IR Bands Research Articles

Computational analysis of the vibrational spectra and structure of aqueous cytosine.

The recently developed efficient protocol for the explicit quantum mechanical modeling of the structure and IR spectra of liquids and solutions [Katsyuba et al., J. Phys. Chem. B, 2020, 124, 6664-6670] is used to describe aqueous solutions of cytosine. The same cluster model of a solute surrounded by the first solvation shell of solvent molecules was shown to be sufficient to reproduce experimental vibrational frequencies and relative IR and Raman intensities. An equally good quality of Raman spectra was provided by B3LYP-D3/def2-TZVP and B3LYP-D3/aug-cc-pVDZ simulations. Computations using the PBE functional were sufficient for modeling of the IR spectra but failed in the simulations of Raman scattering. It is shown that strong changes of frequencies and relative intensities of Raman and IR bands of cytosine, caused by its hydration, cannot be completely assigned to the influence of hydrogen bonds (HBs) with 7 or 8 closest water molecules. They are rather ascribed to the combined effect of solute-solute and solute-solvent HBs with the participation of at least 30 water molecules separating cytosine from the bulk solvent. This suggests that the vibrational modes and derivatives of the polarizability and dipole moment of the solute are mainly locally influenced by its first hydration shell, while the influence of bulk water is rather modest.

Characterization and Conductivity Studies of Graphene Oxide with Different Degrees of Oxidizing Agent

Different degrees of potassium permanganate (KMNO4) was used in the synthesis of graphene oxide (GO). In characterization analysis, the appearance of IR band attributes to O–H, C=C, C–OH and, C–O–C can be observed at around 3500 cm−1, 1650 cm−1, 1400 cm−1 and, 1200 cm−1 respectively. The UV-Vis spectroscopy revealed, GO with more KMNO4 shows increment in absorption and wavenumber due to more concentration of GO and stacked layers of GO. Nevertheless, a high level of KMNO4 results in a low density of GO. Analysis from Semiconductor Parameter Analyzer (SPA) revealed, a low oxygenated functional group from low-level KMNO4 produces less band gap open and thus, yielding high conductivity.

Chemical and Morphologic Characterization of Sylvite (KCl) Mineral from Different Deposits Used in the Production of Fertilizers

In the present work, four (4) samples of sylvite (KCl) from different deposits in Canada, Belarus and Germany were analyzed in order to determine the differences between them in terms of chemical composition, morphology and impurities present. Different non-instrumental and instrumental techniques were used. A scanning electron microscope analysis showed that the particles are completely amorphous. Bueno mineral has particles with the largest area (with 91.4% particles larger than 0.50 mm), and the BPC mineral samples have those with the smallest area (with 49.9% particles smaller than 0.50 mm). The Bueno mineral has the highest angle of repose. Bueno mineral has the highest surface area and pore volume when compared to the other KCl minerals. On the other hand, the BPC KCl mineral presented a lower surface area and pore volume. The problem mineral has the highest percentage composition of K. Blanco mineral did not present Al, and the element Mo was not detected in the Blanco and Bueno mineral. The IR bands of O-H, C-N, N-H and C=O bonds were observed. These results are useful for the fertilizer industry. These differences can produce adverse effects in a subsequent application in fertilizer production processes. Such differences can be attributed to the origin of this mineral, the way it is obtained and exploited, or to the transport and storage process through the use of anticompacting additives due to the high hygroscopicity of the mineral.

A Southern Photometric Quasar Catalog from the Dark Energy Survey Data Release 2

We present a catalog of 1.4 million photometrically selected quasar candidates in the southern hemisphere over the ∼5000 deg2 Dark Energy Survey (DES) wide survey area. We combine optical photometry from the DES second data release (DR2) with available near-infrared (NIR) and the all-sky unWISE mid-infrared photometry in the selection. We build models of quasars, galaxies, and stars with multivariate skew-t distributions in the multidimensional space of relative fluxes as functions of redshift (or color for stars) and magnitude. Our selection algorithm assigns probabilities for quasars, galaxies, and stars and simultaneously calculates photometric redshifts (photo-z) for quasar and galaxy candidates. Benchmarking on spectroscopically confirmed objects, we successfully classify (with photometry) 94.7% of quasars, 99.3% of galaxies, and 96.3% of stars when all IR bands (NIR YJHK and WISE W1W2) are available. The classification and photo-z regression success rates decrease when fewer bands are available. Our quasar (galaxy) photo-z quality, defined as the fraction of objects with the difference between the photo-z z p and the spectroscopic redshift z s , ∣Δz∣ ≡ ∣z s − z p ∣/(1 + z s ) ≤ 0.1, is 92.2% (98.1%) when all IR bands are available, decreasing to 72.2% (90.0%) using optical DES data only. Our photometric quasar catalog achieves an estimated completeness of 89% and purity of 79% at r < 21.5 (0.68 million quasar candidates), with reduced completeness and purity at 21.5 < r ≲ 24. Among the 1.4 million quasar candidates, 87,857 have existing spectra, and 84,978 (96.7%) of them are spectroscopically confirmed quasars. Finally, we provide quasar, galaxy, and star probabilities for all (0.69 billion) photometric sources in the DES DR2 coadded photometric catalog.

