X-ray Powder Diffractograms Research Articles

Forensic characterization of spontaneous acetone peroxide formation from consumer-aged 2-propanol

Numerous instances of well-aged consumer-grade 2-propanol (isopropanol) containing solid primary explosive material have been reported and turned over to the authorities. Herein, one such sample that was turned over to the Bureau of Alcohol, Tobacco, Firearms and Explosives has been analytically characterized to understand the solid primary explosive material as well as the liquid composition for forensic purposes. Upon examination by several analytical methodologies, the liquid phase of the sample contained isopropanol with measurable amounts of species indicative of isopropanol degradation and precursors to triacetone triperoxide. These species included acetone, methanol, acetic acid, isopropyl acetate, hydroxy-propanone, linear acetone peroxides, several atypical linear acetone peroxides species, and cyclic acetone peroxides (e.g., triacetone triperoxide). The solid material in the container was predominately triacetone triperoxide as well as diacetone diperoxide and tetraacetone tetraperoxide. Microscopic properties and x-ray powder diffractograms of the solid material recovered from the aged isopropanol differed from traditionally synthesized triacetone triperoxide. This comprehensive analysis serves as a reference and aid in analysis for forensic laboratories when alleged samples of spontaneously formed triacetone triperoxide are encountered.

Cold and Liquid Crystal Properties of Square-Planar Copper(II) Versus Nickel(II)- Iminophenolate/Naphthalen-2-Olate Schiff Base Complexes.

Reaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸ2N,O]Ni/Cu(II), [Ni(L1)2] (1) and [Cu(L1)2] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸ2N,O]Ni/Cu(II), [Ni(L2)2] (3) and [Cu(L2)2] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N2,O2-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples. Thermal analyses by differential scanning calorimetry (DSC) and polarized light microscopic (PLM) indicate the copper(II) complexes to exhibit cold crystal (2) and liquid crystal (4) property. Cyclic voltammograms suggest an irreversible electrochemical process with two one electron charge transfer processes in N,N-dimethylformamide. Variable temperature magnetic measurements at the solid-state prove the diamagnetic nature of the low-spin Ni2+ centres in 1 or 3, as expected from the square-planar coordination geometry with rather strong ligands. The complexes expose medium level of antioxidant activity in methanol. Optimized geometry and excited state property by DFT/TD-DFT correspond well to the experimental results of the electronic and molecular structure at the ground state.

Synthesis, general physicochemical behaviour and magnetic studies of the macrocyclic bis-pyridine derivatives [TTDPzM(py)2]·2H2O (M = MnII, CoII, NiII)

In our extensive work on phthalocyanine-like macrocycles carrying peripherally attached strongly electron-withdrawing 1,2,5-thia/selenodiazol rings we recently reported on the FeII species of formula [TTDPzFe(py)2].2H2O (TTDPz = tetrakis(thiadiazole)porphyrazinato dianion). The present work deals with the synthesis and extended physicochemical studies of the series of related macrocycles [TTDPzM(py)2].2H2O (M = MnII, CoII, NiII). The diffractograms of three solid samples of the NiII complex [TTDPzNi(py)2]·2H2O, obtained from different synthetic procedures, indicate that the species is reproducibly obtained. All three samples are isomorphous with each other as shown by their X-ray powder diffractograms. Based on the comparison of the IR spectra of [TTDPzNi(py)2].2H2O and the related desolvated [TTDPzNi], the IR absorption peaks belonging to the pyridine molecules could be identified. The systematic presence of the two water molecules in all three species suggests that forms of contact do exist in the form of hydrogen bonds between them and the S and N atoms present peripherally in the thiadiazole groups of the macrocyclic units. As regard to the elimination of water, the thermograms (in inert atmosphere in the range 25–600 °C) indicate in all cases that loss of water occurs below 100 °C but loss of pyridine occurs over a broad range 100–300 °C for the MnII and CoII species whereas for the NiII complex it takes place in the narrow range 200–220 °C. In relation to the parallel series of metallophthalocyanines, i.e. [PcM] (M = MnII, FeII, CoII), it is noted that the NiII analog has not been reported in the literature and in a direct experiment it has been proved that [PcNi] heated in pyridine is obtained unchanged, the different behavior for the NiII TTDPz derivative due to the electron withdrawing effect of the external thiadiazole substituents, which makes favorable axial pyridine coordination in the complex. Completely insoluble in water, the triad of TTDPz derivatives is extremely low-soluble in non-donor or low donor solvents. This precluded any attempt to isolate single crystals for single-crystal X-ray work. Their UV–visible spectra show essential similarities in whatever organic solvent is used with clearly positioned Soret (300–400 nm) and Q-band absorptions (630–650 nm). Variable temperature magnetic susceptibility and magnetization studies reveal that the [TTDPzM(py)2].2H2O complexes all show paramagnetism with ground state spins of 3/2 (MnII), ½ (CoII) and 1 (NiII), supported by fitting the data to spin Hamiltonian formalism, vide infra. Comparisons are made with the magnetism of [PcM] analogues with key differences noted for M = NiII.

