Infrared Spectroscopy Research Articles

Fabrication with magnetic-spin coating: Influence of magnetic-inertia energy ratio on gold-pickering ferrofluid droplet assembly morphology

Magnetic self-assembly of nanoparticles is a well-known technique for creating thin-film array-patterned functional microstructures. However, an uncontrollable hierarchical assembly formation of magnetically stimulated particles has hindered the desired formation of free-standing two-dimensional (2D) array patterns in thin-film layers. In this study, we proposed a fluidic shearing effect from spin coating to reduce magnetically stimulated particles’ disarrayed and complex chain formations, thus promoting linear array formations, even as the film becomes thinner. A series of tests were conducted on a gold-Pickering ferrofluid emulsion (GPFE) dispersed in 15.2 mPas aqueous polyvinyl alcohol (PVAh), which was subjected to varying spin speeds under magnetic setups such as single (SI), compound (CC), and concentric (CR). These setups were chosen to observe the influence of magnetic field strength and distribution on the generated pattern profile from microscopic binary images of the resulting thin films. The aim was to quantify the formed chain thickness (ChT), chain gaps (ChG), and chain lengths (ChL) to capture the morphology and geometrical features of the formed patterns. Our results showed that the quantified values of these profiles and their dimensionless relationships were significantly influenced by the ratio between the applied magnetic packing energy and the centrifugally controlled fluidic energy, QPD. This investigation showed that ChT/ChG for a corresponding QPD value is 98.6% the same for all configurations, and CR was the best setup going forward, as it yielded the lowest array quality defectivity of 14%. Therefore, we assert that this fabrication method offers flexibility, cost-effectiveness, and expandability in generating linear array patterns that contain graduating variability in grating order dimensions within a single cast that can serve efficiently as a substrate for biomolecules under enhanced Raman and Infrared spectroscopies.

Synthesis and physicochemical studies of iron(III) complex compounds with TSC

The authors developed methods for the synthesis of coordination compounds of iron(III) with thiosemicarbazide (TSC).The compounds structure was proved by IR spectroscopy, conductometry, X-ray diffraction, and thermogravimetry. The authors found the bidentate coordination of TSC with iron(III) via sulphur and nitrogen atoms. Thermogravimetrically authors have established the proceeding of the complex decomposition in two stages. The first stage involves thermolysis of organic ligands with the formation of the corresponding iron salts; the second one includes decomposition of iron salts and formation of iron(III) oxide. Conductometrically we have established the synthesised complexes are strong electrolytes. X-ray diffraction shows the crystallisation of the complexes into orthorhombic syngonies. There are two structural units in the cell.

Coordination compounds of zinc carboxylates with an unusual benzohydrazide binding mode

Two new coordination compounds [Zn(Bhz)4(p-OB)2] (1) and [Zn(Bhz)3][Zn(Bhz)2(Fum)2].2H2O (2) (Bhz – benzohydrazide, p-OB - p-hydroxybenzoate, Fum - fumarate anions) have been synthesized and characterized by elemental analysis, IR spectroscopy, mass spectrometry and single-crystal X-ray diffraction.The results obtained show that the nature of the anion is very important factor in the complexes construction and strongly defines the coordination mode of hydrazide and acid ligands. Coordination compounds of zinc with monodentate benzohydrazide were synthesized for the first time.

Synthesis and Molecular Docking Studies of New Ibuprofen Derivatives as AChE, BChE, and COX‐2 Inhibitors

AbstractAlzheimer's disease (AD), the most common age‐related neurodegenerative condition, is named after Alois Alzheimer and is marked by a progressive deterioration in memory, cognitive function, and behavior. Research has highlighted the importance of nonsteroidal anti‐inflammatory drugs (NSAIDs) in inhibiting the aggregation of amyloid β‐peptide (Aβ), a key feature of AD pathology. Ibuprofen, an NSAID from the propionic acid class, is widely used to manage osteoarthritis and rheumatoid arthritis, exhibiting strong anti‐inflammatory and antipyretic effects. However, the drug's acidic group limits its selectivity for cyclooxygenase (COX) enzymes and contributes to several adverse effects. This study aimed to modify the acidic moiety of ibuprofen into lactone (IBU‐O 1–4) and lactam (IBU‐I 1–3) derivatives to mitigate these side effects. The structural properties of the synthesized imidazolone (IBU‐I 1–3) and oxazolone (IBU‐O 1–4) derivatives were characterized through Q‐TOF LC‐MS, ¹H‐NMR, ¹3C‐NMR, and IR spectroscopy. Molecular docking studies followed by Ellman's method assessed the inhibitory effects of these compounds on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), while an enzyme immunoassay (EIA) kit was used to evaluate their inhibition of cyclooxygenase‐2 (COX‐2).

