Table of Content

28 December 2024, Volume 30 Issue 6

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Research progress in coronavirus detection based on thin-film transistors

TU Jianxin, HAO Kui , SUN Le , LI Aijun

2024, 30(6):  989-1005.  doi:10.12066/j.issn.1007-2861.2596

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Thin-film transistors (TFTs) are widely used in bioelectronics for application in detecting metabolites, nucleic acids, proteins, cellular activities, and electrophysiological signals. During the COVID-19 pandemic, TFT-based COVID-19 biosensors displayed excellent performances and high levels of potential for use in various applications. TFTs, such as oxide-based TFTs and graphene field-effect, organic field-effect, and organic electrochemical transistors, yielded promising results in detecting viruses, ribonucleic acid, and antigens and antibodies. This review summarizes biosensors based on TFTs for use in detecting SARS-CoV-2 and the related biomarkers and analyzes sensing strategies based on transistors with different channel materials. Finally, future directions for researches regarding the applications of TFTs in viral detection are proposed.

Research progress on the consolidation and protection of waterlogged wooden artifacts

XU Qingmeng1, 2, 3 , HUANG Xiao2 , LUO Hongjie2, 3 , ZHU Jinmeng4

2024, 30(6):  1006-1017.  doi:10.12066/j.issn.1007-2861.2598

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The consolidation of waterlogged wooden artifacts involves physical, chemical, and biomaterial methods. Physical methods diminish or eliminate surface tension by altering or circumventing the gas-liquid interface. In addition, shrinkage and deformation are caused by internal stress resulting from liquid evaporation in the wood. However, physical methods can only dehydrate wooden artifacts without consolidation and they cannot be used with severely degraded or large wooden artifacts. Chemical methods introduce consolidants to achieve both dehydration and reinforcement by filling wood cell lumens or interacting with cell walls. However, controlling the penetration of consolidants is diffi- cult, and the penetration time can last for several years. In addition, consolidants can degrade over time, which may damage wooden artifacts. Given the high compatibility between biomaterials and wooden artifacts, a greater number of biomaterials have been used recently to consolidate waterlogged wooden artifacts. Yet, factors such as molecular weight, particle size, and solution viscosity of biomass materials hinder their penetration into waterlogged wood artifacts. This area of research remains mostly unexplored, where the current research has focused on new consolidants, with limited studies on the impact of the media used to carry these consolidants on wood. Future studies should attempt to investigate the influence of the media on protective effects, and to estimate the effects of conservation using material chemistry characterization methods.

Diffusion and condensation of water vapor in sandstone of varying weathering degrees in Yungang Grottoes

HUANG Jizhong1, 2, 3 , ZHANG Hongfang1, 2, 3 , CHENG Yuan2, 3 , ZHENG Yi2 , HU Jinshuai1, 2, 3 , ZHANG Yue2, 3

2024, 30(6):  1018-1030.  doi:10.12066/j.issn.1007-2861.2597

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This study focused on sandstones from the Yungang Grottoes under different degrees of weathering and employed a specially designed experimental setup. Using a modified dew point temperature calculation formula, combined with measured temperature, humidity and electrical resistance data, a quantitative evaluation method was developed for water vapor diffusion and condensation processes in sandstone under varying degrees of weathering. Results showed that weathered sandstone had higher porosity and permeability, facilitating water vapor diffusion and condensation. During the water vapor diffusion stage, higher degrees of weathering were correlated with faster inward diffusion rates and greater internal relative humidity. During the condensation stage, as the degree of sandstone weathering increased, the location where condensation water formed became deeper and occurred earlier. In addition, the condensation depth in the rock was positively correlated with the duration of exposure to high-humidity environments. These findings can help in identifying the patterns of water vapor diffusion and condensation in weathered sandstone, thus providing a scientific basis for dealing with condensation issues at stone cultural heritage sites.

Salt transport and crystallization mechanisms and environmental control strategies for inhibiting salt damage to cave temple cultural relics

WU Hong1 , CHEN Ming2 , SONG Yicheng1

2024, 30(6):  1031-1039.  doi:10.12066/j.issn.1007-2861.2641

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Grotto cultural heritage sites, represented by the Mogao Caves in Dunhuang, are important sites in China. However, under the action of evaporation, salt crystallization of the salt solution contained in the rock leads to serious damage to grotto murals and other cultural relics. This study examines the transport and crystallization mechanisms of salt solution in grotto environments. Through theoretical and numerical simulations, we investigated the competitive coupling between salt solution transport and crystallization and the evolution of the spatial distribution of salt concentration. Environmental factors such as ambient temperature, air relative humidity, and wind speed were numerically investigated to determine the critical conditions for salt crystallization. This study considers a combination of environmental control factors necessary to prevent salt crystallization, thus providing a theoretical and operational basis for the protection of related cultural relics.

Adsorption and transport properties of lithium ions in covalent organic framework/graphene composites

XU Yi , SUN Yiwen , SUN Yi , FANG Haoyan , ZHOU Ziheng , YUAN Bin

2024, 30(6):  1040-1052.  doi:10.12066/j.issn.1007-2861.2494

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The adsorption and transport properties of lithium ions (Li+) in covalent organic framework (COF)/graphene (G) composites (COF@G) were investigated using molecular simulations. The adsorption sites and sequence of Li+ were defined, and the corresponding adsorption energy was determined together with the apparent change in the morphology of COF@G. Additionally, the internal π-π stacking interactions and COF-G and Li+-G distances were calculated. When the saturated adsorption state was attained, the volumetric change rate of COF@G was lower than 25%, and the average voltage remained above 3.20 V. Under the same conditions, Li+ exhibited the highest conductivity on the outer surface of G. These results provide a theoretical basis for the practical applications of these systems.

