Search Results (84)

This systematic review synthesizes a decade of peer-reviewed research (2015–2025) examining the interplay of filter bubbles, echo chambers, and algorithmic bias in shaping youth engagement within social media. A total of 30 studies were analyzed, using the PRISMA 2020 framework, encompassing computational audits, simulation modeling, surveys, ethnographic accounts, and mixed-methods designs across diverse platforms, including Facebook, YouTube, Twitter/X, Instagram, TikTok, and Weibo. Results reveal three consistent patterns: (i) algorithmic systems structurally amplify ideological homogeneity, reinforcing selective exposure and limiting viewpoint diversity; (ii) youth demonstrate partial awareness and adaptive strategies to navigate algorithmic feeds, though their agency is constrained by opaque recommender systems and uneven digital literacy; and (iii) echo chambers not only foster ideological polarization but also serve as spaces for identity reinforcement and cultural belonging. Despite these insights, the evidence base suffers from geographic bias toward Western contexts, limited longitudinal research, methodological fragmentation, and conceptual ambiguity in key definitions. This review highlights the need for integrative, cross-cultural, and youth-centered approaches that bridge empirical evidence with lived experiences. Full article

This study investigates the viability of a native Scenedesmus sp. strain for use in a 50 L bubble column photobioreactor designed to reduce greenhouse gas emissions under simulated spring, extreme summer, and winter conditions. The experiments were conducted by placing the reactor in a controlled climatic chamber, which allowed us to regulate the temperature, light intensity, and day–night cycles throughout the entire experiment. The results showed that under simulated spring conditions (a maximum temperature of 22 °C), the algal culture grew continuously for 61 days. Under extreme summer conditions (a maximum temperature of 39 °C), an initial drop in cell density was followed by recovery and continued growth over 75 days, although biomass production was 35% lower. Under winter conditions (a maximum temperature of 10 °C), the culture failed, indicating the need to prevent temperatures below 10 °C. In terms of biomass production, the culture densities achieved were 1.04 g L⁻¹ and 0.68 g L⁻¹ in the spring and summer trials, respectively. The Scenedesmus sp. strain demonstrated high carbon capture efficiency, tolerance to extreme heat, and sustained growth without the need for fresh medium or pH adjustments for over 60 days during spring and extreme summer conditions, confirming its potential for outdoor applications. Full article

Mycogone perniciosa is the causative agent of wet bubble disease, which induces significant losses in the production of Agaricus bisporus, indicating the high importance of the development of novel inhibitory agents. The isolation, identification, and molecular characterization of five isolates of M. perniciosa from diseased fruit bodies of A. bisporus was done. Moreover, the study evaluated the in vitro and in situ potential of Origanum vulgare essential oil (EO) to limit M. perniciosa growth and provided chemical characterization of its volatile components. The obtained strains differed phenotypically and according to their molecular characteristics. O. vulgare EO has shown more promising antifungal activity than the commercial fungicide Prochloraz-Mn in the microatmospheric method. In the treatment of experimentally induced wet bubble disease on A. bisporus in the growing chambers with 2% of O. vulgare EO and simultaneous application of spore suspension of mycopathogen, O. vulgare EO totally inhibited the growth of M. perniciosa. Carvacrol, p-cymene, γ-terpinene, and thymol were dominant constituents of O. vulgare EO examined in this study. O. vulgare EO has shown promising potential to limit growth of M. perniciosa and should be further explored as a novel biofungicide. Full article

Splashed droplets in the vacuum chamber play an important role in decarburization and degassing in Ruhrstahl–Heraeus (RH), but the scholars do not pay attention to the behaviors of splashed droplets. Thus, it is necessary to propose a new method to investigate the splashed droplets. A Euler–Euler model and the inter-phase momentum transfer are applied to investigate the interaction between the molten steel and the bubbles, and the gas domain in the vacuum chamber is included in the computational domain in order to describe the movement of the splashed droplets. Numerical results show that the flow field predicted by Euler–Euler model agrees well with the experimental data. There is a higher gas volume fraction near the up-snorkel wall, the “fountain” formed by the upward flow from the up-snorkel exceeds 0.1 m above the free surface, and the center of the vortex between the upward stream and the downward stream is closer to the upward stream in the vacuum chamber. Full article

