scholarly journals The visceral pericardium: macromolecular structure and contribution to passive mechanical properties of the left ventricle

2007 ◽  
Vol 293 (6) ◽  
pp. H3379-H3387 ◽  
Author(s):  
Paul D. Jöbsis ◽  
Hiroshi Ashikaga ◽  
Han Wen ◽  
Emily C. Rothstein ◽  
Keith A. Horvath ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Ex Vivo ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Left Ventricular ◽  
Opening Angle ◽  
Passive Stiffness ◽  
Photon Excitation ◽  
Before And After

Much attention has been focused on the passive mechanical properties of the myocardium, which determines left ventricular (LV) diastolic mechanics, but the significance of the visceral pericardium (VP) has not been extensively studied. A unique en face three-dimensional volumetric view of the porcine VP was obtained using two-photon excitation fluorescence to detect elastin and backscattered second harmonic generation to detect collagen, in addition to standard light microscopy with histological staining. Below a layer of mesothelial cells, collagen and elastin fibers, extending several millimeters, form several distinct layers. The configuration of the collagen and elastin layers as well as the location of the VP at the epicardium providing a geometric advantage led to the hypothesis that VP mechanical properties play a role in the residual stress and passive stiffness of the heart. The removal of the VP by blunt dissection from porcine LV slices changed the opening angle from 53.3 ± 10.3 to 27.3 ± 5.7° (means ± SD, P < 0.05, n = 4). In four porcine hearts where the VP was surgically disrupted, a significant decrease in opening angle was found (35.5 ± 4.0°) as well as a rightward shift in the ex vivo pressure-volume relationship before and after disruption and a decrease in LV passive stiffness at lower LV volumes ( P < 0.05). These data demonstrate the significant and previously unreported role that the VP plays in the residual stress and passive stiffness of the heart. Alterations in this layer may occur in various disease states that effect diastolic function.

Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps

2011 ◽  
Author(s):  
Kohta Nakahira ◽  
Hironori Tago ◽  
Fumiaki Endo ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Flexural Rigidity ◽  
Three Dimensional ◽  
Strain Gauges ◽  
Copper Interconnection ◽  
Induced Stress ◽  
Alignment Structure

Since the thickness of the stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the thermal residual stress distribution appears in the stacked chips due to the periodic alignment of metallic bumps, and they deteriorate the reliability of products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are discussed quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of 4 gauges with different crystallographic directions. This alignment of strain gauges enables to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made by silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper layer was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the rigid joint formation by alloying with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed experimentally that both the hound’s-tooth alignment between a TSV (Through Silicon Via) and a bump and control of mechanical properties of electroplated copper thin films used for the TSV and bump is indispensable in order to minimize the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process induced stress in 3D stacked chips quantitatively.

scholarly journals Multi-sector approximation method for arteries: the residual stresses of circumferential rings with non-trivial openings

2019 ◽  
Vol 16 (156) ◽  
pp. 20190023 ◽  
Author(s):  
Taisiya Sigaeva ◽  
Michel Destrade ◽  
Elena S. Di Martino
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Inverse Problem ◽  
Residual Stresses ◽  
Opening Angle ◽  
Circular Sector ◽  
Ring Configuration ◽  
Closed Ring ◽  
Angle Method ◽  
Pathological Tissues

The opening angle method is a popular choice in biomechanics to estimate residual stresses in arteries. Experimentally, it means that an artery is cut into rings; then the rings are cut axially or radially allowing them to open into sectors; finally, the corresponding opening angles are measured to give residual stress levels by solving an inverse problem. However, for many tissues, for example in pathological tissues, the ring does not open according to the theory into a neat single circular sector, but rather creates an asymmetric geometry, often with abruptly changing curvature(s). This phenomenon may be due to a number of reasons including variation in thickness, microstructure, mechanical properties, etc. As a result, these samples are often eliminated from studies relying on the opening angle method, which limits progress in understanding and evaluating residual stresses in real arteries. With this work, we propose an effective approach to deal with these non-trivial openings of rings. First, we digitize pictures of opened rings to split them into multiple, connected circular sectors. Then we measure the corresponding opening angles for each sub-sector. Subsequently, we can determine the residual stresses for individual sectors in a closed-ring configuration and, thus, approximate the circumferential residual bending effects.

