Gas flexible pipes are critical multi-layered equipment for offshore oil and gas development.Under high pressure conditions,small molecular components of natural gas dissolve into the polymer inner liner of the flexib...Gas flexible pipes are critical multi-layered equipment for offshore oil and gas development.Under high pressure conditions,small molecular components of natural gas dissolve into the polymer inner liner of the flexible pipes and further diffuse into the annular space,incurring annular pressure build-up and/or production of acidic environment,which poses serious challenges to the structure and integrity of the flexible pipes.Gas permeation in pipes is a complex phenomenon governed by various factors such as internal pressure and temperature,annular structure,external temperature.In a long-distance gas flexible pipe,moreover,gas permeation exhibits non-uniform features,and the gas permeated into the annular space flows along the metal gap.To assess the complex gas transport behavior in long-distance gas flexible pipes,a mathematical model is established in this paper considering the multiphase flow phenomena inside the flexible pipes,the diffusion of gas in the inner liner,and the gas seepage in the annular space under varying permeable properties of the annulus.In addition,the effect of a variable temperature is accounted.A numerical calculation method is accordingly constructed to solve the coupling mathematical equations.The annular permeability was shown to significantly influence the distribution of annular pressure.As permeability increases,the annular pressure tends to become more uniform,and the annular pressure at the wellhead rises more rapidly.After annular pressure relief followed by shut-in,the pressure increase follows a convex function.By simulating the pressure recovery pattern after pressure relief and comparing it with test results,we deduce that the annular permeability lies between 123 and 512 m D.The results help shed light upon assessing the annular pressure in long distance gas flexible pipes and thus ensure the security of gas transport in the emerging development of offshore resources.展开更多
Based on Bingham rheological model,a three-dimensional numerical simulation model for long-distance pipeline transportation is established by computational fluid dynamics(CFD)to study the pipeline transportationproper...Based on Bingham rheological model,a three-dimensional numerical simulation model for long-distance pipeline transportation is established by computational fluid dynamics(CFD)to study the pipeline transportationproperties of high sliming paste from a copper mine in China.Based on the rheological properties test,the pressure and velocity of pipeline and elbow are simulated by CFD under different mass concentrations and different stowing capacities.The results show that the pipeline resistance of whole-tailings paste with high sliming while without pumping agent is much higher than that with high sliming and pumping agent at the same mass concentration,and the pipeline resistance of whole-tailings paste with high sliming while without pumping agent is much higher than that with low sliming while without pumping agent.It is very important to add pumping agent to whole-tailings paste with high sliming,and the resistance changes with mass concentration and stowing capacity at the same cement-to-sand ratio of1:5and tailings-to-waste ratio of6:1.However,the change is just limited,that is to say,the paste transportation system is of good stability.Furthermore,at the elbow,the maximum pressure and velocity transfer to the outside of the pipe from the inside.However,lubricating layer is formed at the pipe wall because of high content of fine particles in whole-tailings paste,which will protect the elbow from abrasion.CFD provides an intuitive and accurate basis for pipeline transportation study,and would have a wider application space in the study of paste rheological properties and resistance reduction methods.展开更多
Cytokinins(CKs),primarily trans-zeatin(tZ)and isopentenyladenine(iP)types,play critical roles in plant growth,development,and various stress responses.Long-distance transport of tZ-type CKs meidated by Arabidopsis ATP...Cytokinins(CKs),primarily trans-zeatin(tZ)and isopentenyladenine(iP)types,play critical roles in plant growth,development,and various stress responses.Long-distance transport of tZ-type CKs meidated by Arabidopsis ATP-binding cassette transporter subfamily G14(AtABCG14)has been well studied;however,less is known about the biochemical properties of AtABCG14 and its transporter activity toward iP-type CKs.Here we reveal the biochemical properties of AtABCG14 and provide evidence that it is also required for long-distance transport of iP-type CKs.AtABCG14 formed homodimers in human(Homo sapiens)HEK293T,tobacco(Nicotiana tabacum),and Arabidopsis cells.Transporter activity assays of AtABCG14 in Arabidopsis,tobacco,and yeast(Saccharomyces cerevisiae)showed that AtABCG14 may directly transport multiple