scholarly journals Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles.

1976 ◽  
Vol 69 (2) ◽  
pp. 352-370 ◽  
Author(s):  
C Siu ◽  
H Swift ◽  
K Chiang
Keyword(s):  
Protein Synthesis ◽  
Structural Organization ◽  
Matrix Material ◽  
Limited Ability ◽  
Main Emphasis ◽  
The Matrix ◽  
Photosynthetic Mutants ◽  
Nuclear Genomes ◽  
Shape And Size

Electron microscope studies have been made on the fine structure of the colorless biflagellate, Polytoma obtusum, with main emphasis on the structural organization of the mitochondria and the leucoplast. Both organelles have been demonstrated to contain DNA aggregates as well as ribosomal particles within their matrix material. Reconstructions from serial showed that (a) the mitochondria were highly convoluted and irregular in shape and size, and (b) the leucoplast was a single cup-shaped entity, with large starch grains, localized at the posterior end, and multiple sites of DNA aggregates. The starch-containing compartments appeared to be interconnected by narrow tubular or sheetlike bridges. Cytoplasmic invaginations into the plastid, often containing mitochondria, were of frequent occurrence, and membranes of mitochondria and the leucoplast appeared to be closely apposed. Membranes elements, both sheetlike and vesicular, were also present in the matrix. The Polytoma leucoplast was, in certain respects, morphologically similar to the plastids of various photosynthetic mutants of Chlamydomonas, most of which show Menedelian segregation. It is suggested that Polytoma arose from a Chlamydomonas-like ancestor, possibly through combined mutational processess of both chloroplast and nuclear genomes. Since Polytoma leucoplasts contain both DNA and ribosomal particles, it is probable that these organelles still possess semiautonomy and limited ability for protein synthesis.

Mechanical Characterization of a Nanotube-Polyethylene Composite Material

Materials ◽  
2003 ◽  
Author(s):  
Michael H. Santare ◽  
Wenzhong Tang ◽  
John E. Novotny ◽  
Suresh G. Advani
Keyword(s):  
Wear Resistance ◽  
Carbon Nanotube ◽  
Matrix Material ◽  
Peak Load ◽  
Composite Films ◽  
Melt Processing ◽  
Polyethylene Composite ◽  
Punch Test ◽  
The Matrix

High-density polyethylene (HDPE) was used as the matrix material for a carbon nanotube (CNT) polymer composites. Multi-wall carbon nanotube composite films were fabricated using the melt processing method. Composite samples with 0%, 1%, 3% and 5% nanotube content by weight were tested. The mechanical properties of the films were measured by the small punch test and wear resistance was measured with a block-on-ring wear tester. Results show increases in the stiffness, peak load, work-to-failure and wear resistance with increasing nanotube content.

Mechanical characterization of hexagonal boron nitride nanocomposites: A multiscale finite element prediction

2017 ◽  
Vol 52 (16) ◽  
pp. 2229-2241 ◽  
Author(s):  
Konstantinos N Spanos ◽  
Nick K Anifantis
Keyword(s):  
Finite Elements ◽  
Boron Nitride ◽  
Load Transfer ◽  
Hexagonal Boron Nitride ◽  
Matrix Material ◽  
The Matrix ◽  
Multiscale Finite Element ◽  
Two Phases ◽  
Good Agreement

In this study, a calculation of the elastic mechanical properties of composite materials reinforced by boron nitride nanosheets is taking place, following the finite elements approach. Composites are specifically composed of two phases of materials, the matrix material and the reinforcing phase, here, consisting of boron nitride monolayers. The simulation of these two materials as well as the interface between them were made in accordance with the micromechanics theory, examining a representative volume element. Specifically, the matrix material is considered as continuous medium and the reinforcing phase, based on its atomistic microstructure, is considered as a discrete medium and was simulated through spring-based finite elements. Something similar occurred with the simulation of the interface region, which is responsible for the load transfer between the two materials. The results of the method were compared with data from other studies and showed good agreement.

Preparation and Characterization of Hybrid Aluminum Matrix Composites Reinforced with MWCNT Using Powder Metallurgy Process

2015 ◽  
Vol 813-814 ◽  
pp. 620-624
Author(s):  
S. Dhandapani ◽  
T. Rajmohan ◽  
K. Palanikumar ◽  
Charan Mugunthan
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Metal Matrix ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Nano Particles ◽  
Aluminum Matrix Composites ◽  
The Matrix ◽  
Carbon Nano Tubes

Metal Matrix Nano Composites (MMNC) consist of a metal matrix reinforced with nano-particles featuring physical and mechanical properties very different from those of the matrix. Especially carbon Nano tubes (CNT) can improve the matrix material in terms of wear resistance, damping properties and mechanical strength. The present investigation deals with the synthesis and characterization of aluminium matrix reinforced with micro B4C particles, and Multi Wall Carbon nano Tubes (MWCNT) were prepared by powder metallurgy route. Powder mixture containing fixed weight (%) of B4C and different wt% of MWCNT as reinforcement constituents that are uniaxial cold pressed and later green compacts are sintered in continues electric furnace. Microstructure and Mechanical properties such as micro hardness and density are examined. Micro structure of samples has been investigated using scanning electron microscope (SEM) .The results indicated that the increase in wt % of MWCNT improves the bonding and mechanical properties.

