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Native cobalt was found in amphibolite of the Kola superdeep borehole (SG-3) from a depth of 9630 m by a complex of local analytical methods (analytical scanning electron microscopy, electron backscatter diffraction). The studied amphibolite is a fine-grained melanocratic rock composed mainly of magnesioferri- hornblende and containing accessory native metal, telluride, sulphotelluride, and sulphide (Au, Ag, Pd, Bi, Cu, Pb, Zn, Sb, and Fe) mineralization.It also includes the clinopyroxene xenoclast carrying a fundamentally different set of accessories—poor in sulphides and including native cobalt. The absence of significant impurities, including iron, in native cobalt and its belonging to the hexagonal α-modification was determined. It is shown, that the metallic cobalt particles exposed during ion polishing of a compact pyroxene matrix cannot be a contaminant, introduced into the sample during drilling and sample preparation. Cobalt, obviously, was formed not only before the stage of retrograde metamorphism and subsequent hydrothermal processing of the amphibolite containing it, but probably long before the formation of the sedimentary protolith of this rock. That is, native cobalt belongs to the early high-temperature mineral phases inherited from the older Proterozoic—Archean main volcanism, while the time of formation of this layer of amphibolites dates back to the age of 2.4 billion years—the Early Karelian era of the Proterozoic. [ABSTRACT FROM AUTHOR]

Extensive analytical electron microscopical analyses were carried out from the micrometer scale down to the nanometer scale to characterize three variants of the 9% reduced activation ferritic martensitic (RAFM) steel EUROFER97/3. No huge microstructural differences were observed between the three grades. Electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM) was used to determine prior austenite grain (PAG) and lath sizes of the martensite matrix. The PAG size varied between 4.5 µm and 6.5 µm depending on the reconstruction algorithm. Furthermore, the martensitic lath sizes determined by SEM-EBSD are only half or 1/3 of that determined manually from transmission electron microscopy (TEM) images, which might be related to the limited statistics in this type of TEM data evaluations. The SEM-EDX shows that M23C6-type phases are preferentially located on lath and grain boundaries due to preferential diffusion of elements like Cr, W, and C to and along grain boundaries, which agrees with TEM-EDX measurements. TEM techniques like STEM-EDX and high-resolution TEM were used to describe the occurring precipitates i.e., M23C6, VN, TaC morphologically, structurally, and chemically. In addition, the thermodynamic calculations were carried out to explain phase formation, phase fraction and phase composition. The results are in good agreement with the experimentally determined values. These results will provide a profound basis to explain the mechanical performance of these materials. Furthermore, it will lay a good reference basis of comparison for the material after neutron irradiation.

The novel reduced activation ferritic/martensitic steel Eurofer 97 is employed by many concept designs for the plasma-facing first wall of the EU DEMO fusion reactor. These designs feature precision joints between Eurofer 97 coolant piping, for which an advanced laser-keyhole welding technique is proposed. In this work the microstructure of these novel laser-keyhole Eurofer 97 welds is modelled by combining finite element thermal analysis with precipitate kinetics modelling. Microanalysis of a representative specimen via scanning electron and high-speed atomic force microscopy techniques is also conducted, complimented by electron backscatter diffraction, energy-dispersive X-ray spectroscopy, and nanoindentation hardness testing. Models of the weld microstructure agree well with the results of microanalysis although the precipitate diameters predicted are slightly underestimated. Several large void defects were discovered within the weld fusion zone, the cause of which is suspected to arise from the evaporation of cerium-rich oxide inclusions present in the as-cast Eurofer 97 during welding.

