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Abstract: Anatase TiO2 has been prepared by mechanochemical synthesis using TiOSO4·xH2O and Na2CO3 as starting reactants. The reaction was performed in high-energy ball mill using steel and corundum jars, respectively. The final products were obtained by annealing the milled powder in the temperature range of 300–700°C and subsequently by washing out the water-soluble byproduct Na2SO4·xH2O. When steel jars were used, the annealing in the range of 300–600°C led to anatase. For products milled in corundum, the stability of anatase increased up to 700°C. Transition electron microscopy (TEM) showed that crystallites with a size in the range of 20–50nm with equiaxed morphology were obtained after milling in corundum and annealing at 600 and 700°C. The process of photoinduced reactive hydroxyl radical generation in aerated aqueous titania suspensions was studied by EPR spectroscopy using spin trapping technique. The presence of iron impurities in the samples milled in steel substantially decreases the radical formation. The rate of radical formation is substantially affected by particle size development of TiO2 nanopowders. The product milled in corundum and annealed at 700°C outperforms more than twice the photochemical activity of TiO2 Degussa P25 standard. [Copyright &y& Elsevier]

The standard moist heat (80 °C and 65% relative humidity) and dry heat (105 °C) techniques of accelerated paper ageing were applied in stability investigations of offset ink films printed on alkaline offset paper. The measured characteristics of paper sample evidenced its first-class mechanical properties, large alkali reserve, in addition to high values of brightness and opacity. The pseudoplastic flow behaviour was established for original offset CMYK printing inks by rheological measurements. The results obtained, following application of both ageing procedures, revealed the significant exponential decrease of relative optical density for MAGENTA and YELLOW ink layers. The variance in visible reflectance spectra and in total colour difference ΔE* (L*a*b* CIE) of ink films evidenced the considerable damage of CYAN and YELLOW ink films, especially upon moist heat treatment. The differences in lightness ΔL* play the dominant role in ΔE* values of BLACK ink films upon both ageing procedures. The FT-IR spectroscopy was additionally used in the characterization of paper, inks, as well as ink films on paper before and after ageing. [Copyright &y& Elsevier]

The photoeffect of new proflavine derivatives with DNA-binding and antitumour activities, 3,6-bis((1-alkyl-5-oxo-imidazolidin-2-yliden)imino)acridine hydrochlorides (AcrDIMs), was studied to evaluate them as potential photosensitizers for photodynamic antitumor therapy. EPR measurements showed that superoxide radical anion and singlet oxygen were produced upon irradiation of AcrDIMs with UV-A light (>300 nm) in the presence of molecular oxygen. This indicates that AcrDIMs may act as photosensitizers. The most active pentyl-AcrDIM and hexyl-AcrDIM displayed photocytotoxic effect toward the mouse lymphocytic leukemia cell line L1210 and human ovarian cancer cells A2780. Antitumor activity of pentyl-AcrDIM increased as high as about 12 times (72 h incubation) after irradiation of A2780 cells (365 nm, 1.05 J/cm 2 ). The photocytotoxicity seems to be associated with oxidative stress. Concerning the cell cycle, flow cytometry showed an arrest in the S -phase already 4 h after irradiation. In a comet assay, no genotoxicity of AcrDIMs was found. Typical morphologic changes and formation of DNA-ladders indicated induction of apoptotic cell death, though no activation of caspase-3 was observed. Investigation of intracellular localization of pentyl-AcrDIM confirmed its partial accumulation in mitochondria and lysosomes. After irradiation of the A2780 cells, colocalization of pentyl-AcrDIM with monodansylcadaverine, a lysosomal dye, was proven, suggesting that lysosomes in the irradiated cells may be involved in the cell death. [ABSTRACT FROM AUTHOR]

Abstract: Nanosized titania photocatalysts were prepared from a TiOSO4·2H2O–Na2CO3 mixture via high-energy milling for 5min, and subsequent annealing at a temperature range of 300–700°C/1h. Photoactivity of all samples monitored by electron paramagnetic resonance (EPR) spectroscopy was correlated with phase composition, crystallinity, crystal size and morphology of the annealed products. The anatase nanocrystals with an XRD average size of 24nm and well-faceted bipyramidal morphology exposed mainly by {101} type planes obtained on heating at 700°C, exhibited markedly higher photoactivity than the Aeroxide® P25 TiO2 standard and sample annealed at 600°C. The rapid increase in photoactivity was assigned to complete crystallization of the sample, optimal size, but mainly to the well-developed bipyramidal morphology of anatase nanocrystals and enlargement of the {101} type plane area due to final growth of bipyramids in the 〈001〉 direction. The weak beam dark field (WBDF) transmission electron microscopy (TEM) method was used to characterize morphology of the nanocrystals. Based on the thickness changes along the electron beam incidence inside the individual nanocrystals yielded by WBDF images, it was demonstrated that the mixture of polyhedral shaped anatase projections, such as square-like, hexagonal-like, rhomboid-like, rhombic-like, and rectangular-like prevailing in bright-field (BF) images, corresponds exclusively to tetragonal bipyramidal shape projected along different crystallographic directions. WBDF images of the most often occurring anatase nanocrystal projections are summarized and compared with both the schematic depictions of similarly oriented anatase bipyramids and that recorded in BF images. The difficulties of 3D morphology assessment from the projected nanocrystal shapes are highlighted. Attention is paid to the determination of facets limiting the nanocrystals, using the high resolution (HR)TEM method. [Copyright &y& Elsevier]

• Vanillin can be used as a scaffold for the synthesis of type I photoinitiator. • Vanillin-derived type I photoinitiator generates highly reactive radical species. • Vanillin-derived photoinitiator induces free-radical photopolymerization. A new efficient type I photoinitiator derived from vanillin was synthesized to initiate, according to a green photoinduced process, the free-radical polymerization (FRP) of acrylate monomers in a reduced time and under air. Interestingly, this unprecedented photoinitiator lead to high acrylate conversions even under air, with a higher efficiency than some reference photoinitiating systems commonly used in FRP. [ABSTRACT FROM AUTHOR]