Modeling of Bubble Expansion-Induced Cell Mechanical Profile in Laser-Assisted Cell Direct Writing

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Wei Wang ◽  
Gang Li ◽  
Yong Huang
Keyword(s):  
Cell Damage ◽  
Initial Pressure ◽  
Damage Mechanism ◽  
High Viscosity ◽  
Ejection Velocity ◽  
Direct Writing ◽  
Cell Velocity ◽  
Initial Stage ◽  
Approach Zero ◽  
Pressure Magnitude

Cell damage due to the mechanical impact during laser-assisted cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to numerically investigate the bubble expansion-induced cell mechanical loading profile in laser-assisted cell direct writing. Some conclusions have been drawn as follows. The cell velocity increases initially and then smoothes out gradually with a constant ejection velocity. Both the cell acceleration and pressure can be very high at the beginning period of bubble expansion and then quickly approach zero in an oscillation manner. A high viscosity can lead to an observable velocity increment at the initial stage, but the ejection velocity decreases. The pressure magnitude decreases when the cell-bubble distance is large, and a larger initial pressure induces a larger cell pressure as expected. This study serves as a foundation to further investigate the cell damage mechanism in laser-assisted cell direct writing to improve the effectiveness and efficiency of cell direct writing techniques.

Modeling of Bubble Expansion-Induced Cell Mechanical Profile in Laser-Assisted Cell Direct Writing

2008 ◽  
Author(s):  
Wei Wang ◽  
Gang Li ◽  
Yong Huang
Keyword(s):  
Cell Damage ◽  
Initial Pressure ◽  
Damage Mechanism ◽  
High Viscosity ◽  
Ejection Velocity ◽  
Direct Writing ◽  
Cell Velocity ◽  
Initial Stage ◽  
Very High ◽  
Pressure Magnitude

Cell damage due to the mechanical impact during laser-assisted cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to numerically investigate the bubble expansion-induced cell mechanical loading profile in laser-assisted cell direct writing. Some conclusions have been drawn as follows. The cell velocity oscillates initially and then smoothes out gradually with a constant ejection velocity. Both the cell acceleration and pressure can be very high at the beginning period of bubble expansion and then quickly approaches zero in an oscillation manner. A high viscosity can lead to an observable velocity increment at the initial stage, but the ejection velocity decreases. The pressure magnitude decreases when the distance is large, and a larger initial pressure induces a larger cell pressure as expected. This study serves as a foundation to further investigate the cell damage mechanism in laser-assisted cell direct writing to improve the effectiveness and efficiency of cell direct writing techniques.

scholarly journals Multiple steady states and the form of response functions to antigen in a model for the initiation of T-cell activation

2017 ◽  
Vol 4 (11) ◽  
pp. 170821 ◽  
Author(s):  
Alan D. Rendall ◽  
Eduardo D. Sontag
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Monotone Function ◽  
Cell Receptor ◽  
State Variables ◽  
Damped Oscillations ◽  
A Value ◽  
Initial Stage ◽  
Approach Zero

The aim of this paper is to study the qualitative behaviour predicted by a mathematical model for the initial stage of T-cell activation. The state variables in the model are the concentrations of phosphorylation states of the T-cell receptor (TCR) complex and the phosphatase SHP-1 in the cell. It is shown that these quantities cannot approach zero and that the model possesses more than one positive steady state for certain values of the parameters. It can also exhibit damped oscillations. It is proved that the chemical concentration which represents the degree of activation of the cell, that of the maximally phosphorylated form of the TCR complex, is, in general, a non-monotone function of the activating signal. In particular, there are cases where there is a value of the dissociation constant of the ligand from the receptor which produces a maximal activation of the T cell. This suggests that mechanisms taking place in the first few minutes after activation and included in the model studied in this paper suffice to explain the optimal dissociation time seen in experiments. In this way, the results of certain simulations in the literature have been confirmed rigorously and some important features which had not previously been seen have been discovered.

