Powder X-ray Diffraction Studies Research Articles

Unraveling Effects of Current Density and Silicon on Silicon-Graphite Composite Anodes By in-Situ Synchrotron X-Ray Diffraction

The development of lithium-ion batteries (LIBs) with high capacity and rate capabilities is imperative to meet energy demands for both transport and grid storage in the future. Due to its relative abundance and excellent cycling stability, state of the art LIBs contains graphite as the main anode component. However, graphite suffers from a low theoretical specific capacity of 372 mAhg-1 [ 1 ]. Alternatively, silicon (Si) has emerged as a promising energy-dense anode material with a theoretical specific capacity 10 times higher than graphite, but their widespread application is impeded by low electrical conductivity and extremely poor cycling stability due to large volume variations when alloying with lithium during electrochemical cycling [ 2 ]. Interestingly, silicon-graphite (SiG) composites have been pinpointed as promising options for producing improved anodes, which aims to combine graphite’s high electronic conductivity and structural stability with silicon’s high specific capacity. As expected, increasing the silicon content of SiG anodes reduces the cycling stability [3]. Optimization of SiG with respect to silicon content and utilization of silicon is not straightforward, and a comprehensive analysis on the effect of variations of silicon content and current density on SiG andoes is key. To investigate these interactions, in-situ synchrotron X-ray diffraction (XRD) analysis of composite anodes with varying silicon content at increasing c-rates was performed.In situ experiments were performed at BM01 of the European Synchrotron Radiation Facility (ESRF). An in-situ electrochemical cell consisting of two current collectors, in which the lower current collector is made of brass and the upper current collector is made of stainless steel, was utilized [ 4 ]. A half-cell was then assembled between the two current collectors in a coin cell configuration using lithium metal as the counter electrode and a glass fiber separator. 1M LIFSI in 1:1 vol EC: DMC was used as the liquid electrolyte. The current collectors each have a thin single crystal sapphire window that is mostly transparent to X-ray but have distinct signals that can be masked out in post-processing. To avoid diffraction signal from the underlying copper current collector of the electrode, the composite anode consists of electrodes cast on copper foil as well as a free-standing section. The assembled cell was galvanostatically cycled between 1 V and 50 mV while XRD data was acquired. In this study 4 different electrodes containing 0, 20 %wt., 30 %wt. and 70 %wt. of Si in the active material of the electrode were cycled at C/5, C/2, 1C and 2C rates.Analysis of the XRD results showed that tracking of the evolution of graphite main reflections during electrochemical cycling while completely avoiding the copper signal has been achieved. The degree of graphite lithiation was tracked by following the distinct 002, 100 and 110 peaks of graphite where phase transitions to LiC12 and LiC6 can be identified. Consistent with the results of other studies, graphite has been found to be both lithiated and delithiated at lower potentials than silicon [ 3 ]. Increasing silicon content was found to decrease the degree of graphite lithiation as silicon will be preferentially lithiated. Increasing the current density was found to reduce the overall degree of lithiation of graphite as the specific capacity decreases and the material is not sufficiently lithiated to undergo the expected phase transitions. This study has therefore unraveled the effect of silicon content and current density on composite anode behavior which could allow for the design of better next-generation composite anodes. Tarascon, J.-M. & Armand, M. Issues and challenges facing rechargeable lithium batteries. Nature 414, 359–367 (2001). Ashuri, M., He, Q. & Shaw, L. L. Silicon as a potential anode material for Li-ion batteries: where size, geometry and structure matter. Nanoscale 8, 74–103 (2015). Moyassari, E. et al. The Role of Silicon in Silicon-Graphite Composite Electrodes Regarding Specific Capacity, Cycle Stability, and Expansion. J. Electrochem. Soc. 169, 010504 (2022). Drozhzhin, O. A. et al. An electrochemical cell with sapphire windows for operando synchrotron X-ray powder diffraction and spectroscopy studies of high-power and high-voltage electrodes for metal-ion batteries. J. Synchrotron Radiat. 25, 468–472 (2018). Figure 1

Battery Thermalization for Operando Synchrotron Powder Diffraction: Application to the Ca-TiS2 System

