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Table of Content

    30 December 2005, Volume 25 Issue 04 Previous Issue    Next Issue
    研究报告
    STUDY ON ETHYNYLATION OF TERPENYLACETONES UNDER NORMAL PRESSURE
    BI Liang-wu;ZHAO Zhen-dong;LI Dong-mei;WANG Jing;GU Yan
    2005, 25 (04):  1-5. 
    Abstract ( 608 )   PDF (754KB) ( 697 )   Save
    α,β-Unsaturated alkynyl alcohols, such as dehydronerolidol, dehydrogeranyllinalool, and dehydroisophytol, were prepared by ethynylation of turpentine derivatives,namely terpenylacetones, e.g. geranylacetone, farnesylacetone, and phyton under normal pressure in presence of alkali metal hydroxide and organic solvents. Results of ethynylation were influenced by factors, such as, reaction temperature, reaction time, variety of solvent, and amount of alkali. The yields of dehydronerolidol, dehydrogeranyllinalool, and dehydroisophytol, under suitable conditions of ethynylation of the three terpenylacetones, were 85.7%, 86.7%, and 74.4%, respectively.
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    PRODUCTION OF CELLULASE-POOR XYLANASE BY BATCH AND FED-BATCH FERMENTATIONS
    YONG Qiang;CHEN Mu;JING Yi;YOU Ji-xue;YU Shi-yuan
    2005, 25 (04):  6-10. 
    Abstract ( 727 )   PDF (756KB) ( 563 )   Save
    Preparation of cellulase-poor xylanase by Trichoderma reesei Rut C 30 in batch and fed-batch fermentations and its application on biobleaching were investigated. The xylanase activity, xylanase volumetric productivity and xylanase yield in batch fermentation were 152.09 IU/mL,2 112.4 IU/(L·h) and 10 139.3 IU/g xylan, respectively, when 15 g/L xylan was employed as carbon source. Compared to batch fermentation, xylanase formation in fed-batch culture,in which 17 g/L xylan was employed as carbon source, was more efficient and the xylanase activity, xylanase volumetric productivity and yield were 252.14 IU/mL,3 501.9 IU/(L·h) and 14 831.8 IU/g xylan, respectively. When straw pulp was pretreated with the xylanase-poor xylanase followed by a hypochlorite bleaching, a pulp brightness of 2%-5% (SBD) higher than that of the untreated one under the same hypochlorite dosage could be obtained, or 43% of active chlorine consumption could be saved under the same brightness.
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    STUDY ON CURING MECHANISM OF LOW-FORMALDEHYDE-EMISSION UREA-FORMALDEHYDE RESINS
    GU Ji-you;ZHU Li-bin;ONO Hirokuni
    2005, 25 (04):  11-16. 
    Abstract ( 759 )   PDF (876KB) ( 1380 )   Save
    Based on evaluation of chemical structures of three typical urea-formaldehyde(UF)resins by 13C NMR, the techniques of torsion braid analysis (TBA) and differential scanning calorimetry (DSC) were applied, respectively, in order to analyze dynamic viscoelasticity and curing characteristics of these UF resins in different curing systems. UF resins from different formulations have quite different chemical structures, in which the modifier, melamine, was well copolymerized with urea. The relative rigidity of UF resins without curing agent was kept almost consistent during heating-up, then decreased quickly when temperature reached 128℃,which indicated that no crosslinking reaction occurred, and exhibited only the thermoplasticity of the resin. When temperature was higher than 135℃, crosslinking started. The curing mechanisms of UF resins in different curing systems were different from each other. UF resin without modifier started its curing reaction at lower temperature and gave off more heat during the more violent reaction. Curing of both UF resins modified by melamine or modifier M gave off less heat and proceeded more stably.
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    STUDY ON BIODEGRADABLE MATERIAL FROM POLY-(L-LACTIC ACID)-ETHYLCELLULOSE BLENDS
    GAO Qin-wei;LI Ming-zi;DONG Xiao;QIAN Jun
    2005, 25 (04):  17-20. 
    Abstract ( 764 )   PDF (658KB) ( 778 )   Save
    Biodegradable material was prepared from blends of poly(L-lactic acid) (PLLA) and ethylcellulose (EC) by mixing their respective chloroform solutions at different proportions, followed by membrane-casting. The obtained blends were characterized with FT-IR, DSC, and X-ray diffraction. PLLA and EC are liable to form interpolymeric hydrogen bonds and PLLA could crystallize in the blend. With increased dosage of EC, melting point of PLLA-EC blend decreased slightly and crystallinity and crystal perfection of the blend decreased notably, while hydrophilicity increased. Degradation of PLLA-EC blends increased greatly at EC content more than 30%, and reached a maximum at EC content 80%, owing to the above-mentioned factors.
