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Giant Second-Order Nonlinearity and Anisotropy of Large-Sized Few-Layer SnS with Ferroelectric Stacking
No full textThe giant second-order nonlinearity of SnS with ferroelectric stacking is reported. Based on theoretical calculations, the susceptibility of second harmonic generation (SHG) from SnS with ferroelectric stacking is up to 1354 pm V−1, which is three orders of magnitude higher than the values of traditional nonlinear crystals such as BBO and KTP. The SHG from ferroelectric SnS few layers is experimentally measured and its intensity is found to be 131 times larger than that of a MoS2 monolayer under the same experimental conditions, with a photon energy of 1.55 eV. The SHG susceptibility is determined to be on the order of 100 pm V−1. Numerous SnS flakes are systematically investigated using polarization-resolved SHG. Micrometer-sized flakes with a single domain are found, and their SHG anisotropic patterns fit well with the theoretical calculations derived from first-principles methods. The variation in SHG anisotropic patterns, attributed to SHG interference from multiple domains, is investigated both theoretically and experimentally. Additionally, the impact of stacking disorder on the SHG anisotropic pattern is explored. It is demonstrated that polarization-resolved SHG microscopy is a valuable tool for identifying domains in SnS flakes and examining stacking disorder.補正完畢DE
Manipulating the electrochemical surface reconstruction of nickel foam via electrolyte engineering for efficient oxygen evolution reaction at industrial-level current density
No full textThe surface reconstruction process happened to electrocatalysts for creating active sites, which has been evidenced to determine the electrocatalytic activity for water splitting. Herein, the electrolyte conditions (i.e., OH– and Fe3+) were engineered to manipulate the surface reconstruction process happened to nickel foam (NF) for forming Fe-incorporated γ-NiOOH phases, and a low overpotential of only 267 mV could be achieved for alkaline oxygen evolution reaction (OER) at the current density of 100 mA cm–2. More excitingly, the anion exchange membrane water electrolyzer (AEMWE) with Fe-incorporated γ-NiOOH phases created on NF as the anode could survive from a 100-h operation at an industrial-level current density of 1 A cm–2. The OH– ions in the electrolyte could promote the dissolution-redeposition process with created γ-NiOOH phases active for the OER, and meanwhile boost the incorporation of Fe into the formed γ-NiOOH phases, thermodynamically facilitating the formation of O* intermediates for improved OER performance.補正完畢US
Fe species supported on blue-TiO2/WO3 nanocomposite as catalyst for the decomposition of toluene vapor under white light-emitting diode lighting
No full textPhotocatalytic nanomaterials for indoor air purification have garnered attention for the removal of aromatic compounds, including toluene, among volatile organic compounds (VOCs). However, there are still limitations that need to be addressed for the practical implementation of this technology, such as low efficiency under indoor lighting and the stability of photocatalytic nanomaterials under real atmospheric conditions. In this study, we present an nanoscaled iron-decorated blue TiO2/WO3 Z-schemed catalyst that possesses the ideal band position for efficiently eliminating toluene. This catalyst generates reactive oxygen species, oxidizing toluene to benzaldehyde and ultimately converting it to CO2 under visible LED light. The toluene removal efficiency continuous flow reaction system is five times higher than that of each catalyst under a constant airflow system. The introduction of nanoscaled iron at the interface and on the surface between BTO and WO3 nanoparticles facilitates Z-scheme charge transfer, promoting the generation of reactive oxygen species (ROS) and effectively breaking down toluene via the Fenton reaction. The catalytic activity of BTO-Fe/WO3 is maintained at over 92% efficiency, even after three recycling cycles. This study demonstrates that the hybridization of nanoscaled iron and semiconductors can decompose the stable toluene ring even under an ambient visible light, showcasing practical performance for feasible air purification in a common indoor environment system.補正完畢US
Peculiar spin glass phase emerging in FeCo/FePt driven via nanoconfined crystallographic distortions
No full textWe explore the existence of spin glass phase in FeCo/FePt bilayers arising due to disordered ferromagnet. The non-ergodic and highly degenerate landscape of the spin glass phase at low temperature explains the origin of complex magnetic texture in the FeCo/FePt system. Upon cooling the bilayered system, the magnetic texture undergoes spin freezing below 120 K as evident from the bifurcations in zero field cooling and field cooling magnetizations at low magnetic field as a manifestation of broken ergodicity. The uncompensated magnetic moments originating in the spin glass state result in slow time dynamics of thermoremanent magnetization. Consequently, the bilayers demonstrate an intriguing magnetic memory effect in which the magnetic state of the system could be retrieved upon isothermal ageing below 120 K after reversing the temperature cycle. Thermal treatment deteriorates the spin glass behaviour and shows a transition to strong ferromagnetic character in FeCo/FePt bilayers.補正完畢GB
