Construction and properties of sub-miniature pressure pickups

Summary Two manometers for dynamical measurements (up to frequencies of the order of 50 Hz) are described which were developed for measuring blood pressure in cardiac catheterization studies and for measurements in pneumatic controllers respectively. The principle of a differential transformer was used in which the core was entirely borne by a phosphorbronze membrane. The diameter of the blood pressure manometer is 2 mm (fitting to no. 6 catheter), its length 10 mm. The most important properties of the manometers are to be found in § 4.     

Dendritic structures based on bis(hydroxymethyl)propionic acid as platforms for surface reactions

In this paper we present results related to the self-assembly of different generations of disulfide-cored 2,2-bis(hydroxymethyl)propionic acid-based dendritic structures onto gold surfaces. These molecular architectures, ranging from generation 1 to generation 3, contain removable acetonide protecting groups at their periphery that are accessible for hydrolysis with subsequent formation of OH-terminated surface-attached dendrons. The deprotection has been investigated in detail as a versatile approach to accomplish reactive surface platforms. A special focus has been devoted to the comparison of the properties of the layers formed by hydrolysis of the acetonide moieties directly on the surface and in solution, prior to the layer formation.     

Conjugate-point conditions for variational problems with delayed argument

A variational problem with delayed argument is investigated. The existing necessary conditions are first reviewed. New results, two conjugate-point conditions, are then derived for this problem. The method of proof is similar to that used by Bliss for the classical problem. An example shows that the two conditions are not equivalent, and that the first-order necessary conditions, the strengthened Legendre conditions, and the conjugate-point conditions do not in general constitute a set of sufficient conditions for the delay problem. It is shown that a special case, referred to as the separated-integrand problem, leads to considerable simplification of the results for the general problem.     

Synthetic peptides with selective affinity for apoptotic cells

The appearance of anionic phosphatidylserine (PS) in the outer monolayer of the plasma membrane is a universal indicator of the early/intermediate stages of cell apoptosis. The most common method of detecting PS on a cell surface is to use the protein annexin V; however, in certain applications there is a need for alternative reagents. Recent research indicates that rationally designed zinc 2,2'-dipicolylamine (Zn2+-DPA) coordination complexes can mimic the apoptosis sensing function of annexin V. Here, a series of fluorescently-labelled, tri- and pentapeptides with side chains containing Zn2+-DPA are prepared and shown to selectively bind to anionic vesicle membranes. Fluorescein-labelled versions of the peptides are used to detect apoptotic cells by fluorescence microscopy and flow cytometry.     

Cavity ring-down spectroscopy of the torsional motions of 1,4-bis(phenylethynyl)benzene

The torsional motions of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB), a prototype molecular wire, were studied using cavity ring-down spectroscopy in the first UV absorption band (316-321 nm). The torsional spectrum of 1,4-bis(phenylethynyl)-2,3,5,6-tetradeuteriobenzene was also recorded in the gas phase. Both spectra were successfully simulated using simple cosine potentials to describe the torsional motions. The ground-state barrier to rotation was estimated to be 220-235 cm(-1), which is similar to that of diphenylacetylene (tolane). Complementary DFT calculations were found to overestimate the torsional barrier.