CKs,including iP-and tZ-type species.AtABCG14 expression was induced by iP in a tZ-type CKdeficient double mutant(cypDM)of CYP735A1 and CYP735A2.The atabcg14 cypDM triple mutant exhibited stronger CK-deficiency phenotypes than cypDM.Hormone profiling,reciprocal grafting,and 2H6-iP isotope tracer experiments showed that root-to-shoot and shoot-to-root long-distance transport of iP-type CKs were suppressed in atabcg14 cypDM and atabcg14.These results suggest that AtABCG14 participates in three steps of the circular long-distance transport of iP-type CKs:xylem loading in the root for shootward transport,phloem unloading in the shoot for shoot distribution,and phloemunloading in the root for root distribution.We found that AtABCG14 displays transporter activity toward multiple CK species and revealed its versatile roles in circular long-distance transport of iP-type CKs.These findings provide newinsights into the transport mechanisms of CKs and other plant hormones.展开更多
BELl-like transcription factors are ubiquitous in plants and interact with KNOTTEDI-types to regulate numerous developmental processes. In potato, the RNA of several BELl-like transcription factors has been identified...BELl-like transcription factors are ubiquitous in plants and interact with KNOTTEDI-types to regulate numerous developmental processes. In potato, the RNA of several BELl-like transcription factors has been identified in phloem cells. One of these, StBEL5, and its Knox protein partner regulate tuber formation by targeting genes that control growth. RNA detection methods and grafting experiments demonstrated that StBEL5 transcripts move across a graft union to localize in stolon tips, the site of tuber induction. This movement of RNA originates in source leaf veins and petioles and is induced by a short-day photoperiod, regulated by the untranslated regions, and correlated with enhanced tuber production. Addition of the StBEL5 untranslated regions to another BELl.like mRNA resulted in its preferential transport to stolon tips leading to increased tuber production. Upon fusion of the untranslated regions of StBEL5 to a β-glucuronidase marker, translation in tobacco protoplasts was repressed by those constructs containing the 3＇ untranslated sequence. The untranslated regions of the StBEL5 mRNA are involved in mediating its long-distance transport and in controlling translation. The 3＇ untranslated sequence contains an abundance of conserved motifs that may serve as binding motifs for RNA-binding proteins. Because of their presence in the phloem sieve tube system, their unique untranslated region sequences and their diverse RNA accumulation patterns, the family of BEL1-like RNAs from potato represents a valuable model for studying the long-distance transport of full-length mRNAs and their role in development.展开更多
Nicotinamide adenine dinucleotide （NAD） biosynthesis, including synthesis from aspartate via the de novo pathway and from nicotinate （NA） via the Preiss-Handler pathway, is conserved in land plants. Diverse spe-ci...Nicotinamide adenine dinucleotide （NAD） biosynthesis, including synthesis from aspartate via the de novo pathway and from nicotinate （NA） via the Preiss-Handler pathway, is conserved in land plants. Diverse spe-cies of NA conjugates, which are mainly involved in NA detoxification, were also found in all tested land plants. Among these conjugates, MeNA （NA methyl ester） has been widely detected in angiosperm plants, although its physiological function and the underlying mechanism for its production in planta remain largely unknown. Here, we show that MeNA is an NAD precursor undergoing more efficient long-distance trans-port between organs than NA and nicotinamide in Arabidopsis. We found that Arabidopsis has one meth- yltransferase （designated AtNaMT1） capable of catalyzing carboxyl methylation of NA to yield MeNA and one methyl esterase （MES2） predominantly hydrolyzing MeNA back to NA. We further uncovered that the transfer of [^14C]MeNA from the root to leaf was significantly increased in both MES2 knockdown and NaMTl-overexpressing lines, suggesting that both NaMT1 and MES2 fine-tune the long-distance transport of MeNA, which is ultimately utilized for NAD production. Abiotic stress （salt, abscisic acid, and mannitol） treatments, which are known to exacerbate NAD degradation, induce the expression of NaMT1 but sup-press MES2 expression, suggesting that MeNA may play a role in stress adaption. Collectively, our study indicates that reversible methylation of NA controls the biosynthesis of MeNA in Arabidopsis, which pre-sumably functions as a detoxification form of free NA for efficient long-distance transport and eventually NAD production especially under abiotic stress, providing new insights into the relationship between NAD biosynthesis and NA conjugation in plants.展开更多
