Butter colour affects sensory perception of spreadability

 Two butter samples of significantly different yellowness were subjected to cone penetration experiments to measure their apparent yield value, as an instrumental measure of spreadability, at different temperatures. A ten-member panel evaluated sensory spreadability of selected pairs of samples, adjusted to particular apparent yield values, by means of simple difference tests both in the daylight and in a dark-room under red light. The results imply that sensory perception of spreadability is heavily affected by butter colour. Whereas the results of the dark-room experiments were in line with instrumental measures, the more yellowish butter was selected as the “easier-to spread” sample when colour differences were perceptible by the panellists. Received: 26 November 1996     

Therapeutic efficiency of lipoprotein(a) reduction by low-density lipoprotein immunoapheresis

This study was performed to investigate the effect of low-density lipoprotein (LDL) immunoapheresis on lipoprotein(a) [Lp(a)] reduction in patients with heterozygous and homozygous familial hyperlipidemia (N=16) and insufficient response to lipid-lowering agents. By desorption of approximately 5,700+/-500 mL of plasma, a mean reduction in total cholesterol of 62% (P < .001) and in LDL-cholesterol of 70% (P < .001) was achieved. Lp(a), which was elevated at study entry in seven of these patients (82.1+/-34.3 mg/dL; range, 48 to 148 mg/dL), was reduced during the initial LDL-apheresis procedure by 74.8%+/-14.1% (P < .001). Long-term apheresis treatment performed at weekly intervals resulted in an mean reduction in Lp(a) pretreatment values to 39.1+/-28.5 mg/dL (-54%; P < .001). Desorbed Lp(a) was measured at the waste of the columns for 31 apheresis treatments. Lp(a) concentration of the column waste was higher in patients with elevated serum Lp(a) pretreatment values as compared with those with Lp(a) serum values within the normal range (elevated Lp(a), 1,420+/-380 mg; without elevated Lp(a), 235+/-190 mg; P < .001). The rate of return of Lp(a) following apheresis treatment scheduled at weekly intervals was comparable to that of LDL-cholesterol.     

Modelluntersuchungen zur Faserverstärkung keramischer Werkstoffe

Model Investigation of the Fibre Reinforcement of Ceramic Materials A mechanism for fibre reinforcement of high-modulus brittle materials, in particular ceramics, is investigated both experimentally and theoretically. A simple mathematical formalism representing crack extension in a brittle matrix reinforced by ductile fibres is derived, and characteristic property values, adapted to composite structures, are introduced. Alumina with unidirectional reinforcement by thin 80Ni20Cr wires is used as a model material. The mechanism presented allows to reduce the high sensivity of ceramic materials to cracks. It is necessary for the fibres to bridge matrix cracks under load. For this purpose, the fibres must not be bound too tightly to the matrix, and while a high ductility is certainly of value, it is not a necessity. The efficiency of the mechanism depends on

• – interface energy and friction at the matrix-fibre interface,
• – deformation and fracture behavior of the fibre material,
• – radius of the fibres,
• – volume fraction of the fibres,
• – critical stress intensity factor of the matrix,
• – size of the largest crack.

Among these, the fibre radius appears to be the most suitable one for variation with the goal of optimizing material quality.     

A law controlling polymer recrystallization showing up in experiments on s-polypropylene

When polymers are crystallized at large supercoolings a subsequent heating is accompanied by recrystallization processes, which proceed to a fixed final melting point. We studied these processes with small-angle X-ray scattering and DSC measurements for three s-polypropylenes with different stereoregularities and co-unit contents. As is known from previous experiments, crystal thicknesses d_c depend on the crystallization temperature T_c only, being not affected by stereo defects or co-units. The new experiments, all carried out at low crystallization temperatures, again confirm this property; in plots of d_c⁻¹ versus T_c all points are located on a unique straight crystallization line. A similarly simple law controls the crystal thickness during the continuous structure reorganization on heating. Over an extended temperature range d_c⁻¹ changes linearly with temperature, guided by a unique, i.e., sample-invariant, ‘recrystallization line’. Crystallization and recrystallization lines extrapolate for d_c⁻¹ → 0 to the same limiting temperature, T_c^∞, and differ only in slope. The findings indicate that both the initial crystallization at T_c and the process of recrystallization use a pathway via a transient mesomorphic phase. The DSC thermograms of the samples show a multiple peak structure which varies with the heating rate. The SAXS results enable the peaks to be assigned to different melting processes.     

WATER-TREEING — Ein Alterungsphänomen in kunststoffisolierten Mittelspannungskabeln

Today, water-treeing is one of the most important ageing phenomena of plastic-insulated cables. Generally, the simultaneous reactions between electrical field and water cause small tree structures. These water-tree-structures resemble to a bush, start at imperfection points in polyolefin-insulations and expand in the direction of the applied electrical field. This process can be regarded as irreversible, causes a damage of the cable dielectrica as well as a decrease of the breakdown stress level. Water-treeing is a very complex process and the growth or acceleration of water-trees depends on many different parameters.     

Quantifying the robustness of fuzzy rule sets in object-based image analysis

Object-based image analysis (OBIA) has become very popular since the turn of the century. For high-resolution situations, in particular, where the objects of interest are larger than pixels, methods have been developed that build on image segmentation and on the further classification of objects rather than on pixels. Many studies have shown that OBIA methods are, in principle, more transferable and reapplicable to other images. To obtain comparable results by reapplying a given rule set on (slightly) changed conditions, the rule set must either be able to adapt to the changed conditions or it must be parameterized for manual adaptation. In this context, a rule set can be seen as the more robust the less it has to be changed, and vice versa. In this article we introduce a new method to evaluate the robustness of a rule set. The main assumption is that the amount of necessary adaptations can be measured in conjunction with the quality of classification achieved. We demonstrate that the method introduced is able to (1) evaluate the robustness of a rule set and (2) identify crucial elements of a rule set that need to be reparameterized.     

A simple all-optical light switch and its relations to opticalcomputing: a demonstration for teaching photonics

The authors discuss how a simple and inexpensive all-optical light switch can be built for teaching and demonstrating photonics in a classroom or for undergraduate lab experiments. The discussion of this readily understandable device will familiarize the student with the similarities and differences between photonics and electronics. As an example, the authors consider how this device relates to all-optical computing circuits, promoting a comparison between electronic and optical integrated circuits