scholarly journals Dissolution of lead matte and copper slag upon exposure to rhizosphere-like conditions

2017 ◽  
Vol 4 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Anna Potysz ◽  
Jakub Kierczak
Keyword(s):  
Root Exudates ◽  
Copper Slag ◽  
Metal Release ◽  
Water Control ◽  
Demineralized Water ◽  
Metallurgical Wastes ◽  
Granulated Slag ◽  
The Stability ◽  
Organic Solutions ◽  
A Minor

Abstract Metallurgical wastes displaying various chemical and mineralogical properties may reveal different behaviour under exposure to weathering conditions. The latter impact the stability of the wastes, which often results in metal release and subsequent pollution problems. The aim of this study was to compare the weathering of two types of metallurgical wastes (i.e., copper slag and lead matte) exposed to artificial root exudates organic solutions and demineralized water. The results of experimental weathering demonstrated that the extent of waste dissolution depends on the composition of weathering solution as well as on the waste properties. Artificial root exudates rich in organic acids were found to enhance elements release from sulphide rich lead matte and copper glassy slag relative to demineralized water control. The release of elements from the wastes exposed to artificial root exudates for 7 weeks reached 17.8% of Pb and 4.97% of Cu, for lead matte and granulated slag respectively. The most leachable elements may result from the dissolution of intermetallic phases hosting these elements. The fraction size ranging from 0.25–0.5 mm to 1–2 mm was found to be a minor factor in elements release under studied conditions.

Polysaccharide Structures in the Outer Mucilage of Arabidopsis Seeds Visualized by AFM

2020 ◽  
Author(s):  
MAK Williams ◽  
V Cornuault ◽  
AH Irani ◽  
VV Symonds ◽  
J Malmström ◽  
...  
Keyword(s):  
Average Length ◽  
American Chemical Society ◽  
Md Simulations ◽  
Chemical Society ◽  
Side Chains ◽  
Rhamnogalacturonan I ◽  
Afm Imaging ◽  
Minor Population ◽  
The Stability ◽  
A Minor

© 2020 American Chemical Society. Evidence is presented that the polysaccharide rhamnogalacturonan I (RGI) can be biosynthesized in remarkably organized branched configurations and surprisingly long versions and can self-assemble into a plethora of structures. AFM imaging has been applied to study the outer mucilage obtained from wild-type (WT) and mutant (bxl1-3 and cesa5-1) Arabidopsis thaliana seeds. For WT mucilage, ordered, multichain structures of the polysaccharide RGI were observed, with a helical twist visible in favorable circumstances. Molecular dynamics (MD) simulations demonstrated the stability of several possible multichain complexes and the possibility of twisted fibril formation. For bxl1-3 seeds, the imaged polymers clearly showed the presence of side chains. These were surprisingly regular and well organized with an average length of ∼100 nm and a spacing of ∼50 nm. The heights of the side chains imaged were suggestive of single polysaccharide chains, while the backbone was on average 4 times this height and showed regular height variations along its length consistent with models of multichain fibrils examined in MD. Finally, in mucilage extracts from cesa5-1 seeds, a minor population of chains in excess of 30 μm long was observed.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

scholarly journals Metal Ion-Binding Properties of the Diphosphate Ester Analogue, Methylphosphonylphosphate, in Aqueous Solution

1999 ◽  
Vol 6 (6) ◽  
pp. 321-328 ◽  
Author(s):  
Bin Song ◽  
Jing Zhao ◽  
Fridrich Gregáň ◽  
Nadja Prónayová ◽  
S. Ali A. Sajadi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Minor Role ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ph Titration ◽  
Role Based ◽  
The Stability ◽  
A Minor ◽  
Complex Stabilities

