TY  - JOUR
A1  - Huang, Hongshi
A1  - Guo, Jianqiao
A1  - Yang, Jie
A1  - Jiang, Yanfang
A1  - Yu, Yuanyuan
A1  - Mueller, Steffen
A1  - Ren, Gexue
A1  - Ao, Yingfang
T1  - Isokinetic angle-specific moments and ratios characterizing hamstring and quadriceps strength in anterior cruciate ligament deficient knees
JF  - Scientific reports
N2  - This study is intended to find more effective and robust clinical diagnostic indices to characterize muscle strength and coordination alternation following anterior cruciate ligament (ACL) rupture. To evaluate angle-specific moments and hamstring (H)/quadriceps (Q) ratios, 46 male subjects with unilateral chronic ACL-rupture performed isokinetic concentric (c), eccentric (e) quadriceps and hamstring muscle tests respectively at 60 degrees/s. Normalized moments and H/Q ratios were calculated for peak moment (PM) and 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees knee flexion angles. Furthermore, we introduced single-to-arithmetic-mean (SAM) and single-to-root-mean-square (SRMS) muscle co-contraction ratios, calculating them for specific angles and different contraction repetitions. Normalized PM and 40 degrees specific concentric quadriceps, concentric hamstring strength in the ACL-deficient knee were reduced significantly (P <= 0.05). Concentric angle-specific moments together with Qe/Qc ratios at 40 degrees (d = 0.766 vs. d = 0.654) identify more obvious differences than peak values in ACL ruptured limbs. Furthermore, we found SRMS-QeQc deficits at 40 degrees showed stronger effect than Qe/Qc ratios (d = 0.918 vs. d = 0.766), albeit other ratio differences remained basically the same effect size as the original H/Q ratios. All the newly defined SAM and SRMS indices could decrease variance. Overall, 40 degrees knee moments and SAM/ SRMS ratios might be new potential diagnosis indices for ACL rupture detection.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06601-5
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Wilkin, Kyle J.
A1  - Parrish, Robert M.
A1  - Yang, Jie
A1  - Wolf, Thomas J. A.
A1  - Nunes, J. Pedro F.
A1  - Gühr, Markus
A1  - Li, Renkai
A1  - Shen, Xiaozhe
A1  - Zheng, Qiang
A1  - Wang, Xijie
A1  - Martinez, Todd J.
A1  - Centurion, Martin
T1  - Diffractive imaging of dissociation and ground-state dynamics in a complex molecule
JF  - Physical review : A, Atomic, molecular, and optical physics
N2  - We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules (C2F4I2) in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited-state dynamics simulations. The molecules are excited by an ultraviolet femtosecond laser pulse to a state characterized by a transition from the iodine 5p perpendicular to orbital to a mixed 5p parallel to sigma hole and CF2 center dot antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wave packet of the dissociating iodine atom followed by coherent vibrations in the electronic ground state of the C2F4I radical. The radical reaches a stable classical (nonbridged) structure in less than 200 fs.
Y1  - 2019
U6  - https://doi.org/10.1103/PhysRevA.100.023402
SN  - 2469-9926
SN  - 2469-9934
VL  - 100
IS  - 2
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Yang, Jie
A1  - Guehr, Markus
A1  - Shen, Xiaozhe
A1  - Li, Renkai
A1  - Vecchione, Theodore
A1  - Coffee, Ryan
A1  - Corbett, Jeff
A1  - Fry, Alan
A1  - Hartmann, Nick
A1  - Hast, Carsten
A1  - Hegazy, Kareem
A1  - Jobe, Keith
A1  - Makasyuk, Igor
A1  - Robinson, Joseph
A1  - Robinson, Matthew Scott
A1  - Vetter, Sharon
A1  - Weathersby, Stephen
A1  - Yoneda, Charles
A1  - Wang, Xijie
A1  - Centurion, Martin
T1  - Diffractive Imaging of Coherent Nuclear Motion in Isolated Molecules
JF  - Physical review letters
N2  - Observing the motion of the nuclear wave packets during a molecular reaction, in both space and time, is crucial for understanding and controlling the outcome of photoinduced chemical reactions. We have imaged the motion of a vibrational wave packet in isolated iodine molecules using ultrafast electron diffraction with relativistic electrons. The time-varying interatomic distance was measured with a precision 0.07 angstrom and temporal resolution of 230 fs full width at half maximum. The method is not only sensitive to the position but also the shape of the nuclear wave packet.
