Core Structure Research Articles

Stiff, lightweight, and programmable architectured pyrolytic carbon lattices via modular assembling

Recent advances in additive manufacturing have enabled the creation of three-dimensional (3D) architectured pyrolytic carbon (PyC) structures with ultrahigh specific strength and energy absorption capabilities. However, their scalability is limited by reduced strength at larger sizes. Here we introduce a modular assembling approach to scale up PyC lattice structures while retaining strength. Three assembling mechanisms—adhesive, Lego-adhesive, and mechanical interlocking—are explored, demonstrating notably increased specific compressive strength and modulus as size increases, driven by energy release from assembly joint fractures. Practical application is demonstrated by using assembled PyC lattices as the core of an aerospace sandwich structure, significantly enhancing indentation resistance compared to conventional aramid paper honeycomb core. The method also enables versatile designs, including curved structures for space debris protection and bio-scaffold applications. This scalable approach offers a promising pathway for integrating PyC structures into large-scale engineering applications requiring superior mechanical properties and programmability in complicated shape design.

Scanning Electron Microscopic Study on the Connective Tissue Cores of the Lingual Epithelium of the Domestic Chicken (Gallus gallus Domesticus).

Anatomically the tongue of Gallus gallus domesticus (Galliformes: Phasianidae) is distinguished into sharp rostral apex, body and root with numerous conical papillae arranged in rows in different sizes in the free portion and the root of the tongue. The epithelium covered the dorsal and ventral surfaces of the free portion and the dorsal surface of the root of the tongue. Numerous orifices of the salivary glands were scattered in the root of the tongue. SEM investigation of the connective tissue cores after maceration of the tongue in 10% NaOH showed the presence of thread-like structures of the connective tissue cores in the rostral apex of the tongue, rod-shaped protrusions in the middle of the free portion and ring-like process posteriorly, while in the conical papillae, they appeared like thin parallel striations. The connective tissue core formed sheaths around the orifices of the salivary glands. While the connective tissue cores of the laryngeal area showed saw-shaped protrusions. Ventrally, the connective tissue core of the lingual nail was arranged in longitudinal parallel rows. SEM investigation revealed that the connective tissue core of the epithelium covered the tongue and closely conformed to the form and size of the filiform papillae.

Tight Control of SiGe Condensation Technique for Large Scale Fabrication of High Quality Thick S0.5G0.5oi Layer

