Fourier-transform Spectroscopy Research Articles

Oil-in-water Pickering emulsions with Buriti vegetable oil stabilized with cellulose nanofibrils: Preparation, stability and antimicrobial properties.

Mauritia flexuosa (Buriti) vegetable oil (OV) has attracted technological interest in various sectors, including pharmaceuticals, food, and beverages, because of its excellent antioxidant activity. The active OV components are fatty compounds, and stability is required for proper application. In this work, we investigated Pickering emulsions based on v in water stabilized by cellulose nanofibrils (CNF). CNF is sustainable, economically viable, and environmentally friendly, and it is suitable for developing products in an eco-friendly way. The factorial design of experiments (DoE) indicates that the amount of CNF and the homogenization time significantly affect the emulsion, preventing coalescence over 30 days. Fourier-transform Raman spectroscopy (FT-Raman) and Fourier-transform infrared spectroscopy (FTIR) show that CNF stabilizes the OV droplets through induced dipole-dipole interactions and hydrogen bonds. Rheological analysis was relevant to the relationship between internal microstructure strength and viscous flow behavior of the emulsions. A novel approach enabled the identification of the CNF stabilization mechanism in the emulsion system via fluorescence microscopy. Diameter distribution measurements and steady-state rheological tests indicate that the emulsions have good stability at room temperature and suitable steady-state viscosity for food applications and beverage products as they show pronounced shear thinning behavior for cream and lotion skin care products.

Gas-phase Conformational Landscape and Ring-puckered Structure of 1-aminoindane.

Indane-based molecules are effective scaffolds for different pharmaceutical products, so it is relevant to analyze the relation between structure and functionality in indane derivatives. Here, we have characterized the conformational landscape and molecular structure of 1-aminoindane in the gas phase using chirped-excitation Fourier-transform microwave spectroscopy and computational methods. The rotational spectrum confirmed the presence of two conformers, which were identified based on their rotational constants and 14N nuclear quadrupole coupling tensor elements. The observed conformers share the cyclopentane puckering and amino equatorial configuration but differ in the orientation of the amino group hydrogens. The spectral analysis further allowed the observation of all monosubstituted 13C and 15 N isotopologues in natural abundance for the most stable isomer, allowing a precise structural determination for this species. Structural information was derived using the substitution ( ) and effective vibrational ground state ( ) methods, revealing that the structure of 1-aminoindane is very similar to that of indane. A calculation of the potential energy surface along the pathway for the conversion between the most stable equatorial species permitted to rationalize the non-observation of additional conformers via molecular relaxation during the adiabatic expansion. The computational results include ab initio (MP2) and DFT methods (B3LYP, ωB97X-D and M06-2X).

The Effect of Zeolite Na-X and Clinoptilolite as Functional Fillers on the Mechanical, Thermal and Barrier Properties of Thermoplastic Polyurethane.

To obtain sustainable food packaging materials, alternatives to traditional ones must be researched. In this work, two different kinds of zeolites, i.e., a natural one, Clinoptilolite, and a synthetic one, Zeolite Na-X, were mixed with thermoplastic polyurethane for the fabrication of composites. Composite films were prepared via a hot mixing stage and then by means of a hot compression molding process. Several TPU/zeolite composites were produced with a filler concentration ranging from 5% to 10%wt. Finally, the obtained films were characterized by Fourier Transform Spectroscopy (FT-IR, ATR), thermal analysis (TGA and DSC), frequency sweep test, scanning electron microscopy (SEM), mechanical tensile test and oxygen permeability test. For both fillers and at all concentrations, the inclusion of zeolites significantly influenced the analyzed properties. In the TPU/zeolite composites, an overall enhancement was observed compared to the neat polymer, attributed to improved processability, superior barrier properties and the potential to create active materials by loading zeolite combined with various chemicals for specific applications. These findings suggest that the resulting composites hold considerable promise for applications in the food packaging sector.

