Search Results (3,778)

Lost circulation is one of the important problems that restricts the speed and efficiency of oil and gas drilling and production. In this study, a resin plugging system was successfully developed for lost circulation formation. The resin plugging system showed excellent performance under high temperature and pressure conditions. The experimental results showed that the compressive strength of the resin plugging material can reach 9.23 MPa after curing, which is significantly higher than that of the traditional polymer gel material. The resin material can achieve effective curing in the temperature range of 60 °C to 100 °C, and the curing time decreases with the increase of temperature and only needs 3.46 h at 140 °C. The microstructure results showed that the resin material can form a chain or three-dimensional network structure after curing, which can effectively increase the toughness and strength of the cured plugging layer. Infrared and thermogravimetric analysis further confirmed the thermal stability of the chemical bonds in the material, and the initial decomposition temperature was about 241 °C, indicating that it had good thermal stability at about 300 °C. In addition, the effects of curing temperature, salinity, and drilling fluid pollution on the properties of the resin plugging agent were also investigated. The results showed that curing agent dosage and curing temperature are the key factors affecting curing time, while salinity and drilling fluid pollution affect the curing strength and overall properties of the materials. After adding 20% KCl polysulfonate drilling fluid, the compressive strength of the consolidated body decreased to 4.55 MPa. This study can provide an efficient and reliable plugging solution for malignant loss formation. Full article

The rheological behavior of concrete pumping in the bend section is complex. The existing conversion calculation for pumping pressure loss based on the straight pipe section often fails to meet engineering precision requirements. This paper develops a pressure loss correction model for a concrete pumping bend section based on a new one-dimensional flow model for the straight pipe section simulation of particle flow; the study analyzes the impact of parameters such as elbow shape and pumping flow rate on pressure loss. An equivalent conversion relationship between the bend section and the straight section is established. The comparison with the measured pressure values from the project shows that the relative error between the pressure loss values calculated by the correction model and the actual measurements is 15.8%. Full article

Most retinal and optic nerve diseases pose significant threats to vision, primarily due to irreversible retinal neuronal cell death, a permanent change, which is a critical factor in their pathogenesis. Conditions such as glaucoma, retinitis pigmentosa, diabetic retinopathy, and age-related macular degeneration are the top four leading causes of blindness among the elderly in Japan. While standard treatments—including reduction in intraocular pressure, anti-vascular endothelial growth factor therapies, and retinal photocoagulation—can partially delay disease progression, their therapeutic effects remain limited. To address these shortcomings, a range of neuroprotective and regenerative therapies, aimed at preventing retinal neuronal cell loss, have been extensively studied and increasingly integrated into clinical practice over the last two decades. Several of these neuroprotective therapies have achieved on-label usage worldwide. This narrative review introduces several neuroprotective and regenerative therapies for retinal and optic nerve diseases that have been successfully translated into clinical practice, providing foundational knowledge and success stories that serve as valuable references for researchers in the field. Full article

Background: The global obesity issue is growing increasingly serious, impacting personal health, economic development, and the sustainability of medical systems. There is an urgent need for effective weight loss strategies that can be widely implemented. This study conducted a 90-day randomized controlled trial to assess the impact of meal replacement products on weight management and glycolipid metabolism in adults with obesity. Methods: Adults with obesity meeting the inclusion and exclusion criteria were divided into three groups: the meal replacement group (n = 19), the diet control group (n = 19), and the normal diet group (n = 22). The meal replacement group used specially formulated meal replacement products for dinner, and the diet control group reduced the intake of staple food at lunch, both controlling daily energy intake between 1200 kcal and 1300 kcal, while the normal diet group maintained their regular dietary habits. Relevant indicators were measured at baseline and after 45 and 90 days of intervention. Results: The results showed that both the meal replacement group and the diet control group experienced significant decreases in weight, BMI, and body fat percentage, with the meal replacement group showing a more pronounced weight loss effect. The weight loss of the meal replacement group at 45 and 90 days was 4.44 ± 1.84 kg and 7.38 ± 3.24 kg, the diet control group was 2.62 ± 2.28 kg and 4.08 ± 2.94 kg, and the normal diet group was 0.66 ± 1.73 kg and 0.97 ± 2.02 kg. The decrease in BMI at 45 and 90 days for the meal replacement group was 1.08 ± 0.78 kg/m² and 2.17 ± 1.57 kg/m², for the diet control group was 0.82 ± 0.80 kg/m² and 1.39 ± 1.16 kg/m², and for the normal diet group was 0.19 ± 0.71 kg/m² and 0.21 ± 0.96 kg/m². The decrease in body fat percentage at 45 and 90 days for the meal replacement group was 1.76 ± 0.68% and 3.67 ± 2.62%, for the diet control group was 1.02 ± 1.11% and 1.52 ± 1.79%, and for the normal diet group was 0.81 ± 1.09% and 0.53 ± 0.93%. In addition, the decrease in BMI and body fat percentage in the meal replacement group was also significantly higher than in the other two groups. In terms of metabolic indicators, there were no significant differences in the changes of blood pressure, blood lipids, blood sugar, and ALT levels among the three groups during the intervention period. Conclusions: In summary, the results indicate that meal replacement products can significantly reduce weight and body fat percentage without affecting metabolic health. Full article