Y1  - 2016
U6  - https://doi.org/10.1103/PhysRevLett.117.153002
SN  - 0031-9007
SN  - 1079-7114
VL  - 117
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - GEN
A1  - Yang, Jie
A1  - Guehr, Markus
A1  - Vecchione, Theodore
A1  - Robinson, Matthew Scott
A1  - Li, Renkai
A1  - Hartmann, Nick
A1  - Shen, Xiaozhe
A1  - Coffee, Ryan
A1  - Corbett, Jeff
A1  - Fry, Alan
A1  - Gaffney, Kelly
A1  - Gorkhover, Tais
A1  - Hast, Carsten
A1  - Jobe, Keith
A1  - Makasyuk, Igor
A1  - Reid, Alexander
A1  - Robinson, Joseph
A1  - Vetter, Sharon
A1  - Wang, Fenglin
A1  - Weathersby, Stephen
A1  - Yoneda, Charles
A1  - Wang, Xijie
A1  - Centurion, Martin
T1  - Femtosecond gas phase electron diffraction with MeV electrons
N2  - We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 326 
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-394989
ER  - 
TY  - JOUR
A1  - Yang, Jie
A1  - Gühr, Markus
A1  - Vecchione, Theodore
A1  - Robinson, Matthew Scott
A1  - Li, Renkai
A1  - Hartmann, Nick
A1  - Shen, Xiaozhe
A1  - Coffee, Ryan
A1  - Corbett, Jeff
A1  - Fry, Alan
A1  - Gaffney, Kelly
A1  - Gorkhover, Tais
A1  - Hast, Carsten
A1  - Jobe, Keith
A1  - Makasyuk, Igor
A1  - Reid, Alexander
A1  - Robinson, Joseph
A1  - Vetter, Sharon
A1  - Wang, Fenglin
A1  - Weathersby, Stephen
A1  - Yoneda, Charles
A1  - Centurion, Martin
A1  - Wang, Xijie
T1  - Diffractive imaging of a rotational wavepacket in nitrogen molecules
with femtosecond megaelectronvolt electron pulses
JF  - Nature Communications
N2  - Imaging changes in molecular geometries on their natural femtosecond timescale with sub-Angstrom spatial precision is one of the critical challenges in the chemical sciences, as the nuclear geometry changes determine the molecular reactivity. For photoexcited molecules, the nuclear dynamics determine the photoenergy conversion path and efficiency. Here we report a gas-phase electron diffraction experiment using megaelectronvolt (MeV) electrons, where we captured the rotational wavepacket dynamics of nonadiabatically laser-aligned nitrogen molecules. We achieved a combination of 100 fs root-mean-squared temporal resolution and sub-Angstrom (0.76 angstrom) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule. In addition, the diffraction patterns reveal the angular distribution of the molecules, which changes from prolate (aligned) to oblate (anti-aligned) in 300 fs. Our results demonstrate a significant and promising step towards making atomically resolved movies of molecular reactions.
Y1  - 2016
U6  - https://doi.org/10.1038/ncomms11232
SN  - 2041-1723
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Yang, Jie
A1  - Gühr, Markus
A1  - Vecchione, Theodore
A1  - Robinson, Matthew Scott
A1  - Li, Renkai
A1  - Hartmann, Nick
A1  - Shen, Xiaozhe
A1  - Coffee, Ryan
A1  - Corbett, Jeff
A1  - Fry, Alan
A1  - Gaffney, Kelly
A1  - Gorkhover, Tais
A1  - Hast, Carsten
A1  - Jobe, Keith
A1  - Makasyuk, Igor
A1  - Reid, Alexander
A1  - Robinson, Joseph
A1  - Vetter, Sharon
A1  - Wang, Fenglin
A1  - Weathersby, Stephen
A1  - Yoneda, Charles
A1  - Wang, Xijie
A1  - Centurion, Martin
T1  - Femtosecond gas phase electron diffraction with MeV electrons
JF  - Faraday discussions
N2  - We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution.
Y1  - 2016
U6  - https://doi.org/10.1039/c6fd00071a
SN  - 1359-6640
SN  - 1364-5498
VL  - 194
SP  - 563
EP  - 581
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Yang, Jie
A1  - Zhu, Xiaolei
A1  - Wolf, Thomas J. A.
A1  - Li, Zheng
A1  - Nunes, João Pedro Figueira
A1  - Coffee, Ryan
A1  - Cryan, James P.
A1  - Gühr, Markus
A1  - Hegazy, Kareem
A1  - Heinz, Tony F.
A1  - Jobe, Keith
A1  - Li, Renkai
A1  - Shen, Xiaozhe
A1  - Veccione, Theodore
A1  - Weathersby, Stephen
A1  - Wilkin, Kyle J.
A1  - Yoneda, Charles
A1  - Zheng, Qiang
A1  - Martinez, Todd J.
A1  - Centurion, Martin
A1  - Wang, Xijie
T1  - Imaging CF3I conical intersection and photodissociation dynamics with ultrafast electron diffraction
JF  - Science
N2  - Conical intersections play a critical role in excited-state dynamics of polyatomic molecules because they govern the reaction pathways of many nonadiabatic processes. However, ultrafast probes have lacked sufficient spatial resolution to image wave-packet trajectories through these intersections directly. Here, we present the simultaneous experimental characterization of one-photon and two-photon excitation channels in isolated CF3I molecules using ultrafast gas-phase electron diffraction. In the two-photon channel, we have mapped out the real-space trajectories of a coherent nuclear wave packet, which bifurcates onto two potential energy surfaces when passing through a conical intersection. In the one-photon channel, we have resolved excitation of both the umbrella and the breathing vibrational modes in the CF3 fragment in multiple nuclear dimensions. These findings benchmark and validate ab initio nonadiabatic dynamics calculations.
Y1  - 2018
U6  - https://doi.org/10.1126/science.aat0049
SN  - 0036-8075
SN  - 1095-9203
VL  - 361
IS  - 6397
SP  - 64
EP  - 67
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  -