7,455 research outputs found
Flavour Changing Neutral Currents, Weak-Scale Scalars and Rare Top Decays
We examine the decays and in the Standard
Model with an extra scalar doublet and no discrete symmetry preventing
tree-level flavour changing neutral currents. The Yukawa couplings of the new
scalars are assumed to be proportional to fermion masses, evading bounds on
FCNC's from the light quark sector. These rare top decays may be visible at the
SSC.Comment: (some wording changed, and several references added) 13 pages, 2
figures included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-0
Use of electrical resistance tomography (ERT) for the detection of biofilm disruption mediated by biosurfactants
© 2018 Institution of Chemical Engineers Inline measurement of biofilms could provide a valuable technology for water, food and bioprocessing industries to improve quality control and avoid contamination. This study presents the first use of electrical resistance tomography (ERT) to detect the removal of biofilms in a pipe. It also tests the effectiveness of sophorolipids and rhamnolipids for the disruption of Bacillus subtilis BBK006 biofilms in an industrial setting. Biofilms were grown on the inner side of a section of 1.5″ test pipe for 5 days using nutrient broth as the culture medium. After the medium was removed the test pipe was incorporated into a cleaning test circuit for the biofilm disruption experiment, where water, sophorolipids (0.4 g L−1) or rhamnolipids (0.4 g L−1) solutions were pumped through respectively for 30 min. ERT was used as an indirect evaluation of the film disruption progression. A cleaning parameter was identified based on zonal boundary averages which successfully measured the extent of biofilm removal
Diffusive Release of Photosensitizing Agents (PS) from Novel PVA-Borate Semi-Solid Drug Carriers Through In Vitro Oral Streptococcus mutans Biofilm
Background: Streptococcus mutans, one of the agent of human dental caries, is particularly effective at forming biofilms on the hard tissues of the human oral cavity; the purpose of this study was to investigate and quantify the diffusional release of photosentising agents (PS): methylene blue (MB), toludine blue (TB), rose bengal (RB) and methyl orange (MO) from Polyvinyl alcohol (PVA)-borate semi-solid gels in the presence of in vitro oral Streptococcus mutans biofilm. Methods: S. mutans biofilm growths were ascertained to ensure proper dental plaque formation and were characterized using confocal microscopy. Release profiles for MB, TB, RB and MO-loaded PVA-borate semi-solids in the absence of biofilms were directly compared to their counterparts in the presence of S. mutans biofilms. In addition, their diffusion coefficients and resistances were determined. Results: The confocal imaging results showed that biofilms grown over a 5-day period had a generally uninterrupted film of colonies occupying the entire surface area of growth surface of a nylon mesh support with approximately 60 µm biofilm size. The overall diffusion resistance of all PVA-borate semi-solids in the presence of S. mutans biofilms was about 1.2 times lower than the diffusion resistance for PVAborate semi-solids in the absence of biofilms. The diffusion resistances for all studied PS, indicate that electrostatic forces and molecular size play an important part in controlled and sustained drug release from PVA-borate semi-solids. Conclusions: PVA-borate semi-solids as novel PSs carriers might offer an innovative delivery system in the treatment against Streptococcus mutans
Supersymmetric Model of Muon Anomalous Magnetic Moment and Neutrino Masses
We propose the novel lepton-number relationship , which
is uniquely realized by the interaction in supersymmetry and may account for a possibly large
muon anomalous magnetic moment. Neutrino masses (with bimaximal mixing) may be
generated from the spontaneous and soft breaking of this lepton symmetry.Comment: 10 pages, including 2 figure
Influence of microbial adherence on corrosion of UNS 1008 carbon steel and hybrid nano-structured coatings
Microbiologically induced corrosion (MIC) causes the degradation of coatings and it can be attributed to either direct or indirect microbial metabolic activity. In this study, we report the ability of sulphate reducing microorganisms (SRM) and marine strain bacteria to attach onto UNS1008 carbon steel, and zinc rich epoxy coatings with a content of carbon nanotubes (CNTs) respectively. In aerobic conditions the outer layer presents a micro-crack appearance and many semisphere products, attributed to spore formation. In anaerobic conditions, evidence of iron sulphide surrounded by a mixture of sulphur-containing extracellular polymer substance was observed by SEM images and EDS analysis. The presence of hybrid coatings (Zn rich epoxy with CNT content) affected the level of microbial adherence and the concentration of corrosion products (Fe2O3, Fe(OH)2, FeS); the cell attachment was lower when the steel surface was coated with Zn/CNTs
Influence of microbial adherence on corrosion of UNS 1008 carbon steel and hybrid nano-structured coatings
Microbiologically induced corrosion (MIC) causes the degradation of coatings and it can be attributed to either direct or indirect microbial metabolic activity. In this study, we report the ability of sulphate reducing microorganisms (SRM) and marine strain bacteria to attach onto UNS1008 carbon steel, and zinc rich epoxy coatings with a content of carbon nanotubes (CNTs) respectively. In aerobic conditions the outer layer presents a micro-crack appearance and many semisphere products, attributed to spore formation. In anaerobic conditions, evidence of iron sulphide surrounded by a mixture of sulphur-containing extracellular polymer substance was observed by SEM images and EDS analysis. The presence of hybrid coatings (Zn rich epoxy with CNT content) affected the level of microbial adherence and the concentration of corrosion products (Fe2O3, Fe(OH)2, FeS); the cell attachment was lower when the steel surface was coated with Zn/CNTs
