Polarity Of Medium Research Articles

Co-aggregation between whey proteins and carotenoids from yellow mombin (Spondias mombin): Impact of carotenoids’ self-aggregation

The interaction between whey proteins and carotenoid is reported to improve carotenoid solubility and stability, however, the strong trend of carotenoids to aggregate when in polar systems is often neglected in papers addressing their molecular interaction. Therefore, this study focused on characterizing the aggregative behavior of the carotenoids from yellow mombin (Spondias mombin) and to understand how these carotenoids behave when added to aqueous dispersions of whey proteins. Carotenoids-rich extract, containing mainly β-cryptoxanthin and lutein, was obtained from freeze-dried yellow mombin pulp and its aggregative behavior in ethanol/water medium was studied. By increasing the medium polarity, carotenoids trend to form J-aggregation, causing a drop in the color intensity of the solution. When added to whey protein aqueous dispersions, rather than a protein-carotenoid bimolecular interaction, the formation of co-aggregates between carotenoids and whey proteins was evidenced by preparative size exclusion chromatography. These results may contribute to the developing functional food products.

Identifying elastic wave polarization and bandgaps in periodic solid media

We present a new computational method to accurately identify the elastic wave propagation modes and polarizations in periodic solid structures and metamaterials. The method uses the eigenvectors associated with each propagating wave solution to calculate the contribution of each translational and rotational component of the total mass-in-motion. We use this information to identify the dominant wave propagation mode by defining a relative effective modal mass vector. Then, we associate each wave solution with its correct polarization by defining a polarization factor that quantifies the relative orientation between the wave propagation and lattice motion directions and provides a positive numerical value between 0 (pure S-wave) and 1 (pure P-wave). Further, we suggest a graphical representational scheme for easier visualization of the wave polarization within traditional dispersion plots. To validate the method, we compare our predictions against previously published results for various elastodynamic problems. Finally, we use the proposed method to analyze the effect of various lattice and structural parameter perturbations on the elastic wave propagation and polarized bandgap behavior of a square planar beam lattice. Our analysis reveals the emergence of previously unobserved dynamic characteristics, including various polarized bandgaps, fluid-like behavior, and ultralow-frequency SH- and SV-bandgaps that extend to 0 Hz. Our proposed method provides an alternative computational approach to the typically employed visual mode inspection technique and provides a robust method for analyzing the elastic wave response of periodic solid media.

Polarization in Media Discourses on Europeanization in Spain

Political and media polarization has had a detrimental impact on democratic principles and democratic processes on a global scale. In Europe, such polarization has eroded the trust in national and European institutions and has challenged the basic values that stand at the heart of the European integration project. The aim of this study is to analyze Spanish media discourses on Europeanization, with an attempt to identify key areas in which polarizing narratives related to Europeanization are more prevalent. To conduct our study, six national media outlets were selected based on four criteria: media format, ownership, ideology, and consumption. A final sample of 540 news items collected between July 2021 to March 2022 was selected for analysis. Using a qualitative methodological approach, the study was carried out in two stages. In the first phase, we conducted a content analysis to identify the main topics discussed in relation to the European Union and the actors represented in them. This led to the identification of polarizing narratives and discourses emerging in the context of the discussed topics. In the second phase, we used critical discourse analysis to analyze polarizing discourses.

Convolvulus pluricaulis Choisy's Extraction, Chemical Characterization and Evaluation of the Potential Effects on Glycaemic Balance in a 3T3-L1 Adipocyte Cell Model.

