The level of chemical oxygen demand(COD)is an important index to evaluate whether sewage meets the discharge requirements,so corresponding tests should be carried out before discharge.Fourier transform infrared spectr...The level of chemical oxygen demand(COD)is an important index to evaluate whether sewage meets the discharge requirements,so corresponding tests should be carried out before discharge.Fourier transform infrared spectroscopy(FTIR)and attenuated total reflectance(ATR)can detect COD in sewage effectively,which has advantages over conventional chemical analysis methods.And the selection of characteristic bands was one of the key links in the application of FTIR/ATR spectroscopy.In this work,based on the moving window partial least-squares(MWPLS)regression to select a characteristic wavelength,a method of equivalent wavelength selection was proposed combining with paired t-test equivalent concept.The results showed that the prediction effect of the selected wavelength was very close to that of the MWPLS method,while the number of wavelength points was much smaller.SEPAve,RP,Ave,SEPStd,and RP,Std which characterized the modeling effect were 26.3 mg L^-1,0.969,3.49 mg L^-1,and 0.006,respectively.The validation effect V-SEP and V-RP were 28.64 mg L^-1 and 0.960,respectively.The selected waveband was between 1809 cm^-1 and 1568 cm^-1.The method was of more reference value for the design of FTIR/ATR spectral instrument for COD detection.展开更多
为了探究基于衰减全反射傅里叶变换红外光谱(attenuated total reflection Fourier transform infrared spectroscopy,ATR-FTIR)技术实施农药沉积量原位感知的可能性,该研究以含有不同量广谱性杀菌剂啶酰菌胺沉积的棉花叶片为试验材料,...为了探究基于衰减全反射傅里叶变换红外光谱(attenuated total reflection Fourier transform infrared spectroscopy,ATR-FTIR)技术实施农药沉积量原位感知的可能性,该研究以含有不同量广谱性杀菌剂啶酰菌胺沉积的棉花叶片为试验材料,结合化学计量学分析方法开展相关探索。首先使用棉花叶片制成140例已知农药沉积量的标准样品,并采用ATR-FTIR技术获取其光谱数据;然后借助区间偏最小二乘法、相关性分析等方法筛选到272个相关性强的波长变量;最后以优化后的变量及偏最小二乘回归算法建立定量预测模型。结果表明模型的预测性能优异,预测的均方根误差为1.18μg/cm^(2),最低检测限(limit of detection,LOD)低至3.54μg/cm^(2);利用概率神经网络判别样品中农药沉积量是否大于LOD的整体准确率高达95%。该研究结果证明ATR-FTIR技术可实现农药沉积量的高精度原位检测,为其在生产中的应用提供理论依据和数据支撑。展开更多
Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existen...Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.展开更多
FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance （ATR） immersion probe was utilized to study in situ the copolymerization of butadiene （Bd） and isoprene （Ip） with neodymium-bas...FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance （ATR） immersion probe was utilized to study in situ the copolymerization of butadiene （Bd） and isoprene （Ip） with neodymium-based catalyst in hexane. The relationship between the signal intensity of monomer and its concentration was investigated. The kinetic study of copolymerization of Bd and Ip was further conducted, and the monomer reactivity ratios were determined via in situ ATR FTIR. The signal band at 1010 cm^-1 was assigned to wagging vibration of Bd and its intensity was proportional to Bd concentration （[Bd]） in the range of 0.46-3.88 mol.L^-1. The signal bands at 890 and 989 cm^-1 were assigned to wagging vibration of Ip and the signal intensity was also proportional to Ip concentration （[Ip]） in the range of 0.08-4.73 mol·L^-1 at 890 cm^-1 and 0.08-7.49 mol·L^-1 at 989 cm^-1, respectively. Thus the signal band at 1010 cm^-1 was chosen to monitor Bd concentration and bands at 989 and 890 cm^-1 to monitor Ip concentration during the copolymerization, respectively. It was demonstrated that the conversions of Bd and Ip calculated from FTIR data agreed very well with those obtained gravimetrically. The poiymerization rates were first order with respect to both [Bd] and [Ip], respectively at different polymerization temperatures. The apparent propagation activation energy for Bd and Ip could be determined to be 54.4 kJ·mol^-1 and 57.7 kJ·mol^-1, respectively. The monomer reactivity ratios were calculated to be 1.08 for Bd （rBd） and 0.48 for IP （rIp） based on FTIR data. The Bd-Ip copolymer products with random sequence could be obtained with only one glass transition temperature.展开更多
