Large Diameter Research Articles

Buckling load optimization of sandwich plates with trapezoidal corrugated core and elliptical cutout using vibration correlation techniques and artificial neural network; experimental and numerical analysis

The present research was carried out in order to estimate the buckling load of a sandwich plate with a trapezoidal corrugated core with cut-out using three vibration correlation techniques (VCT). The structure investigated in this research is a sandwich plate with a trapezoidal core and an oval cut-out, which is made of thermoplastic polymer using a 3D printer. By using artificial neural network (ANN) and genetic algorithm (GA), the specific critical buckling load (p¯cr) which is defined as the ratio of critical buckling load (Pcr) to plate weight (gr) has been minimized and the optimal dimensions for cut-out parameters including the ratio of the large diameter of the ellipse (z=20mm) to the small diameter of the ellipse (b) and oval angles with the horizontal axis (a∘) are obtained. Using the method of equivalent properties, the trapezoidal core is transformed into an equivalent orthotropic core and finally the desired structure is transformed into a three-layer sandwich plate including homogeneous upper and lower layers and an orthotropic middle layer. By using the meshless method based on radial and polynomial functions and with the help of the finite element method, the numerical simulation of buckling and free vibration of the sandwich plate has been done. The results showed that the estimation of the buckling load with the vibration correlation technique (VCT) corresponds to the actual condition of the structure, so that due to the high quality of sandwich plate construction and its integrity, the results obtained from the first, second, and third methods of the VCT show the effectiveness of this method for predicting of the buckling load of the structure.

A resilience optimization design model considering surcharge for large diameter shield tunnel

Large-diameter shield tunnels face challenges owing to the complex strata and surcharges. The robustness of ground disturbance during excavation and resilience during operation in the design model must be considered. This involves establishing a damage evolution law for existing shield tunnels after surcharging and proposing a resilience design method for the entire cycle. In this study, the design process was initiated by utilizing existing borehole survey information and incorporating stratum uncertainty. Subsequently, a ground surcharge was applied to evaluate the changes in the force and deformation at different design points after surcharging. A resilience assessment was conducted in accordance with the specified criteria, and the results indicated that a majority of the design points exhibited robustness within acceptable limits after the surcharge. The original excavation design demonstrated satisfactory initial performance in terms of robustness. However, the resilience after surcharging was suboptimal, exhibiting a value of only 0.65. To enhance the resilience, the design must modify the reinforcing rate to achieve a higher resilience state of 0.8. By considering both the robustness of the design and its resilience after surcharging, modifications can be made to align the design with real operational conditions, which may help improve the overall resilience.

Persistent iatrogenic atrial septal defect after cryoballoon ablation for atrial fibrillation

Aims: Pulmonary vein isolation (PVI) by cryoballoon ablation (CB) technology is effective and safe treatment option for atrial fibrillation (AF). CB is performed by large diameter, 15Fr (4.95mm) transseptal sheath that may lead to creation of iatrogenic atrial septal defect (iASD). The objective of this study was to assess the incidence of iASD in patients who had undergone CB. Methods: Patients with AF having undergone Arctic Front® CB ablation and a subsequent transesophageal echocardiography (TEE) examination during post-ablation follow up period were consecutively enrolled. During all CB procedures, 15Fr transseptal sheath (Flex Cath, Medtronic, Minneapolis, MN) was utilized via single transseptal puncture (TsP). Results: Twenty-eight patients (15 females, mean age 55.8+15.5) with paroxysmal (n=24) or persistent (n=4) AF formed study group. iASD was present 11 (39.3%) of them after mean follow-up time of 17.3+6.2 months. The procedural time is significantly longer in patient with iASD (119.0+8.8 minutes, p=0.01). No patients died or suffered from any clinically significant cerebral ischemic event. There was no sign of increase in systolic pulmonary arterial pressure (sPAP). Conclusion: iASD after CB was found to be present in 39.3% of patient during a mean follow-up time of 17.3+6.2 months. The prolonged CB procedural time was the only factor that predicted iASD in our study. No adverse clinic events that might be related to iASD was observed during follow-up period.