The development of thick pseudo-substrate of SiGe usually involves a complex epitaxy of several microns thick gradual buffer layer. However, a drawback of this approach relies on high roughness of the top layer which implies the addition of subsequent planarization step. Furthermore, if the top part of the layer is relaxed and defect free, abundant dislocations are embedded several microns deep. They can expand during following thermal processes, possibly reaching the surface. Obviously, these defects are detrimental for electronic and photonic purposes. State of the art studies report dislocations density around 106 cm-2 for on a Si0.7Ge0.3 substrate[1].This study shows an alternative approach based on the combination of the SiGe condensation technique combined with a thick epitaxy (figure 1). We demonstrate, using 300mm industrial conditions, that a tight control of SiGe condensation parameters (initial SiGe thickness and composition) allows to improve the structural quality of the thin SGOI to reach ultimate reduction of dislocations. Subsequently, this thin SGOI is used as a pedestal above which is grown a thick layer of SiGe using a simple, constant-composition epitaxy. The slippery SiGe/BOX interface is expected to relax part of the stress, allowing the growth of high quality thick SGOI layer [2,3].First, a thin epitaxy of 25nm fully strained Si0.8Ge0.2 is deposited by RP-CVD on a 300mm SOI wafer. The precursors gases are Germane, Dichlorosilane and Hydrochloric. Afterwards, SiGe condensation is performed using optimized high-temperature slow oxidation to generate thin SGOI structures, with Ge concentration varying from 40 to 55% [4]. Thickness and composition are characterized by Spectroscopic Ellipsometry. AFM and TEM cross-section allow the analysis of crystalline quality of both surface and core of the SGOI structures. The resulting thin SGOI structures exhibit typical defects at the surface revealing in-depth dislocations (figure 2). The defects density is around 105 cm-2 until 50% Ge concentration. Above this concentration, defects density increases rapidly toward 1010 cm-2, in agreement with literature [4,5]. Therefore, the next step focuses on thin SGOI with a maximum Ge concentration of 50%.When reducing the initial SiGe thickness and Ge concentration, defect density of the thin SGOI is strongly improved (figure 3). It exhibits a crucial impact of the stress contained in the initial SiGe layer. Especially, strong influence of the initial Ge concentration is observed: for a 20nm thick initial SiGe layer, a 0.5% decrease of the Ge concentration avoids any defect formation at the surface and in depth of the thin S0.5G0.5OI (figure 4). Raman measurement is performed on a S0.45G0.45OI structure and exhibits 1.6% in-plain strain, showing the pseudo-morphic behavior of the SiGe layer. This study shows that a precise control of the initial SiGe thickness and content allows to fabricate a dislocation free thin S0.5G0.5OI structure.Taking advantage of the weak SiGe/BOX interface achieving possibly stress relaxation, this SGOI structure is a promising compliant pedestal to limit defects creation during the subsequent thick Si0.5Ge0.5 epitaxy. A preliminary trial is achieved: above the defect-free thin S0.5G0.5OI structure, a thick SiGe epitaxy is grown using a constant Ge concentration during all the process. Ge concentration profile along the radius of the wafer was precisely tuned to match the one of thin SGOI (figure 5). The result is promising: no defects are observed in the top part of the layer, allowing a very smooth top surface and no noticeable interface is detected between the two SiGe layers, generating a homogenous crystal (figure 6). However, many crystalline defects are detected at the bottom of the SiGe layer. Analyzing several images, a defect density of 10⁹ cm⁻² is calculated. Though, a close look at the SiGe/BOX interface reveals the presence of SiO2 clusters, from which almost all defects are starting from. These clusters could be due to a bad surface preparation prior to the thick SiGe epitaxy, leaving Si-O or Ge-O residues that could migrate to nucleate into SiO2 precipitates. When growing, these precipitates create a stress field, helping defects formation. A somewhat similar issue was observed in literature [6]. A more efficient surface preparation is under development to completely remove these SiO2 clusters and drastically improve the final defects density.[1] Hartmann et al., Semicond. Sci. Technol., vol. 19, no 3, p. 311-318, 2004[2] Boureau et al., ECS, 2018[3] Usuda, et al., Solid-State Electronics, 2013[4] Valenducq et al., EUROSOI-ULIS, 2019[5] Takagi et al., ECS Trans., 33 (6) 501-509 (2010)[6] Kim et al., Opt Express. 2013 Aug 26;21(17):19615-23 Figure 1

Heterogeneous marine environments diversify microbial-driven polymetallic nodule formation in the South China Sea

Most studies on the genesis of polymetallic nodules suggested that nodules in the South China Sea (SCS) are hydrogenetic; however, the complexity and the heterogeneity in hydrology and geochemistry of the SCS might cause different processes of nodule formation, impacting their application and economic value. Microbial-mediated ferromanganese deposition is an important process in nodule formation, but the related microbial potentials are still unclear in the SCS. In this study, we sampled in three typical regions (A, B, and C) of the SCS enriched with polymetallic nodules. Firstly, we investigated environmental and microbial characteristics of the water columns to determine the heterogeneity of upper seawater that directly influenced deep-sea environments. Then, microbial compositions and structures in sediment cores, overlying waters, and nodules (inside and outside) collected within the same region were analyzed for inferring features of nodule environments. Microbial interactions between nodules and surrounding environments were estimated with collinear network analysis. The microbial evidence indicated that geochemical characteristics in deep sea of the SCS that were key to the polymetallic nodule formation were severely affected by organic matter flux from upper water column. The sediment in region A was sub-oxic due to the large input of terrigenous and phytoplankton-derived organic matter, potentially enhancing the overflow of reduced metals from the porewater. The intense microbial interaction between nodules and surface sediment reinforced the origin of metals for the ferromanganese deposition from the sediment (diagenetic type). Contrarily, the sediments in regions B and C were relatively rich in oxygen, and metal ions could be majorly supplied from seawater (hydrogenetic type). The large discrepancy in microbial communities between nodule inside and remaining samples suggested that nodules experienced a long-term formation process, consistent with the feature of hydrogenetic nodules. Overall, distributions and interactions of microbial communities in nodules and surrounding environments significantly contributed to the nodule formation in the SCS by manipulating biogeochemical processes that eventually determined the source and the fate of metal ions.

