116 research outputs found
Aggressively Oxidized Ultra-Short Single-Walled Carbon Nanotubes Having Oxidized Sidewalls
Published versio
Identifying key components for a psychological intervention for people with vitiligo - a quantitative and qualitative study in the United Kingdom using web-based questionnaires of people with vitiligo and healthcare professionals
UK Dermatology Clinical Trials Network Themed Research Call
Nanogap structures for molecular nanoelectronics
This study is focused on the realization of nanodevices for nano and molecular electronics, based on molecular interactions in a metal-molecule-metal (M-M-M) structure. In an M-M-M system, the electronic function is a property of the structure and can be characterized through I/V measurements. The contact between the metals and the molecule was obtained by gold nanogaps (with a dimension of less than 10 nm), produced with the electromigration technique. The nanogap fabrication was controlled by a custom hardware and the related software system. The studies were carried out through experiments and simulations of organic molecules, in particular oligothiophenes
Spatially Resolving Spin-split Edge States of Chiral Graphene Nanoribbons
A central question in the field of graphene-related research is how graphene
behaves when it is patterned at the nanometer scale with different edge
geometries. Perhaps the most fundamental shape relevant to this question is the
graphene nanoribbon (GNR), a narrow strip of graphene that can have different
chirality depending on the angle at which it is cut. Such GNRs have been
predicted to exhibit a wide range of behaviour (depending on their chirality
and width) that includes tunable energy gaps and the presence of unique
one-dimensional (1D) edge states with unusual magnetic structure. Most GNRs
explored experimentally up to now have been characterized via electrical
conductivity, leaving the critical relationship between electronic structure
and local atomic geometry unclear (especially at edges). Here we present a
sub-nm-resolved scanning tunnelling microscopy (STM) and spectroscopy (STS)
study of GNRs that allows us to examine how GNR electronic structure depends on
the chirality of atomically well-defined GNR edges. The GNRs used here were
chemically synthesized via carbon nanotube (CNT) unzipping methods that allow
flexible variation of GNR width, length, chirality, and substrate. Our STS
measurements reveal the presence of 1D GNR edge states whose spatial
characteristics closely match theoretical expectations for GNR's of similar
width and chirality. We observe width-dependent splitting in the GNR edge state
energy bands, providing compelling evidence of their magnetic nature. These
results confirm the novel electronic behaviour predicted for GNRs with
atomically clean edges, and thus open the door to a whole new area of
applications exploiting the unique magnetoelectronic properties of chiral GNRs
Biocatalytic Synthesis of Polymers of Precisely Defined Structures
The fabrication of functional nanoscale devices requires the construction of complex architectures at length scales characteristic of atoms and molecules. Currently microlithography and micro-machining of macroscopic objects are the preferred methods for construction of small devices, but these methods are limited to the micron scale. An intriguing approach to nanoscale fabrication involves the association of individual molecular components into the desired architectures by supramolecular assembly. This process requires the precise specification of intermolecular interactions, which in turn requires precise control of molecular structure
Field-induced p-n transition in yttria-stabilized zirconia
Oxide ion conducting yttria-stabilised zirconia ceramics show the onset of electronic conduction under a small bias voltage. Compositions with a high yttria content undergo a transition from p-type to n-type behavior at voltages in the range 2.4 to 10 V, which also depends on oxygen partial pressure. Surface reactions have a direct influence on bulk electronic conductivities, with possible implications for voltage-induced flash phenomena and resistive switching
Charge Transport in DNA-Based Devices
Charge migration along DNA molecules has attracted scientific interest for
over half a century. Reports on possible high rates of charge transfer between
donor and acceptor through the DNA, obtained in the last decade from solution
chemistry experiments on large numbers of molecules, triggered a series of
direct electrical transport measurements through DNA single molecules, bundles
and networks. These measurements are reviewed and presented here. From these
experiments we conclude that electrical transport is feasible in short DNA
molecules, in bundles and networks, but blocked in long single molecules that
are attached to surfaces. The experimental background is complemented by an
account of the theoretical/computational schemes that are applied to study the
electronic and transport properties of DNA-based nanowires. Examples of
selected applications are given, to show the capabilities and limits of current
theoretical approaches to accurately describe the wires, interpret the
transport measurements, and predict suitable strategies to enhance the
conductivity of DNA nanostructures.Comment: A single pdf file of 52 pages, containing the text and 23 figures.
Review about direct measurements of DNA conductivity and related theoretical
studies. For higher-resolution figures contact the authors or retrieve the
original publications cited in the caption
Identification of a Novel Calotropis procera Protein That Can Suppress Tumor Growth in Breast Cancer through the Suppression of NF-κB Pathway
10.1371/journal.pone.0048514PLoS ONE712
Adaptations to Submarine Hydrothermal Environments Exemplified by the Genome of Nautilia profundicola
Submarine hydrothermal vents are model systems for the Archaean Earth environment, and some sites maintain conditions that may have favored the formation and evolution of cellular life. Vents are typified by rapid fluctuations in temperature and redox potential that impose a strong selective pressure on resident microbial communities. Nautilia profundicola strain Am-H is a moderately thermophilic, deeply-branching Epsilonproteobacterium found free-living at hydrothermal vents and is a member of the microbial mass on the dorsal surface of vent polychaete, Alvinella pompejana. Analysis of the 1.7-Mbp genome of N. profundicola uncovered adaptations to the vent environment—some unique and some shared with other Epsilonproteobacterial genomes. The major findings included: (1) a diverse suite of hydrogenases coupled to a relatively simple electron transport chain, (2) numerous stress response systems, (3) a novel predicted nitrate assimilation pathway with hydroxylamine as a key intermediate, and (4) a gene (rgy) encoding the hallmark protein for hyperthermophilic growth, reverse gyrase. Additional experiments indicated that expression of rgy in strain Am-H was induced over 100-fold with a 20°C increase above the optimal growth temperature of this bacterium and that closely related rgy genes are present and expressed in bacterial communities residing in geographically distinct thermophilic environments. N. profundicola, therefore, is a model Epsilonproteobacterium that contains all the genes necessary for life in the extreme conditions widely believed to reflect those in the Archaean biosphere—anaerobic, sulfur, H2- and CO2-rich, with fluctuating redox potentials and temperatures. In addition, reverse gyrase appears to be an important and common adaptation for mesophiles and moderate thermophiles that inhabit ecological niches characterized by rapid and frequent temperature fluctuations and, as such, can no longer be considered a unique feature of hyperthermophiles
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