Simultaneously estimating the thermal conductivity and thermal diffusivity of a poorly conducting solid material using single surface measurements.

This paper presents a new experimental method that simultaneously obtains the thermal conductivity and thermal diffusivity of a solid. This technique uses a new surface probe with a resistance heater, two thermocouples, and a heat flux sensor. In this method, part of the top of the sample is heated, and two regions on this surface (one heated and the other not) are used to estimate the thermal properties of the material. This technique minimizes two distinct functions that are defined from surface temperature measurements, using, however, different thermal concepts. The first uses the gain ratio between two surface temperatures to determine the thermal diffusivity. The second uses the well-known square quadratic error function calculated with the same experimental and theoretical values of the temperatures of the surface to estimate the thermal conductivity.

Surface parameters of as-built additive manufactured metal for intraosseous dental implants.

STATEMENT OF PROBLEM: To improve osseointegration, current machined implants are submitted to different surface treatments such as airborne-particle abrasion and acid etching. Although additive manufacturing has allowed the fabrication of implants with custom design, porosity, and roughness, whether good osseointegration can be achieved without subsequent surface treatments is still unclear. PURPOSE: The purpose of this in vitro study was to investigate the feasibility of using additive manufacturing technology for dental implants without the use of subsequent surface treatments. MATERIAL AND METHODS: The roughness, wettability, and surface energy of a flat test stainless-steel specimen produced from a 3D printer were evaluated. The roughness measurements were obtained by using a mechanical contact profilometer. The wettability was characterized by the sessile drop method by using deionized water and ethylene glycol. The surface energy values were calculated by using the Owens, Wendt, Rabel, and Kaeble (OWRK) computational method. RESULTS: The experimental data obtained were Ra=4.55 µm, Rq=5.64 µm, RSm=0.235 mm, Rsk=-0.071, Rku=3.740, Rdq=13 degrees; water contact angle=66 degrees; ethylene glycol contact angle=57 degrees; surface energy=38 mN/m. The measured values were compared with data reported in the literature for commercially available implants. The parameter Ra, which is the most used parameter to describe the surface of dental implants, was 50%, 270%, and 329% higher than that reported in the literature for commercial dental implants. The surface energy was 10% and 19% lower than the representative values in the literature for commercial dental implants. CONCLUSIONS: The results indicate that specimens fabricated by additive manufacturing had higher roughness and lower surface energy than reported results in the literature. Therefore, additive manufacturing was found to produce suitable surface parameters for dental implants, and subsequent surface treatments could be removed from the manufacturing process.

Breast tumor localization using skin surface temperatures from a 2D anatomic model without knowledge of the thermophysical properties.

Breast cancer is the second most common type of cancer among women after nonmelanoma skin cancer. Use of mammography, the main method to diagnose the disease, has several limitations in parts of the population. The primary goal of this work was to detect and localize the geometric centers of mammary tumors using only superficial temperatures of the breast skin. The 2D anatomic geometry of the breast was simulated using the commercial software COMSOL to obtain the distribution of skin temperature in the three main types of breast cancer. Random errors of  ±â€¯2% were added to the simulated temperatures. The temperature variation caused by each type of cancer on the healthy tissue was correlated with auxiliary temperature profiles. These auxiliary temperature profiles were obtained with no prior knowledge of the thermophysical properties of the tumor apart from the mean values for thermal conductivity and blood perfusion of the layers of healthy breast tissue. The results showed that the maximum error for geometric center estimation was 0.32 cm for invasive lobular carcinoma, with a diameter of 1 cm, positioned 5 cm from the skin surface. Thus, this work contributes to studies aiming to improve the use of infrared thermography for early breast cancer diagnosis, as the results showed that localization of tumors using only superficial temperature profiles does not require prior knowledge of the thermophysical properties of the tissues.