Numerous Inclusions Research Articles

A case of fibrinogen storage disease with primary biliary cholangitis

A 66-year-old woman was diagnosed as primary biliary cholangitis (PBC) and was previously hospitalized for ascites and jaundice. She came to our hospital for further examination of the liver by needle biopsy, which showed interface hepatitis that mainly comprised lymphocytes and inflammatory infiltrates in the bile duct in the portal area. On the other hand, numerous intracytoplasmic inclusions that were positive for fibrinogen immunostaining were seen in the lobular area. Finally, we histologically diagnosed as PBC with fibrinogen storage disease (FSD). FSD is rare disease that leads to liver damage caused by abnormal fibrinogen storage in the endoplasmic reticulum of hepatocytes, with only four cases reported in Japan until now.

Structure of the yolk syncytial layer during postembryonic development of Andinoacara rivulatus (Günther), 1860 (Cichlidae)

Temporary “extraembryonic” systems are important for the development of representatives of many Metazoan taxa and are characterized by significant diversity. The yolk syncytial layer (YSL), a component of embryonic and larval teleost yolk complex, is a provisory structure performing morphogenetic, nutritional and immune functions. Despite the crucial role of YSL in the early ontogeny of bony fishes, the data concerning YSL structure and morphological diversity is scant. Here, we describe YSL organization in the postembryonic development of the green terror cichlid, Andinoacara rivulatus, studied by the analysis of serial histological sections. YSL cytoplasm contains numerous yolk inclusions decreasing in size from basal to apical surface of YSL. The mode of yolk engulfment is one of the most variable YSL characteristics in the species studied. The yolk syncytial nuclei (YSN) have especially complex shape, and large nucleoli are well distinguished. The yolk mass consists of homogenous globules. It contains the oil globules, many of which are in contact with the basal surface of YSL. The YSL thickness is very uneven due to its interaction with oil globules. Significant part of the apical YSL surface is associated with the blood vessels and pigment cells. During the period of mixed feeding the yolk complex locates anterior to the liver. Thus, the yolk complex of green terror cichlid has a well-differentiated structure. Our results contribute to the knowledge of the morphology of fish temporary systems and allow clarifying their common and species-specific features.

Circadian sleep/wake-associated cells show dipeptide repeat protein aggregates in C9orf72-related ALS and FTLD cases

Motor-, behavior- and/or cognition-related symptoms are key hallmarks in patients with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) with TDP-43 pathology (FTLD-TDP), respectively. It has been reported that these patients also experience sleep disturbances, which might implicate a disturbed circadian rhythm of the sleep/wake cycle. It remains unknown, however, whether cells involved in the circadian sleep/wake cycle are affected by ALS- and FTLD-related neuropathological changes including phosphorylated TDP-43 (pTDP-43) aggregates and dipeptide repeat protein (DPR) inclusions resulting from the C9orf72 hexanucleotide repeat expansion. Immunohistochemistry for DPR and pTDP-43 pathology was performed in post-mortem hypothalamus and pineal gland tissue of patients with ALS and/or FTLD-TDP with and without the C9orf72 repeat expansion and healthy controls. Circadian sleep/wake-associated cells, including pinealocytes and hypothalamic neurons related to the suprachiasmatic nucleus (SCN), were microscopically assessed. We observed numerous DPR inclusions (poly(GA), poly(GP), poly(GR) and poly(PR)) in the pinealocytes and few poly(GA) inclusions in the SCN-related neurons in C9orf72-related ALS and/or FTLD-TDP cases. These circadian sleep/wake-associated cells, however, were devoid of pTDP-43 pathology both in C9orf72- and nonC9orf72-related ALS and/or FTLD-TDP cases. Our neuropathological findings show that pinealocytes and, to a lesser extent, SCN-related neurons are affected by DPR pathology. This may reflect an involvement of these cells in sleep/wake disturbances observed in ALS and/or FTLD-TDP patients.

