X-ray Powder Diffraction Patterns Research Articles

Pressure Dependence of the Structural and Superconducting Properties of the Bi-Based Superconductor Bi2Pd3Se2.

The structural and superconducting properties of the Bi-based compound Bi2Pd3Se2 were investigated over a wide pressure range. The prepared Bi2Pd3Se2 sample was a superconductor with a superconducting transition temperature, Tc, of approximately 3.0 K, which differed from a previous report (Tc of less than 1.0 K). At ambient pressure, the powder X-ray diffraction (XRD) pattern of the Bi2Pd3Se2 sample was consistent with that previously reported for Bi2Pd3Se2. The Rietveld method was used to refine the crystal structure, which had a space group of C2/m (No. 12), as reported previously. This compound showed no clear anomaly due to the charge-density-wave (CDW) transition, as seen from the temperature dependence of magnetic susceptibility. However, the temperature dependence of electrical resistivity indicated a clear anomaly, presumably because of the CDW transition in the low-pressure range; the CDW transition temperature was approximately 230 K. The XRD patterns of the Bi2Pd3Se2 sample were measured at 0.160-22.7 GPa, and the patterns were well analyzed by both the Le Bail and Rietveld refinement methods, showing no structural phase transitions in the above pressure range. The pressure dependence of Tc of Bi2Pd3Se2 was recorded based on the temperature dependence of the electrical resistance, which showed an almost constant Tc at 0-13.7 GPa, and the Tc-pressure (p) behavior was fully discussed.

Thermotropic Structure Phase Transitions and Two Types of Thermochromic Behaviors in a Bromoargentate Cluster [Pr-dabco]2Ag4Br6.

Organic-inorganic silver halide hybrids show abundant phase transitions and thermochromism. However, it is very rare that silver halides exhibit thermochromism related to thermotropic structure phase transition. Herein, a bromoargentate hybrid, [Pr-dabco]2Ag4Br6 (1) (Pr-dabco+ = 1-propyl-1,4-diazabicyclo-[2.2.2]octan-1-ium), with tetranuclear [Ag4Br6]2- clusters was prepared and characterized by microanalysis, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, and thermogravimetric (TG) and differential scanning calorimetry (DSC) techniques. Interestingly, 1 undergoes an irreversible structure phase transition at ∼436 K in the first heating process, which is accompanied by an abrupt color change from colorless to yellow; however, a reversible color change between pale yellow and yellow is observed in the next heating-cooling cycles. Notably, DSC measurement revealed that a reversible phase transition is associated with the change in color between pale yellow and yellow, while the powder X-ray diffraction (PXRD) patterns corresponding to pale yellow and yellow phases are quite similar to each other. These observations demonstrate that thermochromism in the next heating-cooling runs is associated with a reversible structure phase transition, which perhaps concerns the disorder-order transformation of alkyl chains in the cationic ligand [Pr-dabco]+, and relevant to the anharmonic fluctuations of the Ag-Br and Ag-N bonds, a strong electron-phonon coupling effect is seen within the bromoargentate cluster.

Preparation of Polyethylene Clay Composites via Melt Intercalation Using Hydrophobic and Superhydrophobic Organoclays and Comparison of Their Textural, Mechanical and Thermal Properties.

Polymer clay nanocomposites, which can exhibit many superior properties compared to virgin polymers, have gained increasing interest and importance in recent years. This study aimed to prepare composites of two organoclays with unusual ratios and different degrees of lyophilicity with low-density polyethylene and compare their textural structures and thermal and mechanical properties with those of virgin polymer. For this purpose, firstly, organoclays, hydrophobic and superhydrophobic organoclays (OC and SOC), were prepared by solution intercalation method using cetyltrimethylammonium bromide with and without addition of a hydrocarbon substance. Then, using both organoclays, polyethylene organoclay composites were prepared and characterized using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Additionally, tensile and hardness tests were performed to determine the mechanical properties of the composites, and differential scanning calorimetry (DSC) thermograms were taken to examine their thermal behavior. XRD patterns and HRTEM images of hydrophobic and superhydrophobic organoclays and the composites show that the characteristic smectite peak of the clay shifts to the left and expands, that is, the interlayer space widens and, in the composites, it deforms immediately at low clay ratios. HRTEM images of the composites prepared especially with low clay ratios indicate that a heterogeneous dispersion of clay platelets occurs, indicating that nanocomposite formation has been achieved. On the contrary, in the composites prepared with high clay ratios, this dispersion behavior partially turns into aggregation. In the composites prepared using up to 20% by weight of superhydrophobic organoclay, extremely stable and continuous improvements in all mechanical properties were observed compared to those of the composites prepared using hydrophobic organoclay. This indicates that by using superhydrophobic organoclay, a ductile nanocomposite of polyethylene containing inorganic components in much higher than usual proportions can be prepared.

