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This study considers the influence of purity and surface area on the thermal and oxidation properties of hexagonal boron nitride (h-BN) nanoplatelets, which represent crucial factors in high-temperature oxidizing environments. Three h-BN nanoplatelet-based materials, synthesized with different purity levels and surface areas (~3, ~56, and ~140 m2/g), were compared, including a commercial BN reference. All materials were systematically analyzed by various characterization techniques, including gas pycnometry, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared radiation, X-ray photoelectron spectroscopy, gas sorption analysis, and thermal gravimetric analysis coupled with differential scanning calorimetry. Results indicated that the thermal stability and oxidation resistance of the synthesized materials were improved by up to ~13.5% (or by 120 °C) with an increase in purity. Furthermore, the reference material with its high purity and low surface area (~4 m2/g) showed superior performance, which was attributed to the minimized reactive sites for oxygen diffusion due to lower surface area availability and fewer possible defects, highlighting the critical roles of both sample purity and accessible surface area in h-BN thermo-oxidative stability. These findings highlight the importance of focusing on purity and surface area control in developing BN-based nanomaterials, offering a path to enhance their performance in extreme thermal and oxidative conditions. [ABSTRACT FROM AUTHOR]

Pickering emulsions (PE) are liquid-liquid systems that are stabilized by solid (nano)particles at the fluid interface. They offer higher stability, easier separation and lower toxicity compared to classical emulsions stabilized by surfactants. Common applications range from food science to drug delivery. In the last decade they have become of more interest in the field of multiphasic biocatalysis. First, this study aims to present the influence of pH, salt strength and particle charge on enzyme activity. The different behavior of two lipases (CaLA and CRL) is shown. While the activity optimum of CaLA changed from pH 6.5 to pH 5 by applying particles with negative instead of positive surface charge, the CRL activity optimum stayed at pH 5–5.5. This enables particle charge as an additional parameter to optimize biocatalytic reactions in PEs. Second, the resulting drop sizes were measured to elucidate further interactions between the enzymes and particles in PEs. Drop sizes in PEs prepared with CaLA were not influenced by pH, but increased for positively and decreased for negatively charged particles upon the addition of CaLA. Electrostatic attraction between particles and CRL increased the droplet diameter from 10 μm up to 30 μm and therefore destabilized the PE for both particle types. • Influence of pH, salt strength and particle charge on CaLA and CRL activity inside Pickering emulsions. • activity optimum of CaLA can be shifted to a different pH with varying particle charge. • activity optimum of CRL close to IEP. • CaLA may stabilize or destabilize Pickering emulsions depending on particle charge. [ABSTRACT FROM AUTHOR]

Ultrasonic mixing is a well‐established method to disperse and mix substances. However, the effects of ultrasound on dispersed soft particles as well as on their adsorption kinetics at interfaces remain unexplored. Ultrasound not only accelerates the movement of particles via acoustic streaming, but recent research indicates that it can also manipulate the interaction of soft particles with the surrounding liquid. In this study, it evaluates the adsorption kinetics of microgel at the water‐oil interface under the influence of ultrasound. It quantifies how acoustic streaming accelerates the reduction of interfacial tension. It uses high‐frequency and low‐amplitude ultrasound, which has no destructive effects. Furthermore, it discusses the ultrasound‐induced shrinking and thus interfacial rearrangement of the microgels, which plays a secondary but non‐negligible role on interfacial tension reduction. It shows that the decrease in interfacial tension due to the acoustic streaming is stronger for microgels with higher cross‐linker density. Moreover, it shows that ultrasound can induce a reversible decrease in interfacial tension due to the shrinkage of microgels at the interface. The presented results may lead to a better understanding in any field where ultrasonic waves meet soft particles, e.g., controlled destabilization in foams and emulsions or systems for drug release. [ABSTRACT FROM AUTHOR]

