Wetting of soap bubbles on topographic surfaces.

HYPOTHESIS: There is a relationship between the static contact angle of droplets and soap bubbles on flat homogeneous surfaces, therefore, it should be possible to derive a relationship between the static contact angle of a soap bubble on a periodic topographic surface and a droplet on a flat homogeneous surface. EXPERIMENTS: A free energy model of the static contact angle of soap bubbles on a topographic surface in the Cassie-Baxter state was derived. Polydimethylsiloxane surfaces of varying area fraction (0.125, 0.250, 0.500, 0.750, and 1.00) and periodic topographies (lined and pillared) were fabricated using 3D printed moulds for pattern transfer. A bubble goniometer was developed to accommodate bubbles of 40,000 ± 5,000 mm3 and 50,000 ± 5,000 mm3 volumes. Then, the static contact angle of bubbles of both volumes were measured on the varying topographic surfaces. FINDINGS: The derived predictions imply that the relationship between the static contact angle for bubbles on a flat homogeneous surface and on a composite surface, has the same form as the Cassie-Baxter equation for a droplet. The experimental results for the measured static contact angle for both bubble volumes on the varying surfaces had good agreement with the predicted trends.

Wimpled thin films via multiple motions of a bubble decorated with surface-active molecules.

HYPOTHESIS: Thin liquid films play a crucial role in various systems and applications. Understanding the mechanisms that regulate their morphology is a scientific challenge with obvious implications for application optimization. Thin liquid films trapped between bubbles and air-liquid interface can show various configurations influenced by their deformation history and system characteristics. EXPERIMENTS: The morphology of thin liquid films formed in the presence of surface-active molecules is here studied with interferometric techniques. Three different systems with varying interfacial properties are investigated to understand their influence on film morphology. Specific deformation histories are applied to the films to generate complex film structures. FINDINGS: We achieve the creation of a rather stable wimple by implementing controlled bubble motions against the air-liquid interface. We provide a criterion for wimple formation based on lubrication theory. The long-term stability of the wimple is also investigated, and more complex multi-wimple structures are experimentally produced building upon the achieved wimple stability.

Engineering Hyperechogenic Colloids with Clot-Targeting Capabilities from Platelet-Derived Membranes.

Thrombosis-related cardiovascular diseases remain the leading global cause of mortality and morbidity. In this study, we present a pioneering approach in the field of nanobiotechnology, with a focus on clinical translation, aimed at advancing early diagnosis and enhancing treatment options for thrombotic disorders. We introduce the fabrication of Platelet Membrane-Derived Bubbles (PMBs), which exhibit distinctive characteristics compared to conventional nanoparticles. These PMBs possess an average diameter of 700 nm and a negative ζ-potential, mirroring the attributes of parent platelet membranes. Utilizing diagnostic ultrasound imaging, we demonstrated the ability to visualize PMBs as hyperechogenic entities in agarose phantoms in vitro and in live mice in vivo. Furthermore, through confocal laser microscopy, we verified the retention of crucial transmembrane proteins, such as CD41 (GPIIb) and CD42 (GPIb), pivotal in conferring platelet-specific targeting functions. Importantly, our platelet aggregation studies confirmed that PMBs do not induce platelet aggregation but instead adhere to preformed platelet-rich in vitro thrombi. Overall, our work showcases the safe and precise utilization of PMBs to directly target acute thrombosis induced by laser injury in murine mesenteric veins in vivo, as visualized through intravital microscopy. In conclusion, we have successfully developed a rapid method for generating PMBs with unique ultrasound-directed and thrombus-targeting properties. These exceptional attributes of PMBs hold significant promise for advancing the field of ultrasound diagnostic thrombus imaging and clot-targeted therapy in the clinical context.

Catalyst-free regeneration of plasma-activated water via ultrasonic cavitation: Removing aggregation concealment of antibiotic-resistant bacteria with enhanced wastewater sustainability.

