A supersaturated Cu-Ag nanoalloy joint with ultrahigh shear strength and ultrafine nanoprecipitates for power electronic packaging

Ag-Cu bimetallic nanoalloy,integrating the advantages of reducing migration and cost of nano-Ag and alleviating oxidation of nano-Cu,is a prospective bonding material for power electronic packaging.The Ag-coated Cu nanoparticles(Cu@Ag NPs)paste can execute bonding with high quality at 250℃,and the achieved supersaturated Ag-Cu nanoalloy joint with ultrahigh shear strength(152 MPa)dramatically exceeds most nano-paste joints.The interstitial solid solutions with atomic-level metallurgical bonds at the interface dominantly promoted the shear strength.Besides,the numerous ultrafine nanograin,high proportion of low angle grain boundaries(7.44%)without deformation,and the Cu nanoprecipitates in the joint would improve subordinately.Furthermore,the high content(16.8%)of∑3 twin boundaries would contribute to the electrical and thermal conductivity.Thus,the multiple strengthening mechanisms with the solid solution,the second precipitated phase,and ultrafine nanograin can dramatically enhance shear strength and electro-thermal conductivity of joints for high-temperature device packaging.

天然腐植酸光热剂

腐植酸是天然有机碳源的主要组成部分,是微生物对动植物残体进行生物降解而自然形成的。由于腐植酸含有许多具有生理活性的组分(如酚类、羧酸类和醌类),因此,腐植酸的生物医学应用研究在不同文化背景下已历经了几个世纪甚至更长的时间。在本研究中,基于近红外区域的本征吸收,腐植酸钠(腐植酸的钠盐)被研究开发成一种光热剂,用于光诱导光声成像和光热治疗。纯化的腐植酸钠胶体具有高达76.3%的光热转换效率,远高于包括金纳米棒、Cu9S5纳米颗粒、锑烯量子点和黑磷量子点的大多数先进的光热剂,在体内外都有明显的光声增强作用。除此之外,对HeLa肿瘤的高效光热消融是通过瘤内注射实现的。令人惊喜的是,腐植酸钠在细胞和动物水平上显示出超低毒性。这项工作预示着腐植酸作为光介导治疗剂的巨大潜力,从而扩大了传统腐植酸在生物医学领域的应用范围。

Hybrid dual-channel phototransistor based on ID t-Se and 2D ReS2 mixed-dimensional heterostructures

The com bination of mixed-dimensional semiconducti ng materials can provide additional freedom to construct integrated n anoscale electronic and optoelectronic devices with diverse functionalities. In this work, we report a high-performanee dual-channel phototransistor based on one-dimensional (1D)/two-dimensional (2D) trigonal selenium (t-Se)/ReS2 heterostructures grown by chemical vapor deposition. The injection and separati on efficie ncy of photoge nerated electro n-hole pairs can be greatly improved due to the high-quality in terfacial con tact betwee n t-Se nano belts and ReS2 films. Compared with bare ReS2 film devices, the dual-cha nnel phototra nsistor based on t-Se/ReS2 heterostructure exhibits considerable enhancement with the responsivity (R) and detectivity (D^*) up to 98 A·W^-1 and 6 x 10^10 Jones at 400 nm illumination with an in tensity of 1.7 mW·cm^-2, respectively. Besides, the respo nse time can also be reduced by three times of magnitude to less than 50 ms due to the type-11 band alignment at the in terface. This study opens up a promising ave nue for high-performa nee photodetectors by constructing mixed-dimensional heterostructures.

An Integration Strategy to Develop Dual-State Luminophores with Tunable Spectra,Large Stokes Shift,and Activatable Fluorescence for High-Contrast Imaging

Developing dual-state luminophores(DSLs)with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are either aggregation-induced emission or aggregation-caused quenching molecules.Moreover,limited by the structural conservation of the few existing DSLs,there are not enough response sites that can be used to customize various activatable fluorescent probes for specific molecular imaging.Herein,we engineered a general integration strategy for the fabrication of such DSLs with excellent photophysical properties.The DSLs,with their tunable spectra,a large Stokes shift(>170 nm),and achievable near-infrared(NIR)emission,show great potential for high-contrast imaging.Importantly,DSLs can be used as a universal platform for probe customization due to their activatable fluorescence through protection-deprotection of the phenolic hydroxyl group.Based on this,an NIR fluorescent probe DSL-Gal was developed for sensing of β-galactosidase in solutions,senescent cells,and liver metastases with high contrast,further confirming the superiority and universal feasibility of DSLs in probe design.The integration strategy may provide a novel approach for the generation of other DSLs and have great potential applications in bioimaging.

Recent advances in organic-dye-based photoacoustic probes for biosensing and bioimaging

Photoacoustic imaging(PAI) is a non-destructive biomedical imaging technology with broad application prospects. PAI combines the advantages of optical imaging and ultrasound imaging with high selectivity and deep penetration to overcome the high scattering limitation of light in tissues. This emerging technology also achieves high-resolution and high-contrast imaging of deep tissue in vivo. Recently, photoacoustic(PA) probes based on organic dyes have emerged prominently in biosensing and bioimaging due to their excellent optical properties and structural adaptability. This paper gives an outline of the basic PAI principles and focuses on the application of organic-dye-based PA probes for molecular detection and in vivo imaging. The advantages of PAI technology and the drawbacks of current PA probes are then summarized. Finally, the prospects for application are evaluated considering the potential challenges in the biomedical fields.