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We demonstrate a non-monotonic evolution of in-plane thermal conductivity of large-area hexagonal boron nitride films with thickness. Wrinkles and defects/impurities are present in these films. Raman spectroscopy, an optothermal non-contact technique, is employed to probe the temperature and laser power dependence property of the Raman active E2ghigh phonon mode, which, in turn, is used to estimate the rise in the temperature of the films under different laser powers. As the conventional Fourier law of heat diffusion cannot be directly employed analytically to evaluate the thermal conductivity of these films with defects and wrinkles, finite-element modeling is used instead. In the model, average heat resistance is used to incorporate an overall near-surface defect structure, and Voronoi cells with contact resistance at the cell boundaries are constructed to mimic the wrinkled domains. The effective in-plane thermal conductivity is estimated to be 87, 55, and 117 W/m K for the 2, 10, and 30 nm-thick films, respectively. We also present a quantitative estimation of the thermal resistance by defects and wrinkles individually to the heat flow. Our study reveals that the defects/impurities render a much higher resistance to heat transfer in the films than wrinkles. [ABSTRACT FROM AUTHOR]

The binary Xe–Ar system has been studied in a series of high pressure diamond anvil cell experiments up to 60 GPa at 300 K. In-situ x-ray powder diffraction and Raman spectroscopy indicate the formation of a van der Waals compound, XeAr2, at above 3.5 GPa. Powder x-ray diffraction analysis demonstrates that XeAr2 adopts a Laves MgZn2-type structure with space group P63/mmc and cell parameters a = 6.595 Å and c = 10.716 Å at 4 GPa. Density functional theory calculations support the structure determination, with agreement between experimental and calculated Raman spectra. Our DFT calculations suggest that XeAr2 would remain stable without a structural transformation or decomposition into elemental Xe and Ar up to at least 80 GPa. [ABSTRACT FROM AUTHOR]

Vibrational strong coupling results from the interaction between optically allowed molecular vibrational excitations and the resonant mode of an infrared cavity. Strong coupling leads to the formation of hybrid states, known as vibrational polaritons, which are readily observed in transmission measurements and a manifold of the reservoir states. In contrast, Raman spectroscopy of vibrational polaritons is elusive and has recently been the focus of both theoretical and experimental investigations. Because Raman measurements are frequently performed with high-numerical aperture excitation/collection optics, the angular dispersion of the strongly coupled system must be carefully considered. Herein, we experimentally investigated vibrational polaritons involving dispersive collective lattice resonances of infrared antenna arrays. Despite clear indications of the strong coupling to vibrational excitations in the transmission spectrum; we found that Raman spectra do not bear signatures of the polaritonic transitions. Detailed measurements indicate that the disappearance of the Raman signal is not due to the polariton dispersion in our samples. On the other hand, the Tavis–Cummings–Holstein model that we employed to interpret our results suggests that the ratio of the Raman transition strengths between the reservoir and the polariton states scales according to the number of strongly coupled molecules. Because the vibrational transitions are relatively weak, the number of molecules required to achieve strong coupling conditions is about 109 per unit cell of the array of infrared antennas. Therefore, the scaling predicted by the Tavis–Cummings–Holstein model can explain the absence of the polariton signatures in spontaneous Raman scattering experiments. [ABSTRACT FROM AUTHOR]

Short-lived core-ionized neon atoms were investigated by measuring under resonant Raman conditions the Auger decay following the excitation of a second core electron into a Rydberg state. Making use of intense and narrow bandwidth x-ray free-electron laser pulses, the photoexcitation spectrum of the femtosecond-lived Ne + 1 s 0 2 s 2 2 p 6 n p series was characterized. Energy position and lifetimes of the lower-lying Rydberg states were determined and the final state configurations following the decay of the Ne + 1 s 0 2 s 2 2 p 6 3 p double-core hole resonance were partially resolved. [ABSTRACT FROM AUTHOR]

In this experiment, we successfully synthesized NaCaY(WO 4) 3 ceramic by employing a traditional solid-state reaction method. Experimental results demonstrated that NaCaY(WO 4) 3 ceramic sintered at 925 °C exhibited excellent microwave dielectric properties with ε r = 10.74, Q × f = 46510 GHz, and τ f = −32.7 ppm/°C. In addition, the dielectric demonstrated excellent chemical compatibility with Ag electrodes, suggesting its potential application in LTCC devices. To address its poor temperature stability, we optimized the original NaCaY(WO 4) 3 ceramic by doping Li 2 CO 3 , ultimately obtaining the Li x Na (1- x) CaY(WO 4) 3 (x = 0∼0.3) ceramics. XRD analysis confirmed the tetragonal scheelite structure of this ceramic systems. Rietveld refinement and Raman spectroscopy analysis revealed that the inclusion of Li 2 CO 3 had no impact on the phase structure of this ceramic system. Furthermore, the P-V-L theory demonstrated that the W-O bond significantly contributed to the Q × f value of Li 0.3 Na 0.7 CaY(WO 4) 3 ceramics. With a sintering temperature of 900 °C, Li 0.3 Na 0.7 CaY(WO 4) 3 ceramics exhibited the optimal microwave dielectric properties of ε r = 11.29, Q × f = 19363 GHz, and τ f = −2.46 ppm/°C. This highly stable microwave dielectric ceramic holds potential for applications in 5G communications. [ABSTRACT FROM AUTHOR]

The pure nanostructured anatase titanium dioxide (TiO 2) and subsequent nitrogen–doped derivatives (TiO 2–x N x; where, x = 0.005, 0.01, 0.05) were synthesized by sol–gel auto–combustion technique. XRD analysis confirms the formation of pure anatase phase of TiO 2 up to doping of 1 mol% (x = 0.01) of nitrogen having tetragonal structure with space group of I 4 1 / amd whereas an additional monoclinic phase of TiO 2 –B was observed at 5 mol% of nitrogen doping in TiO 2. This sample has smallest crystallite size of ∼4.7 ± 0.2 nm corresponding to TiO 2 –B phase and ∼12.0 ± 0.1 nm corresponding to anatase phase. XRD also reveals that the crystallite size of all other samples having pure anatase phase ranges between ∼8.7 ± 0.1 nm & 13.9 ± 0.1 nm. The crystalline phase revealed from XRD of all samples was further supported by the Raman analysis. The direct optical band gap of pure TiO 2 (∼3.4 eV) was reduced non–monotonically after nitrogen doping in the ranges from ∼2.8 eV (TiO 1.95 N 0.05) to ∼2.0 eV (TiO 1.99 N 0.01). FTIR spectra confirm the metal oxide bond formation, surface adsorption of water molecules and presence of residual hydroxyl group in all crystalline samples. HRTEM analysis validates the coexistence of secondary phase of TiO 2 –B along with anatase phase of TiO 2 in studied highest doped sample (TiO 1.95 N 0.05) including its broader particle size distribution as compared to pure TiO 2. The electrical studies reveal that the highest values of dielectric constant and ac conductivity can be realized for pure TiO 2 and at 1 mol% (x = 0.01) of nitrogen doping, among all the studied nitrogen doped samples. • Influence of nitrogen doping on the physical properties of anatase TiO 2. • Highest nitrogen doping level in N:TiO 2 possesses structurally dual phase nature. • TEM images also validate the presence of dual phases within the N:TiO 2 lattice. • Nonmonotonic control of optical band gap can be realized via doping of N in TiO 2. [ABSTRACT FROM AUTHOR]

Powder nanoparticles of ZnO/Fe 2 O 3 composites with varying concentrations of precessour have been synthesized with the help of the co-precipitation method followed by annealing and milling the composite at 700 °C. Then, the obtained powder composites were characterized by X-ray diffraction, Fourier Transformation Infrared spectroscopy, Field Emission Scanning electron microscopy with EDX, Raman spectroscopy, UV–visible absorption spectroscopy, and Photolumnisences. The powder X-ray diffraction results show the formation of the well-crystalline phase of ZnO/Fe 2 O 3. For the further study of the structural analysis, we have done the Rietveld refinement of the XRD data. Williams-hall plot was used to calculate the lattice strain of the composites. Crystalline size, dislocation density, and Rietveld parameters were also calculated using the XRD and Rietveld refinement methods. FESEM study revealed that with an increase in the concentration of Fe 2 O 3 , the shape of the composite changes from spherical to nanosheets via nanorods. The absorption peaks and vibration band obtained at zftir and RAMAN spectra show the formation of the ZnO/Fe 2 O 3. The UV–visible absorption spectroscopy shows the maximum absorption peak in the 200–400 nm range. The successfully synthesized nanocomposites ZnO/Fe 2 O 3 indicate that it can be a potential candidate for organic pollutant degradation. [ABSTRACT FROM AUTHOR]

