Crystal structure and drawing-induced polymorphism in poly(aryl ether ether ketone). IV

A new crystal modification induced by strain and denoted as form II exists alongside the dominant form I structure in the uniaxially oriented poly(ether ether ketone) (PEEK) and the related polymers. The crystal structure of form II for PEEK is also found to possess a two-chain orthorhombic packing with unit cell parameters of a equal to 0.475 nm, b equal to 1.060 nm, and c equal to 1.086 nm. More extended and flattened chain conformation of form II relative to that of form I is expected to account for an 8% increase in c-axis dimension, which is attributed to the extensional deformation fixed in situ through strain-induced crystallization during uniaxial drawing. Annealing experiments suggest that form II is thermodynamically metastable and can be transformed into more stable form I by chain relaxation and reorganization at elevated temperature without external tension. This strain-induced polymorphism exists universally in the poly(aryl ether ketone) family. (C) 1999 John Wiley & Sons, Inc.

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s .2. Poly(ether ether ketone ketone), PEEKK

The crystal structure, morphology and polymorphism induced by uniaxial drawing of poly(ether ether ketone ketone) [PEEKK] have been studied by transmission electron microscopy (TEM), electron diffraction (ED) and wide angle X-ray diffraction (WAXD). On the basis of WAXD and ED patterns,the crystal structure of unoriented PEEKK is determined to have two-chain orthorhombic packing with unit cell parameters of a 0.772 nm, b = 0.600 nm, c = 1.004 nm (form I), A stress-induced crystal modification (form II) is identified and found to possess a two-chain orthorhombic lattice with unit cell dimensions of a = 0.461 nm, b = 1.074 nm, c = 1.080 nm. The 7.5% increase in c-axis dimension for form II is attributed to an overextended chain conformation, arising from extensional deformation during uniaxial drawing and fixed ''in-situ'' through strain-induced crystallization. The average ether-ketone bridge bond angles in form II crystal are determined to be 148.9 degrees by using standard bond lengths. The crystal morphology of PEEKK bears a great similarity to that of PEEK. The crystals grow in the form of spherulites and have the b-axis of unit cell radial. The effects of draw rate on strain-induced crystallization and induction of form II structure are also discussed.

The crystal structure and drawing induced polymorphism in poly(aryl ether ketone)s .3. Crystallization during hot-drawing of poly(ether ether ketone ketone)

The evolution of crystallinity and polymorphism during hot-drawing of amorphous poly(ether ether ketone ketone) (PEEKK) as a function of strain rate, draw ratio, and temperature was investigated. In modification I, the competition of chain extension and molecular alignment is responsible for the strain rate and temperature dependence. Modification II crystallization is basically controlled by chain extension during stretching. The former can be transformed into the latter via relaxation during stretching or annealing at elevated temperature.

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s .1. Poly(oxybiphenyl-4-4'-diyloxy-1,4-phenylenecarbonyl-1,3-phenylenecarbonyl-1,4-phenylene)

Crystal structure and polymorphism induced by uniaxial drawing of a poly(aryl ether ketone) [PEDEKmK] prepared from 1,3-bis(4-fluorobenzoyl)benzene and biphenyl-4,4'-diol have been investigated by means of transmission electron microscopy (TEM), electron diffraction (ED), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The melting and recrystallization process in the temperature range of 250-260 degrees C, far below the next melting temperature (306 degrees C), was identified and found to be responsible for the remarkable changes in lamellar morphology. Based on WAXD and ED patterns, it was found that crystal structure of isotropic-crystalline PEDEKmK obtained under different crystallization conditions (melt-crystallization, cold-crystallization, solvent-induced crystallization, melting-recrystallization, and crystallization from solution) keeps the same mode of packing, i.e., a two-chain orthorhombic unit cell with the dimensions a = 0.784 nm, b = 0.600 nm, and c = 4.745 nm (form I). A second crystal modification (form II) can be induced by uniaxial drawing above the glass transition temperature, and always coexists with form I. This form also possesses an orthorhombic unit cell but with different dimensions, i.e., a = 0.470 nm, b = 1.054 nm, c = 5.064 nm. The 0.32 nm longer c-axis of form II as compared with form I is attributed to an overextended chain conformation due to the expansion of ether and ketone bridge bond angles during uniaxial drawing. The temperature dependence of WAXD patterns for the drawn PEDEKmK suggests that form II can be transformed into the more stable form I by relaxation of overextended chains and relief of internal stress at elevated temperature in absence of external tension.

