Fourier Transform Infrared Absorption Research Articles

Structure and Stability of Charge-Coupled Lanthanide-Substituted Ca10(PO4)6F2 as a Potential Fluoride Bearing Nuclear Waste Form.

The structure and stability of charge-coupled lanthanide-substituted Ca10(PO4)6F2 as a potential fluoride-bearing nuclear waste form for the back-end fuel cycle of Gen-IV molten salt reactor have been studied in detail. Here, calcium fluorapatite (CaFAp) as a model structure was taken for incorporation of trivalent lanthanides (Lns, La-Lu except Pm) in a charge-coupled fashion, i.e., 2Ca2+ = Na+ + Ln3+. In these fluorapatite phases, Na+ is substituted exclusively at nine coordinated sites, Ca1, while Ln3+ is preferentially substituted at seven coordinated sites, Ca2. These compositions are further characterized for the local structure by Fourier transform infrared (FTIR) and Raman spectroscopy. Thermal expansion was measured by high-temperature X-ray diffraction (XRD) and the instantaneous thermal expansion coefficient correlates well with the unsubstituted CaFAp. The heat capacities of these solids were measured by differential scanning calorimetry and drop calorimetry, whereas enthalpies of formation were obtained by high-temperature oxide melt solution calorimetry. The thermodynamic analysis demonstrated that lanthanides having ionic radii closure to Ca2+ (Sm3+ and Gd3+) imparted higher thermodynamic stability to the substituted CaFAp as compared to that of other Ln3+. According to structural and thermodynamic investigations, entropy-stabilized fluorapatite waste from NaPr0.125Nd0.125Sm0.125Eu0.125Gd0.125Tb0.125Dy0.125Ho0.125Ca8(PO4)6F2 (WF-Ln) was successfully synthesized for the first time. Furthermore, electron beam irradiation studies probed by XRD, FTIR, Raman, and X-ray absorption (XAS) spectroscopy implied the radiation resistance nature of this substituted CaFAps up to 20 MGy.

Highly efficient uranium uptake by the eco-designed cocamidopropyl betaine-decorated Na-P1 coal fly-ash zeolite

In some locations around the globe, the U concentrations may exceed WHO standards by 2-folds therefore, effective yet environmentally wise solutions to purify radioactive waters are of significant importance. Here, the optimized and fully controlled coal-fly-ash based Na-P1 zeolite functionalization by employing novel, biodegradable biosurfactant molecule - cocamidopropyl betaine (CAPB) is showcased. The zeolite’s surface decoration renders three composites with varying amounts of introduced CAPB molecule (Na-P1 @ CAPB), with 0.44, 0.88, and 1.59-times External Cation Exchange Capacity (ECEC). Wet-chemistry experiments revealed extremely high U adsorption capacity (qmax = 137.1 mg U/g) unveiling preferential interactions of uranyl dimers with CAPB molecules coupled with ion-exchange between Na+ ions. Multimodal spectroscopic analyses, including Fourier-Transformed Infra-Red (FT-IR), X-ray Photoelectron (XPS), and X-ray Absorption Fine Structure (XAFS), showed the hexavalent oxidation state of U, and no secondary release of the CAPB molecule from the composite. The EXAFS signals fingerprint changes in the interatomic distances of adsorbed U, showing the impact of the O and N, heteroatoms present in the CAPB molecule on U binding mechanism. The presented research outcomes showcase the easy, scalable, optimized, and environmentally friendly synthesis of biofunctional zeolite effectively purifying the real-life U-bearing wastewaters from the vicinity of the Pribram deposit (Czech Republic).

