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Compact high-bandwidth single-beam optically-pumped magnetometer for biomagnetic measurement

BIOMEDICAL OPTICS EXPRESS 2025年第1期16卷 235-244页

作者： Wu, Tianbo Xiao, Wei Peng, Xiang Wu, Teng Guo, Hong Peking Univ Sch Elect State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China Peking Univ Ctr Quantum Informat Technol Beijing 100871 Peoples R China Beijing Inst Technol Adv Res Inst Multidisciplinary Sci MIIT Key Lab Complex Field Intelligent Sensing Beijing 100081 Peoples R China

Optically-pumped magnetometer (OPM) has been of increasing interest for biomagnetic measurements due to its low cost and portability compared with superconducting quantum interference devices (SQUID). Miniaturized spin-exchange-relaxation-free (SERF) OPMs typically have limited bandwidth (less than a few hundred Hertz), making it difficult to measure high-frequency biomagnetic signals such as the magnetocardiography (MCG) signal of the mouse. Existing experiments mainly use SQUID systems to measure the signal. In this paper, we introduce a prototype miniaturized single-beam SERF magnetometer with a bandwidth of 1 kHz. Instead of operating the OPM in a closed-loop mode to improve the bandwidth of the OPM, which usually has a poorer performance in high-frequency range, we use the power-broadening effects to shorten the spin relaxation time and thus a faster response to the magnetic fields to be measured. Combined with light power stabilizations to improve both the sensitivity and stability, our magnetometer has a low noise floor of 30 fT / Hz1/2, which has been successfully adopted to measure the MCG signal of the mouse. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Laser light Magnetometry Optical fibers Precision metrology Spatial resolution Vertical cavity surface emitting lasers

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Gain-bandwidth-product-induced technical bound in time transfer system without inline amplifiers

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JOURNAL OF APPLIED PHYSICS 2025年第16期137卷

作者： Zhang, Yufei Chen, Ziyang Guo, Hong Peking Univ Sch Elect State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China Peking Univ Ctr Quantum Informat Technol Beijing 100871 Peoples R China

Time transfer plays a dispensable role in many fields including navigation and positioning, geodesy, and fundamental tests. However, in certain scenarios where effective relay node deployment is often not feasible, such as harsh environments with extremely poor infrastructure and emergency conditions, effective time transfer without inline amplifiers becomes crucial. In this situation, the maximum transmission distance is limited by the receiver's measurement capability, particularly its ability to amplify the signal. Here, we propose a theoretical model, giving a technical lower bound of the detected signal stability at different transmission distances, induced by limited gain-bandwidth products. The results under common gain-bandwidth products show that while for shorter transmission distances, stability is mainly limited by the background noise of the time interval counter, for longer distances reaching the scale of 300 km, the technical lower bound is below the level of 10 ns without any inline amplification devices. Therefore, the given technical bound offers guidance on managing the balance between distance and stability, together with the optimization of the receiver in long-distance time transfer without inline amplification.

关键词： Geodesy

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Hundred-femtosecond-level concise optical time delay measurement system based on linear optical sampling

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REVIEW OF SCIENTIFIC INSTRUMENTS 2023年第8期94卷 1-7页

作者： Zhang, Yufei Chen, Ziyang Yu, Dongrui Niu, Jialin Chen, Xing Guo, Hong Peking Univ Sch Elect State Key Lab Adv Opt Commun Syst Beijing 100871 Peoples R China Peking Univ Ctr Quantum Informat Technol Beijing 100871 Peoples R China Beijing Univ Posts & Telecommun State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China

Fiber-delay measurement is one of the key fundamental technologies in numerous fields. Here, we propose and experimentally demonstrate a high-precision and concise optical time delay measurement system based on the technique of linear optical sampling, reaching the precision better than 100 fs under averaging. The use of only two optical frequency combs without locking the carrier-envelope-offset frequency greatly simplifies the structure of the time-delay measurement system. We also experimentally investigate the current limitations on the precision of the system. The timing jitter noises of two sources are mainly non-common mode and are both restricted to the frequency sources. Our results indicate that the proposed device can measure fiber length fluctuations below 10 mu m, paving the way for further analyses of the external disturbances on the fiber link.