Numerical inclusion of exact periodic solutions for time delay Duffing equation

Numerical inclusion results for exact periodic solutions are presented for the time delay autonomous Duffing equations. Constructive implicit function theorem is used for including one dimensional solution manifolds consisting of exact periodic solutions. A conjecture of a lower bound for a number of periodic solutions is given as a function of the time delay. If the delay time is less than 30, we have proved this conjecture using verified numerical computations.Theory for proving the existence of periodic solutions of the forced delay Duffing equation is proposed based on the verified numerical computations. The forced term is sinusoidal waves. Stress is on a study of the bifurcation of periodic solutions synchronizing to the external forces. A rich bifurcation phenomena of periodic solutions are reported taking the delay time as parameters. Especially, a kind of fractal structure is observed concerning resonance peaks.

Experimental Production of Cu–Cr–N Composite Alloys and Thermodynamic Modeling of Their Phase Composition

Composite Cu–Cr–N alloys were obtained in situ under vibration of “copper melt–chromium powder” compositions before their crystallization. Two types of alloys were prepared, where chromium powder was freely dispersed or compacted into a tablet. Atmospheric nitrogen was used as a source of chromium nitrides in the alloys. The microstructure of the alloys is represented by a copper matrix hardened with chromium particles and numerous inclusions of nonstoichiometric chromium nitrides Cr2N1 – x. Thermodynamic modeling showed that the composition and quantities of chromium nitrides in the Cu–Cr–N alloy depend on the partial pressure of nitrogen above the melt.

Shock‐thermal history of the Agoudal (IIAB) iron meteorite from microstructural studies

AbstractThe Agoudal IIAB iron meteorite exhibits only kamacite grains (~6 mm across) without any taenite. The kamacite is homogeneously enriched with numerous rhabdite inclusions of different size, shape, and composition. In some kamacite domains, this appears frosty due to micron‐scale rhabdite inclusions (~5 to 100 μm) of moderate to high Ni content (~26 to 40 wt%). In addition, all the kamacite grains in matrix are marked with a prominent linear crack formed during an atmospheric break‐up event and subsequently oxidized. This feature, also defined by trails of lowest Ni‐bearing (mean Ni: 23 wt%) mm‐scale rhabdite plates (fractured and oxidized) could be a trace of a pre‐existing γ–α interface. Agoudal experienced a very slow rate of primary cooling ~4 °C Ma−1 estimated from the binary plots of true rhabdite width against corresponding Ni wt% and the computed cooling rate curves after Randich and Goldstein (1978). Chemically, Agoudal iron (Ga: 54 ppm; Ge: 140 ppm; Ir: 0.03 ppm) resembles the Ainsworth iron, the coarsest octahedrite of the IIAB group. Agoudal contains multiple sets of Neumann bands that are formed in space and time at different scales and densities due to multiple impacts with shock magnitude up to 130 kb. Signatures of recrystallization due to postshock low temperature mild reheating at about 400 °C are also locally present.

Immunohistochemical and Ultrastructural Features of the Seasonal Changes in the Epididymal Epithelium of Camel (Camelus dromedarius).

In order to evaluate the influence of reproductive activity on the functional role of the epididymal epithelium in the Egyptian dromedary camel, Connexin-43 (Cx-43), vascular endothelial growth factor (VEGF), and androgen receptor (AR) immunoreactivity in the epididymal epithelium and the fine structure of the principal, dark, basal, apical, and halo cells were investigated. The secretory activity of the principal cells was amplified in the breeding season, while its endocytotic function became more active in the nonbreeding season. This was evidenced by punctate strong immunoreactive signals for Cx-43, which appeared to be more intense in the apical region of these epithelial cells, and the extremely long slender stereocilia (microvilli) with multiple junctional complexes. The nonbreeding principal cells revealed granular immunoreactive signals for VEGF scattered in the apical and basal cytoplasm. Ultrastructurally, both extreme vacuolation and several multivesicular inclusion bodies were observed in their cytoplasm. Dark cell size greatly diminished in the nonbreeding season and their nuclear morphology greatly changed from oval to lobulated shape. The plasma membrane of the apical cells expressed several infoldings (microvilli) in the breeding season. However, it was almost smooth in the nonbreeding season except for a small microvillus that appeared as a bleb-like projection. In some regions, a strong dense immunoreactivity for VEGF could be recognized in the cytoplasm of the apical cells and some basal ones. Halo cells with numerous multivesicular inclusions occupying most of the cytoplasm and a lobulated eccentric nucleus were detected in the nonbreeding season. In conclusion, these findings indicate that the reproductive activity has a significant impact on the immunohistochemical and ultrastructural profiles of the epithelial cells lining the Egyptian dromedary camel epididymis.

