95 results on '"Li, Jingzhi"'
Search Results
2. On the mean field games system with lateral Cauchy data via Carleman estimates.
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Klibanov, Michael V., Li, Jingzhi, and Liu, Hongyu
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GAMES , *INVERSE problems - Abstract
The second-order mean field games system (MFGS) in a bounded domain with the lateral Cauchy data are considered. This means that both Dirichlet and Neumann boundary data for the solution of the MFGS are given. Two Hölder stability estimates for two slightly different cases are derived. These estimates indicate how stable the solution of the MFGS is with respect to the possible noise in the lateral Cauchy data. Our stability estimates imply uniqueness. The key mathematical apparatus is the apparatus of two new Carleman estimates. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Hölder stability and uniqueness for the mean field games system via Carleman estimates.
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Klibanov, Michael V., Li, Jingzhi, and Liu, Hongyu
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PARABOLIC differential equations , *POPULATION density - Abstract
We are concerned with the mathematical study of the mean field games system (MFGS). In the conventional setup, the MFGS is a system of two coupled nonlinear parabolic partial differential equation (PDE)s of the second order in a backward–forward manner, namely, one terminal and one initial condition are prescribed, respectively, for the value function and the population density. In this paper, we show that uniqueness of solutions to the MFGS can be guaranteed if, among all four possible terminal and initial conditions, either only two terminals or only two initial conditions are given. In both cases, Hölder stability estimates are proven. This means that the accuracies of the solutions are estimated in terms of the given data. Moreover, these estimates readily imply uniqueness of corresponding problems for the MFGS. The main mathematical apparatus to establish those results is two new Carleman estimates, which may find application in other contexts associated with coupled parabolic PDEs. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Multiomics‐based study of amniotic fluid small extracellular vesicles identified Moesin as a biomarker for antenatal hydronephrosis.
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Li, Jingzhi, Fu, Ying, Liu, Qiaoshu, Shen, Kuifang, Yao, Ruojin, Fu, Yimei, Lu, Yang, Xie, Mingkun, Jian, Wenyan, Guo, Ming, Dai, Lei, and Zhang, Weishe
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AMNIOTIC liquid , *HYDRONEPHROSIS , *EXTRACELLULAR vesicles , *EXTRACELLULAR fluid , *BIOMARKERS , *AMNIOCENTESIS , *GENE expression , *FETAL surgery - Abstract
CON-sup, normal fetal amniotic fluid sEVs; ANH-sup, ANH amniotic fluid sEVs; CON-cell, normal fetal amniotic fluid cells; ANH-cell, ANH amniotic fluid cells. gl To further explore the special expression pattern in sEVs of ANH, we compared the proteins and mRNAs in sEVs between ANH and normal samples, respectively. Dear Editor, Antenatal hydronephrosis (ANH) is the most common congenital anomaly of the urinary tract. In this study, we extracted small extracellular vesicles riched samples (sEVs) from supernatant amniotic fluid (AF), identified and verified the high expressed Moesin as an effective biomarker for ANH diagnosis. We identified 116 differential expression proteins (Figure 3A, B; Tables S3) and 836 differential expression mRNAs (Figure 3E, F, TableS4) between ANH amniotic fluid sEVs (ANH-sup) and normal fetal amniotic fluid sEVs (CON-sup). [Extracted from the article]
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- 2023
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5. Immunogenicity evaluation of viral peptides via nonspecific interactions between anti-peptide IgYs and non-cognate peptides.
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Zhou, Yuxi, Li, Jingzhi, Wu, Wenya, Chen, Yanfei, Cheng, Hu, Li, Mengyu, Sun, Yiyue, Yang, Jiao, Peng, Daxin, Xue, Qinghong, and Ma, Hongwei
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IMMUNE response , *PEPTIDES , *VACCINE effectiveness , *ENZYME-linked immunosorbent assay , *ANTIBODY formation - Abstract
Immunogenicity can be evaluated by detecting antibodies (Abs) induced by an antigen. Presently deployed assays, however, do not consider the negative impacts of Ab poly-specificity, which is well established at the monoclonal antibody level. Here, we studied antibody poly-specificity at the serum level (i.e. nonspecific Ab–probe interactions, NSIs), and ended up establishing a new platform for viral peptide immunogenicity evaluation. We first selected three peptides of high, medium and low immunogenicity, using a 'vaccine serum response rate'-based approach (i.e. the gold standard). These three peptides (Pi) in the bovine serum albumin–Pi form were used to immunize chickens, resulting in longitudinal serum samples for screening with a non-cognate peptide library. The signal intensity of Ab-peptide specific binding and 'NSI count' was used to evaluate the viral peptides' immunogenicity. Only the NSI count agreed with the gold standard. The NSI count also provides more informative data on antibody production than the aggregated signal intensity by whole-protein-based indirect enzyme-linked immunosorbent assay. [ABSTRACT FROM AUTHOR]
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- 2023
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6. Accurate diagnosis of isolated iliac vein thrombosis in third trimester pregnancy with clues on great saphenous vein reflux: a case report and review of literature.
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Wei, Zhanghong, Li, Jingzhi, Liang, Lijun, and Luo, Hui
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SAPHENOUS vein , *ILIAC vein , *THIRD trimester of pregnancy , *VENOUS thrombosis , *VENA cava inferior - Abstract
Background: Pregnancy is known to be a risk factor for venous thromboembolism (VTE). We report the case of a pregnant patient with difficult to diagnose iliac vein thrombosis, establishing a definite diagnosis by clues of great saphenous vein reflux. Case presentation: A 37-year-old G1P0 woman at 35 weeks of assisted twin gestation presented with a complaint of persistent left lower limb edema and tenderness. A vascular ultrasound was used to examine the bilateral lower limb. Doppler of left lower extremity revealed continuous great saphenous vein reflux. Right saphenofemoral veins demonstrated venous stasis and no reflux. Unilateral continuous great saphenous vein reflux suggested left iliac veins obstruction or extrinsic compression. Anterograde venography showed a completely occlusive filling defect of the left external iliac vein, which is the definitive diagnosis of acute deep venous thrombosis. The patient underwent a cesarean delivery following inferior vena cava filter (IVCF) placement, and no signs of deep venous thrombosis (DVT) or pulmonary embolism (PE) were reported after delivery. Conclusion: In pregnant women with suspected deep vein thrombosis, it is imperative to assess the presence of unilateral continuous great saphenous vein reflux. [ABSTRACT FROM AUTHOR]
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- 2023
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7. Decellularized tympanic membrane scaffold with bone marrow mesenchymal stem cells for repairing tympanic membrane perforation.
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Lu, Yanqing, Li, Jingzhi, Hou, Nan, Zhou, Li, Quan, Xiaoxuan, Tang, Ying, Luo, Xiaoming, Huang, Shi, and Ma, Ruina
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TYMPANIC membrane perforation , *TYMPANIC membrane , *MESENCHYMAL stem cells , *BONE marrow , *BIOMATERIALS , *TISSUE scaffolds , *EXTRACELLULAR matrix - Abstract
Background: Tympanic membrane perforation (TMP) is a common disease in otology, and few acellular techniques have been reported for repairing this condition. Decellularized extracellular matrix (ECM) scaffolds have been used in organ reconstruction. Objective: This study on tissue engineering aimed to develop a tympanic membrane (TM) scaffold prepared using detergent immersion and bone marrow mesenchymal stem cells (BMSCs) as repair materials to reconstruct the TM. Results: General structure was observed that the decellularized TM scaffold with BMSCs retained the original intact anatomical ECM structure, with no cell residue, as observed using scanning electron microscopy (SEM), and exhibited low immunogenicity. Therefore, we seeded the decellularized TM scaffold with BMSCs for recellularization. Histology and eosin staining, SEM and immunofluorescence in vivo showed that the recellularized TM patch had a natural ultrastructure and was suitable for the migration and proliferation of BMSCs. The auditory brainstem response (ABR) evaluated after recellularized TM patch repair was slightly higher than that of the normal TM, but the difference was not significant. Conclusion: The synthetic ECM scaffold provides temporary physical support for the three‐dimensional growth of cells during the tissue developmental stage. The scaffold stimulates cells to secrete their own ECM required for tissue regeneration. The recellularized TM patch shows potential as a natural, ultrastructure biological material for TM reconstruction. [ABSTRACT FROM AUTHOR]
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- 2023
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8. A C0 interior penalty method for mth-Laplace equation.
