A new approach of generating transient chaos from two-dimensional(2D) continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes pl...A new approach of generating transient chaos from two-dimensional(2D) continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes place by switching between three 2D systems.Basic dynamic behavior of the systems is investigated.Numerical examples illustrate the validity of the results.展开更多
High performance liquid chromatography with column switching has been developed for the determination of lansoprazole in plasma. The plasma samples were injected onto a pretreatment column packed with LiChromprep RP2 ...High performance liquid chromatography with column switching has been developed for the determination of lansoprazole in plasma. The plasma samples were injected onto a pretreatment column packed with LiChromprep RP2 (25~40 mm) after simple dilution with distilled water. Distilled water was used to wash out protein and other polar components in plasma. After switching, the concentrated lansoprazole was eluted in the backflush mode onto a Shimpack CLC ODS column with methanol 0 2 mol·L 1 ammonium acetate (65:35) as mobile phase. Purge solutions were used for clean up and for regenerating the pretreatment column. The method showed good precision and recovery. The detection limit was 0 005 mg·L -1 plasma. The RSD’s (intra and interday) were less than 2 5% and 5 3% respectively. The method has been successfully used to determine pharmacokinetics of lansoprazole in Chinese volunteers.展开更多
A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates (PMS) and petroleum disulfonates (PDS) in crude oil that was simply diluted wi...A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates (PMS) and petroleum disulfonates (PDS) in crude oil that was simply diluted with the dichloromethane/methanol (60/40). The high performance liquid chromatography (HPLC) system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.展开更多
[Objective] The paper was to establish the method for quantitative analysis of glyphosate herbicide and identification of salt type. [Method] Using ion chromatographic column switching method,cations( sodion,ammonium ...[Objective] The paper was to establish the method for quantitative analysis of glyphosate herbicide and identification of salt type. [Method] Using ion chromatographic column switching method,cations( sodion,ammonium ion,potassium ion,dimethonium ion and isopropylamine ion) and glyphosate anion in glyphosate salt were determined with Thermo IonP ac SCS1 cation exchange column and Thermo IonP ac AS14 anion exchange column,and external standard method was used for quantification. [Result] Various components showed good linear relationship within the linearity range,and the correlation coefficient r was greater than 0. 999; the relative standard deviation of retention time and peak area were less than 0. 13% and 1. 22%,respectively; the recovery was 98. 22%-99. 97%.[Conclusion] The method is precise,accurate and simple,and can be used to determine the active ingredients of glyphosate herbicide.展开更多
Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in...Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in laboratories, but is unsuitable for measurement of minor constituents, except when using the column-switching method. Thus, we aimed to establish a simple, inexpensive and sensitive method based on HPLC/UV with column switching for measuring nicotine and cotinine in hair. First, we compared the presence and absence of a column selection unit. We then measured amounts of nicotine and cotinine in hair samples collected from the general population, and compared both the corresponding levels and the detection limits with those in previous studies. Finally, initial and running costs of HPLC/UV were compared with other analytical methods. As one of the results, the areas of nicotine and cotinine measured by HPLC/UV with column-switching method were 12.9 and 16.9 times greater, respectively, than those without the column-switching method. The amount of nicotine and cotinine in hair was significantly correlated to number of cigarettes smoked per day (r = 0.228, p = 0.040). In addition, the HPLC/UV method showed similar sensitivity and detection limit (nicotine, 0.10 ng/mg;cotinine, 0.08 ng/mg) as reported in previous studies. The cost of the HPLC/UV method is lower than that of other analytical methods. We were able to establish a low-cost method with good sensitivity for measuring nicotine and cotinine in hair. The HPLC/UV with a column-switching method will be useful as a first step in screening surveys in order to better understand the effects of smoking exposure.展开更多
Facing the growing data storage and computing demands, a high accessing speed memory with low power and non- volatile character is urgently needed. Resistive access random memory with 4F2 cell size, switching in sub-n...Facing the growing data storage and computing demands, a high accessing speed memory with low power and non- volatile character is urgently needed. Resistive access random memory with 4F2 cell size, switching in sub-nanosecond, cycling endurances of over 1012 cycles, and information retention exceeding 10 years, is considered as promising next- generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory.展开更多
Egg white protein bonded columns were developed for HPLC. These columns can be used under aqueous mobile phase and separate various kinds of drug enantiomers. Hyphenated techniques using protein bonded columns with LC...Egg white protein bonded columns were developed for HPLC. These columns can be used under aqueous mobile phase and separate various kinds of drug enantiomers. Hyphenated techniques using protein bonded columns with LC/MS and/or column switching have been recognized as integral methods in pharmaceutical research to analyze drug enantiomers. Therefore, these methods are very useful for research fields of pharmacokinetics and pharmacology.展开更多
An ion chromatography method has been proposed for the determination of three common inorganic anions(chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion...An ion chromatography method has been proposed for the determination of three common inorganic anions(chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits(S/N = 3) were in the range of 0.10-0.68μg/L.The relative standard deviations(RSDs) of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.展开更多
基金Project supported by the Natural Science Foundation of Liaoning Province,China (Grant No. 201102181)
文摘A new approach of generating transient chaos from two-dimensional(2D) continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes place by switching between three 2D systems.Basic dynamic behavior of the systems is investigated.Numerical examples illustrate the validity of the results.
