Pterodontic acid(PA)has been isolated from Laggera pterodonta,a Chinese herbal medicine,and shown to possess antibacterial activity in vitro.To facilitate its preclinical development,the interaction between PA and bov...Pterodontic acid(PA)has been isolated from Laggera pterodonta,a Chinese herbal medicine,and shown to possess antibacterial activity in vitro.To facilitate its preclinical development,the interaction between PA and bovine serum albumin(BSA)was studied using a fluorescence quenching technique,ultraviolet–visible spectrophotometry and dynamic light scattering(DLS).At temperatures of 297 K and 310 K and an excitation wavelength of 282 nm,the fluorescence intensity of BSA decreased significantly with increasing concentration of PA attributed to the formation of a PA–BSA complex.The apparent binding constant,number of binding sites and corresponding thermodynamic parameters were calculated and the main intermolecular attraction shown to result from hydrogen bonding and van der Waals forces.Synchronous fluorescence spectrometry revealed that the binding site in the complex approached the microenvironment of Trp and three-dimensional fluorescence spectroscopy showed the binding induced conformational changes in BSA.Using DLS,increasing PA concentration was shown to cause a gradual increase in hydrodynamic diameter and significant aggregation of the complex.展开更多
本文叙述了新建立的磁场效应(Magnetic Field Effects,简称MFE_s)-偏振-共振同步荧光法。利用偏振技术抑制掉溶剂散射光的99％,利用MFE_s抑制溶剂98％的散射光波动。将偏振、MFE_s技术与共振同步荧光法结合为一体时,则大大改善Δλ=0的...本文叙述了新建立的磁场效应(Magnetic Field Effects,简称MFE_s)-偏振-共振同步荧光法。利用偏振技术抑制掉溶剂散射光的99％,利用MFE_s抑制溶剂98％的散射光波动。将偏振、MFE_s技术与共振同步荧光法结合为一体时,则大大改善Δλ=0的共振同步荧光法的检测灵敏度。如蒽、苝舵同时测定时,其检测限分别为0.068ng/ml、0.015ng/ml。优于一般的Δλ值较小(0～5nm)的同步荧光法和偏振-同步荧光法。展开更多
Synchronous fluorometry can cause a band-narrowing effect to improving the fluorometric selectivity (Fig. 1). However, since the △λ value selected is usually small (generally about 0—5 nm) in synchronous scanning, ...Synchronous fluorometry can cause a band-narrowing effect to improving the fluorometric selectivity (Fig. 1). However, since the △λ value selected is usually small (generally about 0—5 nm) in synchronous scanning, the interference of solvents scattering light (mainly Rayleigh scattering light) is so serious that the sensitivity and the detection limit are harmed greatly.展开更多
A Thomson scattering diagnostic system is under construction at the Joint Texas Experimental Tokamak（J-TEXT）. A 1064 nm Nd：YAG laser with 50 Hz repetition rate is used as the laser source. We have used a software f...A Thomson scattering diagnostic system is under construction at the Joint Texas Experimental Tokamak（J-TEXT）. A 1064 nm Nd：YAG laser with 50 Hz repetition rate is used as the laser source. We have used a software for careful and precise control of the laser through serial communication. A time sequence operating system has been developed to synchronize the laser control and data acquisition system with the central control system（CSS）. The system operates commands from the CSS of J-TEXT and generates triggers for the laser and data acquisition system in the proper sequence. It also measures an asynchronous time value that is needed for accurate time stamping. All functions are served by a field-programmable gate array development platform that is suitable for high-speed data and signal processing applications.Several embedded peripherals, including Ethernet and USB 2.0, provide communication with the CSS and the server.展开更多
This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semic...This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semiconductor laser that is numerically modeled by employing laser rate equations. These two channels were multiplexed and then propagated through single mode optical fiber （SMF） of 80kin length with dispersion compensating fiber of 16 km length. Erbium doped fiber amplifier （EDFA） was used to compensate the power losses in the SMF. In lhis paper, we investigated the effects of polarization mode dispersion （PMD） and nonlinearities especially stimulated Raman scattering （SRS） on 2 channel DWDM chaotic communication system by varying the length of the SMF and value of differential group delay （DGD）.展开更多
基金supported by the Special Fund for Basic Scientific Research of Central Colleges,South-Central University for Nationalities(No.CZQ11013)by the Wuhan Science and Technology Bureau(No.201051730558).
