Methodical investigations for quantitative image analysis on cells of the female genital tract (author's transl)]

An earlier published [8] image analysis system for cytology is tested on gynecological material. At first the question for the staining method which is optimal for scanning-photometrical measurements is investigated. In addition the wavelength of the light which reproduces best the nuclear structure must be found. Feulgen-stained preparations scanned at 570nm allow a more secure sorting of superficial cells against intermediary cells than those in the classical Papanicolaou-stain at white light. Discoloring of Papanicolaou-preparations and Feulgen staining afterwards was accomplished without technical problems and there were not detectable any qualitative differences with directly Feulgen-stained preparations by means of image analysis. With this method it is possible to recognize structural changes in nuclei of vaginal epithelium during cell differentation.     

n-Channel Si-gate process for MNOS EEPROM transistors

An n-channel Si-gate process has been developed to fabricate MNOS EEPROM transistors and fast logic circuits on one chip. The technology proposed involves low thermal oxidation temperatures ≤900°C after nitride deposition, two LOCOS process steps and application of self-aligned overlapped poly-Si contacts. The MNOS memory transistors obtained have been programmed by ±25 V pulses with a write time of t_w = 10 ms and an erase time of t_e = 100 ms.The retention data have been found to be dependent on nitride thickness and threshold voltage shift, but independent of channel length and channel doping. For devices with a nitride thickness of 30.5 nm the short-term decay rate of 0.6 V/(decade of time) has been determined. Endurance testing using up to 10⁷ pulses of ±25 V, 100 μs corresponding to approx. 10⁴ write/erase cycles showed no time dependence for the decay rate over the time of 10⁵ min in which retention measurements were made.     

Bacterial hemagglutination by Neisseria gonorrhoeae

Direct bacterial hemagglutination was investigated with 20 clinical isolates of Neisseria gonorrhoeae. The hemagglutination tests were performed by both a macrotechnique with glass slides and a microtechnique with autotrays. Only organisms from form type 1 or 2 colonies caused hemagglutination. There was no statistical difference at a 10% or higher level in hemagglutination powers of type 1 and type 2 organisms, of male urethral and female cervical isolates, and of the eight major human blood types (ABO-Rh). Of seven erythrocyte species tested, only human cells were agglutinated. D-Mannose did not prevent the agglutination. Rabbit antigonococcal serum and high-titer antigonococcal human sera inhibited the hemagglutination. The results suggest the pili are the mediators of hemagglutination and that their specific agglutination of human erythrocytes may be a correlate of their adherence to human mucosal cells in natural infection. Also, although the procedure is presently insensitive, it is possible to detect human antigonococcal antibody by inhibition of direct bacterial hemagglutination.     

Zur Wirkung von Pimaricin auf Schimmelpilze und deren Aflatoxinbildung bei K?sen

Zusammenfassung Voraussetzung für die Anwendbarkeit des Pimaricins ist dessen Hitzestabilität (bis ungefähr 80° C) und die geringe Eindringtiefe (knapp 2,6 mm), so daß es für die konservierende Wirkung auf der Oberfläche der Käse für längere Zeit zur Verfügung steht. An 13 verschiedenen aflatoxinbildenden Schimmelpilzen wurde die Hemmung auf die Mycelentwicklung und damit auf die Aflatoxinbildung festgestellt, wobei die einzelnen Schimmelpilze unterschiedlich gehemmt werden. Bei Käsen war die Wirkung nicht eindeutig, da die native Oberfläche, der Käse (Rinde) nach Pimaricinbehandlung 8 Wochen vor dem Verschimmeln geschützt blieb, während daraus hergestellte Scheiben, in Pimaricinlösung getaucht, alsbald verschimmelten. Die Aflatoxinbildung selbst wird nur unterdrückt, wenn auch das Wachstum der Schimmelpilze unterbunden wird. Die Käse müssen daher möglichst frühzeitig behandelt werden, ehe es zu einer stärkeren Entwicklung der Schimmelpilze kommt. Die Aflatoxinproduktion setzt zwar erst bei einer nicht vollständigen Unterdrückung ein; es muß mit einer, wenn auch verminderten Aflatoxinbildung gerechnet werden.

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Effect of pimaricin on moulds and their aflatoxin formation in cheese

Summary The prior condition for the application of Pimaricin is its heat stability (up to 80° C) and the low penetration (around 2.6 mm), so that it is available for the effect on the cheese surface for a long period. With 13 different aflatoxin forming moulds, the inhibition on the mycel development and thereby on the aflatoxin formation was tested; the different strains were inhibited to various degrees. The effect on cheese was not definite, because the native cheese surface remained free of mould for 8 weeks after Pimaricin treatment, whereas cheese slices dipped into Pimaricin solution were covered with moulds very soon. The aflatoxin formation itself is only inhibited, if the growth of the moulds is inhibited. Therefore the cheeses have to be treated very early before strong growth of the moulds has started. The aflatoxin formation, however only starts at a certain growth period of the moulds, but at a not completed inhibition, a reduced aflatoxin formation has to be taken into consideration.