Aggregation is a crucial factor in bacterial biofilm formation, and comprehending its properties is vital for managing waterborne antibiotic-resistant bacteria. In this study, we examined Methicillin-resistant Staphylococcus aureus (MRSA) cell aggregation under varying conditions and assessed the inactivation efficiency of a novel disinfection method, micro-nano bubbles plasma-activated water via ultrasonic stirring cavitation (MPAW-US), on aggregated MRSA cells. Aggregation efficiency increased over time and at low salt concentrations but diminished at higher concentrations. Elevated MRSA cell aggregation in actual water samples represented significant real-life biohazard risks. Unlike conventional disinfection, MPAW-US treatment exhibited minimal change in the inactivation rate constant despite protective outer layers. Enhanced inactivation efficiency results from the synergistic effects of increased intracellular oxidative stress damage and extracellular substance disruption, triggered by ultrasound-activated micro-nano bubbles that improve PAW reactivity and applicability. This approach neither induced MRSA cross-resistance to unfavorable conditions nor increased toxicity or regrowth potential of aggregative MRSA, utilizing ATP levels as potential regrowth capability indicators. Ultimately, this energy-efficient disinfection technology functions effectively across diverse temperature ranges, showcasing exceptional sterilization and nutritional bean sprout production after cyclic filtering, thereby promoting wastewater sustainability amidst carbon emission concerns.

Reconsidering freeze-induced protein aggregation: Air bubbles as the root cause of ice-water interface stress.

Freeze-induced stress causing aggregation of proteins has typically been primarily attributed to the ice-water interface. However, we hypothesize that the underlying observed and perceived detrimental effect of ice is, to some extent, attributed to air bubbles expelled from ice crystal lattices or to nanobubbles existing prior to freezing. The reduction of dissolved air was achieved via a deaeration process by placing samples in a reduced pressure chamber, while the reduction of nanobubbles was achieved by filtering samples via a syringe filter. The results showed that the reduction of both dissolved air molecules and stable colloidal nanobubbles in a bovine IgG solution prior to freezing led to a significant decrease in aggregation after thawing compared to untreated samples (∼6,000 vs. âˆ¼ 40,000 particles/mL at a freezing rate of 100 K/s, respectively). The deaeration-filtration treatment works additively with cryoprotectants such as trehalose, further reducing the freeze-induced aggregation of IgG. The results also demonstrated that air-water interfacial aggregation of IgG in bulk liquid samples is a time-dependent process. The number of IgG subvisible particles increased with time and temperature, suggesting that random collisions of denatured molecules promoted the formation of aggregates with spherical morphology. In contrast, the IgG subvisible count after freeze-thawing had already reached its nominal value, suggesting a time-independent process where denatured protein molecules were compressed between ice crystals into filament-like aggregates. In summary, the findings shift the current paradigm from ice crystals being the main destabilizing factor during freezing to air bubbles, although the two are intertwined. From a translational aspect, this study underscores the value of deaeration-filtration as an essential supplemental process that can be applied in addition to formulation approaches such as the use of cryoprotectants to further reduce freezing stress on proteins and increase their stability.

Enhancing sludge thickening in continuous treatment using polymeric bubbles with cationic polymer P2900 and cocamidopropyl betaine.

Sludge thickening is a fundamental stage of treatment. This study investigated the application, in continuous treatment, of polymeric bubbles produced with cationic polymer P2900 and cocamidopropyl betaine (CAPB), a zwitterionic surfactant. The proposed reagent combination aims to form aerated flakes, solid waste structures, and rapidly rising air bubbles, ideal for treatments in compact units. Using this combination, it was possible to achieve a total solids concentration of 45% with the modified bubbles and 25% with the conventional water treatment. This level of thickening occurred under the following operating conditions: initial total solids (TS) concentration of 10 g L-1, a flow rate of 5 L min-1, saturation pressure (psat) of 3 atm, and polymer dosage of 10 mg (gTS)-1. The suggested mechanism of action involves the adhesion of P2900 molecules to CAPB at the air/water interface, forming a lining on the bubble surface. Additionally, polymerized species form due to the residual aluminum (Al) in the sludge, which would occur during flocculation in the helical tubular flocculator (HTF), adsorbing the micelles and bubbles of CAPB. The critical micellar concentration (CMC) of CAPB was 0.26 mmol L-1. Polymeric bubble technology can provide an efficient and cost-effective approach to sludge thickening in continuous treatment.