Characterizing electrode materials and understanding its behavior during redox process is a key factor for battery improvement. In Situ techniques on Operando batteries are of particular interest since they do not only probe the material during the electrochemical process but avoid its hazardous and tedious extraction and transfer under inert atmosphere from an electrochemical cell to e.g. capillaries, to perform Ex Situ data collection. Synchrotron based techniques –absorption and diffraction – together with improved detectors, are now intensively used in such In Situ studies on Operando batteries since they allow fast and real time data acquisition during the electrochemical, ion (des-)insertion, process. So far most In Situ X-ray powder diffraction studies on Operando batteries are performed at room temperature using either coin cells or so called Leriche cells [1] (pouch cells, despite widely used for spectroscopy, are generally not favored for diffraction since the container material produce additional Bragg peaks). At ALBA we slightly modified both types of cells: Leriche type and more widespread used CR2032-type coin cells so as to perform data collection in temperature range -10° – 100° C. (see picture)Both types of cell have been used to study the intercalation of calcium in TiS2, previously determined by Ex Situ powder diffraction [2]. We managed to collect powder patterns operando at 60°C, 45°C and room temperature. (Des-)Insertion of solvated Ca2+ in TiS2 was favoured by temperature, its signature being the appearance of a new phase with a first diffraction peak at very low angles (~17.7 Å in terms of d-spacing). The process was found to be solvent dependent and reversible upon oxidation, which differs from Li cells where a similar process was observed.[3]Either of these thermalized cells can be used at CELLS-ALBA synchrotron for Power Diffraction on BL04-MSPD beamline or hard X-ray Absorption Spectroscopy (XANES/EXAFS) on BL22-CLEASS, and since 2023 also using simultaneous Powder Diffraction and hard X-ray Absorption Spectroscopy in BL16-NOTOS beamline. Moreover, the Leriche setup is also designed to fit for a use in laboratory X-ray diffractometers, in both reflection and transmission. Leriche et al. (2010). J. Electrochem. Soc., 157(5), A606-A610.Tchitchekova et al (2018). Chem. Mater 30, 847−856Houdeville et al. (2021). J. Electrochem. Soc., 168, 030514 Figure 1

Tuning Pd-to-Ag Ratio to Enhance the Synergistic Activity of Fly Ash-Supported PdxAgy Bimetallic Nanoparticles.

Fly ash (FA)-supported bimetallic nanoparticles (PdxAgy/FA) with varying Pd:Ag ratios were prepared by coprecipitation of Pd and Ag involving in situ reduction of Pd(II) and Ag(I) salts in aqueous medium. All the supported nanoparticles were thoroughly characterized with the aid of powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), electron microscopy (field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM)), and elemental analyses, which include inductively coupled plasma-optical emission spectroscopy (ICP-OES) and energy-dispersive X-ray spectroscopy (EDS). A gradual broadening and shifting of PXRD peaks, ascribable to Ag, to higher angles with an increase in the Pd:Ag ratio affirms the alloying of interface between Pd and Ag nanoparticles. The coexistence of Pd and Ag was further confirmed by EDS elemental mapping as well as by the presence of bimetallic lattices on the FA surface, as evident from the high-resolution TEM analysis. The dependency of crystallite size and average size of bimetallic nanoparticles on Ag loading (mol %) was elucidated with the help of a combination of PXRD and TEM studies. Based on XPS analysis, the charge transfer phenomenon between contacting Pd-Ag sites could be evident from the shifting of 3d core electron binding energy for both Pd and Ag compared with monometallic Pd and Ag nanoparticles. Following a pseudo-first-order reaction kinetics, all the nanocatalysts were able to efficiently reduce 4-nitrophenol into 4-aminophenol in aqueous NaBH4. The superior catalytic performance of the bimetallic nanocatalysts (PdxAgy/FA) over their monometallic (Pd100/FA and Ag100/FA) analogues has been demonstrated. Moreover, the tunable synergistic effect of the bimetallic systems has been explored in detail by varying the Pd:Ag mol ratio in a systematic manner which in turn allowed us to achieve an optimum reaction rate (k = 1.050 min-1) for the nitrophenol reduction using a Pd25Ag75/FA system. Most importantly, all the bimetallic nanocatalysts explored here exhibited excellent normalized rate constants (K ≈ 6000-15,000 min-1 mmol-1) compared with other supported bimetallic Pd-Ag nanocatalysts reported in the literature.