A rare case of neuroendocrine cell tumor mixed with a mucinous component in the ampulla of Vater

BackgroundA rare case of neuroendocrine cell tumor (NET) having both conventional and mucinous components was reported. Mucinous NET is rarely encountered in the pathological diagnosis of gastrointestinal (GI) tumors. Here we examined the mechanism for transformation of conventional NETs into mucinous NETs. Case presentation: Macroscopic examination revealed a tumor with ulceration in the ampulla of Vater that measured 1.7 cm in its largest diameter. Histologically, the tumor comprised two components: a tubular/ribbon-like feature and small nests floating in a mucinous lake. The tumor nests showed sheet, nest and ribbon-like structures of small cells having eosinophilic cytoplasm as well as small-sized nuclei with dense hyperchromatin. Immunohistochemical analysis showed tumor cells positive for pan-endocrine markers (synaptophysin, CD56, INSM1 and chromogranin). Based on the histological findings, the solid and mucinous components were diagnosed as conventional and mucinous NETs, respectively. Grading was NET G2 based on 12.8% and 13.2% Ki-67-positive cells in the solid and mucinous components, respectively. Immunohistochemically, the mucin phenotype of this tumor was gastric and intestinal. Only the mucinous NET component had cytoplasmic CD10 expression. Examination using a customized gene panel detected only a DPC4 mutation, which was limited to the mucinous component. Conclusions: Coexistence of conventional and mucinous NETs could provide important insight into evaluating the NET subtype histogenesis. Moreover, molecular alterations including cytoplasmic expression of CD10 and the DPC4 mutation can contribute to interpretation of tumor pathogenesis.

Description and Characteristics of Ocular Tumor Lysis Syndrome

Introduction: The aim of the study was to describe and evaluate characteristics of ocular tumor lysis syndrome (OTLS) in eyes with uveal melanoma. Methods: Retrospective chart review of all patients with OTLS at the University of Colorado from 2009 to 2021. Data collected included patient demographics, tumor characteristics, radiation dosimetry, gene expression profiling (GEP), OTLS characteristics, management, and outcomes. Results: Seven eyes of seven patients with uveal melanoma treated with I-125 brachytherapy developed OTLS. Average age was 59 years (range 32–83). Mean apical height was 8.6 mm (range 6–11); mean diameter was 12.7 mm (range 8.5–15.3). All tumors were treated with plaques ≥16 mm in diameter. On presentation, 5/7 tumors had subretinal fluid, and 6/7 had collar-button configuration. OTLS presented as extensive pigment dispersion in the vitreous in all eyes, subretinal pigment and/or retinal detachment in 4/7 eyes, vitreous hemorrhage in 2/7 eyes, and anterior chamber pigment in 3/7 eyes. Four tumors were GEP class 1, two were class 2, and one was unclassified. Biopsy route was trans-scleral in 4/7 eyes and trans-vitreal in 3/7 eyes. OTLS occurred 2–4 weeks after an intraocular procedure in 5/7 eyes. All underwent pars plana vitrectomy. Cytology of the vitreous, obtained in five cases, showed pigment laden macrophages and hemorrhage, but only 1/5 eyes had viable malignant cells. Four eyes were stable at the last follow-up, two were enucleated, and one had no light perception from pigmentary glaucoma. Poor vision (<20/200) occurred in 6/7 cases. Three patients died from metastasis (tumors were GEP class 2, GEP class without subclassification, and no GEP classification performed). Conclusions: OTLS is a rare but devastating complication of uveal melanoma. Common characteristics included large plaque diameter, presence of subretinal fluid, and collar-button shape. The extensively dispersed pigment is typically not malignant. Though poor vision is common, enucleation may be avoided in most eyes through vitreoretinal surgical repair.

Air-blast atomization of a liquid film

Air-blast atomizers are extensively used for a variety of purposes. Due to its complexity, the atomization mechanism has not been elucidated. In this study, a mechanistic model is proposed to predict the droplet diameter distribution based on the atomization process of a planar liquid film with co-current gas flows, and its validity is examined by comparing the estimated and measured droplet diameters using high-speed image analysis and laser measurement. As a result, using high-speed imaging, we clarified that the bag film rupture is caused not by the turbulence of the gas flow but by the impact of floating droplets on the liquid film of the expanding bag when the film is thin enough. The average thickness of the liquid film at the bag breakup is of the order of micrometres and varies greatly, resulting in a dispersed distribution of droplet diameters. After the film ruptures, the bag film shrinks towards its transversal and vertical rims due to surface tension, forming large-diameter ligaments. During the contraction process of the bag film, tiny droplets of the order of micrometers are formed at the edge of the perforation. Finally, the remaining ligaments with large diameters fragment into large droplets with submillimetre diameters. The good agreement between the measured and predicted droplet diameter distributions validated the mechanistic model.

