Theoretical Definition of a Functional Group and the Molecular Orbital Paradigm

It is the purpose of this review to demonstrate that the empirical classification of the observations of chemistry in terms of the properties assigned to functional groups is a consequence of and is predicted by physics. This is accomplished by showing that the atoms and functional groups of chemistry can be identified with bounded space-filling objects whose properties are defined by quantum mechanics. The quantum mechanical definition of a group is combined with a new pictorial representation of its form to obtain a unified picture which should make it eminently recognizable to chemists. This picture, when combined with the demonstrated ability of these groups to recover the measured properties of atoms in molecules, is offered as one which meets the expectations a chemist associates with the concept of a functional group. The manner in which this physical definition of a group differs fundamentally from models of functional groups based upon molecular orbital theory is discussed.     

054 Determination of clarithromycin and its R-14-hydroxy-metabolite in human serum and urine by reversed-phase HPLC and electrochemical detection

Summary Clarithromycin and its main metabolite R-OH-clarithromycin are determined in human serum and urine. The method is based on liquid-liquid extraction, reversed-phase chromatography and dual-mode coulometric detection. The method is fairly selective. No interferences were observed in samples from human volunteers. Detection limits were 0.05 mg/l serum and 1.3 mg/l urine.     

Bioactivation of self-immolative dendritic prodrugs by catalytic antibody 38C2

Self-immolative dendrimers have recently been developed and introduced as a potential platform for a multi-prodrug. These unique structural dendrimers can release all of their tail units, through a self-immolative chain fragmentation, which is initiated by a single cleavage at the dendrimer's core. Incorporation of drug molecules as the tail units and an enzyme substrate as the trigger can generate a multi-prodrug unit that will be activated with a single enzymatic cleavage. We have synthesized the first generation of dendritic prodrugs with doxorubicin and camptothecin as tail units and a retro-aldol retro-Michael focal trigger, which can be cleaved by catalytic antibody 38C2. The bioactivation of the dendritic prodrugs was evaluated in cell-growth inhibition assay with the Molt-3 leukemia cell line in the presence and the absence of antibody 38C2. The dendritic unit was applied as a platform for a heterodimeric prodrug, which achieved a remarkable increase in toxicity with its bioactivation.     

Enantioselective addition of Et2Zn to seven‐membered cyclic imines catalyzed by a (R)-VAPOL-Zn(II) complex

Various substituted dibenzo[b,f][1,4]oxazepines underwent an enantioselective alkylation with Et₂Zn catalyzed by a (R)-VAPOL-Zn(II) complex. The corresponding chiral 11-ethyl-10,11-dihydrodibenzo[b,f][1,4]oxazepine derivatives were obtained with good yields and moderate enantioselectivities. This represents the first example of enantioselective addition of Et₂Zn to cyclic aldimines.     

Competition between pairing and ferromagnetic instabilities in ultracold Fermi gases near Feshbach resonances

We study the quench dynamics of a two-component ultracold Fermi gas from the weak into the strong interaction regime, where the short time dynamics are governed by the exponential growth rate of unstable collective modes. We obtain an effective interaction that takes into account both Pauli blocking and the energy dependence of the scattering amplitude near a Feshbach resonance. Using this interaction we analyze the competing instabilities towards Stoner ferromagnetism and pairing.     

Decay properties of neutron deficient Kr isotopes

The decay properties of the neutron deficient isotopes^73–77Kr and^73–76Br have been studied at the ISOLDE facility at CERN. The total decay energiesQ, as determined fromβ ⁺ singles orβ ⁺ -γ coincidence measurements, are compared with mass formulae.     

The decay of76Kr

The decay properties of⁷⁶Kr have been investigated using mass separated samples produced by the ISOLDE facility. New information on energies, spins, parities and transition probabilities concerning levels in⁷⁶Br is presented. No direct β-feeding of the⁷⁶Br ground state was found resulting in a spin-parity assignment of 1^? to this state.     

Investigation of craze development using small-angle X-ray scattering of synchrotron radiation

The development of crazes in polycarbonate was investigated with the method of ultra-small-angle X-ray scattering (USAXS) of synchrotron radiation. Measurements at different temperatures and with different draw rates were carried out. The two-dimensional scattering patterns were analyzed by means of a fibrillar model of the craze. The geometrical parameters of the craze as a function of the macroscopic draw ratio were determined by using a curve-fitting procedure. From the measured values of the diameter and the mean distance of the fibrils, it is possible to calculate the volume fraction v_f of the fibrils directly. Additional scattering caused by submicrocracks is discussed.