The effect of cobalt-doped ZnO-g-C3N4 heterostructures on photocatalytic degradation of eosin yellow dye in water under simulated solar light

The unrestricted discharge of textile chemicals in natural water sources has posed major ecological and environmental threats to our standard of living. For decades, there has been a continuous search for affordable, and visible-light driven semiconductors with the capability of harnessing the full potential of sunlight to help curb the aforementioned problem. Herein, photocatalysts based on a series of cobalt (Co) and graphitic carbon nitride (g-C3N4) co-doped ZnO were synthesized via the co-precipitation method for eosin yellow dye degradation in water under visible light. The functional groups present in the materials were determined by FTIR. Other techniques such as Ultraviolet–visible (UV–Vis) spectrophotometry, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were utilized to study the optical properties, structural properties, morphology and elemental composition respectively. The nanomaterials' optical analysis showed a marginal rise in absorbance in the visible region with a corresponding reduction in the forbidden gap energy from 3.10 to 2.52 eV. XRD studies showed that the nanocomposites were polycrystalline in nature and possessed the hexagonal phase of ZnO having an average crystallite size of 42 nm. From the photocatalysis outcomes, the maximum photocatalytic performance was observed for the 0.8 % Co-doped ZnO-g-C3N4 system, which degraded 96 % of the dye in 180 min, with a rate constant of 17.01 x 10−3 min−1. The incorporation of Co enhanced ZnO's outstanding photocatalytic activity in the g- C3N4–ZnO system.

Fabrication and characterization of tamarind seed gum based novel hydrogel for the targeted delivery of omeprazole magnesium

The tamarind seed gum based novel hydrogel was fabricated by varying concentration of polymer, monomer and crosslinker for the targeted delivery of omeprazole magnesium at stomach pH of 1.5. The free radical graft copolymerization of 2-acrylamido-2-methyl propane sulfonic acid with tamarind seed gum backbone resulted in hydrogel. The formation of sulfonic acid pendant groups in hydrogel was observed by the existence of an infrared absorption band at 1152 cm−1 for SO group. The conversion to semicrystalline nature on incorporation of drug evidenced by powder X-ray diffraction studies with peaks at 2θ = 20.4° 31.5° and 52.2°. The scanning electron microscopy images showed bigger voids which narrowed down for drug loaded matrix, supported by the presence of a peak for magnesium in the energy dispersive X-ray spectroscopy. The greatest swelling was observed at pH 7 with second-order rate constant 1.5371 (g/g)/min and drug release was found to be 97.85 ± 1 % over 1200 min at pH 1.5. The drug release transport was found combination of diffusion and erosion of polymer chain to be super case II diffusion and Hill equation model was good fit. The hydrogel drug conjugate found to be non-toxic at tested concentrations (17 mg/50 mg) on in-vivo testing in Drosophila model.

Thermoelectric performance of indium-rich thiospinels [formula omitted] ([formula omitted] ≈ 0.16, 0.22 and x ≈ 0.1, 0.2)

