The effect of a mild base on curcumin in methanol and ethanol

Steady-state and time-resolved emission techniques were employed to study the effect of acetate, a mild base, on the luminescence of curcumin in methanol and ethanol. We found that the steady-state emission intensity as well as the average fluorescence decay time are reduced by a factor of 5 when the acetate concentration is raised to about 1.8 M. We attribute this large effect to an excited-state proton transfer (ESPT) from the acidic groups of curcumin to the acetate anion. We analyze the experimental data in terms of an ESPT reaction occurring between a photoacid and a base.     

Criteria for exact saturation and singular compactness

We introduce the class of unshreddable theories, which contains the simple and NIP theories, and prove that such theories have exactly saturated models in singular cardinals, satisfying certain set-theoretic hypotheses. We also give criteria for a theory to have singular compactness.     

Investigating excited state dynamics of salinixanthin and xanthorhodopsin in the near-infrared

Excited state dynamics of native Xanthorhodopsin (XR), of an XR sample with a reduced prosthetic group, and of the associated Carotenoid (CAR) salinixanthin (SX) in ethanol were investigated by hyperspectral Near Infrared (NIR) probing. Global kinetic analysis shows that: (1) unlike the transient spectra recorded in the visible, fitting of the NIR data requires only two phases of exponential spectral evolution, assigned to internal conversion from S(2) → S(1) and from S(1) → S(0) of the carotene. (2) The rate of the internal conversion from S(2) → S(1) in the reduced sample is well fit with a decay time of 130 fs, significantly longer than in XR and in SX, both of which are well fit with τ ≈ 100 fs. This increased lifetime is consistent with a ～30% efficiency of ET from SX to retinal in XR. (3) S(1) of salinixanthin is verified to lie ～12,700 cm(-1) above the ground electronic surface, excluding its involvement in the retinal sensitization in XR. (4) The oscillator strength of the S(1) → S(2) transition is determined to be no more than 0.16, despite its symmetry allowedness. (5) No long lived NIR absorbance decay assignable to the carotenoid S* state was detected in any of the samples. Inconsistencies concerning previously determined S(2) lifetimes and kinetic schemes used to model these data are discussed.     

Schrödinger’s cat

We show that the classical framework of probability spaces, which does not admit a model-theoretical treatment, is equivalent to that of probability algebras, which does. We prove that the category of probability algebras is a stable cat, where non-dividing coincides with the ordinary notion of independence used in probability theory.     

Goldanskii effect in quadrupole Mössbauer spectra of the 89 keV gamma ray of 156Gd

Unusual relative line intensities in the recoilless absorption spectra of the 89 keV gamma ray of ¹⁵⁶Gd in Gd₂Ti₂O₇ have been observed at various temperatures. The results prove that the unusual intensities are mainly due to lattice vibrational anisotropy.     

Points with large α-depth

We show that for every ?>0 there exists an angle α=α(?) between 0 and π, depending only on ?, with the following two properties: (1) For any continuous probability measure in the plane one can find two lines ?₁ and ?₂, crossing at an angle of (at least) α, such that the measure of each of the two opposite quadrants of angle π−α, determined by ?₁ and ?₂, is at least . (2) For any set P of n points in general position in the plane one can find two lines ?₁ and ?₂, crossing at an angle of (at least) α and moreover at a point of P, such that in each of the two opposite quadrants of angle π−α, determined by ?₁ and ?₂, there are at least points of P.     

Textured thin films grown at room temperature by laser ablation

Thin films of SrFe₁₂O₁₉, BaFe₁₂O₁₉, Pb_0.76La_{0.16 0.08}Zr_0.53Ti_0.47O₃and Sr_0.3Ba_0.7Nb₂O₆ were grown on monocrystalline silicon substrates by pulsed laser deposition using a 20-ns Nd:YAG laser (1064 nm). The deposited thin films were analyzed by X-ray diffraction in the grazing incidence configuration. The analysis showed evidence of textured growth even though the films were grown at room temperature. Emission spectroscopy was used to establish the time of flight of the species within the plasma plume. Velocities of the order of 10⁶ cm/s were obtained. The high kinetic energy of the species is thought to be responsible for the film texture, as it is released in the substrate–film system, favoring a preferential growth. For all the ablated ceramics, singly ionized species were shown to expand at higher velocities than neutrals. For ions, no consistency in the mass–speed relation was obtained, suggesting both the presence of electric fields during the plasma formation and an evaporation of the target that depends on the vapor pressure of the elements. In this way species that are firstly evaporated will be attracted strongly by fast electrons, allowing heavy ions to acquire higher velocities than lighter ones. PACS 81.15.Fg; 52.38.Mf; 68.55.Jk; 52.38.Kd; 52.70.Kz     

Hidden neuronal correlations in cultured networks

Utilization of a clustering algorithm on neuronal spatiotemporal correlation matrices recorded during a spontaneous activity of in vitro networks revealed the existence of hidden correlations: the sequence of synchronized bursting events (SBEs) is composed of statistically distinguishable subgroups each with its own distinct pattern of interneuron spatiotemporal correlations. These findings hint that each of the SBE subgroups can serve as a template for coding, storage, and retrieval of a specific information.