Two‐dimensional (2D) semiconductors have recently become attractive candidate substrates for surface‐enhanced Raman spectroscopy, exhibiting good semiconductor‐based SERS sensing for a wider variety ...of application scenarios. However, the underlying mechanism remains unclear. Herein, we propose that surface defects play a vital role in the magnification of the SERS performances of 2D semiconductors. As a prototype material, ultrathin WO3 nanosheets is used to demonstrate that surface defect sites and the resulting increased charge‐carrier density can induce strong charge‐transfer interactions at the substrate‐molecule interface, thereby improving the sensitivity of the SERS substrate by 100 times with high reproducibility. Further work with other metal oxides suggests the reduced dimension of 2D materials can be advantageous in promoting SERS sensing for multiple probe molecules.
The down‐sizing of metal oxide semiconductors to ultrathin nanosheets creates intrinsic crystalline defects which alters the electronic structure of the semiconductor and activates SERS performance as a result of promoted charge‐transfer efficiency and charge‐transfer pathways.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Tungsten oxide is a versatile transition‐metal oxide with a vast number of polymorphs and sub‐stoichiometric compositions, featuring innate tunnels and oxygen vacancies. The structure‐determined ...nature, such as altered optical absorption and metal‐like conductivity, makes tungsten oxide an attractive candidate for optoelectronic applications. A brief summary of the recent progress in tungsten oxide for optoelectronic applications is provided, including not only the traditional field of electrochromism/photochromism, but also new areas of application, such as visible‐light‐driven photocatalysis, photothermal therapy, and surface enhanced Raman spectroscopy (SERS). Also, the prospects for future applications of tungsten oxide are summarized and highlighted.
Tungsten oxide possesses unique tunnel structures and sub‐stoichiometric compositions, which endow it with advanced optoelectronic properties. Current challenges and future research directions for optoelectronic applications of tungsten oxide materials are discussed, covering traditional chromogenic applications, together with a focus on the latest applications in visible‐light‐driven photocatalysis, surface‐enhanced Raman scattering, and photothermal therapy.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The integration of artificial intelligence and education is a general trend, and it has become necessary to utilize artificial intelligence for teaching. This study takes the application of ...artificial intelligence technology in teaching strategy as the starting point, constructs an intelligent classroom model for recognizing students’ faces and emotions, and better understands their learning state. The method first carries out emotion recognition based on a support vector machine, then realizes the fusion of the decision layer through a posteriori probability, completes the construction of a multimodal emotion recognition model, and finally applies the PAD scale to quantify the emotion and analyze the emotion and state of the sample students in various stages of the classroom. The artificial intelligence teaching strategy that integrates multimodal emotion recognition is constructed and its application effectiveness is examined. More than 60% of the students were in a calm state in the 10 minutes before and after the class, and 78% of the students were in a positive learning mood in the 25 minutes of the class, so the multimodal emotion recognition model has a good effect of recognizing students’ emotions. After the teaching practice is carried out, the student’s performance in the experimental class is 12.29% higher than that in the control class. The learning stability is better, reflecting the superiority of the teaching strategy in this paper. This study can provide a reference for the teaching of the classroom of the future integration of artificial intelligence technology.
Intercalation-based inorganic materials that change their colours upon ion insertion/extraction lay an important foundation for existing electrochromic technology. However, using only such inorganic ...electrochromic materials, it is very difficult to achieve the utmost goal of full-colour tunability for future electrochromic technology mainly due to the absence of structural flexibility. Herein, we demonstrate an ultracompact asymmetric Fabry-Perot (F-P) nanocavity-type electrochromic device formed by using partially reflective metal tungsten as the current collector and reflector layer simultaneously; this approach enables fairly close matching of the reflections at both interfaces of the WO
thin layer in device form, inducing a strong interference. Such an interference-enhanced device that is optically manipulated at the nanoscale displays various structural colours before coloration and, further, can change to other colours including blue, red, and yellow by changing the optical indexes (n, k) of the tungsten oxide layer through ion insertion.
