Ausscheidungsteilchen in hochkohlenstoffhaltigem chromlegiertem Stahl

Röntgenographische Untersuchungen sowie elektronenmikroskopische Durchstrahlungs- und Feinbereichsbeugungs-Untersuchungen an Dünnschliffen aus einem Stahl mit rd. 1,45% G und 1,4% Cr nach martensitischem Härten und Anlassen bis 10 000 min bei 40 bis 100°C zur Ermittlung der beim Anlassen auftretenden Ausscheidungsphasen (Kohlenstoff und Karbide). Folgerungen über deren morphologische und kristallographische Merkmale.     

Prozeßsystemtechnik — Gedanken zu Notwendigkeit und Inhalt einer akademischen Lehre

Process System Engineering. Thoughts on the need for and curriculum of an academic course of instruction . The raw material, energy, and environmental situation, international competition, and the decline in product innovation are increasingly casting doubts on conventional processes and their realization. Hence, in the future-training of chemical engineers a reasonable amount of time should be devoted to the study of system facets, i. e. to thinking and acting in complex systems of interrelationships. Under the general leading ?Process System Engineering”? those activities are discussed which are relevant to the design and planning of chemical engineering systems (process synthesis) and the mathematical analysis of a given system (process analysis). Process synthesis is the creative facet of project planning involving several methodologies. Process analysis embraces steady-state and non-steady state mass- and energy-balancing and the mathematical evaluation of various process alternatives on the basis of operating costs and investment as well as the simulation of operational behaviour and optimization of process configurations using mathematical models. The following article discusses a selection of points which should play an important part in the teaching of process synthesis and process analysis and considers some examples by way of illustration.     

Thermal Conductivity of a Particulate-Diamond-Reinforced Cordierite Matrix Composite

The effect of 15 vol% particulate diamond reinforcement on the thermal conductivity of a cordierite matrix was studied as a function of diamond particle size from room temperature to 700°C. The thermal conductivity was found to increase with increasing particle size to a maximum increase of about 75% for a mean particle size of 50 μ. The particle size effect was found to be more pronounced at the lower temperatures than at the higher temperatures. The observed effect of particle size and temperature was attributed to the existence of an interfacial thermal barrier, possibly resulting from interfacial phonon scattering, with a positive temperature dependence of the interfacial thermal conductance. The magnitude of this conductance suggested strong adhesion between the diamond and cordierite.     

Evaluation of Vitek GPS-SA card for testing of oxacillin against borderline-susceptible staphylococci that lack mec

Fifty-one Staphylococcus aureus strains lacking mec for which oxacillin MICs were 1 to 8 micrograms/ml were tested against oxacillin and the combination of oxacillin and clavulanic acid with the Vitek GPS-SA card, the reference broth microdilution method, and the oxacillin agar screen plate. Of the 51 strains, 44 (86%) did not grow on the oxacillin agar screen plate, broth microdilution MICs were 1 to 2 micrograms/ml, and GPS-SA card MICs were < or = 2 micrograms/ml, with the exception of 3 strains that failed to grow in the card on repeated attempts. Another seven strains did grow on the oxacillin agar screen plate. For four of the latter group of strains, oxacillin broth microdilution MICs were > 4 micrograms/ml and GPS-SA card MICs were > or = 4 micrograms/ml; for the other 3 strains, corresponding MICs were 4 and < or = 2 micrograms/ml, respectively. The GPS-SA card classified 86% of strains as oxacillin susceptible.     

Influence of the processing conditions on morphology and deformation behavior of poly(butylene terephthalate) (PBT)

This paper discusses the effect of varying cooling rates during crystallization on the spherulitic structure of poly(butalene terephthalate). Light microscopy, transmission electron microscopy, and differential scanning calorimetry were used to examine specimens. The mechanical properties of the polymers studied were examined by a variety of methods.