168 research outputs found
Distinctive Features of the Phase Composition of Porous TiNi-based Alloys Obtained by Reaction and Diffusion Sintering
The present article is concerned with questions of reaction and diffusion sintering of porous shape-memory TiNi-based alloys. The comparative analysis of structural features of the porous alloys obtained by diffusion sintering of TiNi powder and reaction sintering of Ti and Ni powders was conducted. It is observed that the main feature of structure of the porous alloys is related to fraction of the TiNi phase which occupies about 90 vol.% at diffusion sintering, and 20÷50 % of the total volume of multiphase alloy for reaction sintering. The mechanisms of the structure formation on the solid phase and liquid phase sintering stages of these methods were considered. The role of Ti2Ni phase during sintering was disclosed. The Ti2Ni phase not only provides the necessary quality of sintering, activates recrystallization processes for diffusion sintering, modifies the phase composition of the sintered specimen for reaction sintering, but also participates in the formation of the TiNi phase, increasing its fraction
Analysis of the selective value of promising Melissa officinalis L. subsp. altissima (Smith.) Arcang variety
The aim of this research was to study a promising MD 1–17 Melissa officinalis L.
subsp. altissima (Smith.) Arcang. variety sample obtained in the collection of the gene pool of
the Research Institute of Agriculture of Crimea (RIAC) in comparison with Krymchanka
(selected in the RIAC) and Lada (selected in the All-Russian research Institute of medicinal and
aromatic plants(VILAR) varieties of lemon balm M. officinalis L. subsp. officinalis. In 2017–
2019, in the Department of Essential Oil and Medicinal Plants of the RIAC,a competitive variety
trial of lemon balm varieties was conducted in accordance with the methodological
recommendations for the selection of essential-oil plants. A territory where this study was
conducted belongs to one of the five agroclimatic regions – the upper piedmont, warm, not
enough humid; to the northern subarea with moderately mild winters. Weather conditions during
the years of competitive variety trial varied significantlya fact that allowed assessing the
adaptability of studied variety samples and forecasting the nature of productivity potential
realization in different growing conditions. As a result, it was found that MD 1–17 variety sample
significantly exceeds other varieties in terms of yield of fresh raw materials, on average, by 62.2
and 77.4%, and in yield of air-dried raw materials, on average, by 32.2 and 52.2%, respectively.
In terms of obtaining essential oil from air-dried raw materials, this variety sample exceeds the
best in this parameter Crimean variety Krymchanka by 56.3%. Basic components of its essential
oil are caryophyllene (25.3–35.9%) and germacrene D (17.7–31.2%) with almost complete
absence or insignificant amount of citral (0.1–7.3%); the proportion of latter in essential oils of
Krymchanka and Lada varieties can reach 36.6% or more. Novelty of this study includes the
creation of the first variety of a new promising essential oil plant –M. altissima. Raw materials
of this variety and products of its processing may be of interest for different ways of use, including
the perfumery and cosmetics industry, for food purposes as a component of tea compositions, etc
Crystallization Features of Porous TiNi Made by SHS
The surface layers and fracture surfaces of porous titanium nickelide obtained by self-propagating high temperature synthesis (SHS) in a flow reactor in an argon atmosphere are studied by SEM and energy dispersive analysis. It is alleged that primary pores 5–15 µ in size and the related granular layer are formed due to segregation and capillary force effect during peritectic crystallization of some porous alloy areas. Coarsening and deformation of pores, as well as migration and growth of granular layers, is caused by reaction gases. Carbon and oxygen impurities present in the reaction gases and the protective atmosphere penetrate into the melt film on the pore surface to form strong and corrosion-resistant nanostructured layers of intermetallic carbides, nitrides and oxides
Frequency behavior of Raman coupling coefficient in glasses
Low-frequency Raman coupling coefficient of 11 different glasses is
evaluated. It is found that the coupling coefficient demonstrates a universal
linear frequency behavior near the boson peak maximum and a superlinear
behavior at very low frequencies. The last observation suggests vanishing of
the coupling coefficient when frequency tends to zero. The results are
discussed in terms of the vibration wavefunction that combines features of
localized and extended modes.Comment: 8 pages, 9 figure
Von Neumann equations with time-dependent Hamiltonians and supersymmetric quantum mechanics
Starting with a time-independent Hamiltonian and an appropriately chosen
solution of the von Neumann equation we construct
its binary-Darboux partner and an exact scattering solution of
where is time-dependent and not