SYNTHESIS AND CHARACTERIZATION OF CARBON NANOTUBES REINFORCED POLYMER NANOCOMPOSITES

2009 ◽  
Vol 08 (03) ◽  
pp. 237-242 ◽  
Author(s):  
MOHAMED A. ETMAN ◽  
R. M. RASHAD ◽  
M. K. BEDEWY
Keyword(s):  
Carbon Nanotubes ◽  
Matrix Material ◽  
Morphological Characterization ◽  
Experimental Program ◽  
Enhancement Effect ◽  
Reinforced Polymer ◽  
The Matrix ◽  
Matrix Nanocomposites ◽  
Strength And Ductility

An experimental program was designed to synthesize and characterize carbon nanotubes (CNTs) and CNTs reinforced polymeric matrix nanocomposites. PMMA, and PS, matrices were adopted for this investigation using different percents of CNTs loading of 0, 1, 3, and 5 and wt%. Morphological characterization was carried out using SEM, TEM, and TEDM microscopy. Mechanical properties were also measured to evaluate the enhancement effect of the CNTs loading percent. The results revealed a remarkable enhancement of the strength and ductility of the matrix material at 3 wt% of reasonably dispersed CNTs.

Fibronectin-independent adhesion of fibroblasts to extracellular matrix material: partial characterization of the matrix components

1983 ◽  
Vol 63 (1) ◽  
pp. 287-301
Author(s):  
P.A. Harper ◽  
P. Brown ◽  
R.L. Juliano
Keyword(s):  
Extracellular Matrix ◽  
Matrix Material ◽  
Block Type ◽  
Type I ◽  
Type Ii ◽  
Matrix Component ◽  
Tyrosine Residues ◽  
The Matrix ◽  
Dependent Type

Fibroblasts can adhere to extracellular matrix (ECM) material by fibronectin-dependent (type I) and fibronectin-independent (type II) mechanisms. In this report we investigate the biochemical characteristics of ECM that contribute to type II adhesion. ECM capable of mediating type II adhesions is produced primarily by normal diploid fibroblasts, but not by transformed cells or epithelial cells. Treatment of fibroblast ECM under conditions that result in the removal of most of the ECM lipid or most of the ECM glycosaminoglycan does not impair type II adhesion. Likewise, treatment of the ECM with large amounts of purified collagenase does not block type II adhesion. However, treatment of ECM with low doses of trypsin or with an agent that reacts with tyrosine residues, results in complete ablation of the ability of the ECM to support type II adhesion. On the basis of these observations we suggest that the matrix component(s) mediating type II adhesion are non-collagenous proteins or glycoproteins.

Modeling and Characterization of Strain Sensing in CNT-Based Polymer Composites Under Tensile Loading

2012 ◽  
Author(s):  
Yu Kuronuma ◽  
Tomo Takeda ◽  
Yasuhide Shindo ◽  
Fumio Narita ◽  
Zhijuan Wei
Keyword(s):  
Polymer Composites ◽  
Electrical Resistance ◽  
Matrix Material ◽  
Tensile Loading ◽  
Tensile Tests ◽  
Tunneling Effect ◽  
Strain Sensing ◽  
Resistance Change ◽  
The Matrix

This paper presents a study on the strain sensing behavior of carbon nanotube (CNT)-based polymer composites subjected to tensile loading. Tensile tests were performed on CNT/polycarbonate composites and the responses in strain and electrical resistance were measured during the tests. An analytical model incorporating the electrical tunneling effect due to the matrix material between CNTs was also developed to predict the electrical resistance change resulted from deformation. The analytical predictions were compared with the experimental data.

Synthesis and Characterization of Hybrid Aluminum Composites Reinforced with Ni Particulates and Interconnected Fe Mesh

2006 ◽  
Vol 111 ◽  
pp. 39-42 ◽  
Author(s):  
W.L.Eugene Wong ◽  
Manoj Gupta ◽  
C.Y.H. Lim
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Pure Aluminum ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Hot Extrusion ◽  
Microstructural Characterization ◽  
Mechanical Analysis ◽  
The Matrix ◽  
Melt Deposition

