Recent advances in acoustic diagnostics for electrochemical power systems

Over the last decade, acoustic methods, such as acoustic emission and ultrasonic testing, have been increasingly deployed for process diagnostics and health monitoring of electrochemical power devices including batteries, fuel cells, and water electrolysers. These acoustic are non-invasive, highly sensitive, and low cost, while also providing a high level of spatial and temporal resolution, and practicality. The application of these tools in electrochemical devices is based on identifying changes in acoustic signals due to physical, structural, and electrochemical properties change within the material which are then correlated to critical processes and the health status of the devices. This review discusses recent progress in the use of acoustic methods for process and health-monitoring of major electrochemical energy conversion and storage devices. First, the fundamental concepts and principles of acoustic emission and ultrasonic testing are introduced, followed by a discussion of the range of electrochemical energy conversion and storage systems, and how acoustic techniques are being used to study relevant materials and devices. Conclusions and future perspectives highlighting some of the unique challenges and potential commercial and academic applications of the devices are also discussed. It is expected that, with further developments, acoustic techniques will form a key part of the suite of diagnostic techniques routinely used to monitor electrochemical devices across various processes including fabrication, on-board maintenance, post-mortem examination and second life or recycle decision support to aid the deployment of these devices in increasingly demanding applications

A comprehensive spectroscopic study of the polymorphs of diflunisal and their phase transformations

Understanding phase transitions in pharmaceutical materials is of vital importance for drug manufacturing, processing and storage. In this paper we have carried out comprehensive high-resolution spectroscopic studies on the polymorphs of the non-steroidal anti-inflammatory drug diflunisal that has four known polymorphs, forms I-IV (FI-FIV), three of which have known crystal structures. Phase transformations during milling, heating, melt-quenching and exposure to high relative humidity were investigated using Raman and terahertz spectroscopy in combination with differential scanning calorimetry and X-ray powder diffraction. The observed phase transformations indicate the stability order FIII>FI>FII, FIV. Furthermore, crystallization experiments from the gas phase and from solution by fast evaporation of different solvents were carried out. Fast evaporation of an ethanolic solution below 70°C was identified as a reliable and convenient method to obtain the somewhat elusive FII in bulk quantities.This work was supported by Science Foundation Ireland under Grant No. [12/RC/2275] as part of the Synthesis and Solid State Pharmaceutical Centre (SSPC). ARP would like to acknowledge ICHEC, Irish HPC system for computing time on the condominium access (nuig02). ARP also acknowledges the RIA Charlemont grant for financial support of a research visit to the University of Cambridge

A coherent feed-forward loop drives vascular regeneration in damaged aerial organs of plants growing in a normal developmental context

Aerial organs of plants, being highly prone to local injuries, require tissue restoration to ensure their survival. However, knowledge of the underlying mechanism is sparse. In this study, we mimicked natural injuries in growing leaves and stems to study the reunion between mechanically disconnected tissues. We show that PLETHORA (PLT) and AINTEGUMENTA (ANT) genes, which encode stem cell-promoting factors, are activated and contribute to vascular regeneration in response to these injuries. PLT proteins bind to and activate the CUC2 promoter. PLT proteins and CUC2 regulate the transcription of the local auxin biosynthesis gene YUC4 in a coherent feed-forward loop, and this process is necessary to drive vascular regeneration. In the absence of this PLT-mediated regeneration response, leaf ground tissue cells can neither acquire the early vascular identity marker ATHB8, nor properly polarise auxin transporters to specify new venation paths. The PLT-CUC2 module is required for vascular regeneration, but is dispensable for midvein formation in leaves. We reveal the mechanisms of vascular regeneration in plants and distinguish between the wound-repair ability of the tissue and its formation during normal development.Peer reviewe

Dynamic disorder, phonon lifetimes, and the assignment of modes to the vibrational spectra of methylammonium lead halide perovskites

We present Raman and terahertz absorbance spectra of methylammonium lead halide single crystals (MAPbX3, X = I, Br, Cl) at temperatures between 80 and 370 K. These results show good agreement with density-functional-theory phonon calculations.1 Comparison of experimental spectra and calculated vibrational modes enables confident assignment of most of the vibrational features between 50 and 3500 cm-1. Reorientation of the methylammonium cations, unlocked in their cavities at the orthorhombic-to-tetragonal phase transition, plays a key role in shaping the vibrational spectra of the different compounds. Calculations show that these dynamics effects split Raman peaks and create more structure than predicted from the independent harmonic modes. This explains the presence of extra peaks in the experimental spectra that have been a source of confusion in earlier studies. We discuss singular features, in particular the torsional vibration of the C-N axis, which is the only molecular mode that is strongly influenced by the size of the lattice. From analysis of the spectral linewidths, we find that MAPbI3 shows exceptionally short phonon lifetimes, which can be linked to low lattice thermal conductivity. We show that optical rather than acoustic phonon scattering is likely to prevail at room temperature in these materials.Comment: 40 pages (no supporting info uploaded

