Kinetics of Enzymatic Synthesis of L-ascorbyl Acetate by Lipozyme TLIM and Novozym 435

Dong-Hao Zhang,Ya-Qiong Li,Chao Li,Yv-Qin Lv,Yang-L 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.1

L-ascorbyl acetate was synthesized through lipase-catalyzed esterification using Lipozyme TLIM and Novozym 435. Four solvents, including methanol, ethanol,acetonitrile, and acetone were investigated for the reaction,and acetone and acetonitrile were found to be suitable reaction media. The influences of several parameters such as water activity (aw), substrate molar ratio, enzyme loading,and reaction temperature on esterification of Lascorbic acid were systematically and quantitatively analyzed. Through optimizing the reaction, lipase-catalyzed esterification of L-ascorbic acid gave a maximum conversion of 99%. The results from using Lipozyme TLIM and Novozym 435 as biocatalysts both showed that aw was an important factor for the conversion of L-ascorbic acid. The effect of pH value on lipase-catalyzed L-ascorbic acid esterification in acetone was also investigated. Furthermore,results from a kinetic characterization of Lipozyme TLIM were compared with those for Novozym 435, and suggested that the maximum reaction rate for Lipozyme TLIM was greater than that for Novozym 435, while the enzyme affinity for substrate was greater for Novozym 436.

Trends in Intergenerational Educational Mobility in the 20th Century

Hao Dong,Yu Xie 한국사회학회 2018 한국사회학회 심포지움 논문집 Vol.2018 No.5

Efficiently visible and 2 μm infrared emission in K2YbF5: Ce3+/Ho3+ microcrystals

Hao Dong,Guangping Zhu,Min Zhang,Kai Dai,Qiang Li,Chaopeng Cui 한국물리학회 2020 Current Applied Physics Vol.20 No.6

Ho3+/Ce3+ co-doped K2YbF5 microcrystals were synthesized by solvent-thermal method. Under excitation of 980 nm laser diode, effectively visible and 2 μm-infrared luminescence of Ho3+ ion were obtained in the microcrystals. By changing Ce3+-ion doping concentration, the luminescence properties of visible and 2 μm emission were effectively regulated. At low Ce3+-ion doping level, the red and green upconversion emission obviously increases and decreases respectively with the increase of Ce3+-ion amount in the samples, meanwhile the intensity of 2 μm fluorescence changes very little. At high Ce3+-ion doping level, the intensities of the red and green emission both decrease with the increase of Ce3+-ion concentration, while the 2 μm emission intensity increases obviously. In the sample doped with 16% Ce3+ ion, the intensity of 2 μm emission is about 4.5 times that of the sample without Ce3+ ion, and the corresponding quantum efficiency is about 78.3%. The result is attributed to the influence of the different cross relaxation between Ho3+ and Ce3+ ion in luminescence process at low and high Ce3+-ion doping concentration. The corresponding luminescence mechanism and energy transfer process were discussed in detail.

Eight Decades of Educational Assortative Marriage in China

Hao Dong,Yu Xie 한국사회학회 2018 한국사회학회 심포지움 논문집 Vol.2018 No.5

Materials(Organic, Inorganic, Electronic, Thin Films), Polymer, Fluidization, Particle Technology : The Kinetics of Oxidation Curing of Polycarbosilane Fibers

( Hao Wang ),( Xiao Dong Li ),( Xiao Xia Li ),( Bin Zhu ),( Dong Pyo Kim ) 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.4

Isolation, Identification, and Performance Studies of a Novel Paraffin-degrading Bacterium of Gordonia amicalis LH3

Dong-Hui Hao,Xin Song,Jian-Qiang Lin,Yu-Jie Su,Yin-Bo Qu,Jian-Qun Lin 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.1

In this study, we describe the isolation and identification of a novel long-chain n-alkane degrading strain, Gordonia amicalis LH3. Under aerobic conditions, it utilized approximately 18.0% of paraffin (2% w/v) after 10 day of incubation, and the paraffin compositions of C18C24 alkalines were utilized preferentially. Under anaerobic conditions, paraffin utilization was approximately 1/8 that seen under aerobic conditions, and the compositions of C34 and C36 alkalines were utilized preferentially. The effects of salinity, temperature, and biosurfactants on paraffin degradation were also evaluated. The strain was also demonstrated to grow on oil, and decreased oil viscosity by 44.7% and degraded oil by 10.4% under aerobic conditions. Our results indicated that G. amicalis LH3 has potential applications in paraffin control, microbial enhanced oil recovery (MEOR), and the bioremediation of hydrocarbon-polluted environments.