Convolvulus pluricaulis (CP) is a common Indian herb, largely employed in Ayurvedic medicine and known for its neuroprotective and neuroinflammatory action. Its effectiveness against several pathologic/sub-pathologic conditions is widely accepted, but it is not yet completely chemically characterized. In recent years, several researchers have pointed out the involvement of CP and other Convolvulaceae in lipidic and glucidic metabolism, particularly in the control of hyperlipidaemia and diabetic conditions. In this scenario, the aim of the study was to chemically characterize the medium polarity part of the CP whole plant and its fractions and to shed light on their biological activity in adipocyte differentiation using the 3T3-L1 cell model. Our results demonstrated that the CP extract and fractions could upregulate the adipocyte differentiation through the modulation of the nuclear receptor PPARγ (Peroxisome Proliferator-Activated Receptor γ), broadly recognized as a key regulator of adipocyte differentiation, and the glucose transporter GLUT-4, which is fundamental for cellular glucose uptake and for metabolism control. CP also showed the ability to exert an anti-inflammatory effect, downregulating cytokines such as Rantes, MCP-1, KC, eotaxin, and GM-CSF, which are deeply involved in insulin resistance and glucose intolerance. Taken together, these data suggest that CP could exert a potential beneficial effect on glycemia and could be employed as an anti-diabetic adjuvant or, in any case, a means to better control glucose homeostasis.

Indicatrix of TE and TM- polarized wave velocities in crystal of classes 4mm, 3m, 6mm with magneto-electric effect

This work is devoted to the theoretical study of the laws of propagation of electromagnetic waves of TE and TM polarization in anisotropic media belonging to classes 4mm, 3m, 6mm, etc. having a magnetoelectric effect. The directions of the vectors of the phase and group velocities of the polarization waves TE and TM at the boundary of a uniaxial crystal with magnetoelectric properties are considered. In the analytical form, the values of the directions of the phase and group velocities of the TE and TM waves are indicated, depending on the direction of the wave vector of the incident wave. The consequences of the obtained results for uniaxial crystals in the absence of magnetoelectric properties are discussed. The solution of the tasks set in this paper is based on the use of the matrix method. On its basis, various problems of wave processes in an isotropic elastic medium, electromagnetic waves in crystals, the distribution of coupled elastic and electromagnetic waves in piezoelectric and piezomagnetic media with a magnetoelectric effect were previously considered. In the presence of a magnetoelectric effect for electromagnetic waves propagating through uniaxial crystals, the parameters of the wave vector, phase and group velocities are determined. The obtained results are analyzed for electromagnetic waves propagating through uniaxial crystals in the absence of a magnetoelectric effect. The indicatrices of the wave vectors propagating in the plane and the phase velocities of the TM polarization waves are limited ( 0 ) x z. Based on the Rayleigh equation, the values of the group velocity are obtained. The density of electromagnetic energy fluxes and their components are determined for TE and TM waves. The energy transfer rate and its direction are determined. It is shown that the group velocities and directions obtained from the Rayleigh equation and the Umov-Poynting vector do not coincide.

Social Media and Political Polarization in Pakistan

This research paper explores the relationship between social media usage and political polarization in Pakistan. The rapid expansion of social media platforms in recent years has revolutionized the way individuals engage with political content and ideologies. Pakistan, as a diverse and politically vibrant country, offers a compelling case study to investigate the impact of social media on political polarization(Aday et al., 2013). The study employs a mixed-methods approach, combining quantitative analysis of social media data with qualitative interviews and surveys. Firstly, an analysis of social media posts, tweets, and discussions was conducted to identify prevalent political narratives and patterns of polarization. Secondly, interviews and surveys were carried out to gain insights into users' experiences, attitudes, and behaviours concerning political discourse on social media. Furthermore, it explores the impact of echo chambers on fostering extreme viewpoints and the potential for misinformation to spread rapidly in these digital spaces.

Thoughtful design of a covalent organic framework with tailor-made polarity and pore size for the enrichment of bisphenols and their derivatives: Extraction performance, adsorption mechanism and toxicity evaluation

