Accurate transfer of bimaxillary orthognathic surgical plans using computer-aided intraoperative navigation

Chen Chen,Ningning Sun,Chunmiao Jiang,Yanshan Liu,Jian Sun 대한치과교정학회 2021 대한치과교정학회지 Vol.51 No.5

Objective: To examine the accuracy of computer-aided intraoperative navigation (Ci-Navi) in bimaxillary orthognathic surgery by comparing preoperative planning and postoperative outcome. Methods: The study comprised 45 patients with congenital dentomaxillofacial deformities who were scheduled to undergo bimaxillary orthognathic surgery. Virtual bimaxillary orthognathic surgery was simulated using Mimics software. Intraoperatively, a Le Fort I osteotomy of the maxilla was performed using osteotomy guide plates. After the Le Fort I osteotomy and bilateral sagittal split ramus osteotomy of the mandible, the mobilized maxilla and the distal mandibular segment were fixed using an occlusal splint, forming the maxillomandibular complex (MMC). Realtime Ci-Navi was used to lead the MMC in the designated direction. Osteoplasty of the inferior border of the mandible was performed using Ci-Navi when facial symmetry and skeletal harmony were of concern. Linear and angular distinctions between preoperative planning and postoperative outcomes were calculated. Results: The mean linear difference was 0.79 mm (maxilla: 0.62 mm, mandible: 0.88 mm) and the overall mean angular difference was 1.20°. The observed difference in the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was < 1 mm in 40 cases. Conclusions: This study demonstrates the role of Ci-Navi in the accurate positioning of bone segments during bimaxillary orthognathic surgery. Ci-Navi was found to be a reliable method for the accurate transfer of the surgical plan during an operation.

Transplanting neurofibromatosis-1 gene knockout neural stem cells improve functional recovery in rats with spinal cord injury by enhancing the mTORC2 pathway

Chen Guoliang,Li Xianlong,Zhu Hongzhang,Wu Huachuan,He Dacheng,Shi Liangyu,Wei Fuxin,Liu Xizhe,Chen Ningning,Liu Shaoyu 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

The poor survival and low efficiency of neuronal differentiation limits the therapeutic effects of transplanted neural stem cells in the treatment of spinal cord injury. Neurofibromatosis-1 (NF-1) is a tumor suppressor gene that restricts the rapid and abnormal growth and differentiation of neural cells. In the present study, lentiviral vectors were used to knock out NF-1, Ricotr (the core member of mTORC2) or NF-1+Ricotr in neural stem cells in vitro, and the NF-1, Ricotr or NF-1+Ricotr knockout neural stem cells were transplanted at the lesion site in a rat model of spinal cord injury (SCI). We first demonstrated that targeted knockout of NF-1 had an antiapoptotic effect and improved neuronal differentiation by enhancing the mTORC2/Rictor pathway of neural stem cells in vitro. Subsequently, transplanting NF-1 knockout neural stem cells into the injured site sufficiently promoted the tissue repair and functional recovery of rats with spinal cord injury by enhancing the survival and neuronal differentiation of grafted neural stem cells. Collectively, these findings reveal a prominent role of NF-1 in neural stem cell biology, which is an invaluable step forward in enhancing the benefit of neural stem cell-mediated regenerative cell therapy for spinal cord injury and identifies the transplantation of NF-1 knockout neural stem cells as a promising strategy for spinal cord injury.

Probabilistic and spectral modelling of dynamic wind effects of quayside container cranes

Suning Chen,Peng Shitao,Hong Ningning,Wu Xiaotong,Chen Yunyue 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.4

Quayside container cranes are important delivery machineries located in the most frontiers of container terminals, where strong wind attacks happen occasionally. Since the previous researches on quayside container cranes mainly focused on the mean wind load and static response characteristics, the fluctuating wind load and dynamic response characteristics require further investigations. In the present study, the aerodynamic wind loads on quayside container cranes were obtained from wind tunnel tests. The probabilistic and spectral models of the fluctuating aerodynamic loads were established. Then the joint probabilistic distributions of dynamic wind-induced responses were derived theoretically based on a series of Gaussian and independent assumption of resonant components. Finally, the results were validated by time domain analysis using wind tunnel data. It is concluded that the assumptions are acceptable. And the presented approach can estimate peak dynamic sliding force, overturning moments and leg uplifts of quayside container cranes effectively and efficiently.

