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Table of Content

    25 October 2019, Volume 39 Issue 5 Previous Issue   
    The Research Progress in Molecular Self-assembly of Rosin Resin Acids and Their Derivatives
    HAN Chunrui, ZHOU Ruonan, HAN Bing, TIAN Chao, XU Pengfei, SONG Xianliang
    2019, 39 (5):  1-10.  doi: 10.3969/j.issn.0253-2417.2019.05.001
    Abstract ( 492 )   HTML ( 296813 )   PDF (5837KB) ( 777 )   Save
    There are many modification sites, such as carboxyl, double bond and benzene ring electric-rich center in the structure of rosin acids. Rosin based derivatives with abundant hydrophilic groups have been obtained by chemical modification. Rosin acids and their derivatives show special self-assembly ability in solutions because they are composed of carboxylic acid, new hydrophilic groups and the unique hydrophobic skeleton, chiral structure of rigid tricyclic terpenes. As a result, rosin and rosin-based derivatives have many functions including high surface activity, smart responsiveness and targeted drug delivery by self-assembly of molecules. According to the structural characteristics of the compounds, the self-assembly of resin acids and their derivatives in small molecules, supramolecules, macromolecules and organic-inorganic hybrid molecules is reviewed. The self-assembly aggregates are analyzed. The self-assembly behaviors and characteristics of resin acids and their derivatives are summarized. The applications in surface activity, smart responsiveness, drug delivery and modification of inorganic nanomaterials are overviewed. Finally, the developments on functional materials and self-assembled aggregates of resin acids and their derivatives are prospected.
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    Research Progress on the Dissolution of Lignocellulose and Separation of Its Components by Deep Eutectic Solvents
    XIE Yitong, GUO Xin, Lü Yanna, WANG Haisong
    2019, 39 (5):  11-18.  doi: 10.3969/j.issn.0253-2417.2019.05.002
    Abstract ( 991 )   HTML ( 2232984 )   PDF (852KB) ( 1307 )   Save
    Deep eutectic solvents (DESs), similarly to ionic liquids in physicochemical properties, have distinctive properties of easy synthesis, cost effectiveness, high dissolution power, and structure design ability. Dissolving and separating lignocellulose and its components by deep eutectic solvents is a new and environmentally friendly method to produce biomass energy and materials. Based on the introduction of the physicochemical properties and dissolution mechanism, the development of DESs applications in dissolving and separating cellulose, hemicellulose and lignin was reviewed.Finally, the prospects of the utilization of DESs in the field of lignocellulose were proposed.
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    Self-activation Mechanism for Preparation of Bamboo Derived High Performance Activated Carbon Under Micro-posotive Pressure
    SUN Hao, SUN Kang, JIANG Jianchun, XU Wei, ZHANG Yanping
    2019, 39 (5):  19-25.  doi: 10.3969/j.issn.0253-2417.2019.05.003
    Abstract ( 417 )   HTML ( 92480 )   PDF (959KB) ( 736 )   Save
    The preparation of activated carbon was carried out using bamboo as material via pyrolysis self-activation under micro-positive pressure without activating agent. The pore formation mechanism of activated carbon was investigated based on its structural characterization and adsorption properties. The results showed that the generated CO2 and H2O could react with solid carbon to prepare activated carbon with high adsorption performance during the pyrolysis process. The main influences on pore structure and adsorption properties of bamboo activated carbon were the pyrolysis gas, humogeneous activation, equilibrium state of gas-carbon reversible reaction, diffusion rate of activator and gas-carbon reaction rate. The activated carbon was prepared under the pyrolysis self-activation of bamboo 0.12 MPa at 900℃ (15℃/min heating rate) for 6 h. The yield of the product was 15.22% with the BET specific surface area(SBET), micropore volume(Vmic), mesopore volume(Vmes), iodine value and methylene blue (MB) value of activated carbon were 1 108 m2/g, 0.407 cm3/g, 0.085 cm3/g, 1 438 mg/g and 300 mg/g, respectively. Moreover, the gas by-product of self-activation contained high concentration of H2 and CO and exhibited a high ratio of CO to CO2, which could be raw materials for Fischer-Tropsch reaction.
