Cm-1 Band Research Articles

Antibacterial Activity of V2O5 Nanoparticles

The chemical synthesis of vanadium pentoxide nanoparticles (V2O5 NPs) is presented in this article. The formation of V2O5 NPs is confirmed by the 508 cm-1 band visible in the Fourier-transform infrared spectrum. According to the scanning electron microscopy analysis, the 40–50 nm-sized V2O5 NPs resemble sponges. The size of V2O5 NPs is in between 33.72 and 52.78 nm, as shown by XRD. The antibacterial capabilities of V2O5 NPs were evaluated against Staphylococcus aureus and Bacillus cereus. Moderate antibacterial activity is exhibited by the synthesized V2O5 NPs.

Efficacy of Sodium Fluoride and Fluoridated Calcium Phosphate in Mitigating Dental Erosion on Human Enamel: An In Vitro Analysis.

With increasing prevalence of dental erosion, this study explores the protective role of traditional fluoride-based products and newer formulations on eroded enamel. To assess the protective effectiveness of casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) and sodium fluoride (NaF) on human enamel against erosion using surface microhardness (SMH) and Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Ten extracted human third molars were sectioned to obtain 40 enamel sections and randomly assigned into four groups (n = 10) and treated as follows: G1 (Sound Enamel), G2 (Erosive Challenge), G3 (CPP-ACPF + Erosive Challenge), and G4 (NaF + Erosive Challenge). All samples were subjected to Vicker's SMH analysis, while changes in surface morphology and elemental composition were validated in few representative samples using FTIR and SEM, respectively. Paired samples test, Kruskal-Wallis test, and Tukey HSD test were performed using SPSS software version 23 setting P value < 0.05 as statistically significant. The mean SMH1 values for the experimental groups G3 and G4 were significantly higher (426.58VHN and 455.83VHN) when compared to G1 (P = 0.000) and G2 (P = 0.000). In SEM analysis, G2 showed eroded honeycomb appearance compared to the smooth homogenous surface of G1, while both G3 and G4 showed deposition of some precipitates. FTIR analysis revealed that in G3 and G4, a characteristic peak of phosphate vibrations between 528 and 823 cm-1 and carbonate bands at 845-932 cm-1 was observed. Both CPP-ACPF and NaF demonstrated a protective effect on enamel against erosive challenge by an orange juice-based beverage.

Semi-empirical water dimer model of the water vapour self-continuum within the IR absorption bands

Water vapour continuum absorption is an important component of atmospheric radiative transfer codes. It significantly impacts the radiative balance of the atmosphere, but the physical nature of this absorption remains a subject of discussion. Here the H2O self-continuum absorption is considered within the infrared absorption bands (from 50 to 11 200 cm-1) of water vapour exploiting existing measurements. Comparison of this data with the MT_CKD-3.5 continuum model, which is used in many radiative transfer codes, reveals significant quantitative and qualitative differences. New water vapour self-continuum spectra are derived from earlier FTS measurements using HITRAN-2016 in the 5300 and 7200 cm-1 bands. A previously proposed water dimer model is refined and unified based on a broad set of up-to-date experimental data on the H2O continuum. The new model, which is suitable for incorporation into radiative transfer codes, has a much firmer physical basis than existing models. It reproduces the spectral behaviour and magnitude of the in-band water vapour self-continuum for temperatures from 279 to 431 K depending on the band. Importantly, the fitted total equilibrium dimerization constant used in the updated continuum model exceeds independent estimates by a factor of 1.5–3 across the entire temperature and spectral regions studied. Possible causes for this, which are important for understanding the physical origin of the continuum, are discussed. The contribution of water dimer to the continuum is estimated to vary from 40 to 90 % depending on absorption band and temperature.

Extraction and Physicochemical Characterization of Hydroxyapatites From Horse Humerus Bones of Different Ages (1, 3, 6, and 8 Years old) Calcined at Low Temperature.

