A series of experiments were conducted in a self-made smog chamber at （300 ＋ 1） K and 1.01 × 10^5 Pa to simulate the photochemical reaction of ethyl methyl sulfide （EMS） and NOx. The results showed that the ...A series of experiments were conducted in a self-made smog chamber at （300 ＋ 1） K and 1.01 × 10^5 Pa to simulate the photochemical reaction of ethyl methyl sulfide （EMS） and NOx. The results showed that the higher the initial concentration of EMS, the more ozone was generated in the simulative reactions. It was found that the light intensity plays a very important role in the evaluation of ozone formation potential for EMS. The parameters of d（Oa-NO） and IR （incremental reactivity） were used to quantify the potential of EMS on ozone formation. The obtained maximum IR values in this article for the five simulative reactions were 1.55 × 10^-2, 0.99 × 10^-2, 1.36 × 10^-2, 2.47 × 10^-2, and 1.65 × 10^-2, respectively. A comparison between the results we obtained here and the results we obtained previously for di-tert-butyl peroxide and acetylene showed that the potential reactivity of EMS on ozone formation was at a relatively low level.展开更多
The rate constants for the ozone reactions with n-butyl methyl sulfide (n-BMS, CH3CH2CH2CH2SCH3), sec-butyl methyl sulfide (s-BMS, CH3CH2(CH3)CHSCH3) and tert-butyl methyl sulfide (t-BMS, (CH3)3CSCH3) were measured us...The rate constants for the ozone reactions with n-butyl methyl sulfide (n-BMS, CH3CH2CH2CH2SCH3), sec-butyl methyl sulfide (s-BMS, CH3CH2(CH3)CHSCH3) and tert-butyl methyl sulfide (t-BMS, (CH3)3CSCH3) were measured using our smog chamber under supposedly pseudo-first-order conditions at 300±2 K and 760 Torr. The experimental determined rate constants for n-butyl, s-butyl and t-butyl methyl sulfide are (1.23 ± 0.06)×10-19, (5.08 ± 0.19)×10?20 and (2.26 ± 0.14)×10?20 cm3·molecule-1·s-1, respectively. The reactivity-structure relationship of the reactions was discussed and used to illustrate the mechanism of the ozone reaction with thioethers. The results enrich the kinetics data of atmospheric chemistry.展开更多
Cutinases are hydrolytic enzymes used by phytopathogenic fungi to gain entry into plants by breaking down the cuticular barrier of higher plants. Cutinase displayed hydrolytic activity not only towards cutin, the main...Cutinases are hydrolytic enzymes used by phytopathogenic fungi to gain entry into plants by breaking down the cuticular barrier of higher plants. Cutinase displayed hydrolytic activity not only towards cutin, the main component of the plant cuticle, but also towards a variety of soluble synthetic esters, insoluble triglycerides and polyesters. Therefore, cutinase was evaluated for use in the chemical, food and cotton bio-scouring industry and for synthetic fibers modification. This research examined the production and purification of extracellular cutinase from the phytopathogenic fungus Fusarium oxysporum. The addition of apple cutin or its hydrolysate to the fungus growth medium resulted in an enhanced secretion of cutinase into the extracellular fluid. Testing 1-hexadecanol as an alternative to natural cutin to induce cutinase production resulted in a high process yield under modified growth conditions. Cutinase enzyme production was followed by an optimized purification method for enzyme preparation using high-performance liquid chromatography and high-specificity 4-nitrophenyl (16-methyl sulfide ester) hexadecanoate (pNMSEH) cutinase substrate. Electrophoresis sodiumdodecyl sulfate-polyacrylamide and isoelectric focusing gels enabled the final separation and identification of the protein. The purified cutinase had an approximate molecular weight of 20 kDa and an isoelectric point of 4.7. The method presented here could be modified and used for cutinase production and purification in other microorganisms that exhibit cutinolytic activity.展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No. KZCX2-YW-205)the National Natural Sci-ence Foundation of China (No. 20577052, 20673123,20503035).
文摘A series of experiments were conducted in a self-made smog chamber at （300 ＋ 1） K and 1.01 × 10^5 Pa to simulate the photochemical reaction of ethyl methyl sulfide （EMS） and NOx. The results showed that the higher the initial concentration of EMS, the more ozone was generated in the simulative reactions. It was found that the light intensity plays a very important role in the evaluation of ozone formation potential for EMS. The parameters of d（Oa-NO） and IR （incremental reactivity） were used to quantify the potential of EMS on ozone formation. The obtained maximum IR values in this article for the five simulative reactions were 1.55 × 10^-2, 0.99 × 10^-2, 1.36 × 10^-2, 2.47 × 10^-2, and 1.65 × 10^-2, respectively. A comparison between the results we obtained here and the results we obtained previously for di-tert-butyl peroxide and acetylene showed that the potential reactivity of EMS on ozone formation was at a relatively low level.
基金Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-205)National Basic Research Program of China (973 Program) (Grant No. 2006CB403701)National Natural Science Foundation of China (Grant Nos. 20577052 and 20673123)
文摘The rate constants for the ozone reactions with n-butyl methyl sulfide (n-BMS, CH3CH2CH2CH2SCH3), sec-butyl methyl sulfide (s-BMS, CH3CH2(CH3)CHSCH3) and tert-butyl methyl sulfide (t-BMS, (CH3)3CSCH3) were measured using our smog chamber under supposedly pseudo-first-order conditions at 300±2 K and 760 Torr. The experimental determined rate constants for n-butyl, s-butyl and t-butyl methyl sulfide are (1.23 ± 0.06)×10-19, (5.08 ± 0.19)×10?20 and (2.26 ± 0.14)×10?20 cm3·molecule-1·s-1, respectively. The reactivity-structure relationship of the reactions was discussed and used to illustrate the mechanism of the ozone reaction with thioethers. The results enrich the kinetics data of atmospheric chemistry.
文摘Cutinases are hydrolytic enzymes used by phytopathogenic fungi to gain entry into plants by breaking down the cuticular barrier of higher plants. Cutinase displayed hydrolytic activity not only towards cutin, the main component of the plant cuticle, but also towards a variety of soluble synthetic esters, insoluble triglycerides and polyesters. Therefore, cutinase was evaluated for use in the chemical, food and cotton bio-scouring industry and for synthetic fibers modification. This research examined the production and purification of extracellular cutinase from the phytopathogenic fungus Fusarium oxysporum. The addition of apple cutin or its hydrolysate to the fungus growth medium resulted in an enhanced secretion of cutinase into the extracellular fluid. Testing 1-hexadecanol as an alternative to natural cutin to induce cutinase production resulted in a high process yield under modified growth conditions. Cutinase enzyme production was followed by an optimized purification method for enzyme preparation using high-performance liquid chromatography and high-specificity 4-nitrophenyl (16-methyl sulfide ester) hexadecanoate (pNMSEH) cutinase substrate. Electrophoresis sodiumdodecyl sulfate-polyacrylamide and isoelectric focusing gels enabled the final separation and identification of the protein. The purified cutinase had an approximate molecular weight of 20 kDa and an isoelectric point of 4.7. The method presented here could be modified and used for cutinase production and purification in other microorganisms that exhibit cutinolytic activity.