Oxalyldihydrazide (ODH) and coffee extracted fuel (CEF) were used to synthesize Ceria (CeO 2) nanoparticles by solution combustion synthesis route. The cubic fluorite structure, crystalline nature, crystallite size and particle size of ceria nanoparticles were confirmed using the powder X-ray diffraction (PXRD) and High-Resolution Transmission Electron Microscope patterns respectively. Field Emission Scanning Electron Microscope (FESEM) images were used to understand the Surface morphology of the synthesized samples. Based on XRD results the volume of coffee husk extract for the optimum phase formation is found to be 40 mL. The fluorite structure of the samples and the presence of oxygen vacancies in the samples were confirmed from the Raman spectral analysis. ESR (Electron Spin Resonance) studies confirmed formation of relatively more intrinsic defects in CEF-ceria nanoparticles compared to ODH-ceria nanoparticles. The semiconducting nature of the synthesized samples was confirmed by analysing UV–visible absorbance spectra. The functional group confirmation was obtained by analysing Fourier Transform Infrared (FTIR) spectra of both the samples. AC conductivity and dielectric relaxation studies of the samples in pellet form were carried out over a wide frequency (20Hz–10 MHz) and temperature (200–640 °C) range using a precision impedance analyser. A higher value of dielectric constant was observed for CEF-ceria nanoparticles. [ABSTRACT FROM AUTHOR]

Magnetic nanocomposite was prepared using the wet chemical precipitation approach with varying amounts of cobaltous oxide (CoO). The concentrations of CoO were 0.5, 3.5, 6.5, and 9.5 g per 100 % wollastonite composition. Samples were sintered separately at 1000 and 1200 °C. X-ray diffraction analysis (XRD) of the sintered parent sample revealed the formation of wollastonite CaSiO 3 and larnite Ca 2 SiO 4 , as well as a minor silicon oxide SiO 2 phase. In CoO-doped samples, Co-åkermanite Ca 2 CoSi 2 O 7 and other phases were formed. The XRD and scanning electron microscope SEM confirm the samples' submicron and nanocrystalline microstructure. The Fourier transform infrared spectroscopy (FTIR) and Raman spectra (RS) of investigated samples sintered at 1000 and 1200 °C revealed their bond structure. Both analyses confirmed that incorporating CoO into CaSiO 3 significantly improved its vibrational modes, reflecting structural modifications. By increasing the cobalt oxide content from 3.5 to 9.5 wt%, the samples attain the ideal paramagnetic state, as demonstrated by the magnetic hysteresis (M − H) curve, which is linearly reversible. Formation of the Ca 2 CoSi 2 O 7 significantly alters the magnetic characteristics of the samples, whether through increasing the cobalt oxide concentration up to 9.5 wt% or modifying the sintering temperature. This enables the prepared nonocomposites to be suitable for novel magnetic applications. [ABSTRACT FROM AUTHOR]

The slag-metal reaction between traditional CaO-SiO 2 -CaF 2 -Na 2 O-based slag and high-titanium steel deteriorates the performance of the mold flux, negatively affecting the surface quality of the slab and causing issues in continuous casting. To maintain the stability of slag properties after the slag-metal interaction, BaO and Li 2 O were added to the mold flux as a potential new slag system of the BaO-CaO-SiO 2 -TiO 2 -CaF 2 -Li 2 O-Na 2 O seven-component slag for the continuous casting of high titanium steel. In this study, the effects of the BaO/CaO ratio on the structure and properties of the seven-component slag were examined using molecular dynamics simulation and Raman spectroscopy, and the effect of the BaO content on the amphoteric behavior of TiO 2 was also investigated. With the gradual substitution of CaO by BaO, the melt's basicity increases, and TiO 2 transforms from acidic TiⅤ to alkaline TiⅥ. Simultaneously, the addition of BaO promotes the conversion of O b into O f and O nb , resulting in a simplified melt structure. The continuous increase in content of structural units Q Si 0 and Q Si 1 , along with the continuous decrease in content of Q Si 3 and Q Si 4 , further elucidates this phenomenon. Hence, it can be inferred that BaO primarily functions as a depolymerizing agent within the network structure of the melt. [ABSTRACT FROM AUTHOR]

This study is the first attempt to examine the electrochemical properties of TiO 2 composite with Fe 3 O 4 thin film. In our analysis, X-Ray diffraction (XRD) confirms the formation of Fe 3 O 4 on TiO 2. Fourier Transform Infrared Spectroscopy (FT-IR) and Raman spectroscopy confirmed the functional groups. The UV–Vis spectroscopy analysis shows that the addition of Fe 3 O 4 results in decrease in optical band gap. Our Cyclic Voltammetry (CV) results demonstrate that, under steady state conditions, the behaviors of TiO 2 and Fe 3 O 4 /TiO 2 electrodes regarding ion adsorption and charge transmission vary. Pseudocapacitive effects and charge transfer affects the functionality of the TiO 2 electrode, whereas two-layer capacitance effects primarily control the response of the Fe 3 O 4 /TiO 2 electrode. Numerous factors, including ion diffusion, rate capability, charge transfer, and series resistance, can be directly determined using electrochemical impedance spectroscopy (EIS). The experimental results and analysis presented in this work brings to light the significance of Fe 3 O 4 in the electrochemical response of an electrode-electrolyte interface. [ABSTRACT FROM AUTHOR]

After the invention of indoor tabletop shock tubes, studies on the impact of low-pressure acoustic shock waves on materials have been sufficiently conducted and found several spectacular phase transitions. However, the acoustic shock wave impact studies on minerals remain unexplored. The floodgates are to be opened by streamlining a systematic approach in bringing out a new era of spectacular findings as more and more minerals are involved in the investigation. Hence, in the present investigation, we have chosen one of the most prominent upper mantle earth minerals of α-Olivine (forsterite-Mg 2 SiO 4) single crystal for the ex-situ shock wave recovery experiment with 2.0 MPa transient pressure. Raman spectroscopic technique has been utilized to examine the crystallographic stability of the title mineral. The observed shock-wave impact results demonstrate that the forsterite remains to be in the crystallized state maintaining the same space group of P bnm, however, significant changes have been witnessed in the normalized intensity ratio of the characteristic doublet Raman peaks of the forsterite (asymmetry stretching SiO 4 (824 cm−1)/symmetry stretching SiO 4 (855 cm−1) such that the values are found to be 2.17, 2.27, 1.38, 0.51, and 2.43 against the number of shock pulses of 0, 1, 2, 3 and 4, respectively. It is to be noted that, we have found more pronounced changes in the doublet Raman peak intensity compared to the flat plate accelerator shock compression experiment on forsterite (Tielke et al., J. Geophys. Res. Planets (2022)) and the observed values are 0.8, 0.3, 0.6, 0.8 and 0.52 for 0, 21.3, 22.4, 38.9 and 41.8 GPa, respectively without undergoing any structural transitions towards the high-pressure phases. Based on the assessment of comparative results, tabletop shock-tubes can be strongly considered for mineralogical research to expand the current knowledge on the behaviors of the earth and space minerals under extreme-conditions. [ABSTRACT FROM AUTHOR]

Novel spinel-type Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics were prepared by the solid-state method. Rietveld refinement revealed that the Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics possess a cubic spinel structure with the F d 3 ‾ m (227) space group. Raman spectrum analysis indicated that the Q × f and FWHM of ceramics exhibit an inverse relationship. According to the P-V-L theory, the Ti-O bond has the highest percentage of contribution to both of bond ionicity and lattice energy, indicating a significant impact on ε r and Q × f , respectively. The Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics showed the best microwave dielectric properties (ε r = 15.72, Q × f = 69,633 GHz, and τ f = −20 ppm/°C), sintering at an optimum temperature of 1200 °C. Additionally, a dielectric resonance antenna, on the basis of Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics was designed and simulated. [ABSTRACT FROM AUTHOR]

