【目的】探讨猪链球菌2型超氧化物歧化酶A(SodA)、硫氧还蛋白A(TrxA)和TrxC基因在调控氧化应激和参与致病过程中的生物学功能。【方法】比较猪链球菌2型3个突变菌株ΔSodA、ΔTrxA和ΔTrxC对抗应激能力和毒力的调控作用。通过应激存活试...【目的】探讨猪链球菌2型超氧化物歧化酶A(SodA)、硫氧还蛋白A(TrxA)和TrxC基因在调控氧化应激和参与致病过程中的生物学功能。【方法】比较猪链球菌2型3个突变菌株ΔSodA、ΔTrxA和ΔTrxC对抗应激能力和毒力的调控作用。通过应激存活试验,分别检测SodA、TrxA和TrxC基因对不同氧化应激处理(0.04%过氧化氢(H 2O 2)、10 mol/L百草枯(PQ))的抗氧化应激能力以及不同温度(4、43℃)的抗温度应激能力;将不同基因缺失株与猪肠道上皮细胞(IPEC-J2)、小鼠巨噬细胞(RAW264.7)共培养,探究3个基因对细胞黏附和抗吞噬功能的影响;通过小鼠攻毒试验,测定各组织载菌量和血清抗氧化酶与肝功能指标,探明SodA、TrxA和TrxC基因在抗氧化应激以及致病过程中的作用。【结果】抗应激试验结果显示,在不同氧化应激和不同温度应激条件下,ΔSodA和ΔTrxC菌株存活能力均极显著低于野生菌株(P<0.01),ΔTrxA菌株在43℃高温刺激下存活能力极显著低于野生菌株(P<0.01)。细胞黏附试验结果显示,SodA和TrxA基因缺失导致细菌黏附能力降低55%~65%,极显著低于野生菌株(P<0.01)。细胞抗吞噬试验结果显示,ΔSodA、ΔTrxC和ΔTrxA菌株在吞噬细胞中的存活率极显著或显著低于野生菌株(P<0.01;P<0.05)。动物攻毒试验结果显示,与野生菌株相比,ΔSodA、ΔTrxA和ΔTrxC菌株毒力均极显著下降(P<0.01);ΔSodA、ΔTrxA和ΔTrxC菌株组小鼠死亡率分别为10%、50%和20%,组织载菌量分别为3.6 lg CFU/g~4.4 lg CFU/g、4.2 lg CFU/g~5.1 lg CFU/g和3.1 lg CFU/g~4.1 lg CFU/g;野生菌株组小鼠死亡率为90%,组织载菌量为6.4 lg CFU/g~7.8 lg CFU/g。小鼠感染ΔSodA、ΔTrxC和ΔTrxA菌株后血清中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和总抗氧化能力(T-AOC)极显著高于野生菌株(P<0.01),天门冬氨酸转氨酶(AST)、谷丙转氨酶(ALT)和碱性磷酸酶(ALP)活性极显著低于野生菌株(P<0.01)。【结论】猪链球菌2型SodA和TrxC基因通过中和菌体内超氧根离子和维持蛋白稳态对抗氧化应激引起的损伤,从而介导细菌毒力,而TrxA可能作为一个调控基因参与抗氧化应激反应。展开更多
High soda content in fine alumina trihydrate（ATH） limits its application and increases the soda consumption. The variation of soda content in the fine ATH by seeded precipitation was determined by detection of elect...High soda content in fine alumina trihydrate（ATH） limits its application and increases the soda consumption. The variation of soda content in the fine ATH by seeded precipitation was determined by detection of electric conductivity of solution, soda content in ATH, measurement of particle size distribution and microscopic analysis. The results show that high concentration of sodium aluminate solution, ground circulative seed, low temperature or fast initial precipitation rate increases the soda content in ATH. Soda mainly exists in lattice soda and less soda in desilication product （DSP） exists in the fine ATH precipitated from sodium aluminate solution with concentration of Al2O3 （ρAl2O3） more than 160 g/L and mass ratio of alumina to silica （μSiO2） of 400, and lattice soda decreases with increasing initial precipitation temperature, aging seed, and low precipitation rate and precipitation time. Results also imply that -＋ 4）Na Al（OH ion-pair influences lattice soda content in ATH on the basis of electric conductivity variation.展开更多
The bicarbonate-formate(HCO_(3)−–HCO_(2)−)interconversion provides a promising cycle for a conveniently accessible hydrogen storage system via reversible dehydrogenation and hydrogenation processes.Existing catalytic...The bicarbonate-formate(HCO_(3)−–HCO_(2)−)interconversion provides a promising cycle for a conveniently accessible hydrogen storage system via reversible dehydrogenation and hydrogenation processes.Existing catalytic systems often use organic solvents,tedious optimization as well as manipulation of pH values,solvent,pressure and various additives.Herein,we present an operational,robust,safe and cost-effective catalytic system for hydrogen storage and liberation.We have established a unique catalytic system with two different solid organometallic assemblies(NHC-Ru and NHC-Ir)that facilitate the reversible transformation between sodium formate and bicarbonate in aqueous solutions collaboratively and efficiently.Notably,the NHC-Ru catalyst is privileged for the hydrogenation of sodium bicarbonate,whereas the NHC-Ir component enables the dehydrogenation of sodium formate,all in a single reaction vessel.What sets this system apart is its simplicity.The H_(2)discharging and recharging is simply regulated by heating the mixture with or without H_(2).Remarkably,this process requires no extra additives or supplementary treatments.Moreover,the reversible hydrogen storage system is durable and can be reused for over 30 cycles without a discernible decline in activity and selectivity.The strategic paradigm in this study shows significant practical potential in hydrogen fuel cell applications.展开更多