A stable, reusable and cost-effective covalent organic framework (COF) with medium polarity was successfully decorated on Fe3O4. The Fe3O4@COF contained tailor-made polarity and pore size that fitted well with bisphenols and their derivatives (BPs). When coupling magnetic solid-phase extraction (MSPE) with high-performance liquid chromatography (HPLC) detection, the Fe3O4@COF featured efficient recognition and enrichment for BPs due to π-π stacking, C–H⋯π interactions, pore-filling effect, dispersion force and hydrophobic interactions. Under optimized conditions, calibration plots exhibited good linearity (5–1000 ng mL−1), and limits of detection (LOD) ranged from 0.15 to 0.39 ng mL−1. The method was successfully employed in quantifying BPs in authentic lake and river water samples with satisfactory recoveries ranging from 81.4% to 120%. Molecular dynamics simulation revealed extraction mechanisms, and a microscopic behavior related to the clustering property of the emerging brominated compounds was first discovered. Ecotoxicological assessments of target pollutants were conducted from multiple aspects, highlighting the harmfulness of the chemicals and the significance of the analytical method. The proposed methodology offered sensitive detection and quantification, which was beneficial for the timely tracking of the concentration, transportation and distribution of BPs to better explore their environmental behavior and tackle contamination problems in complex environmental matrices.

Investigation on selective separation of oxygen-containing compounds in lignite and sub-bitumite

To realize the high value-added utilization of low-rank coal and elucidate the selectivity of solvent structure and oxygen-containing compounds in low-rank coal, Zhaotong (ZT) lignite and Naomaohu (NMH) sub-bitumite were subjected to thermal dissolution in three types of oxygen-containing solvents with different properties, namely ethanol (ET), tetrahydrofuran (THF) and ethyl acetate (EA). The soluble portions (SPs) obtained were separated by column chromatography into three types of fractions: hydrocarbon (HY), non-hydrocarbon (NHY) and asphaltene (ASP). The results indicated that the yields of SPs in all three solvents for each coal was ET > THF > EA, and the ratios of column chromatographic fractions of SPs of the two coals were significantly different, with lower asphaltene content in the SPs of NMH. The thermal dissolution process of the three solvents significantly reduced the oxygen content of low-rank coal, and the deoxygenation capacity was in the order of ET > THF > EA. More medium or low polarity compounds could be obtained from NMH than from ZT through thermal dissolution process. ET showed excellent selectivity for the generation of both phenols and esters, where the phenols were mainly alkylphenols. THF could release highly condensed polycyclic compounds from coal thus more naphthalenols containing substituent groups were detected in phenols. And it was more selective to COO bonds in NMH than ZT from the results of XPS. More esters were detected in the SPs of NMH compared with ZT. EA had a strong selectivity for CO in low-rank coals, and the thermal dissolution process released a large number of esters, which could be divided into alkanoates and aromatic acid esters. This study can provide a theoretical basis for extracting high value-added chemicals from low-rank coal under mild conditions.

Political polarization of news media and influencers on Twitter in the 2016 and 2020 US presidential elections

Social media has been transforming political communication dynamics for over a decade. Here using nearly a billion tweets, we analyse the change in Twitter’s news media landscape between the 2016 and 2020 US presidential elections. Using political bias and fact-checking tools, we measure the volume of politically biased content and the number of users propagating such information. We then identify influencers—users with the greatest ability to spread news in the Twitter network. We observe that the fraction of fake and extremely biased content declined between 2016 and 2020. However, results show increasing echo chamber behaviours and latent ideological polarization across the two elections at the user and influencer levels.

Electropolymerized polypyrrole silver nanocomposite coatings on porous Ti substrates with enhanced corrosion and antibacterial behavior for biomedical applications

