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  • Nondestructive discrimination of internal defects in jujube (Huizao) of Xinjiang based on visible and near-infrared spectroscopy
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-08-13
    Can Hu, Xiaotong Zhu, Xiaokang Yi, Xiaoguang Dong, Bing Lu, Xiuying Tang

    During harvest and transport, defects are most likely to affect the interior of jujubes and thus shorten their storage period. This study applied visible and near-infrared transmission spectroscopy to detect such internal defects. Spectra were acquired on the equator area at 0, 90, 180, and 270 degrees of each sample, and a model was constructed to obtain three-dimensional damage and defect detection model. The first derivative, multiplicative scatter correction, standard normal variate, and median filtering were used for preprocessing. Modeling by mean spectra achieved a better effect than using unidirectional spectra. Then, naive Bayes classifier and support vector machine were employed for the model establishment at 600–950 nm and 680–950 nm bands, respectively, using mean spectra. Median filtering effectively improved the signal to noise ratio and the discrimination accuracy of the support vector machine model at 600–950 nm reached 96.77%, which was the best value among all models. This result indicates that the support vector machine model was the optimum model and 600–950 nm was a suitable data range for the detection of internal defects. This research confirms the feasibility of implementing visible and near-infrared spectroscopy for the detection of internal defects in jujubes.

    更新日期:2019-12-03
  • On the examination of raw, pasteurized, powdered, and adulterated milk samples and their multivariate classification: applications in food and forensic science
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-31
    Raj Kumar, Atamjot Kaur, Kashma Sharma, Brajesh Kumar, Vishal Sharma

    In the present study, we have utilized attenuated total reflectance Fourier transform infrared spectroscopy for the examination of raw, pasteurized and adulterated milk samples. Principal component analysis and discriminant analysis have been applied for discrimination and classification purposes. According to the observations and the model of “goodness of fit”, the obtained results explain 100% of the original classification of the dataset and leave one out cross-validation provides 93.74% of accurate classification.

    更新日期:2019-12-03
  • Near-infrared spectroscopy-based methods for quantitative determination of active pharmaceutical ingredient in transdermal gel formulations
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-11-02
    Éva Szabó, Szilveszter Gergely, Tamás Spaits, Tamás Simon, András Salgó

    Abstract Semi-solid pharmaceutical forms, like topical and transdermal products, are widely used for medical purposes since they provide convenient and pain-free treatment for patients. In this study, two transdermal gel formulations with different active pharmaceutical ingredients were analyzed with near-infrared spectrophotometers with three distinct optical arrangements (dispersive, Fourier transform, and diode-array spectrophotometers) for the measurement of active pharmaceutical ingredient concentration. The reference concentrations were measured with high-performance liquid chromatography methods. The developing of calibration for reference concentrations based on near-infrared spectra was performed using partial least squares regression. The spectra from near-infrared spectrophotometer with diode-array optical arrangement presented the best root mean square error of cross-validation results with 0.045% and 0.144% for the two active pharmaceutical ingredients. The root mean square error of cross-validation using dispersive spectra were 0.125% and 0.193% and using Fourier transform spectra were 0.130% and 0.344% for the active pharmaceutical ingredients. The results of partial least squares regression were confirmed using simulated spectra based on the measured datasets. Near-infrared spectroscopy can be used successfully for the quantitative measurement of active pharmaceutical ingredient concentration in transdermal gel formulations. The type of optical arrangements of spectrophotometers can influence the performance of calibrations and have to be optimized case by case.