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Chen, Huangxin, Li, Jingzhi, and Qiu, Weifeng
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EQUATIONS , *INTEGERS , *POLYNOMIALS , *POLYHEDRAL functions - Abstract
In this paper, we propose a C0 interior penalty method for mth-Laplace equation on bounded Lipschitz polyhedral domain in ℝd, where m and d can be any positive integers. The standard H1-conforming piecewise r-th order polynomial space is used to approximate the exact solution u, where r can be any integer greater than or equal to m. Unlike the interior penalty method in Gudi and Neilan [IMA J. Numer. Anal.31 (2011) 1734–1753], we avoid computing Dm of numerical solution on each element and high order normal derivatives of numerical solution along mesh interfaces. Therefore our method can be easily implemented. After proving discrete Hm-norm bounded by the natural energy semi-norm associated with our method, we manage to obtain stability and optimal convergence with respect to discrete Hm-norm. The error estimate under the low regularity assumption of the exact solution is also obtained. Numerical experiments validate our theoretical estimate. [ABSTRACT FROM AUTHOR]
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- 2022
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9. p53 amyloid aggregation in cancer: function, mechanism, and therapy.
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Li, Jingzhi, Guo, Ming, Chen, Lin, Chen, Zhuchu, Fu, Ying, and Chen, Yongheng
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AMYLOID , *VON Hippel-Lindau disease , *PRION diseases , *CANCER invasiveness , *NEURODEGENERATION , *AMYLOIDOSIS - Abstract
Similar to neurodegenerative diseases, the concept that tumors are prion like diseases has been proposed in recent years. p53, the most well-known tumor suppressor, has been extensively studied for its expression, mutation, and function in various tumors. Currently, an interesting phenomenon of p53 prion-like aggregation has been found in several tumors, and studies have found that its pathological aggregation may lead to functional alterations and ultimately affect tumor progression. It has been demonstrated that the mechanism of p53 aggregation involves its mutation, domains, isoform, etc. In addition to p53 itself, some other factors, including Zn2+ concentration, pH, temperature and chaperone abnormalities, can also contribute to p53 aggregation. Although there are some studies about the mechanism and role of p53 aggregation and amyloidosis in tumors, there still exist some controversies. In this paper, we review the mechanism of p53 amyloid fibril structure and discuss the characteristics and effects of p53 amyloid aggregation, as well as the pathogenic mechanism leading to the occurrence of aggregation in tumors. Finally, we summarize the various inhibitors targeting p53 aggregation and prion-like behavior. In conclusion, a comprehensive understanding of p53 aggregation can expand our understanding of the causes leading its loss of physiological function and that targeting p53 aggregation might be a promising therapeutic strategy for tumor therapy. [ABSTRACT FROM AUTHOR]
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- 2022
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10. Quality Control and Traceability Framework of Electrochromic Materials Based on Block Chain from the Perspective of Practical Application.
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Wang, Qiyuan, Li, Jingzhi, Zheng, Muhong, Ma, Xie, and Wang, Bin
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ELECTROCHROMIC substances , *BLOCKCHAINS , *FACTORY design & construction , *INTELLIGENT buildings , *PRODUCT improvement , *SUPPLY chains , *QUALITY control - Abstract
In recent years, the research on electrochemical devices, especially the promising electrochromic material, is gradually in a wide range of application. But there is few corresponding research about specific industrial manufacturing. The paper starts from the structure of small and medium-sized intelligent factories and designs a system framework optimized by blockchain technology. It connects the electrochromic material quality control module with the product traceability module through a blockchain-based server, which not only ensures the production quality but also effectively improves the product supply chain, which is significant for the development of the electrochromic field. [ABSTRACT FROM AUTHOR]
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- 2022
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11. Effects of various fertilizers on sediment flocculation in high-sediment water drip irrigation systems.
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Li, Jingzhi, Ma, Changjian, Xiao, Yang, Shen, Yan, Zhang, Kai, and Li, Yunkai
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High-sediment water (HSW) drip irrigation has the potential to address agricultural water shortages. However, the sediment flocculation in HSW causes serious technical and economic problems (e.g., emitter clogging). Fertilizer application has been demonstrated to significantly affect sediment flocculation, but the effects of various types of fertilizers on HSW sediment flocculation remain unclear. This study systematically investigated the effects of 17 types of most commonly used fertilizers (Nitrogen, phosphorus, potassium, calcium, magnesium, iron, etc.), and 4 shear forces (0 Pa, 0.2 Pa, 0.4 Pa, and 0.6 Pa) on the flocculation of HSW sediments. The changes in HSW pH, electric conductivity, Zeta potential, oxidation reduction potential, surface tension and dissolved oxygen were measured. Results showed that 11 types of fertilizer application enhanced sediment flocculation. Potassium sulphate had the highest sediment flocculation capacity, followed by calcium ammonium nitrate, ammonium sulphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium carbonate, calcium chloride, ferrous sulphate, potassium chloride, ammonium bicarbonate, and dipotassium hydrogen phosphate. This was because these fertilizers increased the water cation concentration and decreased the surface charge of sediment particles. Furthermore, only 6 types of fertilizers (i.e., iron sulphate, magnesium chloride, manganese sulphate, ammonium chloride, copper sulphate) reduced sediment flocculation. This was because these fertilizers inhibited the connection and collision between sediment particles, thus reducing the likelihood of sediment flocculation. In addition, a higher shear force can reduce HSW sediment flocculation. However, the six water quality parameters did not have statistically significant correlations with sediment flocculation. This study is of significance for clarifying the effect of fertilizer application on sediment flocculation, with implications for the application and promotion of HSW drip fertigation technology. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Comparison Between Clinically Available Low-Intensity Pulsed Ultrasound (LIPUS) and a Novel Bimodal Acoustic Signal System for Accelerating Fracture Healing.
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Machado, Priscilla, Li, Jingzhi, Blackman, Rachel, Liu, Ji-Bin, Kepler, Christopher K., Fang, Taolin, Muratore, Robert, Winder, Jason H., Winder, Alan A., and Forsberg, Flemming
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FRACTURE healing , *BONE fractures , *ULTRASONIC imaging , *TORSIONAL stiffness , *BONE growth , *LEG , *FIBULA - Abstract
Low-intensity pulsed ultrasound (LIPUS) accelerates fracture healing by stimulating the production of bone callus and the mineralization process. This study compared a novel bimodal acoustic signal (BMAS) device for bone fracture healing to a clinical LIPUS system (EXOGEN; Bioventus, Durham, NC, USA). Thirty rabbits underwent a bilateral fibular osteotomy. Each rabbits’ legs were randomized to receive 20-min treatment daily for 18 days with BMAS or LIPUS. The latter utilizes a longitudinal ultrasonic mode only, while the former employs ultrasound-induced shear stress to promote bone formation. Power Doppler imaging (PDI) was acquired days 0, 2, 4, 7, 11, 14, and 18 post-surgery to monitor treatment response and quantified off-line. X-rays were acquired to evaluate fractures on days 0, 14, 18, and 21. Seventeen rabbits completed the study and were euthanized day 21 post-surgery. The fibulae were analyzed to determine maximum torque, initial torsional stiffness, and angular displacement at failure. ANOVAs and paired t-tests were used to compare pair-wise outcome variables for the two treatment modes on a per rabbit basis. The BMAS system induced better fracture healing with greater stiffness (BMAS 0.21 ± 0.19 versus LIPUS 0.16 ± 0.19 $\text{N}\cdot $ cm/°, ${p} =0.050$) and maximum torque (BMAS 7.84 ± 5.55 versus LIPUS 6.26 ± 3.46 $\text{N}\cdot $ cm, ${p} =0.022$) than the LIPUS system. Quantitative PDI assessments showed a higher amount of vascularity with LIPUS than BMAS on days 4 and 18 (${p} < 0.04$). In conclusion, the novel BMAS technique achieved better bone fracture healing response than the current Food and Drug Administration (FDA)-approved LIPUS system. [ABSTRACT FROM AUTHOR]
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- 2022
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13. Alternating direction based method for optimal control problem constrained by Stokes equation.
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Gao, Yu, Li, Jingzhi, Song, Yongcun, Wang, Chao, and Zhang, Kai
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DISCRETE element method , *FINITE element method , *DISCRETE systems , *STOKES equations , *MULTIPLIERS (Mathematical analysis) - Abstract
We consider the optimal control problems constrained by Stokes equations. It has been shown in the literature, the problem can be discretized by the finite element method to generate a discrete system, and the error estimate has also been established. In this paper, we focus on solving the discrete system by the alternating splitting augmented Lagrangian method, which is a direct extension of alternating direction method of multipliers and possesses a global O (1 / k) \mathcal{O}({1}/{k}) convergence rate. In addition, we propose an acceleration scheme based on the alternating splitting augmented Lagrangian method to improve the efficiency of the algorithm. The error estimates and convergence analysis of our algorithms are presented for several different types of optimization problems. Finally, numerical experiments are performed to verify the efficiency of the algorithms. [ABSTRACT FROM AUTHOR]
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- 2022
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14. Engineering Saccharomyces cerevisiae for high-efficient production of ursolic acid via cofactor engineering and acetyl-CoA optimization.