This paper critically examines the risks to democratic institutions and practices posed by disinformation, echo chambers, and filter bubbles within contemporary social media environments. Adopting a modern republican approach and its conception of liberty as nondomination, this paper analyzes the role of algorithms, which curate and shape user experiences, in facilitating these challenges. My argument is that the proliferation of disinformation, echo chambers, and filter bubbles constitutes forms of domination that manipulate vulnerable social media users and imperil democratic ideals and institutions. To counter these risks, I argue for a three-pronged response that cultivates robust institutional and individual forms of antipower by regulating platforms to help protect users from arbitrary interference and empower them to fight back against domination. Full article

Gas bubbles are one of the main disturbances encountered when dispensing drugs of microliter volumes using portable miniaturized systems based on piezoelectric diaphragm micropumps. The presence of a gas bubble in the pump chamber leads to the inaccurate administration of the required dose due to its impact on the flowrate. This is particularly important for highly concentrated drugs such as insulin. Different types of sensors are used to detect gas bubbles: inline on the fluidic channels or inside the pump chamber itself. These solutions increase the complexity, size, and cost of the microdosing system. To address these problems, a radically new approach is taken by utilizing the sensing capability of the piezoelectric diaphragm during micropump actuation. This work demonstrates the workflow to build a self-sensing micropump based on artificial intelligence methods on an embedded system. This is completed by the implementation of an electronic circuit that amplifies and samples the loading current of the piezoelectric ceramic with a microcontroller STM32G491RE. Training datasets of 11 micropumps are generated at an automated testbench for gas bubble injections. The training and hyper-parameter optimization of artificial intelligence algorithms from the TensorFlow and scikit-learn libraries are conducted using a grid search approach. The classification accuracy is determined by a cross-training routine, and model deployment on STM32G491RE is conducted utilizing the STM32Cube.AI framework. The finally deployed model on the embedded system has a memory footprint of 15.23 kB, a runtime of 182 µs, and detects gas bubbles with an accuracy of 99.41%. Full article

Variable stiffness actuators (VSAs) have attracted considerable attention in wearable robotics and soft exoskeletons due to their ability to adapt to various load conditions. This study presents a modular design for VSAs that incorporates a chain mail structure with various link topologies, allowing for a reconfiguration of stiffness. The proposed VSA consists of three main parts: the vacuum chamber, the VSA actuator, and the chain mail structure. The VSA fabrication process was carried out in five stages: (1) mold fabrication by 3D FDM printing, incorporating a film of oil to facilitate easy demolding; (2) mold preparation using silicone, with a precise ratio of 1:1 weight-based mixture to optimize material utilization; (3) silicone pouring into molds while applying vibration to eliminate air bubbles; (4) curing for four hours to achieve optimal mechanical properties; and (5) careful demolding to prevent damage. Experimental tests were conducted to characterize the stiffness of actuators with different chain mail fabric configurations, using an experimental setup designed to securely fix the actuator and accurately measure the pneumatic pressure and the angle of deformation after applying weights at its end. The European 6-in-1 and rounded square configurations were shown to be the most effective, increasing stiffness up to 382% compared to the chain mail-free configuration, highlighting the positive impact of these structural designs. Full article

