Microstructures in Two Alkali Feldspar Megacrysts from the Papuk Mt., Croatia

Two types of megacrysts, one from Pakra Creek and the other from the Slobostina Creek locality proved to be low microcline in association with low albite and quartz. A sample from Pakra Creek is a vein filling megacryst characterised by the absence of twinning. The deduced crystallization temperature is below 460°C. The sample from Sloboština Creek is a pocket forming megacryst which shows tweed-like texture, with deduced crystallization temperature near to but above 460°C. Both samples are characterized by a continuously modulated lattice on the submicroscopic scale

Microstructures in Two Alkali Feldspar Megacrysts from the Papuk Mt., Croatia

Two types of megacrysts, one from Pakra Creek and the other from the Slobostina Creek locality proved to be low microcline in association with low albite and quartz. A sample from Pakra Creek is a vein filling megacryst characterised by the absence of twinning. The deduced crystallization temperature is below 460°C. The sample from Sloboština Creek is a pocket forming megacryst which shows tweed-like texture, with deduced crystallization temperature near to but above 460°C. Both samples are characterized by a continuously modulated lattice on the submicroscopic scale

Structural and magnetic study of the iron cores in iron(III)-polymaltose pharmaceutical ferritin analogue Ferrifol®

Iron(III)-polymaltose pharmaceutical ferritin analogue Ferrifol® was investigated by high resolution transmission electron microscopy (HRTEM), X-ray diffraction, thermogravimetry, electron magnetic resonance (EMR) spectroscopy, dc magnetization measurements and 57Fe Mössbauer spectroscopy to get novel information about the structural arrangement of the iron core. The Ferrifol® Mössbauer spectra measured in the range from 295 to 90 K demonstrated non-Lorentzian two-peak pattern. These spectra were better fitted using a superposition of 5 quadrupole doublets with the same line width. The obtained Mössbauer parameters were different and an unusual line broadening with temperature decrease was observed. Measurements of the Ferrifol® Mössbauer spectra from 60 to 20 K demonstrated a slow decrease of magnetic relaxation in the iron core. Zero-field-cooled and field-cooled magnetization measurements revealed a blocking temperature at ~33 K and paramagnetic state of the Ferrifol® iron core at higher temperatures. Isothermal magnetization measurements at 5 K show that the saturation magnetic moment is ~0.31 emu/g. X-band EMR spectroscopy measurements revealed the presence of different magnetic species in the sample. Transmission electron microscopy demonstrated that the size of the iron cores in Ferrifol® is in the range 2–6 nm. The lattice periodicity in these iron cores, measured on the HRTEM images, appeared to be vary in the range 2.2–2.7 Å. This can be best understood as sets of close packed O(OH) layers in ferrihydrite cores without long range correlation

Structural and Magnetic Study of the Iron Cores in Iron(III)-Polymaltose Pharmaceutical Ferritin Analogue Ferrifol®

Iron(III)-polymaltose pharmaceutical ferritin analogue Ferrifol® was investigated by high resolution transmission electron microscopy (HRTEM), X-ray diffraction, thermogravimetry, electron magnetic resonance (EMR) spectroscopy, direct current magnetization measurements and 57Fe Mössbauer spectroscopy to get novel information about the structural arrangement of the iron core. The Ferrifol® Mössbauer spectra measured in the range from 295 K to 90 K demonstrated non-Lorentzian two-peak pattern. These spectra were better fitted using a superposition of 5 quadrupole doublets with the same line width. The obtained Mössbauer parameters were different and an unusual line broadening with temperature decrease was observed. Measurements of the Ferrifol® Mössbauer spectra from 60 K to 20 K demonstrated a slow decrease of magnetic relaxation in the iron core. Zero-field-cooled and field-cooled magnetization measurements revealed a blocking temperature at ~33 K and a paramagnetic state of the Ferrifol® iron core at higher temperatures. Isothermal magnetization measurements at 5 K show that the saturation magnetic moment is ~0.31 emu/g. X-band EMR spectroscopy measurements revealed the presence of different magnetic species in the sample. Transmission electron microscopy demonstrated that the size of the iron cores in Ferrifol® is in the range 2–6 nm. The lattice periodicity in these iron cores, measured on the HRTEM images, vary in the range 2.2–2.7 Å. This can be best understood as sets of close packed O(OH) layers in ferrihydrite cores without long range correlation. © 2020 Elsevier Inc.The authors wish to thank Prof. Ferenc Simon (Institute of Physics, Budapest University of Technology and Economics, Budapest, Hungary) for making available the applied spectrometer for recording the EMR spectra and Dr. A.V. Chukin (Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russian Federation) for XRD measurements. This work was supported by the Ministry of Science and Higher Education of the Russian Federation, project No FEUZ-2020-0060, and Act 211 of the Government of the Russian Federation, contract No 02.A03.21.0006. V.K.K. was supported by the János Bolyai Postdoctoral Fellowship of the Hungarian Academy of Sciences and the ÚNKP-19-4 New National Excellence Program of the Ministry for Innovation and Technology. HRTEM facility at the Centre for Energy Research was granted by the European Structural and Investment Funds, grant no. VEKOP-2.3.3-15-2016-00002. This work was in part supported by the Hungarian National Research, Development and Innovation Office – NKFIH (K115784, K115913 and K134770). This work was carried out within the Agreement of Cooperation between the Ural Federal University (Ekaterinburg) and the Eötvös Loránd University (Budapest)