Green microalgae Lobosphaera sp. IPPAS С-2047 and Micractinium simplicissimum IPPAS С-2056 were examined for the first time for cell tolerance to elevated concentrations of manganese applied in the form of MnCl2. Analyses of cell photosynthetic activity by chlorophyll fluorometry and the dynamic patterns of absorbance changes of cell suspensions at the peak of chlorophyll absorption revealed differential tolerance of two microalgae species to manganese. The acute toxicity assayed in 4-day treatments became apparent at manganese concentrations equal to or higher than 1 g/L for M. simplicissimum cells and at concentrations above 10 g/L for Lobosphaera sp. Transmission electron microscopy and energy-dispersive X-ray spectroscopy were used to study the subcellular distribution of manganese in microalgal cells under elevated nontoxic concentrations of manganese in the medium. The results with Lobosphaera sp. established the lack of individual manganese-containing inclusions on cell surfaces and in the cell interior; the intracellular distribution of manganese was dispersed with elevated accumulation of this element in the region of thylakoids and plastoglobules. The occurrence of manganese and phosphorus in plastoglobules was found for the first time. Apparently, these compartments become accessible for accumulation of Mn and P upon the translocation of thylakoid components during stress-induced disassembling of their structure. The cells of M. simplicissimum were able to oxidize the exoplasmic Mn2+ with the formation of manganese nanoparticles in the intercellular matrix as well as on the cell surface and within the cell walls. In addition, the manganese permeating into the cells was shown to compartmentalize in vacuoles and bind to the polyphosphate granules. [ABSTRACT FROM AUTHOR]

Coelastrella rubescens Kaufnerová & Eliás (Chlorophyceae) is a green, single-celled algae that lives in the terrestrial-air environment. Under stress conditions, its cells go into a state characterized by low photosynthetic activity and high content of reserve lipids and secondary carotenoids. For the first time, a comparative morphological, ultrastructural, and elemental analysis of vacuolar inclusions in the C. rubescens NAMSU R1 strain when cultivated on a mineral medium under conditions of low and high (causing stress) light intensity. Microalgae cells stained with the fluorescent dye DAPI showed signs of the presence of polyphosphates. Polarization microscopy in cells of C. rubescens has identified structures capable of refracting polarized light, which is typical of crystals. Cell analysis of C. rubescens with the transmission electron microscopy (TEM) method revealed the presence of various vacuoles with heterogeneous contents (autophagic bodies, crystalloids, and rounded globules of inhomogeneous electron density). With the exception of autophagic bodies noted in cells only in bright light, these inclusions were characteristic of microalgae cells, regardless of the intensity of illumination. The elemental composition of vacuolar inclusions was characterized by TEM in combination with energy-dispersive X-ray spectroscopy: the predominant content of nitrogen, phosphorus, or both elements simultaneously was established in them. The potential physiological role of C. rubescens vacuolar inclusions is discussed. [ABSTRACT FROM AUTHOR]

Amilenus aurantiacus overwinter in diapause, a natural starvation period, in hypogean habitats. The structure of spherites in the midgut diverticula (MD) and Malpighian tubules (MT) has been studied comparatively by light microscopy and TEM to detect eventual differences in mineral consumption in the beginning and at the end of the starvation period in these organs (MD and MT) associated with digestive processes. The chemical composition of spherites was examined by combining energy-dispersive X-ray spectroscopy (EDXS), electron energy-loss spectroscopy (EELS) and energy-filtered TEM (EFTEM). The structure of the spherites changed during overwintering in both organs. At the beginning of overwintering, the spherites were composed of densely packed concentric layers of electron-dense and electron-lucent material. In the middle and at the end of overwintering, the electron-lucent layers between the layers of material indicated the loss of some material. The chemical composition of the spherites changed only in the MD; at the beginning of overwintering, these contained Si, O, C and Fe, while later there was no more Fe. In contrast, spherites in the MT were composed of Si, O, C and Ca throughout overwintering. A less intensive exploitation of the MD spherites was probably due to complete cessation of digestive and other cell activity in this organ during the winter diapause; activity of the MT slowed, but continued removing the cell metabolites. [ABSTRACT FROM AUTHOR]

Palladium mineralization was registered in the Kola superdeep borehole (SG-3) for the first time in samples from deep horizons (in the fault zone at ~10 km). A proper palladium mineral (merenskyite) with the formula Pd1.00(Te1.21Bi0.79)2.00 was detected using the analytical electron microscopy and EBSD methods. The unusually high content of bismuth in the discovered merenskyite crystal most likely indicates the lower temperatures of its formation from a bismuth-rich fluid. This is supported by numerous finds of associated bismuth minerals (native and intermetallic minerals, sulfides, tellurides, and sulfotellurides) as well. A close geochemical association of noble and rare elements was revealed in the composition of the rich and diverse ore mineralization in the samples studied. It can be argued that a new type of mineralization was discovered for the SG-3 rocks: noble metal (Au–Ag–Pd) rare-element (Bi–Te). [ABSTRACT FROM AUTHOR]