Purpose: This study aimed to refine the criteria for EndoART implantation regarding posterior corneal irregularity; to improve the selection of candidates for this synthetic alternative to endothelial keratoplasty. Methods: This study analyzed the impact of posterior corneal surface elevation differences; anterior chamber depth (ACD); and preoperative corneal pachymetry on the success of EndoART implant adhesion. Patients undergoing EndoART implantation at the Medical University of Vienna were assessed using OCT to measure corneal irregularities. Postoperative outcomes, including re-bubbling rates; implant adhesion; and visual acuity changes, were monitored. Results: EndoART successfully adhered in eyes with moderate posterior irregularities (elevation differences up to 204 µm). Severe irregularities (elevation differences > 200 µm) resulted in implant detachment. No significant correlation was found between corneal pachymetry or ACD and adhesion failure. Glaucoma devices and prior penetrating keratoplasty did not significantly affect adhesion. Some cases required re-bubbling, and patients reported pain reduction and moderate improvements in visual acuity. Conclusions: This study found that EndoART implantation can be successful despite posterior corneal irregularity. EndoART represents a viable solution for patients with poor biological graft survival prognosis, including those with glaucoma or prior surgeries, expanding its potential use and addressing the global donor cornea shortage. Full article

In this study, through RH water model simulation experiments, the effects of precipitation bubbles on the two-phase flow pattern, liquid steel flow behavior, and flow characteristics in an RH reactor during the whole decarburization process were comparatively investigated and analyzed by using quasi-counts that reflected the similarity of the precipitation bubble phenomenon. The experimental results show that an increase in precipitation bubbles is positively related to an increase in circulating flow rate, a reduction in mixing time, and an increase in gas content and negatively related to the residence time of liquid steel in the vacuum chamber. The two-phase flow pattern of the rising tube under the influence of precipitation bubbles includes bubble flow, slug flow, mixing flow, and churn flow. Under the influence of precipitation bubbles, the liquid surface spattering inside the vacuum chamber is reduced, the fluctuation amplitude is reduced, the efficiency of liquid steel processing is improved, it is not easy for cold steel to form, and the fluctuation frequency is increased, which is conducive to increasing the surface area of the vacuum chamber; the bubbles’ rising, aggregating, and crushing behavior increases the stirring effect inside the vacuum chamber, which is conducive to improving the decarburization and mass transfer rate. Under the influence of the precipitated bubbles, the concentration gradient between the ladle and the vacuum chamber is increased, which accelerates the mixing speed of the liquid steel in the ladle, and the volume of the dead zone is reduced by 50%. The lifting gas flow rate can be appropriately reduced in the plant. Full article

Gas embolism is a rare but life-threatening process characterized by the presence of gas bubbles in the venous or arterial systems. These bubbles, if sufficiently large or numerous, can block the delivery of oxygen to critical organs, in particular the brain, and subsequently they can trigger a cascade of adverse biochemical reactions with severe medical outcomes. Despite its critical nature, gas embolism remains poorly understood, necessitating extensive investigation, particularly regarding its manifestations in the human body and its modulation by various biological conditions. However, given its elusive nature, as well as potential lethality, gas embolism is extremely difficult to study in vivo, and nearly impossible to be the subject of clinical trials. To this end, we developed a microfluidic device designed to study in vitro the impact of blood properties and vascular geometries on the formation and evolution of gas bubbles. The system features a biomimetic vascular channel surrounded by two pressure chambers, which induce the genesis of bubbles under varying circumstances. The bubble parameters were correlated with different input parameters, i.e., channel widths, wall thicknesses, viscosities of the artificial blood, and pressure levels. Smaller channel widths and higher equivalent hematocrit concentrations in synthetic blood solutions increased the nucleation density and bubble generation frequencies. Small channel widths were also more prone to bubble formation, with implications for the vulnerability of vascular walls, leading to increased risks of damage or compromise to the integrity of the blood vessels. Larger channel widths, along with higher equivalent hematocrit concentrations, translated into larger bubble volumes and decreased bubble velocities, leading to an increased risk of bubble immobilization within the blood vessels. This biomimetic approach provides insights into the impact of patient history and biological factors on the incidence and progression of gas embolism. Medical conditions, such as anemia, along with anatomical features related to age and sex—such as smaller blood vessels in women and children or larger vascular widths in adult men—affect the susceptibility to the initiation and progression of gas embolism, explored here in vitro through the development of a controlled, physiological-like environment. The analysis of the videos that recorded gas embolism events in vitro for systems where pressure is applied laterally on the microvasculature with thin walls, i.e., 50 μm or less, suggests that the mechanism of gas transfer for the pressure area to the blood is based on percolation, rather than diffusion. These findings highlight the importance of personalized approaches in the management and prevention of gas embolism. Full article