In this study, pure aluminum reinforced with interconnected galvanized iron mesh and Ni particulates was synthesized using an innovative disintegrated melt deposition technique followed by hot extrusion. Microstructural characterization of composite samples showed uniform distribution of Ni and Al-Ni based intermetallic particulates in the matrix material, good interfacial integrity of aluminum matrix with iron mesh and Ni particulates and the presence of minimal porosity. Results of thermal mechanical analysis indicate a decrease in the average coefficient of thermal expansion of the aluminum matrix with the use of hybrid reinforcements. Mechanical characterization also revealed that the coupled use of galvanized iron mesh and Ni particulates lead to an improvement in the hardness, dynamic modulus, 0.2% yield strength and UTS but ductility was adversely affected. An attempt is made to correlate the use of hybrid reinforcements with the improved properties exhibited by the synthesized composites.

scholarly journals Characterization of γ′ Precipitates in Cast Ni-Based Superalloy and Their Behaviour at High-Homologous Temperatures Studied by TEM and in Situ XRD

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2397 ◽  
Author(s):  
Łukasz Rakoczy ◽  
Ondrej Milkovič ◽  
Bogdan Rutkowski ◽  
Rafał Cygan ◽  
Małgorzata Grudzień-Rakoczy ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Matrix Material ◽  
High Volume ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
In Situ Xrd ◽  
Transmission Electron ◽  
The Matrix

In situ X-ray diffraction and transmission electron microscopy has been used to investigate René 108 Ni-based superalloy after short-term annealing at high-homologous temperatures. Current work is focused on characterisation of γ′ precipitates, their volume fraction, evolution of the lattice parameter of γ and γ′ phases and misfit parameter of γ′ in the matrix. Material in the initial condition is characterised by a high-volume fraction (over 63%) of γ′ precipitates. Irregular distribution of alloying elements was observed. Matrix channels were strongly enriched in Cr, Co, W and Mo, whereas precipitates contain large amount of Al, Ti, Ta and Hf. Exposure to high-homologous temperatures in the range 1100–1250 °C led to the dissolution of the precipitates, which influenced the change of lattice parameter of both γ and γ′ phases. The lattice parameter of the matrix continuously grew during holding at high temperatures, which had a dominant influence on the more negative misfit coefficient.

Fabrication and Characterization of Pineapple Fiber-Reinforced Polypropylene Based Composites

2018 ◽  
Vol 21 ◽  
pp. 31-42 ◽  
Author(s):  
Mohammad Bellal Hoque ◽  
M. Sahadat Hossain ◽  
Abdul M. Nahid ◽  
Solaiman Bari ◽  
Ruhul A. Khan
Keyword(s):  
Bending Strength ◽  
Sodium Hydroxide Solution ◽  
Matrix Material ◽  
Group Analysis ◽  
Tensile Modulus ◽  
Elongation At Break ◽  
Bending Modulus ◽  
The Matrix ◽  
Functional Group Analysis

Pineapple Leaf Fiber (PALF)-reinforced polypropylene (PP) based composites were prepared successfully by conventional compression molding technique. Different percentages (25,30,35, 40 and 405% by weight) of fiber were used to prepare composites. Tensile Strength (TS), Tensile Modulus (TM), Elongation at Break (Eb %), Bending Strength (BS), Bending Modulus (BM) and Impact Strength (IS) were evaluated. The 45 wt% PALF/PP composite exhibited an increase of 132% TS, 412% TM, 155% BS, 265% BM, and 140% IS with respect to the matrix material (PP). Fourier Transform Infrared (FTIR) Spectroscopy was employed for functional group analysis of PALF/PP composites. For all percentages of fiber, the composites demonstrated lower water uptake. The fabricated composites were immersed in alkali solution (Sodium hydroxide solution, 3%, 5% and 7% by weight) for 60 min and showed low TS, TM and Eb% compared to control composites.

scholarly journals Resistance of concrete and expanded clay concrete under periodic external influences

2018 ◽  
Vol 230 ◽  
pp. 03021
Author(s):  
Valery Vyrovoy ◽  
Oksana Korobko ◽  
Vladimir Sukhanov ◽  
Yuri Zakorchemny
Keyword(s):  
Structure Formation ◽  
Concrete Structure ◽  
Structural Organization ◽  
Matrix Material ◽  
External Factors ◽  
Self Organization ◽  
Operating Environment ◽  
Active Elements ◽  
The Matrix ◽  
Operating Factor

The purpose of the work is to increase resistance of concrete in conditions of multiple freezing-thawing and wetting-drying cycles. An important property of concrete is its ability to adapt to the periodical effect of external factors by self-organization of the structure. It assumes the presence at the material of active elements capable of changing their parameters adequately to impacts. Such elements include cracks and inner surfaces of partition as integral elements of the structure of any material. Sets of active elements can be to obtained by directing the structural organization of concrete. The operating factor of structure formation can be a change in the ratio of adhesion and cohesive bonding forces at the surface of partition between the matrix material and the fillers. Concrete the structure of which was initiated by selective adhesion of a matrix to the surface of fillers differed in the raised values of properties. Structural potential has determined resistance of concrete at freezing-thawing and wetting-drying. Sets of active elements of concrete structure are the factors of safe functioning of building constructions in conditions of influence of the operating environment.

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