Novel 1,2,3-triazole derivatives containing benzoxazinone scaffold: Synthesis, docking study, DFT analysis and biological evaluation

In order to address the drastic demand for novel broad-spectrum antibacterial and anticancer medicines with enhanced activity, computer modelling was utilized to rationally develop newer anticancer triazole based drugs. A unique series of benzo[d][1,3]oxazin-4-one linked 1,2,3-triazoles was synthesised in five steps, with good yields and an assessment of their antibacterial and anticancer activities. IR spectroscopy, 1H NMR, 13C NMR, and mass spectrometry were used to characterize the synthesis of triazole compounds. From antibacterial screening, the prepared derivatives namely, 8a, 8e, 8h and 8k showed excellent inhibitory potential against S. aureus with ZI of 28 ± 0.48, 30 ± 0.42, 30 ± 0.11, 35 ± 0.23 mm respectively, compared to moxifloxacin (33 ± 0.15 mm). Compared to doxorubicin (IC50 = 2.45 ± 0.14 μM), compounds 8h and 8k demonstrated superior and exceptional cytotoxicity against the A549 cell line (IC50 = 2.30 ± 0.26 and 1.90 ± 0.30 μM, respectively). Latter All the derivatives were further subjected to in silico docking studies against human lung (PDB: 2P85), VEGFR2 kinase domain (PDB: 3CP9) and could serve as ideal leads for additional modification in the field of anticancer research. Based on docking results, 8e showed that the amino acids Arg373(A), Gly113(A), Glu103(A), Asp108(A), Ser119(A), Asn375(A), Val374(A), Lys387(A), and Asn120(A) exhibited highly stable binding to cytochrome P4502A13 receptor of lung cancer. Furthermore, Density Functional Theory (DFT) calculations are performed to support the molecular docking studies. Compounds 8e, 8h, and 8k were discovered to have estimated energy gaps (eV) of 3.181, 4.034, and 3.539 eV, respectively. Triazole 8h exhibited the lowest chemical hardness (1.962 eV) and the highest chemical softness (0.252 eV), which also suggests that it is more reactive than all the other compounds under study. Moreover, these scaffolds physicochemical characteristics, filtration molecular properties, assessment of toxicity, and bioactivity scores were assessed in relation to ADME (absorption, distribution, metabolism, and excretion). In conclusion, we discovered a novel benzoxazinone linked 1,2,3-triazoles with promising antimicrobial and anticancer activity and a favorable pharmacokinetic profile.

Curcuminoid Chalcones: Synthesis and Biological Activity against the Human Colon Carcinoma (Caco-2) Cell Line.

There are many current scientific reports on the synthesis of various derivatives modelled on the structure of known small-molecular and natural bioactive compounds. Curcuminoid chalcones are an innovative class of compounds with significant therapeutic potential against various diseases and they perfectly fit into the current trends in the search for new biologically active substances. The aim of this study was to design and synthesise a series of curcuminoid chalcones. The objective of this scientific paper was to synthesise twelve curcuminoid chalcones and confirm their structures using spectral methods. Additionally, the biological activity of three of the synthesised compounds was evaluated using various assays, and their anticancer properties and toxicity were studied. The proposed derivatives were obtained via the Claisen-Schmidt reaction of selected acetophenones and aldehydes in various conditions using both classical methods: the solutions and solvent-free microwave (MW) or ultrasound (US) variants. The most optimal synthetic method for the selected curcuminoid chalcones was the classical Claisen-Schmidt condensation in an alkaline (NaOH) medium. Spectral methods were used to confirm the structures of the compounds. The resazurin reduction assay, caspase-3 activity assay, and RT-qPCR method were performed, followed by measurements of the intracellular reactive oxygen species (ROS) level and the lactate dehydrogenase (LDH) release level. Twelve designed curcuminoid chalcones were successfully synthesized and structurally confirmed by NMR, MS, and IR spectroscopy. Examination of the anticancer activity was carried out for the three most interesting chalcone products. The results suggested that compound 3a increased the metabolism and/or proliferation of the human colon carcinoma (Caco-2) cell line, while compounds 3b and 3f showed significant toxicity against the Caco-2 cell line. Overall, the preliminary results suggested that compound 3b exhibited the most favourable anticancer activity.