Promoting strategies for biological stability in drinking water distribution system from the perspective of micro-nano bubbles.

Microorganisms thriving in drinking water distribution system (DWDS) reduces biological stability of water, causing numerous threats to residents' drinking water safety. Traditional disinfection methods have intrinsic drawbacks, including microbial reactivation and byproduct formation, leading to waterborne diseases. Thus, effective disinfection techniques are required to ensure the microorganism's inactivation and enhance biological stability. Micro-nano bubbles (MNB) provide a promising result to these issues. This study simulates the hydraulic conditions of the tank of DWDS to investigate the enhancement of biological stability in the tank using MNBs with distinct gas sources. The analysis focused on water quality characteristics, biological stability indicators, and microbial community composition. The results showed that the dissolved gas method could generate abundant bubbles with a particle size below 1000 nm, with a concentration exceeding 106/mL in water. The particle size and Zeta potential of bubbles were crucial factors influencing in situ the ·OH generation; hence, the ·OH concentration was highly sensitive to changes in bubble size. In addition, MNBs inhibited the growth of target bacteria in water, degraded organic matter, and improved the biological stability of drinking water, reaching significant degradation rates for biodegradable dissolved organic carbon (42.74 %), assimilable organic carbon (49.49 %), and total bacteria (51.32 %). MNBs directly degraded organic matter in water by ·OH generation in situ, reducing the microbial nutrient source, thereby inhibiting microbial metabolism and activity, which induced optimum disinfection effects on Proteobacteria, Cyanobacteria, and Planctomycetota in water. In particular, the proposed experiment achieved a 100 % disinfection rate for Acinetobacter in Proteobacteria, disrupting metabolic intermediate functions with the microbial community after MNB treatment. Therefore, this study has demonstrated the potential of MNBs to enhance the biological stability of drinking water, improve water quality, and ensure residents' water health, providing valuable technical support for drinking water safety.

The Influence of Grain Size on Microstructure Evolution in CeO2 under Xenon Ion Irradiation.

Large-grained UO2 is considered a potential accident-tolerant fuel (ATF) due to its superior fission gas retention capabilities. Irradiation experiments for cerium dioxide (CeO2), used as a surrogate fuel, is a common approach for evaluating the performance of UO2. In this work, spark plasma sintered CeO2 pellets with varying grain sizes (145 nm, 353 nm, and 101 µm) and a relative density greater than 93.83% were irradiated with 4 MeV Xe ions at a fluence of 2 × 1015 ions/cm2 at room temperature, followed by annealing at 600 °C for 3 h. Microstructure, including dislocation loops and bubble morphology of the irradiated samples, has been characterized. The average size of dislocation loops increases with increasing grain size. Large-sized dislocation loops are absent near the grain boundary because the boundary absorbs surrounding defects and prevents the dislocation loops from coalescing and expanding. The distribution of bubbles within the grain is uniform, whereas the large-sized and irregularly shaped xenon bubbles observed in the small grain exhibit pipe diffusion along the grain boundaries. The bubble diameter in the large-grained pellet is the smallest. As the grain size increases, the volumetric swelling of the irradiated pellets decreases while the areal density of Xe bubbles increases. Elemental segregation, which tends to occur at dislocation loops and grain boundaries, has been analyzed. Large-grained CeO2 pellet with lower-density grain boundaries exhibits better resistance to volumetric swelling and elemental segregation, suggesting that large-grained UO2 pellets could serve as a potential ATF.

Price bubbles and Co-bubbles in the green economy market.

