Feature Papers in Spectroscopy Journal

A special issue of Spectroscopy Journal (ISSN 2813-446X).

Deadline for manuscript submissions: closed (28 February 2025) | Viewed by 29359

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Department of Chemistry, and Macromolecular Science & Engineering, College of Arts and Science, Case Western Reserve University, Millis Science Center, Office 223 10900 Euclid Ave., Cleveland, OH 44106, USA
Interests: ultrafast laser spectroscopy; photoscience; nanoscience; materials science; bio- and energy applications; photomedicine
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Published Papers (21 papers)

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26 pages, 3631 KiB  
Article
Exploring Time-Resolved Fluorescence Data: A Software Solution for Model Generation and Analysis
by Thomas-Otavio Peulen
Spectrosc. J. 2025, 3(2), 16; https://doi.org/10.3390/spectroscj3020016 - 1 May 2025
Abstract
Time-resolved fluorescence techniques, such as fluorescence lifetime imaging microscopy (FLIM), fluorescence correlation spectroscopy (FCS), and time-resolved fluorescence spectroscopy, are ideally suited for investigating molecular dynamics and interactions in biological and chemical systems. However, the analysis and interpretation of these datasets require advanced computational [...] Read more.
Time-resolved fluorescence techniques, such as fluorescence lifetime imaging microscopy (FLIM), fluorescence correlation spectroscopy (FCS), and time-resolved fluorescence spectroscopy, are ideally suited for investigating molecular dynamics and interactions in biological and chemical systems. However, the analysis and interpretation of these datasets require advanced computational tools capable of handling diverse models and datasets. This paper presents a comprehensive software solution designed for model generation and analysis of time-resolved fluorescence data with a strong focus on fluorescence for quantitative structural analysis and biophysics. The software supports the integration of multiple fluorescence techniques and provides users with robust tools for performing complex model analysis across diverse experimental data. By enabling global analysis, model generation, data visualization, and sampling over model parameters, the software enhances the interpretability of intricate fluorescence phenomena. By providing flexible modeling capabilities, this solution offers a versatile platform for researchers to extract meaningful insights from time-resolved fluorescence data, aiding in the understanding of dynamic biomolecular processes. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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19 pages, 6192 KiB  
Article
Dynamic FTIR Spectroscopy for Assessing the Changing Biomolecular Composition of Bacterial Cells During Growth
by Gary Hastings, Michael Nelson, Caroline Taylor, Alex Marchesani, Wilbur Hudson, Yi Jiang and Eric Gilbert
Spectrosc. J. 2025, 3(2), 15; https://doi.org/10.3390/spectroscj3020015 - 14 Apr 2025
Viewed by 192
Abstract
Fourier-transform infrared (FTIR) spectroscopy can detect biomolecular changes in bacterial cells in response to drugs or other stimuli. Fully developing this area requires an understanding of IR spectral changes associated with the growth of unperturbed cells. Such an understanding is still lacking, however. [...] Read more.
Fourier-transform infrared (FTIR) spectroscopy can detect biomolecular changes in bacterial cells in response to drugs or other stimuli. Fully developing this area requires an understanding of IR spectral changes associated with the growth of unperturbed cells. Such an understanding is still lacking, however. To address this issue, attenuated total reflectance (ATR) FTIR spectroscopy has been used to probe changes in the composition of Staphylococcus aureus ATCC 6538 cells during exponential growth, with a 30 min time resolution. We find prominent spectral changes in proteins, nucleic acids, and carbohydrates evolving from the early (30–120 min) to the late (240–360 min) log phase of growth. Principal component analysis (PCA) shows that spectra obtained for cells during the early and late log phases of growth can be discriminated against with 100% accuracy. Protein-related spectral features are most significant in spectra collected at 30- and 90-min post-inoculation and provide a robust basis for temporal differentiation. Spectral changes that occur during the first 30 min after inoculation are shown to reverse over the next 30–120 min, indicating dynamic adaptations during cellular growth. Overall, we demonstrate a band assignment strategy based on time resolution, underscoring the utility of FTIR spectroscopy in dynamic studies of bacterial cells. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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18 pages, 3200 KiB  
Article
Influence of Tissue Curvature on the Absolute Quantification in Frequency-Domain Diffuse Optical Spectroscopy
by Giovani G. Martins, Rodrigo M. Forti and Rickson C. Mesquita
Spectrosc. J. 2025, 3(2), 14; https://doi.org/10.3390/spectroscj3020014 - 13 Apr 2025
Viewed by 146
Abstract
Accurate estimation of optical properties and hemodynamic parameters is critical for advancing frequency-domain diffuse optical spectroscopy (FD-DOS) techniques in clinical neuroscience. However, conventional FD-DOS models often assume planar air–tissue interfaces, introducing errors in anatomically curved regions such as the forehead or infant heads. [...] Read more.
