当前期刊: Vibrational Spectroscopy Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Synthesis, structure, tautomerism, intramolecular hydrogen bond, and vibrational assignment of 3-nitroso-2,4-pentanedione: A theoretical and experimental approach
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-24
    Mansoureh Rakhshanipour; Homa Jalali; Vahidreza Darugar; Hossein Eshghi; Mohammad Vakili
    更新日期:2020-01-24
  • Salient features of branched chain amino acid strain states using confocal Raman spectroscopy with adaptive principal component analysis
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-24
    Abigail H.M. Casey; Carleah Dorsey; Nyia E. Chusan; Caroline A. Campbell; Gregory E. Triplett

    In this study, we examined how branched-chain amino acids responded to varying experimental conditions through an adaptive principal component analysis (PCA) method. Three branched chain amino acids were chosen: L-leucine, L-valine and L-isoleucine and, four blends were created with varying ratios in order to analyze the effectiveness of this approach on multicomponent samples. Blended samples were created by dissolving the three individual amino acids in four different ratios: 1:1:1, 2:1:1, 1:2:1, and 1:1:2 and allowed to recrystallize with subsequent baking to remove moisture. X-ray Diffraction was performed on control samples to verify purity and determine crystal structure. Raman spectra was collected using a modular micro-Raman system and according to a randomized full-factorial design of experiment (DOE) with the factors including excitation laser power density, and stage temperature resulting in 180 unique spectral scans across the spectral range of 50-4000 cm-1. Assignment of each Raman band in the individual amino acid samples were compared to literature values. The adaptive PCA method was executed across each sample’s collective data set, and variance across each amino acid’s complete DOE was acquired. We identified the vibrational modes that responded to changes in the excitation laser power density setting and stage temperature setting in individual samples. The variance calculated using the adaptive PCA is illustrated using standard PCA biplots. The adaptive PCA method also revealed variance due to blend composition, where the vibrational modes in the blended samples were matched to those that appear in the individual amino acid Raman spectral data to calculate the wavenumber shift.

    更新日期:2020-01-24
  • Vibrational spectra of NCCN, CNCN and CNNC : a study using the U(4) algebraic model
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-24
    Nirmal Kumar Sarkar

    A detailed study on the vibrational spectra of cyanogen(NCCN) and its isomers – isocyanogen(CNCN) and di-isocyanogen(CNNC) has been reported in this work using the U(4) algebraic model. With detailed spectral analysis, it has been shown in this study that NCCN, CNCN, CNNC and all their isotopic species can be approximated well using the U(4) algebraic model.

    更新日期:2020-01-24
  • Temperature dependence of Raman scattering in single crystal SnSe
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-22
    Xiangnan Gong; Hong Wu; Dingfeng Yang; Bin Zhang; Kunling Peng; Hanjun Zou; Lijie Guo; Xu Lu; Yisheng Chai; Guoyu Wang; Xiaoyuan Zhou

    We report on the temperature-dependence Raman modes of in-plane B3g, Ag2 and out-of-plane Ag1, Ag3 in single crystals of tin selenide that grown by a modified home-made Bridgeman method. The samples are characterized by single crystal X-ray diffraction and high-resolution transmission electron microscopy to confirm their crystal structure. The temperature-dependence of Raman spectroscopy illustrates that Ag1, B3g, Ag2 and Ag3 modes are red-shifted and softened with increasing temperature from 77 K to 400 K. Large temperature coefficients for in-plane Raman modes are observed, say −4.13 × 10−2 cm−1/K and −5.20 × 10−2 cm−1/K for B3g and Ag2 modes, respectively. The values for out-of-plane modes are much lower, say −0.91 × 10−2 cm−1/K and −1.38 × 10−2 cm−1/K for Ag1 and Ag3 modes, respectively. The result indicates intrinsic anisotropic Grüneisen parameter β in SnSe, revealing the strong anisotropic lattice anharmonicity. Besides, coefficients of optical-phonon frequency with incident laser-power were (−0.87, −2.77, −2.18 and −1.08) cm−1/mW for Ag1, B3g, Ag2 and Ag3, respectively for the laser-power dependent Raman spectroscopy experiments. Our work offers a new insight to understand the lattice anharmonicity via Raman spectroscopy and is conductive to search the new thermoelectric materials with intrinsic low lattice thermal conductivity.

    更新日期:2020-01-22
  • Application of Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Spectroscopy Coupled with Chemometrics for Detection and Quantification of Formalin in Cow Milk
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-20
    Biji Balan; Amit S Dhaulaniya; Rahul Jamwal; Amit; Kushneet K Sodhi; Simon Kelly; Andrew Cannavan; Dileep K Singh

    Milk is the best and cheapest source of nutrition and hence adulteration in milk is done to gain economic benefit. Formalin has been added illegitimately in order to increase the shelf life of milk. Fourier transform infrared (FTIR) spectroscopy coupled with multivariate chemometrics was evaluated as a quick quality monitoring method for the qualitative and quantitative analysis of formalin in cow milk. Spectra of pure and adulterated milk (0.5-5% v/v) were acquired in the wavenumber range of 4000-400 cm-1 using ATR-FTIR. Principal component analysis (PCA) showed well separated clusters allowing discrimination of pure samples from adulterated samples. Soft Independent Modelling of Class Analogy (SIMCA) approach was applied for the classification of test samples which showed 100% classification efficiency. Partial least squares (PLS) regression and Principle component regression (PCR) models were established to quantify the level of formalin in milk using normal, 1 st derivative and 2nd derivative spectra. PLSR model for normal spectra showed best prediction as compared to PCR with coefficient of determination (R2) of 0.977 for calibration and 0.985 for validation. This method has a sensitivity of 0.5% level of formalin adulteration.

    更新日期:2020-01-21
  • How SERS responses of probe molecules depend on topographies of the substrates? A vis-à-vis exploration
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-20
    Sumit Kumar Das; Somsubhra Saha; Manash Ghosh; Joydeep Chowdhury
    更新日期:2020-01-21
  • 更新日期:2020-01-17
  • Low-Wavenumber Raman Spectral Database of Pharmaceutical Excipients
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-13
    Kārlis Bērziņš; Ruth E. Sales; Jonathan E. Barnsley; Greg Walker; Sara J. Fraser-Miller; Keith C. Gordon
    更新日期:2020-01-13
  • An Rapid Nondestructive Testing Method for Distinguishing Rice Producing Areas Based on Raman Spectroscopy and Support Vector Machine
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-11
    Fangming Tian; Feng Tan; Huan Li

    This study reports method for rapid and nondestructive identification of single-grain rice produced in neighboring areas. Four types of representative rice from different areas were selected as experimental samples. A total of 284 single-grain rice Raman spectra were acquired and spectral information in the 400–1700 cm-1 spectral area was extracted for analysis. First, the samples were divided into 190 calibration sets and 94 validation sets by the Kennard–Stone method, and the raw spectra were pretreated using smoothing and differential methods. Next, principal component analysis (PCA) and a successive projections algorithm (SPA) were used to extract the optimal principal components and effective wavelengths, which were used as the input variables for k-NearestNeighbor (KNN) and least-squares support vector machine (LS-SVM) algorithms. The PCA-KNN,SPA-KNN,PCA-LS-SVM and SPA-LS-SVM models were established based on information from the rice spectra. Finally, the model was applied to classify the validation set samples. The recognition accuracies of the PCA-KNN,SPA-KNN, PCA-LS-SVM and SPA-LS-SVM models for the validation set are 91.43%,93.62%,91.49 and 94.68%, respectively. These results indicate that single-grain rice from different producing areas can be identified by using Raman spectroscopy combined with KNN and LS-SVM. This method can achieve rapid and completely non-destructive testing.

