Physical Properties of Dried Na2O-SiO2 Monoliths

1988 ◽  
Vol 121 ◽  
Author(s):  
Rounan Li ◽  
L. L. Hench
Keyword(s):  
Optical Properties ◽  
Physical Properties ◽  
Bulk Density ◽  
Sol Gel ◽  
Index Of Refraction ◽  
True Density ◽  
Compositional Dependence ◽  
Ir Reflection ◽  
Acid Catalyzed ◽  
Gel Processing

ABSTRACTDried monolithic gels of compositions XNa2O-(1-X)SiO2 (with X from 0 mol% to 7 mol%) were obtained by acid catalyzed sol-gel processing using tetramethylorthosilicate and NaNO3. Optically clear monoliths in the range of 20 to 90 mm diameter by 3 to 20 mm thickness were routinely produced by controlling the processing schedule. Complete drying in air without cracking was achieved at 180°C from 10–14 days. The bulk density and optical properties of the gels, characterized by UV/VIS/NIR transmission, IR reflection and index of refraction, showed a compositional dependence on Na2O similar to melt glasses of the same Na2O content. However, the true density and microhardness decreased with Na2O content in contrast to melt glasses.

scholarly journals On the optical and physical properties of tabasheer. By David Brewster, LL. D. F. R. S. Lond. and Edin. In a letter to the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S. &c

1833 ◽  
Vol 2 ◽  
pp. 115-116
Keyword(s):  
Optical Properties ◽  
Specific Gravity ◽  
Physical Properties ◽  
The State ◽  
Index Of Refraction ◽  
Flint Glass ◽  
The Third ◽  
Refractive Power ◽  
The Absolute ◽  
The Right

Tabasheer is a substance found in the cavities of the bamboo, existing originally in the state of a transparent fluid, but gradually indurating into a solid of different degrees of hardness: it consists of 70 silica, + 30 potash and lime. One variety has a milky transparency, transmitting a yellowish, and reflecting a bluish light; another is translucent, and a third opake: the two first varieties become transparent, and evolve air when immersed in water: the third evolves air also, but remains opake. If the first varieties be only slightly wetted they become quite opake. The property of acquiring transparency by the evolution of air from, and the absorption of water by its pores, belongs also to the hydrophanous opal; but the faculty of becoming opake by a small quantity, and transparent by a larger, of water, shows a singularity of structure in tabasheer. As the tabasheer disengages more air than hydrophane, its pores must be more numerous; and therefore the transmission of light, so as to form a perfect image, indicates either a very feeble refractive power or some peculiarity in the construction of its pores. To determine this, Dr. Brewster formed a prism of tabasheer with an angle of 34° 15', and upon measuring its refractive power found it very low, though various in different specimens, the index of refraction varying from 1·11 to 1·18, that of water being 1·33, of flint-glass 1·60, of sulphur 2·11, of phosphorus 2·22, and of the diamond 2·47. So that tabasheer has a lower refractive power than any other solid or liquid, and holds an intermediate place between water and the gases. Dr. Brewster then gives a formula for computing the absolute refractive power of bodies, and a table of results, from which it appears that, in this respect, the refractive power of tabasheer is so low as to be separated by a considerable interval from all other bodies. The author next proceeds to detail a variety of experiments upon the absorbent powers of the different kinds of tabasheer, in respect to several liquids, and the corresponding effects upon its optical properties and specific gravity, and concludes with observations on the cause of the paradox exhibited by the transparent tabasheer, in becoming opake by absorbing a small quantity of water, and transparent when the quantity is increased.

Structure and optical properties of (Al2O3)x(Tio)1−x thin films prepared by a sol–gel processing

Vacuum ◽  
2004 ◽  
Vol 76 (2-3) ◽  
pp. 215-218 ◽  
Author(s):  
P. Vitanov ◽  
A. Harizanova ◽  
Chr. Angelov ◽  
I. Petrov ◽  
Z. Alexieva ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Sol Gel ◽  
Gel Processing

Effect of moisture content on physical properties of cashew nut of different varieties

2016 ◽  
Vol 44 (2) ◽  
Author(s):  
Shrikant Baslingappa Swami ◽  
N.J. Thakor A.M. Gawai
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Bulk Density ◽  
Surface Area ◽  
Geometric Mean ◽  
Angle Of Repose ◽  
True Density ◽  
Cashew Nut ◽  
Mean Diameter ◽  
Effect Of Moisture

