Powder Diffraction Research Articles

Formulation and Characterisation of Fluconazole Loaded MCM-41 Powder for Topical Drug Delivery

Purpose: The use of common carriers like talc for topical drug delivery leads to diminished efficacy as a result of poor aqueous solubility and low dissolution rate. The objective of this study was to improve the efficiency of fluconazole topical dosage form using MCM-41 as a carrier material. The aim was to load fluconazole in carriers like MCM-41 as well as ß-Cyclodextrin and to compare the prepared powder formulation with the marketed formulations. Methods: Fluconazole complex was formulated with the use of MCM-41 and ß-CD as carriers in different proportions by melt, solvent evaporation and kneading method. The complex was developed into a powder formulation. These formulations were subjected to in vitro anti-fungal activity tests on candida albicans. Results: The inclusion compound was characterised by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and FTIR. The optimised method of preparation determined by in vitro dissolution was the melt method. The optimised formulation was then subjected to anti-fungal activity test. Formulation B containing MCM-41 as the bulk excipient had better performance than the marketed formulation; it showed 92.95 ± 0.33% CDR compared to 74.96 ± 0.47% CDR at the end of 1 hour and increased moisture adsorption. Conclusion: Thus, a fluconazole topical formulation with improved drug dissolution and moisture adsorption was designed. From in vitro tests, it was seen that the prepared formulation had better performance compared to the commercial formulation against skin mycotic infections and could be used for its treatment.

Silica-based pyrrolidinium ionic liquid immobilised on copper-citric acid metal-organic framework, ([PyrrSi][Cl]@Cu-Cit-MOF): Heterogeneous catalysis to the multicomponent reaction for the synthesis of imidazoles

A novel, silica-based pyrrolidinium ionic liquid immobilised on copper-citric acid metal-organic framework ([PyrrSi][Cl]@Cu-Cit-MOF), has been synthesised through an easy-to-handle procedure and is characterised by several techniques such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), powder X-ray diffraction (PXRD), thermal gravimetric (TG), and Brunauer-Emmett-Teller (BET) analyses. The present protocol is scalable and compatible with a wide range of aldehydes, producing imidazole derivatives in excellent yields (82-96 %) in very short reaction times (10–18 min). Moreover, the catalyst could be recovered and recycled simply by filtration and is reusable for up to six consecutive runs without any significant changes in its catalytic activity.

Effects of Cr doping and size reduction on the structural and magnetic properties of α–CoV2O6

We report the effect of Cr-doping on the structural and magnetic properties of powder α–CoV2O6 samples. Samples were synthesized using a wet chemical synthesis method and calcined at temperatures between 350 ℃ and 500 ℃ to promote phase formation. For α–CoV2O6 and Cr-doped α–CoV2O6 samples, a single phase only occurs when the samples are calcined at 450 ℃ and 500 ℃, respectively, as confirmed using powder x-ray diffraction (XRD). Cr-doping results in a compression distortion of the lattice along the c-axis. Transmission electron microscopy (TEM) measurements indicate that Cr-doping causes a reduction in particle size and particle agglomeration. Metamagnetism was observed in field dependence of magnetization, M(μ0H) for α–Co(V1−xCrx)2O6 samples with 0 ≤ x ≤ 0.05. The hysteresis in M(μ0H) curves for μ0H < 5T at 2K indicate that the magnetization is metastable and suggests magnetic irreversibility. Zero-field-cooled (ZFC) and field-cooled (FC) temperature dependence of magnetization, M(T), show antiferromagnetic (AFM) ordering of the α–Co(V1−xCrx)2O6 samples at fields, μ0H ≤ 1T. Increasing field strength to 2.5T causes a transition from the AFM state to a ferrimagnetic (FI) state, and an introduction of spin-glass (SG)-like behavior. At 5T, a transition from the FI state to a ferromagnetic (FM) state and a suppression of SG-like behavior is observed.