The comparison of experimental performance was studied for soda cans:longitudinal,transverse,diagonal,and smooth cases to improve the heat transfer rate and thermal performance of the solar air heater,in this study us...The comparison of experimental performance was studied for soda cans:longitudinal,transverse,diagonal,and smooth cases to improve the heat transfer rate and thermal performance of the solar air heater,in this study using a frame which has 1.5 m×0.5 m×0.05 m dimensions,the arrangements were placed on the absorber plate inside the channel,raising the air’s exit temperature as it passed by.The work was carried out for 4 cases in January in Baghdad,Iraq,under specific conditions to compare them to reach the ideal case and the best performance evaluation.When the collector was tilted 350 to the horizontal facing south,The range of mass flow rate was from 0.012 to 0.049 kg/s,and the range of Re was from 2000 to 10,000.The results show that the best Nusselt number in the diagonal AL cans case was increased to 112 at Re=10,000.Then the thermal efficiency increased to 98% accompanied by a moderate decrease in the fraction factor to reach 0.435.Aluminum cans also provide good economic support for solar systems due to their low cost,in addition to their recycling and reducing pollution.展开更多
In recent years,some reports,mainly from Chinese research,show that there has been an increasing trend in the use of ammonia-soda residue(ASR)(or called ammonia-soda white mud) as a soil conditioner in farmlands.Up to...In recent years,some reports,mainly from Chinese research,show that there has been an increasing trend in the use of ammonia-soda residue(ASR)(or called ammonia-soda white mud) as a soil conditioner in farmlands.Up to now,the studies on ASR have focused on its utilization for acid soil amendment in agriculture,but few studies have assessed its environmental risk.ASR contains pollutant elements such as mercury(Hg),cadmium(Cd),copper(Cu) and fluorine(F) and the purpose of this study was to review research on the environmental impacts of ASR application in agriculture.Observations obtained from 23 research reports indicate that the concentrations of Hg,Cd,Cu,F and Cl(0-170,0.01-2.8,4.5-200,2000-24700 and 1 600-188 000 mg kg^-1,respectively) in ASR may exceed the limits(≤0.5,≤0.3 and ≤50 mg kg^-1 for Hg,Cd and Cu,respectively) of Chinese Risk Screening Values for Soil Contamination of Agricultural Land(GB 15618-2018 2018) or the refereed critical value(≤800 and ≤200 mg kg^-1 for F and Cl,respectively) based on Chinese research.The concentrations of the elements Hg,Cd,Cu,F and Cl in the leachate of ASR detected by the extraction tests also exceed the limits(Class IV-V) of the Chinese Standard for Groundwater Quality(GB/T 14848-2017 2017).Based on the above results,it is suggested that ASR without any pretreatment for reducing harmful pollutants should not be used for soil remediation or conditioning of farmlands,to ensure soil health,food safety and environmental quality.展开更多