关键词： Timing circuits

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Surface modification of chitin nanocrystals using conducting polymer for triboelectric nanogenerator

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NANO ENERGY 2025年 135卷

作者： Ma, Chuangchi He, Yunqing Zeng, Luying Liu, Mingxian Jinan Univ Coll Chem & Mat Sci Dept Mat Sci & Engn Guangzhou 511443 Peoples R China Jinan Univ Guangdong Prov Key Lab Speed Capabil Res Guangzhou 510632 Peoples R China

Single-electrode triboelectric nanogenerators (TENG) attracted much attentions due to their simplified structure, high energy conversion efficiency, flexible adaptability and wide application potential. Herein, a multifunctional, flexible and highly responsive single-electrode TENG was fabricated by grafting of conducting polypyrrole (PPy) onto the surface of chitin nanocrystals (ChNCs). ChNCs effectively improved the dispersibility of PPy in aqueous solution, thereby improving the electrochemical performance of the suspension. A single-electrode triboelectric nanogenerator (PC-TENG) was fabricated using PPy@ChNCs suspension as the electrode material and polydimethylsilane (PDMS) as the encapsulation material and friction layer. The solid-liquid double layer between the PDMS and the liquid electrode is conducive to output higher triboelectric performance. When the ratio of ChNCs to PPy was 1:2, PC-TENG has a maximum output voltage of approximately 65 V, output current of approximately 8.6 mu A, and a transferred charge of about 38 nC. The power density of PC-TENG can reach 353 mW/m2 with fast responsiveness and stable output performance after 1000 cycles. PC-TENG can realize human motion monitoring and tactile perception with a self-powered system. This work adopted biologically derived ChNCs to improve the dispersibility and conductivity of PPy, and the obtained PC-TENG exhibits promising application in wearable energy harvesting technology.

关键词： Chitin nanocrystals Polypyrrole Single-electrode triboelectric nanogenerator Liquid electrode Wearable devices

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Adhesive thermosensitive polydopamine hydrogel containing Mn3O4 anchored halloysite clay for treatment of ulcerative colitis

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2025年第Pt 1期683卷 147-159页

作者： Zhang, Di Chen, Xiangyu Feng, Yue Li, Lihua Liu, Mingxian Jinan Univ Coll Chem & Mat Sci Dept Mat Sci & Engn Guangzhou 511443 Peoples R China

Ulcerative colitis (UC), a common inflammatory bowel disease, causes ulcers of the colon and rectum. One of the important reasons for intestinal lesions caused by UC is that immune cells produce large amounts of reactive oxygen species (ROS). Herein, we developed an adhesive thermosensitive polydopamine hydrogel containing Mn3O4 nanozyme anchored halloysite nanotubes (Mn3O4@HNTs@PDA) to remove ROS produced by immune cells and treatment of UC. Halloysite nanotubes (HNTs) were used as support for the synthesis of Mn3O4 nanoparticles (similar to 10 nm diameter), which decreased the nanozyme size and increased the catalysis activity. Mn3O4@HNTs can simultaneously remove H2O2 and ot>OH through the mutual reaction conversion between SOD-like and CAT-like enzymes. The PDA coating enables Mn3O4@HNTs to adhere well to the damaged mucosa of the inflamed colon, as an artificial mucosal barrier inhibits local oxidative stress. In the dextran sulfate sodium (DSS)-induced UC mouse model, Mn3O4@HNTs@PDA hydrogel effectively transformed the local inflammatory microenvironment and restored intestinal barrier function by scavenging ROS through enzyme-like action, promoting the expression of intestinal mucosal junction proteins. Overall, this study provided a new dosing method to remove ROS by tissue adhesive hydrogel containing nanozyme modified clay mineral, which shows promising applications in clinic gastroenteritis treatment.

关键词： Halloysite Nanozyme Ulcerative colitis Oxidative stress Adhesive hydrogel

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Orally administered hydrogel containing polyphenol@halloysite clay for probiotic delivery and treatment of inflammatory bowel disease

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NANO TODAY 2025年 62卷

作者： Chen, Xiangyu Feng, Yue Zhang, Di Zhou, Shuiqing Liu, Xinshuo Luo, Binghong Zhou, Changren Liu, Mingxian Jinan Univ Coll Chem & Mat Sci Dept Mat Sci & Engn Guangzhou 511443 Peoples R China Minist Educ Engn Res Ctr Artificial Organs & Mat Guangzhou 510632 Peoples R China