Synchrotron Radiation FTIR Microspectroscopy Study of Biomolecular Alterations in Vincristine-Treated WRL68 Cells at the Single-Cell Level.

The toxic effect of vincristine on hepatocytes has rarely been studied. Synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy is a novel technique for investigating drug-cell interaction systems. In this research, the biomolecular alterations in WRL68 cells induced by vincristine treatment were investigated by SR-FTIR microspectroscopy and were further analyzed by multivariate statistical analysis and semiquantitative methods, including principal component analysis (PCA), orthogonal partial least square-discriminant analysis (OPLS-DA), and the peak area ratios of several characteristic IR bands. In vincristine-treated WRL68 cells, alterations in lipid structures and the presence of more long-chain fatty acids were found. A decrease in protein α-helical content relative to β-sheet structures in vincristine-treated WRL68 cells was identified. The nucleic acid content was decreased relative to that of lipids and proteins in WRL68 cells treated with vincristine. These results provide important information about the toxic effect of vincristine on normal liver cells. This research also provides a new approach to reveal the biomolecular alterations in drug-treated hepatocytes by combining SR-FTIR with multivariate statistical analysis and semiquantitative methods.

Antimicrobial Efficiency of Chitosan and Its Methylated Derivative against Lentilactobacillus parabuchneri Biofilms.

Antimicrobial materials are considered potential alternatives to prevent the development of biofilm-associated contaminations. Concerns regarding synthetic preservatives necessitate the development of innovative and safe natural antimicrobials. In the present study, we discuss the in situ infrared attenuated total reflection spectroscopy (IR-ATR) investigations of the selective antimicrobial efficiency of chitosan in controlling the growth of Lentilactobacillus parabuchneri biofilms. The protonated charges of chitosan were additionally amplified by structural modification via methylation, yielding quaternized derivative TMC (i.e., N, N, N-trimethyl chitosan). To evaluate antimicrobial effectiveness against L. parab. biofilms, IR-ATR spectroscopy provided information on molecular mechanisms and insights into chemical changes during real-time biofilm inhibition studies. The integrated fiberoptic oxygen microsensors enabled monitoring oxygen (O2) concentration gradients within biofilms, thereby confirming the metabolic oxygen depletion dropping from 4.5 to 0.7 mg L-1. IR studies revealed strong electrostatic interactions between chitosan/its water-soluble derivative and bacteria, indicating that a few hours were sufficient to affect biofilm disruption. The significant decrease in the IR bands is related to the characteristic spectral information of amide I, II, III, nucleic acid, and extracellular polymeric matrix (EPS) produced by L. parabuchneri biofilms. Cell clusters of biofilms, microcolonies, and destabilization of the EPS matrix after the addition of biopolymers were visualized using optical microscopy. In addition, scanning electron microscopy (SEM) of biofilms grown on polystyrene and stainless-steel surfaces was used to examine morphological changes, indicating the disintegration of the biofilm matrix into individual cells. Quantification of the total biofilm formation correlated with the CV assay results, indicating cell death and lysis. The electrostatic interactions between chitosan and the bacterial cell wall typically occur between protonated amino groups and negatively charged phospholipids, which promote permeabilization. Biofilm growth inhibition was assessed by a viability assay for a period of 72 h and in the range of low MIC values (varying 0.01-2%). These results support the potential of chitosan and TMC for bacterial growth prevention of the foodborne contaminant L. parabuchneri in the dairy industry and for further implementation in food packaging.