Maya blue is a pigment found in different archaeological sites of different cultures from Mesoamerica, and also in colonial buildings in Mexico and Cuba. The pigment is made from a thermally treated mixture of indigo and palygorskite. Pigment samples from Aztec and non‐Aztec archaeological sites as well as reference Yucatecan palygorskites were studied in this paper to assess their differences. The characterization of the samples was carried out by a combination of a crystal–chemical‐point analyses using electron microscopy to obtain the structural formulae of the palygorskite crystals, and studied using high‐resolution X‐ray diffraction. The data show evidence that the palygorskite used by non‐Aztec cultures, such as the Maya, is compatible with palygorskite from known sources in the Yucatan Peninsula, while the palygorskite used by the Aztec culture is different in its structure and has an origin that is still unknown. [ABSTRACT FROM AUTHOR]

Manganese is added to many magnesium alloys to control impurity iron, but its effects on phase transformations and microstructure formation remain incompletely understood. Here we show that an Al-Mn-based decagonal quasicrystal (d-QC) forms in the late stages of solidification in AZ31 and AZ91 magnesium alloys at relatively slow cooling rates, here down to 0.1 K/s. The d-QC has a periodicity of ∼ 12 Å, grew as decagonal rods and commonly shared interfaces with Al 8 Mn 5 and eutectic Mg 17 Al 12. A reproducible orientation relationship (OR) was measured with Al 8 Mn 5 only, indicating that the d-QC nucleated on Al 8 Mn 5. The OR is consistent with the structural relationship between quasicrystals and gamma brasses and gives the d-QC nucleation advantages over LT-Al 11 Mn 4 during solidification. A subsequent heat treatment at 410 °C caused both Al 8 Mn 5 and the d-QC to transform into LT-Al 11 Mn 4. [Display omitted] [ABSTRACT FROM AUTHOR]

The changes in ATI® 718Plus™ (718Plus) superalloy microstructure after high-temperature long-term exposure (850 °C/4000 h/air) were characterized by two- and three-dimensional imaging techniques. The 718Plus microstructure consists of a γ-matrix strengthened by coherent γ′-phase and plate-like η-phase at grain boundaries. The η-phase analysis showed the presence of δ-phase stacking faults within it, along with fluctuations of chemical composition within these defects. Applied thermal exposure resulted in an increased amount of δ-, η-phases and formation of topologically close-packed phases. One of them was identified by electron diffraction as trigonal μ-phase. However, the difference in size and morphology revealed via tomographic reconstruction indicates that the formation of other topologically close-packed phases is possible. The μ-phase was enriched in Mo, Co, Fe and Cr, which causes their depletion in the γ-matrix and may detrimentally affect the superalloy mechanical properties. [ABSTRACT FROM AUTHOR]

Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30–40% relative humidity, RH) and dry nitrogen (RH

The structural and chemical microinhomogeneity of the high-entropy TiVZrNbHfTa coating is studied. Electron microprobe analysis shows that the content of elements varies within 10 at.% at a distance of several nanometers. The density of (s + d) electrons remains constant. High-resolution electron microscopy used to examine the fine structure found clusters with the size close to the 'periodicity' of the chemical inhomogeneity. [ABSTRACT FROM AUTHOR]