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    FT-IR ANALYSIS OF CARBONIZED BAMBOO CATALYZED BY PHOSPHORIC ACID
    ZUO Song-lin;JIANG Xiao-hua
    2005, 25 (04):  21-25. 
    Abstract ( 637 )   PDF (779KB) ( 948 )   Save
    Fourier transform infrared (FT-IR) spectroscopy was used in attempt to illustrate the pyrolysis of bamboo and evolution of chars under the catalysis of phosphoric acid. FT-IR spectra indicate that phosphoric acid can significantly catalyze the pyrolysis of the chemical components, especially the pyrolysis of lignin, formation and condensation of aromatic rings, and formation of graphite-like micro-crystals in chars. In the case of phosphoric acid as catalyst,the course of bamboo carbonization can be divided into two stages. In the former stage (below 400℃), are mainly the thermal decomposition of the constiuents and formation of aromatic rings. In the latter stage (above 400℃) are the formation and condensation of aromatic rings, as well as formation of graphite-like micro-crystals. Thereby, FT-IR is a feasible and effective approach to investigate the course of pyrolysis of cellulosic biomass and evolution of micro-structure of the derived chars.
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    STUDIES ON FREE-RADICAL SCAVENGING ABILITIES OF FOUR CATECHINS AND THEIR BLENDED COMPOSITE
    LUO Yi-fan;GUO Zhen-fei;XU Xuan;CHEN Jian-jing
    2005, 25 (04):  26-30. 
    Abstract ( 683 )   PDF (1235KB) ( 940 )   Save
    The objectives of this paper were to study the free-radical scavenging abilities of four catechins and their blended composite toward superoxide radical anion (O2·-) and hydroxyl radical (OH·), and to make a comparison with each other using a chemiluminescence technique. The results showed that EGCG, ECG, EGC and EC could scavenge O2·- at SC50 values of 4.2, 4.9, 5.2 and 6.2 μmol/L respectively, and scavenge OH· at SC50 values of 0.22, 0.25, 0.26 and 0.30 μmol/L respectively. The scavenging rates at the same total concentration of four catechins were as follows: EGCG > ECG > EGC > EC. In addition, orthogonal experimental was used to obtain the optimal ratio of four catechins. The optimal blended composite of scavenging rate toward O2·- and OH· were found to be EGCG:ECG:EGC:EC 3:3:1:1. EGCG was the most important factor and was of the most significance. The scavenging rate of four-catechin composite was higher than those of corresponding individual catechins while EGCG in the composite was high in proportion.
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    STUDY ON MAKING ACTIVATED CARBON FROM BAMBOO SAWDUST BY PHOSPHORIC ACID METHOD
    DENG Xian-lun;JIANG Jian-chun;JIANG Zhao-xiong
    2005, 25 (04):  31-34. 
    Abstract ( 577 )   PDF (601KB) ( 796 )   Save
    Activated carbon was manufactured from bamboo sawdusts and chips, activated with phosphoric acid. The product has abundant meso-pore volume and can be applied to adsorb coloring matters of various molecular sizes, possessing excellent decolorization effects for solutions of citric acid,etc.
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    STUDY ON PREPARATION OF ACTIVATED CARBON FROM POLYPHENOL CHAR
    ZHANG Tian-jian
    2005, 25 (04):  35-37. 
    Abstract ( 571 )   PDF (456KB) ( 852 )   Save
    Activated carbon was prepared from polyphenol char through steam activation. Suitable technological conditions are: activation temperature 800-850℃, activation time 1.0 h for particle activated carbon and 2.5-3.0 h for granular activated carbon. The adsoption capability of activated carbon from this char is higher than that specified for activated carbon from wood used for water purification( GB/T 13803.2-1999),with iodine number >1 000 mg/g, methylene blue adsorption >12 mL/0.1 mg.It was also showed that the method of phosphoric acid activation is unsuitable to prepare activated carbon from polyphenol char.
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    STUDY ON PREPARING TERPINEOL CATALYZED BY H-MORDENITE MOLECULAR SIEVE
    ZHU Kai;XU Bin;ZHANG Gang
    2005, 25 (04):  38-42. 