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Jia, Nan, Li, Jingzhi, Zang, Guowei, Yu, Yuan, Jin, Xiaojv, He, Yuna, Feng, Meilin, Na, Xuemei, Wang, Ying, and Li, Chun
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URSOLIC acid , *SACCHAROMYCES cerevisiae , *ACETYLCOENZYME A , *LOQUAT , *CYTOCHROME P-450 , *LOTUS japonicus , *TRITERPENES - Abstract
Ursolic acid (UA) is an important plant-derived pentacyclic triterpene with many physiological and pharmacological activities. Although the heterologous biosynthesis of UA in microbes has been achieved, the titer is too low to be applied for commercial industrialization. The low efficiency of key enzymes such as cytochrome P450 enzyme (CYP450) and the imbalance between endogenous metabolism and exogenous pathways are considered key elements. To solve the problem, high-efficient CYP450s and its compatible cytochrome P450 reductases (CPRs) were screened and characterized. Ej8656, a CYP450 from Eriobotrya japonica , combined with LjCPR, a CPR from Lotus japonicus , showed the best performance in an engineered α-amyrin producing Saccharomyces cerevisiae with a UA titer of 43.0 mg/L. Furthermore, combining cofactor engineering of NADH/NADPH and optimization of acetyl-CoA supply, UA production was improved to 61.0 mg/L. In addition, fermentation optimization was carried out using the constructed S. cerevisiae and the titer of UA was increased to 90.0 mg/L. Finally, 2.33 g/L UA and 1.21 g/L α-amyrin were obtained after scale-up experiment in a 5 L fermenter. The UA production was 70.0-fold of the original strain WN1, and is the highest titer reported in S. cerevisiae. Our study provides a combined way to improve the efficiency of heterologous biosynthesis of UA and offers new ideas and methods for the efficient synthesis of other triterpenoids. • High-efficient Ej8656 was employed for ursolic acid biosynthesis in S. cerevisiae. • LjCPR from L. japonicus was identified as the most complementary CPR for Ej8656. • Balancing the ratio of NAD(P)H/NAD(P)+ was helpful for ursolic acid production. • The highest production of ursolic acid in microorganisms was achieved. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Sparse signal recovery from phaseless measurements via hard thresholding pursuit.
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Cai, Jian-Feng, Li, Jingzhi, Lu, Xiliang, and You, Juntao
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ALGORITHMS , *COMPRESSED sensing - Abstract
In this paper, we consider the sparse phase retrieval problem, recovering an s -sparse signal x ♮ ∈ R n from m phaseless samples y i = | 〈 x ♮ , a i 〉 | for i = 1 , ... , m. Existing sparse phase retrieval algorithms are usually first-order and hence converge at most linearly. Inspired by the hard thresholding pursuit (HTP) algorithm in compressed sensing, we propose an efficient second-order algorithm for sparse phase retrieval. Our proposed algorithm is theoretically guaranteed to give an exact sparse signal recovery in finite (in particular, at most O (log m + log (‖ x ♮ ‖ 2 / | x min ♮ |)) steps, when { a i } i = 1 m are i.i.d. standard Gaussian random vector with m ∼ O (s log (n / s)) and the initialization is in a neighborhood of the underlying sparse signal. Together with a spectral initialization, our algorithm is guaranteed to have an exact recovery from O (s 2 log n) samples. Since the computational cost per iteration of our proposed algorithm is the same order as popular first-order algorithms, our algorithm is extremely efficient. Experimental results show that our algorithm can be several times faster than existing sparse phase retrieval algorithms. [ABSTRACT FROM AUTHOR]
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- 2022
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16. A highly sensitive immunofluorescence sensor based on bicolor upconversion and magnetic separation for simultaneous detection of fumonisin B1 and zearalenone.
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Li, Jingzhi, Zhao, Xudong, Wang, Yu, Li, Shuang, Qin, Yingkai, Han, Tie, Gao, Zhixian, and Liu, Hui
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MAGNETIC separation , *PHOTON upconversion , *IMMUNOFLUORESCENCE , *FUMONISINS , *ZEARALENONE , *MAGNETIC nanoparticles , *FUSARIUM toxins - Abstract
Mycotoxins cause significant harm to human health, so it is imperative to develop a highly sensitive and easy-to-operate method for the detection of mycotoxins. Herein, a fluorescence-based magnetic separation immunoassay for simultaneous detection of mycotoxins fumonisin B1 and zearalenone is established. The method employed high fluorescent upconversion-nanoparticles(UCNPs) conjugated with biotinylated antigens as upconversion fluoroscent probes. Magnetic nanoparticles(MNPs) immobilized with monoclonal antibodies are used as immune-capture probes. Highly sensitive detection of FB1 and ZEN was achieved based on the luminescence properties of UCNPs and the separation effects of MNPs. The results showed a robust linear correlation between the enhanced fluorescence emission intensity and the logarithmic concentrations of FB1 and ZEN under the optimal conditions (R2(FB1) = 0.9965, R2(ZEN) = 0.9976), and the linear ranges were 0.05–5 ng mL−1. Furthermore, the limits of detection (LOD) were 0.016 ng mL−1 for FB1 and 0.012 ng mL−1 for ZEN. The standard addition method was used to determine the content of FB1 and ZEN in the samples to evaluate the accuracy of the process. The average recoveries were 89.48% to 113.69% and 85.97% to 113.82%, respectively. Compared with the other five mycotoxins, this method had high selectivity. It is expected that the multi-component simultaneous detection can be further realized by using the multicolor labeling characteristics of UCNPs. [ABSTRACT FROM AUTHOR]
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- 2021
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17. Speed of sound gradients due to summer thermal stratification can reduce the detection range of acoustic fish tags: results from a field study in Hamilton Harbour, Ontario.
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Wells, Mathew G., Li, Jingzhi, Flood, Bryan, Kuai, Yulong, Brooks, Jill L., Cooke, Steven J., Semcesen, Patricia, and Midwood, Jonathan D.
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SPEED of sound , *FISH tagging , *SEICHES , *ACOUSTIC models , *FIELD research , *HAMILTON-Jacobi equations , *EMISSION control - Abstract
Understanding detection range is a key factor for the use of acoustic telemetry in fisheries research. Lakes have strong seasonal changes in thermal stratification, as well as short-term changes due to internal seiches. These thermal gradients in lakes imply strong sound-speed gradients that can refract and diverge acoustic signals, leading to acoustic attenuation and smaller detection range. Using field-based range testing and the Bellhop acoustic model, we investigated how changes in stratification lead to changes in detection range within Hamilton Harbour, Ontario, Canada. During the summer stratified period, the detection range was less than 350 m, whereas in the isothermal fall, range was up to 500 m. Range test data from three separate field observations showed a good correlation with Bellhop predictions. Owing to the intense internal seiches in Hamilton Harbour, the stratification in the shallower littoral regions essentially switched between stratified and isothermal conditions over short timescales, which is predicted to lead to high temporal variability in detection range that must be accounted for during the analysis and interpretation of telemetry-derived data. [ABSTRACT FROM AUTHOR]
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- 2021
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18. Determining a Random Schrödinger Operator: Both Potential and Source are Random.
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Li, Jingzhi, Liu, Hongyu, and Ma, Shiqi
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RANDOM operators , *SCHRODINGER operator , *INVERSE problems , *OPERATOR theory , *BACKSCATTERING , *INVERSE scattering transform , *PSEUDODIFFERENTIAL operators - Abstract
We study an inverse scattering problem associated with a Schrödinger system where both the potential and source terms are random and unknown. The well-posedness of the forward scattering problem is first established in a proper sense. We then derive two unique recovery results in determining the rough strengths of the random source and the random potential, by using the corresponding far-field data. The first recovery result shows that a single realization of the passive scattering measurements uniquely recovers the rough strength of the random source. The second one shows that, by a single realization of the backscattering data, the rough strength of the random potential can be recovered. The ergodicity is used to establish the single realization recovery. The asymptotic arguments in our study are based on techniques from the theory of pseudodifferential operators and microlocal analysis. [ABSTRACT FROM AUTHOR]
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- 2021
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19. Transcranial Color-Coded Sonography Criteria for Moderate and Severe Middle Cerebral Artery Stenosis.
