Read by QxMD icon Read

crystal structure

A Garbout, M Férid
Considering the features in changing the structure and properties of rare earth titanates pyrochlores, the substituted Dy2 Ti2 O7 may be very attractive for various applications. Effect of Sm and Y substitution on the structural properties of Dy2 Ti2 O7 ceramic was established. These ceramics were prepared by solid-state reaction and characterized by X-ray diffraction and Raman spectroscopy. Both analysis show that YDyTi2 O7 with the pyrochlore structure is obtained after heating at 1400°C, but SmDyTi2 O7 has already formed after sintering at 1200°C...
March 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Ayaka Sato, Yuya Ikeda, Koichi Yamaguchi, Varun Vohra
Facile detection and the identification of hazardous organic solvents are essential for ensuring global safety and avoiding harm to the environment caused by industrial wastes. Here, we present a simple method for the fabrication of silver-coated monodisperse polystyrene nanoparticle photonic structures that are embedded into a polydimethylsiloxane (PDMS) matrix. These hybrid materials exhibit a strong green iridescence with a reflectance peak at 550 nm that originates from the close-packed arrangement of the nanoparticles...
March 16, 2018: Nanomaterials
Hirofumi Akamatsu, Yakun Yuan, Vladimir A Stoica, Greg Stone, Tiannan Yang, Zijian Hong, Shiming Lei, Yi Zhu, Ryan C Haislmaier, John W Freeland, Long-Qing Chen, Haidan Wen, Venkatraman Gopalan
Using time- and spatially resolved hard x-ray diffraction microscopy, the striking structural and electrical dynamics upon optical excitation of a single crystal of BaTiO_{3} are simultaneously captured on subnanoseconds and nanoscale within individual ferroelectric domains and across walls. A large emergent photoinduced electric field of up to 20×10^{6}  V/m is discovered in a surface layer of the crystal, which then drives polarization and lattice dynamics that are dramatically distinct in a surface layer versus bulk regions...
March 2, 2018: Physical Review Letters
Shenglong Xu, Congjun Wu
Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic "space-time" crystal characterized by the general intertwined space-time periodicities in D+1 dimensions, which include both the static crystal and the Floquet crystal as special cases. A new group structure dubbed a "space-time" group is constructed to describe the discrete symmetries of a space-time crystal. Compared to space and magnetic groups, the space-time group is augmented by "time-screw" rotations and "time-glide" reflections involving fractional translations along the time direction...
March 2, 2018: Physical Review Letters
Joyce Pham, Gordon J Miller
Using density functional theory, the crystal structure variation of AAuAl (A = Ca, Sc, and Ti) from orthorhombic Co2 Si-type to distorted hexagonal Fe2 P-type and then Ni2 In-type structures is shown to correlate with their electronic structures and valence electron counts, sizes of the active metals A, and site preferences for Au and Al atoms, which are arranged to maximize Au-Al nearest neighbor contacts. An evaluation of chemical pressure imposed by the varying A metals using total energy vs volume calculations indicates that larger unit cell volumes favor the orthorhombic structure, whereas smaller volumes favor the hexagonal structures...
March 16, 2018: Inorganic Chemistry
Masha M Rosenberg, Alfred G Redfield, Mary Roberts, Lizbeth Hedstrom
The ability of enzymes to modulate the dynamics of bound substrates and cofactors is a critical feature of catalysis, but the role of dynamics has largely been approached from the perspective of the protein. Here we use an underappreciated NMR technique, subtesla high resolution field cycling31 P NMR relaxometry, to interrogate the dynamics of enzyme bound substrates and cofactors in guanosine-5'-monophosphate reductase (GMPR). These experiments reveal distinct binding modes and dynamic profiles associated with the31 P nuclei in the Michaelis complexes for the deamination and hydride transfer steps of the catalytic cycle...
March 16, 2018: Biochemistry
Nicolas Daffern, Zhonglei Chen, Yongbo Zhang, Leslie Pick, Ishwar Radhakrishnan
The ligand-binding domains (LBD) of the NR5A subfamily of nuclear receptors activate transcription via ligand-dependent and ligand-independent mechanisms. The Drosophila Ftz-F1 receptor (NR5A3) belongs to the latter category and its ligand-independence is attributed to a short helical segment (6) within the protein that resides in the canonical ligand-binding pocket (LBP) in the crystalline state. Here, we show that the 6 helix is dynamic in solution when Ftz-F1 is bound to the LxxLL motif of its cofactor Ftz, undergoing motions on the fast (picosecond-nanosecond) as well as slow (microsecond-millisecond) timescales...
