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Performance of pulsed plasma thruster at low discharge energy

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Plasma Science and Technology 2024年第4期26卷 122-132页

作者：李鸿俊林泽豪胡浩俊吴文东陈爱虹杜德扬 Department of Physics Faculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Faculty of Engineering The University of Nottingham Malaysia CampusSemenyih 43500Malaysia Faculty of Engineering Multimedia UniversityCyberjaya 63100Malaysia

As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5-2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy ≥2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.

关键词： pulsed plasma thruster low discharge energy performance parameters

A flexible capacitive photoreceptor for the biomimetic retina

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Light(Science & Applications) 2022年第1期11卷 38-49页

作者： Mani Teja Vijjapu Mohammed E.Fouda Agamyrat Agambayev chun Hong Kang chun-Ho Lin boon S.Ooi Jr-Hau He Ahmed M.Eltawil Khaled N.Salama Sensors lab Advanced Membranes and Porous Materials CenterComputerElectrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Communication and Computing Systems Lab ComputerElectrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Electrical Engineering and Computer Science University of California-IrvineIrvineCA 92612USA Department of Electrical Computer and Energy EngineeringArizona State UniversityTempeAZUSA Computer Electrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Materials Science and Engineering City University of Hong KongHong Kong SARChina

Neuromorphic vision sensors have been extremely beneficial in developing energy-efficient intelligent systems for robotics and privacy-preserving security applications.There is a dire need for devices to mimic the retina's photoreceptors that encode the light illumination into a sequence of spikes to develop such sensors.Herein,we develop a hybrid perovskite-based flexible photoreceptor whose capacitance changes proportionally to the light intensity mimicking the retina's rod cells,paving the way for developing an efficient artificial retina network.The proposed device constitutes a hybrid nanocomposite of perovskites(methyl-ammonium lead bromide)and the ferroelectric terpolymer(polyvinylidene fluoride trifluoroethylene-chlorofluoroethylene).A metal-insulator-metal type capacitor with the prepared composite exhibits the unique and photosensitive capacitive behavior at various light intensities in the visible light spectrum.The proposed photoreceptor mimics the spectral sensitivity curve of human photopic vision.The hybrid nanocomposite is stable in ambient air for 129 weeks,with no observable degradation of the composite due to the encapsulation of hybrid perovskites in the hydrophobic polymer.The functionality of the proposed photoreceptor to recognize handwritten digits(MNIST)dataset using an unsupervised trained spiking neural network with 72.05%recognition accuracy is demonstrated.This demonstration proves the potential of the proposed sensor for neuromorphic vision applications.

关键词： perovskite illumination preserving

Polarization-induced photocurrent switching effect in heterojunction photodiodes

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Nano Research 2023年第4期16卷 5503-5510页

作者： Dingbo Chen Yu-Chang Chen Guang Zeng Yu-chun Li Xiao-Xi Li Dong Li Chao Shen Nan Chi boon S.Ooi David Wei Zhang Hong-Liang Lu State Key Laboratory of ASIC and System Shanghai Institute of Intelligent Electronics&SystemsSchool of MicroelectronicsFudan UniversityShanghai 200433China Key Laboratory for Information Science of Electromagnetic Waves Department of Communication Science and EngineeringFudan UniversityShanghai 200433China Photonics Laboratory Division of ComputerElectricaland Mathematical Sciences and EngineeringKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia

The unipolar photocurrent in conventional photodiodes(PDs)based on photovoltaic effect limits the output modes and potential versatility of these devices in photodetection.Bipolar photodiodes with photocurrent switching are emerging as a promising solution for obtaining photoelectric devices with unique and attractive functions,such as optical logic operation.Here,we design an all-solid-state chip-scale ultraviolet(UV)PD based on a hybrid GaN heterojunction with engineered bipolar polarized electric field.By introducing the polarization-induced photocurrent switching effect,the photocurrent direction can be switched in response to the wavelength of incident light at 0 V bias.In particular,the photocurrent direction exhibits negative when the irradiation wavelength is less than 315 nm,but positive when the wavelength is longer than 315 nm.The device shows a responsivity of up to−6.7 mA/W at 300 nm and 5.3 mA/W at 340 nm,respectively.In particular,three special logic gates in response to different dual UV light inputs are demonstrated via a single bipolar PD,which may be beneficial for future multifunctional UV photonic integrated devices and systems.