The aim of this work is to investigate the changes in the physicochemical properties of hydroxyapatite (HAp) extracted from horse humerus bones of different ages (1, 3, 6, and 8 years) subjected to low temperature calcination (600°C). Thermal analysis revealed significant mass loss due to water, collagen, organic compounds, carbonates, and age-related magnesium out-diffusion. Higher fat content in older bones contributed to increased mass loss. Phosphorus content remained constant across age groups, while calcium and sodium showed age-related fluctuations. Magnesium levels decreased with age, emphasizing its importance for early bone development. The Ca/P ratio deviated from the stoichiometric values due to additional ions from biogenic sources. Infrared spectroscopy identified functional groups in carbonated HAp, with changes observed before and after calcination. The full width at half maximum (FWHM) of the 961 cm-1 band decreased with age, indicating improved crystalline quality. The molar absorption coefficients provided information on the changes in molecular concentration and emphasized the differences between the age groups. X-ray analysis revealed nanocrystalline HAp in all samples, with crystallite size increasing with age. Rietveld analysis showed that the lattice parameters were affected by the presence of organic material, but the lattice constants remained stable, confirming high crystallinity independent of age. TEM analysis confirmed nanocrystalline structures, with crystallite size increasing with age. SEM images showed the characteristic porosity of calcined HAp, with particle size correlating positively with age. Calcination at 600°C preserved the nanoscale properties and microcrystal formation. Raman spectroscopy confirmed the identity of HAp, with FWHM variations indicating age-related changes in crystalline quality. EHAp1 showed increased FWHM, indicating lower crystalline quality and increased trace element content.

Sonochemical Synthesis of Copper Borates: Effect of Reaction Conditions on the Characteristic Properties

The effect of ultrasonic treatment on liquid-state production and the characteristic features of synthesized powder were studied in liquid-state conditions. In sonochemical synthesis, the operation parameters of mole ratio, reaction temperature, and time were optimized. The synthesis was achieved in moderate conditions such as mole ratio of copper: sodium: boron (Cu: Na: B) 1:2:1, 70°C and 2.5 minutes. The prepared samples were identified as copper borate (Cu(BO2)2) with the powder diffraction file number "00-001-0472". The reaction yields were also increased from 50% to 71.5% with the modification of the experimental procedure. The specific FT-IR peaks were observed at 1090, 985, 872, 781 and 731 cm-1 band values. In the morphological analyses, the agglomerations of multi-angular particles were seen. The results showed the affirmative effects of the possible use of the ultrasonic treatment on both the practical synthesis and the increase of characteristics.

Low-Frequency Spectra of Hydrated Ionic Liquids with Kosmotropic and Chaotropic Anions.

In this study, we investigated the water concentration dependence of the intermolecular vibrations of two hydrated ionic liquids (ILs), cholinium dihydrogen phosphate ([ch][dhp]) and cholinium bromide ([ch]Br), using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES). The anions of the former and latter hydrated ILs are kosmotropic and chaotropic, respectively. We found that the spectral peak of ∼50 cm-1 shifted to the low-frequency side in hydrated [ch][dhp], indicating the weakening of its intermolecular interactions. In contrast, no change in the peak frequency of the low-frequency band at ∼50 cm-1 was observed with increasing water concentration in hydrated [ch]Br. The vibrational density of states (VDOS) spectra generated from molecular dynamics (MD) simulations were in qualitative agreement with the experimental results. Decomposition analysis of the VDOS spectra for each component revealed that the red shift of the low-frequency band in the hydrated [ch][dhp] upon water addition was essentially due to the contributions of anions and water rather than that of the cholinium cation. We also found from the low-frequency spectra of the two hydrated ILs that they differed in the concentration dependence of the 180 cm-1 band, which is assigned as a hindered translational motion of water molecules combined to form O···O stretching motions. From the relationship between the peak frequency of the low-frequency band and the bulk parameter, which is the square root of the surface tension divided by the density, we found that the peak frequency in the hydrated IL with kosmotropic [dhp]- depends on the bulk parameter, similar to the case for an aqueous solution of the typical deep eutectic solvent reline. However, the peak frequency of the hydrated IL with chaotropic Br- is constant with the bulk parameter.

Synthesis and Characterization of Hybridfiber from Gelatin Modified by PVACOS Using Coaxial Electrospinning Techniques as an Advanced Medical Textile Material

