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Tunable electron and phonon properties of folded single-layer molybdenum disulfide

Nano Research 2018年第3期11卷 1541-1553页

作者： Jie Peng peter w. chung Madan Dubey Raju R. Namburu Department of Mechanical Engineering University of Maryland College Park MD 20742 USA Sensors & Electron Devices Directorate U.S. Army Research Laboratory Adelphi MD 20783 USA Computational & Information Sciences Directorate U.S. Army Research Laboratory Aberdeen Proving Ground MD 21005 USA

A unique feature of transition metal dichalcogenides is their single-layer form, w.ich enables folding. Although folding has been found to significantly affect the photoluminescence spectrum and some in-plane properties, only limited insight has been gained on how.to modulate those properties. In this report, w. examine the structure of folds of a single sheet of MoS2 and the dependence of the ground-s tate electronic and phonon transport properties on the w.apping length. As the folded structure is effectively a bilayer that terminates in a loop, the w.apping length modulates the relative size of the bilayer region to the closed loop along the edge. A combination of computational methods, including approaches based on variational mechanics, classical potentials, and density functional theory, are employed. Highly accurate calculations of the reference folded structure are first carried out to show.that the folded structure is largely insensitive to the w.apping length. The folded structures are subsequently used to estimate the electronic band gap, w.ich is found to vary significantly as a function of the w.apping length, and converges from below.to the limit value corresponding to an infinite bilayer. The gap values range from 0.43 to 1.09 eV, w.th a crossover to an indirect gap, w.ich suggests that the transitions must be lattice-assisted, similar to the transitions in the bilayer and bulk forms. How.ver, the phonons, w.ile affected by the formation of the folded structure, are insensitive to the w.apping length. In fact, the overall thermal transport behavior along the folding axis is unchanged. The possibility of modulating the gap value w.ile keeping the thermal properties unchanged opens up new.exciting avenues for further applications of this emerging material.

关键词： molybdenum disulfide folded structure electronic band structure thermal conductivity phonon

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BIOSYNTHESIS AND THERMAL PROPERTIES OF POLY(3-HYDROXYBUTYRATE-co-3-HYDROXYVALERATE)w.TH LARGE VARIETY OF HYDROXYVALERATE CONTENTS BY BACILLUS CEREUS

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Chinese Journal of Polymer Science 2007年第4期25卷 341-345页

作者：严群 chung HimYu peter Hoi Fu Yu Key Laboratory of Industrial Biotechnology Ministry of EducationSouthern Yangtze University Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong

Biosynthesis and thermal properties of poly（3-hydroxybutyrate-co-3-hydroxyvalerate）（PHBV） w.th different HV （hydrovalerate） content produced by a Bacillus cereus strain w.re investigated. A large variety of HV contents （up to about 90 mol%） of PHBV could be produced by this strain. Combined nitrogen sources containing both yeast extract and ammonium sulphate w.re better for cell grow.h and polyhydroxyalkanoates （PHA） production than either yeast extract or ammonium sulphate alone. Propionic acid is more favorable for the production of HV content than that of valeric acid. Finally, thermal properties of PHBV produced by this strain are found close to the results of other groups.

关键词： Bacillus cereus Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biosynthesis Thermal properties

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Significant Lifetime Enhancement in QLEDs by Reducing Interfacial Charge Accumulation via Fluorine Incorporation in the ZnO Electron Transport Layer

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Nano-Micro Letters 2022年第12期14卷 432-446页

作者： Dong Seob chung Tyler Davidson-Hall Giovanni Cotella Quan Lyu peter Chun Hany Aziz Department of Electrical and Computer Engineering Waterloo Institute for NanotechnologyUniversity of Waterloo200 University Avenue WestWaterlooON N2L 3G1Canada Ipsw.ch Research Centre Huawei Technologies Research&Development(UK)Ltd.Phoenix House(B55)Adastral ParkIpswich IP53REUK Ottaw. IC Laboratory Huawei Canada19 Allstate ParkwayMarkhamON L3R 5B4Canada

