Search Results (368)

To address the depletion of shallow coal resources, mining activities have progressed to greater depths, where rock masses contain numerous fractures due to complex geological conditions, making grouting reinforcement essential for ensuring stability. Using digital image correlation, this study investigated the strain evolution characteristics of grouted fractured specimens of three rock types—mudstone, coal–rock, and sandstone—under uniaxial compression. Analysis of the strain evolution process focused on two typical fracture inclinations of 0° and 60°, while examination of the peak strain characteristics covered five inclinations, namely 0°, 15°, 30°, 45°, and 60°. The findings indicate that the mechanical response varies systematically with lithology and fracture inclination. The post-peak curves differ significantly among rock types: coal–rock shows a gentle descent, mudstone exhibits a rapid strength drop but higher residual strength, and sandstone is characterized by “serrated” fluctuations. The failure mode transitions from tensile splitting at a horizontal inclination of 0° to shear failure at inclinations of 15°, 30°, 45°, and 60°. Strain nephograms corresponding to the peak stress point D reveal sharp, band-shaped zones of strain localization. The maximum principal strain exhibits a non-monotonic trend, first increasing and then decreasing with increasing inclination angle. For grouted coal–rock and sandstone, the peak values of 47.47 and 45.00 occur at α = 45°. In contrast, grouted mudstone reaches a maximum value of 26.80 at α = 30°, indicating its lower susceptibility to damage. The study systematically clarifies the strain evolution behavior of grouted fractured rock masses, providing a theoretical basis for evaluating the effectiveness of reinforcement and predicting failure mechanisms. Crucially, the findings highlight mudstone’s role as a high-integrity medium and the particular vulnerability of horizontal fractures, offering direct guidance for the targeted grouting design in stratified rock formations. Full article

Colonoscopy is central to colorectal cancer (CRC) prevention, and its effectiveness is determined by the quality of mucosal inspection and lesion detection. The adenoma detection rate (ADR) remains the most widely validated quality benchmark due to its strong inverse association with interval CRC. However, reliance on ADR alone is increasingly recognized as insufficient, particularly given the growing understanding of the serrated neoplasia pathway, which contributes up to one-third of sporadic CRCs. This has driven the emergence of complementary metrics, such as the sessile polyp detection rate (SPDR) and adenomas per colonoscopy (APC). Although SPDR offers important advantages for capturing serrated pathology, challenges persist, including interobserver variability, inconsistent pathology thresholds, limited endoscopist training, and the absence of standardized benchmarks. Alongside these evolving metrics, technological advancements such as image-enhanced endoscopy, computer-aided detection, high-definition optics, and distal attachment devices have demonstrated measurable improvements in detecting subtle lesions and reducing operator-dependent variability. Large real-world registries, including GIQuIC, now support the development and validation of composite models that integrate ADR, SPDR, and APC to better reflect the full spectrum of neoplasia detection. As the field advances, redefining colonoscopy quality will require reconciling established metrics with newer indicators that more comprehensively address both conventional adenomas and serrated lesions. Full article

This study proposes a novel framework for quantifying curved grain boundaries that overcomes key limitations of existing methods. Unlike Fourier-based approaches that require labor-intensive sequential analysis of individual boundaries and selectively represent only high-amplitude regions, or spline-based methods that demand complex parameter selection for interpolation points, the proposed framework integrates curvature variance filtering with U-chord curvature calculation to enable automated, comprehensive, and noise-resistant characterization of grain boundary morphology. The curvature variance filtering adaptively determines smoothing parameters based on local curve properties, while the U-chord curvature method ensures rotational invariance and robustness against digitization errors. Four heat treatment processes were applied to GH4169 alloy, producing distinct grain boundary morphologies with mean curvature (MC) values ranging from 0.0625 to 0.1252. Controlled cooling alone (Process A) yielded predominantly straight boundaries (91.06% straight, 0.12% serrated), while re-dissolution treatment (Process D) produced the highest serration degree (58.81% straight, 3.53% serrated). The quantitative analysis reveals that dispersed δ-phase precipitation creates discrete pinning points, forming serrated boundaries with sharp curvature peaks, whereas dense, parallel δ-phase arrays at specific angles produce coordinated wavy undulations. This framework provides a reliable quantitative tool for optimizing heat treatment protocols to achieve target grain boundary configurations in nickel-based superalloys. Full article