Background/Objectives: Juvenile Open Angle Glaucoma (JOAG) is a condition that presents peculiar issues because it starts at a very early age and, in the end, causes substantial vision loss. This study aimed to analyze the age and gender distribution and treatment outcomes in JOAG patients. Methods: We carried out a retrospective study at King Abdul Aziz University Hospital, Riyadh, Saudi Arabia, from 2015 to 2022. We extracted data from the medical records. Visual acuity data were converted to the logarithm of the minimum angle resolution (LogMAR) for standardized analysis. The CARL ZEISS Humphrey 745i Field Analyzer/HFA II-i Visual Field Analyzer was used to perform visual field examinations under the 24-2 program SITA standard. Results: The study involved 45 JOAG patients (87 affected eyes) with a mean age of 26.91 years. Myopia was the prevailing trait (93%), and a family history of glaucoma was found in 51.1% of cases. Most of the patients presented with severe visual field defects in both eyes (right—57.1%, left—44.4%). Regarding visual acuity, we found that the majority of affected categories belonged to either mild or moderate in both eyes. Initial and final Intraocular pressure (IOP) measurements together showed a significant reduction (p < 0.001) and clearly demonstrated the need for IOP control. Surgical and non-surgical treatments significantly reduced IOP, with no gender or eye differences Conclusions: This research offers important data concerning JOAG demographics (age and gender), clinical picture, and treatment results. Though early-onset presents challenges, multidimensional therapeutic methods have great potential to get JOAG under control and maintain visual function. Additional research is needed to study the genetic causes of JOAG and assess the long-term treatment outcomes. Full article

This study focuses on the great challenges for combined cooling and power supply on hypersonic aircrafts. To address the issues of low thermal efficiency and high fuel consumption of heat sink by the existing CO₂ supercritical Brayton cycle, a novel fuel-based CO₂ transcritical cooling and power (FCTCP) system is constructed. A steady-state simulation model is built to investigate the impacts of combustion chamber wall temperatures and fuel mass flow rates on the FCTCP system. Thermal efficiency of the CO₂ transcritical cycle reaches 25.2~32.8% under various combustion chamber wall outlet temperatures and endothermic pressures. Compared with the supercritical Brayton cycle, the thermal efficiency of novel system increases by 54.5~80.9%. It is found from deep insights into the thermodynamic results that the average heat transfer temperature difference between CO₂ and fuel is effectively reduced from 153.4 K to 16 K by split cooling of the fuel in the FCTCP system, which greatly enhances the matching of CO₂–fuel heat exchange temperatures and reduces the heat exchange loss of the system. Thermodynamic results also show that, in comparison to the supercritical Brayton cycle, the cooling capacity and power generation per unit mass flow rate of working fluid in the FCTCP system increased by 75.4~80.8% and 12.9~51.6%, respectively. The FCTCP system exhibits a substantial performance improvement, significantly enhancing the key characteristic index of the combined cooling and power supply system. This study presents a novel approach to solving the challenges of cooling and power supply in hypersonic aircrafts under limited fuel heat sink conditions, laying the groundwork for further exploration of thermal management technologies of hypersonic aircrafts. Full article

To address the escalating demand for power grid load regulation, pumped storage power stations must frequently switch between operational modes. As a key component of such stations, the pump turbine has seen extensive research on its steady-state flow behavior. However, the intricate dynamics of its transient flow have not yet been thoroughly examined. Notably, the no-load condition represents a quintessential transient state, the instability of which poses challenges for grid integration. Under certain extreme conditions, this could result in the impairment of the unit’s elements, interruption of its functioning, and endangerment of the security of the power station’s output as well as the stability of the power network’s operations. Thus, investigating the flow characteristics of pump turbines under no-load conditions is of significant practical importance. This paper focuses on the transient flow characteristics of a Weifang hydro-generator unit under no-load conditions, exploring the internal unsteady flow features and their underlying mechanisms. The study reveals that under no-load conditions, the runner channel is obstructed by a multitude of vortices, disrupting the normal pressure gradient within the runner and resulting in substantial hydraulic losses. Within the draft tube, a substantial reverse flow zone is present, predominantly along the walls. This irregular flow pattern within the tube generates a potent, stochastic pressure fluctuation. In addition to the interference frequencies of dynamic and static origins, the pressure pulsation frequency at each measurement point also encompasses a substantial portion of low-frequency, high-amplitude components. Full article