Selenium loaded sodium alginate/polyvinyl alcohol nanocomposite film as wound dressing: structural, optical, mechanical, antimicrobial properties and biocompatibility

In the current research, synthesized Se-NPs were loaded into sodium alginate/polyvinyl alcohol SA/PVA blend, 1:2 (w:w), with different proportions to form nanocomposite films by using the solution casting method. The main goal is to enhance the physical and antibacterial properties of the polymer blend; therefore, it can be utilized for wound dressing applications. The physical aspects of the prepared films were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), atomic force microscope (AFM), scanning electron microscope (SEM), Energy dispersive X-ray (EDX), UV–Vis spectroscopic technique, and mechanical analysis to show the effect of increasing the concentration of Se-NPs from zero to 0.5 wt% on their properties. Regarding the XRD analysis, the calculated values of lattice strain (ε\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varepsilon$$\\end{document}) increased from 0.005 to 0.013. The FTIR absorption spectrum recorded an intensity reduction and position shift in the main characteristic peaks of SA/PVA. The morphology of Se-NPs revealed a spherical shape with a mean diameter of 131.76 nm, as revealed by transmission electron microscopy (TEM). The surface morphological images showed the appearance of a few cracks; besides, the average roughness increased from 1.59 to 2.08 nm. According to the UV–Vis spectroscopic analysis, the optical band gap reduces (from 5.425 to 5.216 eV) for the direct transition and from (5.07–4.78 eV) for the indirect transition, which is an indication of the interaction between Se-NPs and SA/PVA blend. Young’s modulus, tensile strength, and yield strength of the films increased with the addition of selenium nanoparticles. On the other hand, the amount of selenium release significantly increased with enhancing the concentration of Se-NPs in SA/PVA blend film from 0.1 to 0.5 wt%. Additionally, the inclusion of Se-NPs supplied the polymer blend with excellent antimicrobial activity, which would remove the possibility of microbial infection at the wound site. Moreover, the prepared SA/PVA/Se nanocomposite films have good biocompatibility with Human Skin Fibroblast (HSF). The results suggest the potential of this nanocomposite to be used in wound dressing applications.

Wound Dressing Based on Cassava Silk-Chitosan.

The application prospects of composite sponges with antibacterial and drug-carrying functions in the field of medical tissue engineering are extensive. A solution of cassava silk fibroin (CSF) was prepared with Ca(NO3)2 as a solvent, which was then combined with chitosan (CS) to create a sponge-porous material by freeze-drying. The CSF-CS composite sponge with a mesh structure was successfully fabricated through hydrogen bonding. Scanning electron microscopy (SEM), Fourier transform infrared absorption (FTIR) and X-ray diffraction (XRD) were employed to investigate the appearance and structure of the cassava silk's fibroin materials, specifically examining the impact of different mass percentages of CS on the sponge's structure. The swelling rate and mechanical properties of the CSF-CS sponge were analyzed, along with its antibacterial properties. Furthermore, by incorporating ibuprofen as a model drug into these loaded sponges, their potential efficacy as efficient drug delivery systems was demonstrated. The results indicate that the CSF-CS sponge possesses a three-dimensional porous structure with over 70% porosity and an expansion rate exceeding 400% while also exhibiting good resistance against pressure. Moreover, it exhibits excellent drug-carrying ability and exerts significant bacteriostatic effects on Escherichia coli. Overall, these findings support considering the CSF-CS composite sponge as a viable candidate for use in drug delivery systems or wound dressings.

Synergistic effects of nano curcumin mediated photodynamic inactivation and nano-silver@colistin against Pseudomonas aeruginosa biofilms

