Embedded Metal Oxide Plasmonics Using Local Plasma Oxidation of AZO for Planar Metasurfaces

New methods for achieving high-quality conducting oxide metasurfaces are of great importance for a range of emerging applications from infrared thermal control coatings to epsilon-near-zero nonlinear optics. This work demonstrates the viability of plasma patterning as a technique to selectively and locally modulate the carrier density in planar Al-doped ZnO (AZO) metasurfaces without any associated topographical surface profile. This technique stands in strong contrast to conventional physical patterning which results in nonplanar textured surfaces. The approach can open up a new route to form novel photonic devices with planar metasurfaces, for example, antireflective coatings and multi-layer devices. To demonstrate the performance of the carrier-modulated AZO metasurfaces, two types of devices are realized using the demonstrated plasma patterning. A metasurface optical solar reflector is shown to produce infrared emissivity equivalent to a conventional etched design. Second, a multiband metasurface is achieved by integrating a Au visible-range metasurface on top of the planar AZO infrared metasurface. Independent control of spectral bands without significant cross-talk between infrared and visible functionalities is achieved. Local carrier tuning of conducting oxide films offers a conceptually new approach for oxide-based photonics and nanoelectronics and opens up new routes for integrated planar metasurfaces in optical technology.     

燃料电池空气电极的孔道结构调控

燃料电池是将化学能转化成电能的装置，其空气电极催化层的设计，既要包含丰富的、易于接近的反应活性位，也要具备高度连通的电子、质子以及反应物、产物传质通道，因此电极必须具有特定三维几何结构形貌和有序分布的各功能化孔道，确保催化活性位得以充分利用以及反应可以连续进行。针对催化剂孔道的几何结构调控，本文调研了最近报道的一系列研究工作，从模板法、高温相变法、模板/相变复合方法以及基于金属有机框架材料进行孔道设计等四种主要方法出发，综述了该领域的最新研究进展。     

Bipolar resistive switching behavior and conduction mechanisms of composite nanostructured TiO2/ZrO2 thin film

In this work, TiO₂/ZrO₂ bilayer thin film was prepared on fluorine doped tin oxide (FTO)/glass substrates by using a simple and low-cost chemical solution deposition method. Reproducible bipolar resistive switching (RS) characteristics in Au/TiO₂/ZrO₂/FTO/glass devices are reported in this work. TiO₂/ZrO₂ bilayer thin films prepared in this work shows reversible bipolar resistive switching and unidirectional conduction performances under applying voltage and these special performances of TiO₂/ZrO₂ bilayer thin films was first reported. Obvious resistive switching performance can be observed after setting a compliance current, the ratio of high/low resistance reached about 100 at a read voltage of +0.1V and −0.1V and the RS properties showed no obvious degradation after 100 successive cycles tests. The resistive switching characteristics of Au/TiO₂/ZrO₂/FTO/glass device can be explained by electron trapping/detrapping related with the vacancy oxygen defects in TiO₂/ZrO₂ bilayer thin film layer. According to slope fitting, the main conduction mechanisms of the sample are Ohmic and Space charge limited current mechanism.     

Reactive Oxygen and Nitrogen Species in Defense/Stress Responses Activated by Chitosan in Sycamore Cultured Cells

Chitosan (CHT) is a non-toxic and inexpensive compound obtained by deacetylation of chitin, the main component of the exoskeleton of arthropods as well as of the cell walls of many fungi. In agriculture CHT is used to control numerous diseases on various horticultural commodities but, although different mechanisms have been proposed, the exact mode of action of CHT is still unknown. In sycamore (Acer pseudoplatanus L.) cultured cells, CHT induces a set of defense/stress responses that includes production of H₂O₂ and nitric oxide (NO). We investigated the possible signaling role of these reactive molecules in some CHT-induced responses by means of inhibitors of production and/or scavengers. The results show that both reactive nitrogen and oxygen species are not only a mere symptom of stress conditions but are involved in the responses induced by CHT in sycamore cells. In particular, NO appears to be involved in a cell death form induced by CHT that shows apoptotic features like DNA fragmentation, increase in caspase-3-like activity and release of cytochrome c from the mitochondrion. On the contrary, reactive oxygen species (ROS) appear involved in a cell death form induced by CHT that does not show these apoptotic features but presents increase in lipid peroxidation.     

