698 research outputs found
A combined "electrochemical-frustrated Lewis pair" approach to hydrogen activation: surface catalytic effects at platinum electrodes
Herein, we extend our “combined electrochemical–frustrated Lewis pair” approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical–frustrated Lewis pair (FLP) system involving the B(C6F5)3/[HB(C6F5)3]− redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6F5)3 to B(C6Cl5)3, the mechanism of electrochemical–FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [Pt[BOND]H] adatoms and transient [HB(C6F5)3]⋅ electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis
Direct and Indirect Detection of Dark Matter in D6 Flavor Symmetric Model
We study a fermionic dark matter in a non-supersymmetric extension of the
standard model with a family symmetry based on D6xZ2xZ2. In our model, the
final state of the dark matter annihilation is determined to be e+ e- by the
flavor symmetry, which is consistent with the PAMELA result. At first, we show
that our dark matter mass should be within the range of 230 GeV - 750 GeV in
the WMAP analysis combined with mu to e gamma constraint. Moreover we
simultaneously explain the experiments of direct and indirect detection, by
simply adding a gauge and D6 singlet real scalar field. In the direct detection
experiments, we show that the lighter dark matter mass ~ 230 GeV and the
lighter standard model Higgs boson ~ 115 GeV is in favor of the observed bounds
reported by CDMS II and XENON100. In the indirect detection experiments, we
explain the positron excess reported by PAMELA through the Breit-Wigner
enhancement mechanism. We also show that our model is consistent with no
antiproton excess suggested by PAMELA.Comment: 20 pages, 9 figures, 2 tables, accepted version for publication in
European Physical Journal
Essential role of CFTR in PKA-dependent phosphorylation, alkalinization, and hyperpolarization during human dperm capacitation
Mammalian sperm require to spend a limited period of time in the female reproductive tract to become competent to fertilize in a process called capacitation. It is well established that HCO3 − is essential for capacitation because it activates the atypical soluble adenylate cyclase ADCY10 leading to cAMP production, and promotes alkalinization of cytoplasm, and membrane hyperpolarization. However, how HCO3 − is transported into the sperm is not well understood. There is evidence that CFTR activity is involved in the human sperm capacitation but how this channel is integrated in the complex signaling cascades associated with this process remains largely unknown. In the present work, we have analyzed the extent to which CFTR regulates different events in human sperm capacitation. We observed that inhibition of CFTR affects HCO3 −-entrance dependent events resulting in lower PKA activity. CFTR inhibition also affected cAMP/PKA-downstream events such as the increase in tyrosine phosphorylation, hyperactivated motility, and acrosome reaction. In addition, we demonstrated for the first time, that CFTR and PKA activity are essential for the regulation of intracellular pH, and membrane potential in human sperm. Addition of permeable cAMP partially recovered all the PKA-dependent events altered in the presence of inh-172 which is consistent with a role of CFTR upstream of PKA activation.Fil: Puga Molina, Lis del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Pinto, Nicolás Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Torres Rodríguez, Paulina. Universidad Nacional Autónoma de México; MéxicoFil: Romarowski, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Vicens Sanchez, Alberto. Universidad Nacional Autónoma de México; MéxicoFil: Visconti, Pablo E.. University of Massachussets; Estados UnidosFil: Darszon, Alberto. Universidad Nacional Autónoma de México; MéxicoFil: Treviño, Claudia L.. Universidad Nacional Autónoma de México; MéxicoFil: Buffone, Mariano Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentin
Proposal for generalised Supersymmetry Les Houches Accord for see-saw models and PDG numbering scheme
The SUSY Les Houches Accord (SLHA) 2 extended the first SLHA to include
various generalisations of the Minimal Supersymmetric Standard Model (MSSM) as
well as its simplest next-to-minimal version. Here, we propose further
extensions to it, to include the most general and well-established see-saw
descriptions (types I/II/III, inverse, and linear) in both an effective and a
simple gauged extension of the MSSM framework. In addition, we generalise the
PDG numbering scheme to reflect the properties of the particles.Comment: 44 pages. Changed titl
Fear Conditioning to Subliminal Fear Relevant and Non Fear Relevant Stimuli
A growing body of evidence suggests that conscious visual awareness is not a prerequisite for human fear learning. For instance, humans can learn to be fearful of subliminal fear relevant images – images depicting stimuli thought to have been fear relevant in our evolutionary context, such as snakes, spiders, and angry human faces. Such stimuli could have a privileged status in relation to manipulations used to suppress usually salient images from awareness, possibly due to the existence of a designated sub-cortical ‘fear module’. Here we assess this proposition, and find it wanting. We use binocular masking to suppress awareness of images of snakes and wallabies (particularly cute, non-threatening marsupials). We find that subliminal presentations of both classes of image can induce differential fear conditioning. These data show that learning, as indexed by fear conditioning, is neither contingent on conscious visual awareness nor on subliminal conditional stimuli being fear relevant