Modeling of Thermoelastic Stress Wave in Laser-Assisted Cell Direct Writing

2009 ◽  
Author(s):  
Wei Wang ◽  
Yong Huang ◽  
Yafu Lin
Keyword(s):  
Stress Wave ◽  
Cell Damage ◽  
Optical Breakdown ◽  
Thermoelastic Stress ◽  
Laser Pulses ◽  
Stress Wave Propagation ◽  
Direct Write ◽  
Direct Writing ◽  
Coating Materials ◽  
Laser Focal Spot

Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, the cell damage due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when the vaporization or optical breakdown of coating materials is not available. It is found that a bipolar pressure pair has been developed within a finite thin coating medium, locations near the laser focal spot experience higher stresses, and shorter duration laser pulses lead to higher thermoelastic stresses. This study will help understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.

Role of Th17 Cytokines in Liver’s Immune Response during Fatal Yellow Fever:Triggering Cell Damage Mechanism

2021 ◽  
Author(s):  
Marcos Luiz Gaia Carvalho ◽  
Jorge Rodrigues Sousa ◽  
Jeferson Costa Lopes ◽  
Caio Cesar Henriques Mendes ◽  
Fábio Alves Olímpio ◽  
...  
Keyword(s):  
Immune Response ◽  
Cell Damage ◽  
Fatal Outcome ◽  
Immunohistochemical Analysis ◽  
Damage Mechanism ◽  
Cellular Damage ◽  
Hepatic Parenchyma ◽  
Tissue Samples ◽  
Th17 Cytokines ◽  
Th17 Cytokine

Abstract Yellow fever (YF) is an infectious disease whoseevolution and outcome arerelated to the host immune response pattern. We investigated the Th17 cytokine profile in the liver of humans with fatal YF. Liver tissue samples were collected from 26 patients, including 21 YF-positive and five flavivirus-negative patients with preserved hepatic parenchyma architecture who died of other causes. Samples underwent histopathological and immunohistochemical analysis to detect the Th17 profile (ROR-γ, STAT3, IL-6, TGF-β, IL-17,and IL-23). Substantial differences were found in the expression of markers between fatal YF cases and control samples with a predominance of Th17 cytokine markers in the midzonal region of the YF cases, the most affected area in the liver acinus. Histopathological changes in the hepatic parenchyma revealed cellular damage characterised mainly by the presence of inflammatory infiltrate, Councilman bodies (apoptotic cells), micro/macrovesicular steatosis, and lytic and coagulative necrosis.Th17 cytokines play a pivotal role during YF and contribute significantly to triggering the mechanisms of cell damage in the fatal outcome of severe cases.

Laser threshold and cell damage mechanism for intravascular photoacoustic imaging

2018 ◽  
Vol 51 (5) ◽  
pp. 466-474 ◽  
Author(s):  
Timothy Sowers ◽  
Don VanderLaan ◽  
Andrei Karpiouk ◽  
Eleanor M. Donnelly ◽  
Ethan Smith ◽  
...  
Keyword(s):  
Photoacoustic Imaging ◽  
Cell Damage ◽  
Damage Mechanism ◽  
Laser Threshold

Study of Impact-Induced Mechanical Effects in Cell Direct Writing Using Smooth Particle Hydrodynamic Method

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Wei Wang ◽  
Yong Huang ◽  
Mica Grujicic ◽  
Douglas B. Chrisey
Keyword(s):  
Shear Strain ◽  
Mechanical Loading ◽  
Cell Damage ◽  
Smooth Particle Hydrodynamic ◽  
Strain Component ◽  
Direct Writing ◽  
Maximum Shear Strain ◽  
Smooth Particle Hydrodynamic Method ◽  
Hydrodynamic Method ◽  
The Impact

Biomaterial direct-write technologies have been receiving more and more attention as rapid prototyping innovations in the area of tissue engineering, regenerative medicine, and biosensor∕actuator fabrication based on computer-aided designs. However, cell damage due to the mechanical impact during cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to investigate the impact-induced cell mechanical loading profile in cell landing in terms of stress, acceleration, and maximum shear strain component during cell direct writing using a mesh-free smooth particle hydrodynamic method. Such cell mechanical loading profile information can be used to understand and predict possible impact-induced cell damage. It is found that the cell membrane usually undergoes a relatively severe deformation and the cell mechanical loading profile is dependent on the cell droplet initial velocity and the substrate coating thickness. Two important impact processes may occur during cell direct writing: the first impact between the cell droplet and the substrate coating and the second impact between the cell and the substrate. It is concluded that the impact-induced cell damage depends not only on the magnitudes of stress, acceleration, and∕or shear strain but also the loading history that a cell experiences.