    更新日期:2020-01-13
  • An in vitro Raman study on compositional correlations of lipids and protein with animal tissue hydration
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-11
    Shan Yang; Chirantan Sen; Raven Thompson; Jian-Ge Zhou; Ozan Akkus

    Raman spectroscopy is a powerful non-invasive tool for detection and classification of chemical composition of materials including biological tissues. In this work, we report an in vitro Raman study on animal skin samples with a focus on high-frequency vibrations such as symmetric CH3 stretching mode at 2934 cm-1, and the symmetric CH2 vibration mode at 2854 cm-1, OH stretching modes near 3412 cm-1, and bounded OH mode near 3284 cm-1. Raman data was acquired with a customized InGaAs based Raman spectrometer that consolidates the NIR (866 nm) light and the InGaAs detector and is particularly suitable for probing high-frequency vibrations. The Raman spectra of fat, tendon, and muscle tissues are also analyzed to determine the spectroscopic identities of CH and OH groups in skin. Our results suggest that the protein is beneficial for the maintenance of skin hydration, as it has higher water capacity and greater capability to retain water than lipids. This conclusion is consistent with the additional discovery that water exists in fat mainly as unbound type, while part of water exists as bound type in muscle.

    更新日期:2020-01-13
  • 更新日期:2020-01-09
  • Raman-IR Spectroscopic Structural Analysis of Rare-Earth (RE3+) Doped Fluorotellurite Glasses at different laser wavelengths
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-07
    E.A. Lalla; A. Sanz-Arranz; M. Kontantinidis; J. Freemantle; P. Such; A.D. Lozano-Gorrín; V. Lavin; G. Lopez-Reyes; F. Rull-Pérez; U.R. Rodríguez-Mendoza
    更新日期:2020-01-07
  • Thermal Degradation in Edible Oils by Surface Enhanced Raman Spectroscopy Calibrated with Iodine values
    Vib. Spectrosc. (IF 1.861) Pub Date : 2020-01-02
    Ho-Ying Lam; Pradip Kumar Roy; Surojit Chattopadhyay

    We present a facile surface enhanced Raman scattering (SERS) based methodology to study the thermal degradation of edible oils using a special gold sputtered SERS tattoo. The methodology is calibrated with Iodine values, which is an industrial standard. This analytical study aims to compare the safety of 7 edible oils rich in monounsaturated (MU), polyunsaturated (PU), and saturated (S) fatty acids (FA) against high temperature re-cooking as done in most restaurants, and street food joints. The changes in the SERS signal intensity (I) ratio of the saturated (@1440 cm-1), and unsaturated (@ 1265 cm-1) FA, I1265/I1440, was studied as a function of heating time, and temperature (T), around the ‘smoke point’. The SERS marker for thermal degradation, I1265/I1440, measuring the normalized unsaturated FA content in the oils decreased consistently, and significantly for the PUFA, and MUFA oils when heated above the ‘smoke point’, following the changes in the industrial standard ‘Iodine value’. Olive (MUFA), and Coconut (SFA) oil showed marginal, and no decrease, respectively, of the SERS marker over the temperature range studied. Based on the SERS marker, a parameter ζ, -the decrease of (I1265/I1440) value of the heated oil with respect to the as-purchased value, is defined that can compare the degradation of the edible oils under different thermal stressing. The Arrhenius fit of the SERS marker yielded similar activation energy of the thermal degradation to that obtained independently from Iodine value, and demonstrates the correctness of the presented methodology.

    更新日期:2020-01-02
  • IR spectroscopic detection of the propene species formed via the interaction of copper-ion-exchanged MFI-type zeolite with propane at 573 K
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-30
    Kaori Horiguchi; Atsushi Itadani; Kazuyoshi Uematsu; Kenji Toda; Mineo Sato

    Copper-ion-exchanged MFI-type zeolite (CuMFI) has been reported to effectively interact with propane (C3H8) even at room temperature and this sample has the potential of being used as a C–H bond activation material. In this study, we examined the interaction between CuMFI and C3H8 at various temperatures. The adsorption isotherms of C3H8 showed that CuMFI exhibits strong adsorption at 573 K. For CuMFI treated at temperatures above 573 K under a C3H8 atmosphere, a characteristic infrared (IR) absorption band was detected at 1542 cm–1, which was hardly observed for other samples such as NaMFI and HMFI. This band was assigned to the C = C stretching vibration mode of propene (C3H6) species adsorbed on CuMFI. Therefore, the C3H6 species were produced by the contact of CuMFI with C3H8 at approximately 573 K; propane dehydrogenation occurred. This temperature (573 K) was lower than the reaction temperature for propane dehydrogenation, which had been reported to be temperature around 773 K or higher.

    更新日期:2019-12-30
  • Application of deep learning and near infrared spectroscopy in cereal analysis
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-26
    Ba Tuan Le

    Deep learning is an important research achievement of artificial intelligence in recent years and has received special attention from scientists around the world. This study applies deep learning to spectral analysis techniques and proposes a rapid analysis method for cereals. First, the advanced features of the near infrared spectroscopy (NIR) were extracted by the deep learning-stacked sparse autoencoder (SSAE) method, and then the prediction model is built using the affine transformation (AT) and the extreme learning machine (ELM). Experiments were conducted on corn and rice data sets to verify the effectiveness of the method. The results show that the proposed method achieves good prediction results and is superior to other typical NIR analysis methods.

    更新日期:2019-12-27
  • A fast and reliable 2D-IR spectroscopic technique for herbal leaves classification
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-26
    Muhammad Azfar Firdaus Azlah; Lee Suan Chua; Farah Izana Abdullah; Mun Fei Yam
    更新日期:2019-12-27
  • Sensitivity of semiclassical vibrational spectroscopy to potential energy surface accuracy: A test on formaldehyde
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-24
    Riccardo Conte; Giacomo Botti; Michele Ceotto

    A set of permutationally invariant potential energy surfaces for the electronic ground state of formaldehyde is built at several levels of electronic theory and atomic orbital basis sets starting from a database of more than 34000 ab initio energies. Preliminarily, the reliability of the fitted surfaces is determined by comparing the calculated harmonic frequencies with the corresponding ab initio values. Then, semiclassical estimates of the quantum frequencies of vibration are presented, and their dependence on the employed level of theory, type of atomic orbital basis set, and complexity of the fit is investigated. Comparisons of semiclassical results to experimental data provide a further assessment of the quality of the analytical surfaces and show that anharmonic frequencies are influenced by the precision of the fit, while accurate frequency values are obtained also with density functional theory. Results and conclusions support the use of ab initio “on-the-fly” semiclassical dynamics as a means of spectroscopic investigation when high-level analytical potential energy surfaces are not available.

    更新日期:2019-12-25
  • A novel biodegradable ESERS (enhanced SERS) platform with deposition of Au, Ag and Au/Ag nanoparticles on gold coated zein nanophotonic structures for the detection of food analytes
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-17
    Xiaoyuan Ma; Hazal Turasan; Fei Jia; Sujin Seo; Zhouping Wang; Gang Logan Liu; Jozef L. Kokini
    更新日期:2019-12-18
  • Near-infrared resonance stimulated Raman study of short-lived transients in PTB7 films
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-12
    Tomohisa Takaya; Ippei Enokida; Yukio Furukawa; Koichi Iwata

    Low-bandgap conjugated polymers, which have an alternating structure of electron-donating and electron-withdrawing monomer units in their main chains, are expected to show high photovoltaic efficiency when the monomer units are appropriately designed. For understanding key factors of the photovoltaic efficiency, we have investigated the structure and dynamics of short-lived transients in films of a low-bandgap conjugated polymer with an alternating structure of thieno[3,4-b]thiophene and benzo[1,2-b:4,5-b′]dithiophene, PTB7, by time-resolved near-infrared stimulated Raman spectroscopy as well as time-resolved near-infrared absorption spectroscopy. Positive polarons of PTB7 are clearly distinguished from its singlet excitons in stimulated Raman spectra by the peak position of a CC stretch band of the thiophene rings in benzodithiophene and intensity of a C–S–C deformation band of them. These differences strongly suggest that the repeated structure of thiophene rings in the main chain predominantly contributes to the charge transfer characteristics of PTB7 in films. Time-resolved absorption and stimulated Raman spectra of PTB7 films blended with a fullerene derivative show that spectral changes associated with the initial charge separation complete within 1 ps while effects of conformational changes and intermediate species are absent. We suggest that alternating copolymers composed of electron-donating and electron-accepting units commonly undergo the initial charge separation process without conformational changes or intermediates.

