the carboxylatophenoxyacetate dianion links the water- and imidazole-coordinated Cd atoms into a zigzag chain that runs along the c axis of the monoclinic unit cell; the chelation by the carboxylate arms leads to a seven-coordinate pentagonal– bipyramidal geometry for the Cd atom. The chains are linked into a three-dimensional network by hydrogen bonds.
chloride anions occupy the axial positions. Each L ligand links two Co II ions, forming an infinite zigzag chain propagating along the c-axis direction and further stabilized by O—H Cl hydrogen bonds between the methanol molecules and the chloride anions. Adjacent chains in the structure are connected by intermolecular C—H Cl hydrogen bonds, resulting in the formation of a three-dimensional supramolecular architecture.
octahedra (Fig. 1). Each BTC ligand bridges two Co II atoms to form a polymeric zigzag chain, and these are further linked via O—H O hydrogen bonds to form a three-dimensional network (Table 1). Two carboxylate groups of the BTC ligand coordinate to Co II atoms, one in a monodentate fashion and the other in a bidentate chelating fashion. The third
Molecular packing in (I): (a) supramolecular zigzag chain aligned along  and sustained by O—H O hydrogen bonding, with the solvent pyridine molecules attached via O—H N hydrogen bonding, (b) a view of the unit-cell contents in projection down the a axis and (c) supramolecular chain along the b axis sustained by (pyridine)C— H (chelate ring) interactions. The O—H O, O—H N, C—H O, – and C—H (chelate ring) interactions are shown as orange, blue, brown, purple and pink dashed lines, respectively.
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The existence of Wigner crystallization 1 , one of the most significant hallmarks of strong elec- tron correlations, has to date only been definitively observed in two-dimensional systems. In one-dimensional (1D) quantum wires Wigner crystals correspond to regularly spaced elec- trons; however, weakening the confinement and allowing the electrons to relax in a second dimension is predicted to lead to the formation of a new ground state constituting a zigzag chain with nontrivial spin phases and properties 2–7 . Here we report the observation of such zigzag Wigner crystals by use of on-chip charge and spin detectors employing electron focus- ing to image the charge density distribution and probe their spin properties. This experiment demonstrates both the structural and spin phase diagrams of the 1D Wigner crystallization. The existence of zigzag spin chains and phases which can be electrically controlled in semi- conductor systems may open avenues for experimental studies of Wigner crystals and their technological applications in spintronics and quantum information.
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bits a pseudo-C-centring which is almost fulfilled by the polymeric metal complex but not by the solvent dimethylform- amide (DMF) molecules. The asymmetric unit contains two independent Cd II ions, two m-bdc 2 ligands, one and two half bix ligands, and two solvent DMF molecules. The Cd II ions are both five-coordinated by three O atoms from two different m- bdc 2 ligands and two N atoms from two different bix ligands in a distorted square-pyramidal geometry. The m-bdc 2 ligands adopt a chelate-monodentate coordination mode, connecting neighboring Cd II ions into a zigzag chain parallel to . Adjacent chains are further cross-linked by bix ligands, giving rise to a puckered sheet nearly perpendicular to the chain direction. Thus, each Cd II ion is connected to four neighboring Cd II ions through two m-bdc 2 anions and two bix ligands, giving rise to the final non-interpenetrating uninodal layer with sql (4,4) topology.
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are arranged as B-C-N-C along the zigzag lines using a tight binding (TB) model . The TB approximation is an efficient method to describe the electronic properties compared with the density functional theories (DFT). In the TB approximation, however, the effect of the charge transfer is absent, resulting in the failure of TB model for B- and N-doped nanocarbon system. The purpose of the paper was to investigate the effect of charge transfer in BC 2 N nanoribbons theoretically.