Children drawing toy commercials: re-imagining television production features

Griffiths, M. (2005). Children drawing toy commercials: re-imagining television production features. Visual Communication. 4(1), pp.21-37. RAE2008

Response to the review of the white paper on Irish aid. The urbanisation of poverty: drawing on the skills and techniques of spatial planning to support the aid programme

Submission on behalf of UCC to the Government Consultation on the White paper on Irish Aid

Problems with drawing lines: Theo-geographies of the Catholic parish in Ireland

While people in Catholic parishes in Ireland appear keenly aware of parish boundaries, these understandings are more often oral than cartographic. There is no digital map of all of the Catholic parishes in Ireland. However, the institutional Catholic Church insists that no square kilometre can exist outside of a parish boundary. In this paper, I explain a process whereby the Catholic parishes of Ireland were produced digitally. I will outline some of the technical challenges of digitizing such boundaries. In making these maps, it is not only a question of drawing lines but mapping people’s understanding of their locality. Through an example of one part of the digitisation project, I want to talk about how verifying maps with local people often complicates something which may have at first sight seemed simple. The paper ends on a comparison with how other communities of interest are territorialised in Ireland and elsewhere to draw out some broader theoretical and theological issues of concern.

Within the carnal: re-reading Merleau-Ponty through the language of drawing

In order to present visual art as a paradigm for philosophy, Merleau-Ponty investigated the creative processes of artists whose work corresponded closely with his philosophical ideas. His essays on art are widely valued for emphasising process over product, and for challenging the primacy of the written word in all spheres of human expression. While it is clear that he initially favoured painting, Merleau-Ponty began to develop a much deeper understanding of the complexities of how art is made in his late work in parallel with his advancement of a new ontology. Although his ontology remains unfinished and only exists as working notes and a manuscript entitled The Visible and Invisible, Merleau-Ponty had begun to appreciate the fundamental role drawing plays in the making of art and the creation of a language of expression that is as vital as the written or spoken word. Through an examination of Merleau-Ponty’s unfinished manuscript and working notes my thesis will investigate his working methods and use of materials and also explore how he processed his ideas by using my own art practice as the basis of my research. This research will take the form of an inquiry into how the unfinished and incomplete nature of text and artworks, while they are still ‘works in progress’, can often reveal the more human and carnal components of creative processes. Applying my experience as a practitioner and a teacher in an art school, I focus on the significance of drawing practice for Merleau-Ponty’s later work, in order to rebalance an overemphasis on painting in the literature. Understanding the differences between these two art forms, and how they are taught, can offer an alternative engagement with Merleau-Ponty’s later work and his struggle to find a language to express his developing new ontology. In addition, by re-reading his work through the language of drawing, I believe we gain new insights which reaffirm Merleau-Ponty's relevance to contemporary art making and aesthetics.

A multilevel algorithm for force-directed graph drawing

We describe a heuristic method for drawing graphs which uses a multilevel technique combined with a force-directed placement algorithm. The multilevel process groups vertices to form clusters, uses the clusters to define a new graph and is repeated until the graph size falls below some threshold. The coarsest graph is then given an initial layout and the layout is successively refined on all the graphs starting with the coarsest and ending with the original. In this way the multilevel algorithm both accelerates and gives a more global quality to the force- directed placement. The algorithm can compute both 2 & 3 dimensional layouts and we demonstrate it on a number of examples ranging from 500 to 225,000 vertices. It is also very fast and can compute a 2D layout of a sparse graph in around 30 seconds for a 10,000 vertex graph to around 10 minutes for the largest graph. This is an order of magnitude faster than recent implementations of force-directed placement algorithms.

The Daedalus system: A tool for the Italian investigating magistrate

Daedalus is a computer tool, developed by an Italian magistrate - Carmelo Asaro - and integrated in his own daily routine as an investigating magistrate conducting inquiries, then as a prosecutor if and when the case investigated goes to court. This tool has recently been adopted by magistrates in judiciary offices throughout Italy, spawning moreover other related projects. First, this paper describes a sample session with daedalus. Next, an overview of an array of judicial tools leads to positioning daedalus in the context of the spectrum.

Statistical investigations - drawing it all together

The author's approach to teaching an integrative unit to a small group of master’s level Applied Statistics students in 2000-2001 is described. Details of the various activities such as data analysis, reading and discussion of papers, and training in consultancy skills are given, as also are details of the assessment. The students’ and lecturer’s views of the unit are discussed.

