CODE TO CRAFT – BEYOND THE VOXEL

The digital nature of post-industrial societies has profound implications for architectural design, documentation and construction. Digital tools and technologies bridge the representational divide between conception and realization, empowering architects to regain control of the design, fabrication and assemblage processes. This paper will discuss ideas and concepts to facilitate the fabrication of non-standard, context-specific, geometrically complex architecture and components. Two case studies exploring digital fabrication and metal casting will be described alongside implications for the fields of architectural design and construction

Effect of Replacement of As by Ge and Sb on the Photo-Response under Near Infrared Femtosecond Laser Irradiation in As-based Sulfide Glasses

Bulk glasses having the compositions As42S58, As36Sb6S58, and As36Ge6S58 have been irradiated at 800 nm using a femtosecond-pulsed laser to determine the relationship between composition and photo-response. Localized variation in the glass volume (photo-expansion) has been determined through interferometric measurements of surface exposures, whereas induced refractive index change (photo-darkening) was determined from the diffraction efficiency of subsurface direct-written phase gratings. To understand the compositional dependence of the photo-response, the linear and nonlinear optical properties and structure of the unexposed glasses have been compared. The ablation threshold is shown to be controlled by variation of the nonlinear absorption, related to shifts of the absorption band gap with exchange of As by Ge or Sb. Changes in the unexposed network structure show that partial replacement of As by Ge or Sb induces an increased number of As–As bonding defects in the glass, particularly in the form of As4S4 molecular units which become polymerized into the network, impacting the photo-modification process. The Ge was found to induce an increase in the ablation threshold, and enhance both photo-darkening and photo-expansion effects, whereas Sb was shown to decrease ablation threshold and inhibit photo-darkening while enhancing photo-expansion

Computation and material practice in architecture: intersecting intention and execution during design development

 It is generally believed that computation and computer numerical control (CNC) manufacturing technologies empower architects by enabling better integrated architectural design to production processes. While this is a tantalizing prospect, there is no clear strategy in place for achieving this goal. Furthermore, the extent to which design, engineering and construction might be integrated around digital technologies is currently limited as the computational processes architects use for design exploration are not typically informed by material logic and the logistics of materialisation. My research explores whether computation and CNC manufacturing can support more informed design methods and better integrated production processes in architecture. I identify the critical factors involved in pursuing this goal and elaborate on an integral computational methodology capable of enhancing the bond between designing and making in architecture. My hypothesis is that digitally mediated design and manufacturing can strengthen the relationship between intention and execution by enabling closer engagement with fabrication during early design exploration, and by supporting more informed decision making via dynamic design representations with embedded material intelligence. This hypothesis has been developed and tested through project led research. Although different in nature, the three investigations I have undertaken serve as complimentary vehicles of discovery and evidence for my claims. Each investigation was devised and carried out in response to practical observations, a critical review of literature focu¬sing on historical and contemporary relationships between design and construction, and a series of precedent studies related to materially informed design computing. As a group they contribute to understanding how digital technologies might be employed by architects to enhance and expand design to production processes, and shed light on some of the technical, cultural and philosophical implications of a deeper engagement with materials and processes of making within the discipline of architecture. My research concludes that new kinds of interactive simulation and evaluation tools, and access to digital fabrication technologies, enables an accelerated generation, evaluation and calibration process during early design exploration. This mutually informed digital-material feedback loop makes it possible to rapidly develop acute material intuition, and consequently to conceive new kinds of architectural systems and materialisation strategies which could lead to better use of available resources, more innovative design and a stronger bond between intent and outcome through more streamlined design to production processes. The digitally supported materially informed methodology that I outline encourages a shift in design process and attitude, away from a visually driven mode of architectural composition towards material practice - an approach in which the self-organising logic of materials and the logistics of materialisation are used to actively inform design exploration, refinement and construction processes. My project based outcomes, findings and observations prompt re-evaluation of the conventional distance between architects and processes of making by highlighting the importance of deep material engagement and broad practical knowledge when utilising computation and CNC manufacturing technologies for designing and producing architecture

Intermediate phase, network demixing, boson and floppy modes, and compositional trends in glass transition temperatures of binary AsxS1-x system

