Development of Boundary Structures for Complex-Shaped Buildings

Over the past few years, the field of architecture has witnessed revolutionary changes in design. The recent completions of Frank O. Gehry’s projects brought unprecedented attention to complex-shaped, nonconventional design. In following these latest trends, the author has been drawn to the issue concerning the structural systems currently being adopted in realizing these complicated designs. It is perhaps inevitable that the traditional structural systems, comprised of structural elements suitable for use in conventional linear shapes, face tremendous challenges and limitations in building such complicated designs. In this context, this research consists of proposing a new alternative by employing “boundary structures with continuously changing curvature,” which follow the complex-curved envelope surface, as well as fabricating an experimental model made of polymer composite materials with computer-aided design/computer-aided engineering/computer-aided manufacturing technologies. Consequently, the study aims at offering architects unprecedented freedom in design and a new paradigm for realizing their creative ideas.     

SnS thin-films by RF sputtering at room temperature

Tin monosulfide (SnS) is of interest as a potential solar cell absorber material. We present a preliminary investigation of the effects of sputtering conditions on SnS thin-film structural, optical, and electronic properties. Films were RF sputtered from an SnS target using an argon plasma. Resistivity, stoichiometry, phase, grain size and shape, bandgap, and optical absorption coefficient can be varied by modifying argon pressure for a fixed deposition time. Most films have an indirect bandgap in the range of 1.08-1.18 eV. XRD patterns confirmed the films as mostly crystalline, and grain morphology was examined using profile and surface SEM images.     

Implementation of service systems on the shop-floor level in financial service companies. Empirical evidence from Australia and Germany

This article presents the practices of Australian and German financial service providers regarding the implementation of shop-floor control within different types of service systems. The results delivered in this article should serve as a guideline for future research to develop and adapt methods for shop-floor control in financial service systems. Interviews with 25 experts from the Australian and German financial services industry reveal novel insights into the practice of shop-floor control, suggesting that methods and concepts from manufacturing are only used to a limited extent for shop-floor control. Shop-floor control is mostly used to react quickly to unexpected deviations due to a low usage of forecasts and information systems. Thus, there seems to be improvement potential in the financial services industry in comparison with in the manufacturing industry in terms of shop-floor control. Further research within the production research area should use the empirical insights to test and adapt existing methods and to develop new ones, taking cultural differences into account.     

SnapPaste: an interactive technique for easy mesh composition

Editing and manipulation of existing 3D geometric objects are a means to extend their repertoire and promote their availability. Traditionally, tools to compose or manipulate objects defined by 3D meshes are in the realm of artists and experts. In this paper, we introduce a simple and effective user interface for easy composition of 3D mesh-parts for non-professionals. Our technique borrows from the cut-and-paste paradigm where a user can cut parts out of existing objects and paste them onto others to create new designs. To assist the user attach objects to each other in a quick and simple manner, many applications in computer graphics support the notion of “snapping”. Similarly, our tool allows the user to loosely drag one mesh part onto another with an overlap, and lets the system snap them together in a graceful manner. Snapping is accomplished using our Soft-ICP algorithm which replaces the global transformation in the ICP algorithm with a set of point-wise locally supported transformations. The technique enhances registration with a set of rigid to elastic transformations that account for simultaneous global positioning and local blending of the objects. For completeness of our framework, we present an additional simple mesh-cutting tool, adapting the graph-cut algorithm to meshes.     

Comparison of thin epitaxial film silicon photovoltaics fabricated on monocrystalline and polycrystalline seed layers on glass

We fabricate thin epitaxial crystal silicon solar cells on display glass and fused silica substrates overcoated with a silicon seed layer. To confirm the quality of hot‐wire chemical vapor deposition epitaxy, we grow a 2‐µm‐thick absorber on a (100) monocrystalline Si layer transfer seed on display glass and achieve 6.5% efficiency with an open circuit voltage (V_OC) of 586 mV without light‐trapping features. This device enables the evaluation of seed layers on display glass. Using polycrystalline seeds formed from amorphous silicon by laser‐induced mixed phase solidification (MPS) and electron beam crystallization, we demonstrate 2.9%, 476 mV (MPS) and 4.1%, 551 mV (electron beam crystallization) solar cells. Grain boundaries likely limit the solar cell grown on the MPS seed layer, and we establish an upper bound for the grain boundary recombination velocity (S_GB) of 1.6x10⁴ cm/s. Copyright © 2014 John Wiley & Sons, Ltd.     

