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34 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I22-Small angle scattering & Diffraction	Mix-and-match diols: adjusting self-assembly of micellar phases in choline chloride eutectics Oliver Hammond , Adrian Sanchez-Fernandez , Rachel Tyte , Robert Dalgliesh , Andrew J. Smith , Karen Edler Crystals 12 DOI: 10.3390/cryst12111621 Diamond Proposal Number(s): [15194] Open Access Show Abstract ▼ Abstract: The common Deep Eutectic Solvent (DES) ‘ethaline’ (1:2 choline chloride:ethylene glycol) was examined here as a basis for the self-assembly of the surfactant dodecyltrimethylammonium bromide (C12TAB). A phase diagram was constructed, showing evidence for a L1 (micellar) phase, confirmed by tensiometry to have a room temperature critical micelle concentration (CMC) of 1.2 wt.%. Small angle neutron scattering (SANS) measurements indicate formation of interacting globular micelles with slightly smaller apparent radii than in water. The apparent mesophase/multiphase region was studied using SWAXS, demonstrating rich mesoscopic lyotropic liquid crystalline phase behaviour, with evidence for lamellar Lα peaks, alongside potential co-crystalline phases. We attempted to tailor the self-assembly by studying binary DES containing longer diols including 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol, and ternary DES where the HBD component was a 1:1 ethylene glycol:diol mixture. However, synchrotron SAXS showed that only ternary ‘propethaline’ mixtures displayed signs of self-assembly and micellization, perhaps due to the reduction in calculated Gordon parameter, which decreases linearly with increasing alkyl chain length. Systematic differences were thus observed in the ability of the solvents to modulate assembly, from globular micelles in ChCl:EG, to weaker assembly in long-tail DES, and complete solubilisation in butaline and pentaline.	Nov 2022
E02-JEM ARM 300CF	Microstructure and anisotropic order parameter of boron-doped nanocrystalline diamond films Somnath Bhattacharyya Crystals 12 DOI: 10.3390/cryst12081031 Diamond Proposal Number(s): [18627] Open Access Show Abstract ▼ Abstract: Unconventional superconductivity in heavily boron-doped nanocrystalline diamond films (HBDDF) produced a significant amount of interest. However, the exact pairing mechanism has not been understood due to a lack of understanding of crystal symmetry, which is broken at the grain boundaries. The superconducting order parameter (Δ) of HBDDF is believed to be anisotropic since boron atoms form a complex structure with carbon and introduce spin-orbit coupling to the diamond system. From ultra-high resolution transmission electron microscopy, the internal symmetry of the grain boundary structure of HBDDF is revealed, which can explain these films’ unconventional superconducting transport features. Here, we show the signature of the anisotropic Δ in HBDDF by breaking the structural symmetry in a layered microstructure, enabling a Rashba-type spin-orbit coupling. The superlattice-like structure in diamond describes a modulation that explains strong insulator peak features observed in temperature-dependent resistance, a transition of the magnetic field-dependent resistance, and their oscillatory, as well as angle-dependent, features. Overall, the interface states of the diamond films can be explained by the well-known Shockley model describing the layers connected by vortex-like structures, hence forming a topologically protected system.	Jul 2022
I04-Macromolecular Crystallography	Through diffusion measurements of molecules to a numerical model for protein crystallization in viscous polyethylene glycol solution Hiroaki Tanaka , Rei Utata , Keiko Tsuganezawa , Sachiko Takahashi , Akiko Tanaka Crystals 12 DOI: 10.3390/cryst12070881 Open Access Show Abstract ▼ Abstract: Protein crystallography has become a popular method for biochemists, but obtaining high-quality protein crystals for precise structural analysis and larger ones for neutron analysis requires further technical progress. Many studies have noted the importance of solvent viscosity for the probability of crystal nucleation and for mass transportation; therefore, in this paper, we have reported on experimental results and simulation studies regarding the use of viscous polyethylene glycol (PEG) solvents for protein crystals. We investigated the diffusion rates of proteins, peptides, and small molecules in viscous PEG solvents using fluorescence correlation spectroscopy. In high-molecular-weight PEG solutions (molecular weights: 10,000 and 20,000), solute diffusion showed deviations, with a faster diffusion than that estimated by the Stokes–Einstein equation. We showed that the extent of the deviation depends on the difference between the molecular sizes of the solute and PEG solvent, and succeeded in creating equations to predict diffusion coefficients in viscous PEG solutions. Using these equations, we have developed a new numerical model of 1D diffusion processes of proteins and precipitants in a counter-diffusion chamber during crystallization processes. Examples of the application of anomalous diffusion in counter-diffusion crystallization are shown by the growth of lysozyme crystals.	Jun 2022
