scholarly journals A Review on Botswana Coal Potential from a Pyrolysis and Gasification Perspective

2020 ◽  
Vol 65 (1) ◽  
pp. 80-96
Author(s):  
Mmoloki Makoba ◽  
Daniel Erich Botha ◽  
Mpho Thabang Rapoo ◽  
László Zsolt Szabó ◽  
Thapelo Shomana ◽  
...  
Keyword(s):  
Product Formation ◽  
Full Potential ◽  
Coal Pyrolysis ◽  
X Ray Diffraction ◽  
Product Selection ◽  
Complex Processes ◽  
Coal Characterization ◽  
History Of ◽  
Mass And Heat Transfer ◽  
Coal Reserves

Coal pyrolysis and gasification are promising options for the future of Botswana as the country has large coal reserves with severe limitations in terms of export options. Coal characterization facilities will be required in order to harness its full potential and methods such as proximate, ultimate and chemical structure analysis (FTIR, Raman spectroscopy and X-ray diffraction techniques) were investigated. The paper presents a brief history of pyrolysis and gasification, typical types of the reactors as well as factors that influence product selection for Botswana coal. Coal pyrolysis and gasification are complex processes and it is difficult to define the mechanisms of product formation. However, there are several kinetic models that are relevant to the sub-bituminous coal of Botswana which were proposed by researchers to describe the formation of the compounds and mathematical models that were validated by other researchers on mass and heat transfer as also presented herein.

Highlights in the history of X-ray topography1

1995 ◽  
Vol 210 (6) ◽  
Author(s):  
A. R. Lang
Keyword(s):  
Magnetic Domain ◽  
Diffraction Theory ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Structures ◽  
Structure Factors ◽  
History Of ◽  
Dislocation Sources ◽  
Non Destructive

AbstractX-ray topography provides a non-destructive method of mapping point-by-point variations in orientation and reflecting power within crystals. The discovery, made by several workers independently, that in nearly perfect crystals it was possible to detect individual dislocations by X-ray diffraction contrast started an epoch of rapid exploitation of X-ray topography as a new, general method for assessing crystal perfection. Another discovery, that of X-ray Pendellösung, led to important theoretical developments in X-ray diffraction theory and to a new and precise method for measuring structure factors on an absolute scale. Other highlights picked out for mention are studies of Frank-Read dislocation sources, the discovery of long dislocation helices and lines of coaxial dislocation loops in aluminium, of internal magnetic domain structures in Fe-3 wt.% Si, and of stacking faults in silicon and natural diamonds.

Plastic deformations in kyanites by tectonometamorphic processes: a single-crystal X-ray diffraction study

2009 ◽  
Vol 73 (3) ◽  
pp. 359-371 ◽  
Author(s):  
G. D. Gatta ◽  
N. Rotiroti ◽  
M. Zucali
Keyword(s):  
Single Crystal ◽  
X Ray Diffraction ◽  
Plastic Deformations ◽  
X Ray ◽  
Deformational History ◽  
Significant Difference ◽  
Elliptical Section ◽  
History Of ◽  
Diffraction Patterns ◽  
Two Stages

AbstractThe crystalch emistry and crystal structure of naturalky anite crystals from the Eclogitic Micaschists Complex of the Sesia-Lanzo Zone, Western Italian Alps, have been investigated by means of optical microscopy, wavelength dispersive X-ray microanalysis, and single-crystal X-ray diffraction. The association of kyanite + garnet + phengitic-mica + chloritoid suggests that the eclogite-facies stages occurred at P ≤ 2.1 GPa and T ≤ 650ºC. Kyanite grains are large (cm-sized) porphyroblasts grown dynamically during one of the deformational events related to the subduction of the Austroalpine continentalcr ust. Under the polarizing microscope, kyanite grains show almost homogeneous cores, whereas rims are sometimes symplectitic aggregates of quartz and kyanite, confirming at least two stages of growth most likely related to the multistage deformational history of these rocks. Chemical analysis shows that Fe3+ is the major substituting cation for Al3+, ranging between 0.038 and 0.067 a.p.f.u.The single-crystal X-ray diffraction investigation of the kyanites shows severely textured patterns on the (h0l)*-plane. Such evidence is not observed in the unwarped diffraction patterns on (0kl)* and (hk0)*. The most significant difference between the structuralp arameters refined in this study, with respect to those of previously published unstrained gem-quality crystals, concerns the displacement parameters. The anisotropic displacement ellipsoids of all the atomic sites are significantly larger than those previously described, and systematically oriented with the largest elliptical section almost perpendicular to [010]. The larger ellipsoids in the kyanite crystal investigated here reflect the displacement of the centre of gravity of the electron distribution, rather than an anomalous atomic thermal motion. The magnitude and orientation of the displacement parameters and the textured/strained diffraction pattern may be the result of two combined effects: (1) that the kyanite crystals are actually composed of several blocks; (2) the crystals are affected by a pervasive residual strain, as a result of tectonometamorphic plastic deformations and re-crystallization.

