Lining Layer Research Articles

Helical Indexing in Real Space

Biological structures with helical symmetries of distinct twist, rise, and axial symmetry are abundant and span a wide range of organisms and functions. Performing de novo helical indexing remains challenging because of the steep learning curve involved in Fourier space layer lines. The unknown amount of out-of-plane tilt and the existence of multiple conformations of the helices further complicate indexing. In this work, we introduce a real-space indexing method that leverages the prior knowledge of the tilt and in-plane angles of the helical filaments/tubes, robust ab initio 3D reconstruction capabilities in single particle cryo-EM to obtain asymmetric reconstructions, and automatic indexing of helical parameters directly from the asymmetric density maps. We validated this approach using data from multiple helical structures of distinct helical symmetries, diameters, flexibility, data qualities, and heterogeneous states. The fully automated tool we introduce for real space indexing, HI3D, uses the 2D lattice in the autocorrelation of the cylindrical projection of a 3D density map to identify the helical symmetry. HI3D can often successfully determine the helical parameters of a suboptimal 3D density map, including ab initio single particle asymmetric reconstructions and sub-tomogram averages, with intermediate evidence that can also help assess the map quality. Furthermore, this open-source HI3D is usable independently as a Web application that can be accessed free of installation. With these methods, de novo helical indexing will be significantly more accessible to researchers investigating structures of helical filaments/tubes using cryo-EM.

Effect of dietary energy concentration on the growth of slow-growing Korat chickens from 43 to 84 days old

The aim of this study was to estimate the effect of diets with different energy levels on the growth performance of slow-growing chickens (so-called Korat chicken (KRC)). The KRC is a cross between a male Thai native chicken (Leung Hang Khoa) and females from crosses among modern broiler and layer lines. The study was divided into two experimental periods when the birds were from 43 to 63 days old and 64 to 84 days old. Birds received feed and water ad libitum throughout the trial. In this study, 1200 mixed-sex KRC(624 and 576 chicks in phases 1 and 2, respectively) were distributed equally to four diets, which provided 2750, 2900, 3050 and 3200 kcal ME/kg. There were six replicate pens of each treatment. At both ages,increased energy content of the diet resulted in decreased feed intake (FI) and thus improved the feed conversion ratio (FCR). Weight gain was unaffected by the treatments. Using a broken-line analysis, dietary energy containing about 3200 kcal ME/kg was found to have the most beneficial effect on FCR during both periods. Thus, the optimal ME for KRC between 43 and 84 days old was 3200 kcal/kg.

Bone quality and composition are influenced by egg production, layer line, and oestradiol-17ß in laying hens

ABSTRACT Keel bone fractures are a serious animal welfare problem in laying hens. The aim of the current study was to assess the influence of egg production, oestradiol-17ß, and selection for high laying performance on bone quality. Hens of two layer lines differing in laying performance (WLA: 320 eggs per year, G11: 200 eggs per year) were allocated to four treatment groups. Group S received a deslorelin acetate implant that suppressed egg production. Group E received an implant with the sexual steroid oestradiol-17ß. Group SE received both implants and group C did not receive any implant. In the 63rd week of age, composition and characteristics of the tibiotarsi were assessed using histological analysis, three-point bending test, thermogravimetric analysis, infrared spectroscopy, and two-dimensional X-ray diffraction, respectively. Non-egg-laying hens showed a higher total bone area and a higher relative amount of cortical bone compared to egg-laying hens. Hens of layer line G11 showed a higher relative amount of medullary bone and a higher degree of mineralization of the cortical bone compared to hens of layer line WLA. These differences in bone composition may explain different susceptibility to keel bone fractures in non-egg-laying compared to egg-laying hens as well as in hens of layer lines differing in laying performance. The effect of exogenous oestradiol-17ß on bone parameters varied between the layer lines indicating a genetic influence on bone physiology and the way it can be modulated by hormone substitution.

