Mechanical properties of the parenchyma of potato (Solanum tuberosum cv. Russet Burbank)

1996 ◽  
Vol 74 (6) ◽  
pp. 859-869 ◽  
Author(s):  
C. H. Pang ◽  
M. G. Scanlon
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Uniaxial Compression ◽  
Compressive Loading ◽  
Shear Stiffness ◽  
Small Strain ◽  
Oscillatory Shear ◽  
Plant Materials ◽  
Short And Long Term

The mechanical properties of plant materials and plant structures influence the form, function, distribution, and utilization of plants. The shear and compressive stiffnesses of different regions of potato parenchyma were measured to more fully characterize the mechanical properties of this important storage organ. Measurements were performed on tubers that had been stored for 1 and 10 months. Slices and cylinders of parenchyma were excised from the centre of the tubers in three directions (and slices from the outer portion in two directions). Slices were subjected to small-strain oscillatory shear at frequencies of 0.02, 0.2, and 2 Hz. Cylinders were subjected to three cycles of uniaxial compression at 2 and 20 cm∙min−1. The coefficient of variation of measured parameters ranged on average from 16 to 44% for both crops and both tests. At small strains, potato parenchyma behaved essentially as an elastic material. The results from both small-strain oscillatory shear and uniaxial compression suggested that potato parenchyma is anisotropic in nature. Slices from the outer and inner regions of the tuber had different shear stiffness values. The shear stiffness of tubers stored for 1 month was approximately 70% greater than those stored for 10 months. Repeated compressive loading of potato parenchyma cylinders ameliorated the differences in stiffness and energy absorption between short- and long-term stored tubers, attributable to movement of fluids from the cells during compression. The observations emphasize the complexity of potato tissue and how its mechanical properties change during storage. Keywords: shear, compression, energy absorption, stiffness, turgor, storage, anisotropicity.

scholarly journals Effect of cigarette smoking on nitric oxide, structural, and mechanical properties of mouse arteries

2006 ◽  
Vol 291 (5) ◽  
pp. H2354-H2361 ◽  
Author(s):  
X. Guo ◽  
M. J. Oldham ◽  
M. T. Kleinman ◽  
R. F. Phalen ◽  
G. S. Kassab
Keyword(s):  
Nitric Oxide ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Cigarette Smoking ◽  
Coronary Arteries ◽  
Short And Long Term ◽  
By Products ◽  
Enos Protein

Cigarette smoking (CS) is a major risk factor for vascular disease. The aim of this study was to quantitatively assess the influence of CS on mouse arteries. We studied the effect of short-term (6 wk) and long-term (16 wk) CS exposure on structural and mechanical properties of coronary arteries compared with that of control mice. We also examined the reversibility of the deleterious effects of CS on structural [e.g., wall thickness (WT)], mechanical (e.g., stiffness), and biochemical [e.g., nitric oxide (NO) by-products] properties with the cessation of CS. The left and right coronary arteries were cannulated in situ and mechanically distended. The stress, strain, elastic modulus, and WT of coronary arteries were determined. Western blot analysis was used to analyze endothelial NO synthase (eNOS) in the femoral and carotid arteries of the same mice, and NO by-products were determined by measuring the levels of nitrite. Our results show that the mean arterial pressure was increased by CS. Furthermore, CS significantly increased the elastic modulus, decreased stress and strain, and increased the WT and WT-to-radius ratio compared with those of control mice. The reduction of eNOS protein expression was found only after long-term CS exposure. Moreover, the NO metabolite was markedly decreased in CS mice after short- and long-term exposure of CS. These findings suggest that 16 wk of CS exposure can cause an irreversible deterioration of structural and elastic properties of mouse coronary arteries. The decrease in endothelium-derived NO in CS mice was seen to significantly correlate with the remodeling of arterial wall.

The Effects of Retesting on the Mechanical Properties of Brain Tissue

2013 ◽  
Author(s):  
A. Rezaei ◽  
M. Salimi Jazi ◽  
G. Karami ◽  
M. Ziejewski
Keyword(s):  
Mechanical Properties ◽  
Brain Tissue ◽  
Relaxation Times ◽  
Human Brain Tissue ◽  
Relaxation Functions ◽  
Before And After ◽  
Short And Long Term ◽  
Tissue Characteristics ◽  
Testing Protocols

