In this work, we report the thermal characterization of platelike composite samples made of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy and thermal relaxation, the thermal diffusivity, conductivity and volumetric heat capacity of the samples were experimentally measured. The volume fraction of inclusions was systematically varied in order to study the changes in the effective thermal conductivity of the composites. In some samples, a static magnetic field was applied during the polymerization process resulting in anisotropic inclusion distributions. Our results show a decrease in the thermal conductivity of some of the anisotropic samples compared to the isotropic randomly distributed ones. Our analysis indicates that the development of elongated inclusion structures leads to the formation of magnetite and resin domains causing this effect. We correlate the complexity of the inclusion structure with the observed thermal response by a multifractal and lacunarity analysis. All the experimental data are contrasted with the well known Maxwell-Garnett's effective media approximation for composite materials.

Cephalometric analysis is an excellent instrument in clinical diagnosis, treatment, and recovery from surgery. Nowadays, efforts to develop computerized dental X-ray image Cephalometric analysis systems for clinical and education usages. Much commercial software is created, but its high cost is unaffordable for some undergraduate students or low-income medical institutions; sure, the best option is the use of open source software alternatives. The study aimed to design free software Cephalopoint that applies vector algebra to perform the accuracy and precision of Cephalometric analysis. Three tests were used to validate the measurements made: accuracy test, consisting of comparing three selected cases and reply 32 times using the manual and software technique measurement; time test, consisted in obtaining the average time used to complete manual and software techniques of the previous test; and statistical test, consisted of measuring and applying the statistical analysis of 42 random cases for each method only using the software technique. The results showed high repeatability and no significant difference between manual tracing and software techniques. All the variables calculated with the software technique exhibited a normal distribution. Cephalopoint is excellent software for accurate and precise Cephalometric measurements. Moreover, it significantly decreased the measurement time compared with the manual.

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Abstract. In this work, we study the thermal transport properties of platelike composite two-layer samples made of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy and thermal relaxation, their effective thermal diffusivity and conductivity were experimentally measured. The composite layers were prepared under the action of a static magnetic field, resulting in anisotropic inclusion structures with the formation of chains of magnetite particles parallel to the faces of the layers. In one kind of bilayers, a composite layer was formed on top of a resin layer while their relative thickness was varied. These samples can be described by known models. In contrast, bilayers with the same concentration of inclusions and the same thickness on both sides, where only the angle between their inclusion structures was systematically varied, show a nontrivial behaviour of their thermal conductivity as a function of this angle. Through a lacunarity analysis, we explain the observed thermal response in terms of the complexity of the interface between the layers.

The effective mechanical properties of composites are affected by the distribution and formation of agglomerations of graphite nanoparticles in a polyester resin matrix. The samples were made varying the volume concentration of inclusions and their maximum tensile strength and morphology of agglomerations were measured. The morphology of agglomerations was analyzed by measuring their average area, fractal dimension and lacunarity from the micrographs. A predictive model of the effective mechanical properties based on the ruleof-mixtures (ROM) was proposed, the parameters related to the complex microstructure were incorporated into the ROM model. This modified model proved to be a good tool for describing the effect of inclusions on effective mechanical properties by changing their volume concentration. Also, a statistical model based on multiple linear regression of observable variables was proposed, which is better for predicting the effective mechanical property.