Journal ArticleDOI
The identification of the two missing conformers of gas-phase alanine: a jet-cooled Raman spectroscopy study
Reads0
Chats0
TLDR
Selective collisional relaxation processes in the jet (associated with low interconversion barriers between different alanine conformations) that depopulate the high-energy conformers were experimentally demonstrated.Abstract:
The jet-cooled spontaneous Raman spectrum of an amino acid—alanine (Ala, 2-aminopropanoic acid; H2NCH(CH3)COOH)—is reported. The low-frequency vibrational spectrum (below 500 cm−1) was recorded and assigned using quantum chemical data: ab initio (MP2) and DFT (BLYP, B3LYP, and PBE0). Band polarization measurements were used to confirm the vibrational assignments. The acquired medium resolution spectra (HWHM of ∼4 cm−1) allow the different alanine conformations to be distinguished. Four alanine conformers were observed and identified: two previously reported by microwave spectroscopy studies and two that were previously unreported. A set of reasons for why these conformers eluded previous studies are discussed. Selective collisional relaxation processes in the jet (associated with low interconversion barriers between different alanine conformations) that depopulate the high-energy conformers were experimentally demonstrated.read more
Citations
More filters
Journal ArticleDOI
Gasoline classification using near infrared (NIR) spectroscopy data: Comparison of multivariate techniques
TL;DR: NIR spectroscopy was found to be effective for gasoline classification purposes, when compared with nuclear magnetic resonance (NMR)Spectroscopy or gas chromatography (GC), and KNN, SVM, and PNN techniques for classification were find to be among the most effective ones.
Journal ArticleDOI
Melamine detection by mid- and near-infrared (MIR/NIR) spectroscopy: A quick and sensitive method for dairy products analysis including liquid milk, infant formula, and milk powder
TL;DR: It was found that infrared spectroscopy is an effective tool to detect melamine in dairy products, such as infant formula, milk powder, or liquid milk and mid- and near-infrared spectroscopic can be regarded as a quick, sensitive, robust, and low-cost method for liquid milk, infants formula, and milk powder analysis.
Journal ArticleDOI
Support vector machine regression (LS-SVM)--an alternative to artificial neural networks (ANNs) for the analysis of quantum chemistry data?
TL;DR: An alternative approach based on support vector machines (SVMs) is used, the least squares support vector machine (LS-SVM) regression, which has been applied to ab initio and density functional theory (DFT) quantum chemistry data and shows that LS-S VM is superior over the ANN method in terms of the stability, generality, and robustness of the final model.
Journal ArticleDOI
A novel biosensor based on competitive SERS immunoassay and magnetic separation for accurate and sensitive detection of chloramphenicol
Kang Yang,Yongjun Hu,Ning Dong +2 more
TL;DR: The proposed SERS-based magnetic immunosensor allows us to detect CAP in a fast, selective and sensitive manner over a wide concentration range and holds great potential for the detection of antibiotics in real aquatic environment, which is crucial to the authors' life.
Journal ArticleDOI
Highly sensitive detection of clenbuterol using competitive surface-enhanced Raman scattering immunoassay.
TL;DR: A novel approach to detect clenbuterol based on competitive surface-enhanced Raman scattering (SERS) immunoassay that has the wide potential applications in food safety and agonist control is presented.
References
More filters
Journal ArticleDOI
Smoothing and Differentiation of Data by Simplified Least Squares Procedures.
Journal ArticleDOI
Conformers of gaseous glycine
TL;DR: In this paper, related level ab initio calculations were performed for 13 conformers of neutral glyane, including all 8 possible conformers with planar heavy-atom arrangements, resulting in accurate geometric structures, relative energise, harmonic vibrational frequencies, and infrared intensities.
Journal ArticleDOI
Comparison of linear and nonlinear calibration models based on near infrared (NIR) spectroscopy data for gasoline properties prediction
TL;DR: In this article, six popular approaches of NIR spectrum-property calibration model building are compared on the basis of a gasoline spectral data and the best preprocessing technique is found for each method.
Journal ArticleDOI
Ab Initio Studies of Amino Acid Conformations. 1. The Conformers of Alanine, Serine, and Cysteine
Journal ArticleDOI
Conformers of Gaseous α-Alanine
TL;DR: In this article, the exact geometries, relative energies, rotational and quartic centrifugal distortion constants, dipole moments, harmonic vibrational frequencies, and infrared intensities have been determined from infrared images.