Self-supported polypyrrole/polyvinylsulfate films: electrochemical synthesis, characterization, and sensing properties of their redox reactions

Thick films of polypyrrole/polyvinylsulfate (PPy/PVS) blends were electrogenerated on stainless‐steel electrodes under potentiostatic conditions from aqueous solution. The best electropolymerization potential window was determined by cyclic voltammetry. After removing the film from the back metal, self‐supported electrodes were obtained. Voltammetric, coulovoltammetric, and chronoamperometric responses from a LiClO4 aqueous solution indicated the formation of an energetically stable structure beyond a reduction threshold of the material. Its subsequent oxidation required higher anodic voltammetric overpotentials or longer chronoamperometric oxidation times. This structure was attributed to the formation of lamellar or vacuolar structures. X‐ray photoelectron spectroscopy analysis of the films under different oxidations states revealed that the electrochemical reactions drive the reversible exchange of cations between the film and the electrolyte. The electrical energy and the charge consumed by the reversible reaction of the film under voltammetric conditions between the constant potential limits are a function of the potential scan rate, that is, they sense the working electrochemical conditions.This project was supported by the Marie‐Sklodowska‐Curie Innovative Training Network MICACT‐H2020‐MSCA‐ITN‐2014 and by the Séneca Foundation project 19253/PI/14

Coastal Ocean Forecasting: system integration and evaluation

Kourafalou, V.H. et al.ecent advances in Coastal Ocean Forecasting Systems (COFS) are discussed. Emphasis is given to the integration of the observational and modeling components, each developed in the context of monitoring and forecasting in the coastal seas. These integrated systems must be linked to larger scale systems toward seamless data sets, nowcasts and forecasts (from the global ocean, through the continental shelf and to the nearshore regions). Emerging capabilities include: methods to optimize coastal/regional observational networks; and probabilistic approaches to address both science and applications related to COFS. International collaboration is essential to exchange best practices, achieve common frameworks and establish standards.V. Kourafalou acknowledges support from NOAA (NA13OAR4830224 and NA11NOS4780045). M. Herzfeld is thankful to the eReefs marine modeling team and partners (CSIRO: Commonwealth Industrial and Scientific Research Organization; SIEF: Science and Industry Endowment Fund; AIMS: Australian Institute of Marine Science). The system CGOFS_ECS (material contributed by X. Zhu) is supported by the National Natural Science Foundation of China (contract #41222038). E. V. Stanev acknowledges the input from COSYNA, which is supported by the Helmholtz Association of German Research CentersPeer Reviewe

Modelling the long term effect of changes in fire frequency on the total area burnt

Wildfires are one of the major problems in Mediterranean countries, and much effort is done by the governments to dissuade people from starting fires. Public campaigns often promote the idea that the more ignitions the larger the surface burnt will be. This reasoning is, however, not so straightforward. This paper addresses the question of how fire frequency relates to the total area burnt by using a model of fire regime that includes variables such as the number of ignitions, fire fighting capacity, fuel accumulation rates, existence of prescribed burning and meteorological variability. This question was addressed by performing three experimental simulations: effect of the number of potential ignitions, the combined effect of the number of ignitions and extinction capacity, and the non random spatial pattern of fire ignitions. Results showed that a larger number ignitions did not have a great effect on the total area burnt but had an effect in the occurrence of large fires, independently of the extinction capacity and of the spatial distribution of ignitions. An explanation for these findings is provided and management implications of these results are briefly discussed

Theoretical study of Ga-based nanowires and the interaction of Ga with single-wall carbon nanotubes

Gallium displays physical properties which can make it a potential element to produce metallic nanowires and high-conducting interconnects in nanoelectronics. Using first-principles pseudopotential plane method we showed that Ga can form stable metallic linear and zigzag monatomic chain structures. The interaction between individual Ga atom and single-wall carbon nanotube (SWNT) leads to a chemisorption bond involving charge transfer. Doping of SWNT with Ga atom gives rise to donor states. Owing to a significant interaction between individual Ga atom and SWNT, continuous Ga coverage of the tube can be achieved. Ga nanowires produced by the coating of carbon nanotube templates are found to be stable and high conducting.Comment: 8 pages, 8 figure

