Cationic Gemini surfactants, alkanediyl-α ,ω- bis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid i...Cationic Gemini surfactants, alkanediyl-α ,ω- bis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid in the presence of strong sulfuric acid. Dodecylbromide was then reacted with N,N- tetramethyl ethane diamine(or N,N- tetramethyl hexana diamine) to prepare the title- compounds. Micellization of these Gemini surfactants was investigated using conductivity measurement. The results showed that the critical micelle concentration(cmc) of the Gemini surfactants has a much lower value compared with that of the corresponding " monomer" . For a series of the Geminis with the same length(s) in the spacer chain, the cmc decreased with increasing the carbon number (m) in the alkyl chain. The aggregation number(N) of the micelle also drastically decreased with m. For the same value of m, the cmc varied slightly with s, which indicated that the electrostatic interaction between the ionic- groups of the " monomer" has been naturally changed duo to a link between the two ionic- groups of the " monomer" through a spacer. However, N was strongly decreased with s,which may be a reason of steric inhibition coming from the ionic- groups due to a link of spacer. With increasing temperature, micellization of the Gemini surfactants was slightly enhanced.展开更多
Addressing micronutrient deficiencies in agricultural soils to meet the growing demands of crops is a matter of great concern worldwide.The use of biosurfactant,a multifunctional microbial metabolite,to enhance nutrie...Addressing micronutrient deficiencies in agricultural soils to meet the growing demands of crops is a matter of great concern worldwide.The use of biosurfactant,a multifunctional microbial metabolite,to enhance nutrient availability may be a sustainable way of enhancing agricultural productivity.Biosurfactants are generally less toxic than synthetic surfactants.The application of biosurfactants in agricultural soils is anticipated to improve nutrient status,increase wettability,and achieve a more even dissemination of complex nutrients.Numerous studies have evaluated the influence of biosurfactants on bioremediation,antimicrobial activity,and soil flushing efficiency.This manuscript reviews the possibility of employing biosurfactants to mobilize and solubilize soil nutrients and make them available to plants through the formation of metal-biosurfactant complexes.Although significant progress regarding an explanation of the mechanisms behind many biosurfactant-induced effects has been made,there are still many aspects of this area that are not sufficiently elucidated,such as differences in specificity for nutrients(e.g.,Cu,Fe,Mn,and Zn)and toxins(e.g.,Cd and Pb).Biosurfactants from various isolates have been considered for their potential role in plant growth promotion and other applications related to improving the effectiveness of agricultural soils.展开更多
β-cyclodextrin (β-CD) induced aggregation and micelle formation of cetyltrimethylam-mnium broAnde (CTMAB) in aqueous solution is demonstrated by the dual fluorescence of p-N, N-dAnethyladrinobenzoic acid (DMABOA) ty...β-cyclodextrin (β-CD) induced aggregation and micelle formation of cetyltrimethylam-mnium broAnde (CTMAB) in aqueous solution is demonstrated by the dual fluorescence of p-N, N-dAnethyladrinobenzoic acid (DMABOA) typical of the twisted intramolecular charge transfer (TICT). The locally excited (LE) state of DMABOA is proved to have the characteristic of intramolecular charge transfer (ICT) with a polarity higher than that of ground state but lower than that of TICT state. The peak positions of the two fluorescence bands and theiI intensity ratio are employed to probe the interaction of β-CD with CTMAB. It is conc1uded that β-CD induces CTMAB aggregation as well as Ancelle formation and may change Ancelle structure. The results also indicate that TICT in aqueous solution may be affected by the anisotropy or viscosity of the medium,increasing viscosity disadvantaging the TICT process.展开更多
文摘Cationic Gemini surfactants, alkanediyl-α ,ω- bis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid in the presence of strong sulfuric acid. Dodecylbromide was then reacted with N,N- tetramethyl ethane diamine(or N,N- tetramethyl hexana diamine) to prepare the title- compounds. Micellization of these Gemini surfactants was investigated using conductivity measurement. The results showed that the critical micelle concentration(cmc) of the Gemini surfactants has a much lower value compared with that of the corresponding " monomer" . For a series of the Geminis with the same length(s) in the spacer chain, the cmc decreased with increasing the carbon number (m) in the alkyl chain. The aggregation number(N) of the micelle also drastically decreased with m. For the same value of m, the cmc varied slightly with s, which indicated that the electrostatic interaction between the ionic- groups of the " monomer" has been naturally changed duo to a link between the two ionic- groups of the " monomer" through a spacer. However, N was strongly decreased with s,which may be a reason of steric inhibition coming from the ionic- groups due to a link of spacer. With increasing temperature, micellization of the Gemini surfactants was slightly enhanced.
基金the Ministry of Human Resource and Development (MHRD), India, for granting a fellowship (No. RGNF2012-13DGEN-UTT-56466)
文摘Addressing micronutrient deficiencies in agricultural soils to meet the growing demands of crops is a matter of great concern worldwide.The use of biosurfactant,a multifunctional microbial metabolite,to enhance nutrient availability may be a sustainable way of enhancing agricultural productivity.Biosurfactants are generally less toxic than synthetic surfactants.The application of biosurfactants in agricultural soils is anticipated to improve nutrient status,increase wettability,and achieve a more even dissemination of complex nutrients.Numerous studies have evaluated the influence of biosurfactants on bioremediation,antimicrobial activity,and soil flushing efficiency.This manuscript reviews the possibility of employing biosurfactants to mobilize and solubilize soil nutrients and make them available to plants through the formation of metal-biosurfactant complexes.Although significant progress regarding an explanation of the mechanisms behind many biosurfactant-induced effects has been made,there are still many aspects of this area that are not sufficiently elucidated,such as differences in specificity for nutrients(e.g.,Cu,Fe,Mn,and Zn)and toxins(e.g.,Cd and Pb).Biosurfactants from various isolates have been considered for their potential role in plant growth promotion and other applications related to improving the effectiveness of agricultural soils.
文摘β-cyclodextrin (β-CD) induced aggregation and micelle formation of cetyltrimethylam-mnium broAnde (CTMAB) in aqueous solution is demonstrated by the dual fluorescence of p-N, N-dAnethyladrinobenzoic acid (DMABOA) typical of the twisted intramolecular charge transfer (TICT). The locally excited (LE) state of DMABOA is proved to have the characteristic of intramolecular charge transfer (ICT) with a polarity higher than that of ground state but lower than that of TICT state. The peak positions of the two fluorescence bands and theiI intensity ratio are employed to probe the interaction of β-CD with CTMAB. It is conc1uded that β-CD induces CTMAB aggregation as well as Ancelle formation and may change Ancelle structure. The results also indicate that TICT in aqueous solution may be affected by the anisotropy or viscosity of the medium,increasing viscosity disadvantaging the TICT process.