    更新日期:2019-12-13
  • A combination of analytical methods to evaluate the effect of humidity aging on the painting materials of icon models
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-12
    Yousry M. Issa; Gomaa Abdel-Maksoud; Medhat Ibrahim; Mina Magdy
    更新日期:2019-12-13
  • Thermal imidization behaviors of 6FDA-ODA poly(amic acid) containing curing accelerators by in-situ FTIR spectroscopy
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-10
    Yo Seob Shin, Boknam Chae, Young Mee Jung, Seung Woo Lee

    In-situ FTIR spectroscopic measurements were used to examine the thermal imidization behaviors of 6FDA-ODA PAA films in the presence of a strong tertiary amine base, such as piperazine, N,N’-dimethyl piperazine, piperidine, and 2,6-dimethyl piperidine. Large spectral changes in the FTIR spectra of 6FDA-ODA PAA films in the presence of curing accelerators were observed in the range of 110∼190 ℃, and strong tertiary amine bases used in this study accelerate the imidization reaction. Less sterically hindered piperidine with a strong base strength led to a relatively slow imidization reaction compared to piperazine, N,N’-dimethyl piperazine, and 2,6’-dimethyl piperidine. N,N’-dimethyl piperazine and 2,6-dimethyl piperidine are effective curing accelerators similar to piperazine.

    更新日期:2019-12-11
  • Installation Design of On-line Near Infrared Spectroscopy for the Production of Compound Fertilizer
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-12-10
    Jittima Ruangratanakorn, Thongchai Suwonsichon, Sumaporn Kasemsumran, Warunee Thanapase

    Low-analysis fertilizer composition highly poses risk to soil infertility, crop yield and farmer livelihood. Fertilizer testing via traditional laboratory methods is a tool for quality control but with the significantly high cost of investment and maintenance in the long run. Physiochemical data from vibrational spectra obtained from the near-infrared reflectance (NIR) analyzer shows successful installation design for real-time quality monitoring of compound fertilizer production in this study overcoming exhaustive laboratory methods offering competitive advantages to the fertilizer industry becoming a great tool for product development and lower the risk of farmers buying the low-analysis fertilizer. The NIR analyzer was designed for on-line analysis of nutrient contents of the fertilizer before bagging. Total nitrogen (TN%), available phosphorus (available―P2O5%), water-soluble potassium (water-soluble―K2O%), total organic matter (TOM%), moisture content (TMC%) including pH were required to be monitored to ensure final product release being within limits legislatively established. Spectral variations across different times of measurement over a day of the production was investigated in the condition of on-line system instead of a controlled condition to confirm the measurement will be reliable and in good reproducibility. Calibration models were developed using Partial Least Squares (PLS) regression with a series of data pretreatments on individual model per nutrient. Precision and accuracy figures of NIR results were obtained considerably good enough to the manufacturing practice. NIR prediction results were later designed for threshold and feed-back to the process control.

    更新日期:2019-12-11
  • Rapid drying-free determination of pure cashmere content in scoured cashmere using a novel method of NIR spectroscopy combined with moisture elimination and spectral reconstruction strategy
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-30
    Xiting Sun, Sisi Cheng, Hongfu Yuan, Chunfeng Song, Li Wang, Wenliang Tian, Xiaoyu Li

    Pure cashmere content (PCC) is a key parameter for assessing the quality of scoured cashmere. The traditional manual analytical method is quite laborious and time-consuming. A novel method has been developed by using near-infrared (NIR) spectroscopy combined with chemometrics and other mathematical methods. The accuracy of PCC calibration model, which is of great importance in practical application, remains a challenge due to the fact that the NIR diffuse reflectance spectra of scoured cashmere are badly influenced by absorbed moisture and light scattering. To improve the prediction accuracy, moisture elimination was first adopted to decrease the adverse effect of moisture on the spectra by subtracting the spectral contribution of water from the raw spectra. Spectral reconstruction was subsequently designed to take full advantage of the information contained in the residual values obtained after multiplicative scatter correction (MSC) pretreatment to retrieve the light scatter signal correlated with the physical properties of pure cashmere. Both the above two methods can improve the prediction performance of the partial least-squares regression (PLSR) model, and their combination can achieve the optimal model with root mean of square error of prediction (RMSEP) of 5.18%, which satisfy the accuracy requirement for PCC measurement. The proposed method is rapid, low-cost, and environment-friendly for evaluating the quality of scoured cashmere fibers and shed light on the NIR-based analysis of the complex systems with valuable physical information.

    更新日期:2019-11-30
  • Raman spectroscopy in the study of chymotrypsin-catalyzed reactions
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-29
    Irina A. Balakhnina, Nikolay N. Brandt, Andrey Yu. Chikishev, Anna A. Mankova, Irina G. Shpachenko

    Raman spectroscopy is used to study components of an enzyme-catalyzed reaction. Time dependences of integral Raman intensities in the spectra of reaction mixtures are analyzed. Parameters of chymotrypsin-catalyzed reaction are determined, and the concentrations of active enzyme molecules in the samples from different manufacturers are compared.

    更新日期:2019-11-30
  • Raman spectra and X-ray diffraction of merrillite at various temperatures
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-29
    Muhua Jia, Kuan Zhai, Mei Gao, Wen Wen, Yungui Liu, Xiang Wu, Shuangmeng Zhai

    The Raman spectra and in-situ X-ray diffraction patterns of synthetic merrillite, Ca9NaMg(PO4)7, have been measured up to 1173 K at ambient pressure. No phase transformation was observed in this study. The effect of temperature on the Raman spectra shows that all observed active bands continuously shift to lower wavenumber with increasing temperature. The temperature dependences of v3 anti-symmetric P-O stretching modes are larger than those of v1 symmetric P-O stretching, v4 and v2 O-P-O bending modes and the external modes. Lattice parameters and volume were analyzed, and the thermal expansion coefficients were obtained as 4.86(5) × 10-5 K-1, 1.46(1) × 10-5 K-1 and 1.94(5) × 10-5 K-1 for V, a and c, respectively. Thermal expansion of merrillite shows an axial anisotropy with a smaller expansion coefficient along the a-axis. The average isobaric mode Grüneisen parameter for the internal PO4 modes of merrillite has been calculated as 0.57.