Dual-polarized elliptic-H slot-coupled patch antenna for 5G applications

A dual-polarized, slot-coupled dielectric patch antenna design is presented in sub-6 GHz for 5G base stations. Proposed antenna is implemented using two dielectric patch layers (main patch and parasitic patch) above a feeding line layer. Excitation is realized by crossed elliptic-H slots in order to create orthogonal ± 45$^{\circ}$ polarizations. Through the use of patches at proper heights together with elliptic-H slots, significant improvement in impedance bandwidth, matching level, isolation and front-to-back ratio is acquired. Prototype antenna has an impedance bandwidth of 18.5\% (3.23--3.85 GHz) for $ S_{11} $, $ S_{22} $ $

The ultrastructural heterogeneity of lung surfactant revealed by serial section electron tomography: insights into the 3-D architecture of human tubular myelin.

Weibel's hypothetical three-dimensional (3-D) model in 1966 provided first ultrastructural details into tubular myelin (TM), a unique, complex surfactant subtype found in the hypophase of the alveolar lining layer. Although initial descriptions by electron microscopy (EM) were already published in the 1950s, a uniform morphological differentiation from other intra-alveolar surfactant subtypes is still missing and potential structure-function relationships remain enigmatic. Technical developments in volume EM methods now allow a more detailed reinvestigation, to address unanswered ultrastructural questions, we analyzed ultrathin sections of humanized SP-A1/SP-A2 coexpressing mouse and human lung samples by conventional transmission EM. We combined these two-dimensional (2-D) information with 3-D analysis of single- and dual-axis electron tomography of serial sections for high z-resolution (in a range of a few nanometers) and extended volumes of up to 1 µm total z-information, this study reveals that TM constitutes a heterogeneous surfactant organization mainly comprised of distorted parallel membrane planes with local intersections, which are distributed all over the TM substructure. These intersecting membrane planes form, among other various polygons, the well-known 2-D "lattice", respectively 3-D quadratic tubules, which in many analyzed spots of human alveoli appear to be less abundant than also observed nonconcentric 3-D lamellae, the additional application of serial section electron tomography to conventional transmission EM demonstrates a high heterogeneity of TM membrane networks, which indicates dynamic transformations between its substructures. Our method provides an ideal basis for further in and ex vivo structural analyses of surfactant under various conditions at nanometer scale.

The internal temperature field of shotcrete in high geothermal tunnel and its effect on microstructures and mechanical properties

Geothermal tunnel creates one-dimensional heat conduction field which may have an uneven effect on the hydration, microstructures, and mechanical properties of shotcrete for the first lining layer. In this study, the evolution of the internal temperature gradient of shotcrete specimens subjected to the simulated geothermal environment was measured, and its effects on the heterogeneous distribution of internal microstructures, hydration products, and mechanical properties were characterized. Results showed that there was an obvious temperature gradient in the shotcrete exposed to the geothermal environment, which dramatically changes within 24 h of contact and then remains stable afterward. For the properties of shotcrete at an early age (within 24 h), the compressive and flexural strength of specimens exposed to a geothermal environment is significantly higher than that of specimens cured in standard conditions, due to the accelerating effect on hydration by the elevated temperature. The phase assemblage, hydration degree, and mechanical property in the specimens at an early age show a gradient distribution, and more hydration degree and lower porosity were formed in the internal regions with a higher temperature, resulting in a higher compressive and flexural strength.

APPLICATION OF HFACS-HFIX FRAMEWORK IN NTSC’S FINDINGS AND RECOMMENDATIONS: WAMENA AIR ACCIDENTS’ CASE STUDY

Wamena airport experienced accidents in 2002, 2008, 2009, 2013, 2015, and 2016. All accidents were cargo flights and in approach and landing flight phases. As the Swiss Cheese concept, accident happened when errors penetrated safety defenses’ layers in straight line. Structuring NTSC’s investigations, under HFACS framework to understand the human factor failures type and HFIX strategy to close the failures by applying the recommendations, need to be done in air accident investigation. Eleven aviation experts and practitioners were interviewed in this study, to validate the framework. There were layers without any failures in accident 2008, 2013, and 2016. Accident in 2016 has no recommendation due operators’ safety actions were considered relevant to block failures. Accidents in 2002, 2009, 2013, and 2015 have failure in a layer which intervened by two or more recommendations. There were failures remain open in accident 2002, 2009, 2013, and 2016. Repetitive failure, error or violation of repetitive accidents in 2002, 2009, 2013, 2015, and 2016 is un-stabilized approach and has not been blocked with effective interventions. HFACS and HFIX are useful to framework the accident investigation, preventing similar accident happened in the future.

