As important components of air pollutant,volatile organic compounds(VOCs)can cause great harm to environment and human body.The concentration change of VOCs should be focused on in real-time environment monitoring sys...As important components of air pollutant,volatile organic compounds(VOCs)can cause great harm to environment and human body.The concentration change of VOCs should be focused on in real-time environment monitoring system.In order to solve the problem of wavelength redundancy in full spectrum partial least squares(PLS)modeling for VOCs concentration analysis,a new method based on improved interval PLS(iPLS)integrated with Monte-Carlo sampling,called iPLS-MC method,was proposed to select optimal characteristic wavelengths of VOCs spectra.This method uses iPLS modeling to preselect the characteristic wavebands of the spectra and generates random wavelength combinations from the selected wavebands by Monte-Carlo sampling.The wavelength combination with the best prediction result in regression model is selected as the characteristic wavelengths of the spectrum.Different wavelength selection methods were built,respectively,on Fourier transform infrared(FTIR)spectra of ethylene and ethanol gas at different concentrations obtained in the laboratory.When the interval number of iPLS model is set to 30 and the Monte-Carlo sampling runs 1000 times,the characteristic wavelengths selected by iPLS-MC method can reduce from 8916 to 10,which occupies only 0.22%of the full spectrum wavelengths.While the RMSECV and correlation coefficient(Rc)for ethylene are 0.2977 and 0.9999 ppm,and those for ethanol gas are 0.2977 ppm and 0.9999.The experimental results show that the iPLS-MC method can select the optimal characteristic wavelengths of VOCs FTIR spectra stably and effectively,and the prediction performance of the regression model can be significantly improved and simplified by using characteristic wavelengths.展开更多
The unfolding of proteins during denaturation by guanidine or urea has been extensively studied. However, the methods hitherto employed usually provide only a limited amount of information on gross changes of such mol...The unfolding of proteins during denaturation by guanidine or urea has been extensively studied. However, the methods hitherto employed usually provide only a limited amount of information on gross changes of such molecular properties as shape, size, or the exposure of buried aromatic residues. CD studies are hampered by high absorption of the denaturants commonly employed in the far ultraviolet region. Recent development in Fourier展开更多
The Fourier transform far infrared spectra of oxalate hydrates of whole rare-earth series except Pm and Sc are investigated in the range of 100-400 cm<sup>-1</sup>. The assignment of vibrational frequencie...The Fourier transform far infrared spectra of oxalate hydrates of whole rare-earth series except Pm and Sc are investigated in the range of 100-400 cm<sup>-1</sup>. The assignment of vibrational frequencies is made on the basis of normal coordinate analysis using our NORVIB program. The model used for the hghter elements of the lanthanide series （La to Eu） is based on the crystal structure of Nd<sub>2</sub>（C<sub>2</sub>O<sub>4</sub>）<sub>3</sub>. 10H<sub>2</sub>O, in which each lanthanide ion is surrounded by nine O atoms, six from three oxalate ions and three from Water molecules.The model adopted for the heavier elements of the lanthanide series （Gd to Lu） and Ytterbium is based on the crystal structure of Yb<sub>2</sub>（C<sub>2</sub>O<sub>4</sub>）<sub>3</sub>· 6H<sub>2</sub>O, in which each ion is surrounded by eight atoms, six from three oxalate ions and two from water molecules. The variation of the metal-ligand frequencies and force constants with the atomic numbers of lanthanides is plotted and discussed.展开更多
The infrared absorbance peaks at 2 852.4, 2 924.3, 2963.0 and 3 034.9 cm-1 have been observed in diamond films made by the direct current arc discharge plasma chemical vapor deposition. Three former absorbance peaks h...The infrared absorbance peaks at 2 852.4, 2 924.3, 2963.0 and 3 034.9 cm-1 have been observed in diamond films made by the direct current arc discharge plasma chemical vapor deposition. Three former absorbance peaks have been assigned to C-H stretching in SP3 configuration, 3 034.9 cm-1 has been assigned to C-H stretching in SP2 configuration. The展开更多
基金supported by National Key Scientific Instrument and Equipment Development Project of China,Grant Nos.2013YQ220643the National 863 Program of China,Grant Nos.2014AA06A503.
文摘As important components of air pollutant,volatile organic compounds(VOCs)can cause great harm to environment and human body.The concentration change of VOCs should be focused on in real-time environment monitoring system.In order to solve the problem of wavelength redundancy in full spectrum partial least squares(PLS)modeling for VOCs concentration analysis,a new method based on improved interval PLS(iPLS)integrated with Monte-Carlo sampling,called iPLS-MC method,was proposed to select optimal characteristic wavelengths of VOCs spectra.This method uses iPLS modeling to preselect the characteristic wavebands of the spectra and generates random wavelength combinations from the selected wavebands by Monte-Carlo sampling.The wavelength combination with the best prediction result in regression model is selected as the characteristic wavelengths of the spectrum.Different wavelength selection methods were built,respectively,on Fourier transform infrared(FTIR)spectra of ethylene and ethanol gas at different concentrations obtained in the laboratory.When the interval number of iPLS model is set to 30 and the Monte-Carlo sampling runs 1000 times,the characteristic wavelengths selected by iPLS-MC method can reduce from 8916 to 10,which occupies only 0.22%of the full spectrum wavelengths.While the RMSECV and correlation coefficient(Rc)for ethylene are 0.2977 and 0.9999 ppm,and those for ethanol gas are 0.2977 ppm and 0.9999.The experimental results show that the iPLS-MC method can select the optimal characteristic wavelengths of VOCs FTIR spectra stably and effectively,and the prediction performance of the regression model can be significantly improved and simplified by using characteristic wavelengths.
基金Project supported in part by the National Natural Science Foundation of China.
文摘The unfolding of proteins during denaturation by guanidine or urea has been extensively studied. However, the methods hitherto employed usually provide only a limited amount of information on gross changes of such molecular properties as shape, size, or the exposure of buried aromatic residues. CD studies are hampered by high absorption of the denaturants commonly employed in the far ultraviolet region. Recent development in Fourier
文摘The Fourier transform far infrared spectra of oxalate hydrates of whole rare-earth series except Pm and Sc are investigated in the range of 100-400 cm<sup>-1</sup>. The assignment of vibrational frequencies is made on the basis of normal coordinate analysis using our NORVIB program. The model used for the hghter elements of the lanthanide series （La to Eu） is based on the crystal structure of Nd<sub>2</sub>（C<sub>2</sub>O<sub>4</sub>）<sub>3</sub>. 10H<sub>2</sub>O, in which each lanthanide ion is surrounded by nine O atoms, six from three oxalate ions and three from Water molecules.The model adopted for the heavier elements of the lanthanide series （Gd to Lu） and Ytterbium is based on the crystal structure of Yb<sub>2</sub>（C<sub>2</sub>O<sub>4</sub>）<sub>3</sub>· 6H<sub>2</sub>O, in which each ion is surrounded by eight atoms, six from three oxalate ions and two from water molecules. The variation of the metal-ligand frequencies and force constants with the atomic numbers of lanthanides is plotted and discussed.
文摘The infrared absorbance peaks at 2 852.4, 2 924.3, 2963.0 and 3 034.9 cm-1 have been observed in diamond films made by the direct current arc discharge plasma chemical vapor deposition. Three former absorbance peaks have been assigned to C-H stretching in SP3 configuration, 3 034.9 cm-1 has been assigned to C-H stretching in SP2 configuration. The
