Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixa...Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.展开更多
Reactive dyes are the main dyes in printing and dyeing of cellulosic fibers.Reactive dyes fixation rate is a vital indicator to measure the degree of the covalent bond between cellulose and reactive dyes.However,the d...Reactive dyes are the main dyes in printing and dyeing of cellulosic fibers.Reactive dyes fixation rate is a vital indicator to measure the degree of the covalent bond between cellulose and reactive dyes.However,the determination of the fixation rate is tedious and time-consumptive.Based on the theory of reactive dyes dyeing and application of modern computer color matching technology,the relationship between K/S value and the fixation rate with the reactive dyes on cotton fabric was studied.The feasibility of K/S value instead of the traditional washing method for the determination of reactive dyes fixation rate was proved.In this study,the K/S value of the fabric has an excellent linear relationship to the reactive dyes fixation rate obtained by the washing method.The reactive dyes fixation rate can be obtained through the K/S correction value.展开更多
Diazotrophs make important contributions to nitrogen(N) inputs in agricultural ecosystems. However, strong evidence of the effects of conservation tillage(CT) on the coexistence and assembly of soil diazotrophic commu...Diazotrophs make important contributions to nitrogen(N) inputs in agricultural ecosystems. However, strong evidence of the effects of conservation tillage(CT) on the coexistence and assembly of soil diazotrophic community and related mechanisms is lacking. Here, a long-term experiment was conducted to study the impacts of CT on the coexistence and assembly patterns of soil diazotrophic community in Lishu County, Jilin Province, North China. Compared to traditional tillage(control, CK), CT significantly reduced both the N fixation rate in top 0–10 cm soil and the alpha diversity of diazotrophic community while increasing the density of diazotrophic and overall bacterial communities. Conservation tillage also reduced the competitive relationships within the diazotrophic community and enhanced network stability. Furthermore, diazotroph assembly was dominated by deterministic processes(relative influence =68.63%) under CK and stochastic processes(relative influence = 58.82%) under CT. Soil depth and total N(TN) were identified as crucial predictors shaping the assembly processes of diazotrophic community under different tillage practices. The relative influence of stochastic processes on diazotrophic community under CT varied more significantly with increasing soil depth. Overall, tillage practice and soil depth had significant influences on the coexistence and assembly processes of soil diazotrophic community. Moreover, long-term CT may impact the selection of N fixation agents and the specific taxa associated with N fixers. Our results indicated that in CT systems, relatively sufficient nutrient availability led to a reduction in interspecies competition, an increase in network stability, and a greater influence of stochastic processes on community assembly. These findings may help us better understand biological N fixation in sustainable agricultural systems.展开更多
The development of pollution-free dyeing technology, including anhydrous dyeing and non-aqueous dyeing technologies, has always been an important way and research hot in energy conservation and emission reduction. Des...The development of pollution-free dyeing technology, including anhydrous dyeing and non-aqueous dyeing technologies, has always been an important way and research hot in energy conservation and emission reduction. Designing new structural dye molecules is the key to water-saving dyeing processes.Herein, three reactive dyes were designed and synthesized, which contained large planar multiconjugated systems and multi-reactive groups. The designed reactive dyes are expected to have high affinity and high fixations in non-aqueous or small bath dyeing processes. The reactive dyes were applied in the decamethylcyclopentasiloxane(DMCS) reverse micelle dyeing for cotton fabric. High exhaustion rate of 99.35%, 98.10% and 98.80%, and fixation rate of 95.15%, 96.34% and 94.40% for three dyes, R1,R2 and R3, could be respectively obtained. The dyes can be fully utilized and had excellent dyeing performance, fastness and levelling properties under the revere micelle dyeing. The cotton fabric is like an oil-water separator in the dyeing process, where the dye micelles rapidly absorb and permeate into the cotton fibers. DMCS circulates around the fabric to transfer mass and energy. After dyeing, the solvent can be separated quickly and reused. The new reactive dyes containing large planar and multi-conjugated systems have potential application in green and sustainable dyeing technology with less wastewater and higher utilization.展开更多
基金The National Natural Science Foundation of China under contract Nos 42076042 and 41721005the Fund of Ministry of Science and Technology of China under contract No.2017FY201403the Fund of China Ocean Mineral Resources R&D Association under contract No.DY135-13-E2-03.