    更新日期:2019-11-30
  • Compositional investigation and phase identification of 13th century Anatolian Seljuk glazed tiles
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-25
    Bilge Alp Güney, Evin Caner

    Glazed tiles from five madrasas built in Anatolia by Seljuks during 13th century were examined using multi-analytical techniques to discover production processes, firing temperatures, raw materials and nature of colorants used. Turquoise colored glazes were assessed to be of the type tin-opacified lead-alkali whereas the violet-brown colored glaze was determined to be of the transparent alkali type. Copper and manganese were identified to be responsible for the turquoise and violet-brown color of the glazes, respectively. Firing temperatures of the glazes were estimated using polymerization indexes calculated by using Raman spectra of the samples and assessed to be in the range of 800-1000 °C. Bodies of the glazes were determined to be produced using quartz, low calcareous and non-calcareous clays. No slip layers were observed between the glaze and the body in the samples. Gas bubbles observed inside the glaze layers in some of the samples suggested that glazes might have been applied on a non-fired body. Tin-opacified lead-alkali glazes investigated in this study were suggested to be produced in the specialist centers in Anatolia which were limited in quantity during the Seljuk period.

    更新日期:2019-11-26
  • ATR-FTIR coupled with Chemometrics for quantification of vildagliptin and metformin in pharmaceutical combinations having diverged concentration ranges
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-23
    Sherif M. Eid, Shymaa S. Soliman, Mohamed R. Elghobashy, Ola M. Abdalla

    An accurate, fast and simple quantitative analysis of drug combinations with wide variation in concentration ranges has been an area of interest for several decades. The limited linearity range of UV-VIS spectroscopy may be insufficient to occupy with multiple components with diverge concentrations and several preparation steps may be required. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) in combination with partial least square regression (PLSR) chemometric method can be a good alternative. Vildagliptin and metformin pharmaceutical dosage forms, which have a wide concentration ranges of (50/500, 50/850 and 50/1000 mg), were used as a model. A calibration set with partial factorial design was used to develop PLSR model able to predict the concentration of unknown samples containing the two drugs. The method was optimized, validated and successfully applied for simultaneous estimation of vildagliptin and metformin in pharmaceutical formulations with high accuracy and reproducibility. The proposed FTIR method was compared to traditional methods such as UV spectroscopy and HPLC to highlight the opportunities and challenges for every technique.

    更新日期:2019-11-26
  • Analysis of omeprazole and esomeprazole obtained from traditional pharmacies and unlicensed internet websites using Raman spectroscopy, 1H-NMR and chemometric analysis
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-23
    Gaetano F. Bellia, Guzman Gil-Ramirez, Mark G. Baron, Ruth Croxton, Jose Gonzalez-Rodriguez

    The relevant therapeutic outcomes obtained with the use of proton pump inhibitors for the treatment of gastric conditions have an important reflection on the prescribing habits of clinicians of primary and secondary care organizations. With the attempt to reduce their financial impact on the health systems, generic medications, obtained both from tradition distribution chain and from parallel import, have represented the main type of proton pump inhibitors used in clinics recently. The effect of parallel import and the use of the internet as an international distribution network significantly facilitates the entry of falsified medicines in the official channels of distribution. Since the interchangeability of different omeprazole preparations has been previously questioned, in this study we used Raman and 1H-NMR to characterise different omeprazole and esomeprazole formulations produced by different manufacturers and obtained from both traditional pharmacies and from unlicensed internet market in order to establish if any differences could be found to substantiate any different clinical performances. A chemometric study of Raman spectra allowed partial separation indicating that there are not sufficient chemical differences for PCA groups to be established using this analytical approach and for these specific medications. On the contrary, NMR investigations allowed the identification of impurities in internet samples, not detected by the Raman analyses, making this technique a valid candidate analytical tool to adopt for the investigation of falsified medicines.

    更新日期:2019-11-26
  • Raman Spectroscopy of Pre-strained VHB 4910 Elastomer Towards Actuator Application
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-18
    Dhananjay Sahu, Raj Kumar Sahu, Karali Patra, Jerzy Szpunar

    Dielectric elastomers are the potential material to configure soft electromechanical actuators and similar modules. But, understanding the relationship between molecular structures and properties of such elastomers in real-time is a powerful and lacking tool, important to consider when properties are targeted to improve by tailoring (macro)molecular arrangement. Here, molecular bonds within VHB 4910 dielectric elastomer are explored using techniques of Raman spectroscopy. Identified bonds are correlated well with electromechanical properties and macromolecular characteristics. Then the effects of pre-strain known to influences material behavior are comprehended in the context of molecular-level structural-adaptation. Intermolecular bonds revealed for hard segments, soft segments and acrylate structure are found certainly sensitive for applied strain, persist ideology of chain entanglement towards strain-induced crystallization. These results are experimentally consistent and the work may help to focus specific structure to adapt user-defined properties.

    更新日期:2019-11-18
  • Study on the reactivity and kinetics of primary and secondary amines during epoxy curing by NIR spectroscopy combined with multivariate analysis
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-17
    Chunyan Huang, Xiting Sun, Hongfu Yuan, Chunfeng Song, Yan Meng, Xiaoyu Li

    The temperature of epoxy curing reaction and the change of amino reactivity for the amine curing agent have an effect on the three-dimensional network structure of the product, which in turn affect the performance of the epoxy resin. The study on the reactivity and kinetics of primary and secondary amines in epoxy curing process is of great significance to deeply understand the curing mechanism and realize the control of product quality. In this paper, an effective method for studying the reactivity and kinetics of primary and secondary amines in epoxy curing process by near-infrared (NIR) spectroscopy combined with multivariate analysis was proposed. The curing system of bisphenol A epoxy resin (E51) and M-xylylenediamine (MXDA) was studied, and the resins were isothermally prepared at 50, 60, 70, 80, 90 °C, respectively. The NIR spectra of the system for each curing reaction process were continuously collected online. The characteristic absorption bands of the primary and secondary amines overlap heavily in the wavenumber range of 6700-6330 cm-1. The wavelet-based second derivative together with multivariate curve resolution(MCR)were employed to resolve their respective absorption peaks. Then, the curves of conversion and conversion rate for primary and secondary amines were obtained. The study shows that the kinetics of the curing reaction follows the self-catalytic Kamal model in the early stage, and it follows the revised model of incorporating the diffusion factor after vitrification, in which the hydroxyl group plays a self-catalytic role in the reaction process; the reactivity of primary and secondary amines is different during epoxy curing process.There is a competitive reaction between them, and its competitiveness can be expressed by k2(SA)/k2(PA); the reactivity of primary and secondary amines varies with curing temperature, and k2(SA)/k2(PA) increases significantly when curing temperature exceeds 60 °C, which has a significant influence on the formed resin network structure.

    更新日期:2019-11-18
  • The Raman optical activity of pinane as compared with (-)α- and (-)β-pinene: the perspective of intramolecular enantiomerism
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-15
    Hongru Yang, Peijie Wang, Guozhen Wu

    The Raman and Raman optical activity (ROA) spectra of chiral pinane were analyzed by a bond polarizability algorithm. By the differential bond polarizability, the chirality of pinane is compared with our previous results of (-)α- and (-)β-pinene to show the intramolecular enantiomerism. The intramolecular enantiomerism implies the existence of an approximate mirror symmetry. This symmetry is most destroyed by the on-ring C-C double in (-)_α-pinene. This leads to the decrease of ROA from (-)α-pinene, (-)β-pinene to pinane. Variation of differential bond polarizabilities also follows this trend. This comparison demonstrates the chiral behavior and the roles of the asymmetric centers of (-)α-, (-)β-pinene and pinane from a spectroscopic viewpoint.

