A bound for the Milnor number of plane curve singularities

Let f = 0 be a plane algebraic curve of degree d > 1 with an isolated singular point at 0 ∈ ?². We show that the Milnor number μ₀(f) is less than or equal to (d?1)² ? [d/2], unless f = 0 is a set of d concurrent lines passing through 0, and characterize the curves f = 0 for which μ₀(f) = (d?1)² ? [d/2].     

Charge‐Assisted Halogen Bonding: Donor–Acceptor Complexes with Variable Ionicity

Charge‐assisted halogen bonding is unambiguously revealed from structural and electronic investigations of a series of isostructural charge‐transfer complexes derived from iodinated tetrathiafulvalene and tetracyanoquinodimethane derivatives, (EDT‐TTFI₂)₂(TCNQF_n), n=0–2, which exhibit variable degrees of ionicity. The iodinated tetrathiafulvalene derivative, EDT‐TTFI₂, associates with tetracyanoquinodimethane (TCNQ) and its derivatives of increasing reduction potential (TCNQF, TCNQF₂) through highly directional C? I???N≡C halogen‐bond interactions. With the less oxidizing TCNQ acceptor, a neutral and insulating charge‐transfer complex is isolated whereas with the more oxidizing TCNQF₂ acceptor, an ionic, highly conducting charge‐transfer salt is found, both of 2:1 stoichiometry and isostructural with the intermediate TCNQF complex, in which a neutral–ionic conversion takes place upon cooling. A correlation between the degree of charge transfer and the C? I???N≡C halogen‐bond strength is established from the comparison of the structures of the three isostructural complexes at temperatures from 300 to 20 K, thus demonstrating the importance of electrostatics in the halogen‐bonding interaction. The neutral–ionic conversion in (EDT‐TTFI₂)₂(TCNQF) is further investigated through the temperature dependence of its magnetic susceptibility and the stretching modes of the C≡N groups.     

Determination of Fe(II) and Zn(II) in Vitrum Prenatal by Ion Chromatography (IC). Comparison with Classical and Derivative Spectrophotometry (D0, D1, and D2) with Metrian,Metriap, Metriarez-γ, and Metidarez-β Dyes and with Atomic Absorption Spectrometry

JPC – Journal of Planar Chromatography – Modern TLC - 3-Mercapto-5-(2′-hydroxynaphthylazo-1′)-1,2,4-triazole (metrian);...     

Analysis of chaotic non-isothermal solutions of thermomechanical shape memory oscillators

Shape memory materials exhibit strong thermomechanical coupling, so that temperature variations occur during mechanical loading and unloading. In previous works the nonlinear dynamics of pseudoelastic oscillators subject to an harmonic force has been studied and the possibility of non-regular chaotic responses has been thoroughly documented. Instead of the standard Lyapunov exponent treatment, the statistical 0–1 test based on the asymptotic properties of a Brownian motion chain was successively applied to reveal the chaotic nature of trajectories in the special case in which temperature variations were neglected. In this work, the 0–1 test is applied to fully non-isothermal trajectories. To improve its reliability the test has been applied to the time-histories of maxima and minima of each trajectory, in each component. The obtained results have been validated and confirmed by the corresponding Fourier spectra. Non-regular solutions with different levels of chaoticity have been analyzed and their qualitative difference is reflected by the different values to which the control parameter K asymptotically converge.     

