The hydrophobic flocculation of jamesonite fines in aqueous suspensions induced by ammonium dibutyl dithiophosphate was investigated using laser particle size analysis, microscope analysis, electrophoretic light scatt...The hydrophobic flocculation of jamesonite fines in aqueous suspensions induced by ammonium dibutyl dithiophosphate was investigated using laser particle size analysis, microscope analysis, electrophoretic light scattering and infrared spectroscopy.Single minerals of 4.607 μm for the 50% volumetric diameters were researched by varying several parameters, including p H,ammonium dibutyl dithiophosphate concentration, stirring strength and kerosene addition. It is found that the maximal floatability of jamesonite fines is induced by ammonium dibutyl dithiophosphate at p H 6, and the floc flotation increases with increasing ammonium dibutyl dithiophosphate concentration despite a simultaneous increase in the negative ζ potential of jamesonite, meaning that hydrophobic interaction between the particles increases much more strongly than electric double layer repulsion from the adsorption of ammonium dibutyl dithiophosphate. It is also found that the floc flotation is closely correlated with the size of flocs,which is strongly influenced by the stirring strength and enhanced by the addition of a small amount of kerosene. The results of FTIR spectra indicate that adsorption of ammonium dibutyl dithiophosphate onto jamesonite is chemical adsorption and the adsorption product is lead dibutyl dithiophosphate.展开更多
Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosp...Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosphates for enzymatically preparing phosphorothioate DNAs and RNAs(PS-DNA and PS-RNA) as potential therapeutics,herein we report a one-pot strategy to synthesize the deoxy-and ribo-nucleoside 5'-(α-P-thio)triphosphates(dNTPαS and NTPαS) without protecting any nucleoside functionalities.This facile synthesis is achieved by treating the nucleosides with a mild phosphitylating reagent,reacting selectively with the 5'-hydroxyl group of each unprotected nucleoside,followed by sulfurization and hydrolysis to afford the crude dNTPαS and NTPαS analogs(mixtures of Sp and Rp diastereomers).We also demonstrated that after just simple precipitation(without HPLC and ion-exchange purification),the quality of the synthesized dNTPαS and NTPαS analogs is excellent for direct DNA polymerization and RNA transcription,respectively.Since Klenow DNA polymerase and T7 RNA polymerase accept the Sp diastereomers of dNTPαS and NTPαS analogs,respectively,while the Rp diastereomers are neither substrates nor inhibitors,the diastereomerically-pure PS-DNAs and PS-RNAs can be conveniently synthesized enzymatically.展开更多
基金Project(51274255)supported by the National Natural Science Foundation of ChinaProject supported by the Foundation of State Key Laboratory of Comprehensive Utilization of Low-Grade Ores(Zijin Mining Group Co.,Ltd.),China
文摘The hydrophobic flocculation of jamesonite fines in aqueous suspensions induced by ammonium dibutyl dithiophosphate was investigated using laser particle size analysis, microscope analysis, electrophoretic light scattering and infrared spectroscopy.Single minerals of 4.607 μm for the 50% volumetric diameters were researched by varying several parameters, including p H,ammonium dibutyl dithiophosphate concentration, stirring strength and kerosene addition. It is found that the maximal floatability of jamesonite fines is induced by ammonium dibutyl dithiophosphate at p H 6, and the floc flotation increases with increasing ammonium dibutyl dithiophosphate concentration despite a simultaneous increase in the negative ζ potential of jamesonite, meaning that hydrophobic interaction between the particles increases much more strongly than electric double layer repulsion from the adsorption of ammonium dibutyl dithiophosphate. It is also found that the floc flotation is closely correlated with the size of flocs,which is strongly influenced by the stirring strength and enhanced by the addition of a small amount of kerosene. The results of FTIR spectra indicate that adsorption of ammonium dibutyl dithiophosphate onto jamesonite is chemical adsorption and the adsorption product is lead dibutyl dithiophosphate.
基金supported by USA NIH(GM095086)the Georgia Cancer Coalition(GCC) Distinguished Cancer Clinicians and ScientistsUSA National Science Foundation(MCB-0824837)
文摘Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosphates for enzymatically preparing phosphorothioate DNAs and RNAs(PS-DNA and PS-RNA) as potential therapeutics,herein we report a one-pot strategy to synthesize the deoxy-and ribo-nucleoside 5'-(α-P-thio)triphosphates(dNTPαS and NTPαS) without protecting any nucleoside functionalities.This facile synthesis is achieved by treating the nucleosides with a mild phosphitylating reagent,reacting selectively with the 5'-hydroxyl group of each unprotected nucleoside,followed by sulfurization and hydrolysis to afford the crude dNTPαS and NTPαS analogs(mixtures of Sp and Rp diastereomers).We also demonstrated that after just simple precipitation(without HPLC and ion-exchange purification),the quality of the synthesized dNTPαS and NTPαS analogs is excellent for direct DNA polymerization and RNA transcription,respectively.Since Klenow DNA polymerase and T7 RNA polymerase accept the Sp diastereomers of dNTPαS and NTPαS analogs,respectively,while the Rp diastereomers are neither substrates nor inhibitors,the diastereomerically-pure PS-DNAs and PS-RNAs can be conveniently synthesized enzymatically.