Shale pores and throats are key factors controlling the enrichment and development efficiency of shale oil and gas. However, the characteristics and formation mechanisms of shale pores and throats remain unclear. Taking the Permian continental shales in the Mahu Sag of the Junggar Basin as an example, this paper studies the formation mechanisms of pores and throats in shales of different lithofacies through a series of experiments, such as high-pressure mercury injection and scanning electron microscopy. The results show that the Permian continental shales in the Junggar Basin are mainly composed of five lithofacies: rich siliceous shale (RSS), calcareous–siliceous shale (CSS), argillaceous–siliceous shale (ASS), siliceous–calcareous shale (SCS), and mixed-composition shale (MCS). The pores in shale are dominated by intergranular and intragranular pores. The intergranular pores are mainly primary pores and secondary dissolution pores. The primary pores are mainly slit-like and polygonal, with diameters between 40 and 1000 nm. The secondary dissolution pores formed by dissolution are irregular with serrated edges, and their diameters range from 0.1 to 10 μm. The throats are mainly pore-constriction throats and knot-like throats, with few vessel-like throats, overall exhibiting characteristics of nanometer-scale width. The mineral composition has a significant influence on the development of pores and throats. Siliceous minerals promote the development of macropores, and carbonate minerals promote the development of mesopores. Clay minerals inhibit pore development. Diagenesis regulates the development of pores and throats through mechanical compaction, cementation, and dissolution. Compaction leads to a reduction in porosity, and cementation has varying effects on the preservation of pores and throats. Dissolution is the main factor for increased pores and throats. These findings provide a lithofacies-based geological framework for evaluating effective porosity, seepage capacity, and shale oil development potential in continental shale reservoirs. Full article

Background: Appendiceal neoplasms are rare, but recent data indicate a rising trend, particularly in patients under the age of 50. These tumours are often diagnosed incidentally during histopathological examination. This study has aimed to examine the incidence and histological subtypes of appendiceal neoplasms in a Southern Hungarian population. Methods: Our study included neoplastic appendix specimens processed at the University of Szeged between 2014 and 2023. Results: Neoplasms were identified in 71 cases from 3640 appendectomies (1.9%). Benign lesions were present in 37% of cases (n = 26), with the most common subtype being the sessile serrated lesion (n = 20). Mucinous and malignant neoplasms were found in 63% of cases (n = 45), most frequently low-grade appendiceal mucinous neoplasm (n = 19), followed by neuroendocrine tumour (n = 17). Notably, colorectal neoplasm was identified in 50% of benign, and 42.2% of mucinous and malignant cases during a mean follow-up of 33.4 months. Significant associations were found between histological subtype and age (p = 0.022), complete resection (p = 0.012), presence of vascular invasion (p = 0.007), and localisation of potentially associated colorectal carcinoma (p = 0.018). Additionally, tumour dignity showed significant correlations with tumour, node, metastasis (TNM) stage (p < 0.001), vascular invasion (p = 0.017), and lastly, occurrence (p = 0.031) and localisation (p = 0.003) of associated colorectal carcinoma. Conclusions: The prevalence and characteristics observed in this Southern Hungarian population were consistent with international data, although raw case numbers suggested an upward trend. The high rate of associated colorectal neoplasms underscores the importance of thorough pathological evaluation and long-term surveillance. Full article

Currently, the synonymy of the two morphologically analogous copepod species, Mongolodiaptomus birulai (Rylov, 1922) and M. formosanus Kiefer, 1937, remains doubtful. While examining the detailed morphology of diaptomid copepods from China, Cambodia, and Vietnam, we came across two undescribed species whose morphology is closely similar to that of M. birulai from Northeast China and M. formosanus from Taiwan. In this paper, descriptions of M. parabirulai sp. nov. from Yunnan, Southwestern China, and M. longiserratus sp. nov. from Cambodia and Vietnam are presented. The first new species, M. parabirulai sp. nov., can be distinguished from its congeners in the male P5 by it having the distal outer portion of the second right exopod produce a wing-shaped expansion and its strongly robust left and right basis. The second new species, M. longiserratus sp. nov., can be differentiated by the following characteristics in the male: the spiniform process on segment 20 of the right antennule is longer than that of segment 21 and has a serrate outer margin, and the right P5 basis has two (longitudinal and semicircular) hyaline lamellae. Furthermore, the status of M. birulai and M. formosanus is reviewed and recommended. Full article

