[Show abstract][Hide abstract] ABSTRACT: The enantioselective interaction between penicillium expansum alkaline lipase and chiral phenoxypropionic acid herbicide dichlorprop was studied by using UV differential spectrophotometry and fluorescence spectrophotometry in the presence of a pH 8, phosphate buffer solution. Chiral differences in the UV absorption and fluorescence spectra of lipase with dichlorprop were detected. (R)-Dichlorprop interacted the strongest with lipase as measured by both UV absorption and fluorescence spectrophotometry, followed by (Rac)-dichlorprop, while (S)-dichlorprop had the weakest interaction. The hydrophobic interaction seem to play the dominant role in the interactions and the (R)-enantiomer needed the minimum put of energy to drive the endothermic reaction, while the Rac-type and S-type compounds needed more for the reaction to take place. In the meantime, the catalytic hydrolysis of FDA with lipase show that (R)-DCPP could inhibit lipase the most strongly relatively at the same condition, perhaps because (R)-DCPP had a stronger combining effect and high enantiomeric selectivity on lipase than (Rac)-DCPP and (S)-DCPP.
[Show abstract][Hide abstract] ABSTRACT: There exists a close relationship between plants and chiral compounds. On one hand, plants can secrete and synthesize some chiral compounds such as glucosides, enzymes, terpenoids, organic acids and phytohormones that play important roles in plant physiological and biochemical processes, and on the other hand, artificial synthetic chiral compounds, especially pesticides, had enantioselective interactions with plants. The pesticides can enantioselectively inhibit the growth of plants, or can be enantioselectively absorbed and metabolized by plants. Therefore, in the exploitation, production and application of chiral compounds, it's needed to consider the enantioselective interaction between plants and chiral compounds. In the meanwhile, choosing appropriate plants to ameliorate the environment polluted by chiral compounds is of practical significance. In this review, the enantioselective interaction between plants and chiral compounds was summarized, and the amelioration of chiral compounds-polluted environment by plants was prospected.
No preview · Article · Mar 2008 · Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban
[Show abstract][Hide abstract] ABSTRACT: Comparative study on the activity and kinectic properties of acid phosphatase (ACPase) of three soils amended with Hg and Cu at constant temperature and humidity was carried out. The results indicated that the inhibition on ACPase of the three sample soils by Hg and Cu varied with the content of soil organic matter and pH, where, Soil 1 was the most seriously contaminated due to its lowest content of organic matter and the lowest pH among three samples, Soil 2 took the second place, and Soil 3 was the least contaminated. Except Soil 3, the activity of soil ACPase tended to increase along with the contact time under the same type and the same concentration of heavy metal. In particular the V
max values of ACPase in all three samples decreased with increasing Hg and Cu concentration, whereas the K
m values were affected weakly. According to the change of V
max and K
m values, Cu and Hg had the same inhibition effect on soil ACPase. Both of them may be a type of compound of non-competitive and anti-competitive inhibition. Statistic analyses indicated that activities of soil ACPase and V
max values could serve as bioindicator to partially denote the heavy metal Hg and Cu contamination degree.
Preview · Article · Jun 2007 · Journal of Zhejiang University - Science A: Applied Physics & Engineering
[Show abstract][Hide abstract] ABSTRACT: The supramolecular complexes of fenoxaprop-p-ethyl and various cyclodextrins (beta-CD, HP-beta-CD, RAMEB) were studied by UV spectra technique. The results showed that all cyclodextrins could form 1:1 inclusion complexes with fenoxaprop-p-ethyl in ethanol-water (the volume ratio of ethanol to water was 1 : 4), and the binding constants of the three types of cyclodextrins toward fenoxaprop-p-ethyl were in the order of KRAEB>KHP-beta-CD>Kbeta-CD. Between 298. 15 and 318. 15 K, the binding constants decreased with temperature increasing. The Gibbs free energy deltaG, enthalpy change deltaH, and entropy change deltaS determined were all negative, suggesting that the inclusion complexation is exothermic and can spontaneously occur by the balance of enthalpy driving and entropy opposing.
No preview · Article · Jan 2007 · Guang pu xue yu guang pu fen xi = Guang pu
[Show abstract][Hide abstract] ABSTRACT: The enantiomers of napropamide were separated by normal phase HPLC (HPLC: high performance liquid Chromatography) with Chiralpak OJ-H column and charactered by circular dichroism. On this basis, a method for the chiral separation and micro-determination of napropamide in water was established. The linearity of calibration curve for racemic mixture was 10-100 ng x mL(-1) and the correlation coefficient was 0. 99. When 10 microL was injected, the detection limit of racemic mixture was 8 ng mL(-1), and the detection limits of both enantiomers were 4 ng x mL(-1).
