On the Impact of Electrostatic Correlations on the Double-Layer Polarization of a Spherical Particle in an Alternating Current Field

At concentrated electrolytes, the ion–ion electrostatic correlation effect is considered an important factor in electrokinetics. In this paper, we compute, in theory and simulation, the dipole moment for a spherical particle (charged, dielectric) under the action of an alternating electric field using the modified continuum Poisson–Nernst–Planck (PNP) model by Bazant et al. [Double Layer in Ionic Liquids: Overscreening Versus Crowding. Phys. Rev. Lett. 2011, 106, 046102] We investigate the dependency of the dipole moment in terms of frequency and its variation with such quantities like ζ-potential, electrostatic correlation length, and double-layer thickness. With thin electric double layers, we develop simple models through performing an asymptotic analysis of the modified PNP model. We also present numerical results for an arbitrary Debye screening length and electrostatic correlation length. From the results, we find a complicated impact of electrostatic correlations on the dipole moment. For instance, with increasing the electrostatic correlation length, the dipole moment decreases and reaches a minimum and then it goes up. This is because of initially decreasing of surface conduction and finally increasing due to the impact of ion–ion electrostatic correlations on ion’s convection and migration. Also, we show that in contrast to the standard PNP model, the modified PNP model can qualitatively explain the data from the experimental results in multivalent electrolytes

Secrecy performance analysis of a cognitive network for IoT over k-μ channels

With the development of Internet of Things (IoTs), devices are now connecting and communicating together on a heretofore unheard-of scale, forming huge heterogeneous networks of mobile IoT-enabled devices. For beyond 5G- (B5G-) enabled networks, this raises concerns in terms of spectral resource allocation and associated security. Cognitive radio is one effective solution to such a spectrum sharing issue which can be adopted to these B5G networks, which works on the principle of sharing spectrum between primary and secondary users. In this paper, we develop the confidentiality of cognitive radio network (CRNs) for IoT over k-μ fading channels, with the information transmitted between secondary networks with multiple cooperative eavesdroppers, under the constraint of the maximum interference that the primary users can tolerate. All considered facilities use a single-antenna receiver. Of particular interest, the minimum limit values of secure outage probability (SOP) and the probability of strictly positive secrecy capacity (SPSC) are developed for this model in a concise form. Finally, the Monte Carlo simulations for the system are provided to support the theoretical analysis presente

Interfacial Sintering of PU/MXene Foam for Piezoresistive Sensor with Superior Sensitivity, Mechanical Performance, and Durability

High sensitivity, good mechanical property, and durability are critical parameters to value piezoresistive sensing performance, which highly rely on the interfacial interaction between the conductive filler and the polymer matrix. Using polydopamine (PDA) to improve the interfacial interaction is the usually adopted manner. However, unsatisfactory sensing performance is afforded, resulting from the formation of inhomogeneous deposition of PDA on the polymer matrix. In this work, for the first time, a piezoresistive sensor comprising anisotropic PU foam with a tightly adhered MXene conductive layer (MXene@PU) is fabricated by microwave sintering. The strong interfacial adhesion induced by microwave sintering coupled with the stress–strain amplification effect imparted by the aligned parallel channels of the directional TPU foams results in trinity excellence in sensitivity, mechanical performance, and durability. As a result, the as-fabricated sensor delivers a high sensitivity of 0.109 kPa–1, an impressive gauge factor of 7.78, and an excellent mechanical property with a compressive strength of 1603 kPa at 80% strain, which is 11.1 times, 16.2 times, and 1.6 times that of PDA-treated traditional ones, respectively. Moreover, superior durability is demonstrated for the MXene@PU foam sensor even under macropressure or macrostrain, which is a big challenge for conductive nanomaterial-coated polymer matrix-derived sensors. This novel approach provides a practical methodology for architecting a high-performance piezoresistive sensor that is very attractive in the intelligent sensing field

Study of the molecular array behaviours and interfacial activities of green surfactant alkyl polyglycoside and the mixed systems with other surfactants on oil–water interface

