Subjects -> CHEMISTRY (Total: 1001 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (726 journals)
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    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
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CHEMISTRY (726 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal  
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 36)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 15)
ACS Catalysis     Hybrid Journal   (Followers: 78)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 25)
ACS Combinatorial Science     Hybrid Journal   (Followers: 25)
ACS Macro Letters     Hybrid Journal   (Followers: 34)
ACS Materials Letters     Open Access   (Followers: 4)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 452)
ACS Photonics     Hybrid Journal   (Followers: 19)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 40)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chemica Malaysia     Open Access  
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: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 81)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 15)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 14)
Advanced Science Focus     Free   (Followers: 7)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 108)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 39)
Advances in Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 27)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Enzyme Research     Open Access   (Followers: 13)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 20)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 20)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 20)
Advances in Polymer Science     Hybrid Journal   (Followers: 54)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 22)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 17)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 6)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Aggregate     Open Access   (Followers: 3)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 3)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 5)
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: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 24)
American Journal of Chemistry     Open Access   (Followers: 41)
American Journal of Plant Physiology     Open Access   (Followers: 13)
Analyst     Full-text available via subscription   (Followers: 40)
Analytical Science Advances     Open Access   (Followers: 2)
Angewandte Chemie     Hybrid Journal   (Followers: 234)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 352)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 8)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 6)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 13)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 12)
Applied Spectroscopy     Full-text available via subscription   (Followers: 27)
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: 2)
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: 3)
Atomization and Sprays     Full-text available via subscription   (Followers: 8)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 483)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 3)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 4)
Biomacromolecules     Hybrid Journal   (Followers: 27)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 4)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 214)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 4)
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: 5)
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: 13)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 13)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 76)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 13)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 14)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 17)
Cereal Chemistry     Full-text available via subscription   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 11)
Chemical and Engineering News     Free   (Followers: 24)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 88)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 28)
Chemical Physics Letters : X     Open Access   (Followers: 4)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 25)
Chemical Reviews     Hybrid Journal   (Followers: 266)
Chemical Science     Open Access   (Followers: 44)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 71)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 23)
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: 223)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 20)
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: 8)
Chemistry Education Review     Open Access   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry Letters     Full-text available via subscription   (Followers: 49)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 337)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemistry–Methods     Open Access   (Followers: 2)
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: 14)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 14)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 13)
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: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 24)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

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Applied Spectroscopy
Journal Prestige (SJR): 0.489
Citation Impact (citeScore): 2
Number of Followers: 27  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0003-7028 - ISSN (Online) 1943-3530
Published by Sage Publications Homepage  [1166 journals]
  • Advertising and Front Matter

    • Free pre-print version: Loading...

      Pages: 1213 - 1224
      Abstract: Applied Spectroscopy, Volume 75, Issue 10, Page 1213-1224, October 2021.

      Citation: Applied Spectroscopy
      PubDate: 2021-10-13T09:14:55Z
      DOI: 10.1177/00037028211050759
      Issue No: Vol. 75, No. 10 (2021)
       
  • On the Limit of Detection in Infrared Spectroscopic Imaging

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      Authors: Laurin Lux, Yamuna Phal, Pei-Hsuan Hsieh, Rohit Bhargava
      Abstract: Applied Spectroscopy, Ahead of Print.
      Infrared (IR) spectroscopic imaging instruments’ performance can be characterized and optimized by an analysis of their limit of detection (LOD). Here we report a systematic analysis of the LOD for Fourier transform IR (FT-IR) and discrete frequency IR (DFIR) imaging spectrometers. In addition to traditional measurements of sample and blank data, we propose a decision theory perspective to pose the determination of LOD as a binary classification problem under different assumptions of noise uniformity and correlation. We also examine three spectral analysis approaches, namely, absorbance at a single frequency, average of absorbance over selected frequencies and total spectral distance – to suit instruments that acquire discrete or contiguous spectral bandwidths. The analysis is validated by refining the fabrication of a bovine serum albumin protein microarray to provide eight uniform spots from ∼2.8 nL of solution for each concentration over a wide range (0.05–10 mg/mL). Using scanning parameters that are typical for each instrument, we estimate a LOD of 0.16 mg/mL and 0.12 mg/mL for widefield and line scanning FT-IR imaging systems, respectively, using the spectral distance approach, and 0.22 mg/mL and 0.15 mg/mL using an optimal set of discrete frequencies. As expected, averaging and the use of post-processing techniques such as minimum noise fraction transformation results in LODs as low as ∼0.075 mg/mL that correspond to a spotted protein mass of ∼112 fg/pixel. We emphasize that these measurements were conducted at typical imaging parameters for each instrument and can be improved using the usual trading rules of IR spectroscopy. This systematic analysis and methodology for determining the LOD can allow for quantitative measures of confidence in imaging an analyte’s concentration and a basis for further improving IR imaging technology.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-21T04:30:31Z
      DOI: 10.1177/00037028211050961
       
  • Solvent Effect on Assembling and Interactions in Solutions of Phenol:
           Infrared Spectroscopic and Density Functional Theory Study

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      Authors: Swapnil Singh, Mateusz Majer, Mirosław Antoni Czarnecki, Yusuke Morisawa, Yukihiro Ozaki
      Abstract: Applied Spectroscopy, Ahead of Print.
      This work provides new insight into assembling of phenol in various solvents and competition between different kinds of interactions. To examine both weak and strong interactions, we selected a series of non-aromatic and aromatic solvents. Infrared spectra were measured at low (0.05 M) and high (2 M) phenol content. In addition, we performed density functional theory calculations of the structures and harmonic vibrational spectra of 1:1 complexes of phenol with the solvents and the associates of phenol from dimer to tetramer. Based on these results, we divided the solvents into three groups. The first group consists of non-aromatic solvents weakly interacting with phenol. Depending on the concentration, molecules of phenol in these solvents remain non-bonded or self-associated. In diluted solutions of phenol in chlorinated non-aromatic solvents do not appear free OH groups, since they are involved in a weak OH···Cl interaction. It is of note that in diluted solutions of phenol in tetramethyl ethylene both the non-bonded and bonded OH coexists due to solvent–solvent interactions. The second group consists of aromatic solvents with methyl or chlorine substituents. At low concentration, the molecules of phenol are involved in the phenol–solvent OH···π interaction and the strength of these interactions depends on the solvent properties. At a higher phenol content an equilibrium exists between phenol–solvent OH···π and phenol–phenol OH···OH interactions. Finally, the third group includes the aromatic and non-aromatic solvents with highly polar group (C≡N). In these solvents, regardless of the concentration all molecules of phenol are involved in the solute–solvent OH···NC interaction. Comparison of the experimental and theoretical band parameters reveals that molecules of phenol in non-aromatic solvents prefer the cyclic associates, while in the aromatic solvents they tend to form the linear associates.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-20T11:59:37Z
      DOI: 10.1177/00037028211052302
       
  • Correlation and Difference Between Raman Spectral Characteristic and
           Feature Evaluation for Leukocytes and Tumor Cells

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      Authors: Yixin Dai, Wenxue Li, Liu Wang, Chuan Luo, Qing Huang, Lin Pang
      Abstract: Applied Spectroscopy, Ahead of Print.
      Tumor detection supported by Raman spectroscopy is becoming increasingly popular, yet the relevance of spectral variation and feature selection retains unclear. Here we determined the correlation and difference between spectral characteristic and feature evaluation for leukocytes and tumor cells. Some peaks were found to show noticeable spectral differences, and their intensity distributions were investigated, finding using log-normal distribution to describe Raman intensity pattern may be more appropriate. Further the importance of all Raman features was calculated, where some other peak features occupied the top status. By surveying the intensity variation and feature evaluation for those peaks, we concluded the peak with the highest importance does not correspond to the peak location with the most noticeable intensity difference in spectra. Moreover, the peak intensity ratio of I1517/I719 associated with protein to nucleic acid level presented the maximum separation, thus, it can be recognized as a special indicator to develop an alternative cancer detection. It is inspiring to introduce advanced statistical models into bio-spectroscopic fields but those intrinsic spectral variations rather than classification performance should be valued. Our explorations can provide possibilities to reveal the essences within tumor carcinogenesis based on Raman spectroscopy, further overwhelming the obstacles during the translation into clinical applications.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-20T11:59:00Z
      DOI: 10.1177/00037028211050663
       
  • Raman Investigation of the Processing Structure Relations in Individual
           Poly(ethylene terephthalate) Electrospun Fibers

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      Authors: Arnaud W. Laramée, Catherine Lanthier, Christian Pellerin
      Abstract: Applied Spectroscopy, Ahead of Print.
      *These authors contributed equally.Electrospun fibers often exhibit enhanced properties at reduced diameters, a characteristic now widely attributed to a high molecular orientation of the polymer chains along the fiber axis. A parameter that can affect the molecular organization is the type of collector onto which fibers are electrospun. In this work, we use polarized confocal Raman spectromicroscopy to determine the incidence of the three most common types of collectors on the molecular orientation and structure in individual fibers of a broad range of diameters. Poly(ethylene terephthalate) is used as a model system for fibers of weakly crystalline polymers. A clear correlation emerges between the choice of collector, the induced molecular orientation, the fraction of trans conformers, and the degree of crystallinity within fibers. Quantitative structural information gathered by Raman contributes to a general description of the mechanism of action of the collectors based on the additional strain they exert on the forming fibers.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-19T10:09:00Z
      DOI: 10.1177/00037028211049242
       
