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  • 1
    Publication Date: 2019-08-19
    Description: The second generation Antarctic magnetic anomaly compilation for the region south of 60°S includes some 3.5 million line-km of aeromagnetic and marine magnetic data that more than doubles the initial map’s near-surface database. For the new compilation, the magnetic data sets were corrected for the International Geomagnetic Reference Field, diurnal effects, and high-frequency errors and leveled, gridded, and stitched together. The new magnetic data further constrain the crustal architecture and geological evolution of the Antarctic Peninsula and the West Antarctic Rift System in West Antarctica, as well as Dronning Maud Land, the Gamburtsev Subglacial Mountains, the Prince Charles Mountains, Princess Elizabeth Land, and Wilkes Land in East Antarctica and the circumjacent oceanic margins. Overall, the magnetic anomaly compilation helps unify disparate regional geologic and geophysical studies by providing new constraints on major tectonic and magmatic processes that affected the Antarctic from Precambrian to Cenozoic times.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 2
    Publication Date: 2021-05-19
    Description: Researchers from Russia and foreign countries, studying medical and environmental contamination of drinking water, point to the relationship of public health with chemical composition of groundwater and anthropogenic inclusions. The aim of the work is to detect the change in chemical composition of natural waters formed within the Khibiny massif and its closest framing depending on the composition of rocks in the catchment area and on anthropogenic impact by means of physical and chemical modeling and modern precision methods of analysis. To achieve the goal the sampling has been taken at the "Predgorny" water intake (Koashva, the Kirovsk district). The complete hydrochemical analysis has shown the presence in waters of such elements as uranium, molybdenum, silver, barium, which supplemented the database of groundwater chemical composition. For the physical-chemical modeling, there have been made some samples of chemical analyzes of the most common rocks composing the southeastern part of the Khibiny massif as the main catchment area. The analysis of the obtained results has made it possible to separate the rock influence from anthropogenic, natural chemical composition of waters from filtered mined (anthropogenic). It has been shown that already in natural (pure) waters the ratios of Ca/P and Ca/Sr can lead to bone diseases. It has been determined that the chemical composition of groundwater from the "Predgorny" water intake is affected by the chemical composition of rocks and surface waters containing oxygen, nitrogen nitrates, chlorine, which affect pH (reducing it), the migration patterns of aluminum, manganese, iron and other elements. In the bones of humans and animals, approximately 70 % falls on hydroxyl apatite Ca5(PO4)3OH. OH group can be replaced by F, Cl, O. Calcium can be isomorphically replaced by a number of elements: Sr, U, Ba, etc. that lead to diseases of bones and teeth. The research results can be useful in the fields of geochemistry, hydrology, ecology, and medicine.
    Description: Исследователи России и зарубежных стран, занимающиеся медико-экологическим загрязнением питьевой воды, указывают на связь здоровья населения с химическим составом подземных вод и антропогенных включений. Целью работы является обнаружение изменения химического состава природных вод, формирующихся в пределах Хибинского массива и его ближайшего обрамления, в зависимости от состава пород области водосбора и от антропогенного влияния с помощью физико-химического моделирования (программный комплекс (ПК) "Селектор") и современных прецизионных методов анализа. Для достижения цели был произведен отбор проб на водозаборе "Предгорный" (п. Коашва, Кировский район). Полный гидрохимический анализ показал присутствие в водах таких элементов, как уран, молибден, серебро, барий, что пополнило базу данных химического состава подземных вод. Для физико-химического моделирования были сделаны выборки химических анализов наиболее распространенных пород, слагающих юго-восточную часть Хибинского массива как основную область водосбора. Анализ полученных результатов позволил отделить породное влияние от антропогенного, природный химический состав вод от профильтрованных рудничных (антропогенных). Показано, что уже в природных (чистых) водах соотношения Са/P и Са/Sr могут приводить к болезням костей у населения. Установлено, что на формирование химического состава подземных вод водозабора "Предгорный" оказывают влияние химические составы пород и поверхностных вод, содержащие кислород, нитраты азота, хлор, которые влияют на значения рН (уменьшая их), формы миграции алюминия, марганца, железа и других элементов. В костях человека и животных примерно 70 % приходится на гидроксил апатит Са5(РО4)3ОН. Группу ОН могут заменять F, Cl, O. Кальций может быть изоморфно заменен рядом элементов: Sr, U, Ba и др., что вызывает заболевания костей и зубов у населения. Результаты исследований могут быть полезны в областях геохимии, гидрологии, экологии, медицине.
