A slip-based model for the size-dependent effective thermal conductivity of nanowires

The heat flux across a nanowire is computed based on the Guyer-Krumhansl equation. Slip conditions with a slip length depending on both temperature and nanowire radius are introduced at the outer boundary. An explicit expression for the effective thermal conductivity is derived and compared to existing models across a given temperature range, providing excellent agreement with experimental data for Si nanowires

Effective thermal conductivity of rectangular nanowires based on phonon hydrodynamics

A mathematical model is presented for thermal transport in nanowires with rectangular cross sections. Expressions for the effective thermal conductivity of the nanowire across a range of temperatures and cross-sectional aspect ratios are obtained by solving the Guyer–Krumhansl hydrodynamic equation for the thermal flux with a slip boundary condition. Our results show that square nanowires transport thermal energy more efficiently than rectangular nanowires due to optimal separation between the boundaries. However, circular nanowires are found to be even more efficient than square nanowires due to the lack of corners in the cross section, which locally reduce the thermal flux and inhibit the conduction of heat. By using a temperature-dependent slip coefficient, we show that the model is able to accurately capture experimental data of the effective thermal conductivity obtained from Si nanowires, demonstrating that phonon hydrodynamics is a powerful framework that can be applied to nanosystems even at room temperature. © 2018 Elsevier Lt

A slip-based model for the size-dependent effective thermal conductivity of nanowires

The heat flux across a nanowire is computed based on the Guyer-Krumhansl equation. Slip conditions with a slip length depending on both temperature and nanowire radius are introduced at the outer boundary. An explicit expression for the effective thermal conductivity is derived and compared to existing models across a given temperature range, providing excellent agreement with experimental data for Si nanowires

VIPER-2: a prospective, randomized single-center comparison of 2 different closure devices with a hemostatic wound dressing for closure of femoral artery access sites

PURPOSE: To report the outcome of a prospective randomized safety and performance trial of 2 access site closure devices versus a wound dressing. METHODS: Between October 2005 and July 2006, 852 consecutive patients (605 men; mean age 67 years) undergoing diagnostic or interventional catheterization procedures thru a 5- or 6-F femoral sheath were randomized to one of the 3 closure methods: a collagen plug device (Angio-Seal), a clip (StarClose), or a wound dressing (D-Stat Dry). The efficacy of the devices was assessed, as well as the complications occurring at the puncture site during the hospital stay. The primary endpoint of the study was the cumulative incidence of access site pseudoaneurysm, major access site bleeding requiring transfusion, access site vascular surgery, or death from all causes. RESULTS: There were no significant differences in baseline characteristics between the 3 treatment groups. The primary endpoint was reached in 20 (7.1%) of 281 patients treated with D-Stat Dry and in 11 (1.9%) of 571 patients treated with the mechanical closure devices (p>0.0001). There was no significant difference among the mechanical closure devices concerning the incidence of the primary endpoint (Angio-Seal 1.1% versus StarClose 2.8%; p = 0.13). CONCLUSION: The collagen plug device had the lowest rates of major and minor access site-related complications after removal of 5- or 6-F femoral sheaths. The difference between the mechanical closure devices concerning the incidence of the primary endpoint did not reach statistical significance. The wound dressing showed significantly higher major and minor complication rates

Advances in vascular medicine

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