I04-Macromolecular Crystallography	Secondary structure and X-ray crystallographic analysis of the glideosome-associated connector (GAC) from Toxoplasma gondii Amit Kumar , Xu Zhang , Oscar Vadas , Fisentzos A. Stylianou , Nicolas Dos Santos Pacheco , Sarah L. Rouse , Marc L. Morgan , Dominique Soldati-Favre , Steve Matthews Crystals 12 DOI: 10.3390/cryst12010110 Open Access Show Abstract ▼ Abstract: A model for parasitic motility has been proposed in which parasite filamentous actin (F-actin) is attached to surface adhesins by a large component of the glideosome, known as the glideosome-associated connector protein (GAC). This large 286 kDa protein interacts at the cytoplasmic face of the plasma membrane with the phosphatidic acid-enriched inner leaflet and cytosolic tails of surface adhesins to connect them to the parasite actomyosin system. GAC is observed initially to the conoid at the apical pole and re-localised with the glideosome to the basal pole in gliding parasite. GAC presumably functions in force transmission to surface adhesins in the plasma membrane and not in force generation. Proper connection between F-actin and the adhesins is as important for motility and invasion as motor operation itself. This notion highlights the need for new structural information on GAC interactions, which has eluded the field since its discovery. We have obtained crystals that diffracted to 2.6–2.9 Å for full-length GAC from Toxoplasma gondii in native and selenomethionine-labelled forms. These crystals belong to space group P212121; cell dimensions are roughly a = 119 Å, b = 123 Å, c = 221 Å, α = 90°, β = 90° and γ = 90° with 1 molecule per asymmetric unit, suggesting a more compact conformation than previously proposed.	Jan 2022
I04-1-Macromolecular Crystallography (fixed wavelength)	Novel device and strategy for growing large, high-quality protein crystals by controlling crystallization conditions Naoki Tanigawa , Sachiko Takahashi , Bin Yan , Masayuki Kamo , Naoki Furubayashi , Koji Kubota , Koji Inaka , Hiroaki Tanaka Crystals 11 DOI: 10.3390/cryst11111311 Diamond Proposal Number(s): [12421] Open Access Show Abstract ▼ Abstract: Neutron diffraction experiments are informative for determining the locations of hydrogen atoms in protein molecules; however, much larger crystals are needed than those required for X-ray diffraction. Thus, additional techniques are required to grow larger crystals. Here, a unique crystallization device and strategy for growing large protein crystals are introduced. The device uses two micropumps to control crystal growth by altering the precipitant concentration and regulating the pinpoint injection of dry air flow to the crystallization cell. Furthermore, the crystal growth can be observed in real time. Preliminary microbatch crystallization experiments at various concentration ranges of polyethylene glycol (PEG) 4000 and sodium chloride were first performed to elucidate optimized crystallization conditions. Based on these results, a device to precisely control the sodium chloride and PEG concentrations and the supply of dry air to the crystallization cell was used, and 1.8 mm lysozyme and 1.5 mm alpha-amylase crystals with good reproducibility were obtained. X-ray data sets of both crystals were collected at room temperature at BL2S1 of the Aichi Synchrotron Radiation Center and confirmed that these crystals were of high quality. Therefore, this crystallization device and strategy were effective for growing large, high-quality protein crystals.	Nov 2021
I04-Macromolecular Crystallography	Molecular characterization of the native (non-linked) CD160–HVEM protein complex revealed by initial crystallographic analysis Simona Lenhartová , Marek Nemčovič , Radka Šebová , Mário Benko , Dirk M. Zajonc , Ivana Nemcovicova Crystals 11 DOI: 10.3390/cryst11070820 Diamond Proposal Number(s): [26567, 20221] Open Access Show Abstract ▼ Abstract: An increasing number of surface-exposed ligands and receptors acting on immune cells are being considered as a starting point in drug development applications. As they are dedicated to manipulating a wide range of immune responses, accurately predicting their molecular interactions will be necessary for the development of safe and effective therapeutics to enhance immune responses and vaccination. Here, we focused on the characterization of human CD160 and HVEM immune receptors, whose mutual engagement leads to bidirectional signaling (e.g., T cell inhibition, natural killer cell activation or mucosal immunity). In particular, our study reports on the molecule preparation, characterization and initial crystallographic analysis of the CD160–HVEM complex and both HVEM and CD160 in the absence of their binding partner. Despite the importance of the CD160–HVEM immune signaling and its therapeutic relevance, the structural and mechanistic basis underlying CD160–HVEM engagement has some controversial evidence. On one hand, there are studies reporting on the CD160 molecule in monomeric form that was produced by refolding from bacterial cells, or as a covalently linked single-chain complex with its ligand HVEM in insect cells. On the other hand, there are older reports providing evidence on the multimeric form of CD160 that acts directly on immune cells. In our study, the native non-linked CD160–HVEM complex was co-expressed in the baculovirus insect host, purified to homogeneity by anion-exchange chromatography to provide missing evidence of the trimeric form in solution. Its trimeric existence was also confirmed by the initial crystallographic analysis. The native CD160–HVEM complex crystallized in the orthorhombic space group with unit cell parameters that could accommodate one trimeric complex (3:3) in an asymmetric unit, thus providing ample space for the multimeric form. Crystals of the CD160–HVEM complex, CD160 trimer and HVEM monomer (reported in two space groups) diffracted to a minimum Bragg spacing of 2.8, 3.1 and 1.9/2.1 Å resolution, respectively. The obtained data will lead to elucidating the native structure of the complex.	Jul 2021