A multilevel algorithm for force-directed graph-drawing

We describe a heuristic method for drawing graphs which uses a multilevel framework combined with a force-directed placement algorithm. The multilevel technique matches and coalesces pairs of adjacent vertices to define a new graph and is repeated recursively to create a hierarchy of increasingly coarse graphs, G0, G1, …, GL. The coarsest graph, GL, is then given an initial layout and the layout is refined and extended to all the graphs starting with the coarsest and ending with the original. At each successive change of level, l, the initial layout for Gl is taken from its coarser and smaller child graph, Gl+1, and refined using force-directed placement. In this way the multilevel framework both accelerates and appears to give a more global quality to the drawing. The algorithm can compute both 2 & 3 dimensional layouts and we demonstrate it on examples ranging in size from 10 to 225,000 vertices. It is also very fast and can compute a 2D layout of a sparse graph in around 12 seconds for a 10,000 vertex graph to around 5-7 minutes for the largest graphs. This is an order of magnitude faster than recent implementations of force-directed placement algorithms.

L'histoire assassinee: Manfredo Tafuri and the present

Italian historian Manfredo Tafuri develops his ‘historical project’ in architecture during the 1960’s and 1970’s in three seminal books, which reach the English speaking specialist audience with a certain delay. Histories and Theories of Architecture (1968), which prepares the ground for the redefinition of a critical and independent history of architecture is first translated in English in 1979. Architecture and Utopia (Progetto e utopia, 1973) is translated in 1976, and becomes a point of reference for architectural histories and for the definition of architectural theories, mainly in the United States. The Sphere and the Labyrinth (1980), translated in 1987, is the text which formally defines and presents the ‘historical project’. Tafuri’s dense and highly politicized prose is often subjected in the English versions to numerous simplifications and reductive interpretations. Yet, the time lag and the space between languages that these translations occupy are inhabited by polemical and fertile reactions to the texts from the world of architectural design. Symptomatic of all, Aldo Rossi’s L’architecture assassinée, a rebuke in drawing to some of Tafuri’s remarks in Architecture and Utopia that seemed to suggest -but the interpretation is arguable– the ‘death’ of architecture as project (progetto). Tafuri’s texts instigate a dialogue between architectural history and practice, particularly relevant at a time in the development of the discipline when history was being redefined in its critical role as a ‘project’ –thus appropriating the active and propositional role traditionally assigned to architectural design–, while architectural design –still coping with the legacy of Modernism and with changed production systems- often found itself relegated to the paper of exhibitions, competitions and theoretical projects. This paper explores the relationship between architectural history and design in Tafuri’s work, focusing on recent reconsideration and interpretations of his work. It argues that, beyond instrumental simplifications, Tafuri’s ‘project’ remains active and essential in architecture’s critical culture today.

Trade credit linkages along the supply chain: evidence for the Italian textile sector

We examine the trade credit linkages among firms within a supply chain to reckon the effect of such linkages on the propagation of liquidity shocks from downstream to upstream firms. We choose a sample appropriate for this task, consisting of a large data set of Italian firms from the textile industry, a well known example of a comprehensive manufacturing cluster featuring a large number of small and specialized firms at each level of the supply chain. The results of the analysis indicate that the level of trade credit that firms provide to their suppliers is positively related to the level of trade credit granted to their clients: when the level of trade credit granted to clients divided by sales goes up by 1, the level of trade credit provided to suppliers divided by cost-of goods-sold goes up by an amount that varies between 0,22 and 0,52. Since all firms along the chain are linked by trade credit relationships, an increase in the level of trade credit granted by wholesalers generates a liquidity cascade throughout the chain. We designate the overall increase in the level of trade credit among all firms in the chain as a result of a unitary impulse in the level of trade credit granted by wholesalers as the multiplier effect of trade credit for the industry chain. We estimate such multiplier to vary between 1.28 and 2.04. We also investigate the effect of final demand on the level of trade credit sourced by firms at various levels of the chain and, in particular, whether such effect is amplified for firms further up in the chain as a result of liquidity propagation via trade credit linkages. We uncover evidence of such amplification when the links of liquidity transmission along the chain are individually modeled and estimated. An unitary increase in wholesalers’ sales is found to produce an effect on trade payables among firms at the top of the chain (i.e., Preparers and Spinners) that is more than twice as big as the corresponding effect among firms at the bottom of the chain (i.e., Wholesalers).

Drawing the net: internet identification, internet use, and the image of internet users

Theory and research suggest that Internet identification may account for some of the gender divide in Internet use. Internet identification is a type of domain identification, and is inherently bound with images of those who use the Internet, a domain traditionally conceived as masculine. Combining the “draw an Internet user” test with an Internet identification scale, this study tests two hypotheses: participants drawing gender-concordant images will (i) identify with and (ii) use the Internet more than those drawing gender-discordant images. Participants were 371 students (121 males, 250 females) from three universities in the United Kingdom and Australia. The need to challenge masculinized images of the Internet is discussed.