Heat capacities and standard entropies and enthalpies of some compounds essential for steelmaking and refractory design approximated by Debye-Einstein integrals

Heat capacity data for compounds located in the binary CaO–SiO₂, CaO–Al₂O₃ and MgO–Al₂O₃ systems are fitted by Debye-Einstein integrals. Starting from the fitted heat capacities, the standard values of the thermodynamic functions of these compounds are calculated. In almost all cases investigated, the derived standard entropies are within the uncertainties of the values provided in literature. The Debye-Einstein coefficients obtained in this thermodynamic assessment can be used to approximate the heat capacities, enthalpies and entropies of these compounds in the temperature range from 0 to 298.15 K.     

Gas-assisted exfoliation of boron nitride nanosheets enhancing adsorption performance

A gas exfoliation strategy for controllable preparation of boron nitride (BN) nanosheets with few-layered structure were reported. The green exfoliation process provides the BN nanosheets remarkable increment of adsorption capacities to organic contaminants, which is ascribed to better exposure of active sites originating from the larger surface area and thinner layer. Moreover, the prepared BN also exhibits outstanding recyclability.     

Super-tough poly(butylene terephthalate) based blends by modification with core-shell structured polyacrylic nanoparticles

Core-shell structured polyacrylic nanoparticles (named CSPN) impact modifiers consisting of a rubbery poly(n-butyl acrylate) core and a rigid poly(methyl methacrylate) shell with a size of about 352 nm were synthesized by seed emulsion polymerization. The CSPN modifier with core-shell weight ratio 80/20 was used to toughen poly(butylene terephthalate) (PBT) by melt blending. With an increase in CSPN content, the impact strength and the elongation at break of PBT/CSPN blends increased significantly compared with those of PBT; however, the tensile strength decreased. It was found that the polymerization had a very high instantaneous conversion (> 93%) and overall conversion (99%). The core-shell structure of CSPN was examined by means of transmission electron microscope. Scanning electron microscope was used to observe the morphology of CSPN particle and fractured surfaces of the blends. The dynamic mechanical analyses of PBT/CSPN blends showed two merged transition peaks of PBT matrix, with the presence of CSPN modifier, which was responsible for the improvement of PBT toughness. The results indicated that the notched impact strength of PBT/CSPN blend with a weight ratio of 80/20 was 8.61 times greater than that of pure PBT where the brittle-ductile transition point appeared.     

Activating Single-Atom Ni Site via First-Shell Si Modulation Boosts Oxygen Reduction Reaction

Atomically dispersed nitrogen-coordinated 3d transition-metal site on carbon support (M-NC) are promising alternatives to Pt group metal-based catalysts toward oxygen reduction reaction (ORR). However, despite the excellent activities of most of M-NC catalysts, such as Fe-NC, Co-NC et al., their durability is far from satisfactory due to Fenton reaction. Herein, this work reports a novel Si-doped Ni-NC catalyst (Ni-SiNC) that possesses high activity and excellent stability. X-ray absorption fine structure and aberration-corrected transmission electron microscopy uncover that the single-atom Ni site is coordinated with one Si atom and three N atoms, constructing Ni-Si₁N₃ moiety. The Ni-SiNC catalyst exhibits a half-wave potential (E_1/2) of 0.866 V versus RHE, with a distinguished long-term durability in alkaline media of only 10 mV negative shift in E_1/2 after 35 000 cycles, which is also validated in Zn-air battery. Density functional theory calculations reveal that the Ni-Si₁N₃ moiety facilitates ORR kinetics through optimizing the adsorption of intermediates.     

High-sensitivity crack-based flexible strain sensor with dual hydrogen bond-assisted structure for monitoring tiny human motions and writing behavior

Owing to their ultrahigh sensitivity, crack-based flexible strain sensors have garnered considerable attention in recent years. In this study, a practical, and reliable chemical bonding-based dip-coating method is proposed to fabricate high sensitivity and high stability crack-based flexible strain sensor with dual hydrogen bond-assisted structure. The strain sensor has a sandwich structure, which is composed of graphene nanoplatelets (GNPs)/poly (sodium-p-styrenesulfonate) (PSS) conductive layer, ultra-violet (UV) adhesive substrate layer, and UV adhesive covering layer. The fabrication process, principle of dual hydrogen bond-assisted structure, strain sensing mechanism, and various properties of the proposed sensor are examined. It is demonstrated that the cracks and the dual hydrogen bond-assisted structure facilitate a practical strain sensor with high sensitivity (gauge factor of 19.65 in the strain range of 0–30%), long-term stability (over 10,000 cycles), good linearity, negligible drift, fast response time (~50 ms), and low detection limit (0.10%). Meanwhile, the proposed crack-based flexible strain sensor can be used as a wearable device, which can be directly mounted on human skin to monitor tiny human motions and writing behavior. Consequently, it exhibits immense potential for wearable applications including artificial skin, human-machine interfaces, and medical healthcare.     

