Low-T formation of high-Cr spinel with apparently primary chemical characteristics within podiform chromitite from Rayat, northeastern Iraq

2006 ◽  
Vol 70 (5) ◽  
pp. 499-508 ◽  
Author(s):  
S. Arai ◽  
Y. Shimizu ◽  
S. A. Ismail ◽  
A. H. Ahmed
Keyword(s):  
Chemical Properties ◽  
Chromian Spinel ◽  
Chemical Characteristics ◽  
Silicate Matrix ◽  
Mantle Origin ◽  
Ophiolitic Mélange ◽  
Magnesian Olivine ◽  
The Matrix ◽  
Detrital Particles ◽  
Podiform Chromitite

AbstractChemical modification of chromian spinel at low-T alteration was examined in detail for a podiform chromitite from a Tethyan ophiolitic mélange belt at Rayat, northeastern Iraq. The chromitite is highly brecciated and the matrix has been completely altered, producing chlorite and carbonate (dolomite and calcite). High-Cr, low-Fe3+ spinel has formed along the margins and cracks of chromian spinel grains throughout the alteration, associated with unaltered primary spinel and magnetite without ferritchromite. In associated harzburgites, only ferritchromite is found instead of the high-Cr, low-Fe3+ spinel. The high-Cr, low-Fe3+ secondary spinel apparently has chemical properties of mantle origin, plotted at the extension of ordinary mantle spinels on compositional spaces. The character is due to subtraction of Al as chlorite with the addition of an amount of magnetite component from the silicate matrix, which is small in volume relative to peridotite and composed of highly magnesian olivine (up to Fo97). We should treat high-Cr chromian spinels with caution in highly altered mantle-derived rocks, especially chromitite and other rocks with highly magnesian olivine, as well as in detrital particles for provenance study.

The microstructure of a TiB2/Ti-47 Al composite material

1989 ◽  
Vol 47 ◽  
pp. 674-675
Author(s):  
O. Popoola ◽  
A.H. Heuer ◽  
P. Pirouz
Keyword(s):  
Composite Material ◽  
Ion Beam ◽  
Chemical Properties ◽  
Intermetallic Alloys ◽  
Transmission Electron ◽  
Diamond Polishing ◽  
Al Composite ◽  
The Matrix ◽  
Argon Ion ◽  
And Chemical Properties

The addition of fibres or particles (TiB2, SiC etc.) into TiAl intermetallic alloys could increase their toughness without compromising their good high temperature mechanical and chemical properties. This paper briefly discribes the microstructure developed by a TiAl/TiB2 composite material fabricated with the XD™ process and forged at 960°C.The specimens for transmission electron microscopy (TEM) were prepared in the usual way (i.e. diamond polishing and argon ion beam thinning) and examined on a JEOL 4000EX for microstucture and on a Philips 400T equipped with a SiLi detector for microanalyses.The matrix was predominantly γ (TiAl with L10 structure) and α2(TisAl with DO 19 structure) phases with various morphologies shown in figure 1.

scholarly journals Formulation and evaluation of bi-layer floating tablets of ziprasidone HCl and trihexyphenidyl HCl

2011 ◽  
Vol 47 (3) ◽  
pp. 545-553 ◽  
Author(s):  
Sathis Kumar Dinakaran ◽  
Santhos Kumar ◽  
David Banji ◽  
Harani Avasarala ◽  
Venkateshwar Rao
Keyword(s):  
Sustained Release ◽  
In Vitro Release ◽  
Chemical Properties ◽  
Matrix Tablets ◽  
In Vitro Dissolution ◽  
Floating Tablets ◽  
Ir Studies ◽  
Weight Variation ◽  
The Matrix

The purpose of this research study was to establish ziprasidone HCl NR 40 mg and trihexyphenidyl HCl SR 4mg in the form of bi-layer sustained release floating tablets. The tablets were prepared using sodium HPMC K4M / HPMC K15M as bio-adhesive polymers and sodium bicarbonate acting as a floating layer. Tablets were evaluated based on different parameters such as thickness, hardness, friability, weight variation, in vitro dissolution studies, content of active ingredient and IR studies. The physico-chemical properties of the finished product complied with the specifications. In vitro release from the formulation was studied as per the USP XXIII dissolution procedure. The formulations gave a normal release effect followed by sustained release for 12 h which indicates bimodal release of ziprasidone HCl from the matrix tablets. The data obtained was fitted to Peppas models. Analysis of n values of the Korsmeyer equation indicated that the drug release involved non-diffusional mechanisms. By the present study, it can be concluded that bi-layer tablets of ziprasidone HCl and trihexyphenidyl HCl will be a useful strategy for extending the metabolism and improving the bioavailability of Ziprasidone HCl and Trihexyphenidyl HCl.

scholarly journals Effect of the Matrix on the 1.5μm Photoluminescence of Er-Doped Silicon Quantum Dots

