Structural Peculiarities and Thermoelectric Study of Iron Indium Thiospinel

The homogeneity range of ternary iron indium thiospinel at 873 K was investigated. A detailed study was focused on two distinct series (y=z): 1) a previously reported charge-balanced (In_0.67+0.33y□_0.33−0.33y)_tetr[In_2−zFe_z]_octS₄ (A1-series; □ stands for vacancy; the abbreviations “tetr” and “oct” indicate atoms occupying tetrahedral 8a and octahedral 16d sites, respectively) and 2) a new charge-unbalanced (In_0.67+y□_0.33−y)_tetr[In_2−zFe_z]_octS₄ (A2-series). Fe atoms were confirmed to exclusively occupy an octahedral position in both series. An unusual reduction of the unit cell parameter with increasing Fe content is explained by differences in the ionic radii between Fe and In, as well as by an additional electrostatic attraction originating from charge imbalance (latter only in A2-series). The studied compound is an n-type semiconductor, and its charge carrier concentration increases or decreases for larger Fe content within the A1- and A2-series, respectively. The thermal conductivity κ_tot is significantly reduced upon increasing vacancy concentration, whereas the change of power factor is insufficient to drastically improve the thermoelectric figure of merit.     

Comparison of two cold atmospheric pressure plasma jet configurations in argon

The present study compares the operation of two cold atmospheric plasma jet (CAPJ) configurations: needle-to-cylinder electrode configuration (CAPJ I) and single high-voltage cylinder electrode around the quartz tube (CAPJ II). The CAPJs were operated in argon flowing through a quartz capillary with 0.5-mm inner diameter into the ambient air, and the plasma was generated by sinusoidal kHz frequency AC power supplies. The main emphasis of the study was on the mechanism of the initiation of ionization waves for these two configurations. For both CAPJs, there appeared several ionization waves during one half-period of the applied voltage waveform, and the number of ionization waves increased at higher voltage amplitudes. However, we discovered marked differences in the initiation of the ionization waves for two different CAPJ configuration. The applied voltage controlled the initiation of consecutive ionization waves, which propagated from the grounded electrode towards the tube orifice in CAPJ I. In the case of CAPJ II, certain time had to pass for the initiation of a new ionization wave, and subsequent ionization waves within the same half-period started at the tube orifice. In addition to the differences in the initiation of the ionization waves, we observed that the CAPJ I was ignited and sustained at lower voltages, while CAPJ II produced a longer plasma jet. The observed advantages and deficiencies of investigated CAPJ configurations point out their potential in different applications.     

Klein-Gordon-Wheeler-DeWitt-Schrödinger equation

We start from the Einstein-Hilbert action for the gravitational field in the presence of a “point particle” source, and cast the action into the corresponding phase space form. The dynamical variables of such a system satisfy the point particle mass shell constraint, the Hamilton and the momentum constraints of the canonical gravity. In the quantized theory, those constraints become operators that annihilate a state. A state can be represented by a wave functional Ψ that simultaneously satisfies the Klein-Gordon and the Wheeler-DeWitt-Schrödinger equation. The latter equation, besides the term due to gravity, also contains the Schrödinger like term, namely the derivative of Ψ with respect to time, that occurs because of the presence of the point particle. The particle?s time coordinate, X⁰, serves the role of time. Next, we generalize the system to p-branes, and find out that for a quantized spacetime filling brane there occurs an effective cosmological constant, proportional to the expectation value of the brane?s momentum, a degree of freedom that has two discrete values only, a positive and a negative one. This mechanism could be an explanation for the small cosmological constant that drives the accelerated expansion of the universe.     

On locally linearly dependent operators and derivations

The first section of the paper deals with linear operators , , where and are vector spaces over an infinite field, such that for every , the vectors are linearly dependent modulo a fixed finite dimensional subspace of . In the second section, outer derivations of dense algebras of linear operators are discussed. The results of the first two sections of the paper are applied in the last section, where commuting pairs of continuous derivations of a Banach algebra such that is quasi-nilpotent for every are characterized.

     

External inversion,internal inversion,and reflection invariance

Having in mind that physical systems have different levels of structure we develop the concept of external, internal and total improper Lorentz transformation (space inversion and time reversal). A particle obtained from the ordinary one by the application of internal space inversion or time reversal is generally a different particle. From this point of view the intrinsic parity of a nuclear particle (elementary particle) is in fact the external intrinsic parity, if we take into account the internal structure of a particle. We show that non-conservation of the external parity does not necessarily imply noninvariance of nature under space inversion. The conventional theory of beta-decay can be corrected by including the internal degrees of freedom to become invariant under total space inversion, though not under the external one.     

Clifford Space as a Generalization of Spacetime: Prospects for QFT of Point Particles and Strings

The idea that spacetime has to be replaced by Clifford space (C-space) is explored. Quantum field theory (QFT) and string theory are generalized to C-space. It is shown how one can solve the cosmological constant problem and formulate string theory without central terms in the Virasoro algebra by exploiting the peculiar pseudo-Euclidean signature of C-space and the Jackiw definition of the vacuum state. As an introduction into the subject, a toy model of the harmonic oscillator in pseudo-Euclidean space is studied.     

Comment on the analysis of angle-dependent X-ray magnetic circular dichroism in systems with reduced dimensionality

The magnetic dipole term T appearing in the X-ray magnetic circular dichroism (XMCD) spin sum rule can be eliminated from the analysis within the spin sum rule by angle-dependent XMCD spectroscopy if the effects of spin–orbit coupling are small so that T_x+T_y+T_z≈0. It is shown by the ab initio electron theory for the extreme case of a low-dimensional system, i.e., for a free-standing monatomic Co wire that this relation is strongly violated, indicating that the determination of T by the angle-dependent XMCD is possibly not very reliable for low-dimensional magnetic systems.     

Polysulfobetaine films prepared by electrografting technique for reduction of biofouling on electroconductive surfaces

The sulfobetaine films were prepared on stainless steel and golden surfaces. In the first step, the poly(2-(dimethylamino)ethyl methacrylate) film was created by employing the electrografting polymerization technique. In the second step, this film was modified to polysulfobetaine, i.e. the polymer film bearing the zwitterionic groups. The presence of the electrografted film and its modification were determined by contact angle measurements, infrared spectroscopy in reflectance mode and X-ray photoelectron spectroscopy. The prepared films were homogeneous with the thickness from about 5 to 26 nm as determined by X-ray photoelectron spectroscopy. The atomic force microscopy measurements showed the increase of surface roughness upon the surface coating. In vitro tests using adherent RAT-2 fibroblast cells and fluorescently labelled bovine serum albumin proteins showed that prepared polysulfobetaine films can be used in applications requiring the resistance against cell attachment and biofouling.