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OALib Journal期刊

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匹配条件： “Ochre precipitate” ，找到相关结果约91条。
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OCHRE PRECIPITATES AND ACID MINE DRAINAGE IN A MINE ENVIRONMENT
BRANISLAV Má？A,PETRA PULI？OVá,PETR BEZDI？KA,EVA MICHALKOVá
Ceramics-Silikáty , 2012,
Abstract: This paper is focused to characterize the ochre precipitates and the mine water effluents of some old mine adits and settling pits after mining of polymetallic ores in Slovakia. It was shown that the mine water effluents from two different types of deposits (adits; settling pits) have similar composition and represent slightly acidic sulphate water (pH in range 5.60-6.05, sulphate concentration from 1160 to 1905 g.dm-3). The ochreous precipitates were characterized by methods of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and B.E.T. method for measuring the specific surface area and porosity. The dominant phases were ferrihydrite with goethite or goethite with lepidocrocide.
Clays of volcanic – detrititus strata of North the Bohemian coal basin as a raw material for the preparation of natural mineral pigments
Ji？í Botula,Pavel Rucky,Vlastimil ？epka
Acta Montanistica Slovaca , 2005,
Abstract: Raw materials which are suitable for the preparation of mineral pigments are found in the area of the North Bohemian brown coal basin. Set Experiments on a hydrocyclone were realized as a part of the technological research of the suitability of “bolus” and ochres from the North Bohemian brown coal basin to be applicated as ecological pigments. It was found that this method of processing is suitable for the preparation of the product which can serve as a mineral pigment. Produced pigments were examined concerning their application in the area of paint pigments with a positive result.
On the Pre-Forging Heating Methods for AA2014 Alloy  [PDF]
Richard Turner, William Turner, Hao Wu
World Journal of Engineering and Technology (WJET) , 2023, DOI: 10.4236/wjet.2023.114059
Abstract: The aluminium alloy AA2014 is one of the most widely used of the 2xxx series alloys, owing to its superior strength-to-weight ratio and stiffness. It is commonly forged to shape for use in aerospace parts. Three different small pilot-scale AA2014 billets were subjected to different heating operations, to physically simulate a pre-forge heating operation. The unheated sample and heated samples were then analysed for micro structural evolution and mechanical properties, to understand how the pre-forge heat treatments may vary the starting condition of the alloy before being forged. It was shown that an induction heating process has the greatest impact upon the precipitation distribution. Whilst this variation is commonly considered a negative impact, the opportunity to control the induction heating to promote preferential microstructure at specific locations within the billet may be possible.
A STUDY OF FINE PRECIPITATES IN ALLOYS BY POSITRON ANNIHILATION
Wang Jing-cheng,You Fu-qiang,Yin Jun-lin,Gao Guo-hu,Liang Ling,Duan Yong,
中国物理 B , 2001,
Abstract: Measurements were performed using the positron annihilation technique associated with physical metallurgical techniques for several engineering alloys containing fine precipitates. It is shown that positron annihilation is an effective method to detect fine precipitates, providing a sound basis for a further intense research of these.
A New Method for Research of Grown-In Microdefects in Dislocation-Free Silicon Single Crystals  [PDF]
V.I Talanin, I.E Talanin, N.Ph Ustimenko
Journal of Crystallization Process and Technology (JCPT) , 2011, DOI: 10.4236/jcpt.2011.12003
Abstract: As a virtual experimental device for analysis and calculation of grown-in microdefects formation in undoped silicon dislocation-free single crystals the software is proposed. The software is built on the basis on diffusion model of formation, growth and coalescence of grown-in microdefects. Diffusion model describes kinetics of defect structure changes during cooling after growth on crystallization temperature to room temperature. The software allows the use of personal computer to investigate the defect structure of dislocation-free silicon single crystals with a diameter on 30 mm to 400 mm grown by floating-zone and Czochralski methods.