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    Liquid Hot Water Pretreatment of Waste Wheat Straw Containing High Ash Content
    HUANG Chen, WU Xinxing, LAI Chenhuan, HUANG Caoxing, LI Xin, YONG Qiang
    2019, 39 (5):  26-32.  doi: 10.3969/j.issn.0253-2417.2019.05.004
    Abstract ( 507 )   HTML ( 8 )   PDF (594KB) ( 669 )   Save
    The liquid hot water pretreatment (LHWP) of waste wheat straw (WWS) and the effect of prewashing on the LHWP were investigated. The pretreated WWS had the highest enzymatic hydrolysis and fermentable sugars production after the pretreatment at 180℃ for 40 min with the solid to liquid ratio of 1:10(g:mL). The corresponding glucan and xylan enzymatic hydrolysis yields were 40.84% and 39.67%, respectively, and the fermentation sugars production was 15.74 g (glucose was 11.68 g and xylose was 4.06 g). The yield of glucan and xylan were 48.98% and 49.06% respectively under the conditions of the cellulase, xylanase and β-glucosidase loadings of 40 FPU/g glucan, 140 U/g xylan and 48 U/g glucan. The key factor of the LHWP of WWS was the acid buffering ability of the absorbable ash in the WWS. Thus, the WWS was first water washed with the dose of 500 mL/g WWS and then was subjected to the LHWP. After prewashing, the enzymatic hydrolysis yields of glucan and xylan were increased from 48.98% and 49.06% to 65.59% and 70.11%, respectively, with the corresponding glucose and xylose concentrations of 17.50 and 4.75 g/L. Moreover, the prewashing could also lower the enzyme dosages in the enzymatic hydrolysis process.
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    Preparation of NCC Assisted NaClO Oxidized Starch and Its Influence on the Properties ofComposite Film
    JI Dexian, LIN Zhaoyun, XIA Yuanyuan, YANG Guihua, CHEN Jiachuan
    2019, 39 (5):  33-40.  doi: 10.3969/j.issn.0253-2417.2019.05.005
    Abstract ( 458 )   HTML ( 7 )   PDF (4374KB) ( 594 )   Save
    The effect of NaClO effective chlorine dosage on the performance of starch and the subsequent composite films was explored. The composite films were fabricated with oxidized starch, polyvinyl alcohol (PVA) and glycerol (GL), which corn starch was used as raw material and nanocrystalline cellulose (NCC)/NaClO was applied as oxidation system. The carboxyl content, molecular weight, surface morphology, crystal structure, and the performance of composite films of the oxidized starch were characterized. The results showed that the oxidation degree of starch increased with increasing NaClO effective chlorine dosage, and increased by 1.17% with 10.0%(Significantly improved comparing with 0.36% of the carboxyl content of NaClO oxidized starch without NCC) with the assistance of NCC; When the amount of NaClO is 8%, the Mw and Mn were 97.33% and 97.27% lower than that of native corn starch. The surface was eroded and crystallinity was reduced after oxidation of starch. However, the films'transparency was improved (The maximum transparency is up to 78.50%). The increasing oxidation degree of oxidized starch contributed to the good performance of the composite film with high water resistance and the increase of the contact angle as well as tensile strength, whereas led to the decrease of the air permeability and tensile strain. When the amount of NaClO is 10%, the mass loss ratio of the composite film is 23.14%, the contact angle is 101.0° in 15 s, the air permeability is 0.10 cm3/(cm2·s), the tensile stress is 24.01 MPa, tensile strain is 2.14% and Young's modulus is 1 452.25 MPa.
