Large Diameter Research Articles

Research and Application of High Efficiency Pressure Relief Technology for Ultra-high Pressure Hydraulic Slotted Coal Seam

In order to solve the technical problem of efficient pressure relief of the impact coal seam, the principle of ultra-high pressure hydraulic slit relief and anti-impact technology is expounded, and the ultra-high pressure hydraulic slit device with working pressure up to 100MPa is selected as the pressure relief equipment of coal seam. The field test of high-efficiency pressure relief by ultra-high pressure hydraulic slotting in impact coal seam was carried out. The test showed that the slotting radius of No.3 coal in Tangkou Mine could reach 1.5m under the condition of 100MPa slotting pressure. The stress variation in seam area and large diameter drilling area is compared and analyzed. The stress in seam area decreases significantly by 40%. The stress of bolt (cable) and the deformation of surrounding rock in the slit area are investigated. Compared with the large-diameter pressure relief area, the increase value of bolt is lower and the increase value of cable is significant in the hydraulic slit test area. The technical benefits of hydraulic slotting and large-diameter drilling are summarized and compared. The engineering quantity of drilling with ultra-high pressure hydraulic slotting is reduced by 60%, and the coal output is 2.5 times of that of large-diameter drilling. The large-diameter drilling provides limited pressure relief space for coal seam, but the ultra-high pressure hydraulic slotting technology can effectively increase the deformation space in the coal body and reduce the elastic energy stored in the coal pillar, so as to achieve a good pressure relief effect. The field test shows that compared with large diameter drilling, ultra-high pressure hydraulic slotting technology has remarkable effects of pressure relief, shock absorption and shock prevention.

Influence of precast microbial reinforcement on lateral responses of monopiles

Microbially Induced Calcium Carbonate Precipitation (MICP) provides an environmentally friendly solution for reinforcing large diameter monopiles for offshore wind turbines (OWTs). This study presents an investigation into the lateral responses of monopiles with precast microbial reinforcement using a low-pH one-phase method. Both static and cyclic loading tests were carried out. The results of static loading tests show that the failure mode of the bio-reinforced monopile was an overall overturn failure. The lateral bearing capacity was increased by 50% and the bending moment was reduced by about 25% with the bio-reinforcement. Further investigation was conducted on the secant stiffness, damping ratio, and accumulated deformation of the bio-reinforced monopile under various cyclic loadings. With the bio-reinforcement, the accumulated deformation under one-way cyclic loading can be reduced by 30%–60%. The influences of cyclic loading parameters and loading sequence on pile stiffness were clarified. The growth ratio of pile stiffness due to bio-reinforcement under one-way loading was between 1.65 and 2.82, and decreased with increasing load amplitude. The ratio was smaller under two-way loading. Three competing factors on pile stiffness were identified: cyclic compaction of the unreinforced sandy soil, weakening of the bio-reinforced soil and soil subsidence around the bio-reinforced soil.

Relationship Between Diameter and Pelvic Vein Reflux

Introduction: Diameter has been a complementary measurement in the evaluation of venous valvular insufficiency of superficial veins of the lower extremity. Small veins with reflux or large veins without reflux may indicate alternative treatments. Awareness of pelvic vein reflux is increasing. The pelvic vein diameter-reflux relationship was investigated. Methods: Findings of lower extremity ultrasound (US) and/or clinical conditions—pelvic pain, dyspareunia and dysmenorrhoea—were indications for pelvic/abdominal venous US. Complete US examination included renal, internal iliac and gonadal/ovarian veins. Diameters of the largest right or left pelvic veins were compared with presence of reflux. Intravaginal US was completed in 104 women, age 46 ± 11 (standard deviation) (range 25-76) years old. Pelvic symptoms were reported by 30 (29%) patients. The other patients had pelvic-related recurrent varicose veins or suspected pelvic source of lower extremity venous reflux. Positive and negative predictive values (PPV, NPV) and other statistics at the 90-95% level were calculated relating diameter to pelvic vein reflux. Results: Pelvic vein reflux was detected in 54 (52%) women. Pelvic vein diameters were larger in refluxing, 8.4 ± 1.9 (5.1-14.0) mm, than in nonrefluxing veins, 5.2 ± 1.0 (3.4-8.3) mm ( P < .001 by t test). Diameters ≥6.3 mm had 91% (49/54) sensitivity and 92% (49/53) PPV. Diameters ≤6.3 mm had 94% specificity (47/50) and 89% (47/53) NPV. All veins with diameter ≥8.4 mm ( n = 21) had reflux. All veins with diameter ≤5.0 mm ( n = 27) did not have reflux. Conclusions: Probabilities of pelvic vein reflux were estimated based on diameters. Diameter-reflux agreement solidifies diagnosis. An explanation for contradiction between small diameter and reflux or large diameter and no reflux is recommended.