Accurate estimation of optical properties and hemodynamic parameters is critical for advancing frequency-domain diffuse optical spectroscopy (FD-DOS) techniques in clinical neuroscience. However, conventional FD-DOS models often assume planar air–tissue interfaces, introducing errors in anatomically curved regions such as the forehead or infant heads. This study evaluates the impact of incorporating tissue curvature into forward models for FD-DOS analysis. Using simulations and optical phantoms, we demonstrate that curved models reduce errors in absorption coefficient estimation from 20% to less than 10% in high-curvature scenarios. Within the curvatures tested, even minor curvature mismatches resulted in errors significantly lower than those observed from planar approximations (p < 0.001). In low-curvature regions, curved models yielded errors comparable to planar models (<5% in both cases). When applied to human data, our proposed curved model increased absorption and hemoglobin concentration estimates by 10–15% compared to standard semi-infinite models, closer to physiological expectations. Overall, these results quantitatively demonstrate that accounting for tissue curvature in FD-DOS forward models significantly improves the accuracy of optical property estimation. We propose a numerical framework that achieves this in a fast and reliable manner, advancing FD-DOS as a robust tool for clinical and research applications in anatomically complex regions. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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18 pages, 5740 KiB  
Article
The Presence of Excitons in Short Single-Stranded DNA Revealed by Absorption and Circular Dichroism Spectroscopy
by Alessandra Picchiotti, Amy L. Stevens, Valentyn I. Prokhorenko and R. J. Dwayne Miller
Spectrosc. J. 2025, 3(2), 11; https://doi.org/10.3390/spectroscj3020011 - 28 Mar 2025
Viewed by 263
Abstract
This paper presents a systematic absorption and circular dichroism spectroscopy study of short single strands of DNA, from 2 to 20 bases. They are composed of a sequence-specific nucleobase composition, either adenine (A), thymine (T), or AT repeats. The absorption spectra hypochromism and [...] Read more.
This paper presents a systematic absorption and circular dichroism spectroscopy study of short single strands of DNA, from 2 to 20 bases. They are composed of a sequence-specific nucleobase composition, either adenine (A), thymine (T), or AT repeats. The absorption spectra hypochromism and the circular dichroism one show butterfly-shaped spectra. Data analysis conducted on the spectra of these oligomers provides evidence for the formation of excitons and their delocalization length along the strand of DNA in relation to how many bases are involved in the excitonic coupling. In particular, the extent of this coupling is limited to adjacent nucleobases in the case of pure adenine strands but spans multiple nucleobases in the case of pure thymine strands. Predictably, AT repeats show a mixed behavior between the two. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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19 pages, 6803 KiB  
Article
Point-of-Care No-Specimen Diagnostic Platform Using Machine Learning and Raman Spectroscopy: Proof-of-Concept Studies for Both COVID-19 and Blood Glucose
by Allen B. Chefitz, Rohit Singh, Thomas Birch, Yongwu Yang, Arib Hussain and Gabriella Chefitz
Spectrosc. J. 2025, 3(1), 6; https://doi.org/10.3390/spectroscj3010006 - 19 Feb 2025
Viewed by 510
Abstract
Significance: We describe a novel, specimen-free diagnostic platform that can immediately detect both a metabolite (glucose) or an infection (COVID-19) by non-invasively using Raman spectroscopy and machine learning. Aim: Current diagnostic testing for infections and glucose monitoring requires specimens, disease-specific reagents and processing, [...] Read more.