The iron oxide nanoparticles (IONPs) fabricated by pulsed wire evaporation were characterized by analytical electron microscopy and magnetic properties measurement system (MPMS). The IONPs produced at various charging voltages (2.6, 5.0 and 6.3 kV) exhibited the average size of 48 nm and the differences in shape, i.e., spherical (83%) and hexagonal (17%) structures. The hexagonal nanoparticles showed single-crystalline magnetite (Fe3O4) with major facets made of {111} planes. The chemical shifts in core–shell nanoparticles were observed by electron energy loss spectroscopy, indicating a dependency of the edge position related to the oxidation state of Fe. From the MPMS, the saturation magnetization and the coercivity of IONPs were measured to be 64 emu/g and 37 Oe at 300 K, respectively. The results provide useful information for the relationship between the nanostructure and magnetic behavior. TEM images of iron oxide nanoparticles (IONPs) fabricated by pulsed wire evaporation. Two distinct shapes of IONPs can be seen, i.e., hexagonal and core/shell structures. The hexagonal nanoparticles showed single-crystalline Fe3O4 magnetite with major facets made of {111} planes, while the core/shell nanoparticle consisted of Fe core and Fe3O4 shell. By magnetic property measurement system (MPMS), the saturation magnetization and the coercivity were measured to be 64 emu/g and 37 Oe at 300 K, respectively. This study provides the possibility for developing novel and various IONPs with unprecedented structures and/or magnetic properties. [ABSTRACT FROM AUTHOR]

The universal response of Escherichia coli to stress is enhancing the synthesis of specific histone-like Dps proteins that bind bacterial DNA. As a result, two-dimensional and three-dimensional crystalline arrays can be observed in the cytoplasm of starving bacteria. Conditions for obtaining in vitro co-crystals of DNA-Dps were selected, and their elemental composition was studied using analytical electron microscopy. It was found that Dps in the co-crystal retains its ferritin-like activity; that is, it can stimulate the oxidation of Fe2+ ions to Fe3+ and facilitate the accumulation of iron in the form of Fe2O3 in the inner cavity of the oligomer. [ABSTRACT FROM AUTHOR]

Oxide scale formed on a polycrystalline nickel-based superalloy was investigated using analytical electron microscopy combined with three-dimensional tomography via conjunction of focused ion beam with scanning electron microscope. Application of these two complementary methods and correlation of the microscopy findings with three-dimensional imaging allowed to describe in detail the structure, chemistry, morphology and spatial distribution of phases and other structural elements formed during oxidation. An original approach proposed in our study allowed to identify the interlayer of the δ phase formed beneath the chromia scale and discuss formation of phases in the near-surface area and their role during oxidation. Unlabelled Image [ABSTRACT FROM AUTHOR]

• ζ-factor microanalysis was successfully applied to quantify boron-rich ceramics. • A full range of ζ-factors were experimentally determined and validated. • Strategies to best determine boron carbide bulk stoichiometry were compared. • Boron carbide specimens with different stoichiometries were determined. • A ζ-factor raster scan technique was used to determine grain boundary compositions. Accurate quantification of light elements which produce only soft X-ray lines via X-ray energy dispersive spectrometry (XEDS) has been traditionally difficult due to poor X-ray emission and detector efficiencies at low energies and significant X-ray absorption effects. The ζ-factor microanalysis method enables one to correct for these shortcomings; however, ζ-factor microanalysis has not yet been thoroughly applied to inorganic materials which are entirely or mostly composed of light elements such as boron carbide, boron nitride, or boron suboxide. This work successfully extended ζ-factor microanalysis to boron-rich ceramics and accurately determined stoichiometries of multiple boron carbides and measured grain boundary compositions of a boron carbide mixed with additives consisting of rare-earth ions. Various strategies were employed to experimentally determine a full range of ζ-factors and measurements were validated using materials of known composition including silicon hexaboride and silicon carbide. Overall, this work has shown that XEDS is a viable technique for light element quantification in (scanning) transmission electron microscopy, in terms of both the accuracy and precision, which is comparable or superior to the complementary electron energy loss spectrometry. [ABSTRACT FROM AUTHOR]

