NMR study of Q-speciation and connectivity in K2O–SiO2 glasses with high silica content

2003 ◽  
Vol 331 (1-3) ◽  
pp. 100-107 ◽  
Author(s):  
S. Sen ◽  
R.E. Youngman
Keyword(s):  
Silica Content ◽  
High Silica Content ◽  
Nmr Study ◽  
High Silica

Synthesis and bioactivity assessment of high silica content quaternary glasses with Ca: P ratios of 1.5 and 1.67, made by a rapid sol-gel process

2017 ◽  
Vol 106 (2) ◽  
pp. 510-520 ◽  
Author(s):  
Basam A. E. Ben-Arfa ◽  
Hugo R. Fernandes ◽  
Isabel M. Miranda Salvado ◽  
José M. F. Ferreira ◽  
Robert C. Pullar
Keyword(s):  
Sol Gel ◽  
Silica Content ◽  
High Silica Content ◽  
Sol Gel Process ◽  
High Silica

scholarly journals Survey on the chemical composition of several tropical wood species

2019 ◽  
Vol 342 ◽  
Author(s):  
Jean Gérard ◽  
Sébastien Paradis ◽  
Bernard Thibaut
Keyword(s):  
Chemical Composition ◽  
Lignin Content ◽  
Silica Content ◽  
Ash Content ◽  
Hot Water ◽  
Mean Values ◽  
High Silica Content ◽  
Distribution Of Values ◽  
High Silica ◽  
Very High

Variability in the chemical composition of 614 species is described in a database containing measurements of wood polymers (cellulose, lignin and pentosan), as well as overall extraneous components (ethanol-benzene, or hot water extracts and ash, with a focus on silica content). These measurements were taken between 1945 and 1990 using the same standard protocol. In all, 1,194 trees belonging to 614 species, 358 genera and 89 families were measured. At species level, variability (quantified by the coefficient of variation) was rather high for density (27%), much lower for lignin and cellulose (14% and 10%) and much higher for ethanol/benzene extractives, hot water extractives and ash content (81%, 60% and 76%). Considering trees with at least five different specimens, and species with at least 10 different trees, it was possible to investigate within-tree and within-species variability. Large differences were found between trees of a given species for extraneous components, and more than one tree should be needed per species. For density, lignin, pentosan and cellulose, the distribution of values was nearly symmetrical, with mean values of 720 kg/m3 for density, 29.1% for lignin, 15.8% for pentosan, and 42.4% for cellulose. There were clear differences between species for lignin content. For extraneous components, the distribution was very dissymmetrical, with a minority of woods rich in this component composing the high value tail. A high value for any extraneous component, even in only one tree, is sufficient to classify the species in respect of that component. Siliceous woods identified by silica bodies in anatomy have a very high silica content and only those species deserve a silica study.

Co-Pyrolysis of Rice Husk and Chicken Manure

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Juan Espindola ◽  
Osama M. Selim ◽  
Ryoichi S. Amano
Keyword(s):  
Rice Husk ◽  
Minimum Energy ◽  
Synergetic Effect ◽  
Silica Content ◽  
Chicken Manure ◽  
Mixing Ratio ◽  
Production Scale ◽  
High Silica Content ◽  
Direct Combustion ◽  
High Silica

Abstract The increase in the production scale of chicken causes an increment in the produced manure. Chicken manure is considered an excellent soil amendment due to the high nitrogen and phosphorous content. However, the high production of manure exceeds the soil requirements. Rice husk is a by-product of rice production. Approximately one hundred forty million tons of rice husk is produced per year worldwide. There are several ways to manage rice husk such as animal bedding, direct combustion, or as a soil fertilizer. The husk's ashes are suitable for construction or as reinforcing material due to the high silica content. However, rice husk has a low volatile matter and high silica content, which makes processes like direct combustion inefficient. Thermochemical processes (such as pyrolysis and gasification) are effective ways to manage waste. The present study investigates the co-pyrolysis of chicken manure and rice husk. The experiments were conducted in a non-isothermal gravimetrical analyzer using nitrogen at a flowrate of 100 ml/min at three different heating rates (5, 10, and 15 °C/min). The degradation of individual biomass and biomass blends is investigated. The kinetic parameters are calculated using the Friedman method. Results show a positive synergetic effect for mixing ratios greater than 20% rice husk. The mixing ratio of 40% of rice husk manifested the best performance among all blends. This mixture showed the minimum energy of activation (90.2 kJ/mol). Also, the 40% rice husk mixing ratio showed maximum conversion when compared with chicken manure's conversion.

Natural Rubber/In Situ Silica Nanocomposite of a High Silica Content

2005 ◽  
Vol 34 (5) ◽  
pp. 672-673 ◽  
Author(s):  
Sirilux Poompradub ◽  
Shinzo Kohjiya ◽  
Yuko Ikeda
Keyword(s):  
Natural Rubber ◽  
Silica Content ◽  
In Situ Silica ◽  
High Silica Content ◽  
High Silica ◽  
Silica Nanocomposite

Characterization of Chalawa River Sand for Foundry Application

2013 ◽  
Vol 315 ◽  
pp. 724-727 ◽  
Author(s):  
Y. Tijjani ◽  
B. Onyekpe ◽  
I.A. Rafukka
Keyword(s):  
Standard Procedure ◽  
Silica Content ◽  
River Sand ◽  
High Silica Content ◽  
Sieve Analyses ◽  
High Silica

The characterization of Chalawa river sand with its suitability for foundry applications has been investigated. Chemical and sieve analyses and Green permeability were determined for the sand via standard procedure. Based on the result of the chemical and sieve analyses and permeability (the sand by its high silica content and low alkali fluxes) it needs small amount of binder, has moderate refractoriness and therefore, can be employed in foundry applications.

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