Environmental stresses that perturb plant Hwater relations influence abscisic acid(ABA) concentrations, but it is unclear whether long-distance ABA transport contributes to changes in local ABA levels. To determine th...Environmental stresses that perturb plant Hwater relations influence abscisic acid(ABA) concentrations, but it is unclear whether long-distance ABA transport contributes to changes in local ABA levels. To determine the physiological relevance of ABA transport, we made reciprocal-and self-grafts of ABA-deficient flacca mutant and wild-type(WT) tomato plants, in which low phosphorus(P) conditions decreased ABA concentrations while salinity increased ABA concentrations. Whereas foliar ABA concentrations in the WT scions were rootstock independent under control conditions, salinity resulted in long-distance transport of ABA: flacca scions had approximately twice as much ABA when grafted on WT rootstocks compared to flacca rootstocks. Root ABA concentrations were scion dependent: both WT and flacca rootstocks had less ABA with the flacca mutant scion than with the WT scion under control conditions. In WT scions, whereas rootstock genotype had limited effects on stomatal conductance under control conditions, a flacca rootstock decreased leaf area of stressed plants, presumably due to attenuated root-to-shoot ABA transport. In flacca scions, a WT rootstock decreased stomatal conductance but increased leaf area of stressed plants, likely due to enhanced root-to-shoot ABA transport. Thus, long-distance ABA transport can affect responses in distal tissues by changing local ABA concentrations.展开更多
Based on the monitored data of references, EANET and the CMAQ （4.7.1） model scenado simulations, the annual average concentration of SO2 in China in the recent 10 years and the contribution of China＇s SO2 emissions...Based on the monitored data of references, EANET and the CMAQ （4.7.1） model scenado simulations, the annual average concentration of SO2 in China in the recent 10 years and the contribution of China＇s SO2 emissions to SO2 concentration and sulfur deposition at various sites in Japan downwind were analyzed. The results showed that from 2001 to 2009 annual average concentration of SO2 was 0 -150 μg/m^3 and showed a decreasing trend on the whole in China. The correlation coefficient of annual average concentration of SO2 at different sites in Japan and China＇s SO2 emissions was lower than that of annual average concentration and emission of SO2 in China＇s cities on the whole, showing that SO2 discharged in China had small impact on SO2 concentration in Japan. The contribution rate of China＇s SO2 emissions to annual average concentration of SO2 at various sites in Japan in 2010 was 7.5% -44.0%, averaging 22.6% ; the annual average volume concentration of SO2 at different sites in Japan caused by China＇s SO2 emissions was 0 -0.5 × 10^-9. The contribution rate of China＇s SO2 emissions to sulfur deposition at various sites in Japan in 2010 varied from 8.0% to 41.0%, averaging 22.1%.展开更多
基金supported by the Natural Science Research Project of Guangling College of Yangzhou University,China (ZKZD18004)General Program of Natural Science Research in Higher Education Institutions of Jiangsu Province,China (20KJD430006)。
文摘Gas flexible pipes are critical multi-layered equipment for offshore oil and gas development.Under high pressure conditions,small molecular components of natural gas dissolve into the polymer inner liner of the flexible pipes and further diffuse into the annular space,incurring annular pressure build-up and/or production of acidic environment,which poses serious challenges to the structure and integrity of the flexible pipes.Gas permeation in pipes is a complex phenomenon governed by various factors such as internal pressure and temperature,annular structure,external temperature.In a long-distance gas flexible pipe,moreover,gas permeation exhibits non-uniform features,and the gas permeated into the annular space flows along the metal gap.To assess the complex gas transport behavior in long-distance gas flexible pipes,a mathematical model is established in this paper considering the multiphase flow phenomena inside the flexible pipes,the diffusion of gas in the inner liner,and the gas seepage in the annular space under varying permeable properties of the annulus.In addition,the effect of a variable temperature is accounted.A numerical calculation method is accordingly constructed to solve the coupling mathematical equations.The annular permeability was shown to significantly influence the distribution of annular pressure.As permeability increases,the annular pressure tends to become more uniform,and the annular pressure at the wellhead rises more rapidly.After annular pressure relief followed by shut-in,the pressure increase follows a convex function.By simulating the pressure recovery pattern after pressure relief and comparing it with test results,we deduce that the annular permeability lies between 123 and 512 m D.The results help shed light upon assessing the annular pressure in long distance gas flexible pipes and thus ensure the security of gas transport in the emerging development of offshore resources.
