Direction sensitive bending sensors based on multi-wall carbon nanotube/epoxy nanocomposites

In the present work, a direction sensitive bending strain sensor consisting of a single block of epoxy/multi-wall carbon nanotube composite was developed. Moreover, the manufacturing could be realized in a straightforward single-step processing route. The directional sensitivity to bending deformations is related to the change in electrical resistance, which becomes positive or negative, depending on the direction of bending deflection. This effect is achieved by generating a gradient in electrical conductivity throughout the material. The resistance versus strain behaviour of these devices is investigated in detail and related to the microstructure of the nanocomposites.     

Axonal guidance on patterned free-standing nanowire surfaces

We demonstrate high-fidelity guidance of axons using rows of nanowires. The axons are prevented from crossing the rows, making it possible to guide and sort a large number of axons as opposed to when chemical patterns are used. Focal adhesion forms at the nanowires establishing a possible site of information transfer between the surface and the cells. Rows of gallium phosphide (GaP) nanowires were epitaxially grown on GaP(111) substrates in patterns defined by electron beam lithography.     

Electrical properties of self-assembled branched InAs nanowire junctions

We investigate electrical properties of self-assembled branched InAs nanowires. The branched nanowires are catalytically grown using chemical beam epitaxy, and three-terminal nanoelectronic devices are fabricated from the branched nanowires using electron-beam lithography. We demonstrate that, in difference from conventional macroscopic junctions, the fabricated self-assembled nanowire junction devices exhibit tunable nonlinear electrical characteristics and a signature of ballistic electron transport. As an example of applications, we demonstrate that the self-assembled three-terminal nanowire junctions can be used to implement the functions of frequency mixing, multiplication, and phase-difference detection of input electrical signals at room temperature. Our results suggest a wide range of potential applications of branched semiconductor nanostructures in nanoelectronics.     

Direct atomic scale imaging of III-V nanowire surfaces

We have succeeded in direct atomic scale imaging of the exterior surfaces of III-V nanowires by scanning tunneling microscopy (STM). By using atomic hydrogen, we expose the crystalline surfaces of InAs nanowires with regular InP segments in vacuum while retaining the wire morphology. We show images with atomic resolution of the two major types of InAs wurtzite nanowire surface facets and scanning tunneling spectroscopy (STS) data. Ab initio calculations of the lowest energy surface structures and simulated STM images, agree very well with experiments.     

Control of GaP and GaAs nanowire morphology through particle and substrate chemical modification

We demonstrate two very different morphologies for GaP and GaAs nanowires grown by Au-assisted MOVPE on Si(111) substrates: rodlike wires and tapered wires with sharp tips. We show that the morphology is related to the stability of the particles at the wire tips during growth, and we propose that the mechanism of this effect is diffusion of Au away from the tip. Diffusion occurs, leading to tapered wires, only if there is a clean Si surface to act as a reservoir for the Au. Furthermore, the presence of indium in the particles, even at background levels from previous growth runs, inhibits the migration of Au. These results demonstrate a dramatic example of the sensitivity of wire morphology to substrate and particle chemistry, which could provide an important tool to tune nanowire morphology through particle alloying or surface treatment.     

Recombination dynamics of surface-related excitonic states in single ZnO nanowires

With decreasing diameter the influence of surface-related effects becomes increasingly important for an understanding of the optical properties of semiconductor nanowires. We present time integrated and time resolved photoluminescence studies of single zincoxide nanowires with different diameters. We analyze the changes in the optical spectra for wires with different surface-to-volume ratios, present optical spectra of single wires at different excitation densities, and study the time-resolved dynamics of the surface related and donor-bound exciton related emission lines for a single nanowire at low temperatures.     

Antioxidative Dietary Compounds Modulate Gene Expression Associated with Apoptosis,DNA Repair,Inhibition of Cell Proliferation and Migration

Many dietary compounds are known to have health benefits owing to their antioxidative and anti-inflammatory properties. To determine the molecular mechanism of these food-derived compounds, we analyzed their effect on various genes related to cell apoptosis, DNA damage and repair, oxidation and inflammation using in vitro cell culture assays. This review further tests the hypothesis proposed previously that downstream products of COX-2 (cyclooxygenase-2) called electrophilic oxo-derivatives induce antioxidant responsive elements (ARE), which leads to cell proliferation under antioxidative conditions. Our findings support this hypothesis and show that cell proliferation was inhibited when COX-2 was down-regulated by polyphenols and polysaccharides. Flattened macrophage morphology was also observed following the induction of cytokine production by polysaccharides extracted from viili, a traditional Nordic fermented dairy product. Coix lacryma-jobi (coix) polysaccharides were found to reduce mitochondrial membrane potential and induce caspase-3- and 9-mediated apoptosis. In contrast, polyphenols from blueberries were involved in the ultraviolet-activated p53/Gadd45/MDM2 DNA repair system by restoring the cell membrane potential. Inhibition of hypoxia-inducible factor-1 by saponin extracts of ginsenoside (Ginsen) and Gynostemma and inhibition of S100A4 by coix polysaccharides inhibited cancer cell migration and invasion. These observations suggest that antioxidants and changes in cell membrane potential are the major driving forces that transfer signals through the cell membrane into the cytosol and nucleus, triggering gene expression, changes in cell proliferation and the induction of apoptosis or DNA repair.     

Language-independent look-ahead for checking multi-perspective declarative process models

Software and Systems Modeling - Declarative process modelling languages focus on describing a process by restrictions over the behaviour, which must be satisfied throughout the whole process...