    更新日期:2019-11-18
  • Optimization of Synephrine and its Vibrational and Electronic Structures
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-15
    T. Yadav, V. Mukherjee
    更新日期:2019-11-18
  • Raman spectra and ab-initio calculations in Bertholletia excelsa oil
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-14
    Q.S. Martins, L.M.S. Santos, J.L.B. Faria

    In the Brazilian Amazon, many plants are important in the economic context, since they can be obtained from raw material for the most diverse commercial applications. Oils extracted from plants in general are in this context. Bertholletia excelsa produces one of the best-known fruits of the Amazon, the Brazil nut, from which the oil of the same name is extracted, object of study in this work. In the present work the vibrational study of the oil of Brazil nut was performed by Raman spectroscopy (RS), since it is a technique of rapid evaluation in the physical-chemical study, since any preparation of the sample is excluded and can be performed often on-site, and with as little time as possible. For the analysis, a monochromatic source Raman spectrometer with excitation frequency of 633 nm was used. In addition, the spectral formation was discussed based on the chemical composition of the sample by density functional theory (DFT) in order to compare and understand the vibrational nature of the sample. The results showed intense vibrational bands from fatty acids with C–C, C=C and O–H bonds. A brief approximation with calculated first principles was used to predict results. The present work also aims to show that RS technique contributes in a safe and fast way for qualitative analyzes in natural oils.

    更新日期:2019-11-14
  • At-line monitoring of salification process of the antiretroviral lamivudine-saccharinate salt using FT-MIR spectroscopy with multivariate curve resolution
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-13
    Sarmento J. Mazivila, Ricardo A.E. Castro, João M.M. Leitão, Joaquim C.G. Esteves da Silva

    This article presents a promising application of Fourier transform-mid infrared (FT-MIR) spectroscopy with multivariate curve resolution ― alternating least-squares (MCR-ALS) as an at-line process analytical technology (PAT) to enhancing the understanding and continuous control of a pharmaceutical manufacturing process. Its objective was to monitor the synthesis of pharmaceutical multicomponent crystals in solid-state, namely the mixture between lamivudine (active pharmaceutical ingredient-API) and saccharin (coformer) using liquid assisted grinding (LAG) in proportion of 1:1 in a ball mill. The continuous monitoring of synthesis procedure ensured product quality, revealing some of the events that can be detected during mechanochemical synthesis by FT-MIR spectroscopy with MCR-ALS. The concentration profiles retrieved by MCR-ALS allowed to identify the end of the salt synthesis. In fact, this is one of the advantages of real-time monitoring using FT-MIR spectroscopy and MCR-ALS, because it can be helpful not only to monitor and control a pharmaceutical manufacturing process, but also to optimize efficient use of energy, time and raw materials for lamivudine-saccharinate salt synthesis. Moreover, it allowed to understand that the antiretroviral lamivudine-saccharinate salt synthetized by LAG showed a fast reaction mechanism due to the presence of ethanol as catalyst. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) techniques provided additional information needed to fully characterize pharmaceutical lamivudine-saccharinate salt synthetized by LAG technique.

    更新日期:2019-11-13
  • Automatic cancer discrimination based on near-infrared spectrum and class-modeling technique
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-13
    Hui Chen, Zan Lin, Chao Tan

    To develop an effective and objective diagnostic method for detecting the malignancy is of great importance. Considering that near-infrared (NIR) spectroscopy has many advantages such as being inexpensive and simple in sample preparation and class-modeling is a rather new strategy, the present paper investigates the feasibility of combining class-modeling technique other than classic classification and NIR spectroscopy for colorectal diagnosis. A total of 162 colorectal tissue slices were prepared and used to collect NIR spectra. A special variable importance (VI) index was defined to pick out 20 most significant variables. The Kennard-Stone (KS) algorithm was used to select representative 57 cancerous samples as the training set for building one-class model and the other samples served as the test set. The results showed that on the independent test set, it can achieve acceptable performance, i.e., the total accuracy of 95.2%, the sensitivity of 96%, and the specificity of 94.5%. It indicates that the combination of NIR spectroscopy and one-class classifier is a potential tool for automatic cancer diagnosis.

    更新日期:2019-11-13
  • Room Temperature Gas Phase Infrared Spectra of H-bonded Oligomers of Methanol
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-09
    Bedabyas Behera, Shubhadip Chakraborty
    更新日期:2019-11-11
  • A novel strategy of near-infrared spectroscopy dimensionality reduction for discrimination of grades, varieties and origins of green tea
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-09
    Peng Liu, Yangping Wen, Junshi Huang, Aihua Xiong, Jianping Wen, Hong Li, Yifeng Huang, Xiaoyu Zhu, Shirong Ai, Ruimei Wu
    更新日期:2019-11-11
  • FTIR spectroscopy analysis for monitoring biodiesel production by heterogeneous catalyst
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-09
    Morgana Rosset, Oscar W. Perez-Lopez

    Layered double hydroxides, mixed oxides, and pure oxides based on magnesium and calcium were evaluated as catalysts in the methyl transesterification of soybean oil in a batch reactor. The catalysts were prepared by continuous co-precipitation and characterized by specific surface area, thermogravimetric analysis, temperature-programmed desorption of CO2, and X-ray diffraction. The reactions were performed at 65 °C, methanol-to-oil molar ratio 9:1, catalyst dosage of 1 wt.%, and reaction time of 240 min. The biodiesel analysis was carried out by Fourier Transform Infrared spectroscopy (FTIR) and Gas Chromatography (GC). Calcium-based catalyst, pure oxide (CaO) and mixed oxide (CaAl), demonstrated higher activity for methyl transesterification than magnesium-based catalyst. Considering both groups of catalysts, the activity for transesterification was: pure oxide > mixed oxide >> LDH. These results were related to the strength of the basic sites. FTIR and GC results were similar, with the advantage of FTIR analysis being simple, fast, and economical.

    更新日期:2019-11-11
  • Comprehensive study of an ancient Egyptian foot case cartonnage using Raman, ESEM-EDS, XRD and FTIR
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-11-03
    Asmaa M. Hussein, Fatma S. Madkour, Hala M. Afifi, Mona Abdel-Ghani, Mostafa Abd Elfatah

    As part of a project concerning conservation of some ancient Egyptian relics excavated from Saqqara, a foot case cartonnage, which could be dated to the Late Period (712-332 B.C.), was investigated. The structure of the cartonnage, along with substrates, ground layers, pigments and paint binders were revealed using multi-analytical techniques. Optical microscopy (OM), X-ray diffraction (XRD), Raman spectroscopy, Environmental scanning electron microscopy with energy-dispersive x-ray analysis of elements (ESEM-EDS) and Fourier transform infrared spectroscopy coupled with attenuated total reflection (FTIR-ATR) were used in this study. The structure of the cartonnage is found to consist of five distinctive layers, from the bottom up; two calcite-based plaster layers which are separated by double linen layers and covered with a polychrome paint layer. The study of the paint layer revealed the presence of three different red shades (light, brilliant, and dark) which consist of a mixture of red ochre and gypsum (CaSO4.2H2O), cinnabar (α-HgS), and red ochre respectively. Two blue shades were also detected of which the darker consists of Egyptian blue [Cuprorivaite (CaCuSi4O10)] while the lighter contains Egyptian blue admixed with gypsum and calcite (CaCO3). Orpiment (As2S3) and yellow ochre (FeOOH) were used to obtain the yellow paint while same pigments in addition to pararealgar (As4S4), calcite and gypsum were used as the beige paint. The pigment palette used was quite complex and is typical of those encountered in the late and Graeco-Roman periods. The only exception is the addition of the yellow pigment pararealgar in the beige paint, which is considered a novelty in cartonnage industry. A proteinaceous binding medium, namely animal glue, was found to be used in both the plaster and the paint layers.