Synthesis, characterization, antimicrobial, molecular docking simulation, and antitumor assays of nanometric complexes based on new thiazole Schiff base derivative

For further pharmaceutical applications, a novel Schiff base derivative of aminothiazole and its Co (II), Cu (II), Zn (II), and Th (IV) chelates were designed and prepared. For this purpose, 2‐aminothiazole and 2,4‐dihydroxybenzaldehyde have been coupled before the complexation reaction with the metal salts. Elemental analysis, FT‐IR, 1HNMR, UV–Vis spectra, transmission electron microscopy (TEM), X‐ray powder diffraction (XRD), molar conductance, and magnetic moment measurements were used to determine the structural formula of the ligand and its produced chelates. The acquired data pointed out that the ligand was chelated with metal through the nitrogen of azo group and deprotonated ortho phenolic oxygen atoms. In Cu (II) complex the copper ion chelated with two ligand molecules, whereas in other complexes the metal binds with one molecule only of ligand. It was shown by XRD patterns and high‐resolution TEM images that the complex particles had a uniform distribution across the chelates' surfaces and were nanometric in size. Extremely, antimicrobial and anticancer activity for the prepared ligand and complexes were investigated, which showed high activity, especially after complex formation. Docking studies have been performed to predict the compounds' efficacy as antitumor agents through their interaction with the co‐crystal structure of proteins for breast cancer cells (PDB ID: 3S7S) and protein of liver cancer 2 (PDB ID: 2JW2). The experimental results of the anticancer activity showed promising results, especially for Cu (II) compound which exhibited the greatest antitumor efficacy (IC50 = 12.81 μg/ml) contra HepG‐2 carcinoma and Mcf‐7 cells (IC50 = 18.92 ± 0.91 μg/ml). Antimicrobial activity against the strains Klebsiella pneumoniae (K. pneumoniae), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), C. albicans (C. albicans), and Aspergillus niger (A. niger) also gave very promising results when it is compared with the standard drugs.

Pilanesbergite: a new rock-forming mineral occurring in nepheline syenite from the Pilanesberg Alkaline Complex, South Africa

Abstract. The new mineral pilanesbergite, with the ideal formula Na2Ca2Fe2Ti2(Si2O7)2O2F2, was found in a nepheline syenite, locally known as green foyaite, from the Pilanesberg Complex located in the North West Province of South Africa. Pilanesbergite occurs in green foyaite in association, and partly intergrown, with aegirine. The two minerals share an assemblage of inclusions, comprising euhedral nepheline, titanite and minor sodalite. Pilanesbergite belongs to the wöhlerite group and is isomorphic with låvenite, normandite and madeiraite. It is related to these species through the homovalent chemical substitutions Mn2+↔Fe2+ and Zr4+↔Ti4+. The empirical formula calculated on the basis of 18 anions is Na2.00(Ca1.74Na0.26)Σ2.00(Fe1.00Mn0.52Ca0.49Zr0.05)Σ2.06(Ti1.69Zr0.14Mg0.09Nb0.08)Σ2.00(Si2O7)2.00O1.84F2.16 (Z=2). The new mineral is translucent with a brown orange colour and a brownish streak. The Mohs hardness is estimated between 5 and 6 by comparison with låvenite, and no cleavage is observed. Measured and calculated densities are Dmeas=3.47 g cm−3 and Dcalc=3.40 g cm−3. In the thin section the pleochroism is strong, between straw yellow and orange red, while in immersion the strong pleochroism is observed between light yellow (α) and yellowish orange (γ). The crystals are optically biaxial (+) with α=1.743(3), β=1.768(3), γ=1.795(5) and a 2 V angle close to 90∘. The crystal structure is monoclinic (P21/a), with the unit-cell parameters a=10.7811(2), b=9.7836(1), c=7.0348(1) Å, β=108.072(2)∘ and V=705.41(2) Å3, and has been refined to R1=2.06 %. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (h k l)] are 3.219 (60) (310), 2.851 (100) (12-2), 2.802 (51) (320), 2.743 (27) (22-2), 2.423 (19) (40-2) and 1.723 (19) (44-2). Pilanesbergite formed under relatively reducing conditions from an agpaitic nepheline syenite magma that had evolved by fractional crystallization mainly of aegirine. Further crystallization of arfvedsonite caused an increase in oxygen fugacity and a change towards higher Mn/Mn+Fe of the magma, causing a change of mineral composition from pilanesbergite towards normandite.