Comparison of two different infrared spectral analysis based evaluation of impact induced shock events of the Chelyabinsk meteorite

Shock metamorphic processes in minerals were observed in the recently fallen Chelyabinsk meteorite and compared with two infrared laboratory methods: DRIFT and ATR based spectral analysis types, attached to a Fourier Transformational Infrared Spectrometer (FTIR). Both of ATR and DRIFT methods have advantages and disadvantages for shock stage identification. However, while the ATR method has wide literature background, the DRIFT method was not used in shock metamorphic research yet, hence this study links ATR spectra with DRIFT spectra to obtain reference for such IR methods in the analysis of shock metamorphism. The results show that shock-based spectral changes could be better followed by the decreasing number of peaks with DRIFT than with ATR data; while the situation is opposite for FWHM values, which better characterizes the shock consequences from ATR data. The DRIFT analyses made from bulk meteorite material. Hence more mineral phases were identified than by separate measurements of ATR. The ATR spectra includes rather major vibration, But with DRIFT the minor bands could be also measured. Hence the other shock indicator, the disappearance of minor bands with increasing shock stage could be better followed by DRIFT. The important shock metamorphic indicator, the FWHM could be identified rather from ATR spectra, as the DRIFT spectra includes small sized peaks, and the FWHM values are near to the spectral resolution of DRIFT spectra. Both of ATR and DRIFT methods show shift of IR bands to higher wavenumber with increasing shock stage. Moreover, the DRIFT method shows the split of some minor bands in case of feldspar and pyroxene due to dimerization of silicate structure.With increasing shock stage one band disappeared and a new one appeared in case of feldspar DRIFT data, while feldspar did not emerge using ATR observations. In case of olivine the major bands shifted by +2… +5 cm−1 using DRIFT and ATR spectra also. In case of pyroxene one band disappeared and new forbidden bands emerged. These results provide starting points to develop shock estimation using DRIFT method too, what is a much more available at various laboratories. However, it is worth mentioning that DRIFT method usually identifies more mineral phases than ATR because of the difference in spatial resolution.

Impact of Natural Degradation on the Aged Lignocellulose Fibers of Moroccan Cedar Softwood: Structural Elucidation by Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD)

The aims of this study are to investigate the structure of four historical Moroccan cedar softwood samples of different aging time duration (16th, 17th, 19th, 21st centuries) and compare among these four samples, using two analytical methods, FTIR and XRD, in order to confirm some structural changes and determine the degree of deterioration. The pronounced hemicellulose deterioration was highlighted by a breakdown of IR acetyl groups at 1738 cm−1 from the 19th century sample until aged ones. The cellulose XRD crystallinity index showed an important decrease from recent to oldest samples (51.8 to 20.2%) justifying the damages mainly in the two oldest samples (17th and 16th centuries), also confirmed by FTIR. The alteration of lignin was manifested in the case of the two ancient samples (16th and 17th centuries), proven by the decrease in IR bands related to aromatic nuclei (1595, 1500, 1230 cm−1) evolving towards a new diconjugate C=O formers at 1647 cm−1 (quinone, Ar-CO-Ar, Ar-CO-C=C). For accurate elucidation, the data of two combined techniques were compared and correlated. The obtained results depended on the part of the wood exposed to weathering effects (internal or external) and were influenced by both extended time of aging and effects of natural deterioration agents. The effects of natural aging were investigated in four historical Moroccan cedar softwood samples (16th, 17th, 19th, 21st centuries) using two analytical tools: FTIR and XRD. The pronounced hemicellulose deterioration was highlighted by a breakdown of IR acetyl groups at 1738 cm−1 and declines in the absorption signal at 1268 cm−1 from the 19th century sample until aged ones. The cellulose XRD crystallinity index (CrI) estimation showed an important decrease from recent to oldest samples (51.8 to 20.2%) justifying the damages mainly in the two oldest samples (17th and 16th centuries). These data were also confirmed by FTIR showing a significant reduction in both area profiles of C-O-C (1150–1000 cm−1) and C-H crystalline cellulosic bands (1375, 1318, and 1268 cm−1), respectively. The lignin alteration in both old samples (16th and 17th centuries) was proven by the decrease in IR aromatic skeleton (1595, 1500, and 1230 cm−1) evolving towards a new diconjugate C=O formers at 1647 cm−1 (quinone, Ar-CO-Ar, Ar-CO-C=C). To determine the structural difference and the degree of deterioration, the IR area of C=O band intensities ranging from 1550 to 1800 cm−1 was exploited. For accurate elucidation, the data of two combined techniques were compared and correlated. The obtained results depended on the part of the wood (internal or external) exposed to weathering effects and were influenced by both extended time of aging and effects of natural deterioration agents.

