Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 6 Articles
In recent years, noninvasive thermal treatment by using high-intensity focused ultrasound (HIFU) has high potential in tumor\ntreatment. The goal of this research is to develop an ultrasound imaging-guided robotic HIFU ablation system for tumor\ntreatment. The system integrates the technologies of ultrasound image-assisted guidance, robotic positioning control, and HIFU\ntreatment planning. With the assistance of ultrasound image guidance technology, the tumor size and location can be\ndetermined from ultrasound images as well as the robotic arm can be controlled to position the HIFU transducer to focus on\nthe target tumor. After the development of the system, several experiments were conducted to measure the positioning accuracy\nof this system. The results show that the average positioning error is 1.01mm with a standard deviation 0.34, and HIFU ablation\naccuracy is 1.32mm with a standard deviation 0.58, which means this system is confirmed with its possibility and accuracy....
Several remote catheter navigation systems have been developed and are now commercially available. However, these systems\ntypically require specialized catheters or equipment, as well as time-consuming operations for the system set-up. In this paper,\nwe present CathROB, a highly compact and versatile robotic system for remote navigation of standard tip-steerable\nelectrophysiology (EP) catheters. Key features of CathROB include an extremely compact design that minimizes encumbrance\nand time for system set-up in a standard cath lab, a force-sensing mechanism, an intuitive command interface, and functions for\nautomatic catheter navigation and repositioning. We report in vitro and in vivo animal evaluation of CathROB. In vitro results\nshowed good accuracy in remote catheter navigation and automatic repositioning (1.5 �± 0.6mm for the left-side targets, 1.7\n�± 0.4mm for the right-side targets). Adequate tissue contact was achieved with remote navigation in vivo. There were no\nadverse events, including absence of cardiac perforation or cardiac damage, indicative of the safety profile of CathROB.\nAlthough further preclinical and clinical studies are required, the presented CathROB system seems to be a promising solution\nfor an affordable and easy-to-use remote catheter navigation....
Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different\nshapes and sizes over large areas. However, the resolution and the aspect ratio of the nanostructures\nfabricated by soft lithography are limited by the depth and the physical properties of the stamp.\nIn this work, silicon nanobelts and nanostructures were achieved by combining soft nanolithography\npatterning with optimized reactive ion etching (RIE) in silicon. Using polymethylmethacrylate (PMMA)\nnanopatterned layers with thicknesses ranging between 14 and 50 nm, we obtained silicon nanobelts\nin areas of square centimeters with aspect ratios up to ~1.6 and linewidths of 225 nm. The soft\nlithographic process was assisted by a thin film of SiOx (less than 15 nm) used as a hard mask and\nRIE. This simple patterning method was also used to fabricate 2D nanostructures (nanopillars) with\naspect ratios of ~2.7 and diameters of ~200 nm. We demonstrate that large areas patterned with\nsilicon nanobelts exhibit a high reflectivity peak in the ultraviolet C (UVC) spectral region (280 nm)\nwhere some aminoacids and peptides have a strong absorption. We also demonstrated how to tailor\nthe aspect ratio and the wettability of these photonic surfaces (contact angles ranging from 8.1 to\n96.2ââ??¦) by changing the RIE power applied during the fabrication process....
The configurational entropy of nanoscale solutions is discussed in this paper. As follows\nfrom the comparison of the exact equation of Boltzmann and its Stirling approximation (widely used\nfor both macroscale and nanoscale solutions today), the latter significantly over-estimates the former\nfor nano-phases and surface regions. On the other hand, the exact Boltzmann equation cannot be\nused for practical calculations, as it requires the calculation of the factorial of the number of atoms\nin a phase, and those factorials are such large numbers that they cannot be handled by commonly\nused computer codes. Herewith, a correction term is introduced in this paper to replace the Stirling\napproximation by the so-called ââ?¬Å?de Moivre approximationââ?¬Â. This new approximation is a continuous\nfunction of the number of atoms/molecules and the composition of the nano-solution. This correction\nbecomes negligible for phases larger than 15 nm in diameter. However, the correction term does\nnot cause mathematical difficulties, even if it is used for macro-phases. Using this correction, future\nnano-thermodynamic calculations will become more precise. Equations are worked out for both\nintegral and partial configurational entropies of multi-component nano-solutions. The equations are\ncorrect only for nano-solutions, which contain at least a single atom of each component (below this\nconcentration, there is no sense to make any calculations)....
Using a seed layer-free hydrothermal method, ZnO nanorods (NRs) were deposited on\nST-cut quartz surface acoustic wave (SAW) devices for ammonia sensing at room temperature. For a\ncomparison, a ZnO film layer with a thickness of 30 nm was also coated onto an ST-cut quartz SAW\ndevice using a sol-gel and spin-coating technique. The ammonia sensing results showed that the\nsensitivity, repeatability and stability of the ZnO NR-coated SAWdevice were superior to those of\nthe ZnO film-coated SAW device due to the large surface-to-volume ratio of the ZnO NRs....
Bamboo-like SiC nanowires (NWs) have specific geometric shapes, which have the potential to suppress thermal conductivity by\nphonon boundary scattering. In this work, phonon transport behaviors in the 3C-SiC, 4H-SiC, and 6H-SiC crystal lattices are\nstudied by the Monte Carlo (MC) method, including impurity scattering, boundary scattering, and Umklapp scattering. Phonon\nrelaxation times for Umklapp (U) scattering for the above three SiC polytypes are calculated from the respective phonon spectra,\nwhich have not been reported in the literature. Diffuse boundary scattering and thermal rectification with different aspect ratios are\nalso studied at different temperatures. It is found that the thermal conductivities of the bamboo-like SiCpolytypes can be lowered by\ntwo orders of magnitude compared with the bulk values by contributions from boundary scattering. Compared with bamboo-like\n4H-SiC and 6H-SiC NWs, 3C-SiC has the largest U scattering relaxation rate and boundary scattering rate, which leads to its lowest\nthermal conductivities. The thermal conductivity in the positive direction is larger than that in the negative direction because of its\nlower boundary scattering relaxation rate....
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