ZnO nanoparticles are w.dely used for the electron transport layers(ETLs)of quantum dots light emitting devices(QLEDs).In this w.rk w. show.that incorporating fluorine(F)into the ZnO ETL results in significant enhancement in device electroluminescence stability,leading to LT50 at 100 cd m^(−2) of 2,370,000 h in red QLED,47X longer than the control devices.X-ray photo-electron spectroscopy,time-of-flight secondary ion mass spectroscopy,photoluminescence and electrical measurements show.that the F passivates oxygen vacancies and reduces electron traps in *** photoluminescence versus bias measurements and capacitance-voltage-luminance measurements reveal that the CF4 plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface,subsequently decreasing hole accumulation,and hence the higher *** findings provide new.insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.

关键词： Colloidal quantum dots Quantum dots light emitting device Device stability Zinc oxide nanoparticles Fluorine

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Pretreatment w.th Rhodiola Rosea Extract Reduces Cognitive Impairment Induced by Intracerebroventricular Streptozotocin in Rats: Implication of Anti-oxidative and Neuroprotective Effects

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Biomedical and Environmental Sciences 2009年第4期22卷 318-326页

作者： peter chung Division of Neuroscience Department of Histology and Embryology Zhongshan School of Medicine Sun Yat-Sen University

Objective To investigate the pretreatment effects of Rhodiola rosea （R. rosea） extract on cognitive dysfunction, oxidative stress in hippocampus and hippocampal neuron injury in a rat model of Alzheimer＇s disease （AD）. Methods Male Sprague-Daw.ey rats w.re pretreated w.th R. rosea extract at doses of 1.5, 3.0, and 6.0 g/kg for 3 w.eks, follow.d by bilateral intracerebroventricular injection w.th streptozotocin （1.5 mg/kg） on days 1 and 3. Behavioral alterations w.re monitored after 2 w.eks from the lesion using Morris w.ter maze task. Three w.eks after the lesion, the rats w.re sacrificed for measuring the malondialdehyde （MDA）, glutathione reductase （GR） and reduced glutathione （GSH） levels in hippocampus and histopathology of hippocampal neurons. Results The MDA level w.s significantly increased w.ile the GR and GSH levels w.re significantly decreased w.th striking impairments in spatial learning and memory and severe damage to hippocampal neurons in the model rat induced by intracerebroventricular injection of streptozotocin. These abnormalities w.re significantly improved by pretreatment w.th R. rosea extract （3.0 g/kg）. Conclusion R. rosea extract can protect rats against cognitive deficits, neuronal injury and oxidative stress induced by intracerebroventricular injection of streptozotocin, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD.

关键词： Rhodiola rosea Oxidative stress Neuroprotective effect Learning and memory Alzheimer's disease Intracerebroventricular streptozotocin

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Mitochondrial protective and anti-apoptotic effects of Rhodiola crenulata extract on hippocampal neurons in a rat model of Alzheimer's disease

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Neural Regeneration Research 2017年第12期12卷 2025-2034页

作者： Jun-mei w.ng Ze-qiang Qu Jin-lang w. peter chung Yuan-shan Zeng Department of Histology and Embryology Zhongshan School of Medicine Sun Yat-sen University Guangzhou Guangdong Province China Department of Electron Microscope Zhongshan School of Medicine Sun Yat-sen University Guangzhou Guangdong Province China Shanghai Ninth People's Hospital Shanghai liao Tong University School of Medicine Shanghai China Institute of Spinal Cord In)ury Sun Yat-sen University Guangzhou Guangdong Province China Co-innovation Center of Neuroregeneration Nantong University Nantong Jiangsu Province China Guangdong Province Key Laboratory of Brain Function and Disease Zhongshan School of Medicine Sun Yat-sen University Guangzhou Guangdong Province China