Exploring delamination behavior in carbon nanofiber-reinforced sandwich structures with various corrugated cores: An experimental study on mixed-mode crack growth

In this paper, the delamination behavior between the face sheet and core of sandwich panels under a mixed mode of failure during TPSB (Three-Point Sandwich Beam) testing is investigated. The experiments were conducted on two sets of specimens: one reinforced with 0.25% carbon nanofiber weight and the other consisting of samples without carbon nanofibers. The core of the sandwich structures was made of PVC foam, and the corrugated cores and face sheets were made of glass-epoxy fibers. The investigated specimens had corrugated cores with different geometries, such as trapezoidal, square, and triangular. The Force-Displacement and R-CURVE diagrams of sandwich panels reinforced with and without carbon nanofibers were extracted. The strain energy release rate increased with increasing crack length, and this trend in the mixed mode of failure was generally upward. The strain energy release rate in the sandwich panel reinforced with carbon nanofibers with trapezoidal, square, and triangular corrugated cores increased by 20.7%, 39.8%, and 44.6%, respectively. These findings underscore the potential of carbon nanofiber-reinforced sandwich structures for diverse applications requiring enhanced fracture resistance under varying loading conditions. These structures have many applications in wind turbine blades and aerospace industry.

In Situ Molecular Reconfiguration of Pyrene Redox-Active Molecules for High-Performance Aqueous Organic Flow Batteries.

Aqueous organic flow batteries (AOFBs) hold great potential for large-scale energy storage, however, scalable, green, and economical synthetic methods for stable organic redox-active molecules (ORAMs) are still required for their practical applications. Herein, pyrene-based ORAMs are obtained via an in situ organic electrolysis strategy in a flow cell. It is revealed that the water attacking pyrenes restructured molecules to produce a variety of isomers and dimers during the electrolysis, which can be modulated by regulating the local electron cloud density and steric hindrance of pyrene precursors. As a result, the molecularly reconfigured pyrene-based catholytes, even without any further purification, achieved a high electrolyte utilization of ≈96% and volumetric capacity above 50AhL-1. Inspiringly, remarkable cell stability with almost no capacity decay for ≈70 days is achieved, benefiting from the robust aromatic structure of the pyrene cores. The insights into the in situ electrosynthesis of pyrene-based ORAMs provided in the work will provide guidance for designing ultra-stable ORAMs for AOFB applications.

Characterization of Industrial Carbon Emission Dynamics and Network Structure Evolution in China

Given that industry is the major source of carbon emissions, clarifying the carbon transfer regularity triggered by industry production linkage is of great importance in realizing the synergistic development of industry to reduce pollution and carbon emissions. Based on the perspective of responsibility allocation, the study accounted for the industry carbon emissions and constructed a carbon transfer weighted directed network model and applied the social network analysis method to explore the structure of the industry carbon transfer network and its evolution characteristics from 2005 to 2020. The results showed that： ① The overall carbon emissions of industries from 2005 to 2020 presented a rapid growth trend and large differences occurred in emissions between industries. ② The scale of the carbon transfer network was expanding rapidly and the characteristics of the small-world network were significant. ③ The community structure of the carbon transfer network was obvious, including four optimal associations： high carbon emission, carbon transmission, carbon endogenous, and high spillover. ④ The construction industry and the metal smelting and rolling processing industry were the core of the carbon transfer network structure, with strong network control. In view of the above characteristics, we proposed countermeasures and suggestions in terms of implementing the allocation of carbon emission reduction responsibilities and differentiated emission reduction measures for associations as well as focusing on the management of core nodes of the network, with the intent of providing cross-sectoral synergistic emission reduction ideas for the development of sustainable low-carbon transformation in China's industry sector.

