Study on the morphology of the hydrophobically‐modified polyelectrolyte in aqueous solution by AFM measurements

This work focuses on the AFM study of the aggregation morphology and association mechanism of the hydrophobically‐association water‐soluble polymer P (AM‐AA‐BPAM) in aqueous solution. It shows that the P (AM‐AA‐BPAM) molecule chain, which has hydrophobic and hydrophilic ionic groups, forms the “spherical” aggregations as micelles below 0.2 g · dL^?1, and then connect each other to form the string‐like aggregations, which produce large viscosity for the polymer solution. It is also coincident with the FCS, DLS, and viscosity study result. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1175–1178, 2004     

Monitoring of chemical reactions during polymer synthesis by real‐time attenuated total reflection (ATR)–FTIR spectroscopy

The present study demonstrates in situ real‐time attenuated total reflection (ATR)–FTIR spectroscopy as a powerful tool for monitoring and analyzing different polymerization and polymer modification reactions. Thus, a metallocene catalyzed copolymerization of propene and 10‐undecene‐1‐ol, a polycondensation reaction towards polysulfone, and a modification reaction of OH end groups of hyperbranched poly(urea‐urethane) were investigated successfully. The interpretation of the development of FTIR spectra was carried out on the basis of typical vibration bands of chemical groups of the corresponding monomers and polymers in each case, e.g. of the C?C double bond of 10‐undecene‐1‐ol during the copolymerization, the new C? O? C group of polysulfone, and the new urethane end group of poly(urea‐urethane). Kinetics prediction is also under consideration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1374–1380, 2006     

Novel phosphorus-modified polysulfone as a combined flame retardant and toughness modifier for epoxy resins

A novel phosphorus-modified polysulfone (P-PSu) was employed as a combined toughness modifier and a source of flame retardancy for a DGEBA/DDS thermosetting system. In comparison to the results of a commercially available polysulfone (PSu), commonly used as a toughness modifier, the chemorheological changes during curing measured by means of temperature-modulated DSC revealed an earlier occurrence of mobility restrictions in the P-PSu-modified epoxy. A higher viscosity and secondary epoxy-modifier reactions induced a sooner vitrification of the reacting mixture; effects that effectively prevented any phase separation and morphology development in the resulting material during cure. Thus, only about a 20% increase in fracture toughness was observed in the epoxy modified with 20 wt.% of P-PSu, cured under standard conditions at 180 °C for 2 h. Blends of the phosphorus-modified and the standard polysulfone (PSu) were also prepared in various mixing ratios and were used to modify the same thermosetting system. Again, no evidence for phase separation of the P-PSu was found in the epoxy modified with the P-PSu/PSu blends cured under the selected experimental conditions. The particular microstructures formed upon curing these novel materials are attributed to a separation of PSu from a miscible P-PSu-epoxy mixture. Nevertheless, the blends of P-PSu/PSu were found to be effective toughness/flame retardancy enhancers owing to the simultaneous microstructure development and polymer interpenetration.     

Thermal Conductivity and Thermal Expansion Coefficients of the Lanthanum Rare-Earth-Element Zirconate System

To enhance the insulating properties of a thermal barrier coating, one has to focus on new materials with lower intrinsic thermal conductivity than established yttria-stabilized zirconia. Substances with pyrochlore structure were investigated. Starting from lanthanum zirconate, substitutions of the lanthanum by other trivalent rare-earth elements were made, and the thermal conductivity and the thermal expansion coefficient of the manufactured materials were measured. A complete substitution of the lanthanum led to increased thermal expansion coefficients, whereas the partial substitution did not show an appreciable effect. The thermal conductivities of the modified materials were lower than that of the pure lanthanum zirconate for temperatures <1000°C for all amounts and elements of substitution. A comparison of the observed values with calculated values of the thermal conductivities showed a relatively good agreement.     

