Calixarene-coated water-soluble CdSe-ZnS semiconductor quantum dots that are highly fluorescent and stable in aqueous solution

A simple method for the preparation of highly fluorescent and stable, water-soluble CdSe-ZnS quantum dots is reported using calix[4]arene carboxylic acids as surface coating agents; the coating of the surface with the calixarene and the conjugation of antibodies to the quantum dots are confirmed by fluorescence correlation spectroscopy.     

Generation of entanglement between frequency bands by nonlinear fiber propagation and spectral pulse shaping

A novel fiber-based scheme for generating quadrature entanglement between a specific pair of frequency bands is proposed. The scheme is based on use of a nonlinear fiber, a spectral pulse shaper, and an adaptive feedback loop. It is numerically predicted that at least -5 dB of the quadrature entanglement will be created by preparation of an appropriate initial phase spectrum. Optimal control of the four-wave mixing terms of the Kerr Hamiltonian is crucial for improvement of the entanglement.     

Magnetic sub-band structure of HgTe under uniaxial stress

The magnetic sub-band structure of HgTe is calculated for the strain-splitting Γ₈ bands, and the lowest Landau levels of the conduction and valence bands at k_H = 0 are shown to cross each other as the magnetic field is increased. It is demonstrated that the crossing means the band inversion for the case of the compressional stress and the semimetal—semiconductor transition for the case of the tensile stress.     

Synthetic studies on β-lactam antibiotics. part 11. Completely stereocontrolled synthesis of 7α-unsubstituted 1-oxacephems from penicillins

A $\text{cis}$ intermediate $\text{3}$ was obtained by novel reductive cleavage of $\text{2}$, prepared from $\text{1}$ in $\text{6}$ steps including a new ester to ketone conversion. Regioselective bromination of $\text{3}$ followed by substitution and known conversions gave 1-oxacephems $\text{5}$.     

Use of polystyrene-supported DBU in the synthesis and alpha-selective glycosylation study of the unstable Schmidt donor of L-kedarosamine

In the alpha-glycosylation study of the unusual, 2-deoxy amino sugar of kedarcidin, polystyrene-supported DBU (PDBU) was found to be invaluable to the clean preparation of the highly labile Schmidt donor of l-kedarosamine. By further recognition that the C4-alcohol should be left free for favorable acceptor reactivity, we could for the first time successfully assemble the C13-O-alpha-glycoside of the ansamacrolide substructure of the kedarcidin chromophore. [reaction: see text]     

Well-Posedness in Sobolev Spaces for Second-Order Strictly Hyperbolic Equations with Nondifferentiable Oscillating Coefficients

The goal of this paper is to study well-posedness to strictly hyperbolic Cauchyproblems with non-Lipschitz coefficients with low regularity with respect to timeand smooth dependence with respect to space variables. The non-Lipschitz conditionis described by the behaviour of the time-derivative of coefficients. This leads to a classification of oscillations, which has a strong influence on the loss of derivatives. To study well-posednesswe propose a refined regularizing technique. Two steps of diagonalizationprocedure basing on suitable zones of the phase spaceand corresponding nonstandard symbol classes allow to applya transformation corresponding to the effect of loss of derivatives.Finally, the application of sharp Gårding's inequality allows to derive a suitable energy estimate. From this estimatewe conclude a result about C well-posedness of the Cauchy problem.