<p>The widely performance of surfactants is closely related to their interfacial activity, which is essentially determined by the molecular array behaviours at the interface, of which the studies are significance for clearly understanding their structure-performance relationships. In this paper, the detailed molecular array behaviours of green surfactant alkyl polyglycoside (APG) and the mixed systems with other types of surfactants on oil/water interface have been studied using molecular dynamics simulations, and the key theoretical principle was confirmed by quantum chemistry calculations. It was found that the hydrophilic maltose ring head groups of decyl polyglycoside (C₁₀-APG) are prone to lie flatly at the oil–water interface, the steric hindrance results in the low interfacial density, which critically determines the limit of the interfacial activity. The interfacial adsorption behaviours of the binary mixtures of C₁₀-APG and SDS or DATB and the ternary mixtures of C₁₀-APG, SDS and DATB were studied in detail, how the efficient synergism effect could be achieved for the mixture to get super high interfacial activity was discussed. This study provides a strategy to reveal how the molecular interfacial behaviours determine the key interfacial characteristics of the novel surfactants, which might provide help to promote their applications.</p

Mechanically Robust Flexible Polyurethane Foams Formulated with Polyols Comprising Soybean Protein

Soybean protein is a compelling raw material for the preparation of high-performance biobased polyurethane (PU) foams in light of its rich polyfunctional moieties containing active hydrogens. However, soybean protein is immiscible with polyols owing to the presence of numerous carboxylic groups of strong polarity, which in turn results in below-par mechanical performance when it is simply applied as a spherical physical filler in a target matrix. In this study, the solubility of soybean protein in polyols is realized through esterification to enable a designated hydroxyl functionality. The esterification process not only converts the original carboxylic group into an ester moiety but also correspondingly introduces hydroxyl groups into the macromolecules. This increases the content of active hydrogens, which ultimately facilitates the subsequent reactions with isocyanates. As a result, the esterified soybean protein (ESP)-derived flexible PU foam exhibits dual excellence in tensile strength and toughness, and its compressive strength and modulus have been improved by 3.2 and 2.5 times, respectively, when compared to the unmodified SP-reinforced PU. Moreover, the incorporation of ESP into the PU framework on a molecular level enables the formation of a secondary interpenetrating network that improves the resilience of the matrix. The as-fabricated foam delivers a superior compressive recovery rate of up to 98.6% even after 150 cycles, which stands out prominently among reports on biobased PU. This work demonstrates a simple and green method to transform soybean protein into biomass-derived multifunctional polyols, which could spur innovations from the community toward high-performance biobased polymeric materials

A Co-Crystal Strategy to Tune the Supramolecular Patterns and Luminescent Properties: Ten Well-Designed Salts Assembled by Arenedisulfonic Acid with Diverse Diamines