Revisit the Development of Native Indonesian Chickens from Red Jungle Fowls (Gallus gallus bankiva) to Commercial Chickens

Kampung chicken which is one of native Indonesian chickens has been domesticated from the ancestor of Red Fowl Jungle, and developed by the village community from generation to generation through an extensive rearing method. Before the intensive management of kampung chicken was introduced, the chickens were allowed to scavange around the household yard during the day, they slept in the trees, on the roofs or underneath of the household at night. It has been for many years that kampung chickens were crossed with imported exotic breeds, and unplanned selection. As a result, kampung chickens have developed to a considerable high phenotype and genetic varieties with several different names and purposes. There have been selection programs, which have resulted a considerable strain of improved egg type of Kampung chicken (KUB-1 chicken), and a strain of broiler type of local chicken (Sensi-1 Agrinak chicken and Gaoksi chicken). KUB-1 chickens can be used as female lines, and Sensi-Agrinak and Gaoksi chickens can be used as male lines to produce local commercial broilers. The article is to provide information on the domestication process of Red Jungle Fowl chickens into Kampung chickens and their development to become layer and broiler line chickens.

Circ_0088036 facilitates the proliferation and inflammation and inhibits the apoptosis of fibroblast-like synoviocytes through targeting miR-326/FZD4 axis in rheumatoid arthritis

Background The function and pathological significance of circular RNAs (circRNAs) in autoimmune diseases, such as rheumatoid arthritis (RA), are barely known. Here, we explored the role of circ_0088036 in RA progression and its associated mechanism. Methods The synovial lining layer tissues of RA patients and non-RA control patients were collected for clinical study in vivo, and tumour necrosis factor α (TNF-α)-induced RA-fibroblast-like synoviocytes (RA-FLSs) were used for the experiments in vitro. Cell proliferation was assessed by Cell Counting Kit 8 (CCK8) assay and flow cytometry. Cell apoptosis was analyzed by flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was conducted to analyze the release of pro-inflammatory cytokines. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the target interaction between microRNA-326 (miR-326) and circ_0088036 or frizzled class receptor 4 (FZD4). Results Circ_0088036 expression was elevated in the synovial lining layer tissues of RA patients and TNF-α-treated RA-FLSs. Circ_0088036 interference largely reversed TNF-α-induced proliferation and inflammation in RA-FLSs. The interaction between circ_0088036 and miR-326 was verified, and miR-326 silencing largely reversed circ_0088036 knockdown-mediated effects in TNF-α-treated RA-FLSs. MiR-326 bound to the 3’ untranslated region (3’UTR) of FZD4 in RA-FLSs. FZD4 overexpression largely diminished miR-326 accumulation-mediated influences in TNF-α-treated RA-FLSs. Circ_0088036 could up-regulate FZD4 by sponging miR-326 in RA-FLSs. Conclusion Circ_0088036 contributed to TNF-α-induced RA progression partly by targeting miR-326/FZD4 signalling.

Divergent selection for natural antibodies in poultry in the presence of a major gene

BackgroundNatural antibodies (NAb) are antibodies that are present in a healthy individual without requiring previous exposure to an exogenous antigen. Selection for high NAb levels might contribute to improved general disease resistance. Our aim was to analyse the genetic background of NAb based on a divergent selection experiment in poultry, and in particular the effect of a polymorphism in the TLR1A gene.MethodsThe study population consisted of a base population from a commercial pure-bred elite white leghorn layer line and seven generations of birds from a High and Low selection line. Birds were selected for total KLH-binding NAb titer (IgTotal). An enzyme-linked immunosorbent assay was performed to determine NAb titers in blood plasma for IgTotal and the antibody isotypes IgM and IgG. NAb titers were available for 10,878 birds. Genotypes for a polymorphism in TLR1A were determined for chickens in generations 5, 6 and 7. The data were analysed using mixed linear animal models.ResultsThe heritability estimate for IgM was 0.30 and higher than that for IgG and IgTotal (0.12). Maternal environmental effects explained 2 to 3% of the phenotypic variation in NAb. Selection for IgTotal resulted in a genetic difference between the High and Low line of 2.4 titer points (5.1 genetic standard deviation) in generation 7. For IgM, the selection response was asymmetrical and higher in the Low than the High line. The frequency of the TLR1A C allele was 0.45 in the base population and 0.66 and 0.04 in generation 7 of the High and Low line, respectively. The TLR1A polymorphism had large and significant effects on IgTotal and IgM. Estimated genotypic effects suggest full dominance of the TLR1A C allele. Significant TLR1A by generation interactions were detected for IgM and IgTotal.ConclusionsThe effect of a polymorphism in the TLR1A gene on IgTotal and IgM NAb was confirmed. Furthermore, we provide experimental verification of changes in allele frequencies at a major gene with dominant gene action on a quantitative trait that is subjected to mass selection. TLR1A by generation interactions indicate sensitivity to environmental factors.

Metabolic reprogramming of synovial fibroblasts in osteoarthritis by inhibition of pathologically overexpressed pyruvate dehydrogenase kinases

Osteoarthritis (OA) is the most common degenerative joint disease and a major cause of age-related disability worldwide, mainly due to pain, the disease's main symptom. Although OA was initially classified as a non-inflammatory joint disease, recent attention has been drawn to the importance of synovitis and fibroblast-like synoviocytes (FLS) in the pathogenesis of OA. FLS can be divided into two major populations: thymus cell antigen 1 (THY1)- FLS are currently classified as quiescent cells and assumed to destroy bone and cartilage, whereas THY1+ FLS are invasively proliferative cells that drive synovitis. Both THY1- and THY1+ FLS share many characteristics with fibroblast-like progenitors – mesenchymal stromal cells (MSC). However, it remains unclear whether synovitis-induced metabolic changes exist in FLS from OA patients and whether metabolic differences may provide a mechanistic basis for the identification of approaches to precisely convert the pathologically proliferative synovitis-driven FLS phenotype into a healthy one. To identify novel pathological mechanisms of the perpetuation and manifestation of OA, we analyzed metabolic, proteomic, and functional characteristics of THY1+ FLS from patients with OA. Proteome data and pathway analysis revealed that an elevated expression of pyruvate dehydrogenase kinase (PDK) 3 was characteristic of proliferative THY1+ FLS from patients with OA. These FLS also had the highest podoplanin (PDPN) expression and localized to the sublining but also the lining layer in OA synovium in contrast to the synovium of ligament trauma patients. Inhibition of PDKs reprogrammed metabolism from glycolysis towards oxidative phosphorylation and reduced FLS proliferation and inflammatory cytokine secretion. This study provides new mechanistic insights into the importance of FLS metabolism in the pathogenesis of OA. Given the selective overexpression of PDK3 in OA synovium and its restricted distribution in synovial tissue from ligament trauma patients and MSC, PDKs may represent attractive selective metabolic targets for OA treatment. Moreover, targeting PDKs does not affect cells in a homeostatic, oxidative state. Our data provide an evidence-based rationale for the idea that inhibition of PDKs could restore the healthy THY1+ FLS phenotype. This approach may mitigate the progression of OA and thereby fundamentally change the clinical management of OA from the treatment of symptoms to addressing causes.

Weakening and Poleward Shifting of the North Pacific Subtropical Fronts from 1980 to 2018

Abstract Recent evidence shows that the North Pacific subtropical gyre and the Kuroshio Extension (KE) and Oyashio Extension (OE) fronts have moved poleward in the past few decades. However, changes of the North Pacific Subtropical Fronts (STFs), anchored by the North Pacific subtropical countercurrent in the southern subtropical gyre, remain to be quantified. By synthesizing observations, reanalysis, and eddy-resolving ocean hindcasts, we show that the STFs, especially their eastern part, weakened (20% ± 5%) and moved poleward (1.6° ± 0.4°) from 1980 to 2018. Changes of the STFs are modified by mode waters to the north. We find that the central mode water (CMW) (180°–160°W) shows most significant weakening (18% ± 7%) and poleward shifting (2.4° ± 0.9°) trends, while the eastern part of the subtropical mode water (STMW) (160°E–180°) has similar but moderate changes (10% ± 8%; 0.9° ± 0.4°). Trends of the western part of the STMW (140°–160°E) are not evident. The weakening and poleward shifting of mode waters and STFs are enhanced to the east and are mainly associated with changes of the northern deep mixed layers and outcrop lines—which have a growing northward shift as they elongate to the east. The eastern deep mixed layer shows the largest shallowing trend, where the subduction rate also decreases the most. The mixed layer and outcrop line changes are strongly coupled with the northward migration of the North Pacific subtropical gyre and the KE/OE jets as a result of the poleward expanded Hadley cell, indicating that the KE/OE fronts, mode waters, and STFs change as a whole system.

Mechanical loading mitigates osteoarthritis symptoms by regulating the inflammatory microenvironment in a mouse model.

Osteoarthritis (OA) is one of the most common chronic diseases, in which inflammatory responses in the articular cavity induce chondrocyte apoptosis and cartilage degeneration. While mechanical loading is reported to mitigate synovial inflammation, the mechanism and pathways for the loading-driven improvement of OA symptoms remain unclear. In this study, we evaluated the loading effects on M1/M2 polarization of synovial macrophages via performing histology, cytology, and molecular analyses. In the OA group, the cell layer of the synovial lining was enlarged with an increase in cell density. Also, M1 macrophages were polarized and proinflammatory cytokines were increased. In contrast, in the OA group with mechanical loading, cartilage degradation was reduced and synovial inflammation was alleviated. Notably, the M1 macrophages were diminished by mechanical loading, while M2 macrophages were increased. Furthermore, mechanical loading decreased the levels of proinflammatory cytokines, such as interleukin-1 beta and tumor necrosis factor-α, and suppressed PI3K/AKT/NF-κB signaling. Taken together, this study demonstrates that mechanical loading changes the ratio of M1 and M2 macrophages via regulation of PI3K/AKT/NF-κB signaling and provides cartilage protection in the mouse OA model.

Gasdermin-E Mediated Pyroptosis-A Novel Mechanism Regulating Migration, Invasion and Release of Inflammatory Cytokines in Rheumatoid Arthritis Fibroblast-like Synoviocytes.

Synovium fibroblast-like synoviocytes (FLSs) are important participants in the pathogenesis of synovitis and joint destruction in rheumatoid arthritis (RA). Pyroptosis is a pro-inflammatory and cell lytic programmed cell death mechanism mediated by gasdermin (GSDM) family proteins. In this study, we demonstrated the increased expression of GSDME and increased levels of GSDME-mediated pyroptosis in RA synovial tissues. In vitro, stimulation with TNF-α plus hypoxia mimicking the inflammatory and hypoxic environment in RA synovium induced GSDME-mediated pyroptosis in RA-FLSs in combination with the promotion of migration and invasion abilities and the release of inflammatory cytokines (IL-6, IL-8). Moreover, knockdown of GSDME significantly inhibited the proliferation rate, migration/invasion effects and cytokines released through the reduction of GSDME-mediated pyroptosis. The immunohistochemistry results showed that RA patients with high GSDME N-terminal (GSDME-NT) expression, which is the active form of GSDME, showed higher IL-6 expression in both lining and sublining layer of synovium than that in patients with low GSDME-NT expression, osteoarthritis and non-inflammatory orthopedic arthropathies. Our findings revealed a novel mechanism regulating cell proliferation, migration, invasion and inflammatory cytokines release during the process of GSDME mediated pyroptosis in RA.

Mild inflammation persists in the glenohumeral joint of patients with shoulder instability: Cross-sectional study

ObjectiveApproximately two-thirds of patients with history of shoulder dislocation may develop osteoarthritis (OA) of the glenohumeral joint. However, the biochemical mechanisms underlying the association between dislocation and OA are largely unknown. This study aimed to investigate macrophage markers and inflammatory cytokine expression associated with shoulder instability (SI) in comparison to rotator cuff tears (RCTs). DesignThis study included 30 patients with SI and 30 patients with RCTs. Synovial membrane samples were harvested from the rotator interval during the arthroscopic anatomical repair for both groups. The localization of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and cluster of differentiation (CD) 68 in synovial membranes was determined by immunohistochemistry. Transcript-level expressions of the inflammatory cytokines (TNFA and IL1B) and macrophage markers pan-CD68 and -M1 (CD80 and CD86) were quantified. CD80 and CD86 expression in macrophages from the SI group was confirmed using flow cytometry. ResultsTNF-α, IL-1β, and CD68 were expressed in the synovial lining layer of the synovial tissue in both groups. In addition, the mRNA expressions of TNFA, IL1B, CD68, and CD80 were significantly higher in the SI group compared to the RCT group (P ​= ​0.012, 0.014, 0.022, 0.003, respectively). In samples from the SI group, 96.3% of CD68+/CD14+ macrophages were CD86-positive, whereas 2.5% of CD68+/CD14+/CD86+ cells were CD80-positive. ConclusionsPatients with SI had higher mRNA levels of TNFA, IL1B, CD68, and CD80 than those with RCTs. These findings may partially explain the biochemical mechanism underlying the frequent development and progression of osteoarthritis in patients with SI.

