植物果聚糖是一类重要的可溶性碳水化合物,其在植物中的积累可提高植物的抗逆性。为了解大蒜蔗糖:蔗糖1-果糖基转移酶的序列特征和功能,本研究采用TA克隆方法(Original TA Cloning Kit)得到乐都紫皮大蒜As-1-SST基因全长序列,利用BLAST...植物果聚糖是一类重要的可溶性碳水化合物,其在植物中的积累可提高植物的抗逆性。为了解大蒜蔗糖:蔗糖1-果糖基转移酶的序列特征和功能,本研究采用TA克隆方法(Original TA Cloning Kit)得到乐都紫皮大蒜As-1-SST基因全长序列,利用BLAST、DNAMAN、ProtParam、SWISS-MODEL、MEGA等生物信息工具分析其序列特征,通过荧光定量PCR(qRT-PCR)分析As-1-SST基因在大蒜根、假茎、叶片和鳞芽中的表达差异及其对低温和干旱胁迫的响应情况。结果表明,大蒜As-1-SST基因全长1872 bp,编码623个氨基酸,推测蛋白质分子质量为69.76 kDa,理论等电点为5.19,为不稳定亲水性蛋白;亚细胞定位预测结果显示,As-1-SST蛋白主要定位于液泡,该蛋白无信号肽,包含2个特异位点,属于糖苷水解酶32(GH32)家族。在进化关系上,大蒜As-1-SST与百合科的洋葱1-SST亲缘关系最为接近。qRT-PCR分析表明,As-1-SST基因在根中的表达量最高,其次是假茎,在鳞芽和叶片中表达水平较低,具有明显的组织特异性;不同组织As-1-SST对于低温及干旱胁迫的响应差异显著,低温胁迫显著诱导了根、假茎、叶片中As-1-SST的表达,而干旱胁迫只显著提高了鳞芽中As-1-SST的表达量,说明大蒜各组织As-1-SST对逆境信号的响应机制不同。本研究为进一步鉴定大蒜果聚糖合成酶基因的生物信息学功能和表达调控机制提供了一定的理论依据。展开更多
Long pulse （of the order of 1000 s or more） SST-1 tokamak experiments demand a data acquisition system that is capable of acquiring data from various diagnostics channels without losing useful data （and hence physi...Long pulse （of the order of 1000 s or more） SST-1 tokamak experiments demand a data acquisition system that is capable of acquiring data from various diagnostics channels without losing useful data （and hence physics information） while avoiding unnecessary generation of a large volume data. SST-1 Phase-1 tokamak operation has been envisaged with data acquisition of several essential diagnostics channels. These channels demand data acquisition at a sampling rate ranging from 1 kilo samples per second （KSPS） to 1 mega samples per second （MSPS）. Considering the technical characteristics and requirements of the diagnostics, a data acquisition system based on PXI and CAMAC has been developed for SST-1 plasma diagnostics. Both these data acquisition systems are scalable. Present data acquisition needs involving slow plasma diagnostics are catered by the PXI based data acquisition system. On the other hand, CAMAC data acquisition hardware meets all requirements of the SST-1 Phase-1 fast plasma diagnostics channels. A graphical user interface for both data acquisition systems （PXI and CAMAC） has been developed using LabVIEW application development software. The collected data on the local hard disk are directly streaming to the central server through a dedicated network for post-shot data analysis. This paper describes the development and integration of the data acquisition system for SST-1 Phase-1 plasma diagnostics. The integrated testing of the developed data acquisition system has been performed using SST-1 central control and diagnostics signal conditioning units. In the absence of plasma shots, the integrated testing of the data acquisition system for the initial diagnostics of SST-1 Phase-1 operation has been performed with simulated physical signals. The primary engineering objective of this integrated testing is to validate the performance of the developed data acquisition system under simulated conditions close to that of actual tokamak operation. The data acquisition is synchronized with a clock and trigger provided by the central timing system.展开更多
In contrast to the earlier experiments conducted in other machines, here, in SST-1 the error field measurement experiment is performed with a filled gas pressure ~8×10^-4 mbar which helped to create a luminescent...In contrast to the earlier experiments conducted in other machines, here, in SST-1 the error field measurement experiment is performed with a filled gas pressure ~8×10^-4 mbar which helped to create a luminescent toroidal beam of electron path originated due to impact excitation and guided by the toroidal magnetic field. Beam path deviations are observed and recorded from radial and top ports using visible range cameras. Such creation and detection of the electron beam path differs from the earlier works where the gun emitted electron beam deviation in ultrahigh vacuum was detected on a collector-grid/fluorescent screen. In the present experiment, large beam deviations were observed. Later investigation of the experimental set-up reveals existence of a possible source of radial electric field in between the source and the vacuum vessel which are separately grounded. Thus, to understand the observed phenomena, experiments are numerically modeled with deviated TF coil set, PF coil set and the electron source location. A particle tracing code is used to follow the electron path in the magnetic field generated by the coil set of interest. Simulation results suggest that the large deviation corresponds to the E×B drifts and not due to the large field errors. Toroidally averaged field errors of the SST-1 TF coils at toroidal field of B0?=?15 kG are negligibly small ~B0?×?10^-6 or less, which should not adversely affect the plasma performance.展开更多