An in-depth study of the genetic mechanisms of graphite in shear zones is crucial for understanding crustal weakening and the origins of inorganic carbon. This research focuses on mylonitic marble (MM) and cataclastic marble (CM) from the Tongyuanpu shear zone of Eastern China. The occurrences, nanostructures, carbon sources, and genesis of graphite were systematically investigated through micro- to ultra-microscale analysis. The results reveal that the MM contains two graphite varieties: C-foliation-aligned bands and stylolite-derived serrated aggregates. Both exhibit strong Z-axis LPO, indicating a deformation temperature below 200 °C. In contrast, the CM features individual graphite particles within fragmented grains. Near-ideal graphite structures are characterized in both types; however, a higher TOC content and a greater graphitization degree are observed in the CM. Raman thermometry indicates metamorphic peak temperatures of 588–673 °C (MM) and 540–682 °C (CM), with the former showing a significant discrepancy from the EBSD results. The δ¹³C_ORG values (−12.21‰ to −8.06‰) suggest fluid-derived carbon sources. We propose that reduction reactions involving high-temperature metamorphic fluids supplied the essential carbon source. Ductile shearing accelerated the graphitization of these carbonaceous materials through the accumulation of local strain energy, while subsequent brittle deformation with frictional sliding further facilitated structural transformation. Full article

Large Strain Extrusion Machining (LSEM) is an intensive plastic deformation process evolved from conventional machining, enabling effective control over chip morphology and grain refinement. This process often generates high cutting temperatures and frictional instability during machining, which degrades material properties and accelerates tool wear. This study proposes a technique combining microtextured tools with LSEM to optimize cutting performance. By designing different microtextured tools (parallel-to-cutting-edge microtextured tools (P-T) and perpendicular-to-cutting-edge microtextured tools (V-T)), cutting experiments were conducted on 7075 aluminum alloy to systematically investigate the effects of microtextured LSEM on cutting performance and chip formation. Results indicate that microtextured tools effectively reduce cutting temperatures. Compared to non-textured tools (N-T), microtextured tools can lower maximum cutting temperatures by up to 13.20% (36.56 °C). Microtextured LSEM suppresses serration formation, leading to more stable chip formation. The serration degree of chips produced by microtextured tools was reduced by up to 25.66% compared to N-T tools. XRD analysis indicates that microtextured tools significantly increase chip dislocation density, reaching nearly 2.77 times that of N-T tools, enhancing material microhardness and refining grain size. This study confirms that combining microtextured tools with LSEM synergistically optimizes chip morphology and improves the microstructural properties of Al7075, providing technical support for machining high-strength aluminum alloys. Full article

Sessile serrated lesions (SSLs) are well-known precursors of colorectal cancer in the general population, but their role in inflammatory bowel disease (IBD) is less clear. This narrative review summarizes what is known about the prevalence, molecular features, endoscopic detection, malignant potential, and management of SSLs in patients with IBD, highlighting where evidence supports action nowadays and where prospective studies are urgently needed. IBD-associated colorectal cancer has long been considered a consequence of the inflammation–dysplasia–carcinoma sequence, distinct from the conventional adenoma–carcinoma pathway. Increasing evidence, however, suggests that the serrated pathway, typically characterized by SSLs and traditional serrated adenomas (TSAs), may also contribute to IBD-related oncogenesis. This review synthesizes histopathological, molecular, endoscopic, and clinical data on SSLs in patients with IBD, with contextual reference to TSAs, sessile serrated lesions with dysplasia, and serrated epithelial change only when relevant to their interpretation or risk stratification. SSLs are now more frequently identified in IBD surveillance, especially in ulcerative colitis and the proximal colon, although prevalence estimates remain heterogeneous due to evolving definitions and significant interobserver variability. Molecular studies indicate that IBD-associated serrated lesions often harbor BRAF mutations but display a lower CpG island methylator phenotype than their sporadic counterparts, suggesting an inflammation-modified biology. While most hyperplastic polyps and non-dysplastic SSLs appear to pose limited neoplastic risk, dysplastic serrated lesions carry a markedly higher likelihood of synchronous or metachronous advanced neoplasia. Advances in high-definition endoscopy and chromoendoscopy improve the detection of these subtle, mucus-capped, flat lesions, while endoscopic resection is nowadays feasible in expert hands. Future priorities should include prospective multicenter cohorts integrating molecular profiling to refine surveillance strategies. Full article