Ten salts assembled by arenedisulfonic acid with hydrazine, flexible aliphatic diamines, rigid and semirigid aromatic diamines, namely, (H₂HA)²⁺·(NDS)^2– (<b>1</b>), (H₂EDA)²⁺·(NDS)^2– (<b>2</b>), (H₂PDA)²⁺·(NDS)^2– (<b>3</b>), (H₂BTDA)²⁺·(NDS)^2– (<b>4</b>), (H₂BDMA)²⁺·(NDS)^2–·2H₂O (<b>5</b>), 2­(<i>o</i>-HBDA)⁺·(NDS)^2– (<b>6</b>), (<i>m</i>-H₂BDA)²⁺·(NDS)^2– (<b>7</b>), (H₂MBDA)²⁺·(NDS)^2–·3H₂O (<b>8</b>), (H₂SDA)²⁺·(NDS)^2–·H₂O (<b>9</b>), and 2­(HSDA)⁺·(NDS)^2–·H₂O (<b>10</b>) (H₂NDS = 1,5-naphthalenedisulfonic acid, HA = hydrazine, EDA = 1,2-ethanediamine, PDA = 1,3-propanediamine, BTDA = 1,4-butanediamine, BDMA = 1,3-benzenedimethanamine, <i>o</i>-BDA = 1,2-benzenediamine, <i>m</i>-BDA = 1,3-benzenediamine, MBDA = 4-methyl-1,3-benzenediamine, SDA = 4,4′-sulfonyldiamiline), have been constructed and characterized by elemental analysis, infrared, thermogravimetric analysis, phospholuminescence, and powder and single-crystal X-ray diffraction. Structural analyses indicate that the nature of the diamines can effectively influence the final structures of the salts through diverse noncovalent bonding interactions, such as hydrogen bonds, π···π stacking, N–H···π, C–H···π, and lone pair···π interactions, which result in six types of architectures. Crystals <b>1</b>–<b>3</b> exhibit a three-dimensional (3-D) pillared layered supramolecular network with the diammonium cations being sandwiched among the sulfonate groups, while crystal <b>4</b> exhibits a 3-D “honeycomb” network with the −(CH₂)₄– groups being encapsulated among the NDS^2– anions. In comparison with crystal <b>4</b>, crystals <b>5</b>, <b>7</b>, and <b>8</b> exhibit a different 3-D supramolecular network, in which the phenylene, phenyl, and methylphenyl groups interpenetrate with the naphthyl rings of NDS^2– anions through continuous π···π interactions. Crystal <b>6</b> is two-dimensional pillared layered network with the <i>o</i>-HBDA⁺ cations arranging along the two sides of the layer. Crystal <b>9</b> possesses an organic 3-D supramolecular network formed by the C–H···π and sulfonyl involved lone pair···π interactions which encapsulates a one-dimensional (1-D) infinite [−SO₃···H₃N−]_<i>n</i> nanotube in the large voids. By contrast, crystal <b>10</b> possesses an organic 3-D supramolecular network formed by intricate C–H···π, π···π, and sulfonyl involved C/N–H···O interactions which encapsulates 1-D “centipede-shaped” [−SO₃···H₃N−]_<i>n</i> chains in the large voids. Luminescent investigations demonstrate that the salts containing aliphatic diamines exhibit stronger emission intensity than those containing aromatic diamines. This result indicates that the H₂NDS might be used to distinguish the aliphatic diamine from aromatic diamine qualitatively through the luminescent signal

Mechanically and Electrically Enhanced CNT–Collagen Hydrogels As Potential Scaffolds for Engineered Cardiac Constructs

With the development of biomimetic scaffolds for engineered cardiac constructs, a considerable number of biomaterials has been evaluated. However, in most previously reported cardiac constructs, the function of the cardiomyocytes (CMs) is restricted because of mismatches in the mechanics, conductivity, and submicrometer structure of the matrix. In this work, type I collagen hydrogels were combined with carbon nanotubes (CNTs) to assess potential improvements in hydrogel strength and conductivity and potential effects on the hydrogel structure. CMs seeded within the CNT–collagen hybrid hydrogels showed improved cardiac cell functions compared to those within pure collagen hydrogels, which suggested great promise of CNT–collagen hydrogels as functional scaffold materials for cardiac construct engineering

Equivalent Reactor Network Model for the Modeling of Fluid Catalytic Cracking Riser Reactor

Modeling description of riser reactors is a highly interesting issue in design and development of fluid catalytic cracking (FCC) processes. However, one of the challenging problems in the modeling of FCC riser reactors is that sophisticated flow-reaction models with high accuracy require time-consuming computation, while simple flow-reaction models with fast computation result in low-accuracy predictions. This dilemma requires new types of coupled flow-reaction models, which should own time-efficient computation and acceptable model accuracy. In this investigation, an Equivalent Reactor Network (ERN) model was developed for a pilot FCC riser reactor. The construction procedure of the ERN model contains two main steps: hydrodynamic simulations under reactive condition and determination of the equivalent reactor network structure. Numerical results demonstrate that with the ERN model the predicted averaged error of the product yields at the riser outlet is 4.69% and the computation time is ∼5 s. Contrast to the ERN model, the predicted error with the plug-flow model is almost three times larger (12.79%), and the computational time of the CFD model is 0.1 million times longer (6.7 days). The superiority of the novel ERN model can be ascribed to its reasonably simplifying transport process and avoiding calculation divergences in most CFD models, as well as taking the back-mixing behavior in the riser into consideration where the plug-flow model does not do so. In summary, the findings indicate the capabilities of the ERN model in modeling description of FCC riser reactors and the possibilities of the model being applied to studies on the dynamic simulation, optimization, and control of FCC units in the future

Lagrange stress versus stretch in the plane of symmetry for loading velocity of 10 mms-1 (strain rate 2s-1), 100 mms-1 (strain rate 20s-1), and 500 mms-1 (strain rate100s-1).

<p>Lagrange stress versus stretch in the plane of symmetry for loading velocity of 10 mms-1 (strain rate 2s-1), 100 mms-1 (strain rate 20s-1), and 500 mms-1 (strain rate100s-1).</p

A Co-Crystal Strategy to Tune the Supramolecular Patterns and Luminescent Properties: Ten Well-Designed Salts Assembled by Arenedisulfonic Acid with Diverse Diamines

Ten salts assembled by arenedisulfonic acid with hydrazine, flexible aliphatic diamines, rigid and semirigid aromatic diamines, namely, (H₂HA)²⁺·(NDS)^2– (<b>1</b>), (H₂EDA)²⁺·(NDS)^2– (<b>2</b>), (H₂PDA)²⁺·(NDS)^2– (<b>3</b>), (H₂BTDA)²⁺·(NDS)^2– (<b>4</b>), (H₂BDMA)²⁺·(NDS)^2–·2H₂O (<b>5</b>), 2­(<i>o</i>-HBDA)⁺·(NDS)^2– (<b>6</b>), (<i>m</i>-H₂BDA)²⁺·(NDS)^2– (<b>7</b>), (H₂MBDA)²⁺·(NDS)^2–·3H₂O (<b>8</b>), (H₂SDA)²⁺·(NDS)^2–·H₂O (<b>9</b>), and 2­(HSDA)⁺·(NDS)^2–·H₂O (<b>10</b>) (H₂NDS = 1,5-naphthalenedisulfonic acid, HA = hydrazine, EDA = 1,2-ethanediamine, PDA = 1,3-propanediamine, BTDA = 1,4-butanediamine, BDMA = 1,3-benzenedimethanamine, <i>o</i>-BDA = 1,2-benzenediamine, <i>m</i>-BDA = 1,3-benzenediamine, MBDA = 4-methyl-1,3-benzenediamine, SDA = 4,4′-sulfonyldiamiline), have been constructed and characterized by elemental analysis, infrared, thermogravimetric analysis, phospholuminescence, and powder and single-crystal X-ray diffraction. Structural analyses indicate that the nature of the diamines can effectively influence the final structures of the salts through diverse noncovalent bonding interactions, such as hydrogen bonds, π···π stacking, N–H···π, C–H···π, and lone pair···π interactions, which result in six types of architectures. Crystals <b>1</b>–<b>3</b> exhibit a three-dimensional (3-D) pillared layered supramolecular network with the diammonium cations being sandwiched among the sulfonate groups, while crystal <b>4</b> exhibits a 3-D “honeycomb” network with the −(CH₂)₄– groups being encapsulated among the NDS^2– anions. In comparison with crystal <b>4</b>, crystals <b>5</b>, <b>7</b>, and <b>8</b> exhibit a different 3-D supramolecular network, in which the phenylene, phenyl, and methylphenyl groups interpenetrate with the naphthyl rings of NDS^2– anions through continuous π···π interactions. Crystal <b>6</b> is two-dimensional pillared layered network with the <i>o</i>-HBDA⁺ cations arranging along the two sides of the layer. Crystal <b>9</b> possesses an organic 3-D supramolecular network formed by the C–H···π and sulfonyl involved lone pair···π interactions which encapsulates a one-dimensional (1-D) infinite [−SO₃···H₃N−]_<i>n</i> nanotube in the large voids. By contrast, crystal <b>10</b> possesses an organic 3-D supramolecular network formed by intricate C–H···π, π···π, and sulfonyl involved C/N–H···O interactions which encapsulates 1-D “centipede-shaped” [−SO₃···H₃N−]_<i>n</i> chains in the large voids. Luminescent investigations demonstrate that the salts containing aliphatic diamines exhibit stronger emission intensity than those containing aromatic diamines. This result indicates that the H₂NDS might be used to distinguish the aliphatic diamine from aromatic diamine qualitatively through the luminescent signal