关键词： GaN heterostructure ultraviolet(UV)photodiodes bipolar photocurrent optical logic device

Site-directed deuteration of dronedarone preserves cytochrome P4502J2 activity and mitigates its cardiac adverse effects in canine arrhythmic hearts

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Acta Pharmaceutica Sinica B 2022年第10期12卷 3905-3923页

作者： Aneesh V.Karkhanis Gopalakrishnan Venkatesan Ryuichi Kambayashi Jacqueline Wen Hui Leow Marcus Qingrui Han Hiroko Izumi-Nakaseko Ai Goto Jeremy Kah Sheng Pang boon Seng Soh Pipin Kojodjojo Atsushi Sugiyama Eric chun Yong Chan Department of Pharmacy Faculty of ScienceNational University of SingaporeSingapore 117543Singapore Department of Pharmacology Faculty of MedicineToho UniversityTokyo 143-8540Japan Institute of Molecular and Cell Biology Agency for ScienceTechnology and ResearchSingapore 138673Singapore Department of Biological Sciences Faculty of ScienceNational University of SingaporeSingapore 117558Singapore Department of Medicine Yong Loo Lin School of MedicineNational University of SingaporeSingapore 119228Singapore

Cytochrome P4502J2(CYP2J2)metabolizes arachidonic acid(AA)to cardioprotective epoxyeicosatrienoic acids(EETs).Dronedarone,an antiarrhythmic drug prescribed for treatment of atrial fibrillation(AF)induces cardiac adverse effects(AEs)with poorly understood mechanisms.We previously demonstrated that dronedarone inactivates CYP2J2 potently and irreversibly,disrupts AA-EET pathway leading to cardiac mitochondrial toxicity rescuable via EET enrichment.In this study,we investigated if mitigation of CYP2J2 inhibition prevents dronedarone-induced cardiac AEs.We first synthesized a deuterated analogue of dronedarone(termed poyendarone)and demonstrated that it neither inactivates CYP2J2,disrupts AA-EETs metabolism nor causes cardiac mitochondrial toxicity in vitro.Our patch-clamp experiments demonstrated that pharmacoelectrophysiology of dronedarone is unaffected by deuteration.Next,we show that dronedarone treatment or CYP2J2 knockdown in spontaneously beating cardiomyocytes indicative of depleted CYP2J2 activity exacerbates beat-to-beat(BTB)variability reflective of proarrhythmic phenotype.In contrast,poyendarone treatment yields significantly lower BTB variability compared to dronedarone in cardiomyocytes indicative of preserved CYP2J2 activity.Importantly,poyendarone and dronedarone display similar antiarrhythmic properties in the canine model of persistent AF,while poyendarone substantially reduces beat-to-beat variability of repolarization duration suggestive of diminished proarrhythmic risk.Our findings prove that deuteration of dronedarone prevents CYP2J2 inactivation and mitigates dronedarone-induced cardiac AEs.

关键词： Arachidonic acid Atrial fibrillation CYP2J2 Drug-induced proarrhythmia Epoxyeicosatrienoic acids Mechanism-based inactivation Dronedarone

Effects of primary glaucoma on sleep quality and daytime sleepiness of patients residing at an equatorial latitude

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International Journal of Ophthalmology(English edition) 2020年第9期13卷 1451-1458页

作者： Jacob YH Chin Zhi Hong Toh Ying Tai Lo Hannah TY Wang Elizabeth YW Poh chun Hau Chua Owen Kim Hee boon Ang Lim Vernon KY Yong Augustinus Laude Hon Tym Wong Leonard WL Yip Department of Ophthalmology National Healthcare Group Eye InstituteTan Tock Seng Hospital308433Singapore Monash School of Medicine Monash UniversityVictoria 3800Australia

AIM:To investigate the impact of primary glaucoma on sleep quality and daytime sleepiness of patients.METHODS:Prospective cross-sectional study with consecutive sampling in South-East Asian population was performed.Validated questionnaires:the Pittsburg Sleep Quality Index(PSQI)and Epworth Sleepiness Scale(ESS)were administered prospectively.Subjects with nonglaucomatous optic neuropathy or concomitant retinal pathology were excluded.Glaucoma severity was based on HVF 24-2 perimetry.Binocular single vision was represented based on the better eye.Frequency of and predictive factors for poor sleep quality and excessive daytime sleepiness were compared.RESULTS:A total of 79 primary open angle glaucoma(POAG),27 primary angle-closure glaucoma(PACG)patients,and 89 controls were recruited.PACG patients had higher median PSQI scores(P=0.004)and poorer sleep quality(P<0.001).Compared to controls,PACG patients were 3.34 times more likely to have poor sleep quality(P=0.008),which remained significant after adjustment for demographics(P=0.016)and predictive variables(P=0.013).PACG patients have poorer sleep quality when visual acuity(VA)was 6/15 or worse(P=0.009).Univariate and multivariate analysis of predictive variables for poor sleep quality and daytime sleepiness did not find statistical significance.CONCLUSION:PACG patients have poorer sleep quality but not daytime sleepiness.This is important in South-East Asian population with heavy disease burden.Evaluations on sleep disturbances can be considered to provide more ho istic care.

关键词： sleep disturbances primary glaucoma intrinsically photosensitive retinal ganglion cells daytime sleepiness sleep quality South-East Asia

High-speed colour-converting photodetector with all-inorganic CsPbBr_(3) perovskite nanocrystals for ultraviolet light communication

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Light(Science & Applications) 2019年第1期8卷 306-317页

作者： chun Hong Kang Ibrahim Dursun Guangyu Liu Lutfan Sinatra Xiaobin Sun Meiwei Kong Jun Pan Partha Maity Ee-Ning Ooi Tien Khee Ng Omar F.Mohammed Osman M.Bakr boon S.Ooi Photonics Laboratory Division of ComputerElectricaland Mathematical Sciences and EngineeringKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Division of Physical Science and Engineering King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Quantum Solutions LLC Thuwal 23955-6900Kingdom of Saudi Arabia

Optical wireless communication(OWC)using the ultra-broad spectrum of the visible-to-ultraviolet(UV)wavelength region remains a vital field of research for mitigating the saturated bandwidth of radio-frequency(RF)communication.However,the lack of an efficient UV photodetection methodology hinders the development of UV-based communication.The key technological impediment is related to the low UV-photon absorption in existing silicon photodetectors,which offer low-cost and mature platforms.To address this technology gap,we report a hybrid Sibased photodetection scheme by incorporating CsPbBr_(3) perovskite nanocrystals(NCs)with a high photoluminescence quantum yield(PLQY)and a fast photoluminescence(PL)decay time as a UV-to-visible colourconverting layer for high-speed solar-blind UV communication.The facile formation of drop-cast CsPbBr_(3) perovskite NCs leads to a high PLQY of up to ~73% and strong absorption in the UV region.With the addition of the NC layer,a nearly threefold improvement in the responsivity and an increase of ~25% in the external quantum efficiency(EQE)of the solar-blind region compared to a commercial silicon-based photodetector were observed.Moreover,timeresolved photoluminescence measurements demonstrated a decay time of 4.5 ns under a 372-nm UV excitation source,thus elucidating the potential of this layer as a fast colour-converting layer.A high data rate of up to 34 Mbps in solar-blind communication was achieved using the hybrid CsPbBr_(3)-silicon photodetection scheme in conjunction with a 278-nm UVC light-emitting diode(LED).These findings demonstrate the feasibility of an integrated high-speed photoreceiver design of a composition-tuneable perovskite-based phosphor and a low-cost silicon-based photodetector for UV communication.

关键词： perovskite ultraviolet inorganic

Large-scale and high-quality Ⅲ-nitride membranes through microcavity-assisted crack propagation by engineering tensile-stressed Ni layers

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Opto-Electronic Science 2022年第10期 45-55页

作者： Jung-Hong Min Kwangjae Lee Tae-Hoon chung Jung-Wook Min Kuang-Hui Li chun Hong Kang Hoe-Min Kwak Tae-Hyeon Kim Youyou Yuan Kyoung-Kook Kim Dong-Seon Lee Tien Khee Ng boon S.Ooi Photonics Laboratory Computer Electrical and Mathematical Sciences and Engineering Division (CEMSE) King Abdullah University of Science and Technology (KAUST) Department of Electrical Engineering Stanford University Light Source Research Division Korea Photonics Technology Institute (KOPTI) School of Electrical Engineering and Computer Science Gwangju Institute of Science and Technology Department of Advanced Convergence Technology Research Institute of Advanced Convergence Technology Korea Polytechnic University King Abdullah University of Science and Technology (KAUST)

Epitaxially grown Ⅲ-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds. This tight bonding presents tremendous challenges in developing Ⅲ-nitride membranes, even though semiconductor membranes can provide numerous advantages by removing thick, inflexible, and costly substrates. Herein, cavities with various sizes were introduced by overgrowing target layers, such as undoped GaN and green LEDs, on nanoporous templates prepared by electrochemical etching of n-type GaN. The large primary interfacial toughness was effectively reduced according to the design of the cavity density, and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers. The resulting Ⅲ-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant. The microcavity-assisted crack propagation process developed for the current Ⅲ-nitride membranes forms a universal process for developing various kinds of largescale and high-quality semiconductor membranes.

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Deep-ultraviolet integrated photonic and optoelectronic devices:A prospect of the hybridization of group Ⅲ–nitrides, Ⅲ–oxides,and two-dimensional materials

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Journal of Semiconductors 2019年第12期40卷 11-58页

作者： Nasir Alfaraj Jung-Wook Min chun Hong Kang Abdullah A.Alatawi Davide Priante Ram Chandra Subedi Malleswararao Tangi Tien Khee Ng boon S.Ooi Photonics Laboratory Computer Electrical and Mathematical Sciences and Engineering Division (CEMSE) King Abdullah University of Science and Technology (KAUST)

Progress in the design and fabrication of ultraviolet and deep-ultraviolet groupⅢ–nitride optoelectronic devices,based on aluminum gallium nitride and boron nitride and their alloys,and the heterogeneous integration with two-dimensional and oxide-based materials is reviewed.We emphasize wide-bandgap nitride compound semiconductors(i.e.,(B,Al,Ga)N)as the deep-ultraviolet materials of interest,and two-dimensional materials,namely graphene,two-dimensional boron nitride,and two-dimensional transition metal dichalcogenides,along with gallium oxide,as the hybrid integrated materials.We examine their crystallographic properties and elaborate on the challenges that hinder the realization of efficient and reliable ultraviolet and deep-ultraviolet devices.In this article we provide an overview of aluminum nitride,sapphire,and gallium oxide as platforms for deep-ultraviolet optoelectronic devices,in which we criticize the status of sapphire as a platform for efficient deep-ultraviolet devices and detail advancements in device growth and fabrication on aluminum nitride and gallium oxide substrates.A critical review of the current status of deep-ultraviolet light emission and detection materials and devices is provided.

关键词： deep-ultraviolet ultraviolet photonics optoelectronics hybrid

Large-scale and high-quality III-nitride membranes through microcavity-assisted crack propagation by engineering tensile-stressed Ni layers

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Opto-Electronic Science 2022年第10期1卷 51-61,42-50页

作者： Jung-Hong Min Kwangjae Lee Tae-Hoon chung Jung-Wook Min Kuang-Hui Li chun Hong Kang Hoe-Min Kwak Tae-Hyeon Kim Youyou Yuan Kyoung-Kook Kim Dong-Seon Lee Tien Khee Ng boon S.Ooi Photonics Laboratory ComputerElectrical and Mathematical Sciences and Engineering Division(CEMSE)King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia Department of Electrical Engineering Stanford UniversityStanfordCA 94305USA Light Source Research Division Korea Photonics Technology Institute(KOPTI)Gwangju 61007Republic of Korea School of Electrical Engineering and Computer Science Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Department of Advanced Convergence Technology Research Institute of Advanced Convergence TechnologyKorea Polytechnic University237 Sangidaehak-roSiheung-si 15073Republic of Korea King Abdullah University of Science and Technology(KAUST) Thuwal 23955-6900Saudi Arabia

Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.

关键词： III-nitride alloys membranes nanoporous Ni stressor light-emitting diodes ultraviolet photodetectors