Oral medication treatment for inflammatory bowel disease (IBD) is often hindered by challenges such as low drug accumulation rates, limited penetration of mucus barriers, and suboptimal therapeutic efficacy. Here, we engineer a probiotic delivery platform (denominated as MHBSA) based on halloysite clay nanotubes (HNTs) to eliminate reactive oxygen species (ROS) and modulate the dysregulated gut microbiota for targeted treatment of IBD. HNTs are functionalized with the excellent adhesion activity and metal coordination ability of epigallocatechin gallate (MPN@HNTs), which are then incorporated into alginate microspheres to load probiotics. The alginate microspheres exhibit controlled release responsive to the intestinal microenvironment. MPN@HNTs is targeted to the inflamed colon sites through electrostatic interactions, and the rod-like microstructure of HNTs prolongs its retention time on the mucosa and enhances accumulation. MPN@HNTs not only reduces aberrantly activated immune responses by eliminating ROS but also improves the resistance of probiotics to oxidative stress. Surprisingly, upon oral administration, MHBSA modulates the gut microbiota, including restoring diversity and enhancing the abundance of short-chain fatty acid-related bacteria. Overall, the pH-responsive oral formulation containing medicinal clay and probiotics is a promising approach for IBD treatment.

关键词： Inflammatory bowel disease Metal polyphenol network Halloysite Reactive oxygen species Gut microbiota

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Tea nanoparticles modified halloysite clay coated polyurethane sponge as multifunctional sensors

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APPLIED CLAY SCIENCE 2024年 262卷

作者： Tian, Kairui Chen, Xiangyu Zhou, Xinyuan Xu, Yuqian Liu, Mingxian Jinan Univ Coll Chem & Mat Sci Dept Mat Sci & Engn Guangzhou 511443 Peoples R China

Tea, as one of the three major beverages in the world, has antioxidant, anti-cancer, inhibitory inflammation, immune regulation, diabetes prevention, antibacterial and other effects. In this study, black tea and FeCl3 & sdot;6H2O were chelated to functionally modify the outer surface of halloysite clay nanotube (Hal). A new nanomaterial with excellent photothermal properties, tea nanoparticles@Hal, was successfully synthesized. Tea nanoparticles@Hal powder can raise to 225.8 degrees C in 25 s, and the corresponding solution can raise to 50.5 degrees C in 8 min with a photothermal efficiency of 77.3 %. The tea nanoparticles@Hal was assembled on the polyurethane (PU) sponges by simply soaking to prepare conductive sensor. The flexible sensor shows a fast response time (132.8 ms) and a long service time (400 cycles), which have wide range of applications. The resistance changes with the pressure is in a regular functional relationship, and the sensor can measure the weight of objects with high accuracy. In addition, the sensor can stably monitor various physiological activities of the human body. When finger is bent, the sensor can produce the difference output signals. The prepared tea nanoparticles@Hal/PU sensor has broad prospects in fields such as human-computer interaction and medical detection.

关键词： Tea Halloysite Complexation Photothermal Sensor

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Compact 780 nm Rb Optical Frequency Standard on "Optical Cubes"

Compact 780 nm Rb Optical Frequency Standard on "Optical Cub...

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2024 IEEE Ultrasonics, Ferroelectrics, and Frequency Control Joint Symposium

作者： Yang, Qiaohui Liu, Tianyu Lian, Jiqing Zhu, Chuanwen Miao, Jie Chen, Zhendong Chen, Jingmin Pan, Duo Chen, Jingbiao Peking Univ Sch Elect Beijing 100871 Peoples R China Lanzhou Inst Phys Sci & Technol Vacuum Technol & Phys Lab Lanzhou Peoples R China Xidian Univ Sch Mechanoelect Engn Xian Peoples R China Hefei Natl Lab Hefei 230000 Peoples R China

ISBN: (纸本)9798350371918;9798350371901

Atomic clock is currently the highest precision time frequency standard device, which is widely used in communication, positioning, navigation and other advanced fields. However, optical frequency standards often face problems such as huge volume, complex system and high cost, which greatly limit their application scenarios. Here we report a compact 780 nm Rb optical frequency standard on "optical cubes", which can greatly reduce the volume and maintain high stability. Profit from the robust architecture of "optical cubes", the physical volume of the optical frequency standard can be greatly reduced to 140 mm*140 mm*100 mm, which based on modulation transfer spectroscopy. The "optical cubes" are a concept that all optical components can be mounted on universal glass cubes. At present, the compact optical frequency standard's frequency instability reached short-term stability of 7.2E-13@1s.

