scholarly journals Problem hydromorphic soils in north-east Thailand. 1. Environment and soil morphology.

1977 ◽  
Vol 25 (2) ◽  
pp. 108-125
Author(s):  
R. Brinkman ◽  
A.G. Jongmans ◽  
R. Miedema
Keyword(s):  
Soil Fauna ◽  
Dry Season ◽  
Soil Morphology ◽  
Surface Salinity ◽  
X Ray ◽  
Iron Mobilization ◽  
North East ◽  
Secondary Silica ◽  
Dryland Crops ◽  
Two Stages

The Roi Et soil, a Gleyic Acrisol (FAO, 1974) is one of the main soils on the extensive seasonally wet, low terrace in north-east Thailand. The soil looks poor and produces traditionally low yields of one paddy rice crop/year. With fertilizers and dry-season irrigation, problems of water-logging, surface salinity and acidity caused poor germination and low yields of both rice and dry-season dryland crops. X-ray stereo radiographs, and macro- and micromorphological data indicate that the processes that have taken place in this soil include perforation and homogenization by roots and soil fauna; iron mobilization and redistribution; clay translocation; alteration of clay and formation of secondary silica; and surface slaking alternated with ploughing. The clay translocated appears to be fossil clay. Two stages of iron mobilization under (seasonally) wet conditions are indicated, the later one, with clay alteration, continuing at present. The soil has considerable macroporosity, due to worms and termites, mainly in the subsoil. The ploughpan and the deep subsoil have low porosity. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Problem hydromorphic soils in north-east Thailand. 3. Saline-acid conditions, reclamation, improvement and management.

1977 ◽  
Vol 25 (4) ◽  
pp. 263-277 ◽  
Author(s):  
R. Brinkman ◽  
P.J. Dieleman
Keyword(s):  
Water Table ◽  
Management Practices ◽  
Crop Residues ◽  
Monsoon Season ◽  
Soil Surface ◽  
Dry Season ◽  
Shallow Water Table ◽  
Surface Salinity ◽  
Water Losses ◽  
North East

Saline-acid conditions have developed in patches in the irrigated areas on the low terrace in north-east Thailand. There are also traditionally uncultivated, virtually barren, saline-acid strips adjoining higher terrace remnants, in spite of the excess of monsoon rainfall over evapotranspiration. Calculations show that the salts in the shallow groundwater of the low terrace may have originated from rainfall, but that salts in the main rivers are mainly derived from salt beds. The local surface salinity, mainly of NaCl, is caused by continual evapotranspiration during the dry season and locally impeded leaching. The latter is due to a combination of a shallow water-table, slow vertical permeability and in some cases the slight elevation above the normal level of monsoon flooding. The high salt concentrations in and on the soil surface bring originally exchangeable aluminium into solution, which lowers the pH. In extreme cases even some ferric iron is dissolved at the soil surface. Reclamation, improvement and management practices on these soils should include leaching, for example under two rice crops per year; judicious liming, to eliminate most of the exchangeable aluminium but not to exceed the small buffer capacity of these soils; and emphasis on paddy rice, both in the monsoon season, and, irrigated, in the dry season. If, however, dry-season dryland crops are to be grown, physical problems of different kinds may necessitate further land improvement and management practices. These include, principally, lowering and keeping down the water-table, for example by control of irrigation water losses from canals and ditches; ploughing or disking in chopped crop residues with added nitrogen; and locally, chiselling the upper part of a dense subsurface horizon. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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.