The synthesis of high-performance adhesives imposes stringent requirements on the design of stirred reactors: simultaneous achievement of efficient mixing and minimal energy dissipation in highly viscous media remains the principal challenge. In this study, computational fluid dynamics (CFD) was employed to solve the Navier–Stokes equations for the high-viscosity epoxy system and numerically simulating the flow fields of four representative reactor configurations across a prescribed range of rotational speeds. Specifically, the four representative reactor configurations were (i) single-serrated shaft, (ii) eccentric single-serrated shaft, (iii) uniaxial single-blade paddle combined with a single-serrated dual-axis assembly, and (iv) biaxial single-blade paddle coupled with a single-serrated triaxial assembly. The mixing performance was quantitatively assessed by systematically comparing the evolution of mixing speed, vorticity fields, restricted power consumption, and mixing time across a range of rotational speeds. The results demonstrated that the synergistic deployment of an eccentric impeller and a differential-speed single-propeller shaft effectively disrupted the axisymmetric flow pattern, compressed the chaotic isolation zones, and intensified both axial exchange and global chaotic mixing. Among the configurations examined, the uniaxial single-propeller–single-serrated biaxial arrangement reduced the mixing time by 13.43% and cut the specific energy consumption by approximately 58.32%, thereby attaining markedly higher energy efficiency. This research will provide guidance for the study of efficient mixing of adhesives. Full article

Comprehensive studies of hydrogen embrittlement in high-strength austenitic alloys under cryogenic conditions are scarce, leaving the combined effect of hydrogen charging and extreme temperatures largely unexplored. Given the demands of cryogenic applications such as hydrogen storage and transport, understanding material behavior under these conditions is crucial. Here, we present the first systematic study of hydrogen’s effect at liquid helium temperature (4.2 K) on the mechanical properties of precipitation hardened austenitic alloys, specifically the nickel-based Alloy 718 and austenitic stainless steel A286. Both materials were subjected to pressurized hydrogen charging at 473 K followed by slow strain rate tensile testing at room temperature and at 4.2 K. Hydrogen charging caused significant ductility loss at room temperature in both alloys. In contrast, testing at 4.2 K resulted in increased strength and no evidence of hydrogen embrittlement. Notably, materials pre-charged with hydrogen and tested at 4.2 K exhibited higher stress drop amplitudes and increased strain accumulation during serration events, suggesting persistent hydrogen–dislocation interactions and possible enhanced dislocation pinning by obstacles such as Lomer–Cottrell locks. These results indicate that while hydrogen influences plasticity mechanisms at cryogenic temperatures, embrittlement is suppressed, providing new insight into the safe development of austenitic alloys in cryogenic hydrogen environments. Full article

Aluminum–magnesium alloys show the Portevin–Le Chatelier (PLC) effect. The aim of this publication is to provide a detailed analysis of the evaluation methods of this phenomenon using tensile tests at a strain rate range of 10⁻³ s⁻¹, where A and A + B stress serrations can be observed. Four smoothing and analytical functions are evaluated in detail as reference functions, which are compared based on their serration amplitude and frequency characteristics. The studied functions are the moving average and Savitzky–Golay smoothing method, as well as the Voce and polynomial analytic functions. The two smoothing methods and smoothing window sizes are compared to obtain the best reference function parameters. Full article

