Fourier Transform Infrared Bands Research Articles

Synthesis and Characterization of Coenzyme Q10 onto Nanoporous Calcium Silicate-Based Systems for Wound Healing

This study explores the microstructure, spectroscopic, and bonding arrangements within bioactive calcium silicate and calcium magnesium silicate systems loaded with different values (1–2.5 wt%) Coenzyme (CoQ10) ratios, synthesized using sol-gel processes. The investigation utilizes X-ray diffraction (XRD), transmission electron microscopy, and Fourier transform infrared (FTIR) spectroscopy to analyze the samples. The study explores the assignment of FTIR bonds, examining changes in the silicate-based bonds environment under the effect of the CoQ10 ratio. The observed frequency shifts and intensity variations in FTIR bonds, linked with the bioactive silicate composition, are attributed to a reduction in local symmetry resulting from introducing the calcium and magnesium oxides and CoQ10 to the silica network. The XRD and FTIR results contribute valuable insights into the structural role of silicate-based materials loaded with CoQ10, thereby enhancing our understanding of the CoQ10 release process. Approval of the CoQ10 drug loading in both calcium silicate and calcium magnesium silicate nanosystems was recognized by shifts in FTIR bands, changes in particle distribution, and the valuation of drug release activity showed by the bioactive two calcium silicate-based nanoparticles. Additionally, wound healing studies revealed the biocompatibility and wound healing response of calcium magnesium silicate nanoparticles.

An investigation of the structural and optical properties of modified barium magnesium fluoroborate glasses with hafnium oxide (HfO2)

AbstractGlasses of nominal composition xHfO2–(35-x)B2O3–15MgF2–35BaO, where x ranged from 0 to 0.2 mol% were fabricated using a melt-quenching technique. Structural characterization techniques, including X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and Raman spectroscopy, were employed to elucidate the glass network structure. The XRD patterns confirmed the amorphous nature of the studied glasses, while the FTIR and Raman spectra revealed that the incorporation of HfO2 may led to a transformation of trigonal BO3 units to tetrahedral BO4 units in the borate glass network. Deconvolution analysis of the FTIR and Raman bands provided quantitative insights into the extent of this structural rearrangement as a function of HfO2 content. UV–Vis absorption studies demonstrated that the optical bandgap of the glasses was widened with increasing HfO2 additions. This blue shift in the absorption edge was attributed to the increased formation of bridging oxygen bonds and reduced non-bridging oxygen content in the glass network. The results indicate that the studied glasses exhibit excellent compositional tunability through the incorporation of HfO2. The structural modifications and concomitant optical property enhancements suggest the potential of this glass system for various integrated photonic applications where low phonon energy and tailored transparency are highly desirable. The present work introduces a comprehensive investigation of the structural and optical property modifications in barium magnesium fluoroborate glasses induced by the addition of hafnium oxide (HfO2).

Mechanistic study of the differences in lactic acid bacteria resistance to freeze- or spray-drying and storage

Lactobacillus delbrueckii subsp. bulgaricus and Lactiplantibacillus plantarum are two lactic acid bacteria (LAB) widely used in the food industry. The objective of this work was to assess the resistance of these bacteria to freeze- and spray-drying and study the mechanisms involved in their loss of activity. The culturability and acidifying activity were measured to determine the specific acidifying activity, while membrane integrity was studied by flow cytometry. The glass transitions temperature and the water activity of the dried bacterial suspensions were also determined. Fourier transform infrared (FTIR) micro-spectroscopy was used to study the biochemical composition of cells in an aqueous environment. All experiments were performed after freezing, drying and storage at 4, 23 and 37 °C. The results showed that Lb. bulgaricus CFL1 was sensitive to osmotic, mechanical, and thermal stresses, while Lpb. plantarum WCFS1 tolerated better the first two types of stress but was more sensitive to thermal stress. Moreover, FTIR results suggested that the sensitivity of Lb. bulgaricus CFL1 to freeze-drying could be attributed to membrane and cell wall degradation, whereas changes in nucleic acids and proteins would be responsible of heat inactivation of both strains associated with spray-drying. According to the activation energy values (47–85 kJ/mol), the functionality loss during storage is a chemically limited reaction. Still, the physical properties of the glassy matrix played a fundamental role in the rates of loss of activity and showed that a glass transition temperature 40 °C above the storage temperature is needed to reach good preservation during storage.Key points• Specific FTIR bands are proposed as markers of osmotic, mechanic and thermal stress• Lb. bulgaricus CFL1 was sensitive to all three stresses, Lpb. plantarum WCFS1 to thermal stress only• Activation energy revealed chemically limited reactions ruled the activity loss in storageGraphical abstract

