The influence of polyvinylpyrrolidone on thick and optical properties of BaTiO<Subscript>3</Subscript>:Er<Superscript>3+</Superscript> thin films prepared by sol–gel method

Erbium (Er³⁺) 0.5% mol doped barium titanate (BaTiO₃) thin films were elaborated via sol–gel method and dip-coating technique using titanium alkoxide and barium pentanedionate. Two syntheses were performed [with and without polyvinylpyrrolidone (PVP)] in order to obtain thick films. The BaTiO₃:Er³⁺ thin films prepared from the sol with PVP were elaborated with 1 layer and those without PVP and were elaborated with 17 layers. In both cases, the films were deposited on silica quartz substrates. Both BaTiO₃:Er³⁺ films presented a cubic phase, as determined by X-ray diffraction. BaTiO₃:Er³⁺ films elaborated with PVP via single-step dip coating produced crack-free films with thicknesses of ~800 nm. SEM micrographs for the obtained BaTiO₃:Er³⁺ films revealed high homogeneity and density. Mapping images obtained from BaTiO₃:Er³⁺ revealed homogeneous distribution of Er³⁺ ions on the surface. XPS analyses of the chemical state and chemical environment of the constituent elements in the compositions showed that Er³⁺ ions in (Ba_1−x Er _x )TiO₃ are in mixed valence of Er³⁺/Er²⁺. The BaTiO₃:Er³⁺-PVP film exhibited luminescent properties under near-infrared excitation, as revealed by green emissions. The BaTiO₃:Er³⁺-PVP film has good potential for optical applications.     

Hydrogen‐bonding patterns in three substituted N‐benzyl‐N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)acetamides

The molecules of N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)‐2‐chloro‐N‐(4‐methoxybenzyl)acetamide, C₂₃H₂₆ClN₃O₂, are linked into a chain of edge‐fused centrosymmetric rings by a combination of one C—H...O hydrogen bond and one C—H...π(arene) hydrogen bond. In N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)‐2‐chloro‐N‐(4‐chlorobenzyl)acetamide, C₂₂H₂₃Cl₂N₃O, a combination of one C—H...O hydrogen bond and two C—H...π(arene) hydrogen bonds, which utilize different aryl rings as the acceptors, link the molecules into sheets. The molecules of S‐[N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)‐N‐(4‐methylbenzyl)carbamoyl]methyl O‐ethyl carbonodithioate, C₂₆H₃₁N₃O₂S₂, are also linked into sheets, now by a combination of two C—H...O hydrogen bonds, both of which utilize the amide O atom as the acceptor, and two C—H...π(arene) hydrogen bonds, which utilize different aryl groups as the acceptors.     

Inversion of Nonsmooth Maps between Banach Spaces

Set-Valued and Variational Analysis - We study the invertibility nonsmooth maps between infinite-dimensional Banach spaces. To this end, we introduce an analogue of the notion of pseudo-Jacobian...     

Spin-Echo planar spectroscopic imaging for fast lipid characterization in bone marrow.

Lipid characterization of bone marrow in vivo with proton magnetic resonance spectroscopy was performed using Spin-Echo Planar Spectroscopic Imaging sequences. The methods are shown capable of rapidly generating two-dimensional chemical shift imaging data sets suitable for measuring lipid indices that reflect unsaturation levels among triglycerides, as demonstrated in oil phantoms and bone marrow from a healthy volunteer. The volume coverage, spatial resolution, acquisition speed, and spectral characteristics of Spin-Echo Planar Spectroscopic Imaging should make it attractive for clinical studies of diseases affecting normal lipid chemical composition.     

Smooth Surjections Without Surjective Restrictions

Let f:E→F be a surjective mapping between two real or complex Banach spaces, with f having some strong differentiability properties. We investigate when there is a smaller Banach space G?E such that the restriction of f to G remains surjective.     

Symmetric Polynomials on Rearrangement-Invariant Function Spaces

The exact representation of symmetric polynomials on Banachspaces with symmetric basis and also on separable rearrangement-invariantfunction spaces over [0, 1] and [0, ) is given. As a consequenceof this representation it is obtained that, among these spaces,l_2n, L_2n[0, 1], L_2n[0, ) and L_2n[0, )L_2m[0, ) where n, m areboth integers are the only spaces that admit separating polynomials.     

Swept-potential oxidative detection in flow streams

A swept-potential electrochemical detector, operated in the oxidative staircase voltammetric metric mode, is demonstrated for the high-performance liquid chromatography of a mixture of catecholamines. Voltammetric limits of detection are approximately 30 pg or 1 nM and chromatographic limits of detection are approximately 250 pg. The use of a platinum working electrode in a wall-jet cell configuration, with potential pulses for cleaning and activation between each sweep, results in a cell that has maintained a constant response for over a year without mechanical refinishing of the electrode surface.     

Thermal chemistry of cis-1,2-dichloroethene on Pd(111)

The reaction of cis-1,2-dichloroethene (cis-DCE) on Pd(111) has been investigated by temperature-programmed desorption, laser-induced thermal desorption, Auger electron spectroscopy, and Fourier transform reflection absorption infrared spectroscopy. Below 130 K, molecularcis-DCE aggregates, resulting in only about 30% of the molecules from exposures below saturation significantly interacting with the palladium surface. The decomposition of cis-DCE generates the observable species H2, HCl, and ethylidyne. A fraction of cis-DCE molecules lose both chlorine atoms and add hydrogen to form ethylidyne, which is stable on the surface between 250 and 370 K. Hydrogen is liberated at about 420 K from cis-DCE surface fragments that immediately combine with surface chlorine and desorb as HCl. The most intense HCl desorption occurs at about 575 K and is due to surface chlorine reacting with either subsurface hydrogen or hydrogen from the remaining surface alkyl fragments. No carbon-containing species desorb from the decomposition of cis-DCE.     

On the one-dimensional Coulomb problem

We analyse the one-dimensional Coulomb problem (1DCP) pointing out some mistaken beliefs on it. We show that no eigenstates of even or odd parity can represent states of the system. The 1DCP exhibits a sort of spontaneous breaking of parity. We also show that a superselection rule operates in the system. Such rule explains some of its peculiarities. We build the superpotential associated to the 1DCP.