Interacting Kilonovae: Long-lasting Electromagnetic Counterparts to Binary Mergers in the Accretion Disks of Active Galactic Nuclei

We investigate the dynamics and electromagnetic (EM) signatures of neutron star–neutron star (NS–NS) or neutron star–black hole (NS–BH) merger ejecta that occur in the accretion disk of an active galactic nucleus (AGN). We find that the interaction between ejecta and disk gas leads to important effects on the dynamics and radiation. We show five stages of the ejecta dynamics: gravitational slowing down, coasting, Sedov–Taylor deceleration in the disk, reacceleration after the breakout from the disk surface, and momentum-conserved snowplow phase. Meanwhile, the radiation from the ejecta is so bright that its typical peak luminosity reaches a few times 1043–1044 erg s−1. Since most of the radiation energy has converted from the kinetic energy of merger ejecta, we call such an explosive phenomenon an interacting kilonova (IKN). It should be emphasized that IKNe are very promising, bright EM counterparts to NS–NS/BH–NS merger events in AGN disks. The bright peak luminosity and long rising time (i.e., 10 to 20 days in UV bands, 30 to 50 days in optical bands, and 100 days to hundreds of days in IR bands) allow most survey telescopes to have ample time to detect an IKN. However, the peak brightness, peak time, and evolution pattern of the light curve of an IKN are similar to a superluminous supernova in a galactic nucleus and a tidal disruption event making it difficult to distinguish between them. But it also suggests that IKNe might have been present in recorded AGN transients.

In silico study on probing atomistic insights into structural stability and tensile properties of Fe-doped hydroxyapatite single crystals

Hydroxyapatite (HA, Ca10PO4(OH)2) is a widely explored material in the experimental domain of biomaterials science, because of its resemblance with natural bone minerals. Specifically, in the bioceramic community, HA doped with multivalent cations (e.g., Mg2+, Fe2+, Sr2+, etc.) has been extensively investigated in the last few decades. Experimental research largely established the critical role of dopant content on mechanical and biocompatibility properties. The plethora of experimental measurements of mechanical response on doped HA is based on compression or indentation testing of polycrystalline materials. Such measurements, and more importantly the computational predictions of mechanical properties of single crystalline (doped) HA are scarce. On that premise, the present study aims to build atomistic models of Fe2+-doped HA with varying Fe content (10, 20, 30, and 40 mol%) and to explore their uniaxial tensile response, by means of molecular dynamics (MD) simulation. In the equilibrated unit cell structures, Ca(1) sites were found to be energetically favourable for Fe2+ substitution. The local distribution of Fe2+ ions significantly affects the atomic partial charge distribution and chemical symmetry surrounding the functional groups, and such signatures are found in the MD analyzed IR spectra. The significant decrease in the intensity of the IR bands found in the Fe-doped HA together with band splitting, because of the symmetry changes in the crystal structure. Another important objective of this work is to computationally predict the mechanical response of doped HA in their single crystal format. An interesting observation is that the elastic anisotropy of undoped HA was not compromised with Fe-doping. Tensile strength (TS) is systematically reduced in doped HA with Fe2+ dopant content and a decrease in TS with temperature can be attributed to the increased thermal agitation of atoms at elevated temperatures. The physics of the tensile response was rationalized in terms of the strain dependent changes in covalent/ionic bond framework (Ca–P distance, P–O bond strain, O–P–O angular strain, O–H bond distance). Further, the dynamic changes in covalent bond network were energetically analyzed by calculating the changes in O–H and P–O bond vibrational energy. Summarizing, the current work establishes our foundational understanding of the atomistic phenomena involved in the structural stability and tensile response of Fe-doped HA single crystals.

Analysis of Urinary Calculi by Fourier Transform Infrared Spectroscopy for Patients in Northern Jordan

The variations in urinary calculi are based on different diameters, which range in the form of sand grain to a urinary collecting system so that it can pass through the urinary tract regardless of any symptoms. To determine the composition of urinary calculi for patients in Northern Jordan by using Fourier Transform Infrared Spectroscopy method, samples of urinary calculi were retrieved from patients at King Abdullah University Hospital and Princess Basma Teaching Hospital. Urinary calculi were surgically removed from patients either arthroscopically (n = 35), or by percutaneous nephrolithotomy (PCNL) (n = 15) over a period of 16 months (2013-2014) and were brought to the laboratory in sterile containers. They were analyzed by Fourier Transform Infrared Spectroscopy method. A total of 39 male patients (78%) aging 23-85 years and 11 female patients (22%) aging 33-69 years were included in the study. The calculi comprised of 40% calcium oxalate and uric acid, 24% calcium oxalate, 18% pure uric acid, 12% magnesium ammonium phosphate, and 6% calcium oxalate and calcium phosphate. Mixed urinary calculi of calcium oxalate and uric acid were predominantly found among the patients with the following characteristic IR bands [1637cm-1 C=C Stretching, 1021 cm-1 N-H stretching, 780 cm-1 aromatic C-N stretching].