In light of growing concerns about climate change and environmental issues, investor interest has surged in the new green economy market. However, the existing literature is limited regarding potential price bubbles and co-bubbles within this new domain. This study examines price bubbles and co-bubbles in the new green economy market, covering 31 indexes classified into three groups: the green economy market and its components, geographical regions, and sectors. Using daily data from August 31, 2005, to May 31, 2024, a test procedure is first applied to detect periods of price bubble in the various indexes, then logistic regressions are employed to examine price co-bubble behaviours. The results show evidence of price bubbles in the green economy market, particularly in solar and wind indexes, with peaks during the COVID-19 pandemic and Russia-Ukraine conflict, whereas the water index is the least prone to price bubbles. Regarding geographical region, the USA market exhibits a higher tendency for price bubbles than the Asian or European markets. Several sectors are resistant to price bubbles. The co-bubble analysis reveals a strong reliance of wind index on price bubbles in the solar and water indexes. Price bubbles in Asia significantly influence price bubbles in Europe and the USA. These findings have implications for investment portfolio management and risk management strategies in the new green economy market.

Experimental study on attenuation effect of liquid viscosity on shockwaves of cavitation bubbles collapse.

How to precisely control and efficiently utilize the physical processes such as high temperature, high pressure, and shockwaves during the collapse of cavitation bubbles is a focal concern in the field of cavitation applications. The viscosity change of the liquid will affect the bubble dynamics in turn, and further affect the precise control of intensity of cavitation field. This study used high-speed photography technology and schlieren optical path system to observe the spatiotemporal evolution of shockwaves in liquid with different viscosities. It was found that as the viscosity of the liquid increased, the wave front of the collapse shockwave of the cavitation bubble gradually thickened. Furthermore, a high-frequency pressure testing system was used to quantitatively analyze the influence of viscosity on the intensity of the shockwave. It was found that the pressure peak of the shockwave in different viscous liquid was proportional to Lb (L represented the distance between the center of bubble and the sensor measuring point), and the larger the viscosity was, the smaller the value of b was. Through in-depth analysis, it was found that as the viscosity of the liquid increased, the proportion of the shockwave energy of first bubble collapse to the maximal mechanical energy of bubble gradually decreased. The proportion of the mechanical energy of rebounding bubble to the maximal mechanical energy of bubble gradually increased. These new findings have an important theoretical significance for the efficient utilization of ultrasonic cavitation.

Biomimetic Transparent Slippery Surface for the Locomotion of Photocontrol Droplets and Bubbles.

Directed transportation and collection of liquids and bubbles play a vital role in the survival of ecosystems. Among them, the optical response control is widely used in the fields of microfluidic chips and chemical synthesis because of its high remote operation and fast response speed. However, due to poor light transmission, the development direction of traditional near-infrared (NIR) absorbing materials in the field of visualization is limited, and there are few reports of manufacturing an operating platform that can realize the directional movement of droplets/bubbles on a single platform. Here, a transparent photo-responsive PBFS platform is prepared for droplet and bubble manipulation by coating the etched glass substrate with Prussian blue (PB) nanocubes. When near-infrared (NIR) irradiation on the PBFS platform, PB nanocubes trigger heat production by photothermal means, due to the action of Marangoni force, the surface tension on the left and right sides of the droplets and bubbles is not uniform, forming a surface tension gradient, thereby driving the movement of the droplets and bubbles. The control platform has good application potential in the field of microchemical reaction and biomedical engineering and brings new solutions to the field of transparent photothermal materials.

Locomotion behavior of air bubbles on solid surfaces.

