Search results for " Proton"

Gas-phase ion chemistry of protonated melatonin

2005

The gas-phase ion chemistry of protonated melatonin has been investigated by mass spectrometric (MS) techniques involving chemical ionisation, fast atom bombardment and electrospray ionisation. Either naturally- occurring or collision-induced decomposition e-D derivatives obtained by exchange with D(2)O. The analysis of experimental results allows definite pathways for the formation of the ion at m/z 174 to be assigned and sheds some more light on the overall fragmentation pathways. Experiments on labelled derivatives evidenced H-D scrambling processes during fragmentation

Fuel cell analytical modeling: Solving the trade-off between accuracy and complexity

2013

In this paper, a 5.5 kW Proton Exchange Membrane fuel cell is modeled. The proposed analytical model is described and the parameters identification procedure is further discussed. Simulation results of all three sub-models are compared to test the accuracy of each one. A comparison between simulation and experimental results is provided as well validating the modeling approach.

Exploring cell biodiversity - Neutron scattering investigation of water diffusion in complex system

2015

Scientists from biophysics, biology and medicine fields are interested in exploring and characterizing topologically cerebral tissue in order to diagnostic different diseases which affect brain in many patients [1-3]. One of the most diffuse diagnostic techniques is dMRI (diffusion magnetic resonance imaging) which extracts information about heterogeneity and asymmetries in brain tissue studying water diffusion dynamics (~80% mass constituent of tissues). The experimental limit of this technique is related to the acquisition time, TA, of the order of milliseconds. Water molecules diffuse within micrometre distance using TA as diffuse time (Eistein equation D~2TA). Cells have micrometric siz…

α decay of the πh11/2 isomer in Ir164

2014

The α -decay branch of the πh 11 / 2 isomer in 164 Ir has been identified using the GREAT spectrometer. The 164 Ir nuclei were produced using the 92 Mo( 78 Kr ,p 5 n ) 164 Ir reaction and separated in flight using the recoil ion transport unit (RITU) gas-filled separator. The measured α -decay energy of 6880 ± 10 keV allowed the excitation of the πh 11 / 2 state in 160 Re to be deduced as 166 ± 14 keV. The half-life of 164 Ir was measured with improved precision to be 70 ± 10 μ sandan α -decay branching ratio of 4 ± 2% was determined. Improved half-life and branching ratio measurements were also obtained for 165 Ir, but no evidence was found for the ground-state decays of either 164 Ir or 1…

The beta-delayed proton and gamma decay of 27P for nuclear astrophysics

2013

The creation site of 26Al is still under debate. It is thought to be produced in hydrogen burning and in explosive helium burning in novae and supernovae, and possibly also in the H-burning in outer shells of red giant stars. Also, the reactions for its creation or destruction are not completely known. When 26Al is created in novae, the reaction chain is: 24Mg(p, γ) 25Al(β +ν) 25Mg(p, γ) 26Al, but this chain can be by-passed by another chain, 25Al(p, γ) 26Si(p, γ) 27P and it can also be destroyed directly. The reaction 26mAl(p, γ) 27Si∗ is another avenue to bypass the production of 26Al and it is dominated by resonant capture. We find and study these resonances by an indirect method, throug…

Exclusive J=ψ Photoproduction off Protons in Ultraperipheral p-Pb Collisions at √sNN = 5.02 TeV

2014

Measurement of ϕ-meson production at forward rapidity in p+p collisions at √s = 510 GeV and its energy dependence from √s = 200 GeV to 7 TeV

2018

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section of ϕ ( 1020 ) -meson production at forward rapidity in p + p collisions at √ s = 510     GeV via the dimuon decay channel. The partial cross section in the rapidity and p T ranges 1.2 < | y | < 2.2 and 2 < p T < 7     GeV / c is σ ϕ = [ 2.28 ± 0.09 ( stat ) ± 0.14 ( syst ) ± 0.27 ( norm ) ] × 10 − 2     mb . The energy dependence of σ ϕ ( 1.2 < | y | < 2.2 , 2 < p T < 5     GeV / c ) is studied using the PHENIX measurements at √ s = 200 and 510 GeV and the Large Hadron Collider measurements at √ s = 2.76 and 7 TeV. The experimental results are compared to various event generator predicti…

Centrality Dependence of the Charged-Particle Multiplicity Density at Midrapidity in Pb-Pb Collisions at √sNN = 5.02 TeV

2016

The pseudorapidity density of charged particles, dNch=dη, at midrapidity in Pb-Pb collisions has been measured at a center-of-mass energy per nucleon pair of √sNN=5.02 TeV. For the 5% most central collisions, we measure a value of 1943±54. The rise in dNch=dη as a function of √sNN is steeper than that observed in proton-proton collisions and follows the trend established by measurements at lower energy. The increase of dNch=dη as a function of the average number of participant nucleons, hNparti, calculated in a Glauber model, is compared with the previous measurement at √sNN=2.76 TeV. A constant factor of about 1.2 describes the increase in dNch=dη from √sNN=2,76 to 5.02 TeV for all central…

Explicit proton transfer in classical molecular dynamics simulations.

2014

We present Hydrogen Dynamics (HYDYN), a method that allows explicit proton transfer in classical force field molecular dynamics simulations at thermodynamic equilibrium. HYDYN reproduces the characteristic properties of the excess proton in water, from the special pair dance, to the continuous fluctuation between the limiting Eigen and Zundel complexes, and the water reorientation beyond the first solvation layer. Advantages of HYDYN with respect to existing methods are computational efficiency, microscopic reversibility, and easy parameterization for any force field peerReviewed

Multifacial Recognition in Binary and Ternary Cocrystals from 5-Halouracil and Aminoazine Derivatives

2018

A systematic analysis using single crystal X-ray diffraction was performed to explore the role exerted by potential intercomponent proton-transfer reactions in the supramolecular structures of A–B cocrystals formed by 5-haloderivatives of uracil (A), coupled with 2-aminoadenine simulants (aminoazines, B). Twelve new heterodimers were synthesized in different stoichiometries and cocrystallized by solvent cogrinding followed by solution crystallization. In the binary cocrystals, uracil or 1-methyluracil with halide modification at the 5 position (F, Cl, Br, I) was coupled with amino-aromatic N-heterocycles (melamine, 2,4,6-triaminopyrimidine, 2,6-diaminopyridine) as a multivalent site for pyr…