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1,236 results on '"Liu, Mengqi"'

1. Can thermal nonreciprocity improve the radiative cooling efficiency?

Author

Liu, Mengqi, Jin, Shenghao, Zhou, Chenglong, Wang, Boxiang, Zhao, Changying, and Qiu, Cheng-Wei

Subjects
Physics - General Physics
Abstract

Can thermal nonreciprocity improve the radiative cooling efficiency? Probably not., Comment: 12 pages, 3 figures

Published
2024

14. Micromorphological identification of the leaves of Artemisia stolonifera and Artemisia argyi

Author

LIU Mengqi, WEI Wenna, QIU Tiantian, LAN Jinxu, and CHEN Suiqing

Subjects
artemisia stolonifera, artemisia argyi, micromorphology identification, glandular trichome, leaf veins, Biology (General), QH301-705.5, Botany, QK1-989
Abstract

Abstract [Objective] The aim is to provide micromorphological data for their identification by studying the leaves of Artemisia stolonifera and Artemisia argyi. [Methods] Digital camera, optical microscope, and scanning electron microscope were used to study the characteristics of leaf veins, leaf surfaces, and powder. [Results] (1) Under strong light background, only the veins at all levels of A . stolonifera leaves could be clearly observed. (2) Glandular trichomes were only distributed on the lower surface of the leaves of A . argyi, and there were a large number of glandular trichomes on both the upper and lower surfaces of A . argyi leaves. (3) Similar to A . argyi leaves, the lower surface of A . stolonifera leaves was also densely covered with T-shaped non-glandular trichomes. There were two types of apical cells: One was a long spindle-shaped and curved apical cell, with an average length about 1 450 μm (Type-Ⅰ); the other type of apical cell was long and thin, and flat and twisted, with an average length of approximately 2 800 μm (Type-Ⅱ). (4) There were fewer calcium oxalate cluster crystals in the mesophyll tissue of A . stolonifera leaves, with a maximum of only 10 μm. [Conclusion] Results show that the micromorphological characteristics of the leaf veins and the presence or absence of glandular trichomes on the upper surface of the leaves of A . stolonifera and A . argyi can be used for rapid identification of the two leaves.

Published
2024
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15. Zero-Carbon Urban Design in a Warming World: Learning from Pre-modern Cities

Author

Pojani, Dorina, White, Jessica, Qiu, Feipeng, Lin, Xiaoyu, Qiang, Yishuai, He, Yuan, Liu, Mengqi, Wood, Geoff, Section editor, Onyango, Vincent, Section editor, Yenneti, Komali, Section editor, Liakopoulou, Mariana, Section editor, Wood, Geoffrey, Series Editor, Onyango, Vincent, editor, Yenneti, Komali, editor, and Liakopoulou, Mariana, editor

Published
2024
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18. Nonreciprocal thermal radiation in ultrathin magnetized epsilon-near-zero semiconductors

Author

Liu, Mengqi, Xia, Shuang, Wan, Wenjian, Qin, Jun, Li, Hua, Zhao, Changying, Bi, Lei, and Qiu, Cheng-Wei

Subjects
Physics - Optics, Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

Spectral/angular emissivity $e$ and absorptivity ${\alpha}$ of an object are widely believed to be identical by Kirchhoff's law of thermal radiation in reciprocal systems, but this introduces an intrinsic and inevitable energy loss for energy conversion and harvesting devices. So far, experimental evidences of breaking this well-known balance are still absent, and previous theoretical proposals are restricted to narrow single-band nonreciprocal radiation. Here we observe for the first time, to our knowledge, the violation of Kirchhoff's law using ultrathin ($<{\lambda}/40$, ${\lambda}$ is the working wavelength) magnetized InAs semiconductor films at epsilon-near-zero (ENZ) frequencies. Large difference of $|{\alpha}-e|>0.6$ has been experimentally demonstrated under a moderate external magnetic field. Moreover, based on magnetized ENZ building blocks supporting asymmetrically radiative Berreman and surface ENZ modes, we show versatile shaping of nonreciprocal thermal radiation: single-band, dual-band, and broadband nonreciprocal emission spectra at different wavebands. Our findings of breaking Kirchhoff's law will advance the conventional understanding of emission and absorption processes of natural objects, and lay a solid foundation for more comprehensive studies in designing various nonreciprocal thermal emitters. The reported recipe of diversely shaping nonreciprocal emission will also breed new possibilities in renovating next-generation nonreciprocal energy devices in the areas of solar cells, thermophotovoltaic, radiative cooling, etc., Comment: 21 pages, 4 figures