    更新日期:2019-11-04
  • A rapid and simple chemical method for the preparation of Ag colloids for surface-enhanced Raman spectroscopy using the Ag mirror reaction.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-01-22
    Rajapandiyan Panneerselvam,Li Xiao,Ken B Waites,T Prescott Atkinson,Richard A Dluhy

    Colloidal silver (Ag) nanoparticles (AgNP) have been widely used for surface-enhanced Raman spectroscopy (SERS) applications. We report a simple, rapid and effective method to prepare AgNP colloids for SERS using the classic organic chemistry Ag mirror reaction with Tollens' reagent. The AgNP colloid prepared with this process was characterized using SEM, and the reaction conditions further optimized using SERS measurements. It was found that Ag mirror reaction conditions that included 20 mM AgNO3, 5 min reaction time, and 0.5 M glucose produced AgNP colloids with an average size of 319.1 nm (s.d ±128.1). These AgNP colloids exhibited a significant SERS response when adenine was used as the reporter molecule. The usefulness of these new AgNP colloids was demonstrated by detecting the nucleotides adenosine 5'-monophosphate (AMP), guanosine 5'-monophosphate (GMP), cytidine 5'-monophosphate (CMP), and uridine 5'-monophosphate (UMP). A detection limit of 500 nM for AMP was achieved with the as-prepared AgNP colloid. The bacterium Mycoplasma pneumoniae was also easily detected in laboratory culture with these SERS substrates. These findings attest to the applicability of this AgNP colloid for the sensitive and specific detection of both small biomolecules and microorganisms.

    更新日期:2019-11-01
  • Raman Spectroscopic Discrimination of Estrogens.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2018-10-30
    Jayson Vedad,Elmer-Rico E Mojica,Ruel Z B Desamero

    Estrogens are a group of steroid compounds found in the human body that are eventually discharged and ultimately end up in sewer effluents. Since these compounds can potentially affect the endocrine system its detection and quantification in sewer water is important. In this study, estrogens such as estrone (E1), estradiol (E2), estriol (E3), and ethynylestradiol (EE2) were discriminated and quantitated using Raman spectroscopy. Simulated Raman spectra were correlated with experimental data to identify unique marker peaks, which proved to be useful in differentiating each estrogen molecules. Among these marker peaks are Raman modes arising from hydroxyl groups of the estrogen molecules in the spectral region 3200-3700 cm-1. Other Raman modes unique to each of the estrogen samples were also identified, including peaks at 1722 cm-1 for E1 and 2109 cm-1 for EE2, which corresponds to their distinctive structures each containing a different set of functional groups. To quantify the components of estrogen mixtures, the intensities of each identifying Raman bands, at 581 cm-1 for E1, 546 cm-1 for E2, 762 cm-1 for E3 and 597 cm-1 for EE2, were compared and normalized against the intensity of a common peak at 783 cm-1. Quantitative analysis yielded most results within an acceptable 20% error.

    更新日期:2019-11-01
  • Infrared spectroscopic characterization of mineralized tissues.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2006-05-13
    Adele L Boskey,Richard Mendelsohn

    Vibrational spectroscopy (Infrared and Raman), and in particular micro-spectroscopy and micro-spectroscopic imaging has been used to characterize developmental changes in bone and other mineralized tissues, to monitor these changes in cell cultures, and to detect disease and drug-induced modifications. Examples of the use of infrared micro-spectroscopy and micro-spectroscopic imaging are discussed in this review.

    更新日期:2019-11-01
  • Phase Behavior of Planar Supported Lipid Membranes Composed of Cholesterol and 1,2-Distearoyl-sn-Glycerol-3-Phosphocholine Examined by Sum-Frequency Vibrational Spectroscopy.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2010-04-03
    Jin Liu,John C Conboy

    The influence of cholesterol (CHO) on the phase behavior of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) planar supported lipid bilayers (PSLBs) was investigated by sum-frequency vibrational spectroscopy (SFVS). The intrinsic symmetry constraints of SFVS were exploited to measure the asymmetric distribution of phase segregated phospholipid domains in the proximal and distal layers of DSPC + CHO binary mixtures as a function of CHO content and temperature. The SFVS results suggest that cholesterol significantly affects the phase segregation and domain distribution in PSLBs of DSPC in a concentration dependent manner, similar to that found in bulk suspensions. The SFVS spectroscopic measurements of phase segregation and structure change in the binary mixture indicate that membrane asymmetry must be present in order for the changes in SFVS signal to be observed. These results therefore provide important evidence for the delocalization and segregation of different phase domain structures in PSLBs due to the interaction of cholesterol and phospholipids.

    更新日期:2019-11-01
  • Cytology by Infrared Micro-Spectroscopy: Automatic Distinction of Cell Types in Urinary Cytology.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2009-09-22
    Benjamin Bird,Melissa J Romeo,Max Diem,Kristi Bedrossian,Nora Laver,Stephen Naber

    We report microscopically collected infrared spectra of cells found in human urine in an effort to develop automatic methods for bladder cancer screening. Unsupervised multivariate analysis of the observed spectral patterns reveals distinct spectral classes, which correlated very well with visual cytology. Therefore, we believe that spectral analysis of individual cells can aid cytology in rendering reliable diagnoses based on objective measurements and discriminant algorithms.

    更新日期:2019-11-01
  • Chasing lipids in health and diseases by coherent anti-Stokes Raman scattering microscopy.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2009-09-19
    Han-Wei Wang,Yan Fu,Terry B Huff,Thuc T Le,Haifeng Wang,Ji-Xin Cheng

    The integration of near IR picosecond pulse excitation, collinear beam geometry, epi-detection, and laser-scanning has produced a coherent anti-Stokes Raman scattering (CARS) microscope with a detection sensitivity of 10(5) vibrational oscillators, sub-micron 3D resolution, and video-rate acquisition speed. The incorporation of spectral detection and other imaging modalities has added versatility to the CARS microscope. These advances allowed sensitive interrogation of biological samples, particularly lipids that have a high density of CH(2) groups. With initial applications to membrane domains, lipid bodies, demyelinating diseases, obesity, and cardiovascular diseases, CARS microscopy is poised to become a powerful bio-imaging tool with the availability of a multifunctional, affordable, easy-to-operate CARS microscope, and the development of CARS endoscopy for in vivo diagnosis.

    更新日期:2019-11-01
  • Infrared micro-spectroscopy of human cells: Causes for the spectral variance of oral mucosa (buccal) cells.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2006-10-18
    Melissa Romeo,Brian Mohlenhoff,Max Diem

    We discuss the causes contributing to the variance of the spectra of individual human epithelial cells. This aspect has largely been ignored in previous studies, but needs to be understood for diagnostic applications of infrared micro-spectroscopy. We attribute the spectral variance to Mie scattering, and to variations of nuclear contributions to the overall spectra caused by different nuclear size.

    更新日期:2019-11-01
  • Infrared spectral imaging of lymph nodes: Strategies for analysis and artifact reduction.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2005-07-29
    Melissa J Romeo,Max Diem

    In this contribution, we discuss state-of-the-art methodology for the collection and analysis of hyperspectral images of tissue that will become useful in complementing classical histopathology. In particular, we discuss sampling strategies, data collection methods, and computational approaches to produce pseudo-color maps of large tissue sections of lymph nodes, up to about 100 mm(2) in size. The latter efforts include methods to reduce the presence of dispersion artifacts in IR transflection micro-spectra which can greatly impact the statistical analyzes performed on the data, such as hierarchical cluster analysis and principal components analysis.

