6 research outputs found
Role of electrostatics in the binding of charged metallophthalocyanines to neutral and charged phospholipid membranes
AbstractBinding of the cationic tetra(tributylammoniomethyl)-substituted hydroxoaluminum phthalocyanine (AlPcN4) to bilayer lipid membranes was studied by fluorescence correlation spectroscopy (FCS) and intramembrane field compensation (IFC) methods. With neutral phosphatidylcholine membranes, AlPcN4 appeared to bind more effectively than the negatively charged tetrasulfonated aluminum phthalocyanine (AlPcS4), which was attributed to the enhancement of the coordination interaction of aluminum with the phosphate moiety of phosphatidylcholine by the electric field created by positively charged groups of AlPcN4. The inhibitory effect of fluoride ions on the membrane binding of both AlPcN4 and AlPcS4 supported the essential role of aluminum–phosphate coordination in the interaction of these phthalocyanines with phospholipids. The presence of negative or positive charges on the surface of lipid membranes modulated the binding of AlPcN4 and AlPcS4 in accord with the character (attraction or repulsion) of the electrostatic interaction, thus showing the significant contribution of the latter to the phthalocyanine adsorption on lipid bilayers. The data on the photodynamic activity of AlPcN4 and AlPcS4 as measured by sensitized photoinactivation of gramicidin channels in bilayer lipid membranes correlated well with the binding data obtained by FCS and IFC techniques. The reduced photodynamic activity of AlPcN4 with neutral membranes violating this correlation was attributed to the concentration quenching of singlet excited states as proved by the data on the AlPcN4 fluorescence quenching
Observation of collider muon neutrinos with the SND@LHC experiment
We report the direct observation of muon neutrino interactions with the
SND@LHC detector at the Large Hadron Collider. A data set of proton-proton
collisions at TeV collected by SND@LHC in 2022 is used,
corresponding to an integrated luminosity of 36.8. The search
is based on information from the active electronic components of the SND@LHC
detector, which covers the pseudo-rapidity region of 7.2 < \eta < 8.4,
inaccessible to the other experiments at the collider. Muon neutrino candidates
are identified through their charged-current interaction topology, with a track
propagating through the entire length of the muon detector. After selection
cuts, 8 interaction candidate events remain with an estimated
background of 0.076 events, yielding a significance of seven standard
deviations for the observed signal