Characterization of Monosubstituted Benzene Ices

Aromatic structures are fundamental for key biological molecules such as RNA and metabolites and the abundances of aromatic molecules on young planets are therefore of high interest. Recent detections of benzonitrile and other aromatic compounds in interstellar clouds and comets have revealed a rich aromatic astrochemistry. In the cold phases of star and planet formation, most of these aromatic molecules are likely to reside in icy grain mantles, where they could be observed through IR spectroscopy. We present laboratory IR spectra of benzene and four monosubstituted benzene molecules—toluene, phenol, benzonitrile, and benzaldehyde—to determine their IR ice absorbances in undiluted aromatic ices, and in mixtures with water and CO. We also characterize the aromatic ice desorption rates, and extract binding energies and respective pre-exponential factors using temperature-programmed desorption experiments. We use these to predict at which protostellar and protoplanetary disk temperatures these molecules sublimate into the gas phase. We find that benzene and monosubstituted benzene derivatives are low-volatility with binding energies in the 5220–8390 K (43–70 kJ mol−1) range, which suggests that most of the chemistry of benzene and of functionalized aromatic molecules is to be expected to occur in the ice phase during star and planet formation.

The influence of functional groups on the pyrolysis of per- and polyfluoroalkyl substances

Thermal treatment is a widely used remediation strategy for PFAS-contaminated materials such as soil, spent sorbents, and domestic waste. To better understand the effectiveness and environmental impact of thermal treatments for PFAS-contaminated materials, a fundamental understanding of PFAS thermal degradation mechanisms is required. This work aims to study the pyrolysis of six representative PFAS compounds, all of which have an eight-carbon length but with different functional groups. To assess the thermal stability and pyrolysis products of these six PFAS compounds, evolved gas analysis (EGA) was performed using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) coupled with an infrared spectrometer (IR) and a mass spectrometer (MS), as well as pyrolysis-GCMS (Pyr-GCMS). The EGA data demonstrates that compounds with lower estimated vapor pressures were generally found to be more thermally labile, and the presence of an ionic bond necessitates higher temperatures for pyrolysis. Pyrolysis at 900 °C yielded a variety of fluorinated organic compounds at significant signals. Tetrafluoroethene constituted the majority of the Pyr-GCMS signal for all the compounds. Moreover, a significant fraction of detected products was unable to be identified, underscoring a need for better tools to help with the identification of unknowns. Pyrolysis can occur through random chain scission, scission of the functional group, scission of the terminal CF3 group, and HF elimination. Some compounds may undergo more complete beta-scission to produce smaller pyrolysis products compared to others. The presence of acidic protons within the functional group can help facilitate HF elimination, whereas the salt form of a PFAS compound is less likely to undergo HF elimination. Termination of radical intermediates can either be recombination with a CF3 radical or hydrogen abstraction (H-abstraction). Observed hydrogen-substituted products indicate that functional groups with higher hydrocarbon character may lead to more H-abstraction terminated products. Overall findings show that the functional group of a PFAS may decrease or increase its thermal stability and lead to different profiles of pyrolysis products.

