Search

Grid computing has the potential to revolutionise how small groups of simulation scientists work together to tackle new science problems. In this paper we report how the eMinerals project has developed a small scale integrated compute and data grid infrastructure - the eMinerals minigrid - and developed generic job submission tools that exploit this infrastructure and which enable the science users to also access other grid systems.

A sensor device based on a single polymer cantilever and optical readout has been developed for detection of molecular recognition reactions without the need of a reference cantilever for subtraction of unspecific signals. Microcantilevers have been fabricated in the photoresist SU-8 with one surface passivated with a thin fluorocarbon layer. The SU-8 surface is sensitized with biological receptors by applying silanization methods, whereas the fluorocarbon surface remains inert to these processes. The thermal and mechanical properties of the chosen materials allow overcoming the main limitations of gold-coated silicon cantilevers: the temperature, pH, and ionic strength cross sensitivities. This is demonstrated by comparing the response of SU-8 cantilevers and that of gold-coated silicon nitride cantilevers to variations in temperature and pH. The sensitivity of the developed polymeric nanomechanical sensor is demonstrated by real-time detection of the human growth hormone with sensitivity in differential surface stress of about 1 mN/m. (c) 2006 American Institute of Physics.

We present an SU-8 micrometer sized cantilever strain sensor with an integrated piezoresistor made of a conductive composite of SU-8 polymer and carbon black particles. The composite has been developed using ultrasonic mixing. Cleanroom processing of the polymer composite has been investigated and it has been shown that it is possible to pattern the composite by standard UV photolithography. The composite material has been integrated into an SU-8 microcantilever and the polymer composite has been demonstrated to be piezoresistive with gauge factors around 15-20. Since SU-8 is much softer than silicon and the gauge factor of the composite material is relatively high, this polymer based strain sensor is more sensitive than a similar silicon based cantilever sensor. (c) 2006 American Institute of Physics.

Planktonic and benthic incubations (bare and Posidonia oceanica vegetated sediments) were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the Bay of Palma (Mallorca, Spain). Results showed a contrast between the planktonic compartment, which was on average near metabolic balance (-4.6 +/- 5.9 mmol O-2 m(-2) d(-1)) and the benthic compartment, which was autotrophic (17.6 +/- 8.5 mmol O-2 m(-2) d(-1)). During two cruises in March and June 2002, planktonic and benthic incubations were performed at several stations in the bay to estimate the whole-system metabolism and to examine its relationship with partial pressure of CO2 (pCO(2)) and apparent oxygen utilisation (AOU) spatial patterns. Moreover, during the second cruise, when the residence time of water was long enough, net ecosystem production (NEP) estimates based on incubations were compared, over the Posidonia oceanica meadow, to rates derived from dissolved inorganic carbon (DIC) and oxygen (O-2) mass balance budgets. These budgets provided NEP estimates in fair agreement with those derived from direct metabolic estimates based on incubated samples over the Posidonia oceanica meadow. Whereas the seagrass community was autotrophic, the excess organic carbon production therein could only balance the planktonic heterotrophy in shallow waters relative to the maximum depth of the bay ( 55 m). This generated a horizontal gradient from autotrophic or balanced communities in the shallow seagrass-covered areas, to strongly heterotrophic communities in deeper areas of the bay. It seems therefore that, on an annual scale in the whole bay, the organic matter production by the Posidonia oceanica may not be sufficient to fully compensate the heterotrophy of the planktonic compartment, which may require external organic carbon inputs, most likely from land.