Anchoring Atomically Precise Chiral Bismuth Oxido Nanoclusters on Gold: The Role of Amino Acid Linkers.

The adsorption of chiral molecules onto metallic surfaces triggers electron spin polarization at the interface, paving the way for applications in chiral opto-spintronics. However, the spin effects sensitively depend on the binding and ordering of the chiral species on surfaces. This study explores the adsorption of chiral thioether-functionalized atomically precise bismuth oxido nanoclusters (BiO-NCs) on gold (Au) surfaces, extending the conventional approach of using thiol-containing molecules and complexes to nanoclusters. Starting from the precursor [Bi38O45(NO3)20(dmso)28](NO3)4·4dmso (A), chiral BiO-NCs were synthesized by substituting the nitrates with N-(tert-butoxycarbonyl)-l-methionine (Boc-l-Met-O-) ligands to obtain [Bi38O45(Boc-l-Met-O)24] (2). The full exchange of nitrate by the Boc-l-methionine ligand was demonstrated by powder X-ray diffractograms, dynamic light scattering, electrospray ionization mass spectrometry, nuclear magnetic resonance, infrared, circular dichroism, and X-ray photoelectron spectroscopy. Compared to previously reported [Bi38O45(Boc-l-Phe-O)24(dmso)9] (1), BiO-NC 2 shows differences in the growth mode on a Au surface as revealed by scanning electron microscopy, wherefore a stronger binding of BiO-NC 2 is assumed. Anchoring of BiO-NC 2 to the Au surface through thioether groups induced a discernible change in the optical response of the Au surface analyzed by spectroscopic ellipsometry (SE). From the numerical modeling of the SE parameters, a layer thickness of ∼2 nm, corresponding to a monolayer of BiO-NC 2, was estimated for the samples prepared by dip coating. Thus, strong adsorption of BiO-NC 2 to the Au surface is concluded, which is an essential prerequisite for chiral-induced interface spin polarization.

Near-infrared Spectroscopy for Remote Sensing of Porosity, Density, and Cubicity of Crystalline and Amorphous H2O Ices in Astrophysical Environments

