Macrokinetic Model for Gluconobacter oxydans in 2-keto-L-gulonic Acid Mixed Culture

Zhixiong Zhang,Xinjie Zhu,Ping Xie,Junwei Sun,Jingqi Yuan 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.5

A set of kinetic models have been developed for the production of 2-keto-L-gulonic acid from L-sorbose by a mixed culture of Gluconobacter oxydans and Bacillus megaterium. A metabolic pathway is proposed for Gluconobacter oxydans, and a macrokinetic model has been developed for Gluconobacter oxydans, where the balances of some key metabolites, ATP and NADH are taken into account. An unstructured model is proposed for concomitant bacterium Bacillus megaterium. In the macrokinetic model and unstructured model, the mechanism of interaction between Gluconobacter oxydans and Bacillus megaterium is investigated and modeled. The specific substrate uptake rate and the specific growth rate obtained from the macrokinetic model are then coupled into a bioreactor model such that the relationship between the substrate feeding rate and the main state variables, such as the medium volume, the biomass concentrations, the substrate,and the is set up. A closed loop regulator model is introduced to approximate the induction of enzyme pool during lag phase after inoculation. Experimental results demonstrate that the model is able to describe 2-keto-Lgulonic acid fermentation process with reasonable accuracy.

Modeling of Left Ventricular Motion and Hemodynamic Analysis Based on CT Tomography

Zhixiong Li,Liang Qi,Wei Han,Minzu Zhang,Tianci Duan,Yan Qiang 한국유체기계학회 2024 International journal of fluid machinery and syste Vol.17 No.1

Based on Computed Tomography (CT) tomography images of the human heart, a 3D reconstruction and wall optimization of the heart was performed by using Mimics to model the motion of the left ventricular overflow wall. The non-Newtonian blood flow in the left ventricle was numerically simulated using the dynamic mesh technique based on User Defined Functions (UDF) programming of the left ventricular wall motion. When the left ventricle is diastolic, the internal pressure gradually increases, the blood flow structure approximates the physiological blood flow pattern, the rate at the mitral orifice first increases and then decreases, and a local high stress zone appears. When the left ventricle is systolic, the pressure gradient is significant, the internal pressure decreases and the rate at the aortic valve orifice shows a pattern of increasing and then decreasing. The dynamic simulation of left ventricular blood flow provides a feasible technical solution for the fluid dynamics analysis of cardiac physiological and pathological processes

Effect of plant secondary metabolites on common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

Qi Su,Zhixiong ZHOU,Jianmin ZHANG,Caihua SHI,Guohui ZHANG,Zhenyu JIN,Wenkai WANG,Chuanren LI 한국곤충학회 2018 Entomological Research Vol.48 No.1

The effect of various flavonoids, lectins and phenyl β‐D‐glucoside on larval survival, weights and the activities of digestive (total serine protease and trypsin) and detoxifying (esterase and glutathione‐S‐transferase) enzymes of Spodoptera litura larvae at 7 days after treatment was studied through diet incorporation assay. Flavonoids (rutin, chlorogenic acid, quinic acid, caffeic acid, naringenin, quercitin, kaempferol, myricetin, catechin, and ferulic acid) were incorporated in artificial diet at 100, 500 and 1000 ppm, lectins: groundnut leaf lectin (GLL), concavalin A (ConA) and phenyl β‐D‐glucoside at 1, 2 and 5 μg/mL. Flavonoids such as rutin, quercitin and kaempferol at 1000 ppm were more toxic to S. litura larvae than quinic acid, caffeic acid, naringenin, myricetin, catechin, and ferulic acid. Larval growth and development were significantly reduced in S. litura larvae fed on a diet with GLL and ConA at 5 μg/mL compared to the larvae fed at 2 and 1 μg/mL concentrations. The larvae fed on flavonoid‐treated diets showed significant reduction in serine protease, trypsin and esterase activities. The flavonoids such as rutin, chlorogenic acid, quinic acid, naringenin, quercitin, kaempferol and myricetin, and lectins, GLL and ConA can be utilized in insect control programs.

Large-scale Field Tests of the Performance of Geogrid-reinforced Piled Embankment over Soft Soil

Gang Wang,Xianwei Zhang,Xinyu Liu,Zhixiong Chang,Zhihai Liu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2

When constructing superstructures on soft soils, geogrid-reinforced embankments and pile-supported embankments are used widely to improve the soft foundation and prevent issues including excessive settlements and large lateral displacements, so it is crucial to understand and evaluate their performance systematically. This study focuses on a case of piled embankments for a motor-racing circuit under construction in China. Two large-scale field tests of pile-supported embankments with and without reinforcement were carried out to investigate the effect of geosynthetic reinforcement on the improvement of embankments. During long-term monitoring, instruments in the test sites measured earth pressures, settlements, lateral displacements, and pore water pressures, and the performances of the reinforced or unreinforced embankments were examined. Test results from the two test sites under similar loading are compared, and it is concluded that the geosynthetic-reinforcement considerably influences the improvement of load transfer and diminishment of total and differential settlements. The lateral restraint provided by the geogrids also reduced the lateral soil displacement and the influence of subsoil depth. The smaller excessive pore water pressures in the site with reinforcement were associated with the enhanced load transfer due to the geogrids. This study provides an important reference for the design and construction of this circuit and other related projects.