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    Synthesis, Antibacterial and Herbicidal Evaluation of Camphoric Acid-based Acylhydrazone Compounds
    ZHENG Wanli, MA Xianli, ZHOU Xiaoqun, LI Fangyao, XIN Mao, JIANG Caina
    2019, 39 (5):  41-49.  doi: 10.3969/j.issn.0253-2417.2019.05.006
    Abstract ( 530 )   HTML ( 17 )   PDF (697KB) ( 718 )   Save
    Camphoric anhydride (2) was prepared via dehydration reaction using camphoric acid (1) as starting material. N-aminocamphorimide (3) was prepared by the acylation of compound2 with hydrazine hydrate. And then, 12 novel camphoric acid-based acylhydrazone compounds4a-4l were synthesized by the condensation reaction between N-aminocamphorimide and polyfluoro-substituted benzaldehyde, thiophene-carbaldehyde or furaldehyde. The target compounds were characterized by means of Fourier transform infrared spectroscopy(FT-IR), nuclear magnetic resonance(1H NMR and 13C NMR) and electrospray ionization-mass spectrometry(ESI-MS). The preliminary bioassay showed that 3, 5-difluorophenyl camphoric acid-based acylhydrazone (4i), 2-trifluoromethylphenyl camphoric acid-based acylhydrazone (4a) and 2, 3-difluorophenyl camphoric acid-based acylhydrazone (4d) exhibited excellent antifungal activities with the inhibition ratios of 90.6%, 85.4% and 82.2% against Botryosphaeria berengeriana at the mass concentration of 50 mg/L. Herbicidal evaluation results showed that most of the compounds had certain inhibitory effects on the growth of rape radicle at 100 mg/L. Among them, the growth inhibition rates of compounds 3-trifluoromethylphenyl camphoric acid-based acylhydrazone (4b), 3, 4-difluorophenyl camphoric acid-based acylhydrazone (4h) and 3-thienyl camphoric acid-based acylhydrazone (4k) on the radicle of rape(Brassica campestris) were 94.7%, 95.6% and 80.6%, respectively. Compound4i has the best overall effect, the inhibition ratio of 90.6% against B.dothidea at 50 mg/L (the activity level was A grade); the root growth inhibition rate of on root of rape (B. campestris) was 75.6% at 100 mg/L (the activity level was B grade).
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    Preparation of Soybean Oil Fatty Acid Polyester and Its Plasticity for Polyvinyl Chloride(PVC)
    FENG Guodong, JIA Puyou, TANG Huimin, ZHANG Meng, HU Yun, ZHOU Yonghong
    2019, 39 (5):  50-58.  doi: 10.3969/j.issn.0253-2417.2019.05.007
    Abstract ( 576 )   HTML ( 12 )   PDF (897KB) ( 679 )   Save
    Epoxidized soybean oil methyl ester (ESAO) was prepared by epoxy reaction and then followed by transesterification using soybean oil as starting material. Then, soybean oleic acid polyester (SF-PE) was prepared by one-pot reaction with ESAO, acetic acid and acetic anhydride. The purity of ESAO was more than 96% by GC analysis, and the structures of products were characterized by IR, 1H NMR and 13C NMR. It was proved that epoxidation, ring opening and esterification occurred and SF-PE was successfully synthesized. The thermal stability of SF-PE was better than ESAO according to TG analysis. The mechanical properties, dynamic mechanical properties (DMA) and TG of PVC samples prepared with SF-PE, ESAO, epoxy soybean oil (ESO) and epoxy fatty acid methyl ester (EFAM) as plasticizers were compared and analyzed. The tensile strength and hardness of PVC samples were 19 MPa and 90.2 HD when the dosage of SF-PE was 50% of the weight of resin. The comprehensive mechanical properties of PVC samples were optimized, and the glass transition temperature (Tg) was 26.4℃. Its low temperature resistance is superior to ESO, and its thermal stability is similar to ESAO, superior to EFAM, but inferior to ESO.