We present laboratory spectra of pure amorphous and crystalline H2O ices in the near-infrared (NIR, 1–2.5 μm/10,000–4000 cm−1) at 80–180 K. The aim of this study is to provide spectroscopic reference data that allow remotely accessing ice properties for icy objects such as icy moons, cometary ice, or Saturn rings. Specifically, we identify new spectral markers for assessing three important properties of ices in space: (i) porosity/fluffiness, (ii) bulk density of amorphous ice, and (iii) cubicity in crystalline ice. The analysis is based on the first OH-stretching overtone (2ν OH) and the combinational band at 5000 cm−1/2 μm, which are potent spectral markers for these properties. By comparison of vapor-deposited, microporous amorphous solid water, pore-free low-, high-, and very-high-density amorphous ice, we are able to separate the effect of (bulk) density from the effect of porosity on NIR-spectra of amorphous ices. This allows for clarifying a longstanding inconsistency about the density of amorphous ice vapor-deposited at low temperatures, first brought up by Jenniskens & Blake. Direct comparison of NIR spectra with powder X-ray diffractograms allows us to correlate spectral features with the number of cubic stacking layers in stacking-disordered ice Isd, ranging from fully cubic ice Ic to fully hexagonal ice Ih. We show that exposure times for instruments on the James Webb Space Telescope are in the hour range to distinguish these properties, demonstrating the usefulness of the neglected NIR spectral range for identifying ices in space.

Efficient Leaching of Metal Ions from Spent Li-Ion Battery Combined Electrode Coatings Using Hydroxy Acid Mixtures and Regeneration of Lithium Nickel Manganese Cobalt Oxide

Extensive use of Li-ion batteries in electric vehicles, electronics, and other energy storage applications has resulted in a need to recycle valuable metals Li, Mn, Ni, and Co in these devices. In this work, an aqueous mixture of glycolic and lactic acid is shown as an excellent leaching agent to recover these critical metals from spent Li-ion laptop batteries combined with cathode and anode coatings without adding hydrogen peroxide or other reducing agents. An aqueous acid mixture of 0.15 M in glycolic and 0.35 M in lactic acid showed the highest leaching efficiencies of 100, 100, 100, and 89% for Li, Ni, Mn, and Co, respectively, in an experiment at 120 °C for 6 h. Subsequently, the chelate solution was evaporated to give a mixed metal-hydroxy acid chelate gel. Pyrolysis of the dried chelate gel at 800 °C for 15 h could be used to burn off hydroxy acids, regenerating lithium nickel manganese cobalt oxide, and the novel method presented to avoid the precipitation of metals as hydroxide or carbonates. The Li, Ni, Mn, and Co ratio of regenerated lithium nickel manganese cobalt oxide is comparable to this metal ratio in pyrolyzed electrode coating and showed similar powder X-ray diffractograms, suggesting the suitability of α-hydroxy carboxylic acid mixtures as leaching agents and ligands in regeneration of mixed metal oxide via pyrolysis of the dried chelate gel.

A Laboratory Investigation of the Adsorption Performance and Mechanism of Organics in Industrial Wastewater on mp-Zr(OH)4

We reported on the development of mesoporous zirconium hydroxide (mp-Zr(OH)4) sorbents with high capacity for adsorptive removal of organic pollutants from industrial wastewater. The sorbent was prepared by a one-step chemical precipitation method at room temperature. The adsorption capacity and removal efficiency for the chemical oxygen demand (COD) of the industrial wastewater were studied using an automatic adsorption measurement apparatus. The effects of different parameters (adsorbent dosage, adsorption time, regeneration times, adsorbate's molecular weight and adsorbate solubility), isotherm, thermodynamics, and kinetics were evaluated. By analyzing scanning electron microscopy (SEM) images and powder X-ray diffractograms (XRD) no obvious differences were observed for the sorbents before and after the adsorption of the organics, which indicated a structural stability of the sorbent. The specific surface area was reduced from 450 m2/g to 189 m2/g on adsorption, and after desorption of the organics the specific surface area was 350 m2/g. The adsorption of COD was analyzed in a Langmuir model that described the data better than the empirical Freundlich model. This finding points towards that the adsorption occurred as a monolayer on the mp-Zr(OH)4. The free energy of adsorption (ΔG) is in the range of −20 kJ/mol < ΔG < 0. Entropy changes are ΔS > 0. The kinetics of the adsorption of COD is better described with a Quasi-second-order dynamic model than with a Quasi-first-order dynamic model, which elucidates its primary reliance on porous adsorption surfaces and incorporation of chemical adsorption.