Significance: We describe a novel, specimen-free diagnostic platform that can immediately detect both a metabolite (glucose) or an infection (COVID-19) by non-invasively using Raman spectroscopy and machine learning. Aim: Current diagnostic testing for infections and glucose monitoring requires specimens, disease-specific reagents and processing, and it increases environmental waste. We propose a new hardware–software paradigm by designing and constructing a finger-scanning hardware device to acquire Raman spectroscopy readouts which, by varying the machine learning algorithm to interpret the data, allows for diverse diagnoses. Approach: A total of 455 patients were enrolled prospectively in the COVID-19 study; 148 tested positive and 307 tested negative through nasal PCR testing conducted concurrently with testing using our viral detector. The tests were performed on both outpatients (N = 382) and inpatients (N = 73) at Holy Name Medical Center in Teaneck, NJ, between June 2021 and August 2022. Patients’ fingers were scanned using an 830 nm Raman System and then, using machine learning, processed to provide an immediate result. In a separate study between April 2023 and August 2023, measurements using the same device and scanning a finger were used to detect blood glucose levels. Using a Dexcom sensor and an Accu-Chek device as references, a cross-validation-based regression of 205 observations of blood glucose was performed with a machine learning algorithm. Results: In a five-fold cross-validation analysis (including asymptomatic patients), a machine learning classifier using the Raman spectra as input achieved a specificity for COVID-19 of 0.837 at a sensitivity of 0.80 and an area under receiver operating curve (AUROC) of 0.896. However, when the data were split by time, with training data consisting of observations before 1 July 2022 and test data consisting of observations after it, the model achieved an AUROC of 0.67, with 0.863 sensitivity at a specificity of 0.517. This decrease in AUROC may be due to substantial domain shift as the virus evolves. A similar five-fold cross-validation analysis of Raman glucose detection produces an area under precision–recall curve (AUPR) of 0.58. Conclusions: The combination of Raman spectroscopy, AI/ML, and our patient interface admitting only a patient’s finger and using no specimen offers unprecedented flexibility in introducing new diagnostic tests or adapting existing ones. As the ML algorithm can be iteratively re-trained with new data and the software deployed to field devices remotely, it promises to be a valuable tool for detecting rapidly emerging infectious outbreaks and disease-specific biomarkers, such as glucose. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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8 pages, 680 KiB  
Article
Evaluation of Spatial Distribution of Crystallinity Induced by Local Heating Using Low-Frequency Raman Spectroscopy on Polyether Ether Ketone (PEEK)
by Tomoko Numata, Naomoto Ishikawa, Toshihiro Shimada, Keith C. Gordon and Makoto Yamaguchi
Spectrosc. J. 2024, 2(4), 341-348; https://doi.org/10.3390/spectroscj2040021 - 18 Dec 2024
Viewed by 730
Abstract
Local heating was performed on a thermoplastic polymer film by contact with the tip of a soldering iron heated above the glass-transition temperature. The locally heated area was measured using microscopic Raman scattering spectroscopy, and the spatial distribution of the crystallinity was obtained [...] Read more.
Local heating was performed on a thermoplastic polymer film by contact with the tip of a soldering iron heated above the glass-transition temperature. The locally heated area was measured using microscopic Raman scattering spectroscopy, and the spatial distribution of the crystallinity was obtained from the low-frequency peak. The crystallinity distribution can be evaluated using the microscale spatial resolution. The temperature distribution around the locally heated area was calculated by applying the heat conduction equation, and good correspondence was obtained with the obtained crystallinity. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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10 pages, 2057 KiB  
Article
Laminated Information Encryption with Printer Using Laser-Induced Breakdown Spectroscopy
by Xiang Han, Li Shen, Lixing Yao and Yu Liu
Spectrosc. J. 2024, 2(4), 322-331; https://doi.org/10.3390/spectroscj2040019 - 8 Dec 2024
Viewed by 795
Abstract
In order to improve the security of information encryption, this paper proposes a novel method based on laser-induced breakdown spectroscopy (LIBS) technology in conjunction with a commercial general-purpose inkjet printer. A “sandwich” model, comprising three layers of a black ink block, a blue [...] Read more.
In order to improve the security of information encryption, this paper proposes a novel method based on laser-induced breakdown spectroscopy (LIBS) technology in conjunction with a commercial general-purpose inkjet printer. A “sandwich” model, comprising three layers of a black ink block, a blue ink layer containing encrypted information, and another black ink block in order to render the information layer undetectable by other conventional optical imagers, was proposed. Because of the lower resolution requirements and better error tolerance of the Quick Response (QR) code, it was used as encryption information carrier. The “sandwich” structure was printed onto original paper using a commercial inkjet printer. The spatial distribution of the “LIBS secret key” on the paper was analyzed by LIBS spectra at different locations. After baseline removal, normalization, and spectral superposition, the contrast of decrypted images is enhanced to extract hidden information effectively. This method has the advantages of high security, low cost, and simple fabrication. It provides a new method with a potential application prospect for LIBS in the field of information encryption. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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19 pages, 2247 KiB  
Article
Diode Laser Absorption Spectroscopy and DSMC Calculations for the Determination of Species-Specific Diffusion Coefficients of a CO2-N2O Gas Mixture in the Transition Gas Regime
by Kannan Munusamy, Harald Kleine and Sean O’Byrne
Spectrosc. J. 2024, 2(4), 287-305; https://doi.org/10.3390/spectroscj2040017 - 25 Nov 2024
Viewed by 957
Abstract
Multicomponent gas mixture diffusion in a microscale confined flow in the transition gas regime at Knudsen numbers (Kn) above 0.1 has potential engineering applications in gas-phase microfluidics. Although the calculation of the diffusion coefficient accounts for the influence of the concentration of other [...] Read more.
