有活力但不可培养(viable but non-culturable,VBNC)状态是细菌遭遇逆境时进入的一种特殊状态,该状态下的菌体在条件适宜时可复苏并恢复其致病性,被认为是细菌躲避不良环境的一种生存策略。VBNC状态菌体对人类医学和工农业生产具有巨大...有活力但不可培养(viable but non-culturable,VBNC)状态是细菌遭遇逆境时进入的一种特殊状态,该状态下的菌体在条件适宜时可复苏并恢复其致病性,被认为是细菌躲避不良环境的一种生存策略。VBNC状态菌体对人类医学和工农业生产具有巨大的潜在威胁,开展关于VBNC状态的检测及诱导、复苏及其机制研究可为减少或避免该状态细菌的危害提供理论基础。本文简要综述了细菌VBNC状态在诱导、复苏及致病性等方面的研究进展,并结合本实验室及国内外相关团队近年来在植物病原细菌VBNC状态研究中的结果,详细总结了VBNC状态细菌的形成和复苏机制,对植物病原细菌在环境胁迫下的存活机制、病害田间初侵染来源分析及VBNC状态菌体在病害循环中的作用等相关研究具有重要参考意义。展开更多
Sixteen pairs of two-component regulatory systems are identified in the genome of Staphylococcus epidermidis ATCC12228 strain, which is newly sequenced by our laboratory for Medical Molecular Virology and Chinese Nati...Sixteen pairs of two-component regulatory systems are identified in the genome of Staphylococcus epidermidis ATCC12228 strain, which is newly sequenced by our laboratory for Medical Molecular Virology and Chinese National Human Genome Center at Shanghai, by using bio- informatics analysis. Comparative analysis of the two- component regulatory systems in S. epidermidis and that of S. aureus and Bacillus subtilis shows that these systems may regulate some important biological functions, e.g. growth, biofilm formation, and expression of virulence factors in S. epidermidis. Two conserved domains, i.e. HATPase_c and REC domains, are found in all 16 pairs of two-component proteins. Homologous modelling analysis indicates that there are 4 similar HATPase_c domain structures of histidine kinases and 13 similar REC domain structures of response regulators, and there is one AMP-PNP binding pocket in the HATPase_c domain and three active aspartate residues in the REC domain. Preliminary experiment reveals that the bioinfor- matics analysis of the conserved domain structures in the two-component regulatory systems in S. epidermidis may provide useful information for discovery of potential drug target.展开更多
Seed weight is usually associated with seed size and is one of the important agronomic traits that determine yield.Understanding of seed weight control is limited,especially in soybean plants.Here we show that Glycine...Seed weight is usually associated with seed size and is one of the important agronomic traits that determine yield.Understanding of seed weight control is limited,especially in soybean plants.Here we show that Glycine max JASMONATEZIM DOMAIN 3(GmJAZ3),a gene identified through gene co-expression network analysis,regulates seed-related traits in soybean.Overexpression of GmJAZ3 promotes seed size/weight and other organ sizes in stable transgenic soybean plants likely by increasing cell proliferation.GmJAZ3 interacted with both G.max RESPONSE REGULATOR 18a(GmRR18a)and GmMYC2a to inhibit their transcriptional activation of cytokinin oxidase gene G.max CYTOKININ OXIDASE 3-4(GmCKX3-4),which usually affects seed traits.Meanwhile,the GmRR18a binds to the promoter of GmMYC2a and activates GmMYC2a gene expression.In GmJAZ3-overexpressing soybean seeds,the protein contents were increased while the fatty acid contents were reduced compared to those in the control seeds,indicating that the GmJAZ3 affects seed size/weight and compositions.Natural variation in JAZ3 promoter region was further analyzed and Hap3 promoter correlates with higher promoter activity,higher gene expression and higher seed weight.The Hap3 promoter may be selected and fixed during soybean domestication.JAZ3 orthologs from other plants/crops may also control seed size and weight.Taken together,our study reveals a novel molecular module GmJAZ3-GmRR18a/GmMYC2a-GmCKXs for seed size and weight control,providing promising targets during soybean molecular breeding for better seed traits.展开更多
p204 is a member of the interferon-inducible p200 family proteins in mice.The p200 family has been reported to be multifunctional regulators of cell proliferation,differentiation,apoptosis and senescence.Interferon-in...p204 is a member of the interferon-inducible p200 family proteins in mice.The p200 family has been reported to be multifunctional regulators of cell proliferation,differentiation,apoptosis and senescence.Interferon-inducible protein 16(IFI16)is regarded as the human ortholog of p204 in several studies.This is possibly due to the similarity of their structures.However the consistency of their functions is still elusive.Currently,an emerging focus has been placed upon the role of the p200 proteins as sensors for microbial DNA in innate immune responses and provides new insights into infections as well as autoimmune diseases.This review specially focuses on IFI16 and p204,the member of p200 family in human and murine respectively,and their pathophysiological roles in innate immune responses,cell differentiation and proliferation.展开更多
