Electrical behaviour, characteristics and properties of anodic aluminium oxide films coloured by nickel electrodeposition

Porous anodic films on 1050 aluminium substrate were coloured by AC electrodeposition of nickel. Several experiments were performed at different deposition voltages and nickel concentrations in the electrolyte in order to correlate the applied electrical power to the electrical behaviour, as well as the characteristics and properties of the coatings. The content of nickel inside the coatings reached 1.67 g/m2, depending on the experimental conditions. According to the applied AC voltage in comparison with the threshold voltage Ut, the coating either acted only as a capacitor when U\Ut and, when U[Ut, the behaviour during the anodic and cathodic parts of the power sine wave was different. In particular, due to the semi-conducting characteristics of the barrier layer, additional oxidation of the aluminium substrate occurred during the anodic part of the electrical signal, whilst metal deposition (and solvent reduction) occurred during the cathodic part; these mechanisms correspond to the blocked and pass directions of the barrier layer/electrolyte junction, respectively

Copper Selenide Nanosnakes: Bovine Serum Albumin-Assisted Room Temperature Controllable Synthesis and Characterization

Herein we firstly reported a simple, environment-friendly, controllable synthetic method of CuSe nanosnakes at room temperature using copper salts and sodium selenosulfate as the reactants, and bovine serum albumin (BSA) as foaming agent. As the amounts of selenide ions (Se2−) released from Na2SeSO3 in the solution increased, the cubic and snake-like CuSe nanostructures were formed gradually, the cubic nanostructures were captured by the CuSe nanosnakes, the CuSe nanosnakes grew wider and longer as the reaction time increased. Finally, the cubic CuSe nanostructures were completely replaced by BSA–CuSe nanosnakes. The prepared BSA–CuSe nanosnakes exhibited enhanced biocompatibility than the CuSe nanocrystals, which highly suggest that as-prepared BSA–CuSe nanosnakes have great potentials in applications such as biomedical engineering

Structural and Electrical Characterization of Bi2Se3 Nanostructures Grown by Metalorganic Chemical Vapor Deposition

We characterize nanostructures of Bi2Se3 that are grown via metalorganic chemical vapor deposition using the precursors diethyl selenium and trimethyl bismuth. By adjusting growth parameters, we obtain either single-crystalline ribbons up to 10 microns long or thin micron-sized platelets. Four-terminal resistance measurements yield a sample resistivity of 4 mOhm-cm. We observe weak anti-localization and extract a phase coherence length l_phi = 178 nm and spin-orbit length l_so = 93 nm at T = 0.29 K. Our results are consistent with previous measurements on exfoliated samples and samples grown via physical vapor deposition.Comment: Related papers at http://pettagroup.princeton.ed

Interfacial Chemistry in Al/CuO Reactive Nanomaterial and Its Role in Exothermic Reaction.

Interface layers between reactive and energetic materials in nanolaminates or nanoenergetic materials are believed to play a crucial role in the properties of nanoenergetic systems. Typically, in the case of Metastable Interstitial Composite nanolaminates, the interface layer between the metal and oxide controls the onset reaction temperature, reaction kinetics, and stability at low temperature. So far, the formation of these interfacial layers is not well understood for lack of in situ characterization, leading to a poor control of important properties. We have combined in situ infrared spectroscopy and ex situ X-ray photoelectron spectroscopy, differential scanning calorimetry, and high resolution transmission electron microscopy, in conjunction with firstprinciples calculations to identify the stable configurations that can occur at the interface and determine the kinetic barriers for their formation. We find that (i) an interface layer formed during physical deposition of aluminum is composed of a mixture of Cu, O, and Al through Al penetration into CuO and constitutes a poor diffusion barrier (i.e., with spurious exothermic reactions at lower temperature), and in contrast, (ii) atomic layer deposition (ALD) of alumina layers using trimethylaluminum (TMA)produces a conformal coating that effectively prevents Al diffusion even for ultrathin layer thicknesses (∼0.5 nm), resulting in better stability at low temperature and reduced reactivity. Importantly, the initial reaction of TMA with CuO leads to the extraction of oxygen from CuO to form an amorphous interfacial layer that is an important component for superior protection properties of the interface and is responsible for the high system stability. Thus, while Al e-beam evaporation and ALD growth of an alumina layer on CuO both lead to CuO reduction, the mechanism for oxygen removal is different, directly affecting the resistance to Al diffusion. This work reveals that it is the nature of the monolayer interface between CuO and alumina/Al rather than the thickness of the alumina layer that controls the kinetics of Al diffusion, underscoring the importance of the chemical bonding at the interface in these energetic materials