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    Preparation of Miscanthus sinensis Pyrolytic Char and Analysis of Reaction Kinetics and Mechanism of Gasification Using CO2 as Gasifier
    GUO Shen, TIAN Hong, HU Zhangmao, XU Huifang, JIAO Hao
    2019, 39 (5):  59-66.  doi: 10.3969/j.issn.0253-2417.2019.05.008
    Abstract ( 404 )   HTML ( 7 )   PDF (2696KB) ( 570 )   Save
    The physicochemical properties of Miscanthus sinensis Andersson pyrolysis char was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy and low temperature nitrogen adsorption. The CO2 gasification reaction mechanism of M. sinensis pyrolysis char was studied by a non-isothermal thermogravimetry method along with Master-plot method. The results showed that the organics of pyrolysis char decreases with the increment of temperature. Pyrolysis process was beneficial to the formation of pore structure and improvement of the specific surface area and pore volume. The maximum microporisty of 600℃ pyrolysis char (MPC600) was 86.73%. With the increasing of pyrolysis char preparation temperature and gasification heating rate, the maximum conversion rate temperature of pyrolysis char gasification reaction were shifted to the high temperature side. The gasification kinetic parameters of pyrolysis chars were calculated by Ozawa method. The average activation energy of pyrolysis chars were 171.87, 181.20 and 184.45 kJ/mol at 400, 600 and 800℃, respectively. The activation energy was independent of the conversion rate and the reaction can be described by a single kinetic mechanism function. The Master-plot method was used to determine the mechanism function of the kinetic model. The gasification kinetics of pyrolysis char was consistent with the 1D phase boundary reaction (R1) mechanisms.
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    Synthetic Technology of p-Menth-3-en-1-amine
    Huanhuan DONG,Shichao XU,Jing WANG,Hongmei ZHANG,Xiaojing ZENG,Yuxiang CHEN,Zhendong ZHAO
    2019, 39 (5):  67-72.  doi: 10.3969/j.issn.0253-2417.2019.05.009
    Abstract ( 721 )   HTML ( 328259 )   PDF (545KB) ( 484 )   Save

    p-Menth-3-en-1-amine was synthesized from p-menthane diacetylamide by two steps as an acid-catalyzed elimination and an alkaline-catalyzed hydrolysis. The effects of different conditions on these reactions were studied by single-factor and orthogonal tests. The optimal reaction conditions of the acid-catalyzed elimination are shown as 20 mmol p-menthane diacetylamide, 35 mL 12.5% H2SO4 solution (24 mmol) and reaction time 8 h, under which the yield is 41.6%; And the optimized technological parameters of the alkaline-catalyzed hydrolysis are shown as n(N-diacetyl-3-en-1-amine):n(NaOH) 1:7, 30 mL ethylene glycol as the solvent, reaction time 11 h and reaction temperature 170 ℃, to give N-diacetyl-3-en-1-amine in a yield of 82.2%, total yield is 34.2%, purified to 97% by vacuum rectification. The structure of the compound was determined by ESI-MS, FT-IR, 1H NMR and 13C HMR spectroscopic analyses.

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    Effects of Removal of Lignin via Two-stage Pretreatment on the Enzymatic Hydrolysis of Poplar
    CHEN Xueyan, CHU Qiulu, WANG Jing, ZHANG Xiaodong, SHI Aiping
    2019, 39 (5):  73-79.  doi: 10.3969/j.issn.0253-2417.2019.05.010
    Abstract ( 393 )   HTML ( 7 )   PDF (2794KB) ( 629 )   Save
    The effects of lignin fractionation via two-stage pretreatment on the surface morphology, physicochemical properties and enzymatic hydrolysis of the poplar chips were investigated. The results showed that, comparing to one-stage steam explosion(SE) pretreatment, alkaline sulfonation-steam explosion(AS-SE) and alkaline oxidation-steam explosion(AO-SE) pretreatment both led to the removal of around 50% lignin from biomass, while incorporating extensive hydrophilic acid groups including sulfonic and carboxylic groups into substrates. As a result, cellulose accessibility was increased to 132.04 and 119.10 mg/g, respectively. Besides, FT-IR spectrum confirmed the incorporation of hydroxyl, carboxylic and sulfonic groups into lignin after AS and AO pretreatments. SEM images showed the cracked and corroded surface morphology after the two-stage pretreatments for lignin fractionation. After the AS-SE pretreatment, 81.09% of the cellulose in pretreated solid could be converted to glucose, while the yield of biomass saccharification was improved to 73.72%. These results indicated that lignin fractionation via two-stage pretreatment led to the selectively removal and modification of lignin, resulting in the change of the physicochemical properties and surface morphology of lignin, and favoring the enzymatic hydrolysis of cellulose.
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    Catalytic Degradation of Lignin by Aluminum Oxide Monosodium Solid Superbase
    WANG Xingjia, QIAO Wei, XIAO Daming, LI Shujun
    2019, 39 (5):  80-86.  doi: 10.3969/j.issn.0253-2417.2019.05.011
    Abstract ( 471 )   HTML ( 15 )   PDF (1007KB) ( 545 )   Save
    In order to improve the activity of lignin and promote the efficient utilization of lignin, the refined lignin (PL) obtained by fermenting corn stover to produce ethanol residue and alkali-soluble acid precipitation is used as the raw material, and reacted with isopropanol-water cosolvent. The degradation of lignin (DL) was obtained by catalytic degradation under the condition of medium, liquid-solid ratio of 10:1 (mL:g) and aluminum-oxygen monosodium solid superbase as catalyst. The orthogonal conditions were used to optimize the degradation conditions before and after degradation, followed by the analyzed and characterized of lignin. The results showed that the optimized degradation condition was 20% lignin mass, 200℃ reaction temperature and 150 min reaction time. The yield and formaldehyde value of lignin degradation were 77.5% and 0.365, respectively. The aromatic structure of lignin was well retained in the process of the solid superbase catalyzed degradation of lignin, which was confirmed by Fourier transform infrared spectroscopy (FT-IR), two-dimensional nuclear magnetic resonance (2D HSQC), gel permeation chromatography (GPC), thermogravimetric (TG) analysis. The content of β-O-4, β-β and β-5/α-O-4 in the DL side chain region was significantly reduced after degradation, and Ar-O-C ether bond was partially cleavage through the degradation of lignin. The content of phenolic hydroxyl group and alcohol hydroxyl group increased, whereas the molecular mass and polydispersity decreased significantly. Compared with PL, the main pyrolysis temperature range of DL became narrower and the maximum pyrolysis rate decreased.
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    Comparison on PRC-APMP Pulping Properties of Three Fast-growing Hardwoods
    LIN Benping, ZHU Hongwei, LIU Chengliang, XIAO Younian, ZHANG Meiyun
    2019, 39 (5):  87-94.  doi: 10.3969/j.issn.0253-2417.2019.05.012
    Abstract ( 1185 )   HTML ( 14788 )   PDF (585KB) ( 796 )   Save
    The chemical composition and basic wood density of three fast-growing hardwoods(Populus euramericana, Eucalyptus grandis×E.urophylla and Acacia mangium) chips were analyzed. The pulping properties of three different hardwood pulps made by PRC-APMP technology were studied. The results showed that higher contents of polysaccharide and 1% NaOH extractive were identified in populus than those in eucalyptus and acacia. Eucalyptus had the highest lignin content, whereas the holocellulose content was lowest than that of populus and acacia. The basic density of eucalyptus was 0.45 g/cm3, which was larger than that of acacia(0.43 g/cm3) and populus (0.39 g/cm3). The PRC-APMP pulping process was carried out under the condition of impregnating with NaOH 5.5% and H2O2 of 5.0%. As a result, acacia showed the highest pulp yield, which was up to 83.8%, while the pulp yield of populus and eucalyptus were 82.4% and 81.3% respectively. A highest pulp brightness of 78.2%(ISO) was achieved for eucalyptus, while the brightnesses for populus and acacia were 75.3%(ISO) and 70.7%(ISO), respectively. Under the same beating degree, it was found that acacia pulps possessed the highest tensile strength index, but required more refining energy. Populus pulps showed higher tearing index than that of acacia and eucalyptus pulps, due to its longer fiber length. In contrast, eucalyptus pulps exhibited the highest apparent bulk the lowest tensile strength as well.