Research and Application of Interferogram Acquisition Method for Ground-Based Fourier-Transform Infrared Greenhouse Gas Spectrometer

A high-performance data acquisition and processing system within a spectrometer provides a powerful guarantee for obtaining high-precision data in ground-based Fourier-transform infrared greenhouse-gas spectroscopy. Addressing the challenge of accurate interferogram sampling in Fourier-transform spectroscopy, a dual-channel interferogram acquisition method was designed. Dual-channel analog-to-digital converters, acquiring interferograms at different gains, enable high dynamic range and high-resolution acquisition of infrared interferometric signals; the analog-to-digital converter channel of low-gain interferograms mainly captures data near the zero-optical-range-difference spike, and the analog-to-digital converter channel of high-gain interferograms mainly acquires the weak signals from the two flanks. The simulation results, circuit design, and correction method between the two channels of the method are given. Finally, in the ground-based Fourier-transform infrared greenhouse-gas spectrometer for experimental applications, the experiment shows that under the same measurement conditions, the carbon dioxide column concentration-measurement accuracy is improved by 2.096 times, and the dual-channel interferometric data acquisition method can significantly enhance the data retrieval accuracy.

Broadband coherent Fourier scatterometry: A two-pulse approach.

We demonstrate a broadband implementation of coherent Fourier scatterometry (CFS) using a supercontinuum source. Spectral information can be resolved by splitting the incident field into two pulses with a variable delay and interfering them at the detector after interaction with the sample, bearing similarities with Fourier-transform spectroscopy. By varying the time delay between the pulses, a collection of diffraction patterns is captured in the Fourier plane, thereby obtaining an interferogram for every camera pixel. Spectrally resolved diffraction patterns can then be retrieved with a per-pixel Fourier transform as a function of the delay. We show the physical principle that motivates the two-pulse approach, the experimental realization, and results for a silicon line grating. The presented implementation using a supercontinuum source offers a cost-effective way to acquire multi-wavelength CFS data over a wide wavelength range, with the potential to improve reconstruction robustness and sensitivity in applications such as dimensional metrology.

Symmetric Non-Monochromatic Light as Reference in Fourier Transform Spectrometers.

Fourier transform spectrometers typically use a presumed monochromatic reference source to track and correct errors in optical path difference changes. This paper will conduct a theoretical analysis to show that non-monochromatic light sources with symmetric spectral profiles can also be used as reference sources without adding errors. An experiment was carried out using a symmetric broadband superluminescent diode (SLED) as reference light to measure the spectrum of some other SLED light sources to experimentally demonstrate this finding.

Investigation of Sn Promoter on Ni/CeO2 Catalysts for Enhanced Acetylene Semihydrogenation to Ethylene.

Ethylene, as an important chemical raw material, could be produced through the coal-based acetylene hydrogenation route. Nickel-based catalysts demonstrate significant activity in the semihydrogenation reaction of acetylene, but they encounter challenges related to catalyst deactivation and overhydrogenation. Herein, the effect of Sn promoter on Ni/CeO2 catalysts has been comprehensively explored for acetylene semihydrogenation. The optimized Ni/8%Sn-CeO2 catalytic performance was significantly improved, with 100% acetylene conversion and 82.5% ethylene selectivity at 250 °C, and the catalyst maintained high catalyst performance within a 1000 min stability test. A series of characterization tests show that CeO2 modified by moderate Sn4+ doping is more conducive to modulating the charge structure and geometry of the Ni active center. Additionally, the in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy and density functional theory results indicated that catalysts doped with Sn4+ facilitated more efficient desorption of ethylene from the catalyst surface compared to Ni/CeO2 catalysts, thus improving ethylene selectivity and yield. This study highlights an effective strategy for improving the catalytic performance of rare-earth-based catalysts through the incorporation of effective metal promoters.

In-situ analysis of methane plasmas with mid-infrared supercontinuum-based Fourier-transform spectroscopy

The conversion of methane (CH4) into the hydrocarbons ethane (C2H6) and acetylene (C2H2) in plasma is investigated in the first in-situ study using a mid-infrared supercontinuum source and a Fourier transform spectrometer. Due to the spatial coherence of the supercontinuum source, it is possible to probe the plasma over a path length of 3.5 m and observe CH4, C2H6, and C2H2 with concentrations below percent level at a few mbar pressure. The broad spectral range of the supercontinuum source (1.4–4.1 μm) covers entire rovibrational bands of molecules, allowing simultaneous detection of the rotational and vibrational temperature of CH4 and C2H2. The ability to study these experimental parameters in situ opens new possibilities for understanding and optimizing plasma-based chemical conversions.