In this report, we investigate dynamic light scattering (DLS) from both randomly diffusing silica particles and acousto-responsive microgels in aqueous dispersions under ultrasonic vibration. Employing high-frequency ultrasound (US) with low amplitude ensures that the polymers remain intact without damage. We derive theoretical expressions for the homodyne autocorrelation function, incorporating the US term alongside the diffusion term. Subsequently, we successfully combined US with a conventional DLS system to experimentally characterize compact silica particles and microgels under the influence of US. Our model allows us to extract essential parameters, including particle size, frequency, and amplitude of particle vibration, based on the correlation function of the scattered light intensity. The studies involving non-responsive silica particles demonstrate that the US does not disrupt size determination, establishing them as suitable reference systems. In addition, we could be able to experimentally resolve the µs-order motion of particles for the first time. Microgels subjected to the US show the same swelling/shrinking behavior as that induced by temperature but with significantly faster kinetics. The findings of this study have potential applications in various industrial and biomedical fields such as smart coatings and drug delivery that benefit from the characterization of macromolecules subjected to the US. Furthermore, the current work may lead to characterizing the mechanical properties of soft particles based on their vibration amplitude extracted using this method. [ABSTRACT FROM AUTHOR]

The incorporation of soft hydrophilic particles at the interface of water in non-polar oil emulsion droplets is crucial for several applications. However, the stabilization of water in non-polar oil emulsions with hydrophilic soft material alone is, besides certain exceptions, not possible. In our previous works, we showed that stabilizing the emulsions with well-characterized spherical hydrophobic silica nanospheres (SNs) and soft equally charged microgel particles (MGs) is a robust strategy to stabilize w/o emulsions while still incorporating a large amount of MGs at the interface. In the present study, we address the question of what the maximum amount of MGs at the interface in these kinds of emulsion droplets can be. By using well-characterized mono-disperse SNs, we are able to calculate the fraction of interface covered by the SNs and complementary that of the present MG. We found that it is not possible to decrease the SN coverage below 56% irrespective of MG softness and SN size. The findings elucidate new perspectives to the broader topic of soft/solid stabilized emulsions. [ABSTRACT FROM AUTHOR]

Coffee, as one of the most traded resources, generates a vast amount of biogenic by-products. Coffee silver skins (CSS), a side stream from the roasting process, account for about 4 wt.%. Despite the abundancy of CSS, possible routes to generate added value for broad applications are limited. Herein, we present an approach to use CSS as a precursor material for supercapacitor electrodes. KOH activated carbon (AC) was produced from CSS. The resulting AC—CSS was characterized by X-ray diffraction, gas sorption analysis, scanning electron microscopy, and Raman spectroscopy. The highly porous AC—CSS exposes a specific surface area of more than 2500 m2 g−1. Electrodes formed with AC—CSS were electrochemically characterized by performing cyclic voltammetry and galvanostatic cycling. The electrodes were further assembled into a supercapacitor device and operated using 1 M sulfuric acid as electrolyte. In addition, various quinones were added to the electrolyte and their impact on the capacitance of AC—CSS electrodes was analyzed. In this work, we were able to show that CSS are a valuable source for supercapacitor applications and that coffee-waste-derived quinones can act as capacitance enhancers. Thus, the findings of this research show a valuable path towards sustainable and green energy storage solutions. [ABSTRACT FROM AUTHOR]

The complexation of microgels with rigid nanoparticles is an effective way to impart novel properties and functions to the resulting hybrid particles for applications such as in optics, catalysis, or for the stabilization of foams/emulsions. The nanoparticles affect the conformation of the polymer network, both in bulk aqueous environments and when the microgels are adsorbed at a fluid interface, in a non-trivial manner by modulating the microgel size, stiffness and apparent contact angle. Here, we provide a detailed investigation, using light scattering, in-situ atomic force microscopy and nano-indentation experiments, of the interaction between poly(N-isopropylacrylamide) microgels and hydrophobized silica nanoparticles after mixing in aqueous suspension to shed light on the network reorganization upon nanoparticle incorporation. The addition of nanoparticles decreases the microgels' bulk swelling and thermal response. When adsorbed at an oil-water interface, a higher ratio of nanoparticles influences the microgel's stiffness as well as their hydrophobic/hydrophilic character by increasing their effective contact angle, consequently modulating the monolayer response upon interfacial compression. Overall, these results provide fundamental understanding on the complex conformation of hybrid microgels in different environments and give inspiration to design new materials where the combination of a soft polymer network and nanoparticles might result in additional functionalities. [ABSTRACT FROM AUTHOR]