  • Calculation of Spectral Optical Constants Using Combined Ellipsometric and
           Reflectance Methods for Smooth and Rough Bulk Samples

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      Authors: Gilles Fortin
      Abstract: Applied Spectroscopy, Ahead of Print.
      Spectra of the optical constants n and k of a substance are often deduced from spectroscopic measurements, performed on a thick and homogeneous sample, and from a model used to simulate these measurements. Spectra obtained for n and k using the ellipsometric method generally produce polarized reflectance simulations in strong agreement with the experimental measurements, but they sometimes introduce significant discrepancies over limited spectral ranges, whereas spectra of n and k obtained with the single-angle reflectance method require a perfectly smooth sample surface to be viable. This paper presents an alternative method to calculate n and k. The method exploits both ellipsometric measurements and s-polarized specular reflectance measurements, and compensates for potential surface scattering effects with the introduction of a specularity factor. It is applicable to bulk samples having either a smooth or a rough surface. It provides spectral optical constants that are consistent with s-polarized reflectance measurements. Demonstrations are performed in the infrared region using a glass slide (smooth surface) and a pellet of compressed ammonium sulfate powder (rough surface).
      Citation: Applied Spectroscopy
      PubDate: 2021-10-12T04:44:10Z
      DOI: 10.1177/00037028211047898
       
  • Revealing Lipid Body Formation and its Subcellular Reorganization in
           Oleaginous Microalgae Using Correlative Optical Microscopy and Infrared
           Nanospectroscopy Atomic Force Microscopy-Induced Resonance (AFM-IR)

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      Authors: Ariane Deniset-Besseau, Rémy Coat, Benjamin Moutel, Rolando Rebois, Jérémie Mathurin, Dominique Grizeau, Alexandre Dazzi, Olivier Gonçalves
      Abstract: Applied Spectroscopy, Ahead of Print.
      The purpose of this work is to develop an integrated imaging approach to characterize without labeling at the sub-cellular level the formation of lipid body droplets (LBs) in microalgae undergoing nitrogen starvation. First conventional optical microscopy approaches, gas chromatography, and turbidimetry measurements allowed to monitor the biomass and the total lipid content in the oleaginous microalgae Parachlorella kesslerii during the starvation process. Then a local analysis of the LBs was proposed using an innovative infrared nanospectroscopy technique called atomic force microscopy-based infrared spectroscopy (AFM-IR). This label-free technique assessed the formation of LBs and allowed to look into the LB composition thanks to the acquisition of local infrared spectra. Last correlative measurements using fluorescence microscopy and AFM-IR were performed to investigate the subcellular reorganization of LB and the chloroplasts.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-05T11:07:29Z
      DOI: 10.1177/00037028211050659
       
  • Raman Spectroscopy Coupled with Reflectance Spectroscopy as a Tool for the
           Characterization of Key Hydrothermal Alteration Minerals in Epithermal
           Au–Ag Systems: Utility and Implications for Mineral Exploration

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      Authors: Carlos Arbiol, Graham D. Layne
      Abstract: Applied Spectroscopy, Ahead of Print.
      Raman spectroscopy of fine-grained hydrothermal alteration minerals, and phyllosilicates in particular, presents certain challenges. However, given the increasingly widespread recognition of field portable visible–near infrared–shortwave infrared (Vis-NIR-SWIR) spectroscopy as a valuable tool in the mineral exploration industry, Raman microspectroscopy has promise as an approach for developing detailed complementary information on hydrothermal alteration phases in ore-forming systems. Here we present exemplar high-quality Raman and Vis-NIR-SWIR spectra of four key hydrothermal alteration minerals (pyrophyllite, white mica, chlorite, and alunite) that are common in precious metal epithermal systems, from deposits on the island of Newfoundland, Canada. The results reported here demonstrate that Raman microspectroscopy can accurately characterize pyrophyllite, white mica, chlorite, and alunite and provide details on their compositional variation at the microscale. In particular, spectral differences in the 1000–1150 cm−1 white mica Raman band allows the distinction between low-Tschermak phases (muscovite, paragonite) and phases with higher degrees of Tschermak substitution (phengitic white mica composition). The peak position of the main chlorite Raman band shifts between 683 cm−1 for Mg-rich chlorite and 665 cm−1 for Fe-rich chlorite and can be therefore used for semiquantitative estimation of the Fe2+ content in chlorite. Furthermore, while Vis-NIR-SWIR macrospectroscopy allows the rapid identification of the overall composition of the most abundant hydrothermal alteration mineral in a given sample, Raman microspectroscopy provides an in-depth spectral and chemical characterization of individual mineral grains, preserving the spatial and paragenetic context of each mineral and allowing for the distinction of chemical variation between (and within) different mineral grains. This is particularly useful in the case of alunite, white mica, and chlorite, minerals with extensive solid solution, where microscale characterization can provide information on the alteration zonation useful for mineral exploration and provide insight into mineral deposit genesis.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-05T11:03:02Z
      DOI: 10.1177/00037028211047869
       
  • Photoacoustic Spectroscopy and Hyperglycemia in Experimental Type 1
           Diabetes

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      Authors: Lilia I. Olvera Cano, Guadalupe C. Villanueva Lopez, Evelyn Romero Mateos, Alfredo Cruz Orea
      Abstract: Applied Spectroscopy, Ahead of Print.
      According to the World Health Organization, diabetes was the seventh leading cause of death in 2016. Long-term diabetes complications are associated with hyperglycemia. It is difficult to predict the beginning and evolution of those complications. The goal of the study was to evaluate the relationship between glycemia and blood spectroscopic variables in an experimental model of type 1 diabetes (streptozotocin model). Blood samples were taken weekly (10 weeks) from the tail of male Wistar rats with or without diabetes. Blood optical absorption spectra were obtained by means of photoacoustic spectroscopy. It was possible to estimate the time-course of blood characteristic peak ratios. The area under the curve of those peaks correlated with hyperglycemia. The evolution of the optical absorption at 450 nm, related to cytochrome p450, was obtained by using the phase-resolved method. The area under the curve of p450 correlated also with hyperglycemia. It is concluded that photoacoustic spectroscopy is a reliable technology to detect the effects of hyperglycemia on blood with possible applications in the study of long-term diabetes complications.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-01T02:20:39Z
      DOI: 10.1177/00037028211047257
       
  • Calibration Technique for Suppressing Residual Etalon Artifacts in
           Slit-Averaged Raman Spectroscopy

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      Authors: Christine Massie, Keren Chen, Andrew J. Berger
      Abstract: Applied Spectroscopy, Ahead of Print.
      Back-illuminated charged-coupled device (BI-CCD) arrays increase quantum efficiency but also amplify etaloning, a multiplicative, wavelength-dependent fixed-pattern effect. When spectral data from hundreds of BI-CCD rows are combined, the averaged spectrum will generally appear etalon-free. This can mask substantial etaloning at the row level, even if the BI-CCD has been treated to suppress the effect. This paper compares two methods of etalon correction, one with simple averaging and one with row-by-row calibration using a fluorescence standard. Two BI-CCD arrays, both roughened by the supplier to reduce etaloning, were used to acquire Raman spectra of murine bone specimens. For one array, etaloning was the dominant source of noise under the exposure conditions chosen, even for the averaged spectrum across all rows; near-infrared-excited Raman peaks were noticeably affected. In this case, row-by-row calibration improved the spectral quality of the average spectrum. The other CCD’s performance was shot-noise limited and therefore received no benefit from the extra calibration. The different results highlight the importance of checking for and correcting row-level fixed pattern when measuring weak Raman signals in the presence of a large fluorescence background.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-01T02:19:39Z
      DOI: 10.1177/00037028211046643
       
  • A Novel Compression Method of Spectral Data Matrix Based on the Low-Rank
           Approximation and the Fast Fourier Transform of the Singular Vectors

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      Authors: Joseph Dubrovkin
      Abstract: Applied Spectroscopy, Ahead of Print.
      Storage, processing, and transfer of huge matrices are becoming challenging tasks in the process analytical technology and scientific research. Matrix compression can solve these problems successfully. We developed a novel compression method of spectral data matrix based on its low-rank approximation and the fast Fourier transform of the singular vectors. This method differs from the known ones in that it does not require restoring the low-rank approximated matrix for further Fourier processing. Therefore, the compression ratio increases. A compromise between the losses of the accuracy of the data matrix restoring and the compression ratio was achieved by selecting the processing parameters. The method was applied to multivariate chemometrics analysis of the cow milk for determining fat and protein content using two data matrices (the file sizes were 5.7 and 12.0 MB) restored from their compressed form. The corresponding compression ratios were about 52 and 114, while the loss of accuracy of the analysis was less than 1% compared with processing of the non-compressed matrix. A huge, simulated matrix, compressed from 400 MB to 1.9 MB, was successfully used for multivariate calibration and segment cross-validation. The data set simulated a large matrix of 10 000 low-noise infrared spectra, measured in the range 4000–400 cm−1 with a resolution of 0.5 cm−1. The corresponding file was compressed from 262.8 MB to 19.8 MB. The discrepancies between original and restored spectra were less than the standard deviation of the noise. The method developed in the article clearly demonstrated its potential for future applications to chemometrics-enhanced spectrometric analysis with limited options of memory size and data transfer rate. The algorithm used the standard routines of Matlab software.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-01T02:04:02Z
      DOI: 10.1177/00037028211044759
       
