Monitoring quantum oscillations with very small disturbance

We present a new scheme to detect and visualize oscillations of a single quantum system in real time. The scheme is based upon a sequence of very weak generalized measurements, distinguished by their low disturbance and low information gain. Accumulating the information from the single measurements by means of an appropriate Bayesian estimator, the actual oscillations can be monitored nevertheless with high accuracy and low disturbance. For this purpose only the minimum and the maximum expected oscillation frequency need to be known. The accumulation of information is based on a general derivation of the optimal estimator of the expectation value of a Hermitian observable for a sequence of measurements. At any time it takes into account all the preceding measurement results.     

Modification of polyetherurethane for endothelial cell seeding

Until now no synthetic polymer surface was available suitable for cardiovascular implantation which effectively prevents microthrombosis for a long time. The presented concept of our work is to develop a polymer surface to promote the growth of a durable endothelial cell monolayer which would be formed on the prothesis prior to implantation. A microporous polyetherurethane foil is being used as carrier polymer for the cell monolayer. Suitable functional groups are grafted on the polymer surface by plasma polymerization. The success of the first modification steps is followed by ESCA-analysis and scanning electron microscopy. The modified carrier polymer is the starting material for covalent binding of biopolymers which react as adhesion supporter between the synthetic polymer surface and the endothelial cells.     

Mass spectrometric characterization of telechelic prepolymers and addition polymers of DGEBA–aliphatic amines

Plasma desorption (PD) mass spectra of high molecular weight addition polymers of 2.2-bis-[4-(2.3-epoxypropoxy)phenyl]propane (DGEBA) and benzylamine show protonated molecular ions of the intact polymers and oligomer molecules. In the spectrum of a DGEBA/N,N′-dibenzyl-5-oxanonanediamine-1.9 addition polymer only fragments of the oligomers and a cyclic oligomer are observed. In both polymer spectra there is no indication for side reactions during the addition polymerization such as ether formation. Fast-atom bombardment (FAB) spectra of telechelic prepolymers having amino end groups show the regular oligomers with increasing degree of polymerization and the expected fragmentation products. Only prepolymers with epoxide end groups contain the regular prepolymers as well as side reaction products which are formed by reactions of the telechelics and DGEBA or by reaction of themselves. © 1996 John Wiley & Sons, Inc.     

Generation of ion-bound solvent clusters as reactant ions in dopant-assisted APPI and APLI

We provide experimental and theoretical evidence that the primary ionization process in the dopant-assisted varieties of the atmospheric pressure ionization methods atmospheric pressure photoionization and atmospheric pressure laser ionization in typical liquid chromatography–mass spectrometry settings is—as suggested in the literature—dopant radical cation formation. However, instead of direct dopant radical cation–analyte interaction—the broadly accepted subsequent step in the reaction cascade leading to protonated analyte molecules—rapid thermal equilibration with ion source background water or liquid chromatography solvents through dopant ion–molecule cluster formation occurs. Fast intracluster chemistry then leads to almost instantaneous proton-bound water/solvent cluster generation. These clusters interact either directly with analytes by ligand switching or association reactions, respectively, or further downstream in the intermediate-pressure regions in the ion transfer stages of the mass spectrometer via electrical-field-driven collisional decomposition reactions finally leading to the predominantly observed bare protonated analyte molecules [M?+?H]⁺.     

Bioresorbable Electrospun Fibers for Immobilization of Thiol‐Containing Compounds

For the reconstruction of functional tissue, biodegradable scaffolds providing specific surface functionality and a three‐dimensional structure matching that of the damaged tissue are needed. Fibers capable of controlling cell‐fiber interaction were produced by electrospinning of PDLLA‐block‐PEG with thiol‐reactive end groups from a solvent mixture. The hydrophilic fibers uniquely combine minimized non‐specific protein adsorption and well‐defined surface reactivity allowing controlled immobilization of peptides and proteins. Human dermal fibroblasts show adherence and proliferation on the surface of RGDC‐functionalized electrospun PDLLA‐block‐PEG fibers.

     

Analysis of the torsional spectrum of monodeuterated methanol CH2DOH

An analysis of the torsional spectrum of monodeuterated methanol CH(2)DOH is presented. Twenty nine torsional subbands have been assigned in the 20-800 cm(-1) region. The newly assigned subbands and those already available in the literature were analyzed with a theoretical approach accounting for internal rotation of an asymmetrical CH(2)D methyl group. Seventy six subband centers were reproduced with an rms value of 0.09 cm(-1). Spectroscopic parameters corresponding to the generalized inertia tensor and to the hindering potential were determined as well as rotation-torsion distortion constants.     

Metal‐template synthesis of cyclic epoxide–amine oligomers: Uncrosslinked epoxide–amine addition polymers, 47

The addition reaction of 2,2‐bis‐[4‐(2,3‐epoxypropoxy)‐phenyl]‐propane (DGEBA) and preformed complexes of metal ions and disecondary diamines led to a large quantity of cyclic epoxide–amine oligomers. As shown by gel permeation chromatographic analysis, cycles of n = 1, 2, and 3 were formed. Functional epoxide end groups of the prepared oligomers were completely missing in the IR and ¹H NMR and ¹³C NMR spectra. In the fast atom bombardment and matrix‐assisted laser desorption/ionization mass spectra, the molecular ions of the n = 1, 2, 3 cycles of DGEBA and N,N′‐dibenzyl‐5‐oxanonanediamine‐1,9 were detected at m/z = 680, 1361, and 2042. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2047–2052, 2003