The optimal form of the scanning near-field optical microscopy probe

A theoretical approach to determine the optimal form of the near-field optical microscope probe is proposed. An analytical expression of the optimal probe form with subwavelength aperture has been obtained. The advantages of the probe with the optimal form are illustrated using numerical calculations. The conducted calculations show 10 times greater light throughput and the reception possibility of the more compactly localized light at the output probe aperture which could indicate better spatial resolution of the optical images in near-field optical technique using optimal probe.Comment: 12 pages, 6 figure

Pressure and temperature dependences in p-ZnAs2 at high pressures

Kinetic effects in p-ZnAs2 were measured at hydrostatic (P ≤ 9 GPa) and quasi-hydrostatic (to P ≤ 50 GPa) pressures on pressure buildup and depressurization. A conclusion on the occurrence of two phase transitions was made: I-II at P = 9-15 GPa and II-III at P = 30-35 GPa. Based on the temperature dependences of electrical resistance, it was shown that the conductivity is determined by activation mechanisms in a temperature range of 250-400 K; in this case, the activation energy changed with temperature and pressure. The pressure dependences of the activation energy and the coefficient R 0, which characterizes the mobility, concentration, and effective mass of carriers, were calculated. © 2013 Pleiades Publishing, Ltd

Pressure control of magnetic clusters in strongly inhomogeneous ferromagnetic chalcopyrites

Room-temperature ferromagnetism in Mn-doped chalcopyrites is a desire aspect when applying those materials to spin electronics. However, dominance of high Curie-temperatures due to cluster formation or inhomogeneities limited their consideration. Here we report how an external perturbation such as applied hydrostatic pressure in CdGeP2:Mn induces a two serial magnetic transitions from ferromagnet to non-magnet state at room temperature. This effect is related to the unconventional properties of created MnP magnetic clusters within the host material. Such behavior is also discussed in connection with ab initio density functional calculations, where the structural properties of MnP indicate magnetic transitions as function of pressure as observed experimentally. Our results point out new ways to obtain controlled response of embedded magnetic clusters

Magnetization of Cd3As2-30 mol % MnAs composite at high pressure

In this article, we report research data for the isothermal magnetization of a composite consisting of Dirac semimetal and MnAs ferromagnet (30 mol %) at pressures up to 5 GPa. A magnetic transformation in MnAs inclusions, the size of which presumably varies from a micro- to nanoscale, has been found to be similar to that in bulk MnAs compound, except for a hysteresis in the range of magnetostructural transformatio

Magnetization of Cd3As2–30 mol % MnAs Composite at High Pressure

Abstract: In this article, we report research data for the isothermal magnetization of a composite consisting of Cd3As2 Dirac semimetal and MnAs ferromagnet (30 mol %) at pressures up to 5 GPa. A magnetic transformation in MnAs inclusions, the size of which presumably varies from a micro- to nanoscale, has been found to be similar to that in bulk MnAs compound, except for a hysteresis in the range of magnetostructural transformation. Under hydrostatic pressure, a magnetization maximum has been revealed at pressures P ≥ 0.77 GPa, which is indicative of ferromagnetic ordering improvement. The conclusion has been drawn that that the above features are due to the superparamagnetic nature of nanometer-sized MnAs inclusions in the Cd3As2 matrix. © 2022, Pleiades Publishing, Ltd

Reconstruction of Holocene environmental changes in Southern Kurils (North-Western Pacific) based on palaeolake sediment proxies from Shikotan Island

© 2017 Elsevier B.V. We investigated a well-dated sediment section of a palaeolake situated in the coastal zone of Shikotan Island (Lesser Kurils) for organic sediment-geochemistry and biotic components (diatoms, chironomids, pollen) in order to provide a reconstruction of the palaeoenvironmental changes and palaeo-events (tsunamis, sea-level fluctuations and landslides) in Holocene. During the ca 8000 years of sedimentation the changes in organic sediment-geochemistry and in composition of the diatoms and chironomids as well as the shifts in composition of terrestrial vegetation suggest that the period until ca 5800 cal yr BP was characterized by a warm and humid climate (corresponds to middle Holocene optimum) with climate cooling thereafter. A warm period reconstructed from ca 900 to at least ca 580 cal yr BP corresponds to a transition to a Nara-Heian-Kamakura warm stage and can be correlated to a Medieval Warm Period. After 580 cal yr PB, the lake gradually dried out and climatic signals could not be obtained from the declining lacustrine biological communities, but the increasing role of spruce and disappearance of the oak from the vegetation give evidences of the climate cooling that can be correlated with the LIA. The marine regression stages at the investigated site are identified for ca 6200–5900 (at the end of the middle Holocene transgression), ca 5500–5100 (Middle Jomon regression or Kemigawa regression), and ca 1070–360 cal yr BP (at the end of Heian transgression). The lithological structure of sediments and the diatom compositions give evidences for the multiple tsunami events of different strengths in the Island. Most remarkable of them can be dated at around ca 7000, 6460, 5750, 4800, 950 cal yr BP. The new results help to understand the Holocene environmental history of the Southern Kurils as a part of the Kuril-Kamchatka and Aleutian Marginal Sea-Island Arc Systems in the North-Western Pacific region

Методика измерений объемных долей газов методом газовой хроматографии в закиси азота медицинской: особенности оценки метрологических характеристик

   An analysis by the Federal Information Fund revealed the lack of methods for measuring the volume fractions of nitrous oxide, carbon oxide and dioxide, oxygen, nitrogen, and non-condensable gases in medical nitrous oxide using portable devices. Nitrous oxide is widely used in medicine, and therefore this research was committed to the development and certification of a method for measuring volume fractions of nitrous oxide, carbon oxide and dioxide, oxygen, nitrogen, and non-condensable gases using gas chromatography in medical nitrous oxide. Certification of the measurement method in accordance with legal requirements in the field of ensuring the uniformity of measurements was carried out by organizing a quasi-interlaboratory experiment; the following approaches were used to obtain the measurement result: the method for constructing a calibration dependence, the external standard method, and the calculation method. In addition, the study presents an algorithm and results for calculating the uncertainty of measurements of volume fractions of gases, subject to the provisions of EURACHEM CITAC, as well methodologically influencing factors that were assessed using a multifactorial experiment and its processing by regression analysis.   Анализ Федерального информационного фонда показал отсутствие методик измерения объемных долей закиси азота, оксида и диоксида углерода, кислорода, азота, неконденсирующихся газов в закиси азота медицинской с применением портативных устройств. Закись азота имеет достаточно широкое применение в медицине, в связи чем настоящее исследование было нацелено на разработку и аттестацию методики измерений объемных долей закиси азота, оксида и диоксида углерода, кислорода, азота, неконденсирующихся газов методом газовой хроматографии в закиси азота медицинской. Аттестация методики измерений в соответствии с требованиями законодательства в области обеспечения единства измерений проведена путем организации квазимежлабораторного эксперимента, при этом использованы следующие подходы к получению результата измерений: метод построения градуировочной зависимости, метод внешнего стандарта, расчетный метод. Кроме того, в работе представлены алгоритм и результаты расчета неопределенности измерений объемных долей газов, выполненные с учетом положений ЕВРАХИМ / СИТАК, а также с учетом методических влияющих факторов, которые оценивались с помощью многофакторного эксперимента и его обработки методом регрессионного анализа