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.

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.

Impact of Double-O-Tube Shield Tunnel Construction on Independent Foundation Frame Building

2011 ◽  
Vol 243-249 ◽  
pp. 3370-3375 ◽  
Author(s):  
Gang Wei ◽  
Jie Hong ◽  
Zhao Lin ◽  
Xin Jiang Wei
Keyword(s):  
Shear Strain ◽  
Principal Stress ◽  
Horizontal Displacement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Shield Tunneling ◽  
Maximum Shear Strain ◽  
Frame Building ◽  
Security Value ◽  
The Impact

Due to its better advantages, Double-O-Tube(DOT) shield has been widely applied in shield tunnel construction. But the impact caused by shield tunnel construction on buildings hasn’t been taken seriously. Considering the interaction of building-soil-tunnel, the independent foundation frame building vertical crossed by DOT shield tunnel was simulated by 3D MIDAS/GTS software, and the impact of construction on the building was analyzed. The results show that: during the passage of the shield tunneling through the building, the settlement of the building increased. The settlement was stable and had a little rebound when shield machine already passed the building. The building’s longitudinal displacement was great larger than lateral horizontal displacement. With the increase of driving distance, the first principal stress P1 and maximum shear strain MSmax increased and then were stable. With the increase of L, the first principal stress P1 and maximum shear strain MSmax tended to gradually reduce the security value, and the maximum differential settlement between columns increased first and then decreased. Finally, the safety of the building was assessed comprehensively.

scholarly journals Numerical Investigation of Closed-Form Solutions for Seismic Design of a Circular Tunnel Lining (by Quasi-Static Method)

2018 ◽  
Vol 4 (1) ◽  
pp. 239 ◽  
Author(s):  
Alireza Rashiddel ◽  
Mohammadreza Koopialipoor ◽  
Mir Raouf Hadei ◽  
Reza Rahmannejad
Keyword(s):  
Numerical Modeling ◽  
Shear Strain ◽  
Seismic Design ◽  
Analytical Methods ◽  
Tunnel Lining ◽  
Circular Tunnel ◽  
Maximum Shear Strain ◽  
Wide Range ◽  
Actual Interaction ◽  
The Impact

In this paper, four known analytical methods including Wang (1993), Penzien (2000), Park et al. (2009), and Bobet (2010) were Evaluated based on seismic design of circular tunnel in Tehran Metro Line 6. For this purpose, a quasi-static numerical method was applied in the framework of finite difference method (FDM) under the same assumptions. In both numerical and analytical methods, to consider the nonlinear behavior of soil, linear equivalent properties of soil derived from ground analysis were incorporated in EERA software. obtained results shown that the Park’s analytical solution under various conditions of interaction between the tunnel lining and soil provides very close results to the of numerical modeling. Afterward, a comprehensive validation was performed to assess the impact of the rigidity of the surrounding ground and the maximum shear strain value. In this regard, several earthquake scenarios with different shear wave rates were used to achieve a wide range of flexibility ratio (F) and maximum shear strain. The results showed a significant difference between the results of Penzine’s and Bobet’s methods under the no-slip conditions and those of numerical analyses for a certain range of flexibility and shear strain ratios. In the final part of the paper, a quasi-static seismic numerical study was performed under realistic soil-structure interaction conditions to illustrate the importance of the actual interaction between the tunnel lining and surrounding soil. The results showed that the actual interaction conditions governing estimation of the axial force play a very important role. Also, it was found that Park’s solution, because of the ability to consider the slip at the interface provides results very close to those of the numerical modeling. In contrast, one of the serious limitations of the other analytical methods is their inability to simulate the slip interface between the tunnel lining and soil.