Harnessing fuzzy logic for building structural health during large diameter tunnelling in urban area

Building structural health is constantly jeopardized by tunnel construction, which thus is in a sustained demand for holistic risk assessment and management approaches. In this study, we propose an enhanced consulting fuzzy model with limited information losses to evaluate the static and dynamic risks of building health deterioration during tunnelling. The model integrates three main strategies including, (i) reducing influence of experts’ bias in the ranking processes; (ii) expanding the space of uncertainties in fuzzy environment, and (iii) controlling risk aversion settings through the prospect theory. The construction of the largest diameter (15.3 m) tunnel in China is adopted as a case study to demonstrate the application of the proposed model in assessing the risk statuses of surrounding buildings. Through the proposed model, the risk index can indicate beneficial or detrimental effects of tunnelling and the degree of risk factors delineates priority actions for risk management. The results enable the development of operational risk abatement procedures to enhance the state of practice of large diameter tunnel construction in complex geological conditions.

The effectiveness of minimally invasive surgical techniques for treating patients with chronic venous insufficiency in the stage of trophic disorders: comparative study

Introduction. Despite the active introduction of minimally invasive techniques into modern phlebology, the problem of surgical treatment of chronic venous insufficiency (CVI) in the stage of trophic disorders is still far from being finally resolved, especially problems of horizontal reflux. Aim. Тo comparatively evaluate the results of using various tactics of minimally invasive surgical treatment in patients with lower extremitiesʹs CVI in the stage of trophic disorders.Materials and methods. A study at 139 patients with CVI at the stage of trophic disorders was carried out. Group 1 (n = 79) included patients who underwent endovasal laser coagulation of the trunks of the great and small saphenous veins (GSV and SSV) with microfoam sclerotherapy of varicose perforating veins. In group 2 (n = 60) – method of intervention was determined by the diameter of Cockettʹs perforants.Results. Indicators of the early postoperative period in the study groups were comparable. After 2 months, no cases of relapse in the GSV and SSV were registered. Recurrence of horizontal reflux was observed only in 6 (7.6%) people in group 1. In long-term postoperative follow-up, decrease in the severity of the disease according to the VCSS scale was found in both groups (p < 0.001). The persistence of pathological reflux along was observed in 16 (22.5%) patients of group 1. Moreover, in 62.5% and 68.75% cases of relapses, the perforants had, respectively, a large diameter and high blood flowʹs speed.Discussion. In general, minimally invasive techniques used demonstrated comparable clinical results and high efficiency. At the same time, the importance of preoperative assessment and taking into account the properties of perforants has been proven.Conclusion. The claimed method should be considered as an effective and safety method of obliteration of incompetent perforating veins at severe forms of CVI.