No preview · Article · Oct 2006 · Guang pu xue yu guang pu fen xi = Guang pu
[Show abstract][Hide abstract] ABSTRACT: The racemic product of metolachlor contains two R-enantiomers and two S-enantiomers. S-Metolachlor is a more effective herbicidal agent than rac-metolachlor; currently, it is widely used instead of rac-metolachlor. The comparative toxicity of rac- and S-metolachlor was assessed on the basis of their effects on some enzyme activities of the fifth instar of the silkworm, Bombyx mori L. These results suggest that rac-metolachlor and S-metolachlor have different effects on enzyme activities of fifth-instar silkworm larvae. Hemolymph lactate dehydrogenase and catalase activity levels in silkworms treated with rac-metolachlor were much lower than those in silkworms treated with S-metolachlor. Control hemolymph ACP activity was 44–73% higher than that of rac-metolachlor-treated hemolymph, but the difference was not large between S-metolachlor treatment and the control. Midgut alkaline phosphatase activity of silkworms treated with rac-metolachlor was 46% lower than control activity, and the effect of S-metolachlor on midgut alkaline phosphatase activity was minor. The difference between the two herbicides was apparent mainly during the first 5 days of the fifth instar, and then gradually disappeared. It is shown that compared with S-metolachlor, rac-metolachlor is more toxic to economically important silkworms because of its effects on some enzymes and on metabolism.
No preview · Article · Jul 2006 · Pesticide Biochemistry and Physiology
[Show abstract][Hide abstract] ABSTRACT: Cyclodextrins (CDs), with hydrophobic interior cavity and hydrophilic external surface, are capable of accelerating or inhibiting chemical degradation of organophosphorus pesticides through forming inclusion complexes between CDs and pesticides. This work evaluated the effects of CDs on hydrolysis of malathion in an attempt to assess their potential application in environmental approach. beta-CD and its two derivatives, randomly methylated beta-CD (RAMEB) and hydroxypropyl beta-CD (HP-beta-CD), were tested. It was found that RAMEB could inhibit the hydrolysis of malathion, and this was the function of pH and temperature, the inhibitory effects increase with increasing concentration of RAMEB and elevating temperature between 15 and 35 degrees C. On the other hand, beta-CD and HP-beta-CD have little or no stabilizing effects on malathion at all pH and temperature studied, except that the large concentration of beta-CD and HP-beta-CD can mildly reduce hydrolysis of malathion. Both 2 mol/L and 5 mol/L urea increase the inhibitory effects of RAMEB on hydrolysis of malathion at 25 degrees C, pH 9.0.
No preview · Article · Feb 2006 · Journal of Environmental Sciences
[Show abstract][Hide abstract] ABSTRACT: Separation of chiral enantiomers and the dissipation of rac-metolachlor and S-metolachlor in soil were evaluated using achiral high-performance liquid chromatography (HPLC) and chiral gas chromatography (GC) methods. Under the experimental conditions the possible metabolite was considered to be N-(2-ethyl-6-methyl-phenyl)-2-hydroxy-acetamide. Because of the presence of two chiral elements (asymmetrically substituted carbon and chiral axis), the baseline separation of metolachlor enantiomers was not achieved. S-metolachlor degraded faster in soil than rac-metolachlor. After a 42-day incubation, 73.4% of rac-metolachlor and 90.0% of S-metolachlor were degraded. However, due to the absence of biological processes the degradation process in sterilized soil showed no enantioselectivity. The results indicated that enantioselective degradations could greatly affect the environmental fate of metolachlor and should be considered when the environmental behavior of these compounds was assessed.
[Show abstract][Hide abstract] ABSTRACT: The effect of kaolinite on the enzymatic chiral hydrolysis of methyl dichlorprop enantiomers ((R,S)-methyl-2-(2,4- dichlorophenoxy) propanoic acid, 2,4-DPM) was investigated using chiral gas chromatography. Compared with the control without kaolinite, the enantiomeric ratio (ER) increased from 1.35 to 8.33 and the residual ratio of 2,4-DPM decreased from 60.89% to 41.55% in the presence of kaolinite. Kaolinite likely had emotion influence on lipase activity and its enantioselectivity. Moreover, the amount of kaolinite added was also found to be a sensitive factor affecting the enantioselective hydrolysis of 2,4-DPM. Fourier transform infrared (FTIR) spectroscopy studies of the interaction of lipase with kaolinite provided insight into the molecular structure of the complex and offered explanation of the effects of kaolinite on enzymatic hydrolysis of 2,4-DPM. Spectra showed that the effect of kaolinite on the hydrolysis of 2,4-DPM was affected by adsorption of lipase on kaolinite and changes of adsorbed lipase conformation, which led to the modified enantioselectivity.
