scholarly journals The Influence of Graphene Nano-Particles on the Biological Interest of Polyvinyl Alcohol Nanocomposites

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Mahmoud A Hussein
Keyword(s):  
Polyvinyl Alcohol ◽  
Nano Particles ◽  
Biological Interest

scholarly journals Fabrication and Characterisation of Titanium Dioxide (Tio2)/PVA Nanofibre Composites using Electrospinning

2019 ◽  
Vol 7 (4.14) ◽  
pp. 348
Author(s):  
N. D.N. Affandi ◽  
L. Y. Chin ◽  
F. Fadil ◽  
F. A. Azhar
Keyword(s):  
Titanium Dioxide ◽  
Polyvinyl Alcohol ◽  
Research Work ◽  
Fibre Diameter ◽  
Control Sample ◽  
Morphological Structure ◽  
Nano Particles ◽  
Membrane Area ◽  
Membrane Surfaces ◽  
Pva Solutions

A study on the formation of titanium dioxide (TiO2)/ polyvinyl alcohol (PVA) nanofibres has been investigated in the research work. In the study, the TiO2/PVA solutions were prepared at different concentrations ranging from 1wt% to 10wt%. The PVA solution without TiO2 was used as control sample in the study. Each solution was extruded using electrospinning at different voltages to form long and continuous nanofibres. The fibres were then characterised for morphological structures, fibre diameter and membrane area. The result shows that control sample of PVA nanofibres formed beads on the fibre surfaces. The addition of TiO2 in PVA was found to reduce the bead formation. The clumps of TiO2 nanoparticles were observed and were also confirmed with the EDX mapping. In addition, the electrospinning parameters affect the formation of TiO2/PVA nanofibers. At 15 kV, the resultant fibre diameter increases from 153 ± 23 nm to 191 ± 26 nm when the TiO2 concentration was further increased from 1wt% to 10wt%. The morphological structure of TiO2/PVA nanofibres varies depending on applied voltages and concentrations used. The membrane area of TiO2/PVA nanofibers is approximately 187 cm2 for 1wt% of TiO2. From the study, it shows that an optimalconcentration to produce TiO2/ PVA nanofibers is 10wt%. At 10wt%, no beads were observed on the fibre and the TiO2 nano-particles were uniformly distributed on the membrane surfaces.  

scholarly journals Fabrication and Characterization of Nano Hybrid Cellulose Acetate-nanoTiO2/crosslinked Polyvinyl Alcohol Coated Membrane for Crude Clove Oil Purification

2019 ◽  
Vol 64 (3) ◽  
pp. 304-319
Author(s):  
Tutuk Djoko Kusworo ◽  
Widayat Widayat ◽  
Dani Puji Utomo
Keyword(s):  
Polyvinyl Alcohol ◽  
Cellulose Acetate ◽  
Membrane Surface ◽  
Polymer Concentration ◽  
Nano Particles ◽  
Inversion Method ◽  
Cellulose Acetate Membrane ◽  
Clove Oil ◽  
Oil Purification ◽  
Coated Membrane

The application of membranes for clove oil purification has the potential to improve the efficiency and effectiveness of processing. The main problem that occurs is the polymer-based membranes tend to change in properties such as weakening, dissolving, and swelling when contact with clove oil. In this study, cellulose acetate membrane was developed with TiO2 nano-particles to reduce swelling effect and coating with polyvinyl alcohol (PVA) to modify membrane surface. The membranes were prepared using dry-wet phase inversion method from dope solution with polymer concentration of 14–20 wt% and nano-particles of TiO2 with a concentration of 0–1.5 wt% in total solid. The formed membrane was coated with PVA with a concentration of 2–5 wt% crosslinked using glutaraldehyde. The SEM results show that prepared membrane are asymmetric membranes and show the coated layer of PVA on the surface. The FTIR spectra confirm that the PVA is successfully crosslinked and the addition of nano-particles TiO2 decreases the membrane swelling degree, significantly. In the addition of 0.5 wt% of nano-TiO2 can increase the flux from 0.54 to 0.66 L × m−2 × h−1 × bar−1. The coated membrane surface using PVA increases the selectivity of the membrane to produce clove oil permeates with eugenol content of 82.5 % from 68 %.

