scholarly journals Microstructural Features in Multicore Cu–Nb Composites

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7033
Author(s):  
Elena N. Popova ◽  
Irina L. Deryagina ◽  
Evgeniya G. Valova-Zaharevskaya ◽  
Maria Letizia Ruello ◽  
Vladimir V. Popov
Keyword(s):  
Structural Changes ◽  
Longitudinal Direction ◽  
Copper Matrix ◽  
Interplanar Distance ◽  
Fiber Texture ◽  
Matrix Lattice ◽  
Lattice Distortions ◽  
Evolution Of Microstructure ◽  
Copper Shell

The study is devoted to heavily drawn multicore Cu–18Nb composites of cylindrical and rectangular shapes. The composites were fabricated by the melt-and-deform method, namely, 600 in situ rods of Cu–18%Nb alloy were assembled in a copper shell and cold-drawn to a diameter of 15.4 mm (e = 10.2) and then rolled into a rectangular shape the size of 3 × 5.8 mm (e = 12.5). The specimens were analyzed from the viewpoints of their microstructure, microhardness, and thermal stability. The methods of SEM, TEM, X-ray analysis, and microhardness measurements were applied. It is demonstrated that, at higher strain, the fiber texture <110>Nb <111>Cu DD (drawing direction), characteristic of this material, becomes sharper. The distortions of niobium lattice can be observed, namely, the {110} Nb interplanar distance is broadened in longitudinal direction of specimens and compacted in transverse sections. The copper matrix lattice is distorted as well, though its distortions are much less pronounced due to its recrystallization. Evolution of microstructure under annealing consists mainly in the coagulation of ribbon-like Nb filaments and in the vanishing of lattice distortions. The structural changes in Nb filaments start at 300–400 °С, then develop actively at 600 °С and cause considerable decrease of strength at 700–800 °С.

scholarly journals In Situ Thermal-Stage Fitted-STEM Characterization of Spherical-Shaped Co/MoS2 Nanoparticles for Conversion of Heavy Crude Oils

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1239
Author(s):  
Manuel Ramos ◽  
Félix Galindo-Hernández ◽  
Brenda Torres ◽  
José Manuel Domínguez-Esquivel ◽  
Martin Heilmaier
Keyword(s):  
Molybdenum Disulfide ◽  
Sodium Molybdate ◽  
Interlayer Spacing ◽  
Scanning Transmission Electron Microscope ◽  
Interplanar Distance ◽  
Scanning Transmission ◽  
Heavy Crude ◽  
C 50 ◽  
Nano Catalysts

We report the thermal stability of spherically shaped cobalt-promoted molybdenum disulfide (Co/MoS2) nano-catalysts from in-situ heating under electron irradiation in the scanning transmission electron microscope (STEM) from room temperature to 550 °C ± 50 °C with aid of Fusion® holder (Protochip©, Inc.). The catalytic nanoparticles were synthesized via a hydrothermal method using sodium molybdate (Na2MoO4·2H2O) with thioacetamide (CH3CSNH2) and cobalt chloride (CoCl2) as promoter agent. The results indicate that the layered molybdenum disulfide structure with interplanar distance of ~0.62 nm remains stable even at temperatures of 550 °C, as observed in STEM mode. Subsequently, the samples were subjected to catalytic tests in a Robinson Mahoney Reactor using 30 g of Heavy Crude Oil (AGT-72) from the golden lane (Mexico’s east coast) at 50 atm using (ultrahigh purity) UHP hydrogen under 1000 rpm stirring at 350 °C for 8 h. It was found that there is no damage on the laminar stacking of Co/MoS2 with temperature, with interlayer spacing remaining at 0.62 nm; these sulfided catalytic materials led to aromatics rise of 22.65% and diminution of asphaltenes and resins by 15.87 and 3.53%, respectively.

Roughened gold electrode for in situ SERS analysis of structural changes accompanying the doping process of polyaniline in acidic aqueous media

2021 ◽  
Vol 882 ◽  
pp. 115034
Author(s):  
A. El Guerraf ◽  
M. Bouabdallaoui ◽  
Z. Aouzal ◽  
S. Ben Jadi ◽  
N.K. Bakirhan ◽  
...  
Keyword(s):  
Gold Electrode ◽  
Structural Changes ◽  
Aqueous Media

In Situ Synchrotron X-Ray Diffraction Study of a Deformed Cu-Fe-P Alloy during Heating

2016 ◽  
Vol 850 ◽  
pp. 191-196 ◽  
Author(s):  
Wei Wang ◽  
Cun Lei Zou ◽  
Ren Geng Li ◽  
Wen Wen ◽  
Hui Jun Kang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lattice Distortion ◽  
Copper Matrix ◽  
Heating Process ◽  
Recrystallization Process ◽  
Full Width ◽  
X Ray Diffraction ◽  
Dramatic Decrease ◽  
X Ray

