Evolution of Clay Morphology in Polypropylene/Montmorillonite Nanocomposites upon Equi-biaxial Stretching: A Solid-State NMR and TEM Approach

Solid-state NMR and TEM were used to quantitatively examine the evolution of clay morphology upon equibiaxial stretching of polypropylene/montmorillonite (PP-MMT) nanocomposites up to a stretch ratio (?= final length/initial length) of 3.5. 1 H spin-lattice relaxation times were measured by the saturation-recovery sequence. For the nanocomposites, initial portions of the magnetization recovery
curves (e~20 ms) were found to depend on v t, indicative of diffusion-limited relaxation and in agreement with calculations based on estimates of the spin-diffusion barrier radius surrounding the paramagnetic centers in the clay, the electron-nucleus coupling constant, and the spin-diffusion coefficient. Initial slopes of these magnetization recovery curves directly correlated with the fraction of clay/polymer interface. New clay surface was exposed as a near linear function of strain. Long-time portions of the magnetization recovery curves yielded information on the average interparticle separations, which decreased slowly before reaching a plateau at ?=~2.5 as particles aligned. TEM images supported these findings and were used to define and quantify degrees of exfoliation and homogeneity from the NMR data. Exfoliation, defined as (platelets/ stack)-1, increased from 0.38 (unstretched) to 0.80 at ? = 3.5 for PP-MMT nanocomposites stretched at
150 C and 16 s-1. A lower stretch temperature, 145 C, which is slightly below melting onset, led to an exfoliation degree of 0.87 at ?= 2.8, consistent with the ability of higher melt viscosities to allow for higher shear stress transfer. Exposure of new clay surface is attributed to aggregate breakup and orientation at low strains (? e ~2) and to platelets sliding apart at higher strains.

Archaeological and Palaeoecological investigations of a Middle Bronze Age settlement at Ballyarnet Lake, Co. Derry

Excavations at Ballyarnet Lake, Co Derry, have identified a Middle Bronze Age settlement site at the margins of the lake. The site is characterised by a palisaded enclosure surrounding a structure containing a hearth. Finds include a large quantity of Cordoned Urn ware, lithics and a faience bead. Palaeoenvironmental studies, including pollen, plant macrofossil and beetle analyses, provide insights into the environmental background of the settlement. The site is considered in terms of the broader context of Middle Bronze Age settlement.

Architecture, memory and historical continuity in Old Cairo

The hawari (local communities) of Old Cairo resemble a unique societal context whose history is actively involved in the contemporary everyday production of local habits, traditions and social practice. By the virtue of its durability and ability to survive, Architecture brings events and traditions of the past alive into the present through the spatial transformation, social practice and the value of the historical-fabric. The presence of buildings and houses from different historical periods has helped the local community’s memory to carry social practices over from one generation to another. This article explores the relationship between architecture, memory and everyday social practices through determining the way architecture moderates community experiences and communicates narratives among generations in haret al-Darb al-Asfar in old Cairo. Architecture emerges as a moderator of cross-time communication and as physical elements that help visualize history, situate values and materialize local traditions in old Cairo. Architecture, as process and product this article reports, works as agent of continuity, which in conjunction with the narrators, brings the full experience of the past alive in the present and helps guide future generations.

Policing the Globe: State Sovereignty and the International in the Post-9/11 Crime Novel

Two recent studies of 9/11 literature are dismissive of the contributions that crime and espionage novels have made to ongoing efforts to map the significance of 9/11 and its aftermath. My essay contests the assumption that only literary fiction – which pays sufficient attention to trauma – can “bear witness” to the events of 9/11 and argues that such fiction is, in fact, singularly ill-equipped to illuminate the complex geo-political circumstances that 9/11 entrenched and transformed. By contrast, genre novels by John Le Carré and Don Winslow have responded in imaginative and critical ways to post-9/11 and avowedly trans-national securitization initiatives and hence to efforts to trouble traditional accounts of state sovereignty.

COUNTER-STATE ZIONISM AND POLITICAL ZIONISM

This article reviews the debate between Political Zionism and Counter-State Zionism, a little know and suggestive interpretation of Zionism

The Ties That Bind Us: Ritual, Fusion, and Identification

Most social scientists endorse some version of the claim that participating in collective rituals promotes social cohesion. The systematic testing and evaluation of this claim, however, has been prevented by a lack of precision regarding the nature of both ‘ritual’and ‘social cohesion’ as well as a lack of integration between the theories and findings of the social and evolutionary sciences. By directly addressing these challenges, we argue that a systematic investigation and evaluation of the claim that ritual promotes social cohesion is achievable.

We present a general and testable theory of the relationship between ritual, cohesion, and cooperation that more precisely connects particular elements of ‘ritual,’ such as causal opacity and emotional arousal, to two particular forms
of ‘social cohesion’: group identification and identity fusion. Further, we ground this theory in an evolutionary account of why particular modes of ritual practice would be adaptive for societies with particular resource acquisition strategies. In setting out our conceptual framework we report numerous ongoing investigations that test our hypotheses against data from controlled psychological experiments as well as from theethnographic, archaeological, and historical records.