Dynamics of dissolved organic matter during four storm events in two forest streams: source, export, and implications for harmful disinfection byproduct formation.

Yang, Liyang,Hur, Jin,Lee, Sonmin,Chang, Soon-Woong,Shin, Hyun-Sang Ecomed 2015 Environmental Science and Pollution Research Vol.22 No.12

<P>Dynamics of river dissolved organic matter (DOM) during storm events have profound influences on the downstream aquatic ecosystem and drinking water safety. This study investigated temporal variations in DOM during four storm events in two forest headwater streams (the EH and JH brooks, South Korea) and the impacts on the disinfection byproducts (DBPs) formation potential. The within-event variations of most DOM quantity parameters were similar to the flow rate in the EH but not in the larger JH brook. The dissolved organic carbon (DOC) showed clockwise and counterclockwise hysteresis with the flow rate in the EH and JH brooks, respectively, indicating the importance of both flow path and DOM source pool size in determining the effects of storm events. The stream DOM became less aromatic/humified from the first to the last event in both brooks, probably due to the increasing fresh plant pool and the decreasing leaf litter pool during the course of rainy season. The DOC export during each event increased 1.3-2.7- and 1.1-7.0-fold by stormflows in the EH and JH brooks, respectively. The leaf litter and soil together was the major DOM source, particularly during early events. The enhanced DOM export probably increases the risks of DBPs formation in disinfection, as indicated by a strong correlation observed between DOC and trihalomethanes formation potential (THMFP). High correlations between two humic-like fluorescent components and THMFP further suggested the potential of assessing THMFP with in situ fluorescence sensors during storms.</P>

Combinatorial Engineering of Hybrid Mevalonate Pathways in Escherichia coli for Protoilludene Production

Liyang YANG,Chonglong WANG,Jia ZHOU,Jung-Hun KIM,Seon-Won KIM 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10

Opportunities and Challenges of in vitro Synthetic Biosystem for Terpenoids Production

Yang Liyang,Gong Qiang,Lv Jifang,Zhou Bangyuan,Li Guilan,Guo JianQuan 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.5

Terpenoids are a large variety of natural products with remarkable diverse biological functions, and have a wide range of applications in flavors, pharmaceuticals, biofuels, pigments, and so on. However, limited production of terpenoids from natural resources constrains their use of bulk commodity products. In vivo synthetic biosystem, harnessing living organisms to produce terpenoids, has been broadly used and in-depth reviewed for terpenoids production, which has inherent weaknesses, such as slow reaction rate, low product yield, toxic intermediates, and high separation cost. In vitro synthetic biosystem, harboring numerous enzymes and/or coenzymes assembled into an in vitro enzymatic bioreactions, can obviate part of problems associated with in vivo style. In this review, the general design of in vitro synthetic biosystem is presented with seven supporting examples: mevalonate, isoprene, limonene, pinene, farnesene, amorpha-4,11-diene and taxadiene. The efforts for the large-scale implementation of in vitro synthetic biosystem have been addressed to enzymes engineering, computational modeling and cofactors recycle. The review also discusses the challenges and solutions for the largescale implementation of in vitro synthetic biosystem around enzymes stability and cofactors recycle. This review may suggest in vitro synthetic biosystems become a realistic option for the production of diverse valuable terpenoids, even expand to other commodity chemicals.

Enhanced performance of the methylerythritol phosphate pathway by manipulation of redox reactions relevant to IspC, IspG, and IspH

Zhou, Jia,Yang, Liyang,Wang, Chonglong,Choi, Eui-Sung,Kim, Seon-Won Elsevier 2017 Journal of biotechnology Vol.248 No.-

