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Journal of Applied Crystallography Aug 2021X-ray diffractometers primarily designed for surface X-ray diffraction are often used to measure the diffraction from powders, textured materials and fiber-texture...
X-ray diffractometers primarily designed for surface X-ray diffraction are often used to measure the diffraction from powders, textured materials and fiber-texture samples in 2θ scans. Unlike in high-energy powder diffraction, only a fraction of the powder rings is typically measured, and the data consist of many detector images across the 2θ range. Such diffractometers typically scan in directions not possible on a conventional laboratory diffractometer, which gives enhanced control of the scattering vector relative to the sample orientation. There are, however, very few examples where the measured intensity is directly used, such as for profile/Rietveld refinement, as is common with other powder diffraction data. Although the underlying physics is known, converting the data is time consuming and the appropriate corrections are dispersed across several publications, often not with powder diffraction in mind. This paper presents the angle calculations and correction factors required to calculate meaningful intensities for 2θ scans with a (2 + 3)-type diffractometer and an area detector. Some of the limitations with respect to texture, refraction and instrumental resolution are also discussed, as is the kind of information that one can hope to obtain.
PubMed: 34429722
DOI: 10.1107/S1600576721006245 -
Analytical Sciences : the International... Dec 2022The thermal behavior of stellerite from the Savinskoye deposit (Transbaikalia, Russia), CaNaK(SiAl)O·53.39HO, was investigated by in situ high-temperature X-ray powder...
The thermal behavior of stellerite from the Savinskoye deposit (Transbaikalia, Russia), CaNaK(SiAl)O·53.39HO, was investigated by in situ high-temperature X-ray powder diffraction (HTXRPD) and ex situ HT infrared (IR) spectroscopic analysis. Four different HTXRPD experimental procedures were used to study the thermal behavior of the powder samples: (1) RT-750 °C, (2) RT-220 °C -RT, (3) 200-350-RT °C, and (4) 350-700 °C. Electron probe microanalysis and single-crystal X-ray diffraction were preliminary used to determine the chemical composition and crystal structure of stellerite. The A → B phase transition (Fmmm → Amma) starts at ∼110 °C and is completed at about 140 °C (in situ HTXRPD) and 200 °C (ex situ HTIR) depending on the experimental conditions. It involves a cell volume decrease of 5.8% (Experiment 1). The thermal expansion of stellerite is more pronounced along the b and c axes, with αa: αb: αc (× 10) = 2.50:-25.52:-6.84 at 100 °C, 0.44:-21.75:-25.64 at 150 °C after the completion of the phase transition, and 3.06:-1.86:-16.94 at 500 °C. The reverse B → A transition occurs at temperatures below 100 °C during slow cooling (Experiment 2), however, it does not occur upon rapid cooling (Experiment 3). The B → D phase transition above 300 °C is not observed (Experiment 4). The temperature barrier of phase transition in the ex situ HTIR spectroscopy experiment is shifted towards high temperatures. The heating above 200 °C leads to an increase of 3430 cm and a decrease of 3600 and 3260 cm bands, which correspond to the stretching vibration of HO. The heating above 400 °C causes complete dehydration of the stellerite.
Topics: X-Ray Diffraction; Temperature; Powders; Powder Diffraction; X-Rays
PubMed: 36094727
DOI: 10.1007/s44211-022-00186-4 -
Molecules (Basel, Switzerland) Nov 2022Tafamidis, chemical formula CHClNO, is a drug used to delay disease progression in adults suffering from transthyretin amyloidosis, and is marketed worldwide under...
Tafamidis, chemical formula CHClNO, is a drug used to delay disease progression in adults suffering from transthyretin amyloidosis, and is marketed worldwide under different tradenames as a free acid or in the form of its meglumine salt. The free acid (CAS no. 594839-88-0) is reported to crystallize as distinct (polymorphic) crystal forms, the thermal stability and structural features of which remained thus far undisclosed. In this paper, we present-by selectively isolating highly pure batches of Tafamidis Form 1 and Tafamidis Form 4-the full characterization of these solids, in terms of crystal structures (determined using state-of-the-art structural powder diffraction methods) and spectroscopic and thermal properties. Beyond conventional thermogravimetric and calorimetric analyses, variable-temperature X-ray diffraction was employed to measure the highly anisotropic response of these (poly)crystalline materials to thermal stimuli and enabled the determination of the linear and volumetric thermal expansion coefficients and of the related indicatrix. Both crystal phases are monoclinic and contain substantially flat and π-π stacked Tafamidis molecules, arranged as centrosymmetric dimers by strong O-H···O bonds; weaker C-H···N contacts give rise, in both polymorphs, to infinite ribbons, which guarantee the substantial stiffness of the crystals in the direction of their elongation. Complete knowledge of the structural models will foster the usage of full-pattern quantitative phase analyses of Tafamidis in drug and polymorphic mixtures, an important aspect in both the forensic and the industrial sectors.