Air bubbles are a common occurrence in both natural and industrial settings and are a significant topic in the fields of physics, chemistry, engineering, and medicine. The physical phenomena of the contact between bubbles and submerged solid surfaces, as well as the locomotion behavior of bubbles, are worth exploring. Bubbles are generated in an unbounded liquid environment and rise due to unbalanced external forces. Bubbles of different diameters follow different ascending paths, after which they approach, touch, collide, bounce, and finally adsorb to the solid surface, forming a stable three-phase contact line (TPCL). The bubbles are in an unstable state due to the unbalanced external forces on the solid surface and the effects generated by the two-phase contact surface, resulting in different locomotion behaviors on the solid surface. Studying the formation, transport, aggregation, and rupture behaviors of bubbles on solid surfaces can enable the controllable operation of bubbles. This, in turn, can effectively reduce the loss of mechanical apparatus in agro-industrial production activities and improve corresponding production efficiency. Recent research has shown that the degree of bubble wetting on a solid surface is a crucial factor in the locomotion behavior of bubbles on that surface. This has led to significant progress in the study of bubble wetting, which has in turn greatly advanced our understanding of bubble behavior. Based on this, exploring the manipulation process of the directional motion of bubbles is a promising research direction. The locomotion behavior of bubbles on solid surfaces can be controlled by changing external conditions, leading to the integration of bubble behavior in various scientific and technological fields. Studying the dynamics of bubbles in liquids with infinite boundaries is worthwhile. Additionally, the manipulation process and mode of these bubbles is a popular research direction.

Emission Characteristics of Aerosols Generated during the Micro-Nano Bubble Aeration Process in Wastewater.

Micro-nano bubble (MNB) aeration is an emerging technology that considerably enhances the aeration efficiency of wastewater. This study evaluates, for the first time, aerosolization at the water-air interface during MNB aeration. Our results show that the concentration of culturable mixed microorganisms (i.e., bacteria, fungi, and intestinal bacteria) in the in situ MNB generation (MNBs-G) phase is 2170 CFU/m3, 1.38 and 1.58-fold higher than those in medium-bubble aeration (MBA; 1568 CFU/m3) and small-bubble aeration (SBA; 1376 CFU/m3) aerosols, respectively. Conversely, the concentration of culturable mixed microorganisms in the MNB persistent dissolved oxygen (MNBs-O) phase is only 914 CFU/m3. Microbiological analysis shows a lower abundance of bacterial pathogens in MNBs-G (34.12%) and MNBs-O (34.02%) phases than in MBA (39.63%) and SBA (38.87%) aerosols. Acinetobacter is prevalent in MNBs-G (14.76%) and MNBs-O (8.22%) aerosols, whereas Bacillus and Arcobacter are prevalent in MBA (23.96%) and SBA (6.92%) aerosols, respectively. The total concentrations of chemicals [i.e., total organic carbon, water-soluble ions, and metal(loid)s] in aerosols formed via MNB aeration (205.98-373.74 µg/m3) are lower than those in MBA and SBA (398.69-594.92 µg/m3). Compared to MBA and SBA, the MNBs-G phase exhibits higher emissions of 12 elements in aerosols (i.e., NO3-, NO2-, Ca2+, Na+, K+, Mg2+, Zn, Cd, Fe, Mn, As, and Cr), whereas the MNBs-O phase generally shows lower emissions. These findings highlight the potential of optimized MNB aeration technology in considerably mitigating aerosol emissions and thereby advancing environmental sustainability in wastewater treatment.

Tribological Research of Resin Composites with the Fillers of Glass Powder and Micro-Bubbles.

This study investigates the tribological properties of resin composites reinforced with the fillers of glass powder and micro-bubbles. Resin composites were prepared with varying concentrations from 1% to 5% wt of fillers. Tribological tests were conducted using a block-on-ring scheme under dry friction conditions. The measurements of friction coefficient and wear values were performed under variable rotation speeds and loading conditions. The study showed that resin composites with 2-3% glass powder fillers and resin composites with 3-4% micro-bubbles exhibited optimal tribological properties. The resin glass powder modifications reduce the wear by 63% and resin micro-bubbles reduce wear by 32%. SEM analysis of the surfaces revealed surface imperfections and structural damage mechanisms, including abrasive and fatigue wear. The study concludes that specific filler concentrations improve the friction and wear resistance of resin composites, highlighting the importance of material preparation and surface quality in tribological performance. The increased wear resistance on both composites would hopefully expand the usage of additive manufactured composite, namely industrial moving components such as polymer gear, wheel, pulley, etc.

Soothing venipuncture: Bubble blowing and ball squeezing in reducing anxiety, fear, and pain in children.