Competing Phases of Iron at Earth's Core Conditions From Deep‐Learning‐Aided ab‐initio Simulations

AbstractThe properties and relative stability of different structures of iron at the extreme conditions of pressure and temperature of relevance for the Earth's core were determined with ab‐initio atomistic simulations aided by a machine‐learning force‐field. We find that the body‐centered cubic (bcc) structure is mechanically stable at core temperatures, but its free energy is marginally higher than those of the hexagonal close‐packed and face‐centered cubic structures. The bcc structure is the only structure whose shear sound velocity matches seismic data. The small free‐energy difference between competing structures suggests that the role of impurities could be crucial in stabilizing the bcc structure in the inner core.

RTG-GNN: A novel rock topology-guided approach for permeability prediction using graph neural networks

Digital core permeability is a crucial factor in rock engineering, reservoir simulation, and underground applications, serving as the foundation for evaluating fluid flow underground. However, predicting digital core permeability using artificial intelligence presents challenges such as high model calculation complexity, strong resource dependence, and low efficiency. To overcome these challenges, this paper presents a novel hybrid enhanced rock topology-guided graph neural network (RTG-GNN) to accurately characterize the pore structure of digital cores and predict permeability. This model takes advantage of the physical attributes of pores and throats, utilizing them as features for nodes and edges. It improves information exchange through a gating mechanism and incorporates an attention mechanism for weighted aggregation of neighboring data, culminating in accurate permeability predictions. Furthermore, a scheme for constructing a comprehensive permeability distribution dataset (CPDD) is proposed for digital cores. This scheme effectively mitigates challenges like inadequate training data, subjective sampling bias, and data drift. Multiple experimental results demonstrate that RTG-GNN surpasses most methods in various performance indicators. Additionally, the RTG-GNN model boasts a lightweight design, occupying only 17% to 44% of the size of mainstream models and requiring just 15% to 38% of GPU resources for training. Remarkably, while maintaining high accuracy and low error rates, the computational load is reduced by a factor ranging from 19.06 to 636.41, the training speed is enhanced by 12.12 to 86.47 times, and the inference speed is increased by 6.76 to 16.14 times. The experiment further confirms that both single core and mixed rock datasets, acquired through the CPDD scheme, exhibit excellent generalization and reliability.

A Review on Synthetic Thiazole Derivatives as an Antimalarial Agent.

Thiazole is a widely studied core structure in heterocyclic chemistry and has proven to be a valuable scaffold in medicinal chemistry. The presence of thiazole in both naturally occurring and synthetic pharmacologically active compounds demonstrates the adaptability of these derivatives. The current study attempted to review and compile the contributions of numerous researchers over the last 20 years to the medicinal importance of these scaffolds, with a primary focus on antimalarial activity. The review is based on an extensive search of PubMed, Google Scholar, Elsevier, and other renowned journal sites for a thorough literature survey involving various research and review articles. A comprehensive review of the antimalarial activity of the thiazole scaffold revealed potential therapeutic targets in Plasmodium species. Furthermore, the correlation of structure-activity-relationship (SAR) studies from various articles suggests that the thiazole ring has therapeutic potential. This article intends to point researchers in the right direction for developing potential thiazole-based compounds as antimalarial agents in the future.

First-principles calculations on dislocations in MgO

ABSTRACT While ceramic materials are widely used in our society, their understanding of the plasticity is not fully understood. MgO is one of the prototypical ceramics, extensively investigated experimentally and theoretically. However, there is still controversy over whether edge or screw dislocations glide more easily. In this study, we directly model the atomic structures of the dislocation cores in MgO based on the first-principles calculations and estimate the Peierls stresses. Our results reveal that the screw dislocation on the primary slip system exhibits a smaller Peierls stress than the edge dislocation. The tendency is not consistent with metals, but rather with TiN, suggesting a characteristic inherent to rock-salt type materials.

