The spheroidization process of micron-scaled α-Al2O3 powder in hydrothermal method

Understanding the spheroidization process of micron-scaled α-Al₂O₃ powder in hydrothermal method is of great importance but still not completely revealed. The results demonstrated that SO₄^2? played a significant role in the formation of spherical powder, while the bubble generated from the reaction of urea didn't work in the spheroidization process. The spheroidization process was summed up as two steps. The first was that SO₄^2? limited the hydrolysis of Al³⁺ and reacted with Al³⁺ and OH^- to form Al₄(OH)₁₀SO₄, which nucleated and agglomerated into granular precipitates. The second was Ostwald ripening, which gave the spherical precursors a double-layered structure. When the spherical precursors obtained 120 °C were sintered at 1200 °C, α-Al₂O₃ were got and the spherical morphology still maintained with a large number of nano-sized pores. We anticipate the spherical α-Al₂O₃ with nano-sized pores can be applied in adsorption and filtration industries.     

Metallocene QACs: The Incorporation of Ferrocene Moieties into monoQAC and bisQAC Structures

Inspired by the incorporation of metallocene functionalities into a variety of bioactive structures, particularly antimicrobial peptides, we endeavored to broaden the structural variety of quaternary ammonium compounds (QACs) by the incorporation of the ferrocene moiety. Accordingly, 23 ferrocene-containing mono- and bisQACs were prepared in high yields and tested for activity against a variety of bacteria, including Gram-negative strains and a panel of clinically isolated MRSA strains. Ferrocene QACs were shown to be effective antiseptics with some displaying single-digit micromolar activity against all bacteria tested, demonstrating yet another step in the expansion of structural variety of antiseptic QACs.     

Synthesis of Hollow Three-Dimensional Channels LiNi_(0.5)Mn_(1.5)O_4 Microsphere by PEO Soft Template Assisted with Solvothermal Method

A appropriate size with three-dimension(3 D) channels for lithium diffusion plays an important role in constructing highperforming LiNi_(0.5)Mn_(1.5)O_4(LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li~+ intercalation/deintercalation. In this work, an e fficient method for designing the hollow LNMO microsphere with 3 D channels structure by using polyethylene oxide(PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3 D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g~(-1) at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3 D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion.     

Core–Shell Photoanodes for Photoelectrochemical Water Oxidation

Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising solution for the conversion and storage of solar energy. Because sluggish water oxidation is the bottleneck of water splitting, the design and preparation of an efficient photoanode is intensively investigated. Currently, all known photoanode materials suffer from at least one of the following drawbacks: ① low carriers separation efficiency; ② sluggish surface water oxidation reaction; ③ poor long-term stability; ④ insufficient water adsorption and gas desorption. Core–shell configurations can endow a photoanode with improved activity and stability by coating an overlayer that plays energetic, catalytic, and/or protective roles. The construction strategy has an important effect on the activity of a core–shell photoanode. Nonetheless, the mechanism for the improvement of performance is still ambiguous and is worthy of a closer examination. In this review, the successes and challenges of core–shell photoanodes for water oxidation, focusing on synthesis strategies as well as functionalities (facilitating carrier separation, surface reaction promotion, corrosion prevention, and bubble detachment) are explored. Finally, the perspectives of this class of materials in terms of new opportunities and efforts are discussed.     

Research advances in residual thermal stress of ceramic/metal brazes

Brazing, as a common method of bonding ceramic and metal, has been applied in microelectronics, aerospace, machinery and other domains extensively. The residual thermal stress in the brazed joint has direct effects on the mechanical properties of the joint, so how to control the generation of residual thermal stress has become the vital point. In this paper, the methods of reducing residual thermal stress in the brazing process in recent years are reviewed. The generation and effects of residual thermal stress in the brazed joint are introduced. Besides, the methods of detecting residual thermal stress are discussed, and different methods of reducing residual thermal stress in brazed joints are also analyzed. Finally, the future development directions of reducing residual thermal stress in the brazed joint are proposed.     

