984 research outputs found
Sustainable Stationery
Many inks used for printmaking contain harmful chemicals. Not only for us, but for the environment. Foliage has designed a system to reduce our carbon footprint. From start to finish, our products are designed by nature, for you. As an ink supplier, Foliage is designed to inspire print makers to produce their work in a more sustainable approach by addressing the selection and use of ink and paper. Our company follows these principles: Inspiration, Education, Safety, Sense of Community & to Love the World.
This research distinction thesis explores the process and materials to make natural inks. It also evaluates the efficiency to convert to sustainable materials.No embargoAcademic Major: Visual Communication Desig
Lane reduction in driven 2d-colloidal systems through microchannels
The transport behavior of a system of gravitationally driven colloidal
particles is investigated. The particle interactions are determined by the
superparamagnetic behavior of the particles. They can thus be arranged in a
crystalline order by application of an external magnetic field. Therefore the
motion of the particles through a narrow channel occurs in well-defined lanes.
The arrangement of the particles is perturbed by diffusion and the motion
induced by gravity. Due to these combined influences a density gradient forms
along the direction of motion of the particles. A reconfiguration of the
crystal is observed leading to a reduction of the number of lanes. In the
course of the lane reduction transition a local melting of the
quasi-crystalline phase to a disordered phase and a subsequent crystallization
along the motion of the particles is observed. This transition is characterized
experimentally and using Brownian dynamics (BD) simulations.Comment: 4 pages, 4 figure
A nanomechanical resonator shuttling single electrons at radio frequencies
We observe transport of electrons through a metallic island on the tip of a
nanomechanical pendulum. The resulting tunneling current shows distinct
features corresponding to the discrete mechanical eigenfrequencies of the
pendulum. We report on measurements covering the temperature range from 300 K
down to 4.2 K. We explain the I-V curve, which differs from previous
theoretical predictions, with model calculations based on a Master equation
approach.Comment: 5 pages, 4 jpeg-figure
Influence of nano-mechanical properties on single electron tunneling: A vibrating Single-Electron Transistor
We describe single electron tunneling through molecular structures under the
influence of nano-mechanical excitations. We develop a full quantum mechanical
model, which includes charging effects and dissipation, and apply it to the
vibrating C single electron transistor experiment by Park {\em et al.}
{[Nature {\bf 407}, 57 (2000)].} We find good agreement and argue vibrations to
be essential to molecular electronic systems. We propose a mechanism to realize
negative differential conductance using local bosonic excitations.Comment: 7 pages, 6 figure
Mechanical Cooper pair transportation as a source of long distance superconducting phase coherence
Transportation of Cooper-pairs by a movable single Cooper-pair-box placed
between two remote superconductors is shown to establish coherent coupling
between them. This coupling is due to entanglement of the movable box with the
leads and is manifested in the supression of quantum fluctuations of the
relative phase of the order parameters of the leads. It can be probed by
attaching a high resistance Josephson junction between the leads and measuring
the current through this junction. The current is suppressed with increasing
temperature.Comment: 4 pages, 4 figures, RevTeX; Updated version, typos correcte
Electromechanics of charge shuttling in dissipative nanostructures
We investigate the current-voltage (IV) characteristics of a model
single-electron transistor where mechanical motion, subject to strong
dissipation, of a small metallic grain is possible. The system is studied both
by using Monte Carlo simulations and by using an analytical approach. We show
that electromechanical coupling results in a highly nonlinear IV-curve. For
voltages above the Coulomb blockade threshold, two distinct regimes of charge
transfer occur: At low voltages the system behave as a static asymmetric double
junction and tunneling is the dominating charge transfer mechanism. At higher
voltages an abrupt transition to a new shuttle regime appears, where the grain
performs an oscillatory motion back and forth between the leads. In this regime
the current is mainly mediated by charges that are carried on the grain as it
moves from one lead to the other.Comment: 8 pages, 10 figures, final version to be published in PR
Limiting Current Density of Oxygen Reduction under Ultrathin Electrolyte Layers: From the Micrometer Range to Monolayers
The oxygen reduction reaction (ORR) under ultrathin electrolyte layers is a key reaction in many processes, from atmospheric corrosion to energy conversion in fuel cells. However, the ORR current under ultrathin electrolyte layers is difficult to measure using conventional electrochemical methods. Hence, reliable data are scarce for the micrometer range and totally missing for the sub-micrometer range of the electrolyte layer thickness. Here, we report a novel hydrogen-permeation-based approach to measure the ORR current underneath thin and ultrathin electrolyte layers. By using a Kelvin-probe-based measurement of the potential, which results from dynamic equilibrium of oxygen reduction and hydrogen oxidation, and the corresponding hydrogen charging current density, the full current-potential relationship can be constructed. The results shed a new light on the nature of the limiting current density of ORR underneath ultrathin layers of electrolyte. © 2021 The Authors. ChemElectroChem published by Wiley-VCH Gmb
Swapping and entangling hyperfine coupled nuclear spin baths
We numerically study the hyperfine induced nuclear spin dynamics in a system
of two coupled quantum dots in zero magnetic field. Each of the electron spins
is considered to interact with an individual bath of nuclear spins via
homogeneous coupling constants (all coupling coefficients being equal). In
order to lower the dimension of the problem, the two baths are approximated by
two single long spins. We demonstrate that the hyperfine interaction enables to
utilize the nuclear baths for quantum information purposes. In particular, we
show that it is possible to swap the nuclear ensembles on time scales of
seconds and indicate that it might even be possible to fully entangle them. As
a key result, it turns out that the larger the baths are, the more useful they
become as a resource of quantum information. Interestingly, the nuclear spin
dynamics strongly benefits from combining two quantum dots of different
geometry to a double dot set up.Comment: 6 pages, 7 figure
Bioactive Materials
Bioactive substantially silica-free glass material with a hydroxyapatite layer thereon is described, as well as methods for producing hydroxyapatite on a borate glass
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