133,727 research outputs found
Carbon dioxide concentrator
Passed exhaled air through electrochemical cell containing alkali metal carbonate aqueous solution, and utilizes platinized electrodes causing reaction of oxygen at cathode with water in electrolyte, producing hydroxyl ions which react with carbon dioxide to form carbonate ions
Technique for producing bipolar and MOS field effect transistors on a single chip
Several cycles of photoetching, dopant deposition, and drive-in produce selectively-doped regions and semiconductor junctions within a single chip
The role of local structure in dynamical arrest
Amorphous solids, or glasses, are distinguished from crystalline solids by
their lack of long-range structural order. At the level of two-body structural
correlations, glassformers show no qualitative change upon vitrifying from a
supercooled liquid. Nonetheless the dynamical properties of a glass are so much
slower that it appears to take on the properties of a solid. While many
theories of the glass transition focus on dynamical quantities, a solid's
resistance to flow is often viewed as a consequence of its structure. Here we
address the viewpoint that this remains the case for a glass. Recent
developments using higher-order measures show a clear emergence of structure
upon dynamical arrest in a variety of glass formers and offer the tantalising
hope of a structural mechanism for arrest. However a rigorous fundamental
identification of such a causal link between structure and arrest remains
elusive. We undertake a critical survey of this work in experiments, computer
simulation and theory and discuss what might strengthen the link between
structure and dynamical arrest. We move on to highlight the relationship
between crystallisation and glass-forming ability made possible by this deeper
understanding of the structure of the liquid state, and emphasize the potential
to design materials with optimal glassforming and crystallisation ability, for
applications such as phase-change memory. We then consider aspects of the
phenomenology of glassy systems where structural measures have yet to make a
large impact, such as polyamorphism (the existence of multiple liquid states),
aging (the time-evolution of non-equilibrium materials below their glass
transition) and the response of glassy materials to external fields such as
shear.Comment: 70 page
Quark Condensates: Flavour Dependence
We determine the q-bar q condensate for quark masses from zero up to that of
the strange quark within a phenomenologically successful modelling of continuum
QCD by solving the quark Schwinger-Dyson equation. The existence of multiple
solutions to this equation is the key to an accurate and reliable extraction of
this condensate using the operator product expansion. We explain why
alternative definitions fail to give the physical condensate.Comment: 9 pages, 7 figures, uses appolb.cls, LaTeX. Talk presented by R.
Williams at the EURIDICE Final Meeting, August 24-27th, 2006, Kazimierz,
Polan
Extended plasticity in commercial-purity zinc
90% rolling-reduction of annealed commercial-purity zinc sheet
(grain size 100 - 150 μ) results in the fragmentation of the large grains
into, finally, stable micro-grains, 1 - 211 in diameter. The stability of
the micro-grains is due to the presence of soluble and insoluble impurities
which prevent recrystallization.
This micro-grain material is strain-rate sensitive, and elongations of
200% have been obtained at room temperature.
Although this as-rolled, 90% reduction zinc sheet is not super-plastic
according to the current definition, its behaviour has led to the coining of
the phase 'extended plasticity'.
Evidence of grain-boundary sliding is found on examination of the surface
by scanning electron microscopy, while the examination of thin foils and
activation energy measurements support the dynamic softening (recovery) theory;
thus, both these mechanisms must be operating, to a greater or less extent,
to confer on this material the observe mechanical behaviour.
It is finally concluded that it is dangerous to draw conclusions regarding
the mechanism of plastic deformation from surface observations alone
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