During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of sy...During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.展开更多
Objective.To study the exact effects and characteristics of a constitutively active myosin light chain kinase fragment (MLCKF)on Ca 2+ -CaM dependent phosphorylation of myosin light chains(CDPM)of smooth muscle.Method...Objective.To study the exact effects and characteristics of a constitutively active myosin light chain kinase fragment (MLCKF)on Ca 2+ -CaM dependent phosphorylation of myosin light chains(CDPM)of smooth muscle.Methods.Proteolysis of myosin light chain kinase(MLCK)by trypsin was used to obtain the con-stitutively active fragment of MLCK;Western blot was applied to demonstrate the homogeneity of typsin-digested MLCK fragments and intact MLCK.The phosphorylation of myosin light chains was detected us-ing SDS-PAGE and Scoin Image Software,and myosin Mg 2+ -ATPase activities were measured using spec-trophotometry to observe the characteristics of MLCKF in phosphorylating myosin light chains and stimu-lating myosin Mg 2+ -ATPase activities compared with intact MLCK.Results.Our assay demonstrated that MLCKF had a specific activity on CDPM.We also found that the extent of CDPM by MLCKF was greater than that by intact MLCK at different concentrations,differ-ent incubation time and different incubation temperatures.CDPM by MLCKF was also less influenced by the change of ionic strength of KCl than CDPM by intact MLCK.Mg 2+ -ATPase activities of phosphorylat-ed myosin light chains by MLCKF were higher than those by MLCK at different concentrations and dif-ferent reaction time.These differences were statistically significant ( P<0.01, P<0.05).Conclusion.MLCKF not only possessed a specific activity on CDPM but also was more efficient than MLCK in phosphorylating myosin light chains and stimulating myosin Mg 2+ -ATPase activities.Our results suggested that MLCKF possibly plays a certain role in smooth muscle contraction-relaxation cycle.展开更多
The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu ...The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2：1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4：1 and copper arsenite was reduced by SO2 at 60℃ for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H2SO4 solution under the action of air. The results show that red residue is Cu3（SO3）2·2H2O and the white powder is As2O3. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H2SO4 to Cu is 1.70, H2SO4 concentration is 24% and the leaching temperature is 80 ℃. The direct recovery rate of copper sulfate is 79.11% and the content of CuSOa·5H2O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution.展开更多
Peel essential oil of bergamot （Citrus bergamia Risso） growing in Tunisia was separated by hydrodistillation and obtained in a yield of 9.7%. The oil composition was investigated using GC and GC-MS with two columns ...Peel essential oil of bergamot （Citrus bergamia Risso） growing in Tunisia was separated by hydrodistillation and obtained in a yield of 9.7%. The oil composition was investigated using GC and GC-MS with two columns HP-I and HP-Innowax. Fifteen compounds accounting for 98.52% of the oil were identified. The oil was characterized by bigb content oflimonene （59.21%）, linalool （9.51%） and linalyl acetate （16.83%）.展开更多
AIM:To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity. METHODS:The effects of YFa and its analogs (D-Ala2) YFa, Y (D...AIM:To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity. METHODS:The effects of YFa and its analogs (D-Ala2) YFa, Y (D-Ala2) GFMKKKFMRF amide and Des-Phe-YGGFMKKKFMR amide in guinea pig ileum (GPI) and mouse vas deferens (MVD) motility were studied using an isolated tissue organ bath system, and morphine and DynA (1-13) served as controls. Acetylcholine was used for muscle stimulation. The observations were validated by specific antagonist pretreatment experiments using naloxonazine, naltrindole and norbinaltor-phimine norBNI. RESULTS:YFa did not demonstrate significant inhibition of GPI muscle contraction as compared with mor-phine (15% vs 62%, P = 0.0002), but moderate inhibition of MVD muscle contraction, indicating the role of κ opioid receptors in the contraction. A moderate inhibition of GPI muscles by (Des-Phe) YFa revealed the role of anti-opiate receptors in the smooth muscle contraction. (D-Ala-2) YFa showed significant inhibition of smooth muscle contraction, indicating the involvement of mainly δ receptors in MVD contraction. These results were supported by specific antagonist pretreatment assays. CONCLUSION:YFa revealed its side-effect-free analgesic properties with regard to arrest of gastroin-testinal transit. The study provides evidences for the involvement of κ and anti-opioid receptors in smooth muscle contraction.展开更多
Se （Ⅳ） contents in rice samples after oxidizing acid digestion were investigated by flow injection-hydride generation atomic absorption spectrometric method （FI-HG-AAS）. The optimization was performed with varyin...Se （Ⅳ） contents in rice samples after oxidizing acid digestion were investigated by flow injection-hydride generation atomic absorption spectrometric method （FI-HG-AAS）. The optimization was performed with varying the formation of gaseous hydrides and the specific pieces of instrumentation. The results of FI-HG-AAS showed good linear calibration curve at the working concentration between 0.10 and 2.00 μg/L （R^2〉0.999）. For 7 replicate determinations of 0.75 μg/L selenium standard solution spiked in deionized water, the precision and accuracy were 2.33% and 86.63%, respectively. The detection limit （3σ/S, n=7） was 0.01 lag/L. Oxidizing acid digestions of rice samples were carried out at the ratio of 5：3 between nitric acid and perchloric acid. This method was succeeded to determine Se （Ⅳ） in acid digestion of rice samples without pre-reduction step with hydrochloric acid and heating.展开更多
文摘During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.
