):  
Drain Current ◽  
Building Blocks ◽  
Electrical Contacts ◽  
Minor Role ◽  
Ambient Atmosphere ◽  
Recovery Times ◽  
Inas Nanowires ◽  
Response And Recovery ◽  
A Minor

In this work, we isolate individual wurtzite InAs nanowires and fabricate electrical contacts at both ends, exploiting the single nanostructures as building blocks to realize two different architectures of conductometric sensors: (a) the nanowire is drop-casted onto—supported by—a SiO2/Si substrate, and (b) the nanowire is suspended at approximately 250 nm from the substrate. We test the source-drain current upon changes in the concentration of humidity, ethanol, and NO2, using synthetic air as a gas carrier, moving a step forward towards mimicking operational environmental conditions. The supported architecture shows higher response in the mid humidity range (50% relative humidity), with shorter response and recovery times and lower detection limit with respect to the suspended nanowire. These experimental pieces of evidence indicate a minor role of the InAs/SiO2 contact area; hence, there is no need for suspended nanostructures to improve the sensing performance. Moreover, the sensing capability of single InAs nanowires for detection of NO2 and ethanol in the ambient atmosphere is reported and discussed.

scholarly journals Characterization and Comparison of Biodegradable Printed Capacitive Humidity Sensors

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6557
Author(s):  
Emma Wawrzynek ◽  
Carol Baumbauer ◽  
Ana Claudia Arias
Keyword(s):  
Relative Humidity ◽  
Potato Starch ◽  
Thermal Drift ◽  
Humidity Sensors ◽  
Interdigitated Electrode ◽  
Recovery Times ◽  
Environmental Relative Humidity ◽  
Response And Recovery ◽  
Silver Electrodes ◽  
The Relationship

Flexible and biodegradable sensors are advantageous for their versatility in a range of areas from smart packaging to agriculture. In this work, we characterize and compare the performance of interdigitated electrode (IDE) humidity sensors printed on different biodegradable substrates. In these IDE capacitive devices, the substrate acts as the sensing layer. The dielectric constant of the substrate increases as the material absorbs water from the atmosphere. Consequently, the capacitance across the electrodes is a function of environmental relative humidity. Here, the performance of polylactide (PLA), glossy paper, and potato starch as a sensing layer is compared to that of nonbiodegradable polyethylene terephthalate (PET). The capacitance across inkjet-printed silver electrodes is measured in environmental conditions ranging from 15 to 90% relative humidity. The sensitivity, response time, hysteresis, and temperature dependency are compared for the sensors. The relationship between humidity and capacitance across the sensors can be modeled by exponential growth with an R2 value of 0.99, with paper and starch sensors having the highest overall sensitivity. The PET and PLA sensors have response and recovery times under 5 min and limited hysteresis. However, the paper and starch sensors have response and recovery times closer to 20 min, with significant hysteresis around 100%. The PET and starch sensors are temperature independent, while the PLA and paper sensors display thermal drift that increases with temperature.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

Staring Down Death

Crisis ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 212-217 ◽  
Author(s):  
Thomas E. Joiner ◽  
Melanie A. Hom ◽  
Megan L. Rogers ◽  
Carol Chu ◽  
Ian H. Stanley ◽  
...  
Keyword(s):  
Suicide Risk ◽  
Clinical Utility ◽  
Blink Rate ◽  
Specific Task ◽  
Careful Planning ◽  
Eye Blink ◽  
Eye Blinks ◽  
Potential Clinical Utility ◽  
The Relationship

Abstract. Background: Lowered eye blink rate may be a clinically useful indicator of acute, imminent, and severe suicide risk. Diminished eye blink rates are often seen among individuals engaged in heightened concentration on a specific task that requires careful planning and attention. Indeed, overcoming one’s biological instinct for survival through suicide necessitates premeditation and concentration; thus, a diminished eye blink rate may signal imminent suicidality. Aims: This article aims to spur research and clinical inquiry into the role of eye blinks as an indicator of acute suicide risk. Method: Literature relevant to the potential connection between eye blink rate and suicidality was reviewed and synthesized. Results: Anecdotal, cognitive, neurological, and conceptual support for the relationship between decreased blink rate and suicide risk is outlined. Conclusion: Given that eye blinks are a highly observable behavior, the potential clinical utility of using eye blink rate as a marker of suicide risk is immense. Research is warranted to explore the association between eye blink rate and acute suicide risk.

