Subjects -> CHEMISTRY (Total: 986 journals)
    - ANALYTICAL CHEMISTRY (58 journals)
    - CHEMISTRY (715 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (44 journals)
    - ORGANIC CHEMISTRY (48 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (715 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 19)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 34)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 2)
ACS Catalysis     Hybrid Journal   (Followers: 60)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 23)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 30)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 48)
ACS Nano     Hybrid Journal   (Followers: 416)
ACS Photonics     Hybrid Journal   (Followers: 17)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 31)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 9)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 11)
Adsorption Science & Technology     Open Access   (Followers: 8)
Advanced Electronic Materials     Hybrid Journal   (Followers: 3)
Advanced Functional Materials     Hybrid Journal   (Followers: 72)
Advanced Science Focus     Free   (Followers: 6)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 1)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 94)
Advances in Chemical Science     Open Access   (Followers: 37)
Advances in Chemistry     Open Access   (Followers: 31)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Environmental Chemistry     Open Access   (Followers: 10)
Advances in Enzyme Research     Open Access   (Followers: 12)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 31)
Advances in Nanoparticles     Open Access   (Followers: 19)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Polymer Science     Hybrid Journal   (Followers: 49)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 15)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 4)
Alchemy : Jurnal Penelitian Kimia     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 36)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 15)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 203)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 318)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 5)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 10)
Applied Spectroscopy     Full-text available via subscription   (Followers: 26)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 7)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 4)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 446)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 10)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 3)
Biomacromolecules     Hybrid Journal   (Followers: 24)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 200)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 4)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Research     Hybrid Journal   (Followers: 23)
Carbon     Hybrid Journal   (Followers: 74)
Catalysis for Sustainable Energy     Open Access   (Followers: 10)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 11)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 14)
Cellulose     Hybrid Journal   (Followers: 13)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 2)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 23)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 81)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Letters : X     Open Access   (Followers: 2)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 24)
Chemical Reviews     Hybrid Journal   (Followers: 246)
Chemical Science     Open Access   (Followers: 36)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 54)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 9)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 209)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 24)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry Education Review     Open Access   (Followers: 2)
Chemistry in Education     Open Access   (Followers: 8)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 47)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 308)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 21)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 12)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Ciencia     Open Access   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 12)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 7)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 23)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access   (Followers: 3)
Composite Interfaces     Hybrid Journal   (Followers: 9)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 2)

        1 2 3 4 | Last

Similar Journals
Journal Cover
Applied Spectroscopy
Journal Prestige (SJR): 0.489
Citation Impact (citeScore): 2
Number of Followers: 26  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0003-7028 - ISSN (Online) 1943-3530
Published by Sage Publications Homepage  [1089 journals]
  • Advertising and Front Matter
    • Pages: 495 - 506
      Abstract: Applied Spectroscopy, Volume 74, Issue 5, Page 495-506, May 2020.

      Citation: Applied Spectroscopy
      PubDate: 2020-05-11T09:30:46Z
      DOI: 10.1177/0003702820925009
      Issue No: Vol. 74, No. 5 (2020)
       
  • Influence of Gamma Ray Irradiation on the Optical Properties of Calcite
           and Dolomite
    • Authors: Hélio José Lucas Junior, Celso de Araujo Duarte, Melissa Wilm Senna Pinto, Dietmar William Foryta, Bruno Guimarães Titon, Eleonora Maria Gouvea Vasconcellos
      Pages: 507 - 514
      Abstract: Applied Spectroscopy, Volume 74, Issue 5, Page 507-514, May 2020.
      The class of carbonaceous chondrite meteorites has carbon in their structures, similarly to the terrestrial calcite and dolomite rocks, and contains the group =CO3 linked to Ca and/or Mg, which may be, in principle, more susceptible to the action of the spatial gamma radiation (γ–R) due to the presence of these light-atom elements. On the present work, we used a variety of optical techniques to investigate the possible effects of γ–R produced by an artificial 192Ir source in terrestrial calcite and dolomite, which may allow to understand the effect of the spatial radiation in that celestial bodies of the solar system. As a result, we verified that the γ–R irradiation caused the effect of untrapping of electrons from deep color centers, that spatially migrate to other color centers on the samples, resulting on the change of the electron energetic configuration.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-11T09:30:29Z
      DOI: 10.1177/0003702819865935
      Issue No: Vol. 74, No. 5 (2020)
       
  • Raman Spectroscopy: An Exploratory Study to Identify Post-Radiation Cell
           Survival
    • Authors: Kshama Pansare, Saurav Raj Singh, Venkatavaradhan Chakravarthy, Neha Gupta, Arti Hole, Poonam Gera, Rajiv Sarin, Chilakapati Murali Krishna
      Pages: 553 - 562
      Abstract: Applied Spectroscopy, Volume 74, Issue 5, Page 553-562, May 2020.
      Resistance to radiotherapy has been an impediment in the treatment of cancer, and the inability to detect it at an early stage further exacerbates the prognosis. We have assessed the feasibility of Raman spectroscopy as a rapid assay for predicting radiosensitivity of cancer cells in comparison to the conventional biological assays. Cell lines derived from breast adenocarcinoma (MCF7), gingivobuccal squamous cell carcinoma (ITOC-03), and human embryonic kidney (HEK293) were subjected to varying doses of ionizing radiation. Cell viability of irradiated cells was assessed at different time points using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and Raman spectroscopy, and colony-forming capability was evaluated by clonogenic assay. Radiosensitivity observed using MTT assay was limited by the finding of similar cell viability in all the three cell lines 24 h post-irradiation. However, cell survival assessed using clonogenic assay and principal component linear discriminant analysis (PC-LDA) classification of Raman spectra showed correlating patterns. Irradiated cells showed loss of nucleic acid features and enhancement of 750 cm−1 peak probably attributing to resonance Raman band of cytochromes in all three cell lines. PC-LDA analysis affirmed MCF7 to be a radioresistant cell line as compared to ITOC-03 and HEK293 to be the most radiosensitive cell line. Raman spectroscopy is shown to be a rapid and alternative assay for identification of radiosensitivity as compared to the gold standard clonogenic assay.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-11T09:30:12Z
      DOI: 10.1177/0003702820908352
      Issue No: Vol. 74, No. 5 (2020)
       
