62 research outputs found
Synthesis and properties of spherical catalysts TiO2-SiO2/МхOy (M = Co and Cr)
Get PDFLayered spherical materials were obtained, the inner layer of which is represented by oxides of cobalt or chromium, and external oxides of titanium and silicon. D-metals were fixed on the surface of the polymer substrate through sorption from aqueous solutions of the corresponding salts. The outer layer of the oxide titanium-silicon matrix was obtained by the sol-gel method. Aggregative stability of sols was controlled by viscosimetry. The influence of the components on the stability of sol solutions has been established. The time interval for the stability of sols is in the range of 400-1000 h. The laminated structure, material characteristics are studied using 3D-microtomography. The catalytic activity of the obtained TiO2-SiO2/Cr2O3 and TiO2-SiO2/Co3O4 samples was compared to the n-heptane oxidation reaction. The maximum heptane conversion for the TiO2-SiO2/Co3O4 sample is 80 % at a temperature of 600 °C, for the TiO2-SiO2/Cr2O3 sample, the conversion of n-heptane reaches 100 % at 400 °C
Size effects in chlorine doped PbSe thin films
Get PDFThe possibility of obtaining strongly degenerate (≈ 3·10²⁰ сm⁻³) PbSe thin films (d = 5 – 220 nm) with n-type conductivity by thermal evaporation in vacuum of PbSe crystals doped with PbCl₂, with subsequent condensation onto (001) KCl substrates was established. It was shown that the films had high homogeneity degree, no grain structure was observed. The thickness dependences of thermoelectric properties (the Seebeck coefficient S, the Hall coefficient RH and the electric conductivity σ) of thin films were obtained. In the thickness range d ≈ 5 ÷ 30 nm, oscillation properties were observed with growth of d that are attributable to electron gas quantization. The calculation of S(d) dependence on the assumption of size quantization with regard to contribution of several subbands and the thickness dependence of the Fermi energy was shown to be in agreement with the experimental data. In the region of d > 30 nm there was growth of S and σ with thickness, which is attributable to manifestation of classical size effect and interpreted in the framework of Fuchs-Sondheimer and Mayer theories
On the Benthic Invertebrate Megafauna at the Mid-Atlantic Ridge, in the Vicinity of the Charlie-Gibbs Fracture Zone
No full textLittle is known about the fauna that inhabits non-chemosynthetic environments associated with mid-ocean ridges. This thesis investigates a ridge and fracture zone system to assess its influence as a barrier to faunal dispersal, and as a unique bathyal habitat. It also describes the ecology of megabenthic communities inhabiting a ridge. Sites were chosen on the Mid-Atlantic Ridge in the vicinity of the Charlie-Gibbs Fracture Zone, at a target depth of 2,500 m. Four superstations were chosen north and south of the Fracture Zone, on either side of the ridge. Different productivity levels and hydrographic features were characteristic for the northern and southern sites. In order to characterise the benthic megafauna 50 ha were trawled and 32,000 m2 of seafloor were sampled with HD video footage, targeting both flat and 10 ? sloped habitats. Holothurians were the most abundant megafauna. In order to assess their evolutionary relationship 43 holothurian specimens were genetically studied by modelling five of their genes (16S, 18S, 28S, COI, H3) in a phylogenetic analysis. All four sites exhibited noticeably different faunal characteristics. The biomass was highest at the SE, and lowest at the NW site. Body sizes differed between sites for most taxa, that were sufficient in numbers to be compared between sites, most likely as a result of different adaptations to food supply. Differences in species richness were observed between the sampling methods, with the highest richness at