Isolation of Cellulosic Nano Fibers from Delonix Regia Fruits by Mechano-chemical Route

Lignocellulosic fibres have acquired prominence over past few years among researchers due to its prevalence in nature, biodegradability and high specific strength, among other factors. In this paper, mechanochemical route is used to obtain cellulosic nano fibres (CNF) from raw Delonix Regia fruits. CNFs are extracted with chemical treatments including alkali treatment, bleaching, acid hydrolysis and mechanical treatment including ball milling, centrifugation and high speed homogenization. Characterization of the material produced is carried out using X-Ray Diffraction (XRD), Thermo-Gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and Nano Particle Size Analyzer (NPA). XRD results showed that the crystallinity index (CrI) improved from 52.24% to 73.59% for extracted cellulose whereas it got reduced slightly to 68.31% for CNF samples and the crystallite size extracted cellulose and CNF was estimated to be 6.9 nm and 5.1 nm respectively. TGA results proved that the extracted cellulose and CNF are thermally stable compared to raw DRFF samples. First degradation in TGA started near 70-80C which represents moisture loss. Second degradation temperature improved for cellulose and CNF from 173.6C for DRFF to 223.4C and 246.1C which showed improvement in thermal stability. Major weight loss in second degradation shifted from 298.3C to 346.8C and 348.5C for cellulose and CNF respectively. Ash content was slightly decreased for CNF and cellulose samples compared to DRFF. Typical characteristic IR bands of cellulose were observed at 3400 cm-1, 2800-2900 cm-1, 1643.6 cm-1,1447 cm-1, 1084.6 cm-1 and 673.8 cm-1 of O-H stretching vibrations, C-H stretching, O-H bending, CH2 bending of pyranose ring, C-O-C pyranose ring vibration and O-H out-of-plane bending respectively in extracted cellulose and CNF samples. Improvement in cellulose content was observed from FTIR results and found suitable for application in composite materials. The average particle size of CNF measured by NPA was 247.3 nm proving the abundance of material at nanoscale. The average zeta potential of CNF was estimated at -50 mV with negative sign representing hydroxyl group. From the results of zeta potential measurement, material was found to be electro-statically stable and can be utilized for nanocomposite fabrication.

Degradation of Losartan Potassium Highlighted by Correlated Studies of Photoluminescence, Infrared Absorption Spectroscopy and Dielectric Spectroscopy.

In this paper, new results on the degradation of losartan potassium (LP, (1)), in the absence and presence of excipients, which was induced by UV light, the acid character of phosphate buffer solution (PBS) and alkaline medium, respectively, are reported through correlated studies of FTIR spectroscopy, photoluminescence and dielectric spectroscopy. The photoluminescence (PL) spectra of LP and the drug marked under the name Lorista (LO) are characterized by intense emission bands, peaking at 378 nm and 380 nm, respectively, accompanied by low intensity bands with a maximum at ~450-460 nm. Photodegradation of LO in a solid state is evidenced by a decrease in the intensity of the PL band at 380 nm, a variation that originates both in the adsorption of water vapors from the air and in the interaction of LP with excipients such as cornstarch, silicon dioxide and cellulose. The LP-water interaction is described, taking into account the main electrical parameters, i.e., complex dielectric permittivity and electrical conductivity. Photodegradation of LP and LO also induces an increase in the intensity of the emission band, at ~450-460 nm. The influence of acid and alkaline medium on the LO degradation is analyzed using phosphate buffer (PBS) and NaOH solutions, respectively. In both cases, a decrease in the intensity of the PL band, at 380 nm, is reported. The intensity diminution of the PL spectra of NaOH-reacted LP and LO is the result of the formation of the photodegradation product N-methanolamide-{[2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl]methyl} (2). This compound was proven by the studies of FTIR spectroscopy achieved on LP and NaOH-reacted LP. The appearance of the IR band at 1740 cm-1 and the increase in the absorbance in the IR band at 1423 cm-1 indicate that the photodegradation product (2) contains the C=O and C-OH functional groups.

