Search Results (27)

This study focuses on the behavior of hybrid polymer composites made from glass fiber and natural fiber-based flax fabric when subjected to low velocity drop-weight impacts. With the rise in the utilization of composites in structural components in various industries like the marine, aerospace and automotive industries, it is of paramount importance to study the effects of low velocity drop-weight impacts and their damage assessment on the composites. Low velocity drop-weight impacts can occur due to a tool falling on a composite part or due to an impact with a small object. The experimental tests were carried out according to ASTM standards with a drop-weight impact testing machine. Simulations were done to replicate the tests using explicit finite element software LS-DYNA. The experimental tests were carried out on samples of thickness ~2.5 mm and the energy at impact was 50 J. Upon comparing the experimental results, it was seen that an error percentage in the deformation varied between a minimum of 3.32% and a maximum of 8.93%, and the maximum force at impact varied between a minimum of 0.06% and a maximum of 17.14%. The variations between the experimental and simulated values can be attributed to the presence of voids or other defects that would have inadvertently crept in while making the composite. Additionally, composite laminates lined with a layer of EPS (expanded polystyrene) foam were tested and compared with composite laminates which were not lined with the foam. An improvement in the performance of the composite laminates lined with the EPS foam was observed. Full article

The transcriptional co-factor cell-cycle-related and expression-elevated protein in tumors (CREPT) has emerged as a critical driver of the cell cycle and a significant contributor to tumorigenesis. The aberrant expression or upregulation of CREPT boosts multiple signaling pathways, including Wnt/β-catenin, STAT3 and NF-κB/TNFR2, which are frequently dysregulated in various cancers and are associated with poor overall survival. In preclinical studies, CREPT knockdown via shRNA has demonstrated sustained tumor growth regression. Recent researches have uncovered additional functions of CREPT, including roles in metabolic regulation, tissue repair, and microenvironmental remodeling, further establishing it as a pleiotropic transcriptional regulator. Currently, there is no therapeutic agent that directly inhibits CREPT expression in clinic. However, miRNAs and other methods have been used to target CREPT, which have yielded useful results in inhibiting tumor growth. In this review, we discuss the role of CREPT in the hallmarks of cancer and propose that targeting CREPT will reverse tumor growth and may improve the immune checkpoint inhibitors in combination in CREPT-driven cancers. Full article

This study investigates the pathophysiological process of healed perforated corneal ulcers (HPCUs) in humans. All subjects underwent keratoplasty due to opacities or leakage from HPCUs. Half of each specimen was fixed with 4% glutaraldehyde for transmission electron microscope (TEM) examination. The other half was fixed in 10% formaldehyde for immunofluorescence (IF) examination. TEM identified layered structures with two cell types (polygonal and elongated) connected by gap or adherent junctions during early stage of healing. Both apoptotic and mitotic changes were found in both types of cells. There were no endothelial cells or Descemet’s membrane (DM) present in early stage of healing. During the intermediate stage, the healed area comprised three layers: epithelium, Bowman’s layer, and stroma, with an increase in stromal collagen. Later, adjacent endothelial cells crept in, forming DM and completing the cornea’s 5-layer structure. IF examinations revealed that vimentin⁺ and α-smooth muscle actin (αSMA)⁺ myofibroblasts gathered around the damaged site. Proliferating cell nuclear antigen⁺ cells, which indicated cell proliferation, were found in both cells. Anti-phospho-histone H2AX antibodies were found in some epithelial cells. CK14-positive cells were only found in superficial polygonal cells. Corneal wound healing is a complex process that includes apoptosis, cell migration, mitosis, differentiation, and extracellular matrix remodeling. Full article

Amidst increased global migration and the close geographic proximity of Poland and Ireland, there exists a significant number of Polish speaking families in Ireland today. This study examines family language policy (FLP) within Polish transnational families in Ireland and addresses a gap in the literature by exploring the influence of forces outside of the family domain on children’s language socialisation and FLP negotiation. These forces include children’s peer groups, school, and societal dominance of English in Irish society. Data were gathered through a combination of a focus group with parents, semi-structured interviews with parents and children, and children’s reflective language diary entries. The findings reveal that, over time, Polish speaking children’s engagement with education, society, and their peers contributes to their English language socialisation. We argue that family members demonstrate an acute awareness of children being socialised into English language use and, as a result, engage in FLP negotiation and language use adaptation within the home. This study demonstrates the significance of the wider sociolinguistic context within which the families are situated, and highlights the influence of multiple forces, outside of the home, on FLP formation and negotiation within the home. Full article