    更新日期:2019-12-03
  • Spectroscopic diagnostics of electron density in a flare ribbon by oxygen IV lines using Non-Maxwellian distribution
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-24
    Jian He, Qingguo Zhang

    By the line ratio of Oxygen IV 1399.776.50 Å and 1401.163 Å lines in a flare ribbon in the solar transition region, the principle of the electron density diagnostics using the collisional radiative model is discussed, and the relationship of the electron density with the line ratio is obtained, for both Maxwellian and Kappa distributions. By the observed line ratio, the diagnostic result of the electron density in the flare ribbon for the Maxwellian distribution are log (Ne)=11.41−0.33+0.46 cm−3, 11.42−0.33+0.46 cm−3 and 11.45−0.33+0.46 cm−3 at the temperature of log T=4.88K, 5.0 K and 5.17 K, respectively, which are slightly smaller than reported 11.96−0.22+0.35 cm−3 using the method of differential emission measure. The electron density for the Kappa distributions are log (Ne)=11.18−0.30+0.42 cm−3, 11.29−0.31+0.43 cm−3, and 11.34−0.32+0.45 cm−3 for κ = 2, 3 and 5, respectively. With increasing κ, the electron density for the Kappa distribution will be close to that for the Maxwellian distribution. This discussion is significant in the electron density diagnostics in the solar transition region, which will be also important for diagnostics for non-Maxwellian distribution.

    更新日期:2019-12-03
  • Analysis of the binding mechanism between o-phenylenediamine and bovine hemoglobin by molecular spectroscopy and molecular modeling methods
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-11-08
    Jian-Li Liu, Yu-Chi Kong, Jing-Yi Miao, Yong-Lin He, Ruo-Chen Bi, Yin He, Xiang-Yu Cao

    This study was aimed to reveal the binding mechanism between bovine hemoglobin and o-phenylenediamine by using molecular spectroscopy techniques and molecular modeling methods. The experimental results revealed that the fluorescence quenching mechanism was a combined dynamic and static quenching. The binding constant was (1.17 ± 0.02)×104 L/mol, and only a single binding site exists. The binding distance was 2.46 nm. The binding process was a spontaneous reaction, dominated by hydrophobic forces. The molecular docking simulations have also confirmed the results of the spectroscopic methods. The results reported here may significantly help understanding the interaction mechanism of o-phenylenediamine and hemoglobin.

    更新日期:2019-12-03
  • Defect characterization of slow-cooled and quenched samples of calcium-copper-titanate through positron annihilation spectroscopy
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-31
    U. M. Meshiya, K. K. Jani, P. L. Mange, D. V. Barad, P. Y. Raval, K. B. Modi, P. M. G. Nambissan

    Positron annihilation lifetime and Doppler-broadened gamma-ray spectra have been analyzed for slow-cooled and thermally quenched polycrystalline samples of calcium-copper-titanate. Two positron lifetimes revealing the characteristic defects in the respective samples were carefully analyzed to compare and contrast the significance of their origin and implication. A third component arising from positronium formation at the powdered particle surfaces has been considered in the analysis although its significance is lost in its very small intensity (∼ 1.1–1.2%). In the quenched sample, the defect-specific long positron lifetime (τ2) is found to larger and the mean lifetime smaller while its intensity I2 is found drastically smaller and the concentration of defects less by an order of magnitude as compared to the slow-cooled sample. The observed changes in electrical parameters of slow-cooled and quenched samples were found to have correlations with the positron annihilation lifetime and Doppler-broadened lineshape parameters.

    更新日期:2019-12-03
  • The model updating based on near infrared spectroscopy for the sex identification of silkworm pupae from different varieties by a semi-supervised learning with pre-labeling method
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-11-08
    Xie Lin, Yang Zhuang, Tao Dan, Li Guanglin, Yang Xiaodong, Song Jie, Liu Xuwen

    It is effective to accurately discriminate the sex of silkworm pupae with the same varieties based on near infrared spectroscopy. However, when the model is promoted to classify new varieties of silkworm pupae, the model’s performance becomes worse, due to the cultivation environment and varieties changing. In the aims of improving the generalization ability and accuracy of the model, this paper proposed a model updating strategy based on semi-supervised learning. First, support vector machine identification model was built after the original spectra was pretreated by Savitzky-Golay convolution smoothing operation, which could effectively reduce spectra noise. Then, the support vector machine model gave the pre-labelings of unlabeled silkworm pupae in the updated set, which were divided into male samples and female samples. According to the correlation coefficients that calculated by Pearson correlation coefficient and Euclidean distance, a total of 8 reliable samples were selected from the male and female samples, respectively. The reliable samples were added to the original training set to update the original model. Finally, the updated model was used to test the test sets from the varieties of silkworm pupae that were the same with updated sets.The results showed the performance of the non-updated model for silkworm pupae from the three new varieties just reached 54.55%, 68.52%, 86.84%, respectively. The support vector machine model updated by using Pearson correlation coefficient improved the accuracy to 100%, 96.30%, 97.37%, and the model updated by Euclidean distance increased the identification accuracy of the three varieties that were not involved in the modeling to 100%, 75.93%, 92.10% respectively. The results showed that the performance of the model updated by Pearson correlation coefficient was better than Euclidean distance. The results revealed that the method based on semi-supervised learning could effectively solve the problem of poor universality for sex identification model.

    更新日期:2019-12-03
  • Tentative characterization of phenolic compounds in three species of the genus Embelia by liquid chromatography coupled with mass spectrometry analysis
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-11-04
    Kizhakke Puttat Rini Vijayan, A. V. Raghu

    This article illustrates the chemical characterization of phenolic compounds, of the selected species of the genus Embelia viz., Embelia ribes, Embelia tsjeriam-cottam, and Embelia basaal using liquid chromatography coupled with mass spectrometry analysis with electrospray ionization (ESI) in negative mode. The analysis of samples allowed first-time identification of different phenolic compounds, which consists of various types of flavonoids, flavonoid glycosides, organic acids, and their derivatives, benzenoids, coumarins, and stilbens in this genus. Seventy-three different phenolic compounds were identified based on the fragment ions, and over thirty unknown compounds with unique fragmentation patterns were further noted. The results of the study offer that the selected species of the genus Embelia, which is being used in centuries-old traditional medical systems, is a promising source of medicinally valuable compounds like luteolin, sinesetin, rutin, naringenin, astragalin, narcissin, vanillic acid, resveratrol, and so on.

    更新日期:2019-12-03
  • Total aromatics of diesel fuels analysis by deep learning and near-infrared spectroscopy
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-11-02
    Ba Tuan Le, Thai Thuy Lam Ha

    This article proposes a method for quickly detecting the total aromatics content of diesel fuels based on a deep learning algorithm and near-infrared spectroscopy. First, extract the features of the diesel fuel spectral data and eliminate redundant information through the deep belief nets. Second, use a new extreme learning machine to build a prediction model. The experimental results show that the root-mean-square error of prediction value is 0.715 and the coefficient of determination value is 0.988, which proves that the method has good performance. Compared with other typical prediction methods, this method has better predictive ability.

    更新日期:2019-12-03
  • Influence of stabilizing agents on structural and optical properties of cobalt oxide nanoparticles synthesized by an ultrasound-assisted method
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-11-08
    S. J. Mammadyarova, M. B. Muradov, A. M. Maharramov, G. M. Eyvazova, Z. A. Aghamaliyev, O. O. Balayeva, I. Hasanova

    Cobalt oxide nanoparticles were synthesized using a facile and convenient sonochemical method, followed by a calcination process. For the synthesis, cobalt nitrate, and sodium borohydride were used as precursors. Polyvinyl alcohol, 3-mercaptopropionic acid, and styrene were used as a stabilizing agent. To identify the structure, optical properties and morphology, the synthesized nanoparticles were characterized using X-ray diffraction, Ultraviolet-Visible Spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy. To explain the formation mechanism of cobalt oxide nanoparticles, some investigations were carried out before thermal annealing. In addition, the particle size was tuned by variation of the concentration of 3-mercaptopropionic acid.

    更新日期:2019-12-03
  • Analyzing the performance of statistical models for estimating leaf nitrogen concentration of Phragmites australis based on leaf spectral reflectance
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-18
    Manyin Zhang, Mengjie Li, Weiwei Liu, Lijuan Cui, Wei Li, Henian Wang, Yuanyun Wei, Ziliang Guo, Daan Wang, Yukun Hu, Weigang Xu, Si Yang, Hongye Xiao, Songyuan Long

    Nitrogen is an essential nutrient for plant growth and development. Rapid and nondestructive monitoring of nitrogen nutrition in plants using hyperspectral remote sensing is important for accurate diagnosis and quality evaluation of plant growth status. The sensitive bands of leaf nitrogen concentration varied in different plants. However, most of the current studies are concentrated on crops, and only a few studies focused on wetland plants. This study investigated the accuracy of the most common univariate, stepwise multiple linear regression, and partial least squares regression models for predicting leaf nitrogen content in a wetland plant reed (Phragmites australis) by testing the accuracy of all the models through leave-one-out cross validation coefficient of determination, root mean square error and relative error. It found that: (i) sensitive bands responding to leaf nitrogen concentration were concentrated in the green and red regions of visible light; (ii) for univariate regression models, the quadratic polynomial model based on the difference spectral index composed of 665 nm and 680 nm had the highest predictive accuracy (the validation coefficient of determination was 0.7535); (iii) for multivariate regression models, the stepwise multiple linear regression models had superior predictive accuracy to the partial least squares regression models, and the stepwise multiple linear regression model with first derivative reflectance was optimal for predicting leaf nitrogen concentration (the validation coefficient of determination was 0.7746, the validation root mean square error was 0.2925, and the validation relative error was 0.0804). The findings provide a scientific basis for rapid estimation and monitoring of leaf nitrogen concentration in P. australis in a nondestructive manner.

    更新日期:2019-11-07
  • Charge transfer interaction and vibrational spectral investigation of 2-amino-5-nitropyridinium sulfamate
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-18
    P. V. Sreelaja, C. Ravikumar

    A hetero aromatic nonlinear optical crystal, 2-amino-5-nitropyridinium sulfamate was synthesized by slow evaporation method. An optimized molecular structure and theoretical vibrational spectra were obtained and analyzed by use of density functional theory. The observed vibrational wavenumbers in the experimental spectra were compared with the calculated results. Scaled quantum mechanical force field methodology with normal coordinate analysis was used for the assignment of experimental infrared and Raman spectra. The second harmonic generation and photoluminescence properties of the crystal were studied. The charge transfer interaction between the donor acceptor moieties were obtained by means of natural bond orbital analysis.

    更新日期:2019-11-07
  • Deoxyribonucleic acid and chromatin imaging of endometriosis and endometrial carcinoma using atomic force microscopy
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-17
    Peter Urdzík, Miroslava Rabajdová, Peter Urban, Rastislav Dudič, Vladimír Komanický, Mária Mareková

    Introduction: Clinical differential diagnosis of endometrial carcinoma is challenging, as signs and symptoms may vary considerably and there is a lack of reliable diagnostic serum biomarkers. Aim of the study: The aim of our work was to characterize the deoxyribonucleic acid and chromatin changes in the tissue of patients confirmed to be suffering from endometriosis and endometrial adenocarcinoma and compare it with a healthy control group. Material and methods: All samples were collected during recommended surgical interventions, and after the DNA isolation, a sonification followed by crosslink of chromatin were done. Consequently, both DNA and chromatin were examined using atomic force microscopy. Results: A chromatin immunoprecipitation was used for the in vivo observation of conformational chromatin changes. The width of ssDNA showed a significant difference, almost double the control value in the endometrial cancer sample versus control (by 73 ± 5% wider, p < 0.001). In contrast, the height of ssDNA was highest in the frozen pelvis patient sample (by 510 ± 12% compared to control, p < 0.01). Conclusion: Our results suggest that the horizontal size of single-stranded deoxyribonucleic acid and nucleosomes can help to identify potential patients with endometrial adenocarcinoma, while the height of the same parameter is associated with endometriosis.