scholarly journals Preparation and Performance of Antibacterial Polyvinyl Alcohol/Polyethylene Glycol/Chitosan Hydrogels Containing Silver Chloride Nanoparticles via One-step Method

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 972 ◽  
Author(s):  
Gang Li ◽  
Daohai Zhang ◽  
Shuhao Qin
Keyword(s):  
Mechanical Properties ◽  
Antibacterial Activity ◽  
Polyethylene Glycol ◽  
Polyvinyl Alcohol ◽  
Silver Chloride ◽  
Silver Ions ◽  
Nano Particles ◽  
High Water Content ◽  
Glycol Chitosan ◽  
Antibacterial Materials

Silver nano-particles (AgNPs)-filled antibacterial materials have been widely employed in the fields of biology and biomedicine. However, AgNPs have shown obvious cytotoxicity. Hence it is more reasonable to use silver chloride nanoparticles (AgCl NPs) to prepare antibacterial materials due to the slow release of silver ions created by AgCl NPs formed in the chitosan. In this experiment, a useful antibacterial hydrogel for skin repairation was prepared by exploring the relationship between AgCl NPs and cytotoxicity. It is worth noting that the crosslinked network structure was successfully obtained in an antibacterial AgCl/PVA (Polyvinyl alcohol)/PEG (Polyethylene glycol)/CS (Chitosan) hydrogel materials by the hydrothermal method. In detail, the dynamic particle size distribution of AgCl NPs was relatively uniform, which is analyzed by a dynamic light scattering (DLS). The internal structure of the lyophilized hydrogel showed obvious porous structure, indicating that the hydrogel had high water content. The result of X-ray photoelectron spectroscopy (XPS) confirmed the existence of a silver element. The release concentration of silver ions was analyzed by inductively coupled plasma (ICP) to study the effect of silver ions release concentration on the antibacterial activity and cytotoxicity of hydrogel. The results show that the lower concentration of silver ions can make the hydrogel have good antibacterial activity and low cytotoxicity. The bacteriostatic rate of the antibacterial hydrogel was over 90%. Simultaneously, the mechanical properties test shows that the hydrogel has good mechanical properties, which can be widely used as an antibacterial material.

scholarly journals Shielding Properties Enhancement of Bentonite Clay Nano Particles Coated by Polyvinyl Alcohol Polymer

2021 ◽  
Author(s):  
Fawzy Hammad Sallam ◽  
Eman Mohamed Ibrahim ◽  
Sayed Fahmy Hassan ◽  
Ahmed Omar
Keyword(s):  
Particle Size ◽  
Polyvinyl Alcohol ◽  
Attenuation Coefficient ◽  
Bentonite Clay ◽  
Mass Attenuation Coefficient ◽  
Nano Particles ◽  
Calcination Process ◽  
Beam Transmission ◽  
Xrd Patterns ◽  
Mass Attenuation

Abstract Calcination process is a method used for gamma rays mass attenuation coefficient enhancement of natural bentonite clay nano-particles. This process eliminates water and organic matter from bentonite clay structure which have low mass attenuation coefficient values. There are two opposite effects on mass attenuation coefficient values; oxides content increases after calcination process which enhances mass attenuation coefficient values and particle size of calcinated bentonite increases which decreases mass attenuation coefficient values. In order to enhance mass attenuation coefficient value for natural bentonite, a physical ball milling must introduced after calcination process that decreases particle size. Calcination process is done at 700 ̊C for two hours because dehydration is completed above 500 ˚C while dehydroxylation observed at 700 ˚C. Mass attenuation coefficients are measured for calcinated and ball milled bentonite clay at different energies (662, 1173 and 1332 keV) and different pressing pressures (50, 100 and 150 bar). Narrow beam transmission technique and two different sources (Cs-137 and Co-60) are used for mass attenuation coefficient measurements, also particle size are measured by two different methods dynamic light scattering and Williamson-Hall size analyses using XRD patterns. All samples are coated by polyvinyl alcohol polymer.