2006 ◽  
Vol 514-516 ◽  
pp. 1116-1120 ◽  
Author(s):  
M.Fátima Cerqueira ◽  
Margarita Stepikhova ◽  
Maria Losurdo ◽  
Teresa Monteiro ◽  
Manuel J. Soares ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Nanocrystalline Silicon ◽  
Raman Spectroscopic ◽  
Silicon Thin Films ◽  
Erbium Ions ◽  
Deposition Parameters ◽  
Composition And Structure ◽  
The Matrix ◽  
Er Doped ◽  
The Impact

Erbium doped nanocrystalline silicon thin films were produced by reactive magnetron r.f. sputtering. Their structural and chemical properties were studied by micro-Raman, spectroscopic ellipsometry and Rutherford backscattering spectroscopy. Films with different crystalline fraction and crystallite size were deposited by changing the deposition parameters. The impact of the composition and structure of Erbium ions environment on the 1.5 µm photoluminescence is discussed.

scholarly journals Extracted Compounds from Neem Leaves as Antimicrobial Agent on the Physico-Chemical Properties of Seaweed-Based Biopolymer Films

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1119 ◽  
Author(s):  
U. Seeta Uthaya Kumar ◽  
S. N. Abdulmadjid ◽  
N. G. Olaiya ◽  
A. A. Amirul ◽  
S. Rizal ◽  
...  
Keyword(s):  
Gamma Irradiation ◽  
Water Solubility ◽  
Composite Films ◽  
Chemical Properties ◽  
Antimicrobial Activities ◽  
Vapour Permeability ◽  
Control Film ◽  
Biocomposite Films ◽  
Neem Leaves ◽  
The Matrix

Neem leaves extract was incorporated into the matrix of seaweed biopolymer, and the seaweed-neem biocomposite films were irradiated with various doses of gamma irradiation (0.5, 1.5, 2.5, 3.5, and 4.5 kGy). The physical, barrier, antimicrobial, and mechanical properties of the films were studied. The incorporation of 5% w/w neem leaves extract into a seaweed-based film, and gamma irradiation dose of 2.5 kGy was most effective for improved properties of the film. The results showed that the interfacial interaction of the seaweed-neem improved with physical changes in colour and opacity. The water solubility, moisture content, and water vapour permeability and biodegradability rate of the film reduced. The contact angle values increased, which was interpreted as improved hydrophobicity. The tensile strength and modulus of the films increased, while the elongation of the composite films decreased compared to the control film. The film’s antimicrobial activities against bacteria were improved. Thus, neem leaves extract in combination with the application of gamma irradiation enhanced the performance properties of the film that has potential as packaging material.

scholarly journals Improving Interaction at Polymer–Filler Interface: The Efficacy of Wrinkle Texture

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 208 ◽  
Author(s):  
Pietro Russo ◽  
Virginia Venezia ◽  
Fabiana Tescione ◽  
Joshua Avossa ◽  
Giuseppina Luciani ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Effective Properties ◽  
Chemical Properties ◽  
Poly Lactic Acid ◽  
Physical Interaction ◽  
Chemical Surface ◽  
Surface Areas ◽  
Polymer Filler ◽  
The Matrix ◽  
Modified Stöber Method

One of the main issues in preparing polymer-based nanocomposites with effective properties is to achieve a good dispersion of the nanoparticles into the matrix. Chemical interfacial modifications by specific coupling agents represents a good way to reach this objective. Actually, time consuming compatibilization procedures strongly compromise the sustainability of these strategies. In this study, the role of particles’ architectures in their dispersion into a poly-lactic acid matrix and their subsequent influences on physical-chemical properties of the obtained nanocomposites were investigated. Two kinds of silica nanoparticles, “smooth” and “wrinkled,” with different surface areas (≈30 and ≈600 m2/g respectively) were synthesized through a modified Stöber method and used, without any chemical surface pre-treatments, as fillers to produce poly-lactic acid based nanocomposites. The key role played by wrinkled texture in modifying the physical interaction at the polymer-filler interface and in driving composite properties, was investigated and reflected in the final bulk properties. Detailed investigations revealed the presence of wrinkled nanoparticles, leading to (i) an enormous increase of the chain relaxation time, by almost 30 times compared to the neat PLA matrix; (ii) intensification of the shear-thinning behavior at low shear-rates; and (iii) slightly slower thermal degradation of polylactic acid.

Preparation and Dielectric Property of Al2O3 Surface Coating Modified BaTiO3/Polyimide Composite Film

2014 ◽  
Vol 908 ◽  
pp. 63-66
Author(s):  
Ya Jun Wang ◽  
Xiao Juan Wu ◽  
Chang Gen Feng
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Composite Film ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Chemical Properties ◽  
Dielectric Strength ◽  
Xrd Analysis ◽  
Nanocomposite Films ◽  
The Matrix

Polyimide (PI) was chosen as the matrix of the composite, barium titanate/polyimide (BT/PI) nanocomposite films were prepared by in situ polymerization. In order to improve the dispersion and the physical-chemical properties of BT surface, barium titanate was modified by Al2O3coating and modified BT/PI nanocomposite films were prepared. The prepared modified BT was characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of the composites were characterized in detail. It was shown that surface modification with Al2O3is the chemical process and there were new substances forming. When BT was modified by 10 wt% Al2O3, the dielectric constant of the composite film was 18.96 (103Hz), the loss tangent 0.005, breakdown strength 70 MV·m-1, energy storage density 0.41 J·cm-3. The dielectric constant of BT modified by Al2O3is decreased while the dielectric strength of the modified BT/PI composite film is increased.