Topics: Crystallization; Powder Diffraction; X-Ray Diffraction
PubMed: 36364244
DOI: 10.3390/molecules27217411 -
Acta Chimica Slovenica Nov 2023Due to its transferability, the soil has been commonly used as evidence in criminal investigations. In this work, 172 soil samples taken from five urban parks from the...
Due to its transferability, the soil has been commonly used as evidence in criminal investigations. In this work, 172 soil samples taken from five urban parks from the town of Tetovo (North Macedonia) and from additional four rural locations in its vicinity. The soil samples were examined using X-ray powder diffraction. The collected diffractograms were used for development of classification models based on supervised self-organizing maps. The examination generalization performances of the developed models showed that they were able to correctly classify between 95.6 and 97.8% of the samples from the independent test set. The influence of the weather and the seasonal changes on the composition of the soil was also examined. For this purpose, three years after the initial soil samples were collected, additional 28 samples were analyzed from different location. The best models presented in this work were able to successfully classify 27 of these additional samples.
PubMed: 38124648
DOI: 10.17344/acsi.2023.8221 -
International Journal of Cosmetic... Feb 2021In the present study, we describe the features and functional properties of a new powder cosmetic ingredient, an amorphous mesoporous magnesium carbonate (MMC, also...
OBJECTIVE
In the present study, we describe the features and functional properties of a new powder cosmetic ingredient, an amorphous mesoporous magnesium carbonate (MMC, also named Upsalite ) with regard to physical characteristics as well as functional attributes.
METHODS
Physical and functional characterization of MMC, as compared to other common powder cosmetic ingredients (silica, mica, kaolin, talc and starch), was assessed using nitrogen gas adsorption, powder X-ray diffraction, particle size distribution by laser diffraction, scanning electron microscopy (SEM), and oil and moisture uptake tests. The powder ingredients were also applied on human skin and analysed for short- and long-term mattifying effect, and a new method was developed to measure flashback effect. MMC was tested for skin irritation using an in vitro cell model as well as in vivo, through the Human Repeated Insult Patch Test on 50 human volunteers.
RESULTS
Mesoporous magnesium carbonate has a high surface area and pore volume. It has an excellent absorption capacity and can take up both oil and water simultaneously. It provides instant and long-lasting mattifying effect when applied on human skin without drying or irritating skin and exhibits no measured flashback effect.
CONCLUSION
Mesoporous magnesium carbonate has good sensory and visual characteristics as well as excellent absorbing and mattifying properties, suggesting that it has great potential to replace other powder ingredients currently used as fillers and absorbers in powder cosmetics.
Topics: Cosmetics; Humans; Irritants; Magnesium; Porosity; Powder Diffraction; Powders; Skin
PubMed: 33038019
DOI: 10.1111/ics.12670 -
Nanomaterials (Basel, Switzerland) Apr 2021We introduce a novel scanning electron microscopy (SEM) method which yields powder electron diffraction patterns. The only requirement is that the SEM microscope must be...
We introduce a novel scanning electron microscopy (SEM) method which yields powder electron diffraction patterns. The only requirement is that the SEM microscope must be equipped with a pixelated detector of transmitted electrons. The pixelated detectors for SEM have been commercialized recently. They can be used routinely to collect a high number of electron diffraction patterns from individual nanocrystals and/or locations (this is called four-dimensional scanning transmission electron microscopy (4D-STEM), as we obtain two-dimensional (2D) information for each pixel of the 2D scanning array). Nevertheless, the individual 4D-STEM diffractograms are difficult to analyze due to the random orientation of nanocrystalline material. In our method, all individual diffractograms (showing randomly oriented diffraction spots from a few nanocrystals) are combined into one composite diffraction pattern (showing diffraction rings typical of polycrystalline/powder materials). The final powder diffraction pattern can be analyzed by means of standard programs for TEM/SAED (Selected-Area Electron Diffraction). We called our new method 4D-STEM/PNBD (Powder NanoBeam Diffraction) and applied it to three different systems: Au nano-islands (well diffracting nanocrystals with size ~20 nm), small TbF nanocrystals (size < 5 nm), and large NaYF nanocrystals (size > 100 nm). In all three cases, the STEM/PNBD results were comparable to those obtained from TEM/SAED. Therefore, the 4D-STEM/PNBD method enables fast and simple analysis of nanocrystalline materials, which opens quite new possibilities in the field of SEM.
PubMed: 33918700
DOI: 10.3390/nano11040962 -
PloS One 2021This study aims at developing and characterizing the puerarin dry powder inhaler (DPI) formulations for pulmonary delivery. The inhalable particles size (<2 μm) was...
