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Abietane Diterpenoids from Perovskia atriplicifolia and Their Anti-HBV Activities
Zhi-Yong Jiang,Zhong-Qiu Li,Chao-Guan Huang,Jun Zhou,Qiu-Fen Hu,Wen-Xing Liu,Xiang-Zhong Huang,Wei Wang,Li-Zhu Zhang,Fu-Ting Xia 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.2
Bioassay-guided phytochemical investigation on the 90% EtOH extract of Perovskia atriplicifolia resulted in the isolation of eight abietane diterpenoids, including three new ones (1–3). Based on spectroscopic methods involving 1D and 2D NMR spectroscopy techniques, mass spectrometry, and optical rotation, the structures of the new compounds (1–3) were unambiguously characterized. Compounds 1–2 and 4–8 were evaluated for their anti-HBV (hepatitis B virus) activity in HepG 2.2.15 cell line. Results suggested rosmadial (8) had the most anti-HBV potency, suppressing the secretion of HBsAg and HBeAg, with IC50 values of 0.09 and 0.34 mM, respectively.
Zhi-Yong Wang,강대기 한국인터넷방송통신학회 2019 International Journal of Internet, Broadcasting an Vol.11 No.4
In this paper, we explore the details of three classic data augmentation methods and two generative model based oversampling methods. The three classic data augmentation methods are random sampling (RANDOM), Synthetic Minority Over-sampling Technique (SMOTE), and Adaptive Synthetic Sampling (ADASYN). The two generative model based oversampling methods are Conditional Generative Adversarial Network (CGAN) and Wasserstein Generative Adversarial Network (WGAN). In imbalanced data, the whole instances are divided into majority class and minority class, where majority class occupies most of the instances in the training set and minority class only includes a few instances. Generative models have their own advantages when they are used to generate more plausible samples referring to the distribution of the minority class. We also adopt CGAN to compare the data augmentation performance with other methods. The experimental results show that WGAN-based oversampling technique is more stable than other approaches (RANDOM, SMOTE, ADASYN and CGAN) even with the very limited training datasets. However, when the imbalanced ratio is too small, generative model based approaches cannot achieve satisfying performance than the conventional data augmentation techniques. These results suggest us one of future research directions.
Characterization of the Stress-optic Properties of Ceramics by Terahertz Time-domain Spectroscopy
Zhi Qiang Wang,Wen Jia Ren,Gui Ying Zhang,Zhi Yong Wang 한국광학회 2024 Current Optics and Photonics Vol.8 No.3
This paper introduces a rapid measurement technique for the stress-optic coefficient, using terahertz time-domain spectroscopy. First we propose a design combining a four-point bending device with a scanning stage to streamline the loading process. Then we detail the measurement principle and outline the signal-processing algorithm. The experiments are carried out on Al 2 O 3 , a representative ceramic material. The experimental data reveal that the refractive index of Al 2 O 3 exhibits a linear decrease with increasing stress. This work supplies an efficient method for stress measurement rooted in the stress-optic effect. This paper introduces a rapid measurement technique for the stress-optic coefficient, using terahertz time-domain spectroscopy. First we propose a design combining a four-point bending device with a scanning stage to streamline the loading process. Then we detail the measurement principle and outline the signal-processing algorithm. The experiments are carried out on Al 2 O 3 , a representative ceramic material. The experimental data reveal that the refractive index of Al 2 O 5 exhibits a linear decrease with increasing stress. This work supplies an efficient method for stress measurement rooted in the stress-optic effect.
Preparation of HMX by Catalytic Nitrolysis of DPT in AIL-N_2O_5-HNO_3 System
Zhi-yong He,Jun Luo,Chun-xu Lü,Ping Wang,Rong Xu,Jin-shan Li 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8
Direct nitrolysis of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT) is a feasible way to synthesize HMX, and it has multiple practical applications. In this paper, a new nitrolysis process involving the use of an N_2O_5-HNO_3 system catalyzed by acidic ionic liquids (AILs) was developed. The results show that [Et_3NH]TsO was the best catalyst among the 28 AILs used and that HMX was formed at a higher yield of 61%, compared to 45% without any AIL. Moreover, with the addition of N_2O_5, the yield was further increased to a maximum value of 69%. The AILs were also efficiently recovered by simple extractions without any apparent loss of catalytic activity, even after five runs.
