In silico Analysis and Experimental Improvement of Taxadiene Heterologous Biosynthesis in Escherichia coli

Hailin Meng,Yong Wang,Qiang Hua,Siliang Zhang,Xiaoning Wang 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.2

The biosynthesis of terpenoids in heterologous hosts has become increasingly popular. Isopentenyl diphosphate (IPP) is the central precursor of all isoprenoids, and the synthesis can proceed via two separate pathways in different organisms: The 1-deoxylulose 5-phosphate (DXP)pathway and the mevalonate (MVA) pathway. In this study,an in silico comparison was made between the maximum theoretical IPP yields and the thermodynamic properties of the DXP and MVA pathways using different hosts and carbon sources. We found that Escherichia coli and its DXP pathway have the most potential for IPP production. Consequently, codon usage redesign, and combinations of chromosomal engineering and various strains were considered for optimizing taxadiene biosynthesis through the endogenic DXP pathway. A high production strain yielding 876 ± 60 mg/L taxadiene, with an overall volumetric productivity of 8.9 mg/(L × h), was successfully obtained by combining the chromosomal engineered upstream DXP pathway and the downstream taxadiene biosynthesis pathway. This is the highest yield thus far reported for taxadiene production in a heterologous host. These results indicate that genetic manipulation of the DXP pathway has great potential to be used for production of terpenoids, and that chromosomal engineering is a powerful tool for heterologous biosynthesis of natural products.

An Anisotropic Failure Criterion for Cross-anisotropic Soils

Hailin Wang,Hong Sun,Xiurun Ge,Fujun Niu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

Strength anisotropy is an important feature closely related to soil microstructure characteristics. A new anisotropic failure criterion, extended from the Ogawa failure criterion, was developed to describe the strength anisotropy of cross-anisotropic soils. Nonlinearization of the failure curves of the Ogawa failure criterion was introduced to account for the nonlinear failure of cross-anisotropic soils in the meridian plane. Meanwhile, an anisotropic strength function based on fabric tensor was theoretically proposed to modify the failure strength under different loading directions and depositional angles. The evolution of the new anisotropic failure criterion in the deviatoric plane was investigated through a series of parametric studies. All of the undetermined parameters in the new criterion can be readily determined in laboratory tests. Compared with experimental results on several types of soils, the new anisotropic failure criterion showed good performance in strength prediction in the deviatoric plane, as well as predicting the peak friction angle. Finally, a linear theoretical relationship on construction of the anisotropic strength function was also elucidated and discussed. The new anisotropic failure criterion proposed in this paper can effectively predict the strength anisotropy of cross-anisotropic soils under different loading directions and depositional angles.

In silico Improvement of Heterologous Biosynthesis of Erythromycin Precursor 6-Deoxyerythronolide B in Escherichia coli

Hailin Meng,Zhiguo Lu,Yong Wang,Xiaoning Wang,Siliang Zhang 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.3

The heterologous biosynthesis of 6-deoxyerythronolide B (6dEB), a key intermediate in the biosynthesis of erythromycin, has recently been achieved in Escherichia coli, but the experimental product yield remains low. In this study, in silico strategies were adopted to evaluate and improve the biosynthesis of 6dEB in this strain. The theoretical capability of E. coli to produce 6dEB was first evaluated by analyzing the maximum theoretical molar yield (MTMY) of 6dEB utilizing three carbon sources,glucose, propionate and glycerol. Although propionate is presently most often used experimentally, our results indicated that glucose would be the most feasible substrate for 6dEB production from economic and long-term standpoints. Compared with Saccharomyces cerevisiae and Bacillus subtilis, E. coli was found to be a better heterologous host for the biosynthesis of 6dEB due to the higher MTMY value under the same conditions. Two strategies,including a flux distribution comparison analysis (FDCA)and linear minimization of metabolic adjustment based (LMOMA-based) methods, were proposed and employed for in silico strain improvement of 6dEB production, which yielded several potential gene targets for future experimental validation. In a further analysis, increasing the specific growth rate (SGR) or the non-growth associated maintenance (NGAM) was found to decrease the MTMY; while increasing the specific oxygen uptake rate (SOUR) or the specific carbon source uptake rate (SCUR) increased the MTMY. Taken together, our findings identified key factors directly affecting the MTMY of 6dEB production, which will guide future experimental research or even the industrial production of 6dEB.

