The consolidation and bond strength of rafted sea ice

The consolidation and bond strength of rafted sea ice were investigated through a series of experiments undertaken in the Ice Physics Laboratory at the UCL. To simulate a section of rafted sea ice, blocks of laboratory grown saline ice were stacked in an insulated tank with spacers between adjacent blocks to allow saline water to flood in. The rate of consolidation was then monitored using a combination of temperature readings recorded in the ice and liquid layer, salinity measurements of the liquid layer, and cores taken at specific times of interest. Two states of consolidation were observed: thermodynamic consolidation where the ice blocks were physically bonded but the bond strength was weak, and mechanical consolidation where the bond had reached full strength. Results showed that the rafted ice had physically bonded in less than a day, however it took many more days (6 to 30 depending on the environmental conditions) for the bond to reach maximum strength. Increasing the thickness of the ice, the salinity of the water and the inter-block gap size all increased the consolidation time. Once consolidated, ice cores were taken and sheared using the asymmetric four-point bending method to measure the strength of the bond between the ice blocks. These were then compared to the shear strength of solid ice blocks simulating level sea ice. Our results show that the shear strength of the bond between the rafted ice blocks is about 30% weaker than that of level ice.

Synergetic effects of the Cu/Pt{110} surface alloy: enhanced reactivity of water and carbon monoxide

We have used synchrotron-based high-resolution X-ray photoelectron spectroscopy in combination with ab initio density functional theory calculations to investigate the characteristics of water and CO adsorption on the bimetallic Cu/Pt{110}-(2 x 1) surface at a Cu coverage near 0.5 ML. Cu fills the troughs of the reconstructed clean surface forming nanowires, which are stable up to 830 K. Their presence dramatically influences the adsorption of water and CO. Water adsorption changes from intact to partially dissociated while the desorption temperature of CO on this surface increases by up to 27 K with respect to the clean Pt{110} surface. Ab initio calculations and experimental valence band spectra reveal that the Cu 3d-band is narrowed and shifted upward with respect to bulk Cu surfaces. This and electron donation to surface Pt atoms cause the increase in the bond strength between CO and the Pt surface atoms. The pathway for water dissociation occurs via Cu surface atoms. The heat of adsorption of water bonding to Cu surface atoms was calculated to be 0.82 eV, which is significantly higher than on the clean Pt{110} surface; the activation energy for partial dissociation is 0.53 eV (not corrected for zero point energy).

Tuning of intramolecular electron transfer between Ru(II) and the disulfide bond

Reaction of 2,2'-dithiodipyridine (DTDP) with cis-Ru(bpy)(2)Cl-2 (bpy = 2,2'-bipyridine) and cis-Ru(phen)(2)Cl-2 (phen = 1,10-phenanthroline) respectively yields the dicationic species [Ru(bpy) (2)(DTDP)](2+) and [Ru(phen)(2) (DTDP)](2+) in which the S-S bond of DTDP remains intact. The S-S bond undergoes a reductive cleavage when DTDP is reacted with cis-Ru(bisox)(2)Cl-2 (bisox = 4,4,4',4'-tetramethyl-2,2'-bisoxazoline) under identical conditions to generate the monocationic species [Ru(bisox)(2)(2-thiolatopyridine)]. The intramolecular electron transfer between the metal and the S-S bond is found to be subtly controlled by the crystal field strength of the ancillary bidentate N-donor ligands.

Teachers' networks in and out of school

A 'mapping task' was used to explore the networks available to head teachers, school coordinators and local authority staff. Beginning from an ego-centred perspective on networks, we illustrate a number of key analytic categories, including brokerage, formality, and strength and weakness of links with reference to a single UK primary school. We describe how teachers differentiate between the strength of network links and their value, which is characteristically related to their potential impact on classroom practice.

Rotational symmetry of a methane molecule and the bond angle

The rotational symmetry of a methane molecule can be used to great advantage to calculate the bond angle. The problem is worked out in this article.

European CMBS pricing: bond, mortgage and real estate characteristics

The recent global economic crisis is often associated with the development and pricing of mortgage-backed securities (i.e. MBSs) and underlying products (i.e. sub-prime mortgages). This work uses a rich database of MBS issues and represents the first attempt to price commercial MBSs (i.e. CMBSs) in the European market. Our results are consistent with research carried out in the US market and we find that bond-, mortgage-, real estate-related and multinational characteristics show different degrees of significance in explaining European CMBS spreads at issuance. Multiple linear regression analysis using a databank of CMBSs issued between 1997 and 2007 indicates a strong relationship with bond-related factors, followed by real estate and mortgage market conditions. We also find that multinational factors are significant, with country of issuance, collateral location and access to more liquid markets all being important in explaining the cost of secured funding for real estate companies. As floater coupon tranches tend to be riskier and exhibit higher spreads, we also estimate a model using this sub-set of data and results hold, hence reinforcing our findings. Finally, we estimate our model for both tranches A and B and find that real estate factors become relatively more important for the riskier investment products.