Electrolytic performance of sodium alginate-poly vinyl alcohol matrix with ammonium bromide for proton conduction: Applications in electrochemical systems

Polymer blend electrolytes based on poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared using the solution casting method. These electrolytes were doped with varying amounts of ammonium bromide (NH4Br). The compatibility of NH4Br with PVA:NaAlg polymers was examined through X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) studies. The FTIR assessment confirmed the formation of a complex between PVA:NaAlg and the added salt, as evidenced by modifications and reductions in the intensity of FTIR bands related to functional groups. The conductivity and dielectric behavior of the samples were analyzed using AC impedance spectroscopy. The sample with 20 wt% of added salt exhibited a higher ionic conductivity of 1.661×10−5 Scm−1. Activation energy and relaxation time were estimated, and dielectric studies revealed a non-Debye nature. The conduction mechanism was best described by the correlated overlapping large polaron tunneling model (OLPT). The highest conducting sample was found to be suitable for electrochemical devices, as demonstrated by transference number (TNM), cyclic volumetric (CV), and linear sweep voltammetry (LSV) analyses. This high-conductivity sample can be employed in electrochemical devices such as EDLC. The cyclic voltammetry (CV) curve exhibited a nearly rectangular shape with non-faradaic peaks. GCD(Galvanostatic charge-discharge) analysis yielded specific capacitance, power density, and energy density values of 125.01 Fg−1, 1037 WKg−1, and 14.06 WhKg−1 respectively. These results indicate that polymer electrolytes show great promise as electrolytes in proton-conducting electrochemical devices.

Green synthesis of zinc oxide nanoparticles from Salvadora persica leaf extract: Characterization and studying methyl orange removal by adsorption

Abstract The present study conducted a successful green synthesis of zinc oxide nanoparticles (ZnO NPs) from the aqueous solution of Salvadora persica leaf extract as capping agent and used for methyl orange dye removal. The morphology, chemical composition, crystallinity, optical property and isothermal behavior of synthesized nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy (UV-Vis). The influencing factors on MO removal such as preparation method, dose, pH, contact time, and dye concentration were examined. The UV-Vis absorption band was found at 365 nm and the XRD analysis confirmed the crystallinity of the ZnO NP and the particle sizes were in the range of 32-68 nm. The FTIR bands confirm the presence of bioactive compounds. SEM images showed the formation of hexagonal and rod-shaped nanoparticles. The results revealed that a maximum methyl orange removal of 68% was obtained with an amount of 0.05 g of ZnO NPs at pH 5. The adsorption process can be well explained by the Langmuir isotherm model. This research demonstrates a green method of preparing various ZnO nanoparticle with a remarkable efficiency towards the removal of methyl orange dye.

Diagnosis of common intraosseous lesions of the dentomaxillofacial region by chemometry-assisted FT-IR spectroscopy in dental tissue samples