Mössbauer characterization of microbially mediated iron and manganese ores of variable geological ages

A combination of various techniques was applied to investigate the mineralogy of the Neoproterozoic Urucum iron and manganese deposit (Brazil) and Carboniferous and Permian manganese carbonate deposits (China). The examined deposits exhibited signs of microbial mediation from Fe and Mn bacteria and cyanobacteria. The studied samples showed diversity in their composition and particle size. Probes from Urucum deposit revealed that the rocks consist mainly of hematite, showing Mn substitution which reflects the oxidation of Mn on the active surface of Fe-rich biomat. Nanominerals occurring in significant concentration also supported the microbial contribution to the formation of these ores. Representative samples of Neoproterozoic and Permian deposits showed considerable amount of mixed carbonates with variable composition. 57Fe Mössbauer spectroscopy analysis supported by X-ray diffraction and transmission electron microscopy data provided a detailed characterization of Fe-rich mineral phases of the samples, including metal ratio outlooks, particle size dimension and presence and type of impurities. Integrity and high resolution of the methods allowed to determine new features of the samples reflecting important signatures of microbial activity revealing the biogeochemistry of the biomat formation

Capacitive Spring Softening in Single-Walled Carbon Nanotube Nanoelectromechanical Resonators

We report the capacitive spring softening effect observed in single-walled carbon nanotube (SWNT) nanoelectromechanical (NEM) resonators. The nanotube resonators adopt dual-gate configuration with both bottom-gate and side-gate capable of tuning the resonance frequency through capacitive coupling. Interestingly, downward resonance frequency shifting is observed with increasing side-gate voltage, which can be attributed to the capacitive softening of spring constant. Furthermore, in-plane vibrational modes exhibit much stronger spring softening effect than out-of-plan modes. Our dual-gate design should enable the differentiation between these two types of vibrational modes, and open up new possibility for nonlinear operation of nanotube resonators.Comment: 12 pages/ 3 figure

Стандартные образцы антибактерильных веществ утвержденного типа: принцип разработки

The authors of the publication have described the basic principles of the procedure of defining metrological characteristics of certified reference materials (hereinafter referred to as CRMs) of antibacterial substances that are being developed. CRMs of antibacterial substances are intended for certification of measurement procedures and accuracy control of measurement results. CRMs can be used for graduation, calibration of measuring instruments if their metrological and technical characteristics comply with the procedures of graduation and calibration of measuring instruments, as well as determination of antibiotic sensitivity of pathogenic microorganisms and authenticity of active substances in pharmaceutical drugs.Авторами работы изложены основные принципы процедуры установления метрологических характеристик, разрабатываемых стандартных образцов антибактериальных веществ утвержденного типа. Стандартные образцы антибактериальных веществ утвержденного типа предназначены для аттестации методик измерений и контроля точности результатов измерений. Стандартные образцы могут быть использованы для градуировки, калибровки средств измерений при соответствии метрологических и технических характеристик стандартного образца требованиям методик градуировки, калибровки средств измерений, а также определения чувствительности патогенных микроорганизмов к антибиотикам и подлинности действующего вещества в лекарственных средствах

Threat-sensitive anti-predator defence in precocial wader, the northern lapwing Vanellus vanellus

Birds exhibit various forms of anti-predator behaviours to avoid reproductive failure, with mobbing—observation, approach and usually harassment of a predator—being one of the most commonly observed. Here, we investigate patterns of temporal variation in the mobbing response exhibited by a precocial species, the northern lapwing (Vanellus vanellus). We test whether brood age and self-reliance, or the perceived risk posed by various predators, affect mobbing response of lapwings. We quantified aggressive interactions between lapwings and their natural avian predators and used generalized additive models to test how timing and predator species identity are related to the mobbing response of lapwings. Lapwings diversified mobbing response within the breeding season and depending on predator species. Raven Corvus corax, hooded crow Corvus cornix and harriers evoked the strongest response, while common buzzard Buteo buteo, white stork Ciconia ciconia, black-headed gull Chroicocephalus ridibundus and rook Corvus frugilegus were less frequently attacked. Lapwings increased their mobbing response against raven, common buzzard, white stork and rook throughout the breeding season, while defence against hooded crow, harriers and black-headed gull did not exhibit clear temporal patterns. Mobbing behaviour of lapwings apparently constitutes a flexible anti-predator strategy. The anti-predator response depends on predator species, which may suggest that lapwings distinguish between predator types and match mobbing response to the perceived hazard at different stages of the breeding cycle. We conclude that a single species may exhibit various patterns of temporal variation in anti-predator defence, which may correspond with various hypotheses derived from parental investment theory