This work proposes an innovative strategy that combines two well-known easy and economical preparation techniques: powder metallurgy based space-holder (SH) technique to provide porous biocompatible Ti substrates with balanced biomechanical behavior (for cortical bone tissue substitution) promoting bone ingrowth and biocoating infiltration, and electropolymerization to coat these substrates with the polypyrrole–silver nanoparticles (PPy-AgNPs) composite conductive polymers improving its corrosion resistance, biocompatibility with enhanced antibacterial activity. The deposited PPy-based coatings present a cauliflower-like structure well adhered to the porous substrates. The macroporosity of and rough inner pore surface of Ti SH substrates are responsible for the superior adhesion of the conductive polymer comparing to typical denser substrates obtained by powder metallurgy or forging. The corrosion protection properties of the coatings were investigated by open circuit potential and Anodic Polarization in PBS media to simulate possible implant conditions, revealing improved corrosion resistance for the composite coatings. The bioactivity of the coatings was evaluated by immersion tests, revealing the formation of Hydroxyapatite after 90-day immersion in PBS. In both PPy and PPy-AgNPs composite coatings, a displacement of the polarization curves to more noble potentials and a decrease in the current density, indicated that the coating's protective character is maintained after 90-day immersion in PBS. The antibacterial activity was assessed by using the Kirby–Bauer disk-diffusion method against Staphylococcus aureus (ATCC 25923). The inhibition halo increased from 5.5 ± 0.4 mm for the bare substrate to 8.2 ± 0.6 mm for the PPy-coated substrate and to 12.5 ± 0.7 mm for the PPy-AgNPs-coated porous Ti. This feature associated to the improved corrosion protection and biocompatibility would significantly contribute to the success of the potential use of porous Ti implants by SH technique envisaging substitution of small damaged bone tissues for example in tumors.

Digital transformation of journalism and media in Serbia: What has gone wrong?

The aim of this paper is to sketch a brief history of complex digital transformation of media and journalism in the context of Serbia, a European country which has undergone politically turbulent transition from authoritarian to democratic rule over the past 20 years. Despite the long process of the EU integration, the country has been recently downgraded to a partly free hybrid regime with rapid decline of press freedom, high political and media polarization and raising political and economic instrumentalization of media. Against this background, the paper problematizes how the main structural transformations of the media environment, such as the transition from state to public broadcasting, the introduction of new media laws and the lengthy process of media privatization intersected and influenced different phases and outcomes of the digital transformation of journalism and news media in the country. Unlike the digital journalism development in established democracies of the West, the real systemic change and adaptation of Serbia’s media market to easy-to-use technologies, newsrooms convergence, profitable content and participatory journalism has been largely limited and overpowered by the interplay between the state and the media over the past two decades.

Electric field activated ON/OFF surface charge polarization of transparent filter media for high-efficiency PM2.5 filtration

It is a cruel reality that the air we breathe has become an invisible but leading danger in terms of public health and the environment. Exposure to fine particulate matter (PM), and indoor volatile organic compounds (VOCs) is particularly harmful to urban residents among the different airborne pollutants. So far, different types of polymers has been widely used to fabricate filter media for clean air. Most of the developed filter are non-transparent not suitable for window. Moreover, the PMs concentration depends on different factors and fluctuates day-to-week and seasonally. Most present development air filter are non-transparent not suitable for window and single functional by their construction, high fiber diameter and large thickness. Therefore, to meet demands, we introduced a transparent advanced air filters with multi-functionality, such as in situ switch based tuning filtration efficiency, VOC adsorption capability and antibacterial properties. We have rationally designed an electric field activated ON/OFF surface charge polarization air filter composed of nanofiber/nets nanoarchitectured networks with 80% optical transparency. The electric field activated nanofiber/nets filter enhanced PM2.5 filtering efficiency from 61% to more than 95% at a low poling voltage of 0.2 kV. More importantly, here the low voltage is adequate to cause a high electric field (MV m−1) and surface charges can form on the fiber surface. In addition, due to the presence of chitosan in nanofiber/nanonet structure the filter can effectively adsorb gases such as ammonia, triethylamine, and formaldehyde and possessed anti-bacterial behaviour for P. aeruginosa and S.aureus. The approach introduced in this work has the potential to filter PMs under extremely hazardous air conditions and can reduce power consumption by turning off the power during low hazardous conditions.

On charged photons in unmagnetized dusty plasma instabilities

Motivated by the expanding interest in complex plasmas, we discuss the equivalent photon charge in dusty electron-ion plasmas. Particularly, we investigate the dusty plasma response in terms of the electron density perturbation driven by electromagnetic waves. The resulting polarization of this plasma medium caused by the photon ponderomotive force of the electromagnetic radiation pressure gives rise to an effective photon electric charge. We determine the acquired photon charge in terms of the involved characteristic parameters. More precisely, here we derive an explicit expression of the photon charge which is found to depend strongly on the free electron density and the photon frequency. Such a photonic charge is relevant for dealing with the photon–plasma couplings in most plasma mediums, namely of the early Universe.

