Monohydroperoxides of linoleic acid in endoplasmic lipids of rats exposed to tetrachloromethane

An accurate method for the quantitative determination of hydroperoxy and hydroxy fatty acids in liver microsomes is presented which involves the use of¹⁸O-labeled internal standards. The method is employed for the determination of hydroperoxides in rat liver microsomes after aerobic incubation with Fe²⁺/ADP and in microsomes from animals exposed to 75 mg tetrachloromethane/kg body weight. The amounts found after artificial microsomal “lipid peroxidation” are almost two orders of magnitude larger than those in microsomes from tetrachloromethaneexposed animals.     

A measuring method for quick determination of local heat transfer coefficients in spray water cooling within the range of stable film boiling

Within the framework of research investigations described in this paper, a measuring method for the determination of heat transfer coefficients in the range of stable film boiling has been developed for water spray cooling in the secondary cooling zone of continuous casting machines. Based on investigations by ³), a water cooled test sample with a measuring field of 20 × 20 mm² was constructed. For this sample geometry, a special evaluation method has been developed which permits quick evaluation in on-line procedure. Result of measurements are sections for the heat transfer coefficient arising from different spray water distributions. On the one hand, these can be used as calculation figures for the determination of the solidification profile and the solidification rate. On the other hand, the measuring results serve as an assessment basis for nozzle constructions. Practical use of the measuring results confirms the usefulness of the measuring method on a laboratory scale. In addition, the validity of the measuring results has been demonstrated by comparing them with an unsteady state method in accordance with ²).     

Realization theory in Hilbert space

A representation theorem for infinite-dimensional, linear control systems is proved in the context of strongly continuous semigroups in Hilbert spaces. The result allows for unbounded input and output operators and is used to derive necessary and sufficient conditions for the realizability in a Hilbert space of a time-invariant, causal input-output operator ℐ. The relation between input-output stability and stability of the realization is discussed. In the case of finite-dimensional input and output spaces the boundedness of the output operator is related to the existence of a convolution kernel representing the operator ℐ. This research has been supported by the Nuffields Foundation.     

Abhängigkeit der Streckgrenze und der Übergangstemperatur der Kerbschlagzähigkeit von der Abschreckalterung von Baustählen im Vergleich mit der Theorie des Sprödbruches

Einfluß der Abschreckalterung auf Streckgrenze und Übergangstemperatur der Kerbschlagzähigkeit. Deutungsmöglichkeiten mit Hilfe der Cottrell-Theorie. Einfluß der Ausscheidungen auf die Größen σ_i, k_y und k bzw. k₀ sowie deren Einfluß auf T_ü.     

Osteogenic differentiation of mesenchymal progenitor cells in computer designed fibrin-polymer-ceramic scaffolds manufactured by fused deposition modeling

Biomimetic scaffolds offer great potentials in the development of bone analogs for tissue engineering. The studies presented in this paper focus specifically on the osteogenic potential of the novel PCL/CaP matrices and its degradation behavior. Biodegradable Polymer-ceramic Scaffolds were fabricated using the solid free form fabrication technology: Fused Deposition Modeling (FDM). The scaffold architecture was characterized by a honeycomb-like design and a complete interconnectivity of the pores. Human mesenchymal stem cells (MSCs) were seeded together with fibrin glue into PCL/CaP scaffolds and cultured in vitro for periods of up to eight weeks. Cellular adhesion, proliferation and osteogenic differentiation were assessed in these constructs using a range of histological and microscopic techniques. In additional experiments, degradation was assessed by measuring mass loss, diameter change, molecular weight change and by scanning electron micrographs. MSCs were able to adhere, migrate, and differentiate along the osteogenic lineage with in these scaffolds. The PCL/CaP scaffolds showed up to 27 fold increased degradation of compared to PCL scaffolds.     

Image guide couplers with isotropic and anisotropic coupling elements

Among other waveguide elements directional couplers are required in integrated millimeterwave circuits in image guide technique. Hereby an I-guide is used which consists of a dielectric slab between two conducting plates on which the electric field is perpendicularily. Flat coupling behaviour and better isolation can be reached by use of a dielectric coupling element and absorber materials. Thereby the frequency dependence is reduced significantly. Further the coupling can be steered by an additional premagnetized ferrite slab. In this way switched couplers can be realized.     

Impact of saccharides and amino acids on the interaction of apple polyphenols with ion exchange and adsorbent resins

Model solutions containing catechin, caffeic acid, chlorogenic acid, phloridzin and rutin were used to examine their recovery using two adsorbent resins, four cation and four anion exchange resins at two temperatures (20 °C and 40 °C) and two pH values (pH 1 and 7). In addition, the interference of glucose, fructose and sucrose and of a saccharide mixture on polyphenol binding by one anion exchange and two adsorbent resins was assessed to approximate real conditions. In a further step polyphenol recovery using the aforementioned adsorbent and ion exchange resins was studied upon the addition of the amino acids alanine, glutamic acid, phenylalanine, lysine and histidine. The data reveal that both saccharides and amino acids influence polyphenol recovery positively and negatively, depending on the experimental conditions and the resin type; possible explanations for these findings are discussed. The information obtained in this study helps to gain a better understanding of the complex mechanisms of ion exchange and adsorption processes involving multi-component systems. The insights gained allow to design cost-efficient recovery of plant secondary metabolites from crude extracts for producing tailor-made health-beneficial fractions.