A pot experiment was carried out to study the effect of trace elements on the biuret toxicity of maize, with the aim to provide theoretical basis for improving the urea-based compound fertilizer production and reducin...A pot experiment was carried out to study the effect of trace elements on the biuret toxicity of maize, with the aim to provide theoretical basis for improving the urea-based compound fertilizer production and reducing the biuret toxicity. The results showed that the compound fertilizer with 2% and 4% biuret caused obvious toxicity on the maize. The plant became short, and the biomass decreased, and the toxicity phenomenon of maize would become more obvious when the biuret leve increased. Application of 5% EDTA-Zn and 0.4% B could reduce the toxicity of bi uret in fertilizers. The toxicity would be eliminated completely when the level of biuret was 2% in compound fertilizers, while the toxicity effects of 4% biuret was just alleviated to a certain extent. In addition, application of 2% amino acids with ureabased compound fertilizer could promote root absorption of biuret, and increase the biuret toxicity. In conclusion, the urea compound fertilizers with high biuret concentrations should be applied with appropriate trace elements to reduce the biuret dam age. It was suggested that the biuret content in the complex fertilizers for maize should be controlled below 2%, and appropriate trace elements should be applied at the same time.展开更多
A new and senseitive Co (II)-biuret method for determination of protein has for the first time been established. In visible wavelength region, the Co (II) -protein complexes had anabsorption peak at 360 nm. -Under the...A new and senseitive Co (II)-biuret method for determination of protein has for the first time been established. In visible wavelength region, the Co (II) -protein complexes had anabsorption peak at 360 nm. -Under the present conditions. the assay had a linear range of 0-120 μg/ml of protein with a detection limit of about 2 μg/ml, and similar calibration curves were obtained for BSA. and BγG. Compared with Cu (II) -biuret method, the present Co (II) -biuret method was more simple, sensitive, and tolerant of interferences from non-protein molecules.展开更多
The reaction of unsymmetrical phenylmethyltin dihydride （PhMeSnH2）, phenylethyltin dihydride （PhEtSnH2）, phenylbutyltin dihydride （PhBuSnH2） and butylmethyltin dihydride （BuMeSnH2） with biuret （HAL） proceeds...The reaction of unsymmetrical phenylmethyltin dihydride （PhMeSnH2）, phenylethyltin dihydride （PhEtSnH2）, phenylbutyltin dihydride （PhBuSnH2） and butylmethyltin dihydride （BuMeSnH2） with biuret （HAL） proceeds via SnH/NH dehydrocoupling to afford the corresponding tetra-coordinate cyclic products. The reactions in the molar ratios of 1 ： 1, 2 ： 1 and 1 ： 2 have been studied. The yellow derivatives so isolated were soluble in polar solvents and insoluble in nonpolar solvents. It was found that 1 ： 1 reaction went to completion while 2 ： 1 and 1 ： 2 did not go to completion. The derivatives had been characterized by elemental analysis and spectroscopic techniques viz. IR, ^1H NMR, ^13C NMR, ^119Sn NMR. DSC and TGA of the reaction products have also been studied. All the derivatives were thermally stable upto （1904- 10）℃ and degradation occurred after that.展开更多
Polyureas （PU） are well known as a class of high impact engineering materials, and widely used also in emerging advanced applications. As a general observation, most of them are only soluble in a very limited number...Polyureas （PU） are well known as a class of high impact engineering materials, and widely used also in emerging advanced applications. As a general observation, most of them are only soluble in a very limited number of highly protonic solvents, which makes their chemical structure analysis a great challenge. Besides the presence of abundant hydrogen bonding, the poor solubility of PU in common organic solvents is often ascribed to the formation of biuret crosslinking in their molecular chains. To clarify the presence of biuret groups in PU has been of great interest. To this end, two samples, based on hexamethylene diisocyanate （HDI） and toluene diisocyanate （TDI） respectively, were synthesized by precipitation polymerization of each of these diisocyanates in water-acetone at 30℃. Their chemical structures were analyzed by high resolution magic angle spinning （HR-MAS） NMR, and through comparison of their NMR spectra with those of specially prepared biuret-containing polyurea oligomers, it was concluded that biuret group was absent in all the PU prepared at 30 ℃. In addition, this NMR analysis was also applied to a PU obtained by copolymerization of TDI with ethylene diamine （EDA） and water at 65 ℃ in EDA aqueous solution. It was confirmed that biuret unit was also absent in this PU and that EDA was more active than water towards TDI. The presence of EDA was crucial to the formation of uniform PU microspheres. This study provides therefore a reliable method for the analysis of PU chemical structure.展开更多