The infrared spectrum of the protic ionic liquid 1-methylimidazolium nitrate: An ab initio molecular dynamics simulation study

Complex features observed in the infrared (IR) spectrum of the protic ionic liquid 1-methylimidazolium nitrate, [C1im][NO3], are assigned using ab initio molecular dynamics (AIMD) simulation. AIMD is used at the same level of theory to simulate the known X-ray crystal structure of [C1im][NO3] and a cluster of ionic pairs representing the liquid phase. The calculation of several single particle and collective time correlation functions of velocity forms the basis for the AIMD simulation assignment of the infrared spectra. The AIMD simulation demonstrates that the lift of the degeneracy of the anion asymmetric stretching mode, νas(NO3), due to symmetry breaking and coupling to external modes result in multiple band splitting in the crystal spectrum in the region of the νas(NO3) mode. Owing of the intrinsic anharmonic characteristic of the AIMD simulation, the calculation accounts for the broad band in the high-frequency range of the IR spectrum caused by the cation ν(NH) stretching mode in strong cation–anion hydrogen bond. The AIMD simulation of the liquid captures spectral changes upon melting of [C1im][NO3] due to loosening of the NH···O hydrogen bond and changes in the [NO3]- interaction with other hydrogen atoms of the imidazolium ring. The AIMD simulation assigns the intermolecular stretching mode of the hydrogen bond, ν(NH…O), as the band at 183 cm−1 in the far infrared spectrum of the [C1im][NO3] crystal.

Identification of cigarettes with different grades by using FTIR microspectroscopy

In this paper, FTIR microspectroscopy was used to identify the cigarettes of three different grades such as Jinwan cigarettes (J group), Yinxiangyipin cigarettes (Y group) and Hongsanhuan cigarettes (H group). IR spectra and peak-area ratios (A2923 /A816, A1601 /A2923, A1601/A920 and A1072/A816) revealed significant differences among H, Y and J groups, reflecting the changes in chemical compositions with increased grade. Discriminant analysis was carried out on basis of the above peak-area ratios, achieving 100% accuracy for identification of H, Y and J groups. Principal component analysis (PCA) showed that carbohydrates and proteins were closely related to the quality of the cigarettes. In addition, curve fitting further confirmed that the structure of carbohydrates underwent changes due to the quality of the cigarettes. The above results suggest that FTIR microspectroscopy can identify different grades of the cigarettes, which may be helpful for tobacco research.

Insight into the Structural Optimization and Electrical Conductivity of NiII/MnII Bipyridine–Dicyanamide Complexes

AbstractTwo monomeric octahedral complexes {[Ni(N(CN)2)2(bpy)2]2·H2O (1) and [Mn(N(CN)2)2(bpy)2] (2) where bpy = 2,2′‐bipyridine} were synthesized and characterized by single crystal X‐ray diffraction, elemental analysis, UV–visible, and IR spectra. The geometry optimization through DFT measurements predicts that both the complexes have similar monomeric structures with hexa‐coordinated metal centers having a couple of bpy and mononegative dca anions and thus satisfying the octahedral geometry. Moreover, it is found that the HOMO–LUMO energy gaps are ΔE = 4.981 and 5.563 eV for complexes 1 and 2, respectively, which are responsible for the stabilization of the complex formation. The calculated absorption bands are located at 304 and 235 nm, which are in excellent agreement with the experimental result. Moreover, the DFT study of the electronic spectra of both complexes shows that the calculated absorption bands are in well agreement with the experimental results. In the electrical studies, direct current (dc) measurements on the copper/complex (1 or 2)/copper structure confirm a definite development in the device current with applied bias. Complex 1 has shown better electrical conductance compared to complex 2 based on the reduction of device resistance.

Exploring deep eutectic solvents of methane sulfonic acid and choline chloride: Formation, properties, and metal solvent effectiveness

