Tuning band structures of photonic multilayers with positive and negative refractive index materials according to generalized Fibonacci and Thue-Morse sequences.

We investigate the photonic band structure, using the transfer-matrix method, in one-dimensional structures composed of a dispersive metamaterial A juxtaposed with a non-dispersive dielectric B according to the generalized Fibonacci and Thue-Morse sequences, which are ruled and characterized by two positive integer numbers, p  and q. We present the band structures of different generations of these sequences for both TE and TM modes and discuss how they are affected by the p  and q parameters and the ratio between the thicknesses of the building blocks. We obtain a new and very important analytical expression for the frequency in which the average refraction index vanishes, i.e. when the [Formula: see text] gap condition is satisfied, and we investigate, in detail, the behavior of this emergent scale insensitive gap, as a function of the thicknesses ratio, for all structures considered. For the metamaterial considered, we show that the reduced frequency for [Formula: see text] converges faster or slower to 0.41 depending on the sequence. By adjusting the p  and q parameters, we can obtain a higher concentration of the pass bands inside (outside) the n A < 0 region when there are more (less) blocks A than B in the unit cell. Our results also show the presence of omnidirectional and complete band gaps, which have various practical and technological applications.

Layperson's preference of the transverse occlusal plane in asymmetric facial model.

OBJECTIVE: Facial asymmetries are common, especially deviated nose and chin. The clinician must consider these variables when establishing the smile, placement and angulation of the occlusal plane. The purpose of this article is to determine if nose and chin deviations affect the perception of laypeople towards different angulations of the occlusal plane cant. MATERIALS AND METHOD: An asymmetric facial model was created from a symmetric facial model used in a previous study. Nose and chin were deviated 3 mm to the left and eight different pictures were created, each with different degrees of occlusal plane cant in both direction. Using a visual Likert scale delivered via Websurvey within the private practice setting, 120 randomly selected laypersons evaluated each image according to their own beauty preferences. RESULTS: In an asymmetric face, nose and chin deviated 3 mm to the left, a minor occlusal plane angulation of 2° can be perceptible regardless of the direction of the cant. CONCLUSIONS: The occlusal plane should be as parallel to the interpupillary line as possible. If occlusal cant is present, less than 2° of angulation it is preferable, regardless of the direction of the nose and chin. CLINICAL SIGNIFICANCE: In the presence of an asymmetric face, the occlusal plane should be as parallel as possible to the interpupillary line. The direction of the deviation of the nose and the chin are irrelevant factors to determine the occlusal plane. An inclination of the occlusal plane can cause vertical discrepancy, which could subsequently create malocclusion. A complete dentofacial analysis can aim at assessing the angulation of the occlusal plane not only for esthetic outcomes, but for also allowing correct occlusal function.

Application of microbial fuel cell technology for vinasse treatment and bioelectricity generation.

OBJECTIVE: Our study evaluated the performance of different two-chambered microbial fuel cell (MFC) prototypes, operated with variable distance between electrodes and Nafion membrane and specific inoculum concentration, applied for vinasse treatment. RESULTS: The performance of the developed MFC resulted in a maximum current density of 1200 mA m-2 and power density of 800 mW m-2 in a period of 61 days. MFC performed a chemical oxygen demand removal at a rate ranging from 51 to 60%. CONCLUSIONS: Taking our preliminary results into consideration, we concluded that the MFC technology presents itself as highly promising for the treatment of vinasse.