scholarly journals Study of Fluid Flow to a Horizontal Well

2021 ◽  
Vol 21 (2) ◽  
pp. 64-70
Author(s):  
Oksana N. Shevchenko ◽  
Keyword(s):  
Flow Rate ◽  
Horizontal Well ◽  
Initial Pressure ◽  
Horizontal Wells ◽  
Surface Friction ◽  
Economic Assessment ◽  
High Viscosity ◽  
Geological Structure ◽  
Oil Viscosity ◽  
Fluid Filtration

Recently, it is necessary to note the presence of negative dynamics in the deterioration of the reserves structure for newly discovered fields, and most of the them are classified as hard-to-recover, confined to deposits with a complex geological structure, low permeability, high oil viscosity, complicated by the presence of faults, active bottom waters and gas caps. Hard-to-recover reserves are drilled with horizontal wells. This is primarily because horizontal wells make it possible to multiply the area of fluid filtration due to the increase in the drainage area, due to the extensive contact of the horizontal well section with the rock, allowing to increase the well flow rate many times over. Summarizing the above, horizontal wells are used to develop fields with the following parameters: fields with a thin oilsaturated rim (up to 15 m), with a gas cap and bottom water; fields of heavy oil, with a viscosity of more than 30 mPa·s; fields with low reservoir permeability (less than 0.002 μm2). Under these conditions, linear Darcy’s law cannot describe fluid filtration. Under the conditions of high-viscosity oil and lowpermeability reservoir existence, a certain initial pressure gradient is determined, due to the rheological properties of the filtering fluid and high values of the surface friction coefficient. Under conditions of a thin oil rim and an increased gas factor, the limiting filtration rates due to the dissolved gas regime are observed, and a nonlinear law describes the fluid inflow. One of the main parameters in the preparation of the technical and economic assessment of the reservoir is the flow rate of each individual horizontal well. Analytical methods for calculating the horizontal well flow rate show a high error. It is proposed to take a fresh look at the problem of determining the predicted flow rate of a horizontal well, using well-known approaches for solving this issue. It is rather difficult to reliably predict the parameters of reservoir operation: the horizontal wells productivity obtained with the help of modern hydrodynamic stimulators turns out to be unreliable, which leads to the formation of an insufficiently rational development system. And the arising complications during operation in field conditions have to be eliminated due to significant volumes of material and labor resources. Thus, the development of methods that contribute to obtaining a reliable calculation of production is an urgent task for the oil industry.

Modeling and Analysis of the Droplet Landing Process in Cell Direct-Writing

2013 ◽  
Vol 7 (3) ◽  
pp. 353-358 ◽  
Author(s):  
Cai Renye ◽  
◽  
Huang Jin ◽  
Keyword(s):  
Large Scale ◽  
Cell Damage ◽  
Three Dimensional ◽  
Smooth Particle Hydrodynamic ◽  
Direct Write ◽  
Direct Writing ◽  
Modeling And Analysis ◽  
Mesh Free ◽  
Hydrodynamic Method ◽  
The Impact

Cell direct-write, a promising technology for the creation of complex, three-dimensional tissue constructs, has great potential in tissue engineering, biological cytology, high-throughput drug screening and cell sensors. However, it has been found that cell damage due to the mechanical impact during cell direct-write is a possible hurdle for broad applications of fragile cell direct writing. The objective of this paper is to analyze the impact of the continuously jetted cell droplets on the hydro-gel coating substrate. In order to avoid the element distortion due to large-scale deformation, a mesh-free Smooth Particle Hydrodynamic method (SPH), is introduced to study the impact-induced cell mechanical loading profile during cell landing, including effective stress, plastic strain, velocity and acceleration, for better understanding and prediction of possible impact-induced cell damage. It is found that three important impact processes, cell-hydrogel, cellcell and cell-substrate impact, may occur during cell landing. It is concluded to decrease impact-induced cell damage, there are an appropriate firing period and jetting velocity.