The stability constants of the 1:1 complexes formed between methylphosphonylphosphate (MePP3-), CH3P(O)2--O-PO32- , and Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+,​ or Cd2+ (M2+) were determined by potentiometric pH titration in aqueous solution (25 C° ; l = 0.1 M, NaNO3 ). Monoprotonated M(H;MePP) complexes play only a minor role. Based on previously established correlations for M2+ -diphosphate monoester complex-stabilities and diphosphate monoester β-group. basicities, it is shown that the M(Mepp)- complexes for Mg2+ and the ions of the second half of the 3d series, including Zn2+ and Cd2+, are on average by about 0.15 log unit more stable than is expected based on the basicity of the terminal phosphate group in MePP3-. In contrast, Ba(Mepp)- and Sr(Mepp)- are slightly less stable, whereas the stability for Ca(Mepp)- is as expected, based on the mentioned correlation. The indicated increased stabilities are explained by an increased basicity of the phosphonyl group compared to that of a phosphoryl one. For the complexes of the alkaline earth ions, especially for Ba2+, it is suggested that outersphere complexation occurs to some extent. However, overall the M(Mepp)- complexes behave rather as expected for a diphosphate monoester ligand.

scholarly journals Analysis of the Phenomena Causing Weave and Wobble in Two-Wheelers

2020 ◽  
Vol 10 (19) ◽  
pp. 6826
Author(s):  
Francesco Passigato ◽  
Andreas Eisele ◽  
Dirk Wisselmann ◽  
Achim Gordner ◽  
Frank Diermeyer
Keyword(s):  
Simulation Models ◽  
Physical Analysis ◽  
Time Behaviour ◽  
Oscillation Modes ◽  
Rigid Body Simulation ◽  
The Stability ◽  
A Minor ◽  
Physical Phenomena ◽  
Relevant Work ◽  
Mechanical Momentum

The present work follows in the tracks of previous studies investigating the stability of motorcycles. Two principal oscillation modes of motorcycles are the well-known wobble and weave modes. The research in this field started about fifty years ago and showed how different motorcycle parameters influence the stability of the mentioned modes. However, there is sometimes a minor lack in the physical analysis of why a certain parameter influences the stability. The derived knowledge can be complemented by some mechanical momentum correlations. This work aims to ascertain, in depth, the physical phenomena that stand behind the influence of fork bending compliance on the wobble mode and behind the velocity dependence of the weave damping behaviour. After a summary of the relevant work in this field, this paper presents different rigid body simulation models with increasing complexity and discusses the related eigenvalue analysis and time behaviour. With these models, the mentioned modes are explained and the physical phenomena only partly covered by the literature are shown. Finally, the influence of the rider model on weave and wobble is presented.

scholarly journals Pyrithione metal (Cu, Ni, Ru) complexes as photo-catalysts for styrene oxide production

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Venkata D. B. C. Dasireddy ◽  
Jerneja Kladnik ◽  
Romana Cerc Korošec ◽  
Blaž Likozar ◽  
Iztok Turel
Keyword(s):  
Metal Complexes ◽  
Uv Light ◽  
Styrene Oxide ◽  
Alkyl Substituent ◽  
Photochemical Oxidation ◽  
Ru Complexes ◽  
The Stability ◽  
A Minor ◽  
Rate Conversion ◽  
Acetonitrile Medium

AbstractSelective photochemical oxidation of styrene was performed in an active acetonitrile medium, using H2O2 with or without ultraviolet (UV) light radiation. Pyrithione metal complexes (M–Pth: M = Cu(II), Ni(II), Ru(II); Pth = 2-mercaptopyridine-N-oxide) were used as catalysts. Catalytic testing measurements were done by varying the time, chemical reaction temperature and H2O2 concentration with or without UV energy. Epoxide styrene oxide (SO), benzaldehyde and acetophenone were the major synthesized products. A high batch rate, conversion and selectivity towards SO was shown in the presence of UV. A minor constant formation of CO2 was observed in the stream. Coordinated Ru-based compounds demonstrated the highest process productivity of SO at 60 °C. The effect of the functional alkyl substituent on the ligand Pth, attached to the specific ruthenium(II) centre, decreased the activity of the substance. Ni-Pth selectively yielded benzaldehyde. The stability of the catalysts was examined by applying nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis coupled with mass spectrometry. Tested metal complexes with pyrithione (M–Pth) exhibited excellent reuse recyclability up to 3 cycles.

