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Investigation on the Preparation and Adsorption Performance of Bamboo Fiber Based Activated Carbon
Qing Zhang,Yue Zeng,Xiuyun Xiao,Penghu Deng,Qing He,Tonghua Zhang 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2
In this work, an approach was explored to make natural fiber based activated carbon with high adsorption capacity for treating dyeing wastewater. Bamboo fiber based activated carbon (BFAC) was prepared by bamboo fiber extracted from bamboo strips by extracting technique. An orthogonal experiment was carried out to obtain optimum preparation condition for the best dye adsorption. The microstructures of BFAC were characterized by scanning electron microscopy, N2 adsorption-desorption analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. Adsorption mechanism of BFAC to methylene blue (MB) was studied and the adsorption isotherm followed the Langmuir model, with maximum monolayer adsorption capacity of 651.7 mg g-1. The adsorption kinetic was better described by the pseudo-second-order model. Microstructure characterization showed lots of opened pores and cracks with different size on BFAC, with Brunauer-Emmett-Teller (BET) surface area of 1370 m2 g-1 and total pore volume of 0.9411 cm3 g-1. The analysis indicated that cellulose crystal of bamboo fiber was severely destroyed in the preparation process, which could contribute to the formation of pores. Moreover, -OH and -C=O functional groups on BFAC are beneficial for adsorbing MB in aqueous solution. As a result, adopting bamboo fiber may help form BFAC with high BET surface area, which proved to be an effective idea to prepare activated carbon with high adsorption performance.
Qing Xiao,Xuan Zhou,Zuobing Xiao,Yunwei Niu 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.2
The aroma composition, aroma-active compounds, and sensory attributions of cherry wines from three different price segments were investigated. A total of 48 aroma compounds were identified and quantified using headspace solid-phase microextraction (HS-SPME)/gas chromatography– mass spectrometry (GC–MS), among which 23 aroma compounds were further screened out as important odorants based on their odor activity values (OAVs); then, the previously mentioned 23 volatiles were correlated to sensory attributes using partial least-squares regression (PLSR). The result indicates that the differently priced wines were associated with different compounds and aroma attributions. Finally, aroma reconstitution was performed by mixing odor-active aroma compounds (OAVs>1) on the basis of their measured concentrations in the original sample. The result indicated that the aroma profile of the reconstituted sample was similar to that of the original sample.
Qing-Mei Quan,Qing-Xia Wang,Xue-Li Zhou,Shan Li,Xiao-Ling Yang,Yun-Guo Zhu,Zhou Cheng 한국미생물학회 2014 The journal of microbiology Vol.52 No.2
Ophiocordyceps sinensis (Ascomycota: Ophiocordycipitaceae)is a native fungal parasite of Hepialidae caterpillars and oneof the most economically important medicinal caterpillarfungi in China. However, little is known about the phylogeneticand evolutionary relationships between O. sinensis andits host insects. In this study, nuclear ITS and β-tubulin sequencesfrom O. sinensis and mitochondrial COI, COII, andCytb sequences from its hosts were analyzed across 33 populationssampled from five regions in China. Phylogenetically,both O. sinensis and its hosts were divided into three geographicallycorrelated clades, and their phylogenies were congruent. Analysis of molecular variance and calculated coefficientsof genetic differentiation revealed significant geneticdivergence among the clades within both O. sinensis (FST=0.878, NST=0.842) and its hosts (FST=0.861, NST=0.816). Estimatedgene flow was very low for O. sinensis (Nm=0.04) andthe host insects (Nm=0.04) among these three clades. Manteltests demonstrated a significant correlation (P<0.01) betweenthe genetic distances for O. sinensis and its hosts, as well as asignificant association (P<0.05) between geographic and geneticdistances in both. The similar phylogenetic relationships,geographic distributions, and genetic structure and differentiationbetween O. sinensis and its hosts imply that they have coevolved.
