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Abstract  

In this article, synthesis, characterization, and thermal properties of diacrylic/divinylbenzene copolymers based on the new aromatic tetrafunctional acrylate monomers are presented. The new monomers were generated by treatment of epoxides derived from various aromatic diols: naphthalene-2,3-diol (NAF), biphenyl-4,4′-diol (BIF), bis(4-hydroxyphenyl)methanone (BEP) or 4,4′-thiodiphenol (BES), and epichlorohydrin with acrylic acid. The addition reaction was carried out by a ratio of 0.5 mol of suitable epoxy derivative and 1 mol of acrylic acid in the presence of 0.7 wt% of triethylbenzylammonia chloride (TEBAC) as a catalyst and 0.045 wt% of hydroquinone as a polymerization inhibitor. The chemical structure of the prepared acrylate monomers was confirmed by 13C NMR and GC MS spectra. The emulsion–suspension polymerization of acrylate monomers with divinylbenzene (DVB) in the presence of pore-forming diluents (toluene + decan-1-ol) allowed obtaining microspheres containing pendant functional groups (hydroxyl groups). This process was carried out at constant mol ratio of acrylate monomers: DVB (1:1), and constant volume ratio of pore-forming diluents to monomers (1:1). The different concentrations of toluene in the mixture with decan-1-ol were used for qualifying the effect of the diluents on the microsphere characteristics. The influence of synthesis’s parameters on the properties of copolymer beads, e.g., pore size and surface area by BET method, the surface texture by AFM, swelling behavior in polar and non-polar solvents as well as thermal stability by differential scanning calorimetry (DSC), and thermogravimetric analysis (TG) was studied and discussed.

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Experimental results for the wicking process in a solid thin porous layer by liquids of different polarity with defined surface free energy components and viscosity has been considered theoretically. The method was used for determination of the solid surface free energy of the adsorbents used in thin layer chromatography. Experiments were performed on commercial glass plates precoated with silica, CN-silica, diol-silica, NH 2 -silica, and silanized silica with n -alkanes, diiodomethane, water, and formamide as mobile phases. Surface free energy components determined for investigated adsorbents were used for characterization and comparison of their surface properties.

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Abstract  

The structure of aqueous solutions of 1,2-butanediol and 1,4-butanediol was investigated using adiabatic compressibility measurements and positron annihilation methods. In the case of 1,2-butanediol the experimental results are very similar to those obtained earlier for systems where hydrophobic hydration dominates. In both cases there are evidences for increased rigidity of the water network, which arises from the formation of hydrogen bonds between diols and water. The usefulness of both the methods applied in investigating the structure of liquid solutions was proved.

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Abstract  

An experimental method is described for the synthesis of195mPt-radiolabeled cis-diammine (glycolato) platinum (II) (254-S). Ten mg of 95% enriched194Pt was irradiated for 75 h in the hydraulic conveyer of KUR at a thermal neutron flux of ca. 8.15×1013 n·cm–2·s–1, and the195mPt-radiolabeled 254-S was synthesized and purified using HPLC (column: Dichrosorb Diol, elution: 80% CH3CN). The chemical yield was approximately 45%, with chemical purity greater than 98.4%. The radionuclidic purity was nearly 100% and the specific activity, 7.2 MBq·mg–1 254-S.

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Natural phenolic compounds, e.g. ellagitannins, gallotannins, and flavonoid glycosides, from the aerial parts of Erodium cicutarium ( Geraniaceae ) have been isolated and identified. The structures of these compounds were determined by conventional methods of analysis and confirmed by MS and NMR spectral analysis. The distribution of tannins and flavonoids in E. ciconium, E. cicutarium, E. manescavi , and E. pelargoniiflorum were examined by TLC on unmodified silica gel and on silica gel chemically modified with polar and nonpolar groups (HPTLC Si 60, HPTLC Si 60 LiChrospher, HPTLC diol, HPTLC CN, and HPTLC RP-18W).