  • Depth Profiling Investigation of Seawater Using Combined Multi-Optical
           Spectrometry
    • Authors: Wangquan Ye, Jinjia Guo, Nan Li, Fujun Qi, Kai Cheng, Ronger Zheng
      Pages: 563 - 570
      Abstract: Applied Spectroscopy, Volume 74, Issue 5, Page 563-570, May 2020.
      Depth profiling investigation plays an important role in studying the dynamic processes of the ocean. In this paper, a newly developed hyphenated underwater system based on multi-optical spectrometry is introduced and used to measure seawater spectra at different depths with the aid of a remotely operated vehicle (ROV). The hyphenated system consists of two independent compact deep-sea spectral instruments, a deep ocean compact autonomous Raman spectrometer and a compact underwater laser-induced breakdown spectroscopy system for sea applications (LIBSea). The former was used to take both Raman scattering and fluorescence of seawater, and the LIBS signal could be recorded with the LIBSea. The first sea trial of the developed system was taken place in the Bismarck Sea, Papua New Guinea, in June 2015. Over 4000 multi-optical spectra had been captured up to the diving depth about 1800 m at maximum. The depth profiles of some ocean parameters were extracted from the captured joint Raman–fluorescence and LIBS spectra with a depth resolution of 1 m. The concentrations of [math] and the water temperatures were measured using Raman spectra. The fluorescence intensities from both colored dissolved organic matter (CDOM) and chlorophyll were found to be varied in the euphotic zone. With LIBS spectra, the depth profiles of metallic elements were also obtained. The normalized intensity of atomic line Ca(I) extracted from LIBS spectra raised around the depth of 1600 m, similar to the depth profile of CDOM. This phenomenon might be caused by the nonbuoyant hydrothermal plumes. It is worth mentioning that this is the first time Raman and LIBS spectroscopy have been applied simultaneously to the deep-sea in situ investigations.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-11T09:29:50Z
      DOI: 10.1177/0003702820906890
      Issue No: Vol. 74, No. 5 (2020)
       
  • A Normalized Difference Spectral Recognition Index for Azurite Pigment
    • Authors: Taixia Wu, Bo Yuan, Shudong Wang, Guanghua Li, Yong Lei
      Pages: 571 - 582
      Abstract: Applied Spectroscopy, Volume 74, Issue 5, Page 571-582, May 2020.
      Hyperspectral technology is a nondestructive, fast, and reliable method for the detection and restoration of relics. Most of the band characteristics of mineral pigment are concentrated between 2200 and 2400 nm, and these data are expensive to obtain (the required imaging sensor is expensive). We are pursuing a hyperspectral index mean that can effectively distinguish pigments in shorter band ranges to achieve high application value that is much less expensive. In this study, based on the spectral features of azurite at 400–1500 nm, we created an azurite normalized difference spectral index (ANDSI) through feature band selection, derivation of characteristic formulae, and discrimination analysis. Reflectivity bands at 458, 806, and 1373 nm were selected to build the ANDSI. Azurite was compared with 25 other common pigments and it was found that the discrimination values between azurite and the other pigments exceeded 0.88 (where values>0.5 indicate discriminable pigments), demonstrating that the ANDSI is suitable for detecting azurite.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-11T09:30:46Z
      DOI: 10.1177/0003702820909435
      Issue No: Vol. 74, No. 5 (2020)
       
  • Restoration Method of Hadamard Coding Spectral Imager
    • Authors: Xingjia Tang, Zongben Xu, Libo Li, Shuang Wang, Bingliang Hu, Feng Wang
      Pages: 583 - 596
      Abstract: Applied Spectroscopy, Volume 74, Issue 5, Page 583-596, May 2020.
      Hadamard coding spectral imaging technology is a computational spectral imaging technology, which modulates the target’s spectral information and recovers the original spectrum by inverse transformation. Because it has the advantage of multichannel detection, it is being studied by more researchers. For the engineering realization of push-broom coding spectral imaging instrument, it will inevitably be subjected to push-broom error, template error and detection noise, the redundant sampling problem caused by detector. Therefore, three restoration methods are presented in this paper: firstly, the one is the least squares solution, the two is the zero-filling inverse solution by extending the coding matrix in the redundant coding state to a complete higher order Hadamard matrix, the three is sparse method. Secondly, the numerical and principle analysis shows that the inverse solution of zero-compensation has better robustness and is more suitable for engineering application; its conditional number, error expectation and covariance are better and more stable because it directly uses Hadamard matrix, which has good generalized orthogonality. Then, a real-time spectral reconstruction method is presented, which is based on inverse solution of zero-compensation. Finally, simulation analysis shows that spectral data could be destructed relative accuracy in the error condition; however, the effect of template noise and push error on reconstruction is much greater than that of detection error. Therefore, in addition to reducing the detection noise as much as possible, lower template noise and more accurate push controlling should be guaranteed specifically in engineering realization.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-11T09:30:06Z
      DOI: 10.1177/0003702819900381
      Issue No: Vol. 74, No. 5 (2020)
       