PurposesThis study aimed to determine the differential diagnosis of three intraosseous lesions (odontogenic keratocyst (OKC), central giant cell granuloma (CGCG), and dentigerous cyst (DC)) of the dentomaxillofacial region with very similar radiological and clinical features by using chemometrics assisted FT-IR (Fourier transform infrared) spectroscopy in tissue samples. MethodsTissue samples (exposed to formaldehyde for a similar time) of 20-micron thickness belonging to 19 intraosseous lesions diagnosed histopathologically were obtained from the pathology laboratory. The samples were analyzed by FT-IR spectroscopic method using the 400–4000 cm−1 wavenumber range, and the obtained spectra of the samples were evaluated using the orthogonal partial least squares discriminant analysis (OPLS-DA) algorithm. ResultsThe intraosseous lesions with different histopathological diagnoses were accurately and precisely clustered with different FT-IR bands corresponding to the main molecular vibrations, especially the phosphodiester region, of the tissue components using the proposed model with 3 latent variables. ConclusionsThe model showed high sensitivity and specificity. The present study is the first to report the elucidation of clear spectral differences between similar lesions in the maxillofacial region. In the future, the FT-IR method may be used in the non-destructive classification of similar lesions in the maxillofacial region as an alternative to histopathological evaluation.

Characterization and spectroscopic investigations of zinc alumino lithium borate glasses doped with TiO2

Spectral investigations of TiO2 doped zinc alumino lithium borate glasses have been reported in this paper. The prepared glasses are characterized by using Fourier Transform Infra Red (FTIR).FTIR bands are observed at around 480 cm−1 is ascribed to metal ion-oxygen in the molecular structure. The XRD pattern confirms a broad diffuse scattering at different angles instead of crystalline peaks (absence of Bragg Peaks), which reflect the characteristics of amorphous glass structure.

Novel formulation for co-delivery of cinnamon- and cumin-loaded polymeric nanoparticles to enhance their oral bioavailability

Nanobiotechnology has been an encouraging approach to improving the efficacy of hydrophobic bioactive compounds. The biologically active constituents present in herbal extracts are poorly absorbed, resulting in loss of bioavailability and efficacy. Hence, herbal medicine and nanotechnology are combined to overcome these limitations. The surface-to-volume ratio of nanoparticles is high and as the size is small, the functional properties are enhanced. The present study reports the synthesis of cinnamon and cumin (Ci–Cu) dual drug-loaded poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) to overcome the limitations of oral bioavailability and extend the effect of these drugs for alleviating health problems. The solvent evaporation method was adopted for the synthesis, and the as-prepared nanoparticles were characterized by Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The average size of the formed spherical Ci-Cu nanoparticles ranged between 90 and 120 nm. The encapsulation efficiency of the drug was found to be 79% ± 4.5%. XRD analysis demonstrated that cinnamon and cumin were amorphously scattered in the PLGA matrix. The FTIR bands showed no evident changes suggesting the no direct molecular interactions between the drug and the polymer. At pH 6.9, the release studies in vitro exhibited a burst initially followed by a tendency to obtain a slower steady release. The results indicated that the Cu-Ci dual drug-loaded polymeric NPs has drug release at a slower rate. The time taken for 25% release of drug in Ci-Cu-loaded PLGA NPs was twice as compared to cumin-loaded PLGA Nps, and three times compared to cinnamon-loaded PLGA NPs.

Application of γ-cyclodextrin-lysozyme as host materials for encapsulation of curcumin: characterization, stability, and controlled release properties.

In this study, a safe and relatively stable γ-cyclodextrin-lysozyme (γ-CD-Lys) was synthesized using epichlorohydrin as the cross-linking agent, and curcumin was successfully encapsulated in γ-CD-Lys. The successful Lys grafting onto γ-CD can be demonstrated by a high grafting ratio (79.02%) and was further confirmed by Fourier transform infrared (FTIR) band shifts and the new signal obtained at δ 2.75 in proton nuclear magnetic resonance. The encapsulation efficiency value of γ-CD-Lys was 76.74%, and the successful encapsulation of curcumin into γ-CD-Lys was confirmed by crystal structure change, increased melting point, and FTIR band shifts. The intermolecular bonds results suggested that associative forces between curcumin and γ-CD-Lys were electrostatic interaction, hydrogen bonds interaction, and hydrophobic interaction. The designed nanoparticles had excellent stability at low pH and low salt concentration. The release rate of these nanoparticles was inhibited in simulated gastric conditions, whereas it increased significantly in intestinal media. Simulated gastrointestinal digestion experiments further confirmed that nanoparticles showed higher bioaccessibility (86.05%) compared with curcumin (58.82%). Overall, our study showed that the nanoparticles were highly promising for delivering curcumin because of their enhanced functional attributes and stabilization in acid or low salt environments. Also, it was an excellent wall material for targeting hydrophobic bioactive compounds in the intestinal tract via oral administration. © 2022 Society of Chemical Industry.