On the Influence of Contact Geometry on Grasp Stability

2008 ◽  
Author(s):  
Gert A. Kragten ◽  
Just L. Herder ◽  
A. L. Schwab
Keyword(s):  
Contact Stiffness ◽  
Contact Geometry ◽  
Contact Forces ◽  
Minor Effect ◽  
Dynamic Simulations ◽  
Normal Contact ◽  
Contact Points ◽  
Grasp Stability ◽  
The Stability ◽  
A Minor

This paper demonstrates that the predicted grasp stability is highly sensitive to only small changes in the character of the contact forces. The contribution of the geometry and stiffness at the contact points to the grasp stability is investigated by a planar grasp with three contact points. Limit cases of zero and infinite contact curvatures, and finite to infinite contact stiffnesses are considered. The stability is predicted based on the approach of Howard and Kumar [1], and verified with multibody dynamic simulations. For rigid objects and fingers with only normal contact stiffness, the grasp stability is dominated by the contact geometry, whereas the local contact stiffness and preload have a minor effect. Furthermore, grasps with pointed finger tips are more likely to be stable than grasps with flat finger tips.

Enhancement of plasticity in Zr-based bulk metallic glasses

2007 ◽  
Vol 22 (9) ◽  
pp. 2454-2459 ◽  
Author(s):  
X.D. Wang ◽  
L. Yang ◽  
J.Z. Jiang ◽  
K. Saksl ◽  
H. Franz ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Concentration Ratio ◽  
Bulk Metallic Glasses ◽  
Amorphous Structure ◽  
Catastrophic Failure ◽  
X Ray Diffraction ◽  
Present Evidence ◽  
X Ray ◽  
The Stability ◽  
A Minor

We present evidence that a minor adjustment in Zr/Ni concentration ratio can dramatically enhance the plasticity of monolithic Zr-based bulk metallic glasses (BMGs) from about 2.2% for Zr65Al8Ni10Cu17 BMG to 14% for Zr62Al8Ni13Cu17 BMG. No deformation-induced nanocrystallization appears in a 55% strained Zr62Al8Ni13Cu17 BMG without catastrophic failure while pre-existing nanocrystals in Zr65Al8Ni10Cu17 BMG result in its limited plasticity. Also note that the stability of Zr62Al8Ni13Cu17 BMG against crystallization upon deformation is somewhat higher than that of Zr65Al8Ni10Cu17 BMG. As determined by x-ray diffraction using synchrotron radiation, the enhanced plasticity of Zr62Al8Ni13Cu17 BMG seems to be related to the relative homogeneity of the amorphous structure.

scholarly journals Sequential Bioleaching of Pyritic Tailings and Ferric Leaching of Nonferrous Slags as a Method for Metal Recovery from Mining and Metallurgical Wastes

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1097
Author(s):  
Natalya Fomchenko ◽  
Maxim Muravyov
Keyword(s):  
Nonferrous Metal ◽  
Microbial Consortium ◽  
Copper Slag ◽  
Leach Solution ◽  
Nonferrous Metals ◽  
Oxidizing Agent ◽  
Total Recovery ◽  
Metallurgical Wastes ◽  
Efficient Extraction ◽  
Ferric Leaching