    Abstract ( 696 )   PDF (1186KB) ( 861 )   Save
    α-Terpineol was synthesized in one-step with α-pinene and β-pinene from turpentine oil as primary materials, using H-mordenite molecular sieve(H-M) as catalyst in the presence of quaternary ammonium salt(QX),to carry out simultaneously the reactions of ring-opening, rearrangement and hydration. Factors affecting product yield were investigated by L16(45) orthogonal experiment, to obtain optimum technological condition as follows: reaction temperature 80℃, QX mass fraction 8%, mH-M:mpinene value 0.6, methylacetate:mpinene value 0.9, mH2O: mpinene value 1.4. α-Terpineol yield was 43.5% under this technological condition.The products were measured by GC-MS, and 15 components were identified. Main components are pinene, limonene, eucalyptol, 1-methyl- 4-(1-methylethyl)-1,4-cyclohexadiene, borneol and(+)-α-terpineol. An optically active α-terpineol was obtained with optical rotation +61°. The product with right pure odor is useful as a fragrance.
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    COMPARATIVE STUDY ON THE EXTRACTION OF VOLATILE OIL FROM RHIZOMES OF ACORUS TATARINOWII S.
    DAI Jian;HA Cheng-yong;ZHANG Jing-cheng;LIU Jun-ling
    2005, 25 (04):  43-46. 
    Abstract ( 661 )   PDF (706KB) ( 1070 )   Save
    Volatile oil from rhizomes of Acorus tatarinowii S. was extracted by supercritical CO2 fluid procedure coupled to a fractional separation. The oil obtained was compared with the one isolated by hydrodistillation(HD).Chemical analysis revealed that these two volatile oils possessed widely different relative contents.The oil obtained by supercritical CO2 fluid extraction (SCFE) showed higher relative contents of monoterpene and sesquiterpene hydrocarbons than by HD. Relative contents of oxygenated monoterpene and sesquiterpene were higher in the oil isolated by HD than by SCFE. Relative content of the main effective constituent, namely β-asarone, in the SCFE oil was 52.84% and in the HD oil 38.67%,which showed that SCFE had good selectivity for the extraction of β-asarone.
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    STUDY ON METHOD OF ISOLATION AND PURIFICATION OF BISEPOXYLIGNANS IN EUCOMMIA ULMOIDES OLIV.
    QI Xiang-yang;CHEN Wei-jun;ZHANG Sheng-hua
    2005, 25 (04):  47-50. 
    Abstract ( 681 )   PDF (590KB) ( 1034 )   Save
    The new method of isolation and purification of (+)-pinoresinol-di-β-D-glucopyranoside(PG)and (+)-syringaresinol di-β-D-glucopyranoside (SG) from Eucommia ulmoides Oliv.was studied. PG and SG were isolated through column chromatography packed with different resins, and the best isolation condition was established according to the results of HPLC analysis. Ethanol extracts was concentrated, centrifugated and then separated by column packed with D101 resin under alkaline condition.The isolated yield was 1.74%, the contents of PG and SG were 8.139 7% and 2.943 1%, respectively. The extract was further purified by means of Sephadex LH-20 column chromatography, followed by preparative HPLC and recrystallization, to obtain two crystals which were characterized as PG and SG by melting point determination, HPLC, TLC, IR, UV and ~1H NMR analysis. Compared with tradition method, the new isolation technology was simple and safe with high yield of product.
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    QUANTITATIVE RELATIONSHIP BETWEEN LIGNIN OXIDATION AND DELIGNIFICATION DURING OXYGEN BLEACHING
    TONG Guo-lin;YOKOYAMA Tomoya;MATSUMOTO Yuji;MESHITSUKA Gyosuke;LI Zhong-zheng
    2005, 25 (04):  51-55. 
    Abstract ( 799 )   PDF (763KB) ( 626 )   Save
    Unbleached softwood kraft pulp was subjected to low consistency oxygen bleaching. Total KMnO4 consumptions by lignin in both pulp and effluent were measured and the difference of this value from the KMnO4 consumption by lignin in original unbleached kraft pulp was used as the indication of the extent of oxidation that lignin in the pulp experienced during oxygen bleaching. Extent of lignin oxidation thus estimated well correlated to the delignification. One lignin unit was found to be oxidized by about 3 electrons as an average when Kappa number of the pulp became about half (from 25.4 to 13.4). Methoxyl determination of the bleached pulp suggested that the residual lignin still remaining in the oxygen-bleached pulp was not extensively oxidized. These results confirmed quantitatively that lignin oxidation is essential for the delignification during oxygen bleaching.