Cocoa polyphenols accelerate vitamin B12 degradation in heated chocolate milk

The rate of vitamin B₁₂ loss was 3X greater in heated, chocolate‐flavoured milk than in unflavoured milk. Studies of B₁₂ stability in the presence of cocoa powder components were performed to identify the reactive agents. Cocoa polyphenols with a strong capacity both for reduction and for peroxide generation accelerated B₁₂ destruction as much as 20‐fold vs. polyphenols without both capacities. Polyphenols with both capacities include the cocoa polyphenol (+)‐catechin and oligomers thereof, but also the structurally related polyphenols gallic acid, caffeic acid and (?)‐epigallocatechin gallate. The demonstrated physical affinity of cocoa powder for B₁₂ was a significant factor in the destructive process. B₁₂ may exhibit decreased stability in heated, neutral pH, polyphenol‐fortified foods.     

Investigations of TaB2 on oxidation-inhibition property and mechanism of Si-based coatings in aerobic environment with broad temperature region for carbon materials

To investigate the formation mechanism of the dendrites glass-ceramics and the effect of TaB₂ modifier on the oxidation-inhibition ability of Si-based coatings in aerobic environment with broad temperature region for carbon materials, the Si-based coatings modified with different TaB₂ content were fabricated by the liquid phase sintering method. The fabricated coatings and its corresponding composite powders were investigated in dynamic TG aerobic environments up to 1500 ℃. The initial oxidation temperatures of Si-based coatings modified with TaB₂ powders are almost completely suppressed to 800 ℃. With the increase of TaB₂ phase content, the relative oxygen permeability of the Si-based coatings is significantly reduced, which can be interpreted as the generation of liquid boride, silicide and Ta-Si-B-O compound glass ceramics those can improve the stability of the coating. The formation mechanism of the dendrites glass-ceramics was illustrated.     

Radiation damage behavior of carbon/carbon composite in Low Earth Orbit environment

To understand the degradation behavior of Carbon/Carbon(C/C) composite in LEO radiation environment, groups of 2D-C/C composites samples were exposed to ground-based Low Earth Orbit(LEO) simulating facilities. The LEO radiating environment covers part of Van Allen inner belt, which contains atomic oxygen(AO) and high-energy proton radiating regions. These two kinds of radiating sources were arranged for simulating the real LEO radiating conditions regarding to the first orbit movement speed of serving space shuttles. Changes of micro-structure, mass loss, surface roughness, chemical construction and thermal physical properties after environmental assessment were analyzed and compared to understand the damage behavior of LEO radiation on C/C composite. It was found that AO is the main factor of mass loss in LEO radiating particles. The charged high-energy protons have an aggravating damage ability with energetic AO, damage situations of degree in orbit down process is more serious than in orbit rising process. The LEO radiation damage mechanisms of C/C composite are revealed and expounded either.     

氧空位超薄Co2AlO4纳米片的合成及其增强电催化氧析出反应（英文）

本文报道了通过脱合金和后续退火工艺合成一种新型超薄二维尖晶石结构的Co2Al O4纳米片.通过温和的溶剂热还原法将氧空位缺陷引入Co2Al O4纳米片中,使得电化学表面积增大,活性位密度变高,钴原子得到电子而产生更多的空轨道.这些空轨道有利于接受水分子中氧原子的孤对电子,促进水分子的活化.含有氧空位的超薄Co2Al O4纳米片在10 m A cm^-2时的过电位为280 m V,塔菲尔斜率为70.98 m V dec^-1.此外,其在碱性溶液中也表现出显著的稳定性,并且优于多数已报道的Co3O4电催化剂.该工作为制备高效的可持续新能源材料提供了新思路.