In situ synchrotron X-ray diffraction was used to study a deformed Cu-0.88 Fe-0.24 P alloy during heating process. The measurements were performed at room temperature and also at high temperatures up to 893 K in order to determine the recovery, ageing and recrystallization process. With the increase of temperature, the angles of copper matrix peaks moved left and the FWHM (full width at half maximum) decreased slightly. Fe3P precipitates were first detected at 533 K, reached the maximum at 673 K, and re-dissolved into matrix at 853 K. A dramatic decrease in FWHM was observed accompanied by the precipitation of Fe3P phases, indicating the reduction of lattice distortion of copper matrix.

scholarly journals High temperature structural study of decagonal Al-Cu-Rh quasicrystal.

2014 ◽  
Vol 70 (a1) ◽  
pp. C94-C94
Author(s):  
Pawel Kuczera ◽  
Walter Steurer
Keyword(s):  
Structural Changes ◽  
Configurational Entropy ◽  
Lattice Vibrations ◽  
X Ray Diffraction ◽  
Stabilization Mechanism ◽  
X Ray ◽  
Comparative Structure ◽  
The Stability

The structure of d(ecagonal)-Al-Cu-Rh has been studied as a function of temperature by in-situ single-crystal X-ray diffraction in order to contribute to the discussion on energy or entropy stabilization of quasicrystals (QC) [1]. The experiments were performed at 293 K, 1223 K, 1153 K, 1083 K, and 1013 K. A common subset of 1460 unique reflections was used for the comparative structure refinements at each temperature. The results obtained for the HT structure refinements of d-Al-Cu-Rh QC seem to contradict a pure phasonic-entropy-based stabilization mechanism [2] for this QC. The trends observed for the ln func(I(T1 )/I(T2 )) vs.|k⊥ |^2 plots indicate that the best on-average quasiperiodic order exists between 1083 K and 1153 K, however, what that actually means is unclear. It could indicate towards a small phasonic contribution to entropy, but such contribution is not seen in the structure refinements. A rough estimation of the hypothetic phason instability temperature shows that it would be kinetically inaccessible and thus the phase transition to a 12 Å low T structure (at ~800 K) is most likely not phason-driven. Except for the obvious increase in the amplitude of the thermal motion, no other significant structural changes, in particular no sources of additional phason-related configurational entropy, were found. All structures are refined to very similar R-values, which proves that the quality of the refinement at each temperature is the same. This suggests, that concerning the stability factors, some QCs could be similar to other HT complex intermetallic phases. The experimental results clearly show that at least the ~4 Å structure of d-Al-Cu-Rh is a HT phase therefore entropy plays an important role in its stabilisation mechanism lowering the free energy. However, the main source of this entropy is probably not related to phason flips, but rather to lattice vibrations, occupational disorder unrelated to phason flips like split positions along the periodic axis.

Alterations of band 3 transport protein by cellular aging and disease: erythrocyte band 3 and glucose transporter share a functional relationship

1990 ◽  
Vol 68 (12) ◽  
pp. 1419-1427 ◽  
Author(s):  
Gieljan J. C. G. M. Bosman ◽  
Marguerite M. B. Kay
Keyword(s):  
Glucose Transport ◽  
Structural Changes ◽  
Glucose Transporter ◽  
Functional Relationship ◽  
Band 3 ◽  
Anion Transport ◽  
Cellular Aging ◽  
Abnormal Band ◽  
Membrane Spanning

Structural changes in human erythrocyte band 3 that affect anion transport are correlated with changes in glucose transport in situ. Breakdown of band 3, observed during normal erythrocyte aging in situ and in some diseases involving erythrocytes, is associated with an increase in Km and a decrease in Vmax of sulfate self-exchange, and with an increase in Km and Vmax of glucose efflux. Erythrocytes containing a high molecular weight form of band 3 exhibit an increase in Vmax of sulfate exchange and a decrease in Vmax of glucose efflux. Identical transport characteristics are observed in abnormal band-3-containing erythrocytes from individuals with familial amyotrophic chorea with acanthocytosis. A third band 3 alteration, fast-aging band 3, exhibits decreased Vmax of sulfate exchange and an increase in Km and decrease in Vmax of glucose efflux. Changes in band 3 structure that are the result of unstable hemoglobin or a deficiency in glucose-6-phosphate dehydrogenase and that do not affect anion transport have no effect on glucose transport characteristics. These data indicate the existence of a functional relationship between the membrane-spanning, anion-transport domain of band 3 and glucose transport in human erythrocytes. Antibodies to synthetic peptides reveal structural changes in membranes from the three inborn band 3 alterations and in band 3 itself in membranes from fast-aging band 3. Thus, immunological data suggests a structural relationship between anion and glucose transporters.Key words: red cell, anion transport, membrane proteins, aging, choreoacanthocytosis, anemia.

