Vacant Channels Research Articles

Topological evolution in uranyl dicarboxylates: synthesis and structures of one-dimensional UO2(C6H8O4)(H2O)2 and three-dimensional UO2(C6H8O4).

Two novel uranyl adipates are reported as synthesized via hydrothermal treatment of uranium oxynitrate and adipic acid. One-dimensional UO(2)(C(6)H(8)O(4))(H(2)O)(2) (1) [a = 9.6306(6) A, c = 11.8125(10) A, tetragonal, P4(3)2(1)2 (No. 96), Z = 4] consists of chains of (UO(2))O(4)(H(2)O)(2) hexagonal bipyramids tethered through a linear adipic acid backbone. Three-dimensional UO(2)(C(6)H(8)O(4)) (2) [a = 5.5835(12) A, b = 8.791(2) A, c = 9.2976(17) A, alpha = 87.769(9) degrees, beta = 78.957(8) degrees, gamma = 81.365(11) degrees, triclinic, P1 (No. 2), Z = 2] is produced by decreasing the hydration level of the reaction conditions. This structure contains a previously unreported [(UO(2))(2)O(8)] building unit cross-linked into a neutral metal-organic framework topology with vacant channels.

Variation of hydrogen bonded O…O distances in goethite at high pressure

In-situ synchrotron X-ray powder diffraction experiments on goethite were performed up to 24.5 GPa using a diamond-anvil cell at BL-18C in the Photon Factory, Japan. The compression behavior of goethite is anisotropic: the a axis, which is close to the direction of the hydrogen bond, is almost twice as compressible as the b and c axes. A second-order Birch-Murnaghan fit (K' = 4) to the unitcell volumes and pressures up to 24 GPa gave a bulk modulus K0 = 111(2) GPa. The pressure medium apparently affects the compression behavior of goethite, as a sudden strain broadening occurs above 11 GPa, where solidification of the 4:1 methanol:ethanol pressure medium occurs. The crystal structure of goethite was refined by means of the Rietveld method at several pressures below 10 GPa. The main compression occurs in the “vacant channels” in the crystal structure, where the OH ···O bridges are located. The hydrogen-bonded O···O distance shortens with increasing pressure at the rate of about -0.023 Å/GPa and reaches 2.60(1) Å at 9 GPa.

Musical sound signal generation apparatus

There is disclosed a musical sound signal generation apparatus for creating vacant channels by monaural sounding, in which a left/right balance is maintained and the total sound volume can be increased. When there is a key-on, and there is no vacant channel, a pair of channels for stereo sounding are selected, one channel of the pair of channels is released at a high rate, the panning coefficient of the other channel is changed, and a monaural sound is outputted from left and right output systems. Similarly, another pair of channels are selected, one channel of the pair of channels is released at the high rate, the panning coefficient of the other channel is changed, and the monaural sound is outputted from the left and right output systems. The L and R channels of the new key-on are assigned to two vacant channels.

Vacant TV channel reuse by extremely low power bidirectional SS using universal timing synchronization

Vacant TV channel reuse by extremely low power bidirectional SS using universal timing synchronization

Vacant TV channel reuse by extremely low power bidirectional SS using universal timing synchronization

Vacant TV channel reuse by extremely low power bidirectional SS using universal timing synchronization

4-Hydroxypipecolic Acid and Pipecolic Acid in Acacia Species: Their Determination by High-Performance Liquid Chromatography, Its Application to Leguminous Plants, and Configuration of 4-Hydroxypipecolic Acid

A new method for the determination of naturally occurring imino acids in plants was devised. This method comprises the formation of dinitrophenyl derivatives and their measurement by HPLC. The determination limits were 100 pmol for 4-hydroxypipecolic acid (HPA) and proline (Pro) and 10 pmol for pipecolic acid (Pip). The recoveries of HPA, Pro, and Pip from leaf homogenate of an Acacia species were 95.9 ± 2.8, 100.5 ± 1.7, and 101.1 ± 2.3%, respectively. HPA was found in leaves, seeds, and roots of five kinds of Acacia but not in leaves of other members of the legume family. The HPA content of Acacia dealbata link leaves was much higher in winter than in summer. From X-ray analysis, HPA was found to be hydrated by two water molecules that are situated in a vacant channel formed by the molecular arrangement of HPA. HPA had no remarkable physiological or pharmaceutical activities. Keywords: 4-Hydroxypipecolic acid; pipecolic acid; Acacia species; leguminous plants; determination

Crystal Structures of Ca5Cr3O12 and Ca5Cr2SiO12, the Chromium Analogs of Silicocarnotite

The crystal structures of Ca5Cr3O12 and Ca5Cr1.8Si1.2O12, the chromium analogues of silicocarnotite, Ca5P2SiO12, have been determined. Both compounds were grown at 1250°C and analyzed by electron microprobe analysis. Diffraction data collection was done on spherically ground crystals which are both orthorhombic with space group Pnma. Charge‐balance requirements as well as siteoccupancy refinement of the Si‐containing compound point strongly to the presence of both tetravalent and hexavalent chromium in tetrahedral sites. The Si is located together with tetravalent Cr in a general position, whereas the hexavalent Cr is situated on a mirror plane. The calcium atoms are located in seven‐, eight‐, and nine‐coordinated sites. The presence of vacant channels of 3.5 Å diameter perpendicular to (100) is a feature of this structural type. Its relation to the apatite and glaserite structures is also shown.

ChemInform Abstract: Lithium/V9Mo6O40 Cells.

AbstractIt is demonstrated that Li+ can be reversibly intercalated into vacant channels of the V9Mo6O40 structure; therefore this material is a promising cathode candidate for secondary lithium batteries.

Exploration of structure and bonding in stishovite with fourier and pseudoatom refinement methods using single crystal and powder X-ray diffraction data

The structure and bonding in stishovite, SiO2, is explored with Fourier summation and pseudoatom refinement of merged x-ray single crystal and powder diffraction data. Replacement of the 25 lowest-angle, highly extinction-affected, single crystal reflections with structure factors obtained from low-extinction powder diffraction data has resulted in a significant improvement in the analysis compared with earlier studies. The deformation electron density, total electrostatic potential and total and valence electron densities are mapped. Accumulations of electron density are observed in both SiO bonds, together with non-bonding features displayed about the oxygen on both sides of a plane formed by three bonds with Si. Deficits of electron density between O atoms across the shared-edges are rationalized in terms of the Pauli exclusion principle. There is no evidence for strong repulsion of Si atoms across the same ring. The total electrostatic potential has a continuous low value for the vacant channels in the structure along c with localized minima between O atoms on opposite sides of the channel. The sizes of Si and O are related to the electron density and to the electrostatic potential.

Traffic characteristics of digital pair‐loop network in common usage of channels

AbstractAn integrated digital pair‐loop network with ring topology of optical fiber cables as a new type of communication systems for interoffice trunk networks in regional service areas is proposed. The pairloop network has a feature in that several switching offices share bidirectional transmission channels, and thus the channels can be utilized in common by several trunk groups of offices belonging to the system. However, if vacant channels are selected arbitrarily and assigned to any calls, blocking probability depends on the office location and a definite grade of service can not be expected. This paper shows that the channel assignment following an algorithm called the channel‐pair selection rule makes it possible for the trunk group to achieve a definite grade of service and improves channel efficiency. It is shown also that analytical results are in good agreement with simulation results.