Investigating the suitability of electrohydrodynamic lithography for the fabrication of cell substrates

We have investigated the feasibility of using electrohydrodynamic lithography (EHDL) to produce large lateral areas of patterned polymer substrates for use in biomedical applications. Half centimetered squared regions of uninterrupted patterning were obtained and characterised by profilometry and microscopy. The patterning was found to be elliptical in shape and was composed of concentric bands of distinct patterns centred on initial, randomly located nucleation sites. The size of the patterned area was limited by the degree to which the inter-electrode gap could be kept perfectly parallel, with a difference in height of just 15 nm influencing the patterning. Such sensitivity meant that issues such as the stiffness of the electrodes were important. Hierarchical patterning was achieved by combining EHDL with fracture-induced structuring. The substrates fabricated using EHDL were demonstrated to be viable for cell culture in vitro using fibroblast (3T3) and muscle (C2C12) cell lines.     

CALL FOR PAPERS: Special Issue of Subsurface Sensing Technologies and Applications: An International Journal (SSTA Journal) on Sensor Technologies for Civil and Mechanical Systems

Call for Papers

CALL FOR PAPERS: Special Issue of Subsurface Sensing Technologies and Applications: An International Journal (SSTA Journal) on Sensor Technologies for Civil and Mechanical Systems     

Modernism sustained: Bucharest in the 1930s and 1990s

During the 1930s the social life of Bucharest rivalled that elsewhere in Europe. Culturally and artistically Bucharest embraced dynamic, innovative and avant-garde attitudes, which were prompted by the establishment of a Greater Romania after the end of the first World War. The artists Brancusi, Janco, Mary, the composer Enescu, the philosopher Eliade, were recognised internationally. The development of Bucharest was based on progressive theoretical ideas and over a period of ten years its appearance was transformed by modernist buildings. The individual villas and apartment buildings which formed the bulk of this transformation were achieved by private enterprise and represented an innovative architecture of social equilibrium which was entirely modernist; quite unlike the modernist social housing programmes elsewhere in Europe which were the products of state intervention and industry. By contrast, state and civic building programmes in Bucharest realised an architecture which retained classical conventions to become austere, sombre and repetitive. Since 1989, Romania has had to adjust to the rigours of market economics. The intervening fifty years of totalitarianism kept the achievements of the inter-war years under wraps, but these are now being rediscovered by a generation for whom they are the nearest representation of democracy on Romanian territory. The new-found democracy of the market place brings this period of cultural achievement into sharp focus, in the hope that it may act as a catalyst for the resolution of today's extensive urban deprivations.     

Drinking locations of drink-drivers: A comparative analysis of accident and nonaccident cases

This study utilizes data collected by the Perth (Australia) Traffic Police on the last drinking location of persons arrested for drink-driving either as a consequence of their being involved in a road traffic accident or as a result of failing a roadside breath test. A comparison of these data has found that significantly more persons involved in traffic accidents had been drinking at unlicensed locations, that is at private residences or in public places such as parks, than at licensed premises. It was also found that accident cases were more likely to involve males under 25 years; for those involved to have, on average, significantly higher blood alcohol levels than was the case for nonaccident drink-driving cases; and for most accidents to occur late at night and early morning. The significance of these findings were confirmed by logistic regression. A surprise incidental finding was that considerably more women had been arrested for drinkdriving than had been previously reported in other studies, both in Australia and overseas.     

Investigation of Refractory Black Carbon-Containing Particle Morphologies Using the Single-Particle Soot Photometer (SP2)

An important source of uncertainty in radiative forcing by absorbing aerosol particles is the uncertainty in their morphologies (i.e., the location of the absorbing substance on/in the particles). To examine the effects of particle morphology on the response of an individual black carbon-containing particle in a Single-Particle Soot Photometer (SP2), a series of experiments was conducted to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate), and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermochemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources.

Copyright 2015 American Association for Aerosol Research     

The FLAME approach: From dense linear algebra algorithms to high-performance multi-accelerator implementations

Parallel accelerators are playing an increasingly important role in scientific computing. However, it is perceived that their weakness nowadays is their reduced “programmability” in comparison with traditional general-purpose CPUs. For the domain of dense linear algebra, we demonstrate that this is not necessarily the case. We show how the libflame library carefully layers routines and abstracts details related to storage and computation, so that extending it to take advantage of multiple accelerators is achievable without introducing platform specific complexity into the library code base. We focus on the experience of the library developer as he develops a library routine for a new operation, reduction of a generalized Hermitian positive definite eigenvalue problem to a standard Hermitian form, and configures the library to target a multi-GPU platform. It becomes obvious that the library developer does not need to know about the parallelization or the details of the multi-accelerator platform. Excellent performance on a system with four NVIDIA Tesla C2050 GPUs is reported. This makes libflame the first library to be released that incorporates multi-GPU functionality for dense matrix computations, setting a new standard for performance.     

A new basis for assessing the sustainability of natural resources

Natural resources are generally referred to as “depleteable” and “renewable.” The term “renewable” typically refers to “biological” resources, such as fish and forests. Other renewable resources, including hydro, solar, tidal, wave and wind power are not explicitly addressed by existing economic theories. Identification of the physical and economic characteristics of natural resources enables the real cost of natural resource use to be identified, providing the basis of a single unifying theory of all resources based on a user cost function. Two key considerations emerge: firstly, in relation to resource depletion, it is necessary to explore the role of rate of consumption relative to rate of supply as a quantitative aspect of resources; secondly, in relation to pollution, it is necessary to investigate the role of rate of change of entropy as a resource is utilised as a qualitative aspect of resources. Once the true costs of resource use have been established, natural resources can be classified in a systematic way. Clear differences between different types of natural resources emerge, leading to new terms being proposed to describe different resource types.     

Optimization of Blended-Elemental Powder-Based Titanium Alloy Extrusions for Aerospace Applications

The process of canless extrusion in ambient environment, using cold isostatic pressed, and vacuum-sintered, direct-consolidated blended-elemental hydrided ADMA titanium powder, mixed with master alloy powder for the Ti-6Al-4V composition, has been successfully demonstrated. However, these initially processed unoptimized powder-based extrusions also exhibited oxygen content of about 3000 ppm, within the ASTM B817 Standard, but exceeding the AMS Specification 4935 maximum limit of 2000 ppm, and with pre-extrusion residual hydrogen within 300–500 ppm resulting in post-extrusion void nucleation aligned with the extrusion direction. Additional optimization of extrusion billets during the CIP-and-sintering steps has been successfully demonstrated reducing both oxygen and hydrogen contents to levels at or below the AMS Specification limits for Ti-6Al-4V composition (oxygen content of 2000 ppm maximum, and hydrogen content of 125 ppm maximum). Processing-microstructure-property correlations of the optimized, AMS-4935-Specification-conformant, Ti-6Al-4V blended-elemental powder-based product form exhibited an overall mechanical property balance matching that of double-arc-remelted ingot-based extrusions. Property matching was not only in terms of static mechanical properties (room-temperature tensile properties, and monotonic fracture toughness K _IC (K _Q) values), but also in terms of dynamic fatigue properties (combined S/N plus da/dN properties), as well as stress-corrosion resistance, as measured in terms of K _ISCC threshold values.