Photothermal Modulation of Depression-Related Ion Channel Function through Conjugated Polymer Nanoparticles

Considering recent breakthroughs in the field of optogenetics, a powerful tool is established in the present study to modulate the activities of target neurons through the application of light-based methods. Near-infrared (NIR) light enables the penetration of deep-tissue. As a result, it can be used to modulate the functions of proteins/cells. Herein, it is aimed to develop a NIR light-sensitive drug delivery system to spatially and temporally control the activation of the loaded drug at the stimulation sites through its release from a nanoparticle sensitive to NIR. Owing to their excellent photothermal effect under NIR irradiation, the nanoparticles are found to penetrate the blood-brain barrier effectively, ultimately reaching neurons. Furthermore, by loading fasudil, a selective activator of the Kv7.4 potassium channel, into the precisely designed and synthesized NIR light-sensitive nanoparticles, the firing frequency of dopaminergic neurons in the ventral tegmental area is found to be remarkably reduced upon NIR light irradiation. Such findings shed light on a new concept that can be used for developing more selective drug therapies for the treatment of diseases, such as major depression.     

Stable Zinc Metal Anodes with Textured Crystal Faces and Functional Zinc Compound Coatings

The uneven electrodeposition and inferior corrosion resistance are the fundamental obstacles to achieve stable Zn metal anodes. The features of the electrode surface/interface are closely correlated with the properties. Herein, the Zn surface with more exposed (002)_Zn planes is modified through a simple acid-etching approach. The in situ generated zinc compounds form an interface layer with strong adhesion to the Zn electrode, which can enhance the Zn²⁺ ion kinetics and regulate the deposition/dissolution behaviors. A variety of acids with functional cations are selected, among which the phosphoric acid etches the Zn with a higher extent of texturing and generates a more compact layer. The obtained zinc phosphate@Zn electrode enables stable cycling and fast kinetics in symmetrical and full Zn metal batteries. This study provides a new example of combined surface and interface modification toward high-performance aqueous zinc metal anodes.     

Reduction of N2O by NH3 on polycrystalline copper and Cu(1 1 0): A combined XPS,FT-IRRAS and kinetics investigation

Kinetics of N₂O decomposition and catalytic reduction of N₂O by NH₃ in the presence or absence of oxygen have been studied on polycrystalline Cu planar chip (3 cm × 3 cm × 0.1 cm) or Cu(1 1 0) single crystal, using catalytic test equipment, XPS and FT-IRRAS techniques. It has been shown that N₂O decomposes on metallic Cu, but gives then Cu₂O, which is detrimental to N₂O decomposition. The presence of a reductant, such as NH₃, allowed N₂O to react leading to its catalytic reduction to N₂; 500 °C is the best temperature for catalytic reduction alone, i.e. with low additional self-decomposition of N₂O or NH₃. The presence of oxygen, in amount less than that of NH₃, leads to more efficient NH₃ oxidation, oxygen being observed to be more reactive than N₂O on NH₃. XPS results enabled to identify the active surface as metallic Cu and Cu₃N for NH₃ oxidation and NH₂, NH, N adsorbed species as intermediates of the reaction. At room temperature, in the presence of N₂O, O₂ and NH₃, FT-IRRAS allowed to show the formation of NH₂ and NH species (bands at 1550 and 1440 cm⁻¹, respectively) and of two N₂^δ− species (bands at 2170 and 2204 cm⁻¹), the latter one corresponding to adsorbed N₂^δ− species close to adsorbed electron accepting O or OH species. This study demonstrated that N₂O decomposed to N₂ and O species during SCR reaction; it enabled to identify several adsorbed surface species (N, NH, NH₂, N₂^δ−), both by XPS after catalytic reaction at 500 °C on the polycrystalline Cu chip and by IRRAS on Cu(1 1 0) single crystal in the presence of the reactants at room temperature. In addition, it was shown that N₂ is a powerful IR probe to characterise the surrounding environment of surface sites that cannot be identified by any other way.     

Dye encapsulated in porous boron nitride microfibers: A non-rare-earth red-emitting phosphor with high efficiency

We report the synthesis of a novel kind of non-rare earth (RE) red-emitting phosphor via incorporation of rhodamine (RhB) into porous boron nitride (BN) microfibers to form RhB@BN composite. The RhB@BN composite with typical one-dimensional (1D) fibrous morphology exhibits intense visible red-light emission, which can be attributed to the reduced dye aggregation via the confinement of RhB within porous BN, as well as the efficient energy transfer from BN host to RhB dyes. Moreover, the quantum efficiency of RhB@BN composite annealed after 150 °C treatment is as high as 86.94%. The strong interaction between RhB dyes and BN host plays an important role for maintaining the good thermal stability of the composite. The developed low-cost and environmentally friendly RhB@BN composite is envisaged to be highly valuable red-emitting phosphor.