Seismic behavior and parametric analysis of CFST composite column to H-section steel beam joint with outer sleeve

LI Chenfan, YANG Feng

2024, 30(6):  1053-1066.  doi:10.12066/j.issn.1007-2861.2504

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A finite element (FE) model was established for a concrete filled steel tube (CFST) composite column connected to an H-section steel beam joint with an outer sleeve. Considering the damage to concrete under cyclic loading and the Bauschinger effect in steel and referencing existing experimental data, the seismic behavior and failure mode of the joint were examined throughout the process. Furthermore, important parameters influencing the joint’s seismic performance were analyzed. The results indicated that the FE calculations were in good agreement with the experimental results, and the hysteretic curves of the joint were plump. The ductility coefficient was in the range of 3.17-4.19 and equivalent viscous damping coefficient was in the range of 0.211-0.326. The outer sleeve thickness significantly affected the failure mode of the joint. As the sleeve thickness increased, the deformation in the joint panel zone improved, and the failure section moved from the joint to the beam section. By reducing the width-to-thickness ratio and increasing the sleeve height, the hysteresis performance and stiffness of the joint were improved. The thickness and height of the reinforced ribs were positively correlated with the bearing capacity and stiffness of the joint. To ensure that the joint satisfies the stiffness requirements, the width-to-thickness ratio of the sleeve should not exceed 25, the height of the sleeve should not be less than 150% of the width of the sleeve, and the thickness of the reinforced rib should not be less than 50% of the width of the beam flange.

Non-parametric option hedging: evidence derived from SSE 50 ETF options

WANG Weiguan, DING Jing, LIU Xin

2024, 30(6):  1067-1079.  doi:10.12066/j.issn.1007-2861.2633

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This paper investigated the performance of non-parametric option hedging methods in the Chinese market, in which investors minimized their single-period mean-squared hedging errors. Experiments were conducted using SSE (Shanghai stock exchange) 50 ETF (exchange traded fund) options. It was proposed the use of feed-forward neural networks and linear regression for model mapping from option-observable variables to hedging strategies. Results showed that non-parametric methods significantly outperformed the benchmark parametric models with hedging errors reduced by over 10% due to the fact that non-parametric models could capture the leverage effect in the SSE 50 ETF option market.

Pricing and empirical analysis of convertible bonds with equity dilution and default risk

LUO Chun , MA Xuanhang , XU Chenxi , XIA Qiqi , JIA Junle , PAN Xiang

2024, 30(6):  1080-1095.  doi:10.12066/j.issn.1007-2861.2490

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The pricing processes of the stock and corporate assets for convertible bonds follow the Markov regime-switching model, while taking the equity dilution effect and default risk into account. This study aims to obtain a pricing formula for convertible bonds using change of measure and risk-neutralized pricing theory. Theoretical and numerical analyses show that the introduction of the Markov modulation model and the equity dilution effect can prevent the overvaluation of convertible bonds. The findings also indicate that convertible bond values differ obviously under various initial economic states.

The influence of financial development and R&D element flow on economic development

TANG Meijuan, YU Liying

2024, 30(6):  1096-1108.  doi:10.12066/j.issn.1007-2861.2235

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The financial development and R&D elements are the key factors that affect the high-quality development of China’s economy. Based on the panel data of 30 provinces and cities in China from 1999 to 2016, a panel econometric model was established to focus on the mechanism of the influence of these two factors on economic development. Firstly, the financial development level is represented by the scale of financial development and the marketization level of the financial industry, and the R&D elements are measured by the flow of R&D personnel and the flow of R&D capital, and the characterization indexes are measured respectively. Secondly, the fixed effect model was used to conduct an empirical study on how financial development and the flow of R&D elements affect China’s economic development. Results show that the scale of financial development and financial marketization level and R&D personnel flow can significantly promote the regional economic growth in China, Compared with the financial development level, the promotion degree of the flow of R&D elements is small. The promotion degree of financial elements and the flow of R&D elements in the east, central and west of China is different; Besides,there is an interaction between the flow of R&D capital and the marketization level of the financial industry, which affects the regional economic development.

Enterprise manufacturing/remanufacturing strategy with consumer returns

ZHAO Lianxia, XI Jie, LIU Jia, MIAO Xiaoyue, CHEN Yawei

2024, 30(6):  1109-1120.  doi:10.12066/j.issn.1007-2861.2427

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Based on the impact of product return rate and product differentiation on consumer purchasing behavior, this study constructs a green closed-loop supply chain model consisting of a manufacturer and a retailer, and studies product manufacturing/remanufacturing and marketing strategies, where the manufacturer produces new and remanufactured products, sells new products to the retailer, and sells remanufactured products directly to consumers. The retailer sells new products and returns any returned products to the manufacturer. The results of solving and analyzing the game model show that an increase in the unit return processing cost and return rate can reduce the profits of the manufacturer and retailer. When the unit return processing cost is low, the manufacturer chooses to remanufacture part of the waste product; otherwise, the manufacturer remanufactures all the waste products. This study further examines an extended model that introduces sales effort. The numerical experiment shows that the introduction of sales effort can increase the profits of the manufacturer and retailer, and that the manufacturer is willing to undertake more sales effort costs with higher return rates.