Natromelansonite, Na3Zr[Si7AlO19]⋅4–5H2O, a new member of the rhodesite mero-plesiotype series from Mont Saint-Hilaire, Quebec, Canada

AbstractNatromelansonite, Na3Zr[Si7AlO19]⋅4–5H2O, was found at the Poudrette (Demix) quarry, Mont Saint-Hilaire, Quebec, Canada in a highly altered pegmatite together with a clay mineral, steacyite, polylithionite and rhodochrosite. It occurs as an outer zone of tabular crystals to 0.1 × 0.3 × 1 mm in size flattened on (001). The inner zone is made of melansonite. The mineral is grey with white powder colour and vitreous lustre. The cleavage is parallel to {010}, perfect. The Mohs hardness is 3.5. The mineral has green fluorescence under short-wave ultraviolet light. The Dcalc is 2.31 g/cm3. The infrared spectrum is reported. The composition (wt.%, average of 8 analyses) is Na2O 10.08, K2O 1.72, CaO 0.24, BaO 0.32, MnO 0.10, Al2O3 6.86, Y2O3 0.35, Yb2O3 0.55, SiO2 56.23, ZrO2 14.78, H2O 9.52, total 100.75. The empirical formula calculated on the basis of O = 23 apfu and H = 8 apfu is Na(□Na0.38Ca0.02Mn0.01)2(Na0.70K0.28Ba0.02)Σ1.00(Zr0.91Y0.02Yb0.02)Σ0.95(Si7.08Al1.02)Σ8.10O19⋅4H2O. The mineral is monoclinic, P21/m, a = 6.5156(3) Å, b = 24.061(1) Å, c = 6.9759(6) Å, β = 90.453(5)° and V = 1093.61(9) Å3 and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 12.02(100)(020), 6.97(89)(001), 6.51(39)(100), 3.416(37)(160), 3.062(42)($\bar{1}$61, 102, 161 and $\bar{1}$12), 3.018(38)(230 and 042), 2.864(40)(240 and 132). The crystal structure, solved and refined from single-crystal X-ray diffraction data (R1 = 0.042), is based on a double sheet of tetrahedra (T) and a sheet of octahedra (O) that alternate along the [010] direction forming a TOT structure typical for members of the rhodesite mero-plesiotype series.

Arsenoústalečite, Cu12(As2Te2)Se13, a new mineral, and crystal structures of arsenoústalečite and stibioústalečite

AbstractArsenoústalečite is a new mineral discovered in a sample collected from the abandoned Ústaleč deposit near Horažďovice, SW Bohemia, Czech Republic. It occurs as rare anhedral grains, up to 40 μm in size, in a calcite gangue, associated with stibioústalečite, hakite-(Hg), berzelianite and uraninite. Arsenoústalečite is dark grey, with a metallic lustre. Mohs hardness is ca. 3½–4; calculated density is 5.730 g/cm3. In reflected light, arsenoústalečite is pale grey with a yellowish shade; it is isotropic. Internal reflections were not observed. Reflectance values for the four COM wavelengths in air [R (%) λ (nm)] are: 33.3 (470); 33.1 (546); 33.0 (589); and 32.9 (650). The empirical formula of arsenoústalečite is (Cu5.81Ag0.17)Σ5.98(Cu5.95Fe0.02Zn0.02Hg0.01)Σ6.00(As1.40Sb0.87Te1.73)Σ4.00(Se10.30S2.32)Σ12.61. The ideal formula is Cu12(As2Te2)Se13, which requires (in wt.%) Cu 34.76, As 6.83, Te 11.63, Se 46.78, total 100.00. Arsenoústalečite is cubic, I$\bar{4}$3m, with unit-cell parameters a = 10.6580(19) Å, V = 1210.7(6) Å3 and Z = 2. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I, %) hkl] are: 3.077 (100) 222, 2.848 (10) 321, 1.946 (12) 521, 1.884(52) 440 and 1.608(21) 622. According to the single-crystal X-ray diffraction data (R1 = 0.0285 on the basis of 334 unique reflections with Fo > 4σFo and 24 refined parameters), arsenoústalečite is isotypic with other tetrahedrite-group minerals. The crystal structure of co-existing stibioústalečite, with an empirical formula of (Cu5.69Ag0.07)Σ5.76(Cu5.80Zn0.13Fe0.06Hg0.01)Σ6.00(Sb1.82As0.42Te1.76)Σ4.00(Se9.52S3.10)Σ12.62 and unit-cell parameters a = 10.6975(16) Å, V = 1224.2(5) Å3 and Z = 2, was refined to R1 = 0.0191 on the basis of 267 unique reflections with Fo > 4σFo and 24 refined parameters. Structural relationships and crystal-chemistry of both members of the ústalečite series are discussed. Arsenoústalečite is named after its type locality, the Ústaleč deposit and its chemical composition. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022-116).