  • Comparison of Individual and Integrated Inline Raman, Near-Infrared, and
           Mid-Infrared Spectroscopic Models to Predict the Viscosity of Micellar
           Liquids
    • Authors: Kiran Haroon, Ali Arafeh, Stephanie Cunliffe, Philip Martin, Thomas Rodgers, Ćesar Mendoza, Michael Baker
      Abstract: Applied Spectroscopy, Ahead of Print.
      In many industries, viscosity is an important quality parameter which significantly affects consumer satisfaction and process efficiency. In the personal care industry, this applies to products such as shampoo and shower gels whose complex structures are built up of micellar liquids. Measuring viscosity offline is well established using benchtop rheometers and viscometers. The difficulty lies in measuring this property directly in the process via on or inline technologies. Therefore, the aim of this work is to investigate whether proxy measurements using inline vibrational spectroscopy, e.g., near-infrared (NIR), mid-infrared (MIR), and Raman, can be used to predict the viscosity of micellar liquids. As optical techniques, they are nondestructive and easily implementable process analytical tools where each type of spectroscopy detects different molecular functionalities. Inline fiber optic coupled probes were employed; a transmission probe for NIR measurements, an attenuated total reflectance probe for MIR and a backscattering probe for Raman. Models were developed using forward interval partial least squares variable selection and log viscosity was used. For each technique, combinations of pre-processing techniques were trialed including detrending, Whittaker filters, standard normal variate, and multiple scatter correction. The results indicate that all three techniques could be applied individually to predict the viscosity of micellar liquids all showing comparable errors of prediction: NIR: 1.75 Pa s; MIR: 1.73 Pa s; and Raman: 1.57 Pa s. The Raman model showed the highest relative prediction deviation (RPD) value of 5.07, with the NIR and MIR models showing slightly lower values of 4.57 and 4.61, respectively. Data fusion was also explored to determine whether employing information from more than one data set improved the model quality. Trials involved weighting data sets based on their signal-to-noise ratio and weighting based on transmission curves (infrared data sets only). The signal-to-noise weighted NIR–MIR–Raman model showed the best performance compared with both combined and individual models with a root mean square error of cross-validation of 0.75 Pa s and an RPD of 10.62. This comparative study provides a good initial assessment of the three prospective process analytical technologies for the measurement of micellar liquid viscosity but also provides a good basis for general measurements of inline viscosity using commercially available process analytical technology. With these techniques typically being employed for compositional analysis, this work presents their capability in the measurement of viscosity—an important physical parameter, extending the applicability of these spectroscopic techniques.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-29T03:56:33Z
      DOI: 10.1177/0003702820924043
       
  • Differentiating Between Malignant Mesothelioma and Other Pleural Lesions
           Using Fourier Transform Infrared Spectroscopy
    • Authors: Fatlinda Sadiku-Zehri, Ozren Gamulin, Marko Škrabić, Ardita Qerimi-Krasniqi, Filip Sedlić, Ana Šepac, Luka Brčić, Lovorka Batelja Vuletić, Sven Seiwerth
      Abstract: Applied Spectroscopy, Ahead of Print.
      Histopathology, despite being the gold standard as a diagnostic tool, does not always provide a correct diagnosis for different pleural lesions. Although great progress was made in this field, the problem to differentiate between reactive and malignant pleural lesions still stimulates the search for additional diagnostic tools. Our research using vibrational spectroscopy and principal component analysis (PCA) statistical modeling represents a potentially useful tool to approach the problem. The objective method this paper explores is based on the correlation between different types of pleural lesions and their vibrational spectra. Obtained tissue spectra recorded by infrared spectroscopy allowed us to categorize spectra in different groups using a created PCA statistical model. The PCA model was built using tissues of known pathology as the model group. The validation samples were then used to confirm the functionality of our PCA model. Student’s t-test was also used for comparing samples in paired groups. The PCA model was able to clearly differentiate the spectra of mesothelioma, metastasis and reactive changes (inflammation), and place them in discrete groups. Thus, we showed that Fourier transform infrared spectroscopy combined with PCA can differentiate pleural lesions with high sensitivity and specificity. This new approach could contribute in objectively differentiating specific pleural lesions, thus helping pathologists to better diagnose difficult pleural samples but also could shed additional light into the biology of malignant pleural mesothelioma.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-29T03:55:43Z
      DOI: 10.1177/0003702820924726
       
  • Nanoscale Spatial Resolution in Far-Field Raman Imaging Using
           Hyperspectral Unmixing in Combination with Positivity Constrained
           Super-Resolution
    • Authors: Dominik J. Winterauer, Daniel Funes-Hernando, Jean-Luc Duvail, Saïd Moussaoui, Tim Batten, Bernard Humbert
      Abstract: Applied Spectroscopy, Ahead of Print.
      This work introduces hyper-resolution (HyRes), a numerical approach for spatial resolution enhancement that combines hyperspectral unmixing and super-resolution image restoration (SRIR). HyRes yields a substantial increase in spatial resolution of Raman spectroscopy while simultaneously preserving the undistorted spectral information. The resolving power of this technique is demonstrated on Raman spectroscopic data from a polymer nanowire sample. Here, we demonstrate an achieved resolution of better than 14 nm, a more than eightfold improvement on single-channel image-based SRIR and [math] better than regular far-field Raman spectroscopy, and comparable to near-field probing techniques.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-26T09:02:00Z
      DOI: 10.1177/0003702820920688
       
  • Micro-Electro-Mechanical System Fourier Transform Infrared (MEMS FT-IR)
           Spectrometer Under Modulated–Pulsed Light Source Excitation
    • Authors: Ahmed M. Othman, Hussein E. Kotb, Yasser M. Sabry, Diaa Khalil
      Abstract: Applied Spectroscopy, Ahead of Print.
      Miniaturized Fourier transform infrared (FT-IR) spectrometers suffer from limited optical throughput due to their tiny aperture size. Therefore, coherent wideband sources with high brightness can provide an advantage over the wideband thermal radiation sources. However, the former ones are available based on pulsed operation. In this work, we present and study a miniaturized FT-IR spectrometer with pulsed light sources including chopped thermal source, semiconductor optical amplifier, Q-switched and femtosecond mode-locked laser sources. A system model for the FT-IR spectrometer system under a modulated input light source is presented. The model accounts for the relatively high scanning speed of the micro-electro-mechanical system (MEMS) interferometer. The signal-to-noise ratio of the spectrometer, due to the light source modulation, is calculated at different values of modulation repetition rate ranging from 20 Hz to 2 MHz, and duty cycle values ranging from 1% to 50%. An analytical expression for the worst-case repetition rate for the spectrometer system is derived. The model results are verified by experimental measurements showing good agreement with the theoretical expectations. Spectroscopic measurements for CO2 gas with pressure ranging from 300 mbar to 700 mbar are also performed using a high-repetition rate source, and the measured spectra agree with the simulation results demonstrating the utility of the spectrometer.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-26T08:59:26Z
      DOI: 10.1177/0003702819886091
       
  • Sample-Specific Prediction Error Measures in Spectroscopy
    • Authors: Carl Emil Eskildsen, Tormod Næs
      Abstract: Applied Spectroscopy, Ahead of Print.
      In applied spectroscopy, the purpose of multivariate calibration is almost exclusively to relate analyte concentrations and spectroscopic measurements. The multivariate calibration model provides estimates of analyte concentrations based on the spectroscopic measurements. Predictive performance is often evaluated based on a mean squared error. While this average measure can be used in model selection, it is not satisfactory for evaluating the uncertainty of individual predictions. For a calibration, the uncertainties are sample specific. This is especially true for multivariate calibration, where interfering compounds may be present. Consider in-line spectroscopic measurements during a chemical reaction, production, etc. Here, reference values are not necessarily available. Hence, one should know the uncertainty of a given prediction in order to use that prediction for telling the state of the chemical reaction, adjusting the process, etc. In this paper, we discuss the influence of variance and bias on sample-specific prediction errors in multivariate calibration. We compare theoretical formulae with results obtained on experimental data. The results point towards the fact that bias contribution cannot necessarily be neglected when assessing sample-specific prediction ability in practice.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-26T08:57:48Z
      DOI: 10.1177/0003702820913562
       
  • Monitoring the Progress and Healing Status of Burn Wounds Using Infrared
           Spectroscopy
    • Authors: Pedro A.A. Castro, Cassio A. Lima, Mychel R.P.T. Morais, Telma M.T. Zorn, Denise M. Zezell
      Abstract: Applied Spectroscopy, Ahead of Print.
      Burns are one of the leading causes of morbidity worldwide and the most costly traumatic injuries. A better understanding of the molecular mechanisms in wound healing is required to accelerate tissue recovery and reduce the health economic impact. However, the standard techniques used to evaluate the biological events associated to wound repair are laborious, time-consuming, and/or require multiple assays/staining. Therefore, this study aims to evaluate the feasibility of Fourier transform infrared (FT-IR) spectroscopy to monitor the progress and healing status of burn wounds. Burn injuries were induced on Wistar rats by water vapor exposure and biopsied for further histopathological and spectroscopic evaluation at four time-points (3, 7, 14, and 21 days). Spectral data were preprocessed and compared by principal component analysis. Pairwise comparison of post-burn groups to each other revealed that metabolic activity induced by thermal injury decreases as the healing progresses. Higher amounts of carbohydrates, proteins, lipids, and nucleic acids were evidenced on days 3 and 7 compared to healthy skin and reduced amounts of these molecular structural units on days 14 and 21 post-burn. FT-IR spectroscopy was used to determine the healing status of a wound based on the biochemical information retained by spectral signatures in each phase of healing. Our findings demonstrate that FT-IR spectroscopy can monitor the biological events triggered by burn trauma as well as to detect the wound status including full recovery based on the spectral changes associated to the biochemical events in each phase.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-18T11:20:20Z
      DOI: 10.1177/0003702820919446
       
  • Simplified Ab Initio Molecular Dynamics-Based Raman Spectral Simulations
    • Authors: Edoardo Aprà, Ashish Bhattarai, Eric Baxter, ShanYi Wang, Grant E. Johnson, Niranjan Govind, Patrick Z. El-Khoury
      Abstract: Applied Spectroscopy, Ahead of Print.
      We describe a simplified approach to simulating Raman spectra from ab initio molecular dynamics (AIMD) calculations. The protocol relies on on-the-fly calculations of approximate molecular polarizabilities using the well-known sum over orbitals (as opposed to states) method. This approach bypasses the more accurate but computationally expensive approach to calculating molecular polarizabilities along AIMD trajectories, i.e., solving the coupled perturbed Hartree–Fock/Kohn–Sham equations. We demonstrate the advantages and limitations of our method through a few case studies targeting molecular systems of interest to surface- and/or tip-enhanced Raman spectroscopy practitioners.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-18T11:17:09Z
      DOI: 10.1177/0003702820923392
       
  • Mid-Infrared Reflectance Spectroscopy of Oil Sands Minerals Based on
           Tunable Quantum Cascade Lasers
    • Authors: Aïssa Harhira, Francis Vanier, Christian Padioleau, Josette El Haddad, Alain Blouin
      Abstract: Applied Spectroscopy, Ahead of Print.
      Minerals play an important role in the oil sands extraction efficiency. It is thus important to assess the major mineral abundance in oil sands ores. This paper presents the application of tunable quantum cascade lasers for mid-infrared reflectance spectroscopy on oil sands minerals. The investigations and results show a new tool to determine oil sands mineral type and to determine potentially quartz and clay contents.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-04T09:47:40Z
      DOI: 10.1177/0003702820906489
       
  • Interactions of Glycerol, Diglycerol, and Water Studied Using Attenuated
           Total Reflection Infrared Spectroscopy
    • Authors: Akari Habuka, Takeshi Yamada, Satoru Nakashima
      Abstract: Applied Spectroscopy, Ahead of Print.
      In order to examine the mixing properties of glycerol–water and diglycerol–water solutions, these solutions were measured using attenuated total reflection infrared spectroscopy. The absorbance spectra corrected for 1 µm thickness were subtracted by pure polyols for obtaining water spectra, and by pure water for polyol spectra. Both asymmetric and symmetric CH2 stretching vibration bands (around 2940, 2885 cm−1) shifted about 10 cm−1 to lower wavenumber side (redshifts) with increasing polyol concentrations, especially at higher concentrations. Redshifts of C–O–H rocking bands (around 1335 cm−1) with increasing polyol concentrations are slightly larger for diglycerol–water (10 > 6 cm−1) than glycerol–water solutions. C–O stretching bands of CHOH groups (1125 and 1112 cm−1) shift slightly but in opposite sides for glycerol and diglycerol at highest polyol concentrations (90–100 wt%). These shifts of CH2 stretching, COH rocking, and CO stretching of CHOH at higher polyol concentrations suggest interactions of outer CH2 with inner CHOH groups of surrounding polyols. The normalized band area changes with polyol concentrations could be fitted by quadratic polynomials possibly due to mixtures of different interactions between water–water, polyol–water, and polyol–polyol molecules. The OH stretching band for diglycerol 90 wt% shows three humps indicating at least three OH components: long, medium, and short H bond water molecules. Short H bond water molecules are the major component possibly between inner CHOH and outer side CH2OH groups, while the long H component might loosely bind to outer CH2OH groups.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-04T09:44:40Z
      DOI: 10.1177/0003702820919530
       
  • Chemical Bleaching to Minimize Fluorescence Interference in Raman
           Spectroscopic Measurements for Sulfonated Polystyrene Solutions
    • Authors: Boyu Li, Peter J. Larkin
      Abstract: Applied Spectroscopy, Ahead of Print.
      Auto-fluorescence is a significant challenge for Raman spectroscopic analyses. Since fluorescence is a much stronger phenomenon than Raman scattering, even trace fluorescent impurities can overwhelm the Raman signal. Strategies to minimize fluorescence interference in Raman measurements include either an instrumental-based approach or treatment of the sample itself to minimize fluorescence. Efforts focused on sample-based treatments to reduce fluorescence interferences have generally focused on sample purification and photobleaching methodologies. In this work, we present a sample treatment approach based upon chemical bleaching to remove fluorescence from Raman measurements of aqueous solutions of sulfonated polystyrene (SPS). Synthetic batches of SPS are characterized by a wide variation in fluorescence from minimum to a catastrophic level, which greatly limits the use of Raman spectroscopy. We systematically investigate the efficacy of various sample-based treatments of the SPS samples. An important acceptance criterion is that the procedure effectively and reliably removes fluorescence without damaging the SPS component. The chemical bleaching, which involves the addition of hydrogen peroxide and incubation at 60 ℃, is found to be highly effective. The parameters affecting the bleaching efficacy are studied, including temperature, hydrogen peroxide dosage, and bleaching time. Classification models are then developed based on the drastically diverse fluorescence background levels in Raman spectra of SPS to help optimize bleaching time for each specific sample. This work serves as an example of using chemical bleaching to remove fluorescence, which is inexpensive and readily available. It can facilitate a broader use of Raman spectroscopy as a quantitative qualitative control method in industrial settings.
      Citation: Applied Spectroscopy
      PubDate: 2020-05-04T09:37:40Z
      DOI: 10.1177/0003702820919823
       
  • Vibrational Spectroscopic Characterization and Coherent Anti-Stokes Raman
           Spectroscopy (CARS) Imaging of Artepillin C
    • Authors: Wallance M. Pazin, Leonardo N. Furini, Vita Solovyeva, Tibebe Lemma, Rafael J. G. Rubira, Bjarke Jørgensen, Carlos J. L. Constantino, Jonathan R. Brewer
      Abstract: Applied Spectroscopy, Ahead of Print.
      In the following work, the vibrational spectroscopic characteristics of artepillin C are reported by means of Fourier transform infrared (FT-IR) and Raman spectroscopies, surface-enhanced Raman scattering (SERS), and coherent anti-Stokes Raman scattering (CARS) microscopy. Artepillin C is an interesting compound due to its pharmacological properties, including antitumor activity. It is found as the major component of Brazilian green propolis, a resinous mixture produced by bees to protect their hives against intruders. Vibrational spectroscopic techniques have shown a strong peak at 1599 cm−1, assigned to C=C stretching vibrations from the aromatic ring of artepillin C. From these data, direct visualization of artepillin C could be assessed by means of CARS microscopy, showing differences in the film hydration obtained for its neutral and deprotonated states. Raman-based methods show potential to visualize the uptake and action of artepillin C in biological systems, triggering its interaction with biological systems that are needed to understand its mechanism of action.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-30T02:19:18Z
      DOI: 10.1177/0003702820904456
       
  • Potentialities of a Laser-Induced Breakdown Spectroscopy Technique in the
           Study of Polymer Composites
    • Authors: Sebastián Tognana, Cristian D'Angelo, Walter Salgueiro, Susana Montecinos
      Abstract: Applied Spectroscopy, Ahead of Print.
      A laser-induced breakdown spectroscopy (LIBS) technique was used to evaluate the filler content in particulate epoxy–copper composites. A potential application for a direct and fast measurement of the filler in composites through the LIBS results is suggested using calibrated samples. The methodology used in this work makes possible the incorporation of LIBS as a quantitative technique for the study of particle metal-filled epoxy composites, providing a method to obtain a direct estimation of the filler volume fraction.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-27T08:27:01Z
      DOI: 10.1177/0003702820918282
       
  • Microplastics Differ Between Indoor and Outdoor Air Masses: Insights from
           Multiple Microscopy Methodologies
    • Authors: Emily Gaston, Mary Woo, Clare Steele, Suja Sukumaran, Sean Anderson
      Abstract: Applied Spectroscopy, Ahead of Print.
      The abundance and distribution of microplastic (
      Citation: Applied Spectroscopy
      PubDate: 2020-04-27T08:25:03Z
      DOI: 10.1177/0003702820920652
       
  • A Comparative Approach to Screen the Capability of Raman and Infrared
           (Mid- and Near-) Spectroscopy for Quantification of Low-Active
           Pharmaceutical Ingredient Content Solid Dosage Forms: The Case of
           Alprazolam
    • Authors: Liljana Makraduli, Petre Makreski, Katerina Goracinova, Stefan Stefov, Maja Anevska, Nikola Geskovski
      Abstract: Applied Spectroscopy, Ahead of Print.
      Content uniformity is a critical attribute for potent and low-dosage formulations of active pharmaceutical ingredient (API) that, in addition to the formulation parameters, plays pivotal role during pharmaceutical development and production. However, when API content is low, implementing a vibrational spectroscopic analytical tool to monitor the content and blend uniformity remains a challenging task. The aim of this study was to showcase the potentials of mid-infrared (MIR), near-infrared (NIR), and Raman spectroscopy for quantitative analysis of alprazolam (ALZ) in a low-content powder blends with lactose, which is used as a common diluent for tablets produced by direct compression. The offered approach might be further scaled up and exploited for potential application in the process analytical technology (PAT). Partial least square and orthogonal PLS (OPLS) methodologies were employed to build the calibration models from raw and processed spectral data (standard normal variate, first and second derivatives). The models were further compared regarding their main statistical indicators: correlation coefficients, predictivity, root mean square error of estimation (RMSEE), and root mean square error of cross-validation (RMSEEcv). All statistical models presented high regression and predictivity coefficients. The RMSEEcv for the optimal models was 1.118, 0.08, and 0.059% for MIR, NIR, and Raman spectroscopy, respectively. The scarce information content extracted from the ALZ NIR spectra and the major band overlapping with those from lactose monohydrate was the main culprit of poor accuracy in the NIR model, whereas the subsampling instrumental setup (resulting in a non-representative spectral acquisition of the sample) was regarded as a main limitation for the MIR-based calibration model. The OPLS models of the Raman spectra of the powder blends manifested favorable statistical indicators for the accuracy of the calibration model, probably due to the distinctive ALZ Raman pattern resulting in the largest number of predictive spectral points that were used for the mathematical modeling. Furthermore, the Raman scattering calibration model was optimized in narrower scanning range (1700–700 cm−1) and its prediction power was evaluated (root mean square error of prediction, RMSEP = 0.03%). Thus, the Raman spectroscopy presented the most favorable statistical indicators in this comparative study and therefore should be further considered as a PAT for the quantitative determination of ALZ in low-content powder blends.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-09T09:07:24Z
      DOI: 10.1177/0003702820905367
       
  • Photoacoustic Spectroscopy of Surface-Functionalized Fe3O4–SiO2
           Nanoparticles
    • Authors: Mateusz Pawlaczyk, Sylwia Pasieczna-Patkowska, Grzegorz Schroeder
      Abstract: Applied Spectroscopy, Ahead of Print.
      A permanent development of hybrid materials based on the highly absorptive or opaque materials has prompted a need of analytical tools, which are able to overcome obstacles connected with their physicochemical features. Iron oxide (II, III) (Fe3O4) nanoparticles gained a huge attention as supporters, as they are not only easily accessible using various synthetic approaches, but they also exhibit homogeneity and paramagnetic properties, which make them easily separable materials. Nevertheless, the classic infrared spectroscopic studies might meet several problems with characterization of such systems. Therefore, infrared spectroscopy in photoacoustic mode using Fourier transform infrared–photoacoustic infrared spectroscopy (FT-IR PAS) can be an extremely sensitive and exact analytical tool for investigation of the magnetite-based hybrid material surface. Herein, we present a synthesis of Fe3O4 nanoparticles using co-precipitation method with their subsequent encapsulation within silica matrix decorated with different silanes containing various terminal functional groups. The proper syntheses of core/shell structures were confirmed using the FT-IR PAS method. Each spectrum exhibited specific bands corresponding to vibrations of magnetite particles, silica lattice, and particular surface functional groups, which strictly indicated successful grafting of silanes onto Fe3O4 surface.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-08T11:37:57Z
      DOI: 10.1177/0003702820913647
       
  • Differentiation of Edible Oils by Type Using Raman Spectroscopy and
           Pattern Recognition Methods
    • Authors: Francis Kwofie, Barry K. Lavine, Joshua Ottaway, Karl Booksh
      Abstract: Applied Spectroscopy, Ahead of Print.
      The application of Raman spectroscopy and pattern recognition methods to the problem of discriminating edible oils by type was investigated. Two-hundred and eighty-six Raman spectra obtained from 53 samples spanning 15 varieties of edible oils were collected for 90 s at 2 cm–1 resolution. Employing a Whittaker filter, all Raman spectra were baseline corrected after removing the high-intensity fluorescent background in each spectrum. The Raman spectral data were then examined using the three major types of pattern recognition methodology: mapping and display, discriminant development and clustering. The 15 varieties of edible oils could be partitioned into five distinct groups based on their degree of saturation and the ratio of polyunsaturated fatty acids to monounsaturated fatty acids. Edible oils assigned to one group could be readily differentiated from those assigned to other groups, whereas Raman spectra within the same group more closely resembled each other and therefore would be more difficult to classify by type.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-06T08:56:01Z
      DOI: 10.1177/0003702819888220
       
  • Rapid Screening of Thyroid Dysfunction Using Raman Spectroscopy Combined
           with an Improved Support Vector Machine
    • Authors: Dingding Wang, Jing Jiang, Jiaqing Mo, Jun Tang, Xiaoyi Lv
      Abstract: Applied Spectroscopy, Ahead of Print.
      This study aimed to screen for thyroid dysfunction using Raman spectroscopy combined with an improved support vector machine (SVM). In spectral analysis, in order to further improve the classification accuracy of the SVM algorithm model, a genetic particle swarm optimization algorithm based on partial least squares is proposed to optimize support vector machine (PLS-GAPSO-SVM). In order to evaluate the performance of the algorithm, five optimization algorithms are used: grid search-based SVM (Grid-SVM), particle swarm optimization algorithm-based SVM (PSO-SVM), genetic algorithm-based SVM (GA-SVM), artificial fish coupled uniform design algorithm-based SVM (AFUD-SVM), and simulated annealing particle swarm optimization algorithm-based SVM (SAPSO-SVM). In this experiment, serum samples from 95 patients with confirmed thyroid dysfunction and 90 serum samples from normal thyroid function were used for Raman spectroscopy. The experimental results show that the GAPSO-SVM algorithm has a high average diagnostic accuracy of 95.08% and has high sensitivity and specificity (91.67%, 97.96%). Compared with the traditional optimization algorithm, the algorithm has high diagnostic accuracy, short execution time, and good reliability. It can be seen that Raman spectroscopy combined with GAPSO-SVM diagnostic algorithm has enormous potential in noninvasive screening of thyroid dysfunction.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-01T11:08:56Z
      DOI: 10.1177/0003702820904444
       
  • An Optical Model for Quantitative Raman Microspectroscopy
    • Authors: Joseph Razzell Hollis, David Rheingold, Rohit Bhartia, Luther W. Beegle
      Abstract: Applied Spectroscopy, Ahead of Print.
      Raman spectroscopy is an invaluable technique for identifying compounds by the unique pattern of their molecular vibrations and is capable of quantifying the individual concentrations of those compounds provided that certain parameters about the sample and instrument are known. We demonstrate the development of an optical model to describe the intensity distribution of incident laser photons as they pass through the sample volume, determine the limitations of that volume that may be detected by the spectrometer optics, and account for light absorption by molecules within the sample in order to predict the total Raman intensity that would be obtained from a given, uniform sample such as an aqueous solution. We show that the interplay between the shape and divergence of the laser beam, the position of the focal plane, and the dimensions of the spectrometer slit are essential to explaining experimentally observed trends in deep ultraviolet Raman intensities obtained from both planar and volumetric samples, including highly oriented pyrolytic graphite and binary mixtures of organic nucleotides. This model offers the capability to predict detection limits for organic compounds in different matrices based on the parameters of the spectrometer, and to define the upper/lower limits within which concentration can be reliably determined from Raman intensity for such samples. We discuss the potential to quantify more complex samples, including as solid phase mixtures of organics and minerals, that are investigated by the unique instrument parameters of the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) investigation on the upcoming Mars 2020 rover mission.
      Citation: Applied Spectroscopy
      PubDate: 2020-04-01T03:57:07Z
      DOI: 10.1177/0003702819895299
       
