Robust Heterojunctions of Metallic Alloy and Carbon Fiber-Reinforced Composite Induced by Laser Processing

The development of heterojunctions with a strong bonding interface between metals and non-metals has attracted much attention owing to their great potential for use in lightweight structures. Laser joining technology, which emerged as a fast and reliable method, has proven its feasibility and unique advantages in joining metal to polymer matrix composites. Herein, an optimized laser joining configuration has been employed to realize high-quality joining of titanium alloy and carbon fiber-reinforced composite. Cross-sectional microstructures of laser-produced joints reveal that micro-bubbles near the interface have been effectively suppressed and eliminated due to the continual clamping pressure applied to the joined area during the joining process. Tensile tests suggest that the joint strength increases with structure density on a titanium alloy surface, and the greatest fracture strength of joints reaches more than 60 MPa even after experiencing a high–low temperature alternating aging test. For higher structure density (>95%), the joints fail by the fracture of parent plastics near the joined area due to the tensile-loading-induced peel stress at the edges of the overlap region. Otherwise, the joints fail by interfacial shear fracture with breakage when the structure density is lower than 91.5%. The obtained high-performance heterojunctions show great potential in the aerospace and automotive fields.

Gas molecules (CH4, CO, H2O and H2S) adsorption on VC (001)surface: a first principles study

The first principle plane wave pseudo-potential method based on density functional theory system is used to calculate and simulate the geometric structure, density of states and optical properties of intrinsic VC materials. And we further studied the adsorption performance of small gas molecules (CH4, CO, H2O, H2S) on the surface of VC(001). The most stable adsorption geometry of CH4, CO, H2O and H2S on the intrinsic VC(001) was determined, and the electronic structure and differential charge were calculated by the first principle method. The results show that the adsorption stability of the same molecule on the surface is related to the interaction position between the molecule and the surface after adsorption. According to the analysis of the differential charge density and the charge layout number, the charge layout number of the central atom C, O, S of the gas molecule increases after adsorption, and the adsorption strength of the gas molecule on the surface is CO>H2S>H2O>CH4. The H2S adsorbed on VC surface has the strongest adsorption energy (-1.442 eV) and more transfer charge (-0.12 e). The calculated dielectric function results shows that the existence of gases molecules inhibited the photon adsorbed on VC(001) surface. Our research provide a theoretical basis for further research on the gas sensing properties of material.

Physical Properties Investigations of Ternary-Layered Carbides M2PbC (M = Ti, Zr and Hf): First-Principles Calculations

We investigated structure optimization, mechanical stability, electronic and bonding properties of the nanolaminate compounds Ti2PbC, Zr2PbC, and Hf2PbC using the first-principles calculations. These structures display nanolaminated edifices where MC layers are interleaved with Pb. The calculation of formation energies, elastic moduli and phonons reveal that all MAX phase systems are exothermic, and are intrinsically and dynamically stable at zero and under pressure. The mechanical and thermal properties are reported with fundamental insights. Results of bulk modulus and shear modulus show that the investigated compounds display a remarkable hardness. The elastic constants C11 and C33 rise more quickly with an increase in pressure than that of other elastic constants. Electronic and bonding properties are investigated through the calculation of electronic band structure, density of states, and charge densities.

A general strategy for preparing pyrrolic-N4 type single-atom catalysts via pre-located isolated atoms

Single-atom catalysts (SACs) have been applied in many fields due to their superior catalytic performance. Because of the unique properties of the single-atom-site, using the single atoms as catalysts to synthesize SACs is promising. In this work, we have successfully achieved Co1 SAC using Pt1 atoms as catalysts. More importantly, this synthesis strategy can be extended to achieve Fe and Ni SACs as well. X-ray absorption spectroscopy (XAS) results demonstrate that the achieved Fe, Co, and Ni SACs are in a M1-pyrrolic N4 (M= Fe, Co, and Ni) structure. Density functional theory (DFT) studies show that the Co(Cp)2 dissociation is enhanced by Pt1 atoms, thus leading to the formation of Co1 atoms instead of nanoparticles. These SACs are also evaluated under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and the nature of active sites under HER are unveiled by the operando XAS studies. These new findings extend the application fields of SACs to catalytic fabrication methodology, which is promising for the rational design of advanced SACs.

Timber Properties and Cellulose Crystallites Size in Pine Wood Cut in Different Sawing Patterns after Pretreatment with CH3COOH and H2O2 and Densification

One process to improve wood quality is densification or wood surface compression. Our study analyzed the changes in some basic properties of pine wood, including its anatomical structure, density, modulus of elasticity (MOE), and dimensions of cellulose crystallites, after densification following soaking pretreatment in CH3COOH and H2O2 at a concentration of 20%. Samples were sawn in radial and tangential directions for analysis of the wood. The results showed a change in the shape of tracheid cells from hexagonal to oval, as well as damage to the ray cell constituents on the tangential surface. The thickness decrease of the samples was in accordance with the target, which meant that spring-back was short. In general, the tangential boards had a higher density than the radial boards, with a lower MOE and crystallite dimensions. Our findings showed that the densified tangential board was stronger than the radial board.