    Description: Published
    Keywords: Подземные воды ; Физико-химическая модель ; Хибиниты ; Медико-экологические исследования ; Гидроксил апатит ; Groundwater ; Physical-chemical model ; Khibinites ; Medical studies ; Ecological studies
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.88-98
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  • 3
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Cyclotron resonance is measured in solitary type-II InAs-AlGaSb quantum wells grown by molecular-beam epitaxy under various growth conditions. Quantum oscillations observed in the cyclotron resonance spectra in InAs-GaSb samples are attributed to scattering by a short-range potential due to roughness of the heterointerface. A new method based on measurement of the cyclotron resonance spectra is proposed for assessing the quality of the heterointerface.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract High-quality ZnSe-based heterostructures are grown by uninterrupted molecular beam epitaxy using the concept of strain compensation and alternating-strain multilayers. To verify the advantages of this technique, optically pumped ZnSSe/ZnCdSe laser structures containing short-period superlattices or multiple quantum wells have been grown and studied. A room-temperature injection laser diode with a BeZnSe/ZnSe superlattice waveguide is described.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The optical properties of structures with submonolayer inclusions of CdSe in a Zn(S,Se) matrix are studied. The submonolayer coating consists of a group of nanosized (40 Å) islands with a height of one monolayer. The exciton oscillator strength of multiple submonolayer CdSe-ZnSSe structures is substantially increased compared to the case of a uniform quantum well of comparable thickness and composition. In submonolayer structures lasing takes place immediately next to the energy of the ground state of the heavy exciton, in contrast with ordinary quantum wells of ZnCdSe, where it is strongly shifted to longer wavelengths by the energy of a single optical phonon. This effect results from the removal of the momentum selection rules during radiative recombination of excitons in submonolayer structures.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The ZnSe and CdSe parameters required to calculate levels in ZnCdSe/ZnSe quantum wells are determined by fitting to published data. The model is shown to be adequate for the example of structures with a collection of quantum wells whose thickness and composition were determined by independent methods.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The photoconductivity of a two-dimensional electron gas in the far IR range in a quantizing magnetic field is investigated for samples in Corbino geometry, which eliminates transport by edge states. It is shown that the photoelectric effect is more than simply the bolometric response of the system, acquiring a component induced by the direct involvement of photoexcited carriers in low-energy scattering processes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Exciton dynamics in ZnCdSe/ZnSe quantum-well structures have been studied from luminescence spectra obtained at T=2 K. The energy and phase relaxation times of localized exciton states have been determined from a study of the destruction of exciton optical alignment by an external magnetic field and direct measurements of the polarized-radiation decay kinetics in the picosecond range. The exciton polarization lifetimes measured by two independent techniques are found to be in a good agreement.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1090-6487
    Keywords: 76.40.+b ; 73.40.Kp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Splitting of the cyclotron resonance (CR) line is observed in the electron CR spectra of InAs/GaSb heterostructures containing tunneling-coupled electron and hole layers. This splitting is interpreted to be a manifestation of a hybridization gap arising as a result of anticrossing of the Landau levels of electrons and holes when their wave functions overlap. The energy splitting of the CR lines is correlated with the magnitude of the overlap and agrees with theoretical estimates of the hybridization gap width.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We report the results of an experimental study of molecular-beam epitaxy of ZnSe-based laser heterostructures with a new structure of the active region, which contains a fractional-monolayer CdSe recombination region in an expanded ZnSe quantum well and a waveguide based on a variably-strained, short-period superlattice are reported. Growth of a fractional-monolayer CdSe region with a nominal thickness of 2–3 ML, i.e., less than the critical thickness, on a ZnSe surface (Δa/a∼7%) leads to the formation of self-organized, pseudomorphic, CdSe-enriched islands with lateral dimensions ∼10–30 nm and density ∼2×1010 cm−2, which serve as efficient centers of carrier localization, giving rise to effective spatial separation of defective regions and regions of radiative recombination and, as a result, a higher quantum efficiency. Laser structures for optical pumping in the (Zn, Mg) (S, Se) system with a record-low threshold power density (less than 4 kW/cm2 at 300 K) and continuous-wave laser diodes in the system (Be, Mg, Zn) Se with a 2.5 to 2.8-ML-thick, fractional-monolayer CdSe active region have been obtained. The laser structures and diodes have an improved degradation resistance.
    Type of Medium: Electronic Resource
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