The estimation of corrosion behaviour of ZrTi binary alloys for dental applications using electrochemical techniques

Titanium and zirconium are in the same group in the periodic table of elements and are known to have similar physical and chemical properties. Both Ti and Zr usually have their surfaces covered by a thin oxide film spontaneously formed in air. However, the cytotoxicity of ZrO₂ is lower than that of TiO₂ rutile. Treatments with fluoride are known as the main methods to prevent plaque formation and dental caries. The corrosion behaviour of ZrTi alloys with Ti contents of 5, 25 and 45 wt.% and cp-Ti was investigated for dental applications. All samples were tested by linear potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) performed in artificial saliva with different pH levels (5.6 and 3.4) and different fluoride (1000 ppm F⁻) and albumin protein (0.6%) contents. In addition, scanning electron microscopy (SEM) was employed to observe the surface morphology of the test materials after linear potentiodynamic polarisation. The corrosion current densities for the ZrTi alloys increased with the titanium content. The Zr5Ti and Zr25Ti alloys were susceptible to localised corrosion. The role that Ti plays as an alloying element is that of increasing the resistance of ZrTi alloy to localised corrosion. The presence of 0.6% albumin protein in fluoridated acidified artificial saliva with 1000 ppm F⁻ could protect the cp-Ti and ZrTi alloys from attack by fluoride ions.     

Mechanical Properties of Conjugated Polymers and Polymer‐Fullerene Composites as a Function of Molecular Structure

Despite the importance of mechanical compliance in most applications of semiconducting polymers, the effects of structural parameters of these materials on their mechanical properties are typically not emphasized. This paper examines the effect of length of the pendant group on the tensile modulus and brittleness for a series of regioregular poly(3‐alkylthiophenes) (P3ATs) and their blends with a soluble fullerene derivative, PCBM. The tensile modulus decreases with increasing length of the alkyl side‐chain, from 1.87 GPa for butyl side chains to 0.16 GPa for dodecyl chains. The moduli of P3AT:PCBM blends films are greater than those of the pure polymers by factors of 2–4. A theoretical model produces a trend in the effect of alkyl side chain on tensile modulus that follows closely to the experimental measurements. Tensile modulus correlates with brittleness, as the strain at which cracks appear is 6% for P3BT and >60% for P3OT. Adhesion of the P3AT film to a polydimethylsiloxane (PDMS) substrate is believed to play a role in an apparent increase in brittleness from P3OT to P3DDT. The additive 1,8‐Diiodooctane (DIO) reduces the modulus of P3HT:PCBM blend by a factor of 3. These results could enable mechanically robust, flexible, and stretchable electronics.     

2‐(1‐Ethynylpyrene)‐Adenosine as a Folding Probe for RNA—Pyrene in or out

A series of short RNA duplexes containing one or two 1‐ethynylpyrene‐modified adenine bases was synthesised. The melting behaviour of these duplexes was examined by monitoring temperature‐dependent pyrene fluorescence. In the singly modified RNA duplexes, the bases flanking the ethynylpyrene‐rA were varied to examine the sequence specificity of the fluorescence change of pyrene upon RNA hybridisation. Because an increase in pyrene fluorescence upon melting of the duplex can be correlated with intercalation of pyrene, and a decrease is usually associated with the position of pyrene outside the strand, a relationship between the flanking bases and the tendency of the dye to intercalate has been established. It was found that pyrene intercalation is less likely to take place if the modified base is flanked only by A–U base pairs. Flanking G–C base pairs, even only in the 5′‐direction of the modified base, will favour intercalation. In addition, we examined a doubly modified compound that had a pyrene located on each strand. The spectra indicated that the two pyrenes were close enough for interaction. Upon melting of the strand, a fluorescence blue shift corresponding to the dissociation of the pyrene–pyrene complex could be observed in addition to the intensity effect already known from the singly modified compounds. Two melting curves based on the different properties of the fluorophore could be extracted, leading to different melting points corresponding to the global duplex melting and to the change of local pyrene environment, respectively.