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Efficient and wideband acousto-optic modulation on thin-film lithium niobate for microwave-to-photonic conversion

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Photonics Research 2021年第7期9卷 1182-1190页

作者： AHMED E.HASSANIEN STEFFEN lINK YANSONG YANG EDMOND CHOW lynford l.goddard SONGBIN GONG Holonyak Micro and Nanotechnology laboratory Department of Electrical and Computer EngineeringUniversity of Illinois at Urbana-ChampaignUrbanaIllinois 61801USA

Microwave photonics,a field that crosscuts microwave/millimeter-wave engineering with optoelectronics,has sparked great interest from research and commercial sectors. This multidisciplinary fusion can achieve ultrawide bandwidth and ultrafast speed that were considered impossible in conventional chip-scale microwave/millimeterwave systems. Conventional microwave-to-photonic converters,based on resonant acousto-optic modulation,produce highly efficient modulation but sacrifice bandwidth and limit their applicability for most real-world microwave signal-processing applications. In this paper,we build highly efficient and wideband microwaveto-photonic modulators using the acousto-optic effect on suspended lithium niobate thin films. A wideband microwave signal is first piezoelectrically transduced using interdigitated electrodes into lamb acoustic waves,which directly propagates across an optical waveguide and causes refractive index pertp urbation through the photoelastic effect. This approach is power-efficient,with phase shifts up to 0.0166 rad∕m W over a 45μm modulation length and with a bandwidth up to 140 MHz at a center frequency of 1.9 GHz. Compared to the state-ofthe-art,a 9×more efficient modulation has been achieved by optimizing the acoustic and optical modes and their interactions.

关键词： wideband millimeter waveguide

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Direct laser writing of volumetric gradient index lenses and waveguides

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light(Science & Applications) 2020年第1期9卷 89-102页

作者： Christian R.Ocier Corey A.Richards Daniel A.Bacon-Brown Qing Ding Raman Kumar Tanner J.Garcia Jorik van de Groep Jung-Hwan Song Austin J.Cyphersmith Andrew Rhode Andrea N.Perry Alexander J.littlefield Jinlong Zhu Dajie Xie Haibo Gao Jonah F.Messinger Mark l.Brongersma Kimani C.Toussaint Jr lynford l.goddard Paul V.Braun Department of Materials Science and Engineering University of Illinois at Urbana-ChampaignUrbanaILUSA Materials Research laboratory University of Illinois at Urbana-ChampaignUrbanaILUSA Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-ChampaignUrbanaILUSA Department of Electrical and Computer Engineering University of Illinois at Urbana-ChampaignUrbanaILUSA Department of Materials Science and Engineering Stanford UniversityStanfordCAUSA Carl R.Woese Institute for Genomic Biology University of Illinois at Urbana-ChampaignUrbanaILUSA Department of Mechanical Science and Engineering University of Illinois at Urbana-ChampaignUrbanaILUSA

Direct laser writing(DlW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer ***,these printed structures are limited to the refractive index and dispersive properties of the ***,we present the subsurface controllable refractive index via beam exposure(SCRIBE)method,a lithographic approach that enables the tuning of the refractive index over a range of greater than 0.3 by performing DlW inside photoresist-filled nanoporous silicon and silica *** the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index and chromatic *** SCRIBE’s unprecedented index range and 3D writing accuracy has realized the world’s smallest(15μm diameter)spherical luneburg lens operating at visible ***’s ability to tune the chromatic dispersion alongside the refractive index was leveraged to render achromatic doublets in a single printing step,eliminating the need for multiple photoresins and writing *** also has the potential to form multicomponent optics by cascading optical elements within a *** a demonstration,stacked focusing structures that generate photonic nanojets were fabricated inside porous ***,an all-pass ring resonator was coupled to a subsurface 3D *** measured quality factor of 4600 at 1550 nm suggests the possibility of compact photonic systems with optical interconnects that traverse multiple *** is uniquely suited for constructing such photonic integrated circuits due to its ability to integrate multiple optical components,including lenses and waveguides,without additional printed supports.

关键词： index refractive render

Optically monitoring and controlling nanoscale topography during semiconductor etching

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light(Science & Applications) 2012年第1期1卷 41-46页

作者： Chris Edwards Amir Arbabi Gabriel Popescu lynford l.goddard Department of Electrical and Computer Engineering University of Illinois at Urbana-ChampaignUrbanaIL 61801USA

We present epi-diffraction phase microscopy(epi-DPM)as a non-destructive optical method for monitoring semiconductor fabrication processes in real time and with nanometer level *** method uses a compact Mach–Zehnder interferometer to recover quantitative amplitude and phase maps of the field reflected by the *** low temporal noise of 0.6 nm per pixel at 8.93 frames per second enabled us to collect a three-dimensional movie showing the dynamics of wet etching and thereby accurately quantify non-uniformities in the etch rate both across the sample and over *** displaying a gray-scale digital image on the sample with a computer projector,we performed photochemical etching to define arrays of microlenses while simultaneously monitoring their etch profiles with epi-DPM.

