19,887 research outputs found
Materials Characterization using the Backscattered Electron Signal in Scanning Electron Microscopy
The backscattered electron signal in scanning electron microscopy is sensitive to changes in the atomic number of the specimen. This atomic number information can be measured by calibrating the output of a backscattered electron detector from two known materials. The atomic number of an unknown sample can then be determined by measuring the backscattered electron signal from the unknown sample.
Knowing the atomic number factor of an unknown sample and the heavy elements (Z \u3e 10 as determined from X-ray analysis), the existence of light elements can be detected. From a knowledge of the sample and valence information, the composition of a sample can often be characterised in terms of its chemical formula
Electron Detectors Used for Imaging in the Scanning Electron Microscope
Electron detectors used for imaging in the scanning electron microscope include those which detect secondary electrons, various portions of the backscattered electron signal, and the residual specimen current. The use of a different detector will often produce a different image of the same specimen. The information contained in these images depends upon the signal detected and the properties of the detector used. The choice of detector to be used depends upon the information desired
Theoretical backgrounds of durability analysis by normalized equivalent stress functionals
Generalized durability diagrams and their properties are considered for a material under a multiaxial loading given by an arbitrary function of time. Material strength and durability under such loading are described in terms of durability, safety factor and normalized equivalent stress. Relations between these functionals are analysed. We discuss some material properties including time and load stability, self-degradation (ageing), and monotonic damaging. Phenomenological strength conditions are presented in terms of the normalized equivalent stress. It is shown that the damage based durability analysis is reduced to a particular case of such strength conditions. Examples of the reduction are presented for some known durability models. The approach is applicable to the strength and durability description at creep and impact loading and their combination
History-sensitive accumulation rules for life-time prediction under variable loading
This is the post-print version of the article. The official published version can be obtained from the link below - Copyright @ 2011 SpringerA general form of temporal strength conditions under variable creep loading is employed to formulate several new phenomenological accumulation rules based on the constant-loading durability diagram. Unlike the well-known Robinson rule of linear accumulation of partial life-times, the new rules allow to describe the life-time sensibility to the load sequence, observed in experiments. Comparison of the new rules with experimental data shows that they fit the data much more accurately than the Robinson rule
Identification of an active metabolite of PAR-1 antagonist RWJ-58259 and synthesis of analogues to enhance its metabolic stability
The discontinuation of PAR-1 antagonist RWJ-58259 beyond use as a biological probe is most likely due to it's short half-life in vivo. However, retention of significant in vivo activity beyond the point where most of the RWJ-58259 had been consumed implies the generation of an active metabolite. Herein we describe the biological activity of a predicted metabolite of RWJ-58259 and the synthesis of analogues designed to enhance the metabolic stability of RWJ-58259
Measurements of the Casimir-Lifshitz force in fluids: the effect of electrostatic forces and Debye screening
In this work, we present detailed measurements of the Casimir-Lifshitz force
between two gold surfaces (a sphere and a plate) immersed in ethanol and study
the effect of residual electrostatic forces, which are dominated by static
fields within the apparatus and can be reduced with proper shielding.
