New taxa and combinations in Neotropical Issidae (Hemiptera: Fulgoroidea)

Six new genera are erected as follows: in the Issini, Argepara gen. n. (type species: Hysteropterum semipellucidum Melichar, 1906), Aztecus gen. n. (type species: Hysteropterum montezuma Kirkaldy, 1913), Incasa gen. n. (type species: Hysteropterum riobambae Schmidt, 1910), Bumaya gen. n. (type species: Bumaya knorozovi sp. n.); and in the Colpopterini, Caudibeccus, gen. n. (type species: Colpoptera carlota Myers, 1928) and Jamaha gen. n. (type species: Poeciloptera elevans Walker, 1858). Four new generic synomymies are proposed: Prothona Caldwell, 1945 and Plummerana Caldwell, 1945 are placed in synonymy under Proteinissus Fowler, 1904. Thionissa Metcalf, 1938 is placed in synonymy under Dracela Signoret, 1861. Hesperophara Kirkaldy, 1904 is placed in synonymy under Colpoptera Burmeister, 1835. Twenty-three new combinations resulting from generic synonymies or transfer of species into new genera are: Argepara lyra (Berg, 1883), Argepara semipellucida (Melichar, 1906), Aztecus auroriferus (Caldwell, 1945), Aztecus erratus (Caldwell, 1945), Aztecus mexicanus (Kirkaldy, 1909), Aztecus montezuma (Kirkaldy, 1913), Aztecus sierrae (Fowler, 1904), Aztecus viridatus (Caldwell, 1945), Caudibeccus carlota (Myers, 1928), Caudibeccus lucaris (Fennah, 1955), Caudibeccus meleagris (Fennah, 1955), Caudibeccus punctatus (Metcalf, 1954), Colpoptera rustica (Fabricius, 1803), Dracela acuta (Metcalf, 1938), Incasa riobambae (Schmidt, 1910), Jamaha chrysops (Fennah, 1955), Jamaha elevans (Walker 1858), Paralixes fowleri (Melichar, 1906), Proteinissus isolatus (Caldwell, 1945), Proteinissus pentagonatus (Caldwell, 1945), Proteinissus punctatus (Caldwell, 1945), Proteinissus reticulatus (Caldwell, 1945), Proteinissus viridus (Caldwell, 1945). Three new species are described: Bumaya knorozovi sp. n. from Belize and Mexico, Traxus kasparyani sp. n. from Mexico, and Caudibeccus emeljanovi sp. n. from Cuba. The description of T. kasparyani represents the first Mexican country record for the genus Traxus Metcalf. The species Hysteropterum acanthum Caldwell, 1945 is placed in synonymy under Aztecus montezuma (Kirkaldy, 1913). Colpoptera sinuata Burmeister, 1835 is redescribed. New country records are presented for A. semipellucida from Argentina, A. lyra from Paraguay and Uruguay, D. acuta from Ecuador, and D. annulipes Signoret, 1861 from Brazil, Peru, and Ecuador. Keys to the species of the genera Aztecus gen. n., Argepara gen. n., Traxus Metcalf, and Dracela Signoret are given. An ant association is recorded for the first time for A. lyra

Dynamical Dzyaloshinsky-Moriya interaction in KCuF3: Raman evidence for an antiferrodistortive lattice instability

In the orbitally ordered, quasi-one dimensional Heisenberg antiferromagnet KCuF3 the low-energy Eg and B1g phonon modes show an anomalous softening (25% and 13%) between room temperature and the characteristic temperature T_S = 50 K. In this temperature range a freezing-in of F ion dynamic displacements is proposed to occur. In addition, the Eg mode at about 260 cm-1 clearly splits below T_S. The width of the phonon lines above T_S follows an activated behavior with an activation energy of about 50 K. Our observations clearly evidence a reduction of the structural symmetry below T_S and indicate a strong coupling of lattice and spin fluctuations for T>T_S.Comment: 7 pages, 9 figure

Static magnetic field alters properties of confined alkylammonium nitrate ionic liquids

© 2018 Elsevier B.V. Ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) ionic liquids confined between polar glass plates and exposed to a strong magnetic field of 9.4 T demonstrate gradually slowing diffusivity, a process that can be reversed by removing the sample from the magnetic field. The process can be described well by the Avrami equation, which is typical for autocatalytic (particularly, nucleation controlled) processes. The transition can be stopped by freezing the sample. Cooling and heating investigations showed differences in the freezing and melting behavior of the sample depending on whether it had been exposed to the magnetic field. After exposure to the magnetic field, the sample demonstrated decrease in the 1H NMR signal of residual water. 1H NMR spectroscopy with presaturation demonstrates that the most probable mechanism of the decrease of the bulk water signal is adsorption of water on polar surfaces of glass plates. Generally, our findings confirm our previous suggestion that alteration of the dynamic properties of confined alkylammonium nitrate ionic liquids exposed to a magnetic field is related to the alteration of real physical-chemical phases

Dynamical lattice instability versus spin liquid state in a frustrated spin chain system

The low-dimensional s=1/2 compound (NO)[Cu(NO3)3] has recently been suggested to follow the Nersesyan-Tsvelik model of coupled spin chains. Such a system shows unbound spinon excitations and a resonating valence bond ground state due spin frustration. Our Raman scattering study demonstrates phonon anomalies as well as the suppression of a broad magnetic scattering continuum for temperatures below a characteristic temperature, T<T*=100K. We interpret these effects as evidence for a dynamical interplay of spin and lattice degrees of freedom that might lead to a further transition into a dimerized or structurally distorted phase at lower temperatures.Comment: 5 pages, 6 figure