FATAL RANAVIRUS INFECTION IN A GROUP OF ZOO-HOUSED MELLER'S CHAMELEONS (TRIOCEROS MELLERI).

A group of five juvenile Meller's chameleons (Trioceros melleri) experienced 100% mortality over a period of 1 mo due to ranavirus infection. The index case was found dead without premonitory signs. The three subsequent cases presented with nonspecific clinical signs (lethargy, decreased appetite, ocular discharge) and were ultimately euthanatized. The final case died after initially presenting with skin lesions. Postmortem examination revealed thin body condition in all five animals and mild coelomic effusion and petechiae affecting the tongue and kidneys of one animal. Microscopically, all animals had multifocal necrosis of the spleen, liver, and kidney; four of five animals had necrosis of the nasal cavity; and two of five had necrosis of adrenal tissue, bone marrow, and skin. Numerous basophilic intracytoplasmic inclusions were present in the liver of all animals and nasal mucosa of three of the five animals. Consensus polymerase chain reaction for herpesvirus and adenovirus were negative, whereas ranavirus quantitative polymerase chain reaction was positive. Virus isolation followed by whole genome sequencing and Bayesian phylogenetic analysis classified the isolates as a strain of frog virus 3 (FV3) most closely related to an FV3 isolate responsible for a previous outbreak in the zoo's eastern box turtle (Terrapene carolina carolina) group. This case series documents the first known occurrence of ranavirus-associated disease in chameleons and demonstrates the potential for interspecies transmission between chelonian and squamate reptiles.

Agate mineralization in spilitized Permian volcanics from “Borówno” quarry (Lower Silesia, Poland) – microtextural, mineralogical, and geochemical constraints

Two forms of silica mineralization, i.e.: (1) vein agates and (2) moss agates, were encountered for the first time within spilitized (albite-rich) alkali-basalts from the upper parts of Borówno quarry (Intra-Sudetic Basin). Vein agates consist predominately of length-fast chalcedony evolving into strongly-zoned prismatic quartz with a distinctive blue cathodoluminescence. They exhibit the abundance of microtextures typical of epithermal vein systems (i.e. pseudo-bladed, flamboyant/feathery, jigsaw puzzle/mosaic, and Bambauer quartz), but also comprise numerous solid inclusions such as sulphides (pyrite, marcasite, chalcopyrite, and chalcocite), sulphates (barite), carbonates (calcite, dolomite), carbonaceous material, and hematite. The formation of vein agates was marked by strong variations in physicochemical conditions (pH, silica content) of SiO2-bearing fluids and recrystallization of metastable silica phases (i.e. moganite), coupled with the local replacement of pre-existing sulphates and/or carbonates by silica during boiling-related conditions. Their LREE-enriched rare-earth patterns with positive Eu anomaly invoke the close relationship between host rocks alterations (spilitization) and origin of SiO2-rich fluids. Conversely, moss agates have formed as a result of a spherical growth of siliceous phases within vesicles and contain numerous mineral inclusions of hematite, goethite, anatase, as well as ore-related phases (mottramite and dickite). The examination of their surface micro-morphology showed a strong age-related maturation marked by the development of stacked silica plates (plate-edge-like structure). The botryoidal-shaped, white-coloured, and Al-enriched outermost layer of these agates possibly reflects a rapid deposition of the initial silica gel onto the cavity walls. The HREE-enriched rare-earth patterns of the moss agates, combined with the presence of positive Eu and Ce anomalies, suggest their parental SiO2-rich fluids could be derived from multiple sources (e.g. volcanics mesostasis and/or meteoric waters). The fluids responsible for the formation of agate mineralization within alkali-basalts in Borówno could be derived from syn- or post- alterations of their host rocks.