为了改进水文建模过程中的不确定性处理,采用一种融合全局优化和数据同化(Simultaneous Optimization and Data Assimilation,SODA)的混合框架,对Hy MOD模型进行了不确定性分析,并与经典SCEM-UA方法进行了比较。SODA方法具有如下特点:(1...为了改进水文建模过程中的不确定性处理,采用一种融合全局优化和数据同化(Simultaneous Optimization and Data Assimilation,SODA)的混合框架,对Hy MOD模型进行了不确定性分析,并与经典SCEM-UA方法进行了比较。SODA方法具有如下特点:(1)具备较高的参数搜索效率和寻优能力;(2)明确考虑包括输入、输出、参数以及模型结构在内的重要不确定性来源。SODA方法在渭河流域的实例应用结果表明:与SCEM-UA方法相比,SODA方法不仅显著提高了预报精度,而且推求出了性质更为优良的预报区间。SODA方法的成功应用,有助于模型概念的改进及对水文系统功能的理解。展开更多
The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidati...The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond inβ-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.展开更多
Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusio...Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusion of the resulting leaching residues with caustic soda. The experimental results show that the extraction of zinc is heavily dependent on the contents of iron in the dusts. The higher iron content, the lower extraction of zinc is obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with 5mol·L^-1 NaOH solution for 42h. The remaining zinc left in the leaching residues, which supposed to be present as zinc ferrites, can be further leached when the residues were fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts wit hvarious contents of iron is compared. The production flowsheet for zinc from the dusts using the process proposed is discussed.展开更多
文摘【目的】探讨猪链球菌2型超氧化物歧化酶A(SodA)、硫氧还蛋白A(TrxA)和TrxC基因在调控氧化应激和参与致病过程中的生物学功能。【方法】比较猪链球菌2型3个突变菌株ΔSodA、ΔTrxA和ΔTrxC对抗应激能力和毒力的调控作用。通过应激存活试验,分别检测SodA、TrxA和TrxC基因对不同氧化应激处理(0.04%过氧化氢(H 2O 2)、10 mol/L百草枯(PQ))的抗氧化应激能力以及不同温度(4、43℃)的抗温度应激能力;将不同基因缺失株与猪肠道上皮细胞(IPEC-J2)、小鼠巨噬细胞(RAW264.7)共培养,探究3个基因对细胞黏附和抗吞噬功能的影响;通过小鼠攻毒试验,测定各组织载菌量和血清抗氧化酶与肝功能指标,探明SodA、TrxA和TrxC基因在抗氧化应激以及致病过程中的作用。【结果】抗应激试验结果显示,在不同氧化应激和不同温度应激条件下,ΔSodA和ΔTrxC菌株存活能力均极显著低于野生菌株(P<0.01),ΔTrxA菌株在43℃高温刺激下存活能力极显著低于野生菌株(P<0.01)。细胞黏附试验结果显示,SodA和TrxA基因缺失导致细菌黏附能力降低55%~65%,极显著低于野生菌株(P<0.01)。细胞抗吞噬试验结果显示,ΔSodA、ΔTrxC和ΔTrxA菌株在吞噬细胞中的存活率极显著或显著低于野生菌株(P<0.01;P<0.05)。动物攻毒试验结果显示,与野生菌株相比,ΔSodA、ΔTrxA和ΔTrxC菌株毒力均极显著下降(P<0.01);ΔSodA、ΔTrxA和ΔTrxC菌株组小鼠死亡率分别为10%、50%和20%,组织载菌量分别为3.6 lg CFU/g~4.4 lg CFU/g、4.2 lg CFU/g~5.1 lg CFU/g和3.1 lg CFU/g~4.1 lg CFU/g;野生菌株组小鼠死亡率为90%,组织载菌量为6.4 lg CFU/g~7.8 lg CFU/g。小鼠感染ΔSodA、ΔTrxC和ΔTrxA菌株后血清中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和总抗氧化能力(T-AOC)极显著高于野生菌株(P<0.01),天门冬氨酸转氨酶(AST)、谷丙转氨酶(ALT)和碱性磷酸酶(ALP)活性极显著低于野生菌株(P<0.01)。【结论】猪链球菌2型SodA和TrxC基因通过中和菌体内超氧根离子和维持蛋白稳态对抗氧化应激引起的损伤,从而介导细菌毒力,而TrxA可能作为一个调控基因参与抗氧化应激反应。
基金Project(51274242)supported by the National Natural Science Foundation of China
文摘High soda content in fine alumina trihydrate（ATH） limits its application and increases the soda consumption. The variation of soda content in the fine ATH by seeded precipitation was determined by detection of electric conductivity of solution, soda content in ATH, measurement of particle size distribution and microscopic analysis. The results show that high concentration of sodium aluminate solution, ground circulative seed, low temperature or fast initial precipitation rate increases the soda content in ATH. Soda mainly exists in lattice soda and less soda in desilication product （DSP） exists in the fine ATH precipitated from sodium aluminate solution with concentration of Al2O3 （ρAl2O3） more than 160 g/L and mass ratio of alumina to silica （μSiO2） of 400, and lattice soda decreases with increasing initial precipitation temperature, aging seed, and low precipitation rate and precipitation time. Results also imply that -＋ 4）Na Al（OH ion-pair influences lattice soda content in ATH on the basis of electric conductivity variation.