Multicomponent gas mixture diffusion in a microscale confined flow in the transition gas regime at Knudsen numbers (Kn) above 0.1 has potential engineering applications in gas-phase microfluidics. Although the calculation of the diffusion coefficient accounts for the influence of the concentration of other species in a multicomponent gas mixture, the higher rate of gas-wall collision at 0.1 < Kn ≤ 10 introduces additional complications not predicted by conventional calculation methods. Thus, simultaneous measurement of diffusion coefficients for multiple gas species ensures accurate estimation of the diffusion coefficient of a particular species that includes the effect of interactions with other species and wall surface conditions in a multicomponent gas mixture at Kn > 0.1. However, most experimental methods for measuring the diffusion coefficient are not species-specific and therefore cannot directly differentiate between the species diffusing in a gas mixture. Thus, this paper demonstrates a new experiment methodology consisting of a two-bulb diffusion configuration accompanied by a tunable diode laser absorption spectroscopy detection technique for species-specific, in-situ, simultaneous measurement of the effective diffusion coefficient for a CO2-N2O gas mixture in the transition gas regime. The experimental results are compared against direct simulation Monte Carlo calculations and the Bosanquet approximation showing a deviation that has not been reported in the literature before. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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10 pages, 3112 KiB  
Article
Benchtop 19F Nuclear Magnetic Resonance (NMR) Spectroscopy-Optimized Knorr Pyrazole Synthesis of Celecoxib and Mavacoxib, 3-(Trifluoromethyl) Pyrazolyl Benzenesulfonamides, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
by Andrew Chyu, Selina Xi, Joshua Kim, Galen Liu, Indalina Chan, Seoyeon Hong, Allen Ke, Thomas Lavery, Anushree Marimuthu, Arjun Akula and Edward Njoo
Spectrosc. J. 2024, 2(4), 206-215; https://doi.org/10.3390/spectroscj2040014 - 11 Nov 2024
Viewed by 1798
Abstract
Fluorinated organic compounds have demonstrated remarkable utility in medicinal chemistry due to their enhanced metabolic stability and potent therapeutic efficacy. Several examples exist of fluorinated non-steroidal anti-inflammatory drugs (NSAIDs), including diflunisal, flurbiprofen, and trifluoromethylated pyrazoles celecoxib and mavacoxib. These trifluoromethylated pyrazoles, which are [...] Read more.
Fluorinated organic compounds have demonstrated remarkable utility in medicinal chemistry due to their enhanced metabolic stability and potent therapeutic efficacy. Several examples exist of fluorinated non-steroidal anti-inflammatory drugs (NSAIDs), including diflunisal, flurbiprofen, and trifluoromethylated pyrazoles celecoxib and mavacoxib. These trifluoromethylated pyrazoles, which are most commonly constructed through the cyclocondensation of a trifluorinated 1,3-dicarbonyl and an aryl hydrazine, are also found in numerous other drug candidates. Here, we interrogate the effects of solvents and the presence of Brønsted or Lewis acid catalysts on catalyzing this process. We highlight the utility of benchtop 19F NMR spectroscopy in enabling the real-time quantification of reaction progress and the identification of fluorinated species present in crude reaction mixtures without the need for cost-prohibitive deuterated solvents. Ultimately, we find that the reaction solvent has the greatest impact on the rate and product yield, and also found that the relationship between the keto-enol equilibrium of the dicarbonyl starting material pyrazole formation rate is highly solvent-dependent. More broadly, we describe the optimization of the yield and kinetics of trifluoromethylpyrazole formation in the synthesis of celecoxib and mavacoxib, which is made possible through high-throughput reaction screening on benchtop NMR. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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17 pages, 707 KiB  
Article
PyRAMD Scheme: A Protocol for Computing the Infrared Spectra of Polyatomic Molecules Using ab Initio Molecular Dynamics
by Denis S. Tikhonov
Spectrosc. J. 2024, 2(3), 171-187; https://doi.org/10.3390/spectroscj2030012 - 13 Sep 2024
Viewed by 1109
Abstract
Here, we present a general framework for computing the infrared anharmonic vibrational spectra of polyatomic molecules using Born–Oppenheimer molecular dynamics (BOMD) with PyRAMD software. To account for nuclear quantum effects, we suggest using a simplified Wigner sampling (SWS) approach simultaneously coupled with Andersen [...] Read more.