Structural insights into the dual substrate specificities of mammalian and <i>Dictyostelium</i> dihydropteridine reductases toward two stereoisomers of quinonoid dihydrobiopterin

Chen, Cong,Kim, Hye Lim,Zhuang, Ningning,Seo, Kyung Hye,Park, Ki Hun,Han, Chang-deok,Park, Young Shik,Lee, Kon Ho Elsevier 2011 FEBS letters Vol.585 No.17

<P><B>Highlights</B></P><P>► The binary structure of <I>Dic</I>DHPR-NAD<SUP>+</SUP> has been solved in 2.16Å resolution. ► Structural changes in NADH binding site result in a higher <I>K</I><SUB>m</SUB> for NADH than mammals. ► A mammalian DHPR carries a dual substrate activity verified by in vitro assay. ► We built structural models of the ratDHPR and <I>Dic</I>DHPR in complex with two substrates.</P> <P><B>Abstract</B></P><P>Up to now, <SMALL>D</SMALL>-<I>threo</I>-tetrahydrobiopterin (DH<SUB>4</SUB>, dictyopterin) was detected only in <I>Dictyostelium discoideum</I>, while the isomer <SMALL>L</SMALL>-<I>erythro</I>-tetrahydrobioterin (BH<SUB>4</SUB>) is common in mammals. To elucidate the mechanism of DH<SUB>4</SUB> regeneration by <I>D. discoideum</I> dihydropteridine reductase (<I>Dic</I>DHPR), we have determined the crystal structure of <I>Dic</I>DHPR complexed with NAD<SUP>+</SUP> at 2.16Å resolution. Significant structural differences from mammalian DHPRs are found around the coenzyme binding site, resulting in a higher <I>K</I><SUB>m</SUB> value for NADH (<I>K</I><SUB>m</SUB>=46.51±0.4μM) than mammals. In addition, we have found that rat DHPR as well as <I>Dic</I>DHPR could bind to both substrates quinonoid-BH<SUB>2</SUB> and quinonoid-DH<SUB>2</SUB> by docking calculations and have confirmed their catalytic activity by in vitro assay.</P><P><B>Structured summary of protein interactions</B></P><P><B>DHPR</B>bindsto<B>DHPR</B> by X-ray crystallography(View interaction)</P>

Complete convergence for weighted sums of i.i.d. random variables with applications in regression estimation and EV model

Chen, Pingyan,Kong, Ningning,Sung, Soo Hak Informa UK (TaylorFrancis) 2017 Communications in Statistics Vol.46 No.7

<P>In this paper, we obtain complete convergence results for Stout type weighted sums of i.i.d. random variables. A strong law for weighted sums of i.i.d. random variables is also obtained. As the applications of the strong law, the strong consistency and rate of the nonparametric regression estimations and the rates of the strong consistency of LS estimators for the unknown parameters of the simple linear errors in variables (EV) model are given.</P>

On DC-Side Impedance Frequency Characteristics Analysis and DC Voltage Ripple Prediction under Unbalanced Conditions for MMC-HVDC System Based on Maximum Modulation Index

Liu, Yiqi,Chen, Qichao,Li, Ningning,Xie, Bing,Wang, Jianze,Ji, Yanchao The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.