文摘High performance liquid chromatography with column switching has been developed for the determination of lansoprazole in plasma. The plasma samples were injected onto a pretreatment column packed with LiChromprep RP2 (25~40 mm) after simple dilution with distilled water. Distilled water was used to wash out protein and other polar components in plasma. After switching, the concentrated lansoprazole was eluted in the backflush mode onto a Shimpack CLC ODS column with methanol 0 2 mol·L 1 ammonium acetate (65:35) as mobile phase. Purge solutions were used for clean up and for regenerating the pretreatment column. The method showed good precision and recovery. The detection limit was 0 005 mg·L -1 plasma. The RSD’s (intra and interday) were less than 2 5% and 5 3% respectively. The method has been successfully used to determine pharmacokinetics of lansoprazole in Chinese volunteers.
基金the National Nature Science Foundation of China(No.20675085)the support from the Program of the Light in China's Western Region(2003)the Province Nature Science Foundation of Gansu(No.3ZS041-A25-23).
文摘A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates (PMS) and petroleum disulfonates (PDS) in crude oil that was simply diluted with the dichloromethane/methanol (60/40). The high performance liquid chromatography (HPLC) system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.
基金Supported by Science and Technology Project of Zhejiang Province(2016C37034)
文摘[Objective] The paper was to establish the method for quantitative analysis of glyphosate herbicide and identification of salt type. [Method] Using ion chromatographic column switching method,cations( sodion,ammonium ion,potassium ion,dimethonium ion and isopropylamine ion) and glyphosate anion in glyphosate salt were determined with Thermo IonP ac SCS1 cation exchange column and Thermo IonP ac AS14 anion exchange column,and external standard method was used for quantification. [Result] Various components showed good linear relationship within the linearity range,and the correlation coefficient r was greater than 0. 999; the relative standard deviation of retention time and peak area were less than 0. 13% and 1. 22%,respectively; the recovery was 98. 22%-99. 97%.[Conclusion] The method is precise,accurate and simple,and can be used to determine the active ingredients of glyphosate herbicide.
文摘Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in laboratories, but is unsuitable for measurement of minor constituents, except when using the column-switching method. Thus, we aimed to establish a simple, inexpensive and sensitive method based on HPLC/UV with column switching for measuring nicotine and cotinine in hair. First, we compared the presence and absence of a column selection unit. We then measured amounts of nicotine and cotinine in hair samples collected from the general population, and compared both the corresponding levels and the detection limits with those in previous studies. Finally, initial and running costs of HPLC/UV were compared with other analytical methods. As one of the results, the areas of nicotine and cotinine measured by HPLC/UV with column-switching method were 12.9 and 16.9 times greater, respectively, than those without the column-switching method. The amount of nicotine and cotinine in hair was significantly correlated to number of cigarettes smoked per day (r = 0.228, p = 0.040). In addition, the HPLC/UV method showed similar sensitivity and detection limit (nicotine, 0.10 ng/mg;cotinine, 0.08 ng/mg) as reported in previous studies. The cost of the HPLC/UV method is lower than that of other analytical methods. We were able to establish a low-cost method with good sensitivity for measuring nicotine and cotinine in hair. The HPLC/UV with a column-switching method will be useful as a first step in screening surveys in order to better understand the effects of smoking exposure.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61376093 and 61622401)the National Key Research and Development Program of China(Grant No.2016YFA0203900)
文摘Facing the growing data storage and computing demands, a high accessing speed memory with low power and non- volatile character is urgently needed. Resistive access random memory with 4F2 cell size, switching in sub-nanosecond, cycling endurances of over 1012 cycles, and information retention exceeding 10 years, is considered as promising next- generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory.
文摘Egg white protein bonded columns were developed for HPLC. These columns can be used under aqueous mobile phase and separate various kinds of drug enantiomers. Hyphenated techniques using protein bonded columns with LC/MS and/or column switching have been recognized as integral methods in pharmaceutical research to analyze drug enantiomers. Therefore, these methods are very useful for research fields of pharmacokinetics and pharmacology.
基金supported by the National Natural Science Foundation of China(Nos.20775070 and J0830413)Zhejiang Provincial Natural Science Foundation of China(Nos.R4080124 and J20091495)
文摘An ion chromatography method has been proposed for the determination of three common inorganic anions(chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits(S/N = 3) were in the range of 0.10-0.68μg/L.The relative standard deviations(RSDs) of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.