Diffractive production of charmed strange mesons by neutrinos and antineutrinos

The diffractive production of charmed strangeD _s ^* and possiblyD _s mesons by neutrinos and antineutrinos on nucleons in hydrogen, deuterium and neon targets is observed. The slope parameter of thet distribution is 3.3±0.8 (GeV)^?2. The production rate per charged current neutrino interaction with an isoscalar target times the D _s ⁺ →φτ⁺ branching fraction is (1.03±0.27)×10^?4.     

Vesicle phases from N-methyl-N-alkanoylglucamin and various co-surfactants

We have studied the phase behavior of N-methyl-N-alkanoylglucamin (GA) in water and the influence of various additives on the phases of GA. We find that GA forms a large L₁-phase that extends up to 60 wt.% of surfactant. The viscosity in this phase increases with increasing concentration and decreasing temperature. When solutions are cooled down below the Krafft-temperature (21–28 °C) T_k the samples transform into clear gels that are stable for several months. The transformation of the gel to the L₁-phase proceeds in two separate steps. Acid–base titration experiments show that the commercially produced GA is not a pure well defined compound but contains about 10% of an anionic surfactant, most likely dodecanoic acid. Solutions of GA can be continuously mixed with the anionic surfactant sodiumdodecylsulfate (SDS) or sodiumdodecylethoxysulfate (SDES) to clear and low viscous phases. Solutions of GA mixed with increasing amount of cationic surfactant tetradecyltrimethylamoniumbromide (TTABr) transform first into two phase systems and then again into low viscous single phases. The influence of several chemically different co-surfactants like n-alcohols, octanoic acid, oleic acid, 2-ethylhexylmonoglyceride (EHMG) and oleylmonoglyceride on the phase behavior of phases with 5% GA has been studied. With increasing mole fraction of the co-surfactants the well-known sequence of phases is observed, namely a L₁-phase, a two phase region L₁/L- and a L-phase. However, the properties of the L-phase for the different systems are very different. For samples with octanol the L-phase is an optically isotropic, transparent, highly viscoelastic gel. Without shear the gel like phase shows no birefringence. FF-TEM micrographs show that it consists of rather monodisperse, unilamellar vesicles with a diameter of about 500 Å. The L-phases for the other co-surfactants are turbid and have a rather low viscosity. They also contain vesicles but with a rather broad size distribution ranging from 200 to 1000 Å. For the same co-surfactant/surfactant ratio the various systems differ also in their conductivity. For some systems the conductivity is only about 20% lower than in the corresponding L₁-phase while in other systems the difference is more than a factor two. These results are an indication that small uni-lamellar vesicles contain more ionic groups at the outside than on the inside of the bilayer and that some systems are composed of uni-lamellar vesicles while others are composed of multilamellar vesicles (onions).     

Inelastic incoherent neutron scattering measurements of intact cells and tissues and detection of interfacial water

We have previously used inelastic incoherent neutron scattering spectroscopy to investigate the properties of aqueous suspensions of biomolecules as a function of hydration. These experiments led to the identification of signals corresponding to interfacial (hydration) water at low water content. A prediction from these studies was that in the crowded environment inside living cells, a significant proportion of the water would be interfacial, with profound implications for biological function. Here we describe the first inelastic incoherent neutron scattering spectroscopy studies of living cells and tissues. We find that the interfacial water signal is similar to that observed for water interacting with purified biomolecules and other solutes, i.e., it is strongly perturbed in the librational and translational intermolecular optical regions of the spectrum at 20-150 meV. The ratio of interfacial water compared to total water in cells (approximately 30%) is in line with previous experimental data for hydration water and calculations based on simple assumptions.