First-principles calculations of electronic and optical properties in the bulk and on the (001) surface of CsPbCl3

We perform density functional theory using first-principles calculations in order to investigate the band structure, density of states, the real and imaginary part of dielectric function, refractive index and optical absorption of CsPbCl3 in the bulk and (001) surface structure. Energy bands exhibits wide and direct bandgap. When CsPbCl3 is extended to (001) surface a decrease of band gap is observed with increasing thickness. The optical constants observed exhibits optimal properties in the ultraviolet and visible range indicating its usefulness in photonic, optoelectronic, photovoltaic and optomagnetic devices.

Instrumental support exchanges among kin and non-kin in light of personal configurations

As exchanges of instrumental support between kin and non-kin remain essential to buffer the impact of critical life events, we consider the characteristics of personal configurations that may enhance or hinder them. Personal configurations vary in terms of their composition and two aspects of their structure: density and centrality. These dimensions are investigated to uncover whether they influence the type of instrumental support being exchanged (financial, material, and care) and the likelihood of their being reciprocal. Drawing on a representative sample of individuals living in Switzerland, results show that overall instrumental support is present in all personal configurations irrespective of their composition, but financial support is more prevalent in configurations based on parent–adult child relationships. Furthermore, configuration structures characterized by density of emotional support are positively associated with giving care support and with reciprocity, while those characterized by density of conflict are associated with giving less instrumental support overall.

Population structure of Lingula (Bruguière, 1791) in Alue Naga waters, Banda Aceh City, Indonesia

Lingula sp. is one of the genera of the Brachiopoda phylum that lives in the intertidal zone or areas that are affected by tides. The purpose of this study was to determine the population structure of Lingula sp. through the approach of population structure, density, distribution patterns, length and weight relationship and with physical and chemical parameters in the waters of Alue Naga, Syiah Kuala District, Banda Aceh City. The method used in this research is a purposive random sampling method. The results show that the growth pattern of Lingula sp. is classified as negative allometric at three research sites in Alue Naga waters, based on the value of b 3. The density of Lingula sp. was the highest at site 1 with a total of 17.7 ind/m2. While the density of Lingula sp. was the lowest at site 3 with a total of 9.7 ind/m2. The distribution of Lingula sp. at the three sites were uniform, with morisita index (Id) values of 0.352, 0.257, and 0.208 for sites 1, 2, and 3 respectively. In addition, the environmental factors of the three research sites in Alue Naga waters are within the normal limits of life for Lingula sp.Keywords: Alue NagaLingula sp. Population structure

Effect of substitution on the superconducting phase of transition metal dichalcogenide Nb(Se$$_{x}$$S$$_{1-x}$$)$$_{2}$$ van der Waals layered structure

By means of first-principles cluster expansion, anisotropic superconductivity in the transition metal dichalcogenide Nb(Se$$_{x}$$ x S$$_{1-x}$$ 1 - x )$$_{2}$$ 2 forming a van der Waals (vdW) layered structure is observed theoretically. We show that the Nb(Se$$_{0.5}$$ 0.5 S$$_{0.5}$$ 0.5 )$$_{2}$$ 2 vdW-layered structure exhibits minimum ground-state energy. The Pnnm structure is more thermodynamically stable when compared to the 2H–NbSe$$_{2}$$ 2 and 2H–NbS$$_{2}$$ 2 structures. The characteristics of its phonon dispersions confirm its dynamical stability. According to electronic properties, i.e., electronic band structure, density of states, and Fermi surface indicate metallicity of Nb(Se$$_{0.5}$$ 0.5 S$$_{0.5}$$ 0.5 )$$_{2}$$ 2 . The corresponding superconductivity is then investigated through the Eliashberg spectral function, which gives rise to a superconducting transition temperature of 14.5 K. This proposes a remarkable improvement of superconductivity in this transition metal dichalcogenide.

Creeping disaster along the U.S. coastline: Understanding exposure to sea level rise and hurri-canes through historical development

Current estimates of U.S. property at risk of coastal hazards and sea level rise (SLR) are stag-gering, evaluated at over a trillion U.S. dollars. Despite being enormous in the aggregate, po-tential losses due to SLR depend on mitigation, adaptation, and exposure and are highly uneven in their distribution across coastal cities. We provide the first analysis of how changes in expo-sure (how and when) have unfolded over more than a century of coastal urban development in the United States. We do so by leveraging new historical settlement layers from the Historical Settlement Data Compilation for the U.S. (HISDAC-US) to examine building patterns within and between the SLR zones of the conterminous United States since the early twentieth century. Our analysis reveals that SLR zones developed faster and continue to have higher structure density than non-coastal, urban and inland areas, patterns which are particularly prominent in locations affected by hurricanes. However, density levels in historically less-developed coastal areas are now quickly converging on early-settled SLR zones, many of which have reached building saturation. These “saturation effects” suggest that adaptation polices targeting existing buildings and developed areas are likely to grow in importance relative to the protection of previously undeveloped land.