Soil salinity severely limits crop yields and quality.Plants have evolved several strategies to mitigate the adverse effects of salinity,including redistribution and compartmentalization of toxic ions using ion-specif...Soil salinity severely limits crop yields and quality.Plants have evolved several strategies to mitigate the adverse effects of salinity,including redistribution and compartmentalization of toxic ions using ion-specific transporters.However,the mechanisms underlying the regulation of these ion transporters have not been fully elucidated.Loss-of-function mutants of OsHKT2;1,which is involved in sodium uptake,exhibit strong salt stress-resistant phenotypes.In this study,OsHKT2;1 was identified as a transcriptional target of the type-B response regulator OsRR22.Loss-of-function osrr22 mutants showed resilience to salt stress,and OsRR22-overexpression plants were sensitive to salt stress.OsRR22 was found to activate the expression of OsHKT2;1 by directly binding to the promoter region of OsHKT2;1 via a consensus cis-element of type-B response regulators.Moreover,rice DELLA protein OsSLR1 directly interacted with OsRR22 and functioned as a transcriptional co-activator.This study has uncovered a novel transcriptional regulatory mechanism by which a type-B response regulator controls sodium transport under salinity stress.展开更多
Abscisic acid （ABA） plays crucial roles in plant growth and development, as well as in response to various environmental stresses. To date, many regulatory genes involved in the ABA response network have been identi...Abscisic acid （ABA） plays crucial roles in plant growth and development, as well as in response to various environmental stresses. To date, many regulatory genes involved in the ABA response network have been identified; however, their roles have remained to be fully elucidated. In this study, we iden- tified AtYY1, an Arabidopsis homolog of the mammalian C2H2 zinc-finger transcription factor Yin Yang 1 （YY1）, as a novel negative regulator of the ABA response. AtYY1 is a dual-function transcription factor with both repression and activation domains. The expression of AtYY1 was induced by ABA and stress conditions including high salt and dehydration. The yyl mutant was more sensitive to ABA and NaCI than the wild-type, while overexpressing AtYY1 plants were less sensitive. AtYY1 loss also enhanced ABA-induced stomatal closing and drought resistance. Moreover, AtYYI can bind the ABA REPRESSOR1 （ABR1） promoter and directly upregulate ABR1 expression, as well as negatively regulate ABA- and saR-responsive gene expression. Additional analysis indicated that ABA INSENSITIVE4 （ABI4） might positively regulate AtYY1 expression and that ABR1 can antagonize this regulation. Our findings provide direct evidence that AtYY1 is a novel negative regulator of the ABA response network and that the ABI4-AtYY1-ABR1 regulatory pathway may fine-tune ABA-responsive gene expression in Arabidopsis.展开更多
The plant hormone cytokinin plays important roles in various aspects of plant growth and development. Cytokinin signaling is mediated by a multistep phosphorelay similar to bacterial two-component system. Type-B ARRs ...The plant hormone cytokinin plays important roles in various aspects of plant growth and development. Cytokinin signaling is mediated by a multistep phosphorelay similar to bacterial two-component system. Type-B ARRs lie at the end of the cytokinin signaling, typically mediating tile output response. However, it is still unclear how type-B ARRs are regulated in response to cytokinin. Typical type-B ARR contains an N-terminal receiver domain and a C-terminal effector domain. In this study, we performed a genome-wild comparative analysis by overexpressing full length and C-terminal effector domain of seven representative type-B ARRs. Our results indicated that overexpression of C-terminal effector domain causes short primary roots and short hypocotyls without the addition of cytokinin, sug- gesting that the inhibitory role of the receiver domain in the activity of the effector domain is a common mechanism in type-B ARRs. To investigate how the receiver domain inhibits the activity of the effector domain, we performed a deletion analysis. We found that deletion of the initial 45 residues of ARR18 （the 45 residues from N-terminus） causes pleiotropic growth defects by directly inducing cytokinin responsive genes. Together, our results suggest that the initial 45 residues are critical for the inhibitory role of the receiver domain to the effector domain in ARRI8.展开更多