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Liu, Ran, Li, Jingzhi, Hua, Yang, Yang, Jie, Zhao, Yue, Tian, Xiaojie, Ma, Yan, and Zhao, Wenbo
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ARTERIAL stenosis , *CEREBRAL arteries , *DIGITAL subtraction angiography , *ULTRASONIC imaging , *FLOW velocity , *ARTERIAL occlusions , *COLOR Doppler ultrasonography , *CROSS-sectional method , *STENOSIS , *TRANSCRANIAL Doppler ultrasonography , *RETROSPECTIVE studies , *SEVERITY of illness index - Abstract
This study aimed to establish optimal criteria for evaluation of moderate (50%-69%) and severe (70%-99%) middle cerebral artery (MCA) stenosis with transcranial color-coded sonography (TCCS). A total of 375 cases provided 409 TCCS/digital subtraction angiography vessel pairs. Peak systolic velocity (PSV), end-diastolic velocity (EDV) and mean flow velocity (MFV) of the MCA were measured. The stenotic/distal MFV ratios (SDRs) were calculated. With digital subtraction angiography as a reference, for 50%-69% MCA stenosis, the optimal combined criteria were PSV ≥180 cm/s (sensitivity 95.7%, specificity 64.9% and overall accuracy 69.7%); EDV ≥75 cm/s (90.0%, 66.4% and 68.7%); MFV ≥110 cm/s (95.7%, 64.0% and 69.4%); and SDR ≥2.5 (88.6%, 71.3% and 76.3%). Criteria for 70%-99% MCA stenosis were PSV ≥240 cm/s (93.5%, 89.9% and 85.5%); EDV ≥100 cm/s (96.8%, 89.0% and 87.3%); MFV≥160 cm/s (91.9%, 92.8% and 92.2%); and SDR ≥4 (87.1%, 92.2% and 91.4%). Parameters of the MCA detected by TCCS, especially SDR, may increase accuracy in diagnosis of 50%-69% and 70%-99% MCA stenosis. [ABSTRACT FROM AUTHOR]
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- 2021
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20. A novel variational method for 3D viscous flow in flow channel of turbomachines based on differential geometry.
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Ju, Guoliang, Li, Jingzhi, and Li, Kaitai
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CHANNEL flow , *NAVIER-Stokes equations , *OPERATOR equations , *TURBOMACHINES , *COORDINATES , *DIFFERENTIAL geometry , *VISCOUS flow - Abstract
This paper presents a novel variational method for treating three-dimensional rotational Navier-Stokes equations in flow channel of turbomachines. The proposed method establishes a new semi-geodesic coordinate system on the central surface of blades. From the perspective of differential geometry, the system under concern is split into a set of membrane operator equations on two-dimensional manifolds and bending operator equations along hub circle. The third variable of the new coordinate system is approximated by the central difference scheme. We derive a new formulation of two-dimensional Navier-Stokes equations with three components on the manifolds in the variational sense. The well-posedness of the proposed variational formulation is rigorously justified. [ABSTRACT FROM AUTHOR]
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- 2020
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21. Convexification for an inverse parabolic problem.
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Klibanov, Michael V, Li, Jingzhi, and Zhang, Wenlong
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INVERSE problems , *NUMERICAL functions , *GLOBAL analysis (Mathematics) - Abstract
A convexification-based numerical method for a coefficient inverse problem for a parabolic PDE is presented. The key element of this method is the presence of the so-called Carleman weight function in the numerical scheme. Convergence analysis ensures the global convergence of this method, as opposed to the local convergence of the conventional least squares minimization techniques. Numerical results demonstrate a good performance. [ABSTRACT FROM AUTHOR]
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- 2020
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22. Distribution characteristics and enrichment model of valuable elements in coal: An example from the Nangou Mine, Ningwu Coalfield, northern China.
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Hao, Huidi, Li, Jingzhi, Wang, Jinxi, Liu, Yuyang, and Sun, Yuzhuang
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RARE earth metals , *COAL , *COALFIELDS , *COAL mining , *MINES & mineral resources - Abstract
[Display omitted] • Li mostly occurs as adsorption or ion exchange in clay minerals. • The depositional environment of the No. 2 coal alternates between a hydrostatic reducing condition and an anoxic reducing environment. • Multiple geological effects influence the dissolution and migration of element-enriched minerals, resulting in the enrichment of stable components. In order to study the enrichment mechanism and depositional environment of valuable elements, this paper reports new geochemistry and mineralogy data on the No. 2 and No. 5 coals of the Nangou Mine, Ningwu Coalfield. Clay minerals and calcite are the dominant minerals in both the No. 2 and No. 5 coals. Additionally, small amounts of pyrite, quartz, rutile, and zircon are observed under scanning electron microscopy in the No. 5 coal. The studied coals in Nangou Mine are enriched in Li (CC = 8.50 and 5.80, respectively in the No. 2 and No. 5 coal), Zr (CC = 21.87 and 5.53), Nb (CC = 16.97 and 2.54), Hf (CC = 14.00 and 4.19), Ga (CC = 2.56 and 2.41). Li mostly occurs as adsorption or ion exchange in clay minerals, Nb, Zr, Hf, and Ga have organic affinities, rare earth elements and Y are mostly found in residue and organic binding states. The sediment source of the Nangou Mine is characterized by a multi-source area, with the dissolution and migration of element-enriched minerals under the influence of multiple geological effects, leading to the enrichment of valuable elements (Li, Nb, Zr, Ga, and REY). [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
23. On an inverse elastic wave imaging scheme for nearly incompressible materials.
- Author
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Li, Jingzhi, Liu, Hongyu, and Sun, Hongpeng
- Subjects
- *
ELASTIC waves , *WAVENUMBER , *ELASTIC scattering , *DATA dictionaries , *SCATTERING (Physics) - Abstract
This paper is devoted to the algorithmic development of inverse elastic scattering problems. We focus on reconstructing the locations and shapes of elastic scatterers with known dictionary data for the nearly incompressible materials. The scatterers include non-penetrable rigid obstacles and penetrable media, and we use time-harmonic elastic point signals as the incident input waves. The scattered waves are collected in a relatively small backscattering aperture on a bounded surface. A two-stage algorithm is proposed for the reconstruction and only two incident waves of different wavenumbers are required. The unknown scatterer is first approximately located by using the measured data at a small wavenumber, and then the shape of the scatterer is determined by the computed location of the scatterer together with the measured data at a regular wavenumber. The corresponding mathematical principle with rigourous analysis is presented. Numerical tests illustrate the effectiveness and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
24. A priori error estimates of two monolithic schemes for Biot's consolidation model.
- Author
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Gu, Huipeng, Cai, Mingchao, Li, Jingzhi, and Ju, Guoliang
- Subjects
- *
EULER method , *CRANK-nicolson method , *A priori - Abstract
This paper concentrates on a priori error estimates of two monolithic schemes for Biot's consolidation model based on the three‐field formulation introduced by Oyarzúa et al. (SIAM J Numer Anal, 2016). The spatial discretizations are based on the Taylor–Hood finite elements combined with Lagrange elements for the three primary variables. We employ two different schemes to discretize the time domain. One uses the backward Euler method, and the other applies the combination of the backward Euler and Crank‐Nicolson methods. A priori error estimates show that both schemes are unconditionally convergent with optimal error orders. Detailed numerical experiments are presented to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. Microgrid energy dispatching for industrial zones with renewable generations and electric vehicles via stochastic optimization and learning.
