Neutron Diffraction and Neutron Radiography Investigation into Powder Sintering of Ti/Al and TiH2/Al Compacts

Metallurgical and Materials Transactions B - Sintering behaviors of two types of powder compact, i.e., Ti/Al and TiH2/Al, under vacuum were studied using in situ neutron diffraction, in situ...     

Periodic Exposure of Plasma-Activated Medium Alters Fibroblast Cellular Homoeostasis

Excess amounts of redox stress and failure to regulate homeostatic levels of reactive species are associated with several skin pathophysiologic conditions. Nonmalignant cells are assumed to cope better with higher reactive oxygen and nitrogen species (RONS) levels. However, the effect of periodic stress on this balance has not been investigated in fibroblasts in the field of plasma medicine. In this study, we aimed to investigate intrinsic changes with respect to cellular proliferation, cell cycle, and ability to neutralize the redox stress inside fibroblast cells following periodic redox stress in vitro. Soft jet plasma with air as feeding gas was used to generate plasma-activated medium (PAM) for inducing redox stress conditions. We assessed cellular viability, energetics, and cell cycle machinery under oxidative stress conditions at weeks 3, 6, 9, and 12. Fibroblasts retained their usual physiological properties until 6 weeks. Fibroblasts failed to overcome the redox stress induced by periodic PAM exposure after 6 weeks, indicating its threshold potential. Periodic stress above the threshold level led to alterations in fibroblast cellular processes. These include consistent increases in apoptosis, while RONS accumulation and cell cycle arrest were observed at the final stages. Currently, the use of NTP in clinical settings is limited due to a lack of knowledge about fibroblasts’ behavior in wound healing, scar formation, and other fibrotic disorders. Understanding fibroblasts’ physiology could help to utilize nonthermal plasma in redox-related skin diseases. Furthermore, these results provide new information about the threshold capacity of fibroblasts and an insight into the adaptation mechanism against periodic oxidative stress conditions in fibroblasts.     

Kinetik der VC-polymerisation: Ein Modellvergleich,II. Anwendungsbeispiele

A selection of several kinetic models for vinyl chloride polymerization in part I of this paper¹ was performed and has resulted in an optimal mathematical model, which exhibits numerous advantages for the practical work of chemical engineers, e.g. in the analysis of experimental results, in the modelling, and the optimization of polymerization reactors. Some examples are shown in this paper.     

Novel method to produce cobalt–polypyrrole catalysts for oxygen reduction reaction by dual plasma process

Platinum-free electrocatalysts based on cobalt and polypyrrole were successfully produced with a dual plasma process and characterised for the oxygen reduction reaction by cyclic voltammetry (CV). The results show that composites with catalytic activity were obtained. Furthermore, by varying the plasma process parameters, the activity of the samples was changed. Structural properties were also investigated by means of energy dispersive X-Ray spectroscopy (EDX), to obtain the elemental contents, and Fourier transform infrared spectroscopy (FT-IR) to identify the chemical structure of the films. The results indicate that, with increasing magnetron power, more and more cobalt nitrogen bonds are formed. The formation of these complexes correlates with the increase in catalytic activity.     

A theory of data-intensive software services

We introduce Abstract State Services (AS²s) as an abstraction of data-intensive services that can be made available for use by other systems, e.g. via the web. An AS² combines a hidden database layer with an operation-equipped view layer, and can be anything from a simple function to a full-fledged Web Information System or a Data Warehouse. We adopt the fundamental approach of Abstract State Machines to model AS²s and show that AS²s capture the fundamentals of approaches such as media types, meme media, SOA and web services excluding presentation issues. Then we show how tailored services can be extracted from available AS²s, combined with other AS² components and personalised to user preferences.     

Towards a theory of consistency enforcement

State oriented specifications with invariants occur in almost all formal specification languages. Hence the problem is to prove the consistency of the specified operations with respect to the invariants. Whilst the problem seems to be easily solvable in predicative specifications, it usually requires sophisticated verification efforts, when specifications in the style of Dijkstra's guarded commands as e.g. in the specification language B are used. As an alternative consistency enforcement will be discussed in this paper. The basic idea is to replace inconsistent operations by new consistent ones preserving at the same time the intention of the old one. More precisely, this can be formalized by consistent spezializations, where specialization is a specific partial order on operations defined via predicate transformers. It will be shown that greatest consistent specializations (GCSs) always exist and are compatible with conjunctions of invariants. Then under certain mild restrictions the general construction of such GCSs is possible. Precisely, given the GCSs of simple basic assignments the GCS of a complex operation results from replacing involved assignments by their GCSs and the investigation of a guard. In general, GCS construction can be embedded in refinement calculi and therefore strengthens the systematic development of correct programs. Received: 28 April 1994 / 5 November 1998