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Two new cationic Cu(II) complexes of cyclam (1,4,8,11-tetraazacyclotetradecane) and aminocarboxylate coligands glycine or alanine have been synthesized. The complexes were characterized by elemental analysis (C, H and N), molar electrical conductivity, magnetic susceptibility measurement at room temperature, spectral methods (UV/Vis and Fourier transform infrared), as well as by thermogravimetric (TG) and differential thermal analysis (DTA). The analytical data of the complexes show the formation of mononuclear complexes with general formula [Cu(L)cyc](ClO4)2·nH2O, A) L = glycine, n = 1.5 and B) L = alanine, n = 2.5. The tetradentate ligand cyclam was coordinated to metals through four N donors. The spectroscopic data suggested that the amino carboxylate ligands coordinated via their carboxylate ion moieties. The six- -coordinate octahedral geometry around Cu(II) in both complexes was presumed. TG-DTA analysis indicated that complex B decomposed exothermally in a single step in the range of 310–400°C. The cytotoxic activity of Cu(II) complexes and the starting ligands were tested against human cervix adenocarcinoma cell line (HeLa), human melanoma (FemX) and human colon carcinoma (LS174). The IC50 values for the Cu(II) complexes were from 48.35–82.25 μM. Both complexes were tested for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and the yeast Candida albicans.

Detailed analysis covered the optical and structural properties of Eu3+-doped NaY9Si6O26 oxyapatite phosphors, which were obtained via hydrothermal synthesis. X-ray diffraction patterns of NaY9Si6O26:xEu3+ (x = 0, 1, 5, 7, 10 mol% Eu3+) samples proved a single-phase hexagonal structure (P63/m (176) space group). Differential thermal analysis showed an exothermic peak at 995 °C attributed to the amorphous to crystalline transformation of NaY9Si6O26. Electron microscopy showed agglomerates composed of round-shaped nanoparticles ~53 nm in size. Room temperature photoluminescent emission spectra consisted of emission bands in the visible spectral region corresponding to 5D0 → 7FJ (J = 0, 1, 2, 3, 4) f-f transitions of Eu3+. Lifetime measurements showed that the Eu3+ concentration had no substantial effect on the rather long 5D0-level lifetime. The Eu3+ energy levels in the structure were determined using room-temperature excitation/emission spectra. Using the 7F1 manifold, the Nv-crystal field strength parameter was calculated to be 1442.65 cm−1. Structural, electronic, and optical properties were calculated to determine the band gap value, density of states, and index of refraction. The calculated direct band gap value was 4.665 eV (local density approximation) and 3.765 eV (general gradient approximation). Finally, the complete Judd–Ofelt analysis performed on all samples confirmed the experimental findings. [ABSTRACT FROM AUTHOR]

This work aims to find the optimal ratio of recycled rubber (RR) in carbon black (CB)/RR filler and determine its influence on the mechanical properties, thermal behavior, and activation energy of ternary rubber based on polyisoprene (natural rubber [NR]), polybutadiene (butadiene rubber [BR]), and styrene–butadiene rubber (SBR) with a constant ratio of 40/40/20 parts per 100 of rubber (phr). The filler used was N330 (60 phr) and a mixture of CB/RR filler in the following proportions: 55/5, 50/10, and 40/20 phr. The activation energy of the examined samples was determined by the rheometric method. The samples were subjected to thermo‐oxidative (at 100°C after 168 h) and γ‐radiation aging (200 kGy). Hardness, tensile strength, and elongation at break were evaluated before and after thermo‐oxidative and γ‐radiation aging. SEM, attenuated total reflectance fourier‐transform infrared (ATR‐FTIR), and TG/DTG techniques were used to characterize NR/BR/SBR composites. The results show that the most optimal CB/RR ratio is 55/5 phr, which is confirmed by the mechanical properties before and after aging and the results for the activation energies of cross‐linking and reversion. The thermal stability of the composite containing 60 phr of the CB and the composite reinforced with 5 phr of the RR in CB/RR filler is almost the same. The results of this research may be applicable in the automotive tire industry since NR/BR/SBR composites are used for automotive tire treads. Another benefit of this research is that the partial replacement of CB with RR contributes to the reduction of tire waste, and thus to the preservation of environmental protection. Highlights: Rubber composite NR/BR/SBR = 40/40/20 phr reinforced with CB/RR fillerThe amount of RR in the CB/RR filler has been changed to 5, 10 and 20 phrThe lowest value for Eac has the sample containing filler CB/RR = 55/5 phrThe most thermally stable sample is the sample with 5 phr RR in CB/RR fillerRR (5 phr) can be applied in CB/RR filler to reinforce NR/BR/SBR composites [ABSTRACT FROM AUTHOR]