Traumatic brain injury (TBI) is one of the most important problems in biomechanical engineering, and there have been many experiments conducted in order to characterize the mechanical properties of brain tissue. However, obtaining fresh human brain tissue is difficult, if not impossible. Also, the sample preparation and testing protocols must be carried out with great delicacy because brain tissue is very soft and vulnerable to being deformed under a very small amount of load. Most importantly, according to several researchers, each sample must be tested only one time as the tissue may be damaged and its characteristics subsequently changed. This paper is intended to examine the amount of decay that can happen in material characteristics due to retesting. A stress relaxation test is conducted on the same samples of the swine brain tissue multiple times in small and large deformations. The mechanical properties of the substance are calculated before and after retesting, and the constants of the tissue, as mechanical characteristics, are determined and compared. Short- and long-term moduli, relaxation times and relaxation functions are calculated and compared to understand how much they decay after repeating the experiments. The results show that retesting does not significantly change the elastic part of the tissue characteristics, but the viscous behavior shows a relatively sizeable change. The ability to account for the material decay of the samples due to repetition of the experiments results in the need for fewer samples and less preparation time and effort.

scholarly journals Rice Husk Shredding as a Means of Increasing the Long-Term Mechanical Properties of Earthen Mixtures for 3D Printing

2022 ◽  
Author(s):  
Elena Ferretti ◽  
Massimo Moretti ◽  
Alberto Chiusoli ◽  
Lapo Naldoni ◽  
Francesco De Fabritiis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Uniaxial Compression ◽  
Rice Husk ◽  
Brittle Material ◽  
Strict Sense ◽  
Compression Tests ◽  
Vegetable Fiber ◽  
Natural Way

This paper is part of a study of earthen mixtures for 3D printing of buildings. To meet the ever-growing environmental needs, the focus of the paper is on a particular type of biocomposite for the stabilization of earthen mixtures—the rice husk-lime biocomposite—and on how to enhance its effect on the long-term mechanical properties of the hardened product. Having assumed that the shredding of the vegetable fiber is precisely one of the possible ways to improve the mechanical properties, we compared the results of uniaxial compression tests performed on cubic specimens made with both shredded and unaltered vegetable fiber, for three curing periods. The results showed that the hardened earthen mixture is not a brittle material in the strict sense, because it exhibits some peculiar behaviors, anomalous for a brittle material. However, being a “designable” material, its properties can be varied with a certain flexibility to get as close as possible to the desired ones. One of the peculiar properties of the hardened earthen mixture deserves further investigation, rather than corrections. This is the vulcanization that occurs (in a completely natural way) in the long term, thanks to the mineralization of the vegetable fiber by carbonation of the lime.

scholarly journals Physical and Mechanical Properties Evolution of Coal Subjected to Salty Solution and a Damage Constitutive Model under Uniaxial Compression

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3264
Author(s):  
Min Wang ◽  
Qifeng Guo ◽  
Yakun Tian ◽  
Bing Dai
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Immersion Time ◽  
Physical And Mechanical Properties ◽  
Relative Mass ◽  
Stress Strain ◽  
Damage Constitutive Model ◽  
Underground Reservoirs

Many underground reservoirs for storing water have been constructed in China’s western coal mines to protect water resources. Coal pillars which work as dams are subjected to a long-term soaking environment of concentrated salty water. Deterioration of the coal dam under the attack of the salty solution poses challenges for the long-term stability and serviceability of underground reservoirs. The evolution of the physical and mechanical properties of coal subjected to salty solutions are investigated in this paper. Coal from a western China mine is made to standard cylinder samples. The salty solution is prepared according to chemical tests of water in the mine. The coal samples soaked in the salty solution for different periods are tested by scanning electron microscope, nuclear magnetic resonance, and ultrasonic detector techniques. Further, uniaxial compression tests are carried out on the coal specimens. The evolutions of porosity, mass, microstructures of coal, solution pH values, and stress–strain curves are obtained for different soaking times. Moreover, a damage constitutive model for the coal samples is developed by introducing a chemical-stress coupling damage variable. The result shows that the corrosion effect of salty solution on coal samples becomes stronger with increasing immersion time. The degree of deterioration of the longitudinal wave velocity (vp) is positively correlated with the immersion time. With the increase in soaking times, the porosity of coal gradually increases. The relative mass firstly displays an increasing trend and then decreases with time. The peak strength and elastic modulus of coal decreases exponentially with soaking times. The developed damage constitutive model can well describe the stress–strain behavior of coal subjected to salty solution under the uniaxial compression.

scholarly journals Enhancement by Metallic Tube Filling of the Mechanical Properties of Electromagnetic Wave Absorbent Polymethacrylimide Foam

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 372 ◽  
Author(s):  
Leilei Yan ◽  
Wei Jiang ◽  
Chun Zhang ◽  
Yunwei Zhang ◽  
Zhiheng He ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electromagnetic Wave ◽  
Energy Absorption ◽  
Structural Integrity ◽  
Compressive Loading ◽  
Metallic Tube ◽  
Foaming Process ◽  
Novel Structure ◽  
Load Carrying ◽  
Tube Filling