Monitoring the Simultaneous Implantation of Ti and Tb Cations to a Sacrificial Template and the Sol-Gel Synthesis of Tb-Doped TiO2 (Anatase) Hollow Spheres and Their Transition to Rutile Phase

Tb-doped TiO2 (anatase) micro-hollow spheres (HSs) with nano-shells, in the range 0.00-3.00 at.% Tb, were successfully synthesized by a simultaneous chemical implantation route of both Ti and Tb cations from chlorides to a poly-styrene (PST)-co-poly-divinyl benzene (PDVB) sacrificial template, followed by controlled hydrolysis and polycondensation reactions. After water addition to the mixture of the precursors with the template, a decrease in the intensity and a shift to lower wavenumbers of the C=O absorption band in the IR spectra can indicate not only the anchoring of Ti and Tb ions to the carbonyl group of the template but also the hydrolysis of the implanted precursors. This latter process can involve a proton attack on the Ti-Cl, Tb-Cl and C=O bonds, the occupation of a vacant site by a water molecule, and then the dissociation of the dangling Ti-Cl, Tb-Cl ligands and C=O bonds. It gives rise to Ti1-xTbx[(OH)4-uClv]@PST-PDVB and Ti1-xTbx[(OH)4-y]@PST-PDVB complexes (x = 0.00, 0.0012, 0.0170 and 0.030). Finally, polycondensation of these species leads to Ti1-xTbxO2-w'@PST-PDVB compounds. After subsequent thermal removal at 550 °C of the template, the IR bands of the core (template) totally vanished and new bands were observed in the 400-900 cm-1 region which can be attributed to the metalloxane bondings (M-O, M'-O, M-O-M, M-O-M' and/or M'-O-M', being M and M' = Ti and Tb, respectively, i.e., mainly vibration modes of anatase). Then, micron-sized HSs of TiO2 and Tb-doped-TiO2 (anatase) were obtained with nano-shells according to field emission gun scanning electron microscopy (FEG-SEM) and transmission electron microscopy (TEM) observations. Furthermore, X-ray photoelectron spectroscopy (XPS) measurements confirmed the presence of Tb4+ (38.5 and 41.2% for 1.70 and 3.00 at.% Tb, respectively) in addition to Tb3+ in the resulting HSs, with increasing Tb4+ content with both Tb doping and higher calcination temperatures. Then, these HSs can be considered as rare earth (RE) co-doped systems, at least for 1.70 and 3.00 at.% Tb contents being the transition to rutile phase favored by Tb doping for those compositions. Finally, diffusion of Tb from the inner parts to the surface of the HSs with the calcination treatments was also observed by XPS.

Synthesis of acetylenic 17α-ethynylestradiol derivatives as potential trypanocidal oral drugs: In vitro and in silico evaluation

The cross-coupling Sonogashira reaction of 17α-ethynylestradiol (EE2) with 4-iodobenzoic acid and 1-iodo-4-nitrobenzene to give two new derivatives 1 and 2, along with the 17α-(4-aminophenyl)ethynyl-estra-1,3,5(10)-triene-3,17β-diol 3 is reported. The compounds were characterized using 1D and 2D NMR techniques, FTIR in the solid state, mass spectrometry and elemental analysis. The correlation in the HMBC spectrum between the acetylenic carbon signal at 85.7 ppm and the aromatic protons at 7.50 ppm, and the presence of the IR bands at 3700–2300, 2217, and 1694 cm−1, support clearly the formation of compound 1. Similarly, the correlation in the HMBC spectrum between the signals at 84.8 and 7.63 ppm, and the IR bands at 2218, 1518, 1339, 818 and 749 cm−1 support the obtention of compound 2. According to the in silico absorption, distribution, metabolism, excretion (ADME) properties of EE2 derivatives, they could act as drugs for oral and topic administration, with gastrointestinal absorption, and good bioavailability. The trypanocidal activity of compounds 1, 2, and 3 was evaluated in vitro against the epimastigote stage of three T. cruzi strains, Ninoa, TH, and INC5, and their cytotoxicity over the J774.2 macrophage cell line was assayed. Derivative 1 showed higher trypanocidal activity than Benznidazole and Nifurtimox against epimastigotes of Ninoa strain, whereas the INC5 strain showed high sensitivity to EE2. None of the compounds showed antibacterial or antifungal activity. Nonetheless, compound 1 could represent an alternative to current trypanocidal drugs.