Efficacy of electrospun PAN/g-C3N4 nanofibers as a photocatalyst for the deterioration of hazardous azo dyes

PAN and PAN/g-C3N4 nanofibers were fabricated using the electrospinning technique. Meanwhile, g-C3N4 nanoflakes were synthesized using the thermal decomposition technique. The challenge of reusing powder catalysts was ultimately surmounted due to the use of dispersed g-C3N4. Characterization of the as-fabricated PAN/g-C3N4 NFs was performed employing wide-angle powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometry (UV–Vis), thermogravimetry analysis (TGA), N2 adsorption-desorption isotherms (BET) and X-ray photoelectron spectrometer (XPS). According to morphological studies, g-C3N4 nanoflakes get uniformly decorated over PAN fibers with a greater specific surface area and smaller band gap than g-C3N4, exhibiting maximal uniformity in dispersion. Under solar light irradiation, PAN (71%), g-C3N4 (84%), and PAN/g-C3N4 nanofibers (95%) showed excellent photocatalytic performances for the degradation of Methyl orange dye (MO) in 120 min with 95% degradation. Similarly, PAN (61%), g-C3N4 (72%), and PAN/g-C3N4 nanofibers (91%) showed photocatalytic performances for the degradation of Congo red dye (CR) in 160 min with 91% degradation. This effective degradation was due to a shift in band gap with high porosity of PAN/g-C3N4 NFs compared to pure materials such as PAN and g-C3N4.

A comparative study of the high-pressure structural stability of zirconolite materials for nuclear waste immobilisation

We present a comparative study of the high-pressure behaviours of the nuclear waste immobilisation materials zirconolite-2 M, −4M, –3O, and −3T. The materials are studied under high-pressure conditions using synchrotron powder X-ray diffraction. For zirconolite-2 M we also performed density-functional theory calculations. A new triclinic crystal structure (space group P1¯), instead of the previously assigned monoclinic structure (space group C2/c) is proposed for zirconolite-2 M. We named the triclinic structure as zirconolite-2TR. We also found that zirconolite-2TR undergoes a phase transition at 14.7 GPa to a monoclinic structure described by space group C2/c, which is different than the high-pressure structure previously proposed in the literature. These results are discussed in comparison with previous studies on zirconolite-2 M and the related compound calzirtite. For the other three zirconolite structures (4 M, 3O, and 3 T) this is the first high-pressure study, and we find no evidence for pressure induced phase transitions in any of them. The linear compressibility of the studied compounds, as well as a room-temperature pressure–volume equation of state, are also presented and discussed.

The impact of alcohol and ammonium fluoride on pressure-induced amorphization of cubic structure I clathrate hydrates.

We have investigated pressure-induced amorphization (PIA) of an alcohol clathrate hydrate (CH) of cubic structure type I (sI) in the presence of NH4F utilizing dilatometry and x-ray powder diffraction. PIA occurs at 0.98GPa at 77K, which is at a much lower pressure than for other CHs of the same structure type. The amorphized CH also shows remarkable resistance against crystallization upon decompression. While amorphized sI CHs could not be recovered previously at all, this is possible in the present case. By contrast to other CHs, the recovery of the amorphized CHs to ambient pressure does not even require a high-pressure annealing step, where recovery without any loss of amorphicity is possible at 120K and below. Furthermore, PIA is accessible upon compression at unusually high temperatures of up to 140K, where it reaches the highest degree of amorphicity. Molecular dynamics simulations confirm that polar alcoholic guests, as opposed to non-polar guests, induce cage deformation at lower pressure. The substitution of NH4F into the host-lattice stabilizes the collapsed state more than the crystalline state, thereby enhancing the collapse kinetics and lowering the pressure of collapse.

Controlling the Orientation-Dependent Second Harmonic Generation in Hybrid Germanium Perovskite Crystals.