Electrochromic technology has been actively researched for displays, adjustable mirrors, smart windows, and other cutting-edge applications. However, it has never been proposed to overcome the ...critical problems in the field of surface-enhanced Raman scattering (SERS). Herein, we demonstrate a generic electrochromic strategy for ensuring the reproducibility and renewability of SERS substrates, which are both scientifically and technically important due to the great need for quantitative analysis, standardized production and low cost in SERS. This color-changing strategy is based on a unique quantitative relationship between the SERS signal amplification and the coloration degree within a certain range, in which the SERS activity of the substrate can be effectively inferred by judging the degree of color change. Our results may provide a first step toward the rational design of electrochromic SERS substrates with a high sensitivity, reproducibility, and renewability.
Semiconductor-based surface enhanced Raman spectroscopy (SERS) platforms take advantage of the multifaceted tunability of semiconductor materials to realize specialized sensing demands in a wide ...range of applications. However, until quite recently, semiconductor-based SERS materials have generally exhibited low activity compared to conventional noble metal substrates, with enhancement factors (EF) typically reaching 10
3
, confining the study of semiconductor-based SERS to purely academic settings. In recent years, defect engineering has been proposed to effectively improve the SERS activity of semiconductor materials. Defective semiconductors can now achieve noble-metal-comparable SERS enhancement and exceedingly low, nano-molar detection concentrations towards certain molecules. The reason for such success is that defect engineering effectively harnesses the complex enhancement mechanisms behind the SERS phenomenon by purposefully tailoring many physicochemical parameters of semiconductors. In this perspective, we introduce the main defect engineering approaches used in SERS-activation, and discuss in depth the electromagnetic and chemical enhancement mechanisms (EM and CM, respectively) that are influenced by these defect engineering methods. We also introduce the applications that have been reported for defective semiconductor-based SERS platforms. With this perspective we aim to meet the imperative demand for a summary on the recent developments of SERS material design based on defect engineering of semiconductors, and highlight the attractive research and application prospects for semiconductor-based SERS.
Defect engineering strategies are used to boost the SERS activity of a wide variety of semiconductors including metal oxides, nitrides, carbon materials and transition metal dichalcogenides (TMDs), as discussed in this perspective.
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IJS, KILJ, NUK, UL, UM, UPUK
Surface enhanced Raman scattering (SERS) is a fingerprint spectral technique whose performance is highly dependent on the physicochemical properties of the substrate materials. In addition to the ...traditional plasmonic metal substrates that feature prominent electromagnetic enhancements, boosted SERS activities have been reported recently for various categories of non-metal materials, including graphene, MXenes, transition-metal chalcogens/oxides, and conjugated organic molecules. Although the structural compositions of these semiconducting substrates vary, chemical enhancements induced by interfacial charge transfer are often the major contributors to the overall SERS behavior, which is distinct from that of the traditional SERS based on plasmonic metals. Regarding charge-transfer-induced SERS enhancements, this short review introduces the basic concepts underlying the SERS enhancements, the most recent semiconducting substrates that use novel manipulation strategies, and the extended applications of these versatile substrates.
•Surface-enhanced Raman scattering (SERS) is a fingerprint spectral technique highly dependent on the substrate materials.•Charge transfer transitions are commonly the major contributors to the boosted SERS activities in non-metal substrates.•Novel manipulation strategies and extended applications of the versatile substrates are illustrated on the basis of interfacial charge transfer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Objective and design
This study aimed to investigate the anti-pulmonary inflammation effect of emodin on Wistar rats with lipopolysaccharide (LPS)-induced acute lung injury (ALI) and RAW264.7 cells ...through the mammalian target of rapamycin (mTOR)/hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway.
Subjects
Wistar rats and RAW264.7 cells were studied.
Treatment
LPS was used to induce inflammation in rats or RAW264.7 cells and emodin was given once a day before LPS stimulation and continued for a certain number of days.
