In this work,a comparative study of three frequently employed modification techniques to g-C_(3)N_(4)(CN)nanosheets for the photocatalytic degradation of metribuzin(MET)under visible-light irradiation has been carried...In this work,a comparative study of three frequently employed modification techniques to g-C_(3)N_(4)(CN)nanosheets for the photocatalytic degradation of metribuzin(MET)under visible-light irradiation has been carried out in detail.The modification methods were coupling TiO_(2)nanoparticles(TO)as electron acceptors,nano-sized Fe_(2)O_(3)(FO)to construct a Z-scheme nanocomposite,and phosphate(HP)modification to promote O_(2)adsorption.The steady-state and transient-state surface photovoltage spectra and transient photoluminescence(PL)spectra confirmed that all the three modification techniques enhanced the charge separation with prolonged lifetimes and presented degradation activities in the order of TO/CN[FO/CN[HP/CN.The TO/CN nanocomposite showed the highest photocatalytic activity for MET degradation,with a sixfold higher rate than bulk CN.Liquid chromatography–tandem mass spectrometry and radical trapping experiments indicated that the increased activity was related to the synergetic effect of two radicals(·O^(2-) and ·OH)involved in the photocatalytic degradation pathway,which was different from the·OH radical-dominated pathway of bulk CN.This work reveals the importance of charge separation and the influence of the radical pathway and provides guidance for the design of high-efficiency photocatalysts.展开更多
Field studies were conducted to determine the dissipation and movement of metribuzin and metolachlor applied at conventional rates to a Verndale sandy loam (Udic Argiboroll) in north-central Minnesota under irrigated ...Field studies were conducted to determine the dissipation and movement of metribuzin and metolachlor applied at conventional rates to a Verndale sandy loam (Udic Argiboroll) in north-central Minnesota under irrigated potato production in two years. The rapid dissipation of both metribuzin and metolachlor was found during the initial 10 to 15 days in both years) and more than 70% of the applied herbicide dissipated during this period. From 10 to 15 days after application up to the end of growing season in both years, the levels of both herbicides decreased slowly with time. Metolachlor dissipated at a slower rate than metribuzin in surface soil and could carry over to the next cropping season. Metribuzin and metolachlor were detected in only 6 and 1 of 154 soil samples in the first year and in 3 and 4 of 225 soil samples in the second year, taken from 15 to 75cm, respectively. Fifty to 67% of water samples from suction samplers at 135-cm depth contained detectable levels (>0.4μg L-1 ) of herbicides in both years. Under laboratory conditions degradation of both herbicides was much slower than their dissipation in field. Therefore, it appeared that leaching might be an important dissipation pathway for metribuzin and metolachlor under irrigated potato production.展开更多
Objective: To evaluate the acute toxicity effect of metribuzin at low dose on liver of mother rabbits and its fetus.Methods: Pregnant female rabbitsOryctolagus cuniculus were divided into three groups (n=5). The first...Objective: To evaluate the acute toxicity effect of metribuzin at low dose on liver of mother rabbits and its fetus.Methods: Pregnant female rabbitsOryctolagus cuniculus were divided into three groups (n=5). The first group of non-treated pregnancy rabbits served as control;the second group of pregnancy rabbits were treated with 1/100 LD50 of metribuzin and the third group of pregnancy rabbits were treated with 1/50 LD50 of metribuzin. Metribuzin was added in their drinking water for 60 d before and during pregnancy. Levels of liver malondialdehyde, liver glutathione S transferase, serum glutamic oxaloacetic transaminase and serum glutamic-pyruvic transaminase were determined. Liver reduced glutathione level was also determined by a colorimetric method. And hepatic homogenate was analyzed by HPLC analysis to determine the existence of traces of metribuzin.Results: Results revealed a significant increase in level of liver malondialdehyde, glutathione S transferase, serum glutamic oxalacetic transaminase and serum glutamic-pyruvic transaminase activities in mother and fetuses rabbits of both metribuzin treatment groups as compared to the control group. However the level of reduced glutathione was decreased in mother and fetuses rabbits of both groups treated with metribuzin compared to control group. Also, the results obtained by HPLC technique showed the presence of trace metribuzin in liver cells of mothers and fetuses rabbits of the both metribuzin treated groups.Conclusions: In conclusion, this study shows that exposure to metribuzin at low concentrations causes a acute toxicity in liver of mother rabbits and its fetus, also the trace of the metribuzin detected in the liver is the origin of possible malformation of the fetuses or abortion of the rabbits.展开更多