The synthesis of hybrid fiber based on bovine bone gelatin combined with polyvinyl alcohol-chitosan-oxidized sucrose (PVACOS) has been successfully carried out using the coaxial electrospinning technique. The presence of oxidized sucrose can improve the diameter and the tensile strength of hybrid fibers due to the formation of new covalent bonds. The combination of gelatin with PVACOS material aims to increase the strength of the hybrid fiber so that it has better tensile strength characteristics and improves the diameter of the resulting hybrid fiber. The characterization of the resulting material was tested using FTIR, SEM, EDX, XRD, and TGA. Based on FTIR analysis, there is an increase in absorption intensity in the 2900 cm-1 – 3000 cm-1 band, which indicates the occurrence of covalent bond interactions so that it can increase the bond strength between materials with the performance of crystalline materials. Apart from that, the morphological structure of the hybrid fibers was also investigated using scanning electron microscopy (SEM), and the resulting fiber diameter for Ge-Ch, Ge-Ch-PVA, Ge-PVACOS 3%, and Ge-PVACOS 5%, respectively, was 0.4049 µm. 0.3735 µm, 0.3388 µm, and 0.3206 µm. The tensile strengths of hybrid fiber for Ge-PVACOS 3% and Ge-PVACOS 5%, respectively, are 39.91935 N/m2 and 76.12507 N/m2. Statistical tests show that the concentration of oxidized sucrose has a significant influence on hybrid fiber performance. The significance values for diameter and tensile strength are 0.0486 and 0.0325, respectively. According to this performance, the Ge-PVACOS hybrid fiber is recommended as a material for advanced medical textiles. Doi: 10.28991/ESJ-2024-08-02-022 Full Text: PDF

Correlated libration in liquid water.

The libration spectrum of liquid H2O is resolved into an octupolar twisting libration band at 485 cm-1 and dipolar rocking-wagging libration bands at 707 and 743 cm-1 using polarization analysis of the hyper-Raman scattering (HRS) spectrum. Dipole interactions and orientation correlation over distances less than 2nm account for the 36 cm-1 splitting of the longitudinal and transverse polarized bands of the dipolar rocking-wagging libration mode, while the intensity difference observed for the bands is the result of libration correlation over distances larger than 200nm. The coupled rock and wag libration in water is similar to libration modes in ice. The libration relaxation time determined from the width of the spectrum is 36-54fs. Polarization analysis of the HRS spectrum also shows long range correlation for molecular orientation and hindered translation, bending and stretching vibrations in water.

Differential diagnosis of Crohn's disease and intestinal tuberculosis based on ATR-FTIR spectroscopy combined with machine learning.

Crohn's disease (CD) is often misdiagnosed as intestinal tuberculosis (ITB). However, the treatment and prognosis of these two diseases are dramatically different. Therefore, it is important to develop a method to identify CD and ITB with high accuracy, specificity, and speed. To develop a method to identify CD and ITB with high accuracy, specificity, and speed. A total of 72 paraffin wax-embedded tissue sections were pathologically and clinically diagnosed as CD or ITB. Paraffin wax-embedded tissue sections were attached to a metal coating and measured using attenuated total reflectance fourier transform infrared spectroscopy at mid-infrared wavelengths combined with XGBoost for differential diagnosis. The results showed that the paraffin wax-embedded specimens of CD and ITB were significantly different in their spectral signals at 1074 cm-1 and 1234 cm-1 bands, and the differential diagnosis model based on spectral characteristics combined with machine learning showed accuracy, specificity, and sensitivity of 91.84%, 92.59%, and 90.90%, respectively, for the differential diagnosis of CD and ITB. Information on the mid-infrared region can reveal the different histological components of CD and ITB at the molecular level, and spectral analysis combined with machine learning to establish a diagnostic model is expected to become a new method for the differential diagnosis of CD and ITB.

Simultaneous determination of glucose and albumin in human urine using attenuated total reflection Fourier-transform infrared spectroscopy.

The ability to quantify albuminuria and glucose is important in identifying conditions such as cardiovascular disease (CVD), chronic kidney disease (CKD), and diabetes. This study utilized Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy to analyze aqueous urine samples spiked with bovine serum albumin (BSA) and glucose at different concentrations. The aim was to determine the limit of detection of the technology using aqueous samples for the future development of a pathological prediction model. The ATR-FTIR spectra of the co-spiked samples exhibited pronounced amide I (1662 cm-1) and amide II (1545 cm-1) bands indicative of elevated protein along with glucose-associated bands at 1155, 1107, 1079 and 1036 cm-1. Partial Least Squares (PLS) yielded promising R2 values of more than 0.9 for BSA, glucose, and co-spiked glucose/protein. The limit of detection of the technique was 40.28 mg L-1 for protein and 291.65 mg L-1 for glucose, demonstrating the potential of the technique as a tool to identify analytes associated with pathological conditions including cardiovascular disease (CVD), chronic kidney disease (CKD), and diabetes.

