44 research outputs found
A Review of Neurogenic Stunned Myocardium.
Neurologic stunned myocardium (NSM) is a phenomenon where neurologic events give rise to cardiac abnormalities. Neurologic events like stroke and seizures cause sympathetic storm and autonomic dysregulation that result in myocardial injury. The clinical presentation can involve troponin elevation, left ventricular dysfunction, and ECG changes. These findings are similar to Takotsubo cardiomyopathy and acute coronary syndrome. It is difficult to distinguish NSM from acute coronary syndrome based on clinical presentation alone. Because of this difficulty, a patient with NSM who is at high risk for coronary heart disease may undergo cardiac catheterization to rule out coronary artery disease. The objective of this review of literature is to enhance physician\u27s awareness of NSM and its features to help tailor management according to the patient\u27s clinical profile
Actuators based on intrinsic conductive polymers/carbon nanoparticles nanocompositesElectroactive Polymer Actuators and Devices (EAPAD) 2013
New polyaniline (PANi) synthesis was performed starting from non-toxic N-phenil-p-phenylenediamine (aniline dimer) using reverse addition of monomer to oxidizing agent, the synthesis allows to produce highly soluble PANi. Several types of doped PANi were prepared to be used on electromechanical active actuators. Different techniques were used to include carbon nanoparticles such as carbon nanotubes and graphene. Bimorph solid state ionic actuators were prepared with these novel nanocomposites using a variety of supporting polymer
Multi-walled carbon nanotubes plastic actuator
Carbon nanotubes (CNTs) have electrical and mechanical properties that make them highly attractive for actuators. They have the ability to deform elastically by several percent, thus storing very large amounts of energy, thanks to their crystalline nature and to their morphology. A bimorph actuator composed of single-walled carbon nanotubes (SWCNTs), polyvinylidene difluoride (PVdF) and the ionic liquid (IL) 1-butyl 3-methylimidazolium tetrafluoroborate [BMIM][BF4] with a polymer-supported internal IL electrolyte was previously demonstrated by Aida and coworkers. While several experiments were carried out using SWCNTs, PVdF and a number of ILs, the use of multi-walled carbon nanotubes (MWCNTs) instead of SWCNTs is, to our knowledge, a new result that will be presented here. Electrochemical characterizations by cyclic voltammetry (CV), and actuation tests performed applying a square wave of 4 V peak-to-peak at frequencies between 0.3 and 2 Hz are reported and discussed. \ua9 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Improvement of polypyrrole and carbon nanotube co-deposition techniques for high charge-transfer electrodes
Both carbon nanotubes (CNTs) and polypyrrole (PPy) have been investigated as materials for manufacturing high charge transfer electrodes due to their outstanding performances. The combination of their complementary properties via an electro chemical co-deposition route has been already shown to achieve interesting results. In this work, PPy and chemically functionalized multi walled CNTs (COOH-MWCNT) were potentiostatically, galvanostatically and potentiodynamically electrodeposited from an aqueous solution to form a nanocomposite on the surface of a variety of metal electrodes. A study of the influence of experimental parameters such as temperature, current, and growth rate in the different electro-deposition methods was performed. The electronic and electro-chemical properties of the nanocomposite films have been studied by cyclic voltammetry and electrochemical impedance spectroscopy, while a morphological study has been performed via scanning electron microscopy. A comparison between the different techniques and guidelines for best results will be reported. \ua9 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Performance improvement in bucky gel actuators by chemical modifications of carbon nanotubes
Single walled carbon nanotubes functionalized with an aromatic diamine have been successfully used to prepare bucky gel layers by mixing with an imidazolium based ionic liquid, allowing to build bimorph actuators that significantly outperform those prepared by using the pristine or oxidized carbon nanotubes. The carbon nanotube gravimetric specific capacitance doubles, the actuator maximum operating frequency becomes five times higher and for same injected charge the strain reaches a fourfold increase. The origin of such dramatic effects is most probably due to an enhanced binding between the carbon nanotubes induced by their chemical modification. \ua9 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Strategies for tuning carbon nanotube plastic actuator performance through material hybridization and the thickness effect: A proof of principle
Bucky gel actuators are a kind of electrochemical actuator based on carbon nanotubes having interesting features. They are intrinsically safe because are operated at low voltage, they are lightweight and they are able to work in air without any liquid electrolyte. One key aspect that needs improvement is their actuation speed which is strongly dependent on their ability of being efficiently charged and discharged without exceeding the electrochemical stability window of the electrolyte. By proper material processing, we have successfully addressed this issue. An actuator thickness reduction to one third of the original size results in a one order of magnitude increase of both the strain at higher frequencies and the maximum operating frequency. The strain improvement at high frequency due to thinning has the sole drawback of decreasing the maximum strain that can be achieved in quasi-static conditions. We addressed this second issue by using a proper combination of actuating materials. Oxidative polymerization of pyrrole was carried out directly on preformed bucky gel slurry in order to combine the remarkable properties of ionic actuators based on carbon nanotubes and polypyrrole. A small amount of polypyrrole is sufficient to dramatically improve the overall actuator performance, and by using this hybrid it is possible to obtain thin actuators (about 0.1 mm) with superior performance even at lower frequencies. \ua9 2013 IOP Publishing Ltd