- Author
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Zhang, Kai, Li, Jingzhi, Yan, Wanfeng, and He, Zhubin
- Subjects
- *
ELECTRIC vehicles , *STOCHASTIC learning models , *ENERGY consumption , *ENERGY storage , *MICROGRIDS - Abstract
In this paper, a stochastic optimization framework is proposed to address the microgrid energy dispatching problem with random renewable generation and vehicle activity pattern, which is closer to the practical applications. The patterns of energy generation, consumption and storage availability are all random and unknown at the beginning, and the microgrid controller design (MCD) is formulated as a Markov decision process (MDP). Hence, an online learning-based control algorithm is proposed for the microgrid, which could adapt the control policy with increasing knowledge of the system dynamics and converges to the optimal algorithm. We adopt the linear approximation idea to decompose the original value functions as the summation of each per-battery value function. As a consequence, the computational complexity is significantly reduced from exponential growth to linear growth with respect to the size of battery states. Monte Carlo simulation of different scenarios demonstrates the effectiveness and efficiency of our algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
26. Overexpression of ARO10 in pdc5Δmutant resulted in higher isobutanol titers in Saccharomyces cerevisiae.
- Author
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Li, Jingzhi, Feng, Ruiqi, Wen, Zhihui, and Zhang, Aili
- Subjects
- *
ISOBUTANOL , *PYRUVATE decarboxylase , *SACCHAROMYCES cerevisiae , *FERMENTATION , *DELETION mutation - Abstract
To investigate effects of different pyruvate decarboxylases on isobutanol titers in Saccharomyces cerevisiae, single-gene deletion of the three PDCs genes encoding pyruvate decarboxylases were constructed in this study. In addition, we over-expressed Ilv2, which catalyzed the first step in the valine synthetic pathway, and Bat2, which was the cytoplasmic branched-chain amino-acid aminotransferase that catalyzed L-valine to 2-ketoisovalerate, to increase isobutanol production in the genetically modified strains. Our results showed that knockout of PDC5 were one of the main factors among the three PDC genes for improving isobutanol titers in S. cerevisiae. Additionally, we found that deletion of PDC5 in strain carrying overexpressed ILV2 and ARO10 resulted in 8-fold higher isobutanol productivity as compared to the control strain in micro-aerobic fermentations. Our results also suggested that engineered strain pdc5ΔpILV2 pARO10 generated lower ethanol titers and higher acetate acid titers than the control strain, while the growth rate and glucose consumption rate of engineered strain pdc5ΔpILV2 pARO10 were slightly lower than that of the control strain. Meanwhile, the biomass concentration of pdc5ΔpILV2 pARO10 decreased dramatically than that of the control strain. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
27. Numerical solution of the 3-D travel time tomography problem.
- Author
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Klibanov, Michael V., Li, Jingzhi, and Zhang, Wenlong
- Subjects
- *
TOMOGRAPHY - Abstract
The first numerical solution of the 3-D travel time tomography problem is presented. The globally convergent convexification numerical method is applied. • The first numerical solution of the Travel Time Tomography Problem in the 3D case. • Globally convergent convexification numerical method is the key. • Rigorous convergence analysis based on a Carleman estimate. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
28. Crystal structures of Hsp104 N-terminal domains from Saccharomyces cerevisiae and Candida albicans suggest the mechanism for the function of Hsp104 in dissolving prions.
- Author
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Li, Jingzhi, Sha, Bingdong, Wang, Peng, Weaver, Clarissa, and Lucius, Aaron
- Subjects
- *
HEAT shock proteins , *CRYSTAL structure , *PEPTIDES - Abstract
Hsp104 is a yeast member of the Hsp100 family which functions as a molecular chaperone to disaggregate misfolded polypeptides. To understand the mechanism by which the Hsp104 N-terminal domain (NTD) interacts with its peptide substrates, crystal structures of the Hsp104 NTDs from Saccharomyces cerevisiae (ScHsp104NTD) and Candida albicans (CaHsp104NTD) have been determined at high resolution. The structures of ScHsp104NTD and CaHsp104NTD reveal that the yeast Hsp104 NTD may utilize a conserved putative peptide-binding groove to interact with misfolded polypeptides. In the crystal structures ScHsp104NTD forms a homodimer, while CaHsp104NTD exists as a monomer. The consecutive residues Gln105, Gln106 and Lys107, and Lys141 around the putative peptide-binding groove mediate the monomer-monomer interactions within the ScHsp104NTD homodimer. Dimer formation by ScHsp104NTD suggests that the Hsp104 NTD may specifically interact with polyQ regions of prion-prone proteins. The data may reveal the mechanism by which Hsp104 NTD functions to suppress and/or dissolve prions. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
29. The ER stress sensor PERK luminal domain functions as a molecular chaperone to interact with misfolded proteins.
- Author
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Wang, Peng, Li, Jingzhi, and Sha, Bingdong
- Subjects
- *
ENDOPLASMIC reticulum , *MOLECULAR chaperones , *CONFORMATIONAL analysis , *CRYSTAL structure , *PROTEIN folding - Abstract
PERK is one of the major sensor proteins which can detect the protein-folding imbalance generated by endoplasmic reticulum (ER) stress. It remains unclear how the sensor protein PERK is activated by ER stress. It has been demonstrated that the PERK luminal domain can recognize and selectively interact with misfolded proteins but not native proteins. Moreover, the PERK luminal domain may function as a molecular chaperone to directly bind to and suppress the aggregation of a number of misfolded model proteins. The data strongly support the hypothesis that the PERK luminal domain can interact directly with misfolded proteins to induce ER stress signaling. To illustrate the mechanism by which the PERK luminal domain interacts with misfolded proteins, the crystal structure of the human PERK luminal domain was determined to 3.2 Å resolution. Two dimers of the PERK luminal domain constitute a tetramer in the asymmetric unit. Superimposition of the PERK luminal domain molecules indicated that the β-sandwich domain could adopt multiple conformations. It is hypothesized that the PERK luminal domain may utilize its flexible β-sandwich domain to recognize and interact with a broad range of misfolded proteins. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
30. Robust and efficient estimation with weighted composite quantile regression.
- Author
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Jiang, Xuejun, Li, Jingzhi, Xia, Tian, and Yan, Wanfeng
- Subjects
- *
QUANTILE regression , *ROBUST statistics , *PARAMETER estimation , *NONLINEAR statistical models , *MAXIMUM likelihood statistics , *ALGORITHMS - Abstract
In this paper we introduce a weighted composite quantile regression (CQR) estimation approach and study its application in nonlinear models such as exponential models and ARCH-type models. The weighted CQR is augmented by using a data-driven weighting scheme. With the error distribution unspecified, the proposed estimators share robustness from quantile regression and achieve nearly the same efficiency as the oracle maximum likelihood estimator (MLE) for a variety of error distributions including the normal, mixed-normal, Student’s t , Cauchy distributions, etc. We also suggest an algorithm for the fast implementation of the proposed methodology. Simulations are carried out to compare the performance of different estimators, and the proposed approach is used to analyze the daily S&P 500 Composite index, which verifies the effectiveness and efficiency of our theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
31. Recovering a polyhedral obstacle by a few backscattering measurements.
- Author
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Li, Jingzhi and Liu, Hongyu
- Subjects
- *
POLYHEDRAL functions , *BACKSCATTERING , *NUMERICAL analysis , *SOUND waves , *DATA analysis - Abstract
We propose an inverse scattering scheme of recovering a polyhedral obstacle in R n , n = 2 , 3 , by only a few high-frequency acoustic backscattering measurements. The obstacle could be sound-soft or sound-hard. It is shown that the modulus of the far-field pattern in the backscattering aperture possesses a certain local maximum behavior, from which one can determine the exterior normal directions of the front sides/faces. Then by using the phaseless backscattering data corresponding to a few incident plane waves with suitably chosen incident directions, one can determine the exterior unit normal vector of each side/face of the obstacle. After the determination of the exterior unit normals, the recovery is reduced to a finite-dimensional problem of determining a location point of the obstacle and the distance of each side/face away from the location point. For the latter reconstruction, we need to make use of the far-field data with phases. Numerical experiments are also presented to illustrate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
32. The structure of Tim50(164-361) suggests the mechanism by which Tim50 receives mitochondrial presequences.
- Author
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Li, Jingzhi and Sha, Bingdong
- Subjects
- *
PROTEINS , *CRYSTALLOGRAPHY , *HYDROPHOBIC surfaces , *MITOCHONDRIA , *N-terminal residues - Abstract
Mitochondrial preproteins are transported through the translocase of the outer membrane (TOM) complex. Tim50 and Tim23 then transfer preproteins with N-terminal targeting presequences through the intermembrane space (IMS) across the inner membrane. The crystal structure of the IMS domain of Tim50 [Tim50(164-361)] has previously been determined to 1.83 Å resolution. Here, the crystal structure of Tim50(164-361) at 2.67 Å resolution that was crystallized using a different condition is reported. Compared with the previously determined Tim50(164-361) structure, significant conformational changes occur within the protruding β-hairpin of Tim50 and the nearby helix A2. These findings indicate that the IMS domain of Tim50 exhibits significant structural plasticity within the putative presequence-binding groove, which may play important roles in the function of Tim50 as a receptor protein in the TIM complex that interacts with the presequence and multiple other proteins. More interestingly, the crystal packing indicates that helix A1 from the neighboring monomer docks into the putative presequence-binding groove of Tim50(164-361), which may mimic the scenario of Tim50 and the presequence complex. Tim50 may recognize and bind the presequence helix by utilizing the inner side of the protruding β-hairpin through hydrophobic interactions. Therefore, the protruding β-hairpin of Tim50 may play critical roles in receiving the presequence and recruiting Tim23 for subsequent protein translocations. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
33. An iterative decoupled algorithm with unconditional stability for Biot model.
- Author
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Gu, Huipeng, Cai, Mingchao, and Li, Jingzhi
- Subjects
- *
EXTRAPOLATION , *ALGORITHMS - Abstract
This paper is concerned with numerical algorithms for Biot model. By introducing an intermediate variable, the classical 2-field Biot model is written into a 3-field formulation. Based on such a 3-field formulation, we propose a coupled algorithm, some time-extrapolation based decoupled algorithms, and an iterative decoupled algorithm. Our focus is the analysis of the iterative decoupled algorithm. It is shown that the convergence of the iterative decoupled algorithm requires no extra assumptions on physical parameters or stabilization parameters. Numerical experiments are provided to demonstrate the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. Uniqueness in determining refractive indices by formally determined far-field data.
