6,669 research outputs found
Bioremoval of Phenol from Aqueous Solutions Using Native Caribbean Seaweed
Among several Puerto Rican algae, Sargassum sp. (SG) and Chaetomorpha (CM) showed the highest phenol adsorption capacity from aqueous solutions and were used in optimized adsorption batch experiments at room temperature. The effects of pH, adsorbent dose, phenol concentration, salinity and presence of interfering substances were evaluated. Initial solution pH exhibited a strong effect, mainly on the phenol aqueous chemistry; showing the maximum adsorption at pH 10. Sorption isotherm results were modelled according to the Langmuir, Tempkin and Freundlich equations. Isotherm modelling indicated a maximum adsorption capacity (qmax) of 82.10 and 17.7 mg of phenol per gram of SG and CM, respectively. Salinity and presence of detergent in the matrix solution showed a positive effect on the adsorption, suggesting that adsorption of phenol was mostly driven by polar forces and not by ionic exchange. On the other hand, presence of heavy metals like copper, lead and cobalt had a negative effect on the adsorption. According to these results, the potential formation of hydrogen bonds between the algae and phenol is proposed as the main adsorption mechanism. These results provide further insight into the adsorption mechanism of phenol and their use as inexpensive adsorbents for the treatment of phenol-containing wastewaters
Flexible membranes anchored to the ground for slope stabilisation: Numerical modelling of soil slopes using SPH
An alternative modelling for flexible membranes anchored to the ground for soil slope stabilisation is presented using Smoothed-Particle Hydrodynamics to model the unstable ground mass in a soil slope, employing a dynamic solve engine. A regression model of pressure normal to the ground, qsim, and also membrane deflection, fsim, have been developed using Design of Experiment. Finally, a comparison between the pressure obtained from numerical simulation and from a limit equilibrium analysis considering infinite slope has been carried out, showing differences in the results, mainly due to the membrane stiffness.The realization of this research paper has been possible thanks to the funding of the following entities: SODERCAN (Sociedad para el Desarrollo de Cantabria), ConsejerĂa de Obras PĂșblicas del Gobierno de Cantabria, Iberotalud S.L., Malla Talud Cantabria S.L. and Contratas Iglesias S.L.
The authors wish also to acknowledge the support provided by the GICONSIME Research Group of the University of Oviedo and the GITECO Research Group of the University of Cantabria. We also thank Swanson Analysis Inc. for the use of the ANSYS Academic program
Broken R-parity, stop decays, and neutrino physics
We discuss the phenomenology of the lightest stop in models where R-parity is
broken by bilinear superpotential terms. In this class of models we consider
scenarios where the R-parity breaking two-body decay ~t_1->\tau^+b competes
with the leading three-body decays such as ~t_1->W^+b~\chi^0_1. We demonstrate
that the R-parity violating decay can be sizable and in some parts of the
parameter space even the dominant one. Moreover we discuss the expectations for
\~t_1->\mu^+b and ~t_1->e^+b. The recent results from solar and atmospheric
neutrinos suggest that these are as important as the tau bottom mode. The
\~t_1->l^+b decays are of particular interest for hadron colliders, as they may
allow a full mass reconstruction of the lighter stop. Moreover these decay
modes allow cross checks on the neutrino mixing angle involved in the solar
neutrino puzzle complementary to those possible using neutralino decays. For
the so--called small mixing angle or SMA solution ~t_1->e^+b should be
negligible, while for the large mixing angle type solutions all ~t_1->l^+b
decays should have comparable magnitude.Comment: 51 pages, 6 figures, LaTeX2e and RevTeX4, published versio
Reconciling neutrino anomalies in a simple four-neutrino scheme with R-parity violation
We propose a simple extension of the MSSM based on extra compact dimensions
which includes an singlet superfield. The fermion present
in this superfield is the sterile neutrino, which combines with one linear
combination of to form a Dirac pair whose mass
accounts for the LSND anomaly. Its small mass can be ascribed to a volume
suppression factor associated with extra compact dimensions. On the other hand
the sterile neutrino scalar partner can trigger the spontaneous violation of
R-parity, thereby inducing the necessary mass splittings to fit also the solar
and atmospheric neutrino data. Thus the model can explain all neutrino
oscillation data. It leads to four predictions for the neutrino oscillation
parameters and implies that the atmospheric neutrino problem must include at
least some oscillations, which will be testable in the
near future. Moreover it also predicts that the lightest supersymmetric
particle (LSP) decays visibly via lepton number violating modes, which could be
searched for at present and future accelerators.Comment: 15 pages, requires axodraw.sty and elsart.cl
Searching for R-Parity Violation at Run-II of the Tevatron
