Raman Spectroscopy Research Articles

RamanSPy: An Open-Source Python Package for Integrative Raman Spectroscopy Data Analysis.

Raman spectroscopy is a nondestructive and label-free chemical analysis technique, which plays a key role in the analysis and discovery cycle of various branches of science. Nonetheless, progress in Raman spectroscopic analysis is still impeded by the lack of software, methodological and data standardization, and the ensuing fragmentation and lack of reproducibility of analysis workflows thereof. To address these issues, we introduce RamanSPy, an open-source Python package for Raman spectroscopic research and analysis. RamanSPy provides a comprehensive library of tools for spectroscopic analysis that supports day-to-day tasks, integrative analyses, the development of methods and protocols, and the integration of advanced data analytics. RamanSPy is modular and open source, not tied to a particular technology or data format, and can be readily interfaced with the burgeoning ecosystem for data science, statistical analysis, and machine learning in Python. RamanSPy is hosted at https://github.com/barahona-research-group/RamanSPy, supplemented with extended online documentation, available at https://ramanspy.readthedocs.io, that includes tutorials, example applications, and details about the real-world research applications presented in this paper.

Synthesis, Characterization, and Applications of Carbon Dots for Determination of Pharmacological and Biological Samples: A Review.

Carbon dots (CDs) are a novel category of carbon-based nanomaterials characterized by their small size, often less than 10 nm. CDs physical, chemical, and optical properties can be tuned using one-pot assembly. Because of their non-toxicity, biocompatibility, chemical and physical responsiveness, photo- and chemical-bleaching resistance, and low cost, nanoparticles have become incredibly versatile. They find various applications in detecting inorganic substances, bio sensing, visualizing cells, studying biological processes in live cells, and aiding in medication delivery. Additionally, CDs exhibit versatility in electronics and energy storage, making them promising candidates for applications in solar cells, light-emitting diodes, and supercapacitors. CDs are more photo stable for hours than typical fluorescent semiconductor quantum dots. Before applying CDs, they must be characterized. Techniques such as UV-VIS spectroscopy, fluorescence spectrophotometry, FT-IR, TEM, XRD, Raman spectroscopy, and NMR are commonly used to assess their photophysical and structural properties. This article review explores the synthesis, characterization applications of CDs in analytical techniques for the determination of various analytes. The article provides a detailed analysis of the different methodologies used to make nanomaterials and devices for the characterization of CDs. It also discusses the challenges that arise when using CDs in analytical techniques for detecting different analytes. The focus of this review is on accurately determining pharmaceutical and biological samples using CDs as sensing probes.

Balancing the Binding of Intermediates Enhances Alkaline Hydrogen Oxidation on D-Band Center Modulated Pd Sites.

Exploring efficient alkaline hydrogen oxidation reaction (HOR) electrocatalysts is of great concern for constructing anion exchange membrane fuel cells (AEMFCs). Herein, d-band center modulated PdCo alloys with ultralow Pd content anchored onto the defective carbon support (abbreviated as PdCo/NC hereafter) are proposed as highly efficient HOR catalyst. The as-prepared catalyst exhibits exceptional HOR performance compared to the Pt/C catalyst, achieving thermodynamically spontaneous and kinetically preferential reactions. Specifically, the resultant PdCo/NC demonstrates a marked enhancement in alkaline HOR performance, with the highest mass and specific activities of 1919.6 mA mgPd-1 and 1.9 mA cm-2, 51.1 and 4.2 times higher than those of benchmark of Pt/C, along with an excellent stability in a chronoamperometry test. In the analysis of in situ Raman spectra, it was discovered that tetrahedrally coordinated H-bonded water molecules were formed during the HOR process. This indicates that the promotion of interfacial water molecule formation and enhancement of HOR activities in PdCo/NC are facilitated by defect engineering and the turning of d-band center in PdCo alloy. The essential knowledge obtained in this study could open up a new direction for modifying the electronic structure of cost-effective HOR catalysts through electronic structure engineering.

Can Aluminum Cations Promote Nucleation for THF Hydrate Growth?