Background and aims: Cell-cycle-related and expression elevated protein in tumor (CREPT, also named RPRD1B) is highly expressed in tumors and functions to promote tumorigenesis. However, the role of CREPT in the pathophysiology of acute liver injury is limited. Here, we demonstrate that CREPT plays an essential role during acute liver injury. Approach and results: Hepatocyte-specific CREPT knockout (CREPT^hep−/−) and CREPT^flox/flox mice were generated and subjected to the CCl₄ challenge for the acute (24 h) liver injury. The acute CCl₄ challenge triggered increased inflammation as well as liver injury, associated with stronger apoptotic and necroptotic cell death in CREPT^hep−/− mice. CREPT knockout down-regulated the expression of different genes involved in cell survival, inflammation and fibrosis under acute CCl₄ challenge conditions. Antioxidant enzymes such as superoxide dismutase 2 (Sod2) and ferritin heavy chain 1 (Fth1) are dramatically induced at 24 h post-CCl₄ treatment, but this induction is blocked by transcriptional inactivation of NF-κB/Nrf2, indicating that CREPT might promote hepatocyte survival in acute liver injury by participating in the transactivation of antioxidant genes. Conclusions: These results elucidate the role of CREPT in acute liver injury and provide hints for future research on how CREPT might function in hepatocyte renewal. Full article

The effects of oxygen content on the microstructure and creep properties of the FGH96 superalloy were investigated. When oxygen content increased from 135 ppm to 341 ppm, the prior particle boundary (PPB) rose from degree 2 to degree 3, the size of the γ′ phase on PPB enlarged from 1.07 μm to 1.27 μm, and the MC carbide size grew from 77.4 nm to 104.0 nm. Meanwhile, the steady creep rate accelerated from 4.34 × 10⁻³ h⁻¹ to 1.87 × 10⁻² h⁻¹, and the creep rupture life shortened from 176 h to 94 h, the creep rupture mode transferred from intergranular and transgranular mixed fracture to along PPB fracture. During creep, the micro-twin formation and gliding will be restrained by ∑3 boundaries. FGH96 superalloy with higher oxygen content contains less ∑3 boundaries, and its micro-twins cross-slipped instead of single-direction slip in lower oxygen content superalloy. Consequently, samples with a higher oxygen content crept faster and ruptured earlier. Full article

The pyrolysis furnace, a critical component in a pyrolysis unit, inevitably faces operational challenges during its use. This study investigates a case of pyrolysis furnace failure, particularly focusing on an occurrence at the 90° lug elbow and furnace tube weld. The failure, characterized by a comprehensive fracture of the furnace tube in the circumferential direction along the weld vicinity, transpired within a timeframe significantly shorter than one-third of the design life. To unravel the root cause, a series of experiments was conducted on a sample extracted from the failed tube. These experiments, comprising visual inspection, chemical composition analysis, metallographic examination, microstructure analysis, fracture scanning electron microscopy, and energy spectrum analysis, collectively aimed at a comprehensive understanding of the failure mechanisms. The results disclosed that the fracture between the lug elbow and the inlet pipe stemmed from the presence of porosity and inclusions in the butt weld. The initiation of cracks was traced to the pores and inclusions in the fusion line of the inner wall of the pyrolysis tube, extending to connect with the pores in the heat-affected zone on the side of the pyrolysis tube parent material. Subsequently, under the influence of high temperature and stress, the cracks propagated, crept, and expanded along the circumference of the pyrolysis tube parent material until the final fracture occurred. In light of these findings, practical recommendations are proposed to mitigate the risk of similar failures in the future. Full article

In this work, three melt-pouring temperatures (1450 °C, 1480 °C, 1520 °C) and CoAl₂O₄ inoculant contents in the shell mold’s primary coating (0 wt%, 5 wt%, and 10 wt%) were selected to study microstructural and mechanical property changes of the Inconel 713C^® nickel-based superalloy. The castings’ phase transformation temperatures, phase constitution, microstructure, and mechanical properties at room and elevated temperatures were investigated via thermodynamical simulations, differential thermal analysis, light and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and tensile and stress-rupture tests. The pouring temperature and inoculant content strongly influenced the mean equiaxed grain size, which ranged between 2.36 and 6.55 mm. The primary microstructure of Inconel 713C^® castings, owing to its complex chemical composition, comprised multiple phases, including γ, γ’, MC, M₃B₂, and Ni₇Zr₂. The mean size of γ’ was in the 0.446–0.613 μm range, depending on the casting variant. Grain refinement with CoAl₂O₄ at ambient temperature for each melt-pouring temperature led to increased yield strength (YS) and ultimate tensile strength (UTS). YS was in the range of 775–835 MPa, while UTS was in the range of 868–1010 MPa. A reverse trend was observed in samples that crept in 982 °C/152 MPa, while for each variant, the time to rupture exceeded 30 h. The maximum time to rupture was 46.1 h obtained in the unmodified casting poured at 1480 °C. Full article