The multistep phosphorelay （MSP） is a central signaling pathway in plants integrating a wide spectrum of hormonal and environmental inputs and controlling numerous developmental adaptations. For the thor- ough compr...The multistep phosphorelay （MSP） is a central signaling pathway in plants integrating a wide spectrum of hormonal and environmental inputs and controlling numerous developmental adaptations. For the thor- ough comprehension of the molecular mechanisms underlying the MSP-mediated signal recognition and transduction, the detailed structural characterization of individual members of the pathway is critical. In this review we describe and discuss the recently known crystal and nuclear magnetic resonance structures of proteins acting in MSP signaling in higher plants, focusing particularly on cytokinin and ethylene signaling in Arabidopsis thaliana. We discuss the range of functional aspects of available structural infor- mation including determination of ligand specificity, activation of the receptor via its autophosphorylaUon, and downstream signal transduction through the phosphorelay. We compare the plant structures with their bacterial counterparts and show that although the overall similarity is high, the differences in structural de- tails are frequent and functionally important. Finally, we discuss emerging knowledge on molecular recog- nition mechanisms in the MSP, and mention the latest findings regarding structural determinants of signaling specificity in the Arabidopsis MSP that could serve as a general model of this pathway in all higher plants.展开更多
This paper presents a 200 mA low-dropout （LDO） linear regulator using two modified techniques for frequency compensation. One technique is that the error amplifier uses a common source stage with variable load, whic...This paper presents a 200 mA low-dropout （LDO） linear regulator using two modified techniques for frequency compensation. One technique is that the error amplifier uses a common source stage with variable load, which is controlled by the output current, is served as the second stage for a stable frequency response. The other technique is that the LDO uses a pole-zero tracking compensation technique at the error amplifier to achieve a good frequency response. The proposed circuit was fabricated and tested in HJTC 0.18 μm CMOS technology. The designed LDO linear regulator works under the input voltage of 2.8-5 V and provides up to 200 mA load current for an output voltage of 1.8 V. The total error of the output voltage due to line and load variation is less than 0.015%. The LDO die area is 630 x 550 μm^2 and the quiescent current is 130 μA.展开更多
Granular power management in a power-efficient system on a chip(SoC)requires multiple integrated voltage regulators with a small area,process scalability,and low supply voltage.Conventional on-chip analog low-dropout ...Granular power management in a power-efficient system on a chip(SoC)requires multiple integrated voltage regulators with a small area,process scalability,and low supply voltage.Conventional on-chip analog low-dropout regulators(ALDOs)can hardly meet these requirements,while digital LDOs(DLDOs)are good alternatives.However,the conventional DLDO,with synchronous control,has inherently slow transient response limited by the power-speed trade-off.Meanwhile,it has a poor power supply rejection(PSR),because the fully turned-on power switches in DLDO are vulnerable to power supply ripples.In this comparative study on DLDOs,first,we compare the pros and cons between ALDO and DLDO in general.Then,we summarize the recent DLDO advanced techniques for fast transient response and PSR enhancement.Finally,we discuss the design trends and possible directions of DLDO.展开更多
Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, ...Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it＇s proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.展开更多