Matching ROY crystal structures to high-throughput PXRD

The variable-cell experimental powder difference (VC-xPWDF) method allows matching of high-throughput powder X-ray diffractograms of ROY to candidate crystal structures.

Potency and Powder X-ray Diffraction (PXRD) Evaluation of Levothyroxine Sodium Tablets under Ambient, Accelerated, and Stressed Conditions.

Levothyroxine tablets, although highly prescribed in the United States, have been one of the most frequently recalled products. Because of the importance of the medication, several efforts have been put in place by the United States Food and Drug Administration (US FDA) to control the quality of levothyroxine tablets available to patients using the drug. The choice of excipients used in the formulation has been shown to impact the hygroscopicity and microenvironment, and ultimately the stability of the levothyroxine tablets formulations. Based on information generated from the US FDA Enforcement Report database, one of the main reasons for recalls is the low potency of different batches of the product. The yearly product recall trends for levothyroxine formulations were determined using the FDA Enforcement Report database. Three brands of levothyroxine tablets were selected with excipient lists similar to those products that have been historically recalled. The samples were placed at ambient (~23 °C), accelerated stability (40 °C/75% RH), and stress (50 °C/75% RH) conditions for up to 6 months. Sample potencies were determined at 0, 1.5, 3, and 6 months using the methods for assay and impurities in the United States Pharmacopeia (USP) monograph for levothyroxine tablets. Additional sample monitoring was conducted by overlaying the initial powder X-ray diffractograms (PXRD) of the samples from 0 months with the patterns generated thereafter. There has been a decline in the number of levothyroxine tablets recalled over the years. The highest numbers of recalls were recorded in the years 2013 [33] and 2020 [23]; no recalls occurred in the years 2019 and 2022. All of the brands evaluated met the USP 95.0-105.0% assay requirements at 1.5 months under accelerated conditions; only one of the brands complied at 3 months. Under ambient conditions, two brands were stable at 6 months, with borderline assay results. For stability, levothyroxine was found in microgram quantities in the formulations and PXRD could not detect changes at these low levels. However, we found some distinguishing data for samples under stress conditions.

Photoproduction of High Molecular Weight Poly (N-methylpyrrole) under Green Conditions

A novel and green photochemical polymerization method of N-methylpyrole is reported. Spectral and chromatographic characterizations revealed the formation of high molecular weight polymer (1436 kg/mol) having light absorption in the near-infrared region (~750 nm), high fluorescence emission in the visible region, high conductivity (0.062 S/cm) and good thermal stability. Powder X-ray diffractogram identified a totally amorphous polymer. According to cyclic voltammetry studies the polymer formed (PMPy) possess a relatively low electronic band gap (1.39 eV) which is very important for the (opto)electronic device applications of such materials.

EFFECT OFTHE SUBSTITUTION OF Bi→Sb ON THE STRUCTURE CHANGES WITHIN THE AgBi1-xSbxS2 (x = 0 - 1) SOLID SOLUTION

The work is devoted to study effect of the isovalent substitution on the parameter of structure elements of the crystal structure of the AgBi1-xSbxS2 (x = 0 – 1) solid solution. The limited isostructural phases of the solid solution have a cubic system with space group Fm-3m. The samples of individual composition of the AgBi1-xSbxS2 (x = 0 – 1) solid solution were obtained in quartz vacuumed ampoules in an electric muffle furnace with MP-30 software control of technological processes. The X-ray powder diffractograms that were recorded with using the DRON 4-13 diffractometer have been analyzed using WinCSD software package. The visualization of the crystal structure has been made with VESTA program. It is worth noting that the method of solid phase reactions allows synthesizing sufficiently pure materials, which are suitable for the measure of physical properties. The change of cell parameters within a solid solution is described by a positive deviation from the Vegard’s law. Only all octahedral voids are filled in the structure. It is important to see the prospect of possible alloying by atoms with small atomic radii, which may be localized in tetrahedral voids. The change of volume of the octahedral voids is linear.&#x0D; Keywords: crystal structure; solid solution; unit cell.