BackgroundPatients with burn injuries colonized by multidrug-resistant Pseudomonas aeruginosa face increased mortality risk. The efficacy of colistin, a last-resort treatment, is declining as resistance levels rise. P. aeruginosa's robust biofilm exacerbates antibiotic resistance. Photodynamic Inactivation (PDI) shows promise in fighting biofilm. Materials and methodsNano curcumin (nCur) particles were synthesized, and their chemical characteristics were determined using zeta potential (ZP), dynamic light scattering analysis (DLS), energy-dispersive X-ray (EDX) analysis, and fourier transform infrared (FTIR). We conducted an MTT assay to assess the cytotoxicity of nCur-mediated PDI in combination with nanosilver colistin. The fractional biofilm inhibitory concentration (FBIC) of two P. aeruginosa clinical isolates and P. aeruginosa ATCC 27853 during nCur-mediated PDI@AgNPs@CL was determined using a 3-dimensional (3-D) checkerboard assay. To study the effect of nCur-mediated PDI@AgNPs@CL on lasI, lasR, rhlI, rhlR, pelA, and pslA gene expression, Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was conducted at each isolate's FBIC. The impact of treatments was also investigated using scanning electron microscopy (SEM). ResultsThe ZP and mean DLS values of the nCur were 10.3 mV and 402.6 ± 24.6 nm, respectively. The distinct functional groups of nCur corresponded with the peaks of FTIR absorption. Moreover, the EDX analysis showed the ratios of different metals in nCur. Cell viability percentages of nCur-mediated PDI@AgNPs@CL at FBIC concentrations of clinical isolates Nos. 30, 354, and P. aeruginosa ATCC 27853 were 91.36 %, 83.20 %, and 92.48 %, respectively. nCur-mediated PDI@AgNPs@CL treatment showed synergistic effects in clinical isolates and P. aeruginosa ATCC 27853 in a 3-D checkerboard assay. All six of the investigated genes showed down-regulation after nCur-mediated PDI@AgNPs@CL treatment. The most suppressed gene during nCur-mediated PDI@AgNPs@CL treatment was the rhlR gene (-11.9-fold) of P. aeruginosa ATCC 27853. The SEM micrographs further proved the connecting cement reduction and biofilm mass mitigation following nCur-mediated PDI@AgNPs@CL treatments. ConclusionsThe combined effect of nCur-mediated PDI and AgNPs@CL synergistically reduce the formation of biofilm in P. aeruginosa. This may be attributable to the suppression of the genes responsible for regulating the production of biofilms.

First principles approach and experimental exploration of a new double perovskite phase Sr2(In0.33 Sn0.33Sb0.33)2O6: evaluation of structural, optical, and dielectric properties.

A new double perovskite phase, Sr2(Sn0.33Sb0.33In0.33)2O6, was successfully synthesized via a solid-state reaction and comprehensively characterized using both experimental and theoretical techniques. Powder X-ray diffraction was used to determine the crystal structure, while scanning electron microscopy (SEM) revealed a high degree of densification and uniform grain distribution across the ceramic. Raman and Fourier-transform infrared (FTIR) absorption spectra of the powder present broad bands predominantly due to different stretching modes of the various SnO3 2-, InO3 2- and SbO3 2- octahedra in the region ν = 400-800 cm-1. An analysis of the UV-Vis diffuse reflectance spectrum shows excellent optical transparency and gives an estimation of an optical gap E g ∼ 3.6 eV on bulk Sr2(Sn0.33Sb0.33In0.33)2O6, making this material a promising candidate for optoelectronic devices. Density Functional Theory calculations further validated the experimental findings, confirming the crystal structure and providing insight into the electronic and vibrational properties. Impedance spectroscopy revealed non-Debye dielectric relaxation and confirmed typical negative temperature coefficient of resistance (NTCR) behavior, underscoring the material's potential for temperature-sensing applications. The primary conduction mechanism, modeled as correlated barrier-hopping (CBH), was complemented by an Arrhenius-type process with activation energies of 0.33 eV and 0.9 eV across two distinct temperature ranges.