Manipulating the crystal orientation plays a crucial role in the conversion efficiency during second harmonic generation (SHG). Here, we provide a new strategy in controlling the surface-dependent anisotropic SHG with the precise design of (101) and (20) MAGeI3 facets. Based on the SHG measurement, the (101) MAGeI3 single crystal exhibits larger SHG (1.3 × (20) MAGeI3). Kelvin probe force microscopy imaging shows a smaller work function for the (101) MAGeI3 compared with the (20), which indirectly demonstrates the stronger intrinsic polarization on the (101) surface. X-ray photoelectron spectroscopy confirms the band bending within the (101) facet. Temperature-dependent steady-state and time-resolved photoluminescence spectroscopy show shorter lifetime and wider emission band in the (101) MAGeI3 single crystal, revealing the higher defect states. Additionally, powder X-ray diffraction patterns show the (101) MAGeI3 possesses larger in-plane polar units [GeI3]- density, which could directly enhance the spontaneous polarization in the (101) facet. Density functional theory (DFT) calculation further demonstrates the higher intrinsic polarization in the (101) facet compared with the (20) facet, and the larger built-in electric field in the (101) facet facilitates surface vacancy defect accumulation. Our work provides a new angle in tuning and optimizing hybrid perovskite-based nonlinear optical materials.

Synthesis, characterisation and voltammetric study of dimethylammonium lead iodide perovskite

In the last decade, the most investigated perovskite materials are the hybrid organic-inorganic perovskites (HOIPs) due to their optoelectronic properties and possible application in the production of photovoltaics. This interest has led to an ongoing search for new HOIP variants, alongside thorough investigations of the properties of existing HOIPs. That is why our research in the field of organic-inorganic perovskites is aimed at the synthesis, characterization, and investigation of the electrochemical properties of dimethylammonium lead iodide (DMAPbI3) using voltammetric studies. A modified synthesis of DMAPbI3, differing slightly from the one described in the literature, was performed by combining stoichiometric amounts of lead iodide (PbI2) and dimethylammonium iodide (DMAI) dissolved in acetonitrile. After conducting controlled evaporation, a yellow crystalline powder of DMAPbI3 was obtained. The identity and purity of the obtained compound were confirmed by powder X-ray diffraction (PXRD), infrared (IR) and Raman spectroscopy, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). Investigations on the electrochemical properties of DMAPbI3 by cyclic voltammetry were performed with dichloromethane (DCM) and tetrabutylammonium chloride (TBAC) as the electrolyte. A paraffin-impregnated graphite electrode (PIGE) was used as a working electrode, on which the perovskite microparticles were immobilized. The electrochemical activity of DMAPbI3 is recognized through an intense, broad, and irreversible anodic peak attributed to the oxidation of the constituents to different possible products and the decomposition of the perovskite structure.

Crystal structure of rilpivirine hydrochloride, N6H19C22Cl

A monoclinic C form of rilpivirine hydrochloride, (N6H19C22)Cl, has been obtained and characterized using solid-state 15N, 13C, and 35Cl NMR spectroscopy and multitemperature synchrotron X-ray powder diffraction. The title compound crystallizes in the monoclinic system (space group C2/c, #15) at both room (295.0(2) K) and low (100.0(2) K) temperatures. At room temperature, the following parameters are a = 19.43051(3), b = 13.09431(14), c = 17.10254(18) Å, β = 109.3937(7), V = 4104.48(9) Å3, and Z = 8. The folded molecular conformation of the cation is similar with that of free base rilpivirine with the exception of cyanovinyl group disposition. The anion links cations to infinite chains parallel to the crystallographic c axis using N–H⋯Cl bonds where both amino groups and the protonated pyrimidine ring take part in the H-bonding. The powder patterns have been submitted to the ICDD for inclusion in the Powder Diffraction File™ (PDF®).

Crystal structure of alectinib hydrochloride Type I, C30H35N4O2Cl

The crystal structure of alectinib hydrochloride has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Alectinib hydrochloride crystallizes in space group P21/n (#14) with the following parameters: a = 12.67477(7), b = 10.44076(5), c = 20.38501(12) Å, β = 93.1438(7)°, V = 2693.574(18) Å3, and Z = 4 at 295 K. The crystal structure consists of stacks of molecules along the b-axis, and the stacks contain chains of strong N–H⋯Cl hydrogen bonds. One density functional theory calculation moved a proton from an N atom to the Cl, but another calculation yielded a more chemically reasonable result. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®)

Seeing the Unseen: The Structural Influence of the Lone Pair Electrons in PbWO4.

