16,788 research outputs found
The influence of Aluminium and Iron additions on Copper-Manganese-Zinc Alloys
MANY alloys in the ternary system Cu-Mn-Zn form the
single phase a brass type structure and in particular,
the alloys approximating to the composition 70 Cu-20
Mn-l0 Zn are sensibly white in colour.These latter
alloys also possess mechanical properties and a
corrosion resistance comparable with the brasses and nickel silvers. The potential of these alloys as subs-titutes for the white range of Cu-Ni alloys (nickel silvers) was originally investigated by R. S. Dean et
al1 in 1945 but was not pursued commercially due, it
is throught, to the limited output and excessive cost
of high purity manganese at the time. Today, it is possible to purchase high purity electrolytic manganese
at a price similar to copper. The potential of these alloys as substitutes nickel silver has thus become a
more attractive proposition.
The main aim of the present investigation was to
evaluate some of the salient properties of the 70 Cu-20
Mn-10 Zn alloys and also to study the effects of separate
additions of aluminium and iron as replacefnent elements
for zinc
The economy of mule production in the South and methods of management
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Influence of surface passivation on ultrafast carrier dynamics and terahertz radiation generation in GaAs
The carrier dynamics of photoexcited electrons in the vicinity of the surface
of (NH4)2S-passivated GaAs were studied via terahertz (THz) emission
spectroscopy and optical-pump THz-probe spectroscopy. THz emission spectroscopy
measurements, coupled with Monte Carlo simulations of THz emission, revealed
that the surface electric field of GaAs reverses after passivation. The
conductivity of photoexcited electrons was determined via optical-pump
THz-probe spectroscopy, and was found to double after passivation. These
experiments demonstrate that passivation significantly reduces the surface
state density and surface recombination velocity of GaAs. Finally, we have
demonstrated that passivation leads to an enhancement in the power radiated by
photoconductive switch THz emitters, thereby showing the important influence of
surface chemistry on the performance of ultrafast THz photonic devices.Comment: 4 pages, 3 figures, to appear in Applied Physics Letter
The Origin of Soft X-rays in DQ Herculis
DQ Herculis (Nova Herculis 1934) is a deeply eclipsing cataclysmic variable
containing a magnetic white dwarf primary. The accretion disk is thought to
block our line of sight to the white dwarf at all orbital phases due to its
extreme inclination angle. Nevertheless, soft X-rays were detected from DQ Her
with ROSAT PSPC. To probe the origin of these soft X-rays, we have performed
Chandra ACIS observations. We confirm that DQ Her is an X-ray source. The bulk
of the X-rays are from a point-like source and exhibit a shallow partial
eclipse. We interpret this as due to scattering of the unseen central X-ray
source, probably in an accretion disk wind. At the same time, we observe what
appear to be weak extended X-ray features around DQ Her, which we interpret as
an X-ray emitting knot in the nova shell.Comment: 18 pages including 4 figures, accepted for publication in
Astrphyisical Journa
Taking Place 8: Interstitial Breakfast
A contextualised presentation of an interstitial act by taking place at the AHRA conference Architecture and Feminisms: Ecologies, Economies, Technologies: 13th International Architectural Humanities Research Association Conference, KTH School of Architecture Stockholm 17-19 November 2016. Taking place (Jos Boys, Julia Dwyer, Teresa Hoskyns, Katie Lloyd Thomas and Helen Stratford) curated their 8th spatial intervention, tp8, a breakfast held early on the second conference day which addressed through conversation and evidence marked into table cloths , the conference participants' responses to an open call by taking place to the question âWhat are the relevant questions for architecture and feminism today
Isolation and identification of Acinetobacter spp. from healthy canine skin
Acinetobacter species can exhibit widespread resistance to antimicrobial agents. They are already recognized as important nosocomial pathogens of humans, but are becoming increasingly recognized in opportunistic infections of animals. This study aimed to determine whether Acinetobacter spp. are carried on skin of healthy dogs and, if present, to identify the species
Cyclic networks of quantum gates
In this article initial steps in an analysis of cyclic networks of quantum
logic gates is given. Cyclic networks are those in which the qubit lines are
loops. Here we have studied one and two qubit systems plus two qubit cyclic
systems connected to another qubit on an acyclic line. The analysis includes
the group classification of networks and studies of the dynamics of the qubits
in the cyclic network and of the perturbation effects of an acyclic qubit
acting on a cyclic network. This is followed by a discussion of quantum
algorithms and quantum information processing with cyclic networks of quantum
gates, and a novel implementation of a cyclic network quantum memory. Quantum
sensors via cyclic networks are also discussed.Comment: 14 pages including 11 figures, References adde
Effect of guidewire on contribution of loss due to momentum change and viscous loss to the translesional pressure drop across coronary artery stenosis: An analytical approach
<p>Abstract</p> <p>Background</p> <p>Guidewire (GW) size and stenosis dimensions are the two major factors affecting the translesional pressure drop. Studying the combined effect of these parameters on the mean pressure drop (Î<it>p</it>) across the stenosis is of high practical importance.</p> <p>Methods</p> <p>In this study, time averaged mass and momentum conservation equations are solved analytically to obtain pressure drop-flow, Î<it>p</it>-<it>Q</it>, curves for three different percentage area blockages corresponding to moderate (64%), intermediate (80%), and severe (90%) stenoses. Stenosis is considered to be axisymmetric consisting of three different sections namely converging, throat, and diverging regions. Analytical expressions for pressure drop are obtained for each of these regions separately. Using this approach, effects of lesion length and GW insertion on the mean translesional pressure drop and its component (loss due to momentum change and viscous loss) are analyzed.</p> <p>Results and Conclusion</p> <p>It is observed that for a given percent area stenosis (AS), increase in the throat length only increases the viscous loss. However, increase in the severity of stenosis and GW insertion increase both loss due to momentum change and viscous loss. GW insertion has greater contribution to the rise in viscous loss (increase by 2.14 and 2.72 times for 64% and 90% AS, respectively) than loss due to momentum change (1.34% increase for 64% AS and 25% decrease for 90% AS). It also alters the hyperemic pressure drop in moderate (48% increase) to intermediate (30% increase) stenoses significantly. However, in severe stenoses GW insertion has a negligible effect (0.5% increase) on hyperemic translesional pressure drop. It is also observed that pressure drop in a severe stenosis is less sensitive to lesion length variation (4% and 14% increase in Î<it>p </it>for without and with GW, respectively) as compared to intermediate (10% and 30% increase in Î<it>p </it>for without and with GW, respectively) and moderate stenoses (22% and 48% increase in Î<it>p </it>for without and with GW, respectively). Based on the contribution of pressure drop components to the total translesional pressure drop, it is found that viscous losses are dominant in moderate stenoses, while in severe stenoses losses due to momentum changes are significant. It is also shown that this simple analytical solution can provide valuable information regarding interpretation of coronary diagnostic parameters such as fractional flow reserve (FFR).</p
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