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    STUDY ON HYDROGENATION OF α-PINENE TO CIS-PINANE CATALYZED BY NANOMETER NICKEL
    XIE Hui;YANG Sheng-jun;ZHANG Zhi-jie
    2005, 25 (04):  56-58. 
    Abstract ( 617 )   PDF (649KB) ( 669 )   Save
    Nanometer nickel was first used in hydrogenation of α-pinene: the conversion rate of raw material with nanometer nickel as catalyst was higher than that of Raney nickel and the selectivity of cis-pinane was higher than that with Pd/C. The suitable conditions of preparing cis-pinane by hydrogenation of α-pinene catalyzed by nanometer nickel were as follows: temperature 90℃, pressure 4.0 MPa, and dosage of catalyst 1.0% (based on the mass fraction of α-pinene).The conversion rate of α-pinene was 100%,and the selectivity of cis-pinane was 94.3%。
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    WATER-DISPERSIBLE POLYISOCYANATE MADE FROM CASHEW NUT LIQUID
    DANG Xiao-rong;YUAN Qiao-long;WANG De-ning
    2005, 25 (04):  59-62. 
    Abstract ( 600 )   PDF (587KB) ( 680 )   Save
    A surfactant containing both hydrophilic and hydrophobic chain segments with terminal hydroxyl group at one end of the molecular chain was prepared by reacting refined commercial cashew nut liquid with polyethylglycol at molar ratio of 1:1. Part of the —NCO group of isocyanurate in the trimerized hexamethylene diisocyanate was capped by such surfactant to obtain water-dispersible isocyanate(WPI),which could be used as a crosslinking agent for the hydrophilic polyurethane(PU) terminated with hydroxyl group. The pot life of the mixture of PU and WPI was 5 h. The crosslineked film, formed from this mixture by addition of nanometer calsium carbonate showed good resistance against acetone and very high rapture elongation.
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    STUDY ON CHEMICAL CONSTITUENTS OF FRAGRANCE RELEASED FROM FRESH FLOWERS OF SYRINGA OBLATA VAR. AFFINIS DURING DIFFERENT FLORESCENCES
    LI Zu-guang;LI Xin-hua;GAO Jian-rong;LIU Wen-han
    2005, 25 (04):  63-66. 
    Abstract ( 648 )   PDF (703KB) ( 1075 )   Save
    The chemical constituents of fragrance released from fresh flowers of Syringa oblata var. affinis were investigated by means of headspace solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Lilac aldehyde A-D,lilac alcohol A-D, α-pinene, sabinene, β-pinene, myrcene, D-limonene,eucalyptol, cis-ocimene, benzaldehyde, terpinolene, linalool, benzeneacetaldehyde, α-terpineol, p-methoxyanisole, p-anisaldehyde, (Z,E)-α-farnesene and (E,E)-α-farnesene were the most abundant volatiles released from fresh flowers of S. oblata var. affinis and 39 volatile compounds were identified in this study. The four isomers of lilac alcohol and four isomeric lilac aldehydes were the characteristic components of fragrance of fresh flowers of S. oblata var. affinis. Variation of the main constituents in the volatile fragrance from fresh flowers of S. oblata var. affinis during different florescences were also studied. Headspace SPME-GC-MS is a simple sampling method for measuring the variations of main constituents in volatile fragrance from fresh flowers during different florescence.
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    MICROWAVE-ASSISTED EXTRACTION OF ESSENTIAL OIL FROM CITRUS GRANDIS PEEL
    GONG Sheng-zhao;CHENG Jiang;YANG Zhuo-ru
    2005, 25 (04):  67-70. 
    Abstract ( 710 )   PDF (574KB) ( 793 )   Save
    Microwave-assisted extraction(MAE)was used to extract essential oil (EO) from pomelo (Citrus grandis (L.)Osbeck) peel (CGP). Results show that petroleum ether is an optimal solvent and the extraction was affected mainly by stock mass ratio, microwave power, water content and granularity of material. The optimal conditions were obtained. Materials with granularity of 60 mesh and water content of around 7.4% are suitable for extraction. Total solvent-material mass ratio is 14:1. Extraction had to be performed twice with microwave irradiation (300 W) for 3 min each time. Crude EO was obtained after the extracted liquor was concentrated under vacuum. Crude EO was then dissolved with ethanol, frozen at -15℃ for 48 h, and centrifugally separated and filtered to get rid of impurities. The final product EO with yield of 2.09% and purity of 99.0% was then obtained after distilling the liquor under vacuum. Compared with direct-heating extraction (DHE), MAE reduced the extracting time up to 1/20.