The surface density changes of the central region of the sites treated by using the CO_2 laser-based non-evaporative damage mitigation for fused silica are investigated by attenuated total reflectance-Fourier transfor...The surface density changes of the central region of the sites treated by using the CO_2 laser-based non-evaporative damage mitigation for fused silica are investigated by attenuated total reflectance-Fourier transform infrared spectroscopy（ATR-FTIR）.The ATR-FTIR peak shifts of the treated sites of fused silica are monitored to determine the changes of the corresponding density.For the quenching treated sites,the surface density is increased by（0.24±0.01）%compared with the initial density but the laser annealing by the exposure of a power ramp down after damage mitigation effectively suppresses the structural changes of treated sites,which could reduce the increase of the corresponding density to（0.08±0.01）%.The results provide sufficient evidence that the laser annealing by a power ramp down after damage mitigation has a positive effect on the control of the structural change induced by CO_2 laser-based damage mitigation.展开更多
<p> Lopinavir is an antiretroviral of the protease inhibitor class (Figure 1 <span style="display:none;" id="__kindeditor_bookmark_end_3__"></span>and Figure 2). It is used agains...<p> Lopinavir is an antiretroviral of the protease inhibitor class (Figure 1 <span style="display:none;" id="__kindeditor_bookmark_end_3__"></span>and Figure 2). It is used against HIV infections as a fixed-dose combination with another protease inhibitor, ritonavir (lopinavir/ritonavir). In the current research, the stimulated ATR-FTIR biospectroscopy of liquid sample of Lopinavir was investigated. The stimulated ATR-FTIR diffractions emitted through focusing the second harmonic laser beam Nd:YAG into the sample were recorded by Echelle spectrometer and ICCD detector. Increasing the energy of laser beam from 2.6 (mJ) to 16 (mJ) led to increase in stimulated ATR-FTIR signal but after breakdown threshold of liquid sample, further increasing energy led to the decrease in stimulating ATR-FTIR signals and for energies higher than 20 (mJ), they were disappeared. </p>展开更多
Interactions between cement clinkers and clay minerals are crucial to the much lower strength of cement-based stabilized clays than concrete or mortar.In this paper,the kaolinite-based and montmorillonite-based clays ...Interactions between cement clinkers and clay minerals are crucial to the much lower strength of cement-based stabilized clays than concrete or mortar.In this paper,the kaolinite-based and montmorillonite-based clays were respectively stabilized by tricalcium silicate(C3S)and tricalcium aluminate(C3A),and measured by the unconfined compressive strength(UCS),29Si/27Al solid state nuclear magnetic resonance(SS-NMR),Fourier transform infrared spectroscopy(FTIR),and transmission electron microscope(TEM)to probe the clinker-clay mineral interaction from macro-mechanical,mineralogical,and microstructural perspectives.The results show that C3A-stabilized samples gain strength rapidly in the first 3 d but are only 20%e60%of the strength of C3S-stabilized ones after 60 d.Microstructures reveal that montmorillonite shows better pozzolanic reactivity due to its superior Sichain and lattice substitution compared to kaolinite.This interaction domains the engineering performance of stabilized clays,benefiting the design of stabilizer referring to as the industrial by-products and clay minerals.展开更多
Fourier transform infrared attenuated total reflectance （FTIR-ATR） spectroscopy was employed to characterize rapeseed oils. The spectral features of rapeseed oils were first investigated. Spectral data was processed...Fourier transform infrared attenuated total reflectance （FTIR-ATR） spectroscopy was employed to characterize rapeseed oils. The spectral features of rapeseed oils were first investigated. Spectral data was processed using principal component analysis （PCA） and linear discriminant analysis （LDA） to discriminate the oils from three cultivars of rapeseeds. As a result, 100% discrimination accuracy was obtained by LDA. Furthermore, the applicability of FTIR-ATR spectroscopy to characterize the changes of rapeseed oils caused by thermal treatment was studied. The rapeseed oil at 60 ℃ was regularly subjected to spectral measurement, and the spectral changes induced by thermal treatment were analyzed and discussed. This study had demonstrated the good performance of FTIR-ATR spectroscopy in characterizing rapeseed oils.展开更多
基金This work was financially supported by the Natural Science Foundation of Hainan Province(417087)the Key Research and Development Program of Hainan Province(ZDYF2018007)Research Fund for Advanced Talents of Hainan University(No.kyqd1577).
