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Particuology 2021年第2期19卷 43-47页

作者： Sisi Yang Patrick Ford Sriram Subramanian Dan Singleton Jason Sanders step.en b.cronin Department of Physics and Astronomy University of Southern CaliforniaLos AngelesCA 90089USA Ming Hsieh Department of Electrical engineering University of Southern CaliforniaLos AngelesCA 90089USA Daniel J.Epstein Department of Industrial&System engineering University of Southern CaliforniaLos AngelesCA 90089USA Transient Plasma Systems Inc.TorranceCA 90501USA

It is now recognized that nanoscale particulate matter(PM)represents a substantial health hazard for our society,including PM from restaurant *** this study,we explored the use of a transient pulsed plasma in conjunction with an applied DC bias to treat oil aerosols that closely resemble restaurant(i.e.,charbroiler)smoke *** polyaromatic olefin PAO-4 and soybean oil,we found that a three-order-of-magnitude reduction in particulates(i.e.,99.9%remediation)could be achieved with this ***,the plasma discharge was produced in a 4-in.-diameter cylindrical reactor with a 5-10 ns high voltage(30 kV)pulse generator together with applied DC bias voltages up to 10 *** distribution of nanoparticle sizes was measured using a scanning mobility particle sizer(SMPS)with diameter centered around 225 ***,the main mechanism of remediation occurs in a two-step process in which the oil nanoparticles are first ionized by the free electrons and free radicals in the plasma and then the charged particles are swept out to the sidewalls of the reactor by the applied DC *** believe this general approach opens up new degrees of freedom in the design of electrostatic oil aerosol pollution control devices.

关键词： Nanoparticles Transient plasma Charbroiler emission DC bias Remediation

broadband electroluminescence from reverse breakdown in individual suspended carbon nanotube pn-junctions

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Nano Research 2020年第10期13卷 2857-2861页

作者： bo Wang Sisi Yang Yu Wang Younghee Kim Ragib Ahsan Rehan K.apadia step.en KDoorn Han Htoon step.en b.cronin Department of Physics and Astronormy University of Southern CalforniaLos AngelesCA 90089USA Ming Hsieh Department of Electrical engineering University of Southern CaliforniaLos AngelesCA 90089USA Mork Farmily Department of Chemical engineering and Materials Science University of Southern CaliforniaLos AngelesCA 90089USA Center for Integrated Nanotechnologies Materials Physics and Applications DivisionLos Alamos National LaboratoryLos AlamosNM 87545USA

There are various mechanisms of light emission in carbon nanotubes (CNTs), which give rise to a wide range of spectral emission characteristics that provide important information regarding the underlying physical processes that lead to photon emission. Here, we report spectra obtained from individual suspended CNT dual-gate field effect transistor (FET) devices under different gate and bias conditions. by applying opposite voltages to the gate electrodes (i.e., Vg1 = –Vg2), we are able to create a pn-junction within the suspended region of the CNT. Under forward bias conditions, the spectra exhibit a peak corresponding to E11 exciton emission via thermal (i.e., blackbody) emission occurring at electrical powers around 8 μW, which corresponds to a power density of approximately 0.5 MW/cm2. On the other hand, the spectra observed under reverse bias correspond to impact ionization and avalanche emission, which occurs at electrical powers of ~ 10 nW and exhibits a featureless flat spectrum extending from 1,600 nm to shorter wavelengths up to 600 nm. Here, the hot electrons generated by the high electric fields (~ 0.5 MV/cm) are able to produce high energy photons far above the E11 (ground state) energy. It is somewhat surprising that these devices do not exhibit light emission by the annihilation of electrons and holes under forward bias, as in a light emitting diode (LED). Possible reasons for this are discussed, including Auger recombination.

