Free-standing plasmonic nanoarrays for leaky optical waveguiding and sensing

Flat optics nanogratings supported on thin free-standing membranes offer the opportunity to combine narrowband waveguided modes and Rayleigh anomalies for sensitive and tunable biosensing. At the surface of high-refractive index Si3N4 membranes we engineered lithographic nanogratings based on plasmonic nanostripes, demonstrating the excitation of sharp waveguided modes and lattice resonances. We achieved fine tuning of these optical modes over a broadband Visible and Near-Infrared spectrum, in full agreement with numerical calculations. This possibility allowed us to select sharp waveguided modes supporting strong near-field amplification, extending for hundreds of nanometres out of the grating and enabling versatile biosensing applications. We demonstrate the potential of this flat-optics platform by devising a proof-of-concept nanofluidic refractive index sensor exploiting the long-range waveguided mode operating at the sub-picoliter scale. This free-standing device configuration, that could be further engineered at the nanoscale, highlights the strong potential of flat-optics nanoarrays in optofluidics and nanofluidic biosensing. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreemen

Broadband and Tunable Light Harvesting in Nanorippled MoS2 Ultrathin Films

Nanofabrication of flat optic silica gratings conformally layered with two-dimensional (2D) MoS2 is demonstrated over large area (cm2), achieving a strong amplification of the photon absorption in the active 2D layer. The anisotropic subwavelength silica gratings induce a highly ordered periodic modulation of the MoS2 layer, promoting the excitation of Guided Mode Anomalies (GMA) at the interfaces of the 2D layer. We show the capability to achieve a broadband tuning of these lattice modes from the visible (VIS) to the near-infrared (NIR) by simply tailoring the illumination conditions and/or the period of the lattice. Remarkably, we demonstrate the possibility to strongly confine resonant and nonresonant light into the 2D MoS2 layers via GMA excitation, leading to a strong absorption enhancement as high as 240% relative to a flat continuous MoS2 film. Due to their broadband and tunable photon harvesting capabilities, these large area 2D MoS2 metastructures represent an ideal scalable platform for new generation devices in nanophotonics, photo- detection and -conversion, and quantum technologies

Growth dynamics of copper thin film deposited by soft-landing of size selected nanoclusters

We investigate surface kinetic roughening of copper films grown on Si(1 0 0) substrates at room temperature by means of atomic force microscopy study. Films were deposited at various durations by soft landing of size selected (~3 nm) nanoclusters using a state of the art nanocluster deposition system. The film growth exhibits two growth regimes with a crossover time of 40 min. In the first regime, surface morphologies show bimodal distribution and surface roughness shows a linear increase with growth exponent β = 0.14 ± 0.02. In the second regime, the height distribution becomes Gaussian and surface roughness shows a steep rise with high β value 0.83 ± 0.45. On the other hand, the roughness exponent α ranges from 0.68 ± 0.03 to 0.84 ± 0.01 for low to high deposition regimes. Estimated scaling exponent suggests the diffusion of clusters on substrate surface and shadowing effect play dominant role in growth mechanism of the nanostructured thin film

Expression of type I collagen in response to Isoniazid exposure is indirect and is facilitated by collateral induction of cytochrome P450 2E1: An in-vitro study.

We wanted to investigate whether Isoniazid (INH) can directly stimulate activation of hepatic stellate cells (HSCs) and enhance production of collagen. Treatment of human hepatic stellate cell line LX2 with or without 5μM INH for 24 to 72 hours was performed to look into content of cytochrome P450 2E1 (CYP2E1), activity of NADPH oxidase (NOX) and intracellular oxidative stress. Protein level as well as mRNA expression of alpha smooth muscle actin (α-SMA) and collagen1A1 (COL1A1) were assessed by western blot and real time PCR. In some experiments pyrazole (PY) was pre-treated to LX2 cells to induce CYP2E1 prior to INH treatment. CYP2E1 level as well as NOX activity was gradually increased with INH treatment in LX2 cells till 72 hours. Following 72 hours of INH exposure, intracellular glutathione (GSH) level was found to be reduced compared to control (p<0.01) and showed expression of α-SMA, indicating activation of HSC. We could not found any change in collagen expression in this experimental study. Pyrazole (PY) pre-treatment to LX2 cells caused significant increase in cellular CYP2E1 content associated with increase of NOX, intracellular reactive oxygen species (ROS), and expression of α-SMA and collagen1 after INH exposure. CYP2E1 is present in insignificant amount in HSCs and INH treatment could not induce collagen expression, although altered cellular oxidant levels was observed. But in LX2 cells when CYP2E1 was over-expressed by PY, INH administration provokes oxidative stress mediated stellate cells activation along with collagen type I expression

Bevel microstrip printed antenna for satellite communication

760-766A single feed, single layer compact bevel cut rectangular patch antenna is proposed. The bevels are cut at the left-top corner and the right-bottom corner. The 1st resonant frequency (4.25 GHz) is applicable for short band radio wave communication and the other resonant frequency (6.93 GHz) is applicable for radar communication. All the results are simulated by using IE3D, a MoM based software and the results are verified by the VNA network analyzer. This paper includes the bandwidth, return loss, vswr range and radiation pattern. </span

Compact microstrip patch antenna for microwave communication

800-807A single layer, single feed compact rectangular microstrip antenna is proposed. Resonant frequency has been reduced drastically by cutting three unequal rectangular slots at the edge of the patch and also small rectangular slots connected with the middle of every patch. Antenna size has been reduced by 47.4% with an increased frequency ratio when compared to a conventional square microstrip patch antenna.</b