- Author
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Hu, Guanghui, Li, Jingzhi, and Liu, Hongyu
- Subjects
- *
REFRACTIVE index , *FRAUNHOFER region (Electromagnetism) , *DATA analysis , *EIGENVALUES , *PROBLEM solving , *MATHEMATICAL analysis - Abstract
We present two uniqueness results for the inverse problem of determining an index of refraction by the corresponding acoustic far-field measurement encoded into the scattering amplitude. The first one is a local uniqueness in determining a variable index of refraction by the fixed incident-direction scattering amplitude. The inverse problem is formally posed with such measurement data. The second one is a global uniqueness in determining a constant refractive index by a single far-field measurement. The arguments are based on the study of certain non-self-adjoint interior transmission eigenvalue problems. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
35. Regularized Transformation-Optics Cloaking for the Helmholtz Equation: From Partial Cloak to Full Cloak.
- Author
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Li, Jingzhi, Liu, Hongyu, Rondi, Luca, and Uhlmann, Gunther
- Subjects
- *
MATHEMATICAL regularization , *MATHEMATICAL transformations , *HELMHOLTZ equation , *APPROXIMATION theory , *SCATTERING (Physics) - Abstract
We develop a very general theory on the regularized approximate invisibility cloaking for the wave scattering governed by the Helmholtz equation in any space dimensions $${N \geq 2}$$ via the approach of transformation optics. There are four major ingredients in our proposed theory: (1) The non-singular cloaking medium is obtained by the push-forwarding construction through a transformation that blows up a subset $${K_\varepsilon}$$ in the virtual space, where $${\varepsilon \ll 1}$$ is an asymptotic regularization parameter. $${K_\varepsilon}$$ will degenerate to K as $${\varepsilon \rightarrow +0}$$ , and in our theory K could be any convex compact set in $${\mathbb{R}^N}$$ , or any set whose boundary consists of Lipschitz hypersurfaces, or a finite combination of those sets. (2) A general lossy layer with the material parameters satisfying certain compatibility integral conditions is employed right between the cloaked and cloaking regions. (3) The contents being cloaked could also be extremely general, possibly including, at the same time, generic mediums and, sound-soft, sound-hard and impedance-type obstacles, as well as some sources or sinks. (4) In order to achieve a cloaking device of compact size, particularly for the case when $${K_\varepsilon}$$ is not 'uniformly small', an assembly-by-components, the (ABC) geometry is developed for both the virtual and physical spaces and the blow-up construction is based on concatenating different components. Within the proposed framework, we show that the scattered wave field $${u_\varepsilon}$$ corresponding to a cloaking problem will converge to u as $${\varepsilon \rightarrow +0}$$ , with u being the scattered wave field corresponding to a sound-hard K. The convergence result is used to theoretically justify the approximate full and partial invisibility cloaks, depending on the geometry of K. On the other hand, the convergence results are conducted in a much more general setting than what is needed for the invisibility cloaking, so they are of significant mathematical interest for their own sake. As for applications, we construct three types of full and partial cloaks. Some numerical experiments are also conducted to illustrate our theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
36. TGF-β2 and TGF-β1 differentially regulate the odontogenic and osteogenic differentiation of mesenchymal stem cells.
- Author
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Li, Jingzhi, Ge, Lihong, Zhao, Yuming, Zhai, Yue, Rao, Nanquan, Yuan, Xiaojing, Yang, Jie, Li, Jing, and Yu, Shi
- Subjects
- *
MESENCHYMAL stem cell differentiation , *MESENCHYMAL stem cells , *IMMUNOSTAINING - Abstract
To explore the effects of transforming growth factor-β2 (TGF-β2) and TGF-β1 on the odontogenic and osteogenic differentiation of mesenchymal stem cells (MSCs). We used lentiviral transduction to knock down TGF-β1 or TGF-β2 in stem cells from dental apical papilla (SCAPs), and to generate bone marrow mesenchymal stem cells (BMSCs) with overexpression of TGF-β1 or TGF-β2. We investigated the odontogenic and osteogenic differentiation abilities of these transductants in vitro and in vivo. In vitro , TGF-β2 knockdown in SCAPs reduced the expression of odontoblast-related markers DSPP and DMP-1, and increased the expression of osteoblast-related markers OCN and RUNX-2. Conversely, TGF-β1 knockdown had the opposite effects. TGF-β2 overexpression promoted expression of odontoblast-related markers in BMSCs at early differentiation, but inhibited the expression of odontoblast-related markers at later stages. TGF-β2 overexpression attenuated expression of osteogenic-related markers in BMSCs, while TGF-β1 overexpression enhanced odontoblast-related and osteoblast-related markers. SCAP or BMSC transductants were transplanted underneath kidneys in vivo. Masson staining showed that knockdown of TGF-β1, but not TGF-β2 promoted the expression of type I collagen in SCAPs. Immunohistochemical staining showed that TGF-β2 knockdown inhibited DSPP expression in SCAPs, but TGF-β1 knockdown had no obvious effect on DSPP expression. In vivo , TGF-β1 overexpression and TGF-β2 overexpression had no effect on the expression of type I collagen and DSPP in BMSCs. TGF-β2 promotes odontogenic differentiation of SCAPs and attenuates osteogenic differentiation of SCAPs and BMSCs. TGF-β1 promotes osteogenic differentiation of BMSCs and plays a complex role in regulating odontogenic differentiation of MSCs. • TGF-β2 promoted the odontogenic differentiation of SCAPs. • TGF-β2 attenuated osteogenic differentiation of SCAPs and BMSCs. • TGF-β1 promoted the osteogenic differentiation of BMSCs. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
37. Recovering complex elastic scatterers by a single far-field pattern.
- Author
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Hu, Guanghui, Li, Jingzhi, and Liu, Hongyu
- Subjects
- *
MATHEMATICAL bounds , *PROBLEM solving , *ELASTICITY , *ELECTRONIC linearization , *NONLINEAR theories - Abstract
Abstract: We consider the inverse scattering problem of reconstructing multiple impenetrable bodies embedded in an unbounded, homogeneous and isotropic elastic medium. The inverse problem is nonlinear and ill-posed. Our study is conducted in an extremely general and practical setting: the number of scatterers is unknown in advance; and each scatterer could be either a rigid body or a cavity which is not required to be known in advance; and moreover there might be components of multiscale sizes presented simultaneously. We develop several locating schemes by making use of only a single far-field pattern, which is widely known to be challenging in the literature. The inverse scattering schemes are of a totally “direct” nature without any inversion involved. For the recovery of multiple small scatterers, the nonlinear inverse problem is linearized and to that end, we derive sharp asymptotic expansion of the elastic far-field pattern in terms of the relative size of the cavities. The asymptotic expansion is based on the boundary-layer-potential technique and the result obtained is of significant mathematical interest for its own sake. The recovery of regular-size/extended scatterers is based on projecting the measured far-field pattern into an admissible solution space. With a local tuning technique, we can further recover multiple multiscale elastic scatterers. [Copyright &y& Elsevier]