The current emphasis on reducing herbicide applications has led to an increase in alternative weed control measures. Field experiment was conducted in the spring of 2014 to examine the effect of hilling-time and reduc...The current emphasis on reducing herbicide applications has led to an increase in alternative weed control measures. Field experiment was conducted in the spring of 2014 to examine the effect of hilling-time and reduced-rates of metribuzin and their combinations on weed infestation in potato, and to determine their impact on potato yield. Metribuzin at 0.35, 0.56, or 0.75 kg ai/ha with or without hilling 6, 7, and 8 weeks after planting (WAP) were used. Weed count, weed control visual rating, weed dry weight, potato plant height, number of shoots and leaves, root dry weight, and potato yield were collected. Results showed that metribuzin, at all tested rates, with or without hilling significantly reduced weed infestation after 50, 70, and 110 days after planting (DAP) compared to the check. Best results were obtained by a combination of metribuzin at all tested rates with hilling 6, 7, and 8 WAP. The results suggest that long season weed control and high marketable yield could be achieved by metribuzin at 0.35 kg ai/ha (53% reduction in metribuzin) supplemented with hilling (6 WAP). None of the treatments was toxic to potato plants compared to the hand-weeded plots.展开更多
The efficiency and selectivity of chlorimuron-ethyl （107 g/kg） associated with metribuzin （643 g/kg）, against weeds which causes big damages to sugar cane, have been studied on the sugar cane field of Beregadougou...The efficiency and selectivity of chlorimuron-ethyl （107 g/kg） associated with metribuzin （643 g/kg）, against weeds which causes big damages to sugar cane, have been studied on the sugar cane field of Beregadougou. The experimental design was a Latin rectangle with eight treatments in four replications including an untreated control, manual weeding, a control product （Trifloxysulfuron-sdium 1.85% ＋ Ametryn 73.15%） and five rates of chlorimuron-ethyl associated with metribuzin. Weeds counting and weighing their dry biomass have been done using 0.25 m2 quadrants to determine their biological efficiencies. The soil nitrogen nitrate and assimilable phosphorus contents were evaluated on a spectrophotometer, those of available potassium on a flame photometer. The biological efficiency coefficients of this herbicide, varied from 12.41% to 100%, according to their dry biomass. High rates, phytotoxics, showed the best coefficients. At the sugar cane complete maturation, the higher rates of imposter led to an accumulation of nitrogen nitrate content and lower available phosphorus and potassium contents, compared to the untreated control. The rate of 1.20 kg/ha became the dose to apply against weeds and less toxic to the soil.展开更多
Antioxidants such as vitamin C and NADH can protect against pesticide adverse effects on immune function. The aim of this work was to study the in vitro effects of vitamin C and NADH on the proliferative responses of ...Antioxidants such as vitamin C and NADH can protect against pesticide adverse effects on immune function. The aim of this work was to study the in vitro effects of vitamin C and NADH on the proliferative responses of human lymphocytes exposed to pesticides （Mancozeb fungicide and Metribuzin herbicide） and on Thl and Th2 cytokine secretion. Their possible protective role on intracellular stress oxidative induced by pesticides was also investigated. Peripheral blood lymphocytes were isolated using differential centrifugation on a density gradient of Histopaque. They were cultured with mitogen concanavalin A （Con A）, Mancozeb and Metribuzin （50 μM） in the presence or the absence of vitamin C （50 μM） or NADH （50 μM）. Proliferation （MTT assay）, IL-2, INFγ and IL-4 （Elisa kits）, oxidative markers （intracellular superoxide anion, hydroperoxides, carbonyl proteins, GSH, catalase and SOD） were determined, The results showed that pesticides were immunosuppressive and decreased cytokine secretion with a shift away from to Thl phenotype. These immunomodulatory properties were accompanied by an increase in lymphocyte intracellular oxidative stress. The presence of vitamin C or NADH, in the medium, exhibited protective effects in human lymphocytes by inhibiting pesticide---induced lymphocyte proliferation suppression, inflammatory status and oxidative stress generation. In conclusion, vitamin C and NADH can result in a safe and effective method to reduce pesticide adverse effects and help to restore immune function.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21971057 and U1805255)the Natural Science Foundation of Heilongjiang Province(Nos.YQ2019B006 and LH2020B012)+2 种基金the Postdoctoral Research Foundation of Heilongjiang Province(No.LBH-Q19052)the Outstanding Youth Fund of Heilongjiang University(No.JCL201901)the Basic Scientific Research Expenses of Colleges and Universities in Heilongjiang Province(No.2020-KYYWF-1008).
