In 0.1 mol/L HCl medium, 12-tungstophosphoric（TP） acid reacted with matrine（Mat） and oxymatrine（Oxy） to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering（RRS）, seco...In 0.1 mol/L HCl medium, 12-tungstophosphoric（TP） acid reacted with matrine（Mat） and oxymatrine（Oxy） to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scattering（FDS） appeared and their intensities were enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS were located at 370, 670 and 390 nm, respectively. The in-crements of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range. Based on this, the method for the determination of matrine and oxymatrine has been established. It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result. The reaction mechanism and reasons of RRS enhancement were discussed.展开更多
In a pH=0.65―1.5 NaAc-HCl medium, methylene blue（MB） reacts with 12-tungstophosphoric acid （TPA） by virtue of electrostatic attraction and hydrophobic force to form a 3：2 ion-association complex. As a result, th...In a pH=0.65―1.5 NaAc-HCl medium, methylene blue（MB） reacts with 12-tungstophosphoric acid （TPA） by virtue of electrostatic attraction and hydrophobic force to form a 3：2 ion-association complex. As a result, the intensities of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scatte- ring（FDS） are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity（△I） are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits（3s） for MB are 2.3 ng/mL（RRS method）, 5.6 ng/mL（SOS method） and 6.4 ng/mL（FDS method）, respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5%―105.0%. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.展开更多
We consider scattering of a time harmonic incident plane wave by a convex polygon with piecewise constant impedance boundary conditions.Standard finite or boundary element methods require the number of degrees of free...We consider scattering of a time harmonic incident plane wave by a convex polygon with piecewise constant impedance boundary conditions.Standard finite or boundary element methods require the number of degrees of freedom to grow at least linearly with respect to the frequency of the incident wave in order to maintain accuracy.Extending earlier work by Chandler-Wilde and Langdon for the sound soft problem,we propose a novel Galerkin boundary element method,with the approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh with smaller elements closer to the corners of the polygon.Theoretical analysis and numerical results suggest that the number of degrees of freedom required to achieve a prescribed level of accuracy grows only logarithmically with respect to the frequency of the incident wave.展开更多
Objective:PCG represents the acoustic replay of heart sounds from the cardiac structure.To detect and analyse the different conditions of the heart,heart sound signals are essential.CVD is detected by classifiers who ...Objective:PCG represents the acoustic replay of heart sounds from the cardiac structure.To detect and analyse the different conditions of the heart,heart sound signals are essential.CVD is detected by classifiers who superficially identify the cardiac features.Abnormal sounds in systole or diastole could indicate valve stenosis or regurgitation.The presence of S3 or S4 sounds could indicate heart failure or stiffening of the heart muscle.This paper proposes a CVD detection technique using improved WST and DA classifiers.Method:The PCG was obtained from the Physionet dataset.The raw signals were pre-processed using 2D DCT.The 2D DCT was applied to a matrix containing 3000 sounds with 10000 samples.The DCT matrix was then filtered using a 20Hz–190 Hz Type II Chebyshev filter to remove the high frequency noise above 190 Hz.After filtering,the denoised PCG matrix was obtained from the DCT matrix using inverse 2D DCT.The PCG matrix was feature extracted using WST.WST produces low-frequency components by using the LPFs to filter high-frequency components.These features were then used with the DA classifier to predict the CVD.The DA classifier uses discriminant analysis pattern classification.The DA classifier learns the training PCG pattern,from WST features,and then classifies test samples as normal or abnormal.Results:The proposed method removed noise up to 99%.The 2D DCT filter provided an average noise improvement of 37.34 dB.Further tuning in filter order or attenuation level resulted in distortion of the PCG,and noise improvement declined.The DCT filter removed up to 99%of noise as per the SNR estimation.The improved WST and the DA classifier resulted in an accuracy of 99.63%.Conclusion:Comparative analysis with DNN,advocates the superiority of the proposed method.DNN classifiers provide accurate CVD classification but require a more expensive and complex GPU.The DA classifier requires only a CPU.This work demonstrated that superior CVD classification was obtained using a combination of WST features and the DA classifier with 94%accuracy.展开更多