Analysis of vibration characterization of a multi-stage planetary gear transmission system containing faults

Hao Dong,Yue Bi,Bing-Xing Ren,Zhen-Bin Liu,Yue Li 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.4

In order to explore the influence of tooth root cracks on the dynamic characteristics of multi-stage planetary gear transmission systems, a concentrated parameter method was used to construct a nonlinear dynamic model of the system with 30- DOF in bending and torsion, taking into account factors such as crack depth, length, angle, error, time-varying meshing stiffness (TVMS), and damping. In the model, the energy method was used to establish a TVMS model with cracks, and the influence of cracks on the TVMS of the system was studied. By using the Runge- Kutta method to calculate the differential equations of system dynamics, a series of system vibration diagrams containing cracks were obtained, and the influence of different crack parameters on the vibration of the system was analyzed. And vibration testing experiments were conducted on the system with planetary gear cracks. The results show that when the gear contains cracks, the TVMS of the system will decrease, and as the cracks intensify, the TVMS will decrease. When cracks appear on the II-stage planetary gear, the system will experience impact effects with intervals of rotation cycles of the II-stage planetary gear. There will be obvious sidebands near the meshing frequency doubling, and the vibration trajectory of the gear will also become disordered. These situations will become more and more obvious as the degree of cracks intensifies. Through experiments, the theoretical results are in good agreement with experimental results, verifying the correctness of the theoretical model. This provides a theoretical basis for fault diagnosis and reliability research of the system.

Influence of errors and floating on static load-sharing characteristics of twin rotors concentric face-gear power-split transmission system

Hao Dong,Hao-Qin Zhang,Gang Liang,Bing-Xing Ren,Xiao-Long Zhao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4

Twin rotors concentric face-gear power-split transmission system (TRCFGPSTS) is a new and more advanced main reducer configuration of the high-speed helicopter. Its loadsharing performance between different branches has a great impact on the service life performance. Its load distribution is complex, and the research on the influence law of error on loadsharing performance is not clear. Therefore, to study the influence of system error and pinions floating on the mechanical properties of the system, the static load-sharing mathematical model of the system was established. The load-sharing model comprehensively considers the factors of manufacturing error (ME) and installation error (IE), meshing stiffness, torsional stiffness, support stiffness and member floating. The coordination conditions of torsional angle elastic deformation of the system with central displacement offset and the mechanical balance conditions under the action of elastic support and floating support are derived, which reflects the change law of load distribution from the perspective of the system as a whole. The load-sharing model is solved by the least square method. The load-sharing coefficient (LSC) of the system is obtained. The influence of ME, IE and floating pinions on load-sharing performance is analyzed. The results show that the LSC shows irregular periodic fluctuation under the combined action of error, and the LSC is 1.212. Under the single influence of ME, the LSC also shows irregular periodic fluctuation, and the LSC is 1.610. Under the single influence of IE, the LSC presents a constant influence law, and the LSC is 1.326. The error of each gear in the III-stage has the most obvious influence on the load-sharing characteristics. The LSC of I-stage and II-stage floating pinion under the single influence are 1.113 and 1.120, respectively. The floating gear can significantly improve the load-sharing performance, and meet the load-sharing at the ±5 % service requirement.

Effect of Resveratrol on Coxsackie Virus B3m - induced Myocarditis in Mice

Hao Han Dong,He Li Ren 한국식품영양과학회 2004 한국식품영양과학회 학술대회발표집 Vol.55 No.-

To observe the intervening effect of resveratrol on coxsackie virus B3m-induced myocarditis in Balb/c mice and explore the mechanism of intervening effect.<br/> Using an animal model of viral myocarditis induced by coxsackie virus B3m (CVB3m), with Ribavirin and Astragalan as comparison, to examine the changes of general condition, mortality, the weights of heart, liver and spleen, serum MDA and NO levels, and cardiac histology in Balb/c mice.<br/> By comparison with Ribavirin and Astragalan, it was found that in the mice model of viral myocarditis induced by coxsackie virus B3m resveratrol significantly improved the changes of general condition, mortality, the weights of heart, liver and spleen, serum MDA and NO levels, and cardiac histology.<br/> It suggested that resveratrol may have some chemopreventive and chemotherapeutic effects in the treatment of viral myocarditis.

Investigation on the interactions of scutellarin and scutellarein with bovine serum albumin using spectroscopic and molecular docking techniques

Hao Tang,Nian-Guang Li,Zhi-Hao Shi,Yu-Ping Tang,Qian-Ping Shi,Ze-Xi Dong,Peng-Xuan Zhang,Jin-ao Duan 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.10

The binding abilities of scutellarin (Scu) andscutellarein (Scue) with bovine serum albumin (BSA) wereinvestigated using equilibrium dialysis, high performanceliquid chromatography, fluorescence spectroscopy, competitivesite marker and molecular docking. The resultsshowed that the average protein binding ratios of Scu andScue with BSA were (79.85 ± 1.83) and (85.49 ± 1.21) %respectively. Under simulated physiological conditions, thefluorescence data indicated that Scu and Scue bound withBSA through a static mechanism. The thermodynamicparameters indicated that the interactions of Scu-BSA andScue-BSA mainly occurred by van der Waals forces andhydrogen bonds and it was easier for Scue to bind withBSA than Scu, indicating that the glucuronic acid moleculein Scu decreased the binding affinity. Site competitivemarker experiments showed that the binding sites of Scuand Scue mainly located within the sub-domain IIA ofBSA. Furthermore, molecular docking studies indicatedthat one BSA could bind three Scue, while one BSA couldcarry only two Scu. All these results clearly indicated theinteractions of Scu and Scue with BSA, which will lay thefoundation for further research to determine the pharmacologyand pharmacodynamics of Scu and Scue for treatingischemic cerebrovascular disease.