Search results for "Note"

Effect of Hot Drawing on the Mechanical Properties of Biodegradable Fibers

2016

The use of biodegradable polymers is increasingly attracting interest over the last years, since they can reduce the environmental effects related to disposal of traditional plastics and, in general, the use of fossil, non-renewable resources. One of the most promising applications is represented by fibers production. However, the orientation and the crystallinity degrees can significantly affect the mechanical properties. Therefore, it is of interest to investigate on the optimum processing conditions, in order to improve the mechanical properties. In particular, while crystallinity can be slightly modified by the processing, orientation can be significantly improved. In this work, the eff…

Theoretical study on hydrogen storage capacity of expanded h-BN systems

2017

In this work, the hydrogen storage capacity of the expanded hexagonal Boron Nitride (eh-BN) systems has been presented. We have employed a new equation of state (EOS) for hydrogen gas to figure out the hydrogen density distribution profiles in the eh-BN systems. In this regard, the environmental conditions (i.e., temperature and pressure) are considered in the prediction procedure using DFT single point calculations. The eh-BN systems with different layer spacings are studied by PBE method with consideration of the long range dispersion corrections. On account of the in-plane polar bonds, a series of adsorption positions are considered. Additionally, the adsorption energy and hydrogen densi…

2017

The volume of ordinary materials decreases in response to a pressure increase exerted by a surrounding gas or liquid, i.e., the material volume compressibility is positive. Recently, poroelastic metamaterial architectures have been suggested theoretically that allow for an unusual negative effective static volume compressibility—which appears to be forbidden for reasons of energy conservation at first sight. The challenge in the three-dimensional (3D) fabrication of these blueprints lies in the necessary many hollow 3D crosses sealed by thin membranes, which we realize in this work by using 3D laser microlithography combined with a serendipitous mechanism. By using optical-microscopy cross-…

Investigation on Metal–Oxide Graphene Field-Effect Transistors With Clamped Geometries

2019

In this work, we report on the design, fabrication and characterization of Metal-Oxide Graphene Field-effect Transistors (MOGFETs) exploiting novel clamped gate geometries aimed at enhancing the device transconductance. The fabricated devices employ clamped metal contacts also for source and drain, as well as an optimized graphene meandered pattern for source contacting, in order to reduce parasitic resistance. Our experimental results demonstrate that MOGFETs with the proposed structure show improved high frequency performance, in terms of maximum available gain and transition frequency values, as a consequence of the higher equivalent transconductance obtained.

Interfacial Modification for High-Efficiency Vapor-Phase-Deposited Perovskite Solar Cells Based on a Metal Oxide Buffer Layer.

2018

Vacuum deposition is one of the most technologically relevant techniques for the fabrication of perovskite solar cells. The most efficient vacuum-based devices rely on doped organic contacts, compromising the long-term stability of the system. Here, we introduce an inorganic electron-transporting material to obtain power conversion efficiencies matching the best performing vacuum-deposited devices, with open-circuit potential close to the thermodynamic limit. We analyze the leakage current reduction and the interfacial recombination improvement upon use of a thin (<10 nm) interlayer of C60, as well as a more favorable band alignment after a bias/ultraviolet light activation process. This wo…

R-Curve Modelling of Mode I Delamination in Multidirectional Carbon/Epoxy Composite Laminates

2014

In the present work, the mode I delamination behaviour of a quasi-isotropic quasi-homogeneous carbon/epoxy composite laminate with adjacent plies of 0o//45o is studied numerically. To describe the R-curve behaviour observed during crack propagation, a linear-exponential traction-separation law is proposed, where the fracture toughness and the increment in the fracture energy could be considered separately in the model. This model is then implemented in the finite element simulation of the delamination process in the composite laminate. Numerical results indicate that with the incorporation of the fibre bridging effect leads to a well-predicted force-displacement response of the composite la…

Guidelines for the assessment of the rate law of slurry photocatalytic reactions

2017

Abstract The assessment of the rate law of slurry photocatalytic reactions appears to be a hard task, mainly because in this type of reactions the average rate of reaction, which is experimentally observed in a real reactor, could be very different from the “true” (intrinsic) rate of reaction, which cannot be measured directly. In the present work, it is shown how a proper mathematical model allows the utilization of the differential and/or the integral methods of kinetic analysis. The mathematical model must take into account not only the momentum and the mass balances, but also the radiative transfer equation. However, the discrimination among different proposed kinetic laws remains diffi…

Process intensification in a photocatalytic membrane reactor: Analysis of the techniques to integrate reaction and separation

2017

Abstract Different methods to integrate reaction and separation in a membrane reactor are studied in the present work, with the aim being to highlight the pros and cons of the different alternatives and the effects of the intervening parameters. The coupling of the two processes can take place inside a single apparatus or using separate units. If a single apparatus is utilized, the coupling is more direct, but separate units offer higher degrees of freedom for the design with more opportunities to optimize the system without constraints. However, when using separate units, the integration of the two unit operations depends largely on the parameters intervening in the coupling procedure. The…

Adsorption of hydrogen isotopes in the zeolite NaX: Experiments and simulations

2017

Abstract Among the different methods to separate hydrogen isotopes one is based on the physisorption at low temperature (below 100 K) where quantum effects induce a particular behavior. In the present work, we study the adsorption of single H 2 and D 2 on the zeolite NaX by combining experiments (manometry) from 30 to 150 K and molecular dynamics simulations at 40 and 77 K. Simulations also include the adsorption analysis for T 2 . Adsorption on NaX membranes is simulated and quantum corrections are introduced by using the well-known Feynman–Hibbs approach into the interaction potentials. Experimental adsorption isotherms are reproduced by using the Toth equation and it is shown that the ad…

The influence of the temperature on the liquid–liquid equlibria of the mixture limonene + ethanol + H2O

2004

Abstract In this work, experimental liquid–liquid equilibria (LLE) of the limonene + ethanol + water system are presented. The LLE of this system has been measured at 293.15, 303.15, 313.15 and 323.15 K. The equilibrium data presented are correlated using NRTL and UNIQUAC equations. Finally, the reliability of these models is tested by comparison with experimental results.