scholarly journals An Investigation of the Glucose Monitoring Practices of Nurses in Stroke Care: A Descriptive Cohort Study

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Elizabeth Ann Laird ◽  
Vivien E. Coates ◽  
Assumpta A. Ryan ◽  
Mark O. McCarron ◽  
Diane Lyttle ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Cohort Study ◽  
Acute Stroke ◽  
Glucose Monitoring ◽  
Positive Association ◽  
Stroke Care ◽  
Routine Practice ◽  
Full Potential ◽  
Significant Positive Association ◽  
History Of

Glucose derangement is commonly observed among adults admitted to hospital with acute stroke. This paper presents the findings from a descriptive cohort study that investigated the glucose monitoring practices of nurses caring for adults admitted to hospital with stroke or transient ischaemic attack. We found that a history of diabetes mellitus was strongly associated with initiation of glucose monitoring and higher frequency of that monitoring. Glucose monitoring was continued for a significantly longer duration of days for adults with a history of diabetes mellitus, when compared to the remainder of the cohort. As glucose monitoring was not routine practice for adults with no history of diabetes mellitus, the detection and treatment of hyperglycaemia and hypoglycaemia events could be delayed. There was a significant positive association between the admission hospital that is most likely to offer stroke unit care and the opportunity for glucose monitoring. We concluded that adults with acute stroke, irrespective of their diabetes mellitus status prior to admission to hospital, are vulnerable to both hyperglycaemic and hypoglycaemic events. This study suggests that the full potential of nurses in the monitoring of glucose among hospitalised adults with stroke has yet to be realised.

scholarly journals The origin of the galaxy color bimodality

2014 ◽  
Vol 11 (S308) ◽  
pp. 383-389
Author(s):  
M. A. Aragón-Calvo ◽  
Mark C. Neyrinck ◽  
Joseph Silk
Keyword(s):  
Spatial Configuration ◽  
Star Formation History ◽  
Star Forming ◽  
Complex Processes ◽  
Complex Process ◽  
Formation History ◽  
Density Relation ◽  
The Galaxy ◽  
Color Density ◽  
History Of

AbstractThe star formation history of galaxies is a complex process usually considered to be stochastic in nature, for which we can only give average descriptions such as the color-density relation. In this work we follow star-forming gas particles in a hydrodynamical N-body simulation back in time in order to study their initial spatial configuration. By keeping record of the time when a gas particle started forming stars we can produce Lagrangian gas-star isochrone surfaces delineating the surfaces of accreting gas that begin producing stars at different times. These surfaces form a complex a network of filaments in Eulerian space from which galaxies accrete cold gas. Lagrangian accretion surfaces are closely packed inside dense regions, intersecting each other, and as a result galaxies inside proto-clusters stop accreting gas early, naturally explaining the color dependence on density. The process described here has a purely gravitational / geometrical origin, arguably operating at a more fundamental level than complex processes such as AGN and supernovae, and providing a conceptual origin for the color-density relation.

X-Ray and Magnetic Measurements of TmFeTi2O7

2014 ◽  
Vol 215 ◽  
pp. 470-473 ◽  
Author(s):  
Tamara V. Drokina ◽  
German A. Petrakovskii ◽  
Dmitrii A. Velikanov ◽  
Maksim S. Molokeev
Keyword(s):  
Spin Glass ◽  
Solid Phase ◽  
Magnetic Measurements ◽  
Diffraction Method ◽  
Freezing Temperature ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
History Of

In this paper we are reported about a peculiarity of the crystal structure and the magnetic state of TmFeTi2O7. The compound TmFeTi2O7 has been synthesizedusing the solid-phase reaction method. Using X-ray diffraction method the disorder in the distribution of the iron ions over five nonequivalent crystal sites was observed, also the populations of the iron atoms positions were determined. We show that below Tf = 6 K the magnetization of TmFeTi2O7 depends on the magnetic history of the sample. There are indications for spin glass state. This results allow us to assume the state of spin glass is realized below freezing temperature Tf = 6 K in TmFeTi2O7.

scholarly journals The Difference Culture Makes

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Paul K Wason
Keyword(s):  
Social Learning ◽  
Genetic Relatedness ◽  
Full Potential ◽  
Animal Kingdom ◽  
Symbolic Thought ◽  
History Of ◽  
The Difference

The dawn of culture and its subsequent elaboration is one of the most important developments in the history of life. It is now recognized that culture, at least in a minimalist sense of behavioral traditions shaped by social learning, is found widely throughout the animal kingdom.  And this fact, perhaps ironically for those of a reductionist bent, has made possible new understandings of just how distinctive humans are, especially in terms of symbolic thought, cooperativity far beyond genetic relatedness, the cumulative nature of our cultures, and our pervasive sense of transcendence. Yet, nearly 150 years after Tylor’s Primitive Culture, we are still coming to appreciate in sometimes surprising new ways how the phenomenon of culture is transforming this planet. I suggest that despite the apparent pervasiveness of the concept, or at least the word, in both scholarly and everyday discourse, we have yet to appreciate the full potential of the concept of culture as an intellectual tool. Through brief exploration of five different situations in which it is useful, I hope to illustrate the importance of the phenomenon and show the untapped potential of the concept. 

