Fractionation of stable iron isotopes in higher plants

Although the fractionation of stable iron isotopes by biological processes in the environment is currently a matter of intense debate, the isotope fractionation associated with the growth of higher plants has, to date, not been characterized. We show that iron isotope fractionation induced by higher plants is substantial and also generates systematic plant-specific patterns. We suggest a hypothesis in which these patterns mirror the two different strategies that plants have developed to incorporate iron from the soil: reduction of Fe(III) in soils by strategy I plants results in the uptake of iron, which is depleted in 56Fe by up to 1.6 per mil relative to 54Fe when compared to the available Fe in soils; complexation with siderophores by strategy II plants results in the uptake of iron that is 0.2 per mil heavier than that in soils. Furthermore, younger parts of strategy I plants get increasingly depleted in heavy isotopes as the plant grows, while strategy II plants incorporate nearly the same isotope composition throughout. This points to entirely different translocation mechanisms between strategy I and II plants. Such presumably redox-related differences in translocation have been under debate up to now. We conclude that plant metabolism represents an important cause of isotopic variation in the biogeochemical cycling of Fe. Therefore, heavy stable metal isotope systems now start to be viable indicators of geosphere-biosphere metal transfer processes.     

Microbiological and color aspects of cooked sausages made from a standardized porcine blood cell concentrate

The objective of this study was to determine the potential for blood cell concentrates (BCCs) from pigs as an ingredient in food. Sausages were made for this study according to a basic recipe for a type of blood sausage that is common in Germany. First, sausages were produced with rind and kettle broth only, and different amounts (2.5 to 31%) of standardized blood cell concentrate (s-BCC) were added (15% table salt [NaCl] and 25% protein content). Then, sausages were made with whole blood and compared with s-BCC sausages; both the BCC and blood had been pretreated either with NaCl or curing salt (nitrite). The impact of BCC and blood on the color (La*b*) of these rind sausages was determined. Finally, blood sausages were made with 12% s-BCC and either natural spices or spice extracts. These sausages were investigated microbiologically and compared to customary commercial blood sausage products (with whole blood) in terms of aerobic plate count (APC), Enterobacteriaceae, sulfite-reducing anaerobic bacteria, coagulase-positive staphylococci, and spore-forming bacilli. The desired color parameters (L, 34.5; a*, 17.8; and b*, 10.6) were obtained with the addition of about 12% s-BCC. Curing the blood or BCC beforehand had no significant (P > 0.05) influence on the color. The microbial counts of both the blood (APC, 4.4 log CFU/g) and the natural spices (APC, 6.6 log CFU/g) were relatively high. The spices were responsible for the relatively high microbial counts in the sausages, particularly the bacilli (6.4 log CFU/g). However, these counts were comparable to those found in commercial blood sausages. The bacteria introduced into the sausage by the blood had no significant impact on the bacterial counts of the end product. The bacterial loads of the sausages produced with 12% s-BCC and spice extracts were significantly lower (APC and bacilli, 2.0 log CFU/g) than those of the other blood sausages (APC, -4.4 log CFU/g; bacilli, 3.2 to 4.0 log CFU/g).     

GripSee: A Gesture-Controlled Robot for Object Perception and Manipulation

We have designed a research platform for a perceptually guided robot, which also serves as a demonstrator for a coming generation of service robots. In order to operate semi-autonomously, these require a capacity for learning about their environment and tasks, and will have to interact directly with their human operators. Thus, they must be supplied with skills in the fields of human-computer interaction, vision, and manipulation. GripSee is able to autonomously grasp and manipulate objects on a table in front of it. The choice of object, the grip to be used, and the desired final position are indicated by an operator using hand gestures. Grasping is performed similar to human behavior: the object is first fixated, then its form, size, orientation, and position are determined, a grip is planned, and finally the object is grasped, moved to a new position, and released. As a final example for useful autonomous behavior we show how the calibration of the robot's image-to-world coordinate transform can be learned from experience, thus making detailed and unstable calibration of this important subsystem superfluous. The integration concepts developed at our institute have led to a flexible library of robot skills that can be easily recombined for a variety of useful behaviors.     

Polymerisation von α-methylstyrol unter hohem druck

The polymerization-depolymerization equilibrium of α-methyl styrene can be shifted by high pressures towards the polymerization step. The equilibrium concentrations of the α-methyl styrene monomer were calculated at different pressures and temperatures from already known data for ΔH and ΔS°. The equilibrium concentrations are reported for temperatures from 40 to 100°C and for pressures from 1–5000 kg/cm². The data show for example, that at 70°C and atmospheric pressure the polymerization of α-methyl styrene is not possible because the required equilibrium concentration (9,6 mole/liter) is greater than the highest possible monomer concentration (7,3 mole/liter). However, at the same temperature and a pressure of 3000 kg/cm², the polymerization should take place up to the monomer concentration of 1,1 mole/liter. Experiments demonstrate, that under these conditions polymeric α-methyl styrene of high molecular weight is obtained by free radical polymerization. Analogous experiments were carried out with anionic initiation of the polymerization by naphthalene-sodium.     

Über das verhalten von sulfonierten naphthalin- und phenol-formaldehyd-kondensationsharzen an grenzflächen

The wetting mechanism of solids by the examined polymers basically differs from the wetting mechanism of surfactants. Aqueous solutions of polymers are not surface-active and show on solids the same contact angle as water. At hydrophobic solids such as graphite or polyethylene, a reversible monomolecular physisorption occurs, which can be described by the LANGMUIR'S equation. In contrast, on polycarbonate plastics, kaolin and porcelain, a largely irreversible adsorption occurs. The irreversibly adsorbed polymer molecules hydrophilize the surfaces of solids, which then retain their hydrophilic properties and can be wettedd even after repeated rinsing. With adsorption on graphite, the adsorbed amount of substance is independent on the ratio liquid volume/adsorbent, whereas with adsorption on kaolin and porcelain the amount of polymers adsorbed in equilibrium increases with an increasing ratio. The adsorption depends upon the external surface area, consequently, the equilibrium adsorption decreases significantly with an increasing grain radius.     