Numerical simulation of jet boiling characteristics of high-pressure water injected into high-temperature liquid lead–bismuth in a confined space

The steam generator heat transfer tube rupture (SGTR) accident is potentially devastating and is one of the most serious design basis accidents for lead–bismuth cooled fast reactor (LFR). It is important to study the mechanism of water jet injecting into liquid lead–bismuth eutectic (LBE) for the safety analysis of SGTR accidents. In this paper, based on the volume of fluid (VOF) model, the large eddy simulation (LES) turbulence model and the Lee phase transition model, a three-dimensional numerical model is developed to investigate the typical characteristics of a high-pressure sub-cooled water jet injecting into high-temperature LBE in a confined space. The study focuses on examining the impact of water temperature, inlet pressure, and nozzle diameter on jet development and its surroundings, including the cover gas layer and LBE phase. The results indicate that the central region of the jet is primarily subject to flash boiling, particularly at the nozzle position, whereas the jet interface undergoes heat-transfer boiling. The residual liquid phase migrates upward along the interface and gradually boils. Based on the phase distribution characteristics, a typical jet can be categorized into four zones: the water-steam transition zone, the multiphase flow zone, the end water phase zone, and the steam block zone. Under the conditions analyzed in this paper (water temperature 140–260 °C, injection pressure 2–10 MPa, nozzle diameter 2–10 mm, LBE temperature 400 °C), the jet volume expands approximately exponentially, correlating positively with the three factors studied. It is also found that at high injection pressures and large nozzle diameters, the steam at the top of the jet is prone to destabilization and fragmentation, with steam volume and pressure oscillations being the dominant factors. Steam migration triggers pressure oscillations in the LBE region, and the intensity of these oscillations is closely linked to the migration rate. Under the conditions studied, the maximum pressure oscillation reached 5.5 times the initial pressure. The expansion of the jet steam drives the pressurization of the cover gas layer, which correlates positively with all three factors studied. The nozzle diameter has the greatest effect, increasing the maximum pressure by 168 % from the initial pressure.

Hydrogeological characterization of low permeability medium for conceptualization of a mine site in Eastern Turkey

The mining site in Eastern Anatolia of Turkey were encounter a significant risk of slope instability within the operational area. One of the processes that govern slope stability is the pore water pressure distribution. The conceptualization and characterization of porous media serve as fundamental prerequisites for the implementation of numerical methods aimed at predicting pore water distribution. This study aims to characterize the hydrogeological properties of water bearing rocks in the active mining site in Eastern Anatolia of Turkey. A total of 21 wells and drill holes were drilled in the study area to conduct in-situ tests, monitoring, and sampling. The large diameter wells drilled in surrounding the carbonate rocks were to determine the groundwater flow and boundary conditions and also wells tapped metasediments and diorite unit for hydraulic testing. The lugeon tests and installation of vibrating wire piezometers were carried out at small diameter drill holes to obtain localized hydraulic conductivity of metasediments and diorite at different depths and monitoring pore water pressure distribution along some critical cross-sections. The results obtained from these tests are used for developing hydrogeological conceptual model for groundwater flow. The results of in-situ tests show that the metasediment and diorite units act as a single hydrostratigraphic unit. The metasediments and diorite have high total porosity and low specific yield indicating that the pore water is retained by electrostatic forces in the medium and it resists flow due to low hydraulic conductivity. The vertical variation in hydraulic conductivity values indicates that the medium is highly heterogeneous.

Off-label use of Lumen-apposing metal stents for treatment of short benign biliary strictures

BackgroundEndoscopic stenting is the mainstay of treatment for benign biliary strictures. There is a not-negligible rate of recurrence and stent migration. Lumen-apposing metal stents (LAMS) have a unique design with short length, large diameter and wide flanges which make them less prone to migration. AimsTo describe the intraluminal use of LAMS to treat short benign biliary strictures. MethodsAll consecutive patients who underwent bi-flanged LAMS placement for benign biliary strictures, in approximately 6 years, were retrospectively included. Primary outcomes were technical and clinical success; secondary outcomes were number of endoscopic procedures, adverse events evaluation and stricture recurrence during follow-up. ResultsSeventy patients (35 male, mean age 67) were enrolled; bilio-enteric anastomotic stricture was the most common etiology. Technical and clinical success were 100 % and 85.7 %, respectively. Patients with post-surgical stricture had a higher success rate than patients with non-surgical stricture or with bilio-enteric anastomotic stricture (90.4 %, 86.3 % and 81.4 %, respectively). Adverse events were 12/70 (17.1 %): stent migration was the most frequent (8/70, 11.4 %). Stricture recurrence was found in 10/54 patients (18.5 %). ConclusionLAMS placement could be safe and effective treatment for short benign biliary strictures in patients in which a significant caliber disproportion between stricture and the duct above was revealed.