Charge transport through two sets of symmetric graphene nanoribbons with zigzag shaped edges in a two-terminal device has been investigated, using density functional theory combined with the non- equilibrium Green’s function method. The conductance has been explored as a function of nanorib- bon length, bias voltage, and the strength of terminal coupling. The set of narrower nanoribbons, in the form of thiolated linear acenes, shows an anomalous length dependence of the conductance, which at first exhibits a drop and a minimum, followed by an evident rise. The length trend is shown to arise because of a gradual transformation in the transport mechanism, which changes from being governed by a continuum of out-of-plane π type and in-plane state channels to being fully con- trolled by a single, increasingly more resonant, occupied π state channel. For the set of nanoribbons with a wider profile, a steady increase is observed across the whole length range, owing to the ab- sence of the former transport mechanism. The predicted trends are confirmed by the inclusion of self-interaction correction in the calculations. For both sets of nanoribbons the replacement of the strongly coupling thiol groups by weakly bonding phenathroline has been found to cause a strong attenuation with the length and a generally low conductance. © 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773020]
In summary, our theoretical calculations indicate that by appropriate n -type and p -type doping, one can obtain much higher ZT values for both the zigzag and armchair CNTs, and those tubes with an intermediate diameter (0.7 to 0.8 nm) seems to have better thermoelectric prop- erties than others. With the zigzag (10,0) as an example, we show that the phonon-induced thermal conductance can be effectively reduced by isotope substitution, iso- electronic impurities, and hydrogen adsorption, while the electronic transport is less affected. As a result, the ZT value can be further enhanced and is very competitive with that of the best commercial materials. To experi- mentally realize this goal, one needs to fabricate CNTs with specific diameter and chirality, and the tube length should be at least 1 μ m. This may be challenging but very possible, considering the fact that the (10,0) tube was successfully produced by many means, such as by direct
Graphene has attracted much attention since it was discovered experimentally in 2004 . Among all its exceptional properties, the long spin diffusion length and spin relaxation time  due to the low intrinsic spin-orbit and hyperfine couplings  are most suitable for spintronics , which aims at generating, controlling, and detecting spin-polarized current. Especially, zigzag graphene nanoribbons (ZGNRs) are expected to host spin-polarized electronic edge states and can serve as the promising graphene-based spintronic device. The ZGNRs are predicted to have a magnetic insulating ground state with ferromagnetic ordering at each edge and antiparallel spin orientation between two edges . The graphene nanoribbons can be fabricated by cutting graphene , patterning epitaxially grown graphene  or unzipping carbon nanotubes [8, 9]. Quite recently, ZGNRs with narrow width and atomically precise zigzag edges are synthesized by a bottom-up fashion and the spin-polarized edge states are directly observed by using scanning tunneling spectroscopy . A variety of spin- tronic devices based on GNRs with edge hydrogenations , nanopore  and different connection methods  have been devised. The graphene nanoscale junc- tions formed by two GNRs leads with different widths [14, 15] or shape  are found to create a spin-
The electronic transport of zigzag-edged graphene nanoribbon (ZGNR) with local Stone-Wales (SW) defects is systematically investigated by first principles calculations. While both symmetric and asymmetric SW defects give rise to complete electron backscattering region, the well-defined parity of the wave functions in symmetric SW defects configuration is preserved. Its signs are changed for the highest-occupied electronic states, leading to the absence of the first conducting plateau. The wave function of asymmetric SW configuration is very similar to that of the pristine GNR, except for the defective regions. Unexpectedly, calculations predict that the asymmetric SW defects are more favorable to electronic transport than the symmetric defects configuration. These distinct transport behaviors are caused by the different couplings between the conducting subbands influenced by wave function alterations around the charge neutrality point.
Abstract. In this paper, we compute the multiplicative first and second Gourava indices, multiplicative first and second hyper Gourava indices, multiplicative sum connectivity Gourava index, multiplicative product connectivity Gourava index, general multiplicative first and second Gourava indices of armchair polyhex nanotubes, zigzag polyhex nanotubes.
2. The same feature has been reported by Moreiras et al. (1981). The structure exhibits both NÐH Cl and CÐH Cl hydrogen bonds. As shown in Fig. 2 (top), each organic cation is bonded to the chloride anions through hydrogen bonds via C13, C22 and N3. Each ion pair is then linked to another pair through the N1ÐH2 Cl hydrogen bond, thus forming a dimer. The dimers are connected to each other, in a zigzag fashion, via N1ÐH1 Cl hydrogen bonds to form sheets [see Fig. 2 (bottom)]. The sheets are stacked along the a axis (see Fig. 3), with chloride ions sandwiched between organic cations. The existence of CÐH Cl hydrogen bonds has recently been reviewed by AakeroÈy et al. (1999), though they have not been invoked by Yatsenko et al. (2000).
