Separation of enantiomers of 1a,2,7,7a-tetrahydro-3-methoxynaphtha-(2,3b)-oxirane by liquid chromatography: laboratory-scale elution chromatography and modelling of simulated moving bed

The separation of enantiomers of la,2,7,7a-tetrahydro-3-methoxynaphtha-(2,3b)-oxirane (Sandoz epoxide) on cellulose triacetate HPLC columns was investigated on the laboratory scale. The performance of the columns was calculated by HEPT measurements and the slopes of the adsorption equilibrium isotherms and effective diffusivities were calculated from elution chromatographic experiments. Multi-component adsorption equilibrium isotherms were calculated from single isotherms by using the ideal adsorbed solution (IAS) model. Simulation of continuous chromatographic separation of the racemic mixture of Sandoz epoxide in a simulated moving bed was carried out and the effect of mass transfer coefficient on process performance was analysed

Kondo spin liquid and magnetically long-range ordered states in the Kondo necklace model

A simplified version of the symmetric Kondo lattice model, the Kondo necklace model, is studied by using a representation of impurity and conduction electron spins in terms of local Kondo singlet and triplet operators. Within a mean field theory, a spin gap always appears in the spin triplet excitation spectrum in 1D, leading to a Kondo spin liquid state for any finite values of coupling strength $t/J$ (with $t$ as hopping and $J$ as exchange); in 2D and 3D cubic lattices the spin gaps are found to vanish continuously around $(t/J)_c\approx 0.70$ and $(t/J)_c\approx 0.38$, respectively, where quantum phase transitions occur and the Kondo spin liquid state changes into an antiferromagnetically long-range ordered state. These results are in agreement with variational Monte Carlo, higher-order series expansion, and recent quantum Monte Carlo calculations for the symmetric Kondo lattice modelComment: Revtex, four pages, three figures; to be published in Physical Review B1, 1 July (2000

Q2Q^2--Dependence of the Gerasimov-Drell-Hearn Sum Rule

We test the Gerasimov-Drell-Hearn (GDH) sum rule numerically by calculating the total photon absorption cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ on the nucleon via photon excitation of baryon resonances in the constituent quark model. A total of seventeen, low-lying, non-strange baryon resonances are included in this calculation. The transverse and longitudinal interference cross section, $\sigma_{1/2}^{TL}$, is found to play an important role in the study of the $Q^2$ variation of the sum rule. The results show that the GDH sum rule is saturated by these resonances at a confidence level of 94%. In particular, the $P_{33}(1232)$ excitation largely saturates the sum rule at $Q^2 = 0$, and dominates at small $Q^2$. The GDH integral has a strong $Q^2$-dependence below $Q^2= 1.0 {GeV}^2$ and changes its sign around $Q^2= 0.3 {GeV}^2$. It becomes weakly $Q^2$-dependent for $Q^2 > 1.0 {GeV}^2$ because of the quick decline of the resonance contributions. We point out that the $Q^2$ variation of the GDH sum rule is very important for understanding the nucleon spin structure in the non-perturbative QCD region.Comment: revtex, 17 pages, 3 ps figs include

Caltubin, a Novel Molluscan Tubulin-Interacting Protein, Promotes Axonal Growth and Attenuates Axonal Degeneration of Rodent Neurons

Axotomized central neurons of most invertebrate species demonstrate a strong regenerative capacity, and as such may provide valuable molecular insights and new tools to promote axonal regeneration in injured mammalian neurons. In this study, we identified a novel molluscan protein, caltubin, ubiquitously expressed in central neurons of Lymnaea stagnalis and locally synthesized in regenerating neurites. Reduction of caltubin levels by gene silencing inhibits the outgrowth and regenerative ability of adult Lymnaea neurons and decreases local α- and β-tubulin levels in neurites. Caltubin binds to α- and/or β-tubulin in both Lymnaea and rodent neurons. Expression of caltubin in PC12 cells and mouse cortical neurons promotes NGF-induced axonal outgrowth and attenuates axonal retraction after injury. This is the first study illustrating that a xenoprotein can enhance outgrowth and prevent degeneration of injured mammalian neurons. These results may open up new avenues in molecular repair strategies through the insertion of molecular components of invertebrate regenerative pathways into mammalian neurons. ©2011 the authors

Prospects of Scintillating Crystal Detector in Low-Energy Low-Background Experiments

Scintillating crystal detector offers potential advantages in low-energy (keV-MeV range) low-background experiments for particle physics and astrophysics. The merits are discussed using CsI(Tl) crystal as illustrations. The various physics topics which can be pursued with this detector technology are summarized. A conceptual design for a generic detector is presented.Comment: 20 pages, 1 tables, 7 figures, submitted to Astroparticle Physic

Partial wave analysis of J/\psi \to \gamma \phi \phi

Using $5.8 \times 10^7 J/\psi$ events collected in the BESII detector, the radiative decay $J/\psi \to \gamma \phi \phi \to \gamma K^+ K^- K^0_S K^0_L$ is studied. The $\phi\phi$ invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/$c^{2}$. A partial wave analysis shows that the structure is dominated by a $0^{-+}$ state ($\eta(2225)$) with a mass of $2.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02}$ GeV/$c^{2}$ and a width of $0.19 \pm 0.03^{+0.06}_{-0.04}$ GeV/$c^{2}$. The product branching fraction is: $Br(J/\psi \to \gamma \eta(2225))\cdot Br(\eta(2225)\to \phi\phi) = (4.4 \pm 0.4 \pm 0.8)\times 10^{-4}$.Comment: 11 pages, 4 figures. corrected proof for journa

Measurements of the observed cross sections for e+e−→e^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

By analyzing the data sets of 17.3, 6.5 and 1.0 pb$^{-1}$ taken, respectively, at $\sqrt s= 3.773$, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for $e^+e^-\to \pi^+\pi^-\pi^0\pi^0$, $K^+K^-\pi^0\pi^0$, $2(\pi^+\pi^-\pi^0)$, $K^+K^-\pi^+\pi^-\pi^0\pi^0$ and $3(\pi^+\pi^-)\pi^0\pi^0$ at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay into these final states at 90% C.L..Comment: 7 pages, 2 figure

Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays

By analyzing about 33 $\rm pb^{-1}$ data sample collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we directly measure the branching fractions for the neutral and charged $D$ inclusive semimuonic decays to be $BF(D^0 \to \mu^+ X) =(6.8\pm 1.5\pm 0.7)$ and $BF(D^+ \to \mu^+ X) =(17.6 \pm 2.7 \pm 1.8)$, and determine the ratio of the two branching fractions to be $\frac{BF(D^+ \to \mu^+ X)}{BF(D^0 \to \mu^+ X)}=2.59\pm 0.70 \pm 0.25$