7,513 research outputs found
Experimental reduction of simulated lunar glass by carbon and hydrogen and implications for lunar base oxygen production
The most abundant element in lunar rocks and soils is oxygen which makes up approximately 45 percent by weight of the typical lunar samples returned during the Apollo missions. This oxygen is not present as a gas but is tightly bound to other elements in mineral or glass. When people return to the Moon to explore and live, the extraction of this oxygen at a lunar outpost may be a major goal during the early years of operation. Among the most studied processes for oxygen extraction is the reduction of ilmenite by hydrogen gas to form metallic iron, titanium oxide, and oxygen. A related process is proposed which overcomes some of the disadvantages of ilmenite reduction. It is proposed that oxygen can be extracted by direct reduction of native lunar pyroclactic glass using either carbon, carbon monoxide, or hydrogen. In order to evaluate the feasibility of this proposed process a series of experiments on synthetic lunar glass are presented. The results and a discussion of the experiments are presented
Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9
Isotopic surface oxygen exchange and its subsequent diffusion have been measured using secondary ion mass spectrometry in the fast ionic conductor La2Mo2O9. A silver coating was applied to the sample surface to enhance the surface exchange process for dry oxygen. Contrary to previous studies performed using a wet atmosphere, no grain boundary diffusion tail was observed under these optimized dry exchange conditions. The activation energy for oxygen diffusion was found to be 0.66(+/- 0.09) eV at high temperature (>570 degrees C), and 1.25(+/- 0.01)eV at low temperature (<570 degrees C). Time-of-Flight secondary ion mass spectrometry was employed to investigate the correlation between the silver coating and the O-18 concentration on the sample surface. A close correlation between the presence of silver and oxygen incorporation on the surface was observed. (C) 2010 Elsevier B.V. All rights reserved
How water flow, geometry and material properties drive plant movements
Plants are dynamic. They adjust their shape for feeding, defence and reproduction. Such plant movements are critical for their survival. We present selected examples covering a range of movements from single cell to tissue level and over a range of timescales. We focus on reversible turgor-driven shape changes. Recent insights into the mechanisms of stomata, bladderwort, the waterwheel and the Venus flytrap are presented. The underlying physical principles (turgor, osmosis, membrane permeability, wall stress, snap buckling, elastic instability) are highlighted and advances in our understanding of these processes are summarised
Memories for Life: A Review of the Science and Technology
This paper discusses scientific, social and technological aspects of memory. Recent developments in our understanding of memory processes and mechanisms, and their digital implementation, have placed the encoding, storage, management and retrieval of information at the forefront of several fields of research. At the same time, the divisions between the biological, physical and the digital worlds seem to be dissolving. Hence opportunities for interdisciplinary research into memory are being created, between the life sciences, social sciences and physical sciences. Such research may benefit from immediate application into information management technology as a testbed. The paper describes one initiative, Memories for Life, as a potential common problem space for the various interested disciplines
Family Diversities Reading Resource (2nd edition)
An annotated bibliography of 150+ high quality children's picture books showing diverse families
Constrained Type Families
We present an approach to support partiality in type-level computation
without compromising expressiveness or type safety. Existing frameworks for
type-level computation either require totality or implicitly assume it. For
example, type families in Haskell provide a powerful, modular means of defining
type-level computation. However, their current design implicitly assumes that
type families are total, introducing nonsensical types and significantly
complicating the metatheory of type families and their extensions. We propose
an alternative design, using qualified types to pair type-level computations
with predicates that capture their domains. Our approach naturally captures the
intuitive partiality of type families, simplifying their metatheory. As
evidence, we present the first complete proof of consistency for a language
with closed type families.Comment: Originally presented at ICFP 2017; extended editio
Should the Insanity Defense be Abolished - An Introduction to the Debate
As the plans for the debate began to unfold I was concerned about the possibility that the subject matter might already be jaded, or in any event no longer would be a hot topic for our potential audience. Being quite familiar with the writings of our Advocates and therefore particularly susceptible to the reader-listener rehash syndrome, I was nonetheless hopeful that what had the potential for being old-hat would instead be new and interesting to those members of the audience not professionally committed to intimate familiarity with the subject matter. While I had expected that these issues, aired in the setting of a debate, would be more exciting and immediate than even the extraordinary written scholarship of both erudite visitors, I hadn\u27t expected the remarkable level of intensity, originality and profundity to which all of us were treated
Magnetically operated check valve
A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region
Should the Insanity Defense be Abolished - An Introduction to the Debate
As the plans for the debate began to unfold I was concerned about the possibility that the subject matter might already be jaded, or in any event no longer would be a hot topic for our potential audience. Being quite familiar with the writings of our Advocates and therefore particularly susceptible to the reader-listener rehash syndrome, I was nonetheless hopeful that what had the potential for being old-hat would instead be new and interesting to those members of the audience not professionally committed to intimate familiarity with the subject matter. While I had expected that these issues, aired in the setting of a debate, would be more exciting and immediate than even the extraordinary written scholarship of both erudite visitors, I hadn\u27t expected the remarkable level of intensity, originality and profundity to which all of us were treated
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