Cartilage Mechanical Response under Dynamic Compression at Physiological Stress Levels Following Collagenase Digestion

2008 ◽  
Vol 36 (3) ◽  
pp. 425-434 ◽  
Author(s):  
Seonghun Park ◽  
Steven B. Nicoll ◽  
Robert L. Mauck ◽  
Gerard A. Ateshian
Keyword(s):  
Mechanical Response ◽  
Physiological Stress ◽  
Dynamic Compression ◽  
Collagenase Digestion ◽  
Stress Levels

Analysis of Twinning Behavior of Ti-2V Alloy Compressed at High Strain Rate

2017 ◽  
Vol 898 ◽  
pp. 231-235
Author(s):  
Qiao Chu Wang ◽  
Rui Liu ◽  
Wen Jun Ye ◽  
Yang Yu ◽  
Xiao Yun Song ◽  
...  
Keyword(s):  
Strain Rate ◽  
Mechanical Response ◽  
Dynamic Compression ◽  
Orientation Imaging Microscopy ◽  
Optical Microscope ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
Deformation Degree ◽  
Ebsd Technique ◽  
Pressure Bar

The spilt Hopkinson pressure bar was employed to study dynamic compression mechanical response of Ti-2V alloy. The dynamic compression experiment was carried at a strain rate of 3000s-1. The microstructure of deformed specimen with ε=0.05, 0.18, 0.26 was observed by optical microscope. Electron Back-Scattered Diffraction (EBSD) technique was applied to confirm the types of twinning. Through analyzing mechanical response and microstructure evolution rule, the effect of element vanadium and deformation degree on dynamic mechanical properties and twinning deformation behavior was revealed. The results indicate that twinning is the prime dynamic deformation mechanism in Ti-2V alloy and the twinning fraction is increasingly raised during the deformation process. The twinning types, confirmed by Orientation Imaging Microscopy software, are namely {102}, {112} and {111} twinning. And the number of {111} twinning is far less than the other two types of twinning.

scholarly journals Grooming in Barbary macaques: better to give than to receive?

2007 ◽  
Vol 3 (3) ◽  
pp. 231-233 ◽  
Author(s):  
Kathryn Shutt ◽  
Ann MacLarnon ◽  
Michael Heistermann ◽  
Stuart Semple
Keyword(s):  
Social Life ◽  
Physiological Stress ◽  
Group Living ◽  
Lower Stress ◽  
Macaca Sylvanus ◽  
Barbary Macaques ◽  
Stress Levels ◽  
Free Ranging ◽  
To Receive ◽  
Grooming Behaviour

It is well established that grooming underpins sociality in group-living primates, and a number of studies have documented the stress-reducing effects of being groomed. In this study, we quantified grooming behaviour and physiological stress (assessed by faecal glucocorticoid analysis) in free-ranging Barbary macaques, Macaca sylvanus . Our results indicate that it is the giving rather than the receiving of grooming that is associated with lower stress levels. These findings shed important new light on the benefits of this key behaviour in primate social life.

scholarly journals Mechanical Response and Shear-Induced Initiation Properties of PTFE/Al/MoO3 Reactive Composites

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1200 ◽  
Author(s):  
Junyi Huang ◽  
Xiang Fang ◽  
Shuangzhang Wu ◽  
Li Yang ◽  
Zhongshen Yu ◽  
...  
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Mechanical Response ◽  
Dynamic Compression ◽  
Volume Ratio ◽  
Outer Edge ◽  
Reaction Products ◽  
Initiation Mechanism ◽  
Static Compression ◽  
Drop Weight

Polytetrafluoroethylene/aluminum/molybdenum oxide (PTFE/Al/MoO3) reactive composites of a volume ratio of 60:16:24 were studied in this research. Quasi-static compression, dynamic compression and drop-weight experiments were performed to explore the mechanical response and the shear-induced initiation properties of the composites. Mesoscale images of the specimens after sintering demonstrate that PTFE, Al and MoO3 powders were evenly mixed and no chemical reaction occurred after the materials were stirred, pressed and sintered. The yield stress and compressive strength of PTFE/Al/MoO3 specimens are sensitive to strain rate within the range of 10−3~3 × 103 s−1, and the yield stress shows a bilinear dependence on the logarithm values of strain rate. The established Johnson-Cook constitutive model based on the experimental data can describe the mechanical response of PTFE/Al/MoO3 material well. Drop-weight tests show that the PTFE/Al/MoO3 specimens can react violently when impacted, with the characteristic drop height (H50) calculated as 51.57 cm. The recovered specimens show that the reaction started from the outer edge of the specimen with the largest shear force and the most concentrated shear deformation, indicating a shear-induced initiation mechanism. The reaction products of PTFE/Al/MoO3 specimens were AlF3, Al2O3, Mo and C, demonstrating that redox reaction occurred between PTFE and Al, and between Al and MoO3.