文摘Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.
文摘Reactive dyes are the main dyes in printing and dyeing of cellulosic fibers.Reactive dyes fixation rate is a vital indicator to measure the degree of the covalent bond between cellulose and reactive dyes.However,the determination of the fixation rate is tedious and time-consumptive.Based on the theory of reactive dyes dyeing and application of modern computer color matching technology,the relationship between K/S value and the fixation rate with the reactive dyes on cotton fabric was studied.The feasibility of K/S value instead of the traditional washing method for the determination of reactive dyes fixation rate was proved.In this study,the K/S value of the fabric has an excellent linear relationship to the reactive dyes fixation rate obtained by the washing method.The reactive dyes fixation rate can be obtained through the K/S correction value.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA28020202)the National Natural Science Foundation of China (No. 42277336)+3 种基金the Natural Science Foundation of Jiangsu Province, China (No. BK20221561)the China Agriculture Research System (Nos. CARS-03 and CARS52)the National Key Research and Development Program of China (No. 2022YFD1500401)the Jiangsu Agricultural Science and Technology Innovation Fund of China (No. CX(24)1003)。
文摘Diazotrophs make important contributions to nitrogen(N) inputs in agricultural ecosystems. However, strong evidence of the effects of conservation tillage(CT) on the coexistence and assembly of soil diazotrophic community and related mechanisms is lacking. Here, a long-term experiment was conducted to study the impacts of CT on the coexistence and assembly patterns of soil diazotrophic community in Lishu County, Jilin Province, North China. Compared to traditional tillage(control, CK), CT significantly reduced both the N fixation rate in top 0–10 cm soil and the alpha diversity of diazotrophic community while increasing the density of diazotrophic and overall bacterial communities. Conservation tillage also reduced the competitive relationships within the diazotrophic community and enhanced network stability. Furthermore, diazotroph assembly was dominated by deterministic processes(relative influence =68.63%) under CK and stochastic processes(relative influence = 58.82%) under CT. Soil depth and total N(TN) were identified as crucial predictors shaping the assembly processes of diazotrophic community under different tillage practices. The relative influence of stochastic processes on diazotrophic community under CT varied more significantly with increasing soil depth. Overall, tillage practice and soil depth had significant influences on the coexistence and assembly processes of soil diazotrophic community. Moreover, long-term CT may impact the selection of N fixation agents and the specific taxa associated with N fixers. Our results indicated that in CT systems, relatively sufficient nutrient availability led to a reduction in interspecies competition, an increase in network stability, and a greater influence of stochastic processes on community assembly. These findings may help us better understand biological N fixation in sustainable agricultural systems.
基金supported by Natural Science Foundation of Shanghai (20ZR1400300)Textile Vision Applied Basic Research Project (J202005)National Key Research & Development Program of China (2017YFB0309600)。
文摘The development of pollution-free dyeing technology, including anhydrous dyeing and non-aqueous dyeing technologies, has always been an important way and research hot in energy conservation and emission reduction. Designing new structural dye molecules is the key to water-saving dyeing processes.Herein, three reactive dyes were designed and synthesized, which contained large planar multiconjugated systems and multi-reactive groups. The designed reactive dyes are expected to have high affinity and high fixations in non-aqueous or small bath dyeing processes. The reactive dyes were applied in the decamethylcyclopentasiloxane(DMCS) reverse micelle dyeing for cotton fabric. High exhaustion rate of 99.35%, 98.10% and 98.80%, and fixation rate of 95.15%, 96.34% and 94.40% for three dyes, R1,R2 and R3, could be respectively obtained. The dyes can be fully utilized and had excellent dyeing performance, fastness and levelling properties under the revere micelle dyeing. The cotton fabric is like an oil-water separator in the dyeing process, where the dye micelles rapidly absorb and permeate into the cotton fibers. DMCS circulates around the fabric to transfer mass and energy. After dyeing, the solvent can be separated quickly and reused. The new reactive dyes containing large planar and multi-conjugated systems have potential application in green and sustainable dyeing technology with less wastewater and higher utilization.