- Published
- 2014
- Full Text
- View/download PDF
38. Enhanced multilevel linear sampling methods for inverse scattering problems.
- Author
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Li, Jingzhi, Liu, Hongyu, and Wang, Qi
- Subjects
- *
MULTILEVEL models , *LINEAR statistical models , *NUMERICAL analysis , *OPTIMAL control theory , *ROBUST control , *INVERSE scattering transform - Abstract
Abstract: We develop two enhanced techniques for the multilevel linear sampling method (MLSM) proposed in [32] for inverse scattering problems. Under some practical situations, the MLSM suffers certain undesirable “breakage cells” problem. We propose to avoid the curse of “breakage cells” by incorporating “expanding” and “searching” techniques. The new techniques are shown to significantly improve the robustness of the MLSM, and meanwhile they possess the same optimal computational complexity as the MLSM. Numerical experiments are presented to illustrate the promising features of the enhanced MLSMs. [Copyright &y& Elsevier]
- Published
- 2014
- Full Text
- View/download PDF
39. First order second moment analysis for stochastic interface problems based on low-rank approximation.
- Author
-
Harbrecht, Helmut and Li, Jingzhi
- Subjects
- *
STOCHASTIC analysis , *TAYLOR'S series , *NUMERICAL analysis , *ERROR analysis in mathematics , *FINITE element method , *FINITE difference method , *MATHEMATICAL decomposition - Abstract
In this paper, we propose a numerical method to solve stochastic elliptic interface problems with random interfaces. Shape calculus is first employed to derive the shape-Taylor expansion in the framework of the asymptotic perturbation approach. Given the mean field and the two-point correlation function of the random interface, we can thus quantify the mean field and the variance of the random solution in terms of certain orders of the perturbation amplitude by solving a deterministic elliptic interface problem and its tensorized counterpart with respect to the reference interface. Error estimates are derived for the interface-resolved finite element approximation in both, the physical and the stochastic dimension. In particular, a fast finite difference scheme is proposed to compute the variance of random solutions by using a low-rank approximation based on the pivoted Cholesky decomposition. Numerical experiments are presented to validate and quantify the method. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
40. Reconstructing acoustic obstacles by planar and cylindrical waves.
- Author
-
Li, Jingzhi, Liu, Hongyu, Sun, Hongpeng, and Zou, Jun
- Subjects
- *
WAVE mechanics , *STATISTICAL sampling , *BOUNDARY value problems , *MATHEMATICAL mappings , *OPERATOR theory , *NUMERICAL analysis , *INVERSE scattering transform - Abstract
In this paper, we develop a novel method of reconstructing acoustic obstacles in R2, which follows a similar spirit of the linear sampling method originated by Colton and Kirsch. The reconstruction scheme makes use of the near-field measurements encoded into the boundary Dirichlet-to-Neumann map or the Neumann-to-Dirichlet map. Both the plane waves and cylindrical waves are shown to meet the reconstruction purpose. Rigorous mathematical justification of the reconstruction scheme is established. The mapping properties of the newly introduced function operators involved in the reconstruction scheme are established. These results are of significant mathematical interests for their own sake. Moreover, due to the distinct properties of the function operators, the indictor function in the proposed reconstruction scheme exhibits completely different behaviors from those having been established for the indictor function in the original linear sampling method for inverse scattering problems. Numerical experiments are presented to illustrate the effectiveness of the proposed reconstruction scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
41. Universal extension for Sobolev spaces of differential forms and applications
- Author
-
Hiptmair, Ralf, Li, Jingzhi, and Zou, Jun
- Subjects
- *
SOBOLEV spaces , *DIFFERENTIAL forms , *OPERATOR theory , *MATHEMATICAL analysis , *PROOF theory , *EXISTENCE theorems - Abstract
Abstract: This article is devoted to the construction of a family of universal extension operators for the Sobolev spaces of differential forms of degree l () in a Lipschitz domain (, ) for any . It generalizes the construction of the first universal extension operator for standard Sobolev spaces , , on Lipschitz domains, introduced by Stein [E.M. Stein, Singular Integrals and Differentiability Properties of Functions, Princeton University Press, NJ, 1970, Theorem 5, p. 181]. We adapt Steinʼs idea in the form of integral averaging over the pullback of a parametrized reflection mapping. The new theory covers extension operators for and in as special cases for , respectively. Of considerable mathematical interest in its own right, the new theoretical results have many important applications: we elaborate existence proofs for generalized regular decompositions. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
42. Enhanced approximate cloaking by SH and FSH lining.
- Author
-
Li, Jingzhi, Liu, Hongyu, and Sun, Hongpeng
- Subjects
- *
APPROXIMATION theory , *MATHEMATICAL regularization , *INVERSE problems , *HELMHOLTZ equation , *GROUP schemes (Mathematics) , *NUMERICAL analysis - Abstract
We consider approximate cloaking from a regularization viewpoint introduced in Kohn et al (2008 Inverse Problems 24 015016) for EIT and further investigated in Kohn et al (2010 Commun. Pure Appl. Math. 63 0973-1016) and Liu (2009 Inverse Problems 25 045006) for the Helmholtz equation. The cloaking schemes given by Kohn et al and Liu are shown to be (optimally) within | ln ρ|-1 in 2D and ρ in 3D of perfect cloaking, where ρ denotes the regularization parameter. In this paper, we show that by employing a soundhard layer right outside the cloaked region, one could (optimally) achieve ρN in RN, N ≥ 2, which significantly enhances the near-cloak. We then develop a cloaking scheme by making use of a lossy layer with well-chosen parameters. The lossy-layer cloaking scheme is shown to possess the same cloaking performance as the one with a sound-hard layer. Moreover, it is shown that the lossy layer could be taken as a finite realization of the sound-hard layer. Numerical experiments are also presented to assess the cloaking performances of all the cloaking schemes for comparisons. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
43. The structural plasticity of Tom71 for mitochondrial precursor translocations.
- Author
-
Li, Jingzhi, Cui, Wenjun, and Sha, Bingdong
- Subjects
- *
CRYSTAL structure research , *MATERIAL plasticity , *MITOCHONDRIA , *C-terminal binding proteins , *PROTEIN precursors - Abstract
Mitochondrial precursors are transported through the translocase of the outer membrane (TOM) complex. Tom70/Tom71 is a major surface receptor of the TOM complex for mitochondrial precursors and facilitates Hsp70/Hsp90-escorted precursor translocation into the mitochondrion. Previous structural studies of Tom71 have revealed that it contains an N-terminal and a C-terminal domain and that the two domains may remain in an open conformation when binding to Hsp70/Hsp90. In a newly obtained crystal form of a complex of Tom71 and the Hsp70 C-terminus, the N-terminal domain was found to have rotated about 12° towards the C-terminal domain compared with the previous determined crystal structure of Tom71 in the open conformation. This newly solved structure is defined as the `intermediate conformation'. The domain rearrangements in Tom71 significantly change the surface hydrophobicity and the volume of the precursor-binding pocket. This work suggests that Tom70/Tom71-family members may exhibit structural plasticity from the intermediate conformation to the fully open conformation when complexed with Hsp70/Hsp90. This structural plasticity enables the precursor receptors to accommodate different precursor substrates for mitochondrial translocation. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
44. Optimal a priori estimates for higher order finite elements for elliptic interface problems
- Author
-
Li, Jingzhi, Melenk, Jens Markus, Wohlmuth, Barbara, and Zou, Jun
- Subjects
- *
ESTIMATION theory , *FINITE element method , *BOUNDARY value problems , *ERROR analysis in mathematics , *STOCHASTIC convergence , *APPROXIMATION theory , *INTERPOLATION , *SPLINE theory - Abstract
Abstract: We analyze higher order finite elements applied to second order elliptic interface problems. Our a priori error estimates in the - and -norm are expressed in terms of the approximation order p and a parameter δ that quantifies how well the interface is resolved by the finite element mesh. The optimal p-th order convergence in the -norm is only achieved under stringent assumptions on δ, namely, . Under weaker conditions on δ, optimal a priori estimates can be established in the - and in the -norm, where is a subdomain that excludes a tubular neighborhood of the interface of width . In particular, if the interface is approximated by an interpolation spline of order p and if full regularity is assumed, then optimal convergence orders and p for the approximation in the - and the -norm can be expected but not order p for the approximation in the -norm. Numerical examples in 2D and 3D illustrate and confirm our theoretical results. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
45. The Crystal Structure of the C-terminal Fragment of Yeast Hsp40 Ydj1 Reveals Novel Dimerization Motif for Hsp40
- Author
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Wu, Yunkun, Li, Jingzhi, Jin, Zhongmin, Fu, Zhengqing, and Sha, Bingdong
- Subjects
- *
PROTEINS , *LEAVENING agents , *YEAST , *DIMERS - Abstract
