Comparative study of filler influence on polylactide photooxidation

Polylactide (PLA) based nanocomposites of organically modified montmorillonite and micro-talc based micro- composites were prepared with different compositions and were UV-light irradiated under artificial accelerated conditions representative of solar irradiation. The chemical modifications resulting from photo-oxidation were followed by infrared (IR) and ultraviolet (UV)-visible spectroscopies. The infrared analysis of PLA photooxidation shows the formation of a band at 1847 cm-1 due to the formation of anhydrides. The filler addition provokes an increase of anhydride formation rate dependent on filler nature, amount and dispersion degree on the matrix. The main factors that influence oxidation rate are the total extension of polymer/filler interfacial area and the presence of transition metal impurities of clays

Compact Model for Multiple Independent Gates Ambipolar Devices

The model presented is a charge-based model that assures the continuity of the current and the analytical derivability of charges to obtain the parasitic capacitances. It has been conceived to support the multiple independent gates, typical of nano-array structures, where each gate controls the charge in the channel. Charge conservation implies constant current in the different section of the multiple gate nanowire FET, making possible the development of a compact model for an arbitrary number of gates. The model has been used to describe different structures (i.e. number of gates, dimension of the single transistor and ranges of applied voltages) under static conditions and the results have been verified on Silvaco TCAD simulations. The modeling approach and the attained results for some cases of study will be presented and discusse

Estimating a Risky Term Structure of Uruguayan Sovereign Bonds.

Based on a joint three – factor a¢ ne model, we estimate the term structure of interest rates and default spreads for Uruguay using the reduced - form approach developed by Du¢ e and Singleton. We …nd that Uruguayan average term structure was negatively sloped between 1997 and 2003, as indicated by previous empirical evidence for low –quality debtors. Surprisingly, Uruguayan average yield curve was also negatively sloped between 1997 and 2001, when the country’s foreign –currency denominated debt was considered investment grade by the leading rating agencies. We also …nd that the estimated Uruguayan default spread is able to capture the behavior and dynamics of a more traditional country risk benchmark such as the “Uruguayan Bond Index” (UBI), with observations on a single Uruguayan bond. Finally, we …nd that regional, international and local …nancial crises cause parallel shifts in the Uruguayan yield curve, with higher increases in short –term rates, and that the banking and debt crises experienced by the country in 2002 had the biggest e¤ects on the average Uruguayan term structure.default risk; term structure; reduced-form model; default spread

Crystallization kinetics of poly(lactic acid)-talc composites

The crystallization kinetics of Poly(lactic acid) / talc composites were determined over a range of 0 wt.% to 15 wt.% of talc. Talc was found to change the crystallization kinetics. The presence of talc increases the crystallization rate and this increase is related to talc concentration and to crystallization temperature. In order to understand the effect of talc and PLA crystallinity on mechanical properties, dynamic mechanical thermal analyses were performed on Poly(lactic acid) / talc composites before and after an annealing process. It was demonstrated that the presence of crystals improves thermo-mechanical properties but in order to achieve good results at high temperatures the reinforcing effect of a filler such as talc is necessar

ToPoliNano: Nano-magnet Logic Circuits Design and Simulation

Among the emerging technologies Field-Coupled devices like Quantum dot Cellular Automata are particularly interesting. Of all the practical implementations of this principle NanoMagnet Logic shows many important features, such as a very low power consumption and the feasibility with up-to- date technology. However, its working principle, based on the interaction among neighbor cells, is quite different with respect to CMOS devices behavior. Dedicated design and simulation tools for this technology are necessary to further study this technology, but at the moment there are no such tools available in the scientific scenario. We present here ToPoliNano, a software developed as a design and simulation tool for NanoMagnet Logic, that can be easily adapted to many others emerging technologies, particularly to any kind of Field-Coupled devices. ToPoliNano allows to design circuits following a top-down approach similar to the one used in CMOS and to simulate them using a switch model specifically targeted for high complexity circuits. This tool greatly enhances the ability to analyze, explore and improve the design of Field- Coupled circuit

MWNT Surface Self-Assembling in Fire Retardant Polyethylene-Carbon nanotubes nanocomposites

Multiwall carbon nanotubes (MWNT) were melt blended at different concentration with linear low density polyethylene (LLDPE). The nanotubes impart the fire-retardant characteristics to the polymer by formation of a thin protective film of MWNT/carbon char generated on the surface of the nanocomposites. The film formation mechanism is discusse

ToPoliNano: Nanoarchitectures Design Made Real

Many facts about emerging nanotechnologies are yet to be assessed. There are still major concerns, for instance, about maximum achievable device density, or about which architecture is best fit for a specific application. Growing complexity requires taking into account many aspects of technology, application and architecture at the same time. Researchers face problems that are not new per se, but are now subject to very different constraints, that need to be captured by design tools. Among the emerging nanotechnologies, two-dimensional nanowire based arrays represent promising nanostructures, especially for massively parallel computing architectures. Few attempts have been done, aimed at giving the possibility to explore architectural solutions, deriving information from extensive and reliable nanoarray characterization. Moreover, in the nanotechnology arena there is still not a clear winner, so it is important to be able to target different technologies, not to miss the next big thing. We present a tool, ToPoliNano, that enables such a multi-technological characterization in terms of logic behavior, power and timing performance, area and layout constraints, on the basis of specific technological and topological descriptions. This tool can aid the design process, beside providing a comprehensive simulation framework for DC and timing simulations, and detailed power analysis. Design and simulation results will be shown for nanoarray-based circuits. ToPoliNano is the first real design tool that tackles the top down design of a circuit based on emerging technologie