Correlations of Surface Free Energy and Solubility Parameter with Dielectric Constant and Density for Inorganic Solids

There should be some intrinsic correlations between the surface free energy (γ) and solubility (δ) parameters, called characteristic parameters here, of substances with their basic physical properties such as the relative dielectric constant (εr) and density (ρ), because they are all related to intermolecular interactions. Several correlations have been proposed empirically (or semiempirically) for liquids, but not for solids. It is essential to establish such correlations for solids because the estimation of γ and δ for solids is difficult and/or time-consuming. In the current work, the γ, δ, εr, and ρ data of 34 inorganic solids were chosen, and possible relationships between the characteristic parameters (γ and δ) and the physical quantities (εr and ρ) were explored by a trial-and-error fitting method based on the data of the solids. Six equations relating γ and δ to εr and δ were established. The γ parameters include total (γt), dispersive (γd), and polar (γp) ones, and the δ parameters include the Hildebrand parameter (δt) and the Hansen-dispersive (δd), polar (δp), and hydrogen-bonding (δh) ones. The empirical equations can be used to estimate the characteristic parameters of inorganic solids from their easily measurable physical quantities

Asymmetric Supercapacitors Assembled by Dual Spinel Ferrites@Graphene Nanocomposites as Electrodes

Spinel-type ferrites are potential active materials for their highly theoretical capacity as electrodes of supercapacitors. Here, CoFe₂O₄@graphene nanocomposites were synthesized by a facile hydrothermal method and worked as cathode material. It was found that the performance of the electrode depended on the weight ratio of ferrites to graphene. The specific capacitance could be significantly increased to 579 F g^–1 at 1 A g^–1 when the content of graphene was 40% in the composite. Next an asymmetric supercapacitor (ASC) was fabricated by using the as-prepared Fe₃O₄@graphene nanocomposites as anode material. The ASC with 1.7 V working voltage delivered a high specific capacitance of 114.0 F g^–1 and a promising energy density of 45.5 Wh kg^–1 at a power density of 840 W kg^–1, along with a highly cycling stability of 91% capacitance retention after 5000 cycles. It provided a new change to fabricate high performance ASCs using spinel ferrite-based graphene nanocomposites as electrodes

Disentangled higher-orbital bands and chiral symmetric topology in confined Mie resonance photonic crystals

Topological phases based on tight-binding models have been extensively studied in recent decades. By mimicking the linear combination of atomic orbitals in tight-binding models based on the evanescent couplings between resonators in classical waves, numerous experimental demonstrations of topological phases have been successfully conducted. However, in dielectric photonic crystals, the Mie resonances' states decay too slowly as $1/r$ when $r$ $\to$ $\infty$, leading to intrinsically different physical properties between tight-binding models and dielectric photonic crystals. Here, we propose a confined Mie resonance photonic crystal by embedding perfect electric conductors in between dielectric rods, leading to a perfectly matched band structure as the tight-binding models with nearest-neighbour couplings. As a consequence, disentangled band structure spanned by higher atomic orbitals is observed. Moreover, we also achieve a three-dimensional photonic crystal with a complete photonic bandgap and third-order topology based on our design. Our implementation provides a versatile platform for studying exotic higher-orbital bands and achieving tight-binding-like 3D topological photonic crystals

Electroactivated Modulation of Highly Aligned Manganese-Doped Cobalt Sulfide Nanoplate Arrays for High-Performance Hybrid Supercapacitors

Transition-metal sulfides have been identified as one of the promising cathode materials of battery type for hybrid supercapacitors (HSCs). However, there are still huge obstacles to their practical applications due to the major problems of poor structural stability and limited redox active sites. In this work, a high-performance cathode material based on three-dimensional porous Mn-doped Co9S8 nanoplate arrays (Mn-Co9S8 NPAs) on Ni foam has been synthesized via a facile electroactivation-modified metal–organic framework self-templating sulfurization strategy. It has been found that the introduction of Mn2+ ions can guarantee the structural integrity of the nanoplate arrays and effectively reduce the electron density near Co sites. By the synergistic modulation of the geometric and electronic structures, the Mn-Co9S8 NPAs electrode delivers an ultrahigh capacity of 569.4 mAh g–1 (4099.7 F g–1) at 1 A g–1 with superior cycling stability. An HSC assembled with the electrode materials exhibits a high energy density of 73.1 Wh kg–1 at a power density of 737.5 W kg–1 and yields a 98.2% capacitance retention after 5000 cycles, indicating robust cycling stability as well. This work demonstrates a doping engineering strategy to regulate the physicochemical properties of metal sulfides for efficient energy-storage and conversion applications