The topic concerns the so-far-unknown mechanism of the bubble effect (b.e.) in a large mass of moist cellulose heated with mineral oil. The well-known b.e. occurs in the Hot Spot area, i.e., in the place where the hot metal of the windings is in contact with the insulation paper. The authors first showed that cyclic heating of a windings model causes the drying of both the insulation paper and pressboard, but the paper dries faster. For this reason, the bubble effect inception temperature can be lower in the pressboard than in the paper. Next, the authors showed that the bubble effect in the pressboard is very intense and causes a sudden and very large increase in pressure in the tank. Moreover, if the tank seal is suddenly damaged because of this, the number and volume of bubbles will increase dramatically. Next, the influence of the mass of cellulose to the mass of oil ratio on the pressure increase dynamics was tested. This experiment showed that the greater the mass of cellulose to the mass of oil, the greater the increase in pressure in the test chamber. The authors also determined that the characteristics of the bubble effect initiation temperature in the pressboard samples, depending on their moisture content, ranged from 2.0 to 4.8%. The experiment showed that the b.e. in the pressboard proceeds in the same way as in paper insulation. The research results showed that, in addition to the well-known b.e. in the winding paper in the Hot Spot area, the b.e. can occur in a large mass of pressboard cellulose, which can be much more dangerous for the transformer. Full article

Background and Objectives: In coronary artery bypass grafting (CABG) on pump, achieving optimal visualization is critical for surgical precision and safety. The use of blowers to clear the CABG anastomosis poses risks, including the formation of micro-embolic gas bubbles, which can be insidious and increase the risk of cerebral or myocardial complications. This retrospective study compares the effectiveness of the use of irrigation mist and CO₂ versus a direct CO₂ blower without irrigation in terms of visualization, postoperative fibrillation, and micro-embolic gas activity. Materials and Methods: The study involved 40 patients who underwent on-pump CABG, with 20 patients assigned to the irrigation mist and CO₂ group (ClearView™) and 20 to the direct CO₂ blower group. Primary outcomes included the quality of intraoperative visualization, the incidence of fibrillation at aortic de-clamping, and the presence of micro-embolic gas activity detected via transesophageal echocardiography (TEE) in the cardiac chambers. Results: Patients in the irrigation mist and CO₂ group experienced superior visualization and reduced tissue desiccation. Fibrillation at the time of aortic de-clamping occurred in two patients (10%) using the irrigation mist and CO₂, compared to eight patients (40%) using the direct CO₂ blower. Additionally, TEE monitoring revealed lower levels of micro-embolic gas activity in the irrigation mist and CO₂ group, indicating a potential reduction in gas embolization risk. Conclusions: The irrigation mist and CO₂ system not only provides enhanced visualization during CABG but also significantly reduces the incidence of fibrillation during aortic de-clamping and micro-embolic gas activity. These findings suggest improved patient safety and outcomes, highlighting the irrigation mist and CO₂ system as a potentially safer alternative to direct CO₂ blowing in the context of myocardial revascularization. Full article

