defect state
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2021 ◽  
Vol 231 ◽  
pp. 111297
Author(s):  
Christina Hollemann ◽  
Nils Folchert ◽  
Steven P. Harvey ◽  
Paul Stradins ◽  
David L. Young ◽  
...  

Author(s):  
Hari K Ankem ◽  
Vivian W Ouyang ◽  
Benjamin R Saks ◽  
Andrew E Jimenez ◽  
Payam W Sabetian ◽  
...  

ABSTRACT The aim of this study was to review and summarize the available biomechanical data on hip capsular reconstruction to guide clinical decision-making. A literature search was completed in December 2020 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify biomechanical cadaver studies on hip capsular reconstruction, hip capsulectomy or hip capsular defect. The investigated parameters included maximum distraction force, capsular state affecting range of motion (ROM), rotation and translation. Four studies met al. the inclusion–exclusion criteria. The median effective force for resisting maximum distraction for the reconstruction state, capsular defect state and the intact state was 171, 111 and 206 N, respectively. The defect capsule force was significantly lower (P = 0.00438) than the intact capsule force. The reconstruction state had a higher distraction force than that of the capsular defect, but due to heterogeneity, the overall effect size was not statistically significant. The capsular reconstruction state reduced excess motion and the degree of instability compared to the capsular defect state but restored the hip close to its native capsular state in the cadaveric model. When compared to capsulectomy/defect state, hip capsular reconstruction significantly improved the rotational stability and effective force at maximum distraction and minimized translation. However, no conclusions can be made regarding the most effective protocol due to the high heterogeneity between the four studies. Further biomechanical studies are needed to test various types of grafts under the same protocol.


Author(s):  
Qiang Yi ◽  
Caiyou Zhao ◽  
Ping Wang

To overcome the ill-conditioned matrix problem of the traditional transfer matrix method, the Floquet transform method and supercell technology are used to study the defect states of the periodic track structure. By solving the equations of the supercell directly, the propagation characteristics of elastic waves in the track structure with defects are analyzed. The existence of defects destroys the periodicity of track structure, thus resulting in the formation of defect states within the band gaps. Moreover, the elastic wave is localized near the defect position at the frequency of the defect state. The formation mechanism of the defect state in track structure can be explained by the local resonance at the defect. With the expansion of the defect range, the number of local resonance modes that can be formed near the defect increases, thus generating multiple defect states. Furthermore, the defect state enhances the vibration of the structure adjacent to the defect. Therefore, the vibration transmission coefficient in a finite-length range can be used to detect the defect characteristics in the track structure, and the defect degree can be evaluated by the peak frequency of the vibration transmission coefficient within the band gap.


2021 ◽  
Vol 14 (06) ◽  
pp. 2151039
Author(s):  
Meng Zhang ◽  
Ting Song ◽  
Hancheng Zhu ◽  
Xinyang Zhang

Study of the defect states in the luminescent host materials has always been a significant point in improving the light emitting devices performances. To afford candidate luminescence host materials, defect states in Sr3MgSi2O[Formula: see text]F[Formula: see text] induced by substitution of fluorine ions (F[Formula: see text] substituting for oxygen ions (O[Formula: see text] have been studied through first principles calculation and the related results are presented in this work. First, chemical formulas have been confirmed to be Sr3MgSi2O[Formula: see text]F[Formula: see text] through calculations of the possible crystal structures with increasing F[Formula: see text] substituting for O[Formula: see text] concentrations while band gap values decrease from 5.889 eV to 5.328 eV. When the fluorine ion substituting concentration [Formula: see text] reached 0.5, a new defect state near 3.002 eV in the band gap appeared and it can be concluded that the defect state originates from the two fluorine ions bonding to the same Si–O–F2 group. In addition, there arose a new absorption band in the visible region and it can also be attributed to the introduced color [Formula: see text] center in Sr3MgSi2O[Formula: see text]F. The aforementioned results show that tiny doping amounts of fluorine ions could make Sr3MgSi2O[Formula: see text]F[Formula: see text] suitable for luminescence host materials.


2021 ◽  
pp. 130391
Author(s):  
Akshaya Mouly Vijayakumari ◽  
Azad Ravi Oraon ◽  
Sonalie Ahirwar ◽  
Amala Kannath ◽  
Suja K J ◽  
...  
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AIP Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 075113
Author(s):  
Huan Liu ◽  
Ting Liu ◽  
Le Song ◽  
Qiao-Mu Zhang ◽  
Ya-Xian Fan ◽  
...  

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