Search results for "Pounds"
showing 10 items of 3374 documents
Synaptic release of zinc from brain slices: factors governing release, imaging, and accurate calculation of concentration.
2006
Cerebrocortical neurons that store and release zinc synaptically are widely recognized as critical in maintenance of cortical excitability and in certain forms of brain injury and disease. Through the last 20 years, this synaptic release has been observed directly or indirectly and reported in more than a score of publications from over a dozen laboratories in eight countries. However, the concentration of zinc released synaptically has not been established with final certainty. In the present work we have considered six aspects of the methods for studying release that can affect the magnitude of zinc release, the imaging of the release, and the calculated concentration of released zinc. We…
Ligand effects on the structures and magnetic properties of tricyanomethanide-containing copper(II) complexes.
2007
The preparation, crystal structure and magnetic properties of four heteroleptic copper(II) complexes with the tricyanomethanide (tcm(-)) and the heterocyclic nitrogen donors 3,6-bis(2-pyridyl)pyridazine (dppn), 2,5-bis(2-pyridyl)pyrazine (2,5-dpp), 2,3-bis(2-pyridyl)pyrazine (2,3-dpp) and 2,3-bis(2-pyridyl)quinoxaline (2,3-dpq) are reported, {[Cu(2)(dppn)(OH)(tcm)(2)] x tcm}(n) (1), {[Cu(2,5-dpp)(tcm)] x tcm}(n) (2), {[Cu(2)(2,3-dpp)(2)(tcm)(3)(H(2)O)(0.5)] x tcm x 0.5H(2)O}(n) (3) and [Cu(2,3-dpq)(tcm)(2)](n) (4). 1 has a ladder-like structure with single mu-1,5-tcm ligands forming the sides and a bis-bidentate dppn and a single mu-hydroxo providing the rung. Each copper atom in 1 exhibits…
Evaluation of 2,3-epoxypropyl groups and functionalization yield in glycidyl methacrylate monoliths using gas chromatography
2014
Abstract Poly(glycidyl methacrylate- co -ethylene dimethacrylate) (poly(GMA- co -EDMA)) is most frequently used as parent monolith to obtain stationary phases with a variety of surface chemistries for liquid chromatography and capillary electrochromatography. Functionalization is performed by opening the accessible 2,3-epoxypropyl groups of the monolith with a suitable reagent. The number of 2,3-epoxypropyl groups which are accessible before and after the functionalization reaction, and the grafting yield, are important parameters, required both to optimize functionalization and to interpret the chromatographic performance of functionalized monoliths. In this work, a method capable of provi…
Raman scattering and infrared reflectivity in [(InP)5(In0.49Ga0.51As)8]30 superlattices
2000
6 páginas, 6 figuras, 1 tabla.
Controlling the Formation of Sodium/Black Phosphorus IntercalationCompounds Towards High Sodium Content
2021
The solid-state synthesis of pure sodium-black phosphorus intercalation compounds (Na-BPICs) has been optimized in bulk for two stoichiometric ratios. Specifically, in-situ X-Ray diffraction (XRD) allowed the precise identification of the optimal temperature range for the formation of Na-BPICs: 94°C–96°C. Moreover, as the undesired formation of Na3P takes place at this very same range, we succeeded in introducing a new synthetic route based on a fast-thermal ball milling implementation that results in the bulk production of BPIC without Na3P in 9 out of 10 cases. Finally, by combining XRD, Raman spectroscopy, and DFT calculations we developed a new structural model for Na-based BPICs showin…
Electron diffraction, X-ray powder diffraction and pair-distribution-function analyses to determine the crystal structures of Pigment Yellow 213, C23…
2009
The crystal structure of the nanocrystalline alpha phase of Pigment Yellow 213 (P.Y. 213) was solved by a combination of single-crystal electron diffraction and X-ray powder diffraction, despite the poor crystallinity of the material. The molecules form an efficient dense packing, which explains the observed insolubility and weather fastness of the pigment. The pair-distribution function (PDF) of the alpha phase is consistent with the determined crystal structure. The beta phase of P.Y. 213 shows even lower crystal quality, so extracting any structural information directly from the diffraction data is not possible. PDF analysis indicates the beta phase to have a columnar structure with a si…
Chirality and electronic structure of the thiolate-protected Au38 nanocluster.
2010
Structural, electronic, and optical properties of the thiolate-protected Au(38)(SR)(24) cluster are studied by density-functional theory computations (R = CH(3) and R = C(6)H(13)) and by powder X-ray crystallography (R = C(12)H(25)). A low-energy structure which can be written as Au(23)@(Au(SR)(2))(3)(Au(2)(SR)(3))(6) having a bi-icosahedral core and a chiral arrangement of the protecting gold-thiolate Au(x)(SR)(y) units yields an excellent match between the computed (for R = C(6)H(13)) and measured (for R = C(12)H(25)) powder X-ray diffraction function. We interpret in detail the electronic structure of the Au(23) core by using a particle-in-a-cylinder model. Although the alkane thiolate l…
Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, …
2013
A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromag…
Structural and vibrational properties of CdAl2S4 under high pressure: Experimental and theoretical approach
2014
The behavior of defect chalcopyrite CdAl2S4 at high pressures and ambient temperature has been investigated in a joint experimental and theoretical study. High-pressure X-ray diffraction and Raman scattering measurements were complemented with theoretical ab initio calculations. The equation of state and pressure dependences of the structural parameters of CdAl2S4 were determined and compared to those of other AB(2)X(4) ordered-vacancy compounds. The pressure dependence of the Raman-active mode frequencies is reported, as well as the theoretical phonon dispersion curves and phonon density of states at 1 atm. Our measurements suggest that defect chalcopyrite CdAl2S4 undergoes a phase transit…
High-pressure study of the behavior of mineral barite by x-ray diffraction
2011
In this paper, we report the angle-dispersive x-ray diffraction data of barite, BaSO 4, measured in a diamond-anvil cell up to a pressure of 48 GPa, using three different fluid pressure-transmitting media (methanol-ethanol mixture, silicone oil, and He). Our results show that BaSO 4 exhibits a phase transition at pressures that range from 15 to 27 GPa, depending on the pressure media used. This indicates that nonhydrostatic stresses have a crucial role in the high-pressure behavior of this compound. The new high-pressure (HP) phase has been solved and refined from powder data, having an orthorhombic P2 12 12 1 structure. The pressure dependence of the structural parameters of both room- and…