Growth mechanism and characterization of ZnO nano-tubes synthesized using the hydrothermal-etching method

2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Yan Li ◽  
Chuan-Sheng Liu ◽  
Yun-Ling Zou
Keyword(s):  
Room Temperature ◽  
Morphological Analysis ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Etching Method ◽  
Nano Rods ◽  
Two Stages

AbstractZnO nano-tubes (ZNTs) have been successfully synthesized via a simple hydrothermal-etching method, and characterized by X-ray diffraction, field emission scanning electron microscopy and room temperature photoluminescence measurement. The as-synthesized ZNTs have a diameter of 500 nm, wall thickness of 20–30 nm, and length of 5 µm. Intensity of the plane (0002) diffraction peak, compared with that of plane (10$$ \bar 1 $$0) of ZNTs, is obviously lower than that of ZnO nano-rods. This phenomenon can be caused by the smaller cross section of plane (0002) of the nano-tubes compared with that of other morphologies. On basis of the morphological analysis, the formation process of nano-tubes can be proposed in two stages: hydrothermal growth and reaction etching process.

Assessment of Laser Effects on the Structure and Electrical Properties of the Compound Bi2-xAgxSr2Ca2Cu3O10+δ Superconducting

2021 ◽  
Vol 19 (11) ◽  
pp. 108-115
Author(s):  
Nihad Ali Shafeek
Keyword(s):  
Critical Temperature ◽  
Hydraulic Press ◽  
Electrical Characteristics ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
X Ray ◽  
Compensation Ratio ◽  
Superconducting Compound ◽  
State Method ◽  
Two Stages

This research contains preparing the superconducting compound Bi2-xAgxSr2Ca2Cu3O10+δ and studying its structural and electrical characteristics. The samples were prepared using the solid-state method in two stages, and different concentrations of x were (x= 0.2,0.4,0.6,0.8) replaced instead of bismuth Bi. Then, using a hydraulic press 9 ton/cm2 and sintering with a temperature of 850°C, the samples were pressed. Next, x-ray diffraction is used to study the structural properties. The study of these samples was presented in different proportions of x values, where x = 0.4 is the best compensation ratio of x. A critical temperature of 1400C and the Tetragonal structure was got. After that, the effect of laser nidinium _ yak (Nd: YAG laser) was used on the compositional. It was found that the temperature value increased, so we got the best critical temperature, which is 142 0C.

scholarly journals Extraction of γ-Alumina from Low-Cost Kaolin

Resources ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 63
Author(s):  
Khalil Ibrahim ◽  
Mohammad Moumani ◽  
Salsabeela Mohammad
Keyword(s):  
Low Cost ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aluminum Metal ◽  
Alumina Particles ◽  
Two Stages ◽  
Method Of Extraction ◽  
Microcrystalline Powder ◽  
Made In

A combined process is proposed for the utilization of local kaolin to produce alumina particles. The applied process is made in two stages: calcination at 700 °C with sodium chloride and leaching with sulfuric followed by hydrochloric acids. The optimal extraction efficiency can be obtained when the conditions are as follows: leaching temperature is at 140 °C, leaching time is 3 h 45 min and concentration of sulfuric acid is 40 wt.%. The results show that the purity of alumina reaches 79.28%, which is suitable for the production of aluminum metal. It is evident that this method of extraction of alumina from the kaolin ash is practical and feasible. The structural and morphological properties of the calcined microcrystalline powder was characterized by X-ray diffraction and scanning electron microscope (SEM).

scholarly journals Seasonal flooding, instream habitat structure and fish assemblages in the Mulgrave River, north-east Queensland: towards a new conceptual framework for understanding fish-habitat dynamics in small tropical rivers

2008 ◽  
Vol 59 (2) ◽  
pp. 97 ◽  
Author(s):  
Thomas S. Rayner ◽  
Bradley J. Pusey ◽  
Richard G. Pearson
Keyword(s):  
Habitat Structure ◽  
Fish Assemblages ◽  
Fish Habitat ◽  
Dry Season ◽  
Assemblage Structure ◽  
Tropical Rivers ◽  
Wet Season ◽  
Seasonal Flooding ◽  
North East ◽  
Habitat Dynamics