Double perovskites have shown promise in the development of spin polarized conduction and ferromag semiconductors. In this category of double perovskite, we report on the lanthanum ferrocobaltite, co-doped with Pr and Mn. The polycrystalline ceramics were analysed for its structural properties by using Rietveld refinement of X-ray diffraction (XRD) and Raman spectroscopy measurements. The pristine and co-doped samples possess monoclinic structure with P2 1 /n space group. In the pristine compound Co and Fe octahedra are ordered periodically which later gets distorted upon cationic substitution. Scanning electron microscopy (SEM) and energy dispersive spectra (EDS) reveals the grain morphology and elemental analysis. The samples were investigated for their dc and ac electrical responses. The two-probe dc resistance was measured from room temperature RT to 575 K. Dielectric spectroscopy in the RT to 650 K temperature range was performed in the frequency range of 50 kHz to 5 MHz. We observed that introducing Pr at La-site and Mn at Fe site creates structural disorder and tilt in octahedra which results in decreasing the dielectric constant at RT but increases significantly at higher temperature with low dielectric loss. ac conductivity was found to increase with increasing temperature indicating the thermally governed hopping mechanism. All these features validate their potential applications as a high temperature capacitor and can be widely used in automotive and aerospace domains for the storage device application. [ABSTRACT FROM AUTHOR]

The zinc doped calcium phosphate biomaterials have recently attracted much attention. In this study, we have investigated the bioactivity, cytotoxicity and antibacterial activity of zinc doped calcium phosphate-sulfate hydroxyapatites Ca 9-x Zn x Na(PO 4) 5 (SO 4)(OH) 2 (x = 0, 0.2, 0.5). The samples have been synthesized by the solid-state reaction at high temperature and then have been characterized using X-ray diffraction, Infrared spectroscopy and Raman scattering spectroscopy. The surface analysis was conducted by scanning electron microscopy (SEM) in combination with energy-dispersive spectroscopy (EDX) and Zeta-potential measurements. The bioactivity investigation involved immersing the samples in a simulated body fluid (SBF), providing valuable insights into the samples capability to stimulate the formation of an apatite layer similar to that found in bones. The antibacterial activity of the materials was studied using pathogenic bacteria. The assessment of sample cytotoxicity was involved using artemia salina as the experimental model. X-ray diffraction patterns reveal that the samples crystallize in the hexagonal system with the P 6 3 / m space group. The x = 0.2 material exhibited the best crystallinity and the highest negative Zeta potential, making it the most bioactive sample when immersed in simulated body fluid (SBF). SEM analysis confirmed that this sample effectively promotes the formation of a new apatite layer, highlighting its promising potential for biomedical applications. The results of the study highlight the significantly beneficial effect of doped hydroxyapatite (x = 0.2) on the biological properties, compared to the other samples analyzed in this study, thus underscoring the strong potential of this material for promising applications in the fields of bioengineering and tissue regeneration. [ABSTRACT FROM AUTHOR]

This study investigates the thermal behavior and structural transitions of silver vanadate microrods (AgVO 3) synthesized via coprecipitation. The samples were characterized at room temperature using scanning electron microscopy, Powder X-ray Diffraction, and Raman scattering. The AgVO 3 was obtained in the monoclinic phase (β-phase) with a Cm space group and rod-like morphology of micrometer-sized diameter. In situ temperature-dependent studies utilizing XRD and Raman spectroscopy revealed notable findings: at low temperatures (298–12 K), the β-AgVO 3 phase exhibited thermal stability alongside uniaxial negative thermal expansion (NTE) along the b lattice parameter of microcrystals. Conversely, experiments at high temperatures (298–673 K) demonstrated a reversible structural transition from the monoclinic phase to a triclinic phase at 473 K (β → β'), with NTE observed along the b direction in both high-temperature phases. These temperature-induced structural modifications and the observed uniaxial negative thermal expansion in β-AgVO 3 microrods constitute significant contributions to the field, providing valuable insights into their thermal behavior and potential applications. • Temperature-dependent behavior of silver vanadate (β-AgVO 3) microrods using in situ XRD and Raman scattering. • β-AgVO 3 microrods present reversible monoclinic to triclinic phase transitions at high temperatures. • The β-AgVO 3 microrods exhibit uniaxial negative thermal expansion along the b-axis at low and high temperatures. [ABSTRACT FROM AUTHOR]

Microwave absorption materials have attracted attention due to their extensive applications in different fields. Herein, ytterbium-doped BaCo 2 W-type hexaferrite nanocrystallites with a nominal composition of BaCo 2 Yb x Fe 16−x O 27 (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were synthesized via the sol–gel method, and their physicochemical and dielectric characteristics were estimated. XRD plots revealed the pure phase structure of each prepared hexaferrite sample. The lattice constant and unit cell volume were affected by changes in the Yb concentration. The crystallite size was measured by the Debye–Scherrer formula, revealing intense crystals typically in the 18–33 nm range. FTIR spectroscopy showed multiple absorption bands from 430 to 3000 cm−1, and Raman spectroscopy revealed multiple peaks between 200 and 1000 cm−1, displaying the allocated polyhedra and symmetry. XPS spectroscopy confirmed the existence of all metal ions in the required valence state. The dielectric measurements were evaluated at frequencies from 1 to 6 GHz for all the synthesized compositions, and the material behavior was explained using the Maxwell–Wagner and Koop theories. The conduction mechanism in the hexagonal ferrites was assessed using Cole–Cole analysis. Reflection loss measurements were also conducted: the samples at x = 0.03 and x = 0.12 yielded minimal reflection losses of −60.06 and −51.69 dB at 5.5 GHz, respectively. The results demonstrate the suitability of the samples for use in microwave and high-frequency absorption applications. [ABSTRACT FROM AUTHOR]

This study evaluated the application of carboxylated multi-walled carbon nanotubes (MWCNTs) as a label in immunochromatographic assay for morphine detection. MWCNTs were carboxylated using nitric acid and characterized by Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, field emission scanning microscopy (FESEM), and dynamic light scattering (DLS). The optimum concentration of polyvinyl pyrrolidone (PVP) as a surfactant for homogenous dispersion of MWCNTs was determined by ultraviolet-visible spectroscopy to be 0.5 mg/mL. The zeta potential of MWCNTs before adding PVP was −41.9 ± 1.02 mV, and after adding PVP, −54.1 ± 0.25 mV. On the surface of MWCNTs, the anti-morphine antibody (AM antibody) had a binding effectiveness ranging from 91.1% to 95.5%. The AM antibody-MWCNTs were conjugated to create immunochromatographic test strips. The visual limit of detection (vLOD) was 1.0 ng/mL and the cutoff concentration (COC) was 10.0 ng/mL. Compared to previous study, carboxylated-MWCNTs as a one-dimensional nanomaterial improved the sensitivity of immunochromatographic assay strips and may be utilized to develop the sensitive immunochromatographic assays. [ABSTRACT FROM AUTHOR]

