Qiumei Lei

Shenzhen Technology University

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Wenyao Li

Zhejiang Chinese Medical University

Gaoqi Tian

Shenzhen Technology University

Anna Su

Shenzhen Technology University

Xiaoyang Zhu

South China Agricultural University

Weixin Chen

Beijing University of Chinese Medicine

Xueping Li

Chongqing Medical University

Bowang Zhao

Shanghai University of Engineering Science

M. Shaheer Akhtar

Jeonbuk National University

Tao Ji

Nantong University

Silin Fan

South China Agricultural University

Cooperative Institutions

Shenzhen Technology University

South China Agricultural University

Shanghai University of Engineering Science

State Key Laboratory For Conservation and Utilization of Subtropical Agro-Bioresources

Chinese Academy of Sciences

Jiangxi University of Science and Technology

Donghua University

Shanghai Jiao Tong University

Nanchang University

Shenzhen University

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Melatonin Maintains Fruit Quality and Reduces Anthracnose in Postharvest Papaya via Enhancement of Antioxidants and Inhibition of Pathogen Development

Antioxidants (2022)

Silin Fan Qian Li Shujie Feng Qiumei Lei Farhat Abbas

Papaya fruit is widely grown in tropical regions because of its sweet taste, vibrant color, and the huge number of health benefits it provides. Melatonin is an essential hormone that governs many plants' biological processes. In the current study, the impact of melatonin on fruit ripening and deterioration in postharvest papaya fruit was explored. An optimum melatonin dose (400 μmol L-1, 2 h) was found to be effective in delaying fruit softening and reducing anthracnose incidence. Melatonin enhanced antioxidant activity and decreased fruit oxidative injury by lowering superoxide anion, hydrogen peroxide, and malondialdehyde content by enhancing the enzymatic and non-enzymatic antioxidants, and by improving the antioxidant capacity of papaya fruit. Melatonin increased catalase, ascorbate peroxidase, NADH oxidase, glutathione reductase, polyphenol oxidase, superoxide dismutase, and peroxidase activity, as well as induced total phenol, total flavonoid, and ascorbic acid accumulation. Melatonin also enhanced the activity of defense-related enzymes, such as chitinase, 4-coumaric acid-CoA-ligase, and phenylalanine ammonia lyase, while it repressed lipid metabolism. Additionally, melatonin inhibited the development of anthracnose in vitro and in vivo. These findings suggest that exogenous melatonin application improves papaya fruit quality by boosting antioxidant and defense-related mechanisms.

Glutathione reductase

Phenylalanine ammonia-lyase

10.3390/antiox11050804

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Citations (31)

Trimetallic MOF-derived CoFeNi/Z-P NC nanocomposites as efficient catalysts for oxygen evolution reaction

Dalton Transactions (2023)

Xudun Shen Liping Huang Shuaishuai Li Longnian Tang Qiumei Lei

We used sodium hydroxide-mediated approach and tannic acid etching to prepare hollow structured trimetallic MOF-derived CoFeNi/Z-P NC nanocomposites. Remarkably, the resulting CoFeNi/Z-P NC nanocomposites have large specific surface area and mesoporous structure, making their active sites more accessible and mass transfer more effective. More complex trimetallic components provide greater possibilities for further improving electrocatalytic performance. The CoFeNi/Z-P NC nanocomposites demonstrate notable enhancements for the OER, and 10 mA cm-2 current density is achieved at a low overpotential of 244 mV, with a low Tafel slope of 66.2 mV dec-1 and have good stability in alkaline solutions. In addition, as a cathode material for overall alkaline water splitting, CoFeNi/Z-P NC is better than RuO2 with longer cycling stability.

Overpotential

Oxygen evolution

10.1039/d3dt02818f

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Citations (4)

Analysis of Electrical Characteristics of N-Doped TiO₂ and Si Heterojunction Diodes

Journal of Nanoelectronics and Optoelectronics (2023)

Qiumei Lei Gaoqi Tian Xiaoping Lei Wenyao Li Anna Su

Heterojunction photodiodes play a crucial role in various industries and daily life. They find application in fields such as photoelectric detection, aerospace, and intelligent manufacturing. In this study, we employed a series of growth processes, including physical vapor deposition techniques such as magnetron sputtering, high-temperature annealing, and hydrothermal growth, to fabricate N-doped TiO 2 heterojunction diode devices with Si as a substrate material. The surface of the device exhibited a columnar array structure with rutile phase TiO 2 . Additionally, the doping of N element led to the bending of the energy band of TiO 2 by approximately 0.2 eV, and the Fermi level also shifted to the valence band, without any effect on the band gap. The I–V characteristics varied in vacuum and air, with ideal factors ( η ) of 4.1 and 8.72, respectively. The study is expected to broaden the application scope of doped photodiodes.

