Data-Driven Prediction of the Formation of Co-Amorphous Systems.

Co-amorphous systems (COAMS) have raised increasing interest in the pharmaceutical industry, since they combine the increased solubility and/or faster dissolution of amorphous forms with the stability of crystalline forms. However, the choice of the co-former is critical for the formation of a COAMS. While some models exist to predict the potential formation of COAMS, they often focus on a limited group of compounds. Here, four classes of combinations of an active pharmaceutical ingredient (API) with (1) another API, (2) an amino acid, (3) an organic acid, or (4) another substance were considered. A model using gradient boosting methods was developed to predict the successful formation of COAMS for all four classes. The model was tested on data not seen during training and predicted 15 out of 19 examples correctly. In addition, the model was used to screen for new COAMS in binary systems of two APIs for inhalation therapy, as diseases such as tuberculosis, asthma, and COPD usually require complex multidrug-therapy. Three of these new API-API combinations were selected for experimental testing and co-processed via milling. The experiments confirmed the predictions of the model in all three cases. This data-driven model will facilitate and expedite the screening phase for new binary COAMS.

Correlating whole sample EDS and Raman mappings - A case study of a Chelyabinsk meteorite fragment.

Whole sample microscopy mappings are of interest in many cases as they provide analytical information of phases varying in size by orders of magnitude and in composition across the sample. These benefits are amplified if more than one microscopic technique is used for the mappings. However, to take full advantage of correlative whole sample mappings, the data of each technique has to be carefully prepared, treated, correlated and evaluated. With this work, we want to present the key steps of our data treatment approach as well as the results on an exemplary sample, the Chelyabinsk meteorite. The most important step in our data treatment approach is to start by evaluating the spectral maps separately as far as possible (at-% quantification for EDS for example) and then generate pseudo spectral maps from this evaluation in the form of image stacks. This allows us to preserve the advantages of specialized software packages and standard work flows for every spectral mapping, whilst also unifying the data format and compressing the data sufficiently for correlation and the application of machine learning tools. We have performed whole sample mappings using SEM, EDS and Raman on a cross-section of a Chelyabinsk meteorite fragment, roughly 1.0cm × 0.8cm large. Combining these mappings into a single "super" spectral map, we were able to produce a uniquely detailed mapping of the composition of the meteorite fragment, as well as perform a quantitative analysis of the elemental composition of several crystallographic phases. The results of our compositional analysis; olivine (Fo72Fa28), pyroxene (≈ 97 % En80Fs20Wo0 and 3 % En56Fs6Wo38), feldspar (albite), troilite, FeNi (taenite and kamacite), merrillite, chromite and hydroxyapatite; agree qualitatively with other reports from literature.

High-Resolution Microstructure Characterization of Additively Manufactured X5CrNiCuNb17-4 Maraging Steel during Ex and In Situ Thermal Treatment.

Powder and selective laser melting (SLM) additively manufactured parts of X5CrNiCuNb17-4 maraging steel were systematically investigated by electron microscopy to understand the relationship between the properties of the powder grains and the microstructure of the printed parts. We prove that satellites, irregularities and superficial oxidation of powder particles can be transformed into an advantage through the formation of nanoscale (AlMnSiTiCr) oxides in the matrix during the printing process. The nano-oxides showed extensive stability in terms of size, spherical morphology, chemical composition and crystallographic disorder upon in situ heating in the scanning transmission electron microscope up to 950 °C. Their presence thus indicates a potential for oxide-dispersive strengthening of this steel, which may be beneficial for creep resistance at elevated temperatures. The nucleation of copper clusters and their evolution into nanoparticles, and the precipitation of Ni and Cr particles upon in situ heating, have been systematically documented as well.

The combination of Raman microscopy and electron microscopy - Practical considerations of the influence of vacuum on Raman microscopy.

Due to the specific vacuum requirements for scanning electron microscopy (SEM), the Raman microscope has to operate in vacuum in a correlative Raman-SEM, which is a type of microscope combination that has recently increased in popularity. This works considers the implications of conducting Raman microscopy under vacuum, as opposed to operating in ambient air, the standard working regime of this technique. We show that the performance of the optics of the Raman microscope are identical in both conditions, but laser beam-sample interactions, such as fluorescent bleaching and beam damage, might be different due to the lack of oxygen in vacuum. The bleaching of the fluorescent background appears to be mostly unaffected by the lack of oxygen, except when very low laser powers are used. Regarding laser-beam damage, organic samples are more sensitive in vacuum than in air, whereas no definite verdict is possible for inorganic samples. These findings have practical implications for the application of correlative Raman-SEM, as low laser powers, or in extreme cases cryo-methods, need to be used for organic samples that appear only moderately beam sensitive under usual ambient air.

Effects of high mechanical treatment and long-term annealing on crystal structure and thermal stability of Ti2O3 nanocrystals.

The effect of high-energy milling and long-term annealing on the stability of Ti2O3 nanocrystals was studied using a magnetic susceptibility method. In situ temperature dependences revealed that the crystal size greatly affects the magnetic susceptibility value. According to XRD, SEM and TEM data, Magnéli phases Ti9O10, Ti4O7, Ti7O19 and Ti3O5 are formed.

Immobilization of Polyiodide Redox Species in Porous Carbon for Battery-Like Electrodes in Eco-Friendly Hybrid Electrochemical Capacitors.

Hybrid electrochemical capacitors have emerged as attractive energy storage option, which perfectly fill the gap between electric double-layer capacitors (EDLCs) and batteries, combining in one device the high power of the former and the high energy of the latter. We show that the charging characteristics of the positive carbon electrode are transformed to behave like a battery operating at nearly constant potential after it is polarized in aqueous iodide electrolyte (1 mol L-1 NaI). Thermogravimetric analysis of the positive carbon electrode confirms the decomposition of iodides trapped inside the carbon pores in a wide temperature range from 190 °C to 425 °C, while Raman spectra of the positive electrode show characteristic peaks of I3- and I5- at 110 and 160 cm-1, respectively. After entrapment of polyiodides in the carbon pores by polarization in 1 mol L-1 NaI, the positive electrode retains the battery-like behavior in another cell, where it is coupled with a carbon-based negative electrode in aqueous NaNO3 electrolyte without any redox species. This new cell (the iodide-ion capacitor) demonstrates the charging characteristics of a hybrid capacitor with capacitance values comparable to the one using 1 mol L-1 NaI. The constant capacitance profile of the new hybrid cell in aqueous NaNO3 for 5000 galvanostatic charge/discharge cycles at 0.5 A g-1 shows that iodide species are confined to the positive battery-like electrode exhibiting negligible potential decay during self-discharge tests, and their shuttling to the negative electrode is prevented in this system.