Coastal risk mitigation by green infrastructure in Latin America
This paper aims to highlight the prevailing experiences of Latin America and to clarify what ‘green infrastructure’ entails in addition to describing seven case studies from a range of coastal ecosystems (wetlands, coastal dunes, beaches and coral reefs) at scales varying from local to regional. The case studies are categorised according to their degree of naturalness (nature-based, engineered ecosystems, soft engineering, ecologically enhanced hard infrastructure and de-engineering). Generally, the implementation of green infrastructure projects aims to increase resilience, enhance the provision of ecosystem services, recover biodiversity, reduce the negative effects of hard infrastructure and implement corrective measures. The greatest benefits of these projects relate to the creation of multi-functional spaces, which often combine the above advantages with improved opportunities for recreation and/or economic activities. It is hoped that this paper will disseminate the experience in green infrastructure among academics and practitioners and stimulate wider adoption of green infrastructure projects and good practices
Antioxidant activity of aminodiarylamines in the thieno[3,2-b]pyridine series: radical scavenging activity, lipid peroxidation inhibition and redox profile
The antioxidant activity of the aminodi(hetero)arylamines, prepared by C-N coupling of the methyl 3-aminothieno[3,2-b]pyridine-2-carboxylate with bromonitrobenzenes and further reduction of the obtained nitro compounds, was evaluated by chemical, biochemical and electrochemical assays. The aminodi(hetero)arylamine with the amino group ortho to the NH and a methoxy group in para, was the most efficient in radical scavenging activity (RSA, 63 µM) and reducing power (RP, 33 µM), while the aminodiarylamine with the amino group in para to the NH, gave the best results in β-carotene-linoleate system (41 µM) and inhibition of formation of thiobarbituric acid reactive substances in porcine brain cells homogenates (7 µM), with EC50 values even lower than those obtained for the standard trolox. This diarylamine also presented the lowest oxidation potential, lower than the one of trolox, and the highest antioxidant power in the electrochemical assays. The para substitution with an amino group enables higher antioxidant potential.The authors are grateful to FCT and FEDER (European Fund for Regional Development)-COMPETE/QREN/EU for financial support through the research unities PEst-C/QUI/UI686/2011 and PEst-OE/AGR/UI0690/2011, the research project PTDC/QUI-QUI/111060/2009 and the post-Doctoral grant attributed to R.C.C. (SFRH/BPD/68344/2010)
LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM
We study the phenomenology of a supersymmetric left-right model, assuming
minimal supergravity boundary conditions. Both left-right and (B-L) symmetries
are broken at an energy scale close to, but significantly below the GUT scale.
Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for
superpotential and soft parameters complete at 2-loop order. At low energies
lepton flavour violation (LFV) and small, but potentially measurable mass
splittings in the charged scalar lepton sector appear, due to the RGE running.
Different from the supersymmetric 'pure seesaw' models, both, LFV and slepton
mass splittings, occur not only in the left- but also in the right slepton
sector. Especially, ratios of LFV slepton decays, such as Br()/Br() are sensitive to the
ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts
a polarization asymmetry of the outgoing positrons in the decay , A ~ [0,1], which differs from the pure seesaw 'prediction' A=1$.
Observation of any of these signals allows to distinguish this model from any
of the three standard, pure (mSugra) seesaw setups.Comment: 43 pages, 17 figure
Supersymmetric mass spectra and the seesaw type-I scale
We calculate supersymmetric mass spectra with cMSSM boundary conditions and a
type-I seesaw mechanism added to explain current neutrino data. Using
published, estimated errors on SUSY mass observables for a combined LHC+ILC
analysis, we perform a theoretical analysis to identify parameter
regions where pure cMSSM and cMSSM plus seesaw type-I might be distinguishable
with LHC+ILC data. The most important observables are determined to be the
(left) smuon and selectron masses and the splitting between them, respectively.
Splitting in the (left) smuon and selectrons is tiny in most of cMSSM parameter
space, but can be quite sizeable for large values of the seesaw scale,
. Thus, for very roughly GeV hints for type-I
seesaw might appear in SUSY mass measurements. Since our numerical results
depend sensitively on forecasted error bars, we discuss in some detail the
accuracies, which need to be achieved, before a realistic analysis searching
for signs of type-I seesaw in SUSY spectra can be carried out.Comment: 17 pages, 7 figure
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