This study reports on the low-pressure hydrogen (H 2) and deuterium (D 2) physisorption processes in nanoporous activated carbon cloth at supercritical temperatures. In-situ small-angle neutron scattering (SANS) is employed as a hydrogen-sensitive method to determine the pore-size-dependent and isotope-dependent adsorbate densification for different gas pressures up to 1 bar. The changes of the SANS signal resulting from the physisorption of adsorbate molecules in the pore space is described by analytical pore scattering functions resembling slit-like pores. Analysis based on a hierarchical pore model allows quantifying the pore-size-dependent physical density of the confined adsorbate for three pore classes, resembling roughly the IUPAC classes of ultramicropores, supermicropores, and mesopores. While the adsorbate density within the very smallest pores approaches the bulk solid density of H 2 for pressures of about 1 bar at 77 K, it remains much lower for larger pores. A high density is also found for D 2 within ultramicropores, but these results are hampered by a subtle effect of an exchange of chemically bound hydrogen by deuterium in the sample. These findings contribute to a fundamentally better understanding of confinement effects on hydrogen densification, and affect materials design for efficient hydrogen storage devices working at realistic cryogenic conditions and low pressures. [Display omitted] • Quantification of density evolution of H 2 and D 2 adsorbed in nanoporous activated carbon cloth at supercritical temperatures. • Hierarchical model of slit-like pores for SANS data reveals pore-size-dependent adsorbate densification. • Adsorbate density in pores smaller than 0,7 nm approaches bulk solid density at 77 K and ambient pressure. [ABSTRACT FROM AUTHOR]

Most of the commonly used microgels (MGs) are hydrophilic and tend to form oil-in-water emulsions. In this review, we discuss the function of MGs at the droplet interface in order to stabilize water-in-oil (w/o) emulsions. This topic addresses both interesting questions in fundamental research and a significant impact for applications, where the w/o emulsion type is of essential importance. Promising approaches to stabilize w/o emulsions with MGs are highlighted from different perspectives, ranging from novel MG modifications to assisted co-stabilization by adding soft or hard particles. We summarize the accumulated knowledge, evaluate the challenges and solutions, and highlight future research trends. [Display omitted] • The swelling ability of microgels in oil decides the type of emulsion (oil-in-water or water-in-oil emulsion). • The swelling ability of microgels is considered as the analog of the wettability of solid particles. • Stabilization of w/o emulsions can be realized via microgel modification or the implementation of a second stabilizer. • Water-in-oil emulsions that contain microgels as stabilizers offer a large variety of possible applications. [ABSTRACT FROM AUTHOR]

In this study, a first approach to model drop size distributions in agitated nanoparticle-stabilized liquid/liquid systems with population balance equations is presented. Established coalescence efficiency models fail to predict the effect of steric hindrance of nanoparticles at the liquid/liquid interface during the film drainage process. A novel modified coalescence efficiency is developed for the population balance framework based on the film drainage model. The elaborate submodel considers the desorption energy required to detach a particle from the interface, representing an energy barrier against coalescence. With an additional implemented function in the population balance framework, the interface coverage rate by particles is calculated for each time step. The transient change of the coverage degree of the phase interface by particles is thereby considered in the submodel. Validation of the modified submodel was performed with experimental data of agitated water-in-oil (w/o) dispersions, stabilized by well-defined spherical silica nanoparticles. The nanospheres with a size of 28 nm are positively charged and were hydrophobized by silanization with dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammoniumchloride. This modeling approach is a first step toward predicting time-resolved dynamic drop size distributions of nanoparticle-stabilized liquid/liquid systems. [ABSTRACT FROM AUTHOR]

Abstract: Hitchin shows in [N. Hitchin, The geometry of three-forms in six and seven dimensions, J. Differ. Geom. 55 (2000) 547–576. math.DG/0010054v1; N. Hitchin, Stable forms and special metrics, Global Differential Geometry: The Mathematical Legacy of Alfred Gray, in: Contemp. Math., volume 288, American Math. Soc., 2001, pp. 70–89. math.DG/0107101v1] that half-flat -structures on a six-dimensional manifold can be lifted to parallel -structure on the product . We show that Hitchin’s approach can also be used to construct nearly parallel -structures by lifting so-called nearly half-flat structures. These -structures are described by pairs of stable 2- and 3-forms with , for some . [Copyright &y& Elsevier]

This work addresses the influence of partially hydrophobic aluminum particles on the interfacial properties of o/w and w/o dispersions. For this purpose, drop size distributions are determined in an agitated tank followed by batch settling experiments after stirrer stop. In presence of hydrophobized aluminum particles, the type of dispersion (o/w or w/o) has an unexpected influence on coalescence behavior. Particles accelerate the coalescence for o/w dispersions (low oil fraction) but hinder the coalescence for w/o dispersions (high oil fraction). For a deeper understanding of this effect, an in-depth characterization and comparison of the drop size distributions of the two dispersion types was performed. [Display omitted] • Aluminum particles induce opposing coalescence behavior in o/w and w/o dispersions. • Endoscope technique can track transient changes in particle-stabilized drop size. • Batch settling experiments are a useful tool to characterize coalescence behavior. [ABSTRACT FROM AUTHOR]

• First comparative study on filtration of particle/oil suspensions, o/w and w/o PE. • Gelling of particles can significantly improve filtration performance. • Possible enhancement of membrane performance after particle contact with membrane. • w/o PE show disproportionate increase of permeability. • Membrane pre-treatment: higher permeability and linear increase of flux with pressure. In recent years, Pickering emulsions (PE) have become of increasing interest for their application in (bio-) catalytic multiphase processes. To design an economically feasible process, an efficient and effective catalyst recovery is necessary. Ultrafiltration of PE has been shown to be a promising procedure. In this work, the influence of drop size distributions and rheology on the ultrafiltration of water-in-oil and oil-in-water PE stabilized by different nanoparticles as well as organic solvent-nanoparticle suspensions was studied. Particles with higher hydrophobicity led to larger Sauter mean diameters. Depending on the ability of silica particles to form three-dimensional network structures, shear thinning or Newtonian rheological behavior was obtained. When suspensions of particles with gelling properties were filtered, an increase in flux compared to the filtration of the pure organic solvent was observed. Water-in-oil PE showed – regardless of investigated particle type and concentration – a disproportionate increase of flux with pressure. However, adjusting the membrane pre-treatment procedure led to a linear dependency between flux and pressure, which was also observed for oil-in-water PE (without special pre-treatment). This work shows that the ultrafiltration of PE made from various nanoparticles is possible and contributes to a better understanding of PE characteristic properties and their influence on the ultrafiltration behavior. [ABSTRACT FROM AUTHOR]

This article presents a systematic mapping study on the model‐driven engineering of safety and security concerns in software systems. Combined modeling and development of both safety and security concerns is an emerging field of research as both concerns affect one another in unique ways. Our mapping study provides an overview of the current state of the art in this field. This study carefully selected 143 publications out of 27,259 relevant papers through a rigorous and systematic process. This study then proposes and answers questions such as frequently used methods and tools and development stages where these concerns are typically investigated in application domains. Additionally, we identify the community's preference for publication venues and trends. The discussion on obtained results also features the gained insights and future research directions. [ABSTRACT FROM AUTHOR]