• TKD on extraction replicas is highly efficient in nanoprecipitate phase mapping. • TKD identified more than one thousand M 23 C 6 , M 7 C 3 , M 2 X and MX nanoprecipitates. • Nanoprecipitates <100 nm, down to 20–25 nm size were successfully indexed. • HRTEM and CBED validated the TKD phase indexing of nanoprecipitates. • Automated structure-chemistry obtainable by combining TKD and STEM-EDX with MVSA. Statistically significant crystal structure and composition identification of nanocrystalline features such as nanoparticles/nanoprecipitates in materials chemistry and alloy designing using electron microscopy remains a grand challenge. In this paper, we reveal that differing crystallographic phases of nanoprecipitates in alloys can be mapped with unprecedented statistics using transmission Kikuchi diffraction (TKD), on typical carbon-based electron-transparent samples. Using a case of multiphase, multicomponent nanoprecipitates extracted from an improved version of 9% chromium Eurofer-97 reduced-activation ferritic-martensitic steel we show that TKD successfully identified more than thousand M 23 C 6 , MX, M 7 C 3, and M 2 X (M =Fe, Cr, W, V, Ta; X = C , N) nanoprecipitates in a single scan, something that is currently unachievable using a transmission electron microscope (TEM) without incorporating a precision electron diffraction (PED) system. Precipitates as small as ∼20–25 nm were successfully phase identified by TKD. We verified the TKD phase identification using high-resolution transmission electron microscopy (HRTEM) and convergent beam electron diffraction (CBED) pattern analysis of a few precipitates that were identified by TKD on same sample. TKD study was combined with state-of-art analytical scanning transmission electron microscopy (STEM)-energy dispersive X-ray (EDX) spectroscopy and multivariate statistical analysis (MVSA) which provided the complete crystal structure and distinct chemistries of the precipitates in the steel in a high throughput automated way. This technique should be applicable to characterizing any multiphase crystalline nanoparticles or nanomaterials. The results highlight that combining phase identification by TKD with analytical STEM and modern data analytics may open new pathways in big data material characterization at nanoscale that may be highly beneficial for characterizing existing materials and in designing new materials. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract The mechanism and kinetics of changes in the microstructure and phase composition of the surface diffusion area of the as-cast heat-resistant HP40NbTi alloy during prolonged, high-temperature aging in an oxidising environment are studied by optical microscopy, electron microscopy, electron microprobe analysis, and X-ray mapping. The transformation process of each phase of the alloy is unique, where these phases differ in their structure, chemical composition, and nature of the reaction with oxygen. When the alloy is oxidised, the chemical composition of the phases changes continuously according to complex laws, depending on the environment, temperature, and duration of exposure. An intensive exchange of chemical elements occurs between different phases. After long-term, high-temperature operation of the alloy, the process of oxidation of the phases probably attains a steady limiting state. Graphical abstract Unlabelled Image Highlights • The changes in the microstructure and phase composition of the subsurface area of HP40NbTi alloy during high-temperature aging. • The transformation process of each phase of the HP40NbTi alloy is unique. • When the alloy is oxidised, the chemical composition of the phases changes continuously according to complex laws. • An intensive exchange of chemical elements occurs between different phases. [ABSTRACT FROM AUTHOR]

The giant phiKZ phage infection induces the appearance of a pseudo-nucleus inside the bacterial cytoplasm. Here, we used RT-PCR, fluorescent in situ hybridization (FISH), electron tomography, and analytical electron microscopy to study the morphology of this unique nucleus-like shell and to demonstrate the distribution of phiKZ and bacterial DNA in infected Pseudomonas aeruginosa cells. The maturation of the pseudo-nucleus was traced in short intervals for 40 min after infection and revealed the continuous spatial separation of the phage and host DNA. Immediately after ejection, phage DNA was located inside the newly-identified round compartments; at a later infection stage, it was replicated inside the pseudo-nucleus; in the mature pseudo-nucleus, a saturated internal network of filaments was observed. This network consisted of DNA bundles in complex with DNA-binding proteins. On the other hand, the bacterial nucleoid underwent significant rearrangements during phage infection, yet the host DNA did not completely degrade until at least 40 min after phage application. Energy dispersive x-ray spectroscopy (EDX) analysis revealed that, during the infection, the sulfur content in the bacterial cytoplasm increased, which suggests an increase of methionine-rich DNA-binding protein synthesis, whose role is to protect the bacterial DNA from stress caused by infection.

This paper presents the results of microscopic investigations of the structure and chemical composition of the axial zones of continuous casting ingots of 140 x 140 mm cross-section made of G3Si1 steel, comprising the areas of porosityand axial shrinkage defects. The occurrence of shrinkage hollows and non-metallic phase, resulting from chemical reactions of the steel components with oxygen at the solidification front, has been stated in these areas.