Pitching Angle on Space Capsule Water Landing Using Smooth Particle Hydrodynamic Method

2017 ◽  
Vol 54 (3) ◽  
pp. 743-754 ◽  
Author(s):  
Zhaoyan Lu ◽  
Tianhang Xiao ◽  
Zhengzhou Li ◽  
Zhenming Zhang ◽  
Sha Du ◽  
...  
Keyword(s):  
Smooth Particle Hydrodynamic ◽  
Smooth Particle Hydrodynamic Method ◽  
Hydrodynamic Method ◽  
Space Capsule

scholarly journals 1178 High coronary wall shear strain developed more vulnerable plaque compared to low shear strain: a systematic review and meta-analysis

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
A B Bajraktari ◽  
I B Bytyci ◽  
S E Elezi ◽  
M Y H Henein
Keyword(s):  
Shear Strain ◽  
Vulnerable Plaque ◽  
Meta Analysis ◽  
Necrotic Core ◽  
Core Area ◽  
Plaque Area ◽  
Central Registry ◽  
Wall Shear ◽  
The Impact

Abstract Background and Aim Arterial wall strain has been proposed to impact the features of developed plaques. The aim of this meta-analysis is to assess the impact of different types of wall shear strain (WSS) on the changes of vulnerable plaque in coronary artery disease (CAD). Methods We systematically searched PubMed-Medline, EMBASE, Scopus, Google Scholar and the Cochrane Central Registry, from 1989 up to May 2019 in order to select clinical trials and observational studies, which assessed the relationship between WSS measured by intravascular ultrasound (IVUS) and morphology of plaque in CAD. Results In 7 studies, a total of 724 patients with 32,083 segments were recruited, with mean follow up 8.4 months. The pooled analysis showed that low WSS was associated with larger baseline lumen area WMD 2.55 [1.34 to 3.76, p < 0.001], smaller plaque area WMD -1.16 [-0.1.84 to -0.49, p = 0007] and necrotic core area WMD -0.45 [-0.78 to 0.14, p = 0.004], dense calcium score WMD -0.18 [-0.46 to 0.10, p = 0.01], and fibrous area WMD -0.79 [-1.84 to 0.30, p = 0.02] as well as smaller fibro-fatty area WMD -0.22 [-0.57 to 0.13, p = 0.02] compared to high WSS. At follow-up, the high WSS had regression of fibrous area, WMD -0.12 [-0.22 to -0.02, p = 0.02] and fibro-fatty area WMD -0.11 [-0.23 to -0.01, p = 0.04], reduction of plaque area WMD -0.09 [-0.17 to -0.02, p = 0.01] and increased dense calcium WMD 0.08 [0.02 to 0.14, p = 0.006] and necrotic core area WMD 0.07 [0.01 to 0.13, p = 0.03] compared to low WSS (Figure 1). The high WSS developed more profound remodeling compared to low WSS (40 vs. 18%, p < 0.05) with more constructive remodelling with low WSS (78%vs. 40 %, p < 0.01). Conclusions. Baseline high WSS is associated with higher necrotic core, calcium, fibrous and fibro-fatty area compared with low WSS, and during follow up the high WSS resulted in the development of more profound remodeling compared with low WSS. These findings highlighted the role of IVUS in detecting the vulnerable plaque in CAD. Abstract 1178 Figure 1. Mean change of plaque morpholo

Study on Thermal Cycling of Sn0.7Cu Solder

2013 ◽  
Vol 791-793 ◽  
pp. 362-365
Author(s):  
Li Yang ◽  
Ju Li Li ◽  
Jing Guo Ge ◽  
Meng Li ◽  
Nan Ji
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
High Temperature ◽  
Thermal Cycling ◽  
Shear Strain ◽  
Maximum Shear Stress ◽  
Steady State Creep ◽  
Maximum Shear Strain ◽  
Cycle Number ◽  
State Cycle

Thermal cycling of a unit Sn0.7Cu solder was studied based on the steady-state creep constitutive equation and Matlab software. The results show that there is a steady-state cycle for the thermal cycling of unit Sn0.7Cu eutectic solder. In steady-state thermal cycling, the shear stress is increased with the increase of temperature. There is a stage of stress relaxation during high temperature. A liner relationship between maximum shear stress and maximum shear strain is observed during thermal cycling. The metastable cycle number is declined greatly with the increase of maximum shear strain.

scholarly journals Research on the Tunnel Excavated In Urumqi Glacier No. 1, Tianshan Glaciological Station, China

1987 ◽  
Vol 33 (113) ◽  
pp. 99-104 ◽  
Author(s):  
Huang Maohuan ◽  
Wang Zhongxiang
Keyword(s):  
Melting Point ◽  
Shear Strain ◽  
Maximum Shear Strain ◽  
Ice Surface ◽  
Basal Sliding ◽  
Glacier Ice ◽  
Glacier Motion