Rapid nucleation of tetrahydrofuran (THF) hydrate is essential for developing a THF hydrate-based cold storage technology. Earlier works have hypothesized the role of aluminum complexes in initiating the nucleation of clathrate hydrates using aluminum metal electrodes and substrates. This study investigates if the nucleation promotional effect of hydrate can be achieved using the aluminum salt, AlCl3, due to the formation of aluminum aqua complexes in water. Metal chlorides NaCl and MgCl2 are also utilized to evaluate the effect of cation type in initiating nucleation, i.e., the effect of charge/radius ratio. The induction time is measured in a stirred reactor at various subcoolings and concentrations of 0.05, 0.1, 0.5, 1, and 2 wt %. The nucleation time is studied in two reactor configurations based on the nature of salt introduction in the THF solution, i.e., salt premixed in solution and salt injected inside the solution. The sudden rise in the reactor temperature due to hydrate formation is used as an indicator of hydrate formation. Results indicate that AlCl3 promotes hydrate nucleation as AlCl3 reduces induction time by 92.2% at 0.05 wt % concentration compared with water. Nearly instantaneous nucleation is also achieved by directly injecting AlCl3. MgCl2 and NaCl do not show a similar effect on induction time as AlCl3. The pH and Raman spectra measurements with and without salts are carried out to explain the effect of cations on the THF-water solution.

Predicting altered bone biomechanics in juvenile mice: insights from microgravity simulation, loading interventions, and Raman Spectroscopy

BackgroundMicrogravity, a condition experienced in a spatial environment, poses unique challenges to the skeletal system, particularly in juvenile organisms. This study aimed to investigate alterations in bone biomechanics of juvenile mice due to unloading – that simulates microgravity in the laboratory—and the effects of a bone-loading intervention. We compared bone compositional and mechanical properties between 21-six-week-old C57Bl/6 from a control group (wild type) and a group that underwent a tail-suspension unloading protocol to mimic microgravity (MG). The second group (MG) experienced additional in vivo loading protocol (MG + LDG) on the right hind leg, where dynamic compressive loading was applied to the right knee using a custom-built loading device.ResultsOur results show that after two weeks, we successfully induced bone alterations by (i) decreasing the energy dissipated before fracture and (ii) decreasing the yield and maximum stress. In addition, we showed that Mineral to matrix component [ν1PO4/Amide I], Carbonate to Amide [CO3/Amide I], and Crystallinity [1/FWHM(ν1PO4)] are strongly linked in physiological bone but not in microgravity even after loading intervention. While Crystallinity is very sensitive to bone deformation (strain) alterations coming from simulated microgravity, we show that Carbonate to Amide [CO3/Amide I] – a common marker of turnover rate/remodeling activity—is a specific predictor of bone deformation for bone after simulated microgravity. Our results also invalidate the current parameters of the loading intervention to prevent bone alterations entirely in juvenile mice.ConclusionsOur study successfully induced bone alterations in juvenile mice by using an unloading protocol to simulate microgravity, and we provided a new Raman Spectroscopy (RS) dataset of juvenile mice that contributes to the prediction of cortical bone mechanical properties, where the degree of interrelationship for RS data for physiological bone is improved compared to the most recent evidence.

Optofluidic Force Induction Meets Raman Spectroscopy and Inductively Coupled Plasma-Mass Spectrometry: A New Hyphenated Technique for Comprehensive and Complementary Characterizations of Single Particles.

Nanoparticles are produced at accelerating rates, are increasingly integrated into scientific and industrial applications, and are widely discharged into the environment. Analytical techniques are required to characterize parameters such as particle number concentrations, mass and size distributions, molecular and elemental compositions, and particle stability. This is not only relevant to investigate their utility for various industrial or medical applications and for controlling the manufacturing processes but also to assess toxicity and environmental fate. Different analytical strategies aim to characterize certain facets of particles but are difficult to combine to retrieve relevant parameters coherently and to provide a more comprehensive picture. In this work, we demonstrate the first online hyphenation of optofluidic force induction (OF2i) with Raman spectroscopy and inductively coupled plasma-time-of-flight-mass spectrometry (ICP-TOFMS) to harness their complementary technology-specific advantages and to promote comprehensive particle characterizations. We optically trapped individual particles on a weakly focused vortex laser beam by aligning a microfluidic flow antiparallelly to the laser propagation direction. The position of particles in this optical trap depended on the hydrodynamic diameter and therefore enabled size calibration as well as matrix elimination. Additionally, laser light scattered on particles was analyzed in a single particle (SP) Raman spectroscopy setup for the identification of particulate species and phases. Finally, particles were characterized regarding elemental composition and their distributions in mass and size using SP ICP-TOFMS. In a proof of concept, we analyzed polystyrene-based microplastic and TiO2 nanoparticles and demonstrated the opportunities provided through the coupling of OF2i with SP Raman and SP ICP-TOFMS.