scholarly journals The Effect of Bile Salts on the Permeability and Ultrastructure of the Perfused, Energy-Depleted, Rat Blood-Brain Barrier

1991 ◽  
Vol 11 (4) ◽  
pp. 644-654 ◽  
Author(s):  
J. Greenwood ◽  
J. Adu ◽  
A. J. Davey ◽  
N. J. Abbott ◽  
M. W. B. Bradbury
Keyword(s):  
Blood Brain Barrier ◽  
Bile Salts ◽  
Structural Changes ◽  
Sodium Deoxycholate ◽  
Ringer Solution ◽  
Brain Barrier ◽  
Rat Blood ◽  
Blood Brain ◽  
Ultrastructural Damage

The action of bile salts upon the rat blood–brain barrier (BBB) was assessed in the absence of energy-yielding metabolism. Brains were perfused in situ with a Ringer solution for 5 min followed by a 1 min perfusion containing either sodium deoxycholate (DOC), taurochenodeoxycholate (TCDC), or Ringer/DNP. The integrity of the BBB was then determined by perfusing with the radiotracer [14C]mannitol for 2.5 min. Alternatively, the brains were perfusion fixed for ultrastructural assessment. At 0.2 m M DOC, the BBB remained intact and the cerebral ultrastructure was similar to the controls. At 1 m M and above, disruption of the BBB became evident. At 2 m M, the cerebral cortex became severely vacuolated, with damaged endothelium and collapsed capillaries. With TCDC, BBB disruption occurred at 0.2 m M without any apparent ultrastructural damage to the micro vasculature. Following 2 m M TCDC, similar, but less widespread, structural changes to the 2 m M DOC-perfused animals was apparent. Opening of the BBB occurred at a concentration lower than that required to cause lysis of either red blood cells or cultured cerebral endothelial cells. It is proposed that the effect of bile salts at concentrations of 1.5 m M and above is largely due to their lytic action as strong detergents on endothelial cell membranes, but that at lower concentrations a more subtle modification of the BBB occurs.

Classification of the Modes of Dissociation in Immiscible Cu-Alloy Thin Films

1999 ◽  
Vol 564 ◽  
Author(s):  
K. Barmak ◽  
G. A. Lucadamo ◽  
C. Cabral ◽  
C. Lavoie ◽  
J. M. E. Harper
Keyword(s):  
Thin Films ◽  
Driving Forces ◽  
Texture Evolution ◽  
Substantial Reduction ◽  
Alloying Elements ◽  
X Ray Diffraction ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Evolution Of Microstructure

AbstractWe have found the dissociation behavior of immiscible Cu-alloy thin films to fall into three broad categories that correlate most closely with the form of the Cu-rich end of the binary alloy phase diagrams. The motivation for these studies was to use the energy released by the dissociation of an immiscible alloy, in addition to other driving forces commonly found in thin films and lines, to promote grain growth and texture evolution. In this work, the dissociation behavior of eight dilute (3.3 ± 0.5 at% solute) binary Cu-systems was investigated, with five alloying elements selected from group VB and VIB, two from group VillA, and one from group 1B. These alloying elements are respectively V, Nb, Ta, Cr, Mo, Fe, Ru and Ag. Several experimental techniques, including in situ resistance and stress measurements as well as in situ synchrotron x-ray diffraction, were used to follow the progress of solute precipitation in approximately 500 nm thick films. In addition, transmission electron microscopy was used to investigate the evolution of microstructure of Cu(Ta) and Cu(Ag). For all eight alloys, dissociation occurred upon heating, with the rejection of solute and evolution of microstructure and texture often occurring in multiple steps that range over several hundred degrees between approximately 100 and 900°C. However, in most cases, substantial reduction in resistivity of the films took place at temperatures of interest to metallization schemes, namely below 400°C.

In situ XRD studies of the structural changes of ZrO2-coated LiCoO2 during cycling and their effects on capacity retention in lithium batteries

2006 ◽  
Vol 163 (1) ◽  
pp. 185-190 ◽  
Author(s):  
Kyung Yoon Chung ◽  
Won-Sub Yoon ◽  
Hung Sui Lee ◽  
James McBreen ◽  
Xiao-Qing Yang ◽  
...  
Keyword(s):  
Lithium Batteries ◽  
Structural Changes ◽  
Capacity Retention ◽  
In Situ Xrd ◽  
Xrd Studies

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

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