We present an outlook for possible discovery of supersymmetry with broken
R-parity at Run II of the Tevatron. We first present a review of the literature
and an update of the experimental bounds. In turn we then discuss the following
processes: 1. Resonant slepton production followed by R-parity violating decay,
(a) via and (b) via . 2. How to distinguish resonant slepton
production from or production. 3. Resonant slepton production
followed by the decay to neutralino LSP, which decays via . 4. Resonant
stop production followed by the decay to a chargino, which cascades to the
neutralino LSP. 5. Gluino pair production followed by the cascade decay to
charm squarks which decay directly via . 6. Squark pair production
followed by the cascade decay to the neutralino LSP which decays via
. 7. MSSM pair production followed by the cascade decay to the LSP
which decays (a) via , (b) via , and (c) via ,
respectively. 8. Top quark and top squark decays in spontaneous R-parity
violation.Comment: 39 pages, 51 figures, LaTex, reqires aipproc2.sty and axodraw.sty. To
be published in the Physics at Run II Workshop: Supersymmetry/Higgs. Text has
been edited by H. Dreiner. Author list on front page has been correcte
Charged lepton Flavor Violation in Supersymmetry with Bilinear R-Parity Violation
The simplest unified extension of the Minimal Supersymmetric Standard Model
with bi-linear R-parity violation naturally predicts a hierarchical neutrino
mass spectrum, suitable to explain atmospheric and solar neutrino fluxes. We
study whether the individual violation of the lepton numbers L_{e,mu,tau} in
the charged sector can lead to measurable rates for BR(mu->e gamma)and
$BR(tau-> mu gamma). We find that some of the R-parity violating terms that are
compatible with the observed atmospheric neutrino oscillations could lead to
rates for mu->e gamma measurable in projected experiments. However, the Delta
m^2_{12} obtained for those parameters is too high to be compatible with the
solar neutrino data, excluding therefore the possibility of having measurable
rates for mu->e gamma in the model.Comment: 29 pages, 8 figures. Constraint from solar neutrino data included,
conclusions changed respect v
A Dual Role for KRT81: A miR-SNP Associated with Recurrence in Non-Small-Cell Lung Cancer and a Novel Marker of Squamous Cell Lung Carcinoma
MicroRNAs (miRNAs) play an important role in carcinogenesis through the regulation of their target genes. miRNA-related single nucleotide polymorphisms (miR-SNPs) can affect miRNA biogenesis and target sites and can alter microRNA expression and functions. We examined 11 miR-SNPs, including 5 in microRNA genes, 3 in microRNA binding sites and 3 in microRNA-processing machinery components, and evaluated time to recurrence (TTR) according to miR-SNP genotypes in 175 surgically resected non-small-cell lung cancer (NSCLC) patients. Significant differences in TTR were found according to KRT81 rs3660 (median TTR: 20.3 months for the CC genotype versus 86.8 months for the CG or GG genotype; Pâ=â0.003) and XPO5 rs11077 (median TTR: 24.7 months for the AA genotype versus 73.1 months for the AC or CC genotypes; Pâ=â0.029). Moreover, when patients were divided according to stage, these differences were maintained for stage I patients (Pâ=â0.002 for KRT81 rs3660; P<0.001 for XPO5 rs11077). When patients were divided into sub-groups according to histology, the effect of the KRT81 rs3660 genotype on TTR was significant in patients with squamous cell carcinoma (Pâ=â0.004) but not in those with adenocarcinoma. In the multivariate analyses, the KRT81 rs3660 CC genotype (ORâ=â1.8; Pâ=â0.023) and the XPO5 rs11077 AA genotype (ORâ=â1.77; Pâ=â0.026) emerged as independent variables influencing TTR. Immunohistochemical analyses in 80 lung specimens showed that 95% of squamous cell carcinomas were positive for KRT81, compared to only 19% of adenocarcinomas (P<0.0001). In conclusion, miR-SNPs are a novel class of SNPs that can add useful prognostic information on the clinical outcome of resected NSCLC patients and may be a potential key tool for selecting high-risk stage I patients. Moreover, KRT81 has emerged as a promising immunohistochemical marker for the identification of squamous cell lung carcinoma
Testing neutrino mixing at future collider experiments
Low energy supersymmetry with bilinear breaking of R-parity leads to a
weak-scale seesaw mechanism for the atmospheric neutrino scale and a radiative
mechanism for the solar neutrino scale. The model has striking implications for
collider searches of supersymmetric particles. Assuming that the lightest SUSY
particle is the lightest neutralino we demonstrate that (i) The neutralino
decays inside the detector even for tiny neutrino masses. (ii) Measurements of
the neutrino mixing angles lead to predictions for the ratios of various
neutralino branching ratios implying an independent test of neutrino physics at
future colliders, such as the Large Hadron Collider or a Linear Collider.Comment: LaTex, 35 pages, 20 figures included, version 2, section on model
shortened, Fig. 13 replaced, typos corrected, version to appear in Phys.Rev.
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