In our previous study, w. found that the edible alcohol extract of the root of the medicinal plant Rhodiola crenulata（RCE） improved spatial cognition in a rat model of Alzheimer＇s disease. Another study from our laboratory show.d that RCE enhanced neural cell proliferation in the dentate gyrus of the hippocampus and prevented damage to hippocampal neurons in a rat model of chronic stress-induced depression. How.ver, the mechanisms underlying the neuroprotective effects of RCE are unclear. In the present study, w. investigated the anti-apoptotic effect of RCE and its neuroprotective mechanism of action in a rat model of Alzheimer＇s disease established by intracerebroventricular injection of streptozotocin. The rats w.re pre-administered RCE at doses of 1.5, 3.0 or 6.0 g/kg for 21 days before model establishment. ATP and cytochrome c oxidase levels w.re significantly decreased in rats w.th Alzheimer＇s disease. Furthermore, neuronal injury w.s obvious in the hippocampus, w.th the presence of a large number of apoptotic neurons. In comparison, in rats given RCE pretreatment, ATP and cytochrome c oxidase levels w.re markedly increased, the number of apoptotic neurons w.s reduced, and mitochondrial injury w.s mitigated. The 3.0 g/kg dose of RCE had the optimal effect. These findings suggest that pretreatment w.th RCE prevents mitochondrial dysfunction and protects hippocampal neurons from apoptosis in rats w.th Alzheimer＇s disease.

关键词： nerve regeneration Alzheimer's disease intracerebroventricular injection streptozotocin neuronal apoptosis neuroprotection cytochrome c oxidase adenosine triphosphate caspase-3 NeuN neural regeneration

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Impact of Korean Ginseng （Panax Ginseng） on Pow.r Generation of Microbial Fuel Cells

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Journal of Chemistry and Chemical Engineering 2015年第7期9卷 448-453页

作者： w.njae Kim peter Lee Thomas w. Kim George Kim Jonathan Sukhee chung Jihw.n Alex. Joo Sung-Jae chung Fuzbien Technology Institute MD 20850 United States Collegiate School NY 10024 United States_ Department of Chemistry University of lllinois-Urbana Champaign IL 61801 United States Centreville High School VA 20124 United States Seoul International School Seoul 13113 South Korea School of Arts and Sciences Marymount University Arlington 22207 United States STEM Research Institute VA 22031 United States

This study reports an increase in pow.r generation of a MFC （microbial fuel cell） by the addition of Korean ginseng （Panax ginseng）. It w.s noted that the use of ginseng enhances the microbial anaerobic degradation of cellobiose, a disaccharide that w.s used as a substrate in the anode chamber of the MFC. The pow.r output of the MFC w.ere ginseng w.s added show.d noticeable enhancement compared to the control MFC. The increase slow.y ramped at the initial days and became appreciably higher after the 11th day of incubation in an experiment set up for 16 days duration. It is attributed that the ginseng increases the CO2 production by accelerating the fermentation process. Decrease in CH4/CO2 ratio w.s observed also due to decrease in methane production per digested cellobiose, the proton donor in the current study. Four ring steroid-like structural moiety Ginsenoside of Panax ginseng seemed to play a beneficial role in the electron transfer from ceilobiose to the anode, perhaps by rendering easier electron transfer due to favorable energy level alignments.

关键词： MFC Korean ginseng Panax anaerobic degradation.

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Bifidobacterium infantis attenuates colitis by regulating T cell subset responses

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w.rld Journal of Gastroenterology 2014年第48期20卷 18316-18329页

作者： Li Zuo Kai-Tao Yuan Li Yu Qing-Hong Meng peter Chee-Keung chung Ding-Hua Yang Department of Immunology Guiyang Medical College Department of Surgery the First AffiliatedHospital of Sun Yat-sen University Department of Paediatrics Guangzhou First Municipal People’s Hospital Department of Hepatobiliary Surgery Nan Fang Hospital Southern Medical University

AIM: to investigate the effect of Bifidobacterium infantis (B. infantis) on the T cell subsets and in attenuating the severity of experimental colitis in mice.

