Predictive carbon nanotube models using the eigenvector dimension reduction (EDR) method

Zhimin Xi,윤병동 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4

It has been reported that a carbon nanotube (CNT) is one of the strongest materials with its high failure stress and strain. Moreover, the nanotube has many favorable features, such as high toughness, great flexibility, low density, and so on. This discovery has opened new opportunities in various engineering applications, for example, a nanocomposite material design. However, recent studies have found a substantial discrepancy between computational and experimental material property predictions, in part due to defects in the fabricated nanotubes. It is found that the nanotubes are highly defective in many different formations (e.g., vacancy, dislocation, chemical, and topological defects). Recent parametric studies with vacancy defects have found that the vacancy defects substantially affect mechanical properties of the nanotubes. Given random existence of the nanotube defects, the material properties of the nanotubes can be better understood through statistical modeling of the defects. This paper presents predictive CNT models, which enable to estimate mechanical properties of the CNTs and the nanocomposites under various sources of uncertainties. As the first step, the density and location of vacancy defects will be randomly modeled to predict mechanical properties. It has been reported that the eigenvector dimension reduction (EDR) method performs probability analysis efficiently and accurately. In this paper, molecular dynamics (MD) simulation with a modified Morse potential model is integrated with the EDR method to predict the mechanical properties of the CNTs. To demonstrate the feasibility of the predicted model, probabilistic behavior of mechanical properties (e.g., failure stress, failure strain, and toughness) is compared with the precedent experiment results.

Preparation of Interface-Assembled Carbonyl Reductase and Its Application in the Synthesis of S-Licarbazepine in Toluene/Tris-HCl Buffer Biphasic System

( Zhimin Ou ),( Jiahui Xu ),( Lihua Du ),( Lan Tang ),( Yangping Niu ),( Jian Cui ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

In this study, interface-assembled carbonyl reductase (IACR) was prepared and used in the synthesis of S-licarbazepine in a toluene/Tris-HCl biphasic system. The carbonyl reductase (CR) was conjugated with polystyrene to form a surfactant-like structure at the interface of the toluene/Tris-HCl biphasic system. The interface-assembled efficiency of IACR reached 83% when the CR (180 U/mg) and polystyrene concentration were 8 × 10² g/ml and 3.75 × 10³ g/ml, respectively. The conversion reached 95.6% and the enantiometric excess of S-licarbazepine was 98.6% when 3.97 × 10⁶ nmol/l oxcarbazepine was converted by IACR using 6% ethanol as a co-substrate in toluene/Tris-HCl (12.5:10) at 30°C and 43 ×g for 6 h. IACR could be reused efficiently five times.

An Optimization Calculation Method of Wind Farm Energy Storage Capacity based on Economic Dispatch

Zhimin Yin,Qin Chao 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.9

Design and Implementation of an AHRS Based on Gauss Newton and Complementary Filtering Algorithm

ZhiMin Liu,Zhao Kai Ning,Feng Tian,ZhenYue Pang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.8

This paper presents design and implementation of an attitude and heading reference system (AHRS) based on Gauss Newton and Complementary Filtering algorithm (CF). The algorithm uses data measured from the MEMS sensor which contains a three-axis magnetometer, a three-axis angular rate sensor, and a three-axis accelerometer. The filter represents rotations using quaternions rather than Euler angles, which eliminates the long-standing problem of singularities associated with attitude estimation. A process model for rigid body angular motions and angular rate measurements is defined. The process model converts angular rates into quaternion rates, which are integrated to obtain quaternions. The Gauss-Newton iteration algorithm is utilized to find the optimal quaternion that relates the measured accelerations and earth magnetic field in the body coordinate frame to calculated values in the earth coordinate frame. Then fuse the optimal quaternion with the quaternion updated from gyroscope and calculate the attitude angle based on the complementary filtering algorithm . Extensive testing of the filter have proved feasibility and acceptable performance of this AHRS design.

Nonparametric estimation for derivatives of compound distribution

Zhimin Zhang,Chaolin Liu 한국통계학회 2015 Journal of the Korean Statistical Society Vol.44 No.3

The compound random variableNj =1 Xj and its distribution have many applications in actuarial science. In this paper, we consider estimation of the derivative functionals of the compound distribution when the underlying density f of Xj is unknown. The estimator is constructed by Fourier inversion and kernel method. An order bound for the bias and asymptotic expression for the variance are given, and the asymptotic normality and uniform consistency are also discussed. Some simulation studies are presented to illustrate the performance of the estimator under finite sample setting.