By the addition of a carbon-based electromagnetic absorbing agent during the foaming process, a novel electromagnetic absorbent polymethacrylimide (PMI) foam was obtained. The proposed foam exhibits excellent electromagnetic wave-absorbing properties, with absorptivity exceeding 85% at a large frequency range of 4.9–18 GHz. However, its poor mechanical properties would limit its application in load-carrying structures. In the present study, a novel enhancement approach is proposed by inserting metallic tubes into pre-perforated holes of PMI foam blocks. The mechanical properties of the tube-enhanced PMI foams were studied experimentally under compressive loading conditions. The elastic modulus, compressive strength, energy absorption per unit volume, and energy absorption per unit mass were increased by 127.9%, 133.8%, 54.2%, and 46.4%, respectively, by the metallic tube filling, and the density increased only by 5.3%. The failure mechanism of the foams was also explored. We found that the weaker interfaces between the foam and the electromagnetic absorbing agent induced crack initiation and subsequent collapses, which destroyed the structural integrity. The excellent mechanical and electromagnetic absorbing properties make the novel structure much more competitive in electromagnetic wave stealth applications, while acting simultaneously as load-carrying structures.

scholarly journals Altered bone mass, geometry and mechanical properties during the development and progression of type 2 diabetes in the Zucker diabetic fatty rat

2008 ◽  
Vol 199 (3) ◽  
pp. 379-388 ◽  
Author(s):  
Rhonda D Prisby ◽  
Joshua M Swift ◽  
Susan A Bloomfield ◽  
Harry A Hogan ◽  
Michael D Delp
Keyword(s):  
Mechanical Properties ◽  
Type 2 Diabetes ◽  
Bone Mass ◽  
Bone Strength ◽  
Skeletal Tissue ◽  
Glucose Levels ◽  
Zucker Diabetic Fatty Rats ◽  
Short And Long Term

Osteopenia and an enhanced risk of fracture often accompany type 1 diabetes. However, the association between type 2 diabetes and bone mass has been ambiguous with reports of enhanced, reduced, or similar bone mineral densities (BMDs) when compared with healthy individuals. Recently, studies have also associated type 2 diabetes with increased fracture risk even in the presence of higher BMDs. To determine the temporal relationship between type 2 diabetes and bone remodeling structural and mechanical properties at various bone sites were analyzed during pre-diabetes (7 weeks), short-term (13 weeks), and long-term (20 weeks) type 2 diabetes. BMDs and bone strength were measured in the femora and tibiae of Zucker diabetic fatty rats, a model of human type 2 diabetes. Increased BMDs (9–10%) were observed in the distal femora, proximal tibiae, and tibial mid- shafts in the pre-diabetic condition that corresponded with higher plasma insulin levels. During short- and long-term type 2 diabetes, various parameters of bone strength and BMDs were lower (9–26%) in the femoral neck, distal femora, proximal tibiae, and femoral and tibial mid-shafts. Correspondingly, blood glucose levels increased by 125% and 153% during short- and long-term diabetes respectively. These data indicate that alterations in BMDs and bone mechanical properties are closely associated with the onset of hyperinsulinemia and hyperglycemia, which may have direct adverse effects on skeletal tissue. Consequently, disparities in the human literature regarding the effects of type 2 diabetes on skeletal properties may be associated with the bone sites studied and the severity or duration of the disease in the patient population studied.

Influence of short and long term aging on chemical, microstructural and macro-mechanical properties of recycled asphalt mixtures

2014 ◽  
Vol 51 ◽  
pp. 414-423 ◽  
Author(s):  
Lily D. Poulikakos ◽  
Salomé dos Santos ◽  
Moises Bueno ◽  
Simon Kuentzel ◽  
Martin Hugener ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Asphalt Mixtures ◽  
Recycled Asphalt ◽  
Short And Long Term

The Effects of Retesting on the Mechanical Properties of the Brain Tissue

2013 ◽  
Author(s):  
Asghar Rezaei ◽  
Ghodrat Karami ◽  
Fardad Azarmi ◽  
Mehdi Salimi Jazi ◽  
Mariusz Ziejewski
Keyword(s):  
Mechanical Properties ◽  
Brain Tissue ◽  
Relaxation Times ◽  
Stress Relaxation Test ◽  
Preparation Time ◽  
Relaxation Functions ◽  
Before And After ◽  
Short And Long Term ◽  
The Brain

This research is intended to examine the amount of changes that can happen in material characteristics after retesting. Stress relaxation test is conducted on the same samples of the swine brain tissue for several times in small and large deformations. The mechanical properties of the substance are calculated before and after retest and the constants of the tissue, as mechanical characteristics, are determined and compared. Short- and long-term moduli, relaxation times and relaxation functions are of those data that are calculated and compared to understand how much they decay after repeating the experiments. The results show that applying different tests on one sample slightly changes the mechanical properties of the tissue and, as a result, it is partly possible to perform more than one test on the same sample resulting in less sample preparation, time and effort.

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