The high‐resolution powder diffraction beamline at ESRF (ID22), built with a dual‐undulator source on the 6 GeV storage ring, combines a wide continuous range of incident energy (6–80 keV) with high brightness, offering the possibility to carry out high‐flux high‐resolution powder diffraction measurements. In routine operation, a bank of nine scintillation detectors is scanned vertically to measure the diffracted intensity versus 2gθ, each detector being preceded by an Si 111 analyser crystal. Although the current detector system has operated successfully for the past 20 years, recent developments in detector technology could be exploited to improve the overall performance. With this in mind, as a test, a two‐dimensional Pilatus3 X CdTe 300 K‐W pixel detector has been mounted on the arm of the diffractometer, replacing the nine scintillator detectors. At each nominal 2gθ value, a two‐dimensional image is recorded showing nine distinct regions corresponding to the diffraction signals passing via each of the analyser crystals. This arrangement offers new flexibility in terms of data handling and processing, with the possibility to optimize both peak shape and statistics, to remove parasitic effects, and to gain spatial resolution information. Combining the high efficiency of a hybrid photon‐counting area detector with the high angular resolution given by analyser crystals is an effective approach to improving the overall performance of high‐resolution powder diffraction.
The nucleobase adenine plays a pivotal role in the chemistry of life, but is also becoming increasingly interesting as a building block in the synthesis of functional solid materials.Although commercially available as a solid, adenine's solid-state chemistry has so far been neglected. In this comprehensive study it is shown that adenine is most often marketed as a mixture of two polymorphs, one previously known, and a new polymorph.Both polymorphs exhibit layered structures with different hydrogen-bonding patterns within layers. The crystal structure of the new polymorph was elucidated using synchrotron powder X-ray diffraction. Polymorph occurrence conditions, interconversion and the difference in their thermodynamic stability were established theoretically and experimentally revealing the polymorph with Z = 2 (known) as stable relative to the polymorph with Z = 1 (new). The adenine layers in both polymorphs are connected by weak interaction likely resulting in stacking faults which are manifested in anisotropic line broadening of their powder diffraction patterns. Analysis of a few commercial samples of adenine revealed them all to be a polymorph mixture, which could be inconvenient in experiments where properties of the solid material could be relevant.
Solid dispersions are important supersaturating formulations to orally deliver poorly water-soluble drugs. A most important process technique is hot melt extrusion but process requirements limit the choice of suitable polymers. One way around this limitation is to synthesize new polymers. However, their disadvantage is that they require toxicological qualification and present regulatory hurdles for their market authorization. Therefore, this study follows an alternative approach, where new polymeric matrices are created by combining a known polymer, small molecular additives, and an initial solvent-based process step. The polyelectrolyte, carboxymethylcellulose sodium (NaCMC), was tested in combination with different additives such as amino acids, meglumine, trometamol, and urea. It was possible to obtain a new polyelectrolyte matrix that was viable for manufacturing by hot melt extrusion. The amount of additives had to be carefully tuned to obtain an amorphous polymer matrix. This was achieved by probing the matrix using several analytical techniques, such as Fourier transform infrared spectroscopy, differential scanning calorimetry, hot stage microscopy, and X-ray powder diffraction. Next, the obtained matrices had to be examined to ensure the homogeneous distribution of the components and the possible residual crystallinity. As this analysis requires probing a sample on several points and relies on high quality data, X-ray diffraction and starring techniques at a synchrotron source had to be used. Particularly promising with NaCMC was the addition of lysine as well as meglumine. Further research is needed to harness the novel matrix with drugs in amorphous formulations.
The ability to utilize a hybrid-photon-counting detector to its full potential can significantly influence data quality, data collection speed, as well as development of elaborate data acquisition schemes. This paper facilitates the optimal use of EIGER2 detectors by providing theory and practical advice on (i) the relation between detector design, technical specifications and operating modes, (ii) the use of corrections and calibrations, and (iii) new acquisition features: a double-gating mode, 8-bit readout mode for increasing temporal resolution, and lines region-of-interest readout mode for frame rates up to 98 kHz. Examples of the implementation and application of EIGER2 at several synchrotron sources (ESRF, PETRA III/DESY, ELETTRA, AS/ANSTO) are presented: high accuracy of high-throughput data in serial crystallography using hard X-rays; suppressing higher harmonics of undulator radiation, improving peak shapes, increasing data collection speed in powder X-ray diffraction; faster ptychography scans; and cleaner and faster pump-and-probe experiments.
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