Separate assessment of porosity and uncombined carbon in cemented carbides

Porosity and uncombined carbon in cemented carbides are traditionally assessed by comparison to standardized microstructure charts, such as those in ISO 4505-1978. To improve the accuracy in the characterization a fully automatic image analysis procedure has been developed. The analysis is performed using light optical microscopy on unetched polished specimens. The implemented algorithm separates uncombined carbon, C-defects, from pores, A- and B-defects. Pores are approximately distributed in a random way in the structure. Uncombined carbon is on the other hand precipitated into clusters of carbon particles. This difference is together with defect size used as a base for the separation. Small defects situated close together are classified as C-defects, small isolated defects as A-pores and large defects as B-pores. Pores are found to be more round than the somewhat elongated C-defects. The difference in shape is significant and can also be used as a separation criterion.

Image analysis is used to quantitatively characterise the ISO 4505-1978 standard charts with respect to volume fraction, number density and size distribution of defects. The results are compared to measured distributions for true microstructures.     

Alternating,all-trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length

The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v_(C?C) = 2108–2128 cm^?1 and v_(C?C) = 1505–1532 cm^?1 were calculated after extrapolation. Similarly sp-C¹³C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.     

Effects of high fat diets on the activity of palmitoyl-CoA hydrolase in rat liver

Palmitoyl-CoA hydrolase [EC 3.1.2.2.] activity in rat liver was found to be enhanced by high fat diets. Partially hydrogenated marine oil and high-erucic acid rapeseed oil diets produced a greater increase than a diet containing soybean oil. With diets containing from 5 to 30% (w/w) of partially hydrogenated marine oil the increase in palmitoyl-CoA hydrolase activity was similar to the increase observed in peroxisomal β-oxidation activity (correlation coefficient r=0.94). A positive correlation (r=0.86) also was observed between the activity of palmitoyl-CoA hydrolase and previously determined levels of long-chain acyl-CoA. The results presented may suggest a common “induction” mechanism for palmitoyl-CoA hydrolase and peroxisomal β-oxidation enzymes, possibly exerted through an increased cellular level of long-chain acyl-CoA.     

Adsorption on activated carbon in countercurrent flow: An experimental study

The work describes adsorption experiments from aqueous solutions on activated carbon using a counter-current adsorber. Phenol and paranitrophenol were used for single component adsorption and molasses colour for multicomponent adsorption experiments. Isotherms were determined using simple equilibrium experiments. Three different techniques were used for determination of the kinetics. These were finite bath, infinite bath and fixed bed experiments. A mathematical model for countercurrent adsorption was tested. The model includes the effect of film diffusion and pore diffusion as well as surface diffusion, and can handle systems with a nonlinear isotherms. Kinetic data in the form of an average diffusivity in the carbon determined from the finite bath experiments and isotherm data did not predict the operation of the countercurrent column well. Data from the fixed bed experiments predicted countercurrent column operation much better. This is deemed to be due to inhomogeneities in the carbon used, resulting in a fairly quick initial uptake of the main part of the solute and a slower uptake of a minor amount.     

Sound synthesis and evaluation of interactive footsteps and environmental sounds rendering for virtual reality applications

We propose a system that affords real-time sound synthesis of footsteps on different materials. The system is based on microphones, which detect real footstep sounds from subjects, from which the ground reaction force (GRF) is estimated. Such GRF is used to control a sound synthesis engine based on physical models. Two experiments were conducted. In the first experiment, the ability of subjects to recognize the surface they were exposed to was assessed. In the second experiment, the sound synthesis engine was enhanced with environmental sounds. Results show that, in some conditions, adding a soundscape significantly improves the recognition of the simulated environment.