Robber bees (Lestrimelitta limao) and their host chemical and visual cues in nest defense byTrigona (Tetragonisca) angustula (Apidae: Meliponinae)

The nest of the stingless bee,Trigona (Tetragonisca) angustula, is guarded by bees positioned in the nest entrance and others hovering in front of it. Hovering guard bees track returning foragers sideways along the last 10 cm in front of the nest, but intercept and incapacitate nest intruders by clinging with mandibles to wings and legs. When attacked by the cleptobiotic stingless beeLestrimelitta limao, the colony strengthens its aerial defense with hundreds of additional hoverers. To test our hypothesis that this reaction is due to interspecific chemical communication based on kairomone effects, we presented synthetic cephalic volatiles of both species at the nest entrance and counted the number of bees leaving the nest and taking up hovering positions. We conclude that guard bees recognizeL. limao by the major terpenoids of their volatile cephalic secretions, geranial, neral (=citral) and 6-methyl-5-hepten-2-one; other components may fine-tune this recognition. The effect of chemical stimuli is not significantly enhanced by combination with a dummy ofL. limao. Guard bees, we hypothesize, respond to this kairomone by secreting a species specific alarm pheromone; a major component of this pheromone, benzaldehyde, recruits additional bees to defend the nest.     

20 Jahre Entwicklung einer bipolaren Membranzelle für die Alkalichlorid-Elektrolyse vom Labor bis zur weltweiten Anwendung

First samples of perfluorinated cation exchange membranes were obtained in 1971. They were tested for use in the diaphragm process as a replacement for asbestos diaphragms. However, the special features of these membranes led to the decision to develop special new membrane electrolysis cells. A patent was sought for the first new cell design in 1975. After extensive material testing and many improvements, the HOECHST bipolar membrane cell was produced, consisting of an electrolyzer made up of individual elements, i.e. individual sealed electrolysis cells. Starting in 1982, this cell type was developed further in cooperation with UHDE GmbH. In 1983 it was installed for the first time in an industrial electrolysis plant. Despite strong competition, the bipolar HOECHST -UHDE membrane cell has now gained an important market share. In 1998 it will be installed worldwide in 43 electrolysis plants, with a total NaOH capacity then amounting to 2.5 million mtpa.     

Netzwerktheorie verfahrenstechnischer Prozesse

The concept of a network theory proposed in this paper provides a basis for systematically addressing questions concerning the design and operation of integrated processes. The route to a problem solution is characterised by the following steps. Modular process structuring takes place on hierarchically ordered levels by switching of components and linkage elements. The process module are switched mass- and energy-wise by means of opposing potential and current vectors. The linkage which is switched one-sidedly and is hence reaction-free is a special case. Process modelling utilises modular process structuring and assigns the structural modules to behaviour-describing modules. Process analysis examiones structural properties (stability, controllability, observability, sensitivity) and nonliner phenomena (ignition and extinction; boundary cycles; waves; chaos) of the overall process behaviour. Process design considers the layout and control of processes from holistic vantage points and aims at optimum determination of the nature, number, and switching of all the components and linkage elements of an integrated process in the light of a given production goal.     

Preface

In May 2014, shortly after Bernd Krieg-Bruckner''s 65th birthday, and shortly before he was going to retire as a professor at Universitat Bremen, Prof. Lu Ruqian proposed us to prepare a special issue of the International Journal of Software and Informatics for this occasion. However, this could not be done within just four months. Fortunately, it turned out that there would be a still better occasion to prepare such an issue: In September 2015, Bernd will finish the last international EC-funded project that he directed for three years, and will enter the life of a proper professor emeritus who has no administrative obligation any more, but can still occupy himself with whatever he finds interesting ......     

A requirements data model for product service systems

Product service systems (PSS) are bundles of physical technological elements and service elements that are integrated to solve customer problems. In practice, most components of PSS are developed independently from each other, which leads to problems with coordination of development activities and integration of PSS components. Therefore, an integrated requirements engineering for PSS is needed that deals with the involvement of developers from product engineering, software engineering, and service engineering, as well as the inherent complexity of the PSS and the development process. In a case study with the development department of a PSS provider, we analyzed requirements documents and conducted expert interviews. We identified problems in the development, for example, that requirements on different levels of abstraction are intermingled, rationales for requirements are missing, and the concretization of requirements is unclear. To solve these problems, we propose a requirements data model (RDMod) for requirements to PSS. An RDMod describes different types of requirements and the relations between them. Thus, it is a scheme for the concretization of the requirements, which especially addresses the problems of structuring the requirements, enabling traceability, and finding conflicts. We then used an analytical evaluation, a feature-based evaluation and a retrospective application with requirements analysts of the industry partner. In a joint workshop, we specified requirements for a PSS with the RDMod. In structured interviews, we analyzed the perceived advantages of the RDMod. The experts confirmed that the RDMod is applicable in their development and it provides a clear structure for the requirements and therefore helps overcoming the identified problems.