Filter feeding in Late Jurassic pterosaurs supported by coprolite contents.

Diets of pterosaurs have mainly been inferred from indirect evidence such as comparative anatomy, associations of co-occurring fossils, and functional morphology. Gut contents are rare, and until now there is only a single coprolite (fossil dropping), with unidentified inclusions, known. Here we describe three coprolites collected from a palaeosurface with numerous pterosaur tracks found in early Kimmeridgian (Hypselocyclum Zone) intertidal deposits of the Wierzbica Quarry, Poland. The specimens’ morphology and association to the tracks suggest a pterosaur producer. Synchrotron scans reveal numerous small inclusions, with foraminifera making up the majority of the identifiable ones. Other small remains include shells/carapaces (of bivalves, ostracods, and other crustaceans/arthropods) and bristles (some possibly of polychaete worms). The high density of the small shelly inclusions suggest that they were not accidently ingested, but constituted an important food source for the pterosaur(s), perhaps together with unpreserved soft-bodied animals. The combined evidence from the tracks and coprolites suggest a filter-feeding ctenochasmatid as the most likely tracemaker. If true, this significantly expands the bromalite record for this pterosaur group, which was previously only known from gastroliths. Moreover, this study also provides the first direct evidence of filter feeding in Jurassic pterosaurs and shows that they had a similar diet to the recent Chilean flamingo (Phoenicopterus chilensis).

The Problem of Formation of Mixed Crystals and High-Efficiency K2(Co, Ni)(SO4)2 • 6H2O Optical Filters

This review, for the first time, summarizes the results of studies of the defect formation mechanisms in mixed crystals grown from aqueous solutions. The general mechanism of interaction of a crystal with a foreign solution is described (reaction of isomorphous replacement). As a result of this reaction, the crystal surface turns into a mosaic of local areas where multidirectional processes (dissolution and growth) occur simultaneously. Data on mosaic microinhomogeneity, which is a new type of composition inhomogeneity inherent solely to multicomponent crystals, is presented. A new mechanism for the mismatch stress relaxation in heterocompositions of brittle crystals grown from low-temperature solutions is described; in this case, the formation of misfit dislocations is impossible and stress relaxation occurs due to the formation of numerous inclusions at the interface. The general concept of growing high-quality mixed crystals from solutions is described, using the example of K2(Co, Ni)(SO)2 · 6H2O (KCNSH) mixed crystals.

New evidence for the prograde and retrograde PT-path of high-pressure granulites, Moldanubian Zone, Lower Austria, by Zr-in-rutile thermometry and garnet diffusion modelling