关键词： microscopy nanoscale metrology photochemical etching quantitative phase imaging semiconductor process monitoring

Overexpression of SHORT VEGETATIVE PHASE-lIKE (SVl) in Populus delays onset and reduces abundance of flowering in field-grown trees

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Horticulture Research 2021年第1期8卷 2404-2415页

作者： Greg S.Goralogia Glenn T.Howe Amy M.Brunner Emily Helliwell Michael F.Nagle Cathleen Ma Haiwei lu Amanda l.goddard Anna C.Magnuson Amy l.Klocko Steven H.Strauss Department of Forest Ecosystems and Society Oregon State UniversityCorvallisORUSA Department of Forest Resources and Environmental Conservation Virginia TechBlacksburgVAUSA Department of Biology University of Colorado Colorado SpringsColorado SpringsCOUSA

The spread of transgenes and exotic germplasm from planted crops into wild or feral species is a difficult problem for public and regulatory acceptance of genetically engineered plants,particularly for wind-pollinated trees such as *** report that overexpression of a poplar homolog of the floral repressor SHORT VEGETATIVE PHASE-lIKE(SVl),a homolog of the Arabidopsis MADS-box repressor SHORT VEGETATIVE PHASE(SVP),delayed the onset of flowering several years in three genotypes of field-grown transgenic *** expression of SVl correlated with a delay in flowering onset and lower floral abundance,and did not cause morphologically obvious or statistically significant effects on leaf characteristics,tree form,or stem *** effects on reproductive and vegetative phenology in spring was modest and *** results suggest that use of SVl and related floral repressors can be useful tools to enable a high level of containment for vegetatively propagated short-rotation woody energy or pulp crops.

关键词： field planted crops

Suppression of discontinuous precipitation and strength improvement by Sc doping in Cu-6 wt%Ag alloys

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Journal of Materials Science & Technology 2023年第4期135卷 80-96页

作者： Bailing An Rongmei Niu Yan Xin William lStarch Zhaolong Xiang Yifeng Su Robert E.goddard Jun lu Theo M.Siegrist Engang Wang Ke Han Key laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China National High Magnetic Field laboratory Florida State UniversityTallahasseeFL 32310USA Oak Ridge National laboratory Oak RidgeTN 37830USA FAMU-FSU College of Engineering TallahasseeFL 32310USA

In low-Ag Cu matrix alloys,the presence of coarse discontinuous precipitates may limit *** demonstrated that discontinuous precipitation was suppressed,and continuous precipitation was en-hanced by the doping of Cu-6 wt%Ag with Sc.A high-volume fraction of continuous precipitates,which nucleated on{111}planes,led to a 55 MPa increase in strength,with only a slight decrease in electri-cal *** addition of Sc inhibited the nucleation of discontinuous precipitates by causing the Sc and the Ag to co-segregate onto grain boundaries,thus forming a thin intermetallic compound layer between *** deformation,both discontinuous and continuous precipitates were drawn into Ag *** combination of deformation strain and doping caused an increase in density and a decrease in the diameter of Ag fibers,resulting in about 205 MPa increase in doped samples when the deformation strain reached *** thinner,denser Ag fibers in the doped samples also caused higher electron scatter-ing at interfaces,leading to electrical conductivity that was 11%IACS lower than in non-doped *** reference,100%IACS(International Annealed Copper Standard)is equivalent to 1.7241μΩcm.

关键词： Sc doping Grain boundary segregation Precipitation Strength Electrical conductivity Plastic deformation

金属Pd催化NO还原形成NH_(3),N_(2)O和N_(2)的原子机制

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Chinese Journal of Chemical Physics 2023年第1期36卷 94-102,I0034-I0042,I0002页

作者：于沛平吴宇杨昊谢森 William A.goddard Ⅲ 程涛苏州大学功能纳米与软物质研究院江苏省碳基功能材料与器件高技术研究重点实验室苏州215123 美国加州理工学院美国光合成联合研究中心加利福利亚91125

工业污染物NO是对环境和人类健康的潜在威胁.因此,将NO选择性地催化还原成无害的N_(2)、NH_(3)或N_(2)O气体是非常有意义的.在许多催化剂中,金属钯已被证明在将NO还原为N_(2)的选择性方面是最有效的.然而,NO在Pd上的还原机制,特别是N-N... 详细信息

