scholarly journals Distinct matrix composition and mechanics in aged and estrogen-deficient mouse skin

2019 ◽  
Author(s):  
Charis R Saville ◽  
Venkatesh Mallikarjun ◽  
David F Holmes ◽  
Elaine Emmerson ◽  
Brian Derby ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Tensile Strength ◽  
Mouse Skin ◽  
Hormone Deficiency ◽  
Matrix Composition ◽  
Estrogen Deprivation ◽  
Skin Loss ◽  
Aged Skin ◽  
Strength And Stiffness

ABSTRACTHormone deficiency has been widely linked to accelerated tissue ageing, and increased incidence of chronic degenerative disease. Furthermore, age-associated hormonal dysregulation is thought to be a major contributing factor to the increased fragility of aged skin. The ageing process is driven by an aggregation of damage to cells and extracellular matrix, which can directly influence the mechanical properties of the tissue. Here we report on the correlation between mechanical properties and composition of skin from ovariectomised and aged mice, to assess the extent to which estrogen deprivation drives dermal ageing. We found that age and estrogen abrogation affected skin mechanical properties in contrasting ways: ageing led to increased tensile strength and stiffness while estrogen deprivation had the opposite effect. Mass spectrometry proteomics showed that the quantity of extractable fibrillar collagen-I decreased with ageing, but no change was observed in ovariectomised mice. This observation, in combination with measurements of tensile strength, was interpreted to reflect changes to the extent of extracellular matrix crosslinking, supported by a significant increase in the staining of advanced glycation endpoints in aged skin. Loss of mechanical strength in the skin following ovariectomy was consistent with a loss of elastic fibres. Other changes in extracellular matrix composition broadly correlated between aged and ovariectomised mice, confirming the important role of estrogen-related pathways in ageing. This study offers new insight into the relationship between tissue composition and mechanics, and suggests that the deleterious effects of intrinsic skin ageing are compounded by factors beyond hormonal dysregulation.

scholarly journals Thermo-Mechanical and Morphological Properties of Water Hyacinth Reinforced Polypropylene Composites

2018 ◽  
Vol 3 (3) ◽  
pp. 151-161
Author(s):  
Manabendra Saha ◽  
Ali Md. Afsar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Water Hyacinth ◽  
Thermal Analyses ◽  
Morphological Properties ◽  
Sem Images ◽  
Pull Out ◽  
Chemically Treated ◽  
Pp Composites ◽  
Strength And Stiffness

This paper focusses on the analysis of thermo-mechanical and morphological properties of water hyacinth (WH) fiber reinforced polypropylene (PP) biocomposites manufactured by using a single screw extruder and an injection molding machine. With a view to increasing the compatibility between the WH fibers and polypropylene matrix, raw WH fibers were chemically treated with Benzenediazonium salt in base media. Composites were manufactured with five different levels of loading (15, 20, 25, 30 and 35 wt%) of both the raw and treated WH fibers. Thermal properties of WH-PP composites were evaluated by thermogravimetric and differential thermal analyses. To analyze mechanical properties of composites, tests of tensile strength and stiffness, flexural strength and stiffness, and Charpy impact strength were carried out following ASTM standards. It was found that thermal stability and all the mechanical properties except tensile strength were improved considerably for chemically treated WH fiber composites in comparison with untreated ones. Fracture surfaces of the tensile and flexural specimens were scanned with scanning electron microscopy (SEM) to understand their surface morphologies. The SEM images clearly revealed that there were fewer fiber agglomerations, microvoids, and fiber pull out traces in treated WH-PP composites than in the untreated ones indicating better distribution of the fibers into the matrix as well as stronger fiber matrix interfacial adhesion due to treatment of WH fibers. Water absorption properties were studied to evaluate the viability of these biocomposites under specified conditions.

scholarly journals An Overview of Alkali Treatments of Hemp Fibres and Their Effects on the Performance of Polymer Matrix Composites

2021 ◽  
Author(s):  
Tom Sunny ◽  
Kim L. Pickering
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Polymer Matrix Composites ◽  
Alkali Treatment ◽  
Matrix Composites ◽  
Natural Plant ◽  
Fibre Bundles ◽  
Hemp Fibres ◽  
Strength And Stiffness