Quaternary In0.15Sn0.85(Se0.95S0.05)2 crystal: Synthesis, characterization, and its multiple applications

The applications of quaternary In0.15Sn0.85(Se0.95S0.05)2 (ITSS) crystals were investigated as a near-infrared (NIR) optoelectronic switching device, vacuum pressure sensor, and photocatalyst. The remarkable photoresponse is demonstrated by the NIR crystal-based ITSS photodetector for various applied external biasing voltage. The NIR photodetector exhibits fast switching with a photoresponsivity of 147 mA/W. The crystals were investigated as a vacuum pressure sensor in the vacuum range ranging from 0 mbar to −1033 mbar as a function of electrical resistance. The n-type grown quaternary crystals have a direct optical bandgap of 1.38 eV. The photocatalytic activity was assessed by varying the concentration of methylene blue (MB) and the characteristics of the photocatalytic process were computed using the Langmuir-Hinshelwood kinetic model. Raman spectroscopy was performed on the grown crystals at temperatures ranging from 98 K to 448 K, with a step of 50 K to study the structural stability. The Lorentzian function was fitted to the experimental data to determine the peak width and peak position. The quaternary ITSS crystals were grown by the mechanical alloying process. The stoichiometry and layered growth mechanism of grown ITSS crystals were confirmed through energy dispersive X-ray spectroscopy (EDS) with mapping and field emission scanning electron microscopy (FESEM), respectively. The hexagonal crystal structure was characterized by the powder X-ray diffraction (PXRD) pattern, and the electrical resistance was studied as a function of temperature.

Studies on structural, optical and microwave dielectric properties of double perovskite Sr2Fe1+xNb1-xO6, ceramics synthesized by solid state route

The solid solution of Sr2Fe1+xNb1-xO6, 0.015 ≤ x ≤ 0.030 double perovskite ceramics has been synthesized by mixed oxide route. In this paper, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy have been used to investigate the structure stability of double perovskite ceramics, Sr2Fe1+xNb1-xO6, 0.015 ≤ x ≤ 0.030 Impedance analysis and photoluminescence (PL) spectroscopy were used to investigate the ceramic's dielectric and optical properties respectively. The XRD pattern revealed the single phase tetragonal structure along with space group I4/m. The findings demonstrate that the binding strength and stability of double perovskite increase with increasing contents (x). Increasing frequency may encourage carrier hopping and mobility, but the free carrier may also be expected to conduct the bound charge at a high frequency. Fe3+ and Nb5+ replace smaller cations at the B-site, causing a cationic disorder that causes oxygen vacancies in the lattice skeleton and boosts conductivity. Tangent loss decreases with increasing frequency, which is reported in this work. According to the PL analysis, an excitation energy of 2.22 eV at a wavelength of 560 nm was measured, which is appropriate for the generating of green light lasers.

Characterization, Antioxidant and Cytotoxic Evaluation of Demethoxycurcumin and Bisdemethoxycurcumin from Curcuma longa Cultivated in Costa Rica

The biological activities of curcuminoids, the main polyphenol constituents of Curcuma longa (turmeric), have been the subject of many studies in recent years. However, these studies have focused on the major active compound, curcumin (CUR), while other important constituents, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDM) have been less studied and reported in the literature regarding their bioactivity as well as their isolation and solid-state characterization. Hence, in this study, DMC and BDM were isolated using pressurized liquid extraction (PLE) followed by column chromatography and crystallization. HRMS and 1H and 13C NMR were used to characterize them. Solid-state characterization was performed through powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) techniques. Further, powder dissolution profiles were performed in two media, antioxidant and cytotoxic activities were determined through 2,2-diphenyl-1-picrylhidrazyl (DPPH) and an MTT assay on gastric adenocarcinoma (AGS), colorectal adenocarcinoma (SW-620), and hepatocellular carcinoma (HepG2) cell lines. DMC and BDM were extracted from Curcuma longa cultivated in Costa Rica, using pressurized liquid extraction (PLE), then isolated and purified, combining column chromatography and crystallization techniques. The highly pure solids obtained were shown to be crystalline with an amorphous component. Although the PXRD pattern of BDM suggested a high amorphous component, the crystal exhibited a well-defined and faceted shape. Meanwhile, DMC crystallized in a botryoidal habit, and this constitutes the first report for this compound. On the other hand, BDM was slightly more soluble than DMC, which in turn showed an antioxidant IC50 value 28% higher than BDM (12.46 and 17.94 µg/mL, respectively). In respect to the cytotoxic effects, DMC showed a better IC50 value than BDM for both the SW-620 and AGS cell lines, while BDM exhibited a better IC50 value than DMC against the HepG2 cell line (64.7 μM). In terms of selectivity, BDM and DMC had the highest SI value for SW-620 cells compared to non-tumoral cells, while both compounds also displayed the best cytotoxic effect against these colon adenocarcinoma SW-620 cells, indicating BDM and DMC as potential chemotherapeutic drugs.

Stability of Zr-Based UiO-66 Metal-Organic Frameworks in Basic Solutions.

