Surface plasmon resonances in periodic and random patterns of gold nano-disks for broadband light harvesting

We analyze the localized surface plasmon resonance spectra of periodic square lattice arrays of gold nano-disks, and we describe numerically and experimentally the effect of disorder on resonance width, spectrum, and EM field enhancement in increasingly randomized patterns. The periodic structure shows a narrower and stronger extinction peak, conversely we observe an increase of up to (1-2) x 10(2) times enhancement as the disorder is gradually introduced. This allows for simpler, lower resolution fabrication, cost-effective in light harvesting for solar cell and sensing applications. We show that dipole-dipole interactions contribute to diffract light parallel to the surface as a mean of long-range coupling between the nano-disks. (C) 2012 Optical Society of Americ

Augmented sensitivity of an IR-absorption gas sensor employing a metal hole array

We demonstrate the use of plasmonic extraordinary transmission at IR wavelengths for surface-enhanced infrared absorption (SEIRA) spectroscopy in gas sensing. Gas detection was performed through non-dispersive infrared (NDIR) absorption. The sensitivity of SF6 gas detection is increased around similar to 27 times with metal hole array (MHA) microstructures placed on the gas cell mirrors, as compared with non-structured mirrors; an absorption change of 2% per 100 ppm was obtained on a standard commercial pyroelectric detector. Down-sizing of IR-sensors to a sub-1 mm gas cell width, delivering similar to 40 nM (or 1 ppm) of SF6 sensitivity, can be foreseen with a simple source-detector setup. (C) 2013 Optical Society of Americ

Black metals : optical absorbers

This research was funded by the Melbourne University administrated DSI-RHD 2018, ARC Discovery DP190103284, Linkage LP190100505 grants, and EPSRC EP/M000869/1.We demonstrate a concept and fabrication of lithography-free layered metal-SiO2 thin-film structures which have reduced reflectivity (black appearance), to as low as 0.9%, with 4.9% broadband reflectance (8.9% for soda lime) in the 500–1400 nm range. The multi-layered (four layers) thin-film metamaterial is designed so that optical impedance matching produces minimal reflectance and transmittance within the visible and infra-red (IR) spectral region for a range of incident angles. The structure has enhanced absorbance and is easily tuned for reduced minimal transmission and reflection. This approach should allow for novel anti-reflection surfaces by impedance matching to be realized.Publisher PDFPeer reviewe

Inhibitory Effects of Antithrombin III on Interactions between Blood Cells and Endothelial Cells during Retinal Ischemia-Reperfusion Injury

PURPOSE. Infiltrating leukocytes have long been widely thought to be key mediators of ischemia-reperfusion injury. Recently, however, evidence suggests that platelets accumulating in postischemic tissues also contribute to ischemia-reperfusion injury because of their inflammatory properties and promotion of formation of thrombi. This study was designed to evaluate quantitatively the inhibitory effects of antithrombin (AT)-III on the interactions between blood cells and retinal endothelial cells in vivo after transient retinal ischemia. METHODS. Transient retinal ischemia was induced for 60 minutes in male Long-Evans rats by ligation of the optic nerve. AT III (250 U/kg) was administered intravenously just after induction of ischemia. Leukocyte and platelet behavior in the retina was evaluated in vivo with a scanning laser ophthalmoscope. Expression of P-selectin and intracellular adhesion molecule (ICAM)-1 in the postischemic retina was investigated by reverse transcription-polymerase chain reaction and immunohistochemistry. After 14 days of reperfusion, ischemia-induced retinal damage was evaluated histologically. RESULTS. Administration of AT III significantly inhibited leukocyte rolling along the major retinal veins and subsequent accumulation of leukocytes in the postischemic retina. Furthermore, the maximum number of rolling and adherent platelets was reduced by 76% (P Ͻ 0.01) and 48% (P Ͻ 0.01), respectively, at 12 hours after reperfusion. Immunohistochemical studies also revealed the suppressive effect of AT III on expression of P-selectin and ICAM-1. Finally, histologic examination demonstrated the protective effects of AT III against retinal damage after transient retinal ischemia. CONCLUSIONS. This study demonstrates the inhibitory effects of AT III on leukocyte and platelet recruitment to the postischemic retina, which may account for the neuroprotective properties of this ␣-2 globulin against retinal ischemia-reperfusion injury. (Invest Ophthalmol Vis Sci. 2003;44:332-341) DOI: 10.1167/iovs.02-0493 I nfiltrating leukocytes have long been acknowledged to be a feature of ischemia-reperfusion injury. 1-4 Recently, however, evidence suggests that platelets also play an important role in the pathogenesis of ischemia-reperfusion injury. 5,6 The importance of platelets is supported by many studies that have demonstrated the beneficial effects of platelet depletion against ischemia-reperfusion injury. 20,21 Thrombin, which is the terminal serine protease of the coagulation cascade, has the ability to activate platelets and fibrinogen. Recently, many investigators have focused on the role of thrombin in various pathologic conditions. It has been demonstrated that an increase in thrombin in postischemic tissues activates vascular endothelial cells. Such activated vascular endothelial cells express adhesion molecules, which contribute to the recruitment of leukocytes and platelets. We recently developed an in vivo method to quantitatively evaluate platelet-endothelium interactions in rat retina. 26 Using this method, we have found that platelets roll along and adhere to retinal venous endothelium during ischemia-reperfusion and that these interactions are mediated by endothelial Pselectin, not by platelet P-selectin. MATERIALS AND METHODS Animal Model Male pigmented Long-Evans rats (200 -250 g) were used in this study. Transient retinal ischemia was induced for 60 minutes in the right eye of each rat