Strong relationships between seasonal flooding, instream habitat structure and fish assemblages have been well documented in large tropical rivers (e.g. the flood pulse concept). However, the mechanics of these relationships are likely to differ substantially in smaller coastal rivers, such as those in Costa Rica, south-east Brazil and Australia’s Wet Tropics. These systems typically feature steep upland streams with short, deeply incised lowland channels and poorly connected floodplains. This hypothesis was investigated by documenting spatial and temporal variation in fish-habitat relationships in the Mulgrave River, north-east Queensland. Sampling was conducted at four lowland sites under a range of flow conditions, from dry-season baseflows to a one-in-ten-year flood. Longitudinal environmental gradients and fine-scale habitat patches were important in regulating fish assemblage structure during the dry season. However, high wet-season flows, constrained by the deep channel, acted as disturbances rather than gentle flood-pulses. In particular, the mobilisation of bed sediments led to scouring of aquatic vegetation and a dramatic reduction in habitat heterogeneity. Seasonal movements of fish led to significant changes in assemblage structure – from a community dominated by Neosilurus ater, Hypseleotris compressa, Awaous acritosus and Redigobius bikolanus during the dry season, to one dominated by Nematalosa erebi, Ambassis agrammus and Glossamia aprion during the wet season. Based on these observations, together with information from the literature, a conceptual model of fish-habitat dynamics is presented that is better suited to small tropical rivers than those developed in larger systems with expansive floodplains.

UV and Solar Light Induced Natural Iron Oxide Activation: Characterization and Photocatalytic Degradation of Organic Compounds

2018 ◽  
Vol 17 (1) ◽  
Author(s):  
S. Belaidi ◽  
L. Mammeri ◽  
H. Mechakra ◽  
W. Remache ◽  
K. Benhamouda ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Oxalic Acid ◽  
Photocatalytic Oxidation ◽  
Diffuse Reflectance Spectroscopy ◽  
Solar Irradiation ◽  
Point Of Zero Charge ◽  
Natural Mineral ◽  
X Ray ◽  
North East ◽  
Natural Iron

Abstract In this study we demonstrate the efficiency of a natural mineral as a photocalyst. This natural mineral was provided from the iron ore deposit from Chaabet-El-Ballout which is located in North-East of Algeria. The characterization analysis of the mineral by the Energy-dispersive X-ray spectroscopy (EDX) revealed that the natural powder has a mixed elemental composition and consist mainly of iron oxide with 50 % of iron. In order to determine the crystal phase composition of the natural iron oxide (NIO), X-ray diffraction (DRX) measurement and infrared absorption spectroscopy (FTIR) were carried out. The results showed that the NIO has a mixed crystal structure composed mainly of hematite and lesser extent of goethite. The specific surface area and the total pore volume of the NIO were 79.015 m2g−1 and 0.0892 cm3g−1 respectively, measured by the Brunauer Emmett–Teller method (BET). The Raman spectrum of the NIO confirmed that the sample has seven characteristic peaks attributable to hematite. The optical properties of soil powder were examined by UV-vis diffuse reflectance spectroscopy (DRS). The pH of point of zero charge (pHpzc) of the adsorbent was determined, a value of 8.3 was found. The photocatalytic activity of the NIO particles was tested by the decomposition of aqueous solution of different class of compounds; phenolic compounds, pesticides and dyes due to their presence in many types of wastewaters. The sorption on the surface of the NIO with photocatalytic oxidation using oxalic acid and hydrogen peroxide would be an effective oxidation process for the removal of contaminants under UV and solar irradiation. High percentages of degradation of 1- Naphtol (1-NP) and Linuron were found about, 94.6 %, 97.2 % respectively, in presence of NIO and H2O2 under UV irradiation. The presence of oxalic acid with NIO enhanced the photodegradation of 2,6-dimethylphenol (2,6-DMP), 2-chlorophenol (2-CP) and Methylene blue (MB) with 72 %, 92 % and 100 % percentages of degradation respectively.

scholarly journals Fracture analysis and countermeasures of the grid switch castings