March 16, 2018: Biochemistry
Si Xuan She, Jie Yu, Wan Qi Tang, Yinlong Zhu, Yu Bo Chen, Jaka Sunarso, Wei Zhou, Zongping Shao
Perovskite oxide is an attractive low-cost alternative catalyst for oxygen evolution reaction (OER) relative to the precious metal oxide-based eletrocatalysts (IrO2 and RuO2). In this work, a series of Sr-doped La-based perovskite oxide catalysts with compositions of La1-xSrxFeO3-δ (x = 0, 0.2, 0.5, 0.8, and 1) are synthesized and characterized. The OER specific activities in alkaline solution increase in the order of LaFeO3-δ (LF), La0.8Sr0.2FeO3-δ (LSF-0.2), La0.5Sr0.5FeO3-δ (LSF-0.5), SrFeO3-δ (SF) and La0...
March 16, 2018: ACS Applied Materials & Interfaces
Chen Zou, Xiaojuan Zhao, Yan Xu
We report a novel, one-dimensional zirconium-doped layered trititanate with a porous core and a textured surface of ultrafine nanofibers (∼5 nm) by the hydrothermal alkaline treatment of electrospun fibers. It demonstrates superior efficiency for rapid, capacitive and simultaneous removal of multiple heavy metal ions such as Pb2+, Cd2+, Cu2+ and Zn2+. The adsorption is exceptionally rapid, showing 100% removal of Cu2+ in 10 min, and 100% removal of Pb2+ and Cd2+ in 20 min in water with a wide range of concentrations from 0...
March 16, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Paween Mahinthichaichan, Robert B Gennis, Emad Tajkhorshid
Cytochrome aa3 is the terminal respiratory enzyme of all eukaryotes and many bacteria and archaea, reducing O2 to water and harnessing the free energy from the reaction to generate the transmembrane electrochemical potential. The diffusion of O2 to the heme-copper catalytic site, which is buried deep inside the enzyme, is the initiation step of the reaction chemistry. Our previous molecular dynamics (MD) study with cytochrome ba3 , a homologous enzyme of cytochrome aa3 in Thermus thermophilus, demonstrated that O2 diffuses from the lipid bilayer to its reduction site through a 25-Å long tunnel inferred by Xe-binding sites detected by X-ray crystallography$ ...
March 16, 2018: Biochemistry
Tadashi Sugahara, Yuichiro Takamatsu, Avinash Bhadani, Masaaki Akamatsu, Kenichi Sakai, Masahiko Abe, Hideki Sakai
In this study, we synthesize a novel oleic acid-based gemini surfactant with carboxylate headgroups, and study the effect of stereochemistry (anti- vs. syn-) on self-aggregation properties in water. We investigate these properties using phase diagrams, static surface tension, and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) measurements. We find that a phase transition from a hexagonal liquid crystal (H1) phase to a lamellar liquid crystal (Lα) phase occurs at a lower surfactant concentration in the syn form, when compared with the anti form...
March 16, 2018: Physical Chemistry Chemical Physics: PCCP
Nathan A Bowden, Johan P M Sanders, Marieke E Bruins
The addition of organic solvents to α-amino acids in aqueous solution could be an effective method in crystallization. We reviewed the available data on the solubility of α-amino acids in water, water-ethanol mixtures, and ethanol at 298.15 K and 0.1 MPa. The solubility of l-alanine, l-proline, l-arginine, l-cysteine, and l-lysine in water and ethanol mixtures and the solubility of l-alanine, l-proline, l-arginine, l-cysteine, l-lysine, l-asparagine, l-glutamine, l-histidine, and l-leucine in pure ethanol systems were measured and are published here for the first time...
March 8, 2018: Journal of Chemical and Engineering Data
H C Sun, Z L Ning, G Wang, W Z Liang, S Pauly, Y J Huang, S Guo, X Xue, J F Sun
ZrCu-based bulk metallic glass composites (BMGCs) are well known for their plastic deformability, superior to traditional metallic glasses (MGs), which is attributed to a unique dual-phases structure, namely, the glassy matrix and unstable B2 phase. In the present study, in-situ tensile testing is used to trace the deformation process of a ZrCu-based BMGC. Three deformation stages of the BMGC, i.e., the elastic-elastic stage, the elastic-plastic stage, and the plastic-plastic stage are identified. In the elastic-elastic and elastic-plastic stages, the yield strength and elastic limit are major influenced by the volume fraction of the B2 crystals...