Inclusion Complex of Ibuprofen-β-Cyclodextrin Incorporated in Gel for Mucosal Delivery: Optimization Using an Experimental Design

β-Cyclodextrin/ibuprofen inclusion complex was synthesized by freeze-drying method and characterized for phase solubility profiles, infrared spectra, thermal analysis, and X-ray powder diffractograms. The inclusion complex with HP-β-CD, as confirmed by molecular dynamics simulations, enhanced the aqueous solubility of ibuprofen by almost 30-fold compared to ibuprofen alone. Different grades of Carbopol (Carbopol 934P/Carbopol 974P/Carbopol 980 NF/Carbopol Ultrez 10 NF) and cellulose derivatives (HPMC K100M/HPMC K15M/HPMC K4M/HPMC E15LV/HPC) were evaluated for mucoadhesive gels incorporating the inclusion complex. The central composite design generated by Design-Expert was employed to optimize the mucoadhesive gel using two independent variables (a varying combination of two gelling agents) on three dependent variables (drug content and in vitro drug release at 6h and 12h). Except for the methylcellulose-based gels, most of the gels (0.5%, 0.75%, and 1% alone or as a mixture thereof) exhibited an extended-release of ibuprofen, ranging from 40 to 74% over 24h and followed the Korsmeyer-Peppas kinetics model. Using this test design, 0.95% Carbopol 934P and 0.55% HPC-L formulations were optimized to increase ibuprofen release, enhance mucoadhesion, and be non-irritating in ex vivo chorioallantoic membrane studies. The present study successfully developed a mucoadhesive gel containing the ibuprofen-β-cyclodextrin inclusion complex with sustained release.

Temperature Dependence on Structural Properties of Liquid Phase Synthesized ZnO

Transparent conducting oxide material, ZnO nanoparticles has been synthesized using inexpensive and eco-friendly synthesis procedures with less or environmental pollutants and no liquid waste products. The effect of the temperatures on the structural properties for the synthesized ZnO nanocrystals has been investigated. In this study, we report an easy, low-cost, re-producible method for synthesizing ZnO nanoparticles by means of the liquid phase method. The ZnO nanocrystals were synthesized using the wet chemical route and the effect of temperature variation on the structural properties of investigated synthesized using powder x-ray diffractogram (XRD). The temperatures for the synthesis were varied from 120 °C to 200 °C in steps of 20 °C. The results show that, during the first stage of the synthesis of ZnO (at 120 °C), the XRD diffraction pattern confirms the cubic structure of zinc peroxide and the XRD pattern of the samples obtained at temperatures of 140 °C, 160 °C, 180 °C and 200 °C were confirmed to be hexagonal (wurtzite) crystal structure of ZnO. The XRD diffraction patterns of the 140 °C and 160 °C samples show some impurity phases which were associated with the zinc acetate by-product which is a colloid complex of water and methyl succinate and were removed by evaporation as temperatures were increased to 180 °C and 200 °C respectively. As temperature increases, the peak of the diffractograms of the sample becomes sharper and narrow indicating a decrease in width. A shift in peak positions to higher angles was observed and the positional parameter, bond angle, β, average crystallite size, APF, number of unit cells and density generally increase with temperature. However, the lattice parameters ‘a’ and ‘c’, bond lengths b and b1, bond angle, α, dislocation density, strain and unit cell volume were found to generally decrease with temperature.

Neural networks trained on synthetically generated crystals can extract structural information from ICSD powder X-ray diffractograms

We used synthetically generated crystals to train ResNet-like models to enhance the prediction of space groups from ICSD powder X-ray diffractograms. The results show improved generalization to unseen structure types compared to previous approaches.