Liquid-phase transmission electron microscopy (LPTEM) technique has been used to perform a wide range of in situ and operando studies. While most studies are based on the sample contrast change in the liquid, acquiring high qualitative results in the native liquid environment still poses a challenge. Herein, we present a novel and facile method to perform high-resolution and analytical electron microscopy studies in a liquid flow cell. This technique is based on removing the liquid from the observation area by a flow of gas. It is expected that the proposed approach can find broad applications in LPTEM studies., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Exosomes are nanovesicles known to mediate intercellular communication. Although it is established that zinc ions can act as intracellular signaling factors, the measurement of zinc in circulating nanovesicles has not yet been attempted. Providing evidence of the existence of this zinc fraction and methods for its measurement might be important to advance our knowledge of zinc status and its relevance in diseases. Exosomes from 0.5 ml of either fresh or frozen human plasma were isolated by differential centrifugation. A morphological and dimensional evaluation at the nanoscale level was performed by atomic force microscopy (AFM) and Transmission Electron Microscopy (TEM). Energy Dispersive X-Ray Microanalysis (EDX) revealed the elemental composition of exosomes and their respective total Zinc content on a quantitative basis. The zinc mole fraction (in at%) was correlated to the phosphorous mole fraction, which is indicative for exosomal membrane material. Both fresh (Zn/P 0.09 ± 0.01) and frozen exosomes (Zn/P 0.08 ± 0.02) had a significant zinc content, which increased up to 1.09 ± 0.12 for frozen exosomes when treated with increasing amounts of zinc (100–500 μM; each p < 0.05). Interestingly, after zinc addition, the Calcium mole fractions decreased accordingly suggesting a possible exchange by zinc. In order to estimate the intra-exosomal labile zinc content, an Imaging Flow Cytometry approach was developed by using the specific membrane permeable zinc-probe Fluozin-3AM. A labile zinc content of 0.59 ± 0.27 nM was calculated but it is likely that the measurement may be affected by purification and isolation conditions. This study suggests that circulating nano-vesicular-zinc can represent a newly discovered zinc fraction in the blood plasma whose functional and biological properties will have to be further investigated in future studies. [ABSTRACT FROM AUTHOR]

Pulsed laser ablation of bulk Pt in tetraethyl orthosilicate caused C-doped Pt and its silicides with special structures as identified by analytical electron microscopy. The former belongs to lamellar/fcc-type, whereas the latter are orthorhombic PtSi with (110) polysynthetic twinning and body-centered tetragonal Pt 16 Si 7 C 1 , i.e. a 2 2 × 2 2 × 1 supercell of the parental Pt 2 Si 1-x by Si/C ordering, with well-developed (132) face having periodic bond chains bypassing the covalent Si-C clusters at the body center. The C-doped PtSi particulate tended to coalesce with the fcc-Pt particulate following the epitaxial relationship [100] PtSi //[011] Pt ; (001) PtSi //(100) Pt across a curved interface for 3-D lattice match. The overall substances have significant UV absorption for potential optocatalytic applications and shed light on dynamic phase selection in the Pt-Si-C system. [ABSTRACT FROM AUTHOR]

Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30-40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSex film (specific wear rate of 2 × 10−8 mm3 N-1m-1 and a friction coefficient of 0.03-0.05) was compared with that of the well-established MoS2 lubricant material. [ABSTRACT FROM AUTHOR]