Xiao-Jie Li,Jie Hu,Zhen-Yu Li,Xue-Mei Qin,Li-Zeng Zhang,Xiao-Qing Guo 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.6
A high-performance liquid chromatographic (HPLC) method was established to analyze 36 Chaihu (Radix Bupleuri) samples collected from three species (Bupleurum chinense DC., B. scorzonerifolium Willd. and B. smithii Wolff.). Addition of trifluoroacetic acid into the mobile phase resulted in fingerprint chromatograms with stable baselines. There were thirty-two characteristic peaks in the standard fingerprint of B. chinense DC. Different recognition pattern methods, including similarity analysis (SA), hierarchical cluster analysis (HCA), principal component analysis (PCA) and partial least squares-discrimination analysis (PLS-DA) were utilized to analyze the 36 samples based on the contents of chemical constituents. Consistent results from SA, HCA and PCA analysis illustrated the rationalisation for why B. smithii Wolff. was not quoted in the Chinese Pharmacopoeia and classified samples were in agreement with their species. PLS-DA loading plots showed the chemical markers which had the most influences on the separation among different species. However, SA, HCA and PCA could not differentiate between wild and cultivated B. chinense DC. as well as between samples from different provinces. HPLC fingerprint in combination with chemometric techniques provided a very flexible and reliable method for homogeneity evaluation and quality assessment of traditional Chinese medicine.
Qing‑Ri Cao,Xiao‑Xue Zhang,Hao‑Yan Huang,Li‑Qing Chen,Hehua Jin,Beom‑Jin Lee,Jing‑Hao Cui 한국약제학회 2019 Journal of Pharmaceutical Investigation Vol.49 No.1
The application of single-walled carbon nanotubes (SWCNTs) as drug carriers is limited by their poor dispersal in aqueous medium. This study aimed to prepare chitosan (CS)-modified SWCNTs (CS-SWCNTs) and to evaluate their physicochemical properties and cytotoxicity. Oxidized SWCNTs (O-SWCNTs) were prepared with the use of strong acid, and the effects of acidizing conditions on the oxidation degree of the O-SWCNTs were investigated. CS was then non-covalently modified on the surfaces of O-SWCNTs. O-SWCNTs and CS-SWCNTs were characterized through ultraviolet spectroscopy, Fourier transform-infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy. The cytotoxic effects of the functionalized SWCNTs were determined through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. O-SWCNTs with relatively complete structure were successfully synthesized through 5 h of treatment with 5 M acid. The amine group of the CS and the carboxyl group of O-SWCNTs interacted in CS-SWCNTs. The functionalized SWCNTs did not aggregate or precipitate in water and exerted no cytotoxic effects on A549 and MCF-7 tumor cells. The CS-SWCNTs possess the advantages of a simple preparation process, excellent water dispersibility, and biocompatibility for drug loading.
Control of Electrically Excited Synchronous Motors with a Low Switching Frequency
Qing-qing Yuan,Xiao-jie Wu,Peng Dai,Xiao Fu 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component (im) and the torque component (it). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between im and it. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.
Rotor Initial Position Estimation Based on sDFT for Electrically Excited Synchronous Motors
Qing-qing Yuan,Xiao-jie Wu,Peng Dai 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
Rotor initial position is an important factor affecting the control performance of electrically excited synchronous motors. This study presents a novel method for estimating rotor initial position based on sliding discrete Fourier transform (sDFT). By injecting an ac excitation into the rotor winding, an induced voltage is generated in stator windings. Through this voltage, the stator flux can be obtained using a pure integral voltage model. Considering the influence from a dc bias and an integral initial value, we adopt the sDFT to extract the fundamental flux component. A quadrant identification model is designed to realize the accurate estimation of the rotor initial position. The sDFT and high-pass filter, DFT, are compared in detail, and the contrast between dc excitation and ac injection is determined. Simulation and experimental results verify that this type of novel method can eliminate the influence of dc bias and other adverse factors, as well as provide a basis for the control of motor drives.