Macro-micro Performances of Granular Materials Considering the Influences of Density and Stress Path under True Triaxial Conditions: A DEM Investigation

Hailin Wang,Hong Sun,Xiurun Ge,Fujun Niu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.10

The mechanical behaviors of granular materials are dominated by internal structure, which are related to fabric evolution during loading. This study investigated the fabric evolution of granular materials with different densities and stress paths under true triaxial conditions. A series of discrete element numerical simulations with different intermediate principal stress coefficient b were carried out along the constant mean stress p and the constant minor principal stress σ3 stress paths for both loose and dense specimens. The results indicated that the constant-p stress path produced a faster increase in stress ratio than the constant-σ3 stress path at the same b. The effects of specimen density on the peak friction angle are greater than that of stress path. The microscopic analyses revealed that the constant-p stress path facilitates a much more preferential distribution of normal contact force network along the major principal direction. The discrepancies in the peak stress ratio under two stress paths were thus interpreted. The dense specimen will rapidly form a higher anisotropic distribution of the normal contact force network upon shearing, and its anisotropic intensity was almost twice that of the loose specimen at the peak stress state. In addition, a unique relationship between the strong deviatoric fabric ratio and stress ratio was presented. The ratio of the two was approximately 1.0 regardless of stress path, density and b value. Finally, an underlying relationship between the stress components and the whole fabric components at the critical state was confirmed by introducing a new stress tensor. The three principal components (F1, F2 and F3) of the whole fabric tensor can be quantitatively represented with the imposed three principal stress components (σ1, σ2 and σ3) by employing a relationship of F1:F2:F3 = σ10.27:σ20.27:σ30.27. It provides a more comprehensive perspective to analyze the macro-micro performances of granular materials at the critical state.

Influence of Forging Temperature on the Microstructures and Mechanical Properties of a Multi-Directionally Forged Al–Cu–Li Alloy

Hailin He,Kanghua Chen,Youping Yi,Wen You,Yonglin Guo,Bingxiang Wang,Jiaguo Tang,Research Institute of Light Alloy, Central South University,Shiquan Huang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

Optimization of forging process to improve the microstructure and mechanical properties of 2195 Al–Cu–Li alloy forgingsis an urgent issue. In this study, a homogenized 2195 alloy ingot was subjected to multi-directional forging (MDF), annealing,and forging at 500 °C, 420 °C, and 240 °C with a 50% reduction in cross-sectional area, followed by a T8 heat treatment(involving solution, quenching, cold compression, and aging). The microstructural evolution during the process and thefinal mechanical properties in three orthogonal directions were examined. The results showed that the grain structures ofthe alloy were significantly refined after MDF by dynamic recrystallization (DRX), but the structure was thermally unstableand formed coarse grains during subsequent annealing by static recrystallization (SRX). The T8-treated samples forged at500 °C, 420 °C, and 240 °C obtained fine and uniform grain structures by DRX, inhomogeneous grain structures by partialSRX, and uniform, equiaxed grain structures by full SRX, respectively. The average grain size of the forging increased withdecreasing forging temperature because more significant SRX occurred for the forging that was deformed at lower temperatures. The grain structures had minimal influence on precipitation behavior and strength but had a significant influence onelongation. The fine and uniform grain structures improved the elongation; whereas, the inhomogeneous grain structures,which contained extremely large grains, significantly deteriorated the elongation. The uniform, equiaxed grain structuresdecreased the anisotropy in three orthogonal directions and maintained fine elongation even though the average grain sizeof the forging was the largest.

Lithium-ion batteries remaining useful life prediction using Wiener process and unscented particle filter

Wang, Ranran,Feng, Hailin The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1

Remaining useful life (RUL) prediction plays an important role in the prognosis and health management of lithium-ion batteries (LIBs). This paper proposes a new method based on the Wiener process for the RUL prediction of LIBs. Firstly, a state-space model based on the Wiener process is constructed to describe the LIBs degradation process, which considers the four variability sources of the degradation process simultaneously. Then, the model parameters are initialized using maximum likelihood estimation (MLE) and dynamically estimated by an unscented particle filter (UPF) algorithm. Finally, through comparison with other models, the proposed method shows its effectiveness and superiority in describing the degradation process and RUL prediction of LIBs.