Binding of heparin with methylene blue (MB) in pH 5.7 Britton Robinson buffer can result in a significant enhancement of frequency doubling scattering (FDS) and second order scattering (SOS). Their maximum scatterin...Binding of heparin with methylene blue (MB) in pH 5.7 Britton Robinson buffer can result in a significant enhancement of frequency doubling scattering (FDS) and second order scattering (SOS). Their maximum scattering wavelengths ( λ max ) appear at 350 nm for FDS and 700 nm for SOS, respectively. The optimum conditions of the reaction, the influencing factors and the relationship between the two scattering intensities and the concentration of heparin have been investigated. The new methods for the determination of trace amounts of heparin based on the FDS and SOS methods have been developed, which exhibit high sensitivities. The detection limits of heparin are 4.36 ng/mL for the FDS method and 3.55 ng/mL for the SOS method, respectively. Both of the methods have fairly good selectivity and were applied to the determination of heparin in sodium heparinate injection samples with satisfactory results. Moreover, the relative mechanisms have also been discussed.展开更多
The interaction between palladium(II)-chlorpromazine hydrochloride and sodium tungstate was investigated by ultravioletvisible absorption,resonance Rayleigh scattering(RRS),second-order scattering(SOS)and frequency do...The interaction between palladium(II)-chlorpromazine hydrochloride and sodium tungstate was investigated by ultravioletvisible absorption,resonance Rayleigh scattering(RRS),second-order scattering(SOS)and frequency doubling scattering (FDS)spectroscopy.In pH 5.3 Britton-Robinson(BR)buffer medium,chlorpromazine hydrochloride(CPZ)reacted with Pd(II) to form 2:1 cationic chelate,which further reacted with Na2WO4 to form a 1:1 ternary ion-association complex ([Pd(CPZ)2]·WO4).As a result,the signal intensities of RRS,SOS and FDS were enhanced greatly,and the enhancements of scattering were proportional to the CPZ concentration in a certain range.Their maximum wavelengths were located at 310 nm, 570 nm and 391 nm,respectively and the detection limits(3)were 1.6 ng/mL(RRS method),3.2 ng/mL(SOS method)and 5.6 ng/mL(FDS method).The optimum reaction conditions,the influences of coexisting substances and analytical application were mainly investigated by RRS method due to its highest sensitivity.A highly sensitive,simple,rapid and new method had been proposed to determine CPZ in the pharmaceutical form and residue of CPZ in pork.In addition,the Gibbs free energy change(△Gf)of ion-association reaction was computed by using B3LYP/3-21g*/LanL2dz method.The formation of ion-association and the reasons for the enhancement of RRS were also discussed.展开更多
基金Supported by the National Natural Science Foundation of China(No.20875078)
文摘In 0.1 mol/L HCl medium, 12-tungstophosphoric（TP） acid reacted with matrine（Mat） and oxymatrine（Oxy） to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scattering（FDS） appeared and their intensities were enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS were located at 370, 670 and 390 nm, respectively. The in-crements of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range. Based on this, the method for the determination of matrine and oxymatrine has been established. It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result. The reaction mechanism and reasons of RRS enhancement were discussed.
基金Supported by the National Natural Science Foundation of China(No.20875078)the Fund of Chongqing Municipal Key Laboratory on Luminescence and Real-Time Analysis China(No.2006CA8006)
文摘In a pH=0.65―1.5 NaAc-HCl medium, methylene blue（MB） reacts with 12-tungstophosphoric acid （TPA） by virtue of electrostatic attraction and hydrophobic force to form a 3：2 ion-association complex. As a result, the intensities of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scatte- ring（FDS） are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity（△I） are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits（3s） for MB are 2.3 ng/mL（RRS method）, 5.6 ng/mL（SOS method） and 6.4 ng/mL（FDS method）, respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5%―105.0%. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.
文摘We consider scattering of a time harmonic incident plane wave by a convex polygon with piecewise constant impedance boundary conditions.Standard finite or boundary element methods require the number of degrees of freedom to grow at least linearly with respect to the frequency of the incident wave in order to maintain accuracy.Extending earlier work by Chandler-Wilde and Langdon for the sound soft problem,we propose a novel Galerkin boundary element method,with the approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh with smaller elements closer to the corners of the polygon.Theoretical analysis and numerical results suggest that the number of degrees of freedom required to achieve a prescribed level of accuracy grows only logarithmically with respect to the frequency of the incident wave.