关键词： Bifidobacterium Colitis Cytokines Th17 Regulatory T cells

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NATURAL SUBSTANCE AND ANTI-CANCER

NATURAL SUBSTANCE AND ANTI-CANCER

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2014《中国国际肿瘤营养学论坛》暨第二届《全国肿瘤营养与支持治疗学术会议》

作者： peter chung Royal College of Surgeons(Edin)

＜正＞～～

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TAV of English Finite Verb Phrase

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Journal of Literature and Art Studies 2018年第7期8卷 1126-1130页

作者： peter Lung-shan chung University of Hong Kong Hong KongChina

It is w.dely know. that a finite verb phrase(fVP)of a clause in English consists of three components:tense,aspect and *** the tw. tenses,present and past,and the tw. voices,active and passive,are recognized and generally agreed,the number and constituents of aspects may not be so simple and they are open to *** paper proposes that a new.aspect,the“modal”aspect,be included in addition to the commonly recognized ones,namely“simple”,“perfect”and“continuous”(also know. as“progressive”).w.th the inclusion of the“modal”aspect,there are four single aspects:“simple”,“modal”,“perfect”and“continuous”.They can be combined to form multiple aspects according to the aforesaid ***“modal”aspect is realized w.th a modal verb(any ofthe modal verbs w.ll/w.uld,shall/should,can/could,may/might,must,ought to,used to and the tw. semi-modals,“need”and“dare”in interrogative and negative structures).w.enever a modal verb is used,the verb phrase is in the modal *** modal verb to be used is for the interlocutor to decide and falls beyond this discussion,w.ich focuses on the structure of the fVP of the English *** tw. tenses,eight aspects and tw. voices(active and passive)make up the 32 TAVs(an acronym formed w.th“Tense”,“Aspect”and“Voice”)of the English ***“discovery”of the“modal”aspect and its incorporation in the aspect system of English might have a significant impact on the learning of English for non-native speakers as they w.uld have a clearer and more precise concept about the“TAVs”of the English fVP.

关键词： English verb phrase finite verb phrase tense aspect mood modality modal verb TAV

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Utilization of microw.ve steam pyrolysis to produce biochar for thermal energy storage

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w.ste Disposal and Sustainable Energy 2022年第4期4卷 335-341页

作者： w.hap bin Abu Bakar peter Nai Yuh Yek Kah Yein Cheong Augustine Chioma Affam Chee chung w.ng Rock Keey Liew.Yie Hua Tan Su Shiung Lam Centre for Research of Innovation and Sustainable Development University of Technology SarawakNo.1Jalan University96000SibuMalaysia Centre on Technological Readiness and Innovation in Business Technopreneurship(CONTRIBUTE) University of Technology Sarawak96000SibuSarawakMalaysia NV w.stern PLT No.208BSecond FloorMacalister Road10400GeorgetownPenangMalaysia Department of Chemical and Energy Engineering Faculty of Engineering and ScienceCurtin University MalaysiaCDT 25098009MiriSarawakMalaysia Higher Institution Centre of Excellence(HICoE) Institute of Tropical Aquaculture and Fisheries(AKUATROP)Universiti Malaysia Terengganu21030 Kuala NerusTerengganuMalaysia

Microw.ve steam pyrolysis(MSP)is an innovative thermochemical approach to converting biomass into high-quality biochar using steam to improve the dielectric heating of microw.ve *** show. high fixed carbon and carbon contents at a maximum temperature of 550℃in 10 *** MSP achieved a heating rate of 112℃/min from 200℃to 400℃to produce biochar ***,the thermal properties of biochar in microw.ve heating w.re investigated in this study to explore its potential as a microw.ve heat-absorbent *** is able to perform volumetric and controllable heating to the ***,biochar show. good microw.ve heat absorbency,storing and transferring heat *** temperature profile of three different sizes of biochar w.s investigated to examine the efficiency of biochar in heat absorption from microw.ve *** w.s found that the pow.er form of biochar show.d a higher heat transfer rate of 40℃/min and a low.cooling rate of 7.5℃/*** presented results are useful for evaluating the application of biochar as a promising medium for heat storage systems.

关键词： Microw.ve Steam Pyrolysis Biochar Thermal Storage

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