Struktur und eigenschaften von ABS-polymeren. VIII. Das elutionsverhalten von homo- und copolymeren aus styrol und acrylnitril in der gelchromatographie. Aufstellung einer eichkurve für lösungsmittel unterschiedlicher güte

The elution behaviour in gel chromatography was investigated for a series of polystyrene, polyacrylonitrile and styrene acrylonitrile copolymer fractions with acrylonitrile contents of 12, 25 and 52% by weight. In each series of tests a separate calibration relationship for solutions in chloroform and dimethyl formamide (DMF) is obtained by plotting the molecular weight versus the elution volume. Using the hydrodynamic volume and undisturbed coil dimensions one can obtain universal calibration relationships, except for solutions of polystyrene in DMF. This exception is explained by the poor solubility of polystyrene in DMF, which necessitates taking into account the interaction between the polymer and solvent molecules. By plotting the product of the second virial coefficient and the molecular weight versus the elution volume a universal calibration relationship is obtained for all the differing series of solutions in chloroform; the differences between the solutions of polystyrene, the copolymers and polyacrylonitrile in DMF can be substantially reduced.     

Struktur und elektrische Leitfähigkeit von polymeren organischen Halbleitern

In this review article we want to give information about low molecular and polymer organic semiconductors, which were recently synthesized in our institute. Specific electric conductivities up to σ_298°K = 9.0 · 10^?5Ω^?1 · cm^?1 and thermic activation energies of E = 0.30 eV of polyenearylenes, respectively -heteroarylenes were measured. Polyazomethines have a maximum σ_298°K = 3.3 · 10^?9Ω^?1 · cm^?1 and E = 0.35 eV. Polymers with indophenine units have conductivities up to σ_298°K = 1.1 · 10^?4Ω^?1 · cm^?1 and E = 0.39 eV. A maximum of σ_298°K = 5.0 · 10^?2Ω^?1 · cm^?1 and E = 0.05 eV was found for bis-(1.2-dicyanoethylenedithiolo)-metal salts. Polymers with a phthalocyanine- or hemiporphyrazine-like structure achieve a conductivity of σ_298°K = 2.3 · 10^?2Ω^?1 · cm^?1 and E = 0.15eV. Coordination polymers of dimercaptomaleic acid, respectively their monoamide show a maximum of σ_298°K = 3.2 · l0^?lΩ^?l · cm^?1 and E = 0.20 ev. Polymers with σ_298°K ≤1.5 · 10^?5 Ω^?l · cm^?l and E ≥ 0.5 eV were obtained by the polymerization of succinonitrile. All the investigated substances show an electronic conductivity. The existence of an ionic conductivity could, in all cases, be excluded by using direct current measurements over a long period of time.     

Kleinwinkel-Lichtstreuung an nukleiertem polypropylen

Polypropylene films with different content of nucleator and crystallized at temperatures between 0 and 130°C were examined by small angle light scattering. Only unnucleated polypropylene films quenched to temperatures lower than 40°C gave H_v-scattering patterns in the form of a four-leaf clover, which is typical for a spherulitic texture and from which the average spherulite radius can be calculated. Nucleated polypropylene and unnucleated polypropylene crystallized at temperatures higher than 40°C show an H_v-scattering pattern, which is extended into the directions of the polarisator and the analysator having maxima at μ = 0° and μ = 90°. Distinct qualitative differences between measured intensity distribution curves and distribution curves calculated from a model involving a rodlike aggregate of crystals show that the measured scattering patterns cannot be interpreted in terms of a rodlike model. By comparison with electron micrographs it is presumed that a supermolecular structure of quadrites with a cross-hatched texture consisting of a network of narrow intercrossing structural units is the reason for the scattering parallel to the polarisator and the analysator. The transition from a spherulitic to a non spherulitic structure appears with aluminium-hydroxy-di-p-tert.-butylbenzoate as nucleator at a concentration between 2.4 · 10^?3 and 9.5 · 10^?3 wt.–%.     

On generating FC3 fuzzy rule systems from data usingevolution strategies

Sophisticated fuzzy rule systems are supposed to be flexible, complete, consistent and compact (FC(3)). Flexibility, and consistency are essential for fuzzy systems to exhibit an excellent performance and to have a clear physical meaning, while compactness is crucial when the number of the input variables increases. However, the completeness and consistency conditions are often violated if a fuzzy system is generated from data collected from real world applications. A systematic design paradigm is proposed using evolution strategies. The structure of the fuzzy rules, which determines the compactness of the fuzzy systems, is evolved along with the parameters of the fuzzy systems. Special attention has been paid to the completeness and consistency of the rule base. The completeness is guaranteed by checking the completeness of the fuzzy partitioning of input variables and the completeness of the rule structure. An index of inconsistency is suggested with the help of a fuzzy similarity which can prevent the algorithm from generating rules that seriously contradict with each other or with the heuristic knowledge. In addition, soft T-norm and BADD defuzzification are introduced and optimized to increase the flexibility of the fuzzy system. The proposed approach is applied to the design of a distance controller for cars. It is verified that a FC(3) fuzzy system works very well both, for training and test driving situations, especially when the training data are insufficient.