Powder x-ray diffraction and Raman spectroscopy studies showed In-rich thiospinels with the chemical formula In1−y□yIn2S4−xTex (y ≈ 0.16, 0.22 and x ≈ 0.1, 0.2) to be composed of the cubic α-modification [space group (SG) Fd3̅m] with a minor admixture of tetragonal β-phase (SG I41/amd). Tellurium incorporation in the crystal structures is confirmed by Rietveld refinements, energy dispersive x-ray- and Raman spectroscopies. All samples are found to be indirect band gap semiconductors with an Egopt≈ 2 eV, which decreases with increasing Te-content. The thiospinels with y ≈ 0.16, 0.22 and x ≈ 0.1 revealed by two orders of magnitude enhanced charge carrier concentration (i.e., n≈ 1018 cm−3) and ≈ 6–9 times larger charge carrier mobilities (μ) than corresponding binary specimens. A kink at 200 K in ρT is found to originate from a stepper increase of n. The Seebeck coefficient is negative for all samples indicating electrons to be the dominant charge carriers. The total thermal conductivity of the compounds is almost completely phonon (κph) mediated. The Debye-Callaway fits of κph reveal an enhanced point-defect scattering in the In2.78S4−xTex series compared to In2.84S4−xTex, in accordance with the higher vacancy concentration (i.e., smaller y). The Balkanski-Klemens analysis of the temperature dependent Raman shifts indicated domination of three-phonon scattering mechanism agreeing with the lowered κph values. The appearance of low-energy optical modes confirms the In1-atoms, randomly occupying [In1S4]-tetrahedra, to reveal a ‘rattling’ motion and thus, to be a probable source of enhanced anharmonic effects limiting κph. Te-doping of In-rich thiospinels (y ≈ 0.16, 0.22) results in the improvement of the electrical transport characteristics and simultaneously in an increase of their thermal conductivities due to smaller vacancy concentration. The possible reduction of κph and the improvement of the TE performance are discussed.

Aerobic bacteria-supported biohybrid palladium catalysts for efficient cross-coupling reactions

Palladium-based catalysts are of key importance in organic synthesis due to their versatility and tolerance for a wide range of functional groups. However, their use challenged by increasing sustainability issues and complex preparation methods. Consequently, the development of new heterogeneous catalysts with enhanced sustainability is of significant interest. Typically, the synthesis of carbon supports for palladium is associated with high energy consumption or the generation of substantial chemical waste, prompting extensive research into the creation of sustainable biological supports. In this study, the potential use of aerobic bacterial cells as a support for palladium nanoparticles was explored, using Paracoccus yeei VKM B-3302 as a model organism. Electron microscopy, powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of palladium particles on the cell surface as well as inside microorganisms following deposition from a solution. Control experiments established that bacterial cells do not interact with either the reactants or the products of selected cross-coupling processes. Furthermore, bacteria do not affect the analysis of reaction mixtures by nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (GC–MS). At the same time, palladium/Paracoccus yeei demonstrated efficient catalysis of the Mizoroki-Heck and Suzuki-Miyaura reactions, yielding results comparable to commercial palladium on carbon (Pd/C) catalysts. Employing a fresh start procedure and catalyst separation method, the catalyst was successfully recycled and reused across five cycles, maintaining good catalytic activity. In a broader aspect, bacteria-supported biohybrid palladium catalysts can represent a new type of catalysts worth to explore in a number of processes, where sustainability issues are concerned.

Synthesis, spectroscopic and structural characterizations and in vitro antimycobacterial activity of silver(I) complexes with sulfapyridine (SPY) and sulfamerazine (SM)

Sulfonamides (sulfas) are a specific class of organic compounds that possesses antibacterial, anti-inflammatory, antiviral and antitumor activities. This class of molecules is also used in the synthesis of silver(I) complexes, which usually present significant biological activity as antimicrobial agents. In this context, the present work describes the synthesis, structural characterization and antibacterial assays of two silver(I) complexes with the sulfa drugs sulfapyridine (SPY) and sulfamerazine (SM). Chemical analyses and high-resolution mass spectrometric studies led to 1:1 metal/ligand compositions, suggesting the minimal formulas C11H10N3O2SAg·2H2O for AgSPY and C11H11N4O2SAg·2H2O for AgSM. Spectroscopic techniques such as 1H, 13C and {1H–15N} nuclear magnetic resonance (NMR), and also infrared measurements (IR) suggest the coordination of the ligands to silver(I) ions by the nitrogen atom of the SO2N moiety for both complexes. Crystal structures of AgSPY and AgSM were solved and refined by X-ray powder diffraction studies, where dimeric structures with Ag(I) ions bridging between two ligand molecules by the usual eight membered ring [AgNCN]2 and strong argentophilic interactions were observed. Minimum Inhibitory Concentration (MIC90) assays showed the promising activities of the free sulfonamides and the respective complexes against Mycobacterium tuberculosis H37Rv. MIC90 values, in µmol L–1, were 2.47, 3.60, 1.33 and 1.61 for SPY, AgSPY, SM and AgSM, respectively. The obtained MIC90 values were lower than those found for silver sulfadiazine and silver nitrate in the same experimental conditions.

