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The microstructure details of the interface, mechanical properties and failure mechanism of laser welding-brazing (LWB) steel-Al joints with various welding parameters were comparatively investigated. The emergence of ternary Fe–Al–Si intermetallic compounds (IMCs) was observed in the interfacial area of the joints prepared utilizing ER4047 filler. In contrast, only the binary Fe–Al IMCs were formed in the interfacial area of the joints prepared employing ER5356 filler. With the same laser tilt angle, the IMCs layer of the joints prepared with ER4047 was thinner than that of the joints prepared with ER5356, implying the rapid growth of the IMCs welded via the ER5356 filler. The tensile strength exhibited by the former surpassed that of the latter. Employing the same filler metal, the average thickness of the IMCs layer of the joints with laser tilt angle of 10° was smaller than that of the joints with laser tilt angle of 20°. The strength of the joints with smaller tilt angle was better than that of the ones with bigger tilt angle. The tensile test outcomes revealed that there existed failure competition among the Al alloy base metal (Al-BM), weld metal (WM) and interface structure. If the interface structure was Fe–Al IMC with high brittleness, the cracks propagated along the interface, and finally fractured at the interface. If the interface structure was Fe–Al–Si IMC with good toughness, the crack propagation in the interface region could be hampered. In this case, the joint was prone to occur via WM failure or even Al-BM failure modes.

Fabricating ultra-long straight-chain C49H100alkane using a modular splicing strategy.

As a challenge to avoid the strength-ductility trade-off for Ti alloys, strength and ductility are contradictory, especially at a high content of primary α phase. This study proposed a new strategy to evade this trade-off dilemma by designing an 81% primary α phase/ultrafine-grained (UFG) secondary α phase lamellar heterogeneous structure(LPSlow-HS) in near-α Ti alloys. Compared to the bimodal structure, the LPSlow-HS offers a remarkable increase in the ultimate tensile strength(1119 MPa) and yield strength(1069 MPa), respectively, while the elongation (15%) is not sacrificed. Owing to the strong heterogeneous deformation-induced(HDI) strengthening, more number of delamination of interfaces, UFG microstructures and strong strain hardening render the Ti alloys high strength. This strategy may provide a new approach for achieving higher HDI strengthening effects in heterogeneous structures (HS) under high soft phases, and offer a feasible method for producing high strength-ductility Ti alloys under high primary α phase.

Maltitol has been identified as an important value-added chemical with versatile applications and is typically manufactured via the catalytic hydrogenation of maltose, which is in urgent need of upgrading from batch to continuous operation to boost production efficiency. Here we propose a viable continuous approach for maltose hydrogenation in a trickle-bed reactor applying a millimeter-scale Raney Ni. The parametric study was performed at various temperatures, liquid flow rates, initial maltose concentrations, pressures, and hydrogen flow rates to maximize the catalytic performance and optimize the product distribution. Under the optimal reaction conditions, generally excellent conversion of maltose (91.0%) and a high yield of maltitol (87.9%) were obtained. Furthermore, a continuous hydrogenation of concentrated maltose proceeded properly, providing a slight reduction in maltose conversion but satisfactory space time yield of maltitol (0.150 gmaltitolgcat–1h–1). Detailed kinetics and density functional theory calculations were combined to unravel the reaction mechanism of maltose hydrogenation. The continuous flow system based on a trickle-bed reactor proved to have high durability and remarkable substrate suitability, thus demonstrating a reliable scale-up capability for the industrial utilization of biomass-derived sugars.

Metal-free carbon-based catalysts have received a lot of attention in electrochemical nitrogen reduction reaction (NRR), but their activity is still unsatisfactory. Designing advanced catalysts with highly defective structure is critical for improving the activity and selectivity toward NRR. We present a method for preparing homogeneous ternary boron carbon nitride (BCN) nanosheets using an organic–inorganic hybrid precursor pyrolysis. Raman spectra and electron paramagnetic resonance analysis reveal the abundant defective structure in the BCN catalyst. The homogeneous element distribution and abundant defective structure in BCN promote the formation of Lewis-acid sites (undercoordinated B sites) and Lewis-base sites (undercoordinated N sites) for N2activation. Benefiting from the structural advantages of BCN, the optimal catalyst exhibits a high faradaic efficiency of 27.2% at −0.29 V (vs RHE), an ammonia yield of 5.21 μg h–1mgcat–1at −0.49 V (vs RHE), and an excellent long-term durability, surpassing most previous reports.