工业污染物NO是对环境和人类健康的潜在威胁.因此,将NO选择性地催化还原成无害的N_(2)、NH_(3)或N_(2)O气体是非常有意义的.在许多催化剂中,金属钯已被证明在将NO还原为N_(2)的选择性方面是最有效的.然而,NO在Pd上的还原机制,特别是N-N键的形成途径仍然不清楚,阻碍了新型催化剂的开发.本文基于密度泛函理论的量子力学计算,报道了还原NO形成NH_(3)、N_(2)O和N_(2)的反应路径中的所有基本反应步骤.结果表明,N_(2)O的形成是通过Eley-Rideal反应机制进行的.即在较高的NO^(*)表面覆盖率时,通过将一个吸附的NO^(*)与一个来自溶剂或气相的非吸附的NO结合,形成dimer-(NO)_(2)^(*)中间物,其N-N耦合势垒较低(0.58 eV).发现了dimer-(NO)_(2)^(*)将继续与溶剂中的NO反应,形成N_(2)O,这一点本文发现之前没有报道过.随着NO的消耗和溶剂中N_(2)O^(*)的形成,langmuir-Hinshelwood(l-H)机制将占主导地位,N_(2)O^(*)将在低化学势垒(0.42 eV)下被还原,从而形成N_(2).相比之下,NH_(3)完全由l-H反应形成,它具有较高的化学势垒(0.87 eV).此外,本文报道了通过在NO^(*)吸附位点掺入另一个金属原子(M)以形成M/Pd,通过考察其对N-N键形成能和N_(2)^(*)结合能的影响,从而实现对产物选择性的调控.

关键词：一氧化氮还原计算模型电化学反应

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SCN5A-△KPQ变异的长QT综合征的细胞电生理

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临床心血管病杂志 2005年第4期21卷 195-197页

作者：雷鸣 goddard C 孙思 Colledge W H Grace A A Huang C l 华中科技大学协和医院心内科华中科技大学同济医学院心血管病研究所武汉430022 Cardiovascular Group Departments of Biochemistry and Physiology University of Cambridge Tennis Court Road Cambridge CB2 1QW UK 华中科技大学协和医院血液科华中科技大学同济医学院干细胞中心

目的探讨长QT综合征3型(lQT3)的致病基因SCN5A及其相关的变异产生室性心律失常的细胞电生理机制。方法从野生型小鼠和SCN5A+/△的小鼠心脏中分离心室肌细胞,采用电流嵌和全细胞膜片钳技术分析了携带SCN5A△KPQ变异的小鼠心肌细胞的电生... 详细信息

目的探讨长QT综合征3型(lQT3)的致病基因SCN5A及其相关的变异产生室性心律失常的细胞电生理机制。方法从野生型小鼠和SCN5A+/△的小鼠心脏中分离心室肌细胞,采用电流嵌和全细胞膜片钳技术分析了携带SCN5A△KPQ变异的小鼠心肌细胞的电生理学表型。结果与野生型细胞[(55.0±6.6)ms,n=7]相比,SCN5A+/△心肌细胞[(152±17.8)ms,n=6]动作电位明显延长(P<0.01);在SCN5A+/△心肌细胞中观察到早期后除极,而野生型心肌细胞中则未出现;全细胞记录表明SCN5A+/△心肌细胞有晚期持续钠电流,而在野生型细胞中未见。结论晚期持续钠电流可能是与SCN5A△KPQ突变相关的室性心律失常的主要机制。

关键词：长QT综合征 sCN5A基因全细胞膜片钳技术电生理学研究,心脏

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列车的空气弹簧转向架——英国铁路部门研究设计的试验型转向架

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智慧轨道交通 1965年第8期 5-9页

作者： J.l.Koffman B.J.goddard 张万九

很多年来设計师对于車辆制造中消除綫路激扰所引起的共振的要点已經有所了解,但是随着列車速度的提高,要完全滿足这个要求是很困难的。在一般的速度下,可以将走行装置的固有頻率設計得足够。使車辆能在低于共振速度的区域內运行,但是在... 详细信息

很多年来设計师对于車辆制造中消除綫路激扰所引起的共振的要点已經有所了解,但是随着列車速度的提高,要完全滿足这个要求是很困难的。在一般的速度下,可以将走行装置的固有頻率設計得足够。使車辆能在低于共振速度的区域內运行,但是在高速度时要达到这个要求是比較困难的,特別在横向平面內,即使将車輪踏面錐度从1/20减少到1/40,增加轉向架固定軸臣等也不能完全消除蛇行运动引起的强迫振动頻率。

关键词：气弹簧摇枕侧架平面内铁路铁道踏面转向架转向装置英国大不列颠及北爱尔兰联合王国

列车的空气弹簧转向架——英国铁路部门研究设计的试验型转向架

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铁道车辆 1965年第8期 5-9页

作者： J.l.Koffman ,B.J.goddard ,张万九

很多年来设计师对于车辆制造中消除线路激扰所引起的共振的要点已经有所了解,但是随着列车速度的提高,要完全满足这个要求是很困难的。在一般的速度下,可以将走行装置的固有频率设计得足够。使车辆能在低于共振速度的区域内运行,但是在... 详细信息

很多年来设计师对于车辆制造中消除线路激扰所引起的共振的要点已经有所了解,但是随着列车速度的提高,要完全满足这个要求是很困难的。在一般的速度下,可以将走行装置的固有频率设计得足够。使车辆能在低于共振速度的区域内运行,但是在高速度时要达到这个要求是比较困难的,特别在横向平面内,即使将车轮踏面锥度从1/20减少到1/40,增加转向架固定轴距等也不能完全消除蛇行

关键词：气弹簧铁路铁道踏面转向架转向装置英国大不列颠及北爱尔兰联合王国