Mineralogical composition of the clay fraction of two fluvio-glacial sediments from east Greenland

Clay Minerals ◽  
1980 ◽  
Vol 15 (2) ◽  
pp. 135-145 ◽  
Author(s):  
L. Petersen ◽  
K. Rasmussen
Keyword(s):  
Clay Fraction ◽  
Mineralogical Composition ◽  
Cold Climate ◽  
High Rate ◽  
Degree Of Crystallinity ◽  
Metamorphic Rocks ◽  
Glacial Sediments ◽  
East Greenland ◽  
Soil Clays ◽  
High Degree

AbstractThe < 2 µm fractions of two fluvio-glacial sediments from East Greenland have been analysed chemically and by XRD and Mössbauer spectroscopy. The bulk of each < 2 µm fraction consists of feldspars and micas (biotite) which are important constituents of the Precambrian igneous and metamorphic rocks of the area. Significant amounts of vermiculitic and smectitic minerals are also present. Compared with similar minerals present in Danish soil clays, the Greenland vermiculite and smectite are characterized by a high degree of crystallinity and it is concluded that these minerals have been formed from biotite through K release and lattice expansion. These processes appear to have proceeded at a sufficiently high rate to yield significant amounts of vermiculite and smectite despite the cold climate prevailing in the area.

Phosphate sorption characteristics of soils of the north Queensland coastal region

Soil Research ◽  
1988 ◽  
Vol 26 (3) ◽  
pp. 465 ◽  
Author(s):  
BN Toreu ◽  
FG Thomas ◽  
GP Gillman
Keyword(s):  
Clay Fraction ◽  
Coastal Region ◽  
Mineralogical Composition ◽  
Parent Material ◽  
Metamorphic Rocks ◽  
Phosphate Sorption ◽  
Soil P ◽  
P Sorption ◽  
The North ◽  
Sorption Characteristics

Phosphate-sorption curves covering the range of supernatant P concentration, 0-1 �g nil-1, have been determined for a number of agriculturally important soils in the high rainfall (2000-4000 mm) region of tropical Queensland. Where possible, soil samples were taken from both virgin and cultivated sites within a soil series. The soils occur on four major parent materials, namely basaltic, granitic and metamorphic rocks, and on alluvium derived from one or more of these rocks. The shapes of the P-sorption curves and the differences in magnitude of P sorption were related to the mineralogical composition of the clay fraction which, in turn, was determined by parent material. Past applications of phosphatic fertilizer have lessened soil P-sorption capacity, despite a reduction in soil organic matter resulting from clearing and cultivation.

scholarly journals Synthesis and Characterization of Nano-Sized 4-Aminosalicylic Acid–Sulfamethazine Cocrystals

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 277 ◽  
Author(s):  
Ala’ Salem ◽  
Anna Takácsi-Nagy ◽  
Sándor Nagy ◽  
Alexandra Hagymási ◽  
Fruzsina Gősi ◽  
...  
Keyword(s):  
High Power ◽  
Active Pharmaceutical Ingredient ◽  
Polymorphic Form ◽  
Degree Of Crystallinity ◽  
Dissolution Enhancement ◽  
Aminosalicylic Acid ◽  
Nano Technology ◽  
Power Ultrasound ◽  
High Power Ultrasound ◽  
High Degree

Drug–drug cocrystals are formulated to produce combined medication, not just to modulate active pharmaceutical ingredient (API) properties. Nano-crystals adjust the pharmacokinetic properties and enhance the dissolution of APIs. Nano-cocrystals seem to enhance API properties by combining the benefits of both technologies. Despite the promising opportunities of nano-sized cocrystals, the research at the interface of nano-technology and cocrystals has, however, been described to be in its infancy. In this study, high-pressure homogenization (HPH) and high-power ultrasound were used to prepare nano-sized cocrystals of 4-aminosalysilic acid and sulfamethazine in order to establish differences between the two methods in terms of cocrystal size, morphology, polymorphic form, and dissolution rate enhancement. It was found that both methods resulted in the formation of form I cocrystals with a high degree of crystallinity. HPH yielded nano-sized cocrystals, while those prepared by high-power ultrasound were in the micro-size range. Furthermore, HPH produced smaller-size cocrystals with a narrow size distribution when a higher pressure was used. Cocrystals appeared to be needle-like when prepared by HPH compared to those prepared by high-power ultrasound, which had a different morphology. The highest dissolution enhancement was observed in cocrystals prepared by HPH; however, both micro- and nano-sized cocrystals enhanced the dissolution of sulfamethazine.