This work aims to study the influence of laser power on the microstructural evolution of novel Ti–6Zr–5Fe alloy fabricated by selective laser melting (SLM). The microstructural evolutions of all top surfaces in SLM Ti–6Zr–5Fe alloy samples fabricated from 80 W to 140 W were investigated in depth. The microstructure in SLM Ti–6Zr–5Fe alloy includes α phase and β phase, the size of the β phase and α phase increases with the increase of laser power due to the decrease of cooling rate. Meanwhile, the melt pool overlapping width increases with the increase of melt pool width due to the increase of laser power. The increase of melt pool overlapping causes the re-heating or re-melting of SLM Ti–6Zr–5Fe alloy. Moreover, as the laser power increases from 80 W to 140 W, the change of the melt pool greatly influenced the size, morphology, crystallographic orientation of the β phase, and their distributions. The increase of laser power causes adequate precipitation of the α phase, which improves the microhardness from 466 HV to 533 HV. The laser power can effectively regulate and control the microstructure and microhardness of SLM Ti alloys.

Microstructural evolution and its effect on microhardness and Young's modulus of Ti–6Zr–4Fe alloy solution and aging treated at different temperatures were studied. The α phase transformed into β phase completely at 860 °C, meanwhile, the athermal ω phase was found at 860 °C and it resulted in a higher Young's modulus. The ω phase content increased from 250 °C to 400 °C, and the content decreased with further increase of aging temperature, there were only α phase and β phase at 600 °C. The phase transformation sequence was β → ω + β → ω + α + β → α + β during aging treatment. The microhardness increased from 315 HV to 492 HV due to the element solution strengthening and phase transformation strengthening. The peak microhardness of Ti–6Zr–4Fe alloy aged at 400 °C reached 652 HV. The formation of ω phase resulted in the increase of microhardness and Young's modulus in Ti–6Zr–4Fe alloy.

Hepatitis-hydropericardium syndrome (HHS) is a highly fatal disease in chickens caused by the highly pathogenic fowl adenovirus serotype 4 (FAdV-4), which has severe economic consequences. The fiber2 protein exhibits excellent potential as a candidate for a subunit vaccination against FAdV-4. Despite having a high safety profile, subunit vaccines have low immunogenicity due to their lack of infectivity, which leads to low levels of immune response. As a vaccine adjuvant, Salmonellaflagellin possesses the potential to augment the immunological response to vaccinations. Additionally, a crucial strategy for enhancing vaccine efficacy is efficient presentation of immune antigens to dendritic cells (DC) for targeted vaccination. In this study, we designed FAdV-4-fiber2 protein and a recombinant protein called FliBc-fiber2-SP which based on FAdV-4-fiber2 protein, was generated using the gene sequence FliBc, which retains only the conserved sequence at the amino and carboxyl termini of the flagellin B subunit, and a short peptide SPHLHTSSPWER (SP), which targets chicken bone marrow-derived DC. They were separately administered via intramuscular injection to 14-day-old specific pathogen-free (SPF) chickens, and their immunogenicity was compared. At 21 days post vaccination (dpv), it was found that the FliBc-fiber2-SP recombinant protein elicited significantly higher levels of IgG antibodies and conferred a vaccine protection rate of up to 100% compared to its counterpart fiber2 protein. These results suggest that the DC-targeted peptide fusion strategy for flagellin chimeric antigen construction can effectively enhance the immune protective efficacy of antigen proteins.

Abstract

Abstract

ZnWO4, as an environment-friendly and economic material, has the potential for Li ion batteries (LIB) application. In this paper, a facile method has been developed to synthesize ZnWO4supported on the reduced graphene oxide (RGO) to improve its LIB performance. The cuboid-like ZnWO4nanocrystals are prepared by directly adding Na2WO4powders into the graphene oxide/Zn aqueous solution followed by a hydrothermal treatment. The high-resolution TEM, XRD and XPS characterizations were employed to demonstrate structural information of the as-prepared ZnWO4/RGO hybrids carefully. Besides, we also discussed the LIB properties of the hybrids based on the detailed galvanostatic charge-discharge cycling tests. As a result, the specific capacity of the as-prepared ZnWO4/RGO hybrids reached more than 477.3 mA h g−1after 40 cycles at a current density of 100 mA g−1(only less than 159 mA g−1for bare ZnWO4). During the whole cyclic process, the coulombic efficiency steadily kept the values higher than 90%.