[Display omitted] The CO preferential oxidation reaction (CO-PROX) is an effective strategy to remove residual poisonous CO in proton exchange membrane fuel cells, in which oxygen vacancies play a critical role in CO adsorption and activation. Herein, a series of CuO/CeO 2 catalysts derived from Ce-MOFs precursors were synthesized using different organic ligands via the hydrothermal method and the CO-PROX performance was investigated. The CuO/CeO 2 -135 catalyst derived from homophthalic tricarboxylic acid (1,3,5-H 3 BTC) exhibited superior catalytic performance with 100 % CO conversion at a relatively low temperature (T 100% = 100 °C), with a wide reaction temperature range and excellent stability. The superior catalytic properties were attributed to the structural improvements provided by the 1,3,5-H 3 BTC precursors and the promotional effects of oxygen vacancies. Additionally, in-situ Raman spectroscopy was performed to verify the dynamic roles of oxygen vacancies for CO adsorption and activation, while in-situ DRIFTS analysis revealed key intermediates in the CO-PROX reaction, shedding light on the mechanistic aspects of the catalytic process. This work not only demonstrates insights into the effective CuO/CeO 2 catalysts for CO preferential oxidation, but also provides a feasible way to synthesize MOF-derived catalysts. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of Mn doping on the performance of polyvinyl alcohol/borax‐structured (PMB) supercapacitor electrodes for high‐capacity, flexible, and self‐healing supercapacitor electrodes. The PMB electrodes were characterized by x‐ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Electrochemical characterization was conducted using cyclic voltammetry (CV), which revealed that redox reactions, which are evident at low scan rates, enhance capacitive performance. However, high scan rates introduce limitations owing to the increased vibrations of the PVA chains and incomplete electrolyte polarization. The PMB electrodes exhibited remarkable electrochemical properties and capacitive performances, which were significantly affected by the MnO₂ structure. The electrodes exhibited self‐healing properties and demonstrated flexibility to stretch by up to 40%. In addition, the results indicate that the electrode capacity of the PVA/borax system increased by 2.03 times after 1000 cycles with manganese doping. The solid electrolyte interface (SEI) layer formed on the electrode surface plays a critical role in stabilizing the capacity loss during prolonged charge–discharge cycles. The study concluded that PMB supercapacitors offer higher capacitance in 0‐2 V applications compared to other PVA/borax combination hydrogels. Moreover, the incorporation of metal‐based additives, particularly manganese, enhanced the capacitive performance, and operating voltage levels. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Radix Bupleuri has been widely used for its plentiful pharmacological effects. But it is hard to evaluate their safety and efficacy because the concentrations of components are tightly affected by the surrounding environment. Thus, Radix Bupleuri samples from different regions and varieties were collected. Based on the experimental and computational Raman spectrum, machine learning is emphasized for certain obscured characteristics; for example, linear discriminant analysis (LDA), support vector machine (SVM), eXtreme gradient boosting (XGBoost) and light gradient boosting machine (LightGBM).After dimension reduction by LDA, models of SVM, XGBoost and LightGBM were trained for classification and regression prediction of Bupleurum production regions. Support vector classifiers achieved the best accuracy of 98% and an F1 score above 0.96 on the test set. Support vector regression has a good fitting performance with an R2 score above 0.90 and a relatively low mean square error. However, complex models were prone to overfitting, resulting in poor generalization ability.Among these machine learning models, the typical LDA‐SVM models, consistent with the high‐performance liquid chromatography results, demonstrate great performance and stability. We envision that this rapid classification and regression technique can be extended to predictions for other herbs. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This article presents the first experiments on filling single‐walled carbon nanotubes (SWCNTs) with the phosphorus sulfides P4S3 and P4S10 using the ampoule method. Transmission electron microscopy examination reveals the encapsulation of phosphorus and sulfur species inside the cavities of SWCNTs without the formation of any regular structures. X‐ray photoelectron spectroscopy observes different oxidation states of P and S atoms, depending on the P/S ratio in the initial mixture used to fill the nanotubes. The Raman signals associated with the encapsulated species are low in intensity, and the vibrational modes are shifted and broadened as compared to those in crystalline P4S3 and P4S10. The proposed models for the arrangement of sulfur and phosphorus inside SWCNTs suggest the formation of 1D amorphous glassy phosphorus sulfides with stoichiometric ratios close to those of elemental phosphorus and sulfur in the initial mixtures. [ABSTRACT FROM AUTHOR]

Solid or quasi-solid electrolytes are acclaimed for their ability to overcome limitations associated with liquid electrolytes, while still retaining crucial characteristics of the latter. Particularly within the realm of energy storage, these electrolytes have garnered substantial interest over the past decade. This study presents an investigation into two hybrid eutectogels obtained from the encapsulation of an ionic-liquid-(IL-) based binary deep eutectic solvent (DES) within a solid matrix of titania (TiO2) or silica (SiO2) through a non-aqueous sol–gel route. The DES is prepared by mixing the IL 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][MeSO3]) and N-methylacetamide (NMAc) in a carefully optimized molar ratio of 1 : 2. The properties of the eutectogels are thoroughly examined employing analytical techniques including field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, field emission transmission electron microscopy (FETEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Remarkably, the structural integrity of the DES remains unaltered following its incorporation into the matrices. The eutectogels exhibit a double-layer capacitive behavior within a wide operating potential window (OPW) of 3 V. Specific capacitance and ionic conductivity as high as 16.32 F g−1 and 1.27 mS cm−1 are obtained at room temperature with specific energy and specific power of 20.39 W h kg−1 and 3.31 kW kg−1 respectively, thus underscoring their potential utility in applications concerning electrochemical supercapacitors. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal chalcogenides (TMDs) have demonstrated immense potential and broad prospects in advancing the fields of next-generation optoelectronics, spintronics, valley electronics, and traditional electronics. In recent years, significant progress has been made in the growth research of TMDs through continuous optimization and innovation of various synthetic strategies. However, precisely controlling the growth conditions of materials, synthesizing high-quality 2D materials with a single domain structure, and achieving the desired shape and performance standards remain complex scientific challenges. Here, we report on the study of MoS2 nucleation and growth habits by precisely controlling the ratio of molybdenum and sulfur sources during the growth process. Using pre-deposited highly oriented MoO2 nanorods as templates, two preferentially oriented (0° or 60°) MoS2 crystal domains were obtained on c-plane sapphire. Characterization using Raman spectroscopy, PL, XPS, and HRTEM reveals that the monolayer MoS2 continuous film, grown using this templating method, possesses superior quality. Our work demonstrates a method for directional growth of 2D MoS2 thin films using highly oriented 1D MoO2 nanorods as templates and precursors, providing new insights into orientation control for epitaxial growth of 2D TMD materials. [ABSTRACT FROM AUTHOR]

Typing of bacterial subspecies is urgently needed for the diagnosis and efficient treatment during disease outbreaks. Physicochemical spectroscopy can provide a rapid analysis but its identification accuracy is still far from satisfactory. Herein, a novel feature-extractor-based fusion-assisted machine learning strategy has been developed for high accuracy and rapid strain differentiation using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and Raman spectroscopy. Based on this fusion approach, rapid and reliable identification and analysis can be performed within 24 hours. Validation on a panel of important pathogens comprising Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Acinetobacter baumannii showed that the identification accuracies of k-nearest neighbors (KNNs), support vector machines (SVMs) and artificial neural networks (ANNs) were 100%. In particular, when benchmarked against a MALDI-TOF MS spectral dataset, the new approach improved the identification accuracy of Acinetobacter baumannii from 87.67% to 100%. This work demonstrates the effectiveness of combining MALDI-TOF MS and Raman spectroscopy fusion data in pathogenic bacterial subtyping. [ABSTRACT FROM AUTHOR]

The widespread distribution of herbicides in the environment poses a significant risk to human health and wildlife. Surface-enhanced Raman scattering (SERS) has emerged as a powerful technique for detecting and analyzing herbicides. However, developing a low-cost, highly sensitive, reproducible, stable, and Raman-active nanostructured substrate for herbicide detection remains a particular challenge. In this research, a nanohybrid substrate consisting of gold nanoparticles@carbon nanodots (AuNPs@CNDs) was synthesized by reducing HAuCl4 in the presence of CNDs at 100 °C. The optical, chemical, and physical properties of CNDs, AuNPs, and the hybrid AuNPs@CND substrates were thoroughly investigated using various techniques including UV-vis spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and CytoViva darkfield and hyperspectral imaging. The SERS effect of the substrates was evaluated using rhodamine 6G (Rh6G), a Raman-active probe, and two groups of herbicides containing mesotrione or S-metolachlor. The results demonstrated a significant signal amplification in the SERS spectra of Rh6G and herbicide molecule detection using the AuNPs@CND substrate compared to bare CNDs and AuNPs alone. This suggests that the nanohybrid AuNPs@CND SERS substrate holds promise for the detection of herbicides and other organic compounds in environmental applications. [ABSTRACT FROM AUTHOR]