isospectral to . The method is analogous to supersymmetric quantum mechanics
but is based on a different version of a Darboux transformation. We illustrate
the technique by the example where corresponds to a 1-D harmonic
oscillator. The resulting represents a scattering of a soliton-like
pulse on a three-level system.Comment: revtex, 3 eps file
Anomalous scaling of a passive scalar in the presence of strong anisotropy
Field theoretic renormalization group and the operator product expansion are
applied to a model of a passive scalar field, advected by the Gaussian strongly
anisotropic velocity field. Inertial-range anomalous scaling behavior is
established, and explicit asymptotic expressions for the n-th order structure
functions of scalar field are obtained; they are represented by superpositions
of power laws with nonuniversal (dependent on the anisotropy parameters)
anomalous exponents. In the limit of vanishing anisotropy, the exponents are
associated with tensor composite operators built of the scalar gradients, and
exhibit a kind of hierarchy related to the degree of anisotropy: the less is
the rank, the less is the dimension and, consequently, the more important is
the contribution to the inertial-range behavior. The leading terms of the even
(odd) structure functions are given by the scalar (vector) operators. For the
finite anisotropy, the exponents cannot be associated with individual operators
(which are essentially ``mixed'' in renormalization), but the aforementioned
hierarchy survives for all the cases studied. The second-order structure
function is studied in more detail using the renormalization group and
zero-mode techniques.Comment: REVTEX file with EPS figure
Different morphological structures of breast tumors demonstrate individual drug resistance gene expression profiles
Aim: To identify gene expression profiles involved in drug resistance of different morphological structures (tubular, alveolar, solid, trabecular, and discrete) presented in breast cancer. Material and Methods: Ten patients with luminal breast cancer have been included. A laser microdissection-assisted microarrays and qRT-PCR were used to perform whole-transcriptome profiling of different morphological structures, to select differentially expressed drug response genes, and to validate their expression. Results: We found 27 differentially expressed genes (p < 0.05) encoding drug uptake (SLC1A3, SLC23A2, etc.) and efflux (ABCC1, ABCG1, etc.) transporters, drug targets (TOP2A, TYMS, and Tubb3), and proteins that are involved in drug detoxification (NAT1 and ALDH1B1), cell cycle progression (CCND1, AKT1, etc.), apoptosis (CASP3, TXN2, etc.), and DNA repair (BRCA1 and USP11). Each type of structures showed an individual gene expression profile related to resistance and sensitivity to anticancer drugs. However, most of the genes (19/27; p < 0.05) were expressed in alveolar structures. Functional enrichment analysis showed that drug resistance is significantly associated with alveolar structures. Other structures demonstrated the similar number (10–13 out of 27) of expressed genes; however, the spectrum of resistance and sensitivity to different anticancer drugs varied. Conclusion: Different morphological structures of breast cancer show individual expression of drug resistance genes. Key Words: breast cancer, tumor heterogeneity, gene expression, chemotherapy, drug resistance
Different morphological structures of breast tumors demonstrate individual drug resistance gene expression profiles
Aim: To identify gene expression profiles involved in drug resistance of different morphological structures (tubular, alveolar, solid, trabecular, and discrete) presented in breast cancer. Material and Methods: Ten patients with luminal breast cancer have been included. A laser microdissection-assisted microarrays and qRT-PCR were used to perform whole-transcriptome profiling of different morphological structures, to select differentially expressed drug response genes, and to validate their expression. Results: We found 27 differentially expressed genes (p < 0.05) encoding drug uptake (SLC1A3, SLC23A2, etc.) and efflux (ABCC1, ABCG1, etc.) transporters, drug targets (TOP2A, TYMS, and Tubb3), and proteins that are involved in drug detoxification (NAT1 and ALDH1B1), cell cycle progression (CCND1, AKT1, etc.), apoptosis (CASP3, TXN2, etc.), and DNA repair (BRCA1 and USP11). Each type of structures showed an individual gene expression profile related to resistance and sensitivity to anticancer drugs. However, most of the genes (19/27; p < 0.05) were expressed in alveolar structures. Functional enrichment analysis showed that drug resistance is significantly associated with alveolar structures. Other structures demonstrated the similar number (10–13 out of 27) of expressed genes; however, the spectrum of resistance and sensitivity to different anticancer drugs varied. Conclusion: Different morphological structures of breast cancer show individual expression of drug resistance genes. Key Words: breast cancer, tumor heterogeneity, gene expression, chemotherapy, drug resistance
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