Quantitative matching of crystal structures to experimental powder diffractograms.

The identification and classification of crystal structures is fundamental in materials science, as the crystal structure is an inherent factor of what gives solid materials their properties. Being able to identify the same crystallographic form from unique origins (e.g. different temperatures, pressures, or in silico-generated) is a complex challenge. While our previous work has focused on comparison of simulated powder diffractograms from known crystal structures, herein is presented the variable-cell experimental powder difference (VC-xPWDF) method to match collected powder diffractograms of unknown polymorphs to both experimental crystal structures from the Cambridge Structural Database and in silico-generated structures from the Control and Prediction of the Organic Solid State database. The VC-xPWDF method is shown to correctly identify the most similar crystal structure to both moderate and "low" quality experimental powder diffractograms for a set of 7 representative organic compounds. Features of the powder diffractograms that are more challenging for the VC-xPWDF method are discussed (i.e. preferred orientation), and comparison with the FIDEL method showcases the advantage of VC-xPWDF provided the experimental powder diffractogram can be indexed. The VC-xPWDF method should allow rapid identification of new polymorphs from solid-form screening studies, without requiring single-crystal analysis.

One pot synthesis of bio-based porous isocyanate-free polyurethane materials

In the current study, synthesis of porous isocyanate-free polyurethane materials derived from xylose is reported through a one-pot process, and the impact of varying amounts of crosslinker is studied. The synthesized materials were characterized using various techniques. The formation of the urethane bridge was confirmed using Fourier Transform Infra-Red (FTIR) spectra that exhibited characteristic bands around 1700 cm−1, 1600 cm−1, and 3400 cm−1. The characteristic peak observed at 21◦ (2θvalue) in Powder X-ray (PXRD) diffractogram further confirms the synthesis of segmented polyurethane porous materials. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) thermograms indicate that thermal stability and glass transition temperature (Tg) of synthesized non-isocyanate polyurethane (NIPU) materials increase with increase in the amount of crosslinker. The increase in Limiting Oxygen Index (LOI) values with an increment in the amount of crosslinker suggests improvement in flame retardant behavior of NIPU material due to formation of highly crosslinked network in the polyurethane matrix. These porous NIPU materials align well with the principles of sustainable development.

Effect of annealing temperature on the structural, electronic and magnetic properties of Co doped TiO2 nanoparticles: An investigation by synchrotron-based experimental techniques

The present study examines the effect of annealing temperature on the structural, electronic and magnetic properties of Co-doped TiO2 (TCO) nanoparticles (NPs) synthesized by the sol-gel method. X-ray powder diffractograms of TCO NPs annealed at 400, 600 and 800 °C exhibited the monophasic anatase, diphase (anatase and rutile) and monophasic rutile structures respectively. A morphological investigation using high-resolution scanning electron microscopy (HR-SEM) reveals the presence of nanoparticles with diameters ranging from ∼11 to ∼51 nm. The widening and shifting of the most intense Eg peak in Raman studies and SEM images of TCO NPs suggest Co incorporation in the TiO2 matrix and the formation of oxygen vacancies. Magnetic measurements of TCO at room temperature demonstrate ferromagnetic behaviour which is caused by the existence of oxygen vacancies and the doped Co content. Element specific technique, soft X-ray magnetic circular dichroism (XMCD) was used to study the magnetism in Co doped TiO2 samples. The estimated total magnetic moment by XMCD was in the range of ∼1.3 ± 0.1–2.3 ± 0.2 μB/Co. This huge magnetization was first time observed by the surface-sensitive Total Electron Yield (TEY) mode. The estimated saturation magnetic moment is in the range of 1.0–1.5 μB/Co, also consistent with XMCD analysis and cluster model calculation. The results obtained by XMCD recommend an intrinsic behaviour of ferromagnetism. The X-ray absorption spectra (XAS) of Co-doped TiO2 nanoparticles at Ti L2,3 and Co L2,3 -edge in TEY mode concludes that the valence states of Co and Ti ions are in 2 + and 4 + respectively. Cluster model calculation also confirmed that Co ions are in a 2 + valence state with D2 h high spin crystal-field symmetry at the surface while a random crystal field symmetry in bulk has been observed which is well consistent with experimental data.