  • Time-Resolved Temperature-Jump Infrared Spectroscopy at a High Repetition
           Rate
    • Authors: Gregory M. Greetham, Ian P. Clark, Benjamin Young, Robby Fritsch, Lucy Minnes, Neil T. Hunt, Mike Towrie
      Abstract: Applied Spectroscopy, Ahead of Print.
      Time-resolved temperature-jump infrared absorption spectroscopy at a 0.5 to 1 kHz repetition rate is presented. A 1 kHz neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pumping an optical parametric oscillator provided>70 µJ, 3.75 µm pump pulses, which delivered a temperature jump via excitation of the O–D stretch of a D2O solution. A 10 kHz train of mid-infrared probe pulses was used to monitor spectral changes following the temperature jump. Calibration with trifluoroacetic acid solution showed that a temperature jump of 10 K lasting for tens of microseconds was achieved, sufficient to observe fast processes in functionally relevant biomolecular mechanisms. Modeling of heating profiles across ≤10 µm path length cells and subsequent cooling dynamics are used to describe the initial 10 µs cooling dynamics of the bulk solution.
      Citation: Applied Spectroscopy
      PubDate: 2020-03-30T08:37:04Z
      DOI: 10.1177/0003702820913636
       
  • Monitor Ionizing Radiation-Induced Cellular Responses with Raman
           Spectroscopy, Non-Negative Matrix Factorization, and Non-Negative Least
           Squares
    • Authors: Xinchen Deng, Ramie Ali-Adeeb, Jeffrey L. Andrews, Phillip Shreeves, Julian J. Lum, Alexandre Brolo, Andrew Jirasek
      Abstract: Applied Spectroscopy, Ahead of Print.
      Radiation therapy (RT) is one of the most commonly prescribed cancer treatments. New tools that can accurately monitor and evaluate individual patient responses would be a major advantage and lend to the implementation of personalized treatment plans. In this study, Raman spectroscopy (RS) was applied to examine radiation-induced cellular responses in H460, MCF7, and LNCaP cancer cell lines across different dose levels and times post-irradiation. Previous Raman data analysis was conducted using principal component analysis (PCA), which showed the ability to extract biological information of glycogen. In the current studies, the use of non-negative matrix factorization (NMF) allowed for the discovery of multiplexed biological information, specifically uncovering glycogen-like and lipid-like component bases. The corresponding scores of glycogen and previously unidentified lipids revealed the content variations of these two chemicals in the cellular data. The NMF decomposed glycogen and lipid-like bases were able to separate the cancer cell lines into radiosensitive and radioresistant groups. A further lipid phenotype investigation was also attempted by applying non-negative least squares (NNLS) to the lipid-like bases decomposed individually from three cell lines. Qualitative differences found in lipid weights for each lipid-like basis suggest the lipid phenotype differences in the three tested cancer cell lines. Collectively, this study demonstrates that the application of NMF and NNLS on RS data analysis to monitor ionizing radiation-induced cellular responses can yield multiplexed biological information on bio-response to RT not revealed by conventional chemometric approaches.
      Citation: Applied Spectroscopy
      PubDate: 2020-03-18T01:40:46Z
      DOI: 10.1177/0003702820906221
       
  • Burn Chamber Test of Ex Situ Thermal Impulse Sensors
    • Authors: Benjamin R. Anderson, Natalie Gese, Ray Gunawidjaja, Hergen Eilers
      First page: 515
      Abstract: Applied Spectroscopy, Ahead of Print.
      Recently, we reported on a novel ex situ thermal impulse sensing technique (based on lanthanide-doped oxide precursor nanoparticles) for use in structural fire forensics and demonstrated its functionality in small-scale lab-based tests. As a next step we have now performed a large-scale lab test at the US Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) Fire Research Laboratory using a burn chamber with three sand burners. In this test we demonstrate our technique’s ability to determine the average temperature experienced by surfaces during the fire. While we successfully demonstrate our techniques accuracy, we also discover several previously unknown vulnerabilities. Namely, we find that: (1) our current method of embedding sensors in paint results in our sensor particles being difficult to recover (due to a large quantity of debris), (2) the current test panels have poor survivability, (3) debris from the fire tests interferes with excitation of dopant Dy ions (limiting our sensors’ functionality), and (4) dispersal in paint results in suppression of the (metastable)tetragonal-to-monoclinic phase transition of ZrO2. To overcome these vulnerabilities we are evaluating new panel materials, paints, and lanthanide-dopants.
      Citation: Applied Spectroscopy
      PubDate: 2020-02-28T02:51:40Z
      DOI: 10.1177/0003702819884131
       
  • Method Transfer Evaluation for Digital Derivative Spectrophotometry
           Through its Resolution Parameter Comparison of Different Computer Programs
           
    • Authors: Ana Homšek, Bojan Marković, Nataša Bogavac-Stanojević, Sote Vladimirov, Katarina Karljiković-Rajić
      First page: 525
      Abstract: Applied Spectroscopy, Ahead of Print.
      The application assessment of different programs was performed with equivalence tests for method transfer pro second-order derivative spectrophotometry. The digital second-order derivative spectra were calculated on different instruments; GBC Scientific Equipment Cintra 20 (Cintral v.2.6 and Spectral v.1.70 software programs) and Thermo Scientific Evolution 300 (VISIONPro software) were analyzed using the amplitude A/B ratio (A = 2D265,263; B = 2D263,261). Amplitude A/B ratio is the resolution parameter for derivative spectrophotometry prescribed in European Pharmacopoeia. The obtained values for A/B ratio were either very similar or significantly different among programs: 0.669 (Cintral v.2.6), 0.549 (Spectral v.1.70), 0.556 (medium indirect VISIONPro), 0.557 (one-step Savitzky–Golay 7 VISIONPro), 0.689 (two-step Savitzky–Golay 7 VISIONPro). Method transfer was possible between Spectral v.1.70 and VISIONPro (medium indirect and one-step Savitzky–Golay 7), but the values obtained in Cintral v.2.6 were not comparable to the other programs. The absorbance data exported from both instruments were additionally calculated in OriginPro8 which provided almost the same mean A/B values (0.627 Cintral v.2.6; 0.624 VISIONPro), confirming that the two instruments recorded the same zero-order spectra. The calculation of resolution parameter could be used for verification of program comparison, which would enable transfer between sender and receiver laboratory. The accordance between program algorithms was confirmed when acceptable differences for values of resolution parameter (A/B ratios) were achieved.
      Citation: Applied Spectroscopy
      PubDate: 2020-03-13T12:43:05Z
      DOI: 10.1177/0003702819889374
       