    更新日期:2019-11-07
  • Feasibility of gem identification using reflectance spectra coupled with artificial intelligence
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-18
    Jun-Ting Qiu, Liang Qiu, Hong-Xu Mu

    Standard traditional gem identification requires expert supervision, while sophisticated modern methods are time-consuming and expensive. In contrast, reflectance spectroscopy coupled with artificial intelligence is economical and convenient and does not require specialist supervision. This study established an artificial neural network model that consists of standard multilayered, feed-forward, and back-propagation neural networks, and obtained reflectance spectra of a transparent gem (almandine), an opaque gem (turquoise), several almandine imitations (agate, plastic, and glass), and several treated turquoise samples (dyed, impregnated, and Zachery treated) using an Analytical Spectral Devices spectrometer. The acquired spectra were used to train and test the artificial neural network model. The results show that the model can effectively discriminate between genuine and imitation gems of different classes. However, discrimination between natural and treated gems of same class is not as effective as discrimination of gems of different classes. The results suggest that an artificial neural network based on reflectance spectroscopy could serve as a useful tool for preliminary gem identification, and the advanced identification needs further training and investigation.

    更新日期:2019-11-07
  • Near-infrared spectroscopy as a rapid tool for water content analysis in the partial oxidation of ethanol
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-18
    Romana Velvarská, Marcela Fiedlerová, José Miguel Hidalgo-Herrador, Zdeněk Tišler

    The oxidation of ethanol to acetaldehyde was previously investigated in a continuous flow bench scale reactor using a zirconium-oxide-supported vanadium catalyst. Products were analyzed by near-infrared spectroscopy, a fast and accurate tool for the determination of water, ethanol, and acetaldehyde content. Water content was calibrated by Karl Fischer titration while gas chromatography was used to calibrate ethanol and acetaldehyde contents. Near-infrared spectroscopy is a fast, cost-effective method for the determination of water, ethanol, and acetaldehyde products from partial ethanol oxidation.

    更新日期:2019-11-07
  • Weighted iterative inversion method for T2 spectrum in nuclear magnetic resonance
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-17
    Xuewen Hou, Guanqun Su, Bing Lu, Xin Wang, Shengdong Nie

    In traditional nuclear magnetic resonance T2 inversion methods, the components with long T2 absorb the components with short T2, especially for low magnetic field intensity. As a result, the true distribution of all components often cannot be reflected by their solutions, and thus obtaining short T2 components is an important T2 inversion problem. Herein, a weighted iterative inversion method for T2 spectrum in nuclear magnetic resonance is proposed to solve this problem. The weight-based method is applied to ensure that the short T2 components are not eliminated. The weight scheme is determined by two parameters: the number of weights and maximum weight. The number of weights is determined by the rate of decay, and the maximum weight is mainly determined by three parameters: signal-noise ratio, curvature, and slope of collected signal. To avoid the mutations of results caused by weights, the iteration process was adopted to obtain the optimal solution. The proposed method provides good results, and it was verified to be robust and accurate though simulations and experiments.

    更新日期:2019-11-07
  • Characterization of a wavelength selection method using near-infrared spectroscopy and partial least squares with false nearest neighbors and its application in the detection of the chemical oxygen demand of waste liquid
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-16
    Qing-Ping Mei, Tai-Fu Li, Li-Zhong Yao, Xiao-Hong Liu, Yuan-Li Hu, Lei Hu

    The spectral wavelength selection method is important in near-infrared spectroscopy. Eliminating redundant information and extracting useful information can improve the prediction accuracy and modeling efficiency of the quantitative analysis model for spectral analysis to obtain a near-infrared calibration model with strong predictability and good robustness. This paper proposes a wavelength selection method for near-infrared spectroscopy by combining the partial least squares and false nearest neighbor methods. In this method, the correlation between the characteristic wavelength variables and the measured index is assessed by means of a similarity-based distance measure of the characteristic wavelength variable, and the characteristic wavelength is selected according to the order of the correlation. The method was used to select characteristic wavelengths from the near-infrared spectrum of waste liquid to establish a prediction model for the chemical oxygen demand. Compared with the full-spectrum partial least squares and interval partial least squares based models, the number of characteristic wavelength variables is reduced from 1557 to 176, and the prediction accuracy of the model is improved. This method both simplifies the model and achieves higher prediction accuracy. Therefore, this study provides a novel solution for wavelength selection for multivariate calibration in near-infrared spectroscopy.

