Werkstoffkennwerte für die Lebensdauerberechnung von Strukturen aus Stahlfeinblechen für den Automobilbau

Materials Data for Fatigue Life Calculation of Steel Sheet Structures for Automotive Engineering Within a joint project of the steel and automotive industry 17 steel sheet materials for automotive engineering in various delivery and forming conditions at temperatures of –40 °C, 22 °C and 100 °C were investigated. In the course of 37 test series strain controlled fatigue curves to crack initiation and stress‐strain‐curves under monotonic and cyclic loading were determined. All experimental data, hysteresis loops and determined cyclic properties are available in a database. A correlation between the mechanical properties from tensile tests and the properties from strain controlled cyclic experiments seems to be possible.     

A technique for evaluating and improving the semantic transparency of modeling language notations

Software and Systems Modeling - The notation of a modeling language is of paramount importance for its efficient use and the correct comprehension of created models. A graphical notation,...     

Ascites and suspected acute abdomen in hereditary angioedema due to C1 inhibitor deficiency

HISTORY AND CLINICAL FINDINGS: A 35-year-old man, for 8 years known to have hereditary angio-oedema with recurrent cutaneous swellings and occasional attacks of gastrointestinal pain, developed very painful, colic-like upper abdominal symptoms and frequent vomiting. INVESTIGATIONS: Routine laboratory tests were normal, except for leucocytosis of 18,200 WBC/microliter. The plasma concentrations of C1-esterase inhibitor (5.6 mg/dl) and of complement factor C4 (10.0 mg/dl) were reduced. Computed tomography revealed about 500 ml free fluid, a perihepatic effusion and definite oedematous thickening of the ileal wall. TREATMENT AND COURSE: During conservative treatment with infusions and no food by mouth the symptoms regressed. Abdominal ultrasonography was normal (no free intraabdominal fluid). Since discharge (now more than 15 months ago) the patient has been on danazole medication (200 mg/d). CONCLUSION: Recurrent gastrointestinal colics are typical of for hereditary angio-oedema and can imitate an acute abdomen. Concurrent ascites has only recently been described. Appropriate instruction of the patient and his/her medical practitioner is important to avoid unnecessary laparotomy.     

The breast cancer gene product TSG101: a regulator of ubiquitination?

Sequence analysis is a powerful tool to obtain structural and functional information about genes and their products. Here we show that TSG101, a gene subjected to somatic mutations in breast cancer, contains an amino terminal domain that is a homologue of ubiquitin conjugating enzymes (UBCs) and not, as previously proposed, DNA-binding domains. As the UBC active site residue is replaced in the TSG101 sequence in a similar manner to several other members of the UBC family, we propose a role for TSG101 in regulating the ubiquitination of short-lived gene products.     

Special Feature Learning with Computer Simulations

For successful classroom use, simulations must be integrated with other educational materials. The examples and methods described here have all been used in large introductory courses.     

Schwingungsrißkorrosion von Baustahl in Offshore-Konstruktionen bei unterschiedlichen Frequenzen und Umgebungsbedingungen

Corrosion fatigue of structural steel in offshore structures at different frequencies and environmental conditions The effect of frequency on the corrosion fatigue in seawater was investigated by use of welded and unwelded bending specimens of plate material (20 mm, StE 460) by performing mainly endurance orientated constant-amplitude tests. The test frequency was varied in a wide range (10; 1, 0,1; 0,01 s^?1). The tests were performed in air as well as in artificial seawater at free corrosion, at a cathodic protection (U_H¹ = ?650 mV) and at an extreme polarization (U_H = ?850 mV). A general grading of the endurance – given by N_fr – with respect to the frequency was evaluated in the expected sequence at free corrosion only. Thereby the frequency effect is smaller as was expected and is intensively pronounced only at the lowest frequency of 0,01 s^?1. But this frequency already results in smaller N_fr – values of welded specimens at air as well as at an extreme cathodic polarization U_H = ?850 mV and higher loading. The results of air and free seawater-corrosion show the usual small scatter whereas those of the cathodic potentials U_H = ?650 and ?850 mV are significantly larger. At U_H = ?650 mV some results mark a significantly better behaviour than in air, the other ones are inside the scatter of the results in air. At the extreme cathodic polarization (U_H = ?850 mV) some results are situated in a domain of significant shorter endurance than in air; this results from negative influence of the increased cathodically emerged hydrogen at this potential. The phase of the fatigue crack initiation is shortened by free seawater corrosion compared with an air environment; it is enhanced by a cathodic protection with U_H = ?650 mV.     

A P-loop-like motif in a widespread ATP pyrophosphatase domain: implications for the evolution of sequence motifs and enzyme activity

A conserved amino acid sequence motif was identified in four distinct groups of enzymes that catalyze the hydrolysis of the alpha-beta phosphate bond of ATP, namely GMP synthetases, argininosuccinate synthetases, asparagine synthetases, and ATP sulfurylases. The motif is also present in Rhodobacter capsulata AdgA, Escherichia coli NtrL, and Bacillus subtilis OutB, for which no enzymatic activities are currently known. The observed pattern of amino acid residue conservation and predicted secondary structures suggest that this motif may be a modified version of the P-loop of nucleotide binding domains, and that it is likely to be involved in phosphate binding. We call it PP-motif, since it appears to be a part of a previously uncharacterized ATP pyrophophatase domain. ATP sulfurylases, NtrL, and OutB consist of this domain alone. In other proteins, the pyrophosphatase domain is associated with amidotransferase domains (type I or type II), a putative citrulline-aspartate ligase domain or a nitrilase/amidase domain. Unexpectedly, statistically significant overall sequence similarity was found between ATP sulfurylase and 3'-phosphoadenosine 5'-phosphosulfate (PAPS) reductase, another protein of the sulfate activation pathway. The PP-motif is strongly modified in PAPS reductases, but they share with ATP sulfurylases another conserved motif which might be involved in sulfate binding. We propose that PAPS reductases may have evolved from ATP sulfurylases; the evolution of the new enzymatic function appears to be accompanied by a switch of the strongest functional constraint from the PP-motif to the putative sulfate-binding motif.