Composition operators on Lizorkin-Triebel spaces

This paper is devoted to the study of the composition operator Tf(g):=f○g on Lizorkin-Triebel spaces . In case s>1+(1/p), 1<p<∞, and 1?q?∞ we will prove the following: the operator Tf takes to itself if and only if f(0)=0 and f belongs locally to .     

Random crystal-field effects in a mixed spin-1/2 and spin-2 ferrimagnetic Ising system

The magnetic properties of a mixed spin ferrimagnetic system σ?=?1/2 and S?=?2 at the sites of a square lattice with a random crystal field are studied by the mean field approximation. The ground state of the system is determined and the total magnetization is plotted according to the model parameters. Different behaviors for the thermal dependence of the magnetization are highlighted. In particular, one sees the appearance of one or two compensating points and many types of phase diagrams with first and second order phase transition lines as well as isolated critical and tricritical points.     

Immersion Calorimetry: Molecular Packing Effects in Micropores

Repeated and controlled immersion calorimetry experiments were performed to determine the specific surface area and pore‐size distribution (PSD) of a well‐characterized, microporous poly(furfuryl alcohol)‐based activated carbon. The PSD derived from nitrogen gas adsorption indicated a narrow distribution centered at 0.57±0.05 nm. Immersion into liquids of increasing molecular sizes ranging from 0.33 nm (dichloromethane) to 0.70 nm (α‐pinene) showed a decreasing enthalpy of immersion at a critical probe size (0.43–0.48 nm), followed by an increase at 0.48–0.56 nm, and a second decrease at 0.56–0.60 nm. This maximum has not been reported previously. After consideration of possible reasons for this new observation, it is concluded that the effect arises from molecular packing inside the micropores, interpreted in terms of 2D packing. The immersion enthalpy PSD was consistent with that from quenched solid density functional theory (QSDFT) analysis of the nitrogen adsorption isotherm.     

Synthesis,polymerization, and curing of N‐substituted citraconimidyl acrylate

Several N‐(substituted phenyl) citraconimides containing phenolic hydroxyl groups (I) were prepared. I were esterified with acryloyl chloride producing the corresponding acrylate esters (II). II were free radically polymerized yielding linear polyacrylates (III). The citraconimidyl vinyls did not participate in the polymerization. The resulting polymers (III) were cured thermally or through the crosslinking agent N,N‐(p‐phenylene)dimaleimide. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 427–433, 1999     

Admissibility results under some balanced loss functions for a functional regression model

We consider the problem of the nonparametric estimation in a functional regression model $Y=r(X)+\epsilon$, with Y a real random variable response and X representing a functional variable taking values in a semi-metric space. The aim of this note is to find conditions of admissibility of Stein-type estimators of such a model under a class of balanced loss functions. Our method is to compare the risk with that obtained in the case of a quadratic loss.     

Study on phase stability and oxide ion conductivity in the BIAGVOX system

A novel oxide ion conductor, BIAGVOX formulated as Bi₄Ag_xV_2?xO_11?(2x)?δ is obtained by substituting a fraction (x) of V⁵⁺ by Ag⁺ in Bi₄V₂O₁₁ samples of the BIAGVOX system in the composition range, 0.05≤x≤0.30 were synthesized using the standard solid-state reaction. XRPD, FT-IR, DTA and AC impedance spectroscopy were used for the investigation of the correlation between the structural phase stability and oxide ion performance of the BIAGVOX materials. It has been found that orthorhombic, β, and incommensurate tetragonal, γ′ were stabilized at room temperature for compositions with x≤0.15 and x≥0.20, respectively. The enthalpy of β→γ and γ→γ transition exhibited a general drop with increasing Ag content and a minimum transition temperature was observed for x=0.20. However, the oxide ion conductivity at lower temperatures remarkably increased in composition stability ranges of β- and γ-phase, while a maximum conductivity was reported for the high temperature γ-phase at x=0.15. However, the low temperature conductivity, σ₃₀₀°c measured for x=0.30 was found to be comparable with the maximum ionic conductivity of the BICUVOX system reported for x=0.20 at the same temperature.     

Equivariant Yamabe problem and Hebey-Vaugon conjecture

In their study of the Yamabe problem in the presence of isometry groups, E. Hebey and M. Vaugon announced a conjecture. This conjecture generalizes T. Aubin's conjecture, which has already been proven and is sufficient to solve the Yamabe problem. In this paper, we generalize Aubin's theorem and we prove the Hebey-Vaugon conjecture in dimensions less or equal to 37.     

Impact of γ-rays on constructional,optical and thermal behavior of alkaline and non alkaline low density polyethylene

ABSTRACT

In this study, we investigated the graft copolymerization of methyl methacrylate (MMA) onto low-density polyethylene (LDPE) in the presence of aniline as an inhibitor by gamma radiation. An alkaline treatment was carried out for the prepared graft copolymer. The structural properties of the prepared samples were examined via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD peaks were slightly shifted, indicating an interaction between MMA and the polyethylene matrix. The morphology of the samples confirmed the homogenous grafted phase scattered onto the LDPE surface. Analysis of the absorption spectra indicated an allowed indirect transition mechanism. The Urbach energy (E_U) results showed that the value of the E_U for grafted LDPE was found to be higher than that of pure LDPE—up to 15?kGy irradiation dose, although this value decreases upon grafting. However, the value of the E_U for alkaline-treated grafted films decreases systematically by increasing the degree of grafting. The thermogravimetric analysis (TGA) of the sample indicated that the thermal stability of LDPE samples is significantly changed by grafting MMA onto it. Horowitz and Metzger's models were utilized to measure the activation energy of the thermal decomposition of all samples.