Uranium Oxide Hydrate Frameworks with Dy(III) or Lu(III) Ions: Insights Into the Framework Structures With Lanthanide Ions.

Two uranium oxide hydrate frameworks (UOHFs) with either Dy3+ or Lu3+ ions, Dy1.36(H2O)6[(UO2)10UO13(OH)4] (UOHF-Dy) or Lu2(H2O)8[(UO2)10UO14(OH)3] (UOHF-Lu), were synthesized hydrothermally and characterized with a range of structural and spectroscopic techniques. Although SEM-EDS analysis confirmed the same atomic ratio of ~5.5 for U : Dy and U : Lu, they displayed different crystal morphologies, needles for UOHF-Dy in the orthorhombic C2221 space group and plates for UOHF-Lu in the triclinic P-1 space group. Both frameworks are composed of β-U3O8 type layers linked by pentagonal bipyramidal uranium polyhedra, with the Dy3+/Lu3+ ions inside the channels. However, the arrangements of Dy3+/Lu3+ ions are different, with disordered Dy3+ ions well aligned at the centers of the channels and single Lu3+ ions well-separated in a zigzag pattern in the channels. While the characteristic vibrational modes were revealed by Raman spectroscopy, the presence of a pentavalent uranium center in UOHF-Lu was confirmed with diffuse reflectance spectroscopy. The formation of two types of UOHFs with lanthanide ions, high or low symmetry, and the structure trend were discussed regards to synthesis conditions and lanthanide ionic radius. This work highlights the complex chemistry driving the formation of UOHFs with lanthanide ions and has implications to the spent nuclear fuel under geological disposal.

Enhancing dye-sensitized solar cell performance: Optimizing Cu2ZnSnS4/ZnCo2O4 nanocomposites as efficient and cost-effective counter electrodes

This study investigates the utilization of Cu2ZnSnS4/ZnCo2O4 (CZTS/ZCO) nanocomposites prepared through hydrothermal and combustion methods as counter electrodes in Dye-Sensitized Solar Cells (DSSCs). Different ratios of Cu2ZnSnS4 and ZnCo2O4 were explored, and comprehensive analyses were conducted using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), High-Resolution TEM (HRTEM), Brunauer–Emmett–Teller (BET) surface area analysis, Raman Spectroscopy, Electrochemical Impedance Spectroscopy (EIS), cyclic voltammetry (CV), Tafel analysis, Field Emission Scanning Electron Microscopy (FESEM), and Incident Photon-to-Electron Conversion Efficiency (IPCE), alongside long-term stability assessments. The CZTS:ZCO ratio of 2:1 exhibited the highest efficiency, reaching 8.81 %, with an open-circuit voltage of 729 mV, short-circuit current of 17.80 mAcm−2, and a fill factor of 67.9 %. This surpasses the efficiency of the reference Pt cell (8.42 %), which had an open-circuit voltage of 735 mV, short-circuit current of 17.16 mAcm−2, and a fill factor of 66.8 %. The average crystallite sizes for the main peaks of CZTS and ZCO samples were estimated to be 19.8 and 16.7 nm, respectively. The crystallite size can significantly affect the charge transfer and conductivity in the counter electrode during electrochemical processes; the presence of nanocrystals with these sizes can notably enhance the electrochemical properties and conductivity of the synthesized samples. Raman analysis results indicate that no additional phases or secondary phases such as ZnS and CuSnS3 have formed in the kesterite CZTS structure, and the crystal has formed as a single phase. Additionally, the F2g modes in the Raman spectrum of ZCO indicate tetrahedral units in the spinel ZCO structure, and the A1g modes represent octahedral structures in this phase, indicating the formation of suitable ZCO phase. The superior performance of the CZTS/ZCO nanocomposite can be attributed to its enhanced crystalline structure, superior charge transport characteristics, and improved electrocatalytic behaviours.

