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Tan, Hao,Wu, Xiang,Xie, Liyuan,Huang, Zhongqian,Gan, Bingcheng,Peng, Weihong The Korean Society for Microbiology and Biotechnol 2015 Journal of microbiology and biotechnology Vol.25 No.6
A phytase gene was identified in a publicly available metagenome derived from subsurface groundwater, which was deduced to encode for a protein of the histidine acid phosphatase (HAP) family. The nucleotide sequence of the phytase gene was chemically synthesized and cloned, in order to further overexpress the phytase in Escherichia coli. Purified protein of the recombinant phytase demonstrated an activity for phytic acid of 298 ± 17 µmol P/min/mg, at the pH optimum of 2.0 with the temperature of 37℃. Interestingly, the pH optimum of this phytase is much lower in comparison with most HAP phytases known to date. It suggests that the phytase could possess improved adaptability to the low pH condition caused by the gastric acid in livestock and poultry stomachs.
Human capital, financial constraints, and innovation investment persistence
Peng Hongxing,Tan Hongping,Zhang Yin 기술경영경제학회 2020 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.28 No.3
We examine the impact of human capital on innovation investment persistence using a sample of high-tech companies listed in the Chinese A-share market for the period 2009–2017. We find that human capital mitigates the negative effect of financial constraints on innovation investment persistence. We further explore the mechanism through which human capital at the management and employee levels affects innovation investment persistence. We find that management human capital affects innovation investment persistence through the expectation of authorised patents, while employee human capital affects the persistence through salary stickiness. Furthermore, we find that management human capital contributes to an increase in future granted patents through persistent innovation investment.
Establishment of a Micro-Particle Bombardment Transformation System for Dunaliella salina
Tan Congping,Qin Song,Zhang Qun,Jiang Peng,Zhao Fangqing The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.4
In this study, we chronicle the establishment of a novel transformation system for the unicellular marine green alga, Dunaliella salina. We introduced the CaMV35S promoter-GUS construct into D. salina with a PDS1000/He micro-particle bombardment system. Forty eight h after transformation, via histochemical staining, we observed the transient expression of GUS in D. salina cells which had been bombarded under rupture-disc pressures of 450 psi and 900 psi. We observed no GUS activity in either the negative or the blank controls. Our findings indicated that the micro-particle bombardment method constituted a feasible approach to the genetic transformation of D. salina. We also conducted tests of the cells' sensitivity to seven antibiotics and one herbicide, and our results suggested that 20 ${\mu}g$/ ml of Basta could inhibit cell growth completely. The bar gene, which encodes for phosphinothricin acetyltransferase and confers herbicide tolerance, was introduced into the cells via the above established method. The results of PCR and PCR-Southern blot analyses indicated that the gene was successfully integrated into the genome of the transformants.
Effects of Nanopowder Additives in Micro-electrical Discharge Machining
Peng-Cheong Tan,Swee-Hock Yeo,Yie-Voon Tan 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.3
The use of electrical discharge machining(EDM) for micro-machining applications requires particular attention to the machined surface roughness and discharge gap distance, as these factors affect the geometrical accuracy of micro-parts. Previous studies of conventional EDM have shown that selected types of semi-conductive and nonconductive powder suspended in the dielectric reduced the surface roughness while ensuring a limited increase in the gap distance. Based on this, an extension of the technique to micro-EDM was studied. Such work is necessary since the introduction of nanopowders suspended in the dielectric is not well understood The experimental results showed that a statistically significant reduction in the surface roughness value was achieved at particular concentrations of the powder additives, depending on the powder material and the machining input energy setting. The average reduction in surface roughness using a powder suspended dielectric was between 14-24% of the average surface roughness generated using a pure dielectric. Furthermore, when these additive concentrations were used for machining, no adverse increase in the gap distance was observed.
Tan Yan Peng,Ling Tau Chuan,Yusoff Khatijah,Tan Wen Siang,Tey Beng Ti The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.3
In the present study, the performances of conventional purification methods, packed bed adsorption (PBA), and expanded bed adsorption (EBA) for the purification of the nucleocapsid protein (NP) of Newcastle disease virus (NDV) from Escherichia coli homogenates were evaluated. The conventional methods for the recovery of NP proteins involved multiple steps, such as centrifugation, precipitation, dialysis, and sucrose gradient ultracentrifugation. For the PBA, clarified feedstock was used for column loading, while in EBA, unclarified feedstock was used. Streamline chelating immobilized with $Ni^{2+}$ ion was used as an affinity ligand for both PBA and EBA. The final protein yield obtained in conventional and PBA methods was $1.26\%$ and $5.56\%$, respectively. It was demonstrated that EBA achieved the highest final protein yield of $9.6\%$ with a purification factor of 7. Additionally, the total processing time of the EBA process has been shortened by 8 times compared to that of the conventional method.
Tan Pi Qiang,Li Yun Peng,Wang De Yuan,Hu Zhi Yuan,Lou Di Ming 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.4
To meet increasingly stringent emission regulations, diesel engines must be equipped with DOC, DPF and SCR. Five performance parameters including system back pressure, HC conversion efficiency, conversion efficiency of NO to NO2, passive regeneration rate, and conversion efficiency of NO to N2 are very important for DOC+DPF+SCR system. Nine structural parameters including rDOC, rDPF, rSCR, σDOC, σDPF, σSCR, δDOC, δDPF, and δSCR di rectly a ffect t he f i ve performance parameters, this paper has carried out a detailed study on it. First, a simulation model of DOC+DPF+SCR system was established, and calibrated by experiment. Then, simulation was performed on the five performance parameters under different values of the nine structural parameters. Subsequently, a novel model using random forest algorithm was established to analyze the correlation between the performance parameters and the structural parameters. The results show that σDPF has the greatest influence on system backpressure, followed by rDPF. The rDOC has the greatest influence on HC conversion, followed by σDOC. The rDOC has the greatest influence on conversion of NO to NO2, followed by σDOC. The rDPF has the greatest influence on DPF passive regeneration rate, followed by rDOC. The rSCR has the greatest influence on conversion of NO to N2, followed by rDOC.
Tan Jia-qi,Li Peng-cheng,Li Qian,Tang Jin-tian,Xue Hong-kun 한국응용생명화학회 2020 Applied Biological Chemistry (Appl Biol Chem) Vol.63 No.5
The aim of this study is to assess the cytoprotection and potential molecular mechanisms of procyanidin B2 ( PCB2) on hydrogen peroxide ( H2O2)-induced oxidative damage in MCF-7 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to determine the viability of MCF-7 cell exposure to H2O2 or PCB2. We measured the antioxidant properties of PCB2 by determining the activities of SOD, GSH-Px, LDH and MDA levels, and evaluated apoptosis and intracellular reactive oxygen species (ROS) levels. The related proteins expression levels were monitored by Western blot. MCF-7 cells induced with H2O2 had a remarkable decrease in cell viability that was suppressed when it was interfered with PCB2 (0.1–10.0 μM). PCB2 interference memorably and dose-dependently inhibited H2O2- induced LDH leakage, ROS and MDA overproduction, while PCB2 markedly increased H2O2- induced the activities of SOD and GSH-Px. Eventually, H2O2 prominently down-regulated the ratio of Bcl-2/Bax and the relative proteins expression levels of Nrf2, GCLC, NQO1 and HO-1, and up-regulated the relative proteins expression levels of cytochrome c, caspase-3 and Keap1. However, the relative expression levels of these proteins were reversed in PCB2- interfered MCF-7 cells. This study implied that protective effect of PCB2 on H2O2- induced oxidative damage in MCF-7 cells might be related to inhibition of mitochondria-dependent apoptosis, activation of Keap1/Nrf2/HO-1 signaling pathway and improvement of the antioxidant enzymes activities.