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Abstract  

Extractive purification of boric acid from radioactive corrosion and fission products dissolved in aqueous solutions modelling nuclear reactor coolants has been studied. Aliphatic 1,3-diols containing 8 and 9 carbon atoms per molecule were used as extractants fro boric acid. The behaviour of some representative corrosion and fission products as well as various factors affecting their distribution between the organic and aqueous phases have been investigated under the conditions of boric acid extraction. Conditions for the effective separation of boric acid from most of the radioactive contaminants are presented.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Ştefănescu, O. Ştefănescu, M. Stoia, and C. Lazau

Abstract  

In this paper we present a study on the synthesis of Fe(III) oxide, by thermal decomposition of some complex combinations of Fe(III) with carboxylate type ligands, obtained in the redox reaction between some polyols (ethylene glycol (EG), 1,2-propane diol (1,2PG), 1,3-propane diol (1,3PG) and glycerol (GL)) and NO3 ions (from ferric nitrate). Fe2O3 was obtained by thermal decomposition of the synthesized metal-organic precursors at low temperatures. γ-Fe2O3 was obtained as nanoparticles at 300C, while at higher temperatures α-Fe2O3 starts to crystallize and becomes single phase at ~500C. The formation of the metal-organic precursors and their thermal decomposition were studied by thermal analysis and FTIR spectroscopy. The evolution of Fe2O3 crystalline phases with the thermal treatment of iron complexes was followed by RX diffractometry. The size of γ-Fe2O3 nanoparticles was estimated by transmission electron microscopy (TEM).

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Abstract  

In this paper, the non-isothermal differential scanning calorimetry (DSC) was employed to investigate the cure process and to determine the kinetic parameters of the curing reaction of the unsaturated polyester resin catalyzed with promoter-cobalt(II)octoate and free-radical initiators. The initiators were formed by the oxidation process of acetylacetone with 60% hydrogen peroxide in the presence of the catalyst-sulphuric acid and the solvents: propano-1,2-diol or the mixture of propano-1,2-diol and hydroxypolyether TG 500. As a reference, the typical curing system containing ethyl methyl ketone hydroperoxide (Luperox) and promoter was used. It was found that the cure process of the unsaturated polyester resin with the new initiators/cobalt(II)octoate was described through lower maximum peak temperatures (T max) and lower values of the total heat of the curing reaction (ΔH R) in comparison with Luperox/cobalt(II)octoate. The computed values of activation energies were in the range of 40.8–44.9 and 80.4–87.6 kJ mol–1 for unsaturated polyester resin cured with the new initiators/cobalt(II)octoate. The values of activation energies were little lower or comparable to those obtained when Luperox/cobalt(II)octoate system was used (45.8 and 82.3 kJ mol–1).

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Conditions have been established for TLC separation of a mixture of nine quinolizidine alkaloid standards (lupanine, methylcytisine, cytisine, hydroxylupanine, sophocarpine, lusitanine, retamine, sparteine, and l - α -isosparteine) and of alkaloid fractions from a variety of Genista species and from in-vitro cultures of members of this species. Optimization of the one-dimensional TLC separation of the nine alkaloid standards was performed on two types of layer, RP-18W and silica gel. The mixture of standards was also chromatographed by two-dimensional TLC on diol F 254S layers and by 2D TLC with an adsorbent gradient. In the last variant (so-called graft TLC) the first development was performed on a TLC diol plate and the second, in the perpendicular direction, on an RP-18W TLC plate. Only by 2D TLC with an adsorbent gradient was it possible to achieve full separation both of the standards and of alkaloid fractions from plant material. Under these conditions the presence of retamine, cytisine, sparteine, l - α -isosparteine, lupanine, and methylcytisine was discovered in all Genista species and in shoot cultures of G. tinctoria .

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Abstract  

Thermal decomposition of metal-organic precursors for the mixed oxide BaBiO3 was studied using TG and EGA. Precursors produced by polyesterification of bifunctional acids with ethylene glycol (Pechini process) decomposed about 100°C higher than those without the diol. BaCO3 was identified by IR and XRD as a reaction intermediate. EGA proved that the amount of BaCO3 was below 10% of the total barium, and that the barium exists mainly as a nitro-compound up to 650°C. Phase-pure BaBiO3 with a moderately high surface area (1.4 m2/g) could be synthesised from a citrate precursor by the Pechini process at around 850°C.

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