Patterned superhydrophobic paper for microfluidic devices obtained by writing and printing

Published online: 26 July 2013This work outlines inexpensive patterning methodologies to create open-air microfluidic paperbased devices. A phase-separation methodology was used to obtain biomimetic superhydrophobic paper, hierarchically composed by micro and nano topographies. Writing and printing are simple actions that can be used to pattern flat superhydrophobic paper with more wettable channels. In particular, inkjet printing permits controlling the wettability of the surface by changing the darkness of the printed regions. The difference between capillary forces provides the possibility to control and drive liquid flows through the open path lines, just by titling the piece of paper. Additionally, maintaining a continuous flow, it is possible to direct the liquid at different volumetric rates in a horizontal position along non-linear channel paths printed/written over the surface

CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their Structural and Magnetic Properties

This work reports on the synthesis of CrO2 thin films by atmospheric pressure CVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films containing highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates. Films display a sharp magnetic transition at 375 K and a saturation magnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2 Bohr magnetons per f.u. for the CrO2. Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics.Comment: 5 pages, 6 figure

MODELING OF PARTIAL OXIDATION OF METHANE IN A MEMBRANE REACTOR

Partial oxidation of methane is one of the most important chemical processes for the production of syngas. In recent years, the abundant availability of natural gas and the increasing demand of hydrogen have led to high interest to further develop this process increasing the yield of syngas. In this work the partial oxidation of methane was studied from a modeling point of view in a membrane reactor and in a conventional reactor. A mathematical model of a membrane reactor used for partial oxidation of methane, assuming steadystate conditions, was developed to simulate and compare the maximum yields and operating conditions in the reactor with that in a conventional reactor. Simulation results show that different parameters affect methane conversion and H /CO ratio, such as temperature, operating conditions, and membrane 2 parameters such as membrane permeance. In a membrane reactor an increase in the operating pressure corresponds to an increase in methane conversion, since allows for a greater partial pressure gradient between the reaction and permeate zone, thus contributing to shift the equilibrium towards the products. As such, the membrane reactors are a good alternative to produce syngas especially for GTL processes. Operating conditions can be set to control the H2/CO ratio to a desired value, and high conversions at mild temperatures can be achieved reducing capital and operational costs

EQUIVALENT MODELS FOR PHOTOVOLTAIC CELL – A REVIEW

Over the years, the contribution of photovoltaic energy to an eco-friendly world is continually increasing. Photovoltaic (PV) cells are commonly modelled as circuits, so finding the appropriate circuit model parameters of PV cells is crucial for performance evaluation, control, efficiency computations and maximum power point tracking of solar PV systems. The problem of finding circuit model of solar PV cells is referred to as “PV cell equivalent model problem”. In this paper, the existing research works on PV cell model parameter estimation problem are classified according to error quali-quantitative analysis, number of parameters, translation equations and PV technology. The existent models were discussed pointing out its different levels of approximation. A qualitative comparative ranking was made and four models were found to be the best ones for simulating PV cells. Besides, based on the conducted review, some recommendations for future research are provided