Physico-chemical properties of chitosan extracted from Whiteleg shrimp (Litopenaeus vannamei) processing shell waste in Sri Lanka

The present study investigated the potential of whiteleg shrimp shell waste to use as a source of chitosan which has a limited focus on previous Sri Lankan studies. Comparatively higher amount of chitosan yield (33.53%) was obtained in the study with 91.78 ± 0.66 (%) of dry matter content, 8.22 ± 0.66 (%) of moisture content, 1.08 ± 0.24 (%) of ash content, 80.43% of the degree of deacetylation, 435.87 ± 1.03 cP dynamic viscosity and a good thermal stability up to 312 °C. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the structure of chitin and chitosan by the presence of their characteristic IR bands and X-ray diffraction analysis further verified the crystalline structure of the extracted chitin and chitosan. Scanning electron microscopic (SEM) images of the extracted chitosan recognized the layers of flakes with porous and fibril structures. According to the energy-dispersive X-ray spectroscopy image, carbon, oxygen and nitrogen were observed as the major elements in the extracted chitosan and no calcium peaks were detected confirming effective demineralization in the extraction process. Further, DPPH (2,2-diphenyl-1-picryl hydrazy) assay revealed that the chitosan solution with the concentration of 10 mg/mL was having 66.45% of free radical scavenging activity. Thus, the present study reveals that the chitosan with high quantity and quality can be extracted from whiteleg shrimp (Litopenaeus vannamei) processing shell waste in Sri Lanka suggesting a solution to the waste accumulation in processing factories while proposing an alternative income generation strategy from waste.

Structure-bandgap tunability of metal halide perovskites: Synthesis, spectral, single crystal X-ray structural, BVS, CShM and Hirshfeld surface analysis of piperidinium hexahalostannates(IV)

Metal halide perovskites such as piperidinium hexachlorostannate(IV) and piperidinium hexabromostannate(IV) were prepared along with their ammonium analogues ((1) and (2)) and were analyzed by IR, 1H, 13C NMR, DRS techniques. Single crystal X-ray structures were determined and Bond valence sums (BVS), Continuous Shape Measure (CShM) parameters were deduced from structural data. Broad IR bands were observed for υNH2 vibrations (3388, 3383 cm–1) long with characteristic δNH bending vibrations (1571, 1573 cm–1). TG–DT analysis confirmed the proposed formulae of (1) to (4). Band gaps of the hybrids derived from the DRS study followed the decreasing order: (NH4)2SnCl6 >(C5H10NH2)2SnCl6 >(NH4)2SnBr6 > (C5H10NH2)2SnBr6. Ammonium hybrids (1) & (2) and the piperidinium analogues (3) & (4) are isostructural. Differentiation of Sn-Xaxial/equatorial bonds and distortion of X–Sn–X bond angles observed in (3) and (4) are due to the substitution of ammonium cation by bulky piperidinium cation. The crystal structures are stabilized by intermolecular N–H···X interactions. BVS for (1), (2), (3) and (4) are: 4.12, 4.01, 3.96 and 3.92 respectively, which established the formal oxidation state of tin as quadripositive. CShM for (1), (2), (3) and (4) are: 0.0000, 0.0000, 0.0172 and 0.0103 respectively, indicating octahedral environment of halogen atoms around tin. Shape Index map of (C5H10NH2)2SnBr6 (4) with the least band gap tends to be spherical compared to other compounds.

Molecular dynamic simulations for interactions of oxytetracycline with copper(II)-exchanged NaY zeolite