<p>The physical properties, viz., geometric diameter, surface area, sphericity, volume, bulk density, true density and angle of repose was measured for  four  cashew varieties <em>viz</em>., <em>Vengurle 1, Vengurle 3, Vengurle 4</em>  and <em>Vengurle 7</em> at different moisture content (15 to 87% db). For <em>Vengurle</em> 1 as the moisture content increased, the physical properties i.e., geometric mean diameter, volume, surface area, true density and angle of repose increased from 20.8 to 22.1 mm, 3485 to 4416 mm<sup>3</sup>, 1355 to 1540 mm<sup>2</sup>, 984 to 1030 kg m<sup>-3</sup> and 32 to 37˚, respectively. The sphericity and bulk density decreased from 74.2 to 71.4 per cent and 490 to 418 kg m<sup>-3</sup> respectively. For <em>Vengurle 3</em> geometric mean diameter, volume, surface area, true density and angle of repose increased from 27.2 to 28.6 mm, 7912 to 9169 mm<sup>3</sup>, 2320 to 2567 mm<sup>2</sup>, 1020 to 1048 kg m<sup>-3</sup> and 33 to 35.5˚, respectively. The sphericity and bulk density decreased from 75.5 to 75.2 per cent and 531 to 470 kg m<sup>-3</sup> respectively. For <em>Vengurle 4</em> the geometric mean diameter, volume, surface area, true density and angle of repose increased from 21.0 to 24.1mm, 3362 to 5113 mm<sup>3</sup>, 1391 to 1828 mm<sup>2</sup>, 970 to 1030 kg m<sup>-3</sup> and 32.5 to 38˚,  respectively. The sphericity and bulk density decreased from 65.8 to 66.8 per cent, 517 to 462 kg m<sup>-3</sup>, respectively. For <em>Vengurle 7</em> the geometric mean diameter, volume, surface area, true density and angle of repose increased from 24.2 to 24.9 mm, 5102 to 5547 mm<sup>3</sup>, 1840 to 1941 mm<sup>2</sup>, 998 to 1045 kg m<sup>-3</sup> and 33 to 38˚, respectively. The sphericity and bulk density decreased from 65.4 to 65.8 per cent, 518 to 438 kg m<sup>-3</sup>, respectively.</p>

scholarly journals Physical properties of safflower grains. Part I: Geometric and gravimetric characteristics

2017 ◽  
Vol 21 (5) ◽  
pp. 344-349 ◽  
Author(s):  
Elton A. S. Martins ◽  
André L. D. Goneli ◽  
Cesar P. Hartmann Filho ◽  
Munir Mauad ◽  
Valdiney C. Siqueira ◽  
...  
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Bulk Density ◽  
Surface Area ◽  
Initial Moisture Content ◽  
Volume Ratio ◽  
True Density ◽  
Geometrical Characteristics ◽  
Forced Air ◽  
Air Circulation

ABSTRACT Safflower is an oil crop and its oil can be used for food and industrial purposes. However, there is little information about the physical properties of these grains, which is important for the planning and execution of post-harvest stages. Thus, this study was carried out with the aim of evaluating the effect of drying on the main physical properties of safflower grains. Safflower grains were harvested with an initial moisture content of approximately 0.445 decimal d.b. (dry basis) and subjected to drying in an oven with forced air circulation at 40 °C, until the grains reached a final moisture content of 0.073 ± 0.008 decimal d.b. During the drying, bulk density and true density, porosity, thousand-grain mass, circularity, sphericity, projected and surface area, and surface-volume ratio were measured. Based on these results, it is concluded that all gravimetric and geometrical characteristics of safflower grains were reduced due to the reduction of moisture content, except for the surface-volume ratio.

Optical properties of BBOT-doped silica films prepared via sol–gel processing

2007 ◽  
Vol 122-123 ◽  
pp. 268-271 ◽  
Author(s):  
Junling Wang ◽  
Zhiqun He ◽  
Huaxiang Mao ◽  
Yufan Du ◽  
Yongsheng Wang
Keyword(s):  
Optical Properties ◽  
Sol Gel ◽  
Silica Films ◽  
Gel Processing

scholarly journals Physical properties of sunflower seeds during drying

2017 ◽  
Vol 38 (1) ◽  
pp. 157
Author(s):  
Thaís Adriana de Souza Smaniotto ◽  
Osvaldo Resende ◽  
Kelly Aparecida de Sousa ◽  
Rafael Cândido Campos ◽  
Denner Nogueira Guimarães ◽  
...  
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Bulk Density ◽  
Initial Moisture Content ◽  
Gravimetric Method ◽  
Terminal Velocity ◽  
True Density ◽  
Sunflower Seeds ◽  
Intergranular Porosity ◽  
Air Ventilation

The aim of this work was to determine the effect that the moisture content has on the physical properties of sunflower seeds. The cultivar Olisun 3, with an initial moisture content of 34.1 (% wb), was used and then subjected to drying in an oven with forced air ventilation under three temperature conditions: 40, 60 and 80 °C. The reduction in the moisture content during drying was monitored by the gravimetric method until it reached a final moisture content of 8.0 ± 1.0 (% wb). The physical properties were analysed: the bulk density, true density, intergranular porosity and volumetric shrinkage of the mass and unit and terminal velocity. The reduction in the moisture content influenced the physical properties of sunflower seeds and caused a decrease in the intergranular porosity, bulk density and true density at all examined temperatures. The mass and volumetric contractions of the unit and reduction in shrinkage rates all increased with the drying of sunflower seeds at all studied temperatures. The terminal velocity increased as the moisture content of the grains increased, which was more evident at the drying temperature of 80 °C.