The role of synbiotics in Alzheimer`s management

AbstractBackgroundQuercetin and Lactobacillus Brevis were used in the development of S‐SNEDDS for their antiinflammaging effect in Alzheimer`s diseaseMethodThe isotropic mixture was prepared by incorporating Capmul MCM, Tween 80 and Transcutol P as oil, surfactant and co surfactant phases respectively. Quercetin was then added. The probiotic mixture was selected as a solid carrier and drug loading was calculated. The droplet size and zeta potential was also determined. The formulation was also assessed for differential scanning colorimetry (DSC), powder x ray diffraction studies (PXRD), and field emission scanning electron microscopy studies (FESEM). Stability studies of the developed formulation was also carried out. Alzheimer’s disease was induced in rats by the use of aluminum chloride (100mg/kg) after taking necessary permission from the institution animal ethical committee. The Morris water maze (MWM) test was used to assess the animals 48 hours following the last treatment. Utilizing marketed ELISA kits, the concentrations of TNF, IL‐1, and IL‐6 were determined.ResultQuercetin was solubilized in the isotropic mixture. The drug loading was found to be 93.4±0.75% for the liquid SNEDDS (QUE‐L‐SNEDDS) formulation. The droplet size of QUE‐L‐SNEDDS was found to be 73.24±1.45nm and had a zeta potential of ‐23.21±1.34 mV. Whereas, the solid SNEDDS (QUE‐LB‐S‐SNEDDS) was found to be 74.56±1.23 nm and had a zeta potential of ‐21.43 mV, respectively. This indicated that there was no change in the L‐SNEDDS and S‐SNEDDS formulation. Further, the amorphous nature of quercetin was confirmed by the DSC, PXRD and FESEM studies. Aluminum chloride was successful in inducing Alzheimer`s disease in the rats. Impaired learning and memory impairments, increased short‐term memory loss, and decreased locomotor activity were all observed in the negative controls. The developed formulation was successful in reversing the inflammatory effects of Alzheimer’s disease.ConclusionThe present study reveals that Quercetin and Lactobacillus Brevis can be used as a symbiotic combination as well as an adjuvant therapy in the treatment of inflammation related to Alzheimer’s disease. The results reveal an interesting outcome at the preclinical level and warrants future studies aimed at other plant based polyphenolic compounds especially in neurodegenerative diseases such as Alzheimer’s disease.

Luminescence properties of Eu3+ doped Li2SrSiO4 phosphor

The modified solid-state reaction method has been used in this work to prepare Eu3+ doped Li2SrSiO4. PL spectroscopy was used to investigate photoluminescence (PL) properties of the sample. X-ray powder diffraction study was used to confirm the crystalline nature and phase purity of the sample. The particle size of prepared material ranges from 37 to 56 nm was observed from XRD. From PLE and PL spectrum the excitation and emission spectra of photoluminescence for Eu3+ doped Li2SrSiO4 were recorded. The prepared Eu3+ doped Li2SrSiO4 phosphor might have application in solid state lighting.

Preparation and Evaluation of Aceclofenac Solid Dispersion by Fusion Technique and Effervescent Assisted Fusion Technique: Comparative Study

Solid dispersion (SD) is one of the most widely used methods to resolve issues accompanied by poorly soluble drugs. The present study was carried out to enhance the solubility and dissolution rate of Aceclofenac (ACE), a BCS class II drug with pH-dependent solubility, by the SD method. Effervescent assisted fusion technique (EFSD) using different hydrophilic carriers (mannitol, urea, Soluplus®, poloxamer 188, and poloxamer 407) in the presence of an effervescent base (sodium bicarbonate and citric acid) in different drug: carrier: effervescent base ratio and the conventional fusion technique (FSD) were used to prepare ACE SD. Solubility, dissolution rate, Fourier transformation infrared spectroscopy (FTIR), PowderX-ray diffraction study (PXRD), and Differential scanning calorimetry (DSC) were determined for the SD obtained from both techniques as a comparative study. The results showed that EFSD using ACE: Soluplus®: effervescent base in a ratio of 1:2:1 had higher solubility and dissolution rate than that obtained from FSD prepared by ACE: Soluplus® in a ratio of 1:2. However, the two techniques obtained the amorphous form according to XRD and DSC results. It can be concluded that EFSD is a promising method for the solubility and dissolution rate improvement of BCS class II drugs.