Permeability prediction method of unconsolidated sandstone reservoirs using CT scanning technology and random forest model

Developing unconsolidated sandstone reservoirs presents a formidable challenge due to their loose formation, which often triggers alterations in pore parameters and seepage characteristics during water injection processes. This study focuses on a specific reservoir, utilizing micro-CT scanning to examine the intricate relationship between permeability and pore throat structure. Leveraging a random forest model, we establish an empirical formula tailored for high permeability reservoirs. Furthermore, we conduct in-situ CT scanning experiments across various displacement multiples to analyze the pore structure of unconsolidated sandstone cores. The derived relationship curves elucidate the positive correlations between porosity and average pore throat radius with displacement multiples, while revealing a negative correlation with tortuosity. These findings enable the formulation of quantitative formulas for permeability and displacement multiples within the studied block. Such insights prove instrumental in devising effective water injection development strategies, predicting dynamic reserves, and projecting water drive development for analogous unconsolidated sandstone reservoirs undergoing high water cut phases.

Multi-objective optimization design of NPR protection shell for hydrogen storage tank

In order to improve the safety of on-board hydrogen storage tanks during collision, a protective shell based on a negative Poisson’s ratio (NPR) core is designed in this paper. After analyzing and comparing the crashworthiness of three typical honeycomb structures, the concave hexagonal negative Poisson’s ratio honeycomb is selected as the energy-absorbing inner core of the hydrogen storage tank protection structure. The sensitivity analysis of the structural parameters of the NPR shell is conducted through orthogonal tests to identify parameters with a significant impact on crash performance. These parameters are then used as experimental variables for subsequent optimization design. Subsequently, a response surface approximation model between the optimization objective and the structural parameters is established based on the response surface method. Finally, the adaptive simulated annealing algorithm (ASA), neighborhood cultivation genetic algorithm (NCGA), and non-dominated sorting genetic algorithm-II (NSGA-II) are used to optimize the structural parameters, and the optimization results are verified by the whole-vehicle crash simulation. The simulation results demonstrate that all three algorithms achieve better optimization results, among which NCGA is more advantageous in improving the overall performance of the protective shell. After NCGA optimization, the specific energy absorption of the protective shell increases by 19.75%, the maximum collision force of the rigid wall decreases by 23.63%, and the maximum stress of the hydrogen storage tank body decreases by 22.77%. These findings indicate that the designed protection shell effectively improves the crashworthiness of the hydrogen storage tank during collisions.

Synthesis and Characterization of New Chiral Smectic Four-Ring Esters.

Orthoconic antiferroelectric liquid crystals (OAFLCs) represent unique self-organized materials with significant potential for applications in photonic devices due to their sub-microsecond switching times and high optical contrast in electro-optical effects. However, almost all known OALFCs suffer from low chemical stability and short helical pitch values. This paper presents the synthesis and study results of two chiral AFLCs, featuring a four-ring structure in the rigid core and high chemical stability. The mesomorphic properties of these compounds were investigated using polarizing optical microscopy and differential scanning calorimetry. Spectrometry and electro-optical studies were employed to estimate the helical pitch, tilt angle, and spontaneous polarization of the synthesized compounds and the prepared mixtures. All studied compounds exhibit enantiotropic chiral smectic mesophases including the SmA*, the SmC*, and a very broad temperature range of the SmCA* phase. Doping top-modern antiferroelectric mixture with synthesized compounds offers benefits such as increased helical pitch and tilt angle values without significantly influencing spontaneous polarization. This allows the prepared mixture to be regarded as an OAFLC with high optical contrast, characterized by an almost perfect dark state. These valuable physicochemical and optical properties suggest significant potential of studied materials for practical applications.

Sustainable Jute Fiber Sandwich Composites with Hybridization of Short Fiber and Woven Fabric Structures in Core and Skin Layers