Effect of Nano-Particle on Durability of Polyvinyl Alcohol Fiber Reinforced Cementitious Composite

2020 ◽  
Vol 12 (2) ◽  
pp. 249-262 ◽  
Author(s):  
Peng Zhang ◽  
Qingfu Li ◽  
Juan Wang ◽  
Yan Shi ◽  
Yuanxun Zheng ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Nano Particles ◽  
Nano Particle ◽  
Cementitious Composite ◽  
Fiber Reinforced ◽  
Cracking Resistance ◽  
Flow Measurements ◽  
Carbonation Resistance ◽  
Pva Fiber

In this study, the influence of nano-particle on flowability and durability of polyvinyl alcohol (PVA) fibers reinforced cementitious composite containing fly ash was evaluated. In the cementitious composite, Portland cement was replaced with 1.0%, 1.5%, 2.0% and 2.5% (by weight) of nano-particles. Two kinds of nano-particle of SiO2 and CaCO3 nano-particles were adopted in this study. PVA fibers were incorporated to the composite at a dosage of 0.9% (by volume). The flowability of the fresh cementitious composite was assessed using slump flow measurements. The durability of hardened cementitious composite includes carbonation resistance, permeability resistance, cracking resistance as well as freezing-thawing resistance, which were evaluated by the depth of carbonation, the water permeability height, cracking resistance ratio of the specimens, and relative dynamic elastic modulus of samples after freeze-thaw cycles, respectively. Our results showed incorporation of nano-particles had a little disadvantageous effect on flowability of PVA fiber reinforced cementitious composite, and the flowability of the fresh mixtures decreased with increases in the nano-particles content. The decrease in flowability of cementitious composite resulted by nano-SiO2 particles is more remarkable than nano-CaCO3 particles. The addition of both nano-SiO2 and nano-CaCO3 particles significantly improved the durability of PVA fiber reinforced cementitious composite. However, the improvement of nano-SiO2 on durability is much better than that of nano-CaCO3. When the amount of SiO2 nano-particle was less than 2.5%, the durability of cementitious composites increased with nano-SiO2 content. The microstructure of PVA fiber reinforced cementitious composite becomes much denser due to filler effect of nano-particle and generation of particles of hydrated products C–S–H gels. Both of SiO2 and CaCO3 nano-particle improved the microstructure of PVA fiber reinforced cementitious composite, and nano-SiO2 particles might be more beneficial for PVA fibers to play the role of reinforcement than nano-CaCO3 particles in the composites.

Immunocytochemistry. A Review of Methodology for Electron Microscopic Applicaiton

1974 ◽  
Vol 32 ◽  
pp. 328-329
Author(s):  
Joseph E. Mazurkiewicz
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Ultrastructural Level ◽  
Electron Microscopic ◽  
Biological Interest ◽  
Investigative Approach ◽  
Immunologic Activity ◽  
Dense Label

Immunocytochemistry is a powerful investigative approach in which one of the most exacting examples of specificity, that of the reaction of an antibody with its antigen, isused to localize tissue and cell specific molecules in situ. Following the introduction of fluorescent labeled antibodies in T950, a large number of molecules of biological interest had been studied with light microscopy, especially antigens involved in the pathogenesis of some diseases. However, with advances in electron microscopy, newer methods were needed which could reveal these reactions at the ultrastructural level. An electron dense label that could be coupled to an antibody without the loss of immunologic activity was desired.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

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