Impacts of tourism on anxiety and physiological stress levels in wild male Barbary macaques

2011 ◽  
Vol 144 (9) ◽  
pp. 2188-2193 ◽  
Author(s):  
Laëtitia Maréchal ◽  
Stuart Semple ◽  
Bonaventura Majolo ◽  
Mohamed Qarro ◽  
Michael Heistermann ◽  
...  
Keyword(s):  
Physiological Stress ◽  
Barbary Macaques ◽  
Wild Male ◽  
Stress Levels

scholarly journals Experimental Investigation on the Mechanical Response of Coals to Uniaxial Compression and Low-Speed Dynamic Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jing-Xuan Zhou ◽  
Chuan-Jie Zhu ◽  
Xi-Miao Lu ◽  
Jie Ren ◽  
Rong-Jun Si ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dynamic Loading ◽  
Mechanical Response ◽  
Fragment Size ◽  
Dynamic Compression ◽  
Dynamic Strain ◽  
Hysteresis Phenomenon ◽  
Gas Explosions ◽  
Static Mechanical ◽  
Static Mechanical Properties

The surrounding rock of roadways in underground coal mines will lose its stability or even collapse under gas explosions, especially roadways surrounded by coals. The dynamic mechanical properties of coals were tested in order to investigate the dynamic response of coals under gas explosions. The static mechanical properties of coals were also tested as comparison. It is found that the dynamic stress-strain curves showed no obvious pore compaction stage comparing with uniaxial loading. The dynamic compression strength and the elastic modulus are obviously larger than those obtained in the static mechanical properties test, and the dynamic strain shows an obvious hysteresis phenomenon. The ultimate strain and absorbed energy increased linearly with increase of the strain rate. With the increase of dynamic loading, the fragment size of coal cores decreased obviously. The results could provide a reference for the antiexplosion design of the coal roadway.

Cyclic Loading of Polyetheretherketone at High Tensile Stress Levels

2014 ◽  
Vol 601 ◽  
pp. 12-16 ◽  
Author(s):  
Michael Berer ◽  
Zoltan Major ◽  
Gerald Pinter ◽  
Dan Mihai Constantinescu ◽  
Liviu Marsavina
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Thermal Conditions ◽  
Hydraulic Testing ◽  
Fatigue Tests ◽  
Material Response ◽  
Cumulative Response ◽  
Stress Levels ◽  
Number Of Cycles ◽  
Highly Strained

In a recent study of the corresponding author, it was found that PEEK bearing elements revealed high (irreversible) surface strains if they were loaded between steel sheets. Since this reflects the conditions in the practical application and because the rolling properties are dominated by the surface material, a more detailed analysis of highly strained PEEK was required. Hence, fatigue tests in the high stress tensile regime were conducted. The experiments were carried out on servo-hydraulic testing machines and during the tests the mechanical response of the specimens was recorded. Two material modifications of PEEK were investigated in the research: untreated PEEK (without heat treatment) and annealed PEEK which was modified using defined thermal conditions. The analysis of the recorded test data aimed on the distinction between cumulative material response (creep deformation, material hardening / softening) and spontaneous material response (material hardening / softening). At the highest stress levels, the cumulative response pretended material softening with increasing number of cycles. However, by examining the spontaneous material response which became stiffer with increasing number of cycles, it was shown that the cumulative softening was caused by time-dependent deformation processes.

scholarly journals Physiological stress levels predict survival probabilities in wild rabbits

2007 ◽  
Vol 51 (3) ◽  
pp. 313-320 ◽  
Author(s):  
Sonia Cabezas ◽  
Julio Blas ◽  
Tracy A. Marchant ◽  
Sacramento Moreno
Keyword(s):  
Physiological Stress ◽  
Survival Probabilities ◽  
Stress Levels
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