    更新日期:2019-11-01
  • Attenuated total reflectance Fourier-transform infrared spectroscopic imaging for breast histopathology.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2012-07-10
    Michael J Walsh,Andre Kajdacsy-Balla,Sarah E Holton,Rohit Bhargava

    Histopathology forms the gold standard for the diagnosis of breast cancer. Fourier Transform Infrared (FT-IR) spectroscopic imaging has been proposed to be a potentially powerful adjunct to current histopathological techniques. Most studies using FT-IR imaging for breast tissue analysis have been in the transmission or transmission-reflection mode, in which the wavelength and optics limit the data to a relatively coarse spatial resolution (typically, coarser than 5 μm × 5 μm per pixel). This resolution is insufficient to examine many histologic structures. Attenuated Total Reflectance (ATR) FT-IR imaging incorporating a Germanium optic can allow for a four-fold increase in spatial resolution due to the material's high refractive index in the mid-IR. Here, we employ ATR FT-IR imaging towards examining cellular and tissue structures that constitute and important component of breast cancer diagnosis. In particular, we resolve and chemically characterize endothelial cells, myoepithelial cells and terminal ductal lobular units. Further extending the ability of IR imaging to examine sub-cellular structures, we report the extraction of intact chromosomes from a breast cancer cells and their spatially localized analysis as a novel approach to understand changes associated with the molecular structure of DNA in breast cancer.

    更新日期:2019-11-01
  • Depth-dependent Anisotropy of Proteoglycan in Articular Cartilage by Fourier Transform Infrared Imaging.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2011-10-26
    Jian-Hua Yin,Yang Xia,Nagarajan Ramakrishnan

    Fourier transform infrared microscopic imaging (FTIRI) was used to quantitatively examine the anisotropies of proteoglycan (PG) and collagen in articular cartilage. Dried 6 μm thick sections of canine humeral cartilage were imaged at 6.25 μm pixel-size in FTIRI with an infrared analyzer set at 26 different angles between 0° and 180° polarization. Like the amide II and amide III peaks, the 1338 cm(-1) band confirms the anisotropy of collagen fibrils in cartilage. The absorption profile of the sugar band shows an anisotropic flipping at the deeper part in the radial zone, just above the tidemark. Together with the reduction in the PG concentration and subsequent increase in tissue calcification in this region, this anisotropy flipping of sugar might be caused by the orientational change in the collagen-attaching PG from orthogonal to parallel when the fibrils are entering the calcified zone.

    更新日期:2019-11-01
  • Accounting for tissue heterogeneity in infrared spectroscopic imaging for accurate diagnosis of thyroid carcinoma subtypes.
    Vib. Spectrosc. (IF 1.861) Pub Date : 2017-08-07
    David Martinez-Marin,Hari Sreedhar,Vishal K Varma,Catarina Eloy,Manuel Sobrinho-Simões,André Kajdacsy-Balla,Michael J Walsh

    Fourier transform infrared (FT-IR) microscopy was used to image tissue samples from twenty patients diagnosed with thyroid carcinoma. The spectral data were then used to differentiate between follicular thyroid carcinoma and follicular variant of papillary thyroid carcinoma using principle component analysis coupled with linear discriminant analysis and a Naïve Bayesian classifier operating on a set of computed spectral metrics. Classification of patients' disease type was accomplished by using average spectra from a wide region containing follicular cells, colloid, and fibrosis; however, classification of disease state at the pixel level was only possible when the extracted spectra were limited to follicular epithelial cells in the samples, excluding the relatively uninformative areas of fibrosis. The results demonstrate the potential of FT-IR microscopy as a tool to assist in the difficult diagnosis of these subtypes of thyroid cancer, and also highlights the importance of selectively and separately analyzing spectral information from different features of a tissue of interest.

    更新日期:2019-11-01
  • An Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopic Study of Waterlogged Woods Treated with Melamine Formaldehyde
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-10-25
    Namık kiliç, A. Gökçe kiliç

    Various different methods are used for the conservation of waterlogged wood. One of them is melamine formaldehyde method which is also used for conservation of highly degraded woods of the Yenikapı shipwrecks. In this method, melamine formaldehyde resin is replaced with the water inside the waterlogged wood. After impregnation and drying process, the wood turns into a stable state. In order to sustain a successful conservation procedure, the wood should be impregnated with the resin. Otherwise, shrinkage and collapse of the wood occur in the parts which are not impregnated with the resin. In this study, 20 melamine formaldehyde treated core samples, which were taken from Yenikapı shipwrecks, were analysed with FTIR-ATR to determine the success of the impregnation. To determine significant bands which are related to melamine formaldehyde, spectra of fresh wood, waterlogged wood, and melamine formaldehyde treated wood were analysed considering wood species. On the spectra of melamine formaldehyde treated woods, the band at ∼ 810 cm-1 was determined which is formed due to the presence of triazine. With this gained information, FTIR analyses were done on the wood samples which were in the impregnation boxes. The band at ∼ 810 cm-1 was determined on the spectra of these samples. It shows that woods were impregnated with melamine formaldehyde and they can be dried in order to end the process.

    更新日期:2019-10-25
  • Monitoring changes in the cellular content of biomolecules during ageing with FTIR spectroscopy
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-09-23
    Mariana Bermúdez-Moretti, Juan Facundo Gulías, Jenniffer Valencia-Guillén, Sebastián Aníbal Muñoz, Isabelle Forfar, Susana Correa-García

    Dietary regimens have proven to promote longevity in several eukaryotic model organisms including the budding yeast Saccharomyces cerevisiae. These interventions are effective strategies for preventing ageing and diseases and many of them are linked to amino acid and protein levels. The aim of this work was to better understand how the age-related TOR1 and SCH9 genes and the presence of amino acids affect cell metabolomes and to establish their impact on the ageing process. Cellular metabolic profiles were determined by FTIR spectroscopy. We demonstrated that metabolic signatures of cells deficient in SCH9, the major TORC1 effector, were very different to those of wild type and TOR1 deficient cells. In cells lacking Sch9 we also observed changes in other processes related to ageing such as endoplasmic reticulum stress and autophagy. We identified several anti-ageing biomarkers being the most relevant the intracellular content of pyruvate, glucose, ribose/deoxyribose associated compounds, and the presence of special protein conformational structures. The very sensitive FTIR technique allowed us to highlight important changes that occur along ageing in the metabolomes of the cells deficient in the key nutrient-sensitive Tor1-Sch9 pathway, even though slight differences on chronological lifespan were detected in our conditions.

    更新日期:2019-10-25
  • Raman and FT-IR investigation of neutron and fission-fragment irradiated DAP polymer
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-09-23
    Luiz Augusto Stuani Pereira, Carlos Alberto Tello Sáenz

    The polymer Diallyl Phthalate (DAP), commonly used as solid-state nuclear track detector (SSNTD), has been characterized via optical microscopy and Raman and FT-IR spectroscopies in three distinct processes: i) without irradiation; ii) irradiated by neutrons and induced fission fragments and iii) as a function of the chemical etching time. The detectors were exposed to fission fragments from the induced fission of 235U and to the neutrons themselves. The optical microscopy provides information about the morphological changes, while the spectroscopic techniques provide physical and chemical information over the detector molecular structure. The irradiation and chemical etching induces molecular degradation and cross-linking of the detector chemical structure as observed in the Raman and FT-IR analyses. According to the spectral profile analyses, the strength of the functional groups OCOO, CH, CHCH, CCH, COC, CCH3, C(CH3)2, CCH3, CO, CH2 decrease and additional CO2 gases and OH groups are produced. Therefore, the characterization process performed in this work is essential to better comprehend the behavior of the DAP molecular structure under irradiation and chemical etching and also to better understand the track formation process which is related to the etching kinetics.