the SE site in trawl samples, and highest at the NW and SW sites in the video survey. Species densities were highest at the northern sites with both methods. Differences in diversity were also observed, with trawl samples providing a higher taxonomic resolution than the video survey and showing highest diversity at the SE site and lowest at the NE site. Community composition was significantly different between sites. Variations in the composition of megabenthic assemblages were observed between flat and 10 ? sloped habitats, although the effect of slope appears to be site dependent. The genetic analyses revealed a close relationship between individuals from different families. The extent to which the Ridge acts as a faunal barrier was unclear as the southern sites lacked an obvious difference in community composition. Faunal differences to the north and south of the Fracture Zone, however, suggest that this feature is a barrier to dispersal. The contrasting megafaunal assemblages of the sites probably reflect a combination of environmental drivers including sediment type, phytodetrital quality, hydrography, and habitat complexity
“The Breathlessness of History” in the Russian Poetry of the 1910s and Early 1920s: Toward the Question of Meaning in Jakobson’s Meta-Language Metaphor
Get PDFThe article observes the literary, biographical and scientific context of the pneumatological metaphor that Roman Jakobson applied to rationalize the tragic fate of Russian poets after the October Revolution. The author traces Romantic and mythological sources in the motif of‘a poet’s suffocation’ and discovers how a symbolic image transforms into a social fact. The article also outlines the reasons why Jakobson united five ‘mutually antagonistic’ poets into a synchronic poetic circle, at the center of which was the art of Vladimir Majakovskij. Besides the obvious motif of predicted death under the conditions of the establishment of the Soviet revolutionary byt (lifestyle), the poets are united by the culture of their language. Majakovskij’s language correlates with the paradigm of how A. Blok, N. Gumilëv, S. Esenin and V. Chlebnikov arranged their lives. In their own way, each of these poets fills the hypothetical ‘air of the epoch’ with particular olfactory markers and creates their variant of the artistic pneumatology. Every persona in the article on Majakovskij’s death is characterized by sways between the comic and tragic modes of the poetic device. According to Jakobson, the union of the generation of poets was preconditioned by the sense and sound of the poetic speech. His article about Majakovskij helps to trace one of the most stable plots in Jakobson’s output. Throughout his life, starting from the early works about the modern poetry (1921) until the last works on language that establish a direct connection between the lifespan of a poetic device and the structure of the national language, Jakobson addresses questions concerning the meaning of ‘the place of development’ in poetics.The article observes the literary, biographical and scientific context of the pneumatological metaphor that Roman Jakobson applied to rationalize the tragic fate of Russian poets after the October Revolution. The author traces Romantic and mythological sources in the motif of‘a poet’s suffocation’ and discovers how a symbolic image transforms into a social fact. The article also outlines the reasons why Jakobson united five ‘mutually antagonistic’ poets into a synchronic poetic circle, at the center of which was the art of Vladimir Majakovskij. Besides the obvious motif of predicted death under the conditions of the establishment of the Soviet revolutionary byt (lifestyle), the poets are united by the culture of their language. Majakovskij’s language correlates with the paradigm of how A. Blok, N. Gumilëv, S. Esenin and V. Chlebnikov arranged their lives. In