Published
2022
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21. A Review of the Antibacterial Activity of Chitosan and Its Application in Antibacterial Packaging

Author

LIU Mengqi, LÜ Rui, CHEN Ju, JIAO Ruiwen, MI Chunxiao, LI Xiang, REN Dandan, WU Long, WANG Qiukuan, ZHOU Hui

Subjects
chitosan, antibacterial, composite materials, application, Food processing and manufacture, TP368-456
Abstract

Chitosan can be used as an active antibacterial agent or film-forming substrate in foods, and has become a powerful substitute for synthetic plastic polymers because of its good biodegradability, film-forming capacity and antibacterial activity. However, chitosan films have several limitations such as poor water solubility and weak mechanical properties, which limit its application in antibacterial food packaging materials to a certain degree. The safety of applying the antibacterial activity of chitosan in foods has attracted much attention in recent years. In order to provide new ideas for further development and utilization of chitosan-based antibacterial composite materials, this paper expounds the antibacterial mechanism of chitosan and the methods to improve its antibacterial performance, and summarizes the current status of the application of chitosan-polysaccharide, protein or lipid composite films in food preservation.

Published
2024
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22. Differences and Commonalities in Responses of Zygosaccharomyces rouxii to High Salt and High Temperature Stress

Author

LIU Mengqi, YAN Zhenzhen, HU Na, CHEN Xiong, LI Xin

Subjects
zygosaccharomyces rouxii, high salt stress, high temperature stress, complete synthetic medium, nutritional needs, metabolic differences, gene expression, Food processing and manufacture, TP368-456
Abstract

Complete synthetic minimal media for Zygosaccharomyces rouxii growth were designed for high temperature (40 ℃, HTS) and high salt stress (18% NaCl, HSS) in this study, and the difference in the nutritional requirements of Z. rouxii cells under long-term adverse environmental conditions was analyzed. The differences in the metabolism and gene expression of organic acids, amino acids and sugars during the period from the growth adaptation stage to the early logarithmic stage were highlighted between HSS and HTS conditions. The results showed that Z. rouxii cells exposed to HSS needed more exogenous amino acids, vitamin and amino acid supplementation alleviated HTS-induced damage in yeast cells. The adversity transcription gene MSN4 and the hypertonic regulatory protein gene HOG1 responded to high salt, while the heat shock regulatory protein gene HSF1 and the superoxide dismutase gene SOD1 responded to high temperature. In summary, different strategies for organic acid, amino acid and sugar metabolism were adopted by Z. rouxii in response to HSS and HTS. This study deepens the understanding of the mechanism of temperature tolerance in salt-tolerant Z. rouxii, which will contribute to the development of new brewing yeast cells with tolerance to both high salt and temperature.

Published
2024
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23. Time Series Generation with Masked Autoencoder

Author

Zha, Mengyue, Wong, SiuTim, Liu, Mengqi, Zhang, Tong, and Chen, Kani

Subjects
Computer Science - Machine Learning
Abstract

This paper shows that masked autoencoder with extrapolator (ExtraMAE) is a scalable self-supervised model for time series generation. ExtraMAE randomly masks some patches of the original time series and learns temporal dynamics by recovering the masked patches. Our approach has two core designs. First, ExtraMAE is self-supervised. Supervision allows ExtraMAE to effectively and efficiently capture the temporal dynamics of the original time series. Second, ExtraMAE proposes an extrapolator to disentangle two jobs of the decoder: recovering latent representations and mapping them back into the feature space. These unique designs enable ExtraMAE to consistently and significantly outperform state-of-the-art (SoTA) benchmarks in time series generation. The lightweight architecture also makes ExtraMAE fast and scalable. ExtraMAE shows outstanding behavior in various downstream tasks such as time series classification, prediction, and imputation. As a self-supervised generative model, ExtraMAE allows explicit management of the synthetic data. We hope this paper will usher in a new era of time series generation with self-supervised models.

Published
2022

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