Role of annealing environments on the local electronic and optical properties of zinc oxide films
No full textThe exploration of zinc oxide (ZnO) has seen rapid growth due to its wide bandgap, high thermal conductivity, and high electron mobility within its nanostructures, making it highly valuable for applications in electronic and optical devices. This study involves the deposition of ZnO nanostructures onto a quartz substrate using the thermal evaporation deposition technique. The research delves into the influence of various annealing environments on morphology and electronic/atomic structures. X-ray Diffraction (XRD) analysis reveals the development of the ZnO phase with a preferred orientation when annealed in a mixture of hydrogen and argon gases. It was observed that the films do not transform into complete ZnO for the as-prepared and for lower temperatures (< 400 °C). Annealing at lower temperatures or room temperature retains the metallic Zn. When subjected to higher annealing temperatures in the presence of oxygen and ambient conditions, formation of ZnO hexagonal wurtzite structures was evident. A wide variation in the morphology was observed for films annealed in different annealing environments, from petal-like structures to rods. Both the band edge and defect emissions using photoluminescence were observed to vary with varying annealing conditions. In-situ XANES uncovers the reduction of Zn and metallic nature noticed in the as-prepared sample and argon annealing at 400 °C. A higher charge transfer by Zn with a prominent delocalization of Zn 4p state was observed in oxygen annealing environment at 400 °C with an enhanced coordination of Zn–O and Zn–Zn. These distinct photoluminescence emissions from the films were correlated to the electronic structure and local atomic structure. Further, this investigation provides a path to develop next-generation optoelectronic devices.補正完畢US
Efficient synthesis of porous triazine-based macrocycles with 22-carbon and 6-nitrogen ring atoms and their adsorption/desorption of non-volatile organic compounds
No full textPorous triazine-based macrocycles with 22-carbon and 6-nitrogen ring atoms were efficiently synthesized and used for adsorbing bisphenol A, sulfamethoxazole, sodium dodecyl sulfate, and polyoxyethylene laural ether from aqueous media; after adsorption, simple extraction to desorb the guests from these porous macrocycles demonstrates a facile and efficient approach for porous materials to adsorb and desorb non-volatile organic compounds, thus being potentially applied to other surfactants or antibiotics.補正完畢GB
In-Situ Synthesis of NbC Nanoparticle-Decorated Polyimide-Derived Graphene for Enhanced Thermal Management
No full textThermal management and heat dissipation are universal challenges related to high-power systems. Graphene and its related composite materials exhibit the potential for widespread application as thermal management materials owing to their high thermal conductivity and emissivity. In this study, we synthesize polyimide (PI)-derived graphene (PDG) incorporated with NbC nanoparticles via CO2 laser scribing on Nb precursor-containing PI sheets. The resultant NbC-decorated PDG (NbC-PDG) shows improved thermal conductivity (0.70 W/m·K) compared with bare PDG (0.24 W/m·K). We use NbC-PDG as an efficient heat sink for industrial computers (ICs), light-emitting diode (LED) modules, and lithium-ion batteries (LIBs). The equilibrium temperature of the applications can be reduced significantly by the NbC-PDG layer owing to its excellent radiation heat transfer. After integration of the NbC-PDG heat sink, the equilibrium temperatures of the IC, LED module, and LIB decreased by 8.1, 9.9, and 7.3 °C, respectively. Accordingly, the performance, efficiency, and lifetime of optoelectronic and electrochemical systems can be enhanced considerably. The NbC-PDG composite with broadband absorption and excellent photothermal properties can be applied for efficient solar–thermal energy conversion. Additionally, we fabricate an NbC-PDG-deposited melamine sponge via spray coating and evaluate its performance in solar-driven desalination and water purification.補正完畢NL
An easy-to-implement construction for (k,n)-threshold progressive visual secret sharing schemes
No full textVisual cryptography encrypts the secret image into n shares (transparency) so that only stacking a qualified number of shares can recover the secret image by the human visual system while no information can be revealed without a large enough number of shares. This paper investigates the ( k, n )-threshold Visual Secret Sharing (VSS) model, where one can decrypt the original image by stacking at least k shares and get nothing with less than k shares. There are two main approaches, which have been showed equivalent in some sense, in the literature: codebook-based schemes and random-grid-based schemes; the former is the case of this paper. In general, given any positive integers k and n, it is not easy to design a valid scheme for the ( k, n )-threshold VSS model. In this paper, we propose a simple strategy to construct an efficient scheme for the ( k, n )-threshold VSS model for any positive integers 2 ≤ k ≤ n. The crucial idea is to establish a seemingly unrelated connection between the ( k, n )-threshold VSS scheme and a mathematical structure — the generalized Pascal’s triangle. This paper improves and extends previous results in four aspects:
• Our construction offers a unified viewpoint and covers several known results.