This study aims at developing and characterizing the puerarin dry powder inhaler (DPI) formulations for pulmonary delivery. The inhalable particles size (<2 μm) was accomplished by micronization and its morphology was examined by scanning electron microscopy (SEM). The puerarin-excipient interaction in powder mixtures was analyzed by using Fourier transform infrared spectroscopy (FTIR), Raman confocal microscopy, X-Ray powder Diffraction (XRD), and differential scanning calorimetry (DSC) methods. Using a Twin stage impinger (TSI), the in-vitro aerosolization of the powder formulations was carried out at a flow rate of 60 L/min and the drug was quantified by employing a validated HPLC method. No significant interactions between the drug and the excipients were observed in the powder formulations. The fine particle fraction (FPF) of the drug alone was 4.2% which has increased five to six-fold for the formulations with aerosolization enhancers. Formulation containing lactose as large carriers produced 32.7% FPF, which further increased with the addition of dispersibility enhancers, leucine and magnesium stearate (40.8% and 41.2%, respectively). The Raman and FTIR techniques are very useful tool for understanding structural integrity and stability of the puerarin in the powder formulations. The puerarin was found to be compatible with the excipients used and the developed DPI formulation may be considered as an efficient formulation for pulmonary delivery for the management of various diseases at a very low dose.
Topics: Administration, Inhalation; Aerosols; Calorimetry, Differential Scanning; Chemistry, Pharmaceutical; Drug Compounding; Dry Powder Inhalers; Excipients; Isoflavones; Microscopy, Electron, Scanning; Particle Size; Powders; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction
PubMed: 33848310
DOI: 10.1371/journal.pone.0249683 -
Journal of Applied Crystallography Feb 2021A recent article by Von Dreele, Clarke & Walsh [ (2021), , https://doi.org/10.1107/S1600576720014624] introduces an entirely new paradigm in structure determination,...
A recent article by Von Dreele, Clarke & Walsh [ (2021), , https://doi.org/10.1107/S1600576720014624] introduces an entirely new paradigm in structure determination, where a complete structural measurement is made in a tenth of a nanosecond.
PubMed: 33833636
DOI: 10.1107/S1600576721000704 -
Journal of Pharmaceutical Sciences Oct 2022The widespread use of amorphous solid dispersions (ASDs) dictates that analytical methods are required to accurately quantify crystallinity and characterize crystals...
Comparison of Differential Scanning Calorimetry, Powder X-ray Diffraction, and Solid-state Nuclear Magnetic Resonance Spectroscopy for Measuring Crystallinity in Amorphous Solid Dispersions - Application to Drug-in-polymer Solubility.
The widespread use of amorphous solid dispersions (ASDs) dictates that analytical methods are required to accurately quantify crystallinity and characterize crystals formed in order to help design a stable ASD. Current crystallinity quantitation methods are limited to ASDs of moderate drug loadings, single polymorphs, and fast crystallization kinetics. The ability of multiple differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and solid-state nuclear magnetic resonance (SSNMR) techniques were compared for quantifying crystallinity in ASDs in varying conditions. Determining crystallinity by DSC is limited by its ability to measure T or heat of fusion. PXRD was relatively robust in determining crystalline and amorphous ratios for drug-polymer systems in the absence of other excipients. SSNMR provides both quantitative information and reveal how crystal quality changes with crystallization conditions and helps to explain the failure of DSC methods. The results of five different methods using three techniques were directly applied to measure drug-in-polymer solubility with four agreeing well with the literature. PXRD and SSNMR are therefore proposed as alternative methods to quantify crystallinity and predict drug-in-polymer solubility when DSC methods do not work. In-situ and ex-situ annealing was also compared, and equivalent crystallinity data was acquired.
Topics: Calorimetry, Differential Scanning; Excipients; Magnetic Resonance Spectroscopy; Polymers; Powder Diffraction; Powders; Solubility; X-Ray Diffraction
PubMed: 35421430
DOI: 10.1016/j.xphs.2022.04.004 -
Journal of Pharmaceutical Sciences Nov 2020Florfenicol is an antimicrobial drug used in veterinary medicine and aquaculture. Two polymorphic forms called A and B have been reported in literature, but the relation...
Florfenicol is an antimicrobial drug used in veterinary medicine and aquaculture. Two polymorphic forms called A and B have been reported in literature, but the relation between these two forms are unknown. In order to get a better understanding of the behavior of solid florfenicol and the possible evolution from a metastable form to a stable one, an accurate thermodynamic study has been carried out by calorimetric measurements. For this purpose, temperatures and enthalpies of transition and of fusion of the stable and metastable forms have been measured by DSC. TGA has been used in view to detect the eventual existence of solvates which does not occur. In view to confirm the kind of transition, c measurements of the two forms have been performed with a C80 calorimeter. With these c values, it has been possible to determine the function of the variation of enthalpies as a function of temperature, ΔH = f (T). A study of the kinetic of transformation has been realized and is presented as well as the patterns of the X-ray powder diffraction from 295 to 426 K. This last approach confirms the crystal structure of form A of florfenicol previously reported in literature.
Topics: Calorimetry, Differential Scanning; Powder Diffraction; Thermodynamics; Thiamphenicol; X-Ray Diffraction
PubMed: 32721472
DOI: 10.1016/j.xphs.2020.07.017