Search results for "Solid-State"

Reactivity of Distibanes toward Trialkylalanes and -gallanes:  Syntheses and X-ray Structures of Bisadducts and Heterocycles

2001

Reactions between distibanes of the type Sb2R4 and trialkylalanes and -gallanes R‘3M in 1:2 stoichiometry yield eight bisadducts of the type [Sb2R4][MR‘3]2 (R = Me, R‘ = t-Bu, M = Al 1, Ga 2; R = Et, M = Al, R‘ = Me 3, Et 4, t-Bu 5; M = Ga, R‘ = Me 6, Et 7, t-Bu 8), which were characterized by multinuclear NMR studies and elemental analysis. In addition, 1, 2, 5, and 8 are the first structurally characterized neutral main group Lewis acid−distibane bisadducts. 1−8 are unstable in solution toward the formation of heterocycles of the type [R2SbMR‘2]x. [Me2SbGa(t-Bu)2]3 (9) and [Et2SbGa(t-Bu)2]2 (10) have been isolated and their solid state structures determined by single-crystal X-ray diffrac…

Solution and solid-state studies on the halide binding affinity of perfluorophenyl-armed uranyl–salophen receptors enhanced by anion–π Interactions

2016

The enhancement of the binding between halide anions and a Lewis acidic uranyl-salophen receptor has been achieved by the introduction of pendant electron- deficient arene units into the receptor skeleton. The association and the occurrence of the elusive anion-p interaction with halide anions (as tetrabutylammonium salts) have been demonstrated in solution and in the solid state, providing unambiguous evidence on the interplay of the concerted interactions responsible for the anion binding.

Polarization Switching in Heterophase Nanostructures: PLZT Relaxor Ceramics

2005

The polarization switching is experimentally investigated in hot-pressed PLZT-x/65/35 ceramics with a lanthanum content from 5 to 12 at. %. The specific features in the temperature dependence of the polarization switching in a heterophase state are interpreted by analyzing the change in the switched charge measured over wide ranges of fields and temperatures. Particular emphasis is placed on the role of depolarization fields induced by interphase boundaries. A model of the evolution of polydomain nanostructures with a change in the temperature and in the response to an external field is considered. It is assumed that the low-temperature dielectric anomaly and the temperature hysteresis are …

Scaling theory of star polymers and general polymer networks in bulk and semi-infinite good solvents

1988

Theorie d'echelle utilisant l'equivalence entre la fonction generatrice du nombre total de configuration et la fonction de correlation a plusieurs spins du modele de Heisenberg classique a n composantes dans la limite n→0

Homodyne Solid-State Biased Coherent Detection of Ultra-Broadband Terahertz Pulses with Static Electric Fields.

2021

We present an innovative implementation of the solid-state-biased coherent detection (SSBCD) technique, which we have recently introduced for the reconstruction of both amplitude and phase of ultra-broadband terahertz pulses. In our previous works, the SSBCD method has been operated via a heterodyne scheme, which involves demanding square-wave voltage amplifiers, phase-locked to the THz pulse train, as well as an electronic circuit for the demodulation of the readout signal. Here, we demonstrate that the SSBCD technique can be operated via a very simple homodyne scheme, exploiting plain static bias voltages. We show that the homodyne SSBCD signal turns into a bipolar transient when the stat…

Synthesis, reactions and structural features of monofluorinated cyclopropanecarboxylates

2002

Abstract Monofluorinated cyclopropanecarboxylates are available in racemic or optically active form by transition metal-catalyzed reactions of vinylfluorides with diazoacetates. From α-fluorostyrene and tert-butyl diazoacetate in the presence of 2 mol% of an enantiopure bis(oxazoline) copper complex, a 81:19 mixture of tert-butyl trans- and cis-2-fluoro-2-phenylcyclopropanecarboxylates was obtained with high enantiomeric excess (ee) of 93 or 89%, respectively. The corresponding racemic ethylesters were used as starting materials for the synthesis of carboxamides, of the cis- and trans-isomers of analogues of tranylcypromine, an anti-depressive drug and several of its homologous fluorinated …

First Steps of µTAS in Latvia

1995

Owing to participation of Latvian and Swedish scientists in the field of chemically sensitive FET and MOS structures it was possible to utilize the technological facilities of the Microelectronics enterprise in Latvia in making an integrated smart sensor as a matrix of chemically sensitive FETs by using silicon based microtechnology. Thereby the first steps of µTAS in Latvia are made in the direction of integration of solid state ionic materials with FET and MOS structures to develop new chemically sensitive structures and systems.

1990

This lecture summarizes some recent results and ideas about interrelations between degradation and mechanical behaviour of polyolefins. Aspects of the heterogeneous nature of oxidative degradation in the solid state, the feedback mechanism in degradation, effects of morphology, particularly orientation, on the degradation process, and the influence of degradation on plasticity and on the ultimate mechanical behaviour are discussed.

NMR crystallography of 2-Acylamino-6-[1H]pyridones: solid state NMR, GIPAW computational, and single crystal X-ray diffraction studies

2011

Abstract 2-Acylamino-6-[1H]-pyridones [acyl = RCO, where R = methyl (1), ethyl (2), iso-propyl (3), tert-butyl (4), and 1-adamantyl (5)] have been synthesized and characterized by NMR spectroscopy. From three congeners, 2, 3 and 5, also single crystal X-ray structures have been solved. For these derivatives GIPAW calculations acts as a “bridge” between solid-state NMR data and calculated chemical shifts based on X-ray determined geometry. In crystals all three compounds exist as pyridone tautomers possessing similar six-membered ring structure stabilized by intramolecular C O⋯HN hydrogen bond. Theoretical GIPAW calculated and experimental 13C and 15N CPMAS NMR shifts are in excellent agreem…

Solid-state electrochemical characterization of emissions and authorities producing Roman brass coins

2020

[EN] The voltammetry of immobilized particles (VIMP) is applied to describe the solid state electrochemistry of brass. This methodology, which involves sampling at the nanogram level, is applied to discriminate mints/authorities producing different Roman monetary emissions covering since the Republic (88 BCE) to Domitianus (55-96 CE) Upon attachment to graphite electrodes in contact with aqueous acetate buffer at pH 4.75, well defined voltarnmetric responses were obtained centered on Cu- and Zn-localized signals whose intensity can be correlated to EMP data, being sensitive to the contents of Zn (15-30 wt.%) and Sn (0.01-1.1 wt.%). Voltammetric data, combined with ATR-FTIR and FIB-PESEM/EDS…