scholarly journals Moderated Posters: Deformation imagingP96How accurate can different strain analysis tools detect regional function?abnormalities, a report from the second inter-vendor comparison?studyP97Variability and reproducibility of segmental longitudinal strain measurements, a report form the second intervendor comparison studyP98Systolic and diastolic left atrial deformation parameters before and after optimization of dual chamber pacemaker parametersP99The timing of the post systolic shortening in prediction of scarred myocardiumP100Altered contribution of longitudinal and radial motion to right ventricular ejection and filling in heart transplant recipientsP101Left ventricular and atrial function in old patients underwent transcatheter aortic valve implantation, evaluated by two and three-dimensional speckle tracking at eighteen-month follow-upP102Age-related changes in left ventricular strain measured by speckle-tracking echocardiography and association with telomere length in healthy peopleP103Intracardiac speckle tracking echocardiography-based method for assessment of pulmonary vein isolation in patients with atrial fibrillation

2016 ◽  
Vol 17 (suppl 2) ◽  
pp. ii9-ii11
Author(s):  
O. Mirea ◽  
O. Mirea ◽  
A. Karuzas ◽  
E. Nestaas ◽  
BK. Lakatos ◽  
...  
Keyword(s):  
Speckle Tracking ◽  
Speckle Tracking Echocardiography ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Left Ventricular ◽  
Old Patients ◽  
Left Ventricular Strain ◽  
Transcatheter Aortic Valve ◽  
Before And After ◽  
Valve Implantation

Three-Dimensional Numerical Simulation of Temperature Field and Force Field of T-Type Turbe during Welding

2013 ◽  
Vol 690-693 ◽  
pp. 2659-2663
Author(s):  
Jian Ping Zhou ◽  
Xiang Feng Zhang ◽  
Hong Sheng Liu ◽  
Jun Yi Gao ◽  
Yan Xu
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Temperature Field ◽  
Three Dimensional ◽  
Welding Process ◽  
Three Dimension ◽  
Analysis Software ◽  
Element Analysis ◽  
Cool Process ◽  
Type Tube

Residual stress affect the lifetime of weldments directly. Temperature Generated from the welding process is the major reason that influences the microstructure and mechanical properties of the metal weldments. Therefore it is necessary to simulate the temperature field for optimizing the structure of weldments. In this work the three-dimension finite element analysis software SYSWELS was used to simulate T-type tube, and carried on a detailed analysis of temperature field and residual stress in cool process of weld.

scholarly journals MULTIMODAL NONLINEAR OPTICAL IMAGING OF CELL–MATRIX INTERACTION DURING SPINAL CORD INJURY EX VIVO

2011 ◽  
Vol 23 (03) ◽  
pp. 223-230 ◽  
Author(s):  
Yi-Cheng Huang ◽  
Te-Hsuen Chen ◽  
Wen-Chun Kuo ◽  
Sung-Hao Hsu ◽  
Yi-You Huang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Ex Vivo ◽  
Second Harmonic ◽  
Two Photon ◽  
Matrix Interaction ◽  
Cell Matrix ◽  
Photon Excitation ◽  
Cord Injury ◽  
Near Future

Neurons within spinal cord injury (SCI) are prevented from regeneration because of scar formation. Chondroitinase ABC (ChABC) was reported to promote functional recovery after spinal cord injury. However, the mechanism and the role of ChABC in the recovery are not clear. In this research, we used second harmonic generation (SHG) and two-photon excitation fluorescence (2PEF) images as probes to observe cell–matrix interaction on fibrosis after SCI followed by ChABC treatment. According to our experimental results, the enzyme ChABC could decrease cystic formation dramatically and consequently allow the spinal cord to regenerate. Using immunohistological analysis, we found that treatment with ChABC at the lesion area resulted in fewer chondroitin sulfate proteoglycans (CSPGs) remaining, longer axonal re-growth, and more new developmental neurons. Furthermore, ChABC 1 U/ml was more effective than 5 U/ml treatment. Using the noninvasive technology, SHG and 2PEF images, we could observe cell–matrix interaction clearly, not only in fixed samples but also in unfixed ex vivo samples. This technology presents a potential for clinical use in the near future.

