The emptying, acid secretion, mucosal changes, and duodenogastric and gastroesophageal reflux of the intrathoracic stomach were studied in 12 patients together with the clinical course 6–12 months after esophageal replacement. Although no pyloroplasty had been performed, the emptying of a semisolid meal from the interposed stomach was significantly accelerated compared to the controls. No residual food was found in the stomach at endoscopy after an overnight fast. Distinctly accelerated gastric emptying correlated with spontaneous duodenogastric reflux across the denervated pylorus. Despite a persistent acid secretion of the vagotomized intrathoracic stomach, no pathologic gastroesophageal reflux and no esophagitis were found proximal to the cervical anastomosis. Gastric biopsies mostly revealed mild gastritis of the antral mucosa, whereas metaplasia was rare. The intrathoracic stomach does not need a drainage procedure to facilitate semisolid emptying. Postoperative reflux esophagitis is prevented by complete intrathoracic stomach transposition with cervical esophagogastrostomy.

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Herrn Professor Dr. Hanns Hofmann zum 65. GeburtstagAusgehend von der Turbulenztheorie wurde theoretisch eine Beziehung zur Berechnung der Mikromischzeit als Funktion der spezifischen Leistung, der kinematischen Viskositat, der Schmidt-Zahl und des Segregationsgrades hergeleitet. Ein Vergleich der theoretisch gefundenen Mikromischzeit mit den in der Literatur vorliegenden Angaben zur Makromischzeit ergibt, darj fur sehr kleine Behalterdurchmesser die Mikromischzeit der geschwindigkeitsbestimmende Schritt ist. Dagegen bestimmt die turbulente Makromischzeit den Mischvorgang fur grorjere Ruhrwerke mit technisch relevanten Durchmessern. An Hand von experimentellen Ergebnissen der turbulenten Geschwindigkeitsverteilungen in verschiedenen Ruhrkesseln werden fur groBe Schmidt-Zahlen Mikromischzeiten Omikro fur unterschiedliche Ruhrwerksgeometrien und Ruhrorgane sowie fur verschiedene lokale Positionen der Eduktzufuhr angegeben. Die mitgeteilten Werte fur die turbulente Mischzeit gelten jedoch nur bei geometrisch optimalen Ruhrbedingungen und konnen bei ungunstiger Anordnung die erforderliche Mischzeit uberschreiten. Bei Ablauf einer chemischen Konsekutiv-Reaktion ist mit einer wesentlichen Verschlechterung der gewunschten Produktausbeute zu rechnen.Macro-and micromixing in stirred tanks. Macromixing time, based on turbulence theory, is calculated theoretically as a function of the specific power input, the kinematic viscosity, the Schmidt number, and the degree of segregation. A comparison of the micromixing time with data for macromixing found in literature reveals that the micromixing time governs the reaction for very small vessel diameters. If the vessel diameter is greater than the critical size than the turbulent macromixing time controls the mixing process. The micromixing time Omikro is calculated by means of the experimental results of the turbulent velocity distributions in different stirred vessels for several geometrical arrangements of stirred tanks and different positions of feed input. The calculated data for turbulent mixing times are only valid for geometrically optimized stirred vessels. The necessary mixing time may increase or, if a chemical reaction of 2nd order takes place, the desired yield of the product may decrease considerably if the geometrical conditions are not taken into account.

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Abstract-Cyber-Physical Systems (CPS) are ubiquitous, motivated by the need to integrate control, computing, and communication, increasing capabilities and declining costs of the underlying technologies, and increased requirements on safety, reliability, and performance. The focus of this paper is the co-design of hybrid communication protocol and adaptive switching control that enables stabilization of multiple control applications using minimal communication resources. The hybrid protocol chosen is one that switches between timetriggered and event-triggered methods in order to realize their combined advantages. A control algorithm is co-designed along with this hybrid protocol so as to exploit the properties of the individual protocols as well as the switches between them. The controller is chosen to be adaptive in order to cope with any uncertainties that may be present. The resulting adaptive, switching controller is shown to be stable in the presence of a class of disturbances.

A one-stage model of the formation of primary bubbles is presented in which the bubble volume is deduced from an equilibrium of buoyancy, viscosity, inertia and surface tension forces. In contrast to the two-stage model, presented by Kumar and Kuloor, it was not assumed that the drag coefficient in bubble expansion can be described by the same constants as in the steady-state bubble ascent. The constants were adapted in such a way that the introduction of an additional bubble volume was not necessary. It was demonstrated that this model describes the bubble formation in gravitational and centrifugal fields equally well and, furthermore, is also applicable to structurally viscous liquids, provided that the effective shear gradient is calculated from the equilibrium of shearing and buoyancy forces. The model is based on the assumption of a constant volumetric flow rate during bubble formation and, for this reason, a minimum Froude number is necessary in analogy to the weeping limit for sieve plates. The normalized presentation permits simple operation. The possibility of applying the model to drop formation was confirmed by comparison of experimental values with those, predicted by the model.

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Fermentation under modified gravity could be of interest in application to (a) increasing productivity of growth and growth linked production with microorganisms at high cell densities and (b) increasing the productivity of highly viscous pseudoplastic polysaccharide fermentation. In both cases, higher oxygen transfer rates in centrifugal fields result in higher productivities since these fermentations are usually oxygen limited. A further aspect of fermentation under increased gravity is the reduction of foam since foam coalescence time decreases with acceleration number. On the other hand, under microgravity, shear reduction would allow growth and production even for very shear sensitive organisms. In order to carry out fermentations under modified gravity, a special type of fermenter–the centrifugal field bioreactor CFBR–has been developed at the Institute of Chemical Engineering (Head: Prof. Mersmann) of the Technical University of Munich. For the first time, exoprotein biosynthesis of lipase with S. carnosus has been carried out under sterile and controlled conditions in this novel bioreactor, in presence of increased mass forces.