Solvent Effect on Small-Molecule Thin Film Formation Deposited Using the Doctor Blade Technique

Small molecule thin films are the core of some organic optoelectronic devices. Their deposition by solution processes is an advantage for device fabrication and can be achieved via spin coating for small areas and slot-die or doctor blade for larger areas. Solution deposition of small molecule thin films is usually processed only with medium polarity solvents. Herein, the use and influence of solvents with several polarities and physicochemical properties to form small-molecule homogeneous thin films via the doctor blade technique over an area of 25 cm2 have been explored. Solvents with different polarity, heptane, chlorobenzene, N,N-dimethylformamide, acetonitrile, and methanol were used along with different deposition temperatures, from room temperature up to near the boiling temperature for each solvent. With heptane and chlorobenzene, smooth films with an average roughness of 3 nm and thickness of 100–120 nm were obtained. The film was homogeneous over the whole substrate for temperatures from room temperature to close to the boiling temperature of both solvents. On the other hand, with dimethylformamide, a film is observed when the deposition is conducted only at room temperature; when the deposition temperature increases, the formation of agglomerates of several sizes from 1 to 5 nm was observed. With acetonitrile, and methanol, no films were formed, and only nanoaggregates were created on the substrate due to the solvent high vapor pressure, and the agglomerate size depends on the deposition temperature. The measure of the contact angle of pure solvent and solutions indicated that wettability helps to film formation over the whole substrate. For heptane and chlorobenzene, a small angle was measured; meanwhile, the contact angle is large in acetonitrile leading to the formation of nanoaggregates. In the case of methanol solution, although it wets very well, no film is deposited because it has high volatility.

How Do Liquid-Junction Potentials and Medium Polarity at Electrode Surfaces Affect Electrochemical Analyses for Charge-Transfer Systems?

The importance of electrochemical analysis for charge-transfer science cannot be overstated. Interfaces in electrochemical cells present certain challenges in the interpretation and the utility of the analysis. This publication focuses on: (1) the medium polarity that redox species experience at the electrode surfaces that is smaller than the polarity in the bulk media and (2) the liquid-junction potentials from interfacing electrolyte solutions of different organic solvents, namely, dichloromethane, benzonitrile, and acetonitrile. Electron-donor-acceptor pairs of aromatics with similar structures (i.e., 1-naphthylamine and 1-nitronaphthalene, 10-methylphenothiazine and 9-nitroanthracene, and 1-aminopyrene and 1-nitropyrene) serve as redox analytes for this study. Using the difference between the reduction potentials of the oxidized donors and the acceptors eliminates the effects of the liquid junctions on the analysis of charge-transfer thermodynamics. This analysis also offers a means for evaluating the medium polarity that the redox species experience at the surface of the working electrode and the effects of the liquid junctions on the measured reduction potentials. While the liquid-junction potentials between the dichloromethane and acetonitrile solutions amount to about 90 mV, for the benzonitrile-acetonitrile junctions, the potentials are only about 30 mV. The presented methods for analyzing the measured electrochemical characteristics of donors and acceptors illustrate a means for improved evaluation of the thermodynamics of charge-transfer systems.

