Rhizobium trifolii capsular polysaccharide: a novel biopolymer with striking physical properties

The physical properties of the capsular polysaccharide of Rhizobium Trifolii (CPS) were investigated. Viscosity measurements provided information about the hydrodynamic volume of single coils, the perturbation of solvent flow and the shear-thinning behaviour of concentrated solutions. Changes in chain geometry and the development of an intermolecular network as a function of temperature were monitored using the techniques of optical rotation and dynamic oscillation. Finally, analysis of calorimetric thermograms elucidated the type of interactions between CPS and the bacterial levan. Overall, the Rhizobium polysaccharide was found to form thermally-reversible gels at an extremely low 'minimum critical gelling concentration' (c_o∼ 0.35gl^-1). At temperatures above the gel melting point (∼ 48°C), however, the compact polymer coils entangled at comparatively high concentrations (about 60 times higher than c_o). In the presence of a highly branched levan, the thermal stability of ordered CPS structures increased as a consequence of thermodynamic incompatibility between the two polymers.     

On some models for developmental systems Part I. Organism structure on the basis of elementary transformations

A great number of organism development processes can be accounted for by the elementary mechanisms of cell partition and cell transformation. In the present article an analytical method is presented which emphasizes the link that exists between the generating word of an organism (in the language consisting of the possible cell transformations) and the successive structures of the developmental process. The viewpoints of analysis (types of structures generated by a given type of word) and of synthesis (type of word generating a given type of structure) are considered. As an illustration of the method models of development are constructed which have already been proposed empirically to account for two types of plant development.     

Comparison of H∞ and state-space induced quotient topologies on stable minimal systems

It is shown that on the set of w-input, p-output asymptotically stable, minimal, nth order systems that the H_∞ ^p·m and the R^N quoiient induced topologies coincide. Implications of this in frequency domain system identification are discussed     

On some models for developmental systems Part IX. Generalized generating word and genetic code

The model for developmental systems used by the present authors in the foregoing eight parts is generalized and compared to biological facts concerning DNA.     

Pressure Induced Inactivation of Selected Food Enzymes

Pectinesterase, lipase, polyphenol oxidase, lipoxygenase, peroxidase, lactoperoxidase, phosphatase and catalase have been examined at distinct conditions within a pressure range of 0.1 to 900 MPa, temperatures from 25°C to 60°C, pH 3 to 7, and time of treatment of 2 min to 45 min. Results in model buffers made it possible to rank the enzymes according to their pressure induced inactivation in the following order: lipoxygenase, lactoperoxidase, pectinesterase, lipase, phosphatase, catalase, polyphenol oxidase, peroxidase. A combination of pressure with moderate temperature increased the degree of enzyme inactivation. Pressure treatment of real food systems showed a protective effect of food ingredients on the pressure inactivation of most enzymes evaluated. For example sucrose protected pectinesterase from inactivation by pressure while lactoperoxidase and lipoxigenase were as stable in milk as in buffer.     

THE FOURTH INTERNATIONAL CONFERENCE ON EXPERIMENTAL STRESS ANALYSIS, CAMBRIDGE 6–10 APRIL, 1970

A short survey of the history and organisation of the series of international conferences on experimental stress analysis is given together with abstracts of all papers to be presented in April, 1970, and a summary subject index for these papers.     

GENERAL THEORY OF INTELLIGENT SYSTEMS

The basic foundations of the general theory of intelligent systems are constructed in this paper through formalization of the evolution in an open system. Evolution is presented as behavior and self-organization of an open system, and it is assumed that intelligence is given by the laws of evolution. Four laws of self-organization are obtained, depending on the type of open system and its kind of self-organization. The redundancy and entropy of self-organization are obtained as basic evolution characteristics. A pattern recognition and an expert subsystems of an intelligent system are constructed. Discrete and analog intelligent systems have been defined, respectively, as an artificial intelligence system and a system of functional diagnostics.     

PHYSICAL AND COOKING PROPERTIES OF MICRONIZED LENTILS

The potential for reducing the cooking time of lentils by micronization was studied. The effect of infrared heat and initial seed moisture on the internal temperature of lentil seeds was monitored up to the stage of seed browning. The seed physical properties, water uptake by seeds, cooking time and starch properties were determined. The cooking time was shortened from 30 min for the control seeds to 15 min for lentils adjusted to 25.8% wb moisture content and micronized for 55s to 18.0% wb moisture. Micronization was effective in gelatinizing and solubilizing 45 to 65% of the starch in the lentil seed, depending on the initial seed moisture content.     

Contact Damage in Single-Crystalline Silicon Investigated by Cross-Sectional Transmission Electron Microscopy

Cross-sectional transmission electron microscopy (TEM) is demonstrated as a powerful tool for investigating subsurface damage in the micrometer and submicrometer ranges in brittle materials, and applications to a wide variety of contact damage in silicon are discussed and illustrated with TEM images. Regions of plasticity and different types of cracking are identified and characterized for various contact situations: indentation, scribing, solid-particle impacts, and polishing/grinding. Most single-point contact situations result in similar types of damage in silicon, although transitions between different damage mechanisms occur between different load levels. Normally, the crack geometry is governed by the principal stress directions and is only weakly influenced by the lattice orientation. Grinding with metal-bonded abrasives results in fairly deep subsurface damage zones, but the main mode of material removal is superficial lateral cracking. Polishing with small-size free abrasives results in very superficial damage zones and mirror-like surface finish.