  • Age and Gender Characteristics of the Infrared Spectra of Normal Human
           Saliva
    • Authors: Lyudmila V. Bel’skaya, Elena A. Sarf, Denis V. Solomatin
      First page: 536
      Abstract: Applied Spectroscopy, Ahead of Print.
      The comparison of the characteristics of the infrared (IR) spectra of saliva of healthy volunteers was carried out based on gender and age. It is shown that statistically significant differences between male and female groups are observed for the absorption bands of proteins and lipids. At the same time, the absorbance of the bands assigned to proteins and nucleic acids is higher for males, whereas the absorbance of the bands assigned to lipids is higher in the group of females. It is established that the correlation relationships of the characteristics of the spectra and age are weakly expressed. Thus, when forming the criteria of the norm and pathology for saliva, it is necessary to take into account the gender of the subjects, while there are no strict requirements for taking into account age periodization. Nevertheless, the revealed patterns are valid only for the composition of the saliva of healthy volunteers, the extension of the results to groups of patients with various diseases, as well as other biological fluids, requires additional testing.
      Citation: Applied Spectroscopy
      PubDate: 2020-03-04T03:58:22Z
      DOI: 10.1177/0003702819885958
       
  • Transmission Fourier Transform Infrared Spectroscopic Imaging, Mapping,
           and Synchrotron Scanning Microscopy with Zinc Sulfide Hemispheres on
           Living Mammalian Cells at Sub-Cellular Resolution
    • Authors: Ka Lung Andrew Chan, Ali Altharawi, Pedro Fale, Cai Li Song, Sergei G. Kazarian, Gianfelice Cinque, Valérie Untereiner, Ganesh D. Sockalingum
      First page: 544
      Abstract: Applied Spectroscopy, Ahead of Print.
      Fourier transform infrared (FT-IR) spectroscopic imaging and microscopy of single living cells are established label-free technique for the study of cell biology. The constant driver to improve the spatial resolution of the technique is due to the diffraction limit given by infrared (IR) wavelength making subcellular study challenging. Recently, we have reported, with the use of a prototype zinc sulfide (ZnS) transmission cell made of two hemispheres, that the spatial resolution is improved by the factor of the refractive index of ZnS, achieving a λ/2.7 spatial resolution using the synchrotron–IR microscopy with a 36× objective with numerical aperture of 0.5. To refine and to demonstrate that the ZnS hemisphere transmission device can be translated to standard bench-top FT-IR imaging systems, we have, in this work, modified the device to achieve a more precise path length, which has improved the spectral quality of the living cells, and showed for the first time that the device can be applied to study live cells with three different bench-top FT-IR imaging systems. We applied focal plane array (FPA) imaging, linear array, and a synchrotron radiation single-point scanning method and demonstrated that in all cases, subcellular details of individual living cells can be obtained. Results have shown that imaging with the FPA detector can measure the largest area in a given time, while measurements from the scanning methods produced a smoother image. Synchrotron radiation single-point mapping produced the best quality image and has the flexibility to introduce over sampling to produce images of cells with great details, but it is time consuming in scanning mode. In summary, this work has demonstrated that the ZnS hemispheres can be applied in all three spectroscopic approaches to improve the spatial resolution without any modification to the existing microscopes.
      Citation: Applied Spectroscopy
      PubDate: 2020-03-30T03:46:18Z
      DOI: 10.1177/0003702819898275
       
  • Spectral Analysis and Deconvolution of the Amide I Band of Proteins
           Presenting with High-Frequency Noise and Baseline Shifts
    • Authors: Alexander P. Fellows, Mike T.L. Casford, Paul B. Davies
      First page: 597
      Abstract: Applied Spectroscopy, Ahead of Print.
      The challenge of deriving quantitative information from the infrared spectra of proteins arises from the large number of secondary structures and amino acid side-chain functional groups that all contribute to the spectral intensity, such as within the amide I band (1600–1700 cm–1). The band is invariably heavily convoluted from overlapping spectral features, thereby making interpretation difficult such that deconvolution is usually required. This work critically examines the methods available to deconvolute the spectra and assesses the commonly used methods and algorithms applied to vibrational spectra for smoothing and peak identification. We show that unless their spectra have very high signal-to-noise ratios, quantitative analysis to decipher protein constituents is not feasible. The advantages and disadvantages of spectral smoothing using adjacent averaging, the Savitzky–Golay filter and the fast Fourier transform filter are examined in detail. The use of derivative spectra to identify peaks is described with particular reference to the influence and reduction of interfering water bands in the amide I region. The reliability of band narrowing techniques such as second-derivative analysis or Fourier deconvolution that lead to the identification of the contributing protein peaks is investigated. Both methods are shown to be limited in their capacity to resolve features with very similar frequencies. Additionally, the presence of narrow bands arising from high-frequency noise whether from atmospheric water vapor, acoustic vibrations, or electrical interference results in both methods becoming increasingly unusable as narrow bands are preferentially enhanced at the expense of broad ones such as the amide I bands. An optimal strategy is critically developed to allow accurate determination and quantification of protein constituents and their conformations. Additionally, quantitative methods are proposed to account for baseline shifts, which would otherwise introduce significant errors in similarity indices.
      Citation: Applied Spectroscopy
      PubDate: 2020-02-10T03:03:14Z
      DOI: 10.1177/0003702819898536
       
 
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