their own way, each of these poets fills the hypothetical ‘air of the epoch’ with particular olfactory markers and creates their variant of the artistic pneumatology. Every persona in the article on Majakovskij’s death is characterized by sways between the comic and tragic modes of the poetic device. According to Jakobson, the union of the generation of poets was preconditioned by the sense and sound of the poetic speech. His article about Majakovskij helps to trace one of the most stable plots in Jakobson’s output. Throughout his life, starting from the early works about the modern poetry (1921) until the last works on language that establish a direct connection between the lifespan of a poetic device and the structure of the national language, Jakobson addresses questions concerning the meaning of ‘the place of development’ in poetics
Dependences of thermoelectric properties on the thickness of thin films of indium doped lead telluride
Get PDFDependences of thermoelectric properties (the Seebeck coefficient S, the electric conductivity σ, the Hall coefficient RH, the carrier mobilityμ and the thermoelectric power P = S²·σ) on the thickness d (d = 10 – 255 nm) of thin films prepared by vacuum evaporation of indiumdoped PbTe crystals and subsequent condensation on (111) BaF₂ substrates were obtained. With decreasing thickness of films to d ≈ 40 nm, there is n- to p-type inversion of conduction which is related to a change in thermodynamic equilibrium conditions and partial reevaporation of lead and/or indium atoms. Extremes were found on the thickness dependences of properties at d₁ ≈ 20 nm which is indicative of hole gas quantization. In the range of thicknesses with n-type conduction there is a smooth change in thermoelectric properties with thickness which testifies to manifestation of classical size effect and is sufficiently well described in the framework of the Fuchs-Sondheimer theory
Semiconductors V. 36, I. 09
No full textSemiconductors -- September 2002
Volume 36, Issue 9, pp. 953-1071
ATOMIC STRUCTURE AND NONELECTRONIC PROPERTIES OF SEMICONDUCTORS
Doping of GaAs Layers with Si under Conditions of Low-Temperature Molecular Beam Epitaxy
M. D. Vilisova, A. E. Kunitsyn, L. G. Lavrent'eva, V. V. Preobrazhenskii, M. A. Putyato, B. R. Semyagin, S. E. Toropov, and V. V. Chaldyshev
pp. 953-957 Full Text: PDF (67 kB)
Mechanism of Copper Diffusion over the Si(110) Surface
A. E. Dolbak, R. A. Zhachuk, and B. Z. Olshanetsky
pp. 958-961 Full Text: PDF (60 kB)
ELECTRONIC AND OPTICAL PROPERTIES OF SEMICONDUCTORS
Internal Friction and Effective Shear Modulus of Single-Crystal Silicon in Early Stages of Oxygen Precipitation
V. V. Motskin, A. V. Oleinich-Lysyuck, N. D. Raranskii, and I. M. Fodchuk
pp. 962-965 Full Text: PDF (93 kB)
The Temperature and Concentration Dependences of the Charge Carrier Mobility in PbTe–MnTe Solid Solutions
E. I. Rogacheva and I. M. Krivul'kin
pp. 966-970 Full Text: PDF (85 kB)
Electron–Plasmon Interaction in Acceptor-Doped Bismuth Crystals
N. P. Stepanov and V. M. Grabov
pp. 971-974 Full Text: PDF (63 kB)
Study of Zinc Impurity Atoms in GaP, GaAs, and GaSb 67Ga(67Zn) and 67Cu(67Zn) by Emission Mössbauer Spectroscopy
N. P. Seregin, S. A. Nemov, and S. M. Irkaev
pp. 975-976 Full Text: PDF (67 kB)
SEMICONDUCTOR STRUCTURES, INTERFACES, AND SURFACES
Cathodoluminescence of ZnO/GaN/alpha-Al2O3 Heteroepitaxial Structures Grown by Chemical Vapor Deposition
M. V. Chukichev, B. M. Ataev, V. V. Mamedov, Ya. I. Alivov, and I. I. Khodos
pp. 977-980 Full Text: PDF (73 kB)
Experimental Observation of Splitting of the Light and Heavy Hole Bands in Elastically Strained GaAsN
A. Yu. Egorov, E. S. Semenova, V. M. Ustinov, Y. G. Hong, and C. Tu
pp. 981-984 Full Text: PDF (54 kB)
Variations in the Properties of an Implantation-Synthesized SixNy–Si Heterosystem as a Result of Thermal and Ion-Beam Treatments
V. V. Karzanov, K. A. Markov, V. V. Sdobnyakov, and E. S. Demidov
pp. 985-989 Full Text: PDF (154 kB)
Optical Storage on the Basis of an n-InSb–SiO2–p-Si Heterostructure
Yu. A. Nikol'skii
pp. 990-992 Full Text: PDF (47 kB)
Field-Dependent Photosensitivity of In–SiO2–Cd0.28Hg0.72Te Metal–Insulator–Semiconductor Structures with an Opaque Field Electrode
V. V. Vasil'ev, A. F. Kravchenko, and Yu. P. Mashukov
pp. 993-996 Full Text: PDF (54 kB)
Effect of Carrier Localization on the Optical Properties of MBE-Grown GaAsN/GaAs Heterostructures
B. V. Volovik, N. V. Kryzhanovskaya, D. S. Sizov, A. R. Kovsh, A. F. Tsatsul'nikov, J. Y. Chi, J. S. Wang, L. Wei, and V. M. Ustinov
pp. 997-1000 Full Text: PDF (69 kB)
Charge Carrier Transport through the Contact of Metal with a Superconducting Semiconductor
G. V. Kuznetsov
pp. 1001-1007 Full Text: PDF (90 kB)
Adsorption and Transformation of C60 Molecules at the (100) Si Surface
N. R. Gall, E. V. Rut'kov, and A. Ya. Tontegode
pp. 1008-1012 Full Text: PDF (101 kB)
LOW-DIMENSIONAL SYSTEMS
Stark Effect in Vertically Coupled Quantum Dots in InAs–GaAs Heterostructures
M. M. Sobolev, V. M. Ustinov, A. E. Zhukov, Yu. G. Musikhin, and N. N. Ledentsov
pp. 1013-1019 Full Text: PDF (130 kB)
The Influence of Heat Treatment Conditions on the Evaporation of Defect Regions in Structures with InGaAs Quantum Dots in the GaAs Matrix
D. S. Sizov, M. V. Maksimov, A. F. Tsatsul'nikov, N. A. Cherkashin, N. V. Kryzhanovskaya, A. B. Zhukov, N. A. Maleev, S. S. Mikhrin, A. P. Vasil'ev, R. Selin, V. M. Ustinov, N. N. Ledentsov, D. Bimberg, and Zh. I. Alferov
pp. 1020-1026 Full Text: PDF (96 kB)
AMORPHOUS, VITREOUS, AND POROUS SEMICONDUCTORS
Photoluminescent and Electronic Properties of Nanocrystalline Silicon Doped with Gold
É. B. Kaganovich, I. M. Kizyak, S. I. Kirillova, É. G. Manoilov, V. E. Primachenko, S. V. Svechnikov, and E. F. Venger
pp. 1027-1032 Full Text: PDF (81 kB)
Strains and Crystal Lattice Defects Arising in Macroporous Silicon under Oxidation
E. V. Astrova, V. V. Ratnikov, A. D. Remenyuk, and I. L. Shul'pina
pp. 1033-1042 Full Text: PDF (277 kB)
Hysteresis of the Photonic Band Gap in VO2 Photonic Crystal in the Semiconductor–Metal Phase Transition
V. G. Golubev, D. A. Kurdyukov, A. B. Pevtsov, A. V. Sel'kin, E. B. Shadrin, A. V. Il'inskii, and R. Boeyink
pp. 1043-1047 Full Text: PDF (96 kB)
PHYSICS OF SEMICONDUCTOR DEVICES
Photoelectric Phenomena in ZnO(ITO)/a-Si:H(n)/c-Si(p)/Al Solar Cells
Yu. A. Nikolaev, V. Yu. Rud', Yu. V. Rud', E. I. Terukov, W. Fuhs, and A. Froitzheim
pp. 1048-1052 Full Text: PDF (85 kB)
Analysis of High-Frequency Response and Nonlinear Coherent Generation of Resonance–Tunneling Diodes within a Broad Frequency Range with Account of Electron–Electron Interaction
V. F. Elesin, I. Yu. Kateev, and A. I. Podlivaev
pp. 1053-1057 Full Text: PDF (61 kB)
Study of the Potential Distribution in a Forward-Biased Silicon Diode Using Electrostatic Force Microscopy
A. V. Ankudinov, A. N. Titkov, R. Laiho, and V. A. Kozlov
pp. 1058-1064 Full Text: PDF (191 kB)
MOCVD-Grown InGaAs/GaAs/AlGaAs Laser Structures with a Broad-Area Contact
P. V. Bulaev, V. A. Kapitonov, A. V. Lutetskii, A. A. Marmalyuk, D. B. Nikitin, D. N. Nikolaev, A. A. Padalitsa, N. A. Pikhtin, A. D. Bondarev, I. D. Zalevskii, and I. S. Tarasov
pp. 1065-1069 Full Text: PDF (97 kB)
PERSONALIA
Éduard Mushegovich Kazaryan (on his 60th birthday)
pp. 1070-1071 Full Text: PDF (104 kB)Archived web conten
Quantum oscillations in thickness dependences of transport properties of topological insulator Bi2Se3 thin films
No full textЗалежність електропровідності від товщини тонких плівок Bi₂Se₃
No full textEffect of film thickness d on electrical conductivity σ of n-Bi₂Se₃ thin films (d = 25-420 nm) prepared by thermal evaporation in vacuum onto glass substrates was investigated. It was established that the electrical conductivity increases with increasing of the thin films thickness. The observed effect is explained as a manifestation of the classical size effect connected with diffuse scattering of electrons at the thin film interfaces. The experimental σ(d) dependence is satisfactorily described using the Fuchs-Sondheimer theory for the film thickness d > 60 nm. The specularity parameter and value of electrons mean free path are determined based of the experimental data
Размерные эффекты и термоэлектрические свойства тонких пленок Bi0.98Sb0.02
No full textThe room-temperature dependences of thermoelectric properties (the Seebeck coefficient S, the electrical conductivity σ, the Hall coefficient RH, and the thermoelectric power factor P = S2·σ) on the thickness (d = 5 - 250 nm) of the Bi0.98Sb0.02 solid solution thin films grown on mica substrates by thermal evaporation in vacuum from a single source were obtained. It is shown that the monotonic component of the σ(d) dependence is well described within the framework of the Fuchs-Sondheimer theory for the classical size effect. The presence of an oscillating component in the d-dependences of σ, S, RH and S2·σ is attributed to the manifestation of the quantum size effect, and the experimentally determined period of quantum oscillations Δd = 45 ± 5 nm is in good agreement with the Δd value calculated theoretically within the framework of the model of an infinitely deep potential well. Bibl. 77, Fig. 1.При кімнатній температурі отримано залежності термоелектричних властивостей (коефіцієнта Зеєбека S, електропровідності σ, коефіцієнта Холла RH і термоелектричної потужності P =S2·σ) від товщини (d = 5 - 250 нм) тонких плівок твердих розчинів Bi98Sb2, вирощених на підкладках зі слюди методом термічного випаровування у вакуумі із одного джерела. Показано, що монотонна складова залежності σ(d) добре описується в рамках теорії Фукса-Зондгеймера для класичного розмірного ефекту. Виявлена осцилююча складова d-залежностей σ, S, RH та S2·σ пов'язується з проявом квантового розмірного ефекту, і визначений експериментально період квантових осциляцій Δd = 45 ± 5 нм добре узгоджується зі значенням Δd, теоретично розрахованим в рамках моделі нескінченно глибокої потенційної ями. Бібл. 77, рис. 1При комнатной температуре получены зависимости термоэлектрических свойств (коэффициента Зеебека S, электропроводности σ, коэффициента Холла RH и термоэлектрической мощности P=S2σ) от толщины (d = 5 - 250 nm) тонких пленок твердых растворов Bi98Sb2, выращенных на подложках из слюды методом термического испарения в вакууме из одного источника. Показано, что монотонная составляющая зависимости σ(d) хорошо описывается в рамках теории Фукса-Зондгеймера для классического размерного эффекта. Обнаружена осциллирующая составляющая d-зависимостей σ, S, RH и S2σ связывается с проявлением квантового размерного эффекта, и определенный экспериментально период квантовых осцилляций Δd = 45 ± 5 нм хорошо согласуется со значением Δd, теоретически рассчитанным в рамках модели бесконечно глубокой потенциальной ямы. Библ. 77, рис. 1
Synthesis of Silicon-Containing Chitosan Hydrogels in a Glycolic Acid Medium
No full textThe present paper considers a “one-pot” green sol-gel synthesis of hybrid inorganic/organic hydrogels based on chitosan glycolate by using organically modified silica Si(OGly)4·2GlyOH as a precursor to form a network of ≡Si–O–Si≡ bonds at 4, 20, and 37°C. The gelation time of the multicomponent chitosan-containing system was estimated as a function of the composition (the polymer template and precursor concentrations, introduction of a low-molecular-weight accelerator NaCl) and gelation conditions (the pH and temperature of the sol-gel process). It has been shown that an increased polymeric salt concentration, the introduction of an accelerator, and increased pH and temperature accelerate the gel-forming process
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