文摘Objective.To study the exact effects and characteristics of a constitutively active myosin light chain kinase fragment (MLCKF)on Ca 2+ -CaM dependent phosphorylation of myosin light chains(CDPM)of smooth muscle.Methods.Proteolysis of myosin light chain kinase(MLCK)by trypsin was used to obtain the con-stitutively active fragment of MLCK;Western blot was applied to demonstrate the homogeneity of typsin-digested MLCK fragments and intact MLCK.The phosphorylation of myosin light chains was detected us-ing SDS-PAGE and Scoin Image Software,and myosin Mg 2+ -ATPase activities were measured using spec-trophotometry to observe the characteristics of MLCKF in phosphorylating myosin light chains and stimu-lating myosin Mg 2+ -ATPase activities compared with intact MLCK.Results.Our assay demonstrated that MLCKF had a specific activity on CDPM.We also found that the extent of CDPM by MLCKF was greater than that by intact MLCK at different concentrations,differ-ent incubation time and different incubation temperatures.CDPM by MLCKF was also less influenced by the change of ionic strength of KCl than CDPM by intact MLCK.Mg 2+ -ATPase activities of phosphorylat-ed myosin light chains by MLCKF were higher than those by MLCK at different concentrations and dif-ferent reaction time.These differences were statistically significant ( P<0.01, P<0.05).Conclusion.MLCKF not only possessed a specific activity on CDPM but also was more efficient than MLCK in phosphorylating myosin light chains and stimulating myosin Mg 2+ -ATPase activities.Our results suggested that MLCKF possibly plays a certain role in smooth muscle contraction-relaxation cycle.
文摘The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2：1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4：1 and copper arsenite was reduced by SO2 at 60℃ for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H2SO4 solution under the action of air. The results show that red residue is Cu3（SO3）2·2H2O and the white powder is As2O3. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H2SO4 to Cu is 1.70, H2SO4 concentration is 24% and the leaching temperature is 80 ℃. The direct recovery rate of copper sulfate is 79.11% and the content of CuSOa·5H2O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution.
文摘Peel essential oil of bergamot （Citrus bergamia Risso） growing in Tunisia was separated by hydrodistillation and obtained in a yield of 9.7%. The oil composition was investigated using GC and GC-MS with two columns HP-I and HP-Innowax. Fifteen compounds accounting for 98.52% of the oil were identified. The oil was characterized by bigb content oflimonene （59.21%）, linalool （9.51%） and linalyl acetate （16.83%）.
基金Supported by Council of Scientific and Industrial Research,Delhi
文摘AIM:To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity. METHODS:The effects of YFa and its analogs (D-Ala2) YFa, Y (D-Ala2) GFMKKKFMRF amide and Des-Phe-YGGFMKKKFMR amide in guinea pig ileum (GPI) and mouse vas deferens (MVD) motility were studied using an isolated tissue organ bath system, and morphine and DynA (1-13) served as controls. Acetylcholine was used for muscle stimulation. The observations were validated by specific antagonist pretreatment experiments using naloxonazine, naltrindole and norbinaltor-phimine norBNI. RESULTS:YFa did not demonstrate significant inhibition of GPI muscle contraction as compared with mor-phine (15% vs 62%, P = 0.0002), but moderate inhibition of MVD muscle contraction, indicating the role of κ opioid receptors in the contraction. A moderate inhibition of GPI muscles by (Des-Phe) YFa revealed the role of anti-opiate receptors in the smooth muscle contraction. (D-Ala-2) YFa showed significant inhibition of smooth muscle contraction, indicating the involvement of mainly δ receptors in MVD contraction. These results were supported by specific antagonist pretreatment assays. CONCLUSION:YFa revealed its side-effect-free analgesic properties with regard to arrest of gastroin-testinal transit. The study provides evidences for the involvement of κ and anti-opioid receptors in smooth muscle contraction.
文摘Se （Ⅳ） contents in rice samples after oxidizing acid digestion were investigated by flow injection-hydride generation atomic absorption spectrometric method （FI-HG-AAS）. The optimization was performed with varying the formation of gaseous hydrides and the specific pieces of instrumentation. The results of FI-HG-AAS showed good linear calibration curve at the working concentration between 0.10 and 2.00 μg/L （R^2〉0.999）. For 7 replicate determinations of 0.75 μg/L selenium standard solution spiked in deionized water, the precision and accuracy were 2.33% and 86.63%, respectively. The detection limit （3σ/S, n=7） was 0.01 lag/L. Oxidizing acid digestions of rice samples were carried out at the ratio of 5：3 between nitric acid and perchloric acid. This method was succeeded to determine Se （Ⅳ） in acid digestion of rice samples without pre-reduction step with hydrochloric acid and heating.
