The evolution equation of joint Pdf of turbulent velocity and dissipation

According to the hypothesis that the dissipation of turbulent kinetic energy satisfies log-normal distribution, a stochastic model of dissipation is provided and the Langevin model^[6] of velocity is modified. Then a joint Pdf equation of turbulent velocity and dissipation is derived. We solve numerically the joint Pdf equation using Monte Carlo method and obtain satisfactory results for decaying turbulence and homogeneous turbulent shear flow. The preliminary results show that the model is well working.     

Chelated heteroatoms in polyoxometalates and the topological equivalence of [CoIII(en)] to type II cis-dioxometal centers. Synthesis and structure of [[Co(en)(mu-OH)2Co(en)}[PW10O37Co(en)]2]8- and [K subset[Co(en)WO4][WO(H2O)](PW9O34)2]12-

The first examples of polyoxometalate structures that incorporate embedded chelated heteroatoms point to new possibilities for stereochemical control of applications.     

General nonextremal rotating black holes in minimal five-dimensional gauged supergravity

We construct the general solution for nonextremal charged rotating black holes in five-dimensional minimal gauged supergravity. They are characterized by four nontrivial parameters: namely, the mass, the charge, and the two independent rotation parameters. The metrics in general describe regular rotating black holes, providing the parameters lie in appropriate ranges so that naked singularities and closed timelike curves (CTCs) are avoided. We calculate the conserved energy, angular momenta, and charge for the solutions, and show how supersymmetric solutions arise in a Bogomol'nyi-Prasad-Sommerfield limit. These have naked CTCs in general, but for special choices of the parameters we obtain new regular supersymmetric black holes or smooth topological solitons.     

Observation of high mass electron-positron pairs produced in proton-proton collisions at the CERN ISR

In an experiment performed at the CERN Intersecting Storage Rings (ISR), 11 e⁺e^? pairs of high invariant mass value (> 2.5 GeV/c²) have been observed. Of these events, 9 can be interpreted as arising from the reaction p + p → J (3.1) + anything. the cross-section for this reaction is estimated and compared with the result obtained at lower centre-of-mass energies.     

Efficient violet upconversion signal from a fluoride fiber doped with erbium

When an erbium-doped fluoride fiber was pumped with a red dye laser beam that resonantly excites the (4)F(9/2) state, we detected efficient violet upconversion emission from the (2)P(3/2) state that is much stronger than the green upconversion emission from the (4)S(3/2) state. Such unusual violet emission was found to be due to a three-photon excitation process.     

Syntheses,structural studies and spectroscopic characterisation of pyridyl–phthalimide complexes of fac-(CO)3ReI-diimines

The mono-dentate ligands, 3-aminomethyl-N-phthalimido-pyridine (L¹) and 3-amino-N-phthalimido-pyridine (L²), were synthesised using a solvent-free melt method. These ligands were then used to access three pairs of functionalised luminescent Re^I complexes of the generic type fac-{Re(CO)₃(diimine)(Lⁿ)}(BF₄) [where diimine = 4,4′-dimethyl-2,2′-bipyridine (dmb); 2,2′-bipyridine (bpy); 1,10-phenanthroline (phen)]. X-ray crystallography has been used to structurally characterise five of the complexes showing that in the cases of the L¹ species the phthalimide unit is adjacent to and co-planar with the coordinated diimine ligand. Solution state UV–Vis absorption, electrochemistry and IR studies confirm that the proposed formulations and coordination modes exist in solution. The photophysical studies show that the visible emission from each of the six complexes is ³MLCT at room temperature. Within each pair of complexes the precise energy of the emission was subtly dependent upon the axial ligand, Lⁿ with luminescence lifetimes in the range 121–288 ns.     

Energy disposal in gas-phase nucleophilic displacement reactions

The partitioning of reaction exothermicity into relative translational energy of the products of gas-phase S_N2 (F^? + CH₃Cl) and nucleophilic aromatic substitution (F^? + C₆H₅Cl) reactions has been investigated using kinetic energy release Fourier transform ion cyclotron resonance spectroscopy. The chloride product ion is observed to be highly translationally excited for the S_N2 reaction, indicating a cold internal energy distribution for the products. For the chlorobenzene reaction the products are not generated with large translational energies. The results are compared with a statistical model. Ion-intensity profiles for the CH₃Cl reaction deviate significantly from the statistical model whereas the chlorobenzene results are consistent with this model. The kinetic energy release for the CH₃C1 reaction is compared with energy-disposal results for the photodissociation and dissociative electron-attachment processes of halomethanes. In all three cases a node in the molecular orbital between the carbon atom and the departing halogen results in a repulsive energy release. Ion-retention curves for the nucleophilic aromatic substitution reaction are consistent with the existence of a long-lived ion-dipole complex on the exit channel for this reaction.     

Deep Red Emitting Heteroleptic Ir(III) Complexes that Incorporate Unsymmetrical 4-quinoline Carboxylic Acid Derived Ligands

Six disubstituted ligands based upon 2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids have been synthesised, solvent-free, in one step from a range of commercially available isatin derivatives. These species behave as ancillary chelating ligands for Ir(III) complexes of the form [Ir(C^N)₂(N^N)]PF₆ (where C^N=cyclometalating ligand; N^N=2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids). An X-ray crystallographic study on one complex shows a distorted octahedral geometry wherein a cis-C,C and trans-N,N coordination mode is observed for the cyclometalating ligands. DFT calculations predicted that variations in N^N ligand from 2,2′-bipyridine to L^{1 – 6} should localise the LUMO on to the Lⁿ ligand and that the complexes are predicted to display MLCT/LLCT character. All complexes displayed luminescence in the deep red part of the visible region (674–679 nm) and emit from triplet states, but with little apparent tuning as a function of L^{1 – 6} . Further time-resolved transient absorption spectroscopy supports the participation of these triplet states to the excited state character.