Derivation of the carbon dioxide total column in the atmosphere from satellite-based infrared fourier-transform spectrometer IKFS–2 measurements: analysis and application experience

The paper discusses the use of a new version of the regression technique for derivation the total content of carbon dioxide in the atmosphere XCO2 (column-averaged dry-air mole fraction) from measurements of the infrared Fourier-transform spectrometer IKFS–2 installed on board Russian meteorological satellite Meteor-M No. 2. To evaluate the accuracy of satellite-based XCO2 estimates the retrospective comparison was made with data from ground-based spectroscopic measurements at Peterhof site of St. Petersburg State University as well as with aircraft measurements of the V. E. Zuev Institute of Atmospheric Optics (IOA) in the area of the Novosibirsk Reservoir conducted in 2019-2022. A brief description of the regression technique modifications is given made to improve the accuracy of satellite – based XCO2 estimates. In particular, to compensate for the effect of changes in the IKFS-2 characteristics during a long flight, the XCO2 estimates calibration is realized using ground - based XCO2 measurements at the NOAA Observatory on Mauna Loa volcano (island of Hawaii). After calibration and cloud scenes filtering, the discrepancy between satellite estimates and ground-based / aircraft measurements is characterized by root mean square deviation of ~4 ppm or 1% of the CO2 total content. In order to accelerate the adjustment of the regression technique, used for estimating XCO2, to IKFS-2 data on new satellites, it is reasonable to use XCO2 observations at the TCCON terrestrial network in addition to conventional contact measurements of CO2 concentrations. Along with this, it seems rational to use the cryogenic film thickness on the glass of the IKFS-2 photodetector, characterizing the state of the instrument, as additional predictor in the regression model.

Hydrogen Production from Formic Acid Using KIT-6 Supported Non-NobleMetal-Based Catalysts.

The aim of this study is to investigate the activity of KIT-6 supported nickel (Ni) and cobalt (Co) catalysts, and the effect of Co incorporation to the Ni@KIT-6 catalyst in the formic acid (FA) dehydrogenation. Ni and Co are inexpensive and readily available non-noble transition metals that are considered ideal for dehydrogenation reactions due to their high activity against C-C and C-H bond breaking. In this study, KIT-6 supported catalysts were tested for hydrogen production from FA in a conventionally heated packed-bed continuous-flow system. N2 adsorption-desorption isotherms of the samples were found to be consistent with Type-IV according to the International Union of Pure and Applied Chemistry (IUPAC) classification. The introduction of metal loading resulted in the preservation of the mesoporous structure of the support material. X-ray diffraction (XRD) patterns of the catalysts exhibited the characteristic amorphous silica structure. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) analysis, Lewis acidity of Co-based catalysts was found to be higher than the Ni-based catalysts. The complete formic acid conversion was observed at 200-350 °C. The highest H2 selectivity was obtained with the 3Ni@KIT-6 catalyst. The Co-based catalysts exhibited relatively lower catalytic activity, which was linked to increased coke formation within these catalysts.

Highly efficient CO2 capture on acid-treated sepiolite impregnated with mixed polyethyleneimine and diethanolamine

Highly efficient CO2 capture on acid-treated sepiolite impregnated with mixed polyethyleneimine and diethanolamine

Nondestructive Control of Macrolides in Tableted Pharmaceuticals Using Near-IR Fourier-Transform Spectrometry and Digital Colorimetry

Nondestructive Control of Macrolides in Tableted Pharmaceuticals Using Near-IR Fourier-Transform Spectrometry and Digital Colorimetry

Sodium cation exchanged zeolites for direct air capture of CO2

Sodium cation exchanged zeolites for direct air capture of CO2

Facile synthesis of CuCo2O4@CdS nanoheterostructure for asymmetric supercapacitor

Facile synthesis of CuCo2O4@CdS nanoheterostructure for asymmetric supercapacitor

Very low Ru loadings boosting performance of Ni-based dual-function materials during the integrated CO2 capture and methanation process

Very low Ru loadings boosting performance of Ni-based dual-function materials during the integrated CO2 capture and methanation process