Green preparation of lipase@Ca3(PO4)2 hybrid nanoflowers using bone waste from food production for efficient synthesis of clindamycin palmitate

Anming Wang,Xinxin Chen,Jianyun Yu,Ningning Li,Huimin Li,Youcheng Yin,Tian Xie,Stephen Gang Wu 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.89 No.-

To prepare enzyme@Ca3(PO4)2 for environmentally friendly biocatalysis, Ca2+ and (PO4)3 were extractedfrom bone waste by acidification. In the nearly neutralizedfiltrate, the Ca2+ and (PO4)3 formed aCa3(PO4)2 sediment that crystallized on a template of Thermomyces lanuginosus lipase (TLL) at 4 ℃ for24 h, producing enzyme@Ca3(PO4)2-Bone hybrid nanoflowers (hNFs). Clindamycin palmitate wasefficiently synthesized by transfer of a palmityl moiety from vinyl palmitate to clindamycin free baseusing these hNFs as a biocatalyst. At 30 ℃ in petroleum ether (PE) as the solvent, the yield of the TLL hNFcatalyzedreaction was as high as 70.0%. Even at a high temperature (80 ℃), the yield in the hNF-catalyzedreaction was still 52.6%, but no product was detected when using free lipase as the catalyst. Moreover, thehNFs retained 90% of their initial activity after 10 cycles (120 h, 12 h per cycle). This green and sustainablemethod that utilizes bone waste from food production as the raw source of the inorganic component wasfacile and efficient, and the system may also be applicable for preparing other enzyme@Ca3(PO4)2 hNFsfor industrial applications.

On DC-Side Impedance Frequency Characteristics Analysis and DC Voltage Ripple Prediction under Unbalanced Conditions for MMC-HVDC System Based on Maximum Modulation Index

Yiqi Liu,Qichao Chen,Ningning Li,Bing Xie,Jianze Wang,Yanchao Ji 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.

Unusual NADPH conformation in the crystal structure of a cinnamyl alcohol dehydrogenase from <i>Helicobacter pylori</i> in complex with NADP(H) and substrate docking analysis

Seo, Kyung Hye,Zhuang, Ningning,Chen, Cong,Song, Jae-Young,Kang, Hyung-Lyun,Rhee, Kwang-Ho,Lee, Kon Ho Elsevier 2012 FEBS letters Vol.586 No.4

<P><B>Highlights</B></P><P>► The binary structure of HpCAD complex NADP(H) is solved at 2.18Å. ► An unusual conformation of the 2′phosphate group of the NADPH, not seen in other CAD structures, was found. ► Docking calculations showed that the substrate is stacked between the aromatic side chains of Tyr116 and Phe114.</P> <P><B>Abstract</B></P><P>Cinnamyl alcohol dehydrogenase is a zinc- and NADPH-dependent dehydrogenase catalyzing the reversible conversion of <I>p</I>-hydroxycinnamaldehydes to their corresponding hydroxycinnamyl alcohols. A CAD homolog from <I>Helicobacter pylori</I> (HpCAD) possesses broad substrate specificities like the plant CADs and additionally a dismutation activity converting benzaldehyde to benzyl alcohol and benzoic acid. We have determined the crystal structure of HpCAD complexed with NADP(H) at 2.18Å resolution to get a better understanding of this class of CAD outside of plants. The structure of HpCAD is highly homologous to the sinapyl alcohol dehydrogenase and the plant CAD with well-conserved residues involved in catalysis and zinc binding. However, the NADP(H) binding mode of the HpCAD has been found to be significantly different from those of plant CADs.</P><P><B>Structured summary of protein interactions</B></P><P><B>HpCAD</B> and <B>HpCAD</B> bind by x-ray crystallography (<U>View interaction</U>)</P>

Performance Improvement of Finite Time Parameter Estimation with Relaxed Persistence of Excitation Condition

Li Zhao,Jianhui Zhi,Ningning Yin,Yong Chen,Jin Li,Jiaolong Liu 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2

In this paper, a novel fi nite time parameter estimation method is proposed to solve the parameter estimation problem for a class of linearly parameterized nonlinear systems. The main feature of the proposed method is that the existing method is modifi ed via concurrent learning technique such that the strict persistence of excitation ( PE ) condition on the regression matrix is relaxed to a rank condition on the recorded data. This makes the presented method more practical. Furthermore, the convergence rate is improved signifi cantly by sliding mode technique in fi nite time sense. The simulation results of the existing general nonlinear system illustrate the aforementioned features. Comparison with existing methods from literature proves the eff ectiveness of the proposed method.