Spin-state ice in geometrically frustrated spin-crossover materials

Spin crossover materials contain metal ions that can access two spin-states: one low-spin (LS), the other high-spin (HS). We propose that frustrated elastic interactions can give rise to spin-state ices -- phases of matter without long-range order, characterized by a local constraint or `ice rule'. The low-energy physics of spin-state ices is described by an emergent divergence-less gauge field with a gap to topological excitations that are deconfined quasi-particles with spin fractionalized midway between the spins of the LS and HS states.Comment: Major edit, some new results; 8+2 page

Return to society.

The Labour government faces the abyss. The Conservative party cannot break from the discredited orthodoxies of its past. It has failed to win people’s trust and can only hope for an election victory on a minority of the vote. Bereft of a credible economic strategy it will divide the country. The politics of both parties now belong to the past, not to the future. As Gramsci said, ‘the crisis consists precisely in the fact that the old is dying and the new cannot be born.’1 The MPs expenses scandal, the constitutional crisis and the profiteering of the banking oligarchy, are all morbid symptoms of this interregnum. We do not know what the next election will bring nor can we predict the fate of the Labour party. The task now is to begin building a progressive left movement that unlike New Labour will break with the legacy of Thatcherism and establish a new hegemony

Structure-property relationships and the mechanisms of multistep transitions in spin crossover materials and frameworks

Spin crossover frameworks and molecular crystals display fascinating collective behaviours. This includes multi-step transitions with hysteresis and a wide variety of long-range ordered patterns of high-spin and low-spin metal centres. From both practical and fundamental perspectives it is important to understand the mechanisms behind these collective behaviours. We study a simple model of elastic interactions and identify thirty six different spin-state ordered phases. We observe spin-state transitions with between one and eight steps. These include both sharp transitions and crossovers, and both complete and incomplete spin crossover. We demonstrate structure-property relationships that explain these differences. These arise because through-bond interactions are antiferroelastic (favour metal centres with different spin-states); whereas, through-space interactions are typically ferroelastic (favour the same spin-state). In general, rigid materials with longer range elastic interactions lead to transitions with more steps and more diverse spin-state ordering, which explains why both are prominent in frameworks.Comment: 10+9 pages, 10+19 figures - fixed typos, updated figure

Diagnosis of an anaerobic pond treating temperate domestic wastewater: An alternative sludge strategy for small works

An anaerobic pond (AP) for treatment of temperate domestic wastewater has been studied as a small works sludge management strategy to challenge existing practice which comprises solids separation followed by open sludge storage, for up to 90 days. During the study, effluent temperature ranged between 0.1 °C and 21.1 °C. Soluble COD production was noted in the AP at effluent temperatures typically greater than 10 °C and was coincident with an increase in effluent volatile fatty acids (VFA) concentration, which is indicative of anaerobic degradation. Analysis from ports sited along the AP's length, demonstrated VFA to be primarily formed nearest the inlet where most solids deposition initially incurred, and confirmed the anaerobic reduction of sludge within this chamber. Importantly, the sludge accumulation rate was 0.06 m3 capita−1 y−1 which is in the range of APs operated at higher temperatures and suggests a de-sludge interval of 2.3–3.8 years, up to 10 times longer than current practice for small works. Coincident with the solids deposition profile, biogas production was predominantly noted in the initial AP section, though biogas production increased further along the AP's length following start-up. A statistically significant increase in mean biogas production of greater than an order of magnitude was measured between winters (t(n=19) = 5.52, P < 0.001) demonstrating continued acclimation. The maximum methane yield recorded was 2630 mgCH4 PE−1 d−1, approximately fifty times greater than estimated from sludge storage (57 mgCH4 PE−1 d−1). Anaerobic ponds at small works can therefore enable sludge reduction and longer sludge holding times than present thus offsetting tanker demand whilst reducing fugitive methane emissions currently associated with sludge storage, and based on the enhanced yield noted, could provide a viable opportunity for local energy generation

Do neighbourhood environmental perceptions affect practices?