The structure of binary As_xS_{1-x} glasses is elucidated using modulated-DSC, Raman scattering, IR reflectance and molar volume experiments over a wide range (8%<x<41%) of compositions. We observe a reversibility window in the calorimetric experiments, which permits fixing the three elastic phases; flexible at x<22.5%, intermediate phase (IP) in the 22.5%<x<29.5% range, and stressed-rigid at x>29.5%. Raman scattering supported by first principles cluster calculations reveal existence of both pyramidal (PYR, As(S1/2)3) and quasi-tetrahedral(QT, S=As(S1/2)3) local structures. The QT unit concentrations show a global maximum in the IP, while the concentration of PYR units becomes comparable to those of QT units in the phase, suggesting that both these local structures contribute to the width of the IP. The IP centroid in the sulfides is significantly shifted to lower As content x than in corresponding selenides, a feature identified with excess chalcogen partially segregating from the backbone in the sulfides, but forming part of the backbone in selenides. These ideas are corroborated by the proportionately larger free volumes of sulfides than selenides, and the absence of chemical bond strength scaling of Tgs between As-sulfides and As-selenides. Low-frequency Raman modes increase in scattering strength linearly as As content x of glasses decreases from x = 20% to 8%, with a slope that is close to the floppy mode fraction in flexible glasses predicted by rigidity theory. These results show that floppy modes contribute to the excess vibrations observed at low frequency. In the intermediate and stressed rigid elastic phases low-frequency Raman modes persist and are identified as boson modes. Some consequences of the present findings on the optoelectronic properties of these glasses is commented upon.Comment: Accepted for PR

Effect of cluster size of chalcogenide glass nanocolloidal solutions on the surface morphology of spin-coated amorphous films

Amorphous chalcogenide thin film deposition can be achieved by a spin-coating technique from proper solutions of the corresponding glass. Films produced in this way exhibit certain grain texture, which is presumably related to the cluster size in solution. This paper deals with the search of such a correlation between grain size of surface morphology of as-deposited spin-coated As33S67 chalcogenide thin films and cluster size of the glass in butylamine solutions. Optical absorption spectroscopy and dynamic light scattering were employed to study optical properties and cluster size distributions in the solutions at various glass concentrations. Atomic force microscopy is used to study the surface morphology of the surface of as-deposited and thermally stabilized spin-coated films. Dynamic light scattering revealed a concentration dependence of cluster size in solution. Spectral-dependence dynamic light scattering studies showed an interesting athermal photo-aggregation effect in the liquid state.Comment: 15 pages, 8 figure

Effects of taurine supplementation on bone mineral density in ovariectomized rats fed calcium deficient diet

Taurine supplementation has been shown to have a beneficial effect on femur bone mineral content in ovariectomized rats. It therefore seemed desirable to find out whether the beneficial effect of taurine on ovariectomized rats fed calcium deficient diet could also be reproduced. Forty female Sprague-Dawley rats were divided into two groups. One group was OVX and the other group received sham operation (SHAM), and received either control diet or a taurine supplemented diet for 6 weeks. All rats were fed on calcium deficient diet (AIN-93: 50% level of calcium) and deionized water. Bone mineral density (BMD) and bone mineral content (BMC) were measured in spine and femur. The serum and urine concentrations of calcium and phosphorus were determined. Bone formation was measured by serum osteocalcin and alkaline phosphatase (ALP) concentrations. Bone resorption rate was measured by deoxypyridinoline (DPD) crosslinks immunoassay and corrected for creatinine. Urinary calcium and phosphorus excretion, osteocalcin in blood and cross link value were not significantly different among the groups. Within the OVX group, the taurine supplemented group had not higher femur bone mineral content than the control group. This study established the need for a study on the taurine effect on bone with different calcium levels

Chalcogenide Glass Optical Waveguides for Infrared Biosensing

Due to the remarkable properties of chalcogenide (Chg) glasses, Chg optical waveguides should play a significant role in the development of optical biosensors. This paper describes the fabrication and properties of chalcogenide fibres and planar waveguides. Using optical fibre transparent in the mid-infrared spectral range we have developed a biosensor that can collect information on whole metabolism alterations, rapidly and in situ. Thanks to this sensor it is possible to collect infrared spectra by remote spectroscopy, by simple contact with the sample. In this way, we tried to determine spectral modifications due, on the one hand, to cerebral metabolism alterations caused by a transient focal ischemia in the rat brain and, in the other hand, starvation in the mouse liver. We also applied a microdialysis method, a well known technique for in vivo brain metabolism studies, as reference. In the field of integrated microsensors, reactive ion etching was used to pattern rib waveguides between 2 and 300 μm wide. This technique was used to fabricate Y optical junctions for optical interconnections on chalcogenide amorphous films, which can potentially increase the sensitivity and stability of an optical micro-sensor. The first tests were also carried out to functionalise the Chg planar waveguides with the aim of using them as (bio)sensors