scholarly journals Preliminary investigations on extrusion of high viscosity slurry using direct writing technique

2020 ◽  
Vol 11 ◽  
pp. 15 ◽  
Author(s):  
Ali Tesfaye Kebede ◽  
Esakki Balasubramanian ◽  
AS Praveen ◽  
Lade Rohit ◽  
Kumar Arvind
Keyword(s):  
Flow Characteristics ◽  
High Viscosity ◽  
Curing Temperature ◽  
Solid Loading ◽  
Disruptive Technology ◽  
Internal Diameter ◽  
Solid Propellants ◽  
Direct Writing ◽  
The Cost ◽  
3D Printing Technique

Traditionally solid propellants are manufactured using casting and molding techniques. The effective burning rate of solid propellants is strongly depended on its cross section and geometry. The preparation of mold and mandrel for the manufacturability of various geometric profiles are tedious, time consuming, increases the cost and more human efforts are needed. In order to mitigate these issues, a disruptive technology called additive manufacturing (AM) is in the verge of development. Although the method is effective, additional study must be conducted to improve the flow characteristics of slurries for the high solid loading and there is a huge necessity to reduce the prolonged curing time. The present study focuses on preliminary investigations of extrusion of high viscosity slurry using a pneumatically driven extrusion system. The slurry was prepared with a 80 wt.% solid loading of NaCl having particle sizes of 45 µm and 150 µm, 15.6 wt.% HTPB, 2.2 wt.% TDI, 2.2 wt.% DOA and 0.03 wt.% of ferric acrylacetonate. The slurry was extruded with an aid of pneumatically controlled extruder and each layer was formed. Formed by extruding the slurry using 1.65 mm internal diameter nozzle. Infrared (IR) heater was utilized to transfer the radiational energy for partial curing of each layer and thereby adhesion of other layer was guaranteed. Simulation is performed to determine the temperature distribution using ANSYS platform for comparing the curing temperature of the printed part top surface. Preliminary experiments confirm that extrusion of slurry and heating of each layer can be effectively achieved with the proposed 3D printing technique. Three tensile specimens were produced in accordance with ASTMD 412-C and their corresponding mechanical properties are evaluated. The printed parts have the tensile strength of 0.7 MPa, elongation of 4.85 % and modulus of elasticity of 18.5 MPa which are comparable with the properties of conventional casted part.

scholarly journals Investigation of physicomechanical properties of carbide-silicon materials using the disten-sillimanite raw material of Ukraine

2018 ◽  
Vol 118 ◽  
pp. 49-55
Author(s):  
D. A. Brazhnik ◽  
G. D. Semchenko ◽  
G. N. Shabanova ◽  
I. N. Rozhko ◽  
V. V. Makarenko
Keyword(s):  
Silicon Carbide ◽  
Raw Materials ◽  
High Viscosity ◽  
Furnace Operation ◽  
Raw Material ◽  
Initial Stage ◽  
Rapid Destruction ◽  
Silicon Materials ◽  
Specific Amount ◽  
Physical And Mechanical Characteristics

Structural destruction is less for products used in various furnaces of ferrous and non-ferrous metallurgy, on the surface of which a melt with a high viscosity is formed during service. With this in mind, it seems appropriate to use silicon carbide materials, the grains of which are coated with a quartz film that protects SiC from rapid destruction in an oxidizing medium. To form a quartz film on carborundum grains, it is necessary to introduce quartz-containing raw materials, in particular, disthen-sillimanite concentrate, which allows to create the necessary phase composition of the lining mass in the process of raising the temperature at the initial stage of the furnace operation. The article is considered the possibility of using the disthen-sillimanite raw materials of Ukraine in the development of carbide-silicon materials. Various types of binder (ethyl silicate ETS-40, ETS 40/60, TLS, thermoplastic), variants of their correlation among themselves, and also with a different amount of disthen-sillimanite concentrate, are given. The possibility of controlling the physical and mechanical characteristics of materials by adjustment of the components ratio of binder and disthen-sillimanite concentrate is shown. The best combination of characteristics of silicon carbide materials, which is achieved by using a specific amount of disthen-sillimanite concentrate, is established.

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