关键词： ballistic avalanche high-field band-to-band photoemission

Plasmonic mode mixing in nanoparticle dimers with nm-separations via substrate-mediated coupling

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Nano Research 2014年第9期7卷 1344-1354页

作者： Jesse Theiss Mehmet Aykol Prathamesh Pavaskar step.en b. cronin Ming Hsieh Department of Electrical engineering University of Southern California Los Angeles CA 90089 USA

We fabricate arrays of metallic nanoparticle dimers with nanometer separation using electron beam lithography and angle evaporation. These ＂nanogap＂ dimers are fabricated on thin silicon nitride membranes to enable high resolution transmission electron microscope imaging of the specific nanoparticle geometries. Plasmonic resonances of the pairs are characterized by dark-field scattering micro-spectroscopy, which enables the optical scattering from individual nano- structures to be measured by using a spatially-filtered light source to illuminate a small area. Scattering spectra from individual dimers are correlated with transmis- sion electron microscope images and finite-difference time-domain simulations of their electromagnetic response, with excellent agreement between simulation and experiment. We observe a strong polarization dependence with two dominant scattering peaks in spectra taken with the polarization aligned along the dimer axis. This response arises from a unique Fano interference, in which the bright hybridized modes of an asymmetric dimer are able to couple to the dark higher- order hybridized modes through substrate-mediated coupling. The presence of this interference is strongly dependent on the nanoparticle geometry that defines the plasmon energy profile but also on the intense localization of charge at the dielectric surface in the nanogap region for separations smaller than 6 nm.

关键词： plasmonics fano interference transmission electron microscopy (TEM) nanogapdark-field spectroscopy

The Influence of biological Maturity on Dynamic Force-Time Variables and Vaulting Performance in Young Female Gymnasts

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Journal of Science in Sport and Exercise 2020年第4期2卷 319-329页

作者： Sylvia Moeskops Jon L.Oliver Paul J.Read John b.cronin Gregory D.Myer G.Gregory Haff Isabel S.Moore Rhodri S.Lloyd Youth Physical Development Centre Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCyncoed CampusCyncoed RoadCardiffCF52YBUK Sports Performance Research Institute New Zealand(SPRINZ) AUT UniversityAuckland 1142New Zealand Centre for Sport Science and Human Performance Waikato Institute of TechnologyHamilton 3240New Zealand Athlete Health and Performance Research Centre Aspetar Orthopaedic and Sports Medicine HospitalDohaQatar Division of Sports Medicine Cincinnati Children’s HospitalCincinnatiOH45229USA Department of Pediatrics and Orthopaedic Surgery College of MedicineUniversity of CincinnatiCincinnatiOH 45267USA The Micheli Center for Sports Injury Prevention WalthamMA 02453USA Centre for Exercise and Sports Science Edith Cowan UniversityJoondalupWA 6027Australia Australian Centre for Research into Injury in Sport and Its Prevention(ACRISP) Edith Cowan UniversityJoondalupWA 6027Australia University of Gloucestershire GloucesterGL502RHUK

Purpose This cross-sectional study investigated dynamic force-time variables and vaulting performance in young female gymnasts of different maturity *** 120 gymnasts aged 5-14 years were sub-divided into maturity groupings using percent of predicted adult height(%PAH)*** performed three jumping protocols,the squat jump(SJ),countermovement jump(CMJ)and drop jump(DJ),before completing straight jump vaults that were recorded using two-dimensional *** Jumping performance improved with biological maturity evidenced by the most mature gymnasts’producing sig-nificantly more absolute force(P0.78),impulse(P0.75)and power(P0.91)than the least mature group,resulting in the greater jump heights(P0.70).While,no significant differences were observed in relative peak force across multiple tests,measures of relative peak power did significantly increase with *** upon regression analyses,maturation was found to influence vertical take-off velocity during vaulting,explaining 41%of the variance in each jumping *** all tests,the DJ was found to have the highest predictive ability of vaulting vertical take-off velocity,explaining 55%of the total *** biological maturation impacts jump height and underpinning mechanical variables in young female *** vertical take-off velocity appears to be influenced by maturation and various dynamic force-time variables,par-ticularly those during DJ,which had the highest explained total variance.