The Formation of Magnetite Nanoparticle in Ordered System of the Soybean Lecithin

Li, Tiefu,Deng, Yingjie,Song, Xiaoping,Jin, Zhixiong,Zhang, Ying Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.7

A method of preparation of magnetite nanoparticles in ordered systems, as in vesicle and microemulsion, consisting of soybean lecithin and water has been introduced. The size of magnetite grain was controlled by the content of soybean lecithin and size of liposomes in the systems. It was found by experiment that magnetite nanoparticles were formed inside the double layer vesicles. The magnetite nanoparticles were separated by magnetic separation and centrifugation and the dispersion of the magnetite nanoparticles prepared at 10% (w/w) soybean lecithin was particularly stable. The formation of pure magnetite nanoparticles was confirmed by analyses of XRD and electron diffraction pattern.

Effects of dietary leucine supplementation on the hepatic mitochondrial biogenesis and energy metabolism in normal birth weight and intrauterine growth-retarded weanling piglets

Weipeng Su,Wen Xu,Hao Zhang,Zhixiong Ying,Le Zhou,Lili Zhang,Tian Wang 한국영양학회 2017 Nutrition Research and Practice Vol.11 No.2

BACKGROUND/OBJECTIVES: The study was conducted to evaluate the effects of dietary leucine supplementation on mitochondrial biogenesis and energy metabolism in the liver of normal birth weight (NBW) and intrauterine growth-retarded (IUGR) weanling piglets. MATERIALS/METHODS: A total of sixteen pairs of NBW and IUGR piglets from sixteen sows were selected according to their birth weight. At postnatal day 14, all piglets were weaned and fed either a control diet or a leucine-supplemented diet for 21 d. Thereafter, a 2 × 2 factorial experimental design was used. Each treatment consisted of eight replications with one piglet per replication. RESULTS: Compared with NBW piglets, IUGR piglets had a decreased (P < 0.05) hepatic adenosine triphosphate (ATP) content. Also, IUGR piglets exhibited reductions (P < 0.05) in the activities of hepatic mitochondrial pyruvate dehydrogenase (PDH), citrate synthase (CS), α-ketoglutarate dehydrogenase (α-KGDH), malate dehydrogenase (MDH), and complexes I and V, along with decreases (P < 0.05) in the concentration of mitochondrial DNA (mtDNA) and the protein expression of hepatic peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α). Dietary leucine supplementation increased (P < 0.05) the content of ATP, and the activities of CS, α-KGDH, MDH, and complex V in the liver of piglets. Furthermore, compared to those fed a control diet, piglets given a leucine-supplemented diet exhibited increases (P < 0.05) in the mtDNA content and in the mRNA expressions of sirtuin 1, PGC-1α, nuclear respiratory factor 1, mitochondrial transcription factor A, and ATP synthase, H+ transporting, mitochondrial F1 complex, β polypeptide in liver. CONCLUSIONS: Dietary leucine supplementation may exert beneficial effects on mitochondrial biogenesis and energy metabolism in NBW and IUGR weanling piglets.

The Dual-frequency (20/40 kHz) Ultrasound Assisted Photocatalysis with the Active Carbon Fiber-loaded Fe³⁺-TiO₂ as Photocatalyst for Degradation of Organic Dye

Xiong, Shaofeng,Yin, Zhoulan,Zhou, Yuanjin,Peng, Xianzhong,Yan, Wenbin,Liu, Zhixiong,Zhang, Xiangyu Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.10

Dual-frequency ultrasound assisted photocatalysis (DUAP) method was proposed to degrade a stable organic model effluent, cresol red (CR), using the prepared $Fe^{3+}$-doped $TiO_2$ with active carbon fiber loading ($Fe^{3+}-TiO_2/ACF$) as photocatalyst. The influence of key factors, including Fe doping amount and power density of dual-frequency ultrasounds (20/40 kHz), on the degradation efficiency was investigated. The degradation efficiency rises to 98.7% in 60 min accompanied by the color removal of CR liquid samples from yellow to colorless transparent at optimal conditions. A synergy index of 1.40 was yielded by comparison with single ultrasound assisted photocatalysis (SUAP) and the photocatalysis without ultrasound assisted (UV/$TiO_2$), indicating that a clear synergistic effect exists for the DUAP process. Obvious enhancement of degradation efficiency for the DUAP process should be attributed to production of large amount of free radicals by strong cavitational effects of dual ultrasounds.

The Dual-frequency (20/40 kHz) Ultrasound Assisted Photocatalysis with the Active Carbon Fiber-loaded Fe3+-TiO2 as Photocatalyst for Degradation of Organic Dye

Shaofeng Xiong,Zhoulan Yin,Yuanjin Zhou,Xianzhong Peng,Wenbin Yan,Zhixiong Liu,Xiangyu Zhang 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.10

Dual-frequency ultrasound assisted photocatalysis (DUAP) method was proposed to degrade a stable organic model effluent, cresol red (CR), using the prepared Fe3+-doped TiO2 with active carbon fiber loading (Fe3+- TiO2/ACF) as photocatalyst. The influence of key factors, including Fe doping amount and power density of dual-frequency ultrasounds (20/40 kHz), on the degradation efficiency was investigated. The degradation efficiency rises to 98.7% in 60 min accompanied by the color removal of CR liquid samples from yellow to colorless transparent at optimal conditions. A synergy index of 1.40 was yielded by comparison with single ultrasound assisted photocatalysis (SUAP) and the photocatalysis without ultrasound assisted (UV/TiO2), indicating that a clear synergistic effect exists for the DUAP process. Obvious enhancement of degradation efficiency for the DUAP process should be attributed to production of large amount of free radicals by strong cavitational effects of dual ultrasounds.