Glass reinforced plastic (GRP) boats and the impact on coastal environment – Evidence of fibreglass ingestion by marine bivalves from natural populations

Classified as marine debris, man made materials are polluting the world’s oceans. Recently, glass reinforced plastic (GRP) has been shown to degrade and contaminate the coasts. In this pioneering study, fibreglass particles have been detected in the soft parts of oysters and mussels collected from natural populations, in front of an active boatyard. The presence of particulate glass, with concentrations up to 11,220 particles/kg ww in Ostrea edulis and 2740 particles/kg ww in Mytilus edulis, was confirmed by micro Raman spectroscopy. The results showed higher accumulation during the winter months, when boat maintenance activities are peaking and, through repair work, the release of glass fibres in the environment is more likely. Bivalves are considered high risk species due to their sessile nature and extensive filter feeding behaviour. The microparticle inclusion may contribute to adverse impacts on physiological processes and eventually to a decline in the overall health and subsequent death of the animal. The high costs involved in the proper GRP disposal and the lack of recycling facilities worldwide lead to boat abandonement and further contamination of the coasts. For the first time this study presents the extensive fibreglass contamination of natural bivalve populations, in a popular South England sailing harbour, designated a biological and geological site of specific scientific interest (SSRI).

Simultaneous measurement of water temperature and salinity using Raman spectroscopy

Simultaneous measurement of water temperature and salinity using Raman spectroscopy

Electrodeposition behaviour of samarium in 1,3-dimethyl-2-imidazolidone solvent

Abstract The present study investigates the electrochemistry spectroscopy of Sm(III), and electrodeposition of samarium metal in neutral ligand-based ionic liquid (solvate ionic liquid). Mixture consisted of a samarium precursor (either samarium triflate or samarium nitrate hexahydrate) in the solvate ionic liquid, 1.3-dimethyl-2-imidazolidone (DMI). FT-IR analysis of Sm(III)-DMI electrolytes indicates that Sm3+ ion coordinates with DMI through carbonyl group (C=O); the band splits into two with emergence of new peak at 1630 cm−1 and 1649 cm−1 for the triflate and nitrate solutions, respectively. Raman spectroscopy also confirms the solvation of Sm(III) with DMI through oxygen atom of the carbonyl group. Voltametric behaviour of Sm(III) ion indicates two-step reduction mechanism via Sm(III)/Sm(II) at ca. −2.0 V and Sm(II)/Sm(0) at ca. −3.0 V vs. Ag/Ag+ for both samarium(III)-containing electrolytes. Diffusion coefficient value of Sm(III) was determined to be 2.185 × 10−6 cm2/s and 2.418 × 10−8 cm2/s for triflate and nitrate electrolytes, respectively. Electrodeposition of samarium was achieved through constant potential electrolysis using copper substrate as the working electrode which yielded compact deposits from triflate-DMI and non-uniform granular deposit from nitrate-DMI electrolyte. Ex situ X-ray photoelectron spectroscopy analysis of the as-deposited samples revealed the presence of metallic Sm (1081 eV) co-existing with its oxide form (1083 eV).

Reversal of crystallization in cryoprotected samples by laser editing.

Advances in cryobiology techniques commonly target either the cooling or the warming cycle, while little thought has been given to ≪repair≫ protocols applicable during cold storage. In particular, crystallization is the dominant threat to cryopreserved samples but proceeds from small nuclei that are innocuous if further growth is forestalled. To this end, we propose a laser editing technique that locally heats individual crystals above their melting point by a focused nanosecond pulse, followed by amorphization during rapid resolidification. As a reference, we first apply the approach to ice crystals in cryoprotected solution and use Raman confocal mapping to study the deactivation of crystalline order. Then, we examine dimethyl sulfoxide trihydrate crystals that can germinate at low temperatures in maximally freeze concentrated regions, as commonly produced by equilibrium cooling protocols. We show how to uniquely identify this phase from Raman spectra and evidence retarded growth of laser-edited crystals during warming.