Effluent quality and ammonia emissions from out-wintering pads in England, Wales and Ireland

Out-wintering pads offer a reduced cost system for wintering cattle, minimising damage to pasture, providing animal welfare and production benefits, and generate, potentially, a more manageable effluent and lower ammonia emissions. The objectives of the present study were (i) to contribute to improved understanding of the factors impacting on effluent quality, ammonia emissions and animal welfare via observations on four farm-based out-wintering pads (ComOWPs) in England, Wales and Ireland and more detailed studies undertaken on four experimental OWPs (ExpOWPs) constructed at Rothamsted Research North Wyke, Devon, England and (ii) to corroborate the effluent quality data from both the ComOWPs and the ExpOWPs, with findings in the literature. Woodchip size, feeding management and area allowance were the treatment factors applied on the ExpOWPs. These three factors were randomised across the four ExpOWPs, over four 6–7 week periods. Effluent quality from the ExpOWPs was sampled frequently in a flow proportional way and analysed for total N (TN); total P (TP); total solids (TS); ammonium-N (NH4+-N); nitrate-N (NO3−-N). Beef cattle were periodically weighed for determination of live weight gain (LWG). An approximate nitrogen balance was calculated as a means of understanding its partitioning and fate during and after the ExpOWPs use. Effluent quality from the ComOWPs was sampled frequently, also in a flow-proportional way, and analysed for TN, TP, TS, NH4+-N, NO3−-N, total K and COD. Effluent quality data from the ExpOWPs showed no significant differences (P > 0.05) between treatments, with average concentrations of 1095 mg l−1, and 806 mg l−1, for TN and NH4+-N, respectively. Average effluent concentrations from the ComOWPs were 356 mg l−1 TN and 124 mg l−1 NH4+-N. Ammonia emissions from the ExpOWPs showed no significant differences (P > 0.05) between the treatments, with average mean emission rates of 2.5 g m−2 d−1 NH3-N, respectively. A positive correlation was established between NH3-N emission rate and wind speed. Emission rates from the ComOWPs ranged from 0.7 to 1.6 g m−2 d−1 NH3-N. Average daily LWG on the ExpOWPs was 1.33 kg steer−1 d−1. The effluent from both the ComOWPs and ExpOWPs were more similar with dirty water and of consistently lower strength than beef cattle slurry, as supported by findings in the literature, and therefore, it is suggested to be subject to the regulatory requirements of dirty water rather than slurry.

'A theatre of ruins'. Edward Bond & Samuel Beckett: theatrical antagonists

The playwright Edward Bond has long made known his antagonism to dramatists allied to Martin Esslin’s Theatre of the Absurd. The work of Samuel Beckett has come in for particular criticism by Bond. Using published writings (and unpublished correspondence between myself and Bond), I hope to trace the development of this antagonism between ‘Bondian’ and ‘Beckettian’ views of theatre. However, this article will also set out to argue that both early work such as The Pope’s Wedding (1962), and more recent work such as Coffee (1995), make use of motifs, characters and ideas from Beckett’s theatre. The article will set out provisional reasons why Bond, despite his misgivings, is not averse to incorporating elements from Beckett’s ‘theatre of ruins’, as he terms it, into his own work.

'Out Vile Jelly': Sarah Kane's 'Blasted' & Shakespeare's 'King Lear'

Sarah Kane's notorious 1995 debut, Blasted, has been widely though belatedly recognized as a defining example of experiential or ‘in-yer-face’ theatre. However, Graham Saunders here argues that the best playwrights not only innovate in use of language and dramatic form, but also rewrite the classic plays of the past. He believes that too much stress has been placed on the play's radical structure and contemporary sensibility, with the effect of obscuring the influence of Shakespearean tradition on its genesis and content. He clarifies Kane's gradually dawning awareness of the influence of Shakespeare's King Lear on her work and how elements of that tragedy were rewritten in terms of dialogue, recast thematically, and reworked in terms of theatrical image. He sees Blasted as both a response to contemporary reality and an engagement with the history of drama. Graham Saunders is Senior Lecturer in Theatre Studies at the University of the West of England, Bristol, and author of the first full-length study of Kane's work: ‘Love Me or Kill Me’: Sarah Kane and the Theatre of Extremes (Manchester University Press, 2002). An earlier version of this article was given as a paper at the ‘Crucible of Cultures: Anglophone Drama at the Dawn of a New Millennium’ conference in Brussels, May 2001. Saunders is currently working on articles about Samuel Beckett and Edward Bond