THE IMPACT OF CORPORATE SOCIAL RESPONSIBILITY ON NEW PRODUCT DEVELOPMENT PERFORMANCE: MEDIATING EFFECT OF INTERNAL CAPABILITY AND AS WELL AS EXTERNAL NETWORK QUALITY

Hailin Zhang,Xina Yuan,Seongsoo Jang,Xin Wang 글로벌지식마케팅경영학회 2020 Global Marketing Conference Vol.2020 No.11

Experimental and Theoretical Investigation on the Forming Limit of 2024-O Aluminum Alloy Sheet at Cryogenic Temperatures

Chenguang Wang,Youping Yi,Shiquan Huang,Fei Dong,Hailin He,Ke Huang,Yanzhen Jia 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

Cryogenic forming, a new technology used to manufacture aluminum alloy thin-walled parts, has attracted much attentionin recent years. This work presents an experimental and theoretical study of 2024-O aluminum alloy sheet forming limit atcryogenic temperatures and provides an effective method for accurate prediction of forming limit curves (FLCs) at cryogenictemperatures. Uniaxial tensile experiments at different temperatures were carried out between 20 °C and − 196 °C to obtainthe constitutive equation of the material at cryogenic temperatures. The Marciniak–Kuczynski (M–K) model was used topredict FLCs at cryogenic and room temperatures. The constitutive equation and yield functions are used in the model. Theeffects of different yield criteria (Mises, Hill-48, Barlat89, Gotoh, and Yld2000-2d) on the prediction results of FLC areanalyzed. These prediction results were verified by the Nakazima test, and it was found that the Yld2000-2d yield criterion isthe most accurate for FLC prediction. Finally, the M–K model is combined with this criterion to predict the FLC at differenttemperatures. It was found that the lower the temperature, the higher the FLC curve and the better the sheet formability, andthe increase is more obvious at extremely low temperatures.

High Strength Vinegar Fermentation by Acetobacter pasteurianus via Enhancing Alcohol Respiratory Chain

Zhengliang Qi,Hailin Yang,Xiaole Xia,Wu Wang,Xiao-Bin Yu 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.2

Seeking high strength vinegar fermentation byacetic acid bacteria (AAB) is still the mission of vinegarproducers. AAB alcohol respiratory chain, located onintracellular membrane, is directly responsible for vinegarfermentation. In the semi-continuous vinegar fermentationby Acetobacter pasteurianus CICIM B7003, acetificationrate showed positive correlation with the activity of theenzymes in alcohol respiratory chain. Aiming at achievinghigh strength fermentation process, a series of trials weredesigned to raise the activity of AAB alcohol respiratorychain. Finally, acetification was enhanced by adding someprecursors (ferrous ions and β-hydroxybenzoic acid) ofalcohol respiration associated factors and increasing aerationrate (0.14 vvm). As final result, average acetification ratehas been raised to 2.29 ± 0.02 g/L/h, which was 28.7%higher than the original level. Simultaneously, it was foundthat the oxidization of alcohol into acetic acid in AAB cellswas improved by well balancing of three factors: enzymeactivity in alcohol respiratory chain, precursor of ubiquinonebiosynthesis, and aeration rate.

Lack of Association Between the Matrix Metalloproteinase-2 -1306C>T Polymorphism and Breast Cancer Susceptibility: a Meta-analysis

Yang, Lu,Li, Ning,Wang, Siyu,Kong, Yanan,Tang, Hailin,Xie, Xinhua,Xie, Xiaoming Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.12

Background: Since inconsistent results have been reported regarding the relation between the matrix metalloproteinase-2 (MMP-2) -1306C>T polymorphism and susceptibility for breast cancer, we performed a meta-analysis to investigate the issue. Materials and Methods: An internet search of PubMed and EMBASE was performed to identify eligible studies. Pooled odds ratios (ORs) with their corresponding confidence intervals (CIs) were calculated to evaluate any association between MMP-2 -1306C>T polymorphism and breast cancer susceptibility. Results: Nine case-control studies were included in the meta-analysis, involving 9,858 cases and 10,871 controls. Overall, there was no evidence of any association between the MMP-2 -1306C>T polymorphism and breast cancer susceptibility in different genetic models (T-allele vs C-allele: OR=0.95, 95%CI, 0.82-1.10, p=0.49; TT vs CC: OR=1.03, 95%CI, 0.90-1.19, p=0.66; TT+TC vs CC: OR=0.93, 95%CI, 0.78-1.10, p=0.38; TT vs TC+CC: OR=1.02, 95%CI, 0.89-1.17, p=0.77). In the subgroup analysis by ethnicity, CC was associated with a significant increase in breast susceptibility among Latin-Americans in the dominant model (OR=0.61, 95%CI, 0.40-0.93, p=0.02), but the association disappeared in other models. No significant association was observed among Europeans, East Asians and others in different genetic models. In the subgroup analysis by their source of controls, no significant association between MMP-2 -1306C>T polymorphism and breast cancer susceptibility was noted among population-based studies and hospital-based studies in different genetic models. Conclusions: The results of this meta-analysis suggest that MMP-2 -1306C>T polymorphism is not associated with breast cancer susceptibility, although the association among Latin-Americans in the dominant model was significant.