Temperature dependence mechanism of high-temperature oxidation of transition metal silicide MoSi2.

Transition metal silicides represented by MoSi2 have excellent oxidation resistance and are widely used as high-temperature anti-oxidation coatings in hot end components of power equipment. However, the mechanism of temperature-dependent growth of MoSi2 oxidation products has not been revealed. Therefore, this study investigated the formation characteristics of oxide film and silicide-poor compound on MoSi2 at temperatures of 1000-1550℃ through high-temperature oxidation experiments, combined with microscopic Raman spectroscopy, SEM, and XRD characterizations. The result showed that MoSi2 underwent high-temperature selective oxidation reactions at 1000-1200℃, forming MoO2 and SiO2 oxide film on the substrate. As the oxidation temperature increased to 1550℃, after 100 hours of oxidation, along with the disappearance of MoO2 and the phase transformation of SiO2, a continuous Mo5Si3 layer with a thickness of approximately 47 μm was formed at the SiO2-MoSi2 interface. Thermodynamics and kinetic calculations further revealed the mechanism of temperature-dependent growth of oxidation products (MoO2 and Mo5Si3) during high-temperature oxidation process of MoSi2. As the temperature increased, the diffusion flux ratio of O and Si decreased, leading to a decrease in oxygen concentration at the interface and promoting the growth of the Mo5Si3 layer. Its thickness is an important indicator for evaluating the oxidation resistance of MoSi2 coatings during service. This study provides experimental and mechanistic insights into the temperature-dependent growth behavior of Mo5Si3 during the high-temperature oxidation of MoSi2 coating, and provides guidance for predicting the service life and improving the oxidation resistance of silicide coatings.

Applications of multi-parameter sensing in pharmaceutical, agriculture and mineral industries using THz spectroscopy and Low-Wavenumber Raman spectroscopy

Multi-parameter sensing using non-destructive optical spectroscopic techniques, specifically Terahertz spectroscopy and low-wavenumber Raman spectroscopy (also known as THz-Raman spectroscopy), has significantly reshaped the landscape of analytical methodologies in various industries. This comprehensive review article elucidates the transformative impact of these advanced spectroscopic methods within the fields of pharmaceutical, agriculture, and mineral industry. As technology continues to evolve, the ability to concurrently analyse multiple parameters at the molecular level has become a cornerstone for precision and efficiency in these critical sectors. In the pharmaceutical industry, THz spectroscopy has emerged as a key tool in ensuring the quality and stability of drug formulations, while low-wavenumber Raman spectroscopy complements by offering insights into chemical structure as well as composition. The agricultural sector benefits from the capabilities of these spectroscopic techniques in optimizing crop management, soil analysis, and resource utilization. Simultaneously, the mineral industry leverages THz and low-wavenumber Raman spectroscopy for accurate mineral identification, aiding in exploration, extraction, and processing. Through this review, we aim to provide a nuanced understanding of how multi-parameter sensing through THz and low-wavenumber Raman spectroscopy is driving innovation, enhancing quality control, and fostering sustainable practices across diverse industrial landscapes.

Pt1.8Pd0.2CuGa Intermetallic Nanocatalysts with Enhanced Methanol Oxidation Performance for Efficient Hybrid Seawater Electrolysis.