Here, we present a general framework for computing the infrared anharmonic vibrational spectra of polyatomic molecules using Born–Oppenheimer molecular dynamics (BOMD) with PyRAMD software. To account for nuclear quantum effects, we suggest using a simplified Wigner sampling (SWS) approach simultaneously coupled with Andersen and Berendsen thermostats. We propose a new criterion for selecting the parameter of the SWS based on the molecules’ harmonic vibrational frequencies and usage of the large-time-step blue shift correction, allowing for a decrease in computational expenses. For the Fourier transform of the dipole moment autocorrelation function, we propose using the regularized least-squares analysis, which allows us to obtain higher-frequency resolution than with the direct application of fast Fourier transform. Finally, we suggest the usage of the pre-parameterized scaling factors for the IR spectra from BOMD, also providing the scaling factors for the spectra at the BLYP-D3(BJ)/6-31G, PBE-D3(BJ)/6-31G, and PBEh-3c levels of theory. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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13 pages, 6650 KiB  
Article
Spectroscopic Analyses of Blue Pigments in the Manoscritto Parmense 3285 from the 14th Century
by Giuseppe Marghella, Stefania Bruni, Alessandro Gessi, Lorena Tireni, Alberto Ubaldini and Flavio Cicconi
Spectrosc. J. 2024, 2(3), 158-170; https://doi.org/10.3390/spectroscj2030011 - 10 Sep 2024
Viewed by 1478
Abstract
During the restoration and digitalization intervention of the Manoscritto Parmense (Ms. Parm.) 3285 codex, a 14th-century illuminated volume that contains the three books of Dante Alighieri’s Divina Commedia belonging to the Biblioteca Palatina of Parma, the deposits present in the center of some [...] Read more.
During the restoration and digitalization intervention of the Manoscritto Parmense (Ms. Parm.) 3285 codex, a 14th-century illuminated volume that contains the three books of Dante Alighieri’s Divina Commedia belonging to the Biblioteca Palatina of Parma, the deposits present in the center of some bifoliums were removed using soft bristle brushes and collected. A preliminary observation of these deposits with a stereomicroscope allowed the detection of some pigment grains of different colors, likely detached from the full-page illuminations at the beginning of each book. These grains of the pigments were then analyzed in the Bologna ENEA Research Centre through Scanning Electron Microscopy (SEM), EDX microanalysis, and micro-Raman spectroscopy, allowing the identification of the minerals or the compounds used as pigments. Consequently, some pigments that were commonly used in the Middle Ages such as gold leaf, typically employed in illuminations and the decoration of heading initials, cinnabar red, and different types of blue pigments, including traces of lapis lazuli and azurite, were identified. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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18 pages, 4236 KiB  
Article
Development and Validation of a Near Infra-Red (NIR) Hand-held Spectrophotometric Method Using PCA Approaches and Chemometric Tools: Application for Qualitative and Quantitative Determination of Tadalafil Marketed in Kinshasa—D.R. Congo
by Jocelyn Mankulu Kakumba, Patient Ciza Hamuli, Merdie Mpemba Luyinama, Freddy Mugisho Kasago, Malachie Tembo Monyele, Dadit Ive Kitenge, Trésor Bayebila Menanzambi, Trésor Kimbeni Malongo, Didi Mana Kialengila and Jérémie Mbinze Kindenge
Spectrosc. J. 2024, 2(3), 105-122; https://doi.org/10.3390/spectroscj2030007 - 3 Jul 2024
Viewed by 1483
Abstract
A hand-held NIR spectrophotometric method was developed, validated, and applied for the determination of tadalafil in tablets. The aim of our work was to develop analytical methods based on vibrational techniques using low-cost portable equipment. Based on different chemometric modeling, we attempted to [...] Read more.