M2 tool steel was used as a feedstock material for casting from the the semisolid range between 1310-1350oC corresponding to 25 - 50 % of the liquid phase. The chemical composition of the investigated steel is following: 0.85%C, 3.9 %Cr, 6.7 %W, 4.7 %Mo and 1.7 % V. A specially constructed machine allowed thixoforming in a protective argon atmosphere and semisolid forming at a high piston velocity powered by a high air pressure. After heating of the feedstock using induction heating by the stamping of semi-liquid sample to a graphite mould pre-heated by resistance heating. The material after thixoforming from 1315oC shows a globular microstructure with a relatively small globule’s size between 30-50 μm. The crystal structure of globules contained, austenite and martensite, while that of the eutectic, ferrite and W2C, Fe3C, Mo2C, M23C6 and VC carbides as determined by X-ray studies and confirmed using electron diffraction studies. The alloying elements like Mo, W and V are concentrated in the eutectic, while Cr only in thixoformed samples segregates to the carbides and indeed M23C6 was identified. The hardness significantly increases up to 780 HV after thixo-forming due to formation of martensite. The other part was cast from the liquid phase at 1450o C using melt spinning method allowing high cooling rate. The microstructure of melt spun ribbon shows a cellular microstructure of austenitic and martensitic structure without the eutectic. The WC and M23C6 carbides were located at the cell’s boundariers. The microhardness near 1300 HV of the ribbon was much higher than that of semisolid formed samples.

Vacuole is a multifunctional compartment central to a large number of functions (storage, catabolism, maintenance of the cell homeostasis) in oxygenic phototrophs including microalgae. Still, microalgal cell vacuole is much less studied than that of higher plants although knowledge of the vacuolar structure and function is essential for understanding physiology of nutrition and stress tolerance of microalgae. Here, we combined the advanced analytical and conventional transmission electron microscopy methods to obtain semi-quantitative, spatially resolved at the subcellular level information on elemental composition of the cell vacuoles in several free-living and symbiotic chlorophytes. We obtained a detailed record of the changes in cell and vacuolar ultrastructure in response to environmental stimuli under diverse conditions. We suggested that the vacuolar inclusions could be divided into responsible for storage of phosphorus (mainly in form of polyphosphate) and those accommodating non-protein nitrogen (presumably polyamine) reserves, respectively. The ultrastructural findings, together with the data on elemental composition of different cell compartments, allowed us to speculate on the role of the vacuolar membrane in the biosynthesis and sequestration of polyphosphate. We also describe the ultrastructural evidence of possible involvement of the tonoplast in the membrane lipid turnover and exchange of energy and metabolites between chloroplasts and mitochondria. These processes might play a significant role in acclimation in different stresses including nitrogen starvation and extremely high level of CO and might also be of importance for microalgal biotechnology. Advantages and limitations of application of analytical electron microscopy to biosamples such as microalgal cells are discussed. [ABSTRACT FROM AUTHOR]

The structure of niobium carbide particles in as-cast heat resistant modified HP40NbTi alloy have been studied by light and electron microscopy, electron microprobe and X-ray diffraction. The niobium carbide particles in the structure of the HP40NbTi alloys are a multiphase polycrystal clusters with inhomogeneous chemical composition and crystallographic form. The boundaries between the crystals of the carbide particle are large-angle; the disorientation angle between crystals is 30–60°. Polycrystalline character of carbides is, probably, connected with the high thermal stress arising at interphase boundaries in the alloy structure at primary cooling of an ingot. The explanation of the polymorphic character of a niobium carbide cluster requires an independent analysis on the basis of a structural and geometrical crystallography. [ABSTRACT FROM AUTHOR]

Tribological coatings made of MoS2and WSe2phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30–40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSexfilm (specific wear rate of 2 × 10−8 mm3 N–1m–1and a friction coefficient of 0.03–0.05) was compared with that of the well-established MoS2lubricant material. [ABSTRACT FROM AUTHOR]

The analysis of nanomaterials in pharmaceutical or cosmetic preparations is an important aspect both in formulation development and quality control of marketed products. Despite the increased popularity of nanoparticulate compounds especially in dermal preparations such as emulsions, methods and protocols of analysis for the characterization of such systems are scarce. This work combines an original sample preparation procedure along with different methods of analytical electron microscopy for the comprehensive analysis of fluid or semi-solid dermal preparations containing nanoparticulate material. Energy-filtered transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and high resolution imaging were performed on model emulsions and a marketed product to reveal different structural aspects of both the emulsion bulk phase and incorporated nanosized material. An innovative analytical approach for the determination of the physical stability of the emulsion under investigation is presented. Advantages and limitations of the employed analytical imaging techniques are highlighted.