In this paper the solution conformation of the response regulator proteins from Deinococcus radiodurans was studied by small-angle X-ray scattering （SAXS）. The SAXS curves of Dr-rrA in solutions were obtained at Bea...In this paper the solution conformation of the response regulator proteins from Deinococcus radiodurans was studied by small-angle X-ray scattering （SAXS）. The SAXS curves of Dr-rrA in solutions were obtained at Beamline 1W2A of Beijing Synchrotron Radiation Facility （BSRF）. Two possible conformations of the response regulator proteins, compact and incompact conformations, have been represented by the known crystallographic structures. And theoretical solution scattering curves of the two possible conformations were calculated and fitted to the experimental scattering curve of Dr-rrA, respectively. The result indicates that the solution conformation of the response regulator proteins is inclined to the compact one, which is in agreement with the result of biochemical experiments.展开更多
文摘有活力但不可培养(viable but non-culturable,VBNC)状态是细菌遭遇逆境时进入的一种特殊状态,该状态下的菌体在条件适宜时可复苏并恢复其致病性,被认为是细菌躲避不良环境的一种生存策略。VBNC状态菌体对人类医学和工农业生产具有巨大的潜在威胁,开展关于VBNC状态的检测及诱导、复苏及其机制研究可为减少或避免该状态细菌的危害提供理论基础。本文简要综述了细菌VBNC状态在诱导、复苏及致病性等方面的研究进展,并结合本实验室及国内外相关团队近年来在植物病原细菌VBNC状态研究中的结果,详细总结了VBNC状态细菌的形成和复苏机制,对植物病原细菌在环境胁迫下的存活机制、病害田间初侵染来源分析及VBNC状态菌体在病害循环中的作用等相关研究具有重要参考意义。
文摘Sixteen pairs of two-component regulatory systems are identified in the genome of Staphylococcus epidermidis ATCC12228 strain, which is newly sequenced by our laboratory for Medical Molecular Virology and Chinese National Human Genome Center at Shanghai, by using bio- informatics analysis. Comparative analysis of the two- component regulatory systems in S. epidermidis and that of S. aureus and Bacillus subtilis shows that these systems may regulate some important biological functions, e.g. growth, biofilm formation, and expression of virulence factors in S. epidermidis. Two conserved domains, i.e. HATPase_c and REC domains, are found in all 16 pairs of two-component proteins. Homologous modelling analysis indicates that there are 4 similar HATPase_c domain structures of histidine kinases and 13 similar REC domain structures of response regulators, and there is one AMP-PNP binding pocket in the HATPase_c domain and three active aspartate residues in the REC domain. Preliminary experiment reveals that the bioinfor- matics analysis of the conserved domain structures in the two-component regulatory systems in S. epidermidis may provide useful information for discovery of potential drug target.
基金supported by the National Key R&D Project(2021YFF1001201,2021YFF1000104-2)the National Natural Science Foundation of China(32090062,32090063)+2 种基金the Chinese Academy of Science leading project(XDA24010105)the State Key Lab of Plant Genomicsthe Qilu Zhongke Academy of Modern Microbiology Technology。
文摘Seed weight is usually associated with seed size and is one of the important agronomic traits that determine yield.Understanding of seed weight control is limited,especially in soybean plants.Here we show that Glycine max JASMONATEZIM DOMAIN 3(GmJAZ3),a gene identified through gene co-expression network analysis,regulates seed-related traits in soybean.Overexpression of GmJAZ3 promotes seed size/weight and other organ sizes in stable transgenic soybean plants likely by increasing cell proliferation.GmJAZ3 interacted with both G.max RESPONSE REGULATOR 18a(GmRR18a)and GmMYC2a to inhibit their transcriptional activation of cytokinin oxidase gene G.max CYTOKININ OXIDASE 3-4(GmCKX3-4),which usually affects seed traits.Meanwhile,the GmRR18a binds to the promoter of GmMYC2a and activates GmMYC2a gene expression.In GmJAZ3-overexpressing soybean seeds,the protein contents were increased while the fatty acid contents were reduced compared to those in the control seeds,indicating that the GmJAZ3 affects seed size/weight and compositions.Natural variation in JAZ3 promoter region was further analyzed and Hap3 promoter correlates with higher promoter activity,higher gene expression and higher seed weight.The Hap3 promoter may be selected and fixed during soybean domestication.JAZ3 orthologs from other plants/crops may also control seed size and weight.Taken together,our study reveals a novel molecular module GmJAZ3-GmRR18a/GmMYC2a-GmCKXs for seed size and weight control,providing promising targets during soybean molecular breeding for better seed traits.