Parenting Behaviors and Anxiety in Young Adults

2015 ◽  
Vol 36 (3) ◽  
pp. 170-176 ◽  
Author(s):  
Erin N. Stevens ◽  
Joseph R. Bardeen ◽  
Kyle W. Murdock
Keyword(s):  
Effortful Control ◽  
Parenting Behaviors ◽  
Protective Role ◽  
Anxiety Symptoms ◽  
Interactive Effects ◽  
Parental Overprotection ◽  
High Control ◽  
Development Of Anxiety ◽  
The Relationship

Parenting behaviors – specifically behaviors characterized by high control, intrusiveness, rejection, and overprotection – and effortful control have each been implicated in the development of anxiety pathology. However, little research has examined the protective role of effortful control in the relation between parenting and anxiety symptoms, specifically among adults. Thus, we sought to explore the unique and interactive effects of parenting and effortful control on anxiety among adults (N = 162). Results suggest that effortful control uniquely contributes to anxiety symptoms above and beyond that of any parenting behavior. Furthermore, effortful control acted as a moderator of the relationship between parental overprotection and anxiety, such that overprotection is associated with anxiety only in individuals with lower levels of effortful control. Implications for potential prevention and intervention efforts which specifically target effortful control are discussed. These findings underscore the importance of considering individual differences in self-regulatory abilities when examining associations between putative early-life risk factors, such as parenting, and anxiety symptoms.

Social Support, Emotional Intelligence, and Posttraumatic Stress Disorder Symptoms

2016 ◽  
Vol 37 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Nicole L. Hofman ◽  
Austin M. Hahn ◽  
Christine K. Tirabassi ◽  
Raluca M. Gaher
Keyword(s):  
Social Support ◽  
Posttraumatic Stress Disorder ◽  
Emotional Intelligence ◽  
Protective Factors ◽  
Posttraumatic Stress ◽  
Stress Disorder ◽  
Traumatic Events ◽  
Ptsd Symptoms ◽  
The Relationship

Abstract. Exposure to traumatic events and the associated risk of developing Posttraumatic stress disorder (PTSD) symptoms is a significant and overlooked concern in the college population. It is important for current research to identify potential protective factors associated with the development and maintenance of PTSD symptoms unique to this population. Emotional intelligence and perceived social support are two identified protective factors that influence the association between exposure to traumatic events and PTSD symptomology. The current study examined the mediating role of social support in the relationship between emotional intelligence and PTSD symptoms. Participants included 443 trauma-exposed university students who completed online questionnaires. The results of this study indicated that social support mediates the relationship between emotional intelligence and reported PTSD symptoms. Thus, emotional intelligence is significantly associated with PTSD symptoms and social support may play an integral role in the relationship between emotional intelligence and PTSD. The current study is the first to investigate the role of social support in the relationship between emotional intelligence and PTSD symptoms. These findings have important treatment and prevention implications with regard to PTSD.

Coping Humor as a Mediator Between Emotional Intelligence and Job Satisfaction

2017 ◽  
Vol 16 (3) ◽  
pp. 155-159 ◽  
Author(s):  
Peizhen Sun ◽  
Jennifer J. Chen ◽  
Hongyan Jiang
Keyword(s):  
Job Satisfaction ◽  
Emotional Intelligence ◽  
Future Research ◽  
Satisfaction Scale ◽  
Primary School Teachers ◽  
Mediating Role ◽  
Regulation Of Emotion ◽  
The Relationship ◽  
Overall Job Satisfaction

Abstract. This study investigated the mediating role of coping humor in the relationship between emotional intelligence (EI) and job satisfaction. Participants were 398 primary school teachers in China, who completed the Wong Law Emotional Intelligence Scale, Coping Humor Scale, and Overall Job Satisfaction Scale. Results showed that coping humor was a significant mediator between EI and job satisfaction. A further examination revealed, however, that coping humor only mediated two sub-dimensions of EI (use of emotion and regulation of emotion) and job satisfaction. Implications for future research and limitations of the study are discussed.

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