The Effect of Swirl Number on Lean Blow Out Limits of Lean Direct Injection Combustors

Abstract This is the first study where a single variable sweep of SN is conducted to assess its impact on lean blowout limits (LBO) in a liquid-fueled lean direct injection (LDI) combustor. This study uses a scaled NASA SV-LDI (Swirl Venturi—Lean Direct Injection) hardware and is concerned with the impact of swirl number on the lean blow-out limit of a single-element LDI system at atmospheric pressure. The swirl numbers (SN) were varied from 0.31 to 0.66 using continuously variable active swirl number control system that was developed in-house. It is shown that the minimum operating equivalence ratio is a linearly increasing function of swirl number. While previous literature agrees with the positive slope for this correlation, past work has suggested that the LBO limit is proportional to the swirler vane angle which is shown to be untrue for LDI systems. By actively varying the swirl number, it is proven that LBO is proportional to SN, and it is well known that SN is not proportional to swirler vane angle. Increased SN reduces LBO margin because the better-mixed, high swirl dilutes locally rich pockets of fuel–air mixture in a globally lean flow. In addition to a baseline venturi, which was scaled from NASA's geometry, two other venturis were tested. A low-pressure loss venturi with a large throat diameter showed poor blow-out performance whereas a parabolically profiled venturi improved LBO over the baseline for the same swirl number.

Gross pathology of brain mass lesions by intraoperative ultrasonography: a comparative study

BackgroundThe purpose of this study was to evaluate the ability of intraoperative ultrasound (IOUS) to differentiate the gross pathological features of brain mass lesions in comparison with preoperative imaging and confirmable histopathological results.ResultsA total of 365 patients were operated on for brain mass lesions removal from May 2017 to May 2022 under the guidance of intraoperative ultrasound with transducers 2.5–8 megahertz (MHZ). Ultrasound gross pathological findings were compared to the preoperative imaging and the confirmable histopathological results. Intraoperative ultrasound defined either internal or external gross pathological features of all brain mass lesions. The IOUS showed spontaneous enhancements of the brain abscess walls, which were equivalent to contrasted CT and MRI. Significantly large diameters were noted in the IOUS measurement of abscesses in comparison with CT and MRI (P = 0.001). The walls of the brain abscesses were significantly well defined in IOUS imaging in comparison with CT (P = 0.001) and equivalent to MRI. IOUS showed equivalent significance to CT and MRI in characterizing intra-parenchymal hematomas. Significantly large diameters were noted in the IOUS measurement of hematomas in comparison with CT and MRI (P = 0.001). IOUS showed significant definition of brain tumors in comparison with CT and MRI regarding tumor edge definition, tumor contours, necrosis, and cystic components (cystic definition, cystic multiplicity, cystic trabeculations, and cystic wall thickness) (P = 0.001). IOUS was equivalent to CT and MRI regarding intra-tumoral hematomas and brain edema. IOUS was equivalent to CT regarding calcification detection. The significant criteria for high-grade brain tumors versus low grade by IOUS were: P = 0.001 (necrosis, brain edema, rare calcifications, presence of cystic components, thick cystic walls, large diameter, hypo-echogenicity, and heterogeneity); P = 0.002 (cystic trabeculations); P = 0.005 (multiple cysts); and P = 0.03 (irregular contour). IOUS can characterize brain tumors and suspect specific and significant criteria for many types with great overlap.ConclusionsIntraoperative ultrasound has the ability to differentiate the gross pathological features of brain mass lesions in comparison with preoperative imaging and confirmable histopathological results.

Assessing prestressed anchor cable support as ore pillar alternatives in stope span expansion: A case study

In large diameter long-hole (LDL) stopes, ore pillars are often set up in the rock drilling chamber to expand the span. However, after the ore pillars are blasted along with the stope, the stability of the roof is difficult to control, and collapse often occurs. This study introduced the idea of employing PAC support technology to replace the traditional ore pillar support and conducted site investigations, theoretical analysis, numerical simulations, and field tests to develop a technology for expanding the span of LDL stope based on prestressed anchor cable (PAC) support. Following a detailed investigation of pillar-supported LDL stope roof collapse events and geological conditions, a mechanical model for the stress arch considering the lateral stress coefficient was developed combining the failure characteristics and deep conditions, and the inverse relationship between the lateral coefficient of ground stress and the height of the stress arch above the opening was determined. Numerical simulation results demonstrate that the elliptical parabolic stress arch mechanical model has been verified, and PAC effectively controls roof stability, as evidenced by displacement and plastic zone response. Field tests were carried out utilizing PAC support, and monitoring results affirm the PAC support system's efficacy in stabilizing the roof. Using PAC to replace ore pillars resulted in a remarkable 29.8 % improvement in blast hole drilling efficiency and reduced ore dilution rate within the stope from 22.3 % to 14.2 %. This study serves as a reference for addressing analogous challenges in other mining operations.

