[en] Complete text of publication follows. In order to count on biomaterials that can be used as implants or osseous fillings, with properties similar to the physiological weave with which they interact and fluids with which they are in contact, it is necessary to make sure that their properties are nearest to each other. Therefore the knowledge of the physical properties as the optical contributes very important information to us that it helps us in the election of biomaterials used in osseous implant. In the present work by means of the technique of Photoacoustic Spectroscopy the optical absorption spectrum of used synthetic and natural materials like osseous substitutes are obtained. The optical rank of observed absorption went of 300 to 800 NM.

[en] We present a study of the influence of Ca(OH)₂ in the thermal and optical properties on pericarp films obtained from nixtamalized corn grains. The nixtamalization process was performed using alkaline solutions with different Ca(OH)₂ concentrations. For this study we have used Photoacoustic techniques and complementary analysis of optical microscopy and x-ray diffraction

[en] Cr_2-xTi_xO₃ thin films with 0 ≤ x ≤ 1.82 were prepared on sapphire substrates by aerosol assisted chemical vapour deposition. The films in the 0 ≤ x ≤ 1.6 composition range grow preserving the α-chromite structure with a lattice constant that changes as a function of the titanium concentration [Ti]. However, films with x > 1.6 start to develop a crystalline phase that can be identified as Cr-doped TiO₂. For the Cr_2-xTi_xO₃ films a Ti³⁺ → Cr³⁺ substitution is deduced from the crystalline structure and confirmed by XPS experiments. The increment in the lattice parameter agrees with the reduction in the optical band gap which goes from 3.50 eV to 2.70 eV for films with x = 0 and x ∼ 1.6, respectively. At room temperature the electrical conductivity decreases as a function of the [Ti]. The thermal stimulated conductivity indicates a trap level at ∼0.55 eV inside the gap in all the samples and the behaviour of the σ-T curves at higher temperatures indicates that the transport properties undergo a transition from a variable range hopping process to a more complicated process as the [Ti] increases.

[en] Results of optical absorption and conductivity measurements on hydrogen doped MoO₃ are reported. A simple band model on ligand-field theory is used to assign the optical transitions and explain the origin of the activation energy obtained from the conductivity data. (author)

[en] In the present study we were interested in the effects of low intensity laser irradiation on hybrid corn seeds CL₁ x CL₄ when these seeds were exposed to different laser intensities and irradiation times. In order to observe qualitative differences in chlorophyll a and b optical absorption spectra of seedling's leaves, whose seeds were irradiated and non irradiated, were obtained by using photoacoustic spectroscopy (PAS). A randomized complete blocks experimental design with three replications was used. The experimental unit included 10 seeds, from which we randomly choose three seedlings. The variance analysis (ANOVA) for both chlorophylls revealed significant (P < 0.05) differences among treatments. (authors)

[en] Thermal diffusivities of Al-Mg based metallic matrix composite reinforced with ceramic particles of Al₂O₃ are reported in this article. The samples were produced by rheocasting and the studied operational condition in this case is the shear rate: 800, 1400 and 2000 rpm. Additionally, the AlMg base alloy was tested. Measurements of thermal diffusivity were performed at room temperature by using photoacoustic technique.

[en] The thermal diffusivity of Au/Ag nanoparticles with core/shell structure, at different compositions (Au/Ag = 3/1, 1/1, 1/3, 1/6), was measured by using the mismatched mode of the dual-beam thermal lens (TL) technique. This study determines the effect of the bimetallic composition on the thermal diffusivity of the nanofluids. In these results we find a lineal increment of the nanofluid it thermal diffusivity when the Ag shell thickness is increased. Our results show that the nanoparticle structure is an important parameter to improve the heat transport in composites and nanofluids. These results could have importance for applications in therapies and photothermal deliberation of drugs. Complementary measurements with UV-vis spectroscopy and TEM, were used to characterize the Au(core)/Ag(shell) nanoparticles

[en] In this work we report the study of the thermal and optical properties of polycrystalline CdS thin films deposited by the gradient recrystallization and growth technique. CdS films were grown on pyrex glass substrates. These studies were carried out using an open photoacoustic cell made out of an electret microphone. From X-ray diffraction, atomic force microscope and photoluminescence measurements we observed polycrystalline CdS films with good morphology and crystalline quality. We obtained a thermal diffusivity coefficient of our samples with values ranging from 3.15 to 3.89 x 10^-2 cm²/s. For comparison, we measured a value of 1.0 x 10^-2 cm²/s for the thermal diffusivity coefficient of a CdS single crystal. We measured an energy gap value of 2.42 eV for our samples by using a photoacoustic spectroscopy system

[en] CdTe is a semiconductor with a wide variety of applications and perspectives for electronic industry (high-efficiency photoelectric cells, infrared radiation detectors, etc.). In the present work, we used photoacoustic (PA) technique to study the thermal properties and the surface recombination velocity in CdTe/glass samples. Experimental PA phase signal as a function of modulation frequency in a heat transmission configuration was fitted to the theoretical expression for PA signal, which takes into account the heat sources resulting from the absorption of light in semiconductors and the nonradiative processes involved, which depend on their thermal, optical and electronic transport properties. By this procedure, it was possible to determine the thermal diffusivity and the surface recombination velocity in these samples. The studied samples were thin polycrystalline CdTe film deposited on glass slides. CdTe layers were deposited by a hot-wall closed-spaced vapor transport method, known as gradient recrystallization and growth. The values for the deposition parameters used in this study were the following: 700 deg. C for the source temperature and 450 and 550 deg. C for the substrate temperatures with three different deposition times from 5 to 20 min (then three different film thicknesses were obtained). A clear increment in the surface velocity and surface roughness is observed as the film thickness is increased

[en] We describe the differential cell design and the experimental (optical and electronic) setup for the differential front photopyroelectric technique, whose theory has been developed in the first part of this paper (Ivanov et al 2008 J. Phys. D: Appl. Phys. 41 085106). We will show first how the direct (non-differential) front photopyroelectric theory described in our previous paper reproduces well the experimental results. The usefulness of the differential technique is demonstrated by means of experimental measurements of the thermal effusivity in binary ethanol-water and glycerol-water mixtures, based on a theoretical methodology that simplifies the measurement procedure and diminishes the experimental uncertainty.