  • Diagnosis of Gulf War Illness Using Laser-Induced Spectra Acquired from
           Blood Samples

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      Authors: Rosalba Gaudiuso, Sirui Chen, Efi Kokkotou, Lisa Conboy, Eric Jacobson, Eugene B. Hanlon, Noureddine Melikechi
      Abstract: Applied Spectroscopy, Ahead of Print.
      Gulf War illness (GWI) is a chronic illness with no known validated biomarkers that affects the lives of hundreds of thousands of people. As a result, there is an urgent need for the development of an untargeted and unbiased method to distinguish GWI patients from non-GWI patients. We report on the application of laser-induced breakdown spectroscopy (LIBS) to distinguish blood plasma samples from a group of subjects with GWI and from subjects with chronic low back pain as controls. We initially obtained LIBS data from blood plasma samples of four GWI patients and four non-GWI patients. We used an analytical method based on taking the difference between a mean LIBS spectrum obtained with those of GWI patients from the mean LIBS spectrum of those of the control group, to generate a “difference” spectrum for our classification model. This model was cross-validated using different numbers of differential LIBS emission peaks. A subset of 17 of the 82 atomic and ionic transitions that provided 70% of correct diagnosis was selected test in a blinded fashion using 10 additional samples and was found to yield 90% classification accuracy, 100% sensitivity, and 83.3% specificity. Of the 17 atomic and ionic transitions, eight could be assigned unambiguously to species of Na, K, and Fe.
      Citation: Applied Spectroscopy
      PubDate: 2021-10-01T02:02:54Z
      DOI: 10.1177/00037028211042049
       
  • Up-Conversion Luminescence Processes in NaLaF4 Doped with Tm3+ and Yb3+
           and Dependence on Tm3+ Concentration and Temperature

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      Authors: Jurgis Grube
      Abstract: Applied Spectroscopy, Ahead of Print.
      In this work, luminescence processes in polycrystalline NaLaF4:Tm3+ and NaLaF4:Tm3+,Yb3+ materials were studied. Luminescence spectra and decay kinetics measurements were performed for NaLaF4 doped with various Tm3+ concentrations (0.01, 0.1, 0.5, 1, and 2 mol%) under direct excitation to 3P0, 1D2, 1G4, and 3H4 states. It was found that some of the Tm3+ excited states are more affected by Tm3+ concentration than other states. Under infrared excitation of Yb3+, energy transfer to Tm3+ occurred and intensive ultraviolet and blue up-conversion luminescence was observed. Possible up-conversion mechanisms are discussed. Spectroscopic measurements show that long-duration excitation radiation reduces ultraviolet up-conversion luminescence intensity, and this intensity reduction is related to sample heating due to high excitation radiation density and a poor heat sink from samples. It was found that sample configuration for spectroscopic measurements is crucial to correctly describe measured up-conversion luminescence spectra.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-29T05:53:33Z
      DOI: 10.1177/00037028211045424
       
  • Distinguishing Resonant from Non-Resonant Nonlinear Optical Processes
           Using Intensity–Intensity Correlation Analyses

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      Authors: Supriya Nagpal, Bryan Semon, Gombojav O. Ariunbold
      Abstract: Applied Spectroscopy, Ahead of Print.
      Three-color coherent anti-Stokes Raman scattering (CARS) represents non-degenerate four wave mixing that includes both non-resonant and resonant processes, the contributions of which depend upon how the molecular vibrational modes are being excited by the input laser pulses. The scattering signal due to resonant processes builds up progressively. An advanced analytical tool to reveal this deferred resonant signal buildup phenomenon is in need. In this work, we adapt a quantitative analytical tool by introducing one-dimensional and two-dimensional intensity–intensity correlation functions in terms of a new variable (probe pulse delay) and a new perturbation parameter (probe pulse linewidth). In particular, discrete diagonal directional sums are defined here as a tool to reduce both synchronous and asynchronous two-dimensional correlation spectroscopy (2D-COS) maps down to one-dimensional plots while maintaining the valuable analytical information. Detailed analyses using the all-Gaussian coherent Raman scattering closed-form solutions and the representative experimental data for resonant and non-resonant processes are presented and compared. The present work holds a promising potential for industrial application, e.g., by extractive industries to distinguish hydrocarbons (chemically resonant substance) from water (non-resonant contaminant) by utilizing the one- and two-dimensional correlation analyses.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-28T04:53:41Z
      DOI: 10.1177/00037028211045711
       
  • Clinical Spectroscopy: Lost in Translation'

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      Authors: James M. Cameron, Christopher Rinaldi, Samantha H. Rutherford, Alexandra Sala, Ashton G. Theakstone, Matthew J. Baker
      Abstract: Applied Spectroscopy, Ahead of Print.
      This Focal Point Review paper discusses the developments of biomedical Raman and infrared spectroscopy, and the recent strive towards these technologies being regarded as reliable clinical tools. The promise of vibrational spectroscopy in the field of biomedical science, alongside the development of computational methods for spectral analysis, has driven a plethora of proof-of-concept studies which convey the potential of various spectroscopic approaches. Here we report a brief review of the literature published over the past few decades, with a focus on the current technical, clinical, and economic barriers to translation, namely the limitations of many of the early studies, and the lack of understanding of clinical pathways, health technology assessments, regulatory approval, clinical feasibility, and funding applications. The field of biomedical vibrational spectroscopy must acknowledge and overcome these hurdles in order to achieve clinical efficacy. Current prospects have been overviewed with comment on the advised future direction of spectroscopic technologies, with the aspiration that many of these innovative approaches can ultimately reach the frontier of medical diagnostics and many clinical applications.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-23T02:16:58Z
      DOI: 10.1177/00037028211021846
       
  • Raman Spectroscopy for the Analysis of Microplastics in Aquatic Systems

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      Authors: Veronica Nava, Maria Luce Frezzotti, Barbara Leoni
      Abstract: Applied Spectroscopy, Ahead of Print.
      Raman spectroscopy is gaining ground in the analysis of microplastics, especially due to its high spatial resolution that allows the investigation of small plastic particles, whose numeric abundance is argued to be particularly relevant in aquatic systems. Here, we aimed at outlining the status of Raman analysis of microplastics from aquatic systems, highlighting the advantages and the drawbacks of this technique and critically presenting tools and ways to effectively employ this instrument and to improve the spectra obtained and their interpretation. In particular, we summarized procedural information for the use of Raman spectroscopy, and we discussed issues linked to fluorescence interference and the analysis of weathered polymers, which may complicate the interpretation of Raman signatures. In this context, a deep understanding of the different plastic polymers and their Raman peaks and chemical fingerprints is fundamental to avoid misidentification. Therefore, we provided a catalog with detailed information about peaks of most common plastic polymers, and this represents, to the best of our knowledge, the first comprehensive resource that systematically synthesized plastic Raman peaks. Additionally, we focused on plastic additives, which are contained in the majority of plastics. These compounds are often intense in Raman scattering and may partly or completely overlie the actual material types, resulting in the identification of additives alone or misidentification issue. For these reasons, we also presented a new R package “RamanMP” that includes a database of 356 spectra (325 of which are additives). This will help to foster the use of this technique, which is becoming especially relevant in microplastic analysis.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-20T10:45:36Z
      DOI: 10.1177/00037028211043119
       
  • Data Preprocessing Method for the Analysis of Spectral Components in the
           Spectra of Mixtures

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      Authors: Richard S. Jackson, Qian Wang, John Lien
      Abstract: Applied Spectroscopy, Ahead of Print.
      This paper describes a data preprocessing algorithm that can be used to mitigate the effects of interfering spectral components when the goal is to detect the spectrum of unknown components in a mixture of known components or to verify the presence of suspected components in the spectrum of a mixture of known components. The algorithm is both relatively simple and applicable to a wide range of problems in spectroscopy. The range of applicability can be increased by combining the method with other data preprocessing methods, for example derivative spectra, and can also accommodate variability in the spectra of one or more of the known components. Examples of the application of the algorithm to real problems are given for near-infrared analysis of antibiotic drug formulations inside gelatin capsules and mid-infrared analysis of atmospheric pollutants.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-10T02:21:19Z
      DOI: 10.1177/00037028211042903
       
  • Spectral Emission Signatures from Cased High Explosive Charges

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      Authors: Austin Butler, David Amondson, Herman Krier, Nick Glumac
      Abstract: Applied Spectroscopy, Ahead of Print.
      Spectroscopic signatures of cased high-explosive charge denotations are examined using emission spectroscopy with sub nanometer resolution. Eleven distinct case materials are investigated for atomic features of their major alloying elements. Molecular features of case material combustion products are also investigated for five case materials. Emission is monitored within the 275–425 nm range for atomic features and in the 310–755 nm range for molecular features. Major alloying elements with concentrations greater than 5% are generally detected through atomic emission. Al, Cu, Fe, Mg, Cr, Mn, Pb, and Ni are all detected in concentrations less than 5%. Undetected elements include Zn, Nb, Ta, and V. Molecular emission from aluminum monoxide, titanium monoxide, and CN is measured for aluminum alloy, titanium alloy, and carbon fiber cases, respectively.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-09T03:40:27Z
      DOI: 10.1177/00037028211042646
       
  • Attenuated Total Reflection (ATR) Micro-Fourier Transform Infrared
           (Micro-FT-IR) Spectroscopy to Enhance Repeatability and Reproducibility of
           Spectra Derived from Single Specimen Organic-Walled Dinoflagellate Cysts

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      Authors: Pjotr Meyvisch, Pieter R. Gurdebeke, Henk Vrielinck, Kenneth Neil Mertens, Gerard Versteegh, Stephen Louwye
      Abstract: Applied Spectroscopy, Ahead of Print.
      The chemical composition of recent and fossil organic-walled dinoflagellate cyst walls and its diversity is poorly understood and analyses on single microscopic specimens are rare. A series of infrared spectroscopic experiments resulted in the proposition of a standardized attenuated total reflection micro-Fourier transform infrared-based method that allows the collection of robust data sets consisting of spectra from individual dinocysts. These data sets are largely devoid of nonchemical artifacts inherent to other infrared spectrochemical methods, which have typically been used to study similar specimens in the past. The influence of sample preparation, specimen morphology and size and spectral data processing steps is also assessed within this methodological framework. As a result, several guidelines are proposed which facilitate the collection and qualitative interpretation of highly reproducible and repeatable spectrochemical data. These, in turn, pave the way for a systematic exploration of dinocyst chemistry and its assessment as a chemotaxonomical tool or proxy.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-08T11:16:57Z
      DOI: 10.1177/00037028211041172
       
  • Femtosecond Single-Pulse and Orthogonal Double-Pulse Laser-Induced
           Breakdown Spectroscopy (LIBS): Femtogram Mass Detection and Chemical
           Imaging with Micrometer Spatial Resolution

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      Authors: Nikolaos Giannakaris, Anna Haider, Christoph M. Ahamer, Stefan Grünberger, Stefan Trautner, Johannes D. Pedarnig
      Abstract: Applied Spectroscopy, Ahead of Print.
      Femtosecond laser-induced breakdown spectroscopy (fs-LIBS) is employed to detect tiny amounts of mass ablated from macroscopic specimens and to measure chemical images of microstructured samples with high spatial resolution. Frequency-doubled fs-pulses (length 400 fs, wavelength 520 nm) are tightly focused with a Schwarzschild microscope objective to ablate the sample surface. The optical emission of laser-induced plasma (LIP) is collected by the objective and measured with an echelle spectrometer equipped with an intensified charge-coupled device camera. A second fs-laser pulse (1040 nm) in orthogonal beam arrangement is reheating the LIP. The optimization of the experimental setup and measurement parameters enables us to record single-pulse fs-LIBS spectra of 5 nm thin metal layers with an ablated mass per pulse of 100 femtogram (fg) for Cu and 370 fg for Ag films. The orthogonal double-pulse fs-LIBS enhances the recorded emission line intensities (two to three times) and improves the contrast of chemical images in comparison to single-pulse measurements. The size of ablation craters (diameters as small as 1.5 µm) is not increased by the second laser pulse. The combination of minimally invasive sampling by a tightly focused low-energy fs-pulse and of strong enhancement of plasma emission by an orthogonal high-energy fs-pulse appears promising for future LIBS chemical imaging with high spatial resolution and with high spectrochemical sensitivity.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-08T03:24:25Z
      DOI: 10.1177/00037028211042398
       
  • Airborne Gold Nanoparticle Detection Using Photoluminescence Excited with
           a Continuous Wave Laser

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      Authors: Per Samuelsson, Markus Snellman, Martin H. Magnusson, Knut Deppert, Marcus Aldén, Zhongshan Li
      Abstract: Applied Spectroscopy, Ahead of Print.
      We report the observation of photoluminescence emission from airborne gold, silver, and copper nanoparticles. A continuous wave 532 nm laser was employed for excitation. Photoluminescence from gold nanoparticles carried in a nitrogen gas flow was both spectrally resolved and directly imaged in situ using an intensified charge-coupled device camera. The simultaneously detected Raman signal from the nitrogen molecules enables quantitative estimation of the photoluminescence quantum yield of the gold nanoparticles. Photoluminescence from metal nanoparticles carried in a gas flow provides a potential tool for operando imaging of plasmonic metal nanoparticles in aerosol reactions.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-03T01:39:08Z
      DOI: 10.1177/00037028211042021
       
  • Monitoring of Oxygen in Simulated Electrolytic Reduction Salt of
           Pyroprocessing Using Laser-Induced Breakdown Spectroscopy

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      Authors: Se-Hwan Park, Seul-Ki Han, Seong-Kyu Ahn
      Abstract: Applied Spectroscopy, Ahead of Print.
      Laser-induced breakdown spectroscopy (LIBS) was explored as a method of monitoring oxygen (O) concentration in electrolytic reduction salt of pyroprocessing. Simulated salt samples were fabricated, and each sample was put in a transparent and sealed vial filled with argon gas. An Nd:YAG laser pulse was applied to the sample through the vial surface, and the optical emission spectrum was measured. O(I) 777.2 nm lines were clearly identified in the spectrum of a sample containing Li2O, and the intensity of the O peak and the intensity ratio of O and lithium (Li) peaks, in which Li was used as the normalization, increased linearly as the O concentration in the salt sample was increased. The limit of detection and root mean square error were calculated for the cases of O peak area, O peak height, peak area ratio of O–Li, and the peak height ratio of O–Li, and all the cases could indicate that the O concentration in the electrolytic reduction salt was out of normal range. Our result shows that LIBS has the possibility to be used as a method for monitoring of O in electrolytic reduction salt.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-01T04:34:42Z
      DOI: 10.1177/00037028211042873
       
  • Effective Medium Model Applied to Biopolymer Solutions

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      Authors: Nikita V. Penkov, Nadezda A. Penkova
      Abstract: Applied Spectroscopy, Ahead of Print.
      Studying dielectric properties of heterogeneous systems is challenged by a problem of uncertainty of the ratio between dielectric permittivity of the system and dielectric permittivities of its components. Such ratios can be obtained in some cases using theoretical effective medium models. However, such models have not yet been developed for all the systems possible. Particularly, there is no effective medium model with filamentary inclusions. Such a theoretical model elaborated based on the fundamental principles of electrodynamics of continuous media is suggested in the present work. Any point of a filamentary inclusion with a length that is significantly greater than the thickness can be regarded as being located in a long cylinder-like fragment of the inclusion with stochastic direction of the cylinder axis relative to the external electric field. With this regard, electric field strength and electric induction values were averaged across the entire volume of a two-phase dielectric material. As a result, a model linking the dielectric permittivity of the two-phase system and the dielectric permittivities of both phases was elaborated. The model appears to be highly relevant for studying solutions of biopolymers, such as nucleic acids, fibrillar proteins and protein aggregates, polysaccharides, by means of electrical impedance spectroscopy, dielectric spectroscopy, and terahertz time-domain spectroscopy. The suggested theoretical model was successfully validated on a DNA solution within the terahertz region.
      Citation: Applied Spectroscopy
      PubDate: 2021-09-01T04:33:44Z
      DOI: 10.1177/00037028211042027
       
  • Quantitative Analysis of Manganese in Underwater Steel Samples Using
           Long–Short Double-Pulse Laser-Induced Breakdown Spectroscopy

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      Authors: Zhenzhen Wang, Kai Rong, Seiya Tanaka, Yoshihiro Deguchi, Minchao Cui, Junjie Yan
      Abstract: Applied Spectroscopy, Ahead of Print.
      The long–short double-pulse laser-induced breakdown spectroscopy (LS-DP-LIBS) method was applied to qualitative and quantitative analyses of underwater steel samples to improve the detection ability of underwater measurement. The stable plasma intensity and discrete emission lines were detected using LS-DP-LIBS when comparing the measured results of single-pulse LIBS (SP-LIBS) and LS-DP-LIBS. The long pulse produces a cavitation bubble without plasma, and the short pulse induces the plasma of steel samples within the bubble. The detection features of LS-DP-LIBS for underwater steel samples were discussed in different intra-pulse delay time, long-pulse width, and delay time conditions when analyzing the measured spectra, the signal intensity of Fe(I) at 400.524 nm and 402.187 nm, Mn(I) at 404.136 nm, and intensity ratio of Mn(I) 404.136 nm/Fe(I) 402.187 nm. The results indicated that the plasma stability and spectral signal intensity were improved significantly with a long-pulse width of 80 µs in the intra-pulse delay time of 70 µs, which were appropriate for bubble formation and plasma generation. According to the discussion of the delay time effect, the state of generated plasma was almost stable from 650 ns to 850 ns. Manganese (Mn) contents in steel samples were analyzed quantitatively when measuring five steel samples with different Mn contents using LS-DP-LIBS in optimal experimental conditions. A strong linear dependence was observed with R2=0.9842, which demonstrated the feasibility and appropriateness of quantitative analysis for underwater measurement using LS-DP-LIBS.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-25T03:01:30Z
      DOI: 10.1177/00037028211038634
       
  • Infrared Refraction Spectroscopy

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      Authors: Thomas G. Mayerhöfer, Vladimir Ivanovski, Jürgen Popp
      Abstract: Applied Spectroscopy, Ahead of Print.
      We suggest a new modality of infrared spectroscopy termed Infrared Refraction Spectroscopy, which is complimentary to absorption spectroscopy. The beauty of this new modality lies not only in its simplicity but also in the fact that it closes an important gap: It allows to quantitatively interpret reflectance spectra by simplest means. First, the refractive index spectrum is calculated from reflectance by neglecting absorption. The change of the refractive index is proportional to concentration, and the spectra with features similar to second derivative absorbance spectra can simply be computed by numerically deriving the refractive index spectra, something which can be easily carried out by standard spectra software packages. The peak values of the derived spectra indicate oscillator positions and are approximately proportional to the concentration in a similar way as absorbance is. In contrast to absorbance spectra, there are no baseline ambiguities for first derivative refractive index spectra, and in refractive index spectra, instead of integrating over a band area, a simple difference of two refractive index values before and after an absorption leads to a quantity that correlates perfectly linearly with concentration in the absence of local field effects.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-18T09:41:23Z
      DOI: 10.1177/00037028211036761
       
  • Group and Basis Restricted Non-Negative Matrix Factorization and Random
           Forest for Molecular Histotype Classification and Raman Biomarker
           Monitoring in Breast Cancer

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      Authors: Xinchen Deng, Kirsty Milligan, Ramie Ali-Adeeb, Phillip Shreeves, Alexandre Brolo, Julian J. Lum, Jeffrey L. Andrews, Andrew Jirasek
      Abstract: Applied Spectroscopy, Ahead of Print.
      Raman spectroscopy is a non-invasive optical technique that can be used to investigate biochemical information embedded in cells and tissues exposed to ionizing radiation used in cancer therapy. Raman spectroscopy could potentially be incorporated in personalized radiation treatment design as a tool to monitor radiation response in at the metabolic level. However, tracking biochemical dynamics remains challenging for Raman spectroscopy. Here we developed a novel analytical framework by combining group and basis restricted non-negative matrix factorization and random forest (GBR-NMF-RF). This framework can monitor radiation response profiles in different molecular histotypes and biochemical dynamics in irradiated breast cancer cells. Five subtypes of; human breast cancer (MCF-7, BT-474, MDA-MB-230, and SK-BR-3) and normal cells derived from human breast tissue (MCF10A) which had been exposed to ionizing radiation were tested in this framework. Reference Raman spectra of 20 biochemicals were collected and used as the constrained Raman biomarkers in the GBR-NMF-RF framework. We obtained scores for individual biochemicals corresponding to the contribution of each Raman reference spectrum to each spectrum obtained from the five cell types. A random forest classifier was then fitted to the chemical scores for performing molecular histotype classifications (HER2, PR, ER, Ki67, and cancer versus non-cancer) and assessing the importance of the Raman biochemical basis spectra for each classification test. Overall, the GBR-NMF-RF framework yields classification results with high accuracy (>97%), high sensitivity (>97%), and high specificity (>97%). Variable importance calculated in the random forest model indicated high contributions from glycogen and lipids (cholesterol, phosphatidylserine, and stearic acid) in molecular histotype classifications.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-06T09:47:57Z
      DOI: 10.1177/00037028211035398
       
  • Molecular Vibrations Are Not Asymmetric

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      Authors: James A. de Haseth
      Abstract: Applied Spectroscopy, Ahead of Print.
      There is considerable confusion when naming vibrations in infrared and Raman spectra. One of the most common errors is the identification of some stretching and bending vibrations as “asymmetric”. There are no asymmetric vibrations as such vibrations incur rotations and translations. The correct term is antisymmetric and it is demonstrated, through molecular symmetry operations, why this is the correct term.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-06T09:47:37Z
      DOI: 10.1177/00037028211036509
       
  • Modeling with Multiple Correlated Spectral Data Based on Approximating the
           Nonlinear Spectrum Induced by Scattering

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      Authors: Yongshun Luo, Gang Li, Guosong Shan, Ling Lin
      Abstract: Applied Spectroscopy, Ahead of Print.
      In the spectral quantitative analysis of scattering solution, the improvement of accuracy is seriously restricted by the nonlinearity caused by scattering, and even the measurement will fail due to the influence of scattering. The important reasons are that the modeling variables are greatly affected by nonlinearity, and the information contained in the modeling data cannot represent the scattering characteristics. In this paper, a method is proposed, in which the spectral data of several optical pathlengths with equal space are combined as the modeling data set of a sample. These highly correlated spectral data contain relatively nonlinear information. The addition of the spectral data provides more options for the selection of principal components in modeling with PLS method. By giving lower weight to the corresponding wavelength which is greatly affected by scattering, the model is insensitive to scattering and the prediction accuracy is improved. Through the spectral quantitative analysis experiment on strong scattering material, the prediction accuracy of the model was 61.7% higher than that of the traditional method and was 58.5% higher than that of the variable sorting for normalization method. The feasibility of the method is verified.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-06T09:47:19Z
      DOI: 10.1177/00037028211036515
       
  • Detection of Low Lithium Concentrations Using Laser-Induced Breakdown
           Spectroscopy (LIBS) in High-Pressure and High-Flow Conditions

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      Authors: Ivo M. Raimundo, S. Michael Angel, Arelis M. Colón
      Abstract: Applied Spectroscopy, Ahead of Print.
      This paper describes the effects of laser pulse rate and solution flow rate on the determination of lithium at high pressure for water and 2.5% sodium chloride solutions using laser-induced breakdown spectroscopy (LIBS). Preliminary studies were performed with 0–40 mg L−1 Li solutions, at ambient pressure and at 210 bar, and in static and flowing (6 mL · min−1) regimes, for a combination of four different measurement conditions. The sensitivity of calibration curves depended on the pressure and the flow rate, as well as the laser pulse rate. The sensitivity of the calibration curve increased about 10% and 18% when the pressure was changed from 1 to 210 bar for static and flowing conditions, respectively. However, an effect of flow rate at high pressure for both 2 and 10 Hz laser pulse rates was observed. At ambient pressure, the effect of flow rate was negligible, as the sensitivity of the calibration curve decreased around 2%, while at high pressure the sensitivity increased around 4% when measurements were performed in a flow regime. Therefore, it seems there is a synergistic effect between pressure and flow rate, as the sensitivity increases significantly when both changes are considered. When the pulse rate is changed from 2 to 10 Hz, the sensitivity increases 26–31%, depending on the pressure and flow conditions. For lithium detection limit studies, performed with a laser pulse energy of 2.5 mJ, repetition rate of 10 Hz, gate delay of 500 ns, gate width of 1000 ns, and 1000 accumulations, a value around 40 µg L−1 was achieved for Li solutions in pure water for all four measurement conditions, while a detection limit of about 92 µg L−1 was determined for Li in 2.5% sodium chloride solutions, when high pressure and flowing conditions were employed. The results obtained in the present work demonstrate that LIBS is a powerful tool for the determination of Li in deep ocean conditions such as those found around hydrothermal vent systems.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-04T02:28:20Z
      DOI: 10.1177/00037028211035439
       
  • Probing the Bovine Hemoglobin Adsorption Process and its Influence on
           Interfacial Water Structure at the Air–Water Interface

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      Authors: Shilpi Chaudhary, Harsharan Kaur, Harpreet Kaur, Bhawna Rana, Deepak Tomar, Kailash C. Jena
      Abstract: Applied Spectroscopy, Ahead of Print.
      *These authors contributed equally to this work.The molecular-level insight of protein adsorption and its kinetics at interfaces is crucial because of its multifold role in diverse fundamental biological processes and applications. In the present study, the sum frequency generation (SFG) vibrational spectroscopy has been employed to demonstrate the adsorption process of bovine hemoglobin (BHb) protein molecules at the air–water interface at interfacial isoelectric point of the protein. It has been observed that surface coverage of BHb molecules significantly influences the arrangement of the protein molecules at the interface. The time-dependent SFG studies at two different frequencies in the fingerprint region elucidate the kinetics of protein denaturation process and its influence on the hydrogen-bonding network of interfacial water molecules at the air–water interface. The initial growth kinetics suggests the synchronized behavior of protein adsorption process with the structural changes in the interfacial water molecules. Interestingly, both the events carry similar characteristic time constants. However, the conformational changes in the protein structure due to the denaturation process stay for a long time, whereas the changes in water structure reconcile quickly. It is revealed that the protein denaturation process is followed by the advent of strongly hydrogen-bonded water molecules at the interface. In addition, we have also carried out the surface tension kinetics measurements to complement the findings of our SFG spectroscopic results.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-04T02:27:55Z
      DOI: 10.1177/00037028211035157
       
  • Classification of Semiconductors Using Photoluminescence Spectroscopy and
           Machine Learning

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      Authors: Yinchuan Yu, Matthew D. McCluskey
      Abstract: Applied Spectroscopy, Ahead of Print.
      Photoluminescence spectroscopy is a nondestructive optical method that is widely used to characterize semiconductors. In the photoluminescence process, a substance absorbs photons and emits light with longer wavelengths via electronic transitions. This paper discusses a method for identifying substances from their photoluminescence spectra using machine learning, a technique that is efficient in making classifications. Neural networks were constructed by taking simulated photoluminescence spectra as the input and the identity of the substance as the output. In this paper, six different semiconductors were chosen as categories: gallium oxide (Ga2O3), zinc oxide (ZnO), gallium nitride (GaN), cadmium sulfide (CdS), tungsten disulfide (WS2), and cesium lead bromide (CsPbBr3). The developed algorithm has a high accuracy (>90%) for assigning a substance to one of these six categories from its photoluminescence spectrum and correctly identified a mixed Ga2O3/ZnO sample.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-03T01:23:21Z
      DOI: 10.1177/00037028211031618
       
  • Machine Learning-Assisted Sampling of SERS Substrates Improves Data
           Collection Efficiency

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      Authors: Tatu Rojalin, Dexter Antonio, Ambarish Kulkarni, Randy P. Carney
      Abstract: Applied Spectroscopy, Ahead of Print.
      Surface-enhanced Raman scattering (SERS) is a powerful technique for sensitive label-free analysis of chemical and biological samples. While much recent work has established sophisticated automation routines using machine learning and related artificial intelligence methods, these efforts have largely focused on downstream processing (e.g., classification tasks) of previously collected data. While fully automated analysis pipelines are desirable, current progress is limited by cumbersome and manually intensive sample preparation and data collection steps. Specifically, a typical lab-scale SERS experiment requires the user to evaluate the quality and reliability of the measurement (i.e., the spectra) as the data are being collected. This need for expert user-intuition is a major bottleneck that limits applicability of SERS-based diagnostics for point-of-care clinical applications, where trained spectroscopists are likely unavailable. While application-agnostic numerical approaches (e.g., signal-to-noise thresholding) are useful, there is an urgent need to develop algorithms that leverage expert user intuition and domain knowledge to simplify and accelerate data collection steps. To address this challenge, in this work, we introduce a machine learning-assisted method at the acquisition stage. We tested six common algorithms to measure best performance in the context of spectral quality judgment. For adoption into future automation platforms, we developed an open-source python package tailored for rapid expert user annotation to train machine learning algorithms. We expect that this new approach to use machine learning to assist in data acquisition can serve as a useful building block for point-of-care SERS diagnostic platforms.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-03T01:22:51Z
      DOI: 10.1177/00037028211034543
       
  • Trace Selenium Measurement in Water Using Laser-Induced Fluorescence
           Assisted by Laser Ablation

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      Authors: Elton Soares de Lima Filho, Paul Bouchard, Mohamad Sabsabi, Guy Lamouche, Aïssa Harhira
      Abstract: Applied Spectroscopy, Ahead of Print.
      Selenium detection and removal from industrial and mining effluents have gained attention recently due to the negative effects of this trace element on aquatic life. However, the current methods for the detection of selenium in effluents are off-line by nature. In order to fill this gap, we investigated the use of laser ablation-assisted laser-induced fluorescence (LA-LIF) to measure trace amount of selenium in aqueous solutions. LA-LIF measurements are real time, label-free, standoff, and require no consumables as well as no sample preparation. They can provide a field-amenable, versatile tool for the measurement of selenium in the whole water treatment chain. We describe the system utilized, the temporal and fluence optimization studies, and the resulting calibration curve, which is linear over a wide dynamic range from parts-per-billion to tens of parts-per-million concentration levels. We also show that the achieved limit of detection of selenium can reach 32 µg/L using LA-LIF, without any kind of preconcentration or matrix transfer.
      Citation: Applied Spectroscopy
      PubDate: 2021-08-03T01:22:03Z
      DOI: 10.1177/00037028211035754
       
  • Compact Color Biofinder (CoCoBi): Fast, Standoff, Sensitive Detection of
           Biomolecules and Polyaromatic Hydrocarbons for the Detection of Life

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      Authors: Anupam K. Misra, Tayro E. Acosta-Maeda, Jie Zhou, Miles J. Egan, Luis Dasilveira, John N. Porter, Sonia J. Rowley, A Zachary Trimble, Patrick Boll, Macey W. Sandford, Christopher P. McKay, M. Nurul Abedin
      Abstract: Applied Spectroscopy, Ahead of Print.
      We have developed a compact instrument called the “COmpact COlor BIofinder”, or CoCoBi, for the standoff detection of biological materials and organics with polyaromatic hydrocarbons (PAHs) using a nondestructive approach in a wide area. The CoCoBi system uses a compact solid state, conductively cooled neodymium-doped yttrium aluminum garnet (Nd:YAG) nanosecond pulsed laser capable of simultaneously providing two excitation wavelengths, 355 and 532 nm, and a compact, sensitive-gated color complementary metal–oxide–semiconductor camera detector. The system is compact, portable, and determines the location of biological materials and organics with PAHs in an area 1590 cm2 wide, from a target distance of 3 m through live video using fast fluorescence signals. The CoCoBi system is highly sensitive and capable of detecting a PAH concentration below 1 part per billion from a distance of 1 m. The color images provide the simultaneous detection of various objects in the target area using shades of color and morphological features. We demonstrate that this unique feature successfully detected the biological remains present in a 150-million-year-old fossil buried in a fluorescent clay matrix. The CoCoBi was also successfully field-tested in Hawaiian ocean water during daylight hours for the detection of natural biological materials present in the ocean. The wide-area and video-speed imaging capabilities of CoCoBi for biodetection may be highly useful in future NASA rover–lander life detection missions.
      Citation: Applied Spectroscopy
      PubDate: 2021-07-26T02:51:05Z
      DOI: 10.1177/00037028211033911
       
  • Enhanced Fluorescence in a Scattering Medium

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      Authors: Nathan A. Giauque, Callum E. Flowerday, Steven R. Goates
      Abstract: Applied Spectroscopy, Ahead of Print.
      Often only small amounts of sample are available for spectroscopic analytical determinations. This work investigates the enhancement of signal in columns packed with silica particles. We propose that silica particles cause the light to scatter through the column, effectively increasing optical path length. Packed columns are shown to be effective with fluorescence spectroscopy, but results were inconclusive with absorbance spectroscopy.
      Citation: Applied Spectroscopy
      PubDate: 2021-07-16T10:31:07Z
      DOI: 10.1177/00037028211029312
       
  • Label-Free Fluorescent Aptasensor for Adenosine Triphosphate Detection
           Using SYBR Gold as a Probe

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      Authors: Jun Deng, Mengyu Niu, Xingquan Liu, Jin Feng, Shuang Ji, Zhijun Guo
      Abstract: Applied Spectroscopy, Ahead of Print.
      In this experimental research, a label-free sensing strategy is developed and employed to detect adenosine triphosphate with utilization of aptamers, including exonuclease I and SYBR Gold. The conformation of aptamers bonding to the specific target molecule (ATP) is transformed into an antiparallel G-quadruplex structure from a random coil. Afterwards, considering the unfolded aptamers are the preferred substrates for exonuclease I, the addition of exonuclease I is used so as to digest unfolded aptamers in the mixture in a selective manner. In the follow-up study, in order to strengthen the fluorescence intensity, SYBR Gold is applied as a fluorescent probe. The aptasensor presents the features of high selectivity against adenosine triphosphate and the low detecting limit of concentrations (39.2 nM). In order to verify the validation of experimental procedures and the practical application of the aptasensor, the detection of adenosine triphosphate for human serum samples is performed with satisfactory success. The recovery result with the range of 93.8%–108.1% is desirable and suggests that the designed approach is applicable. The outcomes of the cellular adenosine triphosphate assay manifest that the level of adenosine triphosphate concentrations in cell extracts can be monitored without the interference of other substances in the cells. Subject to its advantageous benefits (cost-effective, easiness, rapidity, and extraordinary selectivity), the designed approach has a promising implication for adenosine triphosphate detection in the research domain of bioanalytical science and biology.
      Citation: Applied Spectroscopy
      PubDate: 2021-07-14T02:33:44Z
      DOI: 10.1177/00037028211028668
       
  • High-Resolution Fourier Transform Infrared (FT-IR) Spectroscopic Imaging
           for Detection of Lung Structures and Cancer-Related Abnormalities in a
           Murine Model