A hand-held NIR spectrophotometric method was developed, validated, and applied for the determination of tadalafil in tablets. The aim of our work was to develop analytical methods based on vibrational techniques using low-cost portable equipment. Based on different chemometric modeling, we attempted to validate the method, which gave encouraging results from the principal component analysis (PCA), DD-SIMCA, and PLS modeling. Following this, we optimized the method using an appropriate experiment plan. For validation, we used the total error approach with acceptance limits set at ±10% with a risk level of 5%. The method showed that it was possible to perform both qualitative and quantitative analysis of pharmaceutical products using low-cost portable NIR systems with chemometric tools. The developed approach enabled the completion of the first step in implementing an NIR method for quality control of tadalafil-based drugs in the DRC. Validation difficulties of the PLS method resulted from the lack of information about inter-day serial variations of spectral responses. It would be interesting to extend the study to a larger calibration interval in order to correct uncertainties that may result from the variability observed under different conditions and to verify robustness. These are the limitations of this work, but the results are nevertheless very encouraging. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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15 pages, 3831 KiB  
Article
Raman Spectra of Blood Serum as Holistic Biomarker for Differential Auxiliary Diagnoses of Attention Deficit and Hyperactivity Disorder (ADHD) in Adults
by Gizem Yavuz Dogan, Gokhan Halimoglu, Dilara Kaplanoglu, Umut Mert Aksoy, Ali Kandeger, Elif Yavuz, Sehban Kartal, Rui Fausto and Gulce Ogruc Ildiz
Spectrosc. J. 2024, 2(2), 53-67; https://doi.org/10.3390/spectroscj2020004 - 14 Apr 2024
Cited by 1 | Viewed by 2418
Abstract
Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition, impacting approximately 10% of children globally. A significant proportion, around 30–50%, of those diagnosed during childhood continue to manifest ADHD symptoms into adulthood, with 2–5% of adults experiencing the condition. The existing [...] Read more.
Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition, impacting approximately 10% of children globally. A significant proportion, around 30–50%, of those diagnosed during childhood continue to manifest ADHD symptoms into adulthood, with 2–5% of adults experiencing the condition. The existing diagnostic framework for ADHD relies on clinical assessments and interviews conducted by healthcare professionals. This diagnostic process is complicated by the disorder’s overlap in symptoms and frequent comorbidities with other neurodevelopmental conditions, particularly bipolar disorder during its manic phase, adding complexity to achieving accurate and timely diagnoses. Despite extensive efforts to identify reliable biomarkers that could enhance the clinical diagnosis, this objective remains elusive. In this study, Raman spectroscopy, combined with multivariate statistical methods, was employed to construct a model based on the analysis of blood serum samples. The developed partial least-squares discriminant analysis (PLS-DA) model demonstrated an ability to differentiate between individuals with ADHD, healthy individuals, and those diagnosed with bipolar disorder in the manic phase, with a total accuracy of 97.4%. The innovative approach in this model involves utilizing the entire Raman spectrum, within the 450–1720 cm−1 range, as a comprehensive representation of the biochemical blood serum setting, thus serving as a holistic spectroscopic biomarker. This method circumvents the necessity to pinpoint specific chemical substances associated with the disorders, eliminating the reliance on specific molecular biomarkers. Moreover, the developed model relies on a sensitive and reliable technique that is cost-effective and rapid, presenting itself as a promising complementary diagnostic tool for clinical settings. The potential for Raman spectroscopy to contribute to the diagnostic process suggests a step forward in addressing the challenges associated with accurately identifying and distinguishing ADHD from other related conditions. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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16 pages, 4899 KiB  
Article
A Spectroscopy-Based Multi-Analytical Approach for Studies in Conservation: Decorations in the Alexander Palace (Tsarskoye Selo)
by Marilena Ricci, Federico Sebastiani, Maurizio Becucci, Mikhail Rogozny and Vadim Parfenov
Spectrosc. J. 2023, 1(3), 121-136; https://doi.org/10.3390/spectroscj1030011 - 20 Oct 2023
Cited by 1 | Viewed by 1532
Abstract
We studied the painted decorations found during recent restoration work in the Alexander Palace in Tsarskoye Selo. Optical/laser spectroscopic methods were applied to obtain a characterization of the materials, pigments, and binders in use and, possibly, their degradation. We analyzed samples of the [...] Read more.
We studied the painted decorations found during recent restoration work in the Alexander Palace in Tsarskoye Selo. Optical/laser spectroscopic methods were applied to obtain a characterization of the materials, pigments, and binders in use and, possibly, their degradation. We analyzed samples of the original Art Nouveau style decoration that was detached in 2019 during conservation work at the State Office of Emperor Nicholas II. A combination of Raman microscopy, infrared spectroscopy, and elemental analysis (obtained from the optical emission following laser plasma formation) allowed us to obtain detailed information on the materials used. The precious pigments of the artist’s green-blue palette and the binder used (drying oil) were identified. A mixture of blue (Prussian blue and ultramarine blue), white (lead white and barium white), and yellow (chrome yellow and zinc yellow) pigments determined the different blue hues used. The use of bronze paint in the dark blue area, which was identified as a brass powder applied with a drying oil as a binder, was also demonstrated. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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13 pages, 3247 KiB  
Article
Effect of Alkaline Salts on Pyrolyzed Solid Wastes in Used Edible Oils: An Attenuated Total Reflectance Analysis of Surface Compounds as a Function of the Temperature
by Francisca Romero-Sarria, Concepción Real, José Manuel Córdoba, María Carmen Hidalgo and María Dolores Alcalá
Spectrosc. J. 2023, 1(2), 98-110; https://doi.org/10.3390/spectroscj1020009 - 13 Sep 2023
Viewed by 1509
Abstract
Biochars obtained via the pyrolysis of biomass are very attractive materials from the point of view of their applications and play key roles in the current energy context. The characterization of these carbonaceous materials is crucial to determine their field of application. In [...] Read more.
