Zur Emeritierung von Professor Dr. Weinmann

Ohne Zusammenfassung     

Fireside corrosion in German fossil-fuel fired power plants. Appearence,mechanism and causes

Fireside corrosion in German fossil fuel-fired boilers is described out of the view of a laboratory engaged with failure analysis. With German boiler design and German fossil fuel ferritic steels can be used for the tubing in the evaporator and superheater section. Corrosion rates, which have to be expected normally are below 10 nm/h for evaporator tubes and below 25 nm/h for superheater tubes. The appearance of corroded tubes is described and discussed in respect of the corrosion mechanism. In the evaporator section enhanced corrosion risk is mainly due to an increased chemical load, namely reducing conditions or chlorine compounds in the combustion products. In the superheater section higher than normal metal temperatures and stresses, by which the integrity of the oxide layer is destroyed, are the most important factors for increased corrosion rates.     

Paralysis of the accessory nerve following operations in the lateral triangle of the neck

In the last 3 years we had to express our opinion on 11 cases which after operations in the neck resulted in a paralysis of the N. accessorius. In 8 cases we had to state a fault of the operating surgeon. More exactness is apparently required in the operations.     

The biology of aging

Various biological aspects of the aging process are reviewed. Aging has multiple causes. First, there is the initial genetic variability in the organism. Second, there is the destructive effect of the environment. Third, there is an accumulation in the somatic cells of changes, mutations or local chemical damage. These changes incapacitate or kill individual cells, and eventually cause a decline in physiological capacity.     

Intermittent versus continuous administration of 1,25-dihydroxyvitamin D3 in experimental renal hyperparathyroidism

Conflicting results have been reported regarding the efficacy of intermittent versus continuous administration of 1,25(OH)2D3 in renal secondary hyperparathyroidism. To address this issue we examined sham-operated control rats and hyperparathyroid rats with subtotal (5/6) nephrectomy (Nx). The Nx animals (20 to 22 animals per group) were subjected to three treatment protocols: (i) solvent treatment (Nx-solvent); (ii) two i.p. injections of 35 pmol 1,25(OH)2D3 on days 0 and 4 (Nx-bolus); and (iii) continuous infusion of 70 pmol 1,25(OH)2D3 over six days via osmotic minipump (Nx-infusion). All measurements were performed six days after start of treatment. As compared to sham-operated controls, the pre-pro-PTH/beta-actin mRNA ratio was 2.04-fold higher in Nx-solvent. Both modes of administration of 1,25(OH)2D3 resulted in inhibition of PTH mRNA concentrations relative to Nx-solvent. The pre-pro-PTH/beta-actin mRNA ratio was, however, significantly lower (P < 0.05) in Nx-bolus than in Nx-infusion (Nx-bolus 1.26 higher than sham-operated controls; Nx-infusion 1.65 higher than sham-operated controls). Aminoterminal PTH (N-PTH) serum concentrations were higher in Nx-solvent (52 +/- 4 pg/ml) than in sham-operated controls (32 +/- 3 pg/ml, P < 0.01). N-PTH concentrations in Nx-bolus (38 +/- 4 pg/ml) were significantly lower than in Nx-solvent (P < 0.01) and in Nx-infusion (46 +/- 4 pg/ml, P < 0.05). Parathyroid gland weight (microgram/g body wt) was higher in Nx-solvent (1.30 +/- 0.08 pg/ml) than in sham-operated controls (0.79 +/- 0.04 pg/ml, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of bainite on the mechanical properties of dual-phase steels

The bainite-martensite-ferrite steels (tri-phase steels) were made in the laboratory by intercritical annealing, bainite transformation and oil quenching in sequence. With bainite inclusions, ductility was improved substantially without significant reduction of tensile strength. The ductility increase was found to be due to large deformation after necking and increased work-hardening.     

Renal 31-phosphorus-magnetic resonance spectral changes in experimental uremia

The pharmacokinetics of intravenous recombinant erythropoietin administered during or after dialysis were studied by multicompartmental analysis in eight patients with end-stage renal disease to determine whether significant loss of the drug occurred during the hemodialysis procedure. Each patient had five studies, one in which the erythropoietin was given near the end of a dialysis session (baseline). In the other studies, erythropoietin was administered at the beginning of hemodialysis for 4 hrs using each of four different dialysis membranes. Both two compartment and three compartment models were used. In the two compartment solutions, the mass of the exchange compartment was significantly increased in the studies done during dialysis compared with the baseline. Clearance did not change significantly among the study sessions. When a third compartment, representing the dialysis system, was added, the kinetics of the internal exchange compartment and of the dialysis system could be determined separately. At the end of 4 hrs of dialysis after the erythropoietin dose, the dialysis systems contained an average of 7% of the administered dose. It was concluded that hemodialysis immediately after erythropoietin administration does not affect the rate of erythropoietin loss, except for small losses in the dialysis system itself when it is removed at the termination of the procedure.