Pair distribution function (PDF) analysis of the scheelite-type material PbWO4 reveals previously unidentified short-range structural distortions in the PbO8 polyhedra and WO4 tetrahedra not observed in the similarly structured CaWO4. These local distortions are a result of the structural influence of the Pb2+ 6s2 lone pair electrons. These are not evident from the Rietveld analysis of synchrotron X-ray or neutron powder diffraction data, nor do they strongly influence the X-ray PDF (XPDF). This illustrates the importance of neutron PDF (NPDF) in the study of such materials. First-principles density function theory (DFT) calculations show that the Pb2+ 6s2 electrons are hybridized with the O2- 2p electrons near the Fermi level. The presence of local-scale distortions has previously been neglected in studies of structure-functionality relationships in PbWO4 and other scheelite-structured photocatalytic materials, including BiVO4, and this observation opens new avenues for their optimization.

Preparation and Properties of a High-Entropy Wolframite-Type Antiferromagnet, (Mn0.2Co0.2Ni0.2Cu0.2Cd0.2)WO4.

The homogeneous high-entropy wolframite-type solid solution (Mn1/5Co1/5Ni1/5Cu1/5Cd1/5)WO4 was prepared by solid-state reaction at 1000 °C. Elongated "crystals" were grown from the Na2WO4 flux, but their strongly broadened powder X-ray diffraction patterns indicated partial dissolution. Nevertheless, successive annealing of the homogeneous solid solution for 3-4 h at 800, 700, and 600 °C did not bring any sign of dissolution. Thus, the material is kinetically stable at low temperatures although thermodynamically unstable. The long-range antiferromagnetic order was established at TN ∼ 24.8 K. Based on magnetization and specific heat measurements, a magnetic phase diagram was built, demonstrating the presence of an additional field-induced phase. In contrast to the parent MnWO4, no dielectric anomaly has been found down to 2 K.

Synthesis and Properties of the Ba2PrWO6 Double Perovskite.

We report details on the synthesis and properties of barium praseodymium tungstate, Ba2PrWO6, a double perovskite that has not been synthesized before. Room-temperature (RT) powder X-ray diffraction identified the most probable space group (SG) as monoclinic I2/m, but it was only slightly distorted from the cubic structure. X-ray photoelectron spectroscopy confirmed that the initial (postsynthesis) material contained praseodymium in both 3+ and 4+ charge states. The former (Pr3+) disappeared after exposure to UV light at RT. Photoluminescence studies of Pr3+ revealed that Ba2PrWO6 is an insulator with a band gap exceeding 4.93 eV. Pressure-dependent Raman spectroscopy excluded the possibility of a phase transition up to 20 GPa; however, measurements between 8 and 873 K signified that there might be a change toward the lower symmetry SG below 200 K. Electron paramagnetic resonance spectra revealed the presence of interstitial oxygen which acts as a deep electron trap.

Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review

Many analytical methods have been successfully employed for the study of minerals, in particular, vibrational infrared (FTIR) and Raman spectroscopies and X-ray powder diffraction (XRPD). The advantages of the vibrational spectroscopic techniques for identifying and characterizing minerals include: rapid and versatile use; qualitative and quantitative chemical signatures; distinctive chemical fingerprint of a material; indirect determination of the crystal features (polymorphism, isomorphism, coordination, degree of deformation of structural polyhedra); small sample quantity (area less than 1 μm2 for Raman); wide coverage of 4,000 – 50 cm−1 region in a single scan; in situ and direct measurements without sample preparation; nondestructive use; etc. On the other hand, XRPD is a destructive technique that, depending on the method used and the density of the material, requires from a few micrograms up to around 5 grams of sample quantity for analysis. In spite of that, it is a rapid and powerful technique used in mineral studies with relatively straightforward interpretation of the results. During the last decade, portable X-ray powder diffractometers for the nondestructive analysis of art and archeological materials have been developed along with the portable and hand-held vibrational spectroscopy instrument. Here, some advantages and limitations in the process of the complementary use of FTIR and Raman vibrational spectroscopy and XRPD for identification and characterization of minerals are outlined.