Biochars obtained via the pyrolysis of biomass are very attractive materials from the point of view of their applications and play key roles in the current energy context. The characterization of these carbonaceous materials is crucial to determine their field of application. In this work, the pyrolysis of a non-conventional biomass (solid wastes in used edible oils) was investigated. The obtained biochars were characterized using conventional techniques (TG, XRD, and SEM-EDX), and a deep analysis via ATR-FTIR was performed. This spectroscopic technique, which is a rapid and powerful tool that is well adapted to study carbon-based materials, was employed to determine the effect of temperature on the nature of functional groups on the surface. Moreover, the water washing of the raw sample (containing important quantities of inorganic salts) before pyrolysis evidenced that the inorganic salts act as catalysts in the biomass degradation and influence the degree of condensation (DOC) of PAH. Moreover, it was observed that these salts contribute to the retention of oxygenated compounds on the surface of the solid. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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16 pages, 2372 KiB  
Article
Barrier to Methyl Internal Rotation and Equilibrium Structure of 2-Methylthiophene Determined by Microwave Spectroscopy
by Kenneth J. Koziol, Hamza El Hadki, Arne Lüchow, Natalja Vogt, Jean Demaison and Ha Vinh Lam Nguyen
Spectrosc. J. 2023, 1(1), 49-64; https://doi.org/10.3390/spectroscj1010005 - 30 May 2023
Cited by 6 | Viewed by 2303
Abstract
The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra [...] Read more.
The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra of the 34S and 13C isotopologues allowed the determination of the semiexperimental equilibrium structure (reSE). Comparing the structure to that of thiophene revealed a decrease in the ∠(S−C2−C3) angle from 111.595(6)° to 111.37(1)° by addition of the methyl group to the C(2) position, as well as an increase in the S−C2 bond length from 1.7102(1) Å to 1.7219(2) Å. A–E splittings from internal rotation of the methyl group were observed, and the V3 potential in the vibrational ground state was determined to be 197.7324(18) cm−1. The V3 value and the rotational constants A, B, C were calculated with a large number of different methods and basis sets for benchmarking purposes by comparing them to the fitted parameters. The V3 value was also compared to those of other thiophene and furan derivatives to gain a better understanding of the steric and electrostatic effects in these classes of compounds. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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12 pages, 1237 KiB  
Article
Age-Related Fourier-Transform Infrared Spectroscopic Changes in Protein Conformation in an Aging Model of Human Dermal Fibroblasts
by Cláudia Martins, Idália Almeida, Sandra Rebelo, Sandra Magalhães and Alexandra Nunes
Spectrosc. J. 2023, 1(1), 37-48; https://doi.org/10.3390/spectroscj1010004 - 24 Apr 2023
Cited by 2 | Viewed by 2462
Abstract
The loss of proteostasis, which results in the accumulation of misfolded proteins, is one of the hallmarks of aging and is frequently associated with the aging process. Fibroblasts are a cellular model widely used in the study of aging and can mimic the [...] Read more.
The loss of proteostasis, which results in the accumulation of misfolded proteins, is one of the hallmarks of aging and is frequently associated with the aging process. Fibroblasts are a cellular model widely used in the study of aging and can mimic the loss of proteostasis that occurs in the human body. When studying human aging using fibroblasts, two approaches can be used: fibroblasts from the same donor aged in vitro until senescence or fibroblasts from donors of different ages. A previous study by our group showed that the first approach can be used in the study of aging. Thus, this work aimed to study the spectroscopic profile of human dermal fibroblasts from four donors of different ages using Fourier-transform infrared spectroscopy to identify changes in protein conformation and to compare results with those obtained in the previous study. Partial least squares regression analysis and peak intensity analysis suggested that fibroblasts from older donors were characterized by an increase in the levels of antiparallel β-sheets and a decrease in intermolecular β-sheets, in agreement with our previous results. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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Review

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24 pages, 1224 KiB  
Review
Spectroscopic Advances in Real Time Monitoring of Pharmaceutical Bioprocesses: A Review of Vibrational and Fluorescence Techniques
by Abhishek Mishra, Mohammad Aghaee, Ibrahim M. Tamer and Hector Budman
Spectrosc. J. 2025, 3(2), 12; https://doi.org/10.3390/spectroscj3020012 - 1 Apr 2025
Viewed by 483
Abstract
The pharmaceutical industry has witnessed exponential growth in production volumes, driven by factors such as an aging global population and the COVID-19 pandemic. To meet the demand for high product quality alongside increased productivity, there is a growing emphasis on developing innovative Fermentation [...] Read more.