Effects of different Bismuth concentrations of InSbBi crystals grown by Bridgman technique

InSb1-xBix (x = 0, 0.005, 0.010, 0.015) crystals are grown by vertical Bridgman technique using single-zone resistive heating furnace. The main objective of this paper is to study the improvement of thermoelectric quality factors by different concentrations of Bismuth (Bi) in InSbBi crystals. EDAX (Energy Dispersive Analysis of X-rays) confirms that the grown crystals are pure and show the presence of In, Sb, and Bi in proportion. Powder X-ray diffractogram confirms the cubic zinc blend structure of these crystals with space group F-43m and all the diffraction peaks are matched well to the standard JCPDS-ICDD No. 6-0208. Raman spectra are recorded from 80 K to 300 K and Raman mapping spectra at room temperature for all above crystals have shown the presence of TO mode at 179.91 cm−1 and LO mode at 190.16 cm−1. The sharpness and intensity of Raman spectra have clearly reflected the purity and quality of the grown crystals. The electrical conductivity σ is found to increase slowly upto 450 K and then increases linearly upto 600 K and above that, it gets saturated in all crystals. The Seebeck coefficient remains negative showing that these crystals are n-type semiconductor and its value is found to be increased to −200 μV/K for InSb0.985Bi0.015 in comparison to −150 μV/K for pure InSb near 600 K. From the lattice thermal conductivity, power factor and thermoelectric figure of merit i.e. ZT calculations, it is concluded that InSb0.985Bi0.015 at 670 K gives the highest value of ZT = 0.45 in comparison to other grown crystals.

Development of a TiO2/Sepiolite Photocatalyst for the Degradation of a Persistent Organic Pollutant in Aqueous Solution.

A clay-based TiO2 nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO2 nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO2 particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO2 particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO2 beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO2 nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO2 materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency.

Mechanical Properties Improvement of Dexibuprofen through Dexibuprofen-Caffeine Co-crystal Formation by Ultrasound assisted Solution Co-crystallization Method

The ability of an active pharmaceutical ingredient to be compressed is directly affected by its mechanical properties, such as flowability and tabletability. Dexibuprofen (DXI) with poor mechanical properties has improved its flowability and tabletability by co-crystal formation with caffeine (CAF) using ultrasound assisted co-crystallization (USSC) method in chloroform solvent. The characterization of the co-crystal formation included crystal morphology, powder X-ray diffractogram, and thermal behavior. The mechanical properties testing including flowability (compressibility index) and tabletability (tensile strength and elastic recovery) were conducted on DXI-CAF co-crystal and pure DXI. The tabletability test was conducted at 10 to 60 kg/cm2 of compression force. The characterization results show that the USSC result has a unique crystal habit, diffractogram, melting point that is different from pure DXI, and this indicates the formation of DXI-CAF co-crystal. The DXI-CAF co-crystal compressibility index was in the good category, while pure DXI was in the poor category. The maximum tensile strength value of the DXI-CAF co-crystal was 1.526 MPa achieved at a compression force of 50 kg/cm2, whilst the maximum tensile strength value of pure DXI was only 0.853 MPa achieved at a compression force of 20 kg/cm2. The elastic recovery curve showed the percentage of elastic recovery of DXI-CAF co-crystal was better than pure DXI. It can be concluded that the co-crystal formation of DXI-CAF by the USSC method was able to improve the mechanical properties (flowability and tabletability) of dexibuprofen.Keywords: dexibuprofen, caffeine, ultrasound assisted co-crystallization, tensile strength, elastic recovery