关键词： Youth Maturation Squat jump Countermovement jump Drop jump Gymnastics

Thermoelectric transport across graphene/hexagonal boron nitride/graphene heterostructures

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Nano Research 2015年第2期8卷 666-672页

作者： Chun-Chung Chen Zhen Li Li Shi step.en b. cronin Department of Electrical engineering University of Southern California Los Angeles CA 90089 USA Department of Mechanical engineering and Texas Materials Institute University of Texas at Austin Texas 78712 USA

We report thermoelectric transport measurements across a graphene/hexagonal boron nitride （h-bN）/graphene heterostructure device. Using an AC lock-in technique, we are able to separate the thermoelectric contribution to the I-V characteristics of these important device structures. The temperature gradient is measured optically using Raman spectroscopy, which enables us to explore thermoelectric transport produced at material interfaces, across length scales of just 1-2 nm. based on the observed thermoelectric voltage （AV） and tem- perature gradient （AT）, a Seebeck coefficient of -99.3 μV/K is ascertained for the heterostructure device. The obtained Seebeck coefficient can be useful for understanding the thermoelectric component in the cross-plane I-V behaviors of emerging 2D heterostructure devices. These results provide an approach to probing thermoelectric energy conversion in two-dimensional layered heterostructures.

关键词： graphene boron nitride 2D materials heterostructure thermoelectric

enhanced photocurrent and photoluminescence spectra in MoS2 under ionic liquid gating

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Nano Research 2014年第7期7卷 973-980页

作者： Zhen Li Shun-Wen Chang Chun-Chung Chen step.en b. cronin Department of Electrical engineering Department of Physics University of Southern California 3737 Watt Way PHE 624 Los Angeles CA 90089 USA

We report substantial improvements and modulation in the photocurrent （PC） and photoluminescence （PL） spectra of monolayer MoS2 recorded under electrostatic and ionic liquid gating conditions. The photocurrent and photo- luminescence spectra show good agreement with a dominant peak at 1.85 eV. The magnitude of the photoluminescence can be increased 300% by ionic liquid gating due to the passivation of surface states and trapped charges that act as recombination centers. The photocurrent also doubles when passivated by the ionic liquid. Interestingly, a significant shift of the PL peak position is observed under electrostatic （14 meV） and ionic liquid （30 meV） gating, as a result of passivation. The ionic liquid provides significant screening without any externally applied voltage, indicating that these surface recombination centers have net charge. The acute sensitivity of monolayer MoS2 to ionic liquid gating and passivation arises because of its high surface-to-volume ratio, which makes it especially sensitive to trapped charge and surface states. These results reveal that, in order for efficient optoelectronic devices to be made from monolayer MoS2, some passivation strategy must be employed to mitigate the issues associated with surface recombination.

关键词： ionic liquid dichalcogenide MoS2 photoluminescence photocurrent passivation

Perceived stigma and quality of life in Parkinson’s disease with additional health conditions

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General Psychiatry 2022年第3期35卷 192-200页

作者： Samia S Islam Sandy Neargarder Shraddha b Kinger Joshua T Fox-Fuller Robert D Salazar Alice cronin-Golomb Department of Psychological and brain Sciences Boston UniversityBostonMassachusettsUSA Department of Psychology Bridgewater State UniversityBridgewaterMassachusettsUSA

background Parkinson’s disease(PD)is associated with perceived stigma and affects quality of life(QoL).Additional health conditions may influence these consequences of *** This study assessed the impact of health conditions on perceived stigma and QoL in persons with *** hypothesised that individuals with more health conditions would report more stigma and poorer *** also examined the contributions of demographic and clinical characteristics to the correlations between health conditions and perceived stigma/*** We identified 196 eligible participants from the boston University Online Survey Study of Parkinson’s Disease and examined their health history,performance on multiple stigma measures,and scores on the 39-item Parkinson’s Disease Questionnaire assessing *** At least one health condition was reported by 79%of the sample,with a median of 2 and a range of 0–7 health *** perceived stigma and poorer QoL were associated with thyroid disease,depression,anxiety,and the total number of health *** correlations were related to younger age,less education,and earlier disease *** health conditions(high blood pressure,back/leg surgery,headache,cancer/tumours,and heart disease)were not significantly correlated with stigma or *** Having more health conditions,or thyroid disease,depression,or anxiety,was associated with more perceived stigma and poorer QoL,with younger age,less education,and earlier disease onset affecting the *** is important to consider the burden of health conditions and how they affect persons with PD with specific clinical characteristics.