Independent Correlation of the C1–2 Cobb Angle With Patient-Reported Outcomes After Correcting Chronic Atlantoaxial Instability

Zhimin Pan,Yanhai Xi,Wei Huang,김긍년,이성,신동아,Kai Huang,Yu Chen,Zhongren Huang,Da He,하윤 대한척추신경외과학회 2019 Neurospine Vol.16 No.2

Objective: To investigate three-planar radiographic results and patient-reported outcomes (PROs) after correcting chronic atlantoaxial instability (AAI) by translaminar screw (TLS) and pedicle screw (PS) fixation, and to explore the potential association of atlantoaxial realignment with PRO improvements. Methods: Twenty-three patients who underwent C1 lateral mass screw (LMS)-C2 TLS and 29 who underwent C1 LMS-C2 PS with ≥2 years of follow-up were retrospectively analyzed. Three-planar (sagittal, coronal, and axial) radiographic parameters were measured. PROs including the Neck Disability Index (NDI), Japanese Orthopaedic Association (JOA) score and the Short Form 36 Physical Component Summary (SF-36 PCS) were documented. Factors potentially associated with PROs were identified. Results: The radiographic parameters significantly changed postoperatively except the C1–2 midlines’ intersection angle in the TLS group (p=0.073) and posterior atlanto-dens interval in both groups (p=0.283, p=0.271, respectively). The difference in bilateral odontoid lateral mass interspaces at last follow-up was better corrected in the TLS group than in the PS group (p=0.010). Postoperative PROs had significantly improved in both groups (all p<0.05). Thereinto, NDI at last follow-up was significantly lower in the TLS group compared with PS group (p=0.013). In addition, blood loss and operative time were obviously lesser in TLS group compared with PS group (p=0.010, p=0.004, respectively). Multivariable regression analysis revealed that a change in C1–2 Cobb angle was independently correlated to PROs improvement (NDI: β=-0.435, p=0.003; JOA score: β=0.111, p=0.033; SF-36 PCS: β=1.013, p=0.024, respectively), also age ≤40 years was independently associated with NDI (β=5.40, p=0.002). Conclusion: Three-planar AAI should be reconstructed by C1 LMS-C2 PS fixation, while sagittal or coronal AAI could be corrected by C1 LMS-C2 TLS fixation. PROs may improve after atlantoaxial reconstruction in patients with chronic AAI. The C1–2 Cobb angle is an independent predictor of PROs after correcting chronic AAI, as is age ≤40 years for postoperative NDI.

3D printed MXene (Ti2AlN)/polycaprolactone composite scaffolds for in situ maxillofacial bone defect repair

Zhimin Xu,Yingxin Zhang,Huanyan Dai,Yu Wang,Yujie Ma,Shuang Tan,Bing Han 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Obtaining a safe and reliable scaffold that can be rapidly fabricated and used for clinical bone defect repairhas always been a challenge. In this study, polycaprolactone (PCL) composite scaffolds with various MXene(Ti2AlN) contents were prepared using 3D printing technology. The effects of different contents of Ti2AlNon the mechanical properties, hydrophilicity, cytocompatibility, and osteogenic differentiation abilitywere systematically studied and analysed. In vitro experiments showed that scaffolds containing 5%Ti2AlN (PCL@5#Ti2AlN) obtained the best cell adhesion and proliferation ability and significantly upregulatedthe alkaline phosphatase (ALP) level. In vivo experiments of tibial defect repair in rats showed thatthe PCL scaffold containing 5% Ti2AlN (PCL@5#Ti2AlN) could significantly promote the formation of newbone, and the experimental results of rabbit maxillofacial bone defect repair further proved that thePCL@5#Ti2AlN scaffold could effectively promote the repair of bone defects. Transcriptome analysis indicatedthat Ti2AlN may promote osteogenic differentiation by the Wnt/b-catenin signaling pathway andcalcium-binding proteins. These findings suggest that Ti2AlN/PCL composite scaffolds with improvedin situ bone repair ability represent an intelligent strategy for bone defect repair.