文摘The level of chemical oxygen demand(COD)is an important index to evaluate whether sewage meets the discharge requirements,so corresponding tests should be carried out before discharge.Fourier transform infrared spectroscopy(FTIR)and attenuated total reflectance(ATR)can detect COD in sewage effectively,which has advantages over conventional chemical analysis methods.And the selection of characteristic bands was one of the key links in the application of FTIR/ATR spectroscopy.In this work,based on the moving window partial least-squares(MWPLS)regression to select a characteristic wavelength,a method of equivalent wavelength selection was proposed combining with paired t-test equivalent concept.The results showed that the prediction effect of the selected wavelength was very close to that of the MWPLS method,while the number of wavelength points was much smaller.SEPAve,RP,Ave,SEPStd,and RP,Std which characterized the modeling effect were 26.3 mg L^-1,0.969,3.49 mg L^-1,and 0.006,respectively.The validation effect V-SEP and V-RP were 28.64 mg L^-1 and 0.960,respectively.The selected waveband was between 1809 cm^-1 and 1568 cm^-1.The method was of more reference value for the design of FTIR/ATR spectral instrument for COD detection.
文摘为了探究基于衰减全反射傅里叶变换红外光谱(attenuated total reflection Fourier transform infrared spectroscopy,ATR-FTIR)技术实施农药沉积量原位感知的可能性,该研究以含有不同量广谱性杀菌剂啶酰菌胺沉积的棉花叶片为试验材料,结合化学计量学分析方法开展相关探索。首先使用棉花叶片制成140例已知农药沉积量的标准样品,并采用ATR-FTIR技术获取其光谱数据;然后借助区间偏最小二乘法、相关性分析等方法筛选到272个相关性强的波长变量;最后以优化后的变量及偏最小二乘回归算法建立定量预测模型。结果表明模型的预测性能优异,预测的均方根误差为1.18μg/cm^(2),最低检测限(limit of detection,LOD)低至3.54μg/cm^(2);利用概率神经网络判别样品中农药沉积量是否大于LOD的整体准确率高达95%。该研究结果证明ATR-FTIR技术可实现农药沉积量的高精度原位检测,为其在生产中的应用提供理论依据和数据支撑。
基金supported by the National Natural Science Foundation of China(41872174 and 42072189)the Program for Innovative Research Team(in Science and Technology)in the Universities of Henan Province,China(21IRTSTHN007)the Program for Innovative Research Team(in Science and Technology)of Henan Polytechnic University(T2020-4)。
文摘Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.
基金supported by the National 863 program(No.2006AA03Z552)the National Natural Science Foundation of China(No.50903003)China Petroleum Chemical Corp.(SINOPEC)and Program for Changjiang Scholars and Innovative Research Teams in Universities(IRT0706)
文摘FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance （ATR） immersion probe was utilized to study in situ the copolymerization of butadiene （Bd） and isoprene （Ip） with neodymium-based catalyst in hexane. The relationship between the signal intensity of monomer and its concentration was investigated. The kinetic study of copolymerization of Bd and Ip was further conducted, and the monomer reactivity ratios were determined via in situ ATR FTIR. The signal band at 1010 cm^-1 was assigned to wagging vibration of Bd and its intensity was proportional to Bd concentration （[Bd]） in the range of 0.46-3.88 mol.L^-1. The signal bands at 890 and 989 cm^-1 were assigned to wagging vibration of Ip and the signal intensity was also proportional to Ip concentration （[Ip]） in the range of 0.08-4.73 mol·L^-1 at 890 cm^-1 and 0.08-7.49 mol·L^-1 at 989 cm^-1, respectively. Thus the signal band at 1010 cm^-1 was chosen to monitor Bd concentration and bands at 989 and 890 cm^-1 to monitor Ip concentration during the copolymerization, respectively. It was demonstrated that the conversions of Bd and Ip calculated from FTIR data agreed very well with those obtained gravimetrically. The poiymerization rates were first order with respect to both [Bd] and [Ip], respectively at different polymerization temperatures. The apparent propagation activation energy for Bd and Ip could be determined to be 54.4 kJ·mol^-1 and 57.7 kJ·mol^-1, respectively. The monomer reactivity ratios were calculated to be 1.08 for Bd （rBd） and 0.48 for IP （rIp） based on FTIR data. The Bd-Ip copolymer products with random sequence could be obtained with only one glass transition temperature.
