Diverse bio-sensing and therapeutic applications of plasmon enhanced nanostructures

Substantial advancements have been observed over the years in the research and development of Localized Surface Plasmon Resonance (LSPR). A variety of current and future applications involving anisotropic plasmonic nanoparticles include biosensors, photothermal therapies, photocatalysis, and various other fields. Amongst various other applications, plasmonic enhancements are deployed in Surface Enhanced Raman Spectroscopy (SERS) mediated bio-sensing, absorption spectroscopy based analyte quantification, and fluorescence spectroscopy-based biomolecular detection up to femtomolar level and even on the level of single molecules. LSPR based healthcare diagnostics and therapeutics have grown much faster than expected, with an increased number of published original research articles and reviews. Despite the extensive literature available, a comprehensive review with a focused emphasis on recent advances in the field of plasmonic particle anisotropy, plasmonic nanostructure, plasmonic coupling mediated enhanced LSPR intensity and their diverse applications in biosensing is needed. This article focuses on LSPR properties of anisotropic nanostructures like spherical gold nanoparticles (AuNP), gold nanorod (AuNR), gold nanostar (AuNs), gold nanorattles (AuNRT), gold nanoholes (AuNH), dimeric nanostructures and their role in plasmonic enhancements for targeted biosensing and therapeutic research. The contemporary state of the art biosensing development around SERS has also been discussed. A detailed literature analysis of recent development in micro-surgery, photothermal tumor killing, biosensor development for detection up to single molecule level, high-efficiency drug delivery are covered in this article. Furthermore, recent and advanced technologies including Spatially Offset Raman Spectroscopy (SORS), Surface Enhanced Resonance Raman Spectroscopy (SERRS), and Surface Enhanced Spatially Offset Raman Spectroscopy (SESORS) are presented citing their importance in biosensing. We complement this review article with relevant theoretical frameworks to understand finer nuances within the literature that is discussed.     

Characteristic zirconium-rich coring structures in Mg–Zr alloys

The most characteristic feature of the microstructure of a magnesium alloy that contains more than a few tenths per cent soluble zirconium is the zirconium-rich cores that exist in most grains. The morphology, distribution and composition of cores observed in a Mg–0.56%Zr alloy and the small particles present in them were investigated.     

Cure behavior of colorful ZrO2 suspensions during Digital light processing (DLP) based stereolithography process

In this study, the light absorption of the pure ZrO₂ and three types of colorful ZrO₂ mixtures were investigated. It was found that the absorbance of colored ZrO₂ powder increases with the colorant content, and the yellow-colored powder has the strongest absorbance at the wavelength of 405 nm compared with the other two types of colored ZrO₂ powder. The cure behavior investigation on the ceramic suspensions of the above four types of ZrO₂ powders during DLP process shows that as the colorant content increases, the cure depth and excess cure width both decrease due to the ceramic absorbance. The cure depth of colored suspensions is linear with logarithm of incident energy, consistent with Beer-Lambert model, while the further research into the cure width shows that the excess cure width increases nonlinearly with logarithm of incident energy, which is inconsistent with Quasi-Beer-Lambert model. Additionally, colorful ZrO₂ accessories were successfully fabricated.     

Ferroelectric domain structure and atomic-scale phase distribution in a Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal

Lead-based relaxor ferroelectric crystals, such as Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃, are promising for functional applications due to their outstanding ferroelectric properties. Revealing ferroelectric domain structure and phase distribution at the nanoscale are important to understand the basic theory of ferroelectricity and promote their practical applications. In this study, the ferroelectric domain structure and atomic-scale phase distribution in a Pb(Mg_1/3Nb_2/3)O₃ - 35 at.% PbTiO₃ single crystal in the region of morphotropic phase boundary are systematically investigated by a combination of optical microscopy, scanning electron microscopy, and aberration-corrected transmission electron microscopy. It is found that 90° and 180° coarse domains are formed simultaneously in the ferroelectric single crystal. Moreover, there are tweed-like nano-domains formed inside each coarse single domain. Through careful investigations of distribution of stress and tetragonality, it is revealed that the tweed-like nano-domains are composed of nano-sized rhombohedral (R), monoclinic (M), and tetragonal (T) phases. The nano-scale T, M, R phases have the best, moderate, and lowest ferroelectricity, respectively.     

基于强化学习算法的智能飞控开发系统

无人机控制器的设计开发是一项复杂的系统工程, 传统的基于代码编程的开发方式存在开发难度大、周期长及错误率高等缺点. 同时, 强化学习智能飞控算法虽在仿真中取得很好的性能, 但在实际中仍缺乏一套完备的开发系统. 本文提出一套基于模型的智能飞控开发系统, 使用模块化编程及自动代码生成技术, 将强化学习算法应用于飞控的嵌入式开发与部署. 该系统可以实现强化学习算法的训练仿真、测试及硬件部署, 旨在提升以强化学习为代表的智能控制算法的部署速度, 同时降低智能飞行控制系统的开发难度.     