The Environment Specialities in the Ochtinska Aragonite Cave
Bobro Milan,Hanèu？ák Jozef,Kupka Daniel
Acta Montanistica Slovaca , 2003,
Abstract: The Ochtinska Aragonite Cave became well-known due to its unique decoration created by fruticose-like aggregates of crystalline aragonite. The cave is located in the cadastral territory of the village of Ochtiná on the west side of the Hrádok Mt. that belongs to the Slovenské Rudohorie Mts. During the opening season the cave is frequented. In the last period, an increased amount of CO2 has been detected in air of the Ochtinska aragonite cave. The cave environment is created by caverns - relicts after mouldered ankerites and siderites in surroundings of Palaeozoic slates, limestones and dolomites. The residual ochre loams were created by weathering of carbonates. Probably, these processes held up till now and this fact may also result in the liberation of CO2. From the viewpoint of the enhanced CO2 content, the earths and waters occurred in the cave were found as its possible source. An enhanced CO2 content was also measured in old air-proof closed mine workings, with a possibility of rot processes of old organic mine working components. Probably, has the rich attendance of the cave during the season the highest influence on the enhanced CO2 content. The measurements of CO2 content have pointed to its different values in various periods. In the period without visits, the CO2 content in the cave exceeds that in the external surrounding air by 3-4 times, i. e. 310 330 ppm. In the period of visits, it is 8 10 times. Thus, the CO2 content in the cave depends on the number of visits. Up till now, no influence of the CO2 content variation on the unique karstic forms and the health status of the cave staff was not proven.
Biological reduction of iron to the elemental state from ochre deposits of Skelton Beck in Northeast England
Pattanathu K. S. M. Rahman
Frontiers in Environmental Science , 2014, DOI: 10.3389/fenvs.2014.00022
Abstract: Ochre, consequence of acid mine drainage (AMD), is iron oxides-rich soil pigments that can be found in the water drainage from historic base metal and coal mines. The anaerobic strains of Geobacter sulfurreducens and Shewanella denitrificans were used for the microbial reduction of iron from samples of ochre collected from Skelton Beck (Saltburn Orange River, NZ 66738 21588) in Northeast England. The aim of the research was to determine the ability of the two anaerobic bacteria to reduce the iron present in ochre and to determine the rate of the reduction process. The physico-chemical changes in the ochre sample after the microbial reduction process were observed by the production of zero-valent iron which was later confirmed by the detection of elemental Fe in XRD spectrum. The X-Ray fluorescence (XRF) results revealed that 69.16 and 84.82% of iron oxide can be reduced using G. sulfurreducens and S. denitrificans respectively after 8 days of incubation. These results could provide the basis for the development of a biohydrometallurgical process for the production of elemental iron from ochre sediments.
Ochre Bathing of the Bearded Vulture: A Bio-Mimetic Model for Early Humans towards Smell Prevention and Health
Helmut Tributsch
- , 2016, DOI: 10.3390/ani6010007
Abstract:
Quasi-Static and Dynanmic Deformation Behaviors of Medium-Carbon Steels in a Wide Temperature Range  [PDF]
Byoungchul Hwang
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.26076
Abstract: This paper presents a study of the quasistatic and dynamic deformation behaviors of conventional and microalloyed medium-carbon steels in a wide temperature range. As strain rate increased, the flow stress increased at room temperature, but occasionally did not at elevated temperatures. The flow stress of the microalloyed steel containing precipitates was less sensitive to strain rate at room temperature than that of the conventional steel due to a relatively larger activation length. Microstructural observation of the steels deformed after compression test indicated that inhomogeneous deformation became more serious with increasing strain rate and temperature without fracturing in the highly localized region.
Superspheres: Intermediate Shapes between Spheres and Polyhedra
Susumu Onaka
Symmetry , 2012, DOI: 10.3390/sym4030336
Abstract: Using an x-y-z coordinate system, the equations of the superspheres have been extended to describe intermediate shapes between a sphere and various convex polyhedra. Near-polyhedral shapes composed of {100}, {111} and {110} surfaces with round edges are treated in the present study, where {100}, {111} and {110} are the Miller indices of crystals with cubic structures. The three parameters p, a and b are included to describe the {100}-{111}-{110} near-polyhedral shapes, where p describes the degree to which the shape is a polyhedron and a and b determine the ratios of the {100}, {111} and {110} surfaces.
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