Search results for "BIM."
showing 10 items of 365 documents
Observing heme doming in myoglobin with femtosecond X-ray absorption spectroscopy.
2015
International audience; We report time-resolved X-ray absorption measurements after photolysis of carbonmonoxy myoglobin performed at the LCLS X-ray free electron laser with nearly 100 fs (FWHM) time resolution. Data at the Fe K-edge reveal that the photoinduced structural changes at the heme occur in two steps, with a faster (∼70 fs) relaxation preceding a slower (∼400 fs) one. We tentatively attribute the first relaxation to a structural rearrangement induced by photolysis involving essentially only the heme chromophore and the second relaxation to a residual Fe motion out of the heme plane that is coupled to the displacement of myoglobin F-helix
Underlying A_4 Symmetry for the Neutrino Mass Matrix and the Quark Mixing Matrix
2002
The discrete non-Abelian symmetry $A_4$, valid at some high-energy scale, naturally leads to degenerate neutrino masses, without spoiling the hierarchy of charged-lepton masses. Realistic neutrino mass splittings and mixing angles (one of which is necessarily maximal and the other large) are then induced radiatively in the context of softly broken supersymmetry. The quark mixing matrix is also calculable in a similar way. The mixing parameter $U_{e3}$ is predicted to be imaginary, leading to maximal CP violation in neutrino oscillations. Neutrinoless double beta decay and $\tau \to \mu \gamma$ should be in the experimentally accessible range.
Nitroarene hydrogenation catalysts based on Pd nanoparticles glued with PDA on inorganic supports: Multivariate Curve Resolution as an useful tool to…
2021
[EN] Two green catalysts based on Pd(0) nanoparticles (Pd NPs) anchored through PDA on porous silica and magnetite have been synthesized using a generalized simple and reproducible "two-step" methodology. Both catalysts were tested for a model reaction, the hydrogenation of 4-nitrophenol using NaBH4 as the hydrogenating agent, and especially good activity has been achieved in the case of the catalysts containing magnetite as inorganic core (Pd NPs-PDA@Fe3O4). We analyzed the effect associated with the catalyst separation method (centrifugation or magnetically) that affect to the distribution and aggregation degree of the Pd NPs. In addition, we also correlate the final catalyst morphology w…
The roles for a Lewis base and MgCl2 in third-generation Ziegler-Natta catalysts
1998
Activity of a titanium catalyst supported on a bimetallic magnesium-aluminium system, involving a Lewis base [MgCl2(THF) 2 /Al(C 2 H 5 ) 2 Cl], was studied in ethylene polymerization, and the effect of the catalyst composition on the properties of the final polymer produced was investigated. Analysis and discussion of the findings covering also some part of the kinetic study, resulted in defining the roles for MgCl 2 and a Lewis base in the third-generation Ziegler-Natta catalysts. MgCl 2 forms a bimetallic complex with an organoaluminium compound, which involves also a Lewis base. Its reaction with TiCl 4 yields a very active catalyst wherein the Mg: Ti molar ratio is close to 1. This mean…
Highly trans-stereospecific Isoprene Polymerization by Neodymium Borohydrido Catalysts
2005
Highly stereospecific polymerization of isoprene was achieved using borohydridoneodymium complexes. In combination with stoichiometric amounts of dialkylmagnesium, Nd(BH4)3(THF)3 (1) and Cp*‘Nd(BH4)2(THF)2 (2) (Cp*‘ = C5Me4nPr) afford very efficient catalysts. The activity reaches 37300 (g of polyisoprene/mol of Nd)/h. Half-lanthanidocene 2 gives rise to polyisoprene, 98.5% trans-regular, the highest content yet described for a homogeneous organometallic catalyst. NMR experiments argue for the formation of bimetallic Nd(μ-BH4)Mg active species.
A Square-Planar Dinickel(II) Complex with a Noninnocent Dinucleating Oxamate Ligand: Evidence for a Ligand Radical Species
1999
[EN] The new bimetallic nickel(II) compound (PPh4)4[Ni2(2)]·6H2O (3), where H8[2] stands for N,N',N'',N'''-1,2,4,5-benzene-tetrayltetrakis(oxamic acid), has been synthesized and its crystal structure determined by single-crystal X-ray diffraction. The structure of 3 consists of [Ni2(n4:n4-2)]4- anions, tetraphenylphosphonium cations, and water molecules. Facile one-electron oxidation of the square-planar diamagnetic dinickel(II) complex [Ni2(n4:n4-2)]4- generates the metallo-radical species [Ni2(n4:n4-2·+)]3- with characteristic intra-ligand ¿cation radical transitions in the visible region (475-550 nm) as well as a typical quasi-isotropic EPR signal at g ¿ 2.0.
Activity of SiO2 supported gold-palladium catalysts in CO oxidation
2003
Abstract Bimetallic Au-Pd catalysts supported on silica with different Au/Pd atomic ratios were prepared by simultaneous reduction of palladium and gold precursors by ethanol in the presence of the polymer, polyvinylpyrrolidone (PVP). Formation of alloyed particles was detected by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and CO chemisorption measurements. The catalysts were tested in the catalytic oxidation of CO using a plug–flow reactor. The CO conversion was determined as a function of temperature. The monometallic palladium and the palladium-rich catalysts behaved quite similarly and were the most active catalysts. …
Study of the synergistic interaction between nickel, gold and molybdenum in novel modified NiO/GDC cermets, possible anode materials for CH4 fueled S…
2013
Abstract The present study concerns the structural and physicochemical characterization of novel Au–Mo–NiO/GDC cermets, alongside with measurements of their carbon tolerance. This is an investigation on whether commercially available NiO/GDC powder that is modified with Au and/or Mo can yield possible electrocatalysts as anodes for CH4 fueled SOFCs. Specifically, the performed preparation methods of deposition-precipitation and deposition-coprecipitation permitted the modification of a commercial electrocatalyst and lead to cermets that exhibit different reaction kinetics for the catalytic dissociation of CH4 and different performance for CH4 steam reforming. The most interesting structural…
Transmembrane BAX Inhibitor-1 Motif Containing Protein 5 (TMBIM5) Sustains Mitochondrial Structure, Shape, and Function by Impacting the Mitochondria…
2020
The Transmembrane Bax Inhibitor-1 motif (TMBIM)-containing protein family is evolutionarily conserved and has been implicated in cell death susceptibility. The only member with a mitochondrial localization is TMBIM5 (also known as GHITM or MICS1), which affects cristae organization and associates with the Parkinson&rsquo
Utilizzo di modelli bimodali per la descrizione della curva di ritenzione idrica del suolo
2013
L’approfondimento dell’influenza della struttura sulle caratteristiche di ritenzione idrica del suolo può contribuire alla risoluzione dei problemi legati all’eterogeneità del mezzo poroso ed anche alla quantificazione della qualità fisica del suolo. In particolare, nei suoli naturali strutturati, la presenza di un dominio dei pori strutturali (porosità inter-aggregati) e di un dominio dei pori matriciali (porosità intra-aggregati) può essere descritta mediante un’espressione della curva di ritenzione idrica di tipo bi-modale. L’indagine ha riguardato 40 suoli siciliani, per i quali è stato applicato alle misure sperimentali di ritenzione idrica il modello bimodale proposto da Dexter et al.…