In situ small‐angle X‐ray scattering (SAXS) was employed to identify critical parameters during thermal treatment for template removal of an ordered mesoporous carbon precursor synthesized via a direct soft‐templating route. The structural parameters obtained from the SAXS data as a function of time were the lattice parameter of the 2D hexagonal structure, the diameter of the cylindrical mesostructures and a power‐law exponent characterizing the interface roughness. Moreover, detailed information on contrast changes and pore lattice order was obtained from analysis of the integrated SAXS intensity of the Bragg and diffuse scattering separately. Five characteristic regions during heat treatment were identified and discussed regarding the underlying dominant processes. The influence of temperature and O2/N2 ratio on the final structure was analyzed, and parameter ranges were identified for an optimized template removal without strongly affecting the matrix. The results indicate that the final structure and controllability of the process are optimum for temperatures between 260 and 300°C with a gas flow containing 2 mol% of O2. [ABSTRACT FROM AUTHOR]

This study investigates the capability of the Southeast Mesohellenic Trough (SE MHT) sandstone formations to serve as a potential reservoir for CO2 storage in response to the emerging climate change issues by promoting environmentally friendly mineral sequestration applications. Sandstone samples, for the first time, were evaluated for their petrographic characteristics, mineral chemistry, geochemical properties, as well as their petrophysical and gas adsorption properties through tests. The sandstones were tested and classified into distinct groups. The most promising site to be considered for pilot CO2 storage testing is the Pentalofos Formation locality since its sandstones display specific mineral phases with the proper modal composition to conceivably react with injected CO2, leading to the development of newly formed and stable secondary mineral phases. The gas adsorption results are also more encouraging for sandstones from this sedimentary formation. All the measured UCS (uniaxial compressive strength), Ei (bending stiffness), and ν (Poisson's ratio) results are above those dictated by international standards to perform CO2 storage practices safely. Furthermore, the specified targeted locality from the Pentalofos Formation holds the geological advantage of being overlaid by an impermeable cap-rock formation, making it suitable for deploying CO2 mineralization practices. The demarcated area could permanently store a calculated amount of ~50 × 105 tons of CO2 within the geological reservoir by reacting with the specified mineral phases, as specified through the proposed petrographic PrP index (potential reactive phases). [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyaniline-derived activated carbon was studied for H 2 storage and supercapacitors. • A known commercial activated carbon with larger pore sizes was used as a reference. • Strong interaction with H 2 and reversible H 2 uptake of ~5.5 wt% at 77 K and ~60 bar. • Excellent electrochemical energy storage behavior using an aqueous CsCl electrolyte. • Smaller pore sizes are responsible for the enhanced performance in both applications. The development and in-depth characterization of multifunctional materials with versatile use in energy and environmental applications has been a topic of on-going investigations. In this work, a nanoporous polymer-/polyaniline-derived activated carbon (PDAC), with large surface area (~2200 m2/g) and large pore volume (~1 cm3/g), was thoroughly studied towards its applicability for H 2 storage and supercapacitor energy storage. The PDAC demonstrated a superior H 2 adsorption performance under cryogenic conditions, reaching a high and fully reversible excess gravimetric H 2 uptake of ~5.5 wt% at 77 K and ~60 bar, along with a ~8.3 kJ/mol heat of adsorption at zero coverage. Furthermore, thin PDAC electrodes with an aqueous CsCl electrolyte were combined in a supercapacitor cell that exhibited a gravimetric capacitance of ~130 F/g for a 0.5 mV/s scanning rate along with a 99% coulombic efficiency and a 100% capacitance retention after 2500 charge/discharge cycles. The PDAC material showed substantially improved H 2 and electrochemical energy storage performance compared to a well-established commercial activated carbon, which is attributed to the overall smaller pore sizes of the PDAC structure. [ABSTRACT FROM AUTHOR]