AbstractSustainable hybrid composites, made of two different natural plant fiber types, are increasingly being attracted by composite researchers, for their cost effectiveness and ability to control mechanical performances through varying weight ratios of different fibers. In contrast, their lower mechanical properties are reported in the literature, because of strength variations of different fiber types and an improper fiber‐matrix stress distribution. Therefore, it is aimed to develop sustainable hybrid composites from two dry fiber preforms—woven fabric and short fiber preform—originated from same fiber type (jute). A highly packed short fiber preform is used as the core layer, while woven fabrics (plain/twill–rib/twill–diamond) are used in the skin layers for producing sandwiched hybrid jute composites. Mechanical tests and scanning electron microscopy images show that hybridized plain fabric/short fiber preform composites have better mechanical properties (≈58 MPa tensile strength/≈117 MPa flexural strength/≈112.12 kJm−2 impact strength with an ≈487.4% improvement) compared to other fabric structures hybrid/nonhybrid composites. This enhancement is related to the interlocking of short fibers with long plain fabric leading to a strong fiber‐matrix interfacial bonding. Thus, this developed hybrid composites, can be applied in many semi‐structural applications, wherein composites’ low cost and mechanical performances are primary concerns.

Планирование эксперимента на модели медицинской организации, реализующей региональный проект «Борьба с сердечно-сосудистыми заболеваниями» для нахождения элемента оптимального прототипа.

Prevention of cardiovascular diseases and complications in high-risk patients is the most important component of the federal project “Combating Cardiovascular Diseases”, aimed at achieving the goals and results of its implementation. The purpose was the identification of factors influencing the processes of the regional project “Fighting Cardiovascular Diseases” (object of research), to find and optimize elements of a prototype model of a medical organization, using experimental planning methods. Materials and methods. The research methods were experimental planning and process modeling to select the number and conditions for setting up the experiment necessary to solve a specific problem with the required accuracy for decision making. Planning the experiment is aimed at trying to construct an optimal model of a medical organization to implement the strategic goals of the federal project. Results. The object of the study was the processes implemented by medical organizations within the framework of the federal project “Combating Cardiovascular Diseases”, which is part of the national project “Healthcare”. The author has identified constant and variable factors influencing the actual model of the medical organization implementing the project to find an element of the optimal prototype within the framework of the experiment planning processes. From the numerous ranges of available factors of influence (processes of “entrance”) on the object of research, organizational processes in the operational core of the organizational structure of the management of a medical organization have become key elements of the study. Finding the maximum optimistic, pessimistic and probable calculated indicators of the load on medical specialists (the “exit” processes) became the criteria (responses) for determining and selecting the optimal time for organizing processes in the management apparatus of the operational core of a medical organization. Conclusion. By optimizing one element of the model of a medical organization implementing a project, it is impossible to fully optimize the prototype, given the multi-level nature of the healthcare system and the complexity of interconnected elements. As part of the study of the research question, it is planned to continue the search for elements of the optimal prototype. Consecutive execution of iterations with different values of the optimization parameters of the elements and finding the optimal values of the prototype will allow achieving the value of the given objective function with the least loss of resources.

Effect of corona discharge cold plasma on the structure and emulsification properties of soybean protein isolate

As a non-thermal treatment technology, cold plasma (CP) is widely used in food macromolecule modification, sterilization, etc. However, the effect of different CP source treatments on protein structure has yet to be elucidated. This research studied the effects of corona discharge CP treatment at different voltages and treatment times on the structure, physicochemical properties and emulsion properties of soybean protein isolate (SPI). When the CP was treated at 14 kV for 90 min, the SPI structure was disordered and unfolded, leading to increased surface hydrophobicity and sulfhydryl contents. The solubility of SPI increased by 31.75 ± 1.41%. When the voltage was increased to 18 kV, the content of α-helix and β-sheet structures of SPI increased, indicating the formation of protein aggregates. In this case, the average particle size of SPI increases and the intermolecular electrostatic repulsion decreases. The results show that moderate corona discharge CP treatment can enhance the binding ability of protein particles to oil droplets by unfolding the SPI structure and exposing hydrophobic groups in the hydrophobic core of the protein structure. Simultaneously, the accumulation of negatively charged products on the protein surface hinders the flocculation and coalescence of droplets. Collectively, this study provides a new understanding of the effects of different CP treatments on SPI structure and O/W emulsion properties.