Fourteen new 1-acyl-5-aryl biurets were synthesized by the reaction of aryl ureas with acylisocynantes. The latter was obtained from acyl. chloride and lead cyanate in dichloromethane, using pyridine as catalyst. The ...Fourteen new 1-acyl-5-aryl biurets were synthesized by the reaction of aryl ureas with acylisocynantes. The latter was obtained from acyl. chloride and lead cyanate in dichloromethane, using pyridine as catalyst. The structures of compounds 3a-n were confirmed by IR, H-1 NMR and MS spectra.展开更多
基金Supported by the National Science&Technology Pillar Program during the Twelfth Fiveyear Plan Period(2011BAD11B02)the Special Fund for the Independent Innovation in Shandong Province(2012CX90202)~~
文摘A pot experiment was carried out to study the effect of trace elements on the biuret toxicity of maize, with the aim to provide theoretical basis for improving the urea-based compound fertilizer production and reducing the biuret toxicity. The results showed that the compound fertilizer with 2% and 4% biuret caused obvious toxicity on the maize. The plant became short, and the biomass decreased, and the toxicity phenomenon of maize would become more obvious when the biuret leve increased. Application of 5% EDTA-Zn and 0.4% B could reduce the toxicity of bi uret in fertilizers. The toxicity would be eliminated completely when the level of biuret was 2% in compound fertilizers, while the toxicity effects of 4% biuret was just alleviated to a certain extent. In addition, application of 2% amino acids with ureabased compound fertilizer could promote root absorption of biuret, and increase the biuret toxicity. In conclusion, the urea compound fertilizers with high biuret concentrations should be applied with appropriate trace elements to reduce the biuret dam age. It was suggested that the biuret content in the complex fertilizers for maize should be controlled below 2%, and appropriate trace elements should be applied at the same time.
文摘A new and senseitive Co (II)-biuret method for determination of protein has for the first time been established. In visible wavelength region, the Co (II) -protein complexes had anabsorption peak at 360 nm. -Under the present conditions. the assay had a linear range of 0-120 μg/ml of protein with a detection limit of about 2 μg/ml, and similar calibration curves were obtained for BSA. and BγG. Compared with Cu (II) -biuret method, the present Co (II) -biuret method was more simple, sensitive, and tolerant of interferences from non-protein molecules.
文摘The reaction of unsymmetrical phenylmethyltin dihydride （PhMeSnH2）, phenylethyltin dihydride （PhEtSnH2）, phenylbutyltin dihydride （PhBuSnH2） and butylmethyltin dihydride （BuMeSnH2） with biuret （HAL） proceeds via SnH/NH dehydrocoupling to afford the corresponding tetra-coordinate cyclic products. The reactions in the molar ratios of 1 ： 1, 2 ： 1 and 1 ： 2 have been studied. The yellow derivatives so isolated were soluble in polar solvents and insoluble in nonpolar solvents. It was found that 1 ： 1 reaction went to completion while 2 ： 1 and 1 ： 2 did not go to completion. The derivatives had been characterized by elemental analysis and spectroscopic techniques viz. IR, ^1H NMR, ^13C NMR, ^119Sn NMR. DSC and TGA of the reaction products have also been studied. All the derivatives were thermally stable upto （1904- 10）℃ and degradation occurred after that.
基金financially supported by the National Natural Science Foundation of China(Nos.21274054,21304038 and51473066)Research Foundation of University of Jinan(No.XKY1604)Science&Technology Development Plan of Shandong Province(No.2017GGX202009),China
文摘Polyureas （PU） are well known as a class of high impact engineering materials, and widely used also in emerging advanced applications. As a general observation, most of them are only soluble in a very limited number of highly protonic solvents, which makes their chemical structure analysis a great challenge. Besides the presence of abundant hydrogen bonding, the poor solubility of PU in common organic solvents is often ascribed to the formation of biuret crosslinking in their molecular chains. To clarify the presence of biuret groups in PU has been of great interest. To this end, two samples, based on hexamethylene diisocyanate （HDI） and toluene diisocyanate （TDI） respectively, were synthesized by precipitation polymerization of each of these diisocyanates in water-acetone at 30℃. Their chemical structures were analyzed by high resolution magic angle spinning （HR-MAS） NMR, and through comparison of their NMR spectra with those of specially prepared biuret-containing polyurea oligomers, it was concluded that biuret group was absent in all the PU prepared at 30 ℃. In addition, this NMR analysis was also applied to a PU obtained by copolymerization of TDI with ethylene diamine （EDA） and water at 65 ℃ in EDA aqueous solution. It was confirmed that biuret unit was also absent in this PU and that EDA was more active than water towards TDI. The presence of EDA was crucial to the formation of uniform PU microspheres. This study provides therefore a reliable method for the analysis of PU chemical structure.
文摘Fourteen new 1-acyl-5-aryl biurets were synthesized by the reaction of aryl ureas with acylisocynantes. The latter was obtained from acyl. chloride and lead cyanate in dichloromethane, using pyridine as catalyst. The structures of compounds 3a-n were confirmed by IR, H-1 NMR and MS spectra.