Tensile tests of AlMg4.5 alloy were carried out at six strain rates to study the Portevin–Le Chatelier (PLC) effect. The measured engineering stress–time and engineering stress–engineering strain curves were evaluated by direct peak detection and reference function approximation. The waiting and decay times of the PLC effect, and the related stress jumps and drops, were determined. It was shown that, as a function of strain rate, the quotient of the decay and the waiting time forms a curve with a decreasing slope after an initial rapid rise; the same can be stated about the time derivative of the stress jumps. These relationships are suitable for identifying serrations that vary depending on the strain rate, in full harmony with the stress serration amplitudes observed in the tensile test diagrams. Full article

Background/Objectives: Computer-aided detection (CADe) systems are increasingly used in endoscopy to enhance lesion recognition. PolyDeep is a CADe/x tool previously assessed in an observational study. The aim of our study is to determine if PolyDeep-assisted colonoscopy reduces the adenoma miss rate (AMR) compared with conventional colonoscopy. Methods: We carried out a multicenter randomized controlled trial with a tandem colonoscopy design in participants from a colorectal cancer screening program (positive fecal immunochemical test-FIT or surveillance). Expert endoscopists performed all colonoscopies, and patients were allocated to groups by a computer-generated sequence. The primary endpoint was AMR; secondary endpoints included polyp miss rate (PMR), serrated lesion miss rate (SLMR) and advanced polyp miss rate (APMR). Results: From May to November 2023, we recruited 260 patients and excluded 20, leaving 240 for analysis. Baseline characteristics were balanced between groups (62.1% male; mean age 62.3 ± 6.5 years; 65.8% FIT-positive; mean first withdrawal time 13:38 ± 08:07 min; mean second withdrawal time 07:50 ± 03:38 min; lesion detection rate 76.6%; mean polyps per patient 3.4 ± 3.1). We did not find statistically significant differences between PolyDeep-assisted and conventional colonoscopy groups in AMR (21.3% vs. 18.1%, p = 0.5), PMR (21.8% vs. 20.3%, p = 0.7), SLMR (23.4% vs. 25.6%, p = 0.9) or APMR (7.3% vs. 11.3%, p = 0.5). In the subgroup analysis according to indication, we did not find any statistically significant differences. Conclusions: In the context of a CRC screening program, PolyDeep-assisted colonoscopy did not reduce AMR. Full article

The cause of nephrotic–nephritic syndrome and elevated blood pressure values was investigated by renal biopsy in a 72-year-old Caucasian male with B-cell chronic lymphocytic leukemia (B-CLL) and a low level of IgG/lambda paraprotein. Double-contoured glomerular capillaries, glomerular thrombi, interstitial B-CLL infiltrates, and normal-looking arteries and arterioles were observed histologically. The glomerular capillaries displayed nonspecific entrapment of IgM and C3 and pseudolinear C4d positivity immunohistochemically. With electron microscopy, diffusely effaced foot processes, widened and duplicated glomerular basement membrane (BM), mesangial cell interposition, and thickened, non-fenestrated, and serrated endothelial cells located on subendothelial BM layer(s) were seen. The peritubular capillaries lacked any significant BM multilayering. Chronic glomerular thrombotic microangiopathy (TMA) was diagnosed; the C4d positivity result indicated structural remodeling of glomerular capillary walls. Laboratory features of microangiopathic hemolytic anemia were absent. The functional complement assay found selective classical pathway activation and the consumption of early complement components. The components of the alternative pathway were not consumed. A disease-causing variant in the coding region of the complement C2 gene was screened, with negative results. The kidney function gradually deteriorated to stage 4 chronic kidney disease over a period of six months. Second-line treatment with ibrutinib markedly decreased the leukemic symptoms, stopped the production of paraprotein, and eliminated the nephrotic syndrome; the kidney function improved. The decreased activity of the classical pathway remained unchanged. The culprit of glomerular anomalies seemed to be the paraprotein, which acted as a nephrotoxic mediator and triggered glomerular TMA. A hypothetical pathophysiologic explanation of TMA is presented. The paraneoplastic classical pathway activation of complement did not play any role in the development of glomerular TMA. Full article