<P>The 2C-methyl-D-erythritol 4-phosphate (MEP) pathway is a carbon-efficient route for synthesis of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the building blocks of isoprenoids. However, practical application of a native or recombinant MEP pathway for the mass production of isoprenoids in Escherichia coli has been unsatisfactory. In this study, the entire recombinant MEP pathway was established with plasmids and used for the production of an isoprenoid, protoilludene. E. coli harboring the recombinant MEP pathway plasmid (ME) and a protoilludene synthesis pathway plasmid (AO) produced 10.4 mg/L of protoilludene after 48 h of culture. To determine the rate-limiting gene on plasmid ME, each constituent gene of the MEP pathway was additionally overexpressed on the plasmid AO. The additional overexpression of IPP isomerase (IDI) enhanced protoilludene production to 67.4 mg/L. Overexpression of the Fpr and FIdA protein complex, which could mediate electron transfer from NADPH to Fe-S cluster proteins such as IspG and IspH of the MEP pathway, increased protoilludene production to 318.8 mg/L. Given that it is required for IspC as well as IspG/H, the MEP pathway has high demand for NADPH. To increase the supply of NADPH, a NADH kinase from Saccharomyces cerevisiae (tPos5p) that converts NADH to NADPH was introduced along with the deletion of a promiscuous NADPH-dependent aldehyde reductase (YjgB) that consumes NADPH. This resulted in a protoilludene production of 512.7 mg/L. The results indicate that IDI, Fpr-FIdA redox proteins, and NADPH regenerators are key engineering points for boosting the metabolic flux toward a recombinant MEP pathway. (C) 2017 Elsevier B.V. All rights reserved.</P>

Backstepping method based controller design for third-order truck platoon robust to dynamic uncertainty and external disturbance

Jianbo Feng,Liyang He,Yanxue Wang,Jianwei Yang,Hongbin Ren 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

The vehicle platoon is subject to dynamic uncertainty and external disturbance, such as air drag and parameter variation in practice, so lack of consideration for those factors can deteriorate control performance. This paper proposes a nonlinear control algorithm based on a novel adaptive backstepping method to cope with the uncertainty and disturbance. The virtual controller in the backstepping method utilizes only the local information of the individual vehicle, rather than the global state information, in the control algorithm design. A third-order vehicle dynamics model was built to incorporate the nonlinearity and the factor of actuation delay. The fuzzy logic system (FLS) is applied to estimate the nonlinearity in vehicle dynamics to facilitate the adaptive control. Five scenarios with different settings were constructed to verify the control performance in the simulation, which indicates the effectiveness and robustness of the controller to dynamic uncertainty and external disturbance.

DC‑side admittance model of converters with constant power control considering DC‑side voltage fluctuation

Xin Tang,Zhen Li,Yang He,Liyang Wang,Yufei Yue,Wen Wang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.2

In the stability analysis of DC (direct-current) power grids, AC (alternating current)/DC converters are usually treated as linear proportional amplifiers or inertial links. However, this approximation will have a considerable effect on the DC-side impedance model of a constant active power control converter and then affect the accuracy of the stability analysis of DC grids. In this paper, in view of the DC-side of the voltage fluctuations, the DC-side admittance model is established after the nonlinear relationship between the port voltage and the modulation signal function is determined. A comparison is made between the traditional modeling method and the proposed modeling method in the analysis of the phase–frequency characteristics and amplitude–frequency characteristics of the admittance. Results show that the proposed small-signal model can better fit the measured admittance in the low-frequency bands. The proposed admittance model in this paper is further applied to assess the small-signal stability of a DC grid. Finally, PSCAD/EMTDC simulation and lab-scaled prototype experiment are used to verify the correctness and effectiveness of the established admittance model. Results show that the small-signal model deduced in this paper can better fit and measure the admittance in the low-frequency band, and can more accurately judge the stability of the DC system.