Combustion Synthesis of Functionalized Carbonated Boron Nitride Nanoparticles and Their Potential Application in Boron Neutron Capture Therapy

In this research, we developed boron-rich nanoparticles that can be used for boron neutron capture therapy as potential carriers for boron delivery to cancerous tissues. Functionalized carbonated boron nitride nanostructures (CBNs) were successfully synthesized in self-propagating combustion waves in mixtures of high-nitrogen explosives and boron compounds. The products’ composition, morphology, and structural features were investigated using Fourier transform infrared spectroscopy, powder X-ray diffraction, low-temperature nitrogen sorption analysis, thermogravimetric analysis, high-resolution scanning electron microscopy, and high-resolution transmission electron microscopy. The extreme conditions prevailing in combustion waves favor the formation of nanosized CBN hollow grains with highly disordered structures that are properly functionalized on the surface and inside the particles. Therefore, they are characterized by high porosity and good dispersibility in water, which are necessary for medical applications. During biological tests, a concentration-dependent effect of the obtained boron nitride preparations on the viability of normal and neoplastic cells was demonstrated. Moreover, the assessment of the degree of binding of fluorescently labeled nanoparticles to selected cells confirmed the relationships between the cell types and the concentration of the preparation at different incubation time points.

Crystal structure, magnetic and electrical transport properties of titanium-doped half-Heusler alloys Ni1−xTixMnSb

Ni[Formula: see text]TixMnSb polycrystalline alloys in the range [Formula: see text] were synthesized employing the standard solid-phase synthesis method. The crystal, magnetic, as well as electrical properties of the alloys were investigated using neutron powder diffraction and magneto-resistance measurements. The results reveal that the substitution of Ti for Ni within the temperature range of 2.5–300 K does not induce alterations in the crystal and magnetic structures of NiMnSb. The ordered Ni magnetic moment approaches zero. The study of the electrical transport properties of the Ni[Formula: see text]TixMnSb alloys, where [Formula: see text], has demonstrated a half-metallic state at low temperatures and metallic conductivity for temperatures exceeding 160 K. A semiconductor state manifests at titanium concentrations of x = 0.2 and was observed at temperatures below 21 K. The obtained experimental results are elucidated through first-principles theoretical calculations.

The quasi-binary phase diagrams of R 2Fe14B–Ce2Fe14B (R = Nd, Pr) systems

Abstract The phase relations of the R 2Fe14B–Ce2Fe14B (R = Nd, Pr) pseudobinary systems have been investigated by using X-ray powder diffraction, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy and differential thermal analysis. The X-ray powder diffraction results show that continuous solid solutions were formed in this R 2Fe14B–Ce2Fe14B (R = Nd, Pr) pseudobinary systems, and all (R , Ce)2Fe14B solid solutions belong to the tetragonal structure with space group P42/mnm. With the increase in Ce content, the lattice parameters a, c, the peritectic reaction temperatures of the (R, Ce)2Fe14B (R = Nd, Pr) solid solutions decrease linearly, and the cell volume V varies in the form of the regression line. Based on the X-ray powder diffraction results and differential thermal analysis data, the quasi-binary phase diagrams of the R 2Fe14B–Ce2Fe14B (R = Nd, Pr) systems have been established.

Enhanced Anti-Inflammatory Activity of Tilianin Based on the Novel Amorphous Nanocrystals