A number of foreign artists received the earliest commissions to represent Napoleon’s Russian Campaign of 1812 for Russian emperors. My paper is a case study of a German artist who served the Russian Imperial court. Peter von Hess trained at the Academy in Munich and served both King Ludwig I of Bavaria and Otto I of Greece. In 1839, Emperor Nicholas I commissioned the artist to complete 12 monumental canvases for the Winter Palace representing key battles that followed Napoleon’s invasion of Russia in 1812. While earlier battle paintings and portraits commissioned by Alexander I dealt only with elite officers and the emperor, Hess’s paintings elevated the common Russian as the bearers of a great sacrifice and as the true defenders of Russia. This representational shift is the product of changing ideas concerning Russia’s involvement in several alliances from 1803 to 1815 that included Austria, England, Sweden, and Prussia. In addition, over the course of Nicholas I’s reign, the concepts of “autocracy, orthodoxy, nationality” crept into representations of the Russian experience of the Napoleonic wars. Full article

The karst fissures of the carbonate thermal reservoir in Xiong’an New Area have developed, and they have the advantages of a concentrated distribution, shallow burial, large water volume, and easy recharge, which are conducive to the development and utilization of geothermal resources. This paper took the carbonate thermal reservoir in Xiong’an New Area as the research object and studied the characteristics of the seepage patterns and temperature distribution in thermal storage with different well arrangements and recharge methods by laser etching the micromodel of the carbonate thermal reservoir and simulating the recharge methods. The paper established a numerical model of the resettlement area of Xiong’an New Area based on the production data and the current recharge well pattern, and it proposed a plan for a geothermal doublet well arrangement. The results showed that the injection speed and angle significantly influenced the seepage of injected water in the fractured reservoir. The injection speed correlated with the breakthrough time and swept area. The breakthrough time plummeted as the injection speed increased, and the swept area crept up as the injection-fracture dip increased. The well arrangements also impacted the seepage patterns. The well pattern of two injectors and three producers was relatively suitable for geothermal reinjection, and it was more appropriate to choose the maximum injection-fracture dip because of the largest swept area. Factors that affected the sustainable development and utilization of geothermal fields included the well pattern arrangement, well spacing, injection and production volumes, and the temperature of the injected water. Based on the modeling, it is recommended that the well spacing be greater than 500 m, and the injection and production volumes less than 110 m³/h in the resettlement area of Xiong’an New Area. Moreover, a vertical fracture well is recommended to reduce thermal breakthroughs. Full article

From the point of view of production, it is of fundamental importance to know the cutting parameters at which the new surface of the component was created because only in this way is it possible to understand the nature and properties of the created surface. Based on the information obtained, it is then possible to improve the processes used or to create machined surfaces with, if not zero, at least a minimum number of flaws. The main purpose of the article is to create a comprehensive overview of the behavior and properties of the selected material with a focus on the prediction of roughness depending on the cutting speed and depth of cut, Vickers microhardness evaluation, assessment of cutting tool wear, and assessment of the shape and structure of the resulting chip. The achieved results are recorded in graphical and verbal form, from which the necessary conclusions are drawn. From the performed analyses, a mathematical prediction of determining the quality of the machined surface was created, which reflects changes in roughness depending on the cutting speed in the three modifications (700 m/min, 1400 m/min, and 2000 m/min). Conclusions were also drawn regarding the characteristics of the resulting chip and the wear of the cutting edges depending on the change in cutting speed. The fluctuating course of surface roughness when changing the cutting speed can be considered a significant finding—at 1400 m/min, the surface roughness was expected to have a decreasing tendency; however, it increased; a decreasing tendency was not recorded until at speeds of 1800 m/min, but during this process, the material already crept. Full article

