scholarly journals Diatom populations in an upwelling environment decrease silica content to avoid growth limitation

2018 ◽  
Vol 20 (11) ◽  
pp. 4184-4193 ◽  
Author(s):  
Heather M. McNair ◽  
Mark A. Brzezinski ◽  
Jeffrey W. Krause
Keyword(s):  
Silica Content ◽  
Growth Limitation

Effect of furnace atmosphere and silica content on the consolidation behaviour of magnesia partially stabilised zirconia

1990 ◽  
Vol 48 (4) ◽  
pp. 1056-1057
Author(s):  
J. Drennan ◽  
R.H.J. Hannink ◽  
D.R. Clarke ◽  
T.M. Shaw
Keyword(s):  
Liquid Phase ◽  
Silica Content ◽  
Liquid Phase Sintering ◽  
Furnace Atmosphere ◽  
Boundary Phase ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Series Of Experiments ◽  
Compositional Gradients ◽  
Mobile Liquid

Magnesia partially stabilised zirconia (Mg-PSZ) ceramics are renowned for their excellent nechanical properties. These are effected by processing conditions and purity of starting materials. It has been previously shown that small additions of strontia (SrO) have the effect of removing the major contaminant, silica (SiO2).The mechanism by which this occurs is not fully understood but the strontia appears to form a very mobile liquid phase at the grain boundaries. As the sintering reaches the final stages the liquid phase is expelled to the surface of the ceramic. A series of experiments, to examine the behaviour of the liquid grain boundary phase, were designed to produce compositional gradients across the ceramic bodies. To achieve this, changes in both silica content and furnace atmosphere were implemented. Analytical electron microscope techniques were used to monitor the form and composition of the phases developed. This paper describes the results of our investigation and the presentation will discuss the work with reference to liquid phase sintering of ceramics in general.

DIVERSITY AND DISTRIBUTION OF ORIBATID MITE FAUNA(ACARI: ORIBATIDA) IN THE FOREST FLOOR OF SATKOSIA BASIPALLY WILD LIFE SANCTUARY, ODISHA, INDIA

2017 ◽  
Vol 23 (1) ◽  
Author(s):  
SHELLEY ACHARYA ◽  
ADITI DUTTA
Keyword(s):  
Forest Floor ◽  
Dominant Species ◽  
Oribatid Mite ◽  
Soil Condition ◽  
Silica Content ◽  
Soil Mites ◽  
The Core ◽  
Humid Condition ◽  
Core Areas ◽  
Wild Life

The studies were mostly concentrated in Nine forest ranges of the WLS including the core areas. The soil of this region mostly is dry, red and with iron and silica content. Though the soil mites are prevalent in moist humid condition, we got a diversed population of 20 different species under 14 genera which is less than average probably due to the soil condition. Protoribates magnus is the dominant species in this study. The species with larger ranges were Scheloribates curvialatus.

Processing of granite quarry solid waste into industrial high silica materials using leaching process with HCl concentration variation

2020 ◽  
Vol 11 (2) ◽  
pp. 43-50
Author(s):  
Yusup Hendronursito ◽  
Muhammad Amin ◽  
Slamet Sumardi ◽  
Roniyus Marjunus ◽  
Frista Clarasati ◽  
...  
Keyword(s):  
Particle Size ◽  
Rotational Speed ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Silica Content ◽  
X Ray ◽  
Concentration Variation ◽  
Leaching Process ◽  
Hcl Concentration ◽  
Granite Powder

This study was aimed to increase granite's silica content using the leaching process with HCl concentration variation. The granite used in this study came from Lematang, South Lampung. This study aims to determine the effect of variations in HCl concentration, particle size, and rotational speed on the crystalline phase and chemical elements formed in the silica product produced from granite. The HCl concentration variations were 6.0 M, 7.2 M, 8.4 M, and 9.6 M, the variation in particle size used was 270 and 400 mesh. Variations in rotational speed during leaching were 500 and 750 rpm. Granite powder was calcined at 1000 ºC for 2 hours. Characterization was performed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP- OES). The results showed that the silica content increased with increasing HCl concentration, the finer the particle size, and the higher the rotational speed. XRF analysis showed that the silica with the highest purity was leached with 9.6 HCl with a particle size of 400 mesh and a rotational speed of of 750 rpm, which was 73.49%. Based on the results above, by leaching using HCl, the Si content can increase from before. The XRD diffractogram showed that the granite powder formed the Quartz phase.