Laboratory Study of Corrosion of an Alumina Refractory by Molten Potassium Salts

2010 ◽  
Vol 70 ◽  
pp. 65-71 ◽  
Author(s):  
Na Li ◽  
Leena Hupa ◽  
Patrik Yrjas ◽  
Mikko Hupa
Keyword(s):  
Cross Sections ◽  
Molar Ratio ◽  
Biomass Combustion ◽  
Silicate Matrix ◽  
Potassium Salts ◽  
Scale Method ◽  
Matrix Layer ◽  
The Matrix ◽  
Alumina Refractory ◽  
Refractory Surface

The increasing use of biomass and waste derived fuels in combustion challenges the chemical durability of refractories. Durability of an alumina refractory was studied in a chemically aggressive environment. A mixture of potassium chloride and carbonate (molar ratio 1:9) was placed on the sample and heated at 700-1000°C in an electric laboratory furnace in air for one week. Cross-sections of the samples were studied by SEM-EDXA to determine penetration of potassium in the refractory. Potassium was found only in the silicate matrix phase of the alumina refractory. Penetration of potassium decreased steeply from the surface to 1 mm, after which the decrease was linear but varied with temperature. At 700 and 800°C the thickness of the matrix layer that had reacted with potassium was 3 mm, while the layer was thinner at 900 and 1000°C. At the higher temperatures a glassy layer consisting of K2O, Na2O, CaO and SiO2 formed on the refractory surface. At 900°C the thickness of the surface layer was of 10μm, while a 200μm layer was measured at 1000°C. The procedure used in this work can be used to develop a laboratory scale method to be used to study corrosion of refractories in biomass combustion devices.

scholarly journals DESIGN AND CHARACTERISATION OF TRANSDERMAL PATCHES OF PHENFORMIN HYDROCHLORIDE

2017 ◽  
Vol 9 (6) ◽  
pp. 90
Author(s):  
Pratik Swarup Das ◽  
Puja Saha
Keyword(s):  
Drug Release ◽  
Diffusion Mechanism ◽  
Skin Irritation ◽  
In Vitro Release ◽  
Chemical Properties ◽  
In Vitro Dissolution ◽  
Release Mechanism ◽  
Transdermal Patches ◽  
The Matrix

Objective: In present work was designed to develop suitable transdermal matrix patches of Phenformin hydrochloride using various hydrophilic (HPMC) and hydrophobic (EUDRAGID) polymers as matrix formers.Methods: Transdermal patches containing Phenformin hydrochloride were prepared by the solvent casting evaporation technique.Results: Revealed that prepared patches showed good physical characteristics, no drug-polymer interaction and no skin irritation was observed. The in vitro release study revealed that F3 formulation showed maximum release in 24 h. Formulation F3 was subjected for accelerated stability studies. The F3 formulation was found to be stable as there was no drastic change in the Physico-chemical properties of the patches, which was also confirmed by FTIR.Conclusion: Thus conclusion can be made that stable transdermal patches of Phenformin hydrochloride has been developed. F1, F2, F3, F4 formulations showed highest cumulative percentage drug release of 98.13%, 95.50%, 98.65%, 97.21% were obtained during in vitro drug release studies after 24 h. The release of Phenformin hydrochloride appears to be dependent on lipophilicity of the matrix. Moderately lipophillic matrices showed best release. The predominant release mechanism of drug through the fabricated matrices was believed to be by diffusion mechanism. Based upon the in vitro dissolution data the F3 formulation was concluded as optimized formulation.

Investigation of Tensile Property of Aluminium SiC Metal Matrix Composite

2015 ◽  
Vol 766-767 ◽  
pp. 252-256 ◽  
Author(s):  
A. Siddique Ahmed Ghias ◽  
B. Vijaya Ramnath
Keyword(s):  
Composite Material ◽  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Matrix Material ◽  
Chemical Properties ◽  
High Strength ◽  
Stir Casting ◽  
The Matrix ◽  
Hybrid Metal Matrix Composite

The composite material is a combination of two or more materials with different physical and chemical properties. The composite has superior characteristics than those individual components. A hybrid composite is the one which contains at least three materials. When the matrix material is a metal, the composite is termed as metal matrix composites (MMC). The MMC is a composite material with two constituent parts, one being a metal. The other material may be another metal, ceramic or fiber. Among all the MMC’s, Aluminium is the most widely used matrix material due to its light weight, high strength and hardness. This paper deals with the fabrication and mechanical investigation of hybrid metal matrix composite Al - SiC. The fabrication is done by stir casting by adding the required quantities of additives into the stirred molten Aluminium. The results show significant effect of mechanical properties such as tensile strength, yield stress and flexural strength. The internal structure of the composite is observed using Scanning electron microscope (SEM) and found that are formation of pores in them.

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