Enhancing Efficiency of Perovskite Solar Cells via N-doped Graphene: Crystal Modification and Surface Passivation

Controlling the morphology and surface passivation in perovskite solar cells is paramount in obtaining optimal opto-electronic properties. This study incorporates N-doped graphene nanosheets in the perovskite layer, which simultaneously induces an improved morphology and surface passivation at the perovskite/spiro interface, resulting in enhancement in all photovoltaic parameters

Protective Ag :TiO2 thin films for pressure sensors in orthopedic prosthesis: the importance of composition, structural and morphological features on the biological response of the coatings

DC reactive magnetron sputtered Ag:TiO2 nanocomposite thin films were developed to be used as protective coatings in pressure sensor devices. The coatings, with Ag content varying from 0 to about 30 at.%, were prepared and characterized in order to study their biological response. The as-deposited samples were annealed in vacuum at 500 °C in order to evaluate the influence of their morphological and structural differences over the response elicited upon contact with simulated bodily fluids and cultured human cells, as well as selected microorganisms. The results showed that the annealing treatment produced less porous films with an enhanced structure, with a significant reduction in structural defects and improved crystallinity. Additionally, samples with higher Ag contents (≥12.8 at.%) exhibited Ag agglomerates/clusters at the surface, a result anticipated from the XRD data. The crystallization of the TiO2 matrix was also observed by XRD analysis, albeit delayed by the dispersion of Ag into the matrix. Biological characterization showed that the antimicrobial activity and cytotoxicity of the coatings were directly related with their composition, closely followed by the particular structural and morphological features, namely those resulting from annealing process.This research is partially sponsored by FEDER funds through the program COMPETE—Programa Operacional Factores de Competitividade and by national funds through FCT—Fundação para a Ciência e a Tecnologia, under the projects PEst-C/EME/UI0285/2011, PTDC/SAU-ENB/116850/2010, PTDC/CTM-NAN/112574/2009P. T Matamá acknowledges FCT for Grant SFRH/BPD/47555/2008

Deconstructing classical water models at interfaces and in bulk

Using concepts from perturbation and local molecular field theories of liquids we divide the potential of the SPC/E water model into short and long ranged parts. The short ranged parts define a minimal reference network model that captures very well the structure of the local hydrogen bond network in bulk water while ignoring effects of the remaining long ranged interactions. This deconstruction can provide insight into the different roles that the local hydrogen bond network, dispersion forces, and long ranged dipolar interactions play in determining a variety of properties of SPC/E and related classical models of water. Here we focus on the anomalous behavior of the internal pressure and the temperature dependence of the density of bulk water. We further utilize these short ranged models along with local molecular field theory to quantify the influence of these interactions on the structure of hydrophobic interfaces and the crossover from small to large scale hydration behavior. The implications of our findings for theories of hydrophobicity and possible refinements of classical water models are also discussed

Delaying the Stall of A Low-Wing Aircraft Using A Novel Powerful Vortex Generator

In this study, a new aerodynamic surface concept is introduced, which is a powerful vortex generator (PVG). It can delay the stall point in a low-wing aircraft. This delay leads to a significant increase in the CLmax of an aircraft. The results of this research show that the use of PVG, due to its longitudinal position, does not affect the aerodynamic center of the aircraft as well as its static stability. This is an advantage for this method compared to the method based on LEX, in which the aerodynamic center moves forward and the static stability of the aircraft reduces. As a case study, this research focused on a low-wing advanced training jet. Additionally, the aerodynamic characteristics of the aircraft were investigated in three points, including takeoff /landing condition, one maneuvering point, and one MMO condition. To evaluate the concept of PVG in more realistic situations, the wing airfoil was optimized at the same three points using the adjoint method. Then, the effect of PVG on various configurations of the aircraft, including the clean configuration and the different types of flap, was investigated. Since all the analyses were performed using computational fluid dynamics, at first, the validation of numerical methods was conducted on two test cases in low-speed and high-speed flows. The results of the case study show that the PVG greatly delays the separation and increases the value of CLmax. For example, in the case of a hinged leading-edge flap and single slotted trailing-edge flap, more than 12 degrees of delay in the stall was achieved, and the value of CLmax increased from 1.4 to 2.05 (46% increase)