Resonance Raman Scattering in TlGaSe 2

The resonance Raman scattering for geometries Y(YX)Z and Y(ZX)Z at temperature 10 K and infrared reflection spectra in E∥a and E∥b polarizations at 300 K were investigated. The number of Aa (Ba) and Au (Bu) symmetry vibrational modes observed experimentally and calculated theoretically agree better in this case than when TlGa2Se4 crystals belong to D2h symmetry group. The emission of resonance Raman scattering and excitonic levels luminescence spectra overlap. The lines in resonance Raman spectra were identified as a combination of optical phonons in Brillouin zone center

STUDY OF METHANE CONCENTRATION VARIABILITY IN THE SURFACE LAYER OF THE SEA OF JAPAN IN THE CONTEXT OF SEISMIC EVENTS (BASED ON THE RESULTS OF EXPEDITION STUDIES IN 2017–2018)

A spatial distribution of methane dissolved in sea water is a critical but poorly understood factor in the context of seismic activity. Based on the results of the RV AKADEMIK OPARIN integrated geological-geophysical expedition (September 21 – October 31, 2017), this paper deals with the regularities of methane concentration variability in the surface layer of the Sea of Japan: the average growth and the average growth period were 70 % and 10 h, respectively, after each earthquake whereas a decrease in methane concentration in the sea water was 10–30 % 2–4 h before a seismic event. A decrease in methane concentration occurs irrespectively of the depth of an earthquake. The results obtained show good agreement with the published data and gaseous-geochemical monitoring materials, thus making it possible to associate seismic-related gaseous-geochemical regime not only with gas-saturated sediments but also with the water column of the Japan Basin (Sea of Japan)

Rheology of liquid crystalline phases of alkyloxybenzylidene toluidines

A unique viscometer of the CS rheometer viscometer class designed at the Kazan State University of Technology is used to measure viscosities of two p-n-alkyloxybenzylidene-p-toluidines in the entire temperature range of the liquid crystalline state and transition into an isotropic liquid. The measured shear stresses and flow rates are used to calculate shear rates and plot flow and viscosity curves. The liquid crystalline phase and isotropic liquid are demonstrated to possess Newtonian viscosity, whose viscous flow activation parameters are calculated in the temperature range under study. The results are discussed from the standpoint of intermolecular interactions and structural details of the liquid crystalline phase. © 2010 Pleiades Publishing, Ltd

A viscometric study of the liquid crystalline phase of alkyloxybenzoic acids

The viscosities of three benzoic acid derivatives (p-n-heptyloxy-, p-n-decyloxy-, and p-n-dodecyloxy-) were measured on a unique viscometer of the class of CS-rheometer-viscometers with controlled shear stress over the whole temperature range of the liquid crystalline state. Shear rates were calculated and flow and viscosity curves constructed from the experimental shear stress values taking into account the Rabinovich-Moony correction. The smectic and nematic phases were characterized by non-Newton and Newton viscosities, respectively, in all the samples studied. The activation parameters of viscous flow were calculated for Newton viscosity. The results are discussed in terms of intermolecular interactions and structural peculiarities of liquid crystalline phases. © 2009 Pleiades Publishing, Ltd

The content of trace elements in the muscle tissue of some species of aquatic organisms from the Sea of Okhotsk waters of Northeastern Sakhalin

The content of Fe, As, Cu, Mn, Cr, Ni, Pb and Cd in the muscles of some aquatic organism species from the Sea of Okhotsk waters of Northeastern Sakhalin was estimated: walleye pollack (Gadus chalcogrammus Pallas, 1814), longhead dab (Limanda proboscidea Gilbert, 1896) and Bering flounder (Hippoglossoides robustus Gill & Townsend, 1897), snow crab (Chionoecetes opilio (O.Fabricius, 1788)). The concentrations of Fe and Cu are reliably higher in the snow crab, in contrast to fish, and Pb concentration is higher in fish relative to the snow crab. There was no difference in the content of trace elements between the flounders and snow crab, and in relation to the walleye pollock, the snow crab has reliably higher concentrations of Fe, Cu, and Hg and lower ones of Pb. The content of Fe is higher in the flounders compared to the walleye pollack. The concentrations of Pb, Cd, As and Hg are safe according to the hygienic requirements for food products and may indirectly indicate a favorable environmental situation in terms of the content of regulated toxic elements in the waters of Northeastern Sakhalin

The content of trace elements in the Pacific capelin Mallotus catervarius (Pisces: Osmeridae) from the coastal waters of the southwestern part of Sakhalin Island

The content of Fe, As, Cu, Mn, Cr, Ni, Pb, Hg and Cd in the muscles and gonads of the Pacific capelin sampled in 2020 in the coastal waters of the southwestern part of Sakhalin Island was estimated. The highest content of As is noted in muscles, Mn – in fish eggs, Hg – in muscles and milt. The content of trace elements in fish muscles and gonads decreases in the range Fe–Cd or Hg. The concentrations of normalized toxic elements Pb, Cd, As and Hg in the muscles and gonads of the Pacific capelin are safe according to hygienic requirements for food products. The data obtained indirectly indicate a favorable ecological situation in terms of the content of normalized toxic elements in the waters near southwest Sakhalin

