To develop a 3D multi-contrast IVW protocol with 0.5-mm isotropic resolution and a scan time of 5 min per sequence.
Materials and methods
Pre-contrast T1w VISTA, DANTE prepared PDw VISTA, SNAP, and post-contrast T1w VISTA were accelerated using cartesian undersampling with target ordering method (CUSTOM) and self-supporting tailored k-space estimation for parallel imaging reconstruction (STEP). CUSTOM + STEP IVW was compared to full-sample IVW, SENSE-accelerated IVW, and CUSTOM + zero-filled Fourier reconstruction in normal volunteers and subjects with intracranial atherosclerotic disease (ICAD). Image quality, vessel delineation, CSF suppression, and blood suppression were compared.
Results
CUSTOM + STEP vessel wall delineation was comparable to full-sample IVW and better than SENSE IVW for vessel wall delineation on T1w VISTA and luminal contrast on SNAP. Average image quality and wall depiction were significantly improved using STEP reconstruction compared with zero-filled Fourier reconstruction, with no significant difference in CSF or blood suppression.
Conclusions
CUSTOM + STEP allowed multi-contrast 3D 0.5-mm isotropic IVW within 30 min. Although some quantitative and qualitative scores for CUSTOM − STEP were lower than fully sampled IVW, CUSTOM + STEP provided comparable vessel wall delineation as full-sample IVW and was superior to SENSE. CUSTOM + STEP IVW was well tolerated by patients and showed good delineation of ICAD plaque.
Multilayer solar selective absorber coatings have been developed in the last few decades. The thermal stability in terms of microstructure gives an insightful understanding of the optical properties of such coatings. In this context, we extensively utilized transmission electron microscopy (TEM) analysis to establish the thermal stability of TiB2/Ti(B,N)/SiON/SiO2 coating, under thermal cycling/continuous heating to 500°C in vacuum for 250 h. In particular, this work reports the variation in the solar absorptance of TiB2/Ti(B,N)/SiON/SiO2 coating with different angles of incidence of the solar radiation. Extensive analysis using the TEM technique reveals the presence of oxide interlayers that act as diffusion barrier layers to enhance the thermal stability of the coating. Computational simulation using SCOUT software validates the measured reflectance spectrum of the developed multilayer coating. The minor changes in absorptance and emissivity after heat treatment in vacuum at 500°C, together with high solar absorptance over a broad angular variation, establish the potential application of TiB2/Ti(B,N)/SiON/SiO2 as a selective coating in concentrated solar power systems. 相似文献
The International Journal of Advanced Manufacturing Technology - Magnetorheological (MR) finishing is a smart finishing processes applied to a variety of applications. In the present work, an... 相似文献
Gas sensing characteristics of SnO2 thin films prepared by RF sputtering have been investigated and compared to that of RGTO (Rheotaxially Grown and Thermally Oxidized) films. Both the sensor films exhibited a highly selective response towards H2S with RF sputtered film showing better response characteristics. RF sputtered and RGTO films exhibited a maximum response of 54 and 15 towards 10 ppm of H2S at an optimum operating temperature of 150 and 250 °C, respectively. Sputtered films exhibited a linear response in the wide concentration range from 500 ppb to 500 ppm while RGTO films were found to saturate for concentrations above 100 ppm. XPS investigations revealed that the RGTO films are more sub–stoichiometric or oxygen deficient than the sputtered films. Raman studies further indicates that the surface of sputtered and RGTO films are characterized by the presence of oxygen deficiency attributed to the “bridging-type” and deeper “in-plane/sub-bridging” oxygen vacancies, respectively. The improved response kinetics of the RF sputtered films is attributed to the presence of bridging type oxygen vacancies that facilitates the charge transfer between the sensor surface and H2S molecules. 相似文献