Comparing the effectiveness of hyperspectral imaging and Raman spectroscopy:A case study on Armenian manuscripts

Additional file 1. Additional Figures S1–S5 and Tables S1, S2

A Comprehensive Cocrystal Screening Study of Chlorothiazide

Cocrystal formation of chlorothiazide (ctz) was screened with a variety of coformers with carboxyl, amide, hydroxyl, sulfonamide, pyridine, amidine, and amine functional groups. New cocrystals with acetamide (aca), benzamide (bza), propionamide (ppa), caprolactam (cap), carbamazepine (cbz), nicotinamide (nia), isonicotinamide (ina), hexamethylenetetramine (hma), 4,4′-bipyridine (bipy), 1,2-di(4-pyridyl)ethylene (ebipy), 2-hydroxypyridine (hyp), 1,3-di(4-pyridyl)propane (pbipy) and pyrazine (pyr) as well as a benzamidinium (bzamH+) salt were obtained by mechanical grinding and liquid-assisted grinding and identified by powder X-ray diffraction. The structures of ctz-bza, ctz-cbz, ctz-ina, ctz-nia, ctz-hma, ctz-bipy, ctz-ebipy, ctz-pbipy, and (bzamH+)(ctz–) were determined by single-crystal X-ray diffraction. Analysis of the hydrogen bonding motifs showed that in all cocrystal structures except for ctz-bipy, the NHsulfonamide···N(SO2)═C catemer synthon of ctz form I is replaced by ctz-coformer heterosynthons. The dissolution behavior and relationship between dissolution rate, packing index, and lattice energy of the cocrystals is described. To understand why no cocrystals with carboxylic acids formed, a motif search of the Cambridge Structural Database (CSD) was carried out

Shining Light on Growth-Dependent Surface Chemistry of Organic Crystals: A Polarized Raman Spectroscopic and Computational Study of Aspirin

Understanding and controlling crystal surfaces is a critical problem in contemporary materials science. Organic crystal surfaces present the additional complexity of multiple terminations with different functional groups. These alternate terminations influence the surface chemistry and exert control over many material properties. While established tools for surface characterization exist, few provide the chemical information required to unambiguously identify functional groups. Polarized Raman spectroscopy is a versatile tool that can provide detailed chemical information on molecular materials, and, when used in a microscope configuration, can be used to map substrates on a micron scale. In this work, we demonstrate the use of polarized Raman to study the surface chemistry of aspirin. By analyzing crystals grown under a variety of conditions, we relate the growth solvent to the surface termination and reconcile the conflicting results in the literature on the nature of the surface. Our results are supported by detailed first-principles modeling of the surfaces and their vibrational spectra. This study establishes the potential of polarized Raman microscopy as a tool for organic surface science that, when combined with predictive modeling, provides a powerful means to understand and ultimately control surface chemistry

The Molecular Basis for Properties of Binary Solvent Systems: Synchrotron X-ray Pair Distribution Function Analysis of the Acetone-Water System

The acetone-water phase diagram. Dynamic structural insights into intermolecular interactions in acetone-water binary mixtures modelled from synchrotron total X-ray scattering describes phase behavior. <br /

Tailoring Cocrystal and Salt Formation and Controlling the Crystal Habit of Diflunisal

Crystal habit modification of the drug diflunisal that normally grows into extremely thin, long needles has been achieved by breaking the stacking effect with the help of coformers. Eight new cocrystals are reported, along with three crystal structures. In all cases, ortho F disorder, often a feature in diflunisal structures was absent due to the presence of CH···F interactions. Co-milling diflunisal with oxalic acid produced 1:1 and 2:1 cocrystals. In contrast, in solution crystallization, oxalic acid played the role of an additive resulting in the crystallization of diflunisal form I rather than form III. To rationalize cocrystal formation, a statistical analysis of the Cambridge Crystallographic Data Centre database for aromatic o-hydroxy carboxylic acids was carried out. All cocrystals of o-hydroxy carboxylic acids with the COOH dimer motif have an electron-withdrawing group on one of the acids. COOH···Nar motifs are formed preferentially over carboxylic homodimers in the presence of an Nar coformer