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    Extraction and Antimicrobial Activity of Juglone from Pericarpium Juglandis
    LI Wenjun, WANG Chengzhang, LIU Chengjing
    2019, 39 (5):  95-100.  doi: 10.3969/j.issn.0253-2417.2019.05.013
    Abstract ( 605 )   HTML ( 8 )   PDF (541KB) ( 623 )   Save
    Juglone was extracted from pericarpium juglandis by ultrasound-assisted method. The optimal conditions of extracting juglone were obtained by single experiment and orthogonal test as follows:soaking time was 6 h using methanol as solvent, ratio of liquid to material was 5:1(mL:g), ultrasonic time was 35 min, and the yield of juglone was 0.246% and the yield of extract was 13.88%. The antibacterial activities of extract on Bacillus subtilis, Streptococcus pneumoniae, Staphylococcus aureus and S. epidermidis of juglone was investigated by mass concentration of 0.002 5-0.20 g/L, compared with commercial YZN-Y500 nano-silver. The results showed that the optimum extraction conditions was as follows:The antibacterial effect of pericarpium juglandis extract on the mass concentrations of 0.20 g/L and 0.02 g/L was stronger than that of commercial silver nanoparticles.
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    Preparation and Application of Enteromorpha prolifera Fibers of Polyacrylic Acid-based Absorbent Resins
    ZHANG Haonan, WEI Jiahui, ZHAO Hui, LI Dan, REN Hao
    2019, 39 (5):  101-107.  doi: 10.3969/j.issn.0253-2417.2019.05.014
    Abstract ( 418 )   HTML ( 9 )   PDF (4326KB) ( 515 )   Save
    The graft of Acrylic acid onto Enteromorpha prolifera fiber as well as its feasibility was reported and evaluated by varying the fiber pretreatment methods. Water-absorbent resins was synthesized under the conditions of the fixed amount of alkali, crosslinking agent and initiator dosage that using non-pretreated E. prolifera fiber, 1% NaOH pretreated fiber, and bleaching-pretreated fiber as raw materials. The influence of different pretreatment degrees, addition quantities, and fiber size on the water absorbance properties of the resins was studied while keeping the same amount of alkali charge, neutralization degree, crosslinking and initiator agent. The results showed that the synthesized absorbent resin has the best liquid absorption performance. The absorbance rates of deionized water, normal saline, and artificial urine reached 1 643, 244, and 201 g/g, respectively under the conditions of alginate of 1 g, the neutralization degree of acrylic acid of 65%, and the sieving size of 250-380 μm. The SEM images of non-pretreated alginate fiber water-absorbent resin indicated that the fibers had a plump morphology, and the porosity decreased after the water-absorbent resin was saturated. X-ray diffraction (XRD) showed that the amorphous region of the fiber dramatically disappeared. Otherwise the residual crystalline zone hindered the alkali pretreatment and bleaching pretreatment and resulted in the unfavorite of the grafting reaction of Enteromorpha prolifera fibers with acrylic acid.
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    Stimultaneous Determination of Four Flavone C-glycosides in Bamboo Leaves of Phyllostachys by HPLC
    CHEN Dandan, GUO Xuefeng, ZHAO Lei, SHAO Siyue
    2019, 39 (5):  108-114.  doi: 10.3969/j.issn.0253-2417.2019.05.015
    Abstract ( 401 )   HTML ( 117 )   PDF (618KB) ( 525 )   Save
    An HPLC method was developed and validated for simultaneous determination of isoorientin, orientin, vitexin, and isovitexin, and the four common flavone C-glycosides in bamboo leaves of 24 species of Phyllostachys and their contents in P. propinqua in the four seasons. The HPLC separation was performed on an Inertsil ODS-3 (250 mm×4.6 mm, 5 μm) column with the mobile phase of acetonitrile (B) and 0.5% phosphoric acid in water (C) with equal elution at a flow rate of 1 mL/min. The column temperature was 30℃, and the detected wavelength was 340 nm. The results showed that the linear ranges of the concentration of isoorientin, orientin, vitexin and isovitexin were 1-300 mg/L, respectively, and the concentrations of the four compounds showed a good linear relationship with their peak areas, and the correlation coefficients all > 99%; the average recoveries for the samples were 97.14%, 100.53%, 93.60% and 95.66%, respectively, and the relative standard deviations were 1.11%, 1.45%, 1.96% and 1.43%, respectively. The results showed that the content of flavone C-glycosides had big differences among bamboo leaves of 24 species of Phyllostachys. The total content of the four flavone C-glycosides were in the range of 286.14-3 838.79 mg/kg. The maximum content was found in P. nigra, and its content was 3 838.79 mg/kg. The total concentrations of four flavone C-glycosides in P. propinqua were in the range of 1 371.15-4 367.01 mg/kg in the 4 months, and the maximum content was found in January, and its content was 4 367.01 mg/kg. HPLC method had good reproducibility and high accuracy. This provides a basis for quality control of flavone C-glycosides of bamboo leaves.
