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. 相似文献
Chemical modification of recombinant hirudin (r‐hirudin) is necessary whenever surface‐confinement to a biomaterial or biotinylation for subsequent conjugation with carriers is intended. Here, we report a modification strategy that permits chemical discrimination between r‐hirudin's amino groups and preserves its thrombin inhibitor activity. By reaction with Msc‐ONSu, protective groups were successively introduced in r‐hirudin yielding four derivatives (Msc)x‐hirudin (1 ≤ x ≤ 4) and pure fractions were isolated by ion exchange chromatography. Structure–function relationships were studied for all derivatives and revealed a decrease in activity of more than 90% as compared to unprotected r‐hirudin. MALDI‐TOF MS was used to determine the locations of the Msc groups. Furthermore, evidence was provided that r‐hirudin's N‐terminal amino group is highly important for its anti‐thrombin activity. Selective modification of the lysine residues which maintained the free N‐terminal amino group preserved the anti‐thrombin activity of r‐hirudin even after biotinylation and subsequent linkage to streptavidin or confinement to a polymer surface. 相似文献
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. 相似文献
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.
The face numbers of simplicial complexes without missing faces of dimension larger than i are studied. It is shown that among all such (d−1)-dimensional complexes with non-vanishing top homology, a certain polytopal sphere has the componentwise minimal f-vector; and moreover, among all such 2-Cohen–Macaulay (2-CM) complexes, the same sphere has the componentwise minimal h-vector. It is also verified that the l-skeleton of a flag (d−1)-dimensional 2-CM complex is 2(d−l)-CM, while the l-skeleton of a flag piecewise linear (d−1)-sphere is 2(d−l)-homotopy CM. In addition, tight lower bounds on the face numbers of 2-CM balanced complexes in terms of their dimension
and the number of vertices are established. 相似文献
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. 相似文献