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A novel grating monopole (with zigzag) antenna for DVB-T application was proposed and studied. A technique for enhancing both the bandwidth and gain of microstrip patch antenna was designed and a prototype built and presented in this paper. It has a low-cost simple structure which can be easily fabricated; the designed antenna achieves a fractional bandwidth of 85% (420 to 1050 MHz) with minimum 10-dB return loss. The maximum achievable gain of the antenna is 6.28 dBi. The proposed patch has a compact dimension of 64.5 × 170 mm 2 ,
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Fig.7.c. X-Y cut of radiation pattern in 900 MHz for (a) circular path (b) zigzag path (c) straight path It can be seen from above figures that radiation pattern for straight, zigzag and circular paths is almost the same and therefore we can conclude that radiation pattern of leakage current on contaminated insulators is independent from the shape of leakage current path.
The magnetic and coherent transport properties of small-width zigzag graphene nanoribbons (ZGNRs) with monohydrogen edge passivation are investigated as a function of random edge-vacancy disorder and ribbon length. Results from noninteracting tight-binding models with (i) nearest and (ii) up to third nearest neighbor hopping are compared against those obtained from an extended mean-field Hubbard model for edge-defected ZGNRs (length = 48.02 ˚ A and width = 9.24 ˚ A). Through ensemble averaging, a persistent magnetism and Hubbard-U (i.e., spin-generated) conductance gap is found irrespective of the extent of random edge-vacancy disorder. At longer device lengths (up to 144.1 ˚ A) and at high disorder (42.5%), gaps open in the noninteracting model systems, whereas the gap in the Hubbard-calculated systems becomes spin dependent. In all cases, the conductance gaps increase as a function of increasing system length, although the gaps in the Hubbard systems remain smaller due to increased robustness against edge disorder. The continuance of the magnetic state and gap robustness in the ensemble-averaged Hubbard results indicates a complex interplay between the kinetics, disorder, system size, and spin interaction. Such findings may serve to reinform previous studies that have used noninteracting models to investigate disorder in ZGNRs.
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In this study, a physical model, include a canal with two bends (90° and 180°) has been built to investigate the effect of vanes' shapes and arrays on river bank protection. Three types of submerged vanes (flat, angled and curved) in arrays of one, two and three vanes in a row in parallel and zigzag patterns were used. Experimental results on 180°-bend, showed that three curved vanes in a row in zigzag pattern compare to the other states were more effective in
In , Howie and Isbell have extended Isbell’s Zigzag Theorem, by using free products of commutative semigroups, for the category of all commutative semigroups. Stenstrom , by using tensor product of monoids, provided a new proof of the celebrated Isbell’s Zigzag Theorem in the category of all semigroups. In this paper, we provide, based on Stenstrom’s approach, a new algebraic proof of the Howie and Isbell’s result [6, Theorem 1.1] for the category of all commutative semigroups.
synthesized in a methanol–water solution. The asymmetric unit consists of two half-molecules of the complex and two water molecules. Four N and two O atoms form the coordination environment of each Ni atom, resulting in a distorted octahedral configuration. The two halves of each independent dimer are related by a crystallographic inversion centre, which lies at the centre of the ring formed by the two Ni atoms and the coordinating atoms of the two azide anions. The molecules are linked by O—H O hydrogen bonds, generating an interesting double zigzag infinite chain structure in the ac plane.
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regions of the molecule. In the crystal, zigzag supramolecular chains along the a axis are formed by charge-assisted hydroxy-O—H O(phenoxide) hydrogen bonding. These are connected into a layer in the ab plane by charge-assisted hydroxybenzene-C—H O(phenoxide) interactions and – contacts [inter- centroid distance between naphthyl-C 6 rings = 3.4905 (12) A ˚ ]. Layers stack
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