Mechanical Stress Monitoring Sensor for 3-D Module During Manufacturing and Operation

2017 ◽  
Author(s):  
Koki Isobe ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Crystalline Silicon ◽  
Three Dimensional ◽  
Stress Monitoring ◽  
Impact Stress ◽  
Total Structure ◽  
Periodic Stress ◽  
The Impact ◽  
Packaging Module

In three-dimensional packaging module which have been used in electronic equipment, the size of partial interconnections and total structure have been continuously miniaturized for improving the performance of the products. Due to the fluctuation of the mechanical properties of the component materials and the drop impact towards the fragile modules during manufacturing and operation, the final residual stress varies easily in a chip of the 3-D structure. Both the static and dynamic changes of the stress distribution induce the variation of the performance of electronic devices and the degradation of their long-term reliability. It is, therefore, important to control and optimize the residual stress quantitatively. In this study, a stress sensor which can monitor the change of the local residual stress in 3-D module was developed by applying the piezoresistance effect of single-crystalline silicon. The sensor was embedded in a silicon chip, and it can measure the periodic stress in a silicon chip assembled by area-arrayed bump structure. The impact stress during the manufacturing process was successfully monitored by using this sensor. It was also confirmed that the effective amplitude of the impact stress varies drastically depending on the mechanical properties of the stacked thin films.

Evaluation of Hydroxyapatite Film by Powder Jet Deposition after Artificial Aging

2012 ◽  
Vol 529-530 ◽  
pp. 229-232
Author(s):  
Ryo Akatsuka ◽  
Ken Matsumura ◽  
Miyoko Noji ◽  
Chihiro Nishikawa ◽  
Kei Sato ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Cycling ◽  
Vickers Hardness ◽  
Bonding Strength ◽  
Artificial Aging ◽  
Three Dimensional ◽  
Human Tooth ◽  
Significant Difference ◽  
Before And After ◽  
New Type

This study aimed to create a thick hydroxyapatite (HAp) film on the surface of a human tooth by using a newly developed powder jet deposition (PJD) device for dental handpieces, and sought to examine the microstructural and mechanical properties of the resulting HAp film. The film was evaluated on three-dimensional view, surface roughness, Vickers hardness, and bonding strength before and after artificial aging through thermal cycling (555°C) for 500 cycles (30 sec for each cycle, 20 sec of dwell time).The HAp particles in the deposited film were densely packed, and the HAp films three-dimensional microstructure and its rough surface were maintained after thermal cycling. There was no significant difference in either the HAp films Vickers hardness or the bonding strength between the film and the enamel substrate before and after thermal cycling. The HAp films created in this study demonstrated excellent microstructural and mechanical properties even after the application of thermal stress. We demonstrated the possibility of using a new type of powder jet deposition (PJD) method we developed to form a new type of interface between the tooth and biomaterials. Consequently, we propose the use of this method in new dental treatments.

Trabecular cutting: a novel surgical therapy to increase diastolic compliance

2019 ◽  
Vol 127 (2) ◽  
pp. 457-463
Author(s):  
Meagan Oglesby ◽  
Danny Escobedo ◽  
Gladys Patricia Escobar ◽  
Fatemeh Fatemifar ◽  
Edward Y. Sako ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Diastolic Pressure ◽  
Ex Vivo ◽  
Systolic Function ◽  
Wall Stress ◽  
Rabbit Heart ◽  
Left Ventricular ◽  
Before And After ◽  
Diastolic Compliance

Heart failure with preserved ejection fraction (HFpEF) is a common cause of hospital admission in patients over 65 yr old and has high mortality. HFpEF is characterized by left ventricular (LV) hypertrophy that reduces compliance. Current HFpEF therapies control symptoms, but no existing medications or therapies can sustainably increase LV compliance. LV trabeculae develop hypertrophy and fibrosis that contribute to reduced LV compliance. This study expands our previous results in ex vivo human hearts to show that severing LV trabeculae increases diastolic compliance in an ex vivo working rabbit heart model. Trabecular cutting was performed in ex vivo rabbit hearts set up in a working heart perfusion system perfused with oxygenated Krebs-Henseleit buffer. A hook was inserted in the LV to cut trabeculae. End-systolic and end-diastolic pressure-volume relationships during transient preload reduction were recorded using an admittance catheter in the following three groups: control (no cutting; n = 9), mild cutting (15 cuts; n = 5), and aggressive cutting (30 cuts; n = 5). In a second experiment, each heart served as its own control. Hemodynamic data were recorded before and after trabecular cutting ( n = 10) or sham cutting ( n = 5) within the same heart. In the first experiments, trabecular cutting did not affect systolic function ( P > 0.05) but significantly increased overall diastolic compliance ( P = 0.009). Greater compliance was seen as trabecular cutting increased ( P = 0.002, r2 = 0.435). In the second experiment, significant increases in systolic function ( P = 0.048) and diastolic compliance ( P = 0.002) were seen after trabecular cutting compared with baseline. In conclusion, trabecular cutting significantly increases diastolic compliance without reducing systolic function. NEW & NOTEWORTHY We postulate that, in mammalian hearts, free-running trabeculae carneae exist to provide tensile support to the left ventricle and minimize diastolic wall stress. Because of hypertrophy and fibrosis of trabeculae in patients with left ventricular hypertrophy, this supportive role can become pathologic, worsening diastolic compliance. We demonstrate a novel operation involving cutting trabeculae as a method to acutely increase diastolic compliance in patients presenting with heart failure and diastolic dysfunction to improve their left ventricle compliance.