Principal Component Analysis of FTIR Data to Accurately Assess the Real/Equivalent In‐Service‐Times of Homogenous Solid Propellant

AbstractThis study was devoted to setting up new methodologies for an accurate assessment of both real and equivalent in‐service‐times (RIST/EIST) of homogenous solid propellants (HSP) through a combination of principal component analysis (PCA) and Fourier transform infrared (FTIR) spectroscopy. Four double‐base rocket propellants (DBRP) have been artificially aged at T=338.65 K for 4 months with sampling every 20 days. FTIR showed that the homolytic scission of the O‐NO2 bonds and the hydrocarbon chains of the nitrate esters are the main processes occurring during the chemical decomposition. The scatter plot from PCA of FTIR spectra shows that over 93 % of the variance was described by the first principal component. Moreover, the loading plot designated the three characteristic FTIR bands from the nitro (NO2) group as the most influenced by aging. A new PCA/FTIR experimental way was set to accurately assess the RIST of HSPs. The relative deviation associated with the RIST evaluated by the present procedure and those from the PCA/VST experimental way, recently developed, was found to range from 4.0 % to 6.7 %. Subsequently, a PCA/FTIR prediction model of the EIST is established. The predictions present a relative deviation of less than 7.1 % compared to the recent PCA/VST model. The accuracy of the model was further confirmed using similar DBRPs artificially aged for 6, 8, 10, and 12 months. The relative variation between the RIST provided by the PCA/FTIR procedure and the prediction model was found less than 5 %, thus confirming the highest accuracy of such combination.

Structure of allophanes with varied Si/Al molar ratios and implications to their differentiation on Mars

Allophane occurs ubiquitously in soils of volcanic origin on Earth and is also a probable constituent on martian surface, serving as a natural adsorbent and/or an environmental indicator. It remains to be one of the few minerals whose structure has not been unequivocally defined, as a result of its ultrasmall particle size, extremely low structural order and highly variable Si/Al molar ratios. To gain insights into the structure and probably also the formation processes of allophane, we hydrothermally synthesized allophanes at varied initial Si/Al molar ratios (0.5, 0.57, 0.66, 0.75, and 1.0), followed by characterizing their structure using a combination of advanced techniques. X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectra, and 27Al/29Si magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectra show that bayerite was obtained at initial Si/Al molar ratios of 0.5 and 0.57. FTIR and 29Si/27Al MAS NMR spectra also suggest the presence of oligomeric silicates in all the products and the significant amount of AlIV occurring invariably in both natural and synthetic allophanes is located in these oligomeric silicates. A possible explanation for the presence of oligomeric silicates is that the formation of imogolite local structure (ImoLS, which constitutes the skeleton of allophane) and the attachment of oligomeric silicates to it occur simultaneously. The scanning transmission electron microscopy (STEM) and atomic force microscopy (AFM) images showed that these products exhibited different aggregation states, probably resulting from formation of byproducts such as bayerite and proto-allophanes. The visible and near-infrared (VNIR) spectra exhibited little obvious differences resulting from Si/Al molar ratios, indicative of the weakness of this technique in detecting the geochemistry of Al and Si in poorly ordered aluminosilicate components at Mars' surface. Instead, the significant increases of intensity ratios observed in the FTIR bands (1043 cm−1 / 972 cm−1) and the 27Al/29Si MAS NMR signals (60 ppm / 7.6 ppm and (−80 ppm − −110 ppm) / −79 ppm, respectively) with increase of the Si/Al molar ratio of allophane indicate FTIR and MAS NMR could be used in combination with VNIR on future Mars orbiters/rovers.

Identification of metal-sensitive structural changes in the Ca2+-binding photocomplex from Thermochromatium tepidum by isotope-edited vibrational spectroscopy.

