—
Highly dispersed powders of two-phase multicomponent alloys have been prepared by mechanochemical synthesis from Hf
0.5
Nb
0.5
Ta
0.5
Ti
1.5
Zr
1
(composition
1
) and HfNbTaTiZrMo (composition
2
) ...refractory-metal mixtures in a Fritsch (P-7) planetary mill under an Ar atmosphere. Two solid solutions, with BCC and HCP lattices, were obtained from the five-component mixture (composition
1
). In the case of the six-component mixture (composition
2
), both solid solutions had BCC lattices. Using compaction by hot isostatic pressing at a temperature of 1200°C, we obtained dense samples. Mechanical tests in compression showed a combination of high strength and plasticity. For sample
1
, we obtained a yield stress σ
y
= 1317 MPa, compressive breaking stress σ
b
= 1340 MPa, and relative breaking spread of 7%. Even better results were obtained for sample
2
: σ
y
= 2153 MPa and σ
b
= 2165 MPa, with δ = 10%.
This paper presents the first data on the flora of silica-scaled chrysophytes (orders Synurales and Paraphysomonadales) in the delta of the Mekong River (Vietnam). A total of 15 taxa have been ...identified: nine from the genus
Mallomonas
, one from
Synura
, and five from
Paraphysomonas
. Six taxa are reported for the first time from Vietnam. At most sites, 1–2 species per station are recorded. The maximum diversity (12 taxa) is revealed at the station with salinity >1 g/L. Based on previous floristic studies of silica-scaled chrysophytes in Vietnam, the number of taxa known from the country has been increased to 66. Our studies have expanded the list of species which have tolerance to salinity of about 1 g/L.
Acylation of 5,7-di(
tert-
butyl)-2-{5,8-dimethyl-4-(3,5-dimethylphenyl)aminoquinolin-2-yl}-3-(3,5-dimethylphenyl)aminotropone leads to 3-aryl(acetyl)aminotropone. The structure of 3-
N
...-acetyl(3,5-dimethylphenyl)amino-5,7-di(
tert
-butyl)-2-{5,8-dimethyl-4-(3,5-dimethylphenyl)aminoquinolin-2-yl}tropone was established by single crystal X-ray diffraction.
In this work, the interatomic potentials for modeling diffusion in the C15 Cr2Ta Laves phase were constructed within the N-body approach. The potential for Ta–Ta interactions reproduces the lattice ...parameter, cohesive energy, elastic constants, equation of state, thermal expansion, point defect energies, and phonon dispersion of body-centered cubic Ta in qualitative agreement with density functional theory (DFT) data and almost quantitative agreement with available experimental data in the temperature range of stability of C15 Cr2Ta Laves phase. The potential for Cr–Ta interactions reproduces the elastic constants, point defect properties, equilibrium volumes, and formation enthalpies of Cr–Ta structures in qualitative agreement with DFT data. Also, it reproduces the lattice stability and high-temperature formation enthalpy of C15 Cr2Ta Laves phase in very close agreement with the available experimental data. The calculations of diffusion coefficients with constructed potentials showed that diffusion in C15 Cr2Ta lattice is governed by Cr atoms which cannot move without creation of vacancies. The constructed potentials can be used in further investigations of diffusion processes in Cr–Ta phases at temperatures up to 2000 K, while the obtained results on diffusion coefficients in C15 Cr2Ta Laves phase would be useful in the rational design of Cr–Ta based alloys.
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The structures of 5,7-di(
tert
-butyl)-2-(5,8-dimethyl-4-piperidinoquinolin-2-yl)-3-hydroxytropone, 5,7-di(
tert
-butyl)-3-chloro-2-(5,8-dimethyl-4-piperidinoquinolin-2-yl)tropone, 5,7-di(
tert
...-butyl)- 3-(3,5-dimethylphenylamino)-2-(5,8-dimethyl-4-piperidinoquinolin-2-yl)tropone, and 3-(
N
-acetyl-3,5- dimethylphenylamino)-5,7-di(
tert
-butyl)-2-(5,8-dimethyl-4-piperidinoquinolin-2-yl)tropone were determined by X-ray diffraction. These compounds were synthesized through a series of transformations, including the nucleophilic substitution of the chlorine atom by piperidine in the starting 5,7-di(
tert
-butyl)-2-(4- chloroquinolin-2-yl)-3-hydroxytropone followed by the three-step functionalization of the 3-position in 3-hydroxytropone. The nature of dynamic processes in a solution of
N
-acetyl-3-arylaminotropone associated with the rotation of the
N
-acetyl group was revealed by the PCM/PBE0/6-31G(
d,p
) method.
Multicomponent (Cr, Fe, Co, Ni, Al, Ti, and Nb) powder alloys prepared by milling five- to seven-component equiatomic mixtures of elemental powders in a Fritsch (P-7) planetary mill have been ...characterized by differential thermal analysis and X-ray diffraction. The results demonstrate that, if the starting mixture contains Al, the BCC solid solution formed as a result of the milling undergoes heating-induced CsCl-type ordering (β-phase). If not only Al but also Ti are present in the starting mixture, further heating causes the β-phase to convert to an
L
2
1
phase with the composition (Ni,Co)TiAl. The elements Cr and Fe form a tetragonal σ-phase. The presence of Nb in the starting mixture suppresses the formation of the σ- phase and favors the formation of a hexagonal Laves phase of complex composition: (Fe,Co)CrNb.
Fermi-LAT has made a significant contribution to the study of high-energy gamma-ray diffuse emission and the observation of ∼3000 discrete sources. However, one third of all gamma-ray sources (both ...galactic and extragalactic) are unidentified, the data on the diffuse gamma-ray emission should be clarified, and signatures of dark matter particles in the high-energy gamma-ray range are not observed up to now. GAMMA-400, currently developing gamma-ray telescope, will have the angular (∼0.01° at 100 GeV) and energy (∼1% at 100 GeV) resolutions in the energy range of 10-1000 GeV better than the Fermi-LAT (as well as ground gamma-ray telescopes) by a factor of 5-10 and observe some regions of the Universe (such as Galactic Center, Fermi Bubbles, Crab, Cygnus, etc.) in the highly elliptic orbit (without shading the telescope by the Earth) continuously for a long time. It will permit to identify many discrete sources, to clarify the structure of extended sources, to specify the data on the diffuse emission, and to resolve gamma rays from dark matter particles.
Using mechanochemical synthesis through milling of equiatomic multicomponent mixtures of Cr, Fe, Co, Ni, Al, Ti, Mo, and Nb metals in various combinations, we have synthesized powder alloys with ...different phase compositions: amorphous phase (AP), AP + BCC phase, AP + BCC phase + MO, and FCC + BCC phases. The FCC phase has been shown to be a Ni-based solid solution. The presence of aluminum in a starting mixture helps to stabilize the BCC phase owing to the formation of a disordered
B2
phase. Al dissolves in both the BCC and FCC solid solutions, increasing their lattice parameters. In Al-free starting mixtures, Cr is responsible for the formation of the BCC solid solution. The formation of an AP during milling of multicomponent mixtures is favored by the presence of transition metals with a large atomic radius: Ti, Mo, and Nb.
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