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    Preparation of Carbon-doped Zinc Oxide Induced by Nanocellulose and Its Photocatalytic Degradation Properties of Tetracycline
    SHAN Yiwei, WU Hui, XIAO He, CHEN Lihui, HUANG Liulian
    2019, 39 (5):  115-120.  doi: 10.3969/j.issn.0253-2417.2019.05.016
    Abstract ( 514 )   HTML ( 21 )   PDF (1600KB) ( 589 )   Save
    Carbon-doped zinc oxide (C-ZnO) was prepared by hydrothermal synthesis using nanocellulose (CNF) as an inducing agent. C-ZnO was characterized by XRD, FT-IR, SEM and DRS. The photocatalytic degradation of tetracycline by C-ZnO was investigated. It was found that nanocellulose-induced ZnO had good dispersibility, reduced grain size and carbon doping with narrow band gap. Compared with ordinary zinc oxide, C-ZnO didn't affect the physical adsorption of tetracycline. But it had faster degradation rate of tetracycline in the photocatalytic process. When the hydrothermal temperature of C-ZnO was 200℃, n(Zn2+):n(OH-) was 1:4 and the mass ratio of zinc nitrate to nanocellulose was 100:1, the removal of tetracycline was up to 96.1% with 120 min light irradiation.
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    Extraction of Thymus dahuricus Serg. Essential Oil by Microwave Method and Activity of Its Main Components
    YAN Hongxiu, JING Xuemin, LIU Xiangping
    2019, 39 (5):  121-128.  doi: 10.3969/j.issn.0253-2417.2019.05.017
    Abstract ( 452 )   HTML ( 7 )   PDF (592KB) ( 575 )   Save
    The optimum extraction conditions of Thymus dahuricus Serg. essential oil by microwave method and the activity of the main components were explored by orthogonal design experiment. The extraction speed and components of essential oil extracted by microwave method was compared with that by steam distillation method. The antioxidant and antimicrobial activities of essential oils extracted by microwave method were also evaluated. The results showed that the optimal parameters were determined as follows:soaking time of 3 h, solid-liquid ratio of 1:1 (g:mL), extraction time of 40 min, microwave power of 540 W. Under this condition, the extraction ratio of essential oil is 1.04%. The main components of essential oil extracted by microwave method were thymol (52.52%), α-terpinene (12.72%) and p-cymene (8.24%), which was consistent with those obtained by conventional steam distillation extraction. The results of antioxidant activity evaluation showed that among the main components, thymol had the strongest DPPH·scavenging activity (IC50=473.63 mg/L) and the highest β-carotene inhibition rate (IC50=250.91 mg/L). Among the three main components, only the p-cymene had no antioxidant activity. In vitro antimicrobial experiments showed that among three main components of T. dahuricus. essential oil thymol had the strongest antimicrobial activity and was followed by α-terpinene. p-Cymene showed no inhibitory activity on all tested strains. Thymol showed the strongest inhibitory activity against Bacillus subtilis among all tested strains with the diameter of inhibitory zone of 16.85 cm and the minimum inhibitory concentration (MIC) of 0.23 g/L.
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