An Endpoint Detection System for Ion Beam Etching Using Optical Emission Spectroscopy

An ion beam etching system with etching endpoint detection (EPD) capability based on optical emission spectroscopy (OES) was conceived, built, and tested. An expansion chamber was added on the right side of the etching chamber to fix the optical detector for in-situ detecting. In this system, the optical detector was mounted on a seven-shaped bracket, which was fixed by two straight guides, thus the position of the optical detector could be adjusted arbitrarily to collect the emission spectrum generated by the sample during the etching process. The signal was transmitted by optical fiber to the computer for processing, and the etching endpoint could be detected after analyzing the data. Firstly, we used simple substances (Al, Cr, Si, and Mg) to analyze the feasibility of the system and determine the best position of the optical detector. In addition, we also tested the detection limit of the system. Finally, a complex multilayer film sample with different materials was tested, and the results showed that the system could clearly detect the characteristic emission lines of different layers and had a good real-time performance and excellent endpoint detection capabilities.

Biomarkers involved in the proliferation of the odontogenic keratocyst, glandular odontogenic cyst and botryoid odontogenic cyst.

Odontogenic cysts are a heterogeneous group of lesions with varied clinical behavior. To analyze the expression of the epidermal growth factor receptor (EGFR), Cyclin D1, and transcription factor SOX2 in the odontogenic epithelium evaluating the cell cycle control and cystic expansion. This was a cross-sectional study including 40 cases, 20 odontogenic keratocysts (OKC), 10 botryoid odontogenic cysts (BOC), and 10 glandular odontogenic cysts (GOC). All cases of OKC, BOC, and GOC were positive for EGFR in all layers of the cyst lining. The highest expression of nuclear Cyclin D1 was observed in the suprabasal layer of OKCs and in the basal and suprabasal layers of GOC and BOC (p < 0.001). In addition, SOX2 was only expressed in the suprabasal layer of OKCs. The high expression of EGFR in the cyst membrane suggests that EGF stimulates epithelial proliferation in BOCs, and the high expression of SOX2 in OKCs may be related to the presence of stem cells in the lesion. Cyclin D1 is related to cell cycle disruption in G1-S contributing to stimulates epithelial proliferation of OKCs and GOCs and BOCs.

Continuous Fiber-Reinforced Aramid/PETG 3D-Printed Composites with High Fiber Loading through Fused Filament Fabrication

Recent development in the field of additive manufacturing, also known as three-dimensional (3D) printing, has allowed for the incorporation of continuous fiber reinforcement into 3D-printed polymer parts. These fiber reinforcements allow for the improvement of the mechanical properties, but compared to traditionally produced composite materials, the fiber volume fraction often remains low. This study aims to evaluate the in-nozzle impregnation of continuous aramid fiber reinforcement with glycol-modified polyethylene terephthalate (PETG) using a modified, low-cost, tabletop 3D printer. We analyze how dimensional printing parameters such as layer height and line width affect the fiber volume fraction and fiber dispersion in printed composites. By varying these parameters, unidirectional specimens are printed that have an inner structure going from an array-like to a continuous layered-like structure with fiber loading between 20 and 45 vol%. The inner structure was analyzed by optical microscopy and Computed Tomography (µCT), achieving new insights into the structural composition of printed composites. The printed composites show good fiber alignment and the tensile modulus in the fiber direction increased from 2.2 GPa (non-reinforced) to 33 GPa (45 vol%), while the flexural modulus in the fiber direction increased from 1.6 GPa (non-reinforced) to 27 GPa (45 vol%). The continuous 3D reinforced specimens have quality and properties in the range of traditional composite materials produced by hand lay-up techniques, far exceeding the performance of typical bulk 3D-printed polymers. Hence, this technique has potential for the low-cost additive manufacturing of small, intricate parts with substantial mechanical performance, or parts of which only a small number is needed.