The alkali treatment is aimed to modify the surface chemistry of natural plant fibres effectively through several factors. This treatment has been carried out at ambient and high temperature. Natural plant fibres treated with alkali have been seen to have benefits such as improved separation of fibres from fibre bundles, improved removal of unwanted surface constituents, increased tensile strength and stiffness, better thermal stability, and enhanced interfacial adhesions compared to other standard treatments. Hemp fibres are an attractive reinforcement for natural plant fibres as they are environmentally friendly compared to other natural plant fibres and exhibit good mechanical properties. This chapter mainly provides an overview of alkali treatments on hemp fibres.

scholarly journals Extracellular matrix density regulates the formation of tumour spheroids through cell migration

2021 ◽  
Vol 17 (2) ◽  
pp. e1008764
Author(s):  
Inês G. Gonçalves ◽  
Jose Manuel Garcia-Aznar
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Cell Migration ◽  
Tumour Growth ◽  
Individual Cell ◽  
Matrix Composition ◽  
Matrix Density ◽  
Tumour Spheroids ◽  
The Matrix ◽  
Collagen Density

In this work, we show how the mechanical properties of the cellular microenvironment modulate the growth of tumour spheroids. Based on the composition of the extracellular matrix, its stiffness and architecture can significantly vary, subsequently influencing cell movement and tumour growth. However, it is still unclear exactly how both of these processes are regulated by the matrix composition. Here, we present a centre-based computational model that describes how collagen density, which modulates the steric hindrance properties of the matrix, governs individual cell migration and, consequently, leads to the formation of multicellular clusters of varying size. The model was calibrated using previously published experimental data, replicating a set of experiments in which cells were seeded in collagen matrices of different collagen densities, hence producing distinct mechanical properties. At an initial stage, we tracked individual cell trajectories and speeds. Subsequently, the formation of multicellular clusters was also analysed by quantifying their size. Overall, the results showed that our model could accurately replicate what was previously seen experimentally. Specifically, we showed that cells seeded in matrices with low collagen density tended to migrate more. Accordingly, cells strayed away from their original cluster and thus promoted the formation of small structures. In contrast, we also showed that high collagen densities hindered cell migration and produced multicellular clusters with increased volume. In conclusion, this model not only establishes a relation between matrix density and individual cell migration but also showcases how migration, or its inhibition, modulates tumour growth.

Relationships Between Melanocytes, Mechanical Properties and Extracellular Matrix Composition in Mouse Heart Valves

2015 ◽  
Vol 25 (1-2) ◽  
pp. 17-26 ◽  
Author(s):  
Flavia Carneiro ◽  
Boudewijn PT Kruithof ◽  
Kanthesh Balani ◽  
Arvind Agarwal ◽  
Vinciane Gaussin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Heart Valves ◽  
Matrix Composition ◽  
Mouse Heart

Stiffness matters: mechanical properties of human leiomyomas and their extracellular matrix composition

2007 ◽  
Vol 88 ◽  
pp. S218-S219
Author(s):  
J. Norian ◽  
G. Christman ◽  
C. Korecki ◽  
J. Iatridis ◽  
F. Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Matrix Composition

Effect of Magnesium on the Strength, Stiffness and Toughness of Nodular Cast Iron

2020 ◽  
Vol 991 ◽  
pp. 17-23
Author(s):  
Agung Setyo Darmawan ◽  
Pramuko Ilmu Purboputro ◽  
Agus Yulianto ◽  
Agus Dwi Anggono ◽  
Wijianto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Yield Strength ◽  
Tensile Test ◽  
Impact Test ◽  
Nodular Cast Iron ◽  
Ferrite Matrix ◽  
Strength And Stiffness ◽  
The Impact

Nodular cast iron is a type of cast iron with spheroid graphite surrounded by ferrite matrix and / or pearlite. The size of the graphite and its matrix affects the mechanical properties of the cast iron. This research was conducted to investigate the effect of Magnesium composition on strength, stiffness and toughness of nodular cast iron. Magnesium addition is performed by adding FeSiMg alloys. After that, the composition of magnesium was investigated by using spectrometry. Then tensile test was conducted to obtain the yield strength, tensile strength and modulus of elasticity. Further, impact test was performed to determine the impact energy needed to break the material. The result showed an increase of yield strength, tensile strength and stiffness and a decrease of toughness.