Sphene based glass-ceramics (CaTiSiO5), an excellent candidate for a host lattice of ceramic materials and for nuclear waste immobilization, has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization. Starting powders were melted at 1400°C for 2 h, cooled to room temperature, grounded again, then crystallized by thermal treatment yielding a sphene glass-ceramic. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD), FT-IR, Raman and thermal analyses (TG-DTA). Pure synthetic single phase sphene was formed at 800°C for 4 h, even it is very hard to obtain monophase powder at such low temperature. Powder morphology was analyzed by scanning electron microscopy (SEM). [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45012]

The elastomeric materials based on NR/BR/SBR ternary rubber blend were investigated. The polyisoprene (NR), butadiene (BR) and styrene butadiene (SBR) rubbers were used as network precursors and carbon black (CB) as an active filler (60 phr) for elastomeric materials preparation. For sample preparation, the mass ratio of NR to BR was constant, 1:1, but the SBR content was varied from 0 to 80 phr. The morphological, mechanical and thermal properties of prepared elastomeric materials were determined using scanning electron microscopy (SEM), mechanical tensile measurements and thermogravimetric analysis (TGA). Mechanical properties were assessed before and after thermooxidative aging during 168 h at 100 °C. The values of tensile strength, elongation at break, and hardness decrease up to 40 phr of SBR content and after that are increasing, but abrasion resistance of ternary rubber blends increases. Тhe thermal decomposition temperature obviously shifted to a higher temperature for the sample with 40 phr of SBR. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45022 and Grant no. 45020]

This paper presents influence of the type of carbon nanotube functionalization on properties of poly(L-lactide) (PLLA) based nanocomposite materials. For this purpose surface modifications of multi-walled carbon nanotubes (MWCNTs) were performed by chemical and irradiation techniques, while thermo gravimetric analysis, UV-Visible and Fourier-transform infrared (FT-IR) spectroscopies confirmed successful covalent functionalization. Series of PLLA bionanocom-posites with different contents of functionalized MWCNTs (0.7; 1.6; 2.1 wt%), were synthesized via ring-opening solution polymerisation of L-lactide. FT-IR analysis confirmed that grafting of L-lactide, under controlled condition, is possible to perform starting from the surface of functionalized MWCNTs. From differential scanning calorimetry results it was concluded that even low contents of chemically and irradiation functionalized MWCNTs had a significant effect on thermal properties of the prepared nanocomposites, raising the values of melting and glass transition temperatures. Thermogravimetric analysis (TGA) has shown that the degradation onset temperature for composites with chemically functionalized MWCNTs, was much higher than that for the neat poly(L-lactide) sample and composites with irradiation functionalized MWCNTs. Morphology studies by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that poly(L-lactide) covered surfaces and separated functionalized MWCNTs. Good dispersion of carbon nanotubes in polymer matrix enabled conductivity of synthesized materials, as determined by conductivity tests. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45022 and Grant no. III 45020]

Amorphous iron (III) oxide was obtained from clay, using ammonium hydroxide as a precipitating agent. Influence of freeze drying under vacuum, as a drying method, on particle size, chemical composition, and crystallinity of obtained iron (III) oxide powder was investigated. After freeze drying, precipitate was annealed in air at 500°C and 900°C. X-ray diffraction, particle size analysis, scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis were used to characterize obtained iron (III) oxide powder. All of three powders obtained by freeze drying and annealing, have low crystallinity and particles with irregular layered shape. Narrow particle size distribution was given by an average diameter value of around 50 μm for all observed powders. Iron-bearing materials like α-Fe2O3 and γ- Fe2O3 are obtained. Differential thermal analysis curve of obtained samples showed endothermic reaction at 620°C which could be ascribed to phase transition from cubic form γ- → α- Fe2O3. Thermal transformations of iron (III) oxide, obtained from clay as a natural source, is suitable to explore in the framework of materials chemistry, and opens the possibility to synthesize materials based on Fe2O3 with specific magnetic behavior. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III-45012, Grant no. OI-172045, Grant no. III-45015, Grant no. OI-176010, Grant no. OI-172056 and Grant no. III-45007]