Fabrication of superhydrophobic cauliflower-like Cu[sbnd]Co coating with anti-corrosion and anti-fouling properties on B10 copper–nickel alloy welded joint

A superhydrophobic CuCo coating is successfully applied to the surface of a B10 copper–nickel (CuNi) alloy welded joint via electrodeposition and modification using a low-surface-energy material (stearic acid). The static water contact angle is measured to be 162.2 ± 1°, and the roll off angle is 2.1°. Various techniques, including scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared absorption spectroscopy are employed to characterize the chemical composition and phase structure of the samples before and after electrodeposition and modification. The corrosion resistance of the superhydrophobic samples is evaluated via electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning Kelvin probe microelectrochemistry. The results indicate that the superhydrophobic coating exhibits greater charge transfer resistance, lower self-corrosion current density, and higher surface work function, thus effectively enhancing the corrosion resistance of the B10 CuNi alloy welded joint. Furthermore, the micro-nano rough structure with low surface energy on the superhydrophobic sample surface traps air and forms an air layer, thereby reducing the contact between the corrosive medium and welded joint as well as minimizing corrosion. The superhydrophobic coating demonstrate thermal stability as well as excellent self-cleaning and mechanical properties, based on comprehensive testing and analysis.

Graphite Separation in Sunflower Oil and a Possible Food Monitoring Sensor via Near-infrared Spectroscopy

Introduction: As a quick and non-destructive testing method, Fourier transform infrared (FTIR) spectroscopy has become more popular for identifying food adulteration, manipulation, and deception. Sunflower oil is a widely used food item that may be contaminated or even adulterated with potentially harmful chemical substances associated with health issues. Methods: In this regard, this study was carried out to examine the applicability of near- and midinfrared spectroscopy to identify modifications in the pure sunflower oil and sunflower oil dispersed with graphite. The dispersion of graphite powder in sunflower oil was achieved using the ultrasonic technique. The samples were analyzed using FTIR spectroscopy and transmission electron microscopy. Results: Changes in the FTIR signal were observed, indicating changes in the hydrogen atoms distribution within the solution. The flattened peak at 3470 cm-1 was associated with the overtone of glyceride ester carbonyl absorption compared to pure SO. Additionally, the stretching vibration of carbonyl groups of triglyceride esters occurred as a significant absorption band at 1754 cm-1, and the FTIR absorption at 1447 cm-1 was absent. Transmission electron microscopy (TEM) analysis showed transparent layers of graphene sandwiched with sunflower oil with a distinct flake-like shape Conclusion: These findings support dispersed graphite in sunflower oil to check the food quality.

Predicting the physical and chemical properties of sustainable aviation fuels using elastic-net-regularized linear models based on extended-wavelength FTIR spectra

A Fourier transform infrared (FTIR) spectra-based prescreening approach was developed for estimating nine important physical and chemical properties of sustainable aviation fuels (SAFs): molecular weight (MW), hydrogen-to-carbon (H/C) ratio, density, net heat of combustion (NHC), derived cetane number (DCN), threshold sooting index (TSI), initial boiling point (IBP), flash point, and kinematic viscosity (KV). A training dataset containing the vapor-phase FTIR absorption spectra of pure hydrocarbons spanning four molecular classes, blends of neat hydrocarbons, conventional jet fuels and SAFs, across the 2–15.38 μm wavelength range, was compiled. The physical and chemical properties of the fuels in the training dataset were sourced either from experimental data reported in the literature or calculated using relevant property blending correlations. Elastic-net-regularized linear models were trained for each property by optimizing the model parameters using a cross-validated grid search. The results from these models were compared with the results from previous models (Lasso-regularized linear models developed previously by Wang et al. at Stanford), which were trained on FTIR absorption spectra across the limited wavelength range of 3.3–3.55 μm. Use of the extended wavelength range and the new model-parameter optimization strategy results in significant improvement in predictive performance of the current models compared to the previous models for all nine properties. The model performance is also evaluated on three candidate SAFs. The current models are found to achieve higher property prediction accuracy than the previous models for these test fuels. Overall, this work demonstrates the utility of predictive models based on extended-wavelength FTIR spectra and their potential use as a low-volume prescreening method for characterizing properties of new sustainable aviation fuel candidates.

Formulation, Characterization, and Optimization of a Topical Gel Containing Tranexamic Acid to Prevent Superficial Bleeding: In Vivo and In Vitro Evaluations.

Tranexamic acid (TXA) is used systemically to stop bleeding, but it can lead to thromboembolism. Trials have revealed the efficacy of topical TXA on local hemorrhages. However, there is a need for an efficient delivery system that can keep the drug at the site of action. To develop a gel containing TXA (3%) optimized in terms of viscosity and dispersibility, the central composite design based on two factors-three levels [carbopol 940 and hydroxypropyl methylcellulose (HPMC), 1-1.5% and 1-2%, respectively] was applied. The spreadability and viscosity were assessed using glass slide and rheometer, respectively. To confirm the compatibility of TXA with the gel, fourier transform-infrared (FTIR) spectroscopy was performed. Drug content uniformity was analyzed by a spectroscopy method. An ex vivo mice model using Franz cells was applied to evaluate the permeation of TXA through the skin. To investigate the effect of topical TXA gel on bleeding time, IVY human method was performed. HPMC/carbopol 940 (1:1, w/w) gel showed the highest quality in terms of viscosity and dispersibility (3.982 ± 17.6 and 6.052 ± 3.562, respectively). FTIR absorption spectrum showed that all the TXA index peaks appeared without displacement. The complete-encapsulated TXA content was uniformly dispersed throughout the gel. In vitro TXA cumulative release reached 90% in 4 h. The bleeding time determined in vivo for TXA gel was significantly lower than that for TXA solution and control. The results confirm the importance of further studies on this formulation as a potential medication to stop acute superficial bleeding.

Deciphering the anticancer, anti-inflammatory and antioxidant potential of Ti nanoparticles fabricated using Zingiber officinale

Rapid and sustainable green technology was implemented in the current study to fabricated Ti nanoparticles. The vegetable ginger with the scientific name Zingiber officinale was employed as a biological source in the fabrication process of nanoparticles. The optical, structural, morphological, and particle size of the fabricated Ti nanoparticles were characterized with the help of UV–visible absorption spectrum, FTIR (Fourier Transform Infrared) spectrum, SEM (Scanning Electron Microscope) analysis, DLS (Dynamic Light Scattering) technique and XRD (X-ray powder diffraction) crystallography technique. The presence of spherical-shaped Ti nanoparticles with an average particle size of 93 nm was confirmed based on these characterization techniques. The anti-cancer properties of the Z. officinale mediated Ti nanoparticles were analyzed through MTT assay against cell lines MCF-7 (Human breast adenocarcinoma cell line) and concentration-dependent anti-cancer properties were observed. The anti-inflammatory capacity of the Z. officinale mediated Ti nanoparticles were examined through protein denaturation and nitric oxide scavenging assay. The antioxidant capacity of the Z. officinale mediated Ti nanoparticles were examined through DPPH assay, hydrogen peroxide radical scavenging assay, hydroxyl radical scavenging assay, and FRAP (Ferric Reducing Antioxidant Power) analysis. The fabricated Ti nanoparticles exhibited anti-inflammatory and antioxidant capacity in a concentration-dependent pattern.

Conformation-dependent molecular association and spectral properties of 4-pentyl-4′-cyanobiphenyl liquid crystal in different phases

The 4-pentyl-4′-cyanobiphenyl (5CB) molecule conformation and structure alignment have been investigated by means of temperature variable Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy in a wide temperature range (from −90 to 50 °C) covering the 5CB glass-like, metastable and stable crystalline, nematic and isotropic phases defined by differential scanning calorimetry measurements. The corresponding FTIR absorption and PL emission bands reflect a strong dipolar association and a formation of at least two types of 5CB dimeric structures with antiparallel or parallel orientation in the planar configuration. No formation of hydrogen bonds between the cyano groups and hydrogen atoms of the adjacent benzene ring has been found. Besides, a small amount of the 5CB monomer structure has been shown to be present in all phases. The observed temperature-induced changes in the IR and PL spectra can be used as an independent source of experimental information on conformational equilibria and structure alignment of 5CB in different states under the phase transitions.

