Free Radical Chemistry. Part 9.1 Approaches to Fluorinated Polyethers—Model Compound Studies

Using peroxide, γ-, and UV-irradiation, free radical addition reactions of hexafluoropropene to diethers and to 18-crown-6 have been investigated and mono-, di-, and poly-adducts have been obtained. Factors influencing these additions, especially polar characteristics of intermediate radicals, have been elucidated. Adducts of 18-crown-6 retain a capacity to complex to alkali-metal ions.     

The three-dimensional locomotor dynamics of African (Loxodonta africana) and Asian (Elephas maximus) elephants reveal a smooth gait transition at moderate speed

We examined whether elephants shift to using bouncing (i.e. running) mechanics at any speed. To do this, we measured the three-dimensional centre of mass (CM) motions and torso rotations of African and Asian elephants using a novel multisensor method. Hundreds of continuous stride cycles were recorded in the field. African and Asian elephants moved very similarly. Near the mechanically and metabolically optimal speed (a Froude number (Fr) of 0.09), an inverted pendulum mechanism predominated. With increasing speed, the locomotor dynamics quickly but continuously became less like vaulting and more like bouncing. Our mechanical energy analysis of the CM suggests that at a surprisingly slow speed (approx. 2.2 m s(-1), Fr 0.25), the hindlimbs exhibited bouncing, not vaulting, mechanics during weight support. We infer that a gait transition happens at this relatively slow speed: elephants begin using their compliant hindlimbs like pogo sticks to some extent to drive the body, bouncing over their relatively stiff, vaulting forelimbs. Hence, they are not as rigid limbed as typically characterized for graviportal animals, and use regular walking as well as at least one form of running gait.     

What Makes a Good City in Pre-schoolers' Eyes? Findings from Participatory Planning Projects in Australia and New Zealand

Pre-schooler's voices are absent in urban planning and design. With the possible exception of playgrounds, there is limited knowledge about their experiences in and expectations for urban environments. This paper discusses pre-schoolers' aspirations and desires for aesthetic and accessible green spaces as well as social and physical connectedness. Although this age range has so far been limited in its ability to inform policy and decision-makers, it is argued that pre-schoolers have the capacity and capability of making valuable contributions to design. In the eyes of pre-schoolers, creating a good city means to live in a safe place full of diverse destinations in which they can become streetwise and socialize as part of society.     

Replacing the Equations of Fano and Fisher for Cased Charge Blast Equivalence – I Ductile Casings

The initial velocity of casing fragments from bombs, shells etc. was first calculated by R. W. Gurney in 1943 [1]. Subsequent to this derivation by Gurney, which was based on a reasonable simplification of the case and gas dynamics, his wartime co‐worker, U. Fano [2], claimed to have calculated the proportion of kinetic energy remaining with the explosive gases following energy partition with the casing. This paper shows that both Fano’s equation for cased charge blast equivalence and a further derivation by Fisher in 1953 [3], based on Fano’s, are in fact inconsistent with Gurney’s reasonable physical model. Neither of these two reports has ever been the subject of independent peer‐review, despite having been extensively cited. This paper identifies the error made by Fano and copied by Fisher and draws attention to an alternate equation recently published by the author which gives similar predictions to that of Fisher, while being consistent with Gurney’s original derivation. Also, this paper establishes for the first time that the use of such equations for cased charge blast impulse equivalence is valid.     

Relative potencies and combination effects of steroidal estrogens in fish

The natural steroids estradiol-17beta (E2) and estrone (E1) and the synthetic steroid ethynylestradiol-17alpha (EE2) have frequently been measured in waters receiving domestic effluents. All of these steroids bind to the estrogen receptor(s) and have been shown to elicit a range of estrogenic responses in fish at environmentally relevant concentrations. At present, however, no relative potency estimates have been derived for either the individual steroidal estrogens or their mixtures in vivo. In this study the estrogenic activity of E2, E1, and EE2, and the combination effects of a mixture of E2 and EE2 (equi-potent fixed-ratio mixture), were assessed using vitellogenin induction in a 14-day in vivo juvenile rainbow trout screening assay. Median effective concentrations, relative to E2, for induction of vitellogenin were determined from the concentration-response curves and the relative estrogenic potencies of each of the test chemicals calculated. Median effective concentrations were between 19 and 26 ng L(-1) for E2, 60 ng L(-1) for E1, and between 0.95 and 1.8 ng L(-1) for EE2, implying that EE2 was approximately 11 to 27 times more potent than E2, while E2 was 2.3 to 3.2 times more potent than E1. The median effective concentration, relative to E2, for the binary mixture of E2 and EE2 was 15 ng L(-1) (comprising 14.4 ng L(-1) E2 and 0.6 ng L(-1) EE2). Using the model of concentration addition it was shown that this activity of the binary mixture could be predicted from the activity of the individual chemicals. The ability of each individual steroid to contribute to the overall effect of a mixture, even at individual no-effect concentrations, combined with the high estrogenic potency of the steroids, particularly the synthetic steroid EE2, emphasizes the need to consider the total estrogenic load of these chemicals in our waterways.     

Experimental Investigation of Grouted Helical Piers for Use in Foundation Rehabilitation

Building rehabilitation is critical for numerous older urban areas, many of which have inadequate foundations to support new demands. Consequently, development of practical methods to strengthen existing foundations is crucial. In engineering practice, both subsurface grouting and helical piers have been widely used to address these issues by strengthening the foundation. If the solid shaft of a typical helical pier is replaced by a hollow shaft, then helical piers provide the ability to deliver grout. It is hypothesized that these grouted helical pier systems could address foundation strengthening needs. This paper presents findings from an exploratory research program where grouting and pier placement tools were developed and tested on the large geotechnical centrifuge at the University of California, Davis. Experimental methods and procedures developed are presented, and observations regarding the formation of grout bulbs under different conditions are analyzed. Physical observation of the test specimens indicates that average grout bulb diameters of 0.6–1.9 times the helix diameter (Dh) are attainable. For similar grout mixes, 20–50% larger grout bulbs can be attained by adding just a modest amount of injection pressure. Future research may use these results to develop load performance data.     

Shear strengthening of reinforced concrete beams using different configurations of externally bonded carbon fibre reinforced plates

This paper deals with research undertaken at Oxford Brookes University into shear strengthening of reinforced concrete beams using externally bonded carbon fibre reinforced plastic plates (CFRP). Thirty-eight reinforced concrete beams of 1.8 m length were constructed and tested and are described in this paper. The relative performance of a group of sixteen beams with the same steel reinforcement but with different amounts of shear strengthening is discussed. All the beams were designed to fail in shear using a spreadsheet program. The spreadsheets were designed to ensure that the beams' flexural capacity exceeded the shear capacity after strengthening. The variables were: main reinforcement ratio, spacing between links in the shear span and different configurations of CFRP plates on shear spans. The concrete had an average compressive strength of 61.76 N/mm². The majority of the beams tested showed a significant improvement in shear strength by the addition of CFRP plates, with increases of between 19–122% over the control beams.