Alumina Template-Dependant Growth of Cobalt Nanowire Arrays

Different electrochemical regimes and porous alumina were applied for template synthesis of cobalt nanowire (nw) arrays, revealing several peculiar cases. In contrast to quite uniform filling of sulfuric acid alumina templates by alternating current deposition, nonuniform growth of the Co nw tufts and mushrooms was obtained for the case of oxalic acid templates. We showed herein for the first time that such configurations arise from the spontaneous growth of cobalt nw groups evolving from the cobalt balls at the Al/alumina interface. Nevertheless, the uniform growth of densely packed cobalt nw arrays, up to tens of micrometers in length, was obtained via long-term direct current galvanostatic deposition at low current density using oxalic acid templates one-side coated by conducting layer. The unique point of this regime is the formation of hexagonal lattice Co nws with a preferred (100) growth direction

Simulation with Geant4 of a novel position detector based on nanotechnologies

The application of nanotechnologies for a novel type of position particle detector is the aim of NanoChanT project. Titanium dioxide (TiO2) nanowires are grown in an highly ordered array of parallel nanochannels in an alumina template. The template is obtained from the controlled anodization of an aluminum foil that produces regular pores. Depending on anodization conditions, the diameter of the pores ranges from 20 to 200 nm with 40 to 500 nm pitch. After doping, a pn junction can be obtained from each of the TiO2 nanowire. The junction is inversely polarized and is sensitive to the passage of charged particles. The charge produced in groups of nanowires is collected by metal pixels and readout by CMOS electronics. GEANT4 has been used for the simulation of the interaction of ionizing particles with the detector. The simulation at the nanoscale level is of fundamental importance in the design of the geometry of the device, in order to choose the best compromise between the smallest detectable charge produced in a readout channel and the maximum achievable spatial resolution. The current design and status of the detector and the considerations driven by the simulation with GEANT4 are presented

Simulation based teamwork training for emergency department staff: does it improve clinical team performance when added to an existing didactic teamwork curriculum?

Objective: To determine if high fidelity simulation based team training can improve clinical team performance when added to an existing didactic teamwork curriculum. Setting: Level 1 trauma center and academic emergency medicine training program. Participants: Emergency department (ED) staff including nurses, technicians, emergency medicine residents, and attending physicians. Intervention: : ED staff who had recently received didactic training in the Emergency Team Coordination Course (ETCC®) also received an 8 hour intensive experience in an ED simulator in which three scenarios of graduated difficulty were encountered. A comparison group, also ETCC trained, was assigned to work together in the ED for one 8 hour shift. Experimental and comparison teams were observed in the ED before and after the intervention. Design: Single, crossover, prospective, blinded and controlled observational study. Teamwork ratings using previously validated behaviorally anchored rating scales (BARS) were completed by outside trained observers in the ED. Observers were blinded to the identification of the teams. Results: There were no significant differences between experimental and comparison groups at baseline. The experimental team showed a trend towards improvement in the quality of team behavior (p = 0.07); the comparison group showed no change in team behavior during the two observation periods (p = 0.55). Members of the experimental team rated simulation based training as a useful educational method. Conclusion: High fidelity medical simulation appears to be a promising method for enhancing didactic teamwork training. This approach, using a number of patients, is more representative of clinical care and is therefore the proper paradigm in which to perform teamwork training. It is, however, unclear how much simulator based training must augment didactic teamwork training for clinically meaningful differences to become apparent

Simulation with GEANT4 of a novel position detector based on nanotechnologies.

The application of nanotechnologies for a novel type of position particle detector is the aim of NanoChanT project. Titanium dioxide (TiO2) nanowires are grown in an highly ordered array of parallel nanochannels in an alumina template. The template is obtained from the controlled anodization of an aluminum foil that produces regular pores. Depending on anodization conditions, the diameter of the pores ranges from 20 to 200 nm with 40 to 500 nm pitch. After doping, a pn junction can be obtained from each of the TiO2 nanowire. The junction is inversely polarized and is sensitive to the passage of charged particles. The charge produced in groups of nanowires is collected by metal pixels and readout by CMOS electronics. GEANT4 has been used for the simulation of the interaction of ionizing particles with the detector. The simulation at the nanoscale level is of fundamental importance in the design of the geometry of the device, in order to choose the best compromise between the smallest detectable charge produced in a readout channel and the maximum achievable spatial resolution. The current design and status of the detector and the considerations driven by the simulation with GEANT4 are presented