FIXATION AND RELEASE OF POTASSIUM IN RELATION TO THE MINERALOGY OF THE CLAY FRACTION OF SOME SELECTED SOIL HORIZON SAMPLES

1971 ◽  
Vol 51 (3) ◽  
pp. 449-459 ◽  
Author(s):  
A. J. MacLEAN ◽  
J. E. BRYDON
Keyword(s):  
Clay Fraction ◽  
High Capacity ◽  
Soil Horizon ◽  
Exchangeable K ◽  
High Release ◽  
Soil Clays ◽  
Activity Ratios ◽  
Plant Removal ◽  
Satisfactory Relationship ◽  
Intermediate Amount

Soil clays of 11 horizon samples of Canadian soils gave activity ratios (AReK) of 0.0003 to 0.0040, exchangeable K values of 0.18 to 1.74 meq/100 g, nonexchangeable K values of 1.54 to 6.65 meq/100 g upon leaching with 12 liters of 0.1 N BaCl2 and of 0.45 to 4.03 meq as measured by plant removal, and degrees of K-fixation of 29 to 100% of added K against extraction with 1 N NH4OAc. The amounts of exchangeable K were correlated with the activity ratios and with the amounts of non-exchangeable K removed by plants. Of the fixed K, 46 to 86% was recovered by leaching with the 0.1 N BaCl2 and 18 to 64% by cropping. Some of the clays gave a satisfactory relationship between their K behaviour and mineralogy. Two of them (Ae, Humo-Ferric Podzol), consisting of mixtures of vermiculite and montmorillonite, released native K slowly and had a high capacity to fix added K. Another corresponding sample, from the C horizon and consisting of well-ordered 2 M1 muscovite, also released native K slowly but gave the lowest degree of K-fixation. A predominantly montmorillonite clay with some mica layers (Gray Luvisol) gave a high release of native K and fixed an intermediate amount of added K. The K–mineralogy relationship in the remaining samples was less apparent, and varied with the complexity of interstratification.

scholarly journals Chemical and mineralogical composition of clay fraction found in Podillia upland haplic chernozems

2017 ◽  
pp. 278-292
Author(s):  
Igor Papish ◽  
Oleksii Telehuz
Keyword(s):  
Clay Fraction ◽  
Soil Formation ◽  
Mineralogical Composition ◽  
Development Stage ◽  
Potassium Feldspar ◽  
Forest Steppe ◽  
Molar Ratios ◽  
Haplic Chernozems ◽  
Typical Chernozems ◽  
Chemical And Mineralogical Composition

The article presents data on gross chemical and mineralogical composition of clay faction found in typical chernozems occurred within the Podillia Upland. Geographical regularities of formation as regards clayey profile of Chernozems pertaining to the same genetic series are revealed. The relationship between conditions and Chernozem development stage, character of vertical differentiation of basic mineral phases of clayey plasma and its chemical and mineralogical composition are shown. Izoclayey profile of hydromicas is the consequence of their relative accumulation as a result eluviation of colloid-dispersible mica-smectite minerals. The character of clay profile observed in Chernozems is determined by the correlation of intensity of carbonates leaching, lessivage and soils argillisation. Typical Podolian Chernozems are characterised with the like weathering crust of silicate type. The modern Chernozem clayey profile originated mainly during a wetter stage of soil formation. In the ploughable layer a high content of clastic minerals (quartz, potassium feldspar, sodium plagioclase) is observed. Random mixed and stratified mica-smectite minerals with a high content (>50 %) of smectite packets (33–63 %), hydromica (33–52 %), and kaolinite plus chlorite (4–15 %) are present in the profile. The mineralogical composition of soils clay fraction indicates obvious signs of smectite eluviation and relative illite accumulation. Clayey profile of the Bug upstream plateau located within the Podillia Upland is atypical for Chernozems found in the eastern forest-steppe and steppe areas. The distribution character of layered silicates, especially smectite, is even more contrastive. Clayey plasma redistributes differentially through leaching and lessivage processes. Accumulative type of sludge deposits formed in Chernozems of the Dniester plateau located within the Podillia Upland, even profile distribution of basic oxides and molar ratios of SiO2 : Al2O3 and SiO2 : Fe2O3 against the background of decreased downward smectite content indicate weakened eluviation of fine-grained clays towards the Dniester. The prevalence of smectite over hydromicas within the entire profile indicates argillisation of Chernozems. Key words: Chernozem, chemical-mineralogical composition, clayey minerals, hydromica, smectite, kaolinite, leaching, lessivage, argillisation.

scholarly journals Applicability of Ground Penetrating Radar on desert archaeological sites: a case study from the Saqqara necropolis in Egypt

2014 ◽  
Vol 31 (2) ◽  
pp. 133-141 ◽  
Author(s):  
Fabian Welc ◽  
Radosław Mieszkowski ◽  
Sebastian Kowalczyk ◽  
Jerzy Trzciński
Keyword(s):  
Ground Penetrating Radar ◽  
Clay Fraction ◽  
Mineralogical Composition ◽  
Archaeological Site ◽  
Geological Structure ◽  
Horizontal Resolution ◽  
Archaeological Sites ◽  
Depth Range ◽  
Non Invasive ◽  
Ground Penetrating

Abstract This paper presents the preliminary results of ground penetrating radar sounding applied at the desert archaeological site in Saqqara (Egypt). The survey was carried out in 2012 within a project realized by Institute of Archaeology, Cardinal Stefan Wyszyński University in Warsaw and the Faculty of Geology, University of Warsaw. One of the key aims of the research was testing the application of ground penetrating radar to non-invasive surveys of desert archaeological sites. Radargrams obtained for area of so called the Dry Moat channel surrounding the Step Pyramid complex have shown the geological structure of its filling. It comprises among others debris-sand conglomerate of diluval origin characterized by a significant content of the clay fraction and clay minerals. Such lithological content strongly attenuate the propagation of EM waves, restricting the depth range of the GPR survey. The conducted geophysical prospection west to the Step Pyramid in Saqqara has confirmed the high applicability of the GPR method in non-invasive studies of vast architectural structures, such as the monumental ditch surrounding the Step Pyramid known as the Dry Moat. It should summarised that high horizontal resolution obtained during GPR survey is a result of local geological structure of the searched area, i.e. strong lithological contrast of the sediments filling the Dry Moat, which, depending on their mineralogical composition

Heteroepitaxial Growth Of ZnO Films BY PLD

1997 ◽  
Vol 474 ◽  
Author(s):  
R. D. Vispute ◽  
V. Talyansky ◽  
Z. Trajanovic ◽  
S. Choopun ◽  
M. Downes ◽  
...  
Keyword(s):  
Oxygen Pressure ◽  
Surface Region ◽  
Optical Quality ◽  
Degree Of Crystallinity ◽  
Zno Films ◽  
Heteroepitaxial Growth ◽  
Near Surface ◽  
Ion Channeling ◽  
Deposition Parameters ◽  
High Degree

ABSTRACTHere we present our recent work on the fabrication of high crystalline and optical quality ZnO films on sapphire (001) by pulsed laser deposition. The influence of deposition parameters such as the substrate temperature, oxygen pressure, laser fluence, and pulse repetition rate on the crystalline quality of ZnO layers has been studied. The Ω-rocking curve FWHM of the (002) peak for the films grown at 750°, oxygen pressure 10−5 Torr was 0.17°. The XRD-Ф scans studies revealed that the films were epitaxial with a 30° rotation of the unit cell with respect to the sapphire to achieve a low energy configuration for epitaxial growth. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2–3% in the near surface region (-2000Å). The atomic force microscopy revealed smooth hexagonal faceting of the films. The optical absorption edge measured by UV-Visible spectroscopy was sharp at 383 nm. Excellent crystalline properties of these epi-ZnO/sapphire heterostractures are thus promising for III-V nitride heteroepitaxy.

A Novel Spray Based Method for the Production of Semiconductor Nanocrystals

2005 ◽  
Vol 879 ◽  
Author(s):  
Lilac Amirav ◽  
Efrat Lifshitz
Keyword(s):  
Size Distribution ◽  
Semiconductor Nanocrystals ◽  
Average Diameter ◽  
Solute Concentration ◽  
Degree Of Crystallinity ◽  
Attractive Alternative ◽  
Spray Droplet ◽  
Zinc Blend ◽  
Semiconductor Nanoparticle ◽  
High Degree

AbstractWe present a novel spray based method for the formation and production of semiconductor nanocrystals that provides an attractive alternative to the commonly used epitaxial and colloidal procedures. According to this spray-based method, mainly thermospray, solutions of semiconductor salts are first sprayed into monodispersed droplets, which subsequently become solid nanoparticles by solvent evaporation. A semiconductor nanoparticle is produced from a single spray droplet upon the full vaporization of the solvent. The average diameter and size distribution of the final nanocrystals are controlled and determined by the solute concentration of the sprayed solution and by the droplet size, hence by the spray production parameters. The spray-produced nanocrystals are collected on any selected solid support. Representative results, shown in this paper, reveal the formation of CdS nanocrystals in the size range of 3 to 6 nanometer and with a size distribution of as low as five percents. A further structural analysis of these nanocrystals showed that they were formed in the zinc blend phase with high degree of crystallinity.