scholarly journals Improvement of mechanical properties and fatigue life by shot peening process on ASTM A516 Grade 70 steel

2018 ◽  
Vol 14 (4) ◽  
pp. 440-442
Author(s):  
Mohd Rashdan Isa ◽  
Omar Suliman Zaroog ◽  
Kalaikathir Murugan ◽  
Sharif Osman Kabashi Guma ◽  
Fareg Saeid Ali
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Tensile Strength ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Industrial Sector ◽  
Low Intensity ◽  
Before And After

ASTM A516 Grade 70 is widely used in the industrial sector as it provides very good mechanical properties in tough conditions. The main usage of this material is in moderate and low operating services. This paper focuses on the effect of shot peening process on ASTM A516 Grade 70 on improving the mechanical properties and fatigue life of the material. Samples have been shot peened with steel shot to induce compressive residual stress. Hardness, tensile and fatigue test as well as microstructure were done on the samples before and after shot peening process to study the effects on mechanical properties. The result shows that there is an increment in every test after shot peening process. There is a slight increment of 0.47% in hardness value, 0.39% increment in tensile strength and 6.78% increment in fatigue life of the material after shot peening process applied. The slight increment in every result was due to the low intensity of the shot peening process. Result also shows that the shot peening process compressed the molecules closer to each other as can be seen under SEM. Therefore it was proven that in this study, there is a very significant improvement in mechanical properties and fatigue life by shot peening process on ASTM A516 Grade 70 Steel.

scholarly journals A new technique for use in the study of the microbiome: An evaluation of a three-dimensional cell culture technique in maintaining the gastrointestinal microbiome of four Balb/c female mice and implications for future studies

2019 ◽  
Author(s):  
Everest Uriel Castaneda ◽  
Jeff Brady ◽  
Janice Speshock
Keyword(s):  
Ex Vivo ◽  
Three Dimensional ◽  
Distal Colon ◽  
Culture Technique ◽  
Model Organisms ◽  
16S Sequencing ◽  
Future Studies ◽  
Disease States ◽  
Before And After ◽  
A New Technique

AbstractFluctuations in oxygen, pH, nutrients, or other factors such as food or pharmaceuticals, may perturb the microbiota of the gastrointestinal (GI) tract. This environmental variation is a cause for concern given dysbiosis of the microbiome is correlated with disease states; thereby, model organisms are utilized to study microbial communities during, after, or before shifts in microbes since intact ex vivo microbiomes have historically been challenging to utilize. The objective of this study is to culture an explant microbiome of 4 Balb/c, laboratory bred mice to develop an ex vivo tool for future microbiome studies. We cultured homogenates of the distal colon of 4 mice in three dimensional, 24 well plate culture dishes. These dishes were incubated for 24 hours in two different oxygen concentration levels, 0% and 20%. The pH of the plate was tested before and after incubation. To analyze the integrity of the microbiome, we utilized 16S sequencing. Further, we utilized 16S metagenomics to characterize fecal samples and colon samples to speculate whether future studies may utilize feces in constructing an explant microbiome to spare animal lives. We found that pH and familial relationship had a profound impact on community structure while oxygen did not have a significant influence. The feces and the colon were similar in community profiles, which lends credence to utilizing feces in future studies. In addition, our efforts successfully cultured archaea, which included difficult to culture strains such as Miscellaneous Crenarchaeota group (MCG) and Methanobacteria. Ultimately, further attempts to culture and preserve an animal’s microbiome needs to control for and maintain stable pH.

Sign in / Sign up

Export Citation Format

Share Document