Preparation,structure and microwave dielectric properties of novel La2MgGeO6 ceramics with hexagonal structure and adjustment of its τf value

A novel La₂MgGeO₆ ceramic was synthesized through a solid-state reaction process within a sintering temperature range of 1450–1550 °C. By a combination of X-ray diffraction and Rietveld refinement analyses, the ceramics were found to have a pure hexagonal phase structure belonging to space group R3/146. The scanning electron microscopy images revealed that the ceramic grains were closely connected. The effects of internal (lattice energy, valence bond, and fraction packing) and external factors (density) on the microwave properties of ceramics were also studied. The ceramic exhibited excellent microwave dielectric performances, with a relative permittivity (?_r) of 21.2, a quality factor (Q × f) of 52 360 GHz, and a temperature coefficient of resonant frequency (τ_f) of ?44.2 ppm/°C, when sintered at 1500 °C for 4 h. The τ_f value of the La₂MgGeO₆ ceramic doped with CaTiO₃ could be adjusted to zero. Particularly, 0.2La₂MgGeO₆-0.8CaTiO₃ ceramics have good microwave dielectric properties with τ_f = +2.1 ppm/°C, Q × f = 15 610 GHz, and ?_r = 40.3.     

高熵形状记忆合金的研究进展

高熵形状记忆合金是在等原子比NiTi合金的基础上,结合高熵合金的概念,逐渐发展起来的一种新型高温形状记忆合金。近年来,已开发出了综合性能优异的(TiZrHf)50(NiCoCu)50系和(TiZrHf)50(NiCuPd)50系高熵形状记忆合金,引起了广泛的关注和研究兴趣。本文从物相组成、微观组织、马氏体相变行为、形状记忆效应和超弹性等角度出发,综述了高熵形状记忆合金的研究进展,并对高熵形状记忆合金未来的研究重点进行了展望。     

Bioinspired Triboelectric Soft Robot Driven by Mechanical Energy

A sustainable power source is a key technical challenge for practical applications of electrically responsive soft robots, especially the required voltage is over several thousand volts. Here, a practicable new technology, triboelectric soft robot (TESR) system with the primary characteristics of power source from mechanical energy, is developed. At its heart is TESR with bioinspired architectures made of soft-deformable body and two triboelectric adhesion feet, which is driven and accurately controlled through triboelectric effect, while reaching maximum crawling speeds of 14.9 mm s⁻¹ on the acrylic surface. The characteristics of the TESR, including displacement and force, are tested and simulated under the power of a rotary freestanding triboelectric nanogenerator (RF-TENG). Crawling of TESR is successfully realized on different materials surfaces and different angle slopes under the driven of RF-TENG. Furthermore, a real-time visual monitoring platform, in which TESR carries a micro camera to transmit images in a long narrow tunnel, is also achieved successfully, indicating that it can be used for fast diagnosis in an area inaccessible to human beings in the future. This study offers a new insight into the sustainable power source technologies suitable for electrically responsive soft robots and contributes to expanding the applicability of TENGs.     

TiO2/MXene-Assisted LDI-MS for Urine Metabolic Profiling in Urinary Disease

Cancer remains an intractable medical problem. Rapid diagnosis and identification of cancer are critical to differentiate it from nonmalignant diseases. High-throughput biofluid metabolic analysis has potential for cancer diagnosis. Nevertheless, the present metabolite analysis method does not meet the demand for high-throughput screening of diseases. Herein, a high-throughput, cost-effective, and noninvasive urine metabolic profiling method based on TiO₂/MXene-assisted laser desorption/ionization mass spectrometry (LDI-MS) is presented for the efficient screening of bladder cancer (BC) and nonmalignant urinary disease. Combined with machine learning, TiO₂/MXene-assisted LDI-MS enables high diagnostic accuracy (96.8%) for the classification of patient groups (including 47 BC and 46 ureteral calculus (UC) patients) from healthy controls (113 cases). In addition, BC patients can also be identified from noncancerous UC individuals with an accuracy of 88.3% in the independent test cohort. Furthermore, metabolite variations between BC and UC individuals are investigated based on relative quantification, and related pathways are also discussed. These results suggest that this method, based on urine metabolic patterns, provides a potential tool for rapidly distinguishing urinary diseases and it may pave the way for precision medicine.