March 15, 2018: Scientific Reports
Morgane Dolhen, Masayuki Tanaka, Vincent Couderc, Sébastien Chenu, Gaëlle Delaizir, Tomokatsu Hayakawa, Julie Cornette, François Brisset, Maggy Colas, Philippe Thomas, Jean-René Duclère
We report on the laser emission of the polycrystalline ceramic obtained from the full and congruent crystallization of the parent glass 1Nd3+ :75TeO2 -12.5Bi2 O3 -12.5Nb2 O5 composition. In particular, the current work underlines the importance of carefully controlling the heat treatment in order to solely crystallize the Bi0.8 Nb0.8 Te2.4 O8 cubic phase and consequently avoid the formation of the BiNbTe2 O8 orthorhombic phase that would be detrimental for optical purpose. The structure, microstructure and photoluminescence properties of the resulting transparent tellurite ceramics are characterized...
March 15, 2018: Scientific Reports
Cheryl Suwen Law, Siew Yee Lim, Abel Santos
This study presents a nanofabrication approach that enables the production of nanoporous anodic alumina distributed Bragg reflectors (NAA-DBRs) with finely engineered light filtering features across the spectral regions. The photonic stopband (PSB) of these NAA-based photonic crystal (PC) structures is precisely tuned by an apodization strategy applied during stepwise pulse anodization with the aim of engineering the effective medium of NAA-DBRs in depth. We systematically assess the effect of different fabrication parameters such as apodization function (i...
March 15, 2018: Scientific Reports
Sandrina Lampis, Maura Carboni, Daniela Steri, Sergio Murgia, Maura Monduzzi
Lipid based formulations, endowed of long term stability as a result of the formation of lamellar liquid crystals, were prepared using the natural lipids lecithin and glycerol trioleate in water, and characterized using optical microscopy, SAXRD and NMR. The formulations, designed as possible carriers for lysozyme and caffeine, were evaluated for structural features and stability after the loading of the guest molecules. Release experiments were performed at 37 °C using the PBS medium. No burst release was observed either for lysozyme or caffeine...
March 2, 2018: Colloids and Surfaces. B, Biointerfaces
Komathy Munusamy, Jamuna Vadivelu, Sun Tee Tay
BACKGROUND: Biofilm is known to contribute to the antifungal resistance of Candida yeasts. Aureobasidin A (AbA), a cyclic depsipeptide targeting fungal sphingolipid biosynthesis, has been shown to be effective against several Candida species. AIMS: The aim of this study was to investigate Candida biofilm growth morphology, its biomass, metabolic activity, and to determine the effects of AbA on the biofilm growth. METHODS: The biofilm forming ability of several clinical isolates of different Candida species from our culture collection was determined using established methods (crystal violet and XTT assays)...
March 12, 2018: Revista Iberoamericana de Micología
Sebastian Hiller, Björn M Burmann
Living cells contain molecular chaperones that are organized in intricate networks to surveil protein homeostasis by avoiding polypeptide misfolding, aggregation, and the generation of toxic species. In addition, cellular chaperones also fulfill a multitude of alternative functionalities: transport of clients towards a target location, help them fold, unfold misfolded species, resolve aggregates, or deliver clients towards proteolysis machineries. Until recently, the only available source of atomic resolution information for virtually all chaperones were crystal structures of their client-free, apo-forms...
April 2018: Journal of Magnetic Resonance
Giovanni Rillo, Miguel A Morales, David M Ceperley, Carlo Pierleoni
We performed simulations for solid molecular hydrogen at high pressures (250 GPa ≤ P ≤ 500 GPa) along two isotherms at T = 200 K (phase III) and at T = 414 K (phase IV). At T = 200 K, we considered likely candidates for phase III, the C2c and Cmca12 structures, while at T = 414 K in phase IV, we studied the Pc48 structure. We employed both Coupled Electron-Ion Monte Carlo (CEIMC) and Path Integral Molecular Dynamics (PIMD). The latter is based on Density Functional Theory (DFT) with the van der Waals approximation (vdW-DF)...
March 14, 2018: Journal of Chemical Physics
Kazuhiro Takemura, Nobuyuki Matubayasi, Akio Kitao
To aid the evaluation of protein-protein complex model structures generated by protein docking prediction (decoys), we previously developed a method to calculate the binding free energies for complexes. The method combines a short (2 ns) all-atom molecular dynamics simulation with explicit solvent and solution theory in the energy representation (ER). We showed that this method successfully selected structures similar to the native complex structure (near-native decoys) as the lowest binding free energy structures...
March 14, 2018: Journal of Chemical Physics
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"