AbstractA tunnel was excavated in Urumqi Glacier No. 1, at the Tianshan Glaciological Station. Ice temperature, ice displacement, deformation, and basal sliding, etc. were observed at regular intervals. It is shown that the temperature near the glacier bed is close to the melting point and that the largest proportion of the overall glacier motion is within the lowermost ice layers. The glacier ice is in a state of compression. The maximum shear strain increases towards the entrance of the tunnel, corresponding to the change in slope of the ice surface, and also towards the bedrock.

scholarly journals The Impact of Oxidative Stress on Dental Implants

2021 ◽  
Vol 2 (1) ◽  
pp. 1-8
Author(s):  
César Esquivel-Chirino ◽  
Juan Carlos Gómez-Landeros ◽  
Erika Patricia Carabantes-Campos ◽  
Daniela Carmona-Ruiz ◽  
Yolanda Valero-Princet ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dental Implants ◽  
Alveolar Bone ◽  
Inflammatory Responses ◽  
Cell Damage ◽  
Pathological Condition ◽  
Periodontal Diseases ◽  
Tissue Destruction ◽  
Waste Products ◽  
The Impact

Periodontal disease is an inflammatory condition that alters the periodontium, resulting in destruction of the alveolar bone; without treatment the condition may lead to tooth loss. Dental implants are an alternative for substitution of naturally lost teeth as they have high success rates; however, some factors are related to its failure. Peri-implantitis (PI) is a pathological condition that affects the tissues surrounding dental implants and has been reported as the major cause of implant failure; PI and periodontal diseases are characterized by tissue inflammation and bone damage. In homeostasis conditions, reactive oxygen species (ROS) have been shown to be involved in cell maintenance, signal transduction, and repair of all tissues, but ROS overaccumulation leads to oxidative stress, which generates cell damage and tissue destruction; likewise, antioxidants protect against the destructive effects of ROS by turning free radicals into waste products. The main purpose of this review was to determine some aspects of inflammatory responses and oxidative stress and analyze their relationship with the lack of osseointegration and PI.

scholarly journals Processing variables of direct-write, near-field electrospinning impact size and morphology of gelatin fibers

2020 ◽  
Author(s):  
Zachary G. Davis ◽  
Aasim F. Hussain ◽  
Matthew B. Fisher
Keyword(s):  
Acetic Acid ◽  
Acid Concentration ◽  
Near Field ◽  
Fiber Formation ◽  
Direct Write ◽  
Acetic Acid Concentration ◽  
Direct Writing ◽  
Fiber Morphology ◽  
Gelatin Concentration ◽  
The Impact

AbstractSeveral biofabrication methods are being investigated to produce scaffolds that can replicate the structure of the extracellular matrix. Direct-write, near-field electrospinning of polymer solutions and melts is one such method which combines fine fiber formation with computer-guided control. Research with such systems has focused primarily on synthetic polymers. To better understand the behavior of biopolymers used for direct-writing, this project investigated changes in fiber morphology, size, and variability caused by varying gelatin and acetic acid concentration, as well as, process parameters such as needle gauge and height, stage speed, and interfiber spacing. Increasing gelatin concentration at a constant acetic acid concentration improved fiber morphology from large, planar structures to small, linear fibers with a median of 2.3 µm. Further varying the acetic acid concentration at a constant gelatin concentration did not alter fiber morphology and diameter throughout the range tested. Varying needle gauge and height further improved the median fiber diameter to below 2 µm and variability of the first and third quartiles to within +/-1 µm of the median for the optimal solution combination of gelatin and acetic acid concentrations. Additional adjustment of stage speed did not impact the fiber morphology or diameter. Repeatable interfiber spacings down to 250 µm were shown to be capable with the system. In summary, this study illustrates the optimization of processing parameters for direct-writing of gelatin to produce fibers on the scale of collagen fibers. This system is thus capable of replicating the fibrous structure of musculoskeletal tissues with biologically relevant materials which will provide a durable platform for the analysis of single cell-fiber interactions to help better understand the impact scaffold materials and dimensions have on cell behavior.

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