Metabolomics analysis of different diameter classes of Taxus chinensis reveals that the resource allocation is related to carbon and nitrogen metabolism

Taxus chinensis (Taxus cuspidata Sieb. et Zucc.) is a traditional medicinal plant known for its anticancer substance paclitaxel, and its growth age is also an important factor affecting its medicinal value. However, how age affects the physiological and metabolic characteristics and active substances of T. chinensis is still unclear. In this study, carbon and nitrogen accumulation, contents of active substances and changes in primary metabolites in barks and annual leaves of T. chinensis of different diameter classes were investigated by using diameter classes instead of age. The results showed that leaves and barks of small diameter class (D1) had higher content of non-structural carbohydrates and C, which were effective in enhancing defense capacity, while N content was higher in medium (D2) and large diameter classes (D3). Active substances such as paclitaxel, baccatin III and cephalomannine also accumulated significantly in barks of large diameter classes. Moreover, 21 and 25 differential metabolites were identified in leaves and barks of different diameter classes, respectively. The differential metabolites were enhanced the TCA cycle and amino acid biosynthesis, accumulate metabolites such as organic acids, and promote the synthesis and accumulation of active substances such as paclitaxel in the medium and large diameter classes. These results revealed the carbon and nitrogen allocation mechanism of different diameter classes of T. chinensis, and its relationship with medicinal components, providing a guidance for the harvesting and utilization of wild T. chinensis.

An enhanced understanding of the lateral response of large-diameter monopile: Development of a new P-y curve

The present design practices of laterally loaded monopiles tends to discretize the pile into a series of beam elements and connect each element to uncoupled non-linear springs, or P-y curves, to represent soil reactions. The prevailing design codes tend to support the use of a universal P-y curve irrespective of pile configuration, flexural rigidity, and soil rigidity index. However, accumulating evidence suggests otherwise, underscoring the imperative to revise formulas, especially for large diameter rigid monopiles. This study conducts a thorough examination of load transfer and failure mechanisms in large diameter monopiles subjected to monotonic lateral loading in clayey soil. A refined formula is proposed to estimate ultimate net soil resistance, rectifying deficiencies in prevailing design codes prone to underestimation. Findings reveal significant influence of soil rigidity index on the P-y curve of rigid monopiles. Consequently, endeavours are undertaken to develop a new P-y formulation integrating the pivotal role of soil rigidity index. The newly devised P-y curve is anticipated to propel advancements in the design of large diameter monopiles, pivotal in offshore renewable energy exploitation.

Femtosecond laser direct writing large-area fiber Bragg grating based on diaphragm shaping

We propose and demonstrate a new method of direct writing large-area fiber Bragg grating by femtosecond laser through the coating. By adding an adjustable diaphragm before the focusing objective, we can precisely control the length of the refractive index modulation line along the femtosecond laser incident direction up to 29.1 µm. In combination with femtosecond laser scanning fabrication technology, a uniform refractive index modulation plane can be inscribed in the fiber in a single scanning. Based on the plane-by-plane inscription method, we have fabricated a high-quality high-reflectivity fiber Bragg grating and a chirped fiber Bragg grating on 20/400 double-clad fiber core. The reflectivity of both gratings is greater than 99%, and the insertion loss is as low as 0.165 dB and 0.162 dB, respectively. The thermal slope of chirped fiber Bragg grating without any refrigeration is 0.088 °C/W and there is no obvious temperature increase when using the water cooling. Therefore, the fabrication method of large-area fiber Bragg grating based on diaphragm shaping can efficiently fabricate high-quality fiber Bragg grating in the large core diameter fiber, which has an important application prospect in high-power all-fiber oscillators, especially all-fiber oscillators in special wavebands.