Steady State Tokamak （SST-1） vacuum vessel baking as well as baking of the first wall components of SST-1 are essential to plasma physics experiments. Under a refurbishment spectrum of SST-1, the nitrogen gas heatin...Steady State Tokamak （SST-1） vacuum vessel baking as well as baking of the first wall components of SST-1 are essential to plasma physics experiments. Under a refurbishment spectrum of SST-1, the nitrogen gas heating and supply system has been fully refurbished. The SST-1 vacuum vessel consists of ultra-high vacuum （UHV） compatible eight modules and eight sectors. Rectangular baking channels are embedded on each of them. Similarly, the SST-1 plasma facing components （PFC） are comprised of modular graphite diverters and movable graphite based limiters. The nitrogen gas heating and supply system would bake the plasma facing components at 350 ~C and the SST-1 vacuum vessel at 150 ~C over an extended duration so as to remove water vapour and other absorbed gases. An efficient PLC based baking facility has been developed and implemented for monitoring and control purposes. This paper presents functional and operational aspects of a SST-1 nitrogen gas heating and supply system. Some of the experimental results obtained during the baking of SST-1 vacuum modules and sectors are also presented here.展开更多
Refurbishment of steady state tokamak （SST-1） primarily focused at addressing the issues and bottle-necks involving various subsystems of SST-1 as observed during earlier commis- sioning attempts, have progressed si...Refurbishment of steady state tokamak （SST-1） primarily focused at addressing the issues and bottle-necks involving various subsystems of SST-1 as observed during earlier commis- sioning attempts, have progressed significantly. Under the refurbishment spectrum, all joints in the superconducting magnet system have been re-fabricated as low DC leak tight joint resistances, all toroidal field （TF） magnets have been equipped with 5 K radiation shields on the inner side and successfully tested for their rated parameters in cold under nominal currents, all vessel sectors and modules have been baked and tested under representative conditions, supporting helium and ni- trogen cryogenic facilities have been made 〉 99% reliable in various envisaged operating scenarios of SST-1. The reassemblies of the critical subsystems of the SST-1 machine shell have progressed aggressively and are nearing completion. Auxiliaries such as the baking facility for the vacuum vessel and first wall components, current leads assembly distributions, synchronized timing sys- tem, reliable data acquisition and plasma control systems as well as essential diagnostics have also been readied towards the first plasma. A detailed engineering validation of the assembled SST-1 machine shell including field error measurements has been planned prior to first plasma attempts.展开更多
文摘Long pulse （of the order of 1000 s or more） SST-1 tokamak experiments demand a data acquisition system that is capable of acquiring data from various diagnostics channels without losing useful data （and hence physics information） while avoiding unnecessary generation of a large volume data. SST-1 Phase-1 tokamak operation has been envisaged with data acquisition of several essential diagnostics channels. These channels demand data acquisition at a sampling rate ranging from 1 kilo samples per second （KSPS） to 1 mega samples per second （MSPS）. Considering the technical characteristics and requirements of the diagnostics, a data acquisition system based on PXI and CAMAC has been developed for SST-1 plasma diagnostics. Both these data acquisition systems are scalable. Present data acquisition needs involving slow plasma diagnostics are catered by the PXI based data acquisition system. On the other hand, CAMAC data acquisition hardware meets all requirements of the SST-1 Phase-1 fast plasma diagnostics channels. A graphical user interface for both data acquisition systems （PXI and CAMAC） has been developed using LabVIEW application development software. The collected data on the local hard disk are directly streaming to the central server through a dedicated network for post-shot data analysis. This paper describes the development and integration of the data acquisition system for SST-1 Phase-1 plasma diagnostics. The integrated testing of the developed data acquisition system has been performed using SST-1 central control and diagnostics signal conditioning units. In the absence of plasma shots, the integrated testing of the data acquisition system for the initial diagnostics of SST-1 Phase-1 operation has been performed with simulated physical signals. The primary engineering objective of this integrated testing is to validate the performance of the developed data acquisition system under simulated conditions close to that of actual tokamak operation. The data acquisition is synchronized with a clock and trigger provided by the central timing system.