    更新日期:2019-11-07
  • Vibrational and computational analysis for molecular structure properties of N-(2-(trifluoromethyl)phenyl)acetamide: Density functional theory approach
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-18
    Shafi Aayisha, Timiri Sathyamurthy Renuga Devi, Seetharaman Janani, Sambanthan Muthu, Murugesan Raja, Sundaram Sevvanthi, Bhanumathy Ramarathinam Raajaraman

    The conformational study using Potential Energy Surface analysis was performed and its minimum energy conformer has been obtained for N-(2-(Trifluoromethyl)phenyl)acetamide. Fourier Transform Infrared and Fourier Transform Raman investigation have been done experimentally and theoretically. Nuclear Magnetic Resonance analysis has been performed to obtain 1H and 1 Bassetto, M.; Ferla, S.; Pertusati, F. Polyfluorinated Groups in Medicinal Chemistry. Future Med. Chem. 2015, 7, 527–546.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]C chemical shifts. Ultraviolet-Visible analysis has been performed to obtain maximum absorption wavelength. The molecular orbital diagram with different energies has been obtained and compared with the band gap of Ultraviolet-Visible data. Wave function analysis has been discussed to know the electronic properties. Thus, this present study reports the structural, electrical, chemical activities of the title compound.

    更新日期:2019-11-07
  • Effect of lanthanide ion co-doping on the luminescence in the cerium-doped zinc oxide-phosphor system
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-09-20
    Bhagyalekshmi Gopalakrishna Pillai Leela, Deepthi N. Rajendran

    Novel cerium, praseodymium doped, and co-doped zinc oxide nanophosphors were prepared by a solid-state reaction method. The nanopowders were characterized using X-ray diffraction, energy dispersive spectroscopy, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, UV-visible, and photoluminescence. X-ray diffraction results showed high crystalinity in the nanoscale. Emission spectra of both doped and co-doped samples lay in the bluish green region. Color chromaticity co-ordinates were estimated for the Praseodymium co-doped nanophosphor. It was shown that optical emission could be modified by adding praseodymium into the cerium doped zinc oxide lattice. This work demonstrates that luminescence enhancement in zinc oxide is possible by introducing rare earth ions, and the resulting materials may have promise for lighting applications.

    更新日期:2019-10-25
  • Analysis of 1 MeV electron irradiation-induced performance degradation in the germanium bottom cell of triple-junction solar cells using temperature-dependent photoluminescence measurements
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-09-12
    Jun Liu, Junling Wang, Yanyu Liu, Gang Yan, Wu Rui, Rong Wang

    Temperature-dependent photoluminescence spectra of the germanium bottom cell of triple-junction solar cells unirradiated and irradiated with 1 MeV electrons were measured in the 10–300 K temperature range. In unirradiated germanium bottom cell, the spectra show that the PL intensity increases with temperature but slightly decreases at around 250 K because of the intrinsic defect. However, in irradiated germanium bottom cell, the spectra show that there are two negative thermal quenching processes (10–90 K and 200–270 K) and two usual thermal quenching processes (90–200 K and 270–300 K) as a result of the radiation-induced defects Ec − 0.37 eV and Ec − 0.12 eV.

    更新日期:2019-10-25
  • Interaction of hen egg white lysozyme with cefpiramide sodium: multi-spectroscopic and computational simulations
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-09-12
    Hong-Cai Zhang, Bao-Sheng Liu

    Under simulated physiological conditions (pH = 7.40), the interaction between cefpiramide sodium and hen egg white lysozyme was studied with multi-spectroscopy and molecular docking. The results showed that cefpiramide sodium quenched the fluorescence of hen egg white lysozyme by static quenching, and the number of binding site n was about 1. The binding distance (r) between cefpiramide sodium and hen egg white lysozyme was obtained based on the Förster nonradioactive resonance energy transfer and r was less than 7 nm, which indicated that there was a non-radiative energy transition in the system. The thermodynamic parameters were obtained from the van't Hoff equation, and the Gibbs free energy ΔG < 0, indicating that the reaction was spontaneous; ΔH < 0, ΔS > 0, indicating hydrophobic interaction played a major role in forming the cefpiramide sodium-hen egg white lysozyme complex. Synchronous spectra, circular dichroism spectra and UV-Vis spectra showed that cefpiramide sodium changed the conformation of hen egg white lysozyme. The molecular docking results showed that the binding position of cefpiramide sodium was close to the active center composed of Asp52 and Glu35 residues, suggesting that cefpiramide sodium could change the microenvironment of amino acid residues at the catalytic active center of hen egg white lysozyme.

