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1. Quantum Cascade Laser Infrared Microscopy and 2D IR Correlation Spectroscopy Improves Crystallization Screening of a Protein Complex

   Nieves, S; Pastrana, B. (November 2019, Spectroscopy)

   Bush, L; Workman, J. (Ed.)

   X-ray diffraction of crystallized protein continues to be the preferred means of obtaining high-resolution structures of proteins and their complexes. These structures are crucial for drug design, but the screening and optimization of the conditions that produce well-diffracting crystals represent a bottleneck in the structure determination process. In this study, a quantum cascade laser (QCL) infrared microscope was used to determine protein aggregation, distinct from self-association, which is crucial to the success of any crystallization effort. Hyperspectral images of an aliquot from a vapor diffusion hanging drop crystallization screen were acquired over a small temperature range (30–38 ºC), at intervals of 2 ºC. QCL infrared (IR) spectral data were subjected to 2D IR correlation analysis to describe Homo sapiens (Hs) centrin 2(E32A)-Sfi1p21 complex (1:1.5 molar ratio) and the selective aggregation of the target peptide. To our knowledge, this is the first time such a level of molecular understanding has been achieved. 

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2. 20 years of crystal hits: progress and promise in ultrahigh-throughput crystallization screening

   https://doi.org/10.1107/s2059798323001274  

   Lynch, Miranda L; Snell, M Elizabeth; Potter, Stephen A; Snell, Edward H; Bowman, Sarah_E J (March 2023, Acta Crystallographica Section D Structural Biology)

   Diffraction-based structural methods contribute a large fraction of the biomolecular structural models available, providing a critical understanding of macromolecular architecture. These methods require crystallization of the target molecule, which remains a primary bottleneck in crystal-based structure determination. The National High-Throughput Crystallization Center at Hauptman–Woodward Medical Research Institute has focused on overcoming obstacles to crystallization through a combination of robotics-enabled high-throughput screening and advanced imaging to increase the success of finding crystallization conditions. This paper will describe the lessons learned from over 20 years of operation of our high-throughput crystallization services. The current experimental pipelines, instrumentation, imaging capabilities and software for image viewing and crystal scoring are detailed. New developments in the field and opportunities for further improvements in biomolecular crystallization are reflected on. 

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3. The influence of porosity, crystallinity and interlayer adhesion on the tensile strength of 3D printed polylactic acid (PLA)

   https://doi.org/10.1108/rpj-08-2020-0205  

   von Windheim, Natalia; Collinson, David W.; Lau, Trent; Brinson, L. Catherine; Gall, Ken (July 2021, Rapid Prototyping Journal)

   null (Ed.)

   Purpose The purpose of this study is to understand how printing parameters and subsequent annealing impacts porosity and crystallinity of 3D printed polylactic acid (PLA) and how these structural characteristics impact the printed material’s tensile strength in various build directions. Design/methodology/approach Two experimental studies were used, and samples with a flat vs upright print orientation were compared. The first experiment investigates a scan of printing parameters and annealing times and temperatures above the cold crystallization temperature ( T cc ) for PLA. The second experiment investigates annealing above and below T cc at multiple points over 12 h. Findings Annealing above T cc does not significantly impact the porosity but it does increase crystallinity. The increase in crystallinity does not contribute to an increase in strength, suggesting that co-crystallization across the weld does not occur. Atomic force microscopy (AFM) images show that weld interfaces between printed fibers are still visible after annealing above T cc , confirming the lack of co-crystallization. Annealing below T cc does not significantly impact porosity or crystallinity. However, there is an increase in tensile strength. AFM images show that annealing below T cc reduces thermal stresses that form at the interfaces during printing and slightly “heals” the as-printed interface resulting in an increase in tensile strength. Originality/value While annealing has been explored in the literature, it is unclear how it affects porosity, crystallinity and thermal stresses in fused filament fabrication PLA and how those factors contribute to mechanical properties. This study explains how co-crystallization across weld interfaces is necessary for crystallinity to increase strength and uses AFM as a technique to observe morphology at the weld. 

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4. A review on synthesis and engineering of crystal precursors produced via coprecipitation for multicomponent lithium-ion battery cathode materials

   https://doi.org/10.1039/c9ce00679f  

   Dong, Hongxu; Koenig, Gary M. (March 2020, CrystEngComm)

   null (Ed.)

   Interest in developing high performance lithium-ion rechargeable batteries has motivated research in precise control over the composition, phase, and morphology during materials synthesis of battery active material particles for decades. Coprecipitation, as one of the most reported methods in the literature to produce precursors for lithium-ion battery active materials, has drawn attention due to its simplicity, scalability, homogeneous mixing at the atomic scale, and tunability over particle morphology. This highlight summarizes the advancements that have been made in producing crystalline particles of tunable and complex morphologies via coprecipitation for use as lithium-ion battery precursor materials. Comparison among different crystallization reagents, solution conditions that influence the properties of crystal particles, and the fundamental knowledge from equilibrium and/or kinetic study of the coprecipitation processes, are systematically discussed. The research reports and guiding principles summarized in this highlight are meant to improve selections made by researchers to efficiently determine synthesis conditions. In addition, it is desired that the methods applied from the study of crystallization will inspire researchers to pursue further investigation of the nucleation and growth mechanisms of these coprecipitation processes, which will be necessary to achieve truly predictive particle synthesis. 

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5. Design of an atomic layer deposition system with in situ reflection high energy electron diffraction

   https://doi.org/10.1063/5.0206286  

   Howzen, Alexandra J; Caspar, Justin; Oztekin, Alparslan; Strandwitz, Nicholas C (November 2024, Review of Scientific Instruments)

   We report the design, fabrication, and testing of an atomic layer deposition (ALD) system that is capable of reflection high energy electron diffraction (RHEED) in a single chamber. The details and specifications of the system are described and include capabilities of RHEED at varied accelerating voltages, sample rotation (azimuthal) control, sample height control, sample heating up to set temperatures of 1050 °C, and either single- or dual-differential pumping designs. Thermal and flow simulations were used to justify selected system dimensions as well as carrier gas/precursor mass flow rates. Temperature calibration was conducted to determine actual sample temperatures that are necessary for meaningful analysis of thermally induced transitions in ALD thin films. Several demonstrations of RHEED in the system are described. Calibration of the camera length was conducted using a gold thin film by analyzing RHEED images. Finally, RHEED conducted at a series of increasing temperatures was used to monitor the crystallization of an ALD HfO2 thin film. The crystallization temperature and the ring pattern were consistent with the monoclinic structure as determined by separate x-ray diffraction-based measurements. 

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