Gadolinium-substituted cobalt manganese ferrite nanoparticles with the composition Co 0.6 Mn 0.4 Gd x Fe 2- x O 4 (where x ranges from 0.0 to 0.08, with x = 0.02) were prepared through the sonochemical method. X-ray diffraction reveals that grown samples are single-phase cubic spinel belonging to space group Fd 3 m, where the crystallite sizes decrease with increasing Gd3+ content. At high doping ratios (x > 0.06), there was a slight increase in crystallite size compared to that of pure Co–Mn ferrite (x = 0), while the lattice parameter (a) decreased in the low doping range of Gd (x < 0.06), resulting in a reduction in crystallite size. Bertaut's method confirms that 80 % of the tetrahedral (A) sites were occupied by Mn ions, while the remaining sites were occupied by other cations in the octahedral (B) positions. Gd3+ ions were found exclusively in the octahedral-B sites. Co2+ ions were expected to occupy the octahedral-B site, which was confirmed in this study for the x = 0.0 and 0.02 samples. Field emission scanning electron microscopy shows the samples are agglomerated and have dense structures. Fourier transform infrared and Raman spectra validated the presence of spinel ferrite modes. Dielectric investigations indicate that as the Gd3+ content exceeds x = 0.0, the dielectric constant and dielectric loss decrease at lower frequencies. The observed dielectric behavior exhibited typical dispersion patterns attributed to Maxwell-Wagner polarization. Furthermore, changes in dielectric properties were observed as the Gd3+ content in Co 0.6 Mn 0.4 Gd x Fe 2- x O 4 nanoparticles increased, which can be attributed to the presence of oxygen vacancies and variations in the distribution of Fe3+ ions at both A and B-sites. [ABSTRACT FROM AUTHOR]

In this study, the objective was to improve the performance of bismuth vanadium oxide Bi 4 V 2 O 11 by synthesizing double substituted compounds using copper ions Cu2+ and tantalum ions Ta5+. Bi 4 V 2-x Cu x/2 Ta x/2 O 11-3x/4 (0.1 ≤ x ≤ 0.5) polycrystalline samples of were prepared via the solid-state route. XRD patterns measured at room temperature revealed the stabilization of the monoclinic α-Bi 4 V 2 O 11 type structure for x = 0.1 and the tetragonal γ or γ' -Bi 4 V 2 O 11 for x > 0.2. This result has been confirmed by thermogravimetric analysis (DTA), FT-IR spectroscopy and Raman scattering measurements. The influence of the composition on the microstructure and grain size of the prepared samples was explored through dilatometric study, density measurements, and scanning electron microscopy (SEM). Thermal Raman spectra evolution was also investigated. The temperature-dependent Raman spectroscopy analysis of the compound α-BiCuTaVOx (x = 0.1) demonstrated variations in the position, intensity, and width of the Raman mode around 850 cm−1, indicating temperature-assisted structural modifications. One defining feature of the tetragonal-dominated phase of the BiMeVOx systems is the increasing merging of the weak band at 930 cm−1 with the dominating band at 850 cm−1. This behavior was also observed for our samples. The V–O bond lengths were calculated using an empirical relation based on the diatomic approximation. Electrochemical impedance spectroscopy (EIS) was used to investigate the changes in electrical conductivity with the substitution rate across the temperature range of 300–720 °C. The sample with x = 0.3 exhibited the highest electrical conductivity at both high and low temperatures. However, the optimal substitution rate to achieve the best conductivity in this series of copper and tantalum-substituted BiCuTaVOx was found to be x = 0.3 (σ = 4 × 10−3 S cm−1 at 600 °C). [ABSTRACT FROM AUTHOR]

The attempt to search for novel materials for optoelectronics material has become a highly debated and intensively investigated field of study. Within the scope of this investigation, Sn 0.94 Ag 0.06-x Mg x O 2 (0 ≤ x ≤ 0.06) polycrystalline samples were produced using the traditional solid – state reaction method, and their crystalline structure, micro – structure, Raman spectroscopy, optical, and transport characteristics were investigated. Confirmation of a single rutile phase with a tetragonal crystal structure through XRD (X – ray diffraction) analysis is revealed. The morphology study by scanning electron microscopy indicated the formation of nanometric grains. All elements are evenly distributed throughout the structure, as seen by the elemental color mapping. The successful incorporation of Mg/Ag to the SnO 2 lattice is evidenced by two prominent peaks in the Raman spectra of these compounds, with wavenumbers of 634 and 775 cm−1, which correspond to the A 1g and B 2g Raman modes, respectively. The UV – Vis spectrophotometer facilitated the acquisition of absorbance and transmittance data, which revealed that the optical band gap exhibited an expansion when the quantity of Mg/Ag co–doping increased in the SnO 2 material. The transmittance value was also shown to increase from 80 % to 90 % with increased Mg co–doping concentration. The Maxwell – Weigner model has been employed to fully understand how the dielectric constant (ε r), loss tangent (tan δ), complex impedance, and ac conductivity of Mg/Ag co–doped SnO 2 compounds behave depending on frequency. The current – voltage (I – V) characteristics of the sample were measured using a Keithley 6517b electrometer in two – probe mode with a Tin metal pressure contact. The properties of I – V exhibited an Ohmic behavior. A study on the room temperature resistivity reveled that the materials are highly resistive in the nature. [ABSTRACT FROM AUTHOR]

Carbon fibers (CFs) are experiencing a growing demand owing to their low specific weight, exceptional mechanical properties, superior temperature, and corrosion resistance, however, their sustainability and energy consumption during manufacturing is still a challenge. Therefore, reclamation of waste CFs and their reformatting has gained significant attention. Herein, we synthesized a chemically degradable vitrimer matrix by curing bisphenol‐A diglycidyl ether (BADGE) with 2‐aminophenyl disulfide (2‐AFD) and further utilized the matrix for the development of CF reinforced composites (CFRCs) through vacuum‐assisted resin infusion molding (VARIM) process. The obtained vitrimeric system and its composites show excellent mechanical, self‐adhering, shape‐memory, and reprocessing properties. Meanwhile, the developed CFRP vitrimer composites can be rapidly dissolved in thiol solvent (1‐octanethiol), resulting in the efficient recycling of CFs. X‐ray diffraction, scanning electron microscopy, and Raman spectroscopy validate that the chemical structure of the recycled fibers closely resembles the structure of the original CFs. The recycled CFs were further used to prepare second generation composite materials with excellent thermal, dynamic, and mechanical properties for nonstructural applications (e.g., sports, automotive, etc.). Thus, with an effective CF recycling method, this study can assist in preparing reliable, long‐term functional, recyclable, and high‐performance composites. [ABSTRACT FROM AUTHOR]

Phospholipid bilayers, which are a major component of cellular membranes and some drug delivery vehicles, can be in different states of order depending on the conformations of the hydrocarbon tails and their mutual arrangement. The important task of experimental characterization of phospholipid order is often addressed using Raman spectra of the C–H stretching bands. Such characterization uses some empirical relationships for apparent maxima in the spectra, although the origin of the sensitivity of the C–H band to phospholipid order and its model description remain unclear. Surely, a correct description of the sensitivity of the C–H band to phospholipid order is critical for its proper application. Here, we provide a description of the ordering sensitivity of the C–H stretching band using a polarized Raman experiment with hydrated aligned multibilayers of a saturated phospholipid. By this way, Raman contributions from symmetric and antisymmetric vibrations of CH2 were obtained in a model‐free manner. Experiments in a wide temperature range and the use of isotopic isolation helped us to consider separately the effects of conformational and lateral order of chains. The conformational sensitivity of the spectrum of antisymmetric vibrations was confirmed by DFT modeling. The outcomes of the study allowed us to provide recommendations for the use of the Raman spectrum of the C–H stretching band to characterize the conformational and lateral order of phospholipid‐containing materials. [ABSTRACT FROM AUTHOR]