Preview · Article · Nov 2005 · Journal of Zhejiang University SCIENCE B
[Show abstract][Hide abstract] ABSTRACT: Enantioselective Degradation of 2,4-Dichlorprop methyl ester was studied by sediment bacteria. One DCPPM-degrading bacteria stain was isolated from contaminated sediments. The EF values were determined by chiral GC. The enantioselectivity of DCPPM biodegradation in aquatic phases were evaluated. Incubation with DCPPM-degrading bacteria show that the R enantiomer was preferentially degraded over the corresponding S enantiomer of DCPPM. The EF values show a much higher deviation. It indicate that the microbial degradation of DCPPM was enantioselectivety.
No preview · Article · Aug 2005 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]
[Show abstract][Hide abstract] ABSTRACT: Chemical oxygen demand (COD) removal rates of sulfosalicylic acid (SSal) degraded by three advanced oxidation processes (AOPs): O3/UV, O3/TiO2/UV and O3/V-O/TiO2 are compared in this paper. (V = Vanadium). The results show that O3/V-O/TiO2 is the most effective process among three AOPs and the order of degradation efficiencies at different pH values is shown as O3/V-O/TiO2 > O3/TiO2/UV > O3/UV. For example, at the buffered solution of pH 6.8, the COD removal rate of O3/V-O/TiO2 reaches 70% in 30 minutes, but those of O3/TiO2/UV and O3/UV are 55% and 47% at the same conditions, respectively. Furthermore, the effect of CO3 2 −on the COD removal rates of three AOPs shows that O3/V-O/TiO2 and O3/TiO2/UV may be considerable promising methods to overcome the limitation of the presence of radical scavenger in solution. Both the adsorption of SSal on catalysts and other oxidants (atom oxygen, photo-generated hole) must be responsible for the above result.
No preview · Article · Jun 2005 · Ozone Science and Engineering
[Show abstract][Hide abstract] ABSTRACT: The relationship between excess thermodynamic function and binding to urease of four chloroacetanilide herbicides was studied using high-performance liquid chromatography and fluorescence spectrum. The linear relationship between the composition of mobile phase of RP-HPLC and the capacity factor of chloroacetanilide herbicides has been obtained. The excess thermodynamic enthalpy (deltaH* ) of acetochlor, pretilachlor, butachlor and metolachlor was determined, and the binding constant K and the number of binding sites with urease were calculated. The relationship between excess thermodynamic function and the binding constant K was suggested.
No preview · Article · Apr 2005 · Guang pu xue yu guang pu fen xi = Guang pu
[Show abstract][Hide abstract] ABSTRACT: Through cation-exchanging of montmorillonite, mixed hydroxy Fe-Al-pillared montmorillonites with large basal spacing were synthesized. The application of these mixed hydroxy Fe-Al-pillared montmorillonites as adsorbents in the areas of environmental protection and pollution control was investigated. Adsorption of Direct Green B, an organic dye, on OH--Fe--, OH--Al--, OH--Fe--Al-- pillared montmorillonites was studied. Results showed that these pillared montmorillonites had much better adsorption properties than traditional Na-organo-montmorillonite. It was also found that pH of the solutions had great effect on the performance of these hydroxy-metal pillared montmorillonites in treating the wastewater containing Direct Green B.
No preview · Article · Feb 2005 · Journal of Environmental Sciences
[Show abstract][Hide abstract] ABSTRACT: The effect of beta-cyclodextrins (beta-CDs) on the enzymatical hydrolysis of chiral dichlorprop methyl ester (DCPPM) was studied. Four kinds of beta-cyclodextrins (beta-cyclodextrin, Partly methylated-CD (PM-beta-CD), hydroxypropyl-cyclodextrin (HP-beta-CD) and carboxymethyl-cyclodextrin (CM-beta-CD)) were used. Compared with 100% DCPPM in the absence of betacyclodextrins, the activity of lipase decreased with the increase of Pbetacyclodextrin and PM-Pbetacyclodextrin. However, CM-beta-clodextrin stimulated the lipase activity. The inhibition effect of Pbeta cyclodextrin and PM-5betacyclodextrin on the hydrolysis of DCPPM is affected by many factors other than degree of the methylation blocking the active site of lipase. UV-Vis and Fourier transform infrared (FTIR) spectroscopy studies of the complexation of aqueous DCPPM with beta-CDs provide fresh insight into the molecular structure of the complex and explain the effects of beta-CDs on enzymatical hydrolysis of chiral DCPPM. Data showed that inclusion complexes had formed by complexation of the CM-beta-CD with DCPPM and the solubility of DCPPM was increased in water, which lead to the increased lipase activity.