In this work, we proposed a method for biohydrometallurgical processing of mining (old pyritic flotation tailings) and metallurgical (slag) wastes to recover gold and other nonferrous metals. Since this processing allows the removal of toxic metals or at least decreases their content in the solids, this approach may reduce the negative environmental impacts of such waste. The proposed process was based on pyritic tailings’ bioleaching to recover metals and produce leach liquor containing a strong oxidizing agent (ferric sulfate) to dissolve nonferrous metal from slag. This approach also allows us to increase concentrations of nonferrous metals in the pregnant leach solution after pyritic waste bioleaching to allow efficient extraction. The old pyritic tailings were previously leached with 0.25% sulfuric acid for 10 min to remove soluble metal sulfates. As a result, 36% of copper and 35% of zinc were extracted. After 12 days of bioleaching with a microbial consortium containing Leptospirillum spp., Sulfobacillus spp., Ferroplasma spp., and Acidithiobacillus spp. at 35 °C, the total recovery of metals from pyritic tailings reached 68% for copper and 77% for zinc; and subsequent cyanidation allowed 92% recovery of gold. Ferric leaching of two types of slag at 70 °C with the leachate obtained during bioleaching of the tailings and containing 15 g/L of Fe3+ allowed 88.9 and 43.4% recovery of copper and zinc, respectively, from copper slag within 150 min. Meanwhile, 91.5% of copper, 84.1% of nickel, and 70.2% of cobalt were extracted from copper–nickel slag within 120 min under the same conditions.

scholarly journals Thermostatic cover for improving energy and technological efficiency of steel mills

2019 ◽  
Vol 110 ◽  
pp. 01003
Author(s):  
Konstantin Strogonov ◽  
Sergey Tolkanov ◽  
Karina Korkots ◽  
Alexander Fedyukhin
Keyword(s):  
Steel Casting ◽  
Energy Savings ◽  
Casting Process ◽  
Technical Solution ◽  
Metal Release ◽  
Thermal Fields ◽  
Steel Mills ◽  
Stable Production ◽  
Technological Efficiency ◽  
The Stability

The article proposes a technical solution for reducing the energy costs of casting process and providing more stable production conditions, specifically, the use of a thermostatic cap. Two variants of steel casting are considered: with and without the application of a thermostatic cover using the example of a bucket with a capacity of six tons of steel. The technical challenge is to reduce heat losses through the bucket neck to ensure the stability of the melting temperature throughout the casting and to reduce the temperature of metal release from the steelmaking unit. The design of the thermostatic cover with specifications, as well as the duration of process steps in the steel casting with and without the use of a thermally insulated cap are described. The balance calculations were carried out using MathCAD environment, which confirmed significant energy savings with a slight increase in casting time associated with the appearance of an additional technological operation for installing the thermostatic cover after pouring. Using ANSYS Academic software, a study was carried out on the thermal fields of the ladle and steel at various stages of casting for two options, which confirmed the effectiveness of using a thermostatic cover.

scholarly journals Stability Effects of Non-Circular Geometry in Floating Ring Bearings

Lubricants ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 99
Author(s):  
Giovanni Adiletta
Keyword(s):  
Equilibrium Position ◽  
Transient Analysis ◽  
Numerical Study ◽  
Theoretical Aspect ◽  
Static Equilibrium ◽  
Geometrical Parameters ◽  
Nonlinear Transient ◽  
Minor Part ◽  
The Stability ◽  
A Minor

The present study theoretically evaluates the stability potential of noncircular geometries when they are adopted in the outer bearing of floating ring bearings (FRB). A numerical study is carried out to evaluate the stability about the static equilibrium position of a balanced, symmetrical, rigid rotor, horizontally placed, and supported at both ends by identical FRBs. In the analysis, the outer bearing of these FRBs is alternatively shaped with common circular bore (CB), two lobe-wave bore (2LWB) or lemon bore (LB), assuming a linearization of the film forces. A minor part of the study consists of partially supporting the results of the above study by means of a nonlinear, transient analysis. Despite limiting to the theoretical aspect, dealt with under several simplifying hypotheses, the investigation highlights the influence of the examined non-circular geometries on the stability of the static equilibrium position, when these geometries are adopted for shaping the outer housing of the FRB. The paper shows that contrasting effects are obtained, depending on the chosen geometrical parameters. In the paper, the acronyms CB, 2LWB, and LB are used to indicate the FRB layouts respectively equipped with outer circular, wave, and lemon bearing.

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