Plasma-hydrogenated microwave and optoelectronic devices

Hydrogen passivation of impurities, both donors and acceptors in GaAs and in InP based materials reduces free carriers concentration and produces layers with resistivity which can be adjusted to a desired value. Such phenomena can be used in the technological process of realisation of various devices and in this paper, applications to the fabrication of GaAs and InP based optoelectronic lasers on the one hand and of GaAs field effect transistors on the other will be presented. In both cases, the technological process which has been used and the performance which has been obtained will be described.     

Synthesis and characterization of alkyl-, alkenyl-, acyl- and nitrogen-substituted derivatives of the potent phototoxin α-terthiophene

Some alkyl-, alkenyl-, acyl- and nitrogen- derivatives of α-terthienyl 1 have been synthesized in an effort to expand the potential insecticidal activity profile of this compound. The introduction of substituents was carried out directly on the α-terthienyl molecule. Three compounds were isolated in the nitration reaction and the compounds have been identified as 5-nitro-2,2′:5′,2″-terthiophene 5 , 3′-nitro-2,2′:5′,2″-terthiophene 6 and 3-nitro-2,2′:5′,2″-terthiophene 7 respectively. Preliminary results of biological acitivity are reported.     

Photoelectrochemical oxidation of water at transparent ferric oxide film electrodes

The fabrication of thin-film Fe(2)O(3) photoanodes from the spray pyrolysis of Fe(III)-containing solutions is reported along with their structural characterization and application to the photoelectrolysis of water. These films combine good performance, measured in terms of photocurrent density, with excellent mechanical stability. A full investigation into the effects that modifications of the spray-pyrolysis method, such as the addition of dopants or structure-directing agents and changes in precursor species or carrier solvent, have on the performance of the photoanodes has been realized. The largest photocurrents were obtained from photoanodes prepared from ferric chloride precursor solutions, simultaneously doped with Ti(4+) (5%) and Al(3+) (1%). Doping with Zn(2+) also shows promise, cathodically shifting the onset potential by approximately 0.22 V.     

New thoughts on old results of R.T. Seeley

In this paper we show that the L_p-realization of a vector-valued elliptic boundary value problem (, _j) admits a bounded -calculus on L_p(G;E), 1<p<, provided the top-order coefficients of are Hölder continuous. Here G denotes a domain in ⁿ with compact C^2m-boundary and E a Banach space of class . Our proof is based on an abstract perturbation result for operators admitting bounded -calculus and kernel estimates for the solution of (, _j).Mathematics Subject Classification (2000):35J45, 35K55     

A new biotinylated tris bipyridinyl iron(II) complex as redox biotin-bridge for the construction of supramolecular biosensing architectures

The bioaffine immobilization of several avidin layers on an electrode modified by a biotinylated polymer was accomplished by the first biotinylated redox bridge consisted of a tris(bipyridyl)iron(II) complex bearing six pre-oriented biotin groups.     

High detection sensitivity achieved with cryogenic detectors in combination with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Cryogenic detectors directly measure the impact energy of any impinging particle independent of its velocity. Thus a very high, mass-independent, detection efficiency is expected from their application in TOF-MS. The cryogenic detector applied here is based on a superconducting phase-transition thermometer and was implemented in a dual reflector time-of-flight mass spectrometer (N-geometry). A dilution series using standard sample preparation procedures shows that the detection limit for insulin (Mr: 5,734) can be decreased by several orders of magnitude, down to 0.5 amol on the MALDI target. Detection limits for rhM-CSF beta (Mr: 49,032) and for polyclonal IgG (Mr: ca 150,000) in the high femtomole and low picomole range, respectively, were established.