Calcium ions play a dual role in expanding the spectral diversity and structural stability of photocomplexes from several Ca2+-requiring purple sulfur phototrophic bacteria. Here, metal-sensitive structural changes in the isotopically labeled light-harvesting 1 reaction center (LH1-RC) complexes from the thermophilic purple sulfur bacterium Thermochromatium (Tch.) tepidum were investigated by perfusion-induced attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The ATR-FTIR difference spectra induced by exchanges between native Ca2+ and exogenous Ba2+ exhibited interconvertible structural and/or conformational changes in the metal binding sites at the LH1 C-terminal region. Most of the characteristic Ba2+/Ca2+ difference bands were detected even when only Ca ions were removed from the LH1-RC complexes, strongly indicating the pivotal roles of Ca2+ in maintaining the LH1-RC structure of Tch. tepidum. Upon 15N-, 13C- or 2H-labeling, the LH1-RC complexes exhibited characteristic 15N/14N-, 13C/12C-, or 2H/1H-isotopic shifts for the Ba2+/Ca2+ difference bands. Some of the 15N/14N or 13C/12C bands were also sensitive to further 2H-labelings. Given the band frequencies and their isotopic shifts along with the structural information of the Tch. tepidum LH1-RC complexes, metal-sensitive FTIR bands were tentatively identified to the vibrational modes of the polypeptide main chains and side chains comprising the metal binding sites. Furthermore, important new IR marker bands highly sensitive to the LH1 BChl a conformation in the Ca2+-bound states were revealed based on both ATR-FTIR and near-infrared Raman analyses. The present approach provides valuable insights concerning the dynamic equilibrium between the Ca2+- and Ba2+-bound states statically resolved by x-ray crystallography.

Synthesis and Spectroscopic Characterization of Co-Crystals of Fluconazole with Succinic Acid and Urea as Coformer

Co-crystal engineering is an important aspect of pharmaceutical development as it enables the obtainment of structural varieties of drug forms of same active pharmaceutical compounds while maintaining or improving physico-chemical and therapeutic activities of the active pharmaceutical compounds. In this work, we report the green synthesis of two co-crystals of fluconazole with succinic acid and urea. White block single crystals were obtained after slow evaporation of ethanolic solution of fluconazole (FLU) with the coformers (succinic acid and urea) in 1:1 molar ratio and were characterized using UV and Fourier Transform Infrared (FTIR) spectroscopy. FTIR spectra of the co-crystals confirms the formation of the co-crystals in solid state with the appearance of diagnostic FTIR bands of both fluconazole functional groups and those of the coformers (succinic acid and urea) in succinic acid-fluconazole (SFLU) and urea-fluconazole (UFU) respectively. UV-Vis spectra also features the π-π* absorption maxima of fluconazole in the co-crystals, providing additional evidence for the formation of the co-crystals.

Magnetic characteristics and FTIR bands of cerium doped perovskite-type (Ba0.5Sr0.5)(Fe1-xCex)O3-δ (x = 0 – 1.0) oxides

Doped perovskite-type oxides have diversified applications in sensors, inorganic membranes, piezoelectricity, and solid oxide fuel cells. An attempt has been made here to synthesize (Ba0·5Sr0.5)(Fe1-xCex)O3-δ (x = 0 – 1.0) powders by decomposition of sol-gel derived oxalate at 750–950 °C for 5 h to study the effect of cerium insertion with regard to Fourier transform infrared (FTIR) bands and magnetic characteristics. It is shown that the coercivity (Hc) increases from ∼ 83.4 to 1985 Oe and saturation magnetization decreases from ∼ 0.146 to 0.041 emu/g as structure changes from cubic (x = 0) to orthorhombic (x = 1.0). The law of saturation approximation (LAS) agrees well with observed saturation magnetization. The transition temperatures are found to be ∼ 500, 370, and 370.12 K for x = 0, 0.6, and 1.0, respectively. High coercivity (∼ 1985 Oe) and hysteresis in (Ba0·5Sr0.5)CeO3-δ (x = 1.0) arise due to the presence of oxygen vacancies and structural distortion. FTIR spectra show different types of bands related to the iron and/or cerium-oxygen (i.e., Fe/Ce - O) stretching vibrations. The redshift has been observed with cerium in (Ba0·5Sr0.5)(Fe1-xCex)O3-δ. These properties make them useful in magnetic recording and storage applications.