Full-text · Article · Feb 2005 · Journal of Environmental Sciences
[Show abstract][Hide abstract] ABSTRACT: Hydrolytic degradation of the herbicide diclofop-methyl was investigated in the multi-pH deionized water, natural aquatic systems and soil suspensions. Resulting data indicated that the herbicide was stable in the acidic and nearly neutral solutions for at least 15 d. The herbicide diclofop-methyl rapidly dissipated in the natural aquatic systems and soil suspensions with half-lives less than 4 d. Methyl-CD (partially methylated beta-cyclodextrin) improved its hydrolytic degradation in the pH 8 deionized water and natural aquatic systems while humic acid inhibited its hydrolytic degradation at the same conditions. But dissolved organic matter in the natural aquatic systems and soil suspensions increased its hydrolysis. Two catalysis mechanisms were introduced to describe the effects of cyclodextrin and organic matter on its hydrolytic metabolism. Though inorganic ions maybe improved its hydrolysis reaction in the natural aquatic systems, Fe2+ and Cu2+ did not form complexes with the herbicide and had poor influences on its hydrolytic degradation whether cyclodextrin was added or not.
Preview · Article · Feb 2005 · Journal of Environmental Sciences
[Show abstract][Hide abstract] ABSTRACT: Reactive Red 195, which is an azoic anionic dye characterized by the presence of five sulfonic groups and one azoic group, is efficiently removed using chitosan. The increasing chitosan dose had a dramatic positive impact on the achieved color removal, there was approximately a linear relationship between chitosan dose and color removal of dye before color removal reach maximum. Also, the increase of dye concentration led to the increase of chitosan dosage in order to get the same color removal. 92 mg/L of chitosan dosage was sufficient to achieve complete remove of dye at initial concentration of dye at 200 mg/L. For the higher concentrations of dye, high dosages were necessary to reach complete color removal. On the other hand, the use of adsorption interferents (Fe2+, Na+, HCO3- and others) can be interesting, addition of ions had effect on the color removal of Reactive Red 195. Comparing with blank, addition of chemical species approximately decreased the color removal except Na+ and combination of Fe2+ + HCO3-. However, comparing with Fe2+ alone and HCO3- alone, combination of Fe2+ + HCO3- increased the color removal.
Full-text · Article · Feb 2005 · Journal of Environmental Sciences
[Show abstract][Hide abstract] ABSTRACT: Conformational and activity changes of acid phosphatase from wheat germ in ethanol solutions of different concentrations were measured by fluorescence spectra and differential UV-absorption spectra. The effect of ethanol on kinetics of acid phosphatase was determined by using the double reciprocal plot. The results indicate the ethanol has a significant effect on the activity and conformation of acid phosphatase. The activity of acid phosphatase decreased linearly with increasing the concentration of ethanol. Differential UV-absorption spectra of the enzyme denatured in ethanol solutions showed two positive peaks at 213 and 234 nm, respectively. The peaks on the differential UV-absorption spectra suggested that the conformation of enzyme molecule changed from orderly structure to out-of-order crispation. The fluorescence emission peak intensity of the enzyme gradually strengthened with increasing ethanol concentration, which is in concordance with the conformational change of the microenvironments of tyrosine and tryptophan residues. The results indicate that the expression of the enzyme activity correlates with the stability and integrity of the enzyme conformation to a great degree. Ethanol is uncompetitive inhibitor of acid phosphatase.
No preview · Article · Dec 2004 · Guang pu xue yu guang pu fen xi = Guang pu
[Show abstract][Hide abstract] ABSTRACT: Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional methods, 1H-NMR and MS. This technology belongs to the modern concept of environmentally friendly low wastes or non-wastes technology (LWNWT).
Preview · Article · Sep 2004 · Journal of Zhejiang University SCIENCE
[Show abstract][Hide abstract] ABSTRACT: The removals of humic acid and turbidity by polyferric chloride under different coagulation conditions were studied (pH = 4, 7, 10). Zeta potential, turbidity and humic acid removal efficiency were analyzed. Experimental results showed that the dosage and scope of polyferric chloride (PFC) is the narrowest and the residual turbidity is biggest when pH = 4, the dosage and scope of PFC is the broadest and the residual turbidity is the least when pH = 10; Fe(III) can complex with humic acid under acidic condition; The effect of flocculation is not influenced by the presence of humic acid.
No preview · Article · Jun 2004 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]
[Show abstract][Hide abstract] ABSTRACT: In this paper, the modified target factor analysis-UV spectrophotometry method is established for simultaneous determination of paraquat CL, cyanzine, metolachlor and atrazine in mixed herbicides. The experimental results show that the recovery of each herbicide by MTFA is more accurate than by TFA. The recovery of paraquat CL ranges from 99.47% to 102.02%, of cyanzine 98.93%-102.75%, of metolachlor 98.13%-102.65% and of atrazine 97.42%-103.20%, with SD for the four components to be 1.16%, 1.84%, 1.84% and 2.55% respectively. All in all, the modified target factor analysis method can be used to determine accurately mixed herbicides which exhibits intrinsic interaction among components.
No preview · Article · May 2004 · Guang pu xue yu guang pu fen xi = Guang pu