Crystal Structure, Raman, FTIR, UV-Vis Absorption, Photoluminescence Spectroscopy, TG-DSC and Dielectric Properties of New Semiorganic Crystals of 2-Methylbenzimidazolium Perchlorate.

Single crystals of 2-methylbenzimidazolium perchlorate were prepared for the first time with a slow evaporation method from an aqueous solution of a mixture of 2-methylbenzimidazole (MBI) crystals and perchloric acid HClO4. The crystal structure was determined by single crystal X-ray diffraction (XRD) and confirmed by XRD of powder. Angle-resolved polarized Raman and Fourier-transform infrared (FTIR) absorption spectra of crystals consist of lines caused by molecular vibrations in MBI molecule and ClO4- tetrahedron in the region ν = 200-3500 cm-1 and lattice vibrations in the region of 0-200 cm-1. Both XRD and Raman spectroscopy show a protonation of MBI molecule in the crystal. An analysis of ultraviolet-visible (UV-Vis) absorption spectra gives an estimation of an optical gap Eg~3.9 eV in the crystals studied. Photoluminescence spectra of MBI-perchlorate crystals consist of a number of overlapping bands with the main maximum at Ephoton ≅ 2.0 eV. Thermogravimetry-differential scanning calorimetry (TG-DSC) revealed the presence of two first-order phase transitions with different temperature hysteresis at temperatures above room temperature. The higher temperature transition corresponds to the melting temperature. Both phase transitions are accompanied by a strong increase in the permittivity and conductivity, especially during melting, which is similar to the effect of an ionic liquid.

Investigation of Hydration States of Ionic Liquids by Fourier Transform Infrared Absorption Spectroscopy: Relevance to Stabilization of Protein Molecules.

Among many kinds of ionic liquids, some hydrated ionic liquids (Hy ILs) have shown an exceptional capability to stabilize protein molecules and maintain their structure and functions over a long period. However, the complex IL-water interaction among these protein-stabilizing Hy ILs has yet to be elucidated clearly. In this work, we investigate the origin of the compatibility of ionic liquid with proteins from the viewpoint of hydration structure. We systematically analyzed the hydrogen-bonding state of water molecules around ionic liquid using Fourier transform infrared absorption (FT-IR) spectroscopy. We found that the native hydrogen-bonding network of water remained relatively unperturbed in the protein-stabilizing ILs. We also observed that the protein-stabilizing ILs have a strong electric field interaction with the surrounding water molecules and this water-IL interaction did not disrupt the water-water hydrogen-bonding interaction. On the other hand, protein-denaturing ILs perturb the hydrogen-bonding network of the water molecules to a greater extent. Furthermore, the protein-denaturing ILs were found to have a weak electric field effect on the water molecules. We speculate that the direct hydrogen bonding of the ILs with water molecules and the strong electric field of the ions lasting several hydration shells while maintaining the relatively unperturbed hydrogen-bonding network of the water molecules play an essential role in protein stabilization.

Structural and nutritional properties of psyllium husk arabinoxylans with special reference to their antioxidant potential

