Phospholipids of the pulmonate land snailCepaea nemoralis (L.)

The phospholipids of the snailCepaea nemoralis, comprising the major lipid fraction (65%) in this terrestrial pulmonate, were investigated by thin-layer and column chromatography. Detailed gas chromatographic analyses of liberated fatty acid fractions and amino acid analyses of the water soluble moieties of isolated phospholipid classes were carried out. Phosphatidyl choline (47%) and phosphatidyl ethanolamine (21%) were found to be the predominant phospholipid classes, while phosphatidyl serine (8%), phosphatidyl inositol (6%), diphosphatidyl glycerol (3%), ceramide amino-ethylphosphonate (7%), lysophosphatidyl choline (1%), and phosphatidic acid (1%) were present in lesser amounts. In the phosphatidyl ethanolamine and phosphatidyl serine fractions, minor quantities of plasmalogen analogues were detected. Fatty acid profiles of the various phospholipid classes appeared to be strikingly diverse, e.g. a characteristic component, such as linoleic (18∶2ω6) acid, ranging from 3–54%. In vivo radioisotope studies using 1-¹⁴C-acetate demonstrated the high biosynthetic rate of all phospholipid classes and their respective fatty acid fractions. Results are discussed in relation to data on the phospholipids from other invertebrate species.     

A Hierarchical structure of key performance indicators for operation management and continuous improvement in production systems

Key performance indicators (KPIs) are critical for manufacturing operation management and continuous improvement (CI). In modern manufacturing systems, KPIs are defined as a set of metrics to reflect operation performance, such as efficiency, throughput, availability, from productivity, quality and maintenance perspectives. Through continuous monitoring and measurement of KPIs, meaningful quantification and identification of different aspects of operation activities can be obtained, which enable and direct CI efforts. A set of 34 KPIs has been introduced in ISO 22400. However, the KPIs in a manufacturing system are not independent, and they may have intrinsic mutual relationships. The goal of this paper is to introduce a multi-level structure for identification and analysis of KPIs and their intrinsic relationships in production systems. Specifically, through such a hierarchical structure, we define and layer KPIs into levels of basic KPIs, comprehensive KPIs and their supporting metrics, and use it to investigate the relationships and dependencies between KPIs. Such a study can provide a useful tool for manufacturing engineers and managers to measure and utilize KPIs for CI.     

Modelling acid attack on concrete: Part I. The essential mechanisms

At present, a computer model is being developed to predict the corrosion of concrete construction components subjected to acidic solutions with pH values ranging between 4.0 and 6.5, i.e. exposure classes XA3 down to XA1 according to DIN EN 206-1. The concrete may contain Portland cement based binders with dissolvable or acid resistant aggregate. Calcium aluminate cement is also considered. The concrete degradation is characterised by a corroded layer of high porosity whose thickness is determined by the combination of dissolution, precipitation and transport processes which depend on cement chemical composition, binder reactivity, aggregate reactivity, grading curve as well as concrete composition. It is also intended to include the effect of abrasion. The model components will be described in detail in forthcoming publications.     

Beziehungsmarketing aus Kundensicht

Relationship Marketing from a Customer’s Perspective Companies need a wealth of personal data in order to address customers in a targeted manner. Utilizing IT enables them to directly address customers in order to increase sales by improving customer retention. The use of personal data becomes problematic when customers decline the use of their data. If companies ignore their customers’ privacy preferences, their chances of retaining them with targeted offers decline. In this paper, we first identify opportunities and drawbacks of individualization measures from a customer’s perspective based on the findings of a qualitative survey. The results of a quantitative survey illustrate how people’s general attitude toward personal data transmission determines their perception of personalization measures.

Engereicht am 2006-05-12, nach fünf überarbeitungen angenommen am 2006-10-15 durch die Herausgeber des Schwerpunktthemas.     

Static and Cyclic Crack Growth Behavior of Ultrafine-Grained Al Produced by Different Severe Plastic Deformation Methods

Fracture-mechanics experiments were carried out on ultrafine-grained (UFG) samples of aluminum and two Al alloys to obtain the fracture behavior under static and cyclic loading. The UFG materials investigated show crack resistance behavior under static loading, which was confirmed by ductile fracture surfaces. Under cyclic load, the crack growth rate was described well by the ESACRACK model. The crack propagation results show no influence of the type of the severe plastic deformation method in the Paris region but more effect in the threshold region. This article is based on a presentation made in the symposium entitled “Ultrafine-Grained Materials: from Basics to Application,” which occurred September 25–27, 2006 in Kloster Irsee, Germany.     

The effect of chemical structure of basefluids on antiwear effectiveness of additives

The effect of the chemical structure of a lubricant on the complexity of friction and wear under boundary conditions is studied using a pin-on-disc machine and a four-ball wear tester. The two test units are used to compare the friction and wear characteristics of four hydrocarbon fluids. Three vegetable oils and three additives are also evaluated in the four-ball wear tester to demonstrate the importance of chemical structure of the base fluids and the additives on the effectiveness of the additives in controlling friction and wear.     

A New Approach in Layer-by-layer Growth of Oxide Materials by Pulsed Laser Deposition

Pulsed laser deposition (PLD) has become thin film deposition technique with increasing prominence. One of the advantages above other techniques is the possibility to growth at relative high background pressures, with a large freedom in choosing the kind of gas. An example is oxygen in the case of high T_c superconductors and giant magnetic resistors. However, the advantage of relative high pressures hinders the use of a number of diagnostics and monitor techniques, like reflective high energy electron diffraction (RHEED). With the introduction of the possibility to use RHEED at standard PLD pressures, it became possible to study the growth of oxide materials under different oxygen and temperature conditions. In this paper we employed this technique on SrTiO₃, which can be grown in different growth modes depending on growth temperature and oxygen pressure during deposition. Applying a modified etch treatment on SrTiO₃ single crystals, a real 2D growth mode could be observed by the homo-epitaxial growth of SrTiO₃, as indicated by RHEED oscillations. In addition to the RHEED oscillations another phenomenon is observed, typical for PLD. The pulsed way of deposition leads to discontinuities in the intensity of the diffracted pattern. This is caused by the mobility of the deposited material from a disordered distribution till an ordered one and leads to a characteristic exponential slope with characteristic relaxation time constants. These time constants give extra information about relaxation, crystallization, and nucleation of the deposited material during growth. Finally, a new approach to deposit these complex oxide materials will be introduced. This, so-called interval deposition, is based upon the results obtained from the intensity oscillations as well as relaxations. The basic idea is to deposit an equivalent of one unit cell of material in such a short time that no coalescence in larger islands can occur, followed by a relaxation time before the next unit cell layer is deposited. This interval deposition leads to an imposed layer by layer growth.