Rhodium nanoparticles from cluster seeds: control of size and shape by precursor addition rate

The size-tunable synthesis of poly(vinylpyrrolidone)-stabilized cuboctahedral rhodium nanoparticles with mean diameters ranging between 3-7 nm and multipod structures was accomplished using seeded growth methods. Isotropic PVP-capped 2.9 nm seeds were prepared by ligand exchange on rhodium-triphenylphosphine metal-organic clusters. Quantitative investigation of reaction parameters in ethylene glycol revealed that size and shape could be controlled at a single reaction temperature of 120 degrees C. The rate of rhodium monomer addition was found to be critical for monodispersity and shape control, regardless of thermodynamic factors. Solvent viscosity, varied by changing the polyol solvents, indicated that autocatalytic addition kinetics are responsible for isotropic versus anisotropic growth.     

Comparison of SIR-B SAR wave image spectra with wave modelpredictions: implications on the SAR modulation transfer function

During the Spaceborne Imaging Radar (SIR-B) mission in October 1984, the onboard synthetic aperture radar (SAR) acquired data in the vicinity of Hurricane Josephine. Ocean wave spectra computed from the SAR imagery are compared with Ocean Data Gathering Project (ODGP) model forecasts. Because the apparent propagation direction of the dominant wave system rotated over 90° along the pass, the data set affords a unique opportunity to observe the same wave system as imaged by different SAR mechanisms. It is shown that, for the SIR-B geometry, the wave numbers and propagation directions extracted from the wave spectra are not strongly dependent on the exact nature of the SAR imaging mechanism. However,the estimation of ocean significant wave height (SWH) requires accurate knowledge of such mechanisms. The spatial variation of SWH as estimated from SAR-derived wave spectra and ODGP model spectra compare most favorably when the phase of the hydrodynamic portion of the SAR modulation transfer function is approximately 90° past the long wave crest     

A technique for preparing holey carbon films for high resolution electron microscopy

A simple and reproducible method of preparing holey carbon nets for use as support films for high resolution electron microscopy is described.     

Low-cost struvite production using source-separated urine in Nepal

This research investigated the possibility of transferring phosphorus from human urine into a concentrated form that can be used as fertilizer in agriculture. The community of Siddhipur in Nepal was chosen as a research site, because there is a strong presence and acceptance of the urine-diverting dry toilets needed to collect urine separately at the source. Furthermore, because the mainly agricultural country is landlocked and depends on expensive, imported fertilizers, the need for nutrient security is high. We found that struvite (MgNH₄PO₄·6H₂O) precipitation from urine is an efficient and simple approach to produce a granulated phosphorus fertilizer. Bittern, a waste stream from salt production, is a practical magnesium source for struvite production, but it has to be imported from India. Calculations show that magnesium oxide produced from locally available magnesite would be a cheaper magnesium source. A reactor with an external filtration system was capable of removing over 90% of phosphorus with a low magnesium dosage (1.1 mol Mg mol P), with coarse nylon filters (pore width up to 160 ± 50 μm) and with only one hour total treatment time. A second reactor setup based on sedimentation only achieved 50% phosphate removal, even when flocculants were added. Given the current fertilizer prices, high volumes of urine must be processed, if struvite recovery should be financially sustainable. Therefore, it is important to optimize the process. Our calculations showed that collecting the struvite and calcium phosphate precipitated spontaneously due to urea hydrolysis could increase the overall phosphate recovery by at least 40%. The magnesium dosage can be optimized by estimating the phosphate concentration by measuring electrical conductivity. An important source of additional revenue could be the effluent of the struvite reactor. Further research should be aimed at finding methods and technologies to recover the nutrients from the effluent.     

Tenocyte proliferation on collagen scaffolds protects against degradation and improves scaffold properties

Tissue engineering scaffolds encourage cell proliferation whilst degrading to facilitate tissue regeneration. Their mechanical properties therefore change, decreasing due to scaffold degradation and increasing due to extracellular matrix deposition. This work compares the changing properties of collagen scaffolds incubated in culture medium, with and without human tenocytes, in order to investigate the relationship between degradation and tenocyte proliferation. The material properties of scaffolds are compared over 26 days using mechanical testing, differential scanning calorimetry, infra-red spectroscopy, and histology and biochemical assays. For medium-only scaffolds, the mechanical properties decrease rapidly, while culture medium sulfhydryl content increases significantly, with no significant changes in the denaturation temperature of scaffold collagen content. Conversely, the mechanical properties and collagen content of tenocyte-seeded scaffolds increase significantly while culture medium sulfhydryl content decreases and denaturation temperature remains the same. These results indicate that tenocytes proliferation both reduces the degradation of collagen scaffolds incubated in culture medium and produces scaffolds with improved properties.     

The Effects of Warnings, Computer-Based Media, and Probing Activity on Successful Lie Detection

This study on computer-mediated deception features an experiment involving an interactive interview of deceitful applicants for a fictitious scholarship, using one of three different computer-based communication media. Results showed that people were successful at deceiving others no matter what medium was used, but interviewers who used interactive, as opposed to non-interactive, media probed interviewees more during the interviews. Probing led to better lie detection. Also, interviewers who had received simple warnings about the possible presence of deception were better at detecting deception than were interviewers who had received no warnings. However, warnings alone were not sufficient to increase interviewers' probing.     

Development of computer-based techniques for fluid power systems design

The Engineering Design Centre (EDC) in fluid power systems, was established in the School of Mechanical Engineering, University of Bath in 1992 to develop computer-based techniques for fluid power systems design. This paper gives an overview of the research being undertaken at the EDC relating to: system design and performance evaluation using computer simulation; the development of a database for hydraulic components; software tools to minimize noise and vibration; circuit configuration design; and optimization techniques for component selection and sizing.