Seawater electrolysis is a potentially cost-effective approach to green hydrogen production, but it currently faces substantial challenges for its high energy consumption and the interference of chlorine evolution reaction (ClER). Replacing the energy-demanding oxygen evolution reaction (OER) with the methanol oxidation reaction (MOR) represents a promising alternative, as the MOR occurs at a significantly low anodic potential, which cannot only reduces the voltage needed for electrolysis but also completely circumvents the ClER. To this end, developing high-performance MOR catalysts is a key. Herein, we report a novel quaternary Pt1.8Pd0.2CuGa/C intermetallic nanoparticles (i-NPs) catalyst, which shows a high mass activity (11.13 A mgPGM -1), a large specific activity (18.13mA cmPGM -2), and outstanding stability toward alkaline MOR. Advanced in-situ surface-enhanced Raman spectroscopy (SERS), online differential mass spectrometry (DEMS) and density functional theory (DFT) calculations reveal that the introduction of atomically distributed Pd in Pt2CuGa intermetallic markedly promotes the oxidation of key reaction intermediates by enriching electron concentration around Pt sites, resulting in weak adsorption of carbon-containing intermediates and favorable adsorption of the synergistic OH- groups near Pd sites. Using Pt1.8Pd0.2CuGa/C i-NPs as anodic catalysts, we demonstrate MOR-assisted seawater electrolysis that continuously operates under 1.23V for 240h in simulated seawater and 120h in natural seawater without notable degradation, showing great potential for energy-saving and cost-competitive hydrogen production from seawater. This article is protected by copyright. All rights reserved.

Chiral Stacking Identification of Two-Dimensional Triclinic Crystals Enabled by Machine Learning.

Chiral materials possess broken inversion and mirror symmetry and show great potential in the application of next-generation optic, electronic, and spintronic devices. Two-dimensional (2D) chiral crystals have planar chirality, which is nonsuperimposable on their 2D enantiomers by any rotation about the axis perpendicular to the substrate. The degree of freedom to construct vertical stacking of 2D monolayer enantiomers offers the possibility of chiral manipulation for designed properties by creating multilayers with either a racemic or enantiomerically pure stacking order. However, the rapid recognition of the relative proportion of two enantiomers becomes demanding due to the complexity of stacking orders of 2D chiral crystals. Here, we report the unambiguous identification of racemic and enantiomerically pure stackings for layered ReSe2 and ReS2 using circular polarized Raman spectroscopy. The chiral Raman response is successfully manipulated by the enantiomer proportion, and the stacking orders of multilayer ReSe2 and ReS2 can be completely clarified with the help of second harmonic generation and scanning transmission electron microscopy measurements. Finally, we trained an artificial intelligent Spectra Classification Assistant to predict the chirality and the complete crystallographic structures of multilayer ReSe2 from a single circular polarized Raman spectrum with the accuracy reaching 0.9417 ± 0.0059.

Effects of Gamma Irradiation on Polyethylene Terephthalate and Detection of Microplastic Particles Down to 1 μm.

In response to increasing concern about the impact of plastic degradation on the environment, this study investigates the degradation of virgin and recycled polyethylene terephthalate (PET) under γ-irradiation in aqueous solutions, with particular focus on the resulting formation of microplastic particles (MP). By exposing both virgin and recycled PET samples to different doses of γ-irradiation (10, 50, and 100 kGy), a comprehensive analysis using UV-vis spectroscopy, dynamic light scattering (DLS) and micro-Raman spectroscopy is presented. The results, highlighted by micro-Raman spectroscopy, show that γ-irradiation produces micrometer-sized plastic particles, with the recycled PET having a significantly higher MP content than its original counterpart. Careful examination reveals the presence of a stabilizer in samples of recycled PET juice bottles. This study not only contributes to our understanding of the effects of γ-irradiation on PET but also highlights the need for further research into the environmental impact of such processes. The insights gained shed light on the behavior of PET under γ-irradiation and the resulting impact on microplastic pollution and make an important contribution to our understanding of the broader environmental context.

Diagnostic accuracy of autofluorescence-Raman spectroscopy for surgical margin assessment during Mohs micrographic surgery of basal cell carcinoma.