Microbial mat-induced microfacies in clastic deposits – An overview

Abstract This contribution reviews microbial microfacies recognisable in vertical sections through modern or fossil mat-overgrown sediment. Microfacies are products of endobenthic or epibenthic microbial mats interacting with sediment dynamics. Laminae of such mats form during sediment dynamic quiescence by organisation of filaments to an interwoven mat fabrics (binding), and biomass enrichment (growth) by cell replication and the production of extracellular polymeric substances (EPS). Vertical sections through mat-covered sediment may show buried stacks of subrecent mat laminae (biolaminites) that rose from alternating periods of mat development and sediment deposition. Mat laminae that drape ripple marks are visible as sinoidal structures in sediment core or sections. If the sediment-stabilising properties of a microbial mat is overcome by currents or waves of high strengths, cm-size mat fragments (mat chips and roll-ups) are ripped off and redeposited. Intrasedimenary gases, trapped beneath mat layers, may cause a high secondary porosity (sponge pore sand) in the sandy substrates. The internal build-up (microfabrics) of mat laminae is investigated under high magnification. Endobenthic microbial mat fabrics include filamentous and coccoid cells forming a network, EPS, and sedimentary grains. The grains derived from interaction of the endobenthic mats with bed load. Epibenthic microbial mat fabrics may include also silt-size particles syndepositionally enriched by baffling and trapping of suspension load. The fabrics of these mats commonly also include oriented sedimentary grains. These grains (now aligned bedding parallel) were dragged upward from the substrate during the development and growth of the mat. Overall, microbial microfacies provide insight into the sedimentation pattern of the (paleo-)environment and into the types of the substrate-colonising microbial mats.

КОНЦЕПТУАЛЬНИЙ ПІДХІД ДО ВИЯВЛЕННЯ DEEPFAKE МОДИФІКАЦІЙ БІОМЕТРИЧНОГО ЗОБРАЖЕННЯ ЗАСОБАМИ НЕЙРОННИХ МЕРЕЖ

The National Cybersecurity Cluster of Ukraine is functionally oriented towards building systems to protect various platforms of information infrastructure including the creation of secure technologies for detecting deepfake modifications of biometric images based on neural networks in cyberspace. This space proposes a conceptual approach to detecting deepfake modifications which is deployed based on the functioning of a convolutional neural network and the classifier algorithm for biometric images structured as 'sensitivity-Yuden index-optimal threshold-specificity'. An analytical security structure for neural network information technologies is presented based on a multi-level model of 'resources-systems-processes-networks-management' according to the concept of 'object-threat-defense'. The core of the IT security structure is the integrity of the neural network system for detecting deepfake modifications of biometric face images as well as data analysis systems implementing the information process of 'video file segmentation into frames-feature detection processing - classifier image accuracy assessment'. A constructive algorithm for detecting deepfake modifications of biometric images has been developed: splitting the video file of biometric images into frames - recognition by the detector - reproduction of normalized facial images - processing by neural network tools - feature matrix computation - image classifier construction. Keywords: biometric image deepfake modifications neural network technology convolutional neural network classification decision support system conceptual approach analytical security structure.

Broadening of the carbon window and the appearance of core-rim carbides in WC-Fe/Ni cemented carbides

Among several separate challenges, the major one for replacing cobalt in cemented carbides is the difficulty to obtain alternative binder materials with a C-window broad enough to be robustly processed under conventional industrial control on the C content. The C-window is defined as the C content range for which phases that are detrimental to the mechanical properties are avoided. The present paper has two main objectives: first, to show that the processing C-window of Fe-Ni based systems is in fact wider than what thermodynamic equilibrium calculations predict, and that its width can be controlled moderately by tweaking the initial WC grain size and the cooling rate used in the material’s processing. Secondly, in case those detrimental phases are not avoided, this work gives insight on how to make their appearance less detrimental for the mechanical properties. The morphology, volume fraction and particle size distribution of the detrimental phases, specifically η6-carbides at low C contents, are investigated to explore desirable combination of hardness and toughness of alternative binder cemented carbides. During this study it was also discovered that in samples with carbon contents below the low-C limit of the C window a carbide with hexagonal lattice known as κ, not commonly seen in cemented carbides, appeared and formed the core of a core-rim structure together with the more common η6-phase. It is believed that the κ-carbide form due to local high concentrations of tungsten during solid state sintering and that it has an impact on the precipitation characteristics of the η6-phase.