Ion dynamics in halogen-free phosphonium bis(salicylato)borate ionic liquid electrolytes for lithium-ion batteries

© the Owner Societies 2017. This study was focused on the investigation of ion dynamics in halogen-free, hydrophobic, and hydrolytically stable phosphonium bis(salicylato)borate [P 4,4,4,8 ][BScB] ionic liquid electrolytes for lithium-ion batteries. The structure and purity of the synthesized ionic liquid and lithium bis(salicylato)borate Li[BScB] salt were characterized using 1 H, 13 C, 31 P, and 11 B NMR spectroscopy. The Li[BScB] salt was mixed with an ionic liquid at the concentrations ranging from 2.5 mol% to 20 mol%. The physicochemical properties of the resulting electrolytes were characteriz ed using thermal analysis (TGA and DSC), electrical impedance spectroscopy, and pulsed-field gradient (PFG) NMR and ATR-FTIR spectroscopy. The apparent transfer numbers of the individual ions were calculated from the diffusion coefficients of the cation and anion as determined via the PFG NMR spectroscopy. NMR and ATR-FTIR spectroscopic techniques revealed dynamic interactions between the lithium cation and bis(salicylato)borate anion in the electrolytes. The ion-ion interactions were found to increase with the increasing concentration of the Li[BScB] salt, which resulted in ionic clustering at the concentrations higher than 15 mol% of Li salt in the ionic liquid

Anomalous optical phonons in FeTe pnictides: spin state, magnetic order, and lattice anharmonicity

Polarized Raman-scattering spectra of non-superconducting, single-crystalline FeTe are investigated as function of temperature. We have found a relation between the magnitude of ordered magnetic moments and the linewidth of A1g phonons at low temperatures. This relation is attributed to the intermediate spin state (S=1) and the orbital degeneracy of the Fe ions. Spin-phonon coupling constants have been estimated based on microscopic modeling using density-functional theory and analysis of the local spin density. Our observations show the importance of orbital degrees of freedom for the Fe-based superconductors with large ordered magnetic moments, while small magnetic moment of Fe ions in some iron pnictides reflects the low spin state of Fe ions in those systems.Comment: 17 pages, 3 figure

First mesogenic derivative of boron difluoride β-enaminoketonate

Boron difluoride complexes possessing liquid crystalline and luminescent properties were synthesized for the first time on the basis of non-mesogenic β-enaminoketones. © 2010 Pleiades Publishing, Ltd

Transport and Association of Ions in Lithium Battery Electrolytes Based on Glycol Ether Mixed with Halogen-Free Orthoborate Ionic Liquid

© 2017 The Author(s). Ion transport behaviour of halogen-free hybrid electrolytes for lithium-ion batteries based on phosphonium bis(salicylato)borate [P 4,4,4,8 ][BScB] ionic liquid mixed with diethylene glycol dibutyl ether (DEGDBE) is investigated. The Li[BScB] salt is dissolved at different concentrations in the range from 0.15 mol kg -1 to 1.0 mol kg -1 in a mixture of [P 4,4,4,8 ][BScB] and DEGDBE in 1:5 molar ratio. The ion transport properties of the resulting electrolytes are investigated using viscosity, electrical impedance spectroscopy and pulsed-Field Gradient (PFG) NMR. The apparent transfer numbers of ions are calculated from the diffusion coefficients measured by using PFG NMR. PFG NMR data suggested ion association upon addition of Li salt to the [P 4,4,4,8 ][BScB] in DEGDBE solution. This is further confirmed by liquid state 7 Li and 11 B NMR, and FTIR spectroscopic techniques, which suggest strong interactions between the lithium cation and oxygen atoms of the [BScB] - anion in the hybrid electrolytes

Interaction of polyacrylic acid with lipid bilayers: Effect of polymer mass

Polyanion-coated lipid vesicles are proposed to have an appreciable potential for drug delivery because of their ability to control the permeability of lipid bilayers by environmental parameters such as pH and temperature. However, details of the interaction of this class of polymers with lipids and their mechanisms of induced permeability are still being debated. In this work, we applied 1H NOESY to study details of the interaction of polyacrylic acid (PAA) fractions of molecular weights 5 and 240 kDa with dimyristoylphosphatidylcholine vesicles. We showed that PAA of two different molecular masses modifies lipid bilayers increasing disorder and probability of close contact between polar and hydrophobic groups. PAA molecules adsorb near the interface of lipid bilayers but do not penetrate into the hydrophobic core of the bilayer and, thus, cannot participate in formation of transbilayer channels, proposed in earlier works. Increasing the molecular mass of PAA from 5 kDa to 240 kDa does not change the effect of PAA on the bilayer, although PAA240 forms a more compact structure (either intra-molecular or inter-molecular) and interacts more strongly with interface lipid protons. Copyright © 2013 John Wiley & Sons, Ltd. Polyacrylic acid (PAA) molecules adsorb near the interface of lipid bilayers but do not penetrate into the hydrophobic core of the bilayer. Increasing the molecular mass of PAA from 5 to 240 kDa does not change the effect of PAA on the bilayer, although PAA240 forms a more compact structure (either intra-molecular or inter-molecular) and interacts more strongly with interface lipid protons. Copyright © 2013 John Wiley & Sons, Ltd