In this study, a closed multi-channel air-blowing plug seedling pick-up device and a combined plug tray were designed to address the issues of complex structure, high seedling damage rates and low pick-up efficiency in fully automated vegetable transplanter systems. The device operates by sealing the plug seedlings in a seedling cup, where compressed air is channeled into the sealed cavity through multiple passages during the seedling pick-up process. The upper surface of the seedling plug is subjected to uniform force, overcoming the friction and adhesion between the plug seedlings and the tray. This process presses the seedlings into the guide tube, completing the pick-up operation. A mechanical model for the plug seedlings was developed, and the kinetics of the pick-up process were analyzed. The multi-channel high-pressure airflow was simulated and evaluated, identifying three key parameters affecting seedling pick-up performance: water content of the seedling plug, air pressure during pick-up, and air-blowing duration. Using these factors as variables, and with seedling pick-up rate and substrate loss rate as evaluation indicators, single-factor experiments and a three-factor, three-level orthogonal experiment were conducted. The experiments’ results showed that the best seedling pick-up performance was achieved when the water content of the plug was 20%, the air pressure was 0.3 MPa, and the air-blowing time was 30 ms. Under these conditions, the seedling pick-up success rate was 97.22%, and the substrate loss rate was 10.46%. Full article

Biodiversity loss has accelerated over decades and probably exerted adverse impacts on ecosystems. As a key forest ecosystem function, tree productivity and its relationship with the change in species diversity are a hotspot in ecology research. However, the changing patterns of the relationships between these two variables across ecosystems with different environmental conditions and the underlying mechanisms are not well understood but key to make environmental context-specific strategies for forest ecosystem conservation and management. Here, we examined changes in relationship (R_DI-AGB) between the tree species diversity index (DI) and aboveground biomass (AGB) across temperate forest ecosystems with different environmental contexts on a small spatial (plot) scale as well as clarified the driving mechanisms using ground-based data from 3 natural reserves in northeastern China, surveying 22,139 trees across 77 species and 185 plots. We found substantial changes in R_DI-AGB across natural reserves with different environmental conditions on a small spatial scale. These changes were probably modulated by site-specific factors. A positive R_DI-AGB was attributed to positive impacts of local climate conditions (i.e., mean annual temperature and potential evapotranspiration) and stand age on both DI and AGB, which was observed in the Changbai Mountains Natural Reserve. In contrast, a negative R_DI-AGB was likely due to opposite directions in the effects of the site-dependent factors (elevation, mean annual precipitation, vapor pressure deficit, and seasonality of temperature) on DI and AGB, appearing in the Honghuaerji Natural Reserve. In addition, complex impacts of site factors on DI and AGB leading to no obvious R_DI-AGB was observed in the Shengshan Natural Reserve. Our results highlight the importance of site-dependent factors in modulating species diversity–productivity relationships and the need to use site-specific strategies in management and conservation for forest-dominated natural reserves and other forest ecosystems with heterogeneous environmental conditions. Full article

This paper proposes a high-precision interventional pressure measurement catheter with a compact structure for in vivo pressure monitoring. This catheter uses a minimally invasive testing method, and the proposed compact structure reduces pressure loss caused by fluid movement inside the catheter, ensuring accuracy in dynamically varying pressure measurements. The paper conducts a theoretical analysis of the pressure transmission process inside the catheter, fabricates a prototype, and establishes both dynamic and static pressure testing systems. Through experimental research on the effects of the catheter’s dimensions on the accuracy of dynamically varying pressure measurements, it demonstrates that the compact pressure measurement catheter can effectively enhance the precision of dynamically varying pressure measurements. The catheter offers high precision, small size, and simple manufacturing processes. It holds promising applications in fields such as in-body pressure measurement and microfluidic system monitoring. Full article

In view of the necessity of measuring the air content in oil in two-phase flows in the context of general industry, a review of the most popular methods of measuring the air content in oil was carried out. This review includes an assessment of their advantages and disadvantages and of whether they meet criteria such as the degree of filling, the size and number of bubbles, verification, the absence of additional pressure drops, simplicity, and repeatability. In the review, the following methods were examined: the classic trapping method, a modified trapping method, a trapping method using hydrostatic pressure loss, the pressure loss due to frictional flow resistance, the pressure loss with a rapid increase in diameter, the pressure drop in a Venturi tube, the pressure drop in an orifice, a method using the Coriolis effect, the electrical resistance method, the electrical conductivity method, the electromagnetic method, the electrical capacitance method, the thermal anemometry method, the liquid–solid contact electrification method, the photographic method, holography, light scattering, sound dispersion, the ultrasonic transit-time method, X-ray radiation, gamma radiation, neutron radiation, and fiber-optic methods. Full article