Investigation of etravirine uptake and distribution in single aortic endothelial cells in vitro using Raman imaging.

Etravirine (ETV) is an antiretroviral agent that belongs to the class of non-nucleoside reverse transcriptase inhibitors. This study explores the uptake and distribution of ETV in human aortic endothelial cells (HAECs) using Raman spectroscopy combined with chemometrics. The distinctive chemical structure of ETV facilitates tracking of its uptake by observing the Raman band at 2225 cm-1 in the Raman-silent region. The perinuclear distribution pattern in HAECs depends on drug concentration and incubation time. The uptake of ETV is observed within 5 minutes at a concentration of 10 μM, as evidenced by Raman images. Lower ETV concentrations, reflective of those found in human plasma, are detectable in HAECs by applying chemometric methods to Raman spectra from the perinuclear region. The ETV accumulation process is crucial in advancing our understanding of the drug's impact on biochemical alterations within endothelial cells. Additionally, ETV emerges as a promising Raman reporter for marking subcellular compartments, leveraging the 2225 cm-1 band in the cellular Raman silent region. This research contributes valuable insights into the behavior of ETV at the subcellular level, shedding light on its potential applications and impact on subcellular dynamics.

Development of Multi-Analysis By Operando Spectroscopy / Elemental Measurement in Oxide-Type All-Solid-State Na Batteries

Introduction Oxide-type all-solid-state Na batteries (ASSBs) are attracted attention owing to their high safety, resource abundant and intrinsic chemical stability, toward electric storage system for renewable energies, such as photovoltaics and wind generations, using electrochemical devices in urban locations. Although the ASSBs shows low output performances and high internal resistances due to their low sinter density in general, the improvement of these properties have been strenuously studied by using the spark-plasma-sintering (SPS) and sintering additives of low melting point material such as B2O3. However, charge-discharge process is complex reactions extremely, which includes redox reactions of electrode, ionic transport of solid electrolyte at macro / micro-scales every component material. Therefore, to perspective understanding of charge-discharge reactions in the ASSBs, the construction of analysis technique is strongly desired by combination of evaluation methods with suitable selection for each scale. Herein, the multi-scale analysis was demonstrated by using Operando scanning electron microscopy / energy dispersive X-ray spectroscopy (SEM / EDS) (µm-scale) and Raman spectroscopy (atomic-order) for observing changes of Na concentration, bonding states during charge-discharge processes, respectively, in addition evaluation of elemental distributions through the time-of-fright secondary ion mass spectrometry (TOF-SIMS) (nm-scale). Experimental The ASSBs were fabricated by multi-step-sintering method using SPS1 from Na3V2(PO4)3 (NVP) as positive (PE) and negative electrode (NE) active materials, Na3Zr2Si2PO12 (NZSP) as solid electrolyte (SE), B2O3 as adhesive between PE/SE and SE/NE layers. The electrode composition were NVP : NZSP : carbon = 25 : 60 : 15 by weight ratio. The sintered ASSB was physically split for arbitrary size, and then obtained piece loaded into a sample holder of Ar-ion milling system in Ar atmosphere to prepare smooth surface of cross-sectional direction. After the Ar-ion milled sample was transferred to holder enabled to apply voltage, Operando SEM-EDS was performed by cyclic voltammetry (CV) with 0.2 mV s-1 of scan rate, 0.5 - 2.5 V of voltage range at room temperature, and acquired elemental mapping images every 0.5 V for 3 min of recording time. As evaluation at 2, 3 cycle, Operando Raman spectroscopy using the same sample was performed by CV with same conditions at room temperature (at 2 cycle) and 60oC (at 3 cycle), using electrochemical measurement cell having observation window of quartz glass. After 3 cycles, the TOF-SIMS mappings were acquired from all area of the cross-sectional ASSB by using plus mode. Results & Discussion From the Operando SEM / EDS, the distributions of Na element clear changed in PE and NE layers under charge-discharge processes, the 2D-dimensional profile on Na counts normalized by P, which is estimated to be not contribute electrochemical reactions, is shown Figure 1 (a). The Na concentration were confirmed decrease / increase trends at charge process, even though there were decreased / increased at discharge process in the PE and NE layers, respectively. These behaviors of concentration change mean to Na transport between the PE and NE layers with deintercalation and intercalation reactions of NVP during charge-discharge processes. On other hand, Figure 1 (b), (c) shows the Raman spectra changes for PE and NE layers at 2 cycle. Although the D- (1380 cm-1) and G- (1520 cm-1) bands related to carbon material did not change, the integrated intensities at about 780 cm-1 clear increased / decreased at PE layer in charge-discharge processes, respectively. These peaks were assigned to PO4 bonding of NVP, and suggested to reversible structural change owing to intercalation and deintercalation reactions of Na. In addition, the calculation result of Na pathway in the NVP was reported by migration between PO4 tetrahedral along the x direction with low activation energy, and should affect bonding states owing to change of backbone structure during charge-discharge processes.2 Therefore, the peak of PO4 bonding is considered as estimation index on the state-of-charge with electrode redox reactions in ASSBs. In other words, intercalation / deintercalation of Na affects not only structural change of NVP, but also concentration change in all areas of PE and NE layers and these reactions could be directly observed by combination of Operando SEM / EDS and Ram.an spectroscopy. In this presentation, we will also report the results of elemental distributions after 3 cycles by acquired from the TOF-SIMS analysis and correlationship between each evaluation technique for ASSB. D. Kutsuzawa, et al., ACS Appl. Energy Mater., 5, 4025–4028 (2022)W. Song et al., J. Mater. Chem. A, 2, 5358 (2014). Figure 1