2020 ◽  
Vol 165 ◽  
pp. 06015
Author(s):  
Chao Feng ◽  
Siyuan Yang ◽  
Qiao Li ◽  
Mengbao Zhou ◽  
Songqi Wu ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Fracture Analysis ◽  
Casting Defects ◽  
Physical And Chemical Properties ◽  
Direct Reading ◽  
X Ray ◽  
Detection Technology ◽  
Two Stages ◽  
Physical And Chemical ◽  
And Chemical Properties

Based on the detection technology of direct reading spectrum, metallographic microscope and X-ray, the defects of the grid switch castings were analyzed. The four main forms of casting fracture were summarized as poor physical and chemical properties, material misuse, casting defects and designing defects. In order to strengthen the quality control of the source of the product, it was proposed to carry out targeted network inspection in the two stages of material arrival and infrastructure acceptance.

scholarly journals Pressure- and Temperature-Induced Insertion of N2, O2 and CH4 to Ag-Natrolite

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4096
Author(s):  
Donghoon Seoung ◽  
Hyeonsu Kim ◽  
Pyosang Kim ◽  
Yongmoon Lee
Keyword(s):  
Unit Cell Volume ◽  
Molecular Size ◽  
Unit Cell ◽  
Volume Changes ◽  
Volume Increase ◽  
X Ray ◽  
Onset Pressure ◽  
Two Stages ◽  
Cell Volumes

This paper aimed to investigate the structural and chemical changes of Ag-natrolite (Ag16Al16Si24O80·16H2O, Ag-NAT) in the presence of different pressure transmitting mediums (PTMs), such as N2, O2 and CH4, up to ~8 GPa and 250 °C using in situ synchrotron X-ray powder diffraction and Rietveld refinement. Pressure-induced insertion occurs in two stages in the case of N2 and O2 runs, as opposed to the CH4 run. First changes of the unit cell volume in N2, O2 and CH4 runs are observed at 0.88(5) GPa, 1.05(5) GPa and 1.84(5) GPa with increase of 5.7(1)%, 5.5(1)% and 5.7(1)%, respectively. Subsequent volume changes of Ag-natrolite in the presence of N2 and O2 appear at 2.15(5) GPa and 5.24(5) GPa with a volume increase of 0.8(1)% and a decrease of 3.0(1)%, respectively. The bulk moduli of the Ag-NAT change from 42(1) to 49(7), from 38(1) to 227(1) and from 49(3) to 79(2) in the case of N2, O2 and CH4 runs, respectively, revealing that the Ag-NAT becomes more incompressible after each insertion of PTM molecules. The shape of the channel window of the Ag-NAT changes from elliptical to more circular after the uptake of N2, O2 and CH4. Overall, the experimental results of Ag-NAT from our previous data and this work establish that the onset pressure exponentially increases with the molecular size. The unit cell volumes of the expanded (or contracted) phases of the Ag-NAT have a linear relationship and limit to maximally expand and contract upon pressure-induced insertion.

scholarly journals Fabrication of Large-Grain Thick Polycrystalline Silicon Thin Films via Aluminum-Induced Crystallization for Application in Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Hsiao-Yeh Chu ◽  
Min-Hang Weng ◽  
Chen Lin
Keyword(s):  
Solar Cells ◽  
Polycrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Silicon Thin Films ◽  
Si Films ◽  
Two Stages ◽  
Induced Crystallization ◽  
Aluminum Induced Crystallization

The fabrication of large-grain 1.25 μm thick polycrystalline silicon (poly-Si) films via two-stage aluminum-induced crystallization (AIC) for application in thin-film solar cells is reported. The induced 250 nm thick poly-Si film in the first stage is used as the seed layer for the crystallization of a 1 μm thick amorphous silicon (a-Si) film in the second stage. The annealing temperatures in the two stages are both 500°C. The effect of annealing time (15, 30, 60, and 120 minutes) in the second stage on the crystallization of a-Si film is investigated using X-ray diffraction (XRD), scanning electron microscopy, and Raman spectroscopy. XRD and Raman results confirm that the induced poly-Si films are induced by the proposed process.

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