New chitosan wound dressing – first step - the cytotoxicity evaluation

The cytotoxicity of chitosan with polyvinox (PCH) and crosslinked chitosan (CH) was studied and analyzed. Cell viability was determined by thiazolyl blue formazan (MTT) assay and cell morphology observations were carried out during cell culturing and MTT tests. Crosslinked chitosan was used as a protective foil (scaffold) for skin wounds. Studies in vitro and the other obtained in this work results prove that the studied materials CH and PCH do not cause cytotoxic activity to Balb 3T3 mouse fibroblasts. CH and PCH are promising biomaterials with prospective application as wound healing dressings

Influence of thermally induced oxygen order on mobile ion dynamics in Gd_(2)(Ti_(0.65)Zr_(0.35))_(2)O_(7)

We report on the influence of oxygen order in the oxygen-ion dynamics in the ionic conductor Gd_(2)(Ti_(0.65)Zr_(0.35))_(2)O_(7). The metastable Gd_(2)(Ti_(0.65)Zr_(0.35))_(2)O_(7) powders prepared by mechanical milling present an anion-deficient fluorite type of structure, stable up to about 800 °C. Thermal treatments at higher temperatures facilitate the gradual rearrangement of the cation and anion substructures and the relaxation of mechanochemically induced defects. Interestingly, metastable pyrochlores showing a very unusual cation distribution were observed during the thermally induced defect-recovery process. We have found that the ionic conductivity due to mobile oxygen ions increases significantly with increasing sintering temperature from 800 to 1500 °C as a result of a systematic decrease in the activation energy for the dc conductivity from 1.23 to 0.78 eV. Electrical conductivity relaxation is well described by stretched exponentials of the form φ(t)=exp[-(t/τ)^(1−n)], and the fractional exponent n decreases systematically from n=0.51 to 0.18 with increasing sintering temperature. These results are explained in terms of weaker ion-ion interactions in the increasingly ordered structure of the samples sintered at higher temperatures, and point to the importance of structural disorder in determining the dynamics of mobile oxygen ions

Structural and Luminescence Behavior of Nanocrystalline Orthophosphate KMeY(PO4)2: Eu3+ (Me = Ca, Sr) Synthesized by Hydrothermal Method

KMeY(PO4)2:5% Eu3+ phosphates have been synthesized by a novel hydrothermal method. Spectroscopic, structural, and morphological properties of the obtained samples were investigated by X-ray, TEM, Raman, infrared, absorption, and luminescence studies. The microscopic analysis of the obtained samples showed that the mean diameter of synthesized crystals was about 15 nm. The KCaY(PO4)2 and KSrY(PO4)2 compounds were isostructural and they crystallized in a rhabdophane-type hexagonal structure with the unit-cell parameters a = b ≈ 6.90 Å, c ≈ 6.34 Å, and a = b ≈ 7.00 Å, c ≈ 6.42 Å for the Ca and Sr compound, respectively. Spectroscopic investigations showed intense 5D0 → 7F4 transitions connected with D2 site symmetry of Eu3+ ions. Furthermore, for the sample annealed at 500 °C, europium ions were located in two optical sites, on the surface of grains and in the bulk. Thermal treatment of powders at high temperature provided better grain crystallinity and only one position of dopant in the crystalline structure. The most intense emission was possessed by the KSrY(PO4)2:5% Eu3+ sample calcinated at 500 °C

Physicochemical Characterization of the Loganic Acid–IR, Raman, UV-Vis and Luminescence Spectra Analyzed in Terms of Quantum Chemical DFT Approach

The molecular structure and vibrational spectra of loganic acid (LA) were calculated using B3LYP density functional theory, the 6–311G(2d,2p) basis set, and the GAUSSIAN 03W program. The solid-phase FTIR and FT-Raman spectra of LA were recorded in the 100–4000 cm−1 range. The assignment of the observed bands to the respective normal modes was proposed on the basis of the PED approach. The stability of the LA molecule was considered using NBO analysis. The electron absorption and luminescence spectra were measured and discussed in terms of the calculated singlet, triplet, HOMO, and LUMO electron energies. The Stokes shift derived from the optical spectra was 20,915 cm−1

Structural and Vibrational Properties of Imidazo[4,5‑<i>c</i>]pyridine, a Structural Unit in Natural Products

The molecular structures and vibrational properties of 1<i>H</i>-imidazo­[4,5-<i>c</i>]­pyridine in its monomeric and dimeric forms are analyzed and related to the experimental results derived from the XRD, IR, and Raman studies. The theoretical data are discussed on the basis of DFT quantum chemical calculations using the B3LYP correlation functional and 6-311G­(2d,2p) basis set. This compound crystallizes in the non-centrosymmetric orthorhombic space group <i>Fdd</i>2. The asymmetric unit contains one molecule of 1<i>H</i>-imidazo­[4,5-<i>c</i>]­pyridine and disordered molecules of solvents. The molecules are organized in hydrogen-bonded chains propagating along the [1 0 −3] direction. The stability of the dimeric form arising from charge delocalization and the existence of an N–H···N intermolecular hydrogen bond has been analyzed using the natural bond orbital approach. The normal modes, which are unique for the imidazopyridine skeleton, have been identified. The spectra of other compounds containing the imidazopyridine unit have been analyzed