关键词： younger life education

Plasmon resonant amplification of a hot electron-driven photodiode

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Nano Research 2018年第4期11卷 2310-2314页

作者： Lang Shen Nirakar Poudel George N. Gibson bingya Hou Jihan Chen Haotian Shi Ernest Guignon William D. Page Arturo Pilar step.en b. cronin Mork Family Department of Chemical engineering and Materials Science University of Southern California Los Angeles CA 90089 USA Ming Hsieh Department of Electrical engineering University of Southern California Los Angeles CA 90089 USA Department of Physics University of Connecticut Storrs CT06269 USA Department of Chemistry University of Southern California Los Angeles CA 90089 USA Ciencia Inc. East Hartford CT 06108 USA Department of Physics and Astronomy University of Southern California Los Angeles CA 90089 USA

We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal （Au/Al2O3/graphene） heterostructure. In this device, hot electrons, excited optically in the gold layer, jump over the oxide barrier and are injected into the graphene layer, producing a photocurrent. To amplify this process, the bottom gold electrode is patterned into a plasmon resonant grating structure with a pitch of 500 nm. The photocurrent produced in this device is measured using 633-nm-wavelength light as a function of incident angle. We observe the maximum photocurrent at ＋10° from normal incidence under irradiation with light polarized parallel to the incident plane （p-polarization） and perpendicular to the lines on the grating, and a constant （angle-independent） photocurrent under irradiation with light polarized perpendicular to the incident plane （s-polarization） and parallel to the grating. These data show an amplification factor of 4.6× under resonant conditions. At the same angle （±10°）, we also observe sharp dips in the photoreflectance corresponding to wavevector matching between the incident light and the plasmon mode in the grating. In addition, finite-difference time-domain simulations predict sharp dips in the photoreflectance at ±10°, and the electric field intensity profiles show clear excitation of a plasmon resonant mode when illuminated with p-polarized light at this angle.

关键词： hot electrons plasmonic resonance plasmon grating photocurrent non-equilibrium

Carrier dynamics and doping profiles in GaAs nanosheets

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Nano Research 2014年第2期7卷 163-170页

作者： Chia-Chi Chang Chun-Yung Chi Chun-Chung Chen Ningfeng Huang Shermin Arab Jing Qiu Michelle L. Povinelli P. Daniel Dapkus step.en b. cronin Department of Physics Center for energy Nanoscience Department of Electrical engineering Department of Chemical engineering and Materials Science University of Southern California Los Angeles CA 90089 USA

We have recently demonstrated that GaAs nanosheets can be grown by metal-organic chemical vapor deposition （MOCVD）. Here, we investigate these nanosheets by secondary electron scanning electron microscopy （SE-SEM） and electron beam induced current （EbIC） imaging. An abrupt boundary is observed between an initial growth region and an overgrowth region in the nanosheets. The SE-SEM contrast between these two regions is attributed to the inversion of doping at the boundary. EbIC mapping reveals a p-n junction formed along the boundary between these two regions. Rectifying I-V behavior is observed across the boundary further indicating the formation of a p-n junction. The electron concentration （ND） of the initial growth region is around 1 × 10^18 cm^-3, as determined by both Hall effect measurements and low temperature photoluminescence （PL） spectroscopy. based on the EbIC data, the minority carrier diffusion length of the nanosheets is 177 nm, which is substantially longer than the corresponding length in unpassivated GaAs nanowires measured previously.

关键词： MOCVD GaAs nanosheets EbIC Hall measurement secondary electronemission

Electron-phonon coupling of G mode and components of a combination mode in carbon nanotubes

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Electron-phonon coupling of G mode and components of a combi...