基金Project(2016YFC0600709)supported by the National Key R&D Program of ChinaProject(51574013)supported by the National Natural Science Foundation of ChinaProject(FRF-TP-17-024A1)supported by the Fundamental Research Funds for the Central Universities,China
文摘Based on Bingham rheological model,a three-dimensional numerical simulation model for long-distance pipeline transportation is established by computational fluid dynamics(CFD)to study the pipeline transportationproperties of high sliming paste from a copper mine in China.Based on the rheological properties test,the pressure and velocity of pipeline and elbow are simulated by CFD under different mass concentrations and different stowing capacities.The results show that the pipeline resistance of whole-tailings paste with high sliming while without pumping agent is much higher than that with high sliming and pumping agent at the same mass concentration,and the pipeline resistance of whole-tailings paste with high sliming while without pumping agent is much higher than that with low sliming while without pumping agent.It is very important to add pumping agent to whole-tailings paste with high sliming,and the resistance changes with mass concentration and stowing capacity at the same cement-to-sand ratio of1:5and tailings-to-waste ratio of6:1.However,the change is just limited,that is to say,the paste transportation system is of good stability.Furthermore,at the elbow,the maximum pressure and velocity transfer to the outside of the pipe from the inside.However,lubricating layer is formed at the pipe wall because of high content of fine particles in whole-tailings paste,which will protect the elbow from abrasion.CFD provides an intuitive and accurate basis for pipeline transportation study,and would have a wider application space in the study of paste rheological properties and resistance reduction methods.
基金the National Natural Science Foundation of China(31470370 to K.Z.and 32100270 to J.Z.)the Natural Science Foundation of Zhejiang Province(LY22C020003 to J.Z.)C.-J.L.was supported by the DOE Office of Basic Energy Sciences,specifically through the Physical Biosciences Program of the Chemical Sciences,Geosciences and Biosciences Division,under contract DESC0012704.
文摘Cytokinins(CKs),primarily trans-zeatin(tZ)and isopentenyladenine(iP)types,play critical roles in plant growth,development,and various stress responses.Long-distance transport of tZ-type CKs meidated by Arabidopsis ATP-binding cassette transporter subfamily G14(AtABCG14)has been well studied;however,less is known about the biochemical properties of AtABCG14 and its transporter activity toward iP-type CKs.Here we reveal the biochemical properties of AtABCG14 and provide evidence that it is also required for long-distance transport of iP-type CKs.AtABCG14 formed homodimers in human(Homo sapiens)HEK293T,tobacco(Nicotiana tabacum),and Arabidopsis cells.Transporter activity assays of AtABCG14 in Arabidopsis,tobacco,and yeast(Saccharomyces cerevisiae)showed that AtABCG14 may directly transport multiple CKs,including iP-and tZ-type species.AtABCG14 expression was induced by iP in a tZ-type CKdeficient double mutant(cypDM)of CYP735A1 and CYP735A2.The atabcg14 cypDM triple mutant exhibited stronger CK-deficiency phenotypes than cypDM.Hormone profiling,reciprocal grafting,and 2H6-iP isotope tracer experiments showed that root-to-shoot and shoot-to-root long-distance transport of iP-type CKs were suppressed in atabcg14 cypDM and atabcg14.These results suggest that AtABCG14 participates in three steps of the circular long-distance transport of iP-type CKs:xylem loading in the root for shootward transport,phloem unloading in the shoot for shoot distribution,and phloemunloading in the root for root distribution.We found that AtABCG14 displays transporter activity toward multiple CK species and revealed its versatile roles in circular long-distance transport of iP-type CKs.These findings provide newinsights into the transport mechanisms of CKs and other plant hormones.
基金supported by the United States Departmentof Agriculture NRI-CGP award no.2008-02806National Science Foundation-Plant Genome Research Program award no.0820659
文摘BELl-like transcription factors are ubiquitous in plants and interact with KNOTTEDI-types to regulate numerous developmental processes. In potato, the RNA of several BELl-like transcription factors has been identified in phloem cells. One of these, StBEL5, and its Knox protein partner regulate tuber formation by targeting genes that control growth. RNA detection methods and grafting experiments demonstrated that StBEL5 transcripts move across a graft union to localize in stolon tips, the site of tuber induction. This movement of RNA originates in source leaf veins and petioles and is induced by a short-day photoperiod, regulated by the untranslated regions, and correlated with enhanced tuber production. Addition of the StBEL5 untranslated regions to another BELl.like mRNA resulted in its preferential transport to stolon tips leading to increased tuber production. Upon fusion of the untranslated regions of StBEL5 to a β-glucuronidase marker, translation in tobacco protoplasts was repressed by those constructs containing the 3＇ untranslated sequence. The untranslated regions of the StBEL5 mRNA are involved in mediating its long-distance transport and in controlling translation. The 3＇ untranslated sequence contains an abundance of conserved motifs that may serve as binding motifs for RNA-binding proteins. Because of their presence in the phloem sieve tube system, their unique untranslated region sequences and their diverse RNA accumulation patterns, the family of BEL1-like RNAs from potato represents a valuable model for studying the long-distance transport of full-length mRNAs and their role in development.