Multispectral Raman Differentiation of Malignant Skin Neoplasms In Vitro: Search for Specific Biomarkers and Optimal Wavelengths.

Confocal scanning Raman and photoluminescence (PL) microspectroscopy is a structure-sensitive optical method that allows the non-invasive analysis of biomarkers in the skin tissue. We used it to perform in vitro diagnostics of different malignant skin neoplasms at several excitation wavelengths (532, 785 and 1064 nm). Distinct spectral differences were noticed in the Raman spectra of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), compared with healthy skin. Our analysis of Raman/PL spectra at the different excitation wavelengths enabled us to propose two novel wavelength-independent spectral criteria (intensity ratios for 1302 cm-1 and 1445 cm-1 bands, 1745 cm-1 and 1445 cm-1 bands), related to the different vibrational "fingerprints" of cell membrane lipids as biomarkers, which was confirmed by the multivariate curve resolution (MCR) technique. These criteria allowed us to differentiate healthy skin from BCC and SCC with sensitivity and specificity higher than 95%, demonstrating high clinical importance in the differential diagnostics of skin tumors.

Efficient Photocatalytic Reduction of Hexavalent Chromium by BiVO4-Decorated MXene Photocatalysts and Their Charge Carrier Dynamics.

The synergistically MXene (Ti3C2Tx) co-catalyst-decorated BiVO4-based heterostructured photocatalysts have been synthesized by a hydrothermal approach with varied loading concentrations of MXene (Ti3C2Tx) to drive the hexavalent chromium reduction efficiently. The formation of the heterostructured photocatalyst was confirmed by the appearance of X-ray diffraction (XRD) peaks corresponding to the monoclinic BiVO4 phase and MXene (Ti3C2Tx) and also the antisymmetric (834 cm-1) and symmetric stretching (715 cm-1) of tetrahedral VO4 and D (1330 cm-1) and G (1570 cm-1) bands corresponding to MXene (Ti3C2Tx) in the Raman spectrum. The worm-like structures of BiVO4 nanocrystals grew onto the lamellar sheets of MXene (Ti3C2Tx), as shown by field emission scanning electron microscopy (FESEM), and has an increased surface area of 15.62 m2g-1 in the case of BVO-20-TC. X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of V5+ and Ti3+states, and the uniform distribution of BiVO4 nanocrystals over lamellar sheets of MXene (Ti3C2Tx) is evident from energy-dispersive X-ray (EDX) analysis. The ultraviolet-diffuse reflectance spectroscopy (UV-DRS) spectra suggest a decrease in the band gap energy of BVO-20-TC to 2.335 eV, promoting a higher degree of visible light harvesting. Upon optimization, by varying the pH, the amount of the photocatalyst, and the concentration of Cr(IV), BVO-20-TC exhibits the highest photocatalytic efficiency (96.39%) while using a Cr(VI) concentration of 10 ppm at pH 2 and 15 mg of the photocatalyst, and the photoreduction of Cr(VI) to Cr(III) follows the pseudo-first-order reaction. The decrease in the PL intensity in BVO-20-TC reveals a faster transfer of electrons from MXene (Ti3C2Tx) to BiVO4. Further, the higher degree of band bending at the BiVO4/MXene (Ti3C2Tx) heterojunction, revealed from the Mott-Schottky analysis, facilitates efficient charge transfer and eventually faster and efficient photoreduction of Cr(VI) to Cr(III). The reusability and stability test undertaken for BVO-20-TC reveals that even after five cycles, the Cr (VI) photoreduction efficacy is retained. This work provides insights into photoreduction of Cr (VI) by using such heterostructures.

