Biomedical subjects

H Wenner

Publications and source records attributed to H Wenner.

3 recordsLinked to original sources

PubMed2000

Violene/cyanine hybrids as electrochromics part 2: tetrakis(4-dimethylaminophenyl)ethene and its derivatives

The general structure of violene/cyanine hybrids (see below) is exemplified by tetrakis(4-dimethylaminophenyl)ethene 1(RED) its vinylogue 2(RED) and its diazavinylogue 3(RED). As judged from their cyclic voltammograms and spectroelectrograms, oxidation occurs perfectly reversible by loss of two electrons creating closed shell systems 1-3(OX)+2 with strong bathochromic shifts (Michlers hydrol blue moieties). ESR spectra indicate only minor amounts of radical cations. At much higher potentials by another reversible loss of two electrons (-->1-3(OX)+4) the long wavelengths absorptions are replaced by shorter ones. In system 4, containing two 4-dimethylaminophenyl units only, the violene character is better preserved since oxidation occurs stepwise by single electron transfer up to 4(OX)+4. These results are backed by theoretical calculations for 1-4, demonstrating the strong geometrical differences between the various oxidation levels. Besides, new types of cyclic structures for 1-4(OX)+4 are indicated by these calculations: For systems 1-3 cyclic structures for tetracations have been found to be more stable by 3-20 kcalmol(-1) than acyclic structures, whereas for system 4 the acyclic structure is more stable by about 22 kcalmol(-1). The redox behavior of systems 1-4 is of general importance for electrochromic systems.

Journal Article↗

PubMed1997

Software validation.

This article examines the requirements of EN 60601-1-4, which states that risk management is an integral part of the development of software for medical devices. Food and Drug Administration regulations are also compared to the requirements of the Medical Device Directive to provide guidance on developing software for the European and US markets.

Equipment and Supplies↗

PubMed1980

[Andrenogenital syndrome (author's transl)].

Radioimmunologically estimated diurnal profiles of 17-hydroxyprogesterone (17-OHP) showed clearly increased values in 15 patients with adrenogenital syndrome aged 9-19 years who had been treated for at least 4 1/2 years with cortisol. Increases were pronounced in the morning: at 8 hours 58.6 nmol/l, at 12 hours 22.2 nmol/l, at 18 hours 23.7 nmol/l on average. By changing cortisol medication, in particular due to split doses, morning 17-OHP peak values could be lowered and the whole daily profile could be improved: at 8 hours 17.9 nmol/l, at 12 hours 9.3 nmol/l, at 18 hours 8.1 nmol/l on average. The total cortisol dosage had to be increased only marginally from an average of 26.7 to 30 mg/m2 body surface, however, the evening dosage was increased from 20% to 38% on average of the total dose. Measurement of serum 17-OHP diurnal profile is thus advantageous in treatment of adrenogenital syndrome with cortisol when compared to values obtained from 24-hour urine collections.

Adolescent↗