Thermodynamics of the isotopic effects of the structural changes in water, associated with the hydration of the ions of the elements of subgroups IA, IIA, and VIIA at different temperatures

1981 ◽  
Vol 21 (4) ◽  
pp. 503-506
Author(s):  
V. K. Abrosimov ◽  
G. N. Makarov ◽  
G. A. Krestov
Keyword(s):  
Structural Changes ◽  
Different Temperatures ◽  
Isotopic Effects

Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze

2018 ◽  
Vol 69 (5) ◽  
pp. 1055-1059 ◽  
Author(s):  
Mariana Ciurdas ◽  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Alina Daniela Necsulescu ◽  
Cosmin Cotrut ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Structural Changes ◽  
Heating Temperature ◽  
Galvanic Corrosion ◽  
Cooling Water ◽  
Open Circuit ◽  
Water Quenching ◽  
Heat Treated ◽  
Different Temperatures

Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.

Research of Different Noise Barriers Efficiency at Different Temperature

2017 ◽  
Author(s):  
Tomas Vilniškis ◽  
Tomas Januševicius
Keyword(s):  
Air Temperature ◽  
Noise Level ◽  
Structural Changes ◽  
Field Measurements ◽  
Sound Waves ◽  
Noise Barriers ◽  
Different Temperatures ◽  
Noise Measurements ◽  
Noise Barrier ◽  
Key Aspects

In this article was analyzed acoustic efficiency of two different construction noise barriers. Field measurements of noise tests were carried out before and behind a wooden barrier, which height was 2.9 meters and a wooden wall with equipped roof, which height was 3.2 m. As is known the length of the wall, height, surface roughness, shape and material of the wall – key aspects of determining the effectiveness of noise barrier. Different materials, depending on their characteristics of the hard or soft, porous or dense, interact differently with the sound of waves. Article contains research results of noise measurements at positive and negative air temperature. There analyzing wooden noise barrier acoustic efficiency at different temperatures and the effects of temperature to the diffraction of sound waves through the peak of the barrier. Test results show, that noise barrier without structural changes reduced noise level to 14–22 dB, noise barrier with structural changes reduced noise level to 20–23,1 dB, when air temperature was positive. When air temperature was negative, noise barrier without structural changes reduced noise level to 15,5–21,4 dB, noise level with structural changes to 19–26,6 dB.

scholarly journals Phosphorus implantation of Mg-doped (Al)GaN heterostructures: structural examination and depth profiling

2020 ◽  
Vol 31 (20) ◽  
pp. 17892-17902
Author(s):  
Karolina Piętak ◽  
Sebastian Złotnik ◽  
Ewelina Rozbiegała ◽  
Paweł P. Michałowski ◽  
Marek Wójcik ◽  
...  
Keyword(s):  
Structural Changes ◽  
Depth Profiling ◽  
Elemental Distribution ◽  
Structural Examination ◽  
Aluminium Gallium Nitride ◽  
Different Temperatures ◽  
P Diffusion ◽  
Bandgap Semiconductors ◽  
P Type ◽  
Mg Doped

AbstractPhosphorus introduction into Mg-doped aluminium gallium nitride ((Al)GaN) epilayers to enhance the acceptor activation is a possible strategy for a p-type conductivity improvement in III-nitride wide-bandgap semiconductors. To date, P-implanted Mg-doped (Al)GaN structures have not been systematically evaluated, regarding structural verification and elemental distribution. Here, comprehensive studies of P ions impact on structural degradation are presented. Furthermore, a post-implantation annealing conducted at different temperatures is examined as well. The results demonstrated that the structural changes in the examined compounds, namely GaN and Al0.1Ga0.9N, due to P implantation and a subsequent recovery by thermal annealing follow similar trends. Interestingly, it was revealed that P diffusion length is higher in AlGaN than in GaN, possibly due to higher oxygen content in Al-containing compounds, analogous to Mg dopant. Additionally, the initial Mg concentration in (Al)GaN is crucial because too high Mg doping could be the main cause of electrical properties degradation of (Al)GaN heterostructures after P ion implantation.