PROBLEM: The objective of this study was to investigate the impact of bubble-blowing and ball-squeezing interventions on children's levels of anxiety, fear, and pain during venipuncture procedures. METHODS: This study was designed as a randomized controlled trial. Out of 108 children aged 5-10 years, 72 were allocated to the two experimental groups, while 36 were assigned to the control group. The levels of anxiety, fear, and pain experienced by the children were assessed using the "Wong-Baker FACES® Pain Rating Scale," "Child Anxiety Scale-State," and "Child Fear Scale," respectively. Intergroup comparisons were analyzed using one-way ANOVA, while intragroup comparisons were conducted using Wilks' Lambda analysis. FINDINGS: It was observed that 50% of the children in the control group, 47.2% in the bubble-blowing group, and 47.2% in the ball-queezing group did not receive information about the painful procedure. Anxiety, fear, and pain scores of all groups were statistically similar in the initial measurement without any intervention. Children in the bubble-blowing and ball-squeezing groups experienced lower anxiety, fear, and pain during and at the end of the painful procedures. CONCLUSIONS: The study discovered that interventions involving bubble blowing and ball squeezing significantly decreased children's levels of anxiety, fear, and pain both during and after intravenous procedures. Information on procedures, alongside interactive techniques like bubble blowing and ball squeezing, helps pediatric nurses calm children, easing anxiety, fear, and pain. Implementing these strategies enhances treatment experiences and confidence in healthcare.

Do bitcoin electricity consumption and carbon footprint exhibit random walk and bubbles? Analysis with policy implications.

One of the main current focuses of global economies and decision-makers is the efficiency of energy utilization in cryptocurrency mining and trading, along with the reduction of associated carbon emissions. Understanding the pattern of Bitcoin's energy consumption and its bubble frequency can greatly enhance policy analysis and decision-making for energy efficiency and carbon emission reduction. This research aims to assess the validity of the random walk hypothesis for Bitcoin's electricity consumption and carbon footprint. We employed both traditional methods (ADF and KPSS) and recently proposed unit root techniques that account for structural breaks and non-linearity in the data series. Our analysis covers daily data from July 2010 to December 2021. The empirical results revealed that traditional unit root techniques did not confirm the stationarity of both bitcoin's electricity consumption and carbon footprint. However, novel structural break (SB) and linearity tests conducted enabled us to discover five SB episodes between 2012 and 2020 and non-linearity of the variables, which informed our application of the newly developed non-linear unit root tests with structural breaks. With the new methods, the results indicated stationarity after accommodating the SB and non-linearity. Furthermore, based on Phillips and Shi (2019)'s test, we identified certain bubble episodes in the bitcoin energy and carbon variables between 2013 and 2021. The major drivers of the bubbles in bitcoin energy consumption and carbon footprint are variables relating to the bitcoin and financial markets activities and risks, including the global economic and political risks. The study's conclusion based on the above findings informs several policy implications drawn for energy and environmental management including the encouragement of green investments in cryptocurrency mining and trading.

Numerical simulation study on opening blood-brain barrier by ultrasonic cavitation.

Experimental studies have shown that ultrasonic cavitation can reversibly open the blood-brain barrier (BBB) to assist drug delivery. Nevertheless, the majority of the present study focused on experimental aspects of BBB opening. In this study, we developed a three-bubble-liquid-solid model to investigate the dynamic behavior of multiple bubbles within the blood vessels, and elucidate the physical mechanism of drug molecules through endothelial cells under ultrasonic cavitation excitation. The results showed that the large bubbles have a significant inhibitory effect on the movement of small bubbles, and the vibration morphology of intravascular microbubbles was affected by the acoustic parameters, microbubble size, and the distance between the microbubbles. The ultrasonic cavitation can significantly enhance the unidirectional flux of drug molecules, and the unidirectional flux growth rate of the wall can reach more than 5 %. Microjets and shock waves emitted from microbubbles generate different stress distribution patterns on the vascular wall, which in turn affects the pore size of the vessel wall and the permeability of drug molecules. The vibration morphology of microbubbles is related to the concentration, arrangement and scale of microbubbles, and the drug permeation impact can be enhanced by optimizing bubble size and acoustic parameters. The results offer an extensive depiction of the factors influencing the blood-brain barrier opening through ultrasonic cavitation, and the model may provide a potential technique to actively regulate the penetration capacity of drugs through endothelial layer of the neurovascular system by regulating BBB opening.