Although Zr-based metal-organic frameworks (MOFs) exhibit robust chemical and physical stability in the presence of moisture and acidic conditions, their susceptibility to nucleophilic attacks from bases poses a critical challenge to their overall stability. Herein, we systematically investigate the stability of Zr-based UiO-66 (UiO = University of Oslo) MOFs in basic solutions. The impact of 11 standard bases, including inorganic salts and organic bases, on the stability of these MOFs is examined. The destruction of the framework is confirmed through powder X-ray diffraction (PXRD) patterns, and the monitored dissolution of ligands from the framework is assessed using nuclear magnetic resonance (NMR) spectroscopy. Our key findings reveal a direct correlation between the strength and concentration of the base and the destruction of the MOFs. The summarized data provide valuable insights that can guide the practical application of Zr-based UiO-66 MOFs under basic conditions, offering essential information for their optimal utilization in various settings.

Regorafenib: A comprehensive drug profile.

Regorafenib is a small molecule tyrosine kinase inhibitor administered orally drug, act by inhibiting the activity of the VEGF receptors. It is used for the treatment of patients with metastatic colorectal cancer (CRC), advanced gastrointestinal stromal tumors, and hepatocellular carcinoma. This comprehensive profile on regorafenib includes an original data as well as data collected from the literature on Profiles of Methods of Drug Synthesis, different Physical Drug Profiles, Drug Analytical methods and Pharmacological profile (ADME). This chapter is divided into five main sections: General Description of the drug, Physical Characteristics, Methods of Preparation, Methods of Analysis, Pharmacology and List of References. These main sections are further divided to many sub-titles to cover most aspect of the drug in the light of the available literature. Among these sub-titles are the formulae, Elemental Analysis, physical characteristics which include constant of ionization, solubility, X-ray powder diffraction pattern, TGA, thermal conduct and spectroscopic and stability. Additionally, analytical techniques including Electrochemical, Spectrophotometric and chromatographic methods, ADME profiles and pharmacological effects were also discussed. Furthermore, methods and schemes are outlined for the preparation of the drug substance.

Enhancing the solubility and dissolution rate of piperine via preparation of piperine–hydroxypropyl methylcellulose 2910 solid dispersion system using freeze-drying method

Context: Piperine is the main secondary metabolite isolated from the family Piperaceae. This biologically active ingredient has many pharmacological effects, though its low water solubility limits its absorption in gastrointestinal fluid. Aims: To improve piperine’s solubility and dissolution rate by incorporating it into a solid dispersion system with the hydrophilic polymer hydroxypropyl methylcellulose (HPMC) 2910 via the freeze-drying method. Methods: Three different piperine:polymer ratios – 1:1, 1:2, and 2:1 (w/w) – were prepared. A physical mixture was also prepared in a 1:1 (w/w) ratio for comparison. The physicochemical properties of the samples were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The solubility and dissolution tests were conducted in distilled water. Results: The solid dispersion characterization indicated a decrease in the melting points and endothermic peaks in the DSC analysis, a decrease in peak intensity in the PXRD patterns, no chemical interactions between active substances and polymers in the FTIR analysis, and significant morphological changes in the SEM analysis. The solubility test revealed the highest increase in piperine solubility (7.88-fold increase) for the 1:2 solid dispersion. Moreover, the 1:2 solid dispersion in the dissolution test led to the greatest amount of dissolved piperine (56.445 ± 1.13%). Conclusions: The piperine–HPMC solid dispersion system improved the solubility and dissolution rate of piperine.

Evolution of Mn-Bi2O3 from the Mn-doped Bi3O4Br electro(pre)catalyst during the oxygen evolution reaction.

Mn-doped Bi3O4Br has been synthesized using a solvothermal route. The undoped Bi3O4Br and Mn-Bi3O4Br materials possess orthorhombic unit cells with two distinct Bi sites forming a layered atomic arrangement. The shift in the (020) plane in the powder X-ray diffraction (PXRD) pattern confirms Mn-doping in the Bi3O4Br lattice. Elemental mapping indicated 7% Mn doping in the Bi3O4Br lattice structure. A core-level X-ray photoelectron study (XPS) indicates the presence of BiIII and MnII valence-states in Mn-Bi3O4Br. Doping with a cation (MnII) containing a different charge and ionic radius resulted in vacancy/defects in Mn-Bi3O4Br which further altered its electronic structure by reducing the indirect band gap, beneficial for electron conduction and electrocatalysis. The irreversible MnII to MnIII transformation at a potential of 1.48 V (vs. RHE) precedes the electrochemical oxygen evolution reaction (OER). The Mn-doped electrocatalyst achieved 10 mA cm-2 current density at 337 mV overpotential, while the pristine Bi3O4Br required 385 mV overpotential to reach the same activity. The pronounced OER activity of the Mn-Bi3O4Br sample over the pristine Bi3O4Br highlights the necessity of MnII doping. The superior activity of the Mn-Bi3O4Br catalyst over that of Bi3O4Br is due to a low Tafel slope, better double-layer capacitance (Cdl), and small charge-transfer resistance (Rct). The chronoamperometry (CA) study depicts long-term stability for 12 h at 20 mA cm-2. An electrolyzer fabricated as Pt(-)/(+)Mn-Bi3O4Br can deliver 10 mA cm-2 at a cell potential of 2.05 V. The post-CA-OER analyses of the anode confirmed the leaching of [Br-] followed by in situ formation of Mn-doped Bi2O3 as the electrocatalytically active species. Herein, an ultra-low Mn-doping into Bi3O4Br leads to an improvement in the electrocatalytic performance of the inactive Bi3O4Br material.

Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction.

Valence tautomeric complexes (VT) are promising systems for creating molecular devices. From this viewpoint, valence tautomeric complexes with a hysteresis loop on the magnetic curve are of special interest as potential memory elements. The hysteresis loop is a consequence of retarded structural rearrangements which investigation is an actual problem. Recently, we have described a new VT transition taking place in a bis-dioxolene cobalt complex with imino-pyridine having a TEMPO substituent (A. A. Zolotukhin, et al., Inorg. Chem., 2017, 56, 14751-14754). Valence tautomeric transformation occurs with a hysteresis loop and is accompanied by a phase transition. The phase transition taking place during cooling is accompanied by crystal destruction. This fact makes it impossible to monitor the structural changes responsible for the hysteresis loop. The current research attempts to resolve this problem. A nickel compound of the same composition (TEMPO-imino-pyridine)Ni(3,6-DBSQ)2 was synthesized and characterized. It was established to be isostructural with the cobalt complex. It was used as an inert matrix for the dilution of the VT cobalt complex. The number of solid solutions with Co/Ni ratios of 1 : 1, 1 : 2, 1 : 4, and 1 : 8 was obtained. Variable temperature magnetic susceptibility measurements show that VT transformation with a hysteresis loop takes place in all solid solutions. The hysteresis loop is shifted to low temperatures primarily due to the shifting of its low-temperature boundary with dilution. The hysteresis width does not change significantly with dilution. DSC detected that transformations are accompanied by phase transitions at different temperatures at cooling and heating. The phase transition at the first cooling occurs at slightly lower temperatures compared with subsequent cycles. These temperatures correspond to the transition temperatures detected from the magnetic curves. The phase transition during the first cooling is accompanied by crystal destruction. Physical destruction takes place in the crystals of all solid solutions. X-ray diffraction powder patterns confirm that phase transition is accompanied by considerable reorganization of the crystal structure typical for the first order transitions. The unit cell volume of solid solutions is larger than that of pure complexes. Especially calculated crystal invariom indicated that the "lattice energy" in a solid solution is the lowest compared with that in "pure" nickel and cobalt complexes.

Influence of annealing temperature on persistent luminescence in BaAl2O4:Eu2+/Eu3+ nanocrystals and its application for latent fingerprint detection.

The luminescent properties of europium (Eu) doped BaAl2O4 phosphors were strongly influenced by post-annealing temperatures for blue-green persistent luminescence and latent fingerprints (LFPs). The X-ray powder diffraction patterns of the BaAl2O4: 1 mol% Eu nanophosphor, annealed between 1000 and 1300 °C, indicated a hexagonal ferroelectric phase. The X-ray photoelectron spectroscopy (XPS) revealed that the Ba atoms occupied two different sites in the BaAl2O4. The XPS and photoluminescence (PL) results revealed the presence of Eu3+ and Eu2+ states. The Eu-doped BaAl2O4 showed the characteristic red emission of Eu3+ at 251 and 464 nm excitations, while excitations at 340 and 380 nm showed yellowish-green emission. Strong evidence of energy transfer between a charge transfer band and the different energy levels of Eu2+ and Eu3+ ions was obtained. The existence of the Cr ion impurity in the aluminates was confirmed with UV-VIS diffuse reflectance and PL spectroscopy. The present results suggested that and O''i defects have introduced electron and hole traps in the host that acted as luminescent centers for persistent luminescence. LFPs detection using BaAl2O3:Eu2+/Eu3+ phosphor showed an excellent marking agent for applications in forensic science.