基金supported partly by NIH Research Grants R01AR062207,R01AR061484,and R56AI100901,Disease Targeted Research Grants from the American College of Rheumatology Research and Education Foundation.
文摘p204 is a member of the interferon-inducible p200 family proteins in mice.The p200 family has been reported to be multifunctional regulators of cell proliferation,differentiation,apoptosis and senescence.Interferon-inducible protein 16(IFI16)is regarded as the human ortholog of p204 in several studies.This is possibly due to the similarity of their structures.However the consistency of their functions is still elusive.Currently,an emerging focus has been placed upon the role of the p200 proteins as sensors for microbial DNA in innate immune responses and provides new insights into infections as well as autoimmune diseases.This review specially focuses on IFI16 and p204,the member of p200 family in human and murine respectively,and their pathophysiological roles in innate immune responses,cell differentiation and proliferation.
基金supported by the National Natural Science Foundation of China (32001448,32272027)。
文摘Soil salinity severely limits crop yields and quality.Plants have evolved several strategies to mitigate the adverse effects of salinity,including redistribution and compartmentalization of toxic ions using ion-specific transporters.However,the mechanisms underlying the regulation of these ion transporters have not been fully elucidated.Loss-of-function mutants of OsHKT2;1,which is involved in sodium uptake,exhibit strong salt stress-resistant phenotypes.In this study,OsHKT2;1 was identified as a transcriptional target of the type-B response regulator OsRR22.Loss-of-function osrr22 mutants showed resilience to salt stress,and OsRR22-overexpression plants were sensitive to salt stress.OsRR22 was found to activate the expression of OsHKT2;1 by directly binding to the promoter region of OsHKT2;1 via a consensus cis-element of type-B response regulators.Moreover,rice DELLA protein OsSLR1 directly interacted with OsRR22 and functioned as a transcriptional co-activator.This study has uncovered a novel transcriptional regulatory mechanism by which a type-B response regulator controls sodium transport under salinity stress.
基金This work was financially supported by grants from the National Transgenic Animals ＆ Plants Research Project （2009ZX08009-069B, 2013ZX08009-003）, the State Key Basic Research and Development Plan （2010CB126003）, and the China Postdoctoral Science Foundation （20080430370）.
文摘Abscisic acid （ABA） plays crucial roles in plant growth and development, as well as in response to various environmental stresses. To date, many regulatory genes involved in the ABA response network have been identified; however, their roles have remained to be fully elucidated. In this study, we iden- tified AtYY1, an Arabidopsis homolog of the mammalian C2H2 zinc-finger transcription factor Yin Yang 1 （YY1）, as a novel negative regulator of the ABA response. AtYY1 is a dual-function transcription factor with both repression and activation domains. The expression of AtYY1 was induced by ABA and stress conditions including high salt and dehydration. The yyl mutant was more sensitive to ABA and NaCI than the wild-type, while overexpressing AtYY1 plants were less sensitive. AtYY1 loss also enhanced ABA-induced stomatal closing and drought resistance. Moreover, AtYYI can bind the ABA REPRESSOR1 （ABR1） promoter and directly upregulate ABR1 expression, as well as negatively regulate ABA- and saR-responsive gene expression. Additional analysis indicated that ABA INSENSITIVE4 （ABI4） might positively regulate AtYY1 expression and that ABR1 can antagonize this regulation. Our findings provide direct evidence that AtYY1 is a novel negative regulator of the ABA response network and that the ABI4-AtYY1-ABR1 regulatory pathway may fine-tune ABA-responsive gene expression in Arabidopsis.
基金supported by grants from Chinese Academy of Sciences(No.KYQY-QN-020)
文摘The plant hormone cytokinin plays important roles in various aspects of plant growth and development. Cytokinin signaling is mediated by a multistep phosphorelay similar to bacterial two-component system. Type-B ARRs lie at the end of the cytokinin signaling, typically mediating tile output response. However, it is still unclear how type-B ARRs are regulated in response to cytokinin. Typical type-B ARR contains an N-terminal receiver domain and a C-terminal effector domain. In this study, we performed a genome-wild comparative analysis by overexpressing full length and C-terminal effector domain of seven representative type-B ARRs. Our results indicated that overexpression of C-terminal effector domain causes short primary roots and short hypocotyls without the addition of cytokinin, sug- gesting that the inhibitory role of the receiver domain in the activity of the effector domain is a common mechanism in type-B ARRs. To investigate how the receiver domain inhibits the activity of the effector domain, we performed a deletion analysis. We found that deletion of the initial 45 residues of ARR18 （the 45 residues from N-terminus） causes pleiotropic growth defects by directly inducing cytokinin responsive genes. Together, our results suggest that the initial 45 residues are critical for the inhibitory role of the receiver domain to the effector domain in ARRI8.