LETTER TO THE EDITOR: Sharp variations in the temperature dependence of optical reflectivity from AlN/GaN heterostructures

Sharp variations in optical reflectivity were observed when cooling and heating AlN/GaN heterostructures on sapphire substrates between room temperature and 10 K. The reflectivity was found to decrease at a definite temperature Tk in the downward temperature run, and to recover at Tr > Tk in the subsequent upward temperature run. The temperature behaviour of reflectivity exhibits memory on the cooling–heating cycles previously subjected to samples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48936/2/s302l1.pd

ИССЛЕДОВАНИЕ ИЗМЕНЧИВОСТИ КОНЦЕНТРАЦИЙ МЕТАНА В ПОВЕРХНОСТНОМ СЛОЕ ВОД ЯПОНСКОГО МОРЯ В КОНТЕКСТЕ СЕЙСМИЧЕСКИХ СОБЫТИЙ (ПО РЕЗУЛЬТАТАМ ЭКСПЕДИЦИОННЫХ ИССЛЕДОВАНИЙ 2017–2018 гг.)

A spatial distribution of methane dissolved in sea water is a critical but poorly understood factor in the context of seismic activity. Based on the results of the RV AKADEMIK OPARIN integrated geological-geophysical expedition (September 21 – October 31, 2017), this paper deals with the regularities of methane concentration variability in the surface layer of the Sea of Japan: the average growth and the average growth period were 70 % and 10 h, respectively, after each earthquake whereas a decrease in methane concentration in the sea water was 10–30 % 2–4 h before a seismic event. A decrease in methane concentration occurs irrespectively of the depth of an earthquake. The results obtained show good agreement with the published data and gaseous-geochemical monitoring materials, thus making it possible to associate seismic-related gaseous-geochemical regime not only with gas-saturated sediments but also with the water column of the Japan Basin (Sea of Japan).Пространственное распределение метана, растворенного в морской воде, во взаимосвязи с сейсмической активностью играет исключительно важную, но недостаточно исследованную роль. В работе на примере результатов комплексной геолого-геофизической экспедиции на НИС «Академик Опарин» (21 сентября – 31 октября 2017 г.) установлена закономерность изменчивости концентрации метана в поверхностном слое морской воды: после каждого землетрясения средний показатель роста составил 70 %, средний период роста 10 ч; падение уровня концентрации метана в морской воде достигало 10–30 % за 2–4 ч до сейсмического события. Снижение концентраций метана происходит независимо от глубины землетрясения. Полученные результаты согласуются с литературными данными, а также материалами газогеохимического мониторинга и позволяют обсуждать наличие сейсмозависимого газогеохимического режима не только газонасыщенных осадков, но и толщи вод Японского моря

Geochemical features of Sakhalin Island mud volcanoes

The study, based on a complex geochemical research, found that the composition of the most chemical elements in mud breccia from the Yuzhno-Sakhalinsky (YSMV) and Pugachevsky (PMV) mud volcanoes (Sakhalin Island), the unique phenomena of endogenous defluidization in the Hokkaido-Sakhalin fold system (alpine-type folding), are comparable to Clark (C) contents of these elements (0.8-1.2 ×C). For Na, Li, Zn andSn, the ratio between the elemental contentsand their Clarke values (Csample/Clark value) vary from 1.4 to 5.2 xC. But the increased contents of Na and Li are due to the ascending endogenous fluid revealed. Study of the mud breccia chemical composition changes in different explosive activity of YSMV under the seismic activity variationsallowed to establish that, when the mud-volcanic gryphonsare activated against the background of increase in the temperature of the water-mud mixture and the emission of spontaneous gases, the contents of a number of elements (iron, calcium, manganese, rare earth elements, etc.) are decreased. This is explained by the formation of soluble hydrocarbonate complexes. Daginskiegasgeothermal system (DGHS) trace elements depletedooze samples were compared with YSMV and PMVsamples and exposedthat thehigh ratios of Csample /Clarke values for the majority of elements do not exceed 0.6 × C.Ooze samples from DGHS having higher elemental contents than Clark contents were observed only for Cd content (2.2-3.4 ×C) and Pb (0.7-1.5 ×C). Analysis of diatom flora on the DGHS site indicates the existence of an active fluid dynamic system that drains oil and gas bearing complexes. The factors determining the "weighting" of the methane carbon isotope composition in the southern part of Sakhalin Island are the increased seismic activity of deep-seated faults, as well as the presence of intrusions (diabase) and metamorphically altered rocks.References Aliyev A.A., Guliyev I.S., Rakhmanov R.R., 2009. Catalog of eruptions of Azerbaijan mud volcanoes (1810-2007). Baku Nafta-Press, 109p. Astakhov A.S., et al., 2002. Defluitization process dynamic of the Central Sakhalin fault at seismic activization (by monitoring results of the Yuzhno-Sakhalinsky mud volcano in July - August 2001) DAN 2002, 386(2), 223-228. Decisions of operational interdepartmental regional stratigraphical meetings on the Paleogene and Neogene of east regions of Russia-Kamchatka, Koryak Upland, Sakhalin and Kuril Islands, 1998. 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