文摘The surface density changes of the central region of the sites treated by using the CO_2 laser-based non-evaporative damage mitigation for fused silica are investigated by attenuated total reflectance-Fourier transform infrared spectroscopy（ATR-FTIR）.The ATR-FTIR peak shifts of the treated sites of fused silica are monitored to determine the changes of the corresponding density.For the quenching treated sites,the surface density is increased by（0.24±0.01）%compared with the initial density but the laser annealing by the exposure of a power ramp down after damage mitigation effectively suppresses the structural changes of treated sites,which could reduce the increase of the corresponding density to（0.08±0.01）%.The results provide sufficient evidence that the laser annealing by a power ramp down after damage mitigation has a positive effect on the control of the structural change induced by CO_2 laser-based damage mitigation.
文摘<p> Lopinavir is an antiretroviral of the protease inhibitor class (Figure 1 <span style="display:none;" id="__kindeditor_bookmark_end_3__"></span>and Figure 2). It is used against HIV infections as a fixed-dose combination with another protease inhibitor, ritonavir (lopinavir/ritonavir). In the current research, the stimulated ATR-FTIR biospectroscopy of liquid sample of Lopinavir was investigated. The stimulated ATR-FTIR diffractions emitted through focusing the second harmonic laser beam Nd:YAG into the sample were recorded by Echelle spectrometer and ICCD detector. Increasing the energy of laser beam from 2.6 (mJ) to 16 (mJ) led to increase in stimulated ATR-FTIR signal but after breakdown threshold of liquid sample, further increasing energy led to the decrease in stimulating ATR-FTIR signals and for energies higher than 20 (mJ), they were disappeared. </p>
基金supported by the National Natural Science Foundation of China(Grant Nos.52278334,42272322,and 52209136).
文摘Interactions between cement clinkers and clay minerals are crucial to the much lower strength of cement-based stabilized clays than concrete or mortar.In this paper,the kaolinite-based and montmorillonite-based clays were respectively stabilized by tricalcium silicate(C3S)and tricalcium aluminate(C3A),and measured by the unconfined compressive strength(UCS),29Si/27Al solid state nuclear magnetic resonance(SS-NMR),Fourier transform infrared spectroscopy(FTIR),and transmission electron microscope(TEM)to probe the clinker-clay mineral interaction from macro-mechanical,mineralogical,and microstructural perspectives.The results show that C3A-stabilized samples gain strength rapidly in the first 3 d but are only 20%e60%of the strength of C3S-stabilized ones after 60 d.Microstructures reveal that montmorillonite shows better pozzolanic reactivity due to its superior Sichain and lattice substitution compared to kaolinite.This interaction domains the engineering performance of stabilized clays,benefiting the design of stabilizer referring to as the industrial by-products and clay minerals.
文摘Fourier transform infrared attenuated total reflectance （FTIR-ATR） spectroscopy was employed to characterize rapeseed oils. The spectral features of rapeseed oils were first investigated. Spectral data was processed using principal component analysis （PCA） and linear discriminant analysis （LDA） to discriminate the oils from three cultivars of rapeseeds. As a result, 100% discrimination accuracy was obtained by LDA. Furthermore, the applicability of FTIR-ATR spectroscopy to characterize the changes of rapeseed oils caused by thermal treatment was studied. The rapeseed oil at 60 ℃ was regularly subjected to spectral measurement, and the spectral changes induced by thermal treatment were analyzed and discussed. This study had demonstrated the good performance of FTIR-ATR spectroscopy in characterizing rapeseed oils.
