Quantification of the Number of Silanol Groups in Silicalite and Mesoporous MCM-41: Use of Ft-Raman Spectroscopy

Infrared and FT-Raman spectra have been obtained on pyridine adsorbed within two siliceous materials, silicalite and MCM-41. Both spectroscopic techniques detect the presence of weak physisorbed pyridine and stronger hydrogen-bonded pyridine. In particular, the FT-Raman spectra are well resolved and can be used to measure the number of pyridine molecules that interact with hydroxyl groups. for silicalite, it is found that an average of one pyridine molecule per unit cell interacts with hydroxyl groups. the number of hydroxyl groups present at the surface of porous silica materials can also be obtained using this approach. for siliceous MCM-41, it is found that the hydroxyl group concentration is about 3 mmol/g of dry solid.     

Non-Hermitian Fermion Mapping for One-Component Plasma

The two-dimensional, one-component logarithmic Coulomb gas is mapped onto a non-Hermitian fermionic field theory. At = 2, the field theory is free. Correlation functions are calculated and a perturbation theory is discussed for extending to other . A phase transition is found at the mean-field level at large . Some results are extended to spaces of constant negative curvature.     

The structure of ce-doped Bi2(MoO4)3 as determined by neutron profile refinement

The structure of Bi_1.8Ce_0.2(MoO₄)₃ has been refined with powder neutron diffraction data by the Rietveld method. The structure can be derived by severely distorting the scheelite structure (AMO₄) and is perhaps better written $\text{A}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{Ø}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{M}\text{O}{}_4$, where Ø = cation vacancy. Of the two bismuth atom sites, cerium preferentially occupies the more symmetric of the two (Bi(2) in the structure) with some cerium found in the scheelite subcell vacancies also. This site preference is understood by examining the symmetries of the two Bi sites. Crystal data: monoclinic, space group $\text{P2}{}_1\text{c}\text{, Z = 4, a = 7.697(2), b = 11.535(3), c = 11.944(3)}$, β = 115.19.     

IS THE NILE OUTFLOW FRACTAL? HURST'S ANALYSIS REVISITED

In a now classic study, Hurst [1951, 1955] found significant long-term correlations among fluctuations in Nile River outflows and described these correlations in terms of power laws. Mandelbrot's theory of random fractals [1982] later provided an axiomatic framework for Hurst's work. More recently, Bak, Tang and Weisenfeld's [1987] theory of “self-organized criticality” predicted that the fluctuations in Nile River outflows should follow power laws such as those observed by Hurst. In reexamining Hurst's data, we found small but significant deviations from these power laws, and in particular, evidence for a natural time scale of 32–128 years in global climate dynamics, possibly driven by ocean dynamics.     

Observation of B-/+-->rho-/+rho0 decays

We report the first observation of the charmless vector-vector decay process B-/+-->rho(-/+)rho(0). The measurement uses a 78 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider operating at the Upsilon(4S) resonance. We obtain a branching fraction of B(B-/+-->rho(-/+)rho(0))=[31.7+/-7.1(stat)+3.8-6.7(syst)]x10(-6). An analysis of the rho helicity-angle distributions gives a longitudinal polarization fraction of Gamma(L)/Gamma=0.95+/-0.11(stat)+/-0.02(syst). We also measure the direct-CP-violating asymmetry A(CP)(B-/+-->rho(-/+)rho(0))=0.00+/-0.22(stat)+/-0.03(syst).     

Measurements of B decays to two kaons

We report measurements of B meson decays to two kaons using 253 fb(-1) of data collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider. We find evidence for signals in B+ --> K0 K+ and B0 --> K0 K0 with significances of 3.0sigma and 3.5sigma, respectively. (Charge-conjugate modes are included.) The corresponding branching fractions are measured to be [symbol: see text](B+ --> K0 K+) = (1.0 +/- 0.4 +/- 0.1) x 10(-6) and [symbol: see text](B0 --> K0 K0) = (0.8 +/- 0.3 +/- 0.1) x 10(-6). These decay modes are examples of hadronic bd transitions. No signal is observed in the decay B0 --> K+ K-, and we set an upper limit of 3.7 x 10(-7) at 90% confidence level.     

Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.     

Multiscaling at Point J: jamming is a critical phenomenon

We analyze the jamming transition that occurs as a function of increasing packing density in a disordered two-dimensional assembly of disks at zero temperature for "Point J" of the recently proposed jamming phase diagram. We measure the total number of moving disks and the transverse length of the moving region, and find a power law divergence as the packing density increases toward a critical jamming density. This provides evidence that the T=0 jamming transition as a function of packing density is a second order phase transition. Additionally, we find evidence for multiscaling, indicating the importance of long tails in the velocity fluctuations.