Investigation on a mobile fire extinguishing approach using liquid carbon dioxide as inert medium for underground mine.

Injecting carbon dioxide is the most effective means of preventing and extinguishing fires in sealing hazardous areas, but the traditional method slowly and remotely injects carbon dioxide gas into the well after gasification on the ground, which is dependent on the complete mine pipe network without cooling effect. To inject liquid directly from the tank with vacuum interlayer and heat insulating powder for rapid inerting and cooling, a new approach using track mobile platform to go deep into the underground mine disaster area is proposed, so the liquid can be delivered to the nozzle at the end of DN40 large diameter pipe, and the continuous gasification jet can be realized. The experimental results show that: (1) The liquid volume in a tank of vacuum degree within 2.0 Pa and 200 mm interlayer reduced no more than 15.5% after 48 days; (2) Taking the pressure in the tank as the power source, because of environmental differences inside and outside the pipe after 100 m pressure holding delivery, the physical form of liquid and gas could be converted instantly; (3) The continuous discharge time without ice blocking for a tank full of 2 m3 liquid was about 10.5 min under 25 L dual mode nitrogen pressurization, which is 1/12 of injection time after ground gasification; (4) Based on the temperature decrease trend measured at different positions, the cooling characteristics on liquid gasification jet path are quantified, and the calculation formula of temperature changing with time on the center line of liquid gasification jet is obtained. Through this new approach, the integration of vacuum insulated storage, safe mobile transportation, and continuous and rapid release with large flow can be achieved for the liquid carbon dioxide.

Practical Considerations in the Design of Passive Free Piles in Sliding Soil

The stabilisation of shallow translational landslides can be carried out by using large diameter concrete piles, with the aim of increasing the available strength along the slip surface. In the following article, 3D numerical models of a free-head flexible pile embedded into a translational type of landslide are studied. The landslide model has a given inclination angle, β, and a thickness, D, while the reinforced concrete pile has a fixed diameter, d, and a length, D + L, in the perspective of studying the failure modes B1, BY and B2 of free-head flexible piles. In this category of piles, collapse is reached with the formation of plastic hinges. Both the soil and the concrete are modelled with simple constitutive models, such as Mohr–Coulomb for soil and the elastic-perfectly plastic for the concrete pile, in order to carry out the design approaches provided by Eurocode, as well as to highlight some practical aspects of soil–structure interaction during the landslide displacements. The results highlight how the achievement of the shear strength in a flexible free-head concrete pile generally precedes the achievement of the ultimate bending moment associated with the development of plastic hinges. Furthermore, the axial load supported by the pile may itself contribute to the overall strength available along the slip surface.

Assessment for shallow and large tunnel construction in weak ground conditions: Application of tunnel boring machines

AbstractWith recent technological advancements, tunnel boring machines (TBM) have developed and exhibited high performance in large diameters and weak ground conditions. Tunnels are crucial structures that significantly influence the timelines of highway and railway projects. Therefore, the construction of tunnels with TBMs becomes a preferred option. In this study, a comparative analysis between TBM and the New Austrian Tunneling Method (NATM) for tunnel construction is performed in the construction of the T1 tunnel with a diameter of 13 m, which is the longest tunnel in the Eşme‐Salihli section of Ankara‐İzmir High‐Speed Railway Project (Türkiye). The selection of TBM type, measures taken in problematic sections, and application issues of TBM are discussed. The impact of correct description of geological and geotechnical conditions on both selection and performance of TBM is presented. An earth pressure balanced type TBM is chosen for the construction of the T1 tunnel. Because of the additional engineering measures taken before excavation in problematic areas, the tunnel was completed with great success within the initially planned timeframe. From this point of view, this study is an important case and may contribute to worldwide tunneling literature.

