A Parametric Reactive Distillation Study: Economic Feasibility and Design Heuristics

The integration of reaction and distillation into a single column is called reactive distillation or catalytic distillation. Reactive distillation provides many benefits such as reduced capital and operating costs, circumventing non-reactive azeotropes, and overcoming equilibrium limited reactions. Industry has been successful in applying reactive distillation; however the integration of reaction and distillation is not applicable for all reaction/separation systems and it is not always clear when reactive distillation is a feasible design alternative. Heuristics or rules-of-thumb are an integral part of process systems engineering and are used to provide initial guidance and insight for the analysis of process feasibility and conceptual design. Heuristics are developed from experience, computer simulations, and process data and usually are simple rules that greatly reduce the effort required to determine initial process feasibility and design. Due to the complex interactions that occur when combining reaction with distillation, heuristics for reactive distillation have been slow to develop. In order to generate a set of heuristics for single column reactive distillation, a parametric study was conducted for ideal chemical reactive systems involving one or two reactants and one or two products. Each reactive system was divided into regions of similar component boiling point ordering which were expected to exhibit similar reactive distillation characteristics. The parametric study focused on the affects that changing relative volatility and chemical reaction equilibrium have on reactive distillation. Simulation results were used to develop a set of heuristics which outline the initial reactive distillation column design required to produce a desired product as well as the limits of economic feasibility. The generation of these heuristics was facilitated by a graphical representation which relates economic feasibility to reaction equilibrium constant, volatility ordering, relative volatility, and reflux ratio. The graphical representations are a useful screening tool which can be used to identify systems likely to benefit from single column reactive distillation. These heuristics were verified using real chemical reactive systems that are available in the reactive distillation literature

Clinical Significance of Credé's Prophylaxis in Germany at Present

The introduction of silver nitrate for prophylaxis of gonococcal ophthalmia neonatorum is one of the milestones of preventive medicine. However, in our time an increasing necessity to review Credé's prophylaxis from both a human rights and a medical standpoint is required. The chairmen of the obstetrics and gynecology departments of the German university hospitals were questioned to learn about their policy and experience. Data were provided by 22 of 28 consulted institutions, representing 31,700 annual deliveries seen over a mean period of 5.5 years. Ocular prophylaxis was in use in 16 (73%) of the reporting hospitals (1% silver nitrate in 14 and gentamicin in 2). A nonspecific conjunctival reaction occurred in 5–10% of the newborns, but no major side effects were seen. Non-gonococcal ophthalmia neonatorum was observed in less than 0.1%; however, institutions without a preventive policy reported up to a 5% incidence of neonatal conjunctivitis, mostly due to Staphylococcus aureus, as well as Neisseria gonorrhoeae in two newborns. Application of silver nitrate is considered a necessary prophylactic measure and safe if it is properly administered. However, major efforts should be directed toward its replacement by alternative antiseptic substances as well as toward chlamydial screening and therapy in pregnancy

The architecture of a video image processor for the space station

The architecture of a video image processor for space station applications is described. The architecture was derived from a study of the requirements of algorithms that are necessary to produce the desired functionality of many of these applications. Architectural options were selected based on a simulation of the execution of these algorithms on various architectural organizations. A great deal of emphasis was placed on the ability of the system to evolve and grow over the lifetime of the space station. The result is a hierarchical parallel architecture that is characterized by high level language programmability, modularity, extensibility and can meet the required performance goals

Nonwoven geotextile scour protection at offshore wind parks, application and life cycle assessment

The sand surrounding a construction (e.g. monopile) for mounting an offshore wind turbine, could be scoured due to the affection of natural water flow at the ocean floor. To tackle the phenomena, scour protection methods have been established. Mostly rocks are used, but also one alternative, described in this paper, has been used already successfully: The installation of Geotextile Sand Containers

Quantitativer Nachweis von humanem Choriongonadotropin (hCG) im Menstrualblut bei verschiedenen gynäkologischen Entitäten

Aufgrund der von Alexander et al. 1997 erstmals beschriebenen Expression von hCG im sekretorisch transformierten Endometrium der Frau im reproduktiven Alter ließ sich vermuten, dass das hCG auch im Menstrualblut nachweisbar sein müsste und mit herkömmlichen Methoden bestimmt werden könnte. Von 2003 bis 2006 wurden bei 227 Frauen 272 Menstrualblutproben zwischen dem 1. bis 6. Zyklustag untersucht. Des Weiteren wurde untersucht, ob ein Zusammenhang zwischen den hCG-Werten und bestimmten gynäkologischen Erkrankungen besteht. Mit dieser Arbeit konnten wir erstmals nachweisen, dass hCG bei gesunden Frauen ein Bestandteil des Menstrualblutes ist. Die Messungen erfolgten mittels Elektrochemilumineszenz-Immunoassay (ECLIA) der Firma Roche, Mannheim. Dass es sich bei dem im Menstrualblut nachgewiesenen hCG tatsächlich um ein humanes Choriongonadotropin und nicht um einen unspezifischen Nachweis eines Glykoproteins gehandelt hat, wurde durch Western Blot-Untersuchungen belegt. Aus 29 Punktaten von Endometriosezysten, die per laparoskopiam gewonnen wurden, waren ebenfalls hCG-Bestimmungen durchgeführt worden. Um Frühschwangerschaften auszuschließen, wurde parallel dazu immer das hCG im Serum bestimmt. Erhöhte hCG-Werte zeigten sich bei Erkrankungen mit einer gesteigerten Proliferationsrate, wie z.B. bei der Endometriose und beim Uterus myomatosus. In weiteren Untersuchungen müsste geklärt werden, ob es möglich ist, für die hCG-Bestimmung sowohl im Serum als auch im Menstrualblut einen spezifischen ß-hCG 6/7-Kit herzustellen. Wir konnten erstmals zeigen, dass bei 100 % der Frauen hCG im Menstrualblut nachweisbar ist. Am 3. Zyklustag wurde die höchste Konzentration bestimmt