Humic Substances from Waste-Based Fertilizers for Improved Soil Fertility

This research explores how different organic waste transformation methods influence the production of humic substances (HSs) and their impact on soil quality. Using olive and orange wastes as substrates, the study compares vermicomposting, composting, and anaerobic digestion processes to determine which method produces the most humic-substance-rich products. The characterization of HSs in each product included analyses of total organic carbon (TOC), humic and fulvic acid content, humification rate, humification degree, and E4/E6 ratio, with HSs extracted using potassium hydroxide (KOH) and analyzed via Diffuse Reflectance Infrared Fourier-Transform (DRIFT) spectroscopy to assess structural complexity. The results revealed that the chemical composition of the input materials significantly influenced the transformation dynamics, with orange by-products exhibiting a higher humification rate and degree. Vermicomposting emerged as the most efficient process, producing fertilizers with superior humic content, greater microbial biodiversity, and enhanced cation exchange capacity, thus markedly improving soil quality. Composting also contributed to the stabilization of organic matter, albeit less effectively than vermicomposting. Anaerobic digestion, by contrast, resulted in products with lower levels of HSs and reduced nutrient content. Aerobic processes, particularly vermicomposting, demonstrated the most rapid and effective transformation, producing structurally complex, stable humus-like substances with pronounced benefits for soil health. These findings underscore vermicomposting as the most sustainable and efficacious approach for generating HS-rich organic fertilizers, presenting a powerful alternative to synthetic fertilizers. Furthermore, this study highlights the potential of organic waste valorization to mitigate environmental pollution and foster circular economy practices in sustainable agriculture.

Enhancement of mechanical properties of natural rubber latex sheets by incorporating allyl-modified microcrystalline cellulose (AMCC)

Enhancement of mechanical properties of natural rubber latex sheets by incorporating allyl-modified microcrystalline cellulose (AMCC)

Role of Hydroxyl Groups in Zn-containing Nanosized MFI Zeolite for the Photocatalytic Oxidation of Methane.

The effective conversion of methane to a mixture of more valuable hydrocarbons and hydrogen under mild conditions is a significant scientific and practical challenge. Here, we synthesized Zn-containing nanosized MFI zeolite for direct oxidation of methane in the presence of H2O and air. The presence of the surface hydroxyl groups on nanosized MFI-type zeolite and their significant reduction in the Zn-containing nanosized MFI zeolite were confirmed with Infrared Fourier Transform (FTIR) spectroscopy. Incorporation of zinc atoms into the framework of nanosized MFI zeolite is revealed by Nuclear Magnetic Resonance, X-ray Diffraction and UV-Vis Spectroscopy. Unexpectedly, pure silica MFI zeolite exhibited the highest photocatalytic performance. Our findings demonstrated that large number of isolated silanol groups and silanol nests increase the formation of ⋅OH, and enhance the productivity of oxygenate compounds and C2H6, while the Zn incorporated into the zeolite framework or attached to the silanol nests of the nanosized zeolites are less efficient. A mechanism of photocatalytic methane oxidation is proposed. These findings provide insights into the development of active nanosized zeolite photocatalysts with an extended amount of surface hydroxyl groups that can play a key role in photocatalytic methane conversion.

Constructing organic-inorganic woven hybrid membrane for highly-selective catalytic conversion of lignin-based phenolic molecule to value-added products

Constructing organic-inorganic woven hybrid membrane for highly-selective catalytic conversion of lignin-based phenolic molecule to value-added products

Signal-to-Noise Ratio Analysis of Bandpass Sampling Time-Modulated Fourier Transform Spectroscopy

In Bandpass Sampling Fourier Transform Spectroscopy, a comprehensive method for evaluating signal-to-noise ratio (SNR) has not yet been established. This paper employs an energy conservation approach to analyze the relationship of SNR between interferogram and spectra in Bandpass Sampling Time-Modulated Fourier Transform Spectroscopy (BPS-FTS). It systematically presents models for the average SNR of the system interferogram and the average SNR of reconstructed spectra under different parameters. These models are compared with SNR models in traditional Fourier transform spectroscopy (FTS) and are mutually validated through theoretical modeling and simulation analysis. It provides a theoretical basis and simulation verification for the design and implementation of the system.