The application of Raman spectroscopy in the meat processing industry as a quality assurance is dependent on its ability to differentiate tissues from the animal. Meat is commercialised as different cuts with variations in quality and financial value. Whilst it is possible to conduct some analysis on meat quality, there are high costs and time involved. The meat processing industry could benefit from rapid methods for characterising meat quality for large quantities. This study demonstrates the ability of combining Raman spectroscopy with chemometrics to discriminate tissues in a chicken carcass. All spectra from the different tissues were analysed by applying chemometrics. The principal component analysis (PCA) and discriminant function analysis (DFA) showed successful classification of different muscles and tissues. [ABSTRACT FROM AUTHOR]

The quality and the security of preparations in hospital centres are essential to guarantee the patient's safety. The development of fast and efficient analytical methods is required to control the finished product before use. In this context, the study aimed to compare the performance and interchangeability of two spectral analytical methods: the flow injection analysis (FIA) with UV detection and the Raman spectroscopy for the quality control of preparation before use to quantify the remdesivir as a SARS‐CoV‐2 drug. A quantitative study of remdesivir was performed using clinically relevant concentration solutions ranging from 0.25 to 1.625 mg.mL−1 in 0.9% NaCl. Samples were analysed by FIA‐UV at 245 nm and by a handheld Raman spectroscopy at 785 nm. Quantitative models were developed using a calibration set (n = 45 samples) and optimized using a validation set (n = 27). An external validation test set (n = 58) was used to compare the two methods by a Bland–Altman plot. Partial least square regression was used to analyse Raman spectra, while univariate analysis was performed at 245 nm for FIA‐UV. The regression coefficient was higher than 0.990 for both methods, and the root mean square error of prediction was 0.031 mg.mL−1 for Raman spectroscopy. The Bland–Altman plot confirmed the interchangeability of the two methods and the potential of Raman spectroscopy to control remdesivir during clinical preparation in the hospital. [ABSTRACT FROM AUTHOR]

A robust environmental monitoring system is highly essential for the instant detection of environmental microfiber pollutants for the sustainable management of the environment and human health. The extent of microfiber pollution is growing exponentially across the globe in both terrestrial and marine environments. An immediate and accurate environmental monitoring system is crucial to investigate the composition and distribution of these micropollutants. Fourier Transform Infrared Spectroscopy and Raman Spectroscopy are vibrational spectroscopic techniques that have the novel ability to detect microfibers within a minute concentration from diverse environmental samples. The major micropollutants which have been analyzed are polyethylene, polypropylene, nylon 6, polystyrene, and polyethylene terephthalate. After a detailed and critical study of the various aspects of spectroscopic analysis, the review is concluded with a comprehensive discussion of the significance of these robust methods and their application in future aspects for further preventing microfiber pollution in the marine environment. This study highlights the utilities and significance of vibrational spectroscopic detection techniques for the immediate and accurate identification of synthetic microfibers. This review also evaluated the implementation of spectroscopic methods as a precise tool for the characterization and monitoring of microfiber pollutants in the environment. [ABSTRACT FROM AUTHOR]

Tourmaline is a widespread borosilicate mineral that is well known for its variable chemistry. Although a major amount of octahedral Al in tourmaline is commonplace, the occurrence of significant amounts of tetrahedral Al is relatively rare. This paper focuses on tourmaline from the collection of the A.E. Fersman Mineralogical Museum (Russia) originated from Italy with up to 25% of Si replaced by Al at the tetrahedral site. The tourmaline is characterized by optical and scanning electron microscopy, Raman spectroscopy, infrared spectroscopy, Mössbauer spectroscopy, energy-dispersive and wavelength-dispersive X-ray analysis, laser ablation inductively coupled plasma optical emission spectrometry and single-crystal X-ray diffraction. The studied tourmaline occurs as transparent dark blue crystals (with equant external morphology) up to 3 mm in size and forms veinlets cutting a (Mg,Al)-rich metamorphosed mafic-ultramafic rock (Mg >> Fe) composed of spinel, pargasite, clinochlore, phlogopite, and hydroxylapatite. The studied tourmaline meets the criteria defining magnesio-lucchesiite and can be compositionally formed via Tschermak-like ([6]Me2+ + [4]Si4+ ↔ [6]Al3+ + [4]Al3+, where [6]Me2+ = Mg,Fe) or plagioclase-like ([9]Ca2+ + [4]Al3+ ↔ [9]Na+ + [4]Si4+) substitutions. Zones with a relatively high Si content (Si-rich) have pronounced indications of dissolution, while silicon-depleted zones (Si-poor) overgrow Si-rich zones, eventually creating a visible replacement zone of the crystal. We suggest that Si-poor tourmaline results from the Si-rich tourmaline losing Si during a metasomatic process. The resulting empirical crystal-chemical formula for the Si-poor zone is: X     C a   0.95     N a   0.03     ◻ 0.02         Σ 1.00     Y     M g   1.08     A l   0.98     F e   0.50   2 +     F e   0.43   3 +         Σ 3.00     Z     A l   5.91     F e   0.09   3 +         Σ 6.00     T     S i   4.57     A l   1.43         Σ 6.00     O   18           (BO3)3V(OH)3W[O0.95(OH)0.05]Σ1.00 [a = 15.9811(2), c = 7.12520(10) Å, R1 = 1.7%] and for the Si-rich zone is: X     C a   0.89     N a   0.11         Σ 1.00     Y     M g   1.55     A l   0.80     F e   0.34   2 +     F e   0.31   3 +         Σ 3.00     Z     A l   5.51     M g   0.44     F e   0.05   3 +         Σ 6.00     T     S i   5.35     A l   0.65         Σ 6.00     O   18           (BO3)3V(OH)3W[O0.93(OH)0.07]Σ1.00 [a = 15.9621(3), c = 7.14110(10) Å, R1 = 1.7%]. According to pressure-temperature (P-T) calculations of mineral assemblage stability and comparable data on synthetic [4]Al-rich tourmalines, the studied tourmaline was formed at 600–750 °C and 0.10–0.20 GPa. The formation of tetrahedral Al-rich tourmalines requires several unusual factors: (1) desilication of primary rocks and (2) high temperatures and relatively low pressures. [ABSTRACT FROM AUTHOR]

In situ X-ray diffraction and Raman spectroscopy of a synthetic whitlockite, Ca9Mg(PO3OH) (PO4)6, have been conducted at high pressures or high temperatures. The results show that whitlockite is stable up to ~15 GPa at ambient temperature and undergoes a thermally induced dehydrogenation to merrillite above 973 K at ambient pressure. The obtained pressure-volume data were fitted using a third-order Birch-Murnaghan equation of state, yielding an isothermal bulk modulus of K0 = 79(4) GPa with a pressure derivative of K 0 ′ = 4.3(6). When K 0 ′ was fixed at 4, the refined isothermal bulk modulus was 81(1) GPa. The volumetric thermal expansion coefficient (αV) is 4.05(8) × 10-5 K−1, and the axial thermal expansion coefficients (αa and αc) are 1.07(5) × 10−5 K−1 and 1.91(6) × 10−5 K−1. Both compressibility and thermal expansion show an axial anisotropy. The effects of pressure and temperature on the Raman spectra of whitlockite have been quantitatively analyzed. The isothermal and isobaric mode Grüneisen parameters and the intrinsic anharmonic mode parameters of whitlockite were derived. Some amounts of OH−-bearing whitlockite may be preserved in meteorites if whitlockite undergoes a low-temperature process. [ABSTRACT FROM AUTHOR]

AbstractVibrational spectroscopy is a nondestructive analysis technique that depends on the periodic variations in dipole moments and polarizabilities resulting from the molecular vibrations of molecules/atoms. These methods have important advantages over conventional analytical techniques, including (a) their simplicity in terms of implementation and operation, (b) their adaptability to on-line and on-farm applications, (c) making measurement in a few minutes, and (d) the absence of dangerous solvents throughout sample preparation or measurement. Food safety is a concept that requires the assurance that food is free from any physical, chemical, or biological hazards at all stages, from farm to fork. Continuous monitoring should be provided in order to guarantee the safety of the food. Regarding their advantages, vibrational spectroscopic methods, such as Fourier-transform infrared (FTIR), near-infrared (NIR), and Raman spectroscopy, are considered reliable and rapid techniques to track food safety- and food authenticity-related issues throughout the food chain. Furthermore, coupling spectral data with chemometric approaches also enables the discrimination of samples with different kinds of food safety-related hazards. This review deals with the recent application of vibrational spectroscopic techniques to monitor various hazards related to various foods, including crops, fruits, vegetables, milk, dairy products, meat, seafood, and poultry, throughout harvesting, transportation, processing, distribution, and storage. [ABSTRACT FROM AUTHOR]