Compositional zoning in garnet, mineral inclusions and the application of the Zr-in-rutile thermometry on rutile inclusions in garnet in combination with conventional geothermobarometry and thermodynamic modelling allows a reconstruction of the prograde pressure-temperature evolution in felsic and mafic high-pressure granulites from the Moldanubian Zone, Bohemian Massif, Lower Austria. Most garnets in these rocks show homogeneous core compositions with high grossular contents (~30 mol%), while their rim zones have a markedly reduced grossular content. Rutile inclusions in the grossular rich garnet cores have low Zr concentrations (400 to 1300 ppm) indicating a formation temperature of ~810–820 °C which implies that the garnet host grew at these temperature conditions as well. Based on numerous polycrystalline melt inclusions, high Ti-biotite relics and a generally high Ti concentration in garnet cores, the peritectic biotite breakdown reaction is considered to be responsible for a first garnet growth, now observed as high-grossular garnet cores. The corresponding pressure is estimated to be in the range of 1.6 to 2.5 GPa, based on experimentally determined biotite breakdown reactions, thermodynamic modelling and the occurrence of high-Ti biotite in garnet cores. Rutile inclusions in low-Ca garnet rims contain significantly higher Zr concentrations (1700 to 5800 ppm) resulting in ultrahigh temperatures of ~1030 °C. Similar temperature as well as corresponding pressure estimates of 1000 ± 50 °C and 1.60 ± 0.10 GPa were obtained by geothermobarometry and thermodynamic modelling using garnet rim and re-integrated ternary feldspar compositions. These high pressure and ultrahigh temperature conditions are well known from literature for these granulites. The proposed two-phase garnet growth is not only seen in different temperatures obtained from rutile inclusions in garnet core and rim areas, but also in discontinuous trace (Cr, Ga, P, Ti, V, Zr) and heavy rare earth element profiles across garnet porphyroblasts, implying a different reaction mechanism for garnet rim growth. This second phase of garnet growth must have occurred during near isobaric heating to the ultrahigh temperature peak, most likely even at slightly lower pressures compared to the garnet core growth.By applying a binary Fe-Mg diffusion model to strongly zoned garnet grains a maximum timescale of 5–6 million years was estimated for the exhumation and cooling process, assuming a linear cooling path from 1000 °C at 1.6 GPa to 760 °C at 0.8 GPa. This short-lived ultrahigh temperature event corresponds to cooling and exhumation rates of 40–50 °C Ma−1 and 5.3–6.6 mm y−1, respectively.

Rabies-like neuronal inclusions in a dog with meningoencephalomyelitis and neuritis of unknown origin

A four-year-old intact female pointer dog from a hunting plantation in South Georgia, USA, developed acute neurological signs. The referring veterinarian suspected rabies or pseudorabies; the dog was euthanased and...

New Galerkin-vector theory and efficient numerical method for analyzing steady-state heat conduction in inhomogeneous bodies subjected to a surface heat flux

This paper reports a new semi-analytical model, together with core analytical solutions, for solving steady-state heat-conduction problems involving materials of a semi-infinite matrix embedded with arbitrarily distributed inhomogeneities, and a novel fast computing algorithm for model construction. The thermal field is analyzed as the summation of the solution to the homogeneous matrix and the variations caused by the inhomogeneities. The former is obtained through the route of discrete convolution and FFT/Influence coefficients/Green’s function, and the surface heat flux via the conjugate gradient method (CGM). The eigentemperature gradient of the latter is tackled with the numerical equivalent inclusion method (EIM) based on the new analytical formulas for the disturbed temperature and heat flux from the Galerkin vectors. The influences of inhomogeneity shape, location, and heat-conduction properties are studied, and the thermal fields affected by multi-inhomogeneities in a layered form and with a regular or a random distribution are investigated.

Different ecophysiological and structural strategies of toxic and non-toxic Microcystis aeruginosa (cyanobacteria) strains assessed under culture conditions

Microcystis aeruginosa causes severe problems in freshwater environments worldwide due to its capacity to form blooms and produce toxins. Natural populations contain a mixture of strains that vary in morphology, genotype and microcystin production. Beyond its toxic effect in animals, the possible role of microcystin in the metabolism of the producing cell is also a topic of interest. Recent studies pointed to a protective role against cellular oxidative stress. Since natural populations include microcystin producing and non-producing strains, the latter must rely on other ecophysiological traits to thrive. Here, we compared a toxic and a non-toxic strain of M. aeruginosa displaying different morphotypes and growth behaviors, aiming to explore the role of microcystin in an integrated way to the primary metabolism. The toxic strain formed large floating colonies (150–1850 μm) with densely aggregated cells, numerous gas vesicles and lipid inclusions and a typical irregular thylakoid arrangement. The non-toxic strain remained submerged, formed small colonies (< 100 μm) with a dense mucilage covering few sparse cells with rare gas vesicles and various types of thylakoids. It showed a higher abundance of carboxysomes, cyanophycin and polyphosphate granules and also greater amounts of pigments than the toxic strain. The antioxidant potential was higher for the toxic strain and it presented a higher expression of proteins related to photosynthesis, protein folding and cellular redox homeostasis. These traits of the toxic strain were compatible with growth under higher irradiance and microcystin can be a key factor to this adaptation. Growing submerged, the non-toxic strain showed preference for a lower light intensity and invested in intracellular reserves. This study illustrates different adaptive strategies of M. aeruginosa morphotypes that can be valuable in nature, enabling this species to widely exploit freshwater ecosystems.