Design of plasticized proton conducting Chitosan:Dextran based biopolymer blend electrolytes for EDLC application: Structural, impedance and electrochemical studies

In this work, for the use of an electrical double-layer capacitor (EDLC) device applications, the fabrication and characterization of solid polymer electrolytes (SPEs) based on chitosan-dextran (CS-DN) blended polymer doped and plasticized with ammonium thiocyanate (NH 4 SCN) and glycerol are studied, respectively. The Fourier transform infrared (FTIR) spectroscopy method has been used to investigate the structural behavior of electrolytes. It was observed that the FTIR bands are shifted and decreased in their intensities with the increased glycerol plasticizer content and it results in the complex formation. According to the electrical impedance spectra (EIS), the electrolyte incorporated with high contents of plasticizer (42 wt%) revealed the highest ionic conductivity of (3.08 × 10 −4 S/cm). The electrical equivalent circuits (EEC) were used to investigate the circuit elements of the electrolytes further. Increasing glycerol plasticizers verified an improvement in ions density number (n), mobility (μ), and diffusion coefficient (D). The transference number measurements (TNM) indicated that the predominant charge carriers in the conduction process are ions where the ( t ion ) is 0.95. According to the linear sweep voltammetry (LSV) study, the uppermost conducting sample was found to have sufficient anode stability with a breakdown voltage of 1.9 V that can be used in electrochemical devices. The absence of peaks in the cyclic voltammetry (CV) demonstrated that the charge storage mechanism within the constructed EDLC is fully capacitive. Based on this finding, the starting specific capacitance ( C s ), energy density ( E d ), and power density ( P d ) have been identified to be 118F/g, 13.2 Wh/kg, and 1560 W/kg, respectively. Throughout its 100 cycles, the equivalence series resistance ESR value was between 53 and 117 Ω.

Influence of physical and chemical modifications on granule size frequency distribution, fourier transform infrared (FTIR) spectra and adsorption isotherms of starch from four yam (Dioscorea spp.) cultivars.

In this work, the effect of the modifications (annealing, acid hydrolysis and citric acid substitution) on starch granule size frequency distribution, Fourier Transform Infrared (FTIR) spectra, and adsorption isotherm of starches of four yam cultivars were studied. The native and modified white yam, water yam, and yellow yam starches had a normal distribution frequency profile for the granule sizes, which were similar among the cultivars. In contrast, the native and modified bitter yam starch granules were not normally distributed. The modifications resulted in a left shift in normal distribution frequency profiles for the granules sizes of the white, water and yellow yam starches due to broadening of the range of granule sizes. The FTIR spectra revealed that additional bands at 1726.95-1729.49cm-1 were introduced due to citric acid modification of the yam starches. The modifications also caused weakening of the FTIR band representing -CH2 and -OH stretching at 2927.85-2932.94cm-1 and 3259.42-3437.33cm-1, respectively. The native, annealed and acid hydrolyzed yam starches all had similar adsorption isotherms at 28°C. On the other hand, the citric acid-substituted yam starches showed a different adsorption isotherm, because they had significantly higher equilibrium moisture content at water activity (a w ) above 0.9. All the adsorption isotherms were type III, J-shaped isotherms. The adsorption isotherms data of the yam starches fitted best to the Guggenheim-Anderson-De Boer (GAB) model. The GAB model monomolecular moisture content ranged between 0.0165 and 0.0597g/g db. Native and modified yam starches' granules size were normally distributed except bitter yam starchFTIR revealed additional bands and molecular rearrangements were introduced due to modificationsAdsorption isotherms revealed type III, GAB-model isotherms with low monomolecular moisture. The online version contains supplementary material available at 10.1007/s13197-021-05200-7.