Ultrafast Electrochemical Growth of Lithiophilic Nano-Flake Arrays for Stable Lithium Metal Anode

Lithium dendrites caused by nonuniform Li⁺ flux leads to the capacity fade and short-circuit hazard of lithium metal batteries. The solid electrolyte interface (SEI) is critical to the uniformity of Li⁺ flux. Here, an ultrafast preparation of uniform and vertical Cu₇S₄ nano-flake arrays (Cu₇S₄ NFAs) on the Cu substrate is reported. These arrays can largely improve the lithiophilicity of the anode and form Li₂S-enriched SEI due to the electrochemical reduction of Cu₇S₄ NFAs with lithium. A further statistical analysis suggests that the SEI, with a higher content of Li₂S, is more effective to inhibit the formation of lithium dendrites and yields less dead lithium. A quite stable coulombic efficiency of 98.6% can be maintained for 400 cycles at 1 mA cm^–2. Furthermore, at negative to positive electrode capacity ratio of 1.5 (N/P = 1.5), the full battery of Li@Cu₇S₄ NFAs||S shows 83% capacity retention after 100 cycles at 1 C, much higher than that of Li@Cu||S (33%). The findings demonstrate that high Li₂S content in the SEI is crucial for the dendrite inhibition to achieve better electrochemical performance.     

Layered Metal-Halide Perovskite Single-Crystalline Microwire Arrays for Anisotropic Nonlinear Optics

Hybrid organic–inorganic metal-halide perovskites with diverse structure tunability are promising for nonlinear-optical (NLO) applications, such as frequency conversion and electro-optic modulation. For integrated NLO devices, single-crystalline perovskite micro- and nanostructures with high quality and multifunctionality are in high demand. However, the fabrication of single-crystalline perovskites arrays is still challenging in regulating liquid dynamics and crystal growth simultaneously. Herein, a capillary-bridge-manipulated strategy is established to steer the dewetting process of microdroplets and provide spatial confinement for crystal growth. These 1D perovskite microwire arrays show regulated geometry, pure orientation, and single crystallinity. Chiral ammonium molecules are introduced into the metal-halide octahedral quantum wells to break the centrosymmetry of the perovskite, allowing the perovskite to exhibit excellent second-order NLO properties. The as-prepared microwire arrays also demonstrate linearly polarized second harmonic generation and two-photon fluorescence. Microwire arrays exhibit higher second harmonic conversion efficiency compared with their polycrystalline thin-film counterparts. It is believed that this strategy for the fabrication of chiral perovskite microstructure arrays holds great promise for NLO integrated applications and opens up an avenue to explore multifunctional chiral perovskites.     

The impact of mapping wander on the performance of SDH AU-4 and TU-3 uniform pointer processors

Pointer processors in Synchronous Optical Networks (SONET)/Synchronous Digital Hierarchy (SDH) networks may be placed into three categories: fixed threshold, adaptive threshold modulation and uniform. Fixed threshold pointer processors produce gapped pointer sequences during SONET/SDH holdover mode, when one or more node's clock has lost its synchronization reference, as a result of the periodic effects of the SONET/SDH frame overhead bytes. These gapped pointer sequences cause mapping wander in the underlying Plesiochronous Digital Hierarchy (PDH) payloads. Uniform pointer processors can smooth the gapped pointer effects caused by the Synchronous Transport Module (STM), Administrative Unit (AU) and Tributary Unit (TU) overhead bytes. However, uniform pointer processors cannot remove the additional gapped pointer effects caused by the Virtual Container (VC) overhead bytes. Mathematical analysis and simulation results, for fixed threshold pointer processors in SDH networks where VC-3 uses TU-3 to transport an E3-rate PDH payload or VC-4 uses AU-4 to transport an E4-rate PDH payload, illustrate the wander caused by the gapped pointer effects. A proposed uniform pointer processor algorithm shows the residual mapping wander caused by the VC-3 and VC-4 overhead bytes. Finally, a lower bound on the Maximum Time Interval Error (MTIE) that can be achieved with a uniform pointer processor is calculated for these two cases.     

The site occupancies of alloying elements in TiAl and Ti3Al alloys

The site occupancies of V, Cr, Mn, Fe, Ni, Zr, Nb, Mo, Ta, Ga and Sn (1–5 at.%) in TiAl alloys with different compositions, and in Ti₃Al with the compositions of Ti–26 at.%Al–(1–2 at.%)X, were measured by the atom location channelling enhanced microanalysis (ALCHEMI) method. For TiAl alloys, the results show that Zr, Nb and Ta atoms invariably occupy Ti sites, while Fe, Ni, Ga and Sn atoms occupy Al sites, the alloy composition having no significant influence on their site preference. By contrast, the site preference of V, Cr, and Mn changes considerably with alloy composition (the Ti/Al ratio in particular), the probability of these elements substituting for Ti decreasing in the above order. For quaternary Ti–Al–V–Cr alloys, the site occupancies of V and Cr do not show much mutual influence. In general, with increasing atomic number, elements in the same period show increasing tendency to substitute for Al, as is the tendency to substitute for Ti for elements in the same group of the periodic table. For Ti₃Al alloys, Ga and Sn atoms occupy Al sites, while V, Cr, Mn, Zr, Nb, Mo and Ta atoms occupy Ti sites, the site preference of V, Cr, Mn and Mo in TiAl alloys being different from that in Ti₃Al. The experimental results are interpreted in terms of a Bragg–Williams-type model and bond-order data obtained from electronic structure calculation. Qualitative agreement between the model and measurements is reached.