Characterization of a strong green tissue-specific motif in rice photosystem I gene promoter Ppsak

Zhimin Lin,Jingwan Yan,Huanxin Yan,Feng Wang 한국식물생명공학회 2017 Plant biotechnology reports Vol.11 No.2

Characterization of green tissue-specific promoters helps facilitate genetic improvement in crops. Here, we isolated a novel green tissue-specific expression gene Psak encoding photosystem I protein in rice through RTPCR analysis. The 5′ flanking region from −635 to +60 (transcription start site of Psak as +1) covering parts of Psak gene and its promoter Ppsak was identified as be critical for green tissue-specific expression (including leaves and stems) in rice. Further promoter deletion analyses demonstrated that the promoter region from −559 to −232 was necessary and sufficient for green tissue-specific expression of Psak gene. Histochemical assays showed that the GUS expression of this 267-bp region was highly presented in leaves and stems, but reduced or absent in other tissues examined. The GUS expression level of this core promoter region could be 14.6- to 21.6-fold higher than that of the full-length region of Ppsak promoter in leaves and stems. These results combined with cis-acting elements prediction in Ppsak promoter suggested that the TCT motif located in this promoter played a key role in strong green tissue-specific expression.

A Comparative Study on Physiological Activities of Lager and Ale Brewing Yeasts under Different Gravity Conditions

Zhimin Yu,Mou-Ming Zhao,Huiping Li,Hai-Feng Zhao,Qingli Zhang,Chunyan Wan,Huipin Li 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

High gravity (HG) or very high gravity (VHG)brewing has become popular in modern breweries due to its economic and product quality advantages. However,there are the negative impacts such as the fermentation performance of brewer’s yeast in HG or VHG wort, which are closely related to changes in cell physiological activity. In the present study, 3 kinds of worts, with different gravities, were used to examine the systematic effects on fermentation performance and physiological activity of lager yeast FBY009505 (Saccharomyces pastorianus) and ale yeast FBY0099 (Saccharomyces cerevisiae), as well as the resulting beer flavor. Results showed that the responses of FBY009505 and FBY0099 to the HG or VHG worts were similar. The specific fermentation rate and viability of cropped yeast of FBY009505 and FBY0099 were decreased with increasing wort gravity. The increased wort gravity resulted in the increase of energy charge and the decrease of α-glucosides transport rate and glycolytic enzyme activities. Moreover, the environmental stresses in the HG or VHG wort showed a higher inhibitory activity against α-glucoside transport than glycolytic enzymes. The content of intracellular trehalose and glycerol of FBY009505 and FBY0099 increased with the increase in wort gravity. The results from this study provided a potential means to systematically understand the physiology of brewer’s yeast under HG or VHG conditions. High gravity (HG) or very high gravity (VHG)brewing has become popular in modern breweries due to its economic and product quality advantages. However,there are the negative impacts such as the fermentation performance of brewer’s yeast in HG or VHG wort, which are closely related to changes in cell physiological activity. In the present study, 3 kinds of worts, with different gravities, were used to examine the systematic effects on fermentation performance and physiological activity of lager yeast FBY009505 (Saccharomyces pastorianus) and ale yeast FBY0099 (Saccharomyces cerevisiae), as well as the resulting beer flavor. Results showed that the responses of FBY009505 and FBY0099 to the HG or VHG worts were similar. The specific fermentation rate and viability of cropped yeast of FBY009505 and FBY0099 were decreased with increasing wort gravity. The increased wort gravity resulted in the increase of energy charge and the decrease of α-glucosides transport rate and glycolytic enzyme activities. Moreover, the environmental stresses in the HG or VHG wort showed a higher inhibitory activity against α-glucoside transport than glycolytic enzymes. The content of intracellular trehalose and glycerol of FBY009505 and FBY0099 increased with the increase in wort gravity. The results from this study provided a potential means to systematically understand the physiology of brewer’s yeast under HG or VHG conditions.

A Learning Automata-based Algorithm for Area Coverage Problem in Directional Sensor Networks

( Zhimin Liu ),( Zhangdong Ouyang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.10

Coverage problem is a research hot spot in directional sensor networks (DSNs). However, the major problem affecting the performance of the current coverage-enhancing strategies is that they just optimize the coverage of networks, but ignore the maximum number of sleep sensors to save more energy. Aiming to find an approximate optimal method that can cover maximum area with minimum number of active sensors, in this paper, a new scheduling algorithm based on learning automata is proposed to enhance area coverage, and shut off redundant sensors as many as possible. To evaluate the performance of the proposed algorithm, several experiments are conducted. Simulation results indicate that the proposed algorithm have effective performance in terms of coverage enhancement and sleeping sensors compared to the existing algorithms.