Effects of the geometric characteristics of graphene nanoplatelets on the physico-rheological properties of asphalt binder

While graphene nanoplatelets (GnPs) have emerged as promising nano-modifiers of asphalt binder in recent years, much is still unknown in terms of the existing correlations between the physical, chemical, and geometric characteristics of this nanofiller and observed asphalt binder properties. In this work, we investigate the important correlation between the geometric characteristics of GnPs and the rheological properties of the GnP-modified asphalt binder at high temperatures. Our results indicate that, in general, incorporating GnPs with large mean particle diameters (> 14 μm) and thicknesses (> 8 nm) enhances the high-temperature performance of the asphalt binder. The results of the multiple stress creep and recovery tests confirm that including GnPs in asphalt binder can decrease its permanent deformation by 33.2% and enhance its elastic recovery by 53.9%. Phase contrast images obtained by atomic force microscopy further indicate that the presence of GnPs with large mean particle diameters alters the morphology of the asphalt binder, leading to improved temperature stability and less susceptibility to permanent deformation.

Splice Length of Large Diameter Reinforcing Bars in Ultra-High-Performance Concrete

Potential exists for construction time savings through replacement of cast-in-place substructure columns, piers, or both, with prefabricated bridge elements and systems. Cast-in-place substructure construction requires forming, placing steel, and pouring concrete at the construction site. Using prefabricated elements would decrease the extent of work required at the site and potentially reduce concrete curing time. This research furthers the effort to use ultra-high-performance concrete (UHPC) as a joining material for prefabricated bridge substructure elements. UHPC has a high early strength, requires less development or splice length than conventional concrete, and has been used previously for accelerated construction projects, such as bridge deck replacement with precast units. UHPC also has a discontinuous pore structure that reduces liquid ingress, significantly enhancing durability compared to conventional concrete. Although UHPC has been researched extensively, previous research for reinforcing bar splice and development lengths has focused on #9 and smaller diameter bars. Typically, larger diameter bars are used for substructures. This research determined the required splice lengths for large diameter steel deformed reinforcing bars embedded in UHPC based on 127 individual tests. Three primary variables were included in the testing matrix: bar size, bar spacing, and concrete cover. To achieve at least 75 kips per square inch (ksi) (517 MPa) reinforcing bar stress in UHPC with an early age strength of 14 ksi (97 MPa), the required embedment length ranges from 8 to 13 times the bar diameter and the corresponding splice length varies from 6 to 11 times the bar diameter, depending on the bar size and concrete cover.

Clinical features of patients with metastatic pheochromocytoma/paraganglioma

Objective: To analyze the clinical features of patients with metastatic pheochromocytoma/paraganglioma (PPGL). Methods: A follow-up study. The clinical data of 250 patients with metastatic PPGL treated at Peking Union Medical College Hospital from January 2018 to August 2023 were retrospectively analyzed, including 124 males and 126 females. The clinical features and treatment status of patients with metastatic PPGL were summarized and analyzed. Kaplan-Meier survival curve was used to evaluate patients' prognosis. Results: The age of onset, age of diagnosis, and age of tumor metastasis in patients with metastatic PPGL were (33.1±14.2) years, (35.4±15.2) years, and (40.7±15.3) years, respectively. Metastasis occurred in 26.4%(66/250) of patients at the time of initial diagnosis. Among patients without metastases at the time of initial diagnosis, the time from primary tumor resection to metastasis[M(Q1, Q3)] was 5.0 (3.0, 9.0) years, among which 20.1%(37/184) of patients had metastases more than 10 years after surgery. Most patients showed increased 24-hour urinary norepinephrine and plasma normetanephrine, accounting for 78.2%(176/225) and 78.7%(85/108), respectively. 42.3%(69/163) of patients had increased neuron specific enolase (NSE)levels. Germline mutations were screened in 201 patients, of which 55.2%(111/201) had germline pathogenic mutations. In patients with gene mutations, 76.5%(85/111) had SDHB mutations. 52.0%(130/250) of metastatic PPGL patients had primary sites outside the adrenal gland, with the Ki-67 index of 5% (3%, 8%). There were 85.6%(214/250) patients had multisystem metastasis, with bone metastasis being the most common site of metastasis, accounting for 60.8%(152/250). In terms of treatment, 32.8%(75/229) of patients underwent two treatment regimens and 8.7%(20/229) of patients underwent three treatment regimens. Most patients had a good prognosis, with a 5-year and 10-year survival rate of 88.0% and 84.0%, respectively. However, some patients had rapid disease progression, and as of August 2023, 30 patients died, and the time from diagnosis to death in deceased patients was 2.0 (1.0, 4.0) years. Conclusions: Patients with metastatic PPGL have a high rate of germline mutations, especially those with SDHB mutations. The metastatic PPGL is usually multisystem metastasis with the characteristics of mostly paraganglioma, large lesion diameter and high Ki-67 index.