Exploring the Mechanism of Action of Membrane Fusion Protein IncA Using Molecular Dynamics Simulations

Infecting millions of people each year, Chlamydia trachomatis is currently the leading cause of non‐congenital blindness and pelvic inflammatory disease. Incapable of replicating on its own, this bacterium survives by entering a host cell through endocytosis and subsequently modifying the vacuole in which it is enclosed to allow for replication. The newly formed replicative compartment, referred to as an inclusion, has numerous inclusion membrane proteins (Inc proteins) that promote growth and maintenance of the developing C. trachomatis bodies. One Inc in particular, known as IncA, exponentially enhances growth of C. trachomatis by initiating the homotypic fusion of multiple inclusions within a host cell. Although the structure and significance of IncA are known, its mechanism of action remains a mystery. The present research aims to elucidate the structure‐function relationship of IncA; offering insight into fusion protein functionality and potential targets for drug development. Analysis of IncA was accomplished by running Constant pH Molecular Dynamics (CpH MD) simulations with a refined focus on aspartic acids, glutamic acids, and histidines. Similar to conventional MD, CpH MD creates conditions that mimic the natural environment of IncA but with the additional capability to explore protonation states of residues. By running the CpH MD system across a range of pHs, the necessary data are generated to determine dissociation constants for specific residues. Combining proton dissociation with tests examining the solvent accessibility of IncA residues, results suggested that there is a correlation between accessibility of a residue and its proton dissociation. Further analysis of residue fluctuation at varying pHs shows that there appears to be a relationship between a residue's protonation state and the degree to which that residue fluctuated throughout a simulation. These findings demonstrate that the location of titratable residues influence the activity of IncA and furthermore, that IncA's titratable residues affect inclusion membrane fusion.Support or Funding InformationNational Science Foundation, Grant No. 1560325.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Petrography and geochemistry of mantle xenoliths from Ibal-Oku region (North-West region, Cameroon): Preliminary evidence of mantle heterogeneities

Located on the central part of the continental section of Cameroon Volcanic Line, Oku Mountains are one of the largest massifs of this volcano-tectonic structure. These mountains contain ultramafic mantellic xenoliths of peridotites and pyroxenites accidently reared by the Ibal-Oku recent basalts. Petrographically, the peridotites are composed of Fe-rich lherzolites and wehrlites (mg# between 82.7 and 89.9) whereas pyroxenites which constitute the majority of the xenoliths consist of websterites and olivine-websterites (mg# range 80.1–83.6). Some of the pyroxenites Cpx embody apatite and calcite and numerous fluid inclusions. From a geochemical point of view, the study of these xenoliths shows that the upper mantle of the Oku region in general and that of Ibal-Oku in particular has undergone at least two major events: the variations observed among the major elements and some compatible elements can be described in terms of partial melt, whereas the observed heterogeneities in trace elements and rare earths are related to carbonatitic metasomatism. Peridotites are Fe-rich, likely as a result of basaltic melt percolation. Texturally, these xenoliths have secondary protogranular and porphyroclastic textures and bear marks of deformation from the upper mantle. This mantle underwent a lithospheric uplift marked by the presence of clinopyroxenes exsolution lamellae in the orthopyroxenes and screws towards it.