文摘Pterodontic acid(PA)has been isolated from Laggera pterodonta,a Chinese herbal medicine,and shown to possess antibacterial activity in vitro.To facilitate its preclinical development,the interaction between PA and bovine serum albumin(BSA)was studied using a fluorescence quenching technique,ultraviolet–visible spectrophotometry and dynamic light scattering(DLS).At temperatures of 297 K and 310 K and an excitation wavelength of 282 nm,the fluorescence intensity of BSA decreased significantly with increasing concentration of PA attributed to the formation of a PA–BSA complex.The apparent binding constant,number of binding sites and corresponding thermodynamic parameters were calculated and the main intermolecular attraction shown to result from hydrogen bonding and van der Waals forces.Synchronous fluorescence spectrometry revealed that the binding site in the complex approached the microenvironment of Trp and three-dimensional fluorescence spectroscopy showed the binding induced conformational changes in BSA.Using DLS,increasing PA concentration was shown to cause a gradual increase in hydrodynamic diameter and significant aggregation of the complex.
文摘本文叙述了新建立的磁场效应(Magnetic Field Effects,简称MFE_s)-偏振-共振同步荧光法。利用偏振技术抑制掉溶剂散射光的99％,利用MFE_s抑制溶剂98％的散射光波动。将偏振、MFE_s技术与共振同步荧光法结合为一体时,则大大改善Δλ=0的共振同步荧光法的检测灵敏度。如蒽、苝舵同时测定时,其检测限分别为0.068ng/ml、0.015ng/ml。优于一般的Δλ值较小(0～5nm)的同步荧光法和偏振-同步荧光法。
文摘Synchronous fluorometry can cause a band-narrowing effect to improving the fluorometric selectivity (Fig. 1). However, since the △λ value selected is usually small (generally about 0—5 nm) in synchronous scanning, the interference of solvents scattering light (mainly Rayleigh scattering light) is so serious that the sensitivity and the detection limit are harmed greatly.
基金supported by the National Magnetic Confinement Fusion Science Program of China under Contract No.2015GB111001by National Natural Science Foundation of China(Grant No.11575067)
文摘A Thomson scattering diagnostic system is under construction at the Joint Texas Experimental Tokamak（J-TEXT）. A 1064 nm Nd：YAG laser with 50 Hz repetition rate is used as the laser source. We have used a software for careful and precise control of the laser through serial communication. A time sequence operating system has been developed to synchronize the laser control and data acquisition system with the central control system（CSS）. The system operates commands from the CSS of J-TEXT and generates triggers for the laser and data acquisition system in the proper sequence. It also measures an asynchronous time value that is needed for accurate time stamping. All functions are served by a field-programmable gate array development platform that is suitable for high-speed data and signal processing applications.Several embedded peripherals, including Ethernet and USB 2.0, provide communication with the CSS and the server.
文摘This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semiconductor laser that is numerically modeled by employing laser rate equations. These two channels were multiplexed and then propagated through single mode optical fiber （SMF） of 80kin length with dispersion compensating fiber of 16 km length. Erbium doped fiber amplifier （EDFA） was used to compensate the power losses in the SMF. In lhis paper, we investigated the effects of polarization mode dispersion （PMD） and nonlinearities especially stimulated Raman scattering （SRS） on 2 channel DWDM chaotic communication system by varying the length of the SMF and value of differential group delay （DGD）.
