Differences in Thermal Stability of Glucosinolates in Five Brassica Vegetables

The thermal stability of individual glucosinolates within five different Brassica vegetables was studied at 100°C for different incubation times up to 120 minutes. Three vegetables that were used in this study were Brassica oleracea (red cabbage, broccoli and Brussels sprouts) and two were Brassica rapa (pak choi and Chinese cabbage). To rule out the influence of enzymatic breakdown, myrosinase was inactivated prior to the thermal treatments. The stability of three glucosinolates that occurred in all five vegetables (gluconapin, glucobrassicin and 4-methoxyglucobrassicin) varied considerably between the different vegetables. The degradation could be modeled by first order kinetics. The rate constants obtained varied between four to twenty fold between the five vegetables. Brussels sprouts showed the highest degradation rates for all three glucosinolates. The two indole glucosinolates were most stable in red cabbage, while gluconapin was most stable in broccoli. These results indicate the possibilities for plant breeding to select for cultivars in which glucosinolates are more stable during processin

Transfer of BECs through discrete breathers in an optical lattice

We study the stability of a stationary discrete breather (DB) on a nonlinear trimer in the framework of the discrete nonlinear Schr\"odinger equation (DNLS). In previous theoretical investigations of the dynamics of Bose-Einstein condensates in leaking optical lattices, collisions between a DB and a lattice excitation, e.g. a moving breather (MB) or phonon, were studied. These collisions lead to the transmission of a fraction of the incident (atomic) norm of the MB through the DB, while the DB can be shifted in the direction of the incident lattice excitation. Here we show that there exists a total energy threshold of the trimer, above which the lattice excitation can trigger the destabilization of the DB and that this is the mechanism leading to the movement of the DB. Furthermore, we give an analytic estimate of upper bound to the norm that is transmitted through the DB. Our analysis explains the results of the earlier numerical studies and may help to clarify functional operations with BECs in optical lattices such as blocking and filtering coherent (atomic) beams.Comment: 8 pages, 5 figure

Spectrophotometric studies of the photolysis of diazido-bis(phosphine)-metal(II) complexes

The photolysis of mixed ligand complexes of the type MLn(N3)2 (M=Ni, Pd, Pt; L = phosphane and diphosphane ligands, respectively; n = 1, 2) was monitored by electronic spectroscopy in absorption, emission and excitation. Initial quantum yields of these complexes were measured in CH2Cl2 and EtOH in dependence on the irradiation wavelength. Photochemically formed MOIn fragments of Pd and Pt are distinguished by an intensive emission detected at 77 K. No emission was observed with respect to the appropriate NiO fragments. An initial emission at 615 nm detected by irradiating Pd(PPh3)2(N3)2 at 77 K is explained by assuming a photochemical cis/trans isomerization Quenching experiments have been performed by using Ru(bpy)3Cl2, Os(bpy)3Cl2, Re(CO)3(phen)Cl and Cr(bpy)3(ClO4)3 as sensitizers and the mixed-ligand complexes under discussion as quenchers

Tunneling in the self-trapped regime of a two-well Bose-Einstein condensate

Starting from a mean-field model of the Bose-Einstein condensate dimer, we reintroduce classically forbidden tunneling through a Bohr-Sommerfeld quantization approach. We find closed-form approximations to the tunneling frequency more accurate than those previously obtained using different techniques. We discuss the central role that tunneling in the self-trapped regime plays in a quantitatively accurate model of a dissipative dimer leaking atoms to the environment. Finally, we describe the prospects of experimental observation of tunneling in the self-trapped regime, both with and without dissipation.We wish to thank Wolfgang Muessel, Markus Oberthaler, Kaspar Sakmann, Andrea Trombettoni, Stephanos Venakides, and Tilman Zibold for helpful discussions. We are also grateful for the hospitality of Joshua E. S. Socolar and the Duke University Physics Department. This work was supported in part by Boston University. D.W. acknowledges support from the Helmholtz Association (Grant No. VH-NG-1025). (Boston University; VH-NG-1025 - Helmholtz Association)First author draf

Dynamics of entanglement in a dissipative Bose-Hubbard dimer

We study the connection between the semiclassical phase space of the Bose-Hubbard dimer and inherently quantum phenomena in this model, such as entanglement and dissipation-induced coherence. Near the semiclassical self-trapping fixed points, the dynamics of Einstein-Podolski-Rosen (EPR) entanglement and condensate fraction consists of beats among just three eigenstates. Since persistent EPR entangled states arise only in the neighborhood of these fixed points, our analysis explains essentially all of the entanglement dynamics in the system. We derive accurate analytical approximations by expanding about the strong-coupling limit; surprisingly, their realm of validity is nearly the entire parameter space for which the self-trapping fixed points exist. Finally, we show significant enhancement of entanglement can be produced by applying localized dissipation.We thank Luca d'Alessio, Pjotrs Gri. sons, and especially Anatoli Polkovnikov for helpful discussions. This work was supported in part by Boston University, by the US National Science Foundation under Grant No. PHYS-1066293, and by a grant of the Max Planck Society to the MPRG Network Dynamics. H. H. acknowledges support by the German Research Foundation under Grant No. HE 6312/1-1. We are also grateful for the hospitality of the Aspen Center for Physics. (Boston University; PHYS-1066293 - US National Science Foundation; Max Planck Society; HE 6312/1-1 - German Research Foundation)First author draf

Global Phase Space of Coherence and Entanglement in a double-well BEC

Ultracold atoms provide an ideal system for the realization of quantum technologies, but also for the study of fundamental physical questions such as the emergence of decoherence and classicality in quantum many-body systems. Here, we study the global structure of the quantum dynamics of bosonic atoms in a double-well trap and analyze the conditions for the generation of many-particle entanglement and spin squeezing which have important applications in quantum metrology. We show how the quantum dynamics is determined by the phase space structure of the associated mean-field system and where true quantum features arise beyond this `classical' approximation