This paper presents the results of experiments conducted on the flotation separation of cyclone dust particles. The flotation process was conducted using a laboratory flotation apparatus comprising three chambers. Experimental tests supported theoretical results of the theoretical reasoning and justification for the choice of parameters that the flotation process should have in order to extract particles of such small sizes. Furthermore, this work elucidates the concept of “nanobubbles” and substantiates their viability for use in the flotation of nanoparticles, given that bubbles of such a magnitude are firmly affixed to the hydrophobic surface of particles. Bubbles of a larger size than nanoparticles will float both hydrophobic and hydrophilic particles. The effective flotation of cyclone dust from the gas cleaning of silicon and ferroalloy production provided two materials as a result. The experiments yielded insights into the rational technological parameters of the flotation mode for obtaining new products. These insights were gleaned from the preliminary conditioning (conditioning time from 0.5 to 1.5 h) of wet cyclone dust (dry dust weight of 4 kg) with liquid glass (1.4 g per 1 dm³ of pulp) in a cavitation unit at a pH value of 8.5. The flotation process was conducted in a three-chamber flotation apparatus with a volume of 0.02 m³ for a duration of 90 min, utilizing a pneumohydraulic aerator with air suction from the atmosphere. In this instance, the pulp was conveyed via a pump at a pressure of 0.4 MPa from the initial cleansing chamber into the aerator. During the flotation process, kerosene (1 mg per 1 dm³ of pulp) and pine oil (2 mg per 1 dm³ of pulp) were added as additives. The resulting products were silicon dioxide (95%) and carbon nanoparticles (94%). Full article

Aerated irrigation is an emerging and efficient irrigation technique, and the throttle-squeeze releaser (TS releaser) is a commonly used key component in aerated irrigation devices. However, it has issues such as large bubble size, uneven distribution, and low dissolved-oxygen content in the irrigation water. Given these problems, this study optimized the valve chamber and throat structure of the releaser based on the TS releaser, designing three different types of releasers with W-shaped valve chamber, arc-shaped valve chamber, and multi-throat W-shaped valve chamber. The simulation results, obtained using the Fluent module with grid division in ANSYS 2022, show that high-pressure regions are formed inside the releaser with V-shaped and arc-shaped valve chambers that are detrimental to the formation of microbubbles in high-pressure dissolved-air water, while the fluid pressure reduction and energy dissipation are more balanced inside the releasers with a W-shaped valve chamber. Compared to a single-throat design, the multi-throat design allows high-pressure fluid to enter the valve chamber more uniformly, which aids in maximizing the functionality and performance of the valve chamber. To determine the effects of throat size, outlet size, and valve chamber angle on the pressure field, turbulent flow field, velocity field, and air-phase distribution within the multi-throat W-shaped valve chamber releaser, simulation interaction experiments were conducted. The results showed that the optimized releaser performed best when the throat diameter was 1 mm, the outlet size was 2 mm, and the valve chamber angle was 80°. Finally, a comparative performance evaluation between the conventional TS diffuser and the optimized multi-throat W-valve chamber releaser reveals that the latter achieves a maximum dissolved-oxygen content of 6.36 mg/L in the treated irrigation water, representing an approximately 3.5% improvement over the 6.14 mg/L recorded by the traditional releaser. Furthermore, when considering the thresholds of irrigation flow rates above 950 L/h and dissolved-oxygen levels exceeding 5.9 mg/L, the multi-throat W-valve chamber diffuser exhibits a broader operational range characterized by high flow rates and dissolved-oxygen levels. Full article

In the modern aerospace industry, the importance of a lubrication system is self-evident for aero-engines, and the aero-engine bearing chamber return line is an even more challenging environment, as it involves a complex two-phase flow. The designer of the scavenge pipe needs to have an accurate understanding of the flow conditions in the scavenge pipe. This paper establishes a visual scavenge pipe test system. The flow direction was vertical flow, the test temperature was 370 k, and a high-speed camera was used to take high-definition flow photographs, which can observe the three main flow types: bubble flow, slug flow, and annular flow. Code program was created to analyze many pictures taken to obtain the apparent flow rate and perimeter of bubbles in the pipe under different flow conditions and to explore the gas–liquid two-phase flow in the scavenge pipe. A support vector machine (SVM) was used for data regression prediction, and the converted velocities of the gas–oil phases were inputted as eigenvalues to obtain the predicted values of bubble-flow velocity. The bubble-flow analysis prediction model established in this paper has a good prediction effect with root mean square error RMSE = 0.0172, which can more objectively and accurately describe the bubble-flow characteristics in the scavenge pipe. Full article