Hafnium Metallo-Organic Films and Gels Produced by Sol-Gel Processing

1989 ◽  
Vol 155 ◽  
Author(s):  
Charles D. Gagliardi ◽  
Kris A. Berglund
Keyword(s):  
Light Scattering ◽  
Sol Gel ◽  
Organic Films ◽  
Spin Casting ◽  
Synthesis Technique ◽  
Refractory Oxides ◽  
Sol Gel Process ◽  
Optically Transparent ◽  
Acid Catalyzed ◽  
Gel Processing

ABSTRACTMetallo-organic materials are often used as precursors for highly refractory oxides and hightemperature composites. The feasibility of producing hafnium metallo-organic films and gels by sol-gel techniques is demonstrated in the present study. Since hafnium alkoxides are not commercially available, their preparation is an obstacle in the development of their sol-gel processing applications. A common synthesis technique was used to produce hafnium isopropoxide, which was subsequently hydrolyzed under acid catalyzed conditions to produce films and gels. The films were prepared by spin casting and remained optically transparent. Initially, the gels were also optically transparent, but became translucent upon drying. Raman, IR, and light scattering spectroscopies were used to characterize this sol-gel process, and it is compared with the analogous processing of titanium and zirconium alkoxides.

scholarly journals Studies on Evaluation and Determination of Physical and Functional Properties of Millets. (Ragi and Pearl Millet)

2019 ◽  
Vol 38 (03) ◽  
Author(s):  
P A Pawase ◽  
A Shingote ◽  
U D Chavan
Keyword(s):  
Aspect Ratio ◽  
Moisture Content ◽  
Physical Properties ◽  
Bulk Density ◽  
Pearl Millet ◽  
Functional Properties ◽  
True Density ◽  
Sample Weight ◽  
Dimensional Properties ◽  
Significant Difference

The study determined the physical properties of finger millet (FM) (Eluesine coracana) grains and the functional properties of FM flour. Physical properties such as colour attributes, sample weight, bulk density, true density, porosity, surface area, sample volume, aspect ratio, sphericity, dimensional properties and moisture content of grain cultivars were determined. Water absorption capacity (WAC), bulk density (BD), dispersibility, viscosity and micro-structure of FM flours were also evaluated. Data collected were analyzed using SPSS statistical software version 23.0. Results showed that milky cream cultivar was significantly higher (p less than 0.05) than other samples in sample weight, bulk density, true density, aspect ratio and sphericity. However, pearl millet, used as a control, was significantly different from FM flour on all dimensional properties. Moisture content of milky cream showed higher significant difference for both grains and flours as compared to brown and black grain/flours. Milky cream cultivar was significantly different in L , b , C , H values, WAC, BD and dispersibility for both FM grains and flours. Data showed that brown flour was significantly higher in viscosity than in milky and black flours. Microstructure results revealed that starch granules of raw FM flours had oval/spherical and smooth surface. The study is important for agricultural and food engineers, designers, scientists and processors in the design of equipment for FM grain processing. Results are likely to be useful in assessing the quality of grains used to fortify FM flour.

scholarly journals Development of a Millet Destoner for Small Scale Farmers

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Aminu Saleh
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Bulk Density ◽  
Surface Area ◽  
Terminal Velocity ◽  
Commercial Production ◽  
Small Scale ◽  
True Density ◽  
Small Scale Farmers ◽  
Processing Properties

Post-harvest processes of millet rely on labour-intensive manual operations in Nigeria while its produce is associated with contaminants. A manually-operated destoner was developed to increase grain value for commercial production and reduce drudgery. To construct the destoner sieves, physical properties of one thousand randomly selected grains were determined digital Vernier callipers. Millet grains to be destoned was fed through the upper portion of the destoner being operated through the crank handle while the pure grains were collected at the discharge outlet. Results obtained shows the geometric diameter of the grains increase progressively from 3.51-4.22mm as moisture content increases. A screen aperture of 3.5mm was constructed. Grains’ surface area, volume and sphericity increased from 22.67-34.82mm², 8.19-13.98mm³ and 0.691-0.776g respectively. Mass, true density and terminal velocity of 1000 seed increased from 13.56-43.84g, 1548.91-1689.87kg/m³ and 2.69-4.58m/s respectively. The bulk density of millet also increased as moisture content increases but decreased beyond 12.5% moisture level indicating that millet floats on  water and was transpoted with the aid of an auger. About 50kg of millet was poured into the destoner to occupy its  ⅓ capacity while the remaining ⅔ was filled with water. Destoner output was  at 95% efficiency.Key words: Destoner, Millet, Processing, Properties, Contaminants

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