关键词： optical frequency standard chip-scale optical clock optical clock modulation transfer spectroscopy

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Dispersed-laminated structure enabled the practical ultrathin lithium anode

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JOURNAL OF POWER SOURCES 2025年 635卷

作者： Liao, Jiahua Huang, Shaozhen Wang, An Zhu, Antai Guo, Caili Huang, Haifeng Wu, Zhibin Li, Wenhao Li, Chengchao Chen, Libao Cent South Univ State Key Lab Powder Met Changsha 410083 Peoples R China Foshan Lifriend New Energy Co Ltd Foshan 528244 Peoples R China

Lithium metal as an ideal anode with high theoretical capacity and low redox potential, faces hurdles in commercialization due to volume instability and dendrite growth during cycling. Herein, we present a threedimensional composite Li anode (Li@CNT) with a dispersed-laminated skeleton structure, which fabricated by mechanical rolling repeatedly of conductive carbon nanotube (CNT) films and Li strips. The uniform distribution of LiC12 and the cross-linked CNT enhance the uniformity of the electric field, inhibiting the formation of deep stripping pores and promoting radial deposition, which in turn mitigates volume changes and inhibits dendrite growth. The as-prepared Li@CNT anode achieves 99.7 % Coulombic efficiency and 3000-h lifespan at 1 mA cm- 2 and 1 mAh cm- 2. Furthermore, Li@CNT exhibits higher tensile strength (reached 11.3 MPa), which is beneficial for preparing the ultrathin Li strips. The ultrathin Li@CNT||LiFeO4 full cell exhibits 94.7 % capacity after 200 cycles. This work paves the way for the efficient manufacture of high-performance Li anodes for practical applications.

关键词： Lithium metal anode Dispersed-laminated skeleton Ultra-thin processing Rolling

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A Versatile Triboelectric Nanogenerator Using a Flexible Poly(vinyl alcohol)/Polyethylene Glycol/Chinese Ink Hydrogel

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ACS APPLIED POLYMER MATERIALS 2024年第1期7卷 124-136页

作者： Wu, Feng Xu, Yuqian Ma, Chuangchi Huang, Jiawei He, Yunqing Liu, Mingxian Jinan Univ Coll Chem & Mat Sci Dept Mat Sci & Engn Guangzhou 511443 Peoples R China Jinan Univ Guangdong Prov Key Lab Speed Capabil Res Guangzhou 510632 Peoples R China

Stretchable conductive hydrogels exhibit promising potential as portable electronic devices and strain sensors. However, they suffer from intricate preparation procedures and inadequate mechanical properties for constructing triboelectric nanogenerators (TENGs). Herein, we propose a borax-cross-linked poly(vinyl alcohol) (PVA)/polyethylene glycol (PEG)/Chinese ink (C) carbon nanoparticle composite hydrogel, which boasts a simple fabrication method and environmental friendliness. The dispersion of carbon nanoparticles throughout the polymer network bolsters the mechanical strength of the hydrogel and also imparts good electrical conductivity. The incorporation of PEG improves the mechanical properties of the hydrogel, while the dynamic bonding between borate ions and PVA confers excellent self-recovery properties. Upon cutting and reuniting the fractured surfaces for 30 s, the two segments of the hydrogel underwent spontaneous healing without external stimuli. The mended incisions of the hydrogel nearly vanished and withstood stretching to three times their original length without fracturing, showing a remarkable self-healing capability and stretchability. Finally, TENGs were prepared using the PVA/PEG/C hydrogel, and the output voltage was approximately 2.9 V across all frequencies. The PVA/PEG/C-TENG demonstrated a rapid response at 180 degrees of bending, reacting to the stimulation in a mere 0.256 s and returning to its original state within 0.511 s after the stimulus was removed. The PVA/PEG/C hydrogel shows versatility in applications such as wearable motion monitoring, precise stroke recognition, and efficient mechanical energy harvesting.

关键词： Chinese ink composite hydrogel triboelectricnanogenerator motion monitoring mechanical energyharvesting

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