The Cu-rich phase is a high-efficiency and ultra-stable precipitation-strengthening phase and has been widely used in many steels and alloys, especially in heat-resistant steels and alloys. Creep damage is accompanied with the coarsening of the second phase. In the present work, the calculation of phase diagrams (CALPHAD) method and elastic–plastic mechanics are coupled with the phase field (PF) approach to investigate the growth behavior and the accompanying stress/strain field evolution of nano-sized Cu-rich precipitates in an Fe-Cr-Ni-Cu medium-entropy alloy. The results show that creep strain is intensified with the coarsening of Cu-rich particles. The simulated size of Cu-rich particles is in good agreement previous experimental reports. The plastic strain tends to shear the Cu-rich phase when they are relatively fine (~<11 nm), and the size of the Cu-rich particles has a slight influence on the creep strain at this stage. In contrast, coarse Cu-rich precipitates (~>11 nm) are bypassed by the plastic strain due to the enhancing stress concentration around the interface, and the creep strain is rapidly aggravated with the growth of Cu-rich particles. The coarsening of Cu-rich particles will be retarded by the adjacent particles due to the overlapping of the diffusion zone, and hence the creep strain was reduced when crept for the same time. The retard effect will vanish when their distance is sufficiently long (~>60 nm). When the size of the Cu-rich particles is identical, the creep strain will be mitigated with elongation of the distance between two Cu-rich particles. Full article

In this study, we investigated the creep properties of ZK60 alloy and a ZK60/SiC_p composite at 200 °C and 250 °C in the 10–80 MPa stress range after the KOBO extrusion and precipitation hardening process. The true stress exponent was obtained in the range of 1.6–2.3 for both the unreinforced alloy and the composite. The apparent activation energy of the unreinforced alloy was found to be in the range of 80.91–88.09 kJ/mol, and that of the composite was found to be in the range of 47.15–81.60 kJ/mol, and this indicated the grain boundary sliding (GBS) mechanism. An investigation of crept microstructures using an optical microscope and scanning electron microscope (SEM) showed that at 200 °C, the predominant strengthening mechanisms at low stresses were the formation of twin, double twin, and shear bands, and that by increasing the stress, kink bands were activated. At 250 °C, it was found that a slip band was created in the microstructure, and this effectively delayed GBS. The failure surfaces and adjacent regions were examined using SEM, and it was discovered that the primary cause of failure was cavity nucleation around precipitations and reinforcement particles. Full article

The Italian Thermotechnical Committee is drafting a new standard for the life assessment of creep-operated pressure equipment, including modern steam boilers. For the evaluation of the spent life ratio several methods are available, even if each of them is not exhaustive. It should be noted that the methods described must be considered in combination with NDTs and other kinds of tests, e.g., hardness tests. X-ray diffraction (XRD) is one of the methods that could be used to assess material evolution under creep conditions. The method allows for the study of phase transitions involving structural variations. It is possible to operate on both massive samples and powders. In this paper, work done with XRD, in the frame of a wider project regarding the study of the high-temperature behavior of welded martensitic steels, is presented. The results of the XRD analysis were compared with the results of the extraction replicas. This work concerns the controls of eight failed crept specimens submitted to XRD examinations. Eight XRD diagrams were produced and subsequently compared with 12 replicas for each specimen; that is, 96 extraction replicas were produced for this work. Then, around 5000 precipitates were analyzed for each specimen; therefore, for this work, around 40,000 precipitates were characterized with their chemical compositions. The average size of the precipitates was around 97 nm. Full article

Histone deacetylases 1 (HDAC1), an enzyme that functions to remove acetyl molecules from ε-NH3 groups of lysine in histones, eliminates the histone acetylation at the promoter regions of tumor suppressor genes to block their expression during tumorigenesis. However, it remains unclear why HDAC1 fails to impair oncogene expression. Here we report that HDAC1 is unable to occupy at the promoters of oncogenes but maintains its occupancy with the tumor suppressors due to its interaction with CREPT (cell cycle-related and expression-elevated protein in tumor, also named RPRD1B), an oncoprotein highly expressed in tumors. We observed that CREPT competed with HDAC1 for binding to oncogene (such as CCND1, CLDN1, VEGFA, PPARD and BMP4) promoters but not the tumor suppressor gene (such as p21 and p27) promoters by a chromatin immunoprecipitation (ChIP) qPCR experiment. Using immunoprecipitation experiments, we deciphered that CREPT specifically occupied at the oncogene promoter via TCF4, a transcription factor activated by Wnt signaling. In addition, we performed a real-time quantitative PCR (qRT-PCR) analysis on cells that stably over-expressed CREPT and/or HDAC1, and we propose that HDAC1 inhibits CREPT to activate oncogene expression under Wnt signaling activation. Our findings revealed that HDAC1 functions differentially on tumor suppressors and oncogenes due to its interaction with the oncoprotein CREPT. Full article