文摘In contrast to the earlier experiments conducted in other machines, here, in SST-1 the error field measurement experiment is performed with a filled gas pressure ~8×10^-4 mbar which helped to create a luminescent toroidal beam of electron path originated due to impact excitation and guided by the toroidal magnetic field. Beam path deviations are observed and recorded from radial and top ports using visible range cameras. Such creation and detection of the electron beam path differs from the earlier works where the gun emitted electron beam deviation in ultrahigh vacuum was detected on a collector-grid/fluorescent screen. In the present experiment, large beam deviations were observed. Later investigation of the experimental set-up reveals existence of a possible source of radial electric field in between the source and the vacuum vessel which are separately grounded. Thus, to understand the observed phenomena, experiments are numerically modeled with deviated TF coil set, PF coil set and the electron source location. A particle tracing code is used to follow the electron path in the magnetic field generated by the coil set of interest. Simulation results suggest that the large deviation corresponds to the E×B drifts and not due to the large field errors. Toroidally averaged field errors of the SST-1 TF coils at toroidal field of B0?=?15 kG are negligibly small ~B0?×?10^-6 or less, which should not adversely affect the plasma performance.
文摘Steady State Tokamak （SST-1） vacuum vessel baking as well as baking of the first wall components of SST-1 are essential to plasma physics experiments. Under a refurbishment spectrum of SST-1, the nitrogen gas heating and supply system has been fully refurbished. The SST-1 vacuum vessel consists of ultra-high vacuum （UHV） compatible eight modules and eight sectors. Rectangular baking channels are embedded on each of them. Similarly, the SST-1 plasma facing components （PFC） are comprised of modular graphite diverters and movable graphite based limiters. The nitrogen gas heating and supply system would bake the plasma facing components at 350 ~C and the SST-1 vacuum vessel at 150 ~C over an extended duration so as to remove water vapour and other absorbed gases. An efficient PLC based baking facility has been developed and implemented for monitoring and control purposes. This paper presents functional and operational aspects of a SST-1 nitrogen gas heating and supply system. Some of the experimental results obtained during the baking of SST-1 vacuum modules and sectors are also presented here.
文摘Refurbishment of steady state tokamak （SST-1） primarily focused at addressing the issues and bottle-necks involving various subsystems of SST-1 as observed during earlier commis- sioning attempts, have progressed significantly. Under the refurbishment spectrum, all joints in the superconducting magnet system have been re-fabricated as low DC leak tight joint resistances, all toroidal field （TF） magnets have been equipped with 5 K radiation shields on the inner side and successfully tested for their rated parameters in cold under nominal currents, all vessel sectors and modules have been baked and tested under representative conditions, supporting helium and ni- trogen cryogenic facilities have been made 〉 99% reliable in various envisaged operating scenarios of SST-1. The reassemblies of the critical subsystems of the SST-1 machine shell have progressed aggressively and are nearing completion. Auxiliaries such as the baking facility for the vacuum vessel and first wall components, current leads assembly distributions, synchronized timing sys- tem, reliable data acquisition and plasma control systems as well as essential diagnostics have also been readied towards the first plasma. A detailed engineering validation of the assembled SST-1 machine shell including field error measurements has been planned prior to first plasma attempts.