    更新日期:2019-10-25
  • Characterization of atomic layer deposition coated cutting tools by X-ray photoelectron spectroscopy and examination of cutting performance
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-09-12
    Ersin Bahceci

    The performance of cutting tools was examined, involving synthesis of a 10 nm thin film of Aluminum oxide using atomic layer deposition. Characterization of coated and uncoated cutting tools was done by several methods. scanning electron microscopy was used and the images were compared with each other. Chemical characterization was performed by X-ray diffraction and X-ray photoelectron spectroscopy. Coated and uncoated cutting tools were tested with steel material in turning tests. After turning, it was observed that the adhesion effect was reduced to a large extent in turning with coated tool. It was observed that the coating showed stability at high temperatures during cutting and the cutting performance was increased. The main advantage of the coating was that the tools produced were more environmentally friendly, with a longer useful life and they were easier to recycle.

    更新日期:2019-10-25
  • Detection of fentanyl in binary mixtures with cocaine by use of surface-enhanced Raman spectroscopy
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-14
    Abed Haddad, Omar Green, John R. Lombardi

    The ongoing epidemic pertaining to overdose deaths has been attributed to the synthetic opioid fentanyl due to its use as an adulterant in other, less potent drugs of abuse. Detection of low quantities of fentanyl would, therefore, be extremely useful in a forensic science laboratory. While Raman spectroscopy is particularly effective at distinguishing between classes of drugs, weak signatures can prove difficult when dealing with microscopic samples. Surface-enhanced Raman scattering spectroscopy provides the enhancement necessary to make Raman a viable approach for the detection of small amounts of fentanyl. This work explores the use of a paper-based substrate loaded with silver nanoparticles for the recovery of small quantities of fentanyl in cocaine, where it was identified at a lower limit of 500 ng (∼65 ppm) in mixtures. Linear relationships were investigated between intensity and concentration for diagnostic peaks associated with fentanyl and cocaine, which in turn sheds light on the attenuation of the enhancement intensity as a result of competitive binding to silver nanoparticles. This work demonstrates a potentially simple and qualitative pathway for the forensic analysis of fentanyl as an adulterant in cocaine.

    更新日期:2019-10-25
  • Determination of carotenoid and tocopherol content in maize flour and oil samples using near-infrared spectroscopy
    Spectrosc. Lett. (IF 1.081) Pub Date : 2019-10-04
    Fatih Kahrıman, İskender Onaç, Figen Mert Türk, Fatih Öner, Cem Ömer Egesel

    Secondary metabolites are important components in terms of nutrition and health. Carotenoids and tocopherols, two groups of the fat-soluble components, are also included in this category. There is an increasing interest in the detection of secondary metabolites with near-infrared spectroscopy. However, the number of scientific studies for the detection of these components, especially for tocopherols in corn flour or oil samples by near-infrared reflectance spectroscopy is rather limited. This study was carried out to determine the amount of carotenoids and tocopherols in flour and oil samples of 250 different maize genotypes by near-infrared reflectance spectroscopy using the partial least squares regression modeling method. Liquid chromatography mass spectrophotometry was used as a reference method in order to determine the contents of five carotenoids and four tocopherol subcomponents. The estimation models were created by using the spectral data collected from ground samples, and oil samples extracted from the same flour; along with the results of the reference analysis. The reliability of these models was tested by external validation (n = 50). The prediction models generated by the spectra taken from corn flour yielded more successful results than the models created with the spectra taken from the oil samples. Among the models compared, the one developed with the spectra taken from flour samples for lutein was the most successful. It is seen that the estimation models generated from flour samples can be used for screening purposes, though different approaches are needed to increase the success of models.

    更新日期:2019-10-25
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