ABSTRACT The current research aimed to extract and characterize arabinoxylans (AX) from psyllium seeds husk for their nutritional and structural properties. For this purpose, psyllium husk (PH) was procured from the local market and subjected for the nutritional profile, dietary fiber (DF) composition, and AXs extraction. The extraction of AXs from psyllium seed husk was done through enzymatic method and Fourier transform infrared (FTIR) spectroscopy was used for its structural characterization. Further, the antioxidant activity of AXs was also elucidated using ferric reducing antioxidant power (FRAP) and diphenyl picryl hydrazyl (DPPH) assays. Results showed that psyllium seed husk is a good source of DFs (61.5 ± 2.6%) and the proximate composition including moisture, ash, crude fat, crude protein, crude fibers, and Nitrogen free extract (NFE) was 4.9 ± 0.01, 4.1 ± 0.01, 1.2 ± 0.01, 3.9 ± 0.05, 20.23 ± 0.4 and 78.2 ± 4.01 g/100 g, respectively. Furthermore, AXs content was 68.29 ± 3.4 g/100 g of PH. Different monosaccharides including xylose, arabinose, rhamnose, glucose, and galactose contents in PHAXs were 64.23 ± 1.04%, 13.38 ± 0.16%, 1.43 ± 0.04%, 1.89 ± 0.05%, and 3.64 ± 0.07%, respectively. FTIR absorption peaks from 900 to 1100 cm−1 showed spectra of AXs with the highest peak from 980 to 1015 cm−1 reflecting arabinose and xylose ratio. Additionally, the substitution positions on the xylan backbone were 2800–3400 cm−1 of O-H stretching vibrations and peaks of C-H stretching at 2853 and 2923 cm−1. The antioxidant activity of PHAXs exhibited that the FRAP value of extracted AXs was 1.39 ± 0.06 μmol Fe2+/g and the DPPH value was 3.01 ± 0.15 Trolox mg/g. It is depicted that PH is a good source of AXs (non-starch polysaccharide) with better antioxidant potential.

Effect of Alkyl Chain Length on the Phase Situation of Glass-Forming Liquid Crystals

The phase behaviour of the latest synthesised compound belonging to a family of (S)-4′-(1-methyloctyloxycarbonyl) biphenyl-4-yl 4-[‘m’-(2,2,3,3,4,4,4-heptafluorobutoxy) ‘m’alkoxy]-benzoates (where ‘m’ means 3, 5 or 7 methylene groups) is described by polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction and Fourier-transform infrared absorption spectroscopy. It has been shown that as the length of the alkyl chain increases, a given liquid crystal possesses a greater number of mesophases and at a higher temperature it goes into the isotropic liquid phase. All examined compounds form a chiral smectic phase with antiferroelectric properties (SmCA* phase), in which the temperature range of occurrence increases with the length of the molecule. The number of methylene groups also affects the glass transition. The compound with the shortest alkyl chain (‘m’ = 3) is vitrified from the conformationally disordered crystal phase. For the compound with five -CH2- groups (‘m’ = 5), a glass transition from the monotropic high-order hexatic smectic SmXA* phase is observed. In the case of the liquid crystal with the longest carbon chain (‘m’ = 7), the vitrification from the less ordered SmCA* phase is visible. Differences in the crystallization kinetics, e.g., the nucleation-controlled mechanism for the compound with the shortest carbon chain vs. the complex phenomenon for its longer homologs, are discussed.

Investigation of thermal, mechanical and dielectrical properties of LiYO2 filled poly(lactic acid) nanocomposites

In recent years, the development of portable electronic devices has increased considerably. Polymers and polymer composites are employed in a variety of industries, from structural materials to electronics, as well as in our daily lives. PLA@LiYO2 nanocomposites films were subsequently fabricated by a simple solution casting at various concentrations for the development of electronic materials. The effective doping and homogeneous dispersion of nanoparticles in PLA polymer is characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FTIR) spectrophotometer, Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), elastic and dielectric properties of PLA composites films. XRD analysis showed that the crystalline characteristics of the nanocomposites increases with increase in dopant concentration. The FTIR absorption spectra of neat PLA and PLA@LiYO2 nanocomposites are almost equivalent to each other, from TGA analysis there will be less percentage of weight loss in the composite’s films as the concentration of the nanocomposites increased into PLA matrix, Moreover, a significant increase in Tg with an increase in NPs content from 0 to 4 wt% was also observed, the different elastic moduli such as E, K and G of PLA + LiYO2 films are indirectly proportional to the addition of LiYO2 in to PLA matrix. The doped PLA nanocomposites exhibit unique negative dielectric constant and AC conductivity.