Methane sulfonic acid (MSA), a hydrogen bond donor (HBD), was combined with choline chloride (HBA) at varying molar ratios (1:1, 1:2 and 2:1) to explore the formation of deep eutectic solvents (DES). The resulting blends, at 1:1 and 2:1 ratio, remained liquid at ambient temperature. Among these combinations, the DES formed with a 1:1 M ratio (MSA-ChCl) exhibited the highest decomposition temperature (166 °C) followed by MSA-ChCl (1:2) and MSA-ChCl (2:1). Alongside, the glass transition temperature of the DES also remained relatively unaffected by the molar ratio of its components. Notably, both density and viscosity were observed to be temperature dependent. To elucidate hydrogen bonding interactions between choline chloride and MSA, Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy were employed. The broadening and shifting of IR peaks illustrate the formation of intermolecular bonding between MSA and ChCl. Density Functional Theory (DFT) calculations were conducted to optimise molecular structures, analyse HOMO-LUMO levels, estimate electronegativity and ionization potential, and generate electrostatic potential surfaces of the DES. As per calculated Molecular Electrostatic Potential (MEP) by DFT of pure MSA and ChCl, SO of MSA has most electron deficient region and it has potential to interact with electron positive part of OH part of ChCl, which is also demonstrated by IR spectra. MSA-ChCl (2:1) displayed the most negative electron density and proved to be the most effective metal solvent among the DES formulations tested. Exceptional solubility of lithium in MSA-ChCl (2:1) was observed, exceeding 105 mg/L. Moreover, zinc, copper, cobalt, and iron also demonstrated good solubility in MSA-ChCl (2:1), ranging from 105 to 104 mg/L.

The optimization of sample preparation on zebrafish larvae in vibrational spectroscopy imaging

The zebrafish (Danio rerio) larvae are widely used in biomedical, pharmaceutical, and ecotoxicological studies. Their transparency and translational potential make them particularly valuable for fluorescence imaging. In addition to fluorescence imaging, microspectroscopy, which combines vibrational spectroscopy: Raman or Fourier transform infrared (FT-IR) with microscopy, allows the collection of spatially resolved, label-free information. According to available literature, it was the first application of FT-IR imaging in zebrafish larvae.This study aims to compare different fixation methods for 10-day post-fertilization (dpf) zebrafish larvae using vibrational spectroscopy imaging. Paraformaldehyde (PFA), glutaraldehyde (GA), low temperature, and embedding in gelatin and agarose were investigated. Amides, lipids, and phosphates distribution were more informative in embedded samples but with challenging handling of the sample due to stiffness at −20 °C. FT-IR and Raman mapping revealed that frozen samples had better-preserved tissue structure than chemical fixation. PFA showed uniform amide distribution, while GA treatment exhibited tissue disruptions and denser protein networks in both. Handling of embedded samples is challenging for an operator, but provides more reliable results in developmental biology or disease modeling, compared to chemical treatment.

Effect of alkyl chains on the structural and optical properties of nH6BiN orthoconic antiferroelectric liquid crystals: Insights from DFT calculations

This research presents a detailed computational study of a homologous series of orthoconic antiferroelectric liquid crystalline compounds, nH6BiN (where n = 1 to 6), employing Density Functional Theory (DFT) with the B3LYP functional and 6-311G(d,p) basis set. We optimized the molecular geometry and used it as an input file for analyzing thermodynamic properties, vibrational spectroscopy, and evaluating non-linear optical (NLO) properties to investigate the impact of terminal chain length on these compounds. The electronic structure analysis, including HOMO-LUMO gap and reactivity parameters, indicated consistent electronic properties across the series. Raman spectroscopy confirmed structural regularity, with characteristic vibrational modes. Notably, non-linear optical properties enhanced with chain length, as evidenced by increasing dipole moments, polarizabilities, and hyperpolarizabilities. The results highlight the influence of terminal chain length on the structural, electronic, and optical properties of the nH6BiN compounds, providing valuable insights for material design. This comprehensive study provides insights into the influence of terminal chain length on the molecular properties of the nH6BiN series, offering a foundation for their potential application in advanced material science.

