State of the art review: the data revolution in critical care

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2015 and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/annualupdate2015. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901

Thermal breakdown of ZnTe nanowires

As the applications for inorganic nanowires continuously grow, studies on the stability of these structures under high electrical/thermal stress conditions are needed. ZnTe nanowires are grown by the vapor-liquid-solid technique and their breakdown under Joule heating is studied through in situ monitoring in a transmission electron microscope (TEM). The experimental setup, consisting of a scanning tunneling microscope (STM) and a movable piezotube inside the TEM, allows the manipulation of a single nanowire. A voltage applied to the STM tip in contact with a ZnTe nanowire leads to the breakdown of the nanowire into Zn and Te particles or balls which is observed in real time. These balls grow by Ostwald ripening, rendering the surface morphology of the ZnTe nanowire progressively rough. Diffraction patterns along the stem of the wire after the partial breakdown showed substantially smaller lattice spacing compared to 0.35 nm for pristine ZnTe nanowires.X111013sciescopu

In situ Observation of Morphological Change in CdTe Nano- and Submicron Wires

We report growth and characterization of CdTe wires 30-400 nm in diameter by the vapor-liquid-solid technique. Individual nanowires were placed on a movable piezotube, which allowed three-dimensional motion toward a scanning tunneling microscope (STM). A bias was applied to the STM tip in contact with the nanowire, and the morphological changes due to Joule heating were observed in situ using a transmission electron microscope (TEM) in real time. For thick CdTe wires (d > similar to 150 nm), the process results in the growth of superfine nanowires (SFNWs) of 2-4 nm diameter on the surface of the wire. Smaller diameter nanowires, in contrast, disintegrate under the applied bias before the complete evolution of SFNWs on the surface.X11910sciescopu

A computational and experimental investigation of the mechanical properties of single ZnTe nanowires

One-dimensional nanostructures such as ZnTe, CdTe, Bi2Te3 and others have attracted much attention in recent years for their potential in thermoelectric devices among other applications. A better understanding of their mechanical properties is important for the design of devices. A combined experimental and computational approach has been used here to investigate the size effects on the Young's modulus of ZnTe nanowires (NWs). The mechanical properties of individual ZnTe nanowires in a wide diameter range (50-230 nm) were experimentally measured inside a high resolution transmission electron microscope using an atomic force microscope probe with the ability to record in situ continuous force-displacement curves. The in situ observations showed that ZnTe NWs are flexible nanostructures with the ability to withstand relatively high buckling forces without becoming fractured. The Young's modulus is found to be independent of nanowire diameter in the investigated range, in contrast to reported results for ZnO NWs and carbon nanotubes where the modulus increases with a decrease in diameter. Molecular dynamics simulations performed for nanowires with diameters less than 20 nm show limited size dependence for diameters smaller than 5 nm. The surface atoms present lower Young's modulus according to the simulations and the limited size dependency of the cylindrical ZnTe NWs is attributed to the short range covalent interactions.open111515sciescopu

New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (in-situ STM-TEM). As suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending