Indentation Deformation and Fracture of Sapphire

Relatively little is known about the fundamental deformation processes in intrinsically hard, brittle materials, and even less about how these processes lead to the initiation of cracks. In this paper, transmission electron microscopy is used to study the deformation structure within Vickers indentation zones of single-crystal sapphire with {     } surface orientation. The relative misorientation of regions within these zones, as mapped by convergent-beam kikuchi patterns, is found to be severe, indicative of shear processes operating close to the cohesive limit. Two principal types of deformation are identified, basal twinning and pyramidal slip. Incipient microcracks are observed at both the twin interfaces and the slip planes. These incipient "flaws" act as nucleation sites for the ensuing radial and lateral cracks.     

Disproportionation of SO2 in Bubbles Within Soda-Containing Glasses

Deposits of S⁰; and Na₂SO₄ together in bubbles within production float glass are generated by disproportionation of SO₂, derived from dissolved SO₃, in company with Na₂O from the interior bubble surfaces. This reaction proceeds rapidly in molten glass and also at temperatures well below T_g.     

Gelation Enhancement of Soy Protein Isolate using the Maillard Reaction and High Temperatures

Soy protein isolate gels prepared by autoclaving solutions in the presence of xylose of glucono-δ-lactone (GDL), were compared. In both cases, the pH decreased from neutral to pH 5.5 during gel formation. In the xylose systems, this pH decrease was a consequence of the Maillard reaction. The Maillard gels showed less syneresis, had a higher breaking force and were more elastic, as determined by stress relaxation, then the GDL gels. The differences were attributed to formation of additional covalent crosslinks due to the Maillard reaction, as evidenced by greatly reduced solubility in sodium dodecyl sulfate +β-mercaptoethanol.     

DIRECT VAT INOCULATION OF MILK WITH FREEZE-DRIED STARTERS FOR MAKING CHEDDAR CHEESE

The introduction of cheese starter developed by Vitex, Paris, France, in concentrated, freeze-dried form for direct inoculation of milk in the cheesemaking vat offers considerable advantages and the performance of some ICF starters (Inoculum pour Cuve de Fabrication) for making Cheddar is reported. Conditions regarding level of inocula and processing temperatures to establish satisfactory curd making in an acceptable making time are described and numbers of starter bacteria in the milk and in the curd at pressing and the pattern of acidity development during processing are shown to be very similar to those in standard control Cheddar cheesemaking with liquid starter cultures. No apparent lag-phase was observed in the production of acidity by these freeze-dried starters. Chemical analysis and official grading of the cheeses showed them to be of good quality.     

Dispelling the Myth that Preference makes Practice in Residential Location and Transport Behaviour

This paper critically examines the widely held belief that social costs of growth, such as congestion, pollution and sprawl, can be stemmed by compact, mixed-use, design solutions. It is argued instead that when considering the future of cities, we have to actively engage in debates concerning the future of work and changes in the structure and composition of households. Discussion draws on household level research conducted in three West Coast US cities (Portland, Seattle and San Francisco) representing a hierarchy of size, status and growth management. Detailed analysis of 60 two-wage household 'biographies' highlights the way decision making (and ultimately compromise) shapes human-environment interaction. Evidence is presented which shows high levels of dissonance between stated preference for compact, mixed-use neighbourhoods and non-localised lived relations between different daily activities and communities. The results of this inter-city comparative study are discussed with reference to US (and UK) environmental policies currently favouring planning-led behavioural change.