Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identi...Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identification, and time-resolved techniques. In this study, we employ several key technical procedures and successfully develop a highly sensitive femtosecond time-resolved sum frequency generation vibrational spectroscopy （SFG-VS） system. This system is able to measure the spectra with two polarization combinations （ssp and ppp, or psp and ssp） simultaneously. It takes less than several seconds to collect one spectrum. To the best of our knowledge, it is the fastest speed of collecting SFG spectra reported by now. Using the time-resolved measurement, ultrafast vibrational dynamics of the N-H mode of α-helical peptide at water interface is determined. It is found that the membrane environment does not affect the N-H vibrational relaxation dynamics. It is expected that the time-resolved SFG system will play a vital role in the deep understanding of the dynamics and interaction of the complex molecules at surface and interface. Our method may also provide an important technical proposal for the people who plan to develop time-resolved SFG systems with simultaneous measurement of multiple polarization combinations.展开更多
An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this stud...An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this study. Ten marker compounds were simultaneously quantified, including 5-caffeoylquinic acid （5-CQA）, 3-caffeoylquinic acid （3-CQA）, 4-caffeoylquinic acid （4-CQA）, 1-caffeoylquinic acid （1-CQA）, 3,5-dicaffeoylquinic acid （3,5-diCQA）, 4,5-dicaffeoylquinic acid （4,5-diCQA）, 3,4-dicaffeoylquinic acid （3,4-diCQA）, astragalin, kaempferol-3,7-di-O-glucoside and （±）eriodictyol-7-O-β-D-glucuronide. Chromatography was performed on a Kromasil 100-2.5C18 （100 mm×2.1 mm, 2.5 μm） C18 column with gradient elution. The mobile phases consisted of 0.1% formic acid/water （A） and 0.1% formic acid/methanol （B）. The detection wavelength was set at 326 nm and the flow rate was 0.4 mL/min. Ten components were separated well with good linearity （r2〉0.9998）, precision, repeatability, stability. The recovery was in the range of 99.08%-102.77%. The results showed that the content determination using RP-UFLC-DAD fingerprint technique provides an efficient, sensitive, accurate and rapid analytical method for quality assessment ofP. petiolosa （Christ） Ching. Cluster analysis and principal components analysis were successfully applied to analyze 20 samples, the results revealed that the method was efficient and authentic to distinguish producing areas and the source of P. petiolosa （Christ） Ching. Keywords： Pyrrosiapetiolosa （Christ） Ching, Caffeoylquinic acids, Flavonoids, Multicomponent determination, UFLC展开更多
文摘Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identification, and time-resolved techniques. In this study, we employ several key technical procedures and successfully develop a highly sensitive femtosecond time-resolved sum frequency generation vibrational spectroscopy （SFG-VS） system. This system is able to measure the spectra with two polarization combinations （ssp and ppp, or psp and ssp） simultaneously. It takes less than several seconds to collect one spectrum. To the best of our knowledge, it is the fastest speed of collecting SFG spectra reported by now. Using the time-resolved measurement, ultrafast vibrational dynamics of the N-H mode of α-helical peptide at water interface is determined. It is found that the membrane environment does not affect the N-H vibrational relaxation dynamics. It is expected that the time-resolved SFG system will play a vital role in the deep understanding of the dynamics and interaction of the complex molecules at surface and interface. Our method may also provide an important technical proposal for the people who plan to develop time-resolved SFG systems with simultaneous measurement of multiple polarization combinations.
基金Study of Safety Testing Techniques and Standards on New Traditional Chinese Drug(National Key Science and Technology Special Projects,Grant No.2014ZX09304307-001-001)
文摘An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this study. Ten marker compounds were simultaneously quantified, including 5-caffeoylquinic acid （5-CQA）, 3-caffeoylquinic acid （3-CQA）, 4-caffeoylquinic acid （4-CQA）, 1-caffeoylquinic acid （1-CQA）, 3,5-dicaffeoylquinic acid （3,5-diCQA）, 4,5-dicaffeoylquinic acid （4,5-diCQA）, 3,4-dicaffeoylquinic acid （3,4-diCQA）, astragalin, kaempferol-3,7-di-O-glucoside and （±）eriodictyol-7-O-β-D-glucuronide. Chromatography was performed on a Kromasil 100-2.5C18 （100 mm×2.1 mm, 2.5 μm） C18 column with gradient elution. The mobile phases consisted of 0.1% formic acid/water （A） and 0.1% formic acid/methanol （B）. The detection wavelength was set at 326 nm and the flow rate was 0.4 mL/min. Ten components were separated well with good linearity （r2〉0.9998）, precision, repeatability, stability. The recovery was in the range of 99.08%-102.77%. The results showed that the content determination using RP-UFLC-DAD fingerprint technique provides an efficient, sensitive, accurate and rapid analytical method for quality assessment ofP. petiolosa （Christ） Ching. Cluster analysis and principal components analysis were successfully applied to analyze 20 samples, the results revealed that the method was efficient and authentic to distinguish producing areas and the source of P. petiolosa （Christ） Ching. Keywords： Pyrrosiapetiolosa （Christ） Ching, Caffeoylquinic acids, Flavonoids, Multicomponent determination, UFLC