文摘Objective:PCG represents the acoustic replay of heart sounds from the cardiac structure.To detect and analyse the different conditions of the heart,heart sound signals are essential.CVD is detected by classifiers who superficially identify the cardiac features.Abnormal sounds in systole or diastole could indicate valve stenosis or regurgitation.The presence of S3 or S4 sounds could indicate heart failure or stiffening of the heart muscle.This paper proposes a CVD detection technique using improved WST and DA classifiers.Method:The PCG was obtained from the Physionet dataset.The raw signals were pre-processed using 2D DCT.The 2D DCT was applied to a matrix containing 3000 sounds with 10000 samples.The DCT matrix was then filtered using a 20Hz–190 Hz Type II Chebyshev filter to remove the high frequency noise above 190 Hz.After filtering,the denoised PCG matrix was obtained from the DCT matrix using inverse 2D DCT.The PCG matrix was feature extracted using WST.WST produces low-frequency components by using the LPFs to filter high-frequency components.These features were then used with the DA classifier to predict the CVD.The DA classifier uses discriminant analysis pattern classification.The DA classifier learns the training PCG pattern,from WST features,and then classifies test samples as normal or abnormal.Results:The proposed method removed noise up to 99%.The 2D DCT filter provided an average noise improvement of 37.34 dB.Further tuning in filter order or attenuation level resulted in distortion of the PCG,and noise improvement declined.The DCT filter removed up to 99%of noise as per the SNR estimation.The improved WST and the DA classifier resulted in an accuracy of 99.63%.Conclusion:Comparative analysis with DNN,advocates the superiority of the proposed method.DNN classifiers provide accurate CVD classification but require a more expensive and complex GPU.The DA classifier requires only a CPU.This work demonstrated that superior CVD classification was obtained using a combination of WST features and the DA classifier with 94%accuracy.
文摘Binding of heparin with methylene blue (MB) in pH 5.7 Britton Robinson buffer can result in a significant enhancement of frequency doubling scattering (FDS) and second order scattering (SOS). Their maximum scattering wavelengths ( λ max ) appear at 350 nm for FDS and 700 nm for SOS, respectively. The optimum conditions of the reaction, the influencing factors and the relationship between the two scattering intensities and the concentration of heparin have been investigated. The new methods for the determination of trace amounts of heparin based on the FDS and SOS methods have been developed, which exhibit high sensitivities. The detection limits of heparin are 4.36 ng/mL for the FDS method and 3.55 ng/mL for the SOS method, respectively. Both of the methods have fairly good selectivity and were applied to the determination of heparin in sodium heparinate injection samples with satisfactory results. Moreover, the relative mechanisms have also been discussed.
基金financial support for this study by the National Natural Science Foundation of China (20875078) Chongqing Municipal Key Laboratory on Luminescence and Real-Time Analysis (CSTC 2006CA8006)
文摘The interaction between palladium(II)-chlorpromazine hydrochloride and sodium tungstate was investigated by ultravioletvisible absorption,resonance Rayleigh scattering(RRS),second-order scattering(SOS)and frequency doubling scattering (FDS)spectroscopy.In pH 5.3 Britton-Robinson(BR)buffer medium,chlorpromazine hydrochloride(CPZ)reacted with Pd(II) to form 2:1 cationic chelate,which further reacted with Na2WO4 to form a 1:1 ternary ion-association complex ([Pd(CPZ)2]·WO4).As a result,the signal intensities of RRS,SOS and FDS were enhanced greatly,and the enhancements of scattering were proportional to the CPZ concentration in a certain range.Their maximum wavelengths were located at 310 nm, 570 nm and 391 nm,respectively and the detection limits(3)were 1.6 ng/mL(RRS method),3.2 ng/mL(SOS method)and 5.6 ng/mL(FDS method).The optimum reaction conditions,the influences of coexisting substances and analytical application were mainly investigated by RRS method due to its highest sensitivity.A highly sensitive,simple,rapid and new method had been proposed to determine CPZ in the pharmaceutical form and residue of CPZ in pork.In addition,the Gibbs free energy change(△Gf)of ion-association reaction was computed by using B3LYP/3-21g*/LanL2dz method.The formation of ion-association and the reasons for the enhancement of RRS were also discussed.