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. III. Thermodynamics of hydrogen bromide and hydrogen iodide from water to aqueous solutions of sodium nitrate from emf measurements at different temperatures and the structuredness of the solvents

1987 ◽  
Vol 65 (12) ◽  
pp. 2843-2848
Author(s):  
Sibaprasad Rudra ◽  
Himansu Talukdar ◽  
Kiron K. Kundu
Keyword(s):  
Sodium Nitrate ◽  
Structural Changes ◽  
Hydrogen Bromide ◽  
Scaled Particle Theory ◽  
Relative Order ◽  
Emf Measurements ◽  
Solvent Interactions ◽  
Different Temperatures ◽  
Composition Profiles ◽  
The Individual

Standard free energies [Formula: see text] and entropies [Formula: see text] of transfer of hydrogen bromide and iodide from water to the aqueous 1, 2, and 4 m of sodium nitrate have been determined by measuring the emf's of the cell: Pt, H2(g, 1 atm)/KOH(m1), KX(m2), solvent/AgX–Ag where X = Br or I at five equidistant temperatures ranging from 15–35°C. [Formula: see text] values of HBr, HI as well as that of HCl obtained from earlier paper and particularly of the individual ions [Formula: see text](i), obtained by use of modified TATB assumption reported earlier and also [Formula: see text](i) obtained after correcting for "cavity" effect and Born-type electrostatic effect estimated tentatively by the scaled particle theory (SPT) and simple Bom equation, respectively, reveal the relative order of stabilisation of Cl−, Br−, and I− ions. Analysis of [Formula: see text]–composition profile (X = Cl, Br, and I) exhibits a characteristic "maxima" around 1.5 m NaNO3 with the relative order HI > HBr > HCl in the region of maxima. Moreover, dissection of [Formula: see text] values into the individual ion contributions by use of the modified TATB assumption reported earlier, results in the characteristic "maxima" around 1.5 m NaNO3 in [Formula: see text] or [Formula: see text]–composition profiles for H+ and "minima" for Cl−, Br−, and I−. The results are discussed in terms of ion–ion–solvent interactions as well as the structural changes of the solvents.

EVALUATION OF NANOCRYSTALLINE BA(ZRXTI1-X)O3 PRODUCED BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 472-479
Author(s):  
M. Hajfathalian ◽  
Z. A. Nemati ◽  
H. R. Madaah Hosseini
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Structural Changes ◽  
Ferroelectric Properties ◽  
High Energy ◽  
Structural Development ◽  
Transition Electron Microscopy ◽  
Nano Crystalline ◽  
High K ◽  
Different Temperatures

BaTiO 3-based solid solutions involve high piezoelectric and ferroelectric properties. One of the most favorable systems of this material is Ba ( Zr x Ti 1- x ) O 3. While nano structured ceramics of which have a great potential for using them in capacitors, actuators, transducers and dielectrics to reach high K values. In this study, nano crystalline Ba ( Zr x Ti 1- x ) O 3( x =0.1-0.8) which is called BZT composite has been prepared by mechanical alloying. The parameters affecting the process and properties were evaluated. The starting powders that are used here were nano sized high pure ZrO 2; submicron sized high pure TiO 2 and BaCO 3. The prepared powder was calcined, compacted and sintered at different temperatures and in various times. The structural changes and phase developments during mechanical alloying were studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM). The results showed that by using mechanical alloying method, high dense nano crystalline BZT ceramics were obtained successfully at very low sintering temperature. The dielectric constant of BZT was much great, because of using nano materials in this method at the temperatures of 1250-1400°C. The effect of high energy milling in micro structural development of nano crystalline BZT has been discussed as well as dielectric properties.

scholarly journals Temperature-responsive in vitro RNA structurome of Yersinia pseudotuberculosis

2016 ◽  
Vol 113 (26) ◽  
pp. 7237-7242 ◽  
Author(s):  
Francesco Righetti ◽  
Aaron M. Nuss ◽  
Christian Twittenhoff ◽  
Sascha Beele ◽  
Kristina Urban ◽  
...  
Keyword(s):  
Structural Changes ◽  
Yersinia Pseudotuberculosis ◽  
Dynamic Condition ◽  
Rna Structures ◽  
Bacterial Rna ◽  
Different Temperatures ◽  
Metabolic Transition ◽  
Regulatory Potential ◽  
Response To Temperature

RNA structures are fundamentally important for RNA function. Dynamic, condition-dependent structural changes are able to modulate gene expression as shown for riboswitches and RNA thermometers. By parallel analysis of RNA structures, we mapped the RNA structurome of Yersinia pseudotuberculosis at three different temperatures. This human pathogen is exquisitely responsive to host body temperature (37 °C), which induces a major metabolic transition. Our analysis profiles the structure of more than 1,750 RNAs at 25 °C, 37 °C, and 42 °C. Average mRNAs tend to be unstructured around the ribosome binding site. We searched for 5′-UTRs that are folded at low temperature and identified novel thermoresponsive RNA structures from diverse gene categories. The regulatory potential of 16 candidates was validated. In summary, we present a dynamic bacterial RNA structurome and find that the expression of virulence-relevant functions in Y. pseudotuberculosis and reprogramming of its metabolism in response to temperature is associated with a restructuring of numerous mRNAs.