I19-Small Molecule Single Crystal Diffraction	High-pressure crystal structure and unusual magnetoresistance of a single-component molecular conductor [Pd(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) Hengbo Cui , Hamish H.-M. Yeung , Yoshitaka Kawasugi , Takaaki Minamidate , Lucy K. Saunders , Reizo Kato Crystals 11 DOI: 10.3390/cryst11050534 Diamond Proposal Number(s): [20934] Open Access Show Abstract ▼ Abstract: A single-component molecular crystal [Pd(dddt)2] has been shown to exhibit almost temperature-independent resistivity under high pressure, leading theoretical studies to propose it as a three-dimensional (3D) Dirac electron system. To obtain more experimental information about the high-pressure electronic states, detailed resistivity measurements were performed, which show temperature-independent behavior at 13 GPa and then an upturn in the low temperature region at higher pressures. High-pressure single-crystal structure analysis was also performed for the first time, revealing the presence of pressure-induced structural disorder, which is possibly related to the changes in resistivity in the higher-pressure region. Calculations based on the disordered structure reveal that the Dirac cone state and semiconducting state coexist, indicating that the electronic state at high pressure is not a simple Dirac electron system as previously believed. Finally, the first measurements of magnetoresistance on [Pd(dddt)2] under high pressure are reported, revealing unusual behavior that seems to originate from the Dirac electron state.	May 2021
	Bulk and surface conformations in solid-state lovastatin: Spectroscopic and molecular dynamics studies Anuradha R. Pallipurath , Jonathan M. Skelton , Andrew Britton , Elizabeth A. Willneff , Sven Schroeder Crystals 11 DOI: 10.3390/cryst11050509 Open Access Show Abstract ▼ Abstract: Conformational flexibility in molecules can give rise to a range of functional group terminations at crystal surfaces and dynamic disorder in the bulk. In this work, we explore the conformational behavior of the drug molecule lovastatin in the crystallographically disordered solid and at crystal surfaces through a combination of computational modeling and spectroscopy. Gas-phase and periodic quantum-chemical calculations are used to study the potential energy surface associated with rotatable bonds to examine the disorder in bulk. These calculations are combined with vibrational and X-ray photoelectron spectroscopy measurements to obtain insight into the conformations in bulk and at the surface. Our MD simulations show that the bulk disorder is driven by cooperative motion of the butyl group on the S-butanoate moiety along one crystallographic direction beyond a unit cell. The calculations show that the O-H group can rotate relatively freely between two low-energy conformers in the gas phase but is locked in position by intermolecular H-bonding interactions in the bulk crystal, and we find tentative spectroscopic evidence for the second conformer being present at the surface. We also comment on the relative utility of these different techniques for studying molecular conformation in bulk and at surfaces and highlight possible areas for future developments.	May 2021
I15-Extreme Conditions	P–V–T equation of state of iridium up to 80 GPa and 3100 K Simone Anzellini , Leonid Burakovsky , Robin Turnbull , Enrico Bandiello , Daniel Errandonea Crystals 11 DOI: 10.3390/cryst11040452 Diamond Proposal Number(s): [21610] Open Access Show Abstract ▼ Abstract: In the present study, the high-pressure high-temperature equation of the state of iridium has been determined through a combination of in situ synchrotron X-ray diffraction experiments using laser-heating diamond-anvil cells (up to 48 GPa and 3100 K) and density-functional theory calculations (up to 80 GPa and 3000 K). The melting temperature of iridium at 40 GPa was also determined experimentally as being 4260 (200) K. The results obtained with the two different methods are fully consistent and agree with previous thermal expansion studies performed at ambient pressure. The resulting thermal equation of state can be described using a third-order Birch–Murnaghan formalism with a Berman thermal-expansion model. The present equation of the state of iridium can be used as a reliable primary pressure standard for static experiments up to 80 GPa and 3100 K. A comparison with gold, copper, platinum, niobium, rhenium, tantalum, and osmium is also presented. On top of that, the radial-distribution function of liquid iridium has been determined from experiments and calculations.	Apr 2021
B23-Circular Dichroism	A facile synthesis of a room-temperature chiral discotic nematic liquid crystal based on pentaalkynylbenzene core Huanan Yu , Georg H. Mehl Liquid Crystals 2, 1 - 8 DOI: 10.1080/02678292.2021.1900433 Show Abstract ▼ Abstract: The preparation of discotic liquid crystal with a wide thermal nematic phase range remains a challenge. Here, a method to synthesise a class of discotic liquid crystal with exclusive and stable chiral nematic phase over a wide temperature range, based on pentaalkynylbenzene core, is presented and the mesogenic properties are well studied.	Mar 2021

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