Altered Mechanical Properties and Fiber Re-Alignment in Diabetic Mouse Supraspinatus and Achilles Tendons

2012 ◽  
Author(s):  
Brianne K. Connizzo ◽  
Kenneth W. Liechty ◽  
Louis J. Soslowsky
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Insertion Site ◽  
Joint Stiffness ◽  
Biomechanical Properties ◽  
Diabetic Mouse ◽  
Matrix Proteins ◽  
Matrix Composition ◽  
Tendon Stiffness ◽  
Diabetic Population

Tendons function to transfer load, maintain alignment and permit motion in joints. To perform these functions, tendons have complex mechanical behavior which is modulated by the tissue’s structure and composition, such as the collagen fibers and surrounding extracellular matrix. When these matrix proteins are altered, the mechanical properties are also altered, which could potentially lead to reduced loading and healing capacity. Diabetes is a metabolic disease which, among other co-morbidities, has been associated with Achilles tendon disorganization and tendinopathy, as well as increased overall joint stiffness in humans [1]. We have recently reported that the skin from the Db/Db diabetic mouse, a model of Type II Diabetes, as well as the skin from human diabetics, have impaired biomechanical properties compared to non-diabetic skin as the result of altered extracellular matrix composition. [2]. However, the mechanical properties of tendons from these animals have never been studied and could serve as a unique model of altered collagen structure as well as provide further understanding to the cause of tendinous injuries in the diabetic population. Therefore, the objective of this study is to measure the tensile mechanical properties and collagen fiber re-alignment in the db/db mouse model compared to non-diabetic controls. We hypothesize that tendon stiffness and modulus will be increased in the db/db group in the insertion site and midsubstance, and that db/db tendons will re-align earlier and faster during the testing protocol.

Lung tissue mechanics and extracellular matrix composition in a murine model of silicosis

2001 ◽  
Vol 90 (4) ◽  
pp. 1400-1406 ◽  
Author(s):  
Débora S. Faffe ◽  
Gabriela H. Silva ◽  
Pedro M. P. Kurtz ◽  
Elnara M. Negri ◽  
Vera L. Capelozzi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Lung Tissue ◽  
Elastic System ◽  
Elastic Fiber ◽  
Dynamic Mechanical Properties ◽  
Tissue Mechanics ◽  
Matrix Composition ◽  
Elastic Fibers ◽  
Oxytalan Fibers

The dynamic mechanical properties of lung tissue and its contents of collagen and elastic fibers were studied in strips prepared from mice instilled intratracheally with saline (C) or silica [15 (S15) and 30 days (S30) after instillation]. Resistance, elastance, and hysteresivity were studied during oscillations at different frequencies on S15 and S30. Elastance increased from C to silica groups but was similar between S15 and S30. Resistance was augmented from C to S15 and S30 and was greater in S30 than in S15 at higher frequencies. Hysteresivity was higher in S30 than in C and S15. Silica groups presented a greater amount of collagen than did C. Elastic fiber content increased progressively along time. This increment was related to the higher amount of oxytalan fibers at 15 and 30 days, whereas elaunin and fully developed elastic fibers were augmented only at 30 days. Silicosis led not only to pulmonary fibrosis but also to fibroelastosis, thus assigning a major role to the elastic system in the silicotic lung.

Mechanical Behavior and Toughness of Electrospun Polycaprolactone Nanofibers

2007 ◽  
Author(s):  
Avinash Baji ◽  
Shing-Chung Wong ◽  
Todd Blackledge ◽  
Darrell Reneker ◽  
Sureeporn Tripatanasuwan
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Electrospun Nanofibers ◽  
Electrospun Fibers ◽  
Essential Work ◽  
Essential Work Of Fracture ◽  
Strain Behavior ◽  
Strength And Stiffness ◽  
Work Of Fracture

This study examines the toughness and mechanical properties of biodegradable poly(ε-caprolactone) (PCL) with varying hydroxyapatite (HAP) content (0 – 30 wt%). Fracture toughness of HAP-filled PCL was also examined for the electrospun fibers using the essential work of fracture (EWF) concept. The electrospun fibers exhibited a diameter ranging from 200–500 nm and a combination of HAP particle sizes ranging from (50–100 nm) under the SEM. The tensile stress-strain behavior and fracture toughness of electrospun nanofibers were assessed using a nanoforce tensile tester. The electrospun system showed a substantial increase in plane-stress essential work of fracture in comparison to bulk specimens processed from pellets. Toughness decreased as HAP loading increased. The effect of simulated body fluid (SBF) on the mechanical properties was also studied. Mechanical properties including tensile strength and modulus were found to increase with HAP concentration in general. Compression molded electrospun nanofibers were spatially confined such that the tensile strength and stiffness of molded and spun fibers are remarkably higher than those from molded specimen of pellets.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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