3D-CFD Modeling of Hollow-Fiber Membrane Contactor for CO2 Absorption Using MEA Solution.

Membrane technology is considered an innovative and promising approach due to its flexibility and low energy consumption. In this work, a comprehensive 3D-CFD model of the Hollow-Fiber Membrane Contactor (HFMC) system for CO2 capture into aqueous MEA solution, considering a counter-current fluid flow, was developed and validated with experimental data. Two different flow arrangements were considered for the gas mixture and liquid solution inside the HFMC module. The simulation results showed that the CO2 absorption efficiency was considerably higher when the gas mixture was channeled through the membranes and the liquid phase flowed externally between the membranes, across a wide range of gas and liquid flow rates. Sensitivity studies were performed in order to determine the optimal CO2 capture process parameters under different operating conditions (flow rates/flow velocities and concentrations) and HFMC geometrical characteristics (e.g., porosity, diameter, and thickness of membranes). It was found that increasing the membrane radius, while maintaining a constant thickness, positively influenced the efficiency of CO2 absorption due to the higher mass transfer area and residence time. Conversely, higher membrane thickness resulted in higher mass transfer resistance. The optimal membrane thickness was also investigated for various inner fiber diameters, resulting in a thickness of 0.2 mm as optimal for a fiber inner radius of 0.225 mm. Additionally, a significant improvement in CO2 capture efficiency was observed when increasing membrane porosity to values below 0.2, at which point the increase dampened considerably. The best HFMC configuration involved a combination of low porosity, moderate thickness, and large fiber inner diameter, with gas flow occurring within the fiber membranes.

Electrospinning-netting of spider-inspired polycaprolactone/collagen nanofiber-nets incorporated with Propolis extract for enhanced wound healing applications

Nanofibers hold significant promise for wound healing applications, but their potential is limited by their large diameter. To overcome this limitation, the development of nanofibrous systems with refined nanonets (approximately 20 nm in diameter) represents a notable improvement. In this study, a composite of polycaprolactone/collagen (PCLC) nano-fiber/nets (NFNs) was fabricated using benign solvents (acetic acid and formic acid) via the electro-spinning/netting (ESN) technique, harnessing the regenerative potential of collagen as a biological macromolecule. Additionally, to enhance the natural attributes of the NFNs structure, Propolis extract, renowned for its wound healing properties, was incorporated. Five ESN solutions were prepared: PCL, PCLC, PCLC/Pro 5 %, PCLC/Pro 10 %, and PCLC/Pro 15 %. NaCl salt was introduced into all ESN solutions to improve nanonets formation. FE-SEM imaging demonstrated successful nano-net formation in all ESN solutions except for the PCL formulation. The fabricated scaffolds exhibited spider-like nanonets with the addition of collagen and further enhanced nano-net formation with Propolis incorporation. Trunk nanofibers showed filamentous structures without any beads, with an average diameter of 164–728 nm, while the diameter of branched fibers (nanonets) was approximately 20 nm. WVTR values of the NFNs were comparable to commercial dressings such as Tegaderm. The results also demonstrated the potent cytoprotective effects of Propolis-loaded NFNs in a dose-dependent manner. Furthermore, the viability of HFF-2 cells after 72 h of culture on PCLC NFNs significantly increased compared to PCL nanofibers. The highest cell viability was observed in PCLC/Pro 15 % nanofibers after 24, 48, and 72 h of cell culture, indicating the proliferative effect of Propolis extract in nanoformulated form. Additionally, the scaffolds exhibited a hemocompatibility of <3 %, further highlighting their potential in wound healing therapeutics.

