scholarly journals Sand Dune Characterization for Preparing Metallurgical Grade Silicon

2018 ◽  
Vol 16 (1) ◽  
pp. 1227-1232 ◽  
Author(s):  
S. Anas Boussaa ◽  
A. Kheloufi ◽  
N. Boutarek Zaourar
Keyword(s):  
Optical Observations ◽  
X Ray Diffraction ◽  
Dune Sand ◽  
Metallurgical Grade Silicon ◽  
Characterization Methods ◽  
Physico Chemical ◽  
Photovoltaic Applications ◽  
Different Shapes ◽  
Crystalline Nature

AbstractDune sand, from Biskra, Algeria which is in the Great Algerian huge desert attracts tourists from all over the world. Dune sand composes around 80% of the total area of the desert. To date only a few studies have been conducted on this sand. The purpose of the present study is to shed light on the textural and physico-chemical characteristics of this sand using several characterization methods, and to understand the potential for using for photovoltaic applications. The chemical composition of Biskra sand indicated a high purity quartz with 97.6% silica, and a presence of others oxides. Granular analysis enabled the determination of the size of the sand grains which was found to be fine to medium. On the other hand, a Scanning Electron Microscopy and optical observations were carried out, the micrographs observations indicated the presence of different shapes of sand grain, some rounded whereas others are angular edged or elongated. X-ray diffraction indicates the highly crystalline nature of the Biskra sand.

scholarly journals X-Ray Diffraction Studies on Alicyclic Saturated Discotic Liquid Crystals

1987 ◽  
Vol 42 (6) ◽  
pp. 631-635 ◽  
Author(s):  
H. W. Neuling ◽  
H. Stegemeyer ◽  
K. Praefcke ◽  
B. Kohne
Keyword(s):  
Liquid Crystalline ◽  
Optical Observations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkyl Chains ◽  
New Class ◽  
X Ray Scattering ◽  
Oriented Samples ◽  
Hexagonal Columnar

The discotic liquid crystalline phase of a new class of disc-like molecules (hexa-O-alkanoylscyllo- inositoles) is studied by small angle X-ray scattering, DSC and optical observations. Comparison of these three methods allows the determination of the structural arrangement. X-ray film exposures of oriented samples clearly demonstrate the hexagonal columnar ordered type of mesophases. A simple model calculation shows that the alkyl chains of neighbouring columns interpenetrate each other to a small extent.

Wastewater COD characterization: biodegradability of physico-chemical fractions

2002 ◽  
Vol 45 (6) ◽  
pp. 89-97 ◽  
Author(s):  
P. Ginestet ◽  
A. Maisonnier ◽  
M. Spérandio
Keyword(s):  
Hydrolysis Rate ◽  
Affinity Constant ◽  
Characterization Methods ◽  
First Order ◽  
Physico Chemical ◽  
Wastewater Samples ◽  
Solids Analysis ◽  
Activated Sludge Processes ◽  
Limited Surface

Physico-chemical and biological characterization methods were applied to wastewater samples originating from 7 French WWTPs. The settleable fraction (S), unsettleable-coagulable fraction (US-C) and unsettleable-uncoagulable fraction (US-UC) were separated. Special emphasis was put on the determination of hydrolysis kinetics associated with coagulable- and settleable-fractions in order to model their behaviour in activated sludge processes, as both these fractions are influenced by the SRT. The “soluble” fraction (i.e. US-UC) was composed of readily biodegradable COD (2 to 27%), readily hydrolysable COD (37 to 90%) and inerts (2 to 47%). The “colloidal” fraction (i.e. US-C) was composed of heterotrophic biomass (9 to 24%) and readily hydrolysable COD (6 to 82%), with the rest being inerts or very slowly biodegradable COD (0 to 70%). The “particulate” fraction (i.e. settleable) was composed of biomass (14 ± 6%), readily hydrolysable COD (21 ± 14%), slowly hydrolysable COD (about 45–50%) and 15 to 20% which can be considered as inert matter (XI). “Readily hydrolysable COD” was correctly modeled by a global first-order reaction. First-order constants (KH) were 9 ± 2 d−1 for raw-wastewater, 12 ± 3 d−1 for primary settled-wastewater and 16 ± 5 d−1 for coagulated-wastewater. “Slowly hydrolysable COD” was correctly modeled by a limited surface reaction. Concerning this fraction, the specific hydrolysis rate (kH) ranged from 0.25 to 1.05 d−1, and the affinity constant (KX) ranged from 0.33 to 0.95 gCOD/gCOD based on settleable solids analysis.

scholarly journals IV. Physico-chemical determinations at high pressures by optical methods

1913 ◽  
Vol 212 (484-496) ◽  
pp. 117-148 ◽  
Keyword(s):  
High Pressures ◽  
Optical Observations ◽  
Optical Methods ◽  
Small Glass ◽  
Physico Chemical ◽  
Glass Tubes ◽  
Pressure Bomb ◽  
The Subject ◽  
Transition Points

In the course of his well-known investigations concerning the compressibility of gases and liquids, Amagat made some series of measurements taking observations through two small glass windows fitted to his high-pressure bomb (“méthode des regards”),* and he also twice made an attempt to use a similar arrangement for the determination of melting and crystallization at high pressures. His first paper on these subjects deals with the melting and with the formation of two different kinds of crystals of carbon tetrachloride. The highest pressure employed was 1,160 atmospheres. The second paper, in which a somewhat different arrangement of the glass windows was used, deals with the crystallization of ice at temperatures below zero under the influence of high pressures.^ In a summarizing paper Amagat§states that he occasionally was able to reach pressures of about 1,600 atmospheres before the glass windows were broken, but observations were not actually made at higher pressures than 1,000 atmospheres. In this paper a sketch of the apparatus is also given. Amagat states that he met with severe difficulties during these investigations, and he has not pursued the subject further. Later melting-points and transition-points of some “liquo-crystalline” substances have been measured in Jena glass tubes up to 300 atmospheres by Hullett, and other optical observations at pressures above that of the atmosphere have been made by Rothmund (maximum 500 atmospheres), Röntgen and Zehnder, Sierstema, Liveing and Dewar, Hutton and Petavel,§§ and Duffield, but in these investigations the pressures have, as a rule, not exceeded 100 atmospheres.

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

Symmetry breaking in convergent-beam diffraction

1989 ◽  
Vol 47 ◽  
pp. 480-481
Author(s):  
D.J. Eaglesham
Keyword(s):  
Symmetry Breaking ◽  
Point Group ◽  
X Ray Diffraction ◽  
Multiple Diffraction ◽  
Space Groups ◽  
Atomic Displacements ◽  
Small Probe ◽  
Phase Sensitive ◽  
Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

New Coordination Compounds of Fe(III) with Organic Ligands

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihaela Flondor ◽  
Ioan Rosca ◽  
Doina Sibiescu ◽  
Mihaela-Aurelia Vizitiu ◽  
Daniel-Mircea Sutiman ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Complex Compounds ◽  
Organic Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Chemical Analysis ◽  
Structural Formulae ◽  
Paramagnetic Properties

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex compounds are assigned.

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