Methods
Lung tissues and bronchoalveolar lavage fluid (BALF) were collected for the in vivo experiment, while cells and supernatant were collected for the in vitro experiment. Pathological changes in the lung tissues were assessed by hematoxylin and eosin staining. The levels of inflammatory factors, including TNF-α, IL-1β, and IL-6, were determined by enzyme-linked immunosorbent assay. The expression levels of p-mTOR, HIF-1α, and VEGF proteins were measured by Western blot analysis and immunohistochemistry. The mRNA levels of p70S6K, eIF4E-BP1, and eIF4E were measured by quantitative polymerase chain reaction.
Results
Emodin ameliorated pathological changes and infiltrated inflammatory cells in LPS-induced ALI. It also significantly reduced the expression of inflammatory factors, including TNF-α, IL-1β, and IL-6, in BALF and downregulated the expression of p-mTOR, HIF-1α, and VEGF proteins in the lung tissues. Similar anti-inflammatory effects and the downregulation of the mTOR/HIF-1α/VEGF signaling pathway were found in RAW264.7 cells. The mRNA levels of p70S6K, eIF4E-BP1, and eIF4E also decreased in the macrophages.
Conclusion
Emodin alleviated LPS-induced pulmonary inflammation in rat lung tissues and RAW264.7 cells through inhibiting the mTOR/HIF-1α/VEGF signaling pathway, which accounted for the therapeutic effects of emodin on ALI.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The stray-light suppression of a large off-axis three-mirror anastigmatic space camera has been a hot topic, and this study proposes a composite stray-light suppression strategy that effectively ...suppresses stray light using the combination of a baffle, retaining ring, and internal antistray light measures. Additionally, the light barrier of the third mirror with a three-layered structure was designed to further optimize the composite stray-light suppression system. At the stray-light simulation analysis stage, in view of the limitations of the Torrance–Sparrow scattering analysis model, an analysis model with wide adaptability is proposed, which can be applied to the stray-light simulation analysis of large-size mirrors with rough surfaces. The simulation results indicate that the point source transmittance of the composite stray-light suppression strategy proposed in this paper is of the order of 10−5 before installing the light barrier of the third mirror, and the veiling glare index of the full field of view is less than 5.8%. After installing the light barrier of the third mirror, the point source transmittance reached the order of 10−8, and the veiling glare index of the full field of view was less than 1.31%. Moreover, the influence of the light barrier of the third mirror on the modulation transfer function of the system was less than 2.3%. The modulation transfer function test of the large-width off-axis three-mirror anastigmatic space camera in a simulated vacuum on-orbit environment was completed, and the test results indicated that the negative impact of the light barrier of the third mirror on the modulation transfer function was less than 3.6%. Moreover, an out-of-field imaging test of the space camera was conducted and the results showed that the image was clear, and the SNR reached 80 dB. The simulation and experimental results prove that the solution in this study can effectively solve the problem of stray-light suppression for large off-axis three-mirror anastigmatic space cameras.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Semiconductor-based surface-enhanced Raman spectroscopy (SERS) substrates represent a new frontier in the field of SERS. However, the application of semiconductor materials as SERS substrates is ...still seriously impeded by their low SERS enhancement and inferior detection sensitivity, especially for non-metal-oxide semiconductor materials. Herein, we demonstrate a general oxygen incorporation-assisted strategy to magnify the semiconductor substrate-analyte molecule interaction, leading to significant increase in SERS enhancement for non-metal-oxide semiconductor materials. Oxygen incorporation in MoS
even with trace concentrations can not only increase enhancement factors by up to 100,000-fold compared with oxygen-unincorporated samples but also endow MoS
with low limit of detection below 10
M. Intriguingly, combined with the findings in previous studies, our present results indicate that both oxygen incorporation and extraction processes can result in SERS enhancement, probably due to the enhanced charge-transfer resonance as well as exciton resonance arising from the judicious control of oxygen admission in semiconductor substrate.
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