Electrostatic forces are further reduced by Debye screening through the
addition of salt ions to the liquid. Additionally, the salt leads to a
reduction of the Casimir-Lifshitz force by screening the zero-frequency
contribution to the force; however, the effect is small between gold surfaces
at the measured separations and within experimental error. An improved
calibration procedure is described and compared to previous methods. Finally,
the experimental results are compared to Lifshitz's theory and found to be
consistent for the materials used in the experiment.Comment: 11 figures. PRA in pres
Synthesis of novel and potent vorapaxar analogues
Vorapaxar is a first-in-class PAR-1 antagonistic drug based on the ent-himbacine scaffold. Detailed in this article are enantioselective and racemic routes to various novel vorapaxar analogues. Biological testing revealed these compounds to have moderate to excellent potencies against PAR-1 with the most potent analogue demonstrating an IC50 of 27 nM
Fully Explorable Horned Particles Hiding Charge
The charge-hiding effect by a horned particle, which was studied for the case
where gravity/gauge-field system is self-consistently interacting with a
charged lightlike brane (LLB) as a matter source, is now studied for the case
of a time like brane. From the demand that no surfaces of infinite coordinate
time redshift (horizons) appear in the problem we are lead now to a completly
explorable horned particle space for traveller that goes through the horned
particle (as was the case for the LLB) but now also in addition to this, the
horned region is fully visible to a static external observer. This requires
negative surface energy density for the shell sitting at the throat. We study a
gauge field subsystem which is of a special non-linear form containing a
square-root of the Maxwell term and which previously has been shown to produce
a QCD-like confining gauge field dynamics in flat space-time. The condition of
finite energy of the system or asymptotic flatness on one side of the horned
particle implies that the charged object sitting at the throat expels all the
flux it produces into the other side of the horned particle, which turns out to
be of a "tube-like" nature. An outside observer in the asymptotically flat
universe detects, therefore, apparently neutral object. The hiding of the
electric flux behind the tube-like region of a horned particle is the only
possible way that a truly charged particle can still be of finite energy, in a
theory that in flat space describes confinement. This points to the physical
relevance of such solutions, even though there is the need of negative energy
density at the throat of the horned particle, which can be of quantum
mechanical origin.Comment: The new version has been accepted for publication in Classical and
Quantum Gravity. Title changed to "Fully Explorable Horned Particles Hiding
Charge". Horned Particles terminology is used now instead of "wormholes" to
dscribe the solutions here. arXiv admin note: text overlap with
arXiv:1108.373
Gender difference and effect of pharmacotherapy: findings from a smoking cessation service
Background: Smoking cessation services are available in England to provide assistance to those wishing to
quit smoking. Data from one such service were analysed in order to investigate differences in quit rate between
males and females prescribed with different treatments.
Methods: A logistic regression model was fitted to the data using the binary response of self-reported quit
(failed attempt = 0, successful attempt = 1), validated by Carbon Monoxide (CO) monitoring, 4 weeks after commencing
programme. Main effects fitted were: client gender; age; region; the type of advisory sessions; and pharmacotherapy,
Nicotine Replacement Therapy (NRT) or Varenicline. A second model was fitted including all main effects plus two-way
interactions except region. These models were repeated using 12-week self-reported quit as the outcome.
Results: At 4 weeks, all main effects were statistically significant, with males more likely (odds ratio and 95 % CI,
females v males = 0.88 [0.79–0.97]), older smokers more likely (adjusted odds ratios [OR] and 95 % confidence interval [CI]
respectively for groups 20–29, 30–49, 50–69 and 70+ vs 12–19 age group: 1.79 [1.39–2.31], 2.12 [1.68–2.68], 2.30 [1.80–2.
92] and 2.47 [1.81–3.37] and for overall difference between groups, χ
2
(4) = 53.5, p < 0.001) and clients being treated with
Varenicline more likely to have successfully quit than those on NRT (adjusted OR and 95 % CI for Varenicline vs NRT = 1.41
[1.21–1.64]). Statistically significant interactions were observed between (i) gender and type of counselling, and (ii) age
and type of counselling. Similar results were seen in relation to main effects at 12 weeks except that type of counselling
was non-significant. The only significant interaction at this stage was between gender and pharmacotherapy
(adjusted OR and 95 % CI for females using Varenicline versus all other groups = 1.43 [1.06–1.94]).
Conclusion: Gender and treatment options were identified as predictors of abstinence at both 4 and 12 weeks after
quitting smoking. Furthermore, interactions were observed between gender and (i) type of counselling received (ii)
pharmacotherapy. In particular, the quit rate in women at 12 weeks was significantly improved in conjunction with
Varenicline use. These findings have implications for service delivery
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