CT diagnosis and differential diagnosis of renal spaca occupying lesions (author's transl)

In 76 patients with space occupying lesions of the kidneys CT scans were performed. Size, shape and localisation of the kidneys could well be demonstrated by this method. Space occupying lesions were clearly seen, and solid tumors could be differentiated from cysts. However differential diagnosis between either primary renal cell carcinoma and metastases or between malignant and benign mass lesions was not possible. There was no problem in the diagnosis of hydronephrosis where as a differentiation between inflammatory changes and solid masses proved to be difficult. CT scanning seems to be usefull in the diagnosis of renal space occupying lesions. As a non invavise method it should be performed previous to renal angiography, which thereby becomes unnecessary in many cases.     

The origins and evolution of freeze-etch electron microscopy

The introduction of the Balzers freeze-fracture machine by Moor in 1961 had a much greater impact on the advancement of electron microscopy than he could have imagined. Devised originally to circumvent the dangers of classical thin-section techniques, as well as to provide unique en face views of cell membranes, freeze-fracturing proved to be crucial for developing modern concepts of how biological membranes are organized and proved that membranes are bilayers of lipids within which proteins float and self-assemble. Later, when freeze-fracturing was combined with methods for freezing cells that avoided the fixation and cryoprotection steps that Moor still had to use to prepare the samples for his original invention, it became a means for capturing membrane dynamics on the millisecond time-scale, thus allowing a deeper understanding of the functions of biological membranes in living cells as well as their static ultrastructure. Finally, the realization that unfixed, non-cryoprotected samples could be deeply vacuum-etched or even freeze-dried after freeze-fracturing opened up a whole new way to image all the other molecular components of cells besides their membranes and also provided a powerful means to image the interactions of all the cytoplasmic components with the various membranes of the cell. The purpose of this review is to outline the history of these technical developments, to describe how they are being used in electron microscopy today and to suggest how they can be improved in order to further their utility for biological electron microscopy in the future.     

Washing Processes for Disperse Particulate Systems – Process Spectrum and Aspects for the Process Choice

Washing of disperse solid systems is a widely used and complex operation. Since the washing step is mostly integrated into other process operations, it is subject to numerous demands exceeding by far the primary demands, like a good separation result and a low specific wash liquid demand. Because of the phenomenology and limits of different washing processes it is difficult to choose an appropriate washing process. Additionally, the acting transport mechanisms of some washing processes are not yet sufficiently understood. This work gives a broad overview of the existing washing processes, the numerous parameters, and the demands they have to meet. Based on a categorization of washing processes and the classification of these processes according to their macroscopic transport phenomena, an evaluation scheme has been developed which compares and assesses existing washing processes and shows their individual limits. The present work can be used as a rough guideline for the choice of an appropriate washing process.     

Principles of reliability analysis methods applied to an emergency core cooling system

A reliability analysis is given for a model system of an emergency core cooling system of a pressurized water reactor. In order to demonstrate some basic relationships and influences on the system's failure probability the analysis deals only with some of the main-components and subsystems of the emergency core cooling system. With reference to the design basis accident, i.e. the total rupture of a main coolant line, only the low pressure system is considered. The overall system's failure probability is determined by the failure probability per demand, i.e. the unavailability of the system when called on for operation in the emergency case, and the cumulative probability of failure during the subsequent phase of residual heat removal. Detailed calculations have shown that the failure probability per demand is the leading term. Special attention is given to some parameter calculations dealing with the influence of inspection time intervals and repair procedures for different components and subsystems with respect to system failure behaviour.     

Determination of fracture mechanics properties of welded joints and comparison with the failure behaviour of wide plates

Fracture behaviour of different welded joints of 15 MnNi 6 3 and 20 MnMoNi 5 5 steel is studied by testing Charpy-V impact, fracture mechanics specimens as well as wide plate specimens of different sizes. The influence of welding conditions and stress relief heat treatment on the failure behaviour of the heat affected zones is examined. Fracture mechanics test data are used in order to predict failure loads of the wide plates by the R6-procedure and by FE-calculations.     

The PapC usher forms an oligomeric channel: implications for pilus biogenesis across the outer membrane

Bacterial virulence factors are typically surface-associated or secreted molecules that in Gram-negative bacteria must cross the outer membrane (OM). Protein translocation across the bacterial OM is not well understood. To elucidate this process we studied P pilus biogenesis in Escherichia coli. We present high-resolution electron micrographs of the OM usher PapC and show that it forms an oligomeric complex containing a channel approximately 2 nm in diameter. This is large enough to accommodate pilus subunits or the linear tip fibrillum of the pilus but not large enough to accommodate the final 6.8-nm-wide helical pilus rod. We show that P pilus rods can be unraveled into linear fibers by incubation in 50% glycerol. Thus, they are likely to pass through the usher in this unwound form. Packaging of these fibers into their final helical structure would only occur outside the cell, a process that may drive outward growth of the pilus organelles. The usher complex appears to be similar to complexes formed by members of the PulD/pIV family of OM proteins, and thus these two protein families, previously thought to be unrelated, may share structural and functional homologies.     

Deterministic job-shop scheduling problems with capacity focus

In this paper a main point of view is the exhausting of capacity in relation to a capacity focus at every node of the production graph. This exhausting process has a local and a global aspect. Optimality means a homogeneous reservation of the production nets and exhaustion of the capacity in the nodes close to the focus. Under weak conditions an optimal production sequence is achievable constructively. A classical field of application of this result is the assembly, but many other applications are possible.