IN-VITRO BEHAVIOUR OF BIPHASIC CALCIUM PHOSPHATE WITH DIFFERENT RATIO OF SILICA CONTENT IN SIMULATED BODY FLUID

2015 ◽  
Vol 23 (1) ◽  
pp. 1-14
Author(s):  
Sudirman Sahid ◽  
◽  
Nor Shahida Kader Bashah ◽  
Salina Sabudin ◽  
◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Biphasic Calcium Phosphate ◽  
Silica Content

A Theory of Growth Limitation

1953 ◽  
Vol 87 (834) ◽  
pp. 139-153 ◽  
Author(s):  
Gairdner B. Moment
Keyword(s):  
Growth Limitation

Exploring SiC Growth Limitation of Vapor-Liquid-Solid Mechanism when Using Two Different Carbon Precursors

2013 ◽  
Vol 740-742 ◽  
pp. 323-326
Author(s):  
Kassem Alassaad ◽  
François Cauwet ◽  
Davy Carole ◽  
Véronique Soulière ◽  
Gabriel Ferro
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Carbon Precursor ◽  
Growth Limitation ◽  
Vapor Liquid Solid ◽  
Partial Pressures ◽  
Vapor Liquid Solid Mechanism ◽  
Vls Growth ◽  
Vapor Liquid

Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.

Silica Content of a Mesohaline Tidal Marsh in North Carolina

1999 ◽  
Vol 49 (4) ◽  
pp. 597-605 ◽  
Author(s):  
A.R. Norris ◽  
C.T. Hackney
Keyword(s):  
North Carolina ◽  
Tidal Marsh ◽  
Silica Content

Preparation of Raspberry-Like Polymer/Silica Composite Particles through Cationic Soap-Free Emulsion Polymerization

2012 ◽  
Vol 476-478 ◽  
pp. 1408-1411
Author(s):  
Xin Fan ◽  
Qiu Ju Qin ◽  
Xiu Fang Wen ◽  
Jiang Cheng ◽  
Zhuo Ru Yang
Keyword(s):  
Emulsion Polymerization ◽  
Silica Content ◽  
Silica Particles ◽  
Vital Role ◽  
Silica Sol ◽  
Electrostatic Attraction ◽  
Composite Particles ◽  
Silica Composite ◽  
Soap Free Emulsion Polymerization

In this paper raspberry-like composite particles were prepared via cationic soap-free emulsion polymerization with silica sol as stabilizer and 2-(methacryloyl) ethyltrimethylammonium chloride (MTC) as cationic auxiliary monomer. According to the TGA and TEM results we could find that the electrostatic attraction supplied by MTC played a vital role in the adsorption of silica particles as well as the generation of raspberry-like morphology. The silica content and appearance of composite particles were found to be improved with the increasing amount of silica sol and MTC while varied little with changes of AIBA amount.

Mechanical and microstructural properties of polystyrene based composites: positron lifetime spectroscopic and DSC studies

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Abdullah Mohammed Ali Mohammed Altaweel ◽  
Jaya Madhu Raj ◽  
Malalvalli Nagarajaiah Chandrashekara ◽  
Puttegowda Ramya ◽  
Parthasarathy Sampathkumaran ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Free Volume ◽  
Positron Lifetime ◽  
Tensile Modulus ◽  
Silica Content ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Microstructural Property ◽  
Calcium Aluminosilicate

Abstract Polystyrene (PS) based composites respectively with cenosphere (CS) and calcium aluminosilicate (CAS) as fillers were studied using the positron lifetime technique to reveal the correlation between free volume, a microstructural property, and mechanical properties of the composites (tensile strength and tensile modulus). The thermal stability of the composites was determined using differential scanning calorimetry. The results showed that addition of CAS filler lead to a significant improvement in the mechanical properties of the composite, whereas addition of CS resulted in improvement in tensile modulus only. Both PS/CAS and PS/CS composites showed enhancement in thermal stability compared with that of the pure PS matrix. The positron results showed that the average free volume size for the PS/CAS composite (at 40 phr CAS) was reduced significantly compared with that of the pure PS. These results are understood in terms of the influence of silica content, filler-matrix interaction, and particle size.

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