Performance Evaluation of UOWC Systems from an Empirical Channel Model Approach for Air Bubble-Induced Scattering.

Underwater optical wireless communication (UOWC) systems provide the potential to establish secure high-data-rate communication links in underwater environments. The uniqueness of oceanic impairments, such as absorption, scattering, oceanic turbulence, and air bubbles demands accurate statistical channel models based on empirical measurements for the development of UOWC systems adapted to different types of water and link conditions. Recently, generalized Gamma and a mixture of two generalized Gamma probability density functions (PDF) were proposed to describe the statistical behavior of small and large air bubbles, respectively, when considering several levels of particle-induced scattering. In this paper, we derive novel closed-form analytic expressions to compute the bit error rate (BER) and outage performance using both proposed PDFs for various scattering conditions. Furthermore, simple asymptotic expressions are obtained to determine the diversity order of each scenario. Monte Carlo simulation results verify the obtained theoretical expressions. Our results also reveal that UOWC systems present lower BER and outage performance under more turbid water cases with respect to the tap water case due to the higher diversity order and despite the significant increases in pathloss at short link distances. Particle-induced scattering provides an inherent mechanism of turbid waters to mitigate air bubble-induced fluctuations and light blockages.

In-party love spreads more efficiently than out-party hate in online communities.

In this article, we present the findings of a comprehensive longitudinal social network analysis conducted on Twitter across four consecutive election campaigns in Spain, spanning from 2015 to 2019. Our focus is on the discernible trend of increasing partisan and ideological homogeneity within interpersonal exchanges on this social media platform, alongside high levels of networking efficiency measured through average retweeting. This diachronic study allows us to observe how dynamics of party competition might contribute to perpetuating and strengthening network ideological and partisan homophily, creating 'epistemic bubbles' in Twitter, yet showing a greater resistance to transforming them into 'partisan echo-chambers.' Specifically, our analysis reveals that the rise of a new radical right-wing party (RRP), Vox, has heightened ideological homogeneity among users across the entire ideological spectrum. However, this process has not been uniform. While users aligned with mainstream political parties consistently share content that reinforces in-party affinity, resulting in highly efficient 'epistemic bubbles,' the emergence of the RRP has given rise to a distinct group of users associated with the most extreme partisan positions, characterized by a notable proportion of out-partisan hostility content, which has fostered the creation of low-efficient 'partisan echo-chambers.'

Synthesis of new defoamer agents and characterization of cementitious formulations.

The production of cementitious formulations involves the addition of chemical additives essential for the optimization of many properties. Superplasticizers are considered additives of great interest but when mixed with concrete they lead to an undesirable increase of air content, with the consequent development of foam. This can adversely affect both mechanical properties and workability, therefore, the use of an antifoam agent is also necessary which should be able to prevent or destroy the foam. This work aims to synthesize esters derived from the reaction of glycine betaine with saturated and unsaturated fatty alcohols of different chain lengths. The reaction products were analyzed by 1H NMR analysis, and the stability of antifoam agents in a superplasticizer solution was studied through foaming tests according to the Ross-Miles method. At the same time, their effectiveness in the cementitious systems was evaluated through flow Table tests. Finally, the effectiveness of the antifoam agents was quantified through an image analysis software, Image J, which allowed the investigation of the contents of the bubble in concrete samples. All synthesized antifoams showed properties superior to the commercial product, especially defoamers containing saturated fatty alcohols. It has been found that alcohols with too small or too long carbon chains were not effective. In particular, it was verified the optimal range of carbon atoms number contained in the antifoam chain which included between 12 and 14.