Zhi-Yong Zheng,Xiaobei Zhan,Chi Chung Lin,Shan-Jing Yao 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.1
Tryptone has multiple and complex effects on cell physiology and process performance in pulse fed-batch cultivation of recombinant Escherichia coli. By applying feedback control of dissolved oxygen signal responding to pulse in the feed rate, the production of acetate was avoided and the optimization of production of recombinant human epidermal growth factor (hEGF) was successfully achieved. With the addition of an optimum amount of tryptone along with glucose in the pulse fed-batch cultivation of E. coli, the ability of the cell to divide and the stability of the plasmid within the bacteria were improved. Consequently, segregation of the cells into a viable but non-culturable physiological state was alleviated. Addition of tryptone also enhanced cell respiration before and after hEGF expression and thus further benefited the production of recombinant hEGF. Excessive addition of tryptone resulted in low sensitivity of the oscillation of dissolved oxygen signal and poor operability of pulse fed-batch cultivation as this led to an accumulation of acetate, which weakened the dissolved oxygen signal responses. Consequently, the production of recombinant protein was considerably reduced. By combining the process performance and the positive effect of complex media pulse addition on bacterial metabolism, the optimal production conditions of hEGF were successfully determined. A high cell density of 91 g/L dry cell weight was obtained under these optimal production conditions. Furthermore, a high level of 0.24 g/L hEGF was attained leading to a 32.6% increase in product yield as compared to the controls.
Zhi-Qiang Song,Ju-E Cheng,Fei-Xue Cheng,De-Yong Zhang,Yong Liu 한국식물병리학회 2017 Plant Pathology Journal Vol.33 No.2
Tylenchulus semipenetrans is an important and widespreadplant-parasitic nematode of citrus worldwideand can cause citrus slow decline disease leading tosignificant reduction in tree growth and yield. Rapidand accurate detection of T. semipenetrans in soil isimportant for the disease forecasting and management. In this study, a loop-mediated isothermal amplification(LAMP) assay was developed to detect T. semipenetrans using DNA extracted from soil. A setof five primers was designed from the internal transcribedspacer region (ITS1) of rDNA, and was highlyspecific to T. semipenetrans. The LAMP reaction wasperformed at 63°C for 60 min. The LAMP productwas visualized directly in one reaction tube by addingSYBR Green I. The detection limit of the LAMP assaywas 10–2 J2/0.5 g of soil, which was 10 times moresensitive than conventional PCR (10–1 J2/0.5 g of soil). Examination of 24 field soil samples revealed that theLAMP assay was applicable to a range of soils infestednaturally with T. semipenetrans, and the total assaytime was less than 2.5 h. These results indicated thatthe developed LAMP assay is a simple, rapid, sensitive,specific and accurate technique for detection of T. semipenetrans in field soil, and contributes to the effectivemanagement of citrus slow decline disease.
Yong Zhi,Shunmei Lin,A-Yeung Jang,Ki Bum Ahn,Hyun Jung Ji,Hui-Chen Guo,임상용,Ho Seong Seo 한국미생물학회 2019 The journal of microbiology Vol.57 No.1
Salmonella enterica is a major human pathogen that causes invasive non-typhoidal Salmonellosis (iNTS), resulting in significant morbidity and mortality. Although a number of pre-clinical and clinical studies have reported on the feasibility of developing a safe and effective vaccine against iNTS, there have been no licensed Salmonella vaccines available to protect against NTS strains. Vaccine formulations of highest priority for NTS are live attenuated vaccines, which can elicit effective induction of intestinal mucosal and intracellular bacteria-specific cell mediated immune responses. Since glucose is crucial for intracellular survival and replication in host cells, we constructed strains with mutations in components of the glucose uptake system, called the phosphotransferase system (PTS), and compared the relative virulence and immune responses in mice. In this study, we found that the strain with mutations in both ptsI and crr (KST0556) was the most attenuated strain among the tested strains, and proved to be highly effective in inducing a mucosal immune response that can protect against NTS infections in mice. Thus, we suggest here that KST0556 (ΔptsIΔcrr) is a potential live vaccine candidate for NTS, and may also be a candidate for a live delivery vector for heterologous antigens. Moreover, since PTS is a well-conserved glucose transporter system in both Gramnegative and Gram-positive bacteria, the ptsI and crr genes may be potential targets for creating live bacterial vectors or vaccine strains.
Spectral Research on an AlGaAs Epitaxial Material for a Terahertz Quantum-cascade Laser
Zhi-Yong Tan,Jun-Cheng Cao 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.8
The spectral properties of a series of AlGaAs epitaxial films were studied by using a Fourier transform infrared spectrometer with an 80-degree grazing incidence reflection unit. The AlAslike transversal optical phonon was obviously observed in the spectra, but the longitudinal optical phonon was obscured in the transmission spectra. The variation curves for the transversal optical phonon energy were acquired from the two kinds of spectra and were compared with each other and with the early results. A comparison of the results show that the grazing incidence reflection spectrum is better in reflecting the AlAs-like phonon energy of an AlGaAs epitaxial film and could be a supplementary means in the characterization of the material for a terahertz quantum-cascade laser.