Escalations in wildfire activity are of significant global concern, particularly within vulnerable wetland ecosystems integral to natural carbon sequestration and climate change mitigation. Our understanding and management of future wildfire activity may be better contextualised through the study of historic and ancient fire records, independent of human influence. Methods of study include 'geothermometry' - approximating ancient fire intensity from temperature-dependent changes in the chemistry of fossil charcoal. Though well established in their relation to experimental charcoalification, these methods still fail to quantify the true intensity of ancient fires, as a measure of energy release. As a result, their applicability, and contributions to the characterisation of modern fire activity, remain uncertain. Here, we present a novel measure of wildfire energy release, as a proxy for true intensity, through the co-application of cone calorimetry and Raman spectroscopy of charcoal. By applying a range of wildfire heat fluxes to variable peatland fuel mixes, this research demonstrates the complexity in correlating fire behaviour and charcoal microstructure. Further statistical analyses suggest a correlation between spectroscopic results, measures of CO and CO2 release, and fire severity. This offers a principal measure of ancient wildfire intensity, consistent with modern practices in wildfire modelling, monitoring, and management. [ABSTRACT FROM AUTHOR]

Due to the extraordinary chemical and physical properties, ternary chalcogenides with wide‐range bandgap, unique structures, and exceptional photoelectric properties have attracted great interest recently. Among them, Chromium thiophosphate (CrPS4) is a promising semiconductor with excellent optical, mechanical, and electronic properties and has a lower lattice symmetry resulting in significant in‐plane anisotropy. Here, the polarization‐dependent nonlinear optical (NLO) responses of CrPS4 flake are investigated. Based on polarization‐resolved Raman spectroscopy, which identifies the crystal axis of sample, the anisotropic linear absorption spectra, I‐scan technique, and pump‐probe measurements are utilized to investigate the optical absorption information of CrPS4. The polarization‐dependent NLO responses are found originating from the anisotropic optical transition probability. And the polar optical phonons play an important role in carrier relaxation processes. Furthermore, CrPS4‐based all‐optical switches are proposed, which can modulate the transmittance of signal light (CW laser) by changing the polarization of switch light (fs laser). This work provides insights into polarization‐dependent CrPS4‐based devices, which is important to promote the potential applications in optical modulator, versatile optoelectronic detection, and so on. [ABSTRACT FROM AUTHOR]

Cr3+ doped Li2Ba3(P2O7)2 pyrophosphate nanopowder was successfully synthesised by solid-state reaction technique. The nanopowder was characterised by several techniques. X-ray diffraction analysis reveals orthorhombic crystal structureand average crystallite size values 34.21 and 28.41 nm are determined by Debye Scherrer's formula and Williamson-Hall (W-H) method. The morphology displayed both SEM and HR-TEM images are irregular stone-like shapes. EDS analysis confirms the constituted elements. The SAED patterns of HR-TEM with well matched with XRD data. FT-IR and Raman spectra analysis confirmed incorporation of Cr3+ in the Li2Ba3(P2O7)2 pyrophosphate nanopowder. The EPR spectrum exhibited signal at g = 1.968 which is attributed to interaction between Cr3+ and Cr3+ exchange pair. The site symmetry of Cr3+ ions occupy a distorted octahedral. Photoluminescence spectrum exhibited bands correspond to ultraviolet, blue and green regions. The evaluated CCT of 6517 K indicates yellowish-green emission near cold light which reveals that the present prepared sample is useful for LEDs applications. [ABSTRACT FROM AUTHOR]

Recently, Raman spectroscopy has made phased progress in clinical research of breast cancer. Raman spectroscopy is a nondestructive optical analysis technology that can quickly provide biochemical molecular specific information of samples. The analysis of Raman spectral characteristics at different stages of clinical activity in breast cancer patients is helpful to formulate individualized diagnosis and treatment plans, improve surgical results, adjust treatment strategies, and promote prognosis. Due to the development of optical technology and the diversity of clinical research needs, derivative Raman techniques based on Raman effect have emerged, such as surface-enhanced Raman spectroscopy, resonance Raman spectroscopy, spatial shifted Raman spectroscopy and coherent Raman scattering spectroscopy. In this paper, the research progress of Raman spectroscopy and its derivative techniques in the diagnosis and treatment of breast cancer in recent years is reviewed. The diagnostic value of different Raman techniques in different levels of breast cancer cells, body fluids and breast tissue and microcalcification molecules is evaluated. In addition, the application status and prospects of Raman spectroscopy and its derivative techniques in breast cancer surgery, chemotherapy and radiotherapy are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Antibacterial agents play a crucial role in healthcare and public health by combating bacterial infections. However, the emergence of antibiotic resistance necessitates a deeper understanding of 6 their mechanisms of action. This review explores the use of spectroscopic techniques, including UV-Vis, FTIR, NMR, Raman spectroscopy, mass spectrometry, and fluorescence spectroscopy, to elucidate the mechanisms of action (MOA) of antibacterial agents in the period from 2003 to 2024. The review discusses how these techniques can elucidate the MOA of classical antibiotics, antiseptics and antimicrobial peptides. Since these spectroscopic techniques provide valuable insights into the molecular interactions between antibacterial agents and bacteria, offering a comprehensive understanding of their mechanisms at a molecular level. By studying electronic transitions, chemical bond vibrations, metabolomics, and protein interactions, researchers can gain in-depth knowledge of antibacterial MOAs. This knowledge can inform the development of improved treatments and strategies to combat bacterial resistance, leading to better patient outcomes and global public health. [ABSTRACT FROM AUTHOR]

Lignin fluorescence in plant cell walls significantly interferes with Raman spectroscopic signals, resulting in compromised analytical accuracy and resolution. To address this issue, a strategy was implemented to both reduce the absolute lignin content in samples and prepare thinner plant tissue sections. This approach involved embedding plant samples in LR White resin, complemented by an ultrathin sectioning technique. Additionally, algorithms were developed to eliminate the impact of resin spectra on the imaging process. These advancements collectively enhanced the performance of Raman spectroscopy by effectively diminishing the disruptive effects of lignin fluorescence. Further analysis with confocal laser scanning microscopy (CLSM) elucidated the presence of aggregation-induced luminescence (AIE) in plant tissues, revealing a direct correlation with lignin concentration. These findings not only offer a new perspective for the application of Raman spectroscopy in plant science, but also pave the way for advancements in tip-enhanced Raman spectroscopy (TERS) detection. [ABSTRACT FROM AUTHOR]