The effect of hydrogen-bonding on flavin’s infrared absorption spectrum

Cluster and continuum solvation computational models are employed to model the effect of hydrogen bonding interactions on the vibrational modes of lumiflavin. Calculated spectra were compared to experimental Fourier-transform infrared (FTIR) spectra in the diagnostic 1450–1800 cm−1 range, where intense νC=C, νC=N, νC2=O, and νC4=O stretching modes of flavin’s isoalloxazine ring are found. Local mode analysis is used to describe the strength of hydrogen-bonding in cluster models. The computations indicate that νC=C and νC=N mode frequencies are relatively insensitive to intermolecular interactions while the νC2=O and νC4=Omodes are sensitive to direct (and also indirect for νC2=O) hydrogen-bonding interactions. Although flavin is neutral, basis sets without the diffuse functions provide incorrect relative frequencies and intensities. The 6-31+G* basis set is found to be adequate for this system, and there is limited benefit to considering larger basis sets. Calculated vibrational mode frequencies agree with experimentally determined frequencies in solution when cluster models with multiple water molecules are used. Accurate simulation of relative FTIR band intensities, on the other hand, requires a continuum (or possibly quantum mechanical/molecular mechanical) model that accounts for long-range electrostatic effects. Finally, an experimental peak at ca. 1624 cm−1 that is typically assigned to the νC2=O vibrational stretching mode has a complicated shape that suggests multiple underlying contributions. Our calculations show that this band has contributions from both the C6–C7 and C2 = O stretching vibrations.

FTIR Analysis of Nanomodified Cement Concrete Incorporating Nano Silica and Waste Marble Dust

In present study, different compositions of concrete mixes with marble dust and nano-silica have been prepared and studied with Fourier Transform Infrared (FTIR) spectroscopy to evaluate different phases formed during hydration reaction. Formation and extent of phases formed during hydration reaction occurring for different curing days can be successfully correlated with the shifting of FTIR bands in various concrete samples. FTIR results demonstrate the shifting in peaks in presence of marble dust and nano-silica as compared to control mix. Decrease in intensity of Raman bands at 1636 and 3400-3650 cm−1with curing time was observed due to hydration of C3S and C2S. The bands observed at 1475 and 890 cm-1also shift towards lower wave number side 1450-1460 cm−1with increasing nano-silica content. These peaks are correlated with extent of carbonation which gets decreased in the presence of nano-silica. In addition to this, bands corresponding to ettringite, monosulphate and C-S-H molecules at 1180, 1120 and 980 cm−1 also shift towards lower number side with increase in concentration of nano-silica and marble dust.

Homogeneous-like Alkyne Selective Hydrogenation Catalyzed by Cationic Nickel Confined in Zeolite

The selective hydrogenation of alkynes to their corresponding alkenes is an important type of organic transformation, which is currently accomplished by modified palladium catalysts. Herein, we rep...

English

In the current investigation, chitin and chitosan are extracted from Callinectes amnicola (crab) and Penaeus notialis (shrimp) shell wastes using predetermined optimization conditions. The shrimp shell produces higher chitin yield (26.08%), higher chitosan yield (16.93%) and higher degree of deacetylation (DDA) of 89.73% than the yields of chitin (19.36%), chitosan (13.29%) and the DDA from crab shell (84.20%). The Fourier Transform Infrared (FTIR) and acid-base titration methods are used to obtain % DDA of the optimized chitosan. Insignificant deviations between the DDA values from both methods are obtained. The experimental FTIR bands and standards for the refined chitosan from crab and shrimp shell wastes are in excellent agreement. The physicochemical properties of the raw precursors, extracted chitin and chitosan (raw and refined/decolorized) are equally evaluated. The extracted chitin and chitosan are characterized using analytical techniques. The implication of this study is in the current drive to produce chitin and chitosan from the underutilized shell wastes of C. amnicola and P. notialis of Nigerian sources with a high yield and a high DDA. In this study, the P. notialis shell is a better alternative source of chitin and chitosan than C. amnicola shell. Key words: Extraction, characterization, Brunauer-Emmett-Teller (BET) surface area, Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy, transmission electron microscopy.