Re-Structuring of Interfacial Water into Strongly Hydrogen Bonded “Ice-like” Structures as the Unifying Descriptor for Improving Sluggish HOR/HER in Alkaline Electrolyte

The 2 orders of magnitude loss of Platinum Group Metal (PGM) activity toward Hydrogen Oxidation and Reduction reactions (HOR/HER) has hindered implementation of alkaline based electrolyzers and fuel cells and demonstrated a significant knowledge gap in our fundamental understanding of electrochemical interfaces.1 Beneath the seemingly simple reaction lies a potentially convoluted mechanism, with various researchers assigning the activity loss to shifts in electrode potential of zero free charge,2 changed binding energies of adsorbates and reactive intermediates,3,4 and the re-arrangement of interfacial water.5 Recently, Monteiro et al. showed an activity dependence on interfacial cation concentration and identity, suggesting that charge dense cations are able to better stabilize the OH- produced from the unfavorable but necessary water splitting in the HER direction near the negatively charged surface.6,7 In this work, we challenge this notion by demonstrating that competition for water molecules between Outer Helmholtz Plane (OHP) cations and the interfacial water structure is responsible for the activity loss. Through the use of traditional Rotating Disk Electrode, in situ Attenuated Total Reflection-Surface Enhanced Infrared Reflection Absorption Spectroscopy (ATR-SEIRAS) and judicious choice of crown ether additives to hinder the water-interfacial cation interaction, we show a positive correlation between the strength and number of interfacial water-water hydrogen bonds and platinum’s HOR/HER activity.The typical double layer structure in an aqueous electrochemical system consists of specifically adsorbed species in the Inner Helmholtz Plane (IHP), the first layer of non-adsorbates at the OHP, and water hydrating the charged species. ATR-SEIRAS has previously been used to analyze the structure of these hydration shells on a CO covered Pt surface, demonstrating hydrating waters interacting mainly with alkali metal cations through the increase of a 3600 cm-1 ν(O-H) stretch and weak interactions with surrounding interfacial water.8 Through chelation with crown ether, these hydration shells convert from strongly to weakly cation interacting, favoring instead hydrogen bonding with other water molecules, shown with increasing absorption bands at lower wavenumbers (3400 cm-1). This transition is accompanied by an increase in 3000 cm-1 on the CO-free Pt surface, previously assigned to strongly hydrogen bonded “ice-like” interfacial water.9 We further show a similar increase in the 3000 cm-1 band for other kinetic enhancing additives recently reported in the literature, supporting the notion that increasing water-water hydrogen bonding is the unifying descriptor for promoting a rigid interfacial “ice-like” structure and improving PGM HOR/HER activity. Durst, J. et al. New insights into the electrochemical hydrogen oxidation and evolution reaction mechanism. Energy Environ. Sci. 7, 2255–2260 (2014).Sarabia, F. J., Sebastián-Pascual, P., Koper, M. T. M., Climent, V. & Feliu, J. M. Effect of the Interfacial Water Structure on the Hydrogen Evolution Reaction on Pt(111) Modified with Different Nickel Hydroxide Coverages in Alkaline Media. ACS Appl. Mater. Interfaces 11, 613–623 (2019).McCrum, I. T. & Koper, M. T. M. The role of adsorbed hydroxide in hydrogen evolution reaction kinetics on modified platinum. Nat. Energy 5, 891–899 (2020).Yang, X., Nash, J., Oliveira, N. J., Yan, Y. & Xu, B. Understanding the pH Dependence of Underpotential Deposited Hydrogen on Platinum. Angew. Chemie - Int. Ed. 58, 17718–17723 (2019).Zhao, K. et al. Enhancing Hydrogen Oxidation and Evolution Kinetics by Tuning the Interfacial Hydrogen-Bonding Environment on Functionalized Platinum Surfaces. Angew. Chemie - Int. Ed. 61, (2022).Monteiro, M. C. O., Goyal, A., Moerland, P. & Koper, M. T. M. Understanding Cation Trends for Hydrogen Evolution on Platinum and Gold Electrodes in Alkaline Media. ACS Catal. 11, 14328–14335 (2021).Goyal, A. & Koper, M. T. M. The Interrelated Effect of Cations and Electrolyte pH on the Hydrogen Evolution Reaction on Gold Electrodes in Alkaline Media. Angew. Chemie - Int. Ed. 60, 13452–13462 (2021).Yamakata, A. & Osawa, M. Cation-dependent restructure of the electric double layer on CO-covered Pt electrodes: Difference between hydrophilic and hydrophobic cations. J. Electroanal. Chem. 800, 19–24 (2017).Osawa, M., Tsushima, M., Mogami, H., Samjeské, G. & Yamakata, A. Structure of water at the electrified platinum-water interface: A study by surface-enhanced infrared absorption spectroscopy. J. Phys. Chem. C 112, 4248–4256 (2008). Figure 1