Antiproliferative Activity of an Organometallic Sn(IV) Coordination Compound Based on 1-Methylbenzotriazole against Human Cancer Cell Lines

A motivating class of compounds with interest in the research field of biological active metallopharmaceuticals for cancer treatment is based on organometallic complexes of Sn(IV), exhibiting advantages such as improved cellular uptake and body excretion, lower toxicity, and fewer side effects compared to platinum-based drugs. In this study, the mononuclear organotin coordination complex [(CH3)2SnCl2(mebta)2] was synthesized and characterized using vibrational spectroscopy (IR, Raman), 1H NMR, 13C{1H} NMR, and X-ray crystallography. Its antiproliferative properties were thoroughly assessed across an aggressive triple-negative human breast cancer cell line. Notably, comparative studies with precursor materials verified that the observed biological activity is intrinsic to the complex itself. This study highlights the compound’s ability to induce cell fate by disrupting essential cellular functions, such as proliferation. By exploring the antiproliferative effects of organotin(IV) derivatives, we introduce a novel class of Sn complexes with 1-methylbenzotriazole (mebta), demonstrating significant potential as promising antitumor agents in the field of organotin compounds.

Synergistic effect of graphene oxide and silica nanocomposites towards multifunctional biomedical applications

The development of advanced nanomaterials (NMs) has recently gained significant attention because of their potential in addressing various biomedical and healthcare challenges. This study focuses on the synthesis of silica (SiO2) nanoparticles (NPs) and their nanocomposite with graphene oxide (GO-SiO2), using a multifunctional approach to enhance antibacterial, antibiofilm, antioxidant, and antidiabetic properties. The synthesis of the GO-SiO2 involves the controlled growth of SiO2 NPs on the surface of the graphene oxide (GO) sheets. The synthesized NPs were characterized by UV–Visible spectroscopy, Fourier-Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) Spectroscopy. The crystallite sizes of SiO2 and GO-SiO2 were found to be 23.07 nm and 32.07 nm, respectively, by XRD analysis and 27.03 nm and 43.11 nm, respectively, by SEM. The Band gap of SiO2 was decreased from 3.76eV to 3.45eV in GO-SiO2. Disc diffusion method was used to perform antibacterial activity whereas ampicillin and moxifloxacin were taken as reference drugs. Biofilm inhibitions and minimum inhibitory concentrations were measured by microtiter plate method. The composite has shown higher antimicrobial activities against S. aureus, S. aureus MDR, K. pneumoniae, P. aeruginosa, P. aeruginosa MDR, E. coli, and P. vulgaris as compared to SiO2 NPs and GO. When IC50 values were compared with those of control (acarbose), GO-SiO2 and SiO2 demonstrated the highest and lowest antidiabetic activities, respectively. A 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging process was used to evaluate the antioxidant potential of NMs using ascorbic acid as a reference. GO-SiO2 displayed the negligible IC50 value compared to both SiO2 and GO. The nanocomposite (GO-SiO2) has shown higher antibacterial, antibiofilm, antioxidant, and antidiabetic potential as compared to those of GO and SiO2NPs.

A new approach to assess post-mortem interval: A machine learning-assisted label-free ATR-FTIR analysis of human vitreous humor

A crucial issue in forensics is determining the post-mortem interval (PMI), the time between death and the finding of a body. Despite various methods already employed for its estimation, only approximate values are currently achievable. Vitreous humor (VH) is an avascular tissue between the lens and the retina, mainly composed by a collagen fibers network, hyaluronic acid, and hyalocytes. Recently, it has received interest in forensic medicine, being easy to collect and susceptible to low microbiological contamination and putrefaction. Based on this evidence and thanks to the ability of Attenuated Total Reflectance – Fourier Transform InfraRed (ATR–FTIR) spectroscopy to perform fast analyses on a minimal sample amount, in this study, a new analytical approach to reliably estimate PMI is proposed combining ATR-FTIR analysis of VH human samples with multivariate statistical procedures, such as Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA), for discriminant classification. Regression procedures, including Partial Least Squares Regression (PLSR), were performed: extremely positive results were obtained, and the most discriminant spectral features were highlighted (peaks at 1665, 1630, 1585, 1400, 1220, 1200, 1120, 854, 835, and 740 cm−1) and associated to PMI classes (average accuracy over 80 %). Specific and reliable markers able to correlate the macromolecular composition of VH with the PMI were identified, revealing a post-mortem protein degradation and amino acids deamination (decrease of proteins and increase of free amino acids and NH3), an increase of lactate, which diffuses from the retina to the VH, and changes in the hyaluronic acid component.