In this paper, we examine how environmental practices related to public transit and urban green space use are influenced by perceptions of local level environmental change, neighbourhood inhabitation, and socio-demographic factors. The analysis shows that perceptions of change and neighbourhood inhabitation offer better explanations for changing local environmental practices than socio-demographic orientations. We contribute to social practice theory by drawing attention to the interplay of environmental perceptions and neighbourhood inhabitation as factors that facilitate changing environmental practices. By gaining insight into the relationship between perceptions of change and environmental practices, we thereby learn how sustainability goals, such as those embodied by SDG11, can be translated into social practices at the community level.Dans cet article, nous examinons comment les pratiques environnementales liées au transport en commun et à l’utilisation des espaces verts urbains sont influencées par les perceptions du changement environnemental au niveau local, l’habitation des quartiers et les facteurs sociodémographiques. L’analyse montre que les perceptions du changement et de l’habitat du quartier offrent de meilleures explications pour l’évolution des pratiques environnementales locales que les orientations sociodémographiques. Nous contribuons è la théorie de la pratique sociale en attirant l’attention sur l’interaction des perceptions environnementales et de l’habitation du quartier en tant que facteurs qui facilitent l’évolution des pratiques environnementales. En acquérant un aperçu de la relation entre les perceptions du changement et les pratiques environnementales, nous apprenons ainsi comment les objectifs de durabilité, tels que ceux incarnées par ODD (Agenda 2030 du développement durable), peuvent être traduits en pratiques sociales au niveau communautaire

Radical nostalgia, progressive patriotism and Labour's 'English problem'

‘Progressive patriots’ have long argued that Englishness can form the basis of a transformative political project, whether based on an historic tradition of resistance to state power or an open and cosmopolitan identity. However, this article suggests that the politics of Englishness present a number of specific dilemmas for Labour. First the historical narrative of a radical tradition in British history is not straightforwardly English and cannot easily be used to support a competitive politics of nationhood, in the way that disaffected English identifiers might desire. Second, the deliberately alternative nature of this ‘radical nostalgic’ narrative makes it an unlikely basis for a unifying national story. It is also at odds with Labour’s status as a successful party of government, committed to using the power of the British state, rather than opposing it. Finally, while ‘everyday Englishness’ may well align with core Labour values and be less socially conservative, intolerant or racially exclusive than it is often described, its very nature as an everyday practice, rather than a political identity makes it difficult for Labour to co-opt

Selection of screw characteristics and operational boundary conditions to facilitate post-flush urine and faeces separation within single household sanitation systems

To ensure adequate access to sanitation in developing economies, off-grid single household sanitation has been proposed which obviates the need for significant infrastructure capital investment. Whilst treatment at this scale is most efficient when coupled to source separation (i.e. urine from faeces), existing source separation solutions have proved difficult to implement in this context. In this study, screw extrusion is therefore investigated to provide ‘post-flush’ source separation. Both screw characteristics and operational boundary conditions were evaluated. Preferential screw characteristics included tapering of the shaft and progressive pitch reduction, linked to a small extrusion aperture, the combination of which enhanced solids extrusion efficiency and promoted higher solids concentration in the extruded fraction. Whilst maximum extrusion efficiency was observed at high rotational speeds (over 400 rpm), this also promoted free water transport. Operating below 300 rpm instead introduced selectivity for transport of faecal sludge over urine, enabling phase separation. Constraining the volumetric ratio of urine to faeces also enhanced the extrusion rate of faecal sludge by increasing feed viscosity sufficient to overcome backpressure imposed by unmasticated food particles that would otherwise restrict separation. Importantly, this study demonstrates the feasibility of screw extrusion for ‘post flush’ separation of urine and faeces which constitutes a significant advancement towards realising sanitation at a single household scale

The capabilities approach and critical social policy: lessons from the majority world?

The capabilities approach (CA) most closely associated with the thinner and thicker versions of Sen and Nussbaum has the potential to provide a paradigm shift for critical social policy, encompassing but also transcending some of the limitations associated with the Marshallian social citizenship approach. The article argues, however, that it cannot simply be imported from the majority world, rather there is a need to bear in mind the critical literature that developed around it. This is generally discussed and then critically applied to case studies of CA in the developed capitalist world, particularly the Equalities Review conducted for the Equality and Human Rights Commission