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    STUDY ON SYNTHESIS OF ROSIN POLYETHER ESTER DEFOAMER
    JI Yong-xin
    2005, 25 (04):  71-73. 
    Abstract ( 726 )   PDF (572KB) ( 677 )   Save
    Synthesis of rosin polyether ester defoamer was studied in terms of approaching the optimum experimental condition of synthesize and tests of properties. The results for rosin polyether ester show that: dosage of p-toluenesulfonic acid 0.12%, reaction temperature 160-200℃, reaction time 6-7 h.Increase of relative molecular weight (Mw) of PO-EO polyether is favorable to defoaming and antifoaming abilities of fatty alcohol polyether,at nPO:nEO 64-78:10-12, or ratio value 7.25, defoaming and antifoaming abilities of the optimum; For rosin ester of two functional groups, Mw of polyether greater than 4 000,is favourable to defoaming and antifoaming abilities. Howerer, when Mw is greater than 7 000, dispersibility in water declines,which is unfavorable to defoaming ability.Mass ratio of EO in polyether influences defoaming ability. When EO accounts for 10% of rosin polyether ester, defoaming ability is the optimum.
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    ULTRASONIC EXTRACTION OF PIGMENT FROM LEAVES OF VACCINIUM BRACTEATUM THUNB.
    GU Wen-xiu;XIE Wei-ming;XIA Wen-shui;ZHU Chuan-zheng
    2005, 25 (04):  74-78. 
    Abstract ( 646 )   PDF (918KB) ( 713 )   Save
    The optimal processing conditions for ultrasonic extraction of pigment form leaves of Vacciniun bracteatum Thunb. were obtained by single factor and orthogonal tests. The results are: 30 kHz ultrasonic wave, 62% (volume fraction) ethanol as solvent, the ratio of liquid to material is 3.5:1 (mL:g), extracting once for 10 min at room temperature. Ultrasonic extraction has a prime superiority over traditional one. The yield of ultrasonic extraction under optimal processing conditions is 23.84%, higher than that of traditional extraction 11.43%. Furthermore,ultrasonic extraction has advantages of shorter duration, less solvent and energy consumption, and improved quality of products. Moreover, the pigment is stable at pH value<7.0 and temperature below 80℃. Sucrose has little effect on the stability of pigment while citric acid has considerable positive effect on increasing the color and luster, and keeping the stability of pigment. Sodium benzoate and potassium sorbate degrade the pigment quite obviously when their mass fraction are more than 0.01%.
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    COMPARATIVE STUDY ON EXTRACTION METHODS OF TOOSENDANIN
    JIANG Ping;AN Xin-nan
    2005, 25 (04):  79-82. 
    Abstract ( 652 )   PDF (570KB) ( 1180 )   Save
    Extraction methods of toosendanin from Melia azedarach L. were systematically investigated and compared in detail in this paper, including supercritical carbon dioxide extraction, ultrasonic extraction, microwave-assisted extraction and traditional solvent extraction. The results indicated that the ultrasonic extraction method was the preferred one among these methods. In the case of ultrasonic extraction, optimum conditions were as follows: 60% ethanol as solvent, ratio of feedstock to liquor 1:9, extraction time 30 min, temperature 40℃, and ultrasonic power 200 W. Under the optimum conditions, the yield of toosendanin was 0.715%.
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    STUDY ON BACTERIOSTASIS OF BAMBOO VINEGAR AGAINST FOOD-POLLUTING BACTERIA
    CHANG Ya-ning;YU Jian-ying;NI Wei;WO Niao-ping
    2005, 25 (04):  83-85. 
    Abstract ( 543 )   PDF (462KB) ( 770 )   Save
    At first,optimum degree of dilution of Escherichia coli,Staphylococcus aureus and Aspergillus flavus were determined,which are 107,105 and 105 times, respectively.Then minimum inhibitory concentration(MIC) and minimum bactericidal concentration (MBC)of bamboo vinegar against food-plluting bacteria were studied.The experimental result indicated that the bacteriostatic action of bamboo vinegar is the strongest against A. flavus,then is E. coli,the weakest is against S. aureus.The MIC are 7.5,25 and 30 μL/mL,respectively.The MBC are 10,30 and 35 μL/mL,respectively.