Investigating lattice vibrations through Raman spectroscopy is a crucial method for studying crystalline materials. Carriers can interact with lattices and influence lattice vibrations; thus, it is feasible to study the effect of photo-generated carriers on phonons by analyzing changes in the Raman spectra of semiconductors. Rutile is one of the predominant crystalline phases of TiO2, which is a widely utilized metal oxide semiconductor. In this work, rutile TiO2 is coated on a thinned optical fiber to concentrate ultraviolet light energy within the material, thereby enhancing the generation of carriers and amplifying the changes in the Raman spectra. A Raman detection laser with a wavelength of 532 nm is utilized to collect the Raman spectra of rutile TiO2 during irradiation. Using this setup, the impact of photo-generated carriers on the phonons corresponding to Raman vibrational modes is researched. The localization and non-radiative recombination of photo-generated carriers contribute to a reduction in both the frequencies and lifetimes of phonons. This work provides a novel approach to researching the effect of carriers on phonons. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study achieved label-free visualization of PD-L1 expression at tissue level for the first time. • MLC-Raman histopathology achieved an accuracy of 0.99 in classifying distinct PD-L1 expression cells in GBM IME. • MLC-Raman histopathology could identify glioma, CD8+ T cells, macrophages and normal cells. • The imaging results exhibited strong concordance with MxIF and traditional pathologists' scoring. • The entire process from signal collection to visualization could be completed within 30 min. Combination immunotherapy holds promise for improving survival in responsive glioblastoma (GBM) patients. Programmed death-ligand 1 (PD-L1) expression in immune microenvironment (IME) is the most important predictive biomarker for immunotherapy. Due to the heterogeneous distribution of PD-L1, post-operative histopathology fails to accurately capture its expression in residual tumors, making intra-operative diagnosis crucial for GBM treatment strategies. However, the current methods for evaluating the expression of PD-L1 are still time-consuming. To overcome the PD-L1 heterogeneity and enable rapid, accurate, and label-free imaging of PD-L1 expression level in GBM IME at the tissue level. We proposed a novel intra-operative diagnostic method, Machine Learning Cascade (MLC)-based Raman histopathology, which uses a coordinate localization system (CLS), hierarchical clustering analysis (HCA), support vector machine (SVM), and similarity analysis (SA). This method enables visualization of PD-L1 expression in glioma cells, CD8+ T cells, macrophages, and normal cells in addition to the tumor/normal boundary. The study quantified PD-L1 expression levels using the tumor proportion, combined positive, and cellular composition scores (TPS, CPS, and CCS, respectively) based on Raman data. Furthermore, the association between Raman spectral features and biomolecules was examined biochemically. The entire process from signal collection to visualization could be completed within 30 min. In an orthotopic glioma mouse model, the MLC-based Raman histopathology demonstrated a high average accuracy (0.990) for identifying different cells and exhibited strong concordance with multiplex immunofluorescence (84.31 %) and traditional pathologists' scoring (R 2 ≥ 0.9). Moreover, the peak intensities at 837 and 874 cm−1 showed a positive linear correlation with PD-L1 expression level. This study introduced a new and extendable diagnostic method to achieve rapid and accurate visualization of PD-L1 expression in GBM IMB at the tissular level, leading to great potential in GBM intraoperative diagnosis for guiding surgery and post-operative immunotherapy. [ABSTRACT FROM AUTHOR]

The structures of two K-richterite crystals with the crystal chemical formulas (K0.44Na0.320.24)Σ=1(Ca1.18Na0.82)Σ=2Mg5Si8O22OH2 and (K0.83Na0.020.15)Σ=1(Ca1.11Na0.89)Σ=2Mg5Si8O22OH2 synthesized at a pressure of 3 GPa and a temperature of 1000°С in the MgSiO3 + CaMgSi2O6 + K2CO3 + Na2CO3 + CO2 + H2O system were studied by single-crystal X-ray analysis and Raman spectroscopy. The monoclinic cell parameters were obtained: a = 10.0256(5) and 9.9748(11) Å, b = 17.9874(7) and 17.9879(16) Å, c = 5.2687(3) and 5.2746(6) Å, Ve.c. = 916.17(18) and 918.52(8) Å3, β = 104.520(12)° and 104.821(5)°, sp. gr. С2/m (12), and Z = 2. The sites M(1), M(2), and M(3) are inhabited by Mg2+, while site M(4) is occupied simultaneously by Ca2+ and Na+. The Na+ cations not included in M(4) are located in position A, which also accommodates K+ cations. Raman spectroscopy made it possible to reveal vacancies in position A in both samples. The structure corresponds to the "ideal" structure of richterite group minerals. The unit cell volume of the measured crystals is directly proportional to the K content in position A. Based on the generalization of new and published data, an equation of the dependence of Vu.c. for amphiboles of the richterite Na(NaCa)Mg5Si8O22(OH)2–K-richterite K(NaCa)Mg5Si8O22(OH)2 series with a low tremolite component on the K content in position A is proposed. [ABSTRACT FROM AUTHOR]

Samples of siliceous rocks of the Southern Kambalny Central Thermal Field (SKC) containing a unique ore mineralization were studied. Optical microscopy, scanning electron microscopy, X-ray microanalysis, X-ray diffraction, ICP-MS, and Raman spectroscopy were used in this study. High concentrations and a wide range of rare and rare-earth elements were found in siliceous rocks. Silicates (quartz, moganite, and opal-crystobalite/tridymite opal), oxides (hematite and anatase), hydroxides (goethite), carbonates (calcite with Fe and Mn impurities), sulfates (barite with Sr impurity and gypsum), sulfides (pyrite, marcasite, chalcopyrite, and chalcocite), phosphates (xenotime-Y, YPO4 with impurities of lanthanides, S, Ca, and As; berlinite, AlPO4 with the V impurity), and apatite were identified. Structures of anatase replacement by quartz often in association with pyrite were identified. The mineralization of SKC siliceous rocks reflects the physicochemical specificity of deep metal-bearing solutions. [ABSTRACT FROM AUTHOR]

Information about the spectra of noble metal minerals obtained by Raman spectroscopy, using the example of a new copper–gold–platinum ore occurrence in the Polar Urals, is presented. For the first time, spectra of temagamite and minerals of the intermediate merenskyite–moncheite series were obtained, and some of the previously detected minerals are refined and confirmed. The prerequisites for new mineral phases of the intermediate series are noted, difficulties in using the method and the need for further development of this area of research are indicated. It is shown that the use of Raman spectroscopy, in controversial cases, complements and often clarifies the data of microprobe studies. [ABSTRACT FROM AUTHOR]

This paper explains about the mechanical insertion of graphite particles into aluminum (Al-1100) surface for forming composites on the surface through an electrical resistance heat-supported pressing procedure. The surface of the aluminum is first graphite coated by solution casting. To achieve impregnation, the graphite–aluminum interface is locally heated with the assistance of electrical resistance heating followed by mechanical pushing. The degree to which aluminum surface softens can be regulated by process factors like current and heating time. Microstructural characterization of aluminum–graphite composite was carried out with SEM, TEM, Raman spectroscopy and XRD. It was revealed from the microstructural characterization that graphite particles were impregnated into the aluminum surface without agglomeration. Raman spectroscopy of graphite-impregnated surface shows a shift in major graphite peaks and an increased ratio of intensity ( I D / I G ). The presence of carbide compound (Al4C3) was not detected from the XRD and TEM studies. The mechanical property examination of the surface was carried out by nanoindentation and the subsurface was characterized by microhardness tests. It was observed that surface mechanical property and reduced Young's modulus were improved by more than 200% and 150%, respectively. The projected method can be utilized as a surface modification technique in solid-state by fabricating surface composites fabricated through mechanical insertion of particulate reinforcement at sub-melting temperatures of substrate and under an open producing environment. [ABSTRACT FROM AUTHOR]

The lead-free piezoelectric ceramics (1- x)Bi 3 TiTaO 9 – x Na 0.5 Bi 2.5 Nb 2 O 9 [(1- x)BTT– x NBN; x = 0.0; 0.2; 0.5; 0.7; 1.0] were prepared using the traditional solid-state method, and the microstructure and electrical properties of the novel solid solution (1- x)BTT– x NBN were studied. XRD data and Raman spectroscopy analysis indicated that Na ions and Nb ions had been incorporated into the designed lattice, forming a stable solid solution. The piezoelectric performance of the (1- x)BTT– x NBN ceramics was improved for two reasons: on one hand, the incorporation of NBN could suppress the leakage current caused by Ti ions, effectively reducing the contribution of oxygen vacancies to the direct current resistivity, thereby increasing the ceramic's direct current resistivity (ρ dc); on the other hand, the orthorhombic distortion was reduced, and the remanent polarization was enhanced. Among them, the 0.3Bi 3 TiTaO 9 -0.7Na 0.5 Bi 2.5 Nb 2 O 9 ceramic demonstrated excellent comprehensive performance: the values of d 33 , T c , and P r were 14.4 pC/N, 777.8 °C, and 9.82 μC/cm2, respectively. Specifically, at 500 °C, tan δ and ρ dc were 0.67 % and 1.01 × 108 Ω∙cm, respectively, and after depolarization at 750 °C, its d 33 remained at 97.92 % of the original value. [ABSTRACT FROM AUTHOR]