Measurement and Correlation of the Striations in a Liquid Film During Sudden Separation

Experiments are described of the separation at known velocity of uniformly thick oil films of various viscosities and initial thicknesses. Separation of the film occurred in patterned striations or in un-patterned direct cleavage. The width of the striations correlated approximately with the square root of the initial film thickness. This correlation includes other data in the literature. The calculated negative pressures in the striations suggest that the separation mode changed from striations to tensile cleavage at tensile stresses greater than about four atmospheres.

It appears that the rate of damage and the damage pattern in ASTM cavitation erosion tests can be correlated with the maximum negative pressure occurring in the striations.     

Assessing the effects of bacterial predation on membrane biofouling

Membrane biofouling is one of the major obstacles limiting membrane applications in water treatment. In this study, Bdellovibrio bacteriovorus HD 100, a Gram-negative predatory bacterium, was evaluated as a novel way to mitigate membrane biofouling and its subsequent performance decline. Dead-end microfiltration (MF) tests were carried out on Escherichia coli DH5α and B. bacteriovorus HD 100 co-culture feed solutions. Predation of E. coli was performed at either a low or high multiplicity of infection (MOI), which is defined as the predator to prey cell ratio. The MOIs tested were 2 and 200, and the viability of both the E. coli prey and the predator was monitored over 48 h. The higher MOI (high predator, HP) culture showed a nearly 6-log loss in E. coli number after 24 h when compared to both the control and low MOI (low predator, LP) cultures, whereas the E. coli population within both predated cultures (HP and LP) became nearly identical at 48 h and 4-log lower than that of the control. The unpredated cultures led to significant loss in water flux at 12, 24, and 48 h of culture, but the HP and LP membranes showed less loss of flux by comparison. Analysis of the total membrane resistance showed a similar trend as the flux decline pattern; however, irreversible resistance of the membrane was much higher for the 48 h LP culture compared to the unpredated and HP cultures at 48 h. This increase in irreversible resistance was attributed mainly to E. coli debris, which accumulated in the medium after the predator lysed the prey cells. These results show that pretreatment of wastewater using a suitable concentration of predatory bacteria such as B. bacteriovorus can enhance membrane performance.     

Turning Social Relations into Space: Property,Law and the Plaza of Santa Fe,New Mexico

In this article, a series of controversies in and over the central Plaza of Santa Fe, New Mexico, USA is examined. The complex and contradictory dynamics of law and property as they intersect to shape and define a critical public space that is the symbolic heart of Santa Fe's landscape are explored. It is argued that laws and regulations that determine the activities that may occur in the Plaza, that restrict some actions, or that adjudicate ownership disputes literally shape the lands to which they pertain. It is shown that one purpose of law is to negotiate just how the social relations that are property get transformed into the regulated space that is property.     

Quantifying energy demand reduction considering householder willingness to apply measures

ABSTRACT

Reducing energy demand in the domestic sector will be an important feature of future energy systems but is challenging to achieve in practice. Solutions lie in a range of building fabric and system improvements as well as adopting more sustainable routines and conceptions of normality in the home. The impact of such measures has so far been quantified without considering the willingness of the householder to adopt them. This paper uses a modelling approach to evaluate the effectiveness of technical and lifestyle measures to reduce energy demand in six households based on monitoring data and insights from interviews. The results are benchmarked against estimated tailored 2050 reduction targets and demonstrate that although these targets are achievable in the studied homes, householders might not always be willing to apply them. The resultant reduction pathways are shown to vary significantly between households, suggesting that bespoke strategies are needed to allow households to identify and select the most appropriate methods that allow them to maximize demand reduction.     

An Investigation into the Effect of Laundering on the Repellency Behaviour of a Fluorochemical-treated Cotton Fabric

The water- and oil-repellency of a cotton fabric treated with a fluorocarbon finish is shown to decrease with extended laundering. The nature of this diminishing performance is investigated by time-of-flight secondary-ion-mass spectrometry (ToF—SIMS) and X-ray photoelectron spectroscopy (XPS), which reveal an increase in the surfactants on the fibre surface and a decrease in the fluorocarbon coating as a result of laundering. The effect of heat-pressing on fabric repellency is also investigated by using XPS.