文摘The multistep phosphorelay （MSP） is a central signaling pathway in plants integrating a wide spectrum of hormonal and environmental inputs and controlling numerous developmental adaptations. For the thor- ough comprehension of the molecular mechanisms underlying the MSP-mediated signal recognition and transduction, the detailed structural characterization of individual members of the pathway is critical. In this review we describe and discuss the recently known crystal and nuclear magnetic resonance structures of proteins acting in MSP signaling in higher plants, focusing particularly on cytokinin and ethylene signaling in Arabidopsis thaliana. We discuss the range of functional aspects of available structural infor- mation including determination of ligand specificity, activation of the receptor via its autophosphorylaUon, and downstream signal transduction through the phosphorelay. We compare the plant structures with their bacterial counterparts and show that although the overall similarity is high, the differences in structural de- tails are frequent and functionally important. Finally, we discuss emerging knowledge on molecular recog- nition mechanisms in the MSP, and mention the latest findings regarding structural determinants of signaling specificity in the Arabidopsis MSP that could serve as a general model of this pathway in all higher plants.
文摘This paper presents a 200 mA low-dropout （LDO） linear regulator using two modified techniques for frequency compensation. One technique is that the error amplifier uses a common source stage with variable load, which is controlled by the output current, is served as the second stage for a stable frequency response. The other technique is that the LDO uses a pole-zero tracking compensation technique at the error amplifier to achieve a good frequency response. The proposed circuit was fabricated and tested in HJTC 0.18 μm CMOS technology. The designed LDO linear regulator works under the input voltage of 2.8-5 V and provides up to 200 mA load current for an output voltage of 1.8 V. The total error of the output voltage due to line and load variation is less than 0.015%. The LDO die area is 630 x 550 μm^2 and the quiescent current is 130 μA.
基金supported by the National Natural Science Foundation of China(No.61974046)the Provincial Key Research and Development Program of Guangdong(2019B010140002)the Macao Science&Technology Development Fund(FDCT)145/2019/A3 and SKL-AMSV(UM)-2020-2022.
文摘Granular power management in a power-efficient system on a chip(SoC)requires multiple integrated voltage regulators with a small area,process scalability,and low supply voltage.Conventional on-chip analog low-dropout regulators(ALDOs)can hardly meet these requirements,while digital LDOs(DLDOs)are good alternatives.However,the conventional DLDO,with synchronous control,has inherently slow transient response limited by the power-speed trade-off.Meanwhile,it has a poor power supply rejection(PSR),because the fully turned-on power switches in DLDO are vulnerable to power supply ripples.In this comparative study on DLDOs,first,we compare the pros and cons between ALDO and DLDO in general.Then,we summarize the recent DLDO advanced techniques for fast transient response and PSR enhancement.Finally,we discuss the design trends and possible directions of DLDO.
文摘Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it＇s proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.
基金Supported by National Natural Science Foundation of China(10979005)National Basic Research Program of China(2009CB918600)
文摘In this paper the solution conformation of the response regulator proteins from Deinococcus radiodurans was studied by small-angle X-ray scattering （SAXS）. The SAXS curves of Dr-rrA in solutions were obtained at Beamline 1W2A of Beijing Synchrotron Radiation Facility （BSRF）. Two possible conformations of the response regulator proteins, compact and incompact conformations, have been represented by the known crystallographic structures. And theoretical solution scattering curves of the two possible conformations were calculated and fitted to the experimental scattering curve of Dr-rrA, respectively. The result indicates that the solution conformation of the response regulator proteins is inclined to the compact one, which is in agreement with the result of biochemical experiments.