Considerations for quantitative in situ X-ray powder diffraction studies of solid-state reactions

The importance of sample preparation in collecting high-fidelity powder diffraction data suitable for quantitative structure and phase analysis is well established. Such powder diffraction experiments are increasingly being applied in situ, during reactions, to explore solid-state reactivity. When applied in situ, X-ray diffraction is widely used to gain insight into the mechanism and kinetics, and to identify dynamic intermediate states. Here, using a model ion-exchange reaction (NaFeO2 + LiCl → LiFeO2 + NaCl), we show that sample preparation not only influences the fidelity of powder diffraction analysis but also impacts the observed reaction progress. Specifically, we found that the observed reaction progress can differ by ∼50% depending on the capillary sample preparation. Thus, for in situ diffraction studies of solid-state reactions, packing fraction is an important and previously unrecognized consideration that impacts reproducibility and fidelity of the reaction study.

Structural and vibrational properties of cage-type Sc5Ru6Sn18 superconductor under pressure using synchrotron X-ray diffraction and Raman spectroscopy

We report detailed structural investigations of cage-type quasi-skutterudite compound Sc5Ru6Sn18 using synchrotron single-crystal and powder x-ray diffraction. Single-crystal x-ray diffraction studies at ambient temperature revealed that the Sc5Ru6Sn18 compound has a tetragonal symmetry in the I41/acd space group setting with a = 13.58Å and c = 27.14Å, similar to other R5Rh6Sn18 (R = Y, Sc, Lu) cage-type compounds. The electrical resistivity ρ(T) revealed the presence of a sharp superconducting (SC) transition at Tc = 4.07K. The ρ(T) of Sc5Ru6Sn18 above Tc shows a smooth decrease with decreasing temperature without any evident anomalies. Systematic temperature dependent synchrotron x-ray powder diffraction (XRPD) studies covering 400 to 110K shows that the Sc5Ru6Sn18 system remain in the tetragonal I41/acd structure in this temperature range without any anomalous behaviour in the unit-cell parameters. High-pressure (HP) synchrotron XRPD revealed a smooth reduction in the unit-cell parameters up to ~7GPa which can be well described by a third-order Birch-Murnaghan equation providing the bulk modulus of the system to be ~102.6GPa. This system is found to several Raman modes below 300cm-1. We could follow the pressure evolution of four Raman modes, all of which show a smooth hardening with pressure up to ~7GPa. Our results call for systematic HP studies of the SC properties of the title system.

Solubility and Dissolution Enhancement of Atorvastatin Calcium using Phospholipid Solid Dispersion Technique

Atorvastatin (ATR) is a poorly water-soluble anti-hyperlipidemic drug. The drug belongs to the class II group according to the biopharmaceutical classification system (BCS) with low bioavailability due to its low solubility. Solid dispersion is an effective technique for enhancing the solubility and dissolution of drugs. Phospholipid solid dispersion (PSD) using phosphatidylcholine (PC) as a carrier with or without adsorbent (magnesium aluminum silicate, silicon dioxide 15nm, silicon dioxide 30nm, calcium silicate) was used to prepare ATR PSD using different drug: PC: adsorbent ratios by solvent evaporation method. The resulted PSD was evaluated for its percentage yield, drug content, solubility, dissolution rate, Fourier transformation infrared spectroscopy (FTIR), powder X-ray diffraction study (PXRD), and differential scanning calorimetry (DSC). The prepared (PSD) showed improvement in drug solubility in all prepared formulas. The best result was obtained with F5 (ATR: PC: MAS 1:3:4). The solubility was increased by 21 folds compared to the pure drug with enhanced dissolution and decrease crystallinity.

Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation

Acid pressure oxidation (POX) is a cost-efficient pre-treatment method for releasing refractory gold from arsenopyrite and pyrite prior to cyanidation. However, ongoing debate surrounds the mechanism of the dissolution, crystallization, and phase transformation during POX, in part due to the lack of thermodynamic data and in situ studies of the acid POX. In this study, we developed Eh-pH diagrams and used in situ powder X-ray diffraction (PXRD) to investigate mineralogical phase changes during acid POX of arsenopyrite. Based on the existing thermodynamic data, we established the Eh-pH diagrams for the Fe-As-S-H2O systems at 225 °C and 100 °C, which correctly predicted the predominant solid phases precipitating during POX of arsenopyrite at a pH range of 0 to 0.5, such as basic ferric sulphate (BFS: Fe(OH)SO4), szomolnokite (FeSO4·H2O), hydronium jarosite ((H3O)Fe3(SO4)2(OH)6) and angelellite (Fe4O3(AsO4)2). FeSO4·H2O solid is the stable phase during annealing stages as predicted by the Eh-pH diagram, which is in line with the observed solid phases using in situ PXRD. The influence of initial concentration of ferric ions and the presence of pyrite on mineral phase change was revealed. Our results confirmed the formation of FeSO4·H2O, BFS and hydronium jarosite during annealing stages, while BFS and/or hydronium jarosite dissolved during curing and cooling process. Especially, the formation of angelellite was observed in the presence of pyrite during cooling process, which is well-agreed with thermodynamic analysis.

SOLID DISPERSION SYSTEMS OF POORLY WATER SOLUBLE DRUG FEBUXOSTAT: PREPARATION, CHARACTERIZATION AND OPTIMIZATION

Febuxostat is a poor soluble drug used in the management of hyperuricemia and gout. The present study aims at increasing the solubility of febuxostat by solid dispersion technique with the aid of various polymers (Beta cyclodextrin, Soluplus®, HPMC E5, and Kolliphor® P 407) in various drug: carrier ratios employing the solvent evaporation method. Solid dispersions were evaluated for physical appearance, percentage yield, drug content, saturation solubility and dissolution properties. Saturation solubility data of the study depict an increased solubility of the solid dispersion compared to the pure drug. In in vitro release profiles revealed that formulation SD20, having drug: Kolliphor® P 407 in 1:9 ratio exhibited highest dissolution rate. The powder X-ray diffraction study and scanning electron microscopy (SEM) exhibited a crystalline to an amorphous transformation in the solid dispersion. The study demonstrated that solid dispersions are a highly effective technique to increase solubility and bioavailability of febuxostat.

Development of Chitosan/Sodium Carboxymethylcellulose Complexes to Improve the Simvastatin Release Rate: Polymer/Polymer and Drug/Polymer Interactions' Effects on Kinetic Models.

Simvastatin (SIM) is a potent lipid-lowering drug used to control hyper-cholesterolemia and prevent cardiovascular diseases. SIM presents low oral bioavailability (5%) because of its low aqueous solubility. In this work, polyelectrolyte complexes (PEC) are developed with different chitosan (CS) and carboxymethylcellulose (CMC) ratios that will allow for an increase in the SIM dissolution rate (2.54-fold) in simulated intestinal medium (pH 4.5). Scanning Electron Microscopy (SEM) images revealed highly porous structures. The changes between both complexes, PEC-SIM:CS:CMC (1:1:2) and (1:2:1), were related to the relaxation of the polymer chains upon absorption of the dissolution medium. Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRPD) studies were used to evaluate the polymer/polymer and drug/polymer interactions on the different PEC-SIM:CS:CMC ratios. In addition, the PEC-SIM:CS:CMC (1:2:1) complex exhibited a high ratio of protonated amino groups (NH3+) and an increase in intramolecular hydrogen bonds, which were correlated with a high expansion of the interpolymer chains and an increase in the SIM dissolution rate. Different kinetic models such as zero-order, first-order, Higuchi and Korsmeyer-Peppas were studied to evaluate the influence of CS/CMC ionic interactions on the ability to improve the release rate of poorly soluble drugs.