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Auszug aus: Erwin Zierer Zur Verhinderung der Aflatoxinbildung auf Käsen durch Pimaricin. Dissertation Techn. Universität München 1974.

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34. Mitt. Zur Aflatoxinbildung in Milch und Milchprodukten.     

Resolving crises through automated bilateral negotiations

We describe the development of an automated agent that can negotiate efficiently with people in crises. The environment is characterized by two negotiators, time constraints, deadlines, full information, and the possibility of opting out. The agent can play either role, with communications via a pre-defined language. The model used in constructing the agent is based on a formal analysis of the crises scenario using game-theoretic methods and heuristics for bargaining. The agent receives messages sent by its opponent, analyzes them and responds. It also initiates discussion on one or more parameters of an agreement. Experimental results of simulations of a fishing dispute between Canada and Spain indicate that the agent played at least as well as, and in the case of Spain, significantly better than a human player.     

Determination of oxidizing anions in explosive mixtures by phase transfer

Inorganic oxidizing agents are used in various explosive mixtures that are analysed by analytical chemists. Among them are dynamites, ANFO, black powder, match heads, pyrotechnical devices and home-made bombs. The crucial step in post explosion analysis is the extraction and purification of the explosive residues from the debris. A unique, fast and selective extraction technique for inorganic oxidizing agents is described in this paper. The debris are first extracted with water to yield an aqueous solution of the ions. Oxidizing anions such as nitrate and chlorate, are selectively transfered into the organic phase by the use of lipophilic quarternary ammonium cations. Other anions such as carbonate, sulphate and nitrite are not extracted into the organic phase under these conditions. The extracted anions are then identified by infra-red spectrometry and chemical spot tests.     

Pool boiling heat transfer of carbon dioxide on a horizontal tube

Carbon dioxide is again becoming an important refrigerant. While the thermophysical properties are well known there is a lack of data on its heat transfer characteristics.

In this study, heat transfer coefficients for nucleate boiling of carbon dioxide are determined using a standard apparatus for the investigation of pool boiling based on a set-up from Karlsruhe [D. Gorenflo, J. Goetz, K. Bier. Vorschlag für eine Standard-Apparatur zur Messung des Wärmeübergangs beim Blasensieden. Wärme-und Stoffübertragung 16 (1982), 69–78; J. Goetz, Entwicklung und Erprobung einer Normapparatur zur Messung des Wärmeübergangs beim Blasensieden. Dissertation Universität Karlsruhe (1980).] and built at our institute. Electrically heated horizontal cylinders with an outer diameter of 16 mm and a length of 100 mm are used as heating elements. Measurements with constant heat flux are performed for different wall materials and surface roughnesses. The heat transfer is investigated within the pressure range of 0.53≤ p ≤1.43 MPa (0.072≤ p/p_c ≤0.190) and a temperature range of −56≤ t ≤−30 °C, respectively. Heat fluxes of up to 80,000 W m⁻² are applied.

The influences of wall material and roughness on the heat transfer coefficient are evaluated separately. The obtained coefficients are compared to generally accepted correlations and to experimental results of other authors, who used similar configurations with copper tubes and carbon dioxide. These are the only previous experimental data, which could be found. Results for copper, stainless steel and aluminium as wall materials are presented.     

Integration of a three-stage expander into a CO2 refrigeration system

The inclusion of an expander with work recovery provides two advantages for transcritical CO₂ refrigeration cycles: the COP is improved and the exhaust pressure of the main compressor is lowered. Several designs of expanders have been proposed for this application and some prototypes have been tested already. In our laboratory a three-stage expander has been developed, which replaces the throttle valve of the normal refrigeration cycle and expands into the two-phase region. For optimum integration into the overall system it is proposed to install a vapour-liquid separator between the second and third stage of expansion. The vapour is guided back to the third expander stage whereas the liquid is supplied to the cooling stations via thermostatic or electronic expansion valves.     

Robocasting of dense yttria-stabilized zirconia structures

Advanced ceramic materials with complex design have become inseparable from the current engineering applications. Due to the limitation of traditional ceramic processing, ceramic additive manufacturing (AM) which allows high degree of fabrication freedom has gained significant research interest. Among these AM techniques, low-cost robocasting technique is often considered to fabricate complex ceramic components. In this work, aqueous ceramic suspension comprising of commercial nano-sized yttria-stabilized zirconia (YSZ) powder has been developed for robocasting purpose. Both fully and partially stabilized YSZ green bodies with complex morphologies were successfully printed in ambient conditions using relatively low-solid-content ceramic suspensions (<38 vol%). The sintered structures were able to retain the original morphologies with >94% of the theoretical density despite its high linear shrinkage (up to 33%). The microstructure analysis indicated that dense fully and partially stabilized YSZ with grain size as small as 1.40 ± 0.53 and 0.38 ± 0.10 μm can be obtained, respectively. The sintered partially stabilized YSZ solid and porous mesh samples (porosity of macro-pores >45%) exhibited hardness up to 13.29 GPa and flexural strengths up to 242.8 ± 11.4 and 57.3 ± 5.2 MPa, respectively. The aqueous-based ceramic suspension was also demonstrated to be suitable for the fabrication of large YSZ parts with good repeatability.