• Surface structure reflections on interactions of OTC with Cu 2+ -Y was explored. • The Raman spectra revealed ion exchange took place at the 4-ring I site. • Cu 2+ -Y offered reducing strain broadening and narrow particle size distribution. • MD simulation revealed ability of Cu 2+ -Y to attract OTC at force interaction. This study was devoted to examine the effect of the surface structure of Cu 2+ -Y against pure NaY on the photodegradation of oxytetracycline (OTC). The lattice strain examined by Rietveld analysis of XRD data showed strain induced peak broadening at 0.124 for NaY, which diminished to 0.119 for Cu 2+ -Y, prompted by the exchange of Cu 2+ onto the NaY zeolite. Scanning electron microscope (SEM) statistical analysis of Cu 2+ -Y revealed better crystallinity with larger cube width, >2 µm, compared with NaY, 1.7 µm. The vibrational modes and optical properties of Cu 2+ -Y and NaY were compared using Fourier transform infrared (FTIR) spectra, Raman spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). An IR band at 665 cm −1 associated with ν s (Si-O-Cu) was evident for Cu 2+ -Y, which was absent from the spectrum of pure NaY. The Raman bending vibration at 490 cm −1 due to 4-membered ring I in the Cu 2+ -Y displayed a blue shift and a lower value of the full width at half maximum (FWHM) by about 3.02 nm and 0.74 cm −1 , respectively, compared with that of NaY. It was proposed that Cu 2+ ions are attached to shared oxygen of double 4-rings in Y-zeolite. The electronic analysis of Cu 2+ -Y revealed an indirect energy bandgap of 3.17 eV together with an excitonic absorption band at ∼2 eV. The computational molecular adsorption calculations demonstrated the potential effect of Cu 2+ -Y to accommodate five molecules of OTC per unit cell. Molecular dynamics (MD) simulations were committed to support the response behind the higher efficiency and stability of Cu 2+ -Y towards adsorption of the OTC under the force of interaction. OTC molecules brought into being travel toward positions of copper in the optimized OTC@Cu 2+ -Y. In contrast, Na + ions in OTC@NaY held moving towards the edges of the zeolite unit cell and no evidence of the presence of OTC molecules inside the confines of the zeolite cavities. H-bond distribution indicate a close connection and a more stable configuration of OTC inside the Cu 2+ -Y. Thus, MD simulations can safely predict the potential of Cu 2+ to attract the OTC molecules to form OTC@Cu 2+ -Y complexes.

COVID-19 and Its Derivatives- A relation with light for health

Light now has many applications in life and plays a vital role in therapeutic and protective fields. In the recent era, many light sources are considered for prevention, sterilization, and curing, especially with artificial lamps. Since the coronavirus pandemic appeared in 2019, the world has been interested in sterilization by light rays from a physical and applied point of view. In this work, the authors focus on definite spectral bands and their direct effects on the current COVID-19 pandemic for a prevention spreading purpose. According to the light use results, until now, the most useful method for decontamination against COVID-19 is ultraviolet C. The other spectral bands like UVA, UVB, and violet-blue show that they have a more negligible effect on the deactivation of the COVID-19 virus. The UVA and UVB help increase vitamin D in the human body, reflecting positively on the immunity system and increasing the recovery rate. The violet-blue band is helpful in decontamination against bacteria microorganisms. As for the IR band, the studies are still recent, and until now, there is no recommendation to use this band in sterilization against this pandemic. Studies continued on UV utilization because the world urgently needs industrial and domestic disinfection systems and sterilization. The other bands have another substantial practical effect on health improvement so any people can survive and overcome different diseases.

PECA-FY4A: Precipitation Estimation using Chromatographic Analysis methodology for full-disc multispectral observations from FengYun-4A/AGRI

Near-real-time precipitation estimates based on geostationary meteorological satellites are of great importance for monitoring hydrology-related disasters. Currently, the contributions of multispectral infrared observations to precipitation estimation have not been fully understood thus far. Motivated by estimating precipitation based on real-time data from geostationary satellites, this study proposes the Precipitation Estimation using Chromatographic Analysis (PECA) methodology based on full-disc observations from Advanced Geosynchronous Radiation Imager (AGRI) of FengYun-4A (FY-4A). Compared with PERSIANN-CCS and FY4AQPE-Official, the results of PECA (PECA-FY4A) are comprehensively evaluated against the GSOD (global gauge data), CMS (Chinese gauge data) and IMERG-LR (micro-wave precipitation products) for the period from January, 2019 to November, 2021. The findings and conclusions mainly include but are not limited to the following: (1) PECA clearly reveals that T12, ∆T10−14, ∆T7−14, and ∆T7−8 are effective for estimating precipitation volumes, with strong correlation to precipitation volumes but significantly less redundant information. (2) IR band differences are still sensitive to heavy precipitation although the abilities of single IR bands have become insufficient. For example, ∆T7−8 are sensitive to heavy precipitation in the eye walls of the typhoons. (3) The evaluation results show that PERSIANN-CCS generally outperforms FY4AQPE-Official, while PECA-FY4A features significant improvements over PERSIANN-CCS (the international benchmark of IR precipitation products) in terms of CC (∼10%, ∼100%, and ∼ 21%), RMSE (∼20%, ∼36%, and ∼ 11%), and CSI (∼25%, ∼100%, and ∼ 12%) against IMERG-LR, CMS and GSOD, respectively. The findings are expected to considerably contribute towards extending the current three-geostationary-satellite-series network (GOES, Meteosat, and Himawari) in PERSIANN-CCS to a four-geostationary-satellite-series network (by adding FY-4A and FY-4B) using PECA with higher quality, especially over the Asia-Pacific areas.