Effect of the Presence of Structural Defects on the Superconducting Properties of (NbTa)0.67(MoHfW)0.33 and Nb-47wt%Ti

A comparison of the results of studies on the influence of structural defects on the critical parameters of superconductivity has been made for the high-entropy alloy (NbTa)0.67(MoHfW)0.33 and for the conventional superconducting magnet material Nb-47wt%Ti. Positron annihilation lifetime spectroscopy (PALS), electrical resistivity, magnetization and magnetic susceptibility measurements were used. In addition, X-ray powder diffraction studies were performed on the high-entropy alloy (NbTa)0.67(MoHfW)0.33. Due to the rapid cooling of the materials after melting in the arc furnace, they contain a higher concentration of structural defects compared to the heat-treated materials. Magnetic property measurements showed that both the critical temperatures Tc and the upper critical fields μ0Hc2 of bulk superconductivity-related materials are improved in the presence of structural defects.

A comparative study on physico-chemical, optical, magnetic and ferroelectric properties of undoped BiFeO3 and Ni-doped BiFeO3 nanoparticles

Undoped BiFeO3 and Ni-doped BiFeO3 nanostructures were synthesised via colloidal gel, followed by a combustion reaction at a processing temperature of 500 °C, for testing their multiferrioic properties. Powder X-ray diffraction studies reveal the rhombohedral perovskite crystal structure for the synthesized pure BiFeO3, whereas Ni-doped BiFeO3 sample shows the formation of the rhombohedral perovskite structure along with the heterogeneous phase contains Fe2O3 and Bi2Fe4O9. The energy band gap (Eg) of Ni-doped BiFeO3 was found to be reduced (1.87 eV) compared to the Eg value (2.02 eV) of undoped BiFeO3, as confirmed by the Tauc plot. The synthesized compounds were tested for their vibrational bands by FT-IR analysis, and strong absorption bands were found at 555 cm−1, which attribute the vibration bonds of Bi-O and Fe-O. The aggregated particles with irregular morphology appeared in the TEM images of the undoped BiFeO3 and the presence of Ni-doped incorporation of BiFeO3. The ferromagnetic and ferroelectric behaviour of the synthesized undoped and Ni-doped BiFeO3materials was noticed in the magnetization vs. magnetic field (M−H) loops and polarization–electric field (P-E) at room temperature. The areas of the hysteresis loop, coercive force, magnetic saturation, saturation polarization, remanent magnetization, and polarization of Ni-doped BiFeO3 were decreased compared to undoped BiFeO3. The investigated Ni-doped BiFeO3 results were elucidated to assess the soft magnetic nature of device applications.

Preparation and evaluation of βcyclodextrin-based nanosponges loaded with Budesonide for pulmonary delivery

Budesonide (BUD) is a glucocorticosteroid used to treat chronic obstructive pulmonary disease. Despite this, it is a hydrophobic compound with low bioavailability. To address these hurdles, non-toxic and biocompatible βcyclodextrin-based nanosponges (βCD-NS) were attempted. BUD was loaded on five different βCD-NS at four different ratios. NS with 1,1′-carbonyldiimidazole (CDI) as a crosslinking agent, presented a higher encapsulation efficiency ( ̴ 80%) of BUD at 1:3 BUD: βCD-NS ratio (BUD-βCD-NS). The optimized formulations were characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), water absorption capacity (WAC), scanning electron microscopy (SEM), X-ray powder diffraction studies (XRD), particle size, zeta potential, encapsulation efficiency, in vitro and in vivo release studies, acute toxicity study, solid-state characterization, and aerosol performance. In vitro-in vivo correlation and cytotoxicity of the formulations on alveolar cells in vitro were further determined. In vitro and in vivo studies showed almost complete drug release and drug absorption from the lungs in the initial 2 h for pure BUD, which were sustained up to 12 h from BUD loaded into nanosponges (BUD-βCD-NS). Acute toxicity studies and in vitro cytotoxicity studies on alveolar cells proved the safety of BUD-βCD-NS. Several parameters, including particle size, median mass aerodynamic diameter, % fine particle fraction, and % emitted dose, were evaluated for aerosol performance, suggesting the capability of BUD-βCD-NS to formulate as a dry powder inhaler (DPI) with a suitable diluent. To sum up, this research will offer new insights into the future advancement of βCD-NS as drug delivery systems for providing controlled release of therapeutic agents against pulmonary disease.