Method to detect carbon in silicon crystals in the concentration range down to 5 × 1014 cm−3 by Fourier transform infrared absorption at room temperature

The procedure of Fourier transform infrared absorption (FT-IR) at room temperature for quantifying C impurities in Si crystals was reexamined to improve the detection limit down to 5 × 1014 cm−3. Since the substitutional C absorption peak overlaps with a strong two-phonon absorption, the difference spectroscopy is necessary with using a C-lean reference sample. A baseline flatness of less than 0.0005 in absorbance and a thickness uniformity of less than 0.001 mm are required to realize a detection limit of 5 × 1014 cm−3 for 2 mm thick samples. To check the flatness, we define the Si/Si baseline which is the difference in the absorbance spectra measured twice with the removal and attachment of the same Si sample. Four organizations participated in the FT-IR round-robin test for ten samples with the C concentration ranging from 3.6 × 1014 to 3.3 × 1015 cm−3. The obtained C concentrations were almost within 30% deviation from the values determined by reliable secondary ion mass spectroscopy.

A toolbox for easy entry low wavenumber in situ atomic layer deposition transmission FTIR spectroscopy studies.

A detailed description of a flexible and portable atomic layer deposition (ALD) system is presented for conducting in situ Fourier transform infrared (FTIR) absorption spectroscopy studies during the evolution and growth of ALD films. The system is directly integrated with a commercial FTIR spectrometer (Bruker Vertex 80V) to avoid the necessity of an external optical path to the instrument, thereby mitigating complexity and optical losses. In this work, we use potassium bromide (KBr) with a 5nm layer of sputtered Si as a substrate due to higher infrared transmittance when compared to a single-side polished Si wafer. The FTIR absorption study is conducted at normal incidence in transmission mode using a deuterated L-alanine doped triglycine sulfate (DTGS) detector owing to its potential applicability for reliable measurements at wavenumbers below ∼700cm-1. We demonstrate this by measuring ex situ the transverse optical phonon of bulk Al2O3 centered at 680cm-1. The integrity and functionality of the system to track the nucleation stage are validated by conducting in situ FTIR absorption measurements of Al2O3 using tri-methyl aluminum (TMA) and H2O. The measured IR absorption spectra for the Al2O3 growth after each cycle of TMA and H2O show the formation and removal of CH3 (2800-3000cm-1) groups on the substrate surface and CH4 (3016 and 1306cm-1) molecules in the reactor, thus confirming the successful tracking of ligand exchange. Thus, this instrument, together with the choice of KBr as substrate, can enable straightforward ALD nucleation studies using a DTGS detector having sufficient signal without additional optical setup and modifications to off-the-shelf FTIR systems that allow low wavenumber experiments.

Weighted LASSO variable selection for the analysis of FTIR spectra applied to the prediction of engine oil degradation

The aim of this work is to quantify the relationship between different methods of artificial oil alteration as well as engine oils collected from a passenger car using FTIR (Fourier-transform infrared) spectroscopic data and chemometric methods. We propose a comprehensive procedure for the analysis of FTIR spectra: First, a reconstruction error based pre-processing to filter non-informative variables is introduced, then simultaneous variable selection and parameter estimation using the (weighted) LASSO is performed. Eventually, post-selection inference is applied to derive confidence intervals for the selected model coefficients. The proposed pre-processing methods do not rely on manual selection of FTIR absorption bands suitable for analysis but perform filtering of non-informative variables objectively. With weighted LASSO, experts’ knowledge can be integrated with the model. This pipeline for the analysis of FTIR spectroscopic data is demonstrated and validated on a real-world dataset including series of FTIR spectra of used and artificially altered engine oils.