Thermally conductive polyamide 6/carbon filler composites based on a hybrid filler system

We explored the use of a hybrid filler consisting of graphite nanoplatelets (GNPs) and single walled carbon nanotubes (SWCNTs) in a polyamide 6 (PA 6) matrix. The composites containing PA 6, powdered GNP, and SWCNT were melt-processed and the effect of filler content in the single filler and hybrid filler systems on the thermal conductivity of the composites was examined. The thermal diffusivities of the composites were measured by the standard laser flash method. Composites containing the hybrid filler system showed enhanced thermal conductivity with values as high as 8.8 W (m · K)^-1, which is a 35-fold increase compared to the thermal conductivity of pure PA 6. Thermographic images of heat conduction and heat release behaviors were consistent with the thermal conductivity results, and showed rapid temperature jumps and drops, respectively, for the composites. A composite model based on the Lewis-Nielsen theory was developed to treat GNP and SWCNT as two separate types of fillers. Two approaches, the additive and multiplicative approaches, give rather good quantitative agreement between the predicted values of thermal conductivity and those measured experimentally.

The anterior chamber angle is different in different racial groups: a gonioscopic study

The purpose of the study was to determine racial and sexual differences and age-related changes in the anterior chamber angle to evaluate the reliability of a standardised gonioscopic grading system. The anterior chamber angle was studied prospectively in 291 patients who included Afro-Americans, Caucasians and Far East Asians. No statistically significant difference was found between the angle width of these three groups, but the iris joins the scleral wall more anteriorly in Asians, slightly more posteriorly in Afro-Americans, and most posteriorly in Caucasians (p = 0.03). The anterior chamber tends to be narrower in females (p = 0.002) and to become narrower with increasing age (p < 0.0001) in all ethnic groups. Refractive error significantly affects both the level of iris insertion (p < 0.003) and the angle width (p < 0.001). The consistency of the angle grading system in this project is demonstrated by a close agreement between the examiners. It is concluded that the difference in the angle configuration may account for racial differences in the incidence of angle-closure glaucoma, this being least common in Caucasians, more common in Afro-Americans and most common in Asians.