Enhanced CO2 Electroreduction to ethylene on Cu nanocube coated with nitrogen-doped carbon shell in-situ electro-derived from metal-organic framework

Electrochemical CO2 reduction reaction (CO2RR) to ethylene is one of the most promising technologies to achieve efficient use of carbon resources and sustainable development, in which the development of an efficient and stable electrocatalyst is particularly important. In this work, we develop a catalyst in situ electro-derived from Cu-based MOF for CO2RR to ethylene. We prepared nano Cu-MOF by microwave synthesis and supported it on a Cu foil substrate as a working electrode (denoted as MOF/Cu foil). During in situ electrolysis, Cu-MOF was converted into a highly dispersed nitrogen-doped carbon-coated Cu nanocube (denoted as Cu-cube/CN), which inhibited particle agglomeration and enhanced active site exposure. At a potential of −1.15 V vs. RHE, the Faradaic efficiency (FE) of the Cu-cube/CN catalyst for ethylene is 49.6 %, significantly higher than that of the original Cu foil electrode and Cu-MOF supported on the gas diffusion layer (GDL) prepared working electrode (denoted as MOF/GDL). In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations studies indicate that due to the electron-donating ability of the CN coating, the adsorption of *CO is enhanced, increasing the *CO coverage, lowering the reaction free energy of *CO dimerization, promoting C-C coupling and ethylene generation. This work provides new insights for the development of efficient and stable electrocatalysts for CO2RR-to-ethylene production.

Kinetic analysis of coal oxidative pyrolysis before and after immersion effect

The oxidative pyrolysis kinetics of coal before and after immersion effect was studied by thermogravimetric experiments. Non-isothermal thermogravimetric analysis data were analyzed at four heating rates of 5, 10, 20 and 30 K/min. Furthermore, temperature-programmed experiments and Fourier-transform infrared (FTIR) spectroscopy were employed to understand the oxidation activity and chemical structure of raw coal and soaked coal. After coal immersion effect, the increase in the content of active functional groups, the increase in the concentration of gaseous products, and the decrease in crossing point temperature during oxidation process all indicate that soaked coal is easier to oxidize and spontaneously combust. Lastly, four model-free methods such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods are employed to calculate the activation energy (Eα). Kinetic analysis reveals that Eα value obtained by the former three methods significantly depends on the conversion of coal oxidative pyrolysis process, and the average Eα value of soaked coal obtained by four methods is lower than that of raw coal. For the kinetic analysis of coal oxygen adsorption and combustion stages, it is more reliable to adopt the FWO and KAS methods in turn. This research helps to better understand the mechanism of enhanced oxidation activity of soaked coal and optimizes the calculation method of kinetic parameters in different oxidation stages of coal.

Assessment of submicron bone tissue composition in plastic-embedded samples using optical photothermal infrared (O-PTIR) spectral imaging and machine learning

Understanding the composition of bone tissue at the submicron level is crucial to elucidate factors contributing to bone disease and fragility. Here, we introduce a novel approach utilizing optical photothermal infrared (O-PTIR) spectroscopy and imaging coupled with machine learning analysis to assess bone tissue composition at 500 nm spatial resolution. This approach was used to evaluate thick bone samples embedded in typical poly(methyl methacrylate) (PMMA) blocks, eliminating the need for cumbersome thin sectioning. We demonstrate the utility of O-PTIR imaging to assess the distribution of bone tissue mineral and protein, as well as to explore the structure-composition relationship surrounding microporosity at a spatial resolution unattainable by conventional infrared imaging modalities. Using bone samples from wildtype (WT) mice and from a mouse model of osteogenesis imperfecta (OIM), we further showcase the application of O-PTIR spectroscopy to quantify mineral content, crystallinity, and carbonate content in spatially defined regions across the cortical bone. Notably, we show that machine learning analysis using support vector machine (SVM) was successful in identifying bone phenotypes (typical in WT, fragile in OIM) based on input of spectral data, with over 86% of samples correctly identified when using the collagen spectral range. Our findings highlight the potential of O-PTIR spectroscopy and imaging as valuable tools for exploring bone submicron composition.