Structural and optical properties of europium-doped sodium-lead-antimony glasses

Antimony-sodium-lead glasses doped with varying amounts of europium were synthesized using the melt quenching technique. To investigate the mutual effects between the dopant and the glass matrix, various methods and techniques were employed to analyze and characterize the glass samples. These methods included X-ray diffraction (XRD) for justifying the amorphous nature of the samples, differential scanning calorimetry (DSC) for analyzing thermal properties, Fourier transform infrared (FTIR) spectroscopy for studying functional groups in the 1400–400 cm-1 range, and peak deconvolution techniques used to analyze the defect impact in the 1100–800 cm-1 band region. UV–VIS spectroscopy was utilized for absorption analysis, optical band gap estimation, and Urbach energy calculation. Photoluminescence spectroscopy was employed in the UV–VIS-NIR range to investigate excitation, emission, lifetime decay, and local structure of Eu3+ ions within the disordered matrix, characterized by high polarizability content. Judd-Ofelt analysis and radiative parameters were obtained from emission spectra using a 464 nm excitation wavelength. The estimation of the optical band gap revealed broadening and shrinking with increasing Eu3+ ion concentration. The excitation spectra showcased the potential for emission under two distinct excitation mechanisms: single-photon excitation (1PE) and two-photon excitation (2PE). The quality of emitted light color was characterized using CIE chromaticity coordinates.

Conformational Relaxation Dynamics of Poly(3-hexylthiophene) Photoexcited in Solution as Studied by Femtosecond Time-Resolved Stimulated Raman Spectroscopy in 1190-1550 nm Region.

When a conjugated polymer is photoexcited in solution, its effective conjugation length in the singlet exciton state often increases through the conformational relaxation of the polymer main chain and/or hopping of the excitation. We measured femtosecond time-resolved near-IR stimulated Raman spectra of poly(3-hexylthiophene) (P3HT) photoexcited in four organic solvents for understanding the dynamics of the exciton elongation through the conformational relaxation separately from that through the exciton hopping. In the ring CC stretch frequency region, a band appears at around 1415 cm-1 and decays, while a new band rises at around 1370 cm-1. The average time constant of the change is estimated to be 8.7-19 ps and correlated almost linearly with the viscosity of the solvents. These results suggest that the main chain of P3HT in the singlet exciton state relaxes from a twisted form to a planar form in the 0-100 ps range when it surmounts an activation barrier of 5.8-7.8 kJ mol-1, generated possibly by the steric effect of the hexyl side group. When the rise of the 1370 cm-1 band is analyzed in detail, it is reproduced with two exponential rise functions with time constants of 0-3.3 and 16-22 ps. The two rise components suggest that a portion of P3HT forms a cluster in solution, while the other portion of P3HT is isolated.