A Computational Scheme for the Interaction between an Edge Dislocation and an Arbitrarily Shaped Inhomogeneity via the Numerical Equivalent Inclusion Method

The interactions between dislocations and inhomogeneity may play an important role in strengthening and hardening of materials. The problem can be solved analytically only for limited cases of simple geometry. By employing the recently developed numerical equivalent inclusion method, this work presents an effective computational scheme for studying the stress field due to an edge dislocation in the vicinity of an arbitrarily shaped inhomogeneity. The inhomogeneity is treated as an equivalent inclusion that is numerically discretized by rectangular elements. The mismatch between the matrix and the inhomogeneity materials are formulated through Dundurs’ parameters for numerical stability and robustness. The proposed method can efficiently and accurately evaluate the elastic field of the equivalent inclusion with the assistance of a fast Fourier transform based algorithm, constituting an essential refinement of the existing approach in the dislocation-inhomogeneity literature. Several benchmark examples are examined to demonstrate the flexibility, efficiency and accuracy of the present method.

Investigation into the Structure and Oxidation Mechanism of FeAlCr/Al2O3 Detonation Spraying Coatings

The oxidation resistance of detonation spraying coatings of the FeAlCr/Al2O3 powder fabricated by mechanically assisted self-propagating high-temperature synthesis using aluminothermic reactions of oxide reduction is investigated. The powder has a sufficiently homogeneous composite structure consisting of chromium-alloyed ordered B2-FeAl and fine inclusions of α-Cr2O3 and α-Al2O3. The detonation coatings sprayed on stainless steel substrates have a typical layered structure without cracks and spalling. The coating thickness is 250–300 μm, and microhardness is in a range of 5.9–6.1 GPa. Coatings of the synthesized powder mainly inherit its structure and phase composition, although certain aluminum and chromium oxidation occurs when spraying. The features of the cyclic and isothermal oxidation of coatings in air in a temperature range of 900–1000°C are studied. It is established that the oxidation resistance of detonation coatings of the synthesized powder after oxidation in air for 48 h at 950°C is close that of coatings formed from the FeAl‒FexAly powder with an aluminum content of 45 wt %. At the same time, the linear thermal expansion coefficient (LTEC) of FeAlCr/Al2O3 coatings is closer to the LTEC of the base material, while their creep resistance is higher when compared the latter due to the presence of fine refractory oxide inclusions. It is assumed that α-Cr, Cr2O3, and numerous fine alumina inclusions present in the synthesized powder (and which form when spraying) accelerate the protective film, formation suppressing hematite nucleation and growth at early oxidation stages at temperatures up to 950°C.

Numerical Simulation for Elasto-Plastic Contact of Novel Ti-(SiCf/Al3Ti)-Laminated Composite with Double-Layered SiC Fiber Reinforcements

An innovative, high-strength metal–intermetallic-laminate (MIL) composite Ti-(SiCf/Al3Ti), reinforced by double or even several SiC fiber rows, was fabricated. A high-efficiency, semi-analytical model with a numerical equivalent inclusion method (NEIM) was employed to investigate the deformation behaviors, microscopic strengthening, and failure mechanisms of the composite during elasto-plastic sphere–plane contact. The microstructure and interface features were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The contact model for the Ti-(SiCf/Al3Ti) composite was validated via quasi-static compressive indentation tests with a spherical indenter. A series of in-depth parametric studies were conducted to quantify the effect of the microstructure. The results indicate that the as-fabricated laminated composite has a well-organized microstructure and a higher volume fraction of fibers. The SiC fiber rows effectively enhance the strength and toughness of the composite. The optimal diameter of the SiC fibers is 32 μm when the horizontal center distance between the adjacent fibers is 2.5 times that of the fiber diameter. The hole defects occurring above the fibers would damage the material strength most compared with those occurring in other positions. The optimal quantity of the SiC fiber rows is four when the thickness of the SiCf/Al3Ti layer is 400 μm and the fiber diameter is 8 μm.