Electronic and Structural Requisites for Catalytic Activity in Copper-Ruthenium Catalysts

1994 ◽  
Vol 368 ◽  
Author(s):  
M. Malaty ◽  
D. Singh ◽  
Noel Vadel ◽  
M.L. Gomez ◽  
M. Palmieri ◽  
...  
Keyword(s):  
Structural Changes ◽  
Supported Catalyst ◽  
Ruthenium Catalysts ◽  
Molecular Techniques ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Different Temperatures ◽  
Electron Paramagnetic ◽  
Reduced Forms

ABSTRACTA system made by combining two non-alloying metals, ruthenium and copper, using alumina as a support was studied. This bimetallic supported catalyst has been used mainly in hydrogenolysis, dehydrogenation and oxidation reactions of hydrocarbons. The samples were characterized by Electron Paramagnetic Resonance Spectrometry (EPR) and X-ray Diffraction (XRD). These two molecular techniques are ideal for studying the electronic and structural changes of the samples at different temperatures and concentrations. Catalytic reactions were performed using the catalyst in the reduced and non-reduced forms on a series of catalytic hydrogenations. A correlation between the electronic, structural and catalytic properties has been made. A correlation of catalytic process to molecular phenomena has yield a better understanding of the catalytic site.

Nanostructure Formation in Austenitic Stainless Steel

2008 ◽  
Vol 140 ◽  
pp. 173-178 ◽  
Author(s):  
Agnieszka T. Krawczynska ◽  
Małgorzata Lewandowska ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Stainless Steels ◽  
Structural Changes ◽  
Annealing Temperature ◽  
True Strain ◽  
Nano Structure ◽  
Uniform Microstructure ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Different Temperatures ◽  
Nano Grains

Samples of 316LVM stainless steels were hydrostatically extruded in a multi-step process to a total true strain of 1,84 and subsequently annealed at different temperatures. The structural changes occurring as a result of HE and annealing were observed using a transmission electron microscope. The microhardness of the samples was measured using a load of 200g. The results show that hydrostatic extrusion results in a uniform microstructure characterized by a high density of nano-twins. Subsequent annealing at 600°C produces a partial transformation to a nano structure of average grain size 54 nm. At an annealing temperature of 700°C a fullyrecrystallized uniform microstructure consisting of 68 nm diameter nano-grains was formed. It should be noted that 700°C is much lower than that required to recrystallize a micro-grained alloy of the same composition. The microstructural changes which occurred during annealing have a significant effect on the mechanical properties. The microhardness after HE increased following annealing at 500°C. However, annealing at 800°C resulted in a drop in microhardness, indicating the occurrence of grain growth.

Formation of lubricant and other films on clean metal surfaces: a study by electron diffraction

1952 ◽  
Vol 212 (1111) ◽  
pp. 459-462 ◽  
Keyword(s):  
Electron Diffraction ◽  
Metal Surfaces ◽  
Structural Changes ◽  
High Vacuum ◽  
The Body ◽  
Oriented Films ◽  
Different Temperatures ◽  
Published Paper ◽  
Very High ◽  
Clean Metal

In a recently published paper (Courtel 1950), the author has collected the results of researches carried out during the last few years on clean metal surfaces. These have been obtained by‘ grinding in a very high vacuum (10 -4 to 10 -5 mm of mercury) within the body of an electron diffraction camera. The surface may be examined by diffraction immediately after preparation, and it is also possible to study the effect of the admission of controlled amounts of gas, inert or otherwise. With iron, for example, it is found that the vapours of fatty materials are adsorbed and form oriented films. On the other hand, with cerium an oxide is formed which has not hitherto been isolated (sesquioxide Ce 2 O 2 cubic). By observing the oxides and their structural changes, it is also possible to determine, in certain cases, the surface temperature developed by grinding. The author provides details of an apparatus in the course of construction under the auspices of I.R.S.I.D. (Institut des Recherches Sidérurgiques Françaises) which is to be used for extending these investigations. In particular, this apparatus contains a separate preparation chamber, so that the action of certain sulphurized compounds, especially on clean surfaces, may be studied at different temperatures.

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