Towards a new family of photoluminescent organozinc 8-hydroxyquinolinates with a high propensity to form noncovalent porous materials

We report on investigations of reactions of tBu(2)Zn with 8-hydroxyquinoline (q-H) and the influence of water on the composition and structure of the final product. A new synthetic approach to photoluminescent zinc complexes with quinolinate ligands was developed that allowed the isolation of a series of structurally diverse and novel alkylzinc 8-hydroxyquinolate complexes: the trinuclear alkylzinc aggregate [tBuZn(q)](3) (1(3)), the pentanuclear oxo cluster [(tBu)(3)Zn(5)(μ(4) -O)(q)(5)] (2), and the tetranuclear hydroxo cluster [Zn(q)(2)](2)[tBuZn(OH)](2) (3). All compounds were characterized in solution by (1)H NMR, IR, UV/Vis, and photoluminescence (PL) spectroscopy, and in the solid state by X-ray diffraction, TGA, and PL studies. Density functional theory calculations were also carried out for these new Zn(II) complexes to rationalize their luminescence behavior. A detailed analysis of the supramolecular structures of 2 and 3 shows that the unique shape of the corresponding single molecules leads to the formation of extended 3D networks with 1D open channels. Varying the stoichiometry, shape, and supramolecular structure of the resulting complexes leads to changes in their spectroscopic properties. The close-packed crystal structure of 1(3) shows a redshifted emission maximum in comparison to the porous crystal structure of 2 and the THF-solvated structure of 3.     

Some Comments on Projective Quadrics Subordinate to Pseudo-Hermitian Spaces

We study in some detail the structure of the projective quadric Q′ obtained by taking the quotient of the isotropic cone in a standard pseudo-hermitian space H _p,q with respect to the positive real numbers \mathbb R⁺{\mathbb R^{+}} and, further, by taking the quotient [(Q)\tilde] = Q￠/U(1){\tilde Q = Q^\prime /U(1)}. The case of signature (1, 1) serves as an illustration. Q̃ is studied as a compactification of \mathbb R ×H_p-1,q-1{\mathbb R \times H_{p-1,q-1}}     

The influence of fly ash physical and chemical properties on electrostatic precipitation process

Flue gases emitted from coal fired power plants are mainly cleaned with electrostatic precipitators (ESP). Increased awareness of the effects of atmospheric pollution and tightening legislation force precipitator producers to increase their ESP efficiency, especially when collecting very fine particulates (PM2.5). The fly ash characteristic parameters are formatted during combustion process and its depend on the coal type as well as boiler parameters and combustion conditions. Due to that many series of tests were done to investigate the influence of fly ash physical and chemical properties on ESP operation.     

Study of low concentrated ionic ferrrofluid stability in magnetic field by ultrasound spectroscopy

Ultrasound spectroscopy has been used to investigate the effect of magnetic field on particle (cluster) size distribution in ionic ferrofluid. The method applied is non-destructive, fast and sensitive to structural changes of a suspension as it is based on measurements of ultrasonic attenuation. Changes in the ultrasound attenuation induced by an external magnetic field have been measured for different frequencies of the acoustic wave. According to the Harker-Temple theory, the aggregation process has been analysed on the basis of the cluster size distribution determined for different magnetic field intensities.     

Global phase diagram of the fractional quantum Hall effect arising from repulsive three-body interactions

The model of fermions in a magnetic field interacting via a purely three-body repulsive interaction has attracted interest because it produces, in the limit of short range interaction, the Pfaffian state with non-Abelian excitations. We show that this is part of a rich phase diagram containing a host of fractional quantum Hall states, a composite fermion Fermi sea, and a pairing transition. This is entirely unexpected, because the appearance of composite fermions and fractional quantum Hall effect is ordinarily thought to be a result of strong two-body repulsion. Recent breakthroughs in ultracold atoms have facilitated the realization of such a system, where this physics can be tested.     

Dose-rate effect in the model of semi-localized transitions (SLT)

The model of semi-localized transitions (SLT) unifies two standard models of thermoluminescence (TL) and optically stimulated luminescence (OSL) kinetics – the simple trap model (STM) and the model of localized transitions (LT). SLT equations were previously formulated for the heating stage of TL. This paper presents SLT equations for the excitation and fast relaxation stages. Exemplary calculations were performed to show the occurrence of dose-rate effect – previously found in STM. It is shown that the dose-rate effect occurs for both – localized and delocalized TL glow peaks.