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      Authors: Karolina Augustyniak, Karolina Chrabaszcz, Marta Smeda, Marta Stojak, Katarzyna M. Marzec, Kamilla Malek
      Abstract: Applied Spectroscopy, Ahead of Print.
      Label-free molecular imaging is a promising utility to study tissues in terms of the identification of their compartments as well as chemical features and alterations induced by disease. The aim of this work was to assess if higher magnification of optics in the Fourier transform infrared (FT-IR) microscope coupled with the focal plane detector resulted in better resolution of lung structures and if the histopathological features correlated with clustering of spectral images. FT-IR spectroscopic imaging was performed on paraffinized lung tissue sections from mice with optics providing a total magnification of 61× and 36×. Then, IR images were subjected to unsupervised cluster analysis and, subsequently, cluster maps were compared with hematoxylin and eosin staining of the same tissue section. Based on these results, we observed minute features such as cellular compartments in single alveoli and bronchiole, blood cells and megakaryocytes in a vessel as well as atelectasis of the lung. In the case of the latter, differences in composition were also noted between the tissue from the non-cancerous and cancerous specimen. This study demonstrated the ability of high-definition FT-IR imaging to evaluate the chemical features of well-resolved lung structures that could complement the histological examination widely used in animal models of disease.
      Citation: Applied Spectroscopy
      PubDate: 2021-06-23T10:19:46Z
      DOI: 10.1177/00037028211025540
       
  • Disposable Coverslip for Rapid Throughput Screening of Malaria Using
           Attenuated Total Reflection spectroscopy

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      Authors: Thulya Chakkumpulakkal Puthan Veettil, Kamila Kochan, Karen J. Edler, Paul De Bank, Philip Heraud, Bayden R. Wood
      Abstract: Applied Spectroscopy, Ahead of Print.
      Malaria is considered to be one of the most catastrophic health issues in the whole world. Vibrational spectroscopy is a rapid, robust, label-free, inexpensive, highly sensitive, nonperturbative, and nondestructive technique with high diagnostic potential for the early detection of disease agents. In particular, the fingerprinting capability of attenuated total reflection spectroscopy is promising as a point-of-care diagnostic tool in resource-limited areas. However, improvements are required to expedite the measurements of biofluids, including the drying procedure and subsequent cleaning of the internal reflection element to enable high throughput successive measurements. As an alternative, we propose using an inexpensive coverslip to reduce the sample preparation time by enabling multiple samples to be collectively dried together under the same temperature and conditions. In conjunction with partial least squares regression, attenuated total reflection spectroscopy was able to detect and quantify the parasitemia with root mean square error of cross-validation and R2 values of 0.177 and 0.985, respectively. Here, we characterize an inexpensive, disposable coverslip for the high throughput screening of malaria parasitic infections and thus demonstrate an alternative approach to direct deposition of the sample onto the internal reflection element.
      Citation: Applied Spectroscopy
      PubDate: 2021-05-06T01:10:54Z
      DOI: 10.1177/00037028211012722
       
  • Multivariate Analysis Aided Surface-Enhanced Raman Spectroscopy (MVA-SERS)
           Multiplex Quantitative Detection of Trace Fentanyl in Illicit Drug
           Mixtures Using a Handheld Raman Spectrometer

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      Authors: Ling Wang, Mario O. Vendrell-Dones, Chiara Deriu, Sevde Doğruer, Peter de B. Harrington, Bruce McCord
      First page: 1225
      Abstract: Applied Spectroscopy, Ahead of Print.
      Recently there has been upsurge in reports that illicit seizures of cocaine and heroin have been adulterated with fentanyl. Surface-enhanced Raman spectroscopy (SERS) provides a useful alternative to current screening procedures that permits detection of trace levels of fentanyl in mixtures. Samples are solubilized and allowed to interact with aggregated colloidal nanostars to produce a rapid and sensitive assay. In this study, we present the quantitative determination of fentanyl in heroin and cocaine using SERS, using a point-and-shoot handheld Raman system. Our protocol is optimized to detect pure fentanyl down to 0.20 ± 0.06 ng/mL and can also distinguish pure cocaine and heroin at ng/mL levels. Multiplex analysis of mixtures is enabled by combining SERS detection with principal component analysis and super partial least squares regression discriminate analysis (SPLS-DA), which allow for the determination of fentanyl as low as 0.05% in simulated seized heroin and 0.10% in simulated seized cocaine samples.
      Citation: Applied Spectroscopy
      PubDate: 2021-07-28T10:00:55Z
      DOI: 10.1177/00037028211032930
       
  • An improved Method for Determining Transient Fuel Dilution of Oil in an
           Internal-Combustion Engine Using Laser-Induced Florescence and
           Multivariate Least Square Calibration

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      Authors: Sneha Neupane, Vicente Boronat, Derek Splitter, William P. Partridge
      First page: 1237
      Abstract: Applied Spectroscopy, Ahead of Print.
      An optical diagnostic, based on laser-induced fluorescence (LIF), has been developed for on-engine measurements of real-time fuel dilution of engine oil or fuel in oil (FIO). Fuel dilution of oil is broadly relevant to advancing engine technology including durability, calibration, and catalyst-system management, and believed to promote destructive stochastic pre-ignition (SPI) during high-load engine operations. While standard (e.g., ASTM D3524-90) methods are not capable of real-time transient measurements, the LIF technique resolves transient dilution on the minutes time scale. We have expanded on our original FIO instrument development by introducing an improved analysis based on multivariate least square chemometrics analysis. The measurement uses a fuel dye (180–1300 parts per million, by mass) and monitors for its presence in the oil using 532 nm excitation and LIF. While the original FIO instrument utilized a two-color ratio method for analysis, the improved chemometric analysis uses the fully resolved LIF dye spectra to provide better predictive FIO accuracy (>92%) over a wide FIO range (1.5–14%) typical of engine application. We also investigate the effect of oil temperature on the LIF signal. Limited engine applications for demonstrating and validating the improved FIO instrument are shown, and the related data used to quantify practical detection limit and sensitivity. The improved analysis is insensitive to laser power fluctuation and change in detector integration time, providing an excellent FIO sensitivity (1–2%) and detection limit (0.01 %FIO) over a wide range of loads and injection timings, illustrating this updated approach to be a promising tool for advancing engine technology.
      Citation: Applied Spectroscopy
      PubDate: 2021-03-05T03:40:59Z
      DOI: 10.1177/0003702821996455
       
  • Device-Independent Discrimination of Falsified Amoxicillin Capsules Using
           Heterogeneous Near-Infrared Spectroscopic Devices for Training and Testing
           of a Support Vector Machine

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      Authors: Yusuke Hattori, Yuka Hoshi, Yasunori Ichimura, Yasuo Sugiura, Makoto Otsuka
      First page: 1251
      Abstract: Applied Spectroscopy, Ahead of Print.
      The objective of this work is to demonstrate the potential of near-infrared spectroscopy for common screening of falsified medicines in the field by means of a device-independent universal discrimination approach. In order to provide a useful discrimination tool to protect people from low-quality medical products, not only is a low-cost and portable screening device necessary, but a reference library is also essential. The authors believe that a device-dependent reference library inhibits near-infrared spectroscopy from becoming a popular screening tool. In this study, to develop a device-independent method, discrimination performance is evaluated using different devices for training and testing. The training data sets for the reference library were prepared using a bench-top Fourier transform near-infrared spectrophotometer, and predictive discrimination was performed using the spectral data by a low-cost and portable wavelength dispersive near-infrared spectrophotometer. A near-infrared spectrum-based support vector machine was used for these purposes, but the screening resulted in low accuracy thought to be caused by the intrinsically device-dependent features of the spectra data. Thus, principal component analysis was performed to collect the proper components to discriminate low-quality products from standard products. The principal component score-based support vector machine was able to produce highly accurate results, identifying falsified products with no false positive cases.
      Citation: Applied Spectroscopy
      PubDate: 2021-03-08T03:27:48Z
      DOI: 10.1177/0003702821999659
       
  • Determination of Elemental Composition in Soft Biological Tissue Using
           Laser Ablation Inductively Coupled Plasma Mass Spectrometry: Method
           Validation

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      Authors: Geriene O. LaBine, Philip P. Molloy, Jennie R. Christensen
      First page: 1262
      Abstract: Applied Spectroscopy, Ahead of Print.
      Determination of elemental concentrations in biological tissue is fundamental to many environmental studies. Analytical methods typically used to quantify concentrations in such studies have minimum sample volumes that necessitate lethal or impactful collection of tissues. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) has small sample volume requirements and offers environmental practitioners an opportunity to employ low-impact sample collection methods. Environmental applications of LA-ICP-MS are limited by the lack of validated methods, partly due to the need for dry samples and scarcity of matrix-matched certified reference materials (CRMs). This study validates an LA-ICP-MS method to determine concentrations of 30 elements in soft biological tissue (fish ovary and muscle). Tissue samples (median: 0.48 grams (g); inter-quartile range: 0.30 g to 0.56 g wet weight) were dehydrated, powdered, compressed into pellets (weighing approximately 0.03 g) and analyzed using LA-ICP-MS alongside three matrix-matched CRMs. The method yielded concentration determinations for CRM elements that were typically accurate to within 30% of theoretical concentrations, and precise (relative standard deviation
      Citation: Applied Spectroscopy
      PubDate: 2021-04-22T10:48:15Z
      DOI: 10.1177/00037028211008535
       
  • Assessment of Bulk Composition of Heterogeneous Food Matrices Using Raman
           Spectroscopy