Influence of test methodology on the characterization of the parallel-to-grain timber embedment strength and foundation modulus of dowels

ABSTRACT A reliable determination of the embedment strength and foundation modulus of timber elements is critical for the design and safety assessment of joints in timber structures. However, the existence of various test configurations for characterising the embedding properties of large diameter steel fasteners in timber elements poses challenges in directly comparing and utilising available test data. This paper aims to provide an insight into the influence of embedment property test methods, comparing experimental results from different test setups within the guidelines of the EN 383 and ASTM D 5764-97a standards for European softwood species, Scots pine wood (Pinus sylvestris) and Norway spruce (Picea abies). In addition to the test guidelines, the thickness of the specimen and the application of the load was evaluated within the protocols. A comprehensive statistical analysis was performed to identify statistically significant differences between the groups evaluated. The results of the analysis revealed disagreement between the standards in the evaluation of the strength of the embedding, highlighting the potential bias inserted by the experimental setup and protocol. Furthermore, it was proven that the thickness of the specimens influences both the embedding strength and the foundation modulus of the wood species tested. Finally, no distinctions were observed between tensile and compressive loading within the guidelines of the EN 383 standard.

Field flattening concepts for linac cavities of the cross-bar H type

The development of cross-bar H-type cavities (CH-DTL, H21 mode) is ongoing to improve the technology of this attractive type of drift tube linac (DTL). In comparison with the conventional DTL, the H-type cavities can reach a higher effective field gradient and are competitive in shunt impedance at an energy range up to 100 A MeV. H-mode DTL’s profit in shunt impedance additionally when applying the KONUS beam dynamics. They are in use at research laboratories as well as at hospitals. This paper describes a new concept to approach the zero mode in CH-type cavities, by extending the cavity diameter at the tank ends in combination with tilted drift tube stems. RFQs of the four-vane type are operated as well in the H210 mode and the strategy for voltage flattening can be partly applied there too if conventional vane undercuts are causing problems. Up to around 35 MeV, it is attractive to integrate one or more triplet lenses into each cavity, as one KONUS section is relatively short and would not exploit the full rf power of 3 MW klystrons which are available above 300 MHz. Such a cavity is denoted as a coupled CH-cavity CCH. Three possible arrangements of those internal triplet lenses are discussed and are compared to each other. The operating modes as well as higher modes are then compared with a lens-free CH cavity, where the lens position was filled by ordinary drift tubes. As a result, it is shown that the rf behavior and resonance frequency for the higher harmonics of the frequency band are very similar for all four investigated arrays. This means, that the tuning behavior of the CCH cavity can be simply deduced from the lens-free CH cavity by replacing an even number of ordinary drift tubes (nβλ) with a lens-containing drift tube with adequate length and large outer diameter. This large drift tube itself oscillates like an Alvarez-type drift tube. rf simulations on a 30-gap CH cavity show that the reduction in shunt impedance is about 10% when installing a lens with length 2 beta lambda. Published by the American Physical Society 2024

Determinants of the economy in multistrata agroforestry in Ethiopia

Agroforestry represents a potentially multi-beneficial approach to land management as it may enhance a farming household’s income and income stability simultaneously with nutrition security and climate change mitigation. However, our comprehension of the specific characteristics within agroforestry systems that bolster economic productivity remains limited, exacerbating the challenges of land management for smallholder livelihoods. This complexity is compounded by the potential influence of carbon revenue, adding an additional layer of intricacy to the equation. This paper aimed to identify the key economic determinants of multistrata agroforestry in sub-Saharan Africa with and without potential carbon revenue. A quantitative survey of 135 farmers was performed regarding their multistrata agroforestry systems with contrasting histories in three regions of Ethiopia. The carbon sequestration rate and carbon stocks in agroforestry were assessed on one-fifth (27) of the farms. The relative importance of hypothetical determinants of agroforestry systems’ economic performance was modeled using descriptive statistics and generalized linear models. Farm size and fertilizer usage were the primary drivers of the farm economy, but farm net income was also highly influenced by the richness and diversity of the income sources. In addition, tree diversity had a positive impact on the net income, whereas the proportion of legume trees and trees with a large diameter correlated negatively with the income. Potential carbon revenue at prices of US$40 tCO2−1 and US$100 tCO2−1 increased income for multistrata agroforestry farms without significantly changing the magnitude of the identified key determinants. This suggests that the most economically viable agroforestry systems inherently possess a strong capacity for carbon sequestration, effectively serving as carbon sinks. Consequently, carbon revenue serves as a compelling financial incentive for the adoption of these agroforestry systems. Ultimately, this research underscores the pivotal role of biological and product diversity in shaping economic productivity within multistrata agroforestry systems. Moreover, it highlights the accessibility of diversity management for smallholder farmers, even under conditions of resource constraints.