The local electric field distribution and the effect of surface-enhanced Raman spectroscopy (SERS) were investigated on the quasi-3D (Q3D) plasmonic nanostructures formed by gold nanohole and nanodisc array layers physically separated by a dielectric medium. The local electric fields at the top gold nanoholes and bottom gold nanodiscs as a function of the dielectric medium, substrate, and depth of Q3D plasmonic nanostructures upon the irradiation of a 785 nm laser were calculated using the three-dimensional finite-difference time-domain (3D-FDTD) method. The intensity of the maximum local electric fields was shown to oscillate with the depth and the stronger local electric fields occurring at the top or bottom gold layer strongly depend on the dielectric medium, substrate, and depth of the nanostructure. This phenomenon was determined to be related to the Fabry-Pérot interference effect and the interaction of localized surface plasmons (LSPs). The enhancement factors (EFs) of SERS obtained from the 3D-FDTD simulations were compared to those calculated from the SERS experiments conducted on the Q3D plasmonic nanostructures fabricated on silicon and ITO coated glass substrates with different depths. The same trend was obtained from both methods. The capabilities of tuning not only the intensity but also the location of the maximum local electric fields by varying the depth, dielectric medium, and substrate make Q3D plasmonic nanostructures well suited for highly sensitive and reproducible SERS detection and analysis.

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Objective Blunt cerebrovascular injuries (BCVI) of the neck are a common cause for concern after blunt trauma. The purpose of this article is to demonstrate whether patients with a cervical seat belt sign in the absence of associated high-risk injuries or neurological symptoms are at an increased risk for developing a clinically significant vascular injury and therefore require a screening neck computed tomographic angiography (CTA). Methods A retrospective review was performed of patients who presented after motor vehicle collision and received a neck CTA for an indication of “seat belt sign.” Imaging was reviewed to determine the vascular injury grade, associated injuries, and, if available, follow-up imaging was reviewed to assess for interval change or resolution. The patients were split into 2 groups. Group 1 included patients without high-risk injuries, and group 2 included patients with high-risk injuries. Results In group 1, 6 (2.9%) of 208 patients had BCVI. In group 2, 7 (18.9%) of 37 patients had BCVI. Patients in group 2 were 6.5 times more likely to suffer BCVI compared with group 1 (P < 0.001). No patient in group 1 was ever symptomatic, and only 1 (0.5%) patient underwent interventional treatment. Conclusions Patients presenting after blunt trauma with a seat belt sign and no other high-risk injuries as laid out by screening criteria demonstrate a low probability of BCVI and an even lower likelihood of adverse outcome.