НАПРЯЖЕННО-ДЕФОРМИРОВАННОЕ СОСТОЯНИЕ ПОДКРЕПЛЕННЫХ СЛОИСТЫМИ ОБДЕЛКАМИ ТОННЕЛЕЙ МЕЛКОГО ЗАЛОЖЕНИЯ ПРИ ДЕЙСТВИИ ТРАНСПОРТНЫХ НАГРУЗОК

Based on the solution of the problem of the action of a transport loads moving at a constant speed on a three-layer or two-layer shells in an elastic half-space, a comparative analysis was performed for the rock mass in the vicinity of a shallows circular tunnel with various designs of their lining (three-layer and two-layer), along the inner surface of which an axisymmetric normal load moves at a constant speed. The inner layer of the three-layer lining is a thick-walled concrete shell, and the outer layers are thin-walled steel shells of equal thickness. The two-layer lining is structurally different from the considered three-layer lining by the absence of the inner layer of the lining. Dynamic equations of elasticity theory in Lame potentials are used to describe the motion of the half-space and the inner layer of the shell. The vibrations of the outer layers of the shell are described by the classical equations of the theory of thin shells. The equations are represented in a movable coordinate system. The contact between the shell and the array is assumed to be either rigid or sliding. The contact between the layers of the shell is supposed to be rigid. To solve the problem, the method of incomplete separation of variables is used. The solution for potentials is presented in the form of a superposition of Fourier-Bessel series and contour integrals of the Fourier type. Next, the method of decomposition of potentials into plane waves and re-decomposition of plane waves into series according to cylindrical functions is used. The solution is obtained for the case when the velocity of the load is less than its critical velocities. The calculation results are presented in the form of graphs and are analyzed in detail. From the analysis of the calculation results, it follows that the use of a three-layer lining as a building envelope is more efficient than a two-layer lining, since in this case the dynamic effect of the moving loads on the rock mass is significantly less.

Дослідження термічної підготовки ковшів

The purpose of the work is to develop a computer model of ladle heating with an open torch on a drying and high-temperature heating installation to control the thermal preparation process. The task of managing ladle drying and high-temperature heating installations (USVR) is to implement their operating modes, which ensure obtaining the specified temperature profile of the lining layers of steel castings with minimal fuel consumption. The task of controlling by drying and high-temperature heating unit (SHHS) is to implement their operating modes that provide a given temperature profile of steel pouring ladle lining layers with minimal fuel consumption. Since modern technical means of control do not allow obtaining relevant information about the temperature field of the lining of the walls and bottom of the ladle, it is necessary to create a predictive model of its heating by an open torch at the SHHS. A 68-ton rammed steel-pouring ladle KС-68 was chosen as the object of study. According to the research data, the shape and dimensions of the open torch were evaluated at OCC PrJSC “Evraz- Dnipro Metallurgical Plant”. A digital camera recorded the torch at the burner outlet at a natural gas flow rate of 50 m3/h, which corresponds to the standard mode of drying and warming up the ladle. For modeling purposes, the resulting torch shape was approximated by two truncated cones. Determination of the parameters of convective-radiant heat transfer in the “torch – cover – wall – ladle bottom” system was carried out taking into account the temperature of the torch, the thermophysical properties of the lining materials, as well as the irradiance coefficients and the emissivity of the surfaces. The calculation of the temperature field in the lining of the wall and bottom of the ladle was carried out by the finite element method implemented in the ANSYS package. Based on the simulation, a change in the temperature field of the ladle lining was obtained during its heating at the SHHS with an open torch for 6 hours, which corresponds to the current technology. An analysis of the dynamics of the temperature field of the ladle lining obtained as a result of modeling indicates that when it is heated by an open torch at a drying and high-temperature heating unit, thermal stresses do not occur, which are dangerous from the point of view of cracking in the layers of refractory materials. The maximum temperature gradient in the wall is 10 °С/mm, and at the bottom – 6 °С/mm. It has been established that the working surface of the lining warms up sufficiently to avoid thermal shock when steel is poured into the ladle. The results of the research can be useful for optimizing the process of thermal preparing steel pouring ladles.