Vibrational Mode Assignment of α‑Pinene by Isotope Editing: One Down, Seventy-One To Go

This study aims to reliably assign the vibrational sum frequency generation (SFG) spectrum of α-pinene at the vapor/solid interface using a method involving deuteration of various methyl groups. The synthesis of five deuterated isotopologues of α-pinene is presented to determine the impact that removing contributions from methyl group C–H oscillators has on its SFG response. 0.6 cm^–1 resolution SFG spectra of these isotopologues show varying degrees of differences in the C–H stretching region when compared to the SFG response of unlabeled α-pinene. The largest spectral changes were observed for the isotopologue containing a fully deuterated vinyl methyl group. Noticeable losses in signal intensities allow us to reliably assign the 2860 cm^–1 peak to the vinyl methyl symmetric stretch. Furthermore, upon removing the vinyl methyl group entirely by synthesizing apopinene, the steric influence of the unlabeled C₉H₁₄ fragment on the SFG response of α-pinene SFG can be readily observed. The work presented here brings us one step closer to understanding the vibrational spectroscopy of α-pinene

Fabrication of Modularly Functionalizable Microcapsules Using Protein-Based Technologies

Proteins are desirable building blocks to create self-assembled, spatially defined structures and interfaces on length-scales that are inaccessible by traditional methods. Here, we describe a novel approach to create functionalized monolayers using the proteins BslA and SpyCatcher/SpyTag. BslA is a bacterial hydrophobin whose amphiphilic character underlies its ability to assemble into a monolayer at both air/water and oil/water interfaces. We demonstrate that Bsa1A having the SpyTag peptide fused at the N- or C-terminus does not affect the formation of such monolayers. We establish the creation of stable oil-in-water microcapsules using BslA, and also show the fabrication of capsules outwardly displaying the reactive SpyTag peptide by fusing it to the C-terminus of BslA. Such capsules can be covalently labeled by reacting the surface-displayed SpyTag with SpyCatcher fused to any desired protein. We demonstrate this principle by labeling microcapsules using green fluorescent protein (GFP). All components are genetically encodable, the reagents can be readily prepared in large quantities, and all reactions occur at ambient temperature in aqueous solution. Thus, this straightforward, modular, scalable strategy has myriad potential applications in the creation of novel, functional materials, and interfaces

Direct Probes of 4 nm Diameter Gold Nanoparticles Interacting with Supported Lipid Bilayers

This work presents molecular-level investigations of how well-characterized silica-supported phospholipid bilayers formed from either pure DOPC or a 9:1 mixture of DOPC:DOTAP interact with positively and negatively charged 4 nm gold metal nanoparticles at pH 7.4 and NaCl concentrations ranging from 0.001 to 0.1 M. Second harmonic generation (SHG) charge screening measurements indicate the supported bilayers carry a negative interfacial potential. Resonantly enhanced SHG measurements probing electronic transitions within the gold core of the nanoparticles show the particles interact irreversibly with the supported bilayers at a range of concentrations. At 0.1 M NaCl, surface coverages for the particles functionalized with the negatively charged ligand mercaptopropionic acid (MPA) or wrapped in the cationic polyelectrolyte poly­(allylamine) hydrochloride (PAH) are estimated from a joint analysis of QCM-D, XPS, AFM, and ToF-SIMS to be roughly 1 × 10⁷ and 1 × 10¹¹ particles cm^–2, respectively. Results from complementary SHG charge screening experiments point to the possibility that the surface coverage of the MPA-coated particles is more limited by interparticle Coulomb repulsion due to the charges within their hydrodynamic volumes than with the PAH-wrapped particles. Yet, SHG adsorption isotherms indicate that the interaction strength per particle is independent of ionic strength and particle coating, highlighting the importance of multivalent interactions. ¹H NMR spectra of the lipids within vesicles suspended in solution show little change upon interaction with either particle type but indicate loosening of the gold-bound PAH polymer wrapping upon attachment to the vesicles. The thermodynamic, spectroscopic, and electrostatic data presented here may serve to benchmark experimental and computational studies of nanoparticle attachment processes at the nano–bio interface