Changes in starch content and amylase zymograms during storage of Golden Delicious and Cox's Orange Pippin apples

Changes in starch content and amylase zymograms were followed during storage of Golden Delicious and Cox's Orange Pippin apples. Although the former was stored at 3-4 degrees C under controlled atmosphere (3--4% O2; 7--8% CO2 by volume) and the latter in air at 17 degrees C, in both, the multiple forms of amylases remained active, even after the starch content decreased to zero. It is the lack of starch substrate, therefore, rather than of enzymes that limits the amylase action in the stored apple.     

Characterisation of Phaseolus vulgaris Cultivars by their electrophoretic patterns

Characterisation of 32 cultivars of Phaseolus vulgaris has been obtained by densitograms of protein patterns, which were evaluated by starch-gel electrophoresis of protein fractions obtained by single extraction of bean seeds with water. Experiments indicated that the protein patterns are unlikely to be affected by external conditions such as N fertilisation, climatic conditions and soil properties.     

Lambda Calculus with Explicit Recursion

This paper is concerned with the study ofλ-calculus with explicit recursion, namely of cyclicλ-graphs. The starting point is to treat aλ-graph as a system of recursion equations involvingλ-terms and to manipulate such systems in an unrestricted manner, using equational logic, just as is possible for first-order term rewriting. Surprisingly, now the confluence property breaks down in an essential way. Confluence can be restored by introducing a restraining mechanism on the substitution operation. This leads to a family ofλ-graph calculi, which can be seen as an extension of the family ofλσ-calculi (λ-calculi with explicit substitution). While theλσ-calculi treat the let-construct as a first-class citizen, our calculi support the letrec, a feature that is essential to reason about time and space behavior of functional languages and also about compilation and optimizations of programs     

The role of the hydrogen bonding network for the shear modulus of PIPD

Ab initio total energy calculations at the DFT-GGA level for PIPD are reported. Both the monoclinic crystal with a bi-directional hydrogen-bond network and the triclinic crystal with a sheet-like network are studied. It is concluded that the latter is the more plausible microstructure for the fibre based on the following: (i) After optimisation of the lattice parameters and atomic positions it has a lower energy. (ii) The calculated internal shear modulus agrees better with experiment. (iii) The minimal shear stiffness constant, which is interpreted as the upper limit on the compressive strength, compares favourably with the experimental compressive strength.The hydrogen bonding network plays a crucial—but indirect—role in explaining the high compressive strength. It replaces the weak components of the lateral bonding, such as present in many high performance polymer materials with low compressive strength, e.g. PBO and PBZT, with much stronger hydrogen bonds. This makes that in PIPD the relatively strong π-π interaction has the weakest resistance against shear.     

Crystallite size evolution of aramid fibres aged in alkaline environments

Aramid fibres are high-performance materials proposed in geotextiles for alkaline ground reinforcement. To study their durability in such environments, accelerated ageing has been carried out at pH 9 and at pH 11 for up to one and a half years. First, the lateral and longitudinal crystallite sizes have been determined before and after ageing under these conditions by Wide-Angle X-ray diffraction. Next, the tensile fracture surfaces have been observed after different ageing times by scanning electron microscopy. Finally, molecular weight changes have been evaluated by size exclusion chromatography. This study highlights the dependence of structural changes on the ageing conditions. A structural degradation scheme is proposed.     

Proving program inclusion using Hoare's logic

We explore conservative refinements of specifications. These form a quite appropriate framework for a proof theory for program inclusion based on a proof theory for program correctness.We propose two formalized proof methods for program inclusion and prove these to be sound. Both methods are incomplete but seem to cover most natural cases.     

The influence of the lateral filament texture on the compressive properties of PpPTA aramid filaments

A series of PpPTA aramid fibres with various degree of lateral orientation ranging from their usual radial-oriented lateral texture to a full random lateral texture were prepared by employing a series of different coagulating media in the fibre spinning process. The resulting variation in lateral texture did not lead to differences in linear tensile properties or crystallite dimensions. Raman spectroscopy measurements on embedded axially compressed filaments showed that the stresses for kink band initiation and propagation were independent of the degree of lateral texture. The kink band morphology and the final kink band density upon further straining were found to correlate with the shear modulus derived from combined mechanical and XRD data.