Due to its inherent advantages, shield tunnelling has become the primary construction method for urban tunnels, such as high-speed railway and metro tunnels. However, there are numerous technical challenges to shield tunnelling in complex geological conditions. Under the disturbance induced by shield tunnelling, sandy pebble soil is highly susceptible to ground loss and disturbance, which may subsequently lead to the risk of surface collapse. In this paper, large-diameter slurry shield tunnelling in sandy pebble soil is the engineering background. A combination of field monitoring and numerical simulation is employed to analyze tunnelling parameters, surface settlement, and deep soil horizontal displacement. The patterns of ground disturbance induced by shield tunnelling in sandy pebble soil are explored. The findings reveal that slurry pressure, shield thrust, and cutterhead torque exhibit a strong correlation during shield tunnelling. In silty clay sections, surface settlement values fluctuate significantly, while in sandy pebble soil, the settlement remains relatively stable. The longitudinal horizontal displacement of deep soil is significantly greater than the transverse horizontal displacement. In order to improve the surface settlement troughs obtained by numerical simulation, a cross-anisotropic constitutive model is used to account for the anisotropy of the soil. A sensitivity analysis of the cross-anisotropy parameter α was performed, revealing that as α increases, the maximum vertical displacement of the ground surface gradually decreases, but the rate of decrease slows down and tends to level off. Conversely, as the cross-anisotropy parameter α decreases, the width of the settlement trough narrows, improving the settlement trough profile. Full article

One of the main problems of water distribution systems is the management and the evaluation of water losses. At the Laboratory of Hydraulics and Maritime Constructions at the Università Politecnica delle Marche, experimental research on this topic was conducted to measure the water volume exiting from a known shape and size hole at fixed hydraulic conditions. The obtained results were also used as input data for the Evolutionary Polynomial Regression (EPR) analysis for the construction of prediction models that could be employed for the management of water leakages in pressurized networks. Full article

Background: Obstructive Sleep Apnea (OSA) is a prevalent disorder characterized by repetitive upper airway obstructions during sleep, leading to intermittent hypoxia and sleep fragmentation. Current treatments, particularly Continuous Positive Airway Pressure (CPAP), face adherence challenges, necessitating novel therapeutic approaches. Methods: This review explores the potential of Glucagon-like Peptide-1 receptor agonists (GLP-1RA), commonly used for type 2 diabetes and obesity, in managing OSA. GLP-1RA promotes weight loss, enhances insulin sensitivity, and exhibits anti-inflammatory and neuroprotective properties, potentially addressing key pathophysiological aspects of OSA. Results: Emerging evidence suggests that these agents may reduce OSA severity by decreasing upper airway fat deposition and improving respiratory control. Clinical trials have demonstrated significant reductions in the Apnea-Hypopnea Index (AHI) and improvements in sleep quality with GLP-1 therapy. Conclusions: Future research should focus on elucidating the mechanisms underlying GLP-1 effects on OSAS, optimizing combination therapies, and identifying patient subgroups that may benefit the most. Integrating GLP-1RA into OSAS management could revolutionize treatment by addressing both the metabolic and respiratory components of the disorder, ultimately enhancing patient outcomes. Full article

Obesity is a multifactorial disease that is difficult to control worldwide. Although nuts are recognized health foods, the application of food in obesity management is unclear. We systematically reviewed the literature and performed a meta-analysis to evaluate if nut consumption favors people on energy restriction (ER) dietary interventions. Four databases were used to search for eligible articles in May 2024. This review was conducted according to the PRISMA guide, and the bias risk of papers was evaluated. For the meta-analysis, we extracted the endpoint values of the group’s variables and estimated the effect sizes by the random-effects model. Sixteen and ten articles were included in the systematic review and meta-analysis, respectively. Almonds were evaluated in the majority of studies (n = 6). The consumption of nuts (28 to 84 g/d, 4 to 72 months) included in ER (–250 to 1000 kcal/d) did not differently affect anthropometry (weight loss, BMI, waist and hip circumferences), body composition (fat mass, fat-free mass, or lean mass), markers of glucose (glycemia and insulinemia), lipid metabolism (total cholesterol, HDL-c, LDL-c, LDL-c/HDL-c, or triglycerides), and systolic and diastolic blood pressure. In most analyses, stratifying studies by type of nut or intervention time did not present different results in the meta-analysis. As there are few studies, in addition to great methodological variability, more high-quality trials are needed to confirm these results. The PROSPERO registration number is CRD42023444878. Full article