The influence of roots on soil's electrical signature

Detecting and monitoring roots and their activity in soil is of great importance as it controls water and nutrient transport, soil carbon dynamics, and soil microorganisms. However, roots are hidden in the soil, they are heterogeneous, and dynamics; therefore, in-situ measurements of their properties and the involved processes are highly challenging. The spectral induced polarization (SIP) is a geophysical method that allows noninvasive mapping of subsurface properties and processes. Recently, the quadrature conductivity (measured with the SIP method) was positively correlated with root biomass and root surface area in hydroponics. Unlike the nonpolarized hydroponic solution (at frequencies <1000 Hz, relevant to the SIP method), the soil is a polarizable medium, and various soil-root interactions (e.g., water and nutrient uptake, root exudation, etc.) are expected to influence the soil SIP signature. Therefore, this research aimed to assess the impact of roots on the SIP signature of soil. We conducted a series of experiments in which we measured and monitored the SIP signature of soil in which wheat plants are growing. Supplementary measurements included soil water content, pore water salinity, and root biomass. Our results show that, unlike in hydroponic, there is an inverse relationship between root biomass and quadrature conductivity. Most of the decrease in the quadrature conductivity was associated with the water content decrease. We suggest that the unexplained decline in the quadrature conductivity is associated with various soil-root interactions, such as selective uptake of nutrients and root exudation, but further research is needed.

Analysis of individual characteristics influencing user polarization in COVID-19 vaccine hesitancy.

During the COVID-19 pandemic, vaccine hesitancy proved to be a major obstacle in efforts to control and mitigate the negative consequences of COVID-19. This study centered on the degree of polarization on social media about vaccine use and contributing factors to vaccine hesitancy among social media users. Examining the discussion about COVID-19 vaccine on the Weibo platform, a relatively comprehensive system of user features was constructed based on psychological theories and models such as the curiosity-drive theory and the big five model of personality. Then machine learning methods were used to explore the paramount impacting factors that led users into polarization. Findings revealed that factors reflecting the activity and effectiveness of social media use promoted user polarization. In contrast, features reflecting users' information processing ability and personal qualities had a negative impact on polarization. This study hopes to help healthcare organizations and governments understand and curb social media polarization around vaccine development in the face of future surges of pandemics.

Biodegradable and active zein-gelatin-based electrospun mats and solvent-cast films incorporating sage extract: Formulation and comparative characterization

This study aimed to develop active, biodegradable materials for food packaging by incorporating sage extract (SE) within a zein-gelatin blend by electrospinning and solvent casting. The fabrication techniques, SE incorporation, and its content (5, 10% w/w) determined the materials’ properties. Electrospinning produced 0.36–0.53 mm thick, non-transparent fibrous mats (mean fiber diameter 1.12–1.36 µm). Solvent casting generated 0.34–0.41 mm thick, transparent continuous films. The analysis indicated the constituents’ compatibility, homogenous dispersion, and efficient SE incorporation without strong chemical interactions and phase separation. The solvent-cast films presented more ordered structures, higher mechanical resistance, elongation, and water vapor barrier performance than the electrospun mats. The SE-incorporating formulations showed phenolics’ delivery ability to food simulants influenced by structure, SE content, and media polarity. The electrospun mats expressed higher DPPH• radicals’ inhibition, while the solvent-cast films showed stronger Staphylococcus aureus and Escherichia coli growth inhibition, increased by SE incorporation. All formulations showed rapid complete bio-disintegration in compost (18–25 days).

Befriended to polarise? The impact of friend identity on review polarisation—A quasi‐experiment

AbstractOpinion polarisation in social media has recently become a significant issue. The existing literature mainly attributes polarisation to online friends' informational social influence, that is, users are more likely to interact with others with similar opinions, which leads to the echo chamber effect. However, the impact of social interaction on individual polarisation may also result from normative social influence, which varies with social settings on the platform. In this paper, we leverage a quasi‐experiment to investigate the normative social influence of online friends on focal users' review polarity. We use fixed effects and difference‐in‐differences approaches, along with propensity score matching, to address the potential endogeneity in users' friend function adoption decisions. Our results indicate that adopting the friend function leads users to post less extreme ratings. We further separate the reviews into positive and negative, finding that the reduction in the review polarity for positive reviews is more prominent than for negative ones. Regarding user heterogeneity, our causal forest analysis uncovers that users with a higher engagement level on the platform are less affected by adopting the friend function than those with less engagement. Our study has clear implications for managers and platform designers, highlighting the importance of social function design in reducing social media induced polarisation.

Introduction to Freedom of Expression in an Age of Social Media, Misinformation, and Political Polarization

Introduction to Freedom of Expression in an Age of Social Media, Misinformation, and Political Polarization