Photodiode

Photoelectric effect

10.1166/jno.2023.3413

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Citations (1)

Enhancing Oxygen Sensing Precision Through Gate-Controlled TiO₂ Field Effect Transistors Under Ultraviolet Excitation

Science of Advanced Materials (2023)

Qiumei Lei Yan Shao Guojia Lu Ahmad Umar Ahmed A. Ibrahim

We report on the fabrication and characterization of a novel oxygen sensor based on a TiO 2 thin film field effect transistor (FET) deposited on a silicon substrate with an oxide layer by magnetron sputtering. TiO 2 is a n -type semiconductor with a wide band gap, which allows the formation of oxygen vacancies or adsorbed oxygen species on its surface under ambient conditions. These oxygen-related defects act as electron traps that modulate the electrical conductivity of the TiO 2 film. Under ultraviolet (UV) irradiation, at 310 nm wavelength, the photogenerated carriers in the TiO 2 film are captured by the oxygen defects, resulting in a decrease of the film resistance that depends on the oxygen concentration. We demonstrate that the sensitivity and resolution of the oxygen sensor can be enhanced by applying a positive gate voltage to the FET device. The photocurrent variation per unit of oxygen concentration (Δ I photo /ΔCPO) increases from 1.08 at VG =0 V to 2.5 at VG= 20 V in the range of 5%–20% oxygen concentration. The gate voltage also extends the controllable range of oxygen defects and photocurrent. Our study provides a new insight into the design and optimization of gas sensors based on TiO 2 thin film FETs.

Photocurrent

Ultraviolet

Oxygen sensor

Photoconductivity

10.1166/sam.2023.4602

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Citations (1)

Flexible Carbon Fiber/TiO₂ Nanopillars Electrode in the Detection of Glucose Under Photoexcitation

Journal of Nanoelectronics and Optoelectronics (2023)

Gaoqi Tian Yaolan Yang Wenyao Li Ying Meng Tianyou Zhou

The development and utilization of biosensors have received a great attention from the scientific community due to their wide applications in the areas of food safety, medical diagnosis, environmental monitoring and other fields. In this paper, we report the development of a novel photoelectrochemical (PEC) sensor for glucose detection using a flexible carbon fiber/TiO 2 nanopillars electrode. The carbon fiber/TiO 2 nanopillars was prepared by two step process in which the first step is to grow TiO 2 seeds over carbon fiber by magnetron sputtering while the second step leads the growth of TiO 2 nanopillars over flexible carbon fibers substrate. Under photoexcitation, the PEC sensor showed a significant enhancement in the sensitivity for glucose detection. The detection mechanism was based on the photoelectrochemical oxidation of glucose to gluconic acid, which generated an electrical signal that was proportional to the glucose concentration. The electrochemical examinations were performed at low glucose concentrations in the range of 1–5 mM (mmol L −1 ) to investigate the corresponding photocurrent. The results showed that the photocurrent increases with increasing the glucose concentration. This is of great significance for the detection of hypoglycemia, and has good application prospects in the fields of nano-detection, biological diagnosis and wearable devices. The flexible carbon fiber/TiO 2 PEC sensor developed in this study is a promising approach for the development of wearable devices for continuous glucose monitoring.

Photocurrent

Nanopillar

Carbon fibers

10.1166/jno.2023.3394

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Melatonin Treatment Improves Postharvest Preservation and Resistance of Guava Fruit (Psidium guajava L.)