Phonon and plasmon excitation in inelastic electron tunneling spectroscopy of graphite

The inelastic electron tunneling spectrum (IETS)of highly oriented pyrolitic graphite (HOPG) has been measured with scanning tunneling spectroscopy (STS) at 6K. The observed spectral features are in very good agreement with the vibrational density of states (vDOS) of graphite calculated from first principles. We discuss the enhancement of certain phonon modes by phonon-assisted tunneling in STS based on the restrictions imposed by the electronic structure of graphite. We also demonstrate for the first time the local excitation of surface-plasmons in IETS which are detected at an energy of 40 meV.Comment: PRB rapid communication, submitte

Fascicular Topography of the Human Median Nerve for Neuroprosthetic Surgery

One of the most sought-after applications of neuroengineering is the communication between the arm and an artificial prosthetic device for the replacement of an amputated hand or the treatment of peripheral nerve injuries. For that, an electrode is placed around or inside the median nerve to serve as interface for recording and stimulation of nerve signals coming from the fascicles that innervate the muscles responsible for hand movements. Due to the lack of a standard procedure, the electrode implantation by the surgeon is strongly based on intuition, which may result in poor performance of the neuroprosthesis because of the suboptimal location of the neural interface. To provide morphological data that can aid the neuroprosthetic surgeon with this procedure, we investigated the fascicular topography of the human median nerve along the forearm and upper arm. We first performed a description of the fascicular content and branching patterns along the length of the arm. Next we built a 3D reconstruction of the median nerve so we could analyze the fascicle morphological features in relation to the arm level. Finally, we characterized the motor content of the median nerve fascicles in the upper arm. Collectively, these results indicate that fascicular organization occurs in a short segment distal to the epicondyles and remains unaltered until the muscular branches leave the main trunk. Based on our results, overall recommendations based on electrode type and implant location can be drawn to help and aid the neuroprosthetic procedure. Invasive interfaces would be more convenient for the upper arm and the most proximal third of the forearm. Epineural electrodes seem to be most suitable for the forearm segment after fascicles have been divided from the main trunk

Wall Drying in Hot and Humid Climates

Moisture and subsequent mold problems in buildings are a serious and increasing concern for the building industry. Moisture intrusion in buildings is especially pertinent in hot and humid climates because the climate conditions provide only limited drying potential while at the same time providing a high potential for mold growth. To reduce moisture accumulation in wall systems, it is important to design wall systems that not only reduce moisture intrusion, but also allow drying. Yet often a wall's ability to dry is not considered during the design or material selection process. No cladding system or installation is perfect, therefore wall systems should be designed with the assumption that some moisture will enter and then consider the effects and how that moisture can be managed. This paper explores the mechanisms of wall drying, focusing on how wood frame walls dry in hot, humid climates. This paper describes laboratory drying studies of conventional sheathing / weather resistive barrier systems under a variety of temperature and humidity conditions including those typical of hot humid climates. Additionally, a computer simulation is used to examine the implications of drying to the interior, drying to the exterior, or drying to both the interior and exterior. Traditional rules of thumb for construction in hot humid climates rely on drying to the interior, but we will show that walls can and do dry to the exterior in these climates

Theoretical Study of One-dimensional Chains of Metal Atoms in Nanotubes

Using first-principles total-energy pseudopotential calculations, we have studied the properties of chains of potassium and aluminum in nanotubes. For BN tubes, there is little interaction between the metal chains and the tubes, and the conductivity of these tubes is through carriers located at the inner part of the tube. In contrast, for small radius carbon nanotubes, there are two types of interactions: charge-transfer (dominant for alkali atoms) leading to strong ionic cohesion, and hybridization (for multivalent metal atoms) resulting in a smaller cohesion. For Al-atomic chains in carbon tubes, we show that both effects contribute. New electronic properties related to these confined atomic chains of metal are analyzed.Comment: 12 pages + 3 figure