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      Authors: Petter Vejle Andersen, Jens Petter Wold, Nils Kristian Afseth
      First page: 1278
      Abstract: Applied Spectroscopy, Ahead of Print.
      Raman spectroscopy (RS) has for decades been considered a promising tool for food analysis, but widespread adoption has been held back by, e.g., high instrument costs and sampling limitations regarding heterogeneous samples. The aim of the present study was to use wide area RS in conjunction with surface scanning to overcome the obstacle of heterogeneity. Four different food matrices were scanned (intact and homogenized pork and by-products from salmon and poultry processing) and the bulk chemical parameters such as fat and protein content were estimated using partial least squares regression (PLSR). The performance of PLSR models from RS was compared with near-infrared spectroscopy (NIRS). Good to excellent results were obtained with PLSR models from RS for estimation of fat content in all food matrices (coefficient of determination for cross-validation (R2CV) from 0.73 to 0.96 and root mean square error of cross-validation (RMSECV) from 0.43% to 2.06%). Poor to very good PLSR models were obtained for estimation of protein content in salmon and poultry by-product using RS (R2CV from 0.56 to 0.92 and RMSECV from 0.85% to 0.94%). The performance of RS was similar to NIRS for all analyses. This work demonstrates the applicability of RS to analyze bulk composition in heterogeneous food matrices and paves way for future applications of RS in routine food analyses.
      Citation: Applied Spectroscopy
      PubDate: 2021-04-22T10:50:04Z
      DOI: 10.1177/00037028211006150
       
  • Feasibility of Using Boltzmann Plots to Evaluate the Stark Broadening
           Parameters of Cu(I) Lines

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      Authors: Mohamed Fikry, Ibraheem A. Alhijry, Abdelnasser M. Aboulfotouh, Ashraf M. El Sherbini
      First page: 1288
      Abstract: Applied Spectroscopy, Ahead of Print.
      A linear Boltzmann plot was constructed using Cu(I) lines of well-known atomic parameters. Aligning other spectral lines to the plot was adopted as a viable way to estimate the most probable values of Stark broadening parameters of Cu(I) lines at 330.79, 359.91, and 360.2 nm. Plasma was generated by focusing neodymium-doped yttrium aluminum garnet (Nd:YAG) laser radiation at wavelength 532 nm on a pure copper target in open air. Plasma emission was recorded at delay times of 3, 4, 5, 7, and 10 μs. The in situ optically thin Hα line was used to determine the plasma reference electron density over the entire experiment. Following this method, the missing values of the Stark broadening parameters of the three Cu(I) lines turn out to be about 0.15 ± 0.05 Å (for 330.79 nm transition) and 0.17 ± 0.05 Å (for 359.91 360.20 nm transition) at reference electron density of (1 ± 0.09) × 1017 cm–3 and temperature of 10 800 ± 630 K. The apparent variation in plasma parameters at different delay times was found to scale with electron density and temperature as ∼ne.Te0.166.
      Citation: Applied Spectroscopy
      PubDate: 2021-05-26T10:44:41Z
      DOI: 10.1177/00037028211013371
       
  • Characterization of Drug Resistance in Chronic Myeloid Leukemia Cells
           Based on Laser Tweezers Raman Spectroscopy

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      Authors: Qian Zhang, Minlu Ye, Lingyan Wang, Dongmei Jiang, Shuting Yao, Donghong Lin, Yang Chen, Shangyuan Feng, Ting Yang, Jianda Hu
      First page: 1296
      Abstract: Applied Spectroscopy, Ahead of Print.
      Multidrug resistance is highly associated with poor prognosis of chronic myeloid leukemia. This work aims to explore whether the laser tweezers Raman spectroscopy (LTRS) could be practical in separating adriamycin-resistant chronic myeloid leukemia cells K562/adriamycin from its parental cells K562, and to explore the potential mechanisms. Detection of LTRS initially reflected the spectral differences caused by chemoresistance including bands assigned to carbohydrates, amino acid, protein, lipids, and nucleic acid. In addition, principal components analysis as well as the classification and regression trees algorithms showed that the specificity and sensitivity were above 90%. Moreover, the band data-based classification and regression tree model and receiver operating characteristic curve further determined some important bands and band intensity ratios to be reliable indexes in discriminating K562 chemoresistance status. Finally, we highlighted three metabolism pathways correlated with chemoresistance. This work demonstrates that the label-free LTRS analysis combined with multivariate statistical analyses have great potential to be a novel analytical strategy at the single-cell level for rapid evaluation of the chemoresistance status of K562 cells.
      Citation: Applied Spectroscopy
      PubDate: 2021-06-23T02:17:23Z
      DOI: 10.1177/00037028211024581
       
  • Simple Ultraviolet–Visible Spectroscopy-Based Assay for Fast Evaluation
           of Magnetic Nanoparticle Selectivity Changes After Doping

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      Authors: Jacek Sikorski, Norbert Obarski, Maciej Trzaskowski, Magdalena Matczuk
      First page: 1305
      Abstract: Applied Spectroscopy, Ahead of Print.
      Simple ultraviolet–visible spectroscopy-based methodology was proposed and utilized for the initial characterization of potential changes in selectivity of doped magnetic nanoparticles. Doped and undoped iron(II,III) (Fe3O4) magnetic nanoparticles were synthesized by the coprecipitation method. The doping processes of nanoparticles were confirmed using optical emission spectrometry, while the sizes of undoped and Cu-doped nanoparticles were investigated using a high-resolution field emission scanning electron microscope. The average diameters of nanoparticles were 8.34±1.78 nm and 9.12±1.93 nm, for doped and undoped materials, respectively. The influence of the nanoparticle's doping on their selectivity towards chosen analyte was monitored by the spectral techniques such as ultraviolet–visible and optical emission spectrometry. The interaction between Cu-doped Fe3O4 nanoparticles and cuprizone (a compound forming the characteristic colorful complex with copper) was confirmed. The elaborated studies proved the potential of ultraviolet–visible spectroscopy for the fast qualification of magnetic nanoparticles in terms of their ability to separate the selected analyte from the sample matrix.
      Citation: Applied Spectroscopy
      PubDate: 2021-07-14T01:35:38Z
      DOI: 10.1177/00037028211028669
       
  • A Lanthanide Complex Fluorescent Probe for the Detection of Melamine

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      Authors: Xiaolin Li, Chaoqun Ma, Lei Li, Hui Gao, Jiao Gu, Chun Zhu, Yamin Wu, Senqi Guo, Yitao Wei, Guoyu Wang, Zirui Wang, Guoqing Chen
      First page: 1312
      Abstract: Applied Spectroscopy, Ahead of Print.
      Melamine has been illegally adulterated in dairy food because of the rich nitrogen content and stable chemical properties in recent years. Therefore, the detection of melamine is of great significance for food safety supervision and human health protection. As melamine is a weak fluorescent substance, it is difficult to detect melamine directly by fluorescence spectroscopy. In this work, we found that melamine can significantly enhance the emission of the tetracycline–europium (EuTC) complex at 616 nm. Therefore, we took EuTC complex as a fluorescent probe to detect melamine. According to the characterizations of absorption spectra, molecular electrostatic potential distribution, and the time-resolved spectra, we speculated that tetracycline and melamine may form a complex through hydrogen bonding interaction in the melamine-EuTC reaction system, causing the melamine closer approach to Eu3+ and reducing the non-radiative energy loss of water molecules to Eu3+, which significantly enhanced the fluorescence intensity of EuTC. The fluorescence intensity of EuTC complex with melamine concentration in the range of 0.5–40.0 μM shows a good linear relationship, and the correlation coefficient is 0.9951 with the detection limit of 7.85 × 10−8 M. It shows a high sensitivity for the EuTC complex as a fluorescent probe to detect melamine, which provides a supplement and extension for the detection of melamine by fluorescence spectroscopy.
      Citation: Applied Spectroscopy
      PubDate: 2021-06-08T02:25:45Z
      DOI: 10.1177/00037028211022375
       
  • Acoustic Steering Using Thermally-induced Optical Reflection of Sound
           (THORS)

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      Authors: Daniel S. Kazal, An Ngo, Ellen L. Holthoff, Brian M. Cullum
      First page: 1320
      Abstract: Applied Spectroscopy, Ahead of Print.
      Using the recently discovered THermally-induced Optical Reflection of Sound (THORS) phenomenon, it is possible to generate optically induced, local density barriers in air by the absorption of intense, modulated laser light (the THORS phenomenon), which results in abrupt differences in compressibility of the air at these barriers that can efficiently reflect incident acoustic waves. In this note, we demonstrate the ability to optically manipulate and reflect acoustic waves in air as well as optimize the functional parameters (optical modulation and acoustic frequency) and characterize the effects of common physical parameters, including localized thermal gradients and incident angle of reflection on the efficiency of the resulting acoustic reflection. Finally, the ability to efficiently steer acoustic waves around a physical obstruction using THORS is also demonstrated.
      Citation: Applied Spectroscopy
      PubDate: 2021-03-31T03:02:54Z
      DOI: 10.1177/00037028211004601
       
 
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