Development of PCL/TiO2 composite as an efficient antibacterial, anticancer drug and biocompatible properties

The present investigation focuses on the synthesis of hybrid materials (organic/inorganic) for biomedical applications using titanium dioxide (TiO2) and polycaprolactone (PCL). Nano-structured titania produced from a newly synthesized titanium(IV) heteroleptic complex using sol–gel method. In order to develop PCL/TiO2 nanocomposite, three different compositions (30 wt%, 40 wt% and 50 wt%) of TiO2 was processed with biodegradable PCL matrix via sol–gel technique. The resulted nanocomposite material was characterized using powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) analyses. PXRD patterns of the hybrid material revealed that the crystallinity of the PCL/TiO2 was found to be decreased as the amount of nano TiO2 got increased in the PCL matrix and crystallites size was observed as 27 nm for 50 wt% composite. FTIR spectra indicated the interaction between the nano titania and functional group of the PCL. Surface morphology and elemental composition were analysed using FE-SEM and EDX. Using the well diffusion technique, PCL/TiO2 composites were tested for antibacterial activity against four infective microbiological strains such as Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli). PCL/TiO2 composite (50 wt%) demonstrated good results against S. aureus (16 mm) and E. coli (17 mm) strains. Protein binding interaction of composite material with bovine serum albumin (BSA) exhibited highest binding affinity for 50 wt% of PCL/TiO2 (Kb = 0.88 × 104 M−1). Biocompatibility of very PCL/TiO2 composite was evaluated against osteosarcoma cancer (MG 63) cell line and observed half-maximal inhibitory concentration (IC50) value as 35.37 µg/mL estimated by MTT assay. Apoptosis was also carried out by using acridine orange/ethidium bromide (AO/EB) staining.

Kodamaite, Na3(Ca5Na)6Si16O36(OH)4F2·14−xH2O, x = ∼5, A New Layered Alkali-Alkaline Earth Fluorosilicate-Hydrate and Member of the Gyrolite Supergroup, from Mont Saint-Hilaire, Quebec, Canada: Description, Crystal-Chemical Considerations, and Genetic Implications

Abstract Kodamaite, ideally Na3(Ca5Na)6Si16O36(OH)4F2·14−xH2O, where x = ∼5, is a new mineral discovered at the Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada. It develops in spherulitic aggregates up to ∼2 mm across, comprising thin, platy to bladed crystals, with individual crystals averaging <0.05 × 0.5 mm. Crystals are dominated by the form pinacoid {100} with a lesser {hk0} form and typically range from tan to creamy-yellow to white in color, less often being colorless, light or dark green, or white. Associated minerals include eudialyte-group minerals, aegirine, a clinoamphibole, serandite-group minerals, natrolite, molybdenite, pyrite, fluorite, sodalite, catapleiite, rinkite-group minerals, albite, villiaumite, pyrochlore, fluorapatite, microcline, and erdite. Kodamaite is translucent to transparent and has a silky to slightly vitreous luster, a white streak, a Mohs hardness of ∼2, a perfect {001} cleavage, a sectile tenacity, and a smooth fracture. The mineral shows a pronounced bluish-white fluorescence under both long- and medium-wave ultraviolet radiation, much less so under short-wave radiation. The calculated density is 2.16 g/cm3. Optically, kodamaite is presumed to be optically biaxial, but its optical properties could not be readily discerned. An average nD = 1.507 (for λ = 590 nm) was calculated using data from the refined crystal structure. It is non-pleochroic, has low birefringence (first-order gray) and crystals are length slow and show no dispersion. The Raman spectrum shows two strong peaks at 607 (O–Si–O stretch) and 1070 cm−1 (Si–O stretch), along with several weaker ones over the range of ∼100–500 cm−1 arising from a combination of alkali–O bonds and lattice vibrations. An average of 11 energy-dispersive spectroscopic analyses gave Na2O 8.55, CaO 16.80, Fe2O3 0.39, SiO2 60.76, F 2.57, Cl 0.11, H2O (calc.) 12.49, O=F −1.08, O=Cl −0.02, total 100.98 wt.%. The empirical formula [based on Σ16(Si+S6+) cations apfu] is Na3.14(Ca4.72Na1.30Fe0.08)Σ6.00(Si15.92S6+0.08)Σ16O36.09(OH3.82F0.13Cl0.08)Σ4.00F2·9H2O. The crystal-structure formula is NaNa2Ca2Ca2(NaCa)2Si16O36(OH)4F2·14−xH2O with x = ∼5, which may be simplified to Na3(Ca5Na)6Si16O36(OH)4F2·9H2O. The mineral is triclinic, crystallizing in space group P, with a = 9.609(2), b = 9.630(2), c = 15.739(3) Å, α = 75.21(3), β = 85.22(3), γ = 60.12(3) °, V = 1219.3(1) Å3, Z = 1. The strongest six lines of the X-ray powder-diffraction pattern [dobs in Å (Iobs) (hkl)] are: 15.197 (100) (001), 3.833 (7) (004), 3.068 (7) (005), 2.996 (18) , 2.780 (14) , 1.831 (9) . The crystal structure was refined to R = 8.43%, wR2 = 23.50% using single-crystal X-ray diffraction data (1578 reflections with Fo > 4σFo). Kodamaite has a strongly layered crystal structure, with a motif based on single sheets of SiO4 tetrahedra (T) that are composed of regular, planar, six-membered rings (with a u6 arrangement; apices of the tetrahedra all point in a common direction, up = u). The regular rings of tetrahedra are linked in the (001) plane by SiO3(OH) tetrahedra, whose apical directions are opposite to those in the ring (down; d). Linkages between the two types of tetrahedra give rise to an irregular, six-membered ring of tetrahedra with a u2du2d arrangement. The combination of regular and irregular six-membered rings of tetrahedra produces a three-connected (63)4 net. Two symmetry-related T layers, designated T2 and −T2, sandwich a closest-packed layer of edge-sharing Naφ6 and Caφ6 octahedra and Naφ8 polyhedra (φ = undefined ligand; O, F), forming a quasi-layer of octahedra (O). Refinement of the crystal structure shows the Ca sites are dominated by Ca with small amounts of Na (9:1 ratio); one of the sites has an equal concentration of Ca and Na, suggesting ordering of the two in a single site. The arrangement of T and O layers produces a TOT module with the interlayer space being occupied by H2O groups. Charge-balance arguments and observed anion–anion distances support ordering of F in a single, distinct site. The complete crystal structure of kodamaite conforms to a scheme, which is similar to that of the closely related minerals martinite and ellingsenite. All are classed in the gyrolite supergroup, which includes minerals in five groups, all having similar but distinct crystal-structure features. The crystal-chemical relationships among the groups and implications in terms of the stacking of various modules are presented and discussed. Kodamaite is a late-stage mineral that developed under hydrothermal conditions at T < 200 °C, most likely under high to very high alkalinity. The interaction of these fluids with pre-existing minerals, including pectolite, eudialyte-group minerals, and sodalite, is likely essential to the formation of the kodamaite.