The pharmaceutical industry has witnessed exponential growth in production volumes, driven by factors such as an aging global population and the COVID-19 pandemic. To meet the demand for high product quality alongside increased productivity, there is a growing emphasis on developing innovative Fermentation Analytical Technology (FAT) and Process Analytical Technology (PAT) tools for real-time performance monitoring, modeling, measurement, and control. Building on our earlier work involving in-line monitoring of Bordetella pertussis fermentations using fluorescence spectroscopy, this review explores and compares the applications of vibrational and fluorescence spectroscopy for real-time bioprocess monitoring. We examine recent technological advancements and ongoing challenges in the field. Various spectroscopic techniques are evaluated in terms of cost-effectiveness and practical applicability, with a particular focus on in-line spectroscopy as a promising, low-cost solution for effective bioprocess monitoring. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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18 pages, 1540 KiB  
Review
Advantages of In Situ Mössbauer Spectroscopy in Catalyst Studies with Precaution in Interpretation of Measurements
by Károly Lázár
Spectrosc. J. 2025, 3(1), 10; https://doi.org/10.3390/spectroscj3010010 - 17 Mar 2025
Viewed by 202
Abstract
Mössbauer spectroscopy can be advantageous for studying catalysts. In particular, its use in in situ studies can provide unique access to structural features. However, special attention must be paid to the interpretation of data, since in most studies, the samples are not perfectly [...] Read more.
Mössbauer spectroscopy can be advantageous for studying catalysts. In particular, its use in in situ studies can provide unique access to structural features. However, special attention must be paid to the interpretation of data, since in most studies, the samples are not perfectly homogeneous. Balance and compromise should be found between the refinement of evaluations by extracting and interpreting data from spectra, while also considering the presence of possible inhomogeneities in samples. In this review, examples of studies on two types of catalysts are presented, from which, despite possible inhomogeneities, clear statements can be derived. The first example pertains to selected iron-containing microporous zeolites (with 57Fe Mössbauer spectroscopy), from which unique information is collected on the coordination of iron ions. The second example is related to studies on supported PtSn alloy particles (with 119Sn probe nuclei), from which reversible modifications of the tin component due to interactions with the reaction partners are revealed. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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23 pages, 5872 KiB  
Review
Interpreting the Microwave Spectra of Diatomic Molecules—Part II: Nuclear Quadrupole Coupling of One Nucleus
by Cory C. Pye
Spectrosc. J. 2024, 2(3), 82-104; https://doi.org/10.3390/spectroscj2030006 - 27 Jun 2024
Viewed by 1189
Abstract
The effect of nuclear quadrupole coupling of a single nucleus on the rotational spectra of diatomic molecules is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra. The microwave spectra of some alkali halides, interhalogen [...] Read more.
The effect of nuclear quadrupole coupling of a single nucleus on the rotational spectra of diatomic molecules is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra. The microwave spectra of some alkali halides, interhalogen diatomics, and deuterium halides provide excellent examples for analysis and for student exercises. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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25 pages, 5230 KiB  
Review
Interpreting the Microwave Spectra of Diatomic Molecules
by Cory C. Pye
Spectrosc. J. 2023, 1(1), 3-27; https://doi.org/10.3390/spectroscj1010002 - 8 Feb 2023
Cited by 2 | Viewed by 4382
Abstract
A brief review of the theory of the rigid rotor and its application to microwave spectroscopy is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra, and the theory is extended to the harmonic nonrigid [...] Read more.
A brief review of the theory of the rigid rotor and its application to microwave spectroscopy is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra, and the theory is extended to the harmonic nonrigid rotor and anharmonic nonrigid rotor when needed. The microwave spectra of carbon monoxide, and of some alkali halides, provide excellent examples for analysis and for student exercises. Full article
(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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