Relaxing b\to s\gamma Constraints on the Supersymmetric Particle Mass Spectrum
We consider the radiative decay b \to s \gamma in a supersymmetric extension
of the standard model of particle interactions, where the -quark mass is
entirely radiative in origin. This is accomplished by the presence of
nonholomorphic soft supersymmetry breaking terms in the Lagrangian. As a
result, the contributions to the b \to s \gamma amplitude from the charged
Higgs boson and the charginos/neutralinos are suppressed by 1/\tan^2\beta and
{\cal O}(\alpha/\alpha_s) respectively, allowing these particles to be lighter
than in the usual supersymmetric model. Their radiatively generated couplings
differ from the usual tree-level ones and change the collider phenomenology
drastically. We also study how this scenario may be embedded into a larger
framework, such as supersymmetric SU(5) grand unification.Comment: references added, version to be published in PL
Enhancement of Radiatively Induced Magnetic Moment Form-Factors of Muon: an Effective Lagrangian Approach
Using an effective lagrangian approach, we identify a class of models in
which the loop-induced magnetic moment form-factors of muon are enhanced by
possibly large factors
(\Lambda^2_F/\Lambda^2)(m_\tau/m_\mu)\ln(m_\tau^2/\Lambda^2) or
(\Lambda^2_F/\Lambda^2)\ln(m_\mu^2/\Lambda^2), where \Lambda is the scale of
new physics and \Lambda_F is the Fermi scale. These follow from left- and
right-chirality mixing dimension-8 operators which for relatively small
\Lambda, as required to explain the new (g_\mu-2) measurement, dominate over
dimension-6 operators. Thus significant enhancement of new physics
contributions to (g_\mu-2) and, in the presence of intergenerational couplings,
also to the \mu\to e\gamma decay rate is possible. We discuss the compatibility
of the (g_\mu-2) and \mu\to e\gamma experimental data in this case and comment
on the enhancement of the electron anomalous magnetic moment. An explicit model
is presented to illustrate the general results.Comment: Discussion on the enhancement of electron anomalous magnetic moment
included. New references adde
Radiative corrections to : THDM versus MSSM
One loop radiative corrections to are considered at
future linear collider energies, in the general type II Two Higgs Doublet Model
(THDM) and in the Minimal Supersymmetric Standard Model-like (MSSM) Higgs
sector. To make the comparison between THDM and MSSM tractable, we have
introduced a quasi-SUSY parameterization which preserves all the tree-level
Higgs mass-sum-rules of the MSSM, and involves just 3 free parameters in the
Higgs sector (instead of 7 in the general THDM) and comprises the MSSM as a
particular case. The model-independent soft photon contribution is isolated and
shown to be substantial. Important effects come also from the contribution of
the model dependent and vertices to the final
state. In the MSSM, the contribution of the Higgs sector is moderate (a few
percent) while in the THDM and both for small and large important
effects () can be found.Comment: 46 pages, LaTeX, 9 figures, shortened and revised version, to be
published in Nuclear Physics
Antioxidant and Anti-Inflammatory Strategies Based on the Potentiation of Glutathione Peroxidase Activity Prevent Endothelial Dysfunction in Chronic Kidney Disease
BACKGROUND/AIMS: Accelerated atherosclerosis in chronic kidney disease (CKD) is preceded by endothelial dysfunction (ED), which exhibits a proinflammatory and prothrombotic phenotype and enhanced oxidative stress. In this study, the effect of several compounds with anti-inflammatory and/or antioxidant properties on uremia-induced endothelial dysfunction has been evaluated in an in vitro model. METHODS: Endothelial cells (ECs) were exposed to sera from uremic patients in the absence and presence of the flavonoids apigenin, genistein and quercetin, the antioxidant enzyme mimetics (AEM) ebselen (glutathione peroxidase mimetic), EUK-134 and EUK-118 (both superoxide dismutase mimetics), and the pharmacological drug N-acetylcysteine (NAC). We explored changes in the expression of adhesion receptors on the cell surface, by immunofluorescence, the production of radical oxygen species (ROS), by fluorescence detection, and the activation of signaling proteins related to inflammation, by both a phosphospecific antibody cell-based ELISA and immunoblotting techniques. RESULTS: Uremic media induced a significantly increased expression of ICAM-1, overproduction of radical oxygen species (ROS) and activation of p38 mitogen activated protein kinase (p38MAPK) and Nuclear Factor kB (NFkB) in ECs. Quercetin, the AEM and NAC showed a significant inhibitory effect on both ICAM-1 expression and ROS generation (p<0.05). All the compounds reduced p38MAPK activation, but only the AEM, especially ebselen, and NAC, both potentiating the glutathione peroxidase pathway, also inhibited NFkB activation. These two compounds were capable of increasing endothelial glutathione levels, especially in response to uremia. CONCLUSION: Our results indicate that the potentiation of the antioxidant pathways can be an effective strategy to improve endothelial dysfunction in uremia and a potential target to reduce the cardiovascular risk in this population
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