Structural, optical and photoluminescence properties of BaLa2ZnO5: Eu3+ phosphor: A prospective red-emitting phosphor for LED applications

Herein, we report the synthesis of red-emitting Eu3+-activated BaLa2ZnO5 phosphors using a high-temperature solid-state reaction technique. The phase confirmation and crystal structure were established through X-ray powder diffraction patterns. Density-functional theory calculations revealed an indirect bandgap in the material. The bandgaps of both undoped and doped BaLa2ZnO5 phosphors were analyzed using diffuse reflectance spectra. The influence of Eu3+ doping on the bandgap was confirmed by applying the Kubelka-Munk function to the diffuse reflectance spectra. The effects of doping on the surface morphology and elemental composition were investigated through field emission scanning electron microscopy and energy-dispersive spectroscopy, respectively. Additionally, X-ray photoelectron spectroscopic studies were conducted to analyze the electronic structure, chemical states and impact of doping on the crystal structure. Using near ultraviolet excitation at 329 nm, the synthesized phosphor exhibited strong red emission attributed to various 5D0 → 7FJ transitions. Concentration quenching phenomena were observed due to dipole-dipole interactions. Judd-Ofelt analysis was performed to elucidate the coordination nature of the doping element in the host lattice. Excellent thermal stability was observed with an activation energy of 0.64 eV for discharging via lattice vibrations. The better color purity (98–99.3 %) and stable Commission Internationale de l’Elcairage coordinates in the red region of the gamut suggest that the prepared phosphor material holds potential as an efficient candidate for ultra violet and blue light-emitting diode chips, as well as an efficient component in the fabrication of white light-emitting diodes.

Karakterisasi Pembentukan Ko-kristal Tenoksikam-Asam Malat dan Evaluasi Kompresibilitas dan Tabletabilitasnya

Tenoxicam is a non-steroidal anti-inflammatory drug which has poor compressibility and compactibility. One way to change the compressibility and compactibility of a material is to use co-crystallization techniques The aim of this research is to characterize the formation of co-crystal between tenoxicam and malic acid and evaluate their compressibility and tabletability. Tenoxicam-malic acid co-crystal were prepared using the ultrasound-assisted solution co-crystallisation (USSC) method with the addition of ethanol solvent at the same molar ratio. The USSC result was characterized by polarization microscopy, powder X-ray diffraction, and thermal analysis methods. Evaluation of compressibility and tabletability (tensile strength and elactic recovery) was carried out on tenoxicam-malic acid co-crystal and intact tenoxicam. Characterization of the USSC result indicated the formation of tenoxicam-malic acid co-crystal, which were characterized by crystal habit, powder X-ray diffraction patterns, and DSC thermograms that were specific and different from intact tenoxicam and malic acid. Compressibility evaluation results show that the tenoxicam-malic acid co-crystal is in the good flow properties category, while the intact tenoxicam is in the poor flow properties category. The tensile strength of tenoxicam-malic acid co-crystal is higher than that of intact tenoxicam at the same compression strength (40 kg/cm2). Tenoxicam-malic acid co-crystal showed lower elastic recovery compared to intact tenoxicam. These results can be concluded that tenoxicam-malic acid co-crystals have been successfully prepared using the USSC method and have better compressibility and tabletability than intact tenoxicam.