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BackgroundIn this work the chemical structure of dextran-iron oxide thin films was reported. The films were obtained by MAPLE technique from composite targets containing 10 wt. % dextran with 1 and 5 wt.% iron oxide nanoparticles (IONPs). The IONPs were synthesized by co-precipitation method. A KrF* excimer laser source (λ = 248 nm, τFWHM≅25 ns, ν = 10 Hz) was used for the growth of the hybrid, iron oxide NPs-dextran thin films.ResultsDextran coated iron oxide nanoparticles thin films were indexed into the spinel cubic lattice with a lattice parameter of 8.36 Å. The particle sized calculated was estimated at around 7.7 nm. The XPS shows that the binding energy of the Fe 2p3/2 of two thin films of dextran coated iron oxide is consistent with Fe3+ oxides. The atomic percentage of the C, O and Fe are 66.71, 32.76 and 0.53 for the films deposited from composite targets containing 1 wt.% maghemite and 64.36, 33.92 and 1.72 respectively for the films deposited from composite targets containing 5 wt.% maghemite. In the case of cells cultivated on dextran coated 5% maghemite γ-Fe2O3, the number of cells and the level of F-actin were lower compared to the other two types of thin films and control.ConclusionsThe dextran-iron oxide continuous thin films obtained by MAPLE technique from composite targets containing 10 wt.% dextran as well as 1 and 5 wt.% iron oxide nanoparticles synthesized by co-precipitation method presented granular surface morphology. Our data proved a good viability of Hep G2 cells grown on dextran coated maghemite thin films. Also, no changes in cells morphology were noticed under phase contrast microscopy. The data strongly suggest the potential use of iron oxide-dextran nanocomposites as a potential marker for biomedical applications.

SmMn2Ge2 shows reentrant ferromagnetism. Using flux grown single crystals we find that on cooling through the Curie temperature (Tt1=350 K) the material becomes ferromagnetic (FM). Upon further cooling, at Tt2=150 K an antiferromagnetic (AFM) phase is reached which is stable until Tt3=100 K when there is a transition to FM. The transitions at Tt1 and Tt2 are first order with a temperature hysteresis of about 4 K. Using ac susceptibility to determine the various transition temperatures as a function of pressure (P) we find that Tt3 rapidly decreases with increasing P and at relatively low pressures falls below our measuring range (90 K). Tt2 increases nearly linearly with P and reaches 330 K and 11 kbar. Tt1, drops slowly with increasing P and at 11 kbar the high temperature FM region ends. An x-ray determination of the lattice parameters (at atm pressure) shows that in the AFM region the a0 lattice parameter is decreased, discontinuously changing at Tt2 and Tt3. The c0 lattice parameter is essentially unchanged going through this transition region. These observations indicate that the magnetic properties of SmMn2Ge2 are very sensitive to interatomic spacing. Measurements with a differential scanning calorimeter show that, on heating, the transition at Tt2 is endothermic.

The structure, chemical composition, and optical properties of tungsten trioxide thin films grown by pulsed laser deposition were investigated. An ultraviolet KrF* excimer laser (λ=248nm, τFWHM≅20ns, ν=2Hz) was used for irradiation of tungsten trioxide targets in oxygen atmosphere. Our research focused on the effect of the ambient gas pressure and substrate temperature on the chemical composition, crystalline status, and optical properties of the obtained thin films. To this end, the films were studied by x-ray diffractometry Raman spectroscopy, and energy dispersive x-ray spectroscopy. Optical transmittance measurements were performed with a double beam spectrometer within the 400–1200nm range. The films deposited at oxygen pressure values higher than 10Pa and substrate temperatures above 300°C consist of crystalline tungsten trioxide. Their average transmittance in the visible-infrared spectral region reaches about 85% appropriate for the envisaged applications.

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Pure titanium dioxide (TiO 2 ) and graphene oxide (GO) as well as TiO 2 / GO composite structures were grown by matrix-assisted pulsed laser evaporation (MAPLE) in a controlled oxygen atmosphere. The MAPLE target dispersions were prepared using distilled water as solvent matrix, with TiO 2 nanoparticles (NPs) and GO platelets serving as host materials. Two laser sources, a free-running IR Er:YAG (λ = 2940 nm, τ fwhm ≅ 350 μs, ν = 10 Hz) and a UV KrF* excimer (λ = 248 nm, τ fwhm ≅ 25 ns, ν = 10 Hz) laser, were used for the transfer and immobilization experiments by infrared (IR)-and ultraviolet (UV)-MAPLE, respectively. The potential physical mechanisms implied in both the IR-and UV-MAPLE processes are discussed, based on numerical simulations of temperature evolution of the distilled water matrix, TiO 2 NPs, and GO platelets. Our results demonstrate the effectiveness of IR-and UV-MAPLE processes for the immobilization of nanoentities onto solid substrates. During IR-MAPLE, the laser radiation is primarily absorbed by the water matrix. The materials transferred to the substrate surface resemble the initial starting materials used for the preparation of the MAPLE target dispersions. Conversely, during UV-MAPLE the UV radiation is mainly absorbed by the nanoentities dispersed in the water matrix. The structural transformation of the nanoentities deposited by UV-MAPLE is significant as compared to the starting materials.