• The resulting scheme has a progressive-viewing property that means the more shares being stacked together the clearer the secret image would be revealed.
• The proposed scheme can be constructed explicitly and efficiently based on the generalized Pascal’s triangle without a computer.
• Performance of the proposed scheme is comparable with known results.補正完畢GB
Reliability assessment and remaining useful prediction based on the inverse Gaussian step-stress accelerated degradation data.
No full textAn inverse Gaussian step-stress accelerated degradation test model was put forward, in which the drift and shape parameters are functions of the stress levels. The confidence intervals of the model parameters and some reliability measures, such as the mean lifetime, the reliability function, and the pth percentile under the rated usage stress, are presented. The online and offline remaining useful life prediction intervals under the rated usage stress level are also acquired. Simulation technologies are used to examine the effect of the presented interval estimation approaches. Simulation results manifest that the presented interval estimation method performs well in all cases. Finally, a case study is provided to illustrate our inference approaches.補正完畢US
Empire, the Politics of Care, and Illness as Metaphor: La Mona, AIDS, and Blue Buster in Alejandro Morales's The Rag Doll's Plagues
No full text《布娃娃瘟疫》是一部有關醫學的推想小說，探索歷史、醫學、殖民、環境和 醫療歧視的議題。小說分為三卷，場景發生在三個不同的地方：（一）十八世紀西 班牙帝國統治下的墨西哥市（Mexico City）、（二）二十世紀七○年代的加州橘郡 （Orange County）的德里（Delhi），以及（三）2050 年未來的聯合城（Lamex）， 而且主要敘述者皆為葛利果（Gregorio）或格利高里醫師（Doctor Gregory）。在第 一卷中，葛利果受到帝國徵召，前往墨西哥市治療「夢娜瘟疫」，俗稱「布娃娃瘟 疫」。 葛利果是西班牙皇家醫療和醫藥董事會的主任， 同情底層階級， 最後選擇 「再棲居」美洲新大陸。第二卷剖析敘述者格利高里（Gregory）的女友因輸血之 故，感染「人類免疫缺乏病毒」（HIV）而飽受醫療歧視與汙名化的創傷。第三卷 發生於未來的後國家社會，描述拉美醫療走廊的主任暨醫學生物環境遺傳學專家格 利高里醫師與助理佳比（Gabi Chung）醫治「藍色剋星」（Blue Buster）病患，並 找尋病毒解方。本文嘗試以環境醫療人文的視角重審墨裔美國小說家莫拉利斯瘟疫 論述中的帝國、瘟疫、環境污染、健康、公衛危機、照護政治、疾病隱喻和生命政 治之間的關係。論文分為五個部分：（一）導論；（二）夢娜病毒：帝國、獵巫和 照護倫理學 ；（三）愛滋病：醫療歧視、污名化和疾病隱喻；（四）藍色剋星：危 脆性與環境歧視；（五）結論。在結論中，我特別指出環境健康和身體健康的鑲嵌 性、纏繞性和共構性。補正完畢TW