9,177 research outputs found
Corrosion study of pipeline material for seabed sediment in tropical climate
Corrosive environments such as marine sediments can cause corrosion to
steel pipelines at any time when certain conditions are met. Seabed sediment could cause severe corrosion damage due to its corrosiveness to the pipelines buried under it. Many consequences could take place in case if there is incident in oil/gas pipelines. Successfully identifying elements of corrosion in marine sediment would enhance the future of steel structure protection and monitoring systems. This article focuses on the behaviour of corrosion rate of steel located near shore environment and the aim is to determine the effect of sediment on corrosion of steel. To investigate that, simulated near shore sediment conditions have been used where the steel coupons buried in sediments which have different characteristics. Weight loss technique has been implemented to determine the weight loss rate of the steel specimens. Based on the
results of this study, metal weight loss increases as the duration of exposure to seabed sediment environment become longer. The sea sediment simulated condition has given significant levels of corrosion. Conclusively, the corrosion rate of steel in seabed sediment located in tropical region is complicated and further studies are suggested
The Chromoelectric Dipole Moment of the Top Quark in Models with Vector Like Multiplets
The chromoelectric dipole moment of the top quark is calculated in a model
with a vector like multiplet which mixes with the third generation in an
extension of the MSSM. Such mixings allow for new CP violating phases.
Including these new CP phases, the chromoelectric dipole moment that generates
an electric dipole of the top in this class of models is computed. The top
chromoelectric dipole moment operator arises from loops involving the exchange
of the W, the Z as well as from the exchange involving the charginos, the
neutralinos, the gluino, and the vector like multiplet and their superpartners.
The analysis of the chromoelectric dipole moment operator of the top is more
complicated than for the light quarks because the mass of the external fermion,
in this case the top quark mass, cannot be ignored relative to the masses
inside the loops. A numerical analysis is presented and it is shown that the
contribution to the top EDM could lie in the range ( ecm
consistent with the current limits on the EDM of the electron, the neutron and
on atomic EDMs. A top EDM of size ecm could be accessible
in collider experiments such as at the LHC and at the ILC.Comment: 17 pages, 6 figures. Accepted for publication in Phys. Rev.
Magnetic graphene oxide as adsorbent for the removal of lead(II) from water samples
Magnetic Fe3O4 nanoparticles were prepared on graphene oxide (Fe3O4/GO) in situ in a one step process. The obtained Fe3O4/GO was used as an adsorbent for the removal for Pb(II) from environmental water samples prior to flame atomic absorption spectroscopy measurement. The adsorption procedure was optimized as follows: 60 min adsorption time, 50 mL sample volume, solution pH 4.5, and 25 mg adsorbent dosage. Under the optimum conditions, the adsorption efficiency obtained was greater than 75% (C = 50 mg L-1). The adsorption isotherm of Fe3O4@GO magnetic adsorbent was studied for Pb(II) adsorption using two isotherm adsorption models namely Langmuir and Freundlich. The adsorption isotherm data fits well with Langmuir isotherm (R2 = 0.9988) rather than with Freundlich isotherm. The maximum adsorption capacity (qm) obtained was 86.2 mg g-1. The results signified that the prepared Fe3O4/GO nanocomposite has a great adsorptive ability towards the Pb(II) from environmental water samples
A Young Man with Multiple Pulmonary Cysts
Several diseases cause cystic or cyst-like parenchymal lung abnormalities including adult pulmonary Langerhan's cell histiocytosis (PLCH), lymphangioleiomyomatosis (LAM), emphysema, end-stage interstitial lung disease, and cystic bronchiectasis. Many of these diseases can now be diagnosed with high accuracy by the use of high-resolution computerized tomography (HRCT). In fact, HRCT of chest has proved a major breakthrough in the diagnosis of these diseases. We are presenting a young man with a cystic lung disease in which, the HRCT findings were virtually diagnostic of that disease. The clinical and HRCT findings of this disease along with its differential diagnosis are discussed in this paper
Effects of CP Violation on Event Rates in the Direct Detection of Dark Matter
A full analytic analysis of the effects of CP violating phases on the event
rates in the direct detection of dark matter in the scattering of neutralinos
from nuclear targets is given. The analysis includes CP violating phases in
softly broken supersymmetry in the framework of the minimal supersymmetric
standard model (MSSM) when generational mixings are ignored. A numerical
analysis shows that large CP violating phases including the constraints from
the experimental limits on the neutron and the electron electric dipole moment
(EDM) can produce substantial effects on the event rates in dark matter
detectors.Comment: 17 pages, LaTex, including 2 figures; revised version to appear in
the Physical Review
Electron and Neutron Electric Dipole Moments in the Focus Point Scenario of SUGRA Model
We estimate the electron and neutron electric dipole moments in the focus
point scenario of the minimal SUGRA model corresponding to large sfermion
masses and moderate to large . There is a viable region of moderate
fine-tuning in the parameter space, around , where the
experimental limits on these electric dipole moments can be satisfied without
assuming unnaturally small phase angles. But the fine-tuning constraints become
more severe for .Comment: 16 pages, LaTeX, 4 postscript figures. Very minor changes made in
only a few sentences for clarification. Final version to appear in Phys. Rev.
CP Violation and Dark Matter
A brief review is given of the effects of CP violation on the direct
detection of neutralinos in dark matter detectors. We first summarize the
current developments using the cancellation mechanism which allows for the
existence of large CP violating phases consistent with experimental limits on
the electron and on the neutron electric dipole moments in a broad class of
SUSY, string and D brane models. We then discuss their effects on the
scattering of neutralinos from quarks and on the event rates. It is found that
while CP effects on the event rates can be enormous such effects are reduced
significantly with the imposition of the EDM constraints. However, even with
the inclusion of the EDM constraints the effects are still very significant and
should be included in a precision prediction of event rates in any SUSY, string
or D brane model.Comment: Based on an invited talk at the conference "Sources and Detection of
Dark Matter in the Universe", at Marina del Rey, CA, Feb. 23-25, 2000; 12
pages, Latex including 2 figure
Mixing of the CP Even and the CP Odd Higgs Bosons and the EDM Constraints
The mixing among the CP even and the CP odd neutral Higgs bosons of MSSM by
one loop induced effects in the presence of CP phases is investigated using
three different mechanisms to satisfy the EDM constraints, i.e., a fine tuning
of phases, a heavy sparticle spectrum, and the cancellation mechanism. It is
shown that if a mixing effect among the CP even and the CP odd Higgs bosons is
observed experimentally, then it is only the cancellation mechanism that can
survive under the naturalness constraint.Comment: 14 pages, Latex and 4figures. A new paragraph is added and few more
references. One figure is modified. To appear in Phys. Rev.
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