Treatment of intracranial aneurysms with large-diameter (≥5.5 mm) Derivo Embolization Devices, with particular focus on 7 and 8 mm diameter devices.

There are few studies on flow diverters with diameters >5 mm. We present our preliminary experience with the 5.5-8 mm Derivo Embolization Device (DED) implants for the treatment of cerebral aneurysms. A consecutive series of 26 patients (median age: 60 years) treated for 32 aneurysms in 26 procedures was retrospectively analyzed for procedural characteristics, complications, and mid-term angiographic results. The median aneurysm size was 10.5 mm, 2 of 30 (6%) aneurysms were ruptured and 9 (28%) had a fusiform or dissecting morphology. DED implantation was performed in the internal carotid artery in 18 of 26 (69%) procedures and in the vertebrobasilar artery in 8 (31%). Device deployment failed in 1 (4%) procedure. The 7 and 8 mm implants were successfully deployed in 5 cases. Additional balloon angioplasty or stent implantation was performed in 3 (12%) cases to improve wall apposition. Complications included 1 (4%) major stroke and 2 (8%) minor strokes. Angiographic follow up at a mean of 6 months showed complete occlusion in 8 of30 (27%) aneurysms and favorable occlusion in 14 (47%). The use of large diameter DEDs was safe and feasible. The mid-term occlusion rates are acceptable considering the complex subset of aneurysms studied. Further studies are warranted to define the indications for large-diameter DEDs and to evaluate their long-term efficacy.

Cu-BTC Derived Mesoporous CuS Nanomaterial as Nanozyme for Colorimetric Detection of Glutathione.

In this paper, Cu-BTC derived mesoporous CuS nanomaterial (m-CuS) was synthesized via a two-step process involving carbonization and sulfidation of Cu-BTC for colorimetric glutathione detection. The Cu-BTC was constructed by 1,3,5-benzenetri-carboxylic acid (H3BTC) and Cu2+ ions. The obtained m-CuS showed a large specific surface area (55.751 m2/g), pore volume (0.153 cm3/g), and pore diameter (15.380 nm). In addition, the synthesized m-CuS exhibited high peroxidase-like activity and could catalyze oxidation of the colorless substrate 3,3',5,5'-tetramethylbenzidine to a blue product. Peroxidase-like activity mechanism studies using terephthalic acid as a fluorescent probe proved that m-CuS assists H2O2 decomposition to reactive oxygen species, which are responsible for TMB oxidation. However, the catalytic activity of m-CuS for the oxidation of TMB by H2O2 could be potently inhibited in the presence of glutathione. Based on this phenomenon, the colorimetric detection of glutathione was demonstrated with good selectivity and high sensitivity. The linear range was 1-20 μM and 20-300 μM with a detection limit of 0.1 μM. The m-CuS showing good stability and robust peroxidase catalytic activity was applied for the detection of glutathione in human urine samples.

Synthesis of Copper Supported on Natural Rubber-derived Mesoporous Carbon/Silica Composite for Efficient Adsorption of Caffeine

Caffeine (CAF) removal from water resources is important because it is widely distributed and can be toxic to aquatic life. The copper supported on mesoporous carbon/silica composite (Cu/MCS) in this research was developed as a novel adsorbent to remove caffeine from aqueous solutions. The Cu/MCS material was prepared in two steps. The first step was the preparation of a precursor consisting of copper and natural rubber distributed inside a hexagonal mesoporous silica matrix (Cu/NR/HMS). Then, the composite was carbonized at high temperature under inert gas conditions to obtain Cu/MCS material. The amount of Cu loading in the MCS structure was studied. The Cu/MCS composites revealed a high level of copper distribution incorporated into the mesoporous carbon/silica framework as confirmed by Powder X-ray diffraction (XRD) and Scanning Electron Microscope and Energy Dispersive X-ray Spectrometer (SEM-EDS). The Cu/MCS materials possessed a high specific surface area (523–748 m2 g−1), large pore volume (0.80–0.86 cm3 g−1) and mesoporous diameter (3.07-3.30 nm). Fourier Transform Infrared Spectroscopy (FT-IR) and CHN analysis revealed a high amount of carbonaceous species dispersed in the Cu/MCS material. The Cu (0.010)/MCS, with copper loading of 1 mmol/g, revealed good properties for CAF removal when compared to other series of Cu/MCS adsorbents. Moreover, the Cu (0.010)/MCS composite exhibited the maximum adsorption capacity for CAF as 55.8 mg/g.