Foods (2022)

Silin Fan Tiantian Xiong Qiumei Lei Qinqin Tan Jiahui Cai

Guava fruit has a short postharvest shelf life at room temperature. Melatonin is widely used for preservation of various postharvest fruit and vegetables. In this study, an optimal melatonin treatment (600 μmol·L-1, 2 h) was identified, which effectively delayed fruit softening and reduced the incidence of anthracnose on guava fruit. Melatonin effectively enhanced the antioxidant capacity and reduced the oxidative damage to the fruit by reducing the contents of superoxide anions, hydrogen peroxide and malondialdehyde; improving the overall antioxidant capacity and enhancing the enzymatic antioxidants and non-enzymatic antioxidants. Melatonin significantly enhanced the activities of catalase, superoxide dismutase, ascorbate peroxidase and glutathione reductase. The contents of total flavonoids and ascorbic acid were maintained by melatonin. This treatment also enhanced the defense-related enzymatic activities of chitinase and phenylpropanoid pathway enzymes, including phenylalanine ammonia lyase and 4-coumaric acid-CoA-ligase. The activities of lipase, lipoxygenase and phospholipase D related to lipid metabolism were repressed by melatonin. These results showed that exogenous melatonin can maintain the quality of guava fruit and enhance its resistance to disease by improving the antioxidant and defense systems of the fruit.

Phenylalanine ammonia-lyase

Glutathione reductase

10.3390/foods11030262

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Citations (50)

Combination of 1-MCP and modified atmosphere packaging (MAP) maintains banana fruit quality under high temperature storage by improving antioxidant system and cell wall structure

Postharvest Biology and Technology (2023)

Xiaoyan Li Tiantian Xiong Qiunan Zhu Yiwei Zhou Qiumei Lei

Modified atmosphere

Musa acuminata

10.1016/j.postharvbio.2023.112265

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Citations (30)

Influence of Oxygen Adsorption on Local N-Doped TiO₂/p-Si (100) Heterojunction UV-Visible Photodetector

Science of Advanced Materials (2023)

Gaoqi Tian Qiumei Lei Wenyao Li Anna Su Mohamed Hashem

TiO 2 -based devices are known for their responsive behavior to environmental conditions. In this study, we report the fabrication of a locally N-doped TiO 2 / p -Si (100) heterojunction UV-vis photodetector, achieved through a series of processes including magnetron sputtering, high-temperature annealing, hydrothermal synthesis, and thermal evaporation. Due to surface oxygen adsorption and partial nitrogen doping in TiO 2 , the photocurrent of the device was found to be higher in vacuum than in air at low voltage, and lower in vacuum than in air at higher voltage. Moreover, the photocurrent was more likely to reach saturation under vacuum at low voltage. Under UV light illumination (380 nm), the voltage applied to the device to reach the saturation currents in vacuum and air were approximately −1 V and −1.5 V, respectively, and these values increased slightly when illuminated by visible light (480 nm). The study of the impact of oxygen adsorption and partial N doping in TiO 2 on the hindrance and multiplier effects of carrier movement in photodetectors can be beneficial for the development and application of wearable, biosensing, and vacuum sensing devices.

Photocurrent

Saturation current

10.1166/sam.2023.4467

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Nitrogen-Phosphorus-Doped Trimetallic Hollow MOF for Efficient Oxygen Evolution Reactions

Authorea (Authorea) (2023)

Xudun Shen Liping Huang Shuaishuai Li Longnian Tang Qiumei Lei

We employed a synergistic approach by utilizing in situ etching and phosphating techniques on trimetallic zeolitic imidazolate frameworks (ZIFs) to facilitate the conversion of CoFeNi-ZIFs into CoFeNi/Z-P NC (Nitrogen-doped graphene coating) nanocomposites. Remarkably, the resulting CoFeNi/Z-P NC materials have a large surface area and a lot of pore volume, making their active sites more accessible and makes mass transfer more effective. Additionally, the introduction of Fe and Ni guest metals into the CoP crystal lattice without phase segregation ensures a homogeneous distribution while altering the electrical characteristics. Leveraging these advantages, the CoFeNi/Z-P NC nanocomposites demonstrate a notable enhancement for the OER, 10mA cm-2 is achieved at a low overpotential with a current density of 244mV for alkaline solutions, with a low Tafel slope of 66.2mV dec-1 and has good stability.

Overpotential

Oxygen evolution

10.22541/au.169277546.64290616/v1

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An enzyme-free glucose sensing device based on TiO2 nanorod array photoelectric catalysis

Chinese Journal of Structural Chemistry (2023)

Anna Su Qiumei Lei Gaoqi Tian Yaolan Yang Shuqing He

Glucose oxidase

Photocurrent

Nanorod

Photoelectric sensor

Linear range

10.1016/j.cjsc.2023.100133

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Citations (4)