Autofluorescence (AF) - Raman spectroscopy is a technology that can detect residual basal cell carcinoma (BCC) on the resection margin of fresh surgically excised tissue specimens. The technology does not require tissue fixation, staining, labelling, or sectioning, and provides quantitative diagnosis maps of the surgical margins in 30 minutes. To determine the accuracy of the AF-Raman instrument to detect incomplete excisions of BCC during Mohs micrographic surgery, using histology as reference standard. Skin layers from 130 patients undergoing Mohs surgery at the Nottingham University Hospitals NHS Trust (September 2022 to July 2023) were investigated with the AF-Raman instrument. The layers were measured fresh, immediately after excision. The AF-Raman results and the intra-operative assessment by Mohs surgeons were compared to a post-operative consensus-derived reference produced by three dermatopathologists. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated. The AF-Raman analysis was successfully completed for 125 out of the 130 layers. The AF-Raman analysis covered 91% of the specimen surface area on average, with the lowest being 87% for eyelid and the highest being 94% for forehead specimens. The AF-Raman instrument identified positive margins in 24 out of 36 BCC-positive cases, resulting in a 67% sensitivity (95% confidence intervals (CI): 49%-82%) and negative margins in 65 out of 89 BCC-negative cases, resulting in a 73% specificity (95% CI 63%-82%). Only one out of the 12 false negative cases was caused by misclassification by the AF-Raman algorithm. The other 11 false negatives cases were produced because no valid Raman signal was recorded at the location of the residual BCC due to either occlusion by blood or poor contact between tissue and cassette window. The intra-operative diagnosis by Mohs surgeons identified positive margins in 31 out of 36 BCC-positive cases, 86% sensitivity (95% CI: 70%-95%), and negative margins in 79 out of 89 BCC-negative cases, 89% specificity (95% CI: 81%-95%). This study shows that the AF-Raman instrument has potential for intra-operative microscopic assessment of surgical margins in surgery of BCC. Further improvements are required for tissue processing to ensure complete coverage of the surgical specimens. ClinicalTrials.gov ID NCT03482622.

Research on disease diagnosis based on teacher-student network and Raman spectroscopy.

Diabetic nephropathy is a serious complication of diabetes, and primary Sjögren's syndrome is a disease that poses a major threat to women's health. Therefore, studying these two diseases is of practical significance. In the field of spectral analysis, although common Raman spectral feature selection models can effectively extract features, they have the problem of changing the characteristics of the original data. The teacher-student network combined with Raman spectroscopy can perform feature selection while retaining the original features, and transfer the performance of the complex deep neural network structure to another lightweight network structure model. This study selects five flow learning models as the teacher network, builds a neural network as the student network, uses multi-layer perceptron for classification, and selects the optimal features based on the evaluation indicators accuracy, precision, recall, and F1-score. After five-fold cross-validation, the research results show that in the diagnosis of diabetic nephropathy, the optimal accuracy rate can reach 98.3%, which is 14.02% higher than the existing research; in the diagnosis of primary Sjögren's syndrome, the optimal accuracy rate can be reached 100%, which is 10.48% higher than the existing research. This study proved the feasibility of Raman spectroscopy combined with teacher-student network in the field of disease diagnosis by producing good experimental results in the diagnosis of diabetic nephropathy and primary Sjögren's syndrome.

Spectroscopic Investigation of Tomato Seed Germination Stimulated by Trichoderma spp.

Seed germination is a complex process that can be negatively affected by numerous stresses. Trichoderma spp. are known as effective biocontrol agents as well as plant growth and germination stimulators. However, understanding of the early interactions between seeds and Trichoderma spp. remains limited. In the present paper, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to reveal the nature of tomato seed germination as stimulated by Trichoderma. A rapid response of tomato seeds to Trichoderma spp. was observed within 48 h on Murashige and Skoog medium (MS) substrate, preceding any physical contact. Raman analysis indicated that both Trichoderma species stimulated phenolic compound synthesis by triggering plant-specific responses in seed radicles. The impact of T. harzianum and T. brevicompactum on two tomato cultivars resulted in alterations to the middle lamella pectin, cellulose, and xyloglucan in the primary cell wall. The Raman spectra indicated increased xylan content in NA with T9 treatment as well as increased hemicelluloses in GZ with T4 treatment. Moreover, T4 treatment resulted in elevated conjugated aldehydes in lignin in GZ, whereas the trend was reversed in NA. Additionally, FTIR analysis revealed significant changes in total protein levels in Trichoderma spp.-treated tomato seed radicles, with simultaneous decreases in pectin and/or xyloglucan. Our results indicate that two complementary spectroscopic methods, FTIR and Raman spectroscopy, can give valuable information on rapid changes in the plant cell wall structure of tomato radicles during germination stimulated by Trichoderma spp.