Planktonic and benthic incubations (bare and Posidonia oceanica vegetated sediments) were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the Bay of Palma (Mallorca, Spain). Results showed a contrast between the planktonic compartment, which was on average near metabolic balance (-4.6 +/- 5.9 mmol O-2 m(-2) d(-1)) and the benthic compartment, which was autotrophic (17.6 +/- 8.5 mmol O-2 m(-2) d(-1)). During two cruises in March and June 2002, planktonic and benthic incubations were performed at several stations in the bay to estimate the whole-system metabolism and to examine its relationship with partial pressure of CO2 (pCO(2)) and apparent oxygen utilisation (AOU) spatial patterns. Moreover, during the second cruise, when the residence time of water was long enough, net ecosystem production (NEP) estimates based on incubations were compared, over the Posidonia oceanica meadow, to rates derived from dissolved inorganic carbon ! (DIC) and oxygen (O-2) mass balance budgets. These budgets provided NEP estimates in fair agreement with those derived from direct metabolic estimates based on incubated samples over the Posidonia oceanica meadow. Whereas the seagrass community was autotrophic, the excess organic carbon production therein could only balance the planktonic heterotrophy in shallow waters relative to the maximum depth of the bay ( 55 m). This generated a horizontal gradient from autotrophic or balanced communities in the shallow seagrass-covered areas, to strongly heterotrophic communities in deeper areas of the bay. It seems therefore that, on an annual scale in the whole bay, the organic matter production by the Posidonia oceanica may not be sufficient to fully compensate the heterotrophy of the planktonic compartment, which may require external organic carbon inputs, most likely from land, Planktonic and benthic incubations (bare and Posidonia oceanica vegetated sediments) were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the Bay of Palma (Mallorca, Spain). Results showed a contrast between the planktonic compartment, which was on average near metabolic balance (-4.6 +/- 5.9 mmol O-2 m(-2) d(-1)) and the benthic compartment, which was autotrophic (17.6 +/- 8.5 mmol O-2 m(-2) d(-1)). During two cruises in March and June 2002, planktonic and benthic incubations were performed at several stations in the bay to estimate the whole-system metabolism and to examine its relationship with partial pressure of CO2 (pCO(2)) and apparent oxygen utilisation (AOU) spatial patterns. Moreover, during the second cruise, when the residence time of water was long enough, net ecosystem production (NEP) estimates based on incubations were compared, over the Posidonia oceanica meadow, to rates derived from dissolved inorganic carbon ! (DIC) and oxygen (O-2) mass balance budgets. These budgets provided NEP estimates in fair agreement with those derived from direct metabolic estimates based on incubated samples over the Posidonia oceanica meadow. Whereas the seagrass community was autotrophic, the excess organic carbon production therein could only balance the planktonic heterotrophy in shallow waters relative to the maximum depth of the bay ( 55 m). This generated a horizontal gradient from autotrophic or balanced communities in the shallow seagrass-covered areas, to strongly heterotrophic communities in deeper areas of the bay. It seems therefore that, on an annual scale in the whole bay, the organic matter production by the Posidonia oceanica may not be sufficient to fully compensate the heterotrophy of the planktonic compartment, which may require external organic carbon inputs, most likely from land

We present the results of simulations, using density functional theory (DFT) with generalized gradient corrections (GGA), on the troilite (FeS), pyrrhotite (Fe12xS) and MnP phases of FeS. The values obtained for the cell parameters and c/a ratio of troilite accurate to within 1% of those determined by experiment, a significant improvement on previous simulations. Energy volume curves for FeS in the troilite and MnP structures indicate a pressure-induced transition at 4 GPa (experimentally observed at 3.4 GPa). Comparison of spin-polarised and non-spin-polarised simulations of the troilite structure demonstrate the significance of magnetostructural effects in determining the c/a ratio and shed light on the magnetic and volume collapse of FeS on its transition from the MnP to a monoclinic structure at 6.7 GPa. Simulations of different (001) surface terminations of troilite indicate that stable surfaces are characterised by triangles of iron atoms "capped" with a sulphur atom.

A polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes has been designed and realized. Multi-walled carbon nanotubes from aqueous solution have been assembled between two metal electrodes that are separated by 2 mu m and embedded in the polymer cantilever. The entire chip, except for the metallic electrodes and wiring, was fabricated in the photoresist SU-8. SU-8 allows for an inexpensive, flexible and fast fabrication method, and the cantilever platform provides a hydrophobic surface that should be well suited for nanotube assembly. The device can be integrated in a micro-total analysis system and has the potential to be used as a scanning sensor for biochemical applications.

We report the fabrication of arrays of polymeric cantilevers for biochemistry applications. The cantilevers are fabricated in the polymer SU-8. The use of a polymer as the component material for the cantilevers provides the sensors with very high sensitivity due to convenient mechanical material properties. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. The method allows obtaining well-controlled and uniform mechanical properties of the cantilevers. The elastic constant of the cantilevers was measured, and their dynamic response was studied. Characterization of the devices shows that they are suitable for both static and dynamic measurements for biochemical detection in either air or liquid environments. The sensor was applied to monitoring of the immobilization process of cystamine on a gold-coated SU-8 cantilever.