基金Financial support from the National Natural Science Foundation of China(No.22271060)。
文摘The bicarbonate-formate(HCO_(3)−–HCO_(2)−)interconversion provides a promising cycle for a conveniently accessible hydrogen storage system via reversible dehydrogenation and hydrogenation processes.Existing catalytic systems often use organic solvents,tedious optimization as well as manipulation of pH values,solvent,pressure and various additives.Herein,we present an operational,robust,safe and cost-effective catalytic system for hydrogen storage and liberation.We have established a unique catalytic system with two different solid organometallic assemblies(NHC-Ru and NHC-Ir)that facilitate the reversible transformation between sodium formate and bicarbonate in aqueous solutions collaboratively and efficiently.Notably,the NHC-Ru catalyst is privileged for the hydrogenation of sodium bicarbonate,whereas the NHC-Ir component enables the dehydrogenation of sodium formate,all in a single reaction vessel.What sets this system apart is its simplicity.The H_(2)discharging and recharging is simply regulated by heating the mixture with or without H_(2).Remarkably,this process requires no extra additives or supplementary treatments.Moreover,the reversible hydrogen storage system is durable and can be reused for over 30 cycles without a discernible decline in activity and selectivity.The strategic paradigm in this study shows significant practical potential in hydrogen fuel cell applications.
文摘The comparison of experimental performance was studied for soda cans:longitudinal,transverse,diagonal,and smooth cases to improve the heat transfer rate and thermal performance of the solar air heater,in this study using a frame which has 1.5 m×0.5 m×0.05 m dimensions,the arrangements were placed on the absorber plate inside the channel,raising the air’s exit temperature as it passed by.The work was carried out for 4 cases in January in Baghdad,Iraq,under specific conditions to compare them to reach the ideal case and the best performance evaluation.When the collector was tilted 350 to the horizontal facing south,The range of mass flow rate was from 0.012 to 0.049 kg/s,and the range of Re was from 2000 to 10,000.The results show that the best Nusselt number in the diagonal AL cans case was increased to 112 at Re=10,000.Then the thermal efficiency increased to 98% accompanied by a moderate decrease in the fraction factor to reach 0.435.Aluminum cans also provide good economic support for solar systems due to their low cost,in addition to their recycling and reducing pollution.
基金supported by the Special Program for Fertilizer Registration of Ministry of Agriculture and Rural Affairs of China(2130112)
文摘In recent years,some reports,mainly from Chinese research,show that there has been an increasing trend in the use of ammonia-soda residue(ASR)(or called ammonia-soda white mud) as a soil conditioner in farmlands.Up to now,the studies on ASR have focused on its utilization for acid soil amendment in agriculture,but few studies have assessed its environmental risk.ASR contains pollutant elements such as mercury(Hg),cadmium(Cd),copper(Cu) and fluorine(F) and the purpose of this study was to review research on the environmental impacts of ASR application in agriculture.Observations obtained from 23 research reports indicate that the concentrations of Hg,Cd,Cu,F and Cl(0-170,0.01-2.8,4.5-200,2000-24700 and 1 600-188 000 mg kg^-1,respectively) in ASR may exceed the limits(≤0.5,≤0.3 and ≤50 mg kg^-1 for Hg,Cd and Cu,respectively) of Chinese Risk Screening Values for Soil Contamination of Agricultural Land(GB 15618-2018 2018) or the refereed critical value(≤800 and ≤200 mg kg^-1 for F and Cl,respectively) based on Chinese research.The concentrations of the elements Hg,Cd,Cu,F and Cl in the leachate of ASR detected by the extraction tests also exceed the limits(Class IV-V) of the Chinese Standard for Groundwater Quality(GB/T 14848-2017 2017).Based on the above results,it is suggested that ASR without any pretreatment for reducing harmful pollutants should not be used for soil remediation or conditioning of farmlands,to ensure soil health,food safety and environmental quality.
文摘为了改进水文建模过程中的不确定性处理,采用一种融合全局优化和数据同化(Simultaneous Optimization and Data Assimilation,SODA)的混合框架,对Hy MOD模型进行了不确定性分析,并与经典SCEM-UA方法进行了比较。SODA方法具有如下特点:(1)具备较高的参数搜索效率和寻优能力;(2)明确考虑包括输入、输出、参数以及模型结构在内的重要不确定性来源。SODA方法在渭河流域的实例应用结果表明:与SCEM-UA方法相比,SODA方法不仅显著提高了预报精度,而且推求出了性质更为优良的预报区间。SODA方法的成功应用,有助于模型概念的改进及对水文系统功能的理解。
基金Supported by the National Natural Science Foundation of China（20876064） the Natural Science Foundation of Guangdong Province（9151064101000082） the Guangdong Provincial International Cooperation Fund（2008B05010006）
文摘The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond inβ-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.
文摘Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusion of the resulting leaching residues with caustic soda. The experimental results show that the extraction of zinc is heavily dependent on the contents of iron in the dusts. The higher iron content, the lower extraction of zinc is obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with 5mol·L^-1 NaOH solution for 42h. The remaining zinc left in the leaching residues, which supposed to be present as zinc ferrites, can be further leached when the residues were fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts wit hvarious contents of iron is compared. The production flowsheet for zinc from the dusts using the process proposed is discussed.
