Florica Doroftei

Highly efficient copper(II) ion sorbents obtained by calcium carbonate mineralization on functionalized cross-linked copolymers.

A new type of Cu(II) ion sorbents is presented. These are obtained by CaCO3 mineralization from supersaturated solutions on gel-like cross-linked polymeric beads as insoluble templates. A divinylbenzene-ethylacrylate-acrylonitrile cross-linked copolymer functionalized with weakly acidic, basic, or amphoteric functional groups has been used, as well as different initial inorganic concentrations and addition procedures for CaCO3 crystal growth. The morphology of the new composites was investigated by SEM and compared to that of the unmodified beads, and the polymorph content was established by X-ray diffraction. The beads, before and after CaCO3 mineralization, were tested as sorbents for Cu(II) ions. The newly formed patterns on the bead surface after Cu(II) sorption were observed by SEM, and the elemental distribution on the composites and the chemical structure of crystals after interaction with Cu(II) were investigated by EDAX elemental mapping and by FTIR-ATR spectroscopy, respectively. The sorption capacity increased significantly after CaCO3 crystals growth on the weak anionic bead surface (up to 1041.5 mg Cu(II) /g sample) compared to that of unmodified beads (491.5 mg Cu(II) /g sample).

Surface characterization and drug release from porous microparticles based on methacrylic monomers and xanthan.

Porous crosslinked microparticles based on glycidyl methacrylate and xanthan were prepared by suspension polymerization and used for loading theophylline, a bronhodilatator drug, in order to obtain new drug delivery systems. The surface morphologies observed by means of SEM and AFM analysis demonstrated that microparticles show a spherical shape and are characterized by a porous structure. The presence of xanthan in the structure of microparticles leads to a decrease of surface roughness and pore diameters as well as to an increase of hydrophilicity degree compared to the micropaticles based only on glycidyl methacrylate. To analyze the in vitro release data various mathematical models were used, such as, first order, Higuchi model, Korsmeyer-Peppas model and Baker-Lonsdale model. Based on the highest values of the correlation coefficient, the analysis of the kinetic data indicate that drug release from G1 and X1 porous microparticles fits similarly well to the first order and Higuchi models and diffusion was the dominant mechanism of drug release.

Analytical techniques used for the characterization and authentification of six ancient religious manuscripts (XVIII-XIX centuries).

This article presents the experimental results of a research on six manuscripts (three of the XVIII century and three of XIX century) belonging collection of old religious books to the Moldovan Metropolitan Church of Romania. Non‐invasive techniques (optical microscopy [OM], scanning electron microscopy/energy dispersive X‐ray system, X‐ray fluorescence analysis, shrinkage temperature, and Fourier transform infrared spectroscopy/attentuated total reflectance) provided information on the degree of degradation and identification of the leather bookbinding type. Moreover, visual assessment and OM revealed the extent of the surface degradation (wane, biological attack, change color, etc.). The degradation extent of the skin bindings was determined on the 12 samples. The insight on the mechanism of degradation was accomplished by analyzing the deterioration of collagen fibers in terms of shrinkage temperature and chemical modifications induced by oxidative and hydrolytic processes. Shrinkage temperature values were lower compared with the literature data for collagen, indicating that the leather bookbinding suffered intrinsic damage. Morphological analysis was accomplished by microscopy and allowed the identification of skin type and provided information about its processing technique. Mineral elements were identified for leather composition and contributed to the information regarding the origin and the extent of degradation of the leather bookbinding, of the studied manuscripts. The analyzed results were useful in determining the state of preservation and were able to provide an increased efficiency of further restoration. The correlation of the obtained data brought new contributions to the knowledge of the leather covers for the book technique in the XVIII and XIX centuries in monastic workshops of Eastern Europe. Microsc. Res. Tech. 78:70–84, 2015.

Calcium carbonate microparticle growth controlled by a conjugate drug–copolymer and crystallization time

The influence of crystallization reaction time on CaCO3 microparticle growth from supersaturate aqueous solutions, in the presence of a conjugate drug-copolymer, has been investigated. The polymer conjugate, P(NVP-MA-Ox), is based on poly(N-vinylpyrrolidone-co-maleic anhydride) as the support and 2-amino-5-(4-methoxyphenyl)-1,3,4-oxadiazole as the drug. The microparticles are characterized by optical, scanning and transmission electron microscopy, dynamic light scattering, X-ray diffraction, flow particle image analysis and particle charge density. X-ray diffraction (XRD) investigations showed that calcite polymorph content increased with an increase in crystallization time, even if the electrostatic interactions between Ca(2+) and polyanionic sites of P(NVP-MA-Ox) structure conduct to an increased vaterite phase stability. The strong particle size increase after 6 h of ageing can be ascribed to partially vaterite recrystallization and adsorption of nano-scaled calcite crystallite nuclei at microparticles surfaces. The pH stability of the particles was shown by zeta potential changes and their adsorption capacity as a function of their composition, and characteristics were tested using methylene blue. The sorption capacity of composite materials was strongly influenced by the ratio between polymorphs in the composites, and increased with the increase of calcite content and ageing time.

Composite materials based on poly(N-isopropylacrylamide-co-methacrylic acid) hydrogels and calcium carbonate

The synthesis of complex functional materials with thermo- and pH-sensitive tunable properties based on poly(N-isopropylacrylamide-co-methacrylic acid) hydrogels with different porosities and pH-sensitive and biocompatible calcium carbonate (CaCO3) was investigated. To control the composites characteristics, two hydrogles with the same chemical composition but different porosities were used, as well as different methods for crystal growth, namely, the adding protocol of inorganic partners (rapid mixing or alternate dipping) or the carbonate source. The morphology of the new composites was investigated by scanning electron microscopy and the polymorphs content by Fourier transform infrared spectroscopy, as compared to unmodified hydrogels. Information on the interface between organic/inorganic materials, the radii of gyration of the scattering objects, their fractal dimension, and CaCO3 porosity characteristics were obtained by small-angle X-ray scattering.

Superparamagnetic Composites Based on Ionic Resin Beads/CaCO3/Magnetite

The preparation of superparamagnetic composites obtained by CaCO3 mineralization from supersaturate aqueous solutions is presented. The preparation was conducted in the presence of oleic acid stabilized magnetite nanoparticles as a water-based magnetic fluid and insoluble templates as gel-like cross-linked polymeric beads. The presence of the magnetic particles in the composites provides a facile way for external manipulation using a permanent magnet, thus allowing the separation and extraction of magnetically modified materials. Two ion exchangers based on divinylbenzene/ethyl acrylate/acrylonitrile cross-linked copolymer-a cation ion exchanger (CIE) and an amphoteric ion exchanger (AIE)-were used, as well as different addition orders of magnetite and CaCO3 crystals growth precursors. The morphology of the composites was investigated by SEM, the polymorphs content by X-ray diffraction, and the thermal stability by thermogravimetric analysis. Polymer, CaCO3 , and magnetite in the composite particles were shown to be present by energy dispersive X-ray (EDX), XPS, and TEM. The sorption capacity for CuII ions was tested, as compared to samples prepared without magnetite.