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    FAST LIQUEFACTION OF BAGASSE IN ETHYLENE CARBONATE
    XIE Tao;CHEN Fan-geng
    2005, 25 (04):  86-90. 
    Abstract ( 722 )   PDF (677KB) ( 857 )   Save
    Fast liquefaction of bagasse was conducted in ethylene carbonate in the presence of sulfuric acid as catalyst in order to convert bagasse into product for manufacturing epoxy resin adhesive. Effects of temperature, liquid ratio and catalyst dosage for the liquefaction were investigated. Liquefaction products were characterized. Experiments indicated that bagasse can be liquefied 97% in approximately 10-20 min. The hydroxyl number of the liquefied product is in the range of 220-330 mg/g.
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    STUDY ON TECHNOLOGY OF PREPARING ACTIVATED CARBON FROM CORN STALK ASSISTED BY MICROWAVE IRRADIATION
    JIANG Hui;JIANG Wen-ju
    2005, 25 (04):  91-93. 
    Abstract ( 638 )   PDF (501KB) ( 687 )   Save
    Technology of preparing activated carbon from corn stalks with ZnCl2 assisted by microwave irradiation was studied.The optimum technology was obtained through orthogonal test. The product was applied to absorb formaldehyde and compared with marketed activated carbon. When concentration of formaldehyde was 1.94-1.97 mg/m3, penetration time(tB) of this activated carbon was 12 min which was 20% higher than that of marketed activated carbon, and the speed of adsorption was also faster.
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    RESEARCH ON METHOD AND EFFECT OF MICROWAVE TREATMENT ON BAMBOO-CHARCOAL
    ZHANG Qi-wei;WANG Gui-xian
    2005, 25 (04):  94-96. 
    Abstract ( 568 )   PDF (427KB) ( 811 )   Save
    Bamboo-charcoal was pretreated with microwave or microwave with chemical reagent prior to its application. The methods and effects of pretreatment were studied. Results showed that specific surface area and adsorption capacity were elevated remarkably after pretreatment with the above mentioned methods, and the methylene blue adsorption values of bamboo-charcoal were increased over a range of 34%-92%. The methods were used in regeneration of bamboo-charcoal after adsorption of Pb2+, and the percentages of regeneration was up to 96%. The technology could be an effective means for activation of bamboo-charcoal.
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    IMPROVED METHOD TO EXPRESS ENZYME ACTIVITY OF Cx-ENZYME
    LIU Jian;LI Dong-bing;YANG Ji-chu
    2005, 25 (04):  97-99. 
    Abstract ( 632 )   PDF (495KB) ( 548 )   Save
    Cellulase system contains a series of complex components,in which Cx-enzyme is a main member. Traditional assaying method of enzyme activity leads to lots of system mistakes attributable to low and alternative substrate concentration. On account of that, a reasonable new way to show enzyme activity by determining νmax is brought out. The research of this method focuses on the analysis of enzyme activity of Cx-enzyme expressed by Trichoderma koningii AS3.4262 in different concentrations of substrate. The data have been calculated under multiple regression to get initial reaction rates of different substrate concentrations. The values of constant (Km) and maximum reaction rate (νmax) are obtained by using Lineweaver-Burk chart. The benefit of this improved method is to express enzyme activity regardless of varied substrate concentrations.
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    STUDY ON CORROSION-INHIBITION PERFORMANCES OF CALCIUM LIGNOSULPHONATE OF DIFFERENT RELATIVE MOLECULAR WEIGHTS
    QIU Xue-qing;YI Cong-hua;YANG Dong-jie;LOU Hong-ming
    2005, 25 (04):  100-104. 
    Abstract ( 457 )   PDF (863KB) ( 786 )   Save
    Calcium lignosulphonate (CL) was separated into four fractions of different relative molecular weights (Mw) by ultrafiltration and their contents of functional groups were determined. The corrosion-inhibition performances and mechanism of different fractions were studied by weight-loss and electrochemical impedance spectroscopy. Results indicated that contents of carboxyl, phenolic hydroxyl and sulfonic groups decreased with increased Mw. Only the fractions of Mw<5 000 had corrosion-inhibition performance. The fitting results showed that the equivalent circuit models were different with fractions of different Mw. Two time-constants appeared in the electrode system in the solution with Mw between 1 000 and 5 000, which indicated that this fraction could form an inhibitory film on the surface of carbon steel.
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