Preparation and physicochemical characterization of debranched rice starch nanoparticles from mono- and dual-modification by hydrothermal treatments

Starch nanoparticles (SNPs) are attracting attention due to their novel attributes beneficial to certain applications; their fabrication technique and physicochemical attributes have yet to be systematically investigated. In this study, starch nanoparticles were fabricated from the debranched rice starches of three rice lines employing the mono-modification by annealing treatments for one and five days and the dual-modification by the combined annealing and heat-moisture treatments, and their physicochemical properties were characterized. The highest percent recovery of crystalline SNPs was obtained by the dual-modification treatments (32.6–45.6%), followed by the five-day annealing treatment (23.8–28.7%), and then the one-day annealing treatment (11.7–15.8%). The modified starches showed significant increases in oil absorption capacity, water holding capacity, and solubility and decreases in swelling power and volume fraction compared to their native counterparts. The crystal types were changed from A-type to B-type polymorphs by mono-modification treatment and to CA-type polymorphs by the dual-modification treatment with significant increases in relative crystallinity. The dual-modification treatment resulted in the highest increases in 1047/1022 cm-1, 995/1022 cm-1, and 1047/1035 cm-1 band ratios and the highest melting temperatures and enthalpies. The resistant starch contents of the modified starches were markedly increased and strongly related to the percent recovery and the short- and long-range ordered structures. The results suggest that the dual-modified starches comprised the rigid and densely packing of nanoaggregates with superior oil/water absorption performance and water dispersibility, and high enzymatic resistance, which could be the contributing factors for their utilizations as novel ingredients in food-related applications.

Spatiotemporal Mapping of Local Heterogeneities during Electrochemical Carbon Dioxide Reduction.

The activity and selectivity of a copper electrocatalyst during the electrochemical CO2 reduction reaction (eCO2RR) are largely dominated by the interplay between local reaction environment, the catalyst surface, and the adsorbed intermediates. In situ characterization studies have revealed many aspects of this intimate relationship between surface reactivity and adsorbed species, but these investigations are often limited by the spatial and temporal resolution of the analytical technique of choice. Here, Raman spectroscopy with both space and time resolution was used to reveal the distribution of adsorbed species and potential reaction intermediates on a copper electrode during eCO2RR. Principal component analysis (PCA) of the in situ Raman spectra revealed that a working electrocatalyst exhibits spatial heterogeneities in adsorbed species, and that the electrode surface can be divided into CO-dominant (mainly located at dendrite structures) and C-C dominant regions (mainly located at the roughened electrode surface). Our spectral evaluation further showed that in the CO-dominant regions, linear CO was observed (as characterized by a band at ∼2090 cm-1), accompanied by the more classical Cu-CO bending and stretching vibrations located at ∼280 and ∼360 cm-1, respectively. In contrast, in the C-C directing region, these three Raman bands are suppressed, while at the same time a band at ∼495 cm-1 and a broad Cu-CO band at ∼2050 cm-1 dominate the Raman spectra. Furthermore, PCA revealed that anodization creates more C-C dominant regions, and labeling experiments confirmed that the 495 cm-1 band originates from the presence of a Cu-C intermediate. These results indicate that a copper electrode at work is very dynamic, thereby clearly displaying spatiotemporal heterogeneities, and that in situ micro-spectroscopic techniques are crucial for understanding the eCO2RR mechanism of working electrocatalyst materials.

Central and Peripheral Fatigue Evaluation during Physical Exercise in Athletic Horses by Means of Raman Spectroscopy.

The evaluation of the performance levels in athletic horses is of major importance to prevent sports injuries. Raman spectroscopy is an innovative technique that allows for a rapid evaluation of biomolecules in biological fluids. It also permits qualitative and quantitative sample analyses, which lead to the simultaneous determination of the components of the examined biological fluids. On the basis of this, the Raman spectroscopy technique was applied on serum samples collected from five Italian Saddle horses subjected to a standardized obstacle course preceded by a warm-up to evaluate the applicability of this technique for the assessment of central and peripheral fatigue in athletic horses. Blood samples were collected via jugular venipuncture in a vacutainer tube with a clot activator before exercise, immediately after exercise, and 30 min and 1 h after the end of the obstacle course. Observing the obtained Raman spectra, the major changes due to the experimental conditions appeared in the (1300-1360) cm-1 and (1385-1520) cm-1 bands. In the (1300-1360) cm-1 band, lipids and tryptophan were identified; in the (1385-1520) cm-1 band, leucine, glycine, isoleucine, lactic acid, tripeptide, adenosine, and beta carotene were identified. A significant effect of exercise was recorded on all the sub-bands. In particular, a change immediately after exercise versus before exercise was found. Moreover, the mean lactic concentration was positively correlated with the Raman area of the sub-band assigned to lactic acid. In this context, the application of Raman spectroscopy on blood serum samples represents a useful technique for secondary-structure protein identification to investigate the metabolic changes that occur in athletic horses during physical exercise.