Application of super large and deep diameter assembly shafts in soft soil layers

Considering the background of the Shanghai Jing’an Smart Garage Project, first, we introduced the world’s largest vertical shaft boring machine, which was suitable for vertical shaft excavation of diameter 12∼23 m. Then, we expounded the design points and key technologies of super large and deep diameter assembly shafts in soft soil layers. Finally, we verified the applicability of the vertical shaft boring technology in soft soil layers in Shanghai through on-site measurement results. It was observed that this technology had a minimal impact on the surrounding environment, indicating its potential for widespread applications in the coming years.

Procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 promotes collagen cross-linking and ECM stiffening to induce liver fibrosis

Procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (Plod2) is a key collagen lysyl hydroxylase mediating the formation of collagen fiber and stabilized collagen cross-links, and has been identified in several forms of fibrosis. However, the potential role and regulatory mechanism of Plod2 in liver fibrosis remain unclear yet. Mouse liver fibrosis models were induced by injecting carbon tetrachloride (CCl4) intraperitoneally. The morphology and alignment of collagen was observed under transmission and scanning electron microscopy, and extracellular matrix (ECM) stiffness was measured by atomic force microscopy. Large amounts of densely packed fibrillar collagen fibers produced by myofibroblasts (MFs) were deposited in fibrotic liver of mice reaching very large diameters in the cross section, accompanied with ECM stiffening, which was positively correlated with collagen-crosslinking. The expression of Plod2 was dynamically up-regulated in fibrotic liver of mouse and human. In MFs transfection of Plod2 siRNA made collagen fibers more orderly and linear aligned which can be easily degraded and protected from ECM stiffness. Administration of Plod2 siRNA preventatively or therapeutically in CCl4 mice reduced the average size of collagen bundles in transverse section, increased collagen solubility, decreases the levels of crosslinking products hydroxylysylpyridinoline and lysylpyridinoline, prevented ECM stiffening and alleviated liver fibrosis. Altogether, Plod2 mediates the formation of stabilized profibrotic collagen cross-links in MFs, leading to the alteration of collagen solubility and ECM stiffness, and eventually aggravates liver fibrosis, which provide potential target for the treatment of liver disease.

Longitudinal structural behavior of shield tunnel with large diameter and small curvature

The structural mechanism of a large-diameter curved tunnel is introduced in detail because no relevant calculation method is available. A longitudinal discontinuous contact model is established based on the newly built North Highway Tunnel in Shanghai, China. First, the load-spreading mechanism of circumferential joints was considered. Second, the distribution laws of the longitudinal internal force, settlement, and joint deformation of curved and straight tunnels under the same load were analyzed and compared. Finally, a model test is conducted to verify the effectiveness of the discontinuous contact model. The results indicated that with an increase in the radius of curvature, the maximum internal force and deformation decreased. The internal forces and deformations of straight and curved tunnels are quite different; therefore, the design method for a straight tunnel cannot be used in the design of curved tunnels. The overall and local deformations of the curved tunnel were affected by end displacement.

Long-term results of liver thermal ablation in patients with hepatocellular carcinoma and colorectal cancer liver metastasis regarding spatial features and tumor-specific variables

Colorectal cancer liver metastasis (CRLM) and hepatocellular carcinoma (HCC) are widely treated using microwave and radiofrequency ablation. Local tumor progression (LTP) may develop depending on the shortest vascular distance and large lesion diameter. This study aims to explore the effect of these spatial features and to investigate the correlation between tumor-specific variables and LTP. This is a retrospective study covering the period between January 2007 and January 2019. One hundred twenty-five patients (CRLM: HCC: 64:61) with 262 lesions (CRLM: HCC: 142:120) were enrolled. The correlation between LTP and the variables was analyzed using the chi-square test, Fischer's exact test, or the Fisher-Freeman-Halton test where applicable. The local progression-free survival (Loc-PFS) was analyzed using the Kaplan-Meier method. Univariable and multivariable Cox regression analyses were performed to identify prognostic factors. Significant correlations were observed for LTP in both CRLM and HCC at a lesion diameter of 30-50 mm (P = 0.019 and P < 0.001, respectively) and SVD of ≤3 mm (P < 0.001 for both). No correlation was found between the ablation type and LTP (CRLM: P = 0.141; HCC: P = 0.771). There was no relationship between residue and the ablation type, but a strong correlation with tumor size was observed (P = 0.127 and P < 0.001, respectively). In CRLM, LTP was associated with mutant K-ras and concomitant lung metastasis (P < 0.001 and P = 0.003, respectively). In HCC, a similar correlation was found for Child-Pugh B, serum alpha-fetoprotein (AFP) level of >10 ng/mL, predisposing factors, and moderate histopathological differentiation (P < 0.001, P = 0.008, P = 0.027, and P < 0.001, respectively). In CRLM, SVD of ≤3 mm proved to be the variable with the greatest negative effect on Loc-PFS (P = 0.007), followed by concomitant lung metastasis (P = 0.027). In HCC, a serum AFP level of >10 ng/mL proved to be the variable with the greatest negative effect on Loc-PFS (P = 0.045). In addition to the lesions' spatial features, tumor-specific variables may also have an impact on LTP.

The Intrinsic Sizes of Odd Radio Circles

A new class of sources, the so-called odd radio circles (ORCs), have been discovered by recent sensitive, large-area radio continuum surveys. The distances of these sources have so far relied on photometric redshifts of optical galaxies found at the centers of or near ORCs. Here we present Gemini rest-frame optical spectroscopy of six galaxies at the centers of, or potentially associated with, the first five ORC discoveries. We supplement this with Legacy Survey imaging and Prospector fits to their griz+W1/W2 photometry. Of the three ORCs with central galaxies, all lie at distances (z = 0.27–0.55) that confirm the large intrinsic diameters of the radio circles (300–500 kpc). The central galaxies are massive (M * ∼ 1011 M ☉), red, unobscured ellipticals with old (≳1 Gyr) stellar populations. They have LINER spectral types that are shock-powered or active galactic nucleus (AGN)-powered. All three host low-luminosity, radio-quiet AGN. The similarity of their central galaxies is consistent with a common origin, perhaps as a blast wave from an ancient starburst. The other two ORCs are adjacent and have no prominent central galaxies. However, the z = 0.25 disk galaxy that lies between them hosts a Type 2, moderate-luminosity AGN. They may instead be the lobes of a radio jet from this AGN.

Numerical study of borehole instability of large diameter monopile during the window period between drilling and pile driving

Large-diameter monopiles are among the most widely used offshore wind turbine foundations. Implementing drive-drill-drive construction techniques in a decomposed granite seabed may lead to borehole instability during the window period between drilling and pile driving. In this study, the borehole stability of a large-diameter monopile in a weathered granite seabed was investigated using the discrete element method. A linear parallel bond model was employed to simulate the bonding effect among weathered granite particles, and the influence of pore water was considered. The results indicated that soil shear failure caused by excavation unloading was the primary cause of borehole instability. The exposed height of the unsupported borehole significantly influenced the occurrence of borehole instability. The greater the exposed height of the unsupported borehole, the larger the soil arch required to maintain the stability of the borehole, and the less stable the soil arch becomes. Moreover, the susceptibility to borehole instability and collapse also increased.