Toward Multidrug Transporters in Escherichia coli for a Possible Tolerance Mechanism to Fuel-like Isoprenol

Chonglong WANG,Jung-Hun KIM,Liyang YANG,Asad Ali SHAH,Ju-Eon PARK,Seon-Won KIM 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10

Effects of ruminally degradable starch levels on performance, nitrogen balance, and nutrient digestibility in dairy cows fed low corn-based starch diets

Guobin Luo,Wenbin Xu,Jinshan Yang,Yang Li,Liyang Zhang,Yizhen Wang,Cong Lin,Yonggen Zhang 아세아·태평양축산학회 2017 Animal Bioscience Vol.30 No.5

Objective: This trial was performed to examine the effects of ruminally degradable starch (RDS) levels in total mixed ration (TMR) with low corn-based starch on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows. Methods: Eight multiparous Holstein cows (body weight [BW]: 717±63 kg; days in milk [DIM]: 169±29) were assigned to a crossover design with two dietary treatments: a diet containing 62.3% ruminally degradable starch (% of total starch, low RDS) or 72.1% ruminally degradable starch (% of total starch, high RDS). Changes to the ruminally degradable levels were conducted by using either finely ground corn or steam-flaked corn as the starch component. Results: The results showed that dry matter intake, milk yield and composition in dairy cows were not affected by dietary treatments. The concentration of milk urea nitrogen was lower for cows fed high RDS TMR than low RDS TMR. The whole-tract apparent digestibility of neutral detergent fiber, acid detergent fiber and crude protein decreased, and that of starch increased for cows fed high RDS TMR over those fed low RDS TMR, with no dietary effect on the whole-tract apparent digestibility of dry matter and organic matter. The proportion of urinary N excretion in N intake was lower and that of fecal N excretion in N intake was higher for cows fed high RDS TMR than those fed low RDS TMR. The N secretion in milk and the retention of N were not influenced by the dietary treatments. Total purine derivative was similar in cows fed high RDS TMR and low RDS TMR. Consequently, estimated microbial N flow to the duodenum was similar in cows fed high RDS TMR and low RDS TMR. Conclusion: Results of this study show that ruminally degradable starch levels can influence whole-tract nutrient digestibility and nitrogen balance in dairy cows fed low corn-based starch diets, with no influence on performance.

RGB-D Sensor-based Visual Target Detection and Tracking for an Intelligent Wheelchair Robot in Indoors Environments

Hanzhen Xiao,Zhijun Li,Chenguang Yang,Wang Yuan,Liyang Wang 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.3

The ability to follow or move alongside a person is a necessary skill for an autonomous mobile agent that works with human users. To accomplish such tasks, we develop a new scheme of visual-target de-tection and tracking for a wheelchair robot equipped with Microsoft Kinect that captures RGB images along with per-pixel depth information (RGB-D camera). The speeded-up semi-supervised on-line boosting algorithm is employed to provide the robust description of feature for environments and the target person from RGB images. Based on the environmental Haar-like features, we utilize an ex-tended Kalman filter (EKF) based localization to estimate robot pose. Then obstacle avoidance navigation approach based on η3 spline trajectory planning and optimization are proposed for the wheelchair robot. Finally, the experimental results are provided to demonstrate the effectiveness and feasibility in real world environments.

Simultaneous separation of three isoflavones on oligo-β-cyclodextrin substituted polystyrene-based medium and evaluation adsorption characteristics using AutoDock

Li Yang,Tianwei Tan,Jinyi Luan,Xin Wei,Yongqiang Yang,Wenqing Huang,Zhi Guo,Yujie Wang 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2

The adsorption characteristics between three isoflavones in crude soybean sample and styrene-β-cyclodextrin (S-CD) were studied by molecular mechanics calculations with AutoDock. The discriminatory ability exhibited by S-CD against glycitin, daidzin, and genistin through the differences in the interaction energies and complex geometries could potentially serve for the chromatographic separation. The chromatographic elution order of the three analytes on oligo-β-cyclodextrin substituted polystyrene-based medium (PS-CDP) was predicted depending on the binding free energy values obtained from molecular docking simulations. The experimental results of chromatographic evaluation on PS-CDP were consistent with the simulation prediction. The three isoflavones in sample can be simultaneously separated in one-step under the optimized mobile phase, which consisted of methanol/0.1mM NH4AC=65.0/35.0 (v/v) by PS-CDP column chromatography. A glycitin purity of 95.1% with a recovery of approximate 86.3% was achieved by proper peak cutting, and that of daidzin and genistin was 95.8%, 95.4% and 96.2%, 95.7%, respectively.