文摘In this work,a comparative study of three frequently employed modification techniques to g-C_(3)N_(4)(CN)nanosheets for the photocatalytic degradation of metribuzin(MET)under visible-light irradiation has been carried out in detail.The modification methods were coupling TiO_(2)nanoparticles(TO)as electron acceptors,nano-sized Fe_(2)O_(3)(FO)to construct a Z-scheme nanocomposite,and phosphate(HP)modification to promote O_(2)adsorption.The steady-state and transient-state surface photovoltage spectra and transient photoluminescence(PL)spectra confirmed that all the three modification techniques enhanced the charge separation with prolonged lifetimes and presented degradation activities in the order of TO/CN[FO/CN[HP/CN.The TO/CN nanocomposite showed the highest photocatalytic activity for MET degradation,with a sixfold higher rate than bulk CN.Liquid chromatography–tandem mass spectrometry and radical trapping experiments indicated that the increased activity was related to the synergetic effect of two radicals(·O^(2-) and ·OH)involved in the photocatalytic degradation pathway,which was different from the·OH radical-dominated pathway of bulk CN.This work reveals the importance of charge separation and the influence of the radical pathway and provides guidance for the design of high-efficiency photocatalysts.
基金Project supported by the Legislative Commission on Minnesota Resources, USA the Teaching and ResearchAward Program for Outsta
文摘Field studies were conducted to determine the dissipation and movement of metribuzin and metolachlor applied at conventional rates to a Verndale sandy loam (Udic Argiboroll) in north-central Minnesota under irrigated potato production in two years. The rapid dissipation of both metribuzin and metolachlor was found during the initial 10 to 15 days in both years) and more than 70% of the applied herbicide dissipated during this period. From 10 to 15 days after application up to the end of growing season in both years, the levels of both herbicides decreased slowly with time. Metolachlor dissipated at a slower rate than metribuzin in surface soil and could carry over to the next cropping season. Metribuzin and metolachlor were detected in only 6 and 1 of 154 soil samples in the first year and in 3 and 4 of 225 soil samples in the second year, taken from 15 to 75cm, respectively. Fifty to 67% of water samples from suction samplers at 135-cm depth contained detectable levels (>0.4μg L-1 ) of herbicides in both years. Under laboratory conditions degradation of both herbicides was much slower than their dissipation in field. Therefore, it appeared that leaching might be an important dissipation pathway for metribuzin and metolachlor under irrigated potato production.
文摘Objective: To evaluate the acute toxicity effect of metribuzin at low dose on liver of mother rabbits and its fetus.Methods: Pregnant female rabbitsOryctolagus cuniculus were divided into three groups (n=5). The first group of non-treated pregnancy rabbits served as control;the second group of pregnancy rabbits were treated with 1/100 LD50 of metribuzin and the third group of pregnancy rabbits were treated with 1/50 LD50 of metribuzin. Metribuzin was added in their drinking water for 60 d before and during pregnancy. Levels of liver malondialdehyde, liver glutathione S transferase, serum glutamic oxaloacetic transaminase and serum glutamic-pyruvic transaminase were determined. Liver reduced glutathione level was also determined by a colorimetric method. And hepatic homogenate was analyzed by HPLC analysis to determine the existence of traces of metribuzin.Results: Results revealed a significant increase in level of liver malondialdehyde, glutathione S transferase, serum glutamic oxalacetic transaminase and serum glutamic-pyruvic transaminase activities in mother and fetuses rabbits of both metribuzin treatment groups as compared to the control group. However the level of reduced glutathione was decreased in mother and fetuses rabbits of both groups treated with metribuzin compared to control group. Also, the results obtained by HPLC technique showed the presence of trace metribuzin in liver cells of mothers and fetuses rabbits of the both metribuzin treated groups.Conclusions: In conclusion, this study shows that exposure to metribuzin at low concentrations causes a acute toxicity in liver of mother rabbits and its fetus, also the trace of the metribuzin detected in the liver is the origin of possible malformation of the fetuses or abortion of the rabbits.