Tilianin (Til), a flavonoid glycoside, is well-known for its therapeutic promise in treating inflammatory disorders. Its poor water solubility and permeability limit its clinical applicability. In order to overcome these restrictions, an antisolvent precipitation and ultrasonication technique was used to prepare amorphous tilianin nanocrystals (Til NCs). We have adjusted the organic solvents, oil-to-water ratio, stabilizer composition, and ultrasonic power and time by combining single-factor and central composite design (CCD) methodologies. The features of Til NCs were characterized using powder X-ray diffraction (PXRD), scanning calorimetry (DSC), and transmission electron microscopy (TEM). Specifically, the optimized Til NCs were needle-like with a particle size ranging from 90 to 130 nm. PVA (0.3%, w/v) and TPGS (0.08%, w/v) stabilized them well. For at least two months, these Til NCs stayed amorphous and showed an impressive stability at 4 °C and 25 °C. Remarkably, Til NCs dissolved almost 20 times faster in simulated intestinal fluid (SIF) than they did in crude Til. In RAW264.7 cells, Til NCs also showed a better cellular absorption as well as safety and protective qualities. Til NCs were shown to drastically lower reactive oxygen species (ROS), TNF-α, IL-1β, and IL-6 in anti-inflammatory experiments, while increasing IL-10 levels and encouraging M1 macrophages to adopt the anti-inflammatory M2 phenotype. Our results highlight the potential of amorphous Til NCs as a viable approach to improve Til’s anti-inflammatory effectiveness, solubility, and dissolving rate.

Microhardness, Surface Roughness, and Wear Resistance Enhancement of Reinforced Conventional Glass Ionomer Cement Using Fluorinated Graphene Oxide Nanosheets.

Conventional glass ionomer cements (GICs) have been considered the most prevalent restorative material however; the reduced mechanical qualities and decreased wear resistance have been the main challenges facing their wide clinical application. This study was designed to assess the mechanical properties of fluorinated graphene (FG) oxide-modified conventional GIC. Composites of FG/GIC samples were prepared using (Medifil from PROMEDICA, Germany, shade A3) at different concentrations (0wt%) control group and (1wt%, 2wt% and 3wt% FG) groups using cylindrical molds (3mm × 6mm). FG was prepared using hydrothermal technique and characterized using XPERT-PRO Powder Diffractometer system for X-ray diffraction analysis and JEOL JEM-2100 high resolution transmission electron microscope. Vickers' hardness and wear resistance of GI samples were measured. Mechanical abrasion was performed via three-body tooth brushing wear test using ROBOTA chewing simulator coupled with a thermocycling protocol (Model ACH-09075DC-T, AD-Tech Technology Co., Ltd., Leinfelden-Echterdingen, Germany). Comparisons between groups with respect to normally distributed numeric variables were performed using one-way analysis of variance test followed by posthoc test. While paired t-test was utilized for comparing data within the same group. The surface roughness values of GICs (1wt% FG) and (2wt% FG) composites were significantly lower than those of the control and 3wt%FG groups. Vickers' hardness numbers were significantly higher in FG/GICs composites than in the control group (p≤0.05). GIC/FG combinations have sufficient strength to resist the occlusion stresses with improved hardness as compared with conventional GIC. GIC/FG appeared to be a promising restorative material.

The study on mechanism of water–rock reaction in shale oil formation rich in alkaline minerals in Mahu Sag by using supercritical CO2

The Mahu Sag of Junggar Basin, China is rich in alkaline minerals. Generally, the water–rock reactions between hydraulic fluid and alkaline minerals during the hydraulic fracturing process will lead to the precipitation of minerals and block the pore or wellbore, thereby affecting the recovery efficiency. Supercritical carbon dioxide (ScCO2) regarded as a fracturing fluid can significantly improve the recovery of shale oil resources, but there is limited research on the reaction of ScCO2 to water and rock in shale samples rich in alkaline minerals. Therefore, ScCO2 treatment experiments were conducted on shale samples rich in alkaline minerals under 80°C and 10 MPa. Before the experiments, X-ray powder diffraction (XRD) was applied to characterise the mineral properties of the three shale samples. In addition, the duration time of ScCO2 treatment was set at 7 and 20 days to observe the treatment time impacts on the pore structure. Scanning electron microscopy (SEM) analysis and the Mann–Whitney U test were conducted before and after ScCO2 treatment. SEM images show the changes in pore structure. Opening pores are observed due to the interaction between the alkaline mineral and ScCO2. The Mann–Whitney U test shows the changes in fracture toughness. The changes in pore structure also play an important role in fracture toughness. This study investigated the ScCO2 impacts on shale samples rich in alkaline minerals and the analysis of changes in pore structure and fracture toughness can provide theoretical and data evidence to enable on-site optimisation of the ScCO2 fracturing scheme.