    更新日期:2019-10-25
  • Multi-walled carbon nanotubes /boron oxide composite using plasmonic Ag nanoparticles: Synthesis and SERS characterization
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-09-23
    H. Hasan Bouzari, L. Farhang Matin, R. Malekfar

    In this work, by applying a straightforward and easy technique B2O3 doped MWCNTs synthesized using laser ablation in liquid environment (LALE) method. The plasmonc properties of Ag NPs prepared via Lee-Meisel technique was used to prepare high quality substrates for Surface – enhanced Raman scattering (SERS) measurements The size of Ag NPs was acknowledged by UV/Vis/NIR absorption spectroscopy and SEM imaging (<50 nm). A rather powerful SERS signal was created due to the plasmonic effect and the presence of Ag NPs. Furthermore, SERS spectra were collected in all the synthesized samples. The concentration level down to 10−4 molar (M) of boron oxide (B2O3) doped samples were detected. The recorded data reveals that an enhancement factor (EF) SERS factor of about 105 can be easily achieved applying this method.

    更新日期:2019-10-25
  • Thermodynamic model and Raman spectra of BaO-B2O3 glasses
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-09-30
    Branislav Hruška, Armenak A. Osipov, Leyla. M. Osipova, Mária Chromčíková, Jan Macháček, Marek Liška

    The structure of xBaO•(1-x)B2O3 (x = 0.20, 0.25, 0.30, 0.35, and 0.40) glasses were studied by Raman spectroscopy and the thermodynamic model of Shakhmatkin and Vedishcheva (SVTDM). Nine system components were considered in the SVTDM: BaO, B2O3, 2BaO•5B2O3, 2BaO•B2O3, 3BaO•B2O3, 4BaO•B2O3, BaO•B2O3, BaO•2B2O3, and BaO•4B2O3. In all components of the SVTDM with non-negligible equilibrium abundance, only three short range order structural units were identified on the basis of structural data: trigonal boron with three bridging oxygen atoms (T3), trigonal boron with two bridging oxygen atoms (T2), and tetragonal boron with four bridging oxygen atoms (Q4). The Multivariate Curve Analysis (MCR) of the baseline subtracted and thermally corrected experimental Raman spectra was performed for three components. MCR resulted in the Raman spectra (so called loadings) and relative abundances (so called scores) of each considered structural unit. On the basis of strong positive correlations between the equilibrium molar amounts of structural units and scores, the particular structural units were attributed to individual loadings. This result was confirmed by the structural analysis of the individual loadings.

    更新日期:2019-10-25
  • The effect of Cd- substitution on the Raman vibrational characteristics of sphalerite
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-09-17
    L. Babedi, B.P. von der Heyden, P.H. Neethling, M. Tadie

    The structural and electronic properties of sphalerite (ZnS) are strongly dependent on the presence of trace metal substituents, which thereby impact the industrial applicability of this important semi-conducting mineral phase. Cadmium (a 4d transition metal) commonly substitutes into the sphalerite mineral structure, yet the geochemical effects of this substitution reaction have not been fully defined. Here we present novel Raman and X-ray Diffraction (XRD) data collected from Cd-bearing synthetic sphalerite samples which explicitly test the influences of Cd substitution on the crystal structure and the surface bonding environment of the ZnS host molecular cluster. The XRD analyses revealed significant shifts in the measured Bragg’s peak positions, which manifest as a linear increase in the calculated unit cell parameter for sphalerite as a function of the local distortions arising from the increasing Cd concentration. These structural and chemical changes are further reflected in the Raman spectra, in which Cd substitution gives rise to a new Raman active mode occurring at 295 cm−1 and which we attribute to Cd-S bond vibrations. The intensity ratio between this Cd-S bond vibrational mode, and the Transverse Optic (TO) mode of the Zn-S bond correlates positively (r2 = 0.9403) with the concentration of Cd substituted into the sphalerite structure. Our work thus highlights the applicability of Raman spectroscopy for identifying the presence and concentration of Cd in sphalerite, and in doing so, fills an existing knowledge gap related to the influence of Cd on the vibrational characteristics of this important semi-conducting mineral phase.

    更新日期:2019-10-25
  • Investigations of the Neolithic potteries of 6th millennium BC from Göytepe-Azerbaijan by vibrational spectroscopy and chemometric techniques
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-10-03
    Sevim Akyuz, Farhad Guliyev, Sefa Celik, Aysen E. Ozel, Valeh Alakbarov

    This article presents the results of the vibrational spectroscopic and chemometric analyses of Neolithic pottery remains excavated in Göytepe (Azerbaijan), a typical Shomutepe-Shulaveri culture settlement. Fifty-five pottery fragments, that were unearthed in the excavations of Göytepe during the 2009–2013 years, were investigated using Fourier Transform Infrared (FTIR) and micro-Raman spectroscopy. X-Ray Diffraction (XRD) was used as a complementary technique. The firing-temperature and -conditions were inferred from the mineral phases obtained from the vibrational spectra of the samples and were estimated to be between 600 °C and 750 °C in oxidizing atmosphere. As chemometrics, Principal Component Analysis (PCA) followed by Linear Discriminant Analysis (LDA), were applied to the FTIR spectral data, in order to examine the possible classification of those findings, and to extract the most discriminant features. Pottery fragments were identified and characterized, depending on the excavation levels, by PCA-LDA analysis.

    更新日期:2019-10-25
  • Monitoring of Breast cancer patients under pre and post treated conditions using Raman Spectroscopic Analysis of blood plasma
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-10-19
    Chithra Krishnamoorthy, Aruna Prakasarao, Vijayaraghavan Srinivasan, Sivarama Prasad G.N., Ganesan Singaravelu

    This study is aimed to monitor the therapeutic response in breast cancer patients, by using the Raman spectra of liquid blood plasma of biopsy proved 19 breast cancer patients under pre and post treatment conditions and also by comparing them with the spectra of control group, consisting of 26 normal subjects (with no significant history of illness) in the same age group. The results indicate that there exists a statistical significance in the spectral signatures between the normal and breast cancer patient’s blood plasma as well as between pre treated and post treated plasma, which may be attributed to the changes in the vibrational characteristics of some of the key biomolecules viz tyrosine, phenylalanine, methionine, tryptophan, lipids / phospholipids, amides, DNA base pairs(adenine and guanine) etc. Further, it is found that the spectral signatures of post treated plasma (after completion of the entire course of treatment) are almost matching with that of normal subjects. The results of the study indicates the possibility of using Raman Spectroscopy for diagnosis as well as for monitoring of treatment response in breast cancer patients.

    更新日期:2019-10-25
  • Infrared and Raman spectroscopy of tschermigite, (NH4)Al(SO4)2•12H2O
    Vib. Spectrosc. (IF 1.861) Pub Date : 2019-10-18
    Anastasia V. Sergeeva, Elena S. Zhitova, Vladimir N. Bocharov

    Tschermigite, (NH4)Al(SO4)2·12H2O, is a rather rare mineral of the alum group that occurs in such environments as burning coal seams, guano deposits and volcanic-related conditions in association with other hydrated sulphates. The remote identification of hydrated ammonium sulphates is relevant to volcanology and Martian mineralogy and require detailed vibrational characterization of reference species of which tschermigite can serve. The study provides analysis of infrared and Raman spectra of the mineral tschermigite that originate from low-temperature volcanic (geothermal) environment at Southern Kamchatka, Russia. The detailed analysis of tschermigite infrared and Raman spectra revealed that its signatures agree with structural and chemical characteristics. However, it was possible to distinguish stretching vibrations of ammonium ion from those of water molecules by infrared (8030, 6430, 3203, 3045, 2843 cm-1) and Raman (∼ 3163, 2883 cm-1) spectroscopy. The bending vibrations of ammonium are found ∼ 1680 cm-1, whereas H ˗ O˗H bending occurs ∼ 1630 cm-1. The data were compared to other hydrated ammonium sulphates, hydrated non-ammonium sulphates and mascagnite, (NH4)2SO4.

    更新日期:2019-10-25
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
加州大学洛杉矶分校
上海纽约大学William Glover
南开大学化学院周其林
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug