Mechanisms of chiral plasmonics -- scattering, absorption and photoluminescence

Chirality is a concept that one object is not superimposable on its mirror image by translation and rotation. In particular, chiral plasmonics have been widely investigated due to the their excellent optical chiral properties, and have led to numerous applications such as optical polarizing element etc. In this study, we develop a model based on the concept of the interaction between harmonic oscillators to investigate and explain the optical chiral mechanisms of strongly coupled metal nanoparticles (MNPs). The chirality of the scattering, absorption, and photoluminescence spectra are carefully discussed in detail. The results show that the chirality of the system originates not only from the orientations of the MNPs, but also from the different eigen parameters between them. Specifically, the derived three factors contribute to the chirality: the symmetry, the coupling strength, and the coherent superposition of the emitted electric field. This work provides a deeper understanding on the chiral plasmonics and may guide relevant applications in theory.Comment: 8 pages, 8 figure

Unified Treatment for Scattering, Absorption, and Photoluminescence of coupled Metallic Nanoparticles with Vertical Polarized Excitation

Optical properties of coupled metallic particles (MNPs) have been widely reported due to their unique characteristics such as peak shift/splitting of the coupling spectra and electromagnetic enhancement at sub-wavelength scale, etc. In a previous work, we have investigated the coupling spectra of two coupled MNPs with parallel polarized excitation. In this study, we investigate the vertical polarization case in detail. Different from the parallel one, the vertical one has its unique properties: (a) three coupling coefficients; (b) positive coupling terms in the coupling equations; (c) blue-shifts of the peaks with the increasing coupling strength for identical MNPs spectra, including scattering, absorption, and photoluminescence. Comparison with published experimental results shows the validity of this model. This work provides a deeper understanding on the optical properties of coupled MNPs and is beneficial to relevant applications.Comment: 7 pages, 5 figure

Plasmonic nano-resonator enhanced one-photon luminescence from single gold nanorods

Strong Stokes and anti-Stokes one-photon luminescence from single gold nanorods is measured in experiments. It is found that the intensity and polarization of the Stokes and anti-Stokes emissions are in strong correlation. Our experimental observation discovered a coherent process in light emission from single gold nanorods. We present a theoretical mode, based on the concept of cavity resonance, for consistently understanding both Stokes and anti-Stokes photoluminescence. Our theory is in good agreement of all our measurements.Comment: 14 pages, 7 figures, 2 table

AIGC In China: Current Developments And Future Outlook

The increasing attention given to AI Generated Content (AIGC) has brought a profound impact on various aspects of daily life, industrial manufacturing, and the academic sector. Recognizing the global trends and competitiveness in AIGC development, this study aims to analyze China's current status in the field. The investigation begins with an overview of the foundational technologies and current applications of AIGC. Subsequently, the study delves into the market status, policy landscape, and development trajectory of AIGC in China, utilizing keyword searches to identify relevant scholarly papers. Furthermore, the paper provides a comprehensive examination of AIGC products and their corresponding ecosystem, emphasizing the ecological construction of AIGC. Finally, this paper discusses the challenges and risks faced by the AIGC industry while presenting a forward-looking perspective on the industry's future based on competitive insights in AIGC

The current opportunities and challenges of Web 3.0

With recent advancements in AI and 5G technologies,as well as the nascent concepts of blockchain and metaverse,a new revolution of the Internet,known as Web 3.0,is emerging. Given its significant potential impact on the internet landscape and various professional sectors,Web 3.0 has captured considerable attention from both academic and industry circles. This article presents an exploratory analysis of the opportunities and challenges associated with Web 3.0. Firstly, the study evaluates the technical differences between Web 1.0, Web 2.0, and Web 3.0, while also delving into the unique technical architecture of Web 3.0. Secondly, by reviewing current literature, the article highlights the current state of development surrounding Web 3.0 from both economic and technological perspective. Thirdly, the study identifies numerous research and regulatory obstacles that presently confront Web 3.0 initiatives. Finally, the article concludes by providing a forward-looking perspective on the potential future growth and progress of Web 3.0 technology

Simultaneous state and actuator fault estimation for satellite attitude control systems

AbstractIn this paper, a new nonlinear augmented observer is proposed and applied to satellite attitude control systems. The observer can estimate system state and actuator fault simultaneously. It can enhance the performances of rapidly-varying faults estimation. Only original system matrices are adopted in the parameter design. The considered faults can be unbounded, and the proposed augmented observer can estimate a large class of faults. Systems without disturbances and the fault whose finite times derivatives are zero piecewise are initially considered, followed by a discussion of a general situation where the system is subject to disturbances and the finite times derivatives of the faults are not null but bounded. For the considered nonlinear system, convergence conditions of the observer are provided and the stability analysis is performed using Lyapunov direct method. Then a feasible algorithm is explored to compute the observer parameters using linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed approach is illustrated by considering an example of a closed-loop satellite attitude control system. The simulation results show satisfactory performance in estimating states and actuator faults. It also shows that multiple faults can be estimated successfully

Impact of main residential locations on depressive symptoms among older adults in China: A Blinder–Oaxaca decomposition analysis

BackgroundWith the development of urbanization in China, the scale of internal migration and the number of immigrants among older adults are increasing. This requires paying attention to the living conditions and environment of immigrants. Many studies note a gap in the prevalence of depressive symptoms among older adults living in different main residential locations. However, few studies have examined the extent to which main residential locations influence depressive symptoms among older adults. This study aims to quantify the effect of main residential locations on depressive symptoms.MethodsFor this study, we used data from the 2018 Chinese Longitudinal Health and Longevity Survey and randomly selected 8,210 individuals aged 65 years and older were from the community to determine the effect of main residential locations on depressive symptoms among older adults. We further used the Blinder–Oaxaca decomposition method to quantify the explanatory factors of depressive symptom gaps among older adults and to estimate the relative effect of individual characteristics on depressive symptoms.ResultsIn this study, we noted significant differences in depressive symptoms among older adults in different main residential locations. Rural–urban migrants had higher depressive symptom scores (7.164). According to the Blinder–Oaxaca decomposition analysis, the high proportion of the depressive symptom gap can be explained by years of education, income, and exercise among different main residential locations groups. In addition, in the main parts of the explained differences, the proportions of the limitation of activities of daily living (2.28, 0.46, and −52.11%) showed opposite effects, while their share in different main residential locations groups varied widely.ConclusionUrbanization has resulted in more rural people moving to urban areas in China; Rural–urban migrants have the highest prevalence of depressive symptoms, which needs attention. Thus, there is an urgent need to integrate the health insurance and pension policy for urban and rural residents. This study provides a basis for formulating health policies and promoting the mental health of older adults in China as well as in low- and middle-income countries