Polyaniline nanotubes: conditions of formation

The courses of aniline oxidation with ammonium peroxydisulfate in aqueous solutions of strong (sulfuric) and in weak (acetic) acids, followed by temperature and acidity changes, are different. In solutions of sulfuric acid, granular polyaniline (PANI) was produced; in solutions of acetic acid, PANI nanotubes were obtained. The external diameter of the nanotubes was 100–300 nm, the internal cavity 20–100 nm, and the length extended to several micrometres. The morphology of PANI, granular or tubular, depends on the acidity conditions during the reaction rather than on the chemical nature of the acid. PANI nanotubes were also produced when aniline was oxidized in the absence of any acid. The bulk conductivity of PANI prepared in solutions of acetic acid was 0.08–0.27 S cm^?1, depending on the acid concentration. Protonated PANI prepared in sulfuric and acetic acids were deprotonated with ammonium hydroxide to obtain PANI bases and the ammonium salt of the protonating acid. FTIR spectroscopy showed the differences in the molecular structure of the PANI bases. Irrespective of whether the polymerization was performed in solutions of sulfuric or acetic acid, PANI had hydrogen sulfate counter‐ions only. The PANI morphology is thus not controlled by the nature of counter‐ions. The acidity of the reaction medium determines the protonation of monomer, oligomer and polymer species. The chemistry of aniline oxidation is likely to be affected especially by the protonation of an intermediate in the pernigraniline form. It is proposed that, in the course of aniline oxidation, pH‐dependent self‐assembly of aniline oligomers predetermines the final PANI morphology. Copyright © 2005 Society of Chemical Industry     

Safety-relevant mode confusions—modelling and reducing them

Mode confusions are a significant safety concern in safety-critical systems, for example in aircraft. A mode confusion occurs when the observed behaviour of a technical system is out of sync with the user's mental model of its behaviour. But the notion is described only informally in the literature. We present a rigorous way of modelling the user and the machine in a shared-control system. This enables us to propose precise definitions of ‘mode’ and ‘mode confusion’ for safety-critical systems. We then validate these definitions against the informal notions in the literature. A new classification of mode confusions by cause leads to a number of design recommendations for shared-control systems. These help in avoiding mode confusion problems. Our approach supports the automated detection of remaining mode confusion problems. We apply our approach practically to a wheelchair robot.     

Sexual fantasies of child molesters.

Investigated the mood accompanying sexual fantasies, and the way in which the other person in the fantasy was perceived, by 21 child molesters, 19 rapists, and 19 non-sexual offenders. Child molesters did not differ from other Ss in their perceptions of adults in their fantasies, and the adult fantasy was perceived more positively than the child fantasy. Child molesters were more likely to fantasize about children when in a negative emotional state than when in a positive mood, and these fantasies were likely to produce a negative mood state. Child molesters may fantasize about a child as an inappropriate way of coping with dysphoric moods, thus enhancing that dysphoria and leading to further inappropriate fantasies. Results suggest that sexual fantasy monitoring should become an important component in the treatment of child molesters. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modelling of selective catalytic denox reactors – strategy for replacing deactivated catalyst elements

A simulation model for denox reactors (high dust) containing honeycomb catalysts and operating at temperatures between 300 and 400 °C has been developed. The model predicts the NO_x reduction as a function of process variables (temperature, gas velocity, NO_x concentration, NH₃/NO_x ratio) as well as a function of reactor and catalyst geometry (pitch diameter, length of catalyst layer, number of layers). Model parameters such as the rate constant and the adsorption equilibrium constant of NH₃ on the catalyst surface were determined by curve fitting of experimental data obtained in a pilot test unit. Based on model calculations, it is shown that the effect of catalyst poisoning (deactivation) on NO_x reduction is not the same for every catalyst layer. The lifetimes of catalyst elements located at the inlet to the reactor appear shorter than those of the elements positioned at the outlet from the reactor. Experimental verification of this theoretical finding is required.     

The influence of tempering on cleavage fracture stress and transition behaviour of bainitic 2.25Cr1Mo steel

The effect of tempering on the mechanical properties and on the cleavage fracture stress of bainitic 2.25Cr1Mo steel was studied in a variety of structures with the Hollomon-Jaffe parameter M ranging between 18.23 × 10³ and 21.70 × 10³. The rapid decrease in yield stress and UTS was observed up to value M = 20 × 10³. For values M > 20 × 10³ the reduction of yield stress and UTS slows down. The cleavage fracture stress continuously decreases with increasing value of M. Concurrently, the changes in dislocation density and in carbide size, morphology and distribution were observed. Various theories of cleavage origin of tempered bainitic microstructures are discussed. The transition temperatures, determined from impact Charpy test, reach minimum at M = 20 × 10³. Using Orowan's theory of initiation of the brittle fracture in steels, the minimum of transition temperatures may be explained by the different reduction rates of cleavage fracture stress and yield stress with value of M.     

Irreführende Leitbilder Zum Mythos der Individualisierung durch pharmakogenetische Behandlungskonzepte. Eine kritische Anmerkung

Zusammenfassung Die prospektive Analyse der ethischen Implikationen medizinisch-technischer Innovationen läuft immer auch Gefahr, sich in den Wunschbildern von Marketingexperten zu verfangen. Vor diesem Hintergrund könnte es durchaus nützlich sein, die Erkenntnisse der Wissenschafts- und Technikforschung zur Genese und Entwicklung neuer Techniken auszuschöpfen. Dies erscheint gerade auch für die ins Phantastische weisende Zukunft der Individualisierung medikamentöser Therapie, wie man ihr häufig in der Beschreibung pharmakogenetischer Behandlungskonzepte begegnet, angebracht. Techniken, die sich noch im Entwicklungsstadium befinden und deren breite Anwendung noch einige Jahre auf sich warten lassen wird, sollten sehr sorgfältig auf ihren Realitätsgehalt und das zu erwartende Leistungspotenzial hin analysiert werden. Dazu gehört v. a. auch eine kritische Auseinandersetzung mit den Leitbildern, Visionen und Nutzenversprechen, mit denen technische Innovationen oft sehr absichtsvoll ausgestattet werden. Wird dabei die Distanz zur Rhetorik der Protagonisten der neuen Techniken nicht gewahrt, gerät die ethische Reflexion unvermittelt in die Rolle, profane Marketingstrategien wortgewandt und ideenreich zu veredeln.     

Beyond imprisonment of meaning: Technology facilitating redefining

Defining is a natural and necessary response to an ambiguous world, but causes fixation of categories and perspectives. On the basis of two earlier studies of project groups, we came to argue that redefining, and hence constructing various ways in which one perceives and understands something, enables groups to overcome imprisonment in meaning, establishing continuous development and flexibility. In this article, we first build a rationale for facilitating a process of redefining, to be taken into account when designing technology. Departing from this rationale, we discuss features of groupware technology that permit change by being flexible, and evoke redefining by engaging the user more actively. In so doing, we argue to think along new lines in the design of communication and collaboration technology. This paper proposes a specific perspective on technology, facilitating groups to engage in a productive, creative fashion of exploiting meaning potential.