scholarly journals Mortar mixes with oxblood: historical background, model sample recipes and properties

2018 ◽  
Vol 45 ◽  
pp. 19-24 ◽  
Author(s):  
Kun Zhang ◽  
Laura Rampazzi ◽  
Maria Pia Riccardi ◽  
Antonio Sansonetti ◽  
Alberto Grimoldi
Keyword(s):  
Building Materials ◽  
Historical Background ◽  
Organic Additives ◽  
X Ray Diffraction ◽  
Amorphous Calcium Carbonate ◽  
Historical Building ◽  
Model Sample ◽  
History Of ◽  
History Of Architecture ◽  
History Of Use

Abstract. In this survey we present studies on mortar mixes added with oxblood, which was a commonly found local waste material, with a wide application and long history of use; a precise recipe of lime–pozzolan mortar with blood addition from a 19th-century Italian manual was chosen, and model samples were prepared accordingly, with the aim of better understanding the chemical, mineralogical and physical characteristics of such compositions, starting with a blank reference specimen. The specimens were analysed by means of scanning electron microscopy, infrared spectroscopy, thermal analysis and X-ray diffraction, and the results suggested that amorphous calcium carbonate could be formed in the specimens with oxblood addition. These preliminary results allow a better understanding of historical building practices, measuring effects induced by organic additives on mortar microstructure, as well as an evaluation of new performances obtained in mortar mixes. Moreover, this paper intends to propose a full multi-discipline approach to bridge the history of architecture and building materials to conservation science.

scholarly journals Thermal History of Matrix Forsterite Grains from Murchison Based on High-resolution Tomography

2021 ◽  
Vol 922 (2) ◽  
pp. 256
Author(s):  
Giulia Perotti ◽  
Henning O. Sørensen ◽  
Henning Haack ◽  
Anja C. Andersen ◽  
Dario Ferreira Sanchez ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Density ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Maps ◽  
Thermally Processed ◽  
The Matrix ◽  
History Of ◽  
Chondrule Formation

Abstract Protoplanetary disks are dust- and gas-rich structures surrounding protostars. Depending on the distance from the protostar, this dust is thermally processed to different degrees and accreted to form bodies of varying chemical compositions. The primordial accretion processes occurring in the early protoplanetary disk such as chondrule formation and metal segregation are not well understood. One way to constrain them is to study the morphology and composition of forsteritic grains from the matrix of carbonaceous chondrites. Here, we present high-resolution ptychographic X-ray nanotomography and multimodal chemical microtomography (X-ray diffraction and X-ray fluorescence) to reveal the early history of forsteritic grains extracted from the matrix of the Murchison CM2.5 chondrite. The 3D electron density maps revealed, at unprecedented resolution (64 nm), spherical inclusions containing Fe–Ni, very little silica-rich glass and void caps (i.e., volumes where the electron density is consistent with conditions close to vacuum) trapped in forsterite. The presence of the voids along with the overall composition, petrological textures, and shrinkage calculations is consistent with the grains experiencing one or more heating events with peak temperatures close to the melting point of forsterite (∼2100 K), and subsequently cooled and contracted, in agreement with chondrule-forming conditions.

ROOM TEMPERATURE MAGNETIC ANOMALIES IN BENZENE TREATED Bi–Pb–Sr–Ca–Cu–O POWDER

1991 ◽  
Vol 05 (21) ◽  
pp. 1447-1456 ◽  
Author(s):  
A. R. HARUTUNYAN ◽  
L. S. GRIGORYAN ◽  
A. S. KUZANYAN ◽  
A. A. KUZNETSOV ◽  
A. A. TERENTIEV ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Chemical Composition ◽  
Room Temperature ◽  
Microprobe Analysis ◽  
Magnetic Anomalies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Samples ◽  
Field Dependent ◽  
History Of

Two samples of benzene-treated Bi–Pb–Sr–Ca–Cu–O powder exhibited at 300 K magnetic field dependent diamagnetism and magnetization irreversibility. The treatment with benzene resulted also in the appearance of microwave absorption at low magnetic fields, while is sensitive to magnetic history of the sample. From X-ray diffraction data one can see that upon benzene treatment the reflections of 85 K and 110 K phases do not change practically, but a series of new reflections appeared, indicating a lattice modulation with 4.9 nm periodicity. A microprobe analysis revealed substantial inhomogeneity of chemical composition across the samples. The room temperature anomalies were weakened in one sample and vanished in the second upon thermal cycling.

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