Mineral sources of potassium to plants for seven soils from south-western Australia

Soil Research ◽  
2002 ◽  
Vol 40 (8) ◽  
pp. 1357 ◽  
Author(s):  
Y. Pal ◽  
R. J. Gilkes ◽  
M. T. F. Wong
Keyword(s):  
Clay Fraction ◽  
Mineralogical Composition ◽  
High Specific Surface Area ◽  
K Uptake ◽  
Size Fractions ◽  
Silicate Structure ◽  
Constant Rate ◽  
Incomplete Removal ◽  
Congruent Dissolution ◽  
K Release

This investigation was conducted with surface horizon samples from 7 south-western Australian soils and their 3 size fractions (sand, silt, and clay). The K release of these materials was measured for several extractants; the highest amounts of K were released from the clay (<2 μm) fraction. The presence of sand-size feldspars and incomplete removal of attached organic matter resulted in sand releasing significant amounts of K. The proportions of total K released in boiling 1 m HNO3 by the sand, silt, and clay fractions ranged from 0.4 to 3.4%, 2.6 to 36.3%, and 11.2 to 51.4%, respectively, and from 2.0% to 22.9% for the whole soils. Cumulative K uptake by 6 harvests of ryegrass over 260 days ranged from 0.26 to 1.23 cmol/kg soil.The clay fraction released higher proportions of total K to acid compared with the sand and silt size fractions because of the high specific surface area of the clay and because it contained proportionately higher amounts of illite, which releases K by both ion exchange and dissolution, whereas K release from feldspars requires congruent dissolution of the silicate structure. The differences in contents of StepK (relatively available fraction of the non-exchangeable K) and CRK (constant rate K) for 1 m HNO3 dissolution of these soils and size fractions reflect differences in mineralogical composition between the soils and size fractions. The low contents of StepK for the sand fraction indicated that K was strongly retained by feldspars. The soils with high CRK values had significant amounts of illite in the clay fraction. Values of CRK were positively related to cumulative K uptake and cumulative dry matter yield of ryegrass.

The manganese oxide mineral, lithiophorite, in an oxisol From Hawaii

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 51 ◽  
Author(s):  
DC Golden ◽  
JB Dixon ◽  
Y Kanehiro
Keyword(s):  
Electron Microscopy ◽  
Clay Fraction ◽  
Hydroxylamine Hydrochloride ◽  
Mineralogical Composition ◽  
Soil Horizon ◽  
X Ray Diffraction ◽  
High Gradient Magnetic Separation ◽  
X Ray ◽  
Tropeptic Eutrustox ◽  
Treated Sample

The mineralogical composition of the surface soil horizon (0-15 cm) of Wahiawa soil (Tropeptic Eutrustox) was investigated by X-ray diffraction (XRD), high gradient magnetic separation (HGMS), transmission electron microscopy (TEM), and infrared methods. The concentration of lithiophorite decreased with particle size and none was present in the clay fraction as indicated by XRD. Lithiophorite was further concentrated from the crushed sand-sized fraction by HGMS. Hexagonal, electron-dense, often twinned lithiophorite particles were identified by electron diffraction. Differential infrared (DIR) spectra obtained by dissolving Mn oxides in acidified hydroxylamine hydrochloride (HAHC) indicated lithiophorite as the HAHC-soluble Mn-phase. Lithiophorite compositiion, as revealed by chemical analysis of the HAHC extracts, consisted of appreciable amounts of Mn, Al, Zn, Co and Mg, and less than stoichiometric amounts of Li. Sodium hydroxide treatment apparently altered the lithiophorite, as revealed by the DIR spectrum of the hydroxylamine-soluble fraction of the NaOH-treated sample compared with the untreated sample. The high crystallinity of the lithiophorite was suggested by its resistance to chemical dissolution and narrow X-ray diffraction lines. No evidence for the presence of todorokite or birnessite was found, contrary to earlier reports. Examination of sand-sized nodules by scanning electron microscopy indicated large (2-5 �m) platy lithiophorite crystals at the surface of these nodules. Electron microprobe analysis of these platy particles indicated iron enrichment near the surface. The freshly fractured nodule surface revealed numerous unaltered platy crystals of lithiophorite filling the veins of the nodule.

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