文摘The current emphasis on reducing herbicide applications has led to an increase in alternative weed control measures. Field experiment was conducted in the spring of 2014 to examine the effect of hilling-time and reduced-rates of metribuzin and their combinations on weed infestation in potato, and to determine their impact on potato yield. Metribuzin at 0.35, 0.56, or 0.75 kg ai/ha with or without hilling 6, 7, and 8 weeks after planting (WAP) were used. Weed count, weed control visual rating, weed dry weight, potato plant height, number of shoots and leaves, root dry weight, and potato yield were collected. Results showed that metribuzin, at all tested rates, with or without hilling significantly reduced weed infestation after 50, 70, and 110 days after planting (DAP) compared to the check. Best results were obtained by a combination of metribuzin at all tested rates with hilling 6, 7, and 8 WAP. The results suggest that long season weed control and high marketable yield could be achieved by metribuzin at 0.35 kg ai/ha (53% reduction in metribuzin) supplemented with hilling (6 WAP). None of the treatments was toxic to potato plants compared to the hand-weeded plots.
文摘The efficiency and selectivity of chlorimuron-ethyl （107 g/kg） associated with metribuzin （643 g/kg）, against weeds which causes big damages to sugar cane, have been studied on the sugar cane field of Beregadougou. The experimental design was a Latin rectangle with eight treatments in four replications including an untreated control, manual weeding, a control product （Trifloxysulfuron-sdium 1.85% ＋ Ametryn 73.15%） and five rates of chlorimuron-ethyl associated with metribuzin. Weeds counting and weighing their dry biomass have been done using 0.25 m2 quadrants to determine their biological efficiencies. The soil nitrogen nitrate and assimilable phosphorus contents were evaluated on a spectrophotometer, those of available potassium on a flame photometer. The biological efficiency coefficients of this herbicide, varied from 12.41% to 100%, according to their dry biomass. High rates, phytotoxics, showed the best coefficients. At the sugar cane complete maturation, the higher rates of imposter led to an accumulation of nitrogen nitrate content and lower available phosphorus and potassium contents, compared to the untreated control. The rate of 1.20 kg/ha became the dose to apply against weeds and less toxic to the soil.
文摘Antioxidants such as vitamin C and NADH can protect against pesticide adverse effects on immune function. The aim of this work was to study the in vitro effects of vitamin C and NADH on the proliferative responses of human lymphocytes exposed to pesticides （Mancozeb fungicide and Metribuzin herbicide） and on Thl and Th2 cytokine secretion. Their possible protective role on intracellular stress oxidative induced by pesticides was also investigated. Peripheral blood lymphocytes were isolated using differential centrifugation on a density gradient of Histopaque. They were cultured with mitogen concanavalin A （Con A）, Mancozeb and Metribuzin （50 μM） in the presence or the absence of vitamin C （50 μM） or NADH （50 μM）. Proliferation （MTT assay）, IL-2, INFγ and IL-4 （Elisa kits）, oxidative markers （intracellular superoxide anion, hydroperoxides, carbonyl proteins, GSH, catalase and SOD） were determined, The results showed that pesticides were immunosuppressive and decreased cytokine secretion with a shift away from to Thl phenotype. These immunomodulatory properties were accompanied by an increase in lymphocyte intracellular oxidative stress. The presence of vitamin C or NADH, in the medium, exhibited protective effects in human lymphocytes by inhibiting pesticide---induced lymphocyte proliferation suppression, inflammatory status and oxidative stress generation. In conclusion, vitamin C and NADH can result in a safe and effective method to reduce pesticide adverse effects and help to restore immune function.
