A New Allenic Fatty Acid in Phlomis (Lamiaceae) Seed Oil

A new allenic fatty acid, phlomic acid, 7,8-eicosadienoic acid or 20:2Δ7,8allene, has been observed in several genera of the Lamiaceae, subfamily Lamioideae. The occurrence of this fatty acid seems to be correlated with the presence of an unusual 20:1 acid, 20:1Δ9cis or 20:1n–11. Phlomic acid is apparently produced by chain-elongation of the major seed oil fatty acid, laballenic acid or 18:2Δ5,6allene.     

A learning fedforward control strategy for the concentration control of recycle reactors. Part I: Set-point control

Unknown reaction rates make concentration control in laboratory recycle reactors a difficult task, particularly when gas chromatographs or other analytical equipment with long analysis times from part of the control system. For such time-delay systems, a model-based feedforward control technique is developed which uses some kind of learning linear mapping to provide estimates of the reaction rates. Regarding the number of time steps necessary to satisfy a new set point, in a variety of simulation studies, this technique has proven superior to similar but simpler control strategies.     

Evaluation of Crystallographic Data with the Program DIAMOND

The new crystal structure information system DIAMOND is presented. It handles all kinds of crystallographic databases on PCs including SHELX files and Chemical Information Files (CIF’s). DIAMOND, because of its graphics capability, is a powerful tool for establishing structural relationships and for evaluating crystallographic data.     

On case-based learnability of languages

Case-based reasoning is deemed an important technology to alleviate the bottleneck of knowledge acquisition in Artificial Intelligence (AI). In case-based reasoning, knowledge is represented in the form of particular cases with an appropriate similarity measure rather than any form of rules. The case-based reasoning paradigm adopts the view that an Al system is dynamically changing during its life-cycle which immediately leads to learning considerations. Within the present paper, we investigate the problem of case-based learning of indexable classes of formal languages. Prior to learning considerations, we study the problem of case-based representability and show that every indexable class is case-based representable with respect to a fixed similarity measure. Next, we investigate several models of case-based learning and systematically analyze their strengths as well as their limitations. Finally, the general approach to case-based learnability of indexable classes of formal languages is prototypically applied to so-called containmet decision lists, since they seem particularly tailored to case-based knowledge processing.     

The role of reversible temper embrittlement in TM-rolling of HSLA-steels

In TM-rolling of strip and plate the mill parameters can be adjusted such that reversible temper embrittlement (RTE) happens. This leads, together with the TM-typical grain elongation, to a special fracture appearance which consists of sub-fracture (split, separation) formation starting from the main fracture plane. The lower toughness in the thickness direction is connected with a sloping shelf of the otherwise sigmoidal energy temperature curve of impact bending tests with ISO-V(CVN) specimens. It is shown how RTE can be avoided, namely by low phosphorus contents of the material and/or by low coiling temperatures at strip rolling. Accelerated cooling of plates can avoid RTE, but care must be taken not to produce plates with lower toughness.     

Evaluation of piping damage in German nuclear power plants

Information relating to piping damage in safety-relevant systems in German nuclear power plants with light water reactors (both pressurized water reactors (PWRs) and boiling water reactors (BWRs)) were analyzed with respect to the modes and the causes of damages. In general, the total range of observed piping damage is low. The incidents (82) in plants with PWRs affected mainly pipes with small diameters. Almost all damaged piping showed wall-penetrating cracks combined with leakages, which revealed the damage. Initial cracks at piping with larger diameters were discovered in isolated cases during in-service inspections. With regard to the incidents (71) in plants with BWRs, piping with small as well as large diameters was affected to different degrees. Wall-penetrating cracks combined with leakages were detected at piping with small diameters. For large-diameters pipes, cracks were indicated during in-service inspections and supplementary examinations. The results of the incident evaluations confirm the conservativeness of the safety concept chosen for the design of German nuclear power plants with light water reactors.     

The formation of hydroxy monocarboxylic acids and dicarboxylic acids by alkaline thermochemical degradation of cellulose

Treatment of cotton cellulose with 3 M sodium hydroxide solution at 260°C and 280°C gave a mixture of carboxylic acids with a yield of > 95%. The identified 50 carboxylic acids included both hydroxy monocarboxylic acids and dicarboxylic acids; their routes of formation are discussed. Among the main compounds were lactic, glycolic, 2-hydroxy-2-methylpropanoic, 2-hydroxybutanoic, 3,4-dideoxypentonic, anhydroisosaccharinic, 2,3-dideoxypentaric, and 3,4-dideoxyhexaric acids. Technical utilisation of this kind of acid mixture requires further studies. Investigations of the cyclic compounds, formed in small amounts only, resulted in identification of mainly alkyl-substituted 2-cyclopenten-1-ones.