文摘Nicotinamide adenine dinucleotide （NAD） biosynthesis, including synthesis from aspartate via the de novo pathway and from nicotinate （NA） via the Preiss-Handler pathway, is conserved in land plants. Diverse spe-cies of NA conjugates, which are mainly involved in NA detoxification, were also found in all tested land plants. Among these conjugates, MeNA （NA methyl ester） has been widely detected in angiosperm plants, although its physiological function and the underlying mechanism for its production in planta remain largely unknown. Here, we show that MeNA is an NAD precursor undergoing more efficient long-distance trans-port between organs than NA and nicotinamide in Arabidopsis. We found that Arabidopsis has one meth- yltransferase （designated AtNaMT1） capable of catalyzing carboxyl methylation of NA to yield MeNA and one methyl esterase （MES2） predominantly hydrolyzing MeNA back to NA. We further uncovered that the transfer of [^14C]MeNA from the root to leaf was significantly increased in both MES2 knockdown and NaMTl-overexpressing lines, suggesting that both NaMT1 and MES2 fine-tune the long-distance transport of MeNA, which is ultimately utilized for NAD production. Abiotic stress （salt, abscisic acid, and mannitol） treatments, which are known to exacerbate NAD degradation, induce the expression of NaMT1 but sup-press MES2 expression, suggesting that MeNA may play a role in stress adaption. Collectively, our study indicates that reversible methylation of NA controls the biosynthesis of MeNA in Arabidopsis, which pre-sumably functions as a detoxification form of free NA for efficient long-distance transport and eventually NAD production especially under abiotic stress, providing new insights into the relationship between NAD biosynthesis and NA conjugation in plants.
基金supported by the National Natural Science Foundation of China (31300327)Excellent Young Scientist Foundation of Henan University (yqpy20140030)the EU ROOTOPOWER (289365) project for supporting research on grafting
文摘Environmental stresses that perturb plant Hwater relations influence abscisic acid(ABA) concentrations, but it is unclear whether long-distance ABA transport contributes to changes in local ABA levels. To determine the physiological relevance of ABA transport, we made reciprocal-and self-grafts of ABA-deficient flacca mutant and wild-type(WT) tomato plants, in which low phosphorus(P) conditions decreased ABA concentrations while salinity increased ABA concentrations. Whereas foliar ABA concentrations in the WT scions were rootstock independent under control conditions, salinity resulted in long-distance transport of ABA: flacca scions had approximately twice as much ABA when grafted on WT rootstocks compared to flacca rootstocks. Root ABA concentrations were scion dependent: both WT and flacca rootstocks had less ABA with the flacca mutant scion than with the WT scion under control conditions. In WT scions, whereas rootstock genotype had limited effects on stomatal conductance under control conditions, a flacca rootstock decreased leaf area of stressed plants, presumably due to attenuated root-to-shoot ABA transport. In flacca scions, a WT rootstock decreased stomatal conductance but increased leaf area of stressed plants, likely due to enhanced root-to-shoot ABA transport. Thus, long-distance ABA transport can affect responses in distal tissues by changing local ABA concentrations.
基金Supported by the National Natural Science Foundation of China(41373131)National Key Technology R&D Program(2014BAC23B03)Major Tender Project of Social Science Foundation of Human Province,China(14DA12)
文摘Based on the monitored data of references, EANET and the CMAQ （4.7.1） model scenado simulations, the annual average concentration of SO2 in China in the recent 10 years and the contribution of China＇s SO2 emissions to SO2 concentration and sulfur deposition at various sites in Japan downwind were analyzed. The results showed that from 2001 to 2009 annual average concentration of SO2 was 0 -150 μg/m^3 and showed a decreasing trend on the whole in China. The correlation coefficient of annual average concentration of SO2 at different sites in Japan and China＇s SO2 emissions was lower than that of annual average concentration and emission of SO2 in China＇s cities on the whole, showing that SO2 discharged in China had small impact on SO2 concentration in Japan. The contribution rate of China＇s SO2 emissions to annual average concentration of SO2 at various sites in Japan in 2010 was 7.5% -44.0%, averaging 22.6% ; the annual average volume concentration of SO2 at different sites in Japan caused by China＇s SO2 emissions was 0 -0.5 × 10^-9. The contribution rate of China＇s SO2 emissions to sulfur deposition at various sites in Japan in 2010 varied from 8.0% to 41.0%, averaging 22.1%.