The molecular chaperone Hsp40 functions as a dimer. The dimer formation is critical for Hsp40 molecular chaperone activity to facilitate Hsp70 to refold non-native polypeptides. We have determined the crystal structure of the C-terminal fragment of yeast Hsp40 Ydj1 that is responsible for Ydj1 dimerization by MAD method. The C-terminal fragment of Ydj1 comprises of the domain III of Ydj1 and the Ydj1 C-terminal dimerization motif. The crystal structure indicates that the dimerization motif of type I Hsp40 Ydj1 differs significantly from that of yeast type II Hsp40. The C terminus of type I Hsp40 Ydj1 from one monomer forms β-strands with the domain III from the other monomer in the homo-dimer. The L372 from Ydj1 C terminus inserts its side-chain into a hydrophobic pocket on domain III. The modeled full-length Ydj1 dimer structure reveals that a large cleft is formed between the two monomers. The domain IIs of Ydj1 monomers that contain the zinc-finger motifs points directly against each other. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
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46. The Crystal Structure of the Yeast Hsp40 Ydj1 Complexed with Its Peptide Substrate
- Author
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Li, Jingzhi, Qian, Xinguo, and Sha, Bingdong
- Subjects
- *
YEAST , *PEPTIDES , *GENES , *GENETICS - Abstract
The mechanisms by which Hsp40 functions as a molecular chaperone to recognize and bind nonnative polypeptides is not understood. We have identified a peptide substrate for Ydj1, a member of the type I Hsp40 from yeast. The structure of the Ydj1 peptide binding fragment and its peptide substrate complex was determined to 2.7 A˚ resolution. The complex structure reveals that Ydj1 peptide binding fragment forms an L-shaped molecule constituted by three domains. The domain I exhibits a similar protein folds as domain III while the domain II contains two Zinc finger motifs. The peptide substrate binds Ydj1 by forming an extra β strand with domain I of Ydj1. The Leucine residue in the middle of the peptide substrate GWLYEIS inserts its side chain into a hydrophobic pocket formed on the molecular surface of Ydj1 domain I. The Zinc finger motifs located in the Ydj1 domain II are not in the vicinity of peptide substrate binding site. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
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47. Crystal Structure of the E. coli Hsp100 ClpB N-Terminal Domain
- Author
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Li, Jingzhi and Sha, Bingdong
- Subjects
- *
ESCHERICHIA coli , *PEPTIDES - Abstract
E. coli Hsp100 ClpB can disaggregate denatured polypeptides by employing ATP hydrolysis. The ClpB N-terminal domain (ClpBN) has been proposed to play important roles in ClpB molecular chaperone activities. We have determined the crystal structure of ClpBN to 1.95 A˚ resolution by MAD methods. The ClpBN monomer contains two subdomains that have similar folds. The crystal structure revealed a hydrophobic groove on the molecular surface. We have constructed ClpB mutants in which the hydrophobic residues within the putative peptide binding groove were replaced by glutamine. These ClpB mutants exhibited severe defects in molecular chaperone activity but retained the wild-type ATPase activity. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
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48. Crystal Structure of E. coli Hsp100 ClpB Nucleotide-binding Domain 1 (NBD1) and Mechanistic Studies on ClpB ATPase Activity
- Author
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Li, Jingzhi and Sha, Bingdong
- Subjects
- *
ESCHERICHIA coli , *PROTEIN folding - Abstract
E. coli Hsp100 ClpB was recently identified as a critical part in a multi-chaperone system to play important roles in protein folding, protein transport and degradation in cell physiology. ClpB contains two nucleotide-binding domains (NBD1 and NBD2) within their primary sequences. NBD1 and NBD2 of ClpB can be classified as members of the large ATPase family known as ATPases associated with various cellular activities (AAA). To investigate how ClpB performs its ATPase activities for its chaperone activity, we have determined the crystal structure of ClpB nucleotide-binding domain 1 (NBD1) by MAD method to 1.80 A˚ resolution. The NBD1 monomer structure contains one domain that comprises 11 α-helices and six β-strands. When compared with the typical AAA structures, the crystal structure of ClpB NBD1 reveals a novel AAA topology with six-stranded β-sheet as its core. The N-terminal portion of NBD1 structure has an extra β-strand flanked by two extra α-helices that are not present in other AAA structures. Moreover, the NBD1 structure does not have a C-terminal helical domain as other AAA proteins do. No nucleotide molecule is bound with ClpB NBD1 in the crystal structure probably due to lack of the C-terminal helix domain in the structure. Isothermal titration calorimetry (ITC) studies of ClpB NBD1 and other ClpB deletion mutations showed that either ClpB NBD1 or NBD2 alone does not bind to nucleotides. However, ClpB NBD2 combined with ClpB C-terminal fragment can interact with one ADP or ATP molecule. ITC data also indicated that full-length ClpB could bind two ADP molecules or one ATP analogue ATPγS molecule. Further ATPase activity studies of ClpB and ClpB deletion mutants showed that only wild-type ClpB have ATPase activity. None of ClpB NBD1 domain, NBD2 domain and NBD2 with C-terminal fragment has detectable ATPase activities. On the basis of our structural and mutagenesis data, we proposed a “see-saw” model to illustrate the mechanisms by which ClpB performs its ATPase activities for chaperone functions. [Copyright &y& Elsevier]
- Published
- 2002
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49. Land space simulation of urban agglomerations from the perspective of the symbiosis of urban development and ecological protection: A case study of Changsha-Zhuzhou-Xiangtan urban agglomeration.
- Author
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Li, Jingzhi, Ouyang, Xiao, and Zhu, Xiang
- Subjects
- *
URBAN planning , *URBAN growth , *PUBLIC spaces , *SYMBIOSIS , *ECOLOGICAL impact , *SUSTAINABLE urban development - Abstract
• Ecological impact coefficients and land use protection coefficients are proposed. • The system dynamic model was developed to analyze land space changes under different scenarios. • The coordinated symbiotic scenario would be in a better state compared with the other development scenarios. Simulation of future land space changes in urban agglomerations is a powerful means to optimize regional spatial structure and improve human well-being. This study highlights the equilibrium between urban development and ecological protection and introduces ecological impact coefficient and land use protection coefficient to measure the degree of sustainable land development. The system dynamic model was used to simulate the dynamics of urban development space, ecological space, and urban agricultural space in the Changsha-Zhuzhou-Xiangtan urban agglomeration from 2019 to 2035. Four development scenarios were used in the simulation, namely, status-quo, economic-centric, environment-centric, and coordinated equilibrium. Simulation results show that for the year 2035, urban development space scale would increase by 678.91 km2 under the status quo, increase by 870.12 km2 under the economic-centric scenario, increase by 740.98 km2 under an environment-centric setting, and increase by 775.54 km2 with coordinated equilibrium. The various scenarios would have significant differences in ecological impact and land use protection coefficients, with the environment-centric scenario yielding the highest values for these indicators. The approach presented in this study shows that the needs for urban development can be achieved while also protecting ecological and urban agricultural spaces and that allocation of production, living, and ecological spaces can be optimized using multi-scenario simulation. The development of ecological impact coefficients and land use protection coefficients, as well as the use of different development scenarios, can be used as reference for the more efficient use of land resources areas and the formulation of land-use and spatial planning. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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50. Exploring the heterogeneous effects of riding behaviours and road conditions on delivery rider severities in scooter-style electric bicycle crashes involving vehicles.
- Author
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Ma, Jingfeng, Cao, Qi, Ren, Gang, Yang, Yuanxiang, Deng, Yue, and Li, Jingzhi
- Subjects
- *
ELECTRIC bicycles , *CELL phones , *BICYCLE lanes - Abstract
Delivery riders are more vulnerable than other traffic participants, especially in vehicle-involved delivery crashes. This study aims at identifying the unobserved heterogeneities in different factors, based on 4251 vehicle-scooter-style electric bicycle (SSEB) crashes. First, some potential factors are selected from seven perspectives, and the spatiotemporal characteristics are analysed. Second, a latent class clustering method is proposed to clarify the optimal number of clusters by maximizing the heterogeneities across clusters. Third, partial proportional odds (PPO) models for the whole dataset and sub-datasets are developed to explore the heterogeneities across various clusters. Besides, marginal effects are implemented to quantify the heterogeneities. The results evidence that there are remarkable heterogeneities across different clusters, especially in riding behaviours and road conditions. Several factors only significantly affect particular clusters but not the whole dataset. The PPO models for the sub-datasets perform better in identifying the underlying heterogeneities. The results also highlight the greater roles of riding behaviours and road conditions in delivery SSEB-vehicle crashes. The top five influencing factors are running red light, using cell phones, vehicle type, reverse riding and bike lane (their maximum marginal effects exceeding +35%). The findings could support to mitigate the related crash losses. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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