A Route to Unusually Broadband Plasmonic Absorption Spanning from Visible to Mid-infrared

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. In this paper, a route to ultra-broadband absorption is suggested and demonstrated by a feasible design. The high absorption regime (absorption above 90%) for the suggested structure ranges from visible to mid-infrared (MIR), i.e., for the wavelength varying from 478 to 3278 nm that yields an ultra-wide band with the width of 2800 nm. The structure consists of a top-layer-patterned metal-insulator-metal (MIM) configuration, into the insulator layer of which, an ultra-thin 5 nm layer of manganese (Mn) is embedded. The MIM configuration represents a Ti-Al2O3-Ti tri-layer. It is shown that, without the ultra-thin layer of Mn, the absorption bandwidth is reduced to 274 nm. Therefore, adding only a 5 nm layer of Mn leads to a more than tenfold increase in the width of the absorption band. It is explained in detail that the physical mechanism yielding this ultra-broadband result is a combination of plasmonic and non-plasmonic resonance modes, along with the appropriate optical properties of Mn. This structure has the relative bandwidth (RBW) of 149%, while only one step of lithography is required for its fabrication, so it is relatively simple. This makes it rather promising for practical applications.status: publishe

Toward Electrically Tunable, Lithography-Free, Ultra-Thin Color Filters Covering the Whole Visible Spectrum

The possibility of real-time tuning of optical devices has attracted a lot of interest over the last decade. At the same time, coming up with simple lithography-free structures has always been a challenge in the design of large-area compatible devices. In this work, we present the concept and the sample design of an electrically tunable, lithography-free, ultra-thin transmission-mode color filter, the spectrum of which continuously covers the whole visible region. A simple Metal-Insulator-Metal (MIM) cavity configuration is used. It is shown that using the electro-optic dielectric material of 4-dimethyl-amino-N-methyl-4-stilbazoliumtosylate (DAST) as the dielectric layer in this configuration enables efficient electrical tuning of the color filter. The total thickness of the structure is 120 nm, so it is ultra-thin. The output color gets tuned from violet to red by sweeping the applied voltage from -12 to +12 Volts (V). We present an in-detail optimization procedure along with a simple calculation method for the resonance wavelength of the MIM cavity that is based on circuit theory. Such power-efficient structures have a large variety of potential applications ranging from optical communication and switching to displays and color-tunable windows.status: publishe

Characteristics, sources, and health risks of atmospheric PM10-bound heavy metals in a populated middle eastern city

This study reports on the characteristics, sources, and health risks of atmospheric PM10-bound heavy metals (HMs) on citizenship living in different regions of Ahvaz, Southwest of Iran were investigated during 2016–2017. A total of 84 samples were analyzed from different regions: (S1) industrial, (S2) high traffic, and (S3) residential. Blood samples were collected from people who came to the east health center of Ahvaz. High volume air samplers, equipped with quartz fiber filters (8 × 10) were utilized for sampling in this study. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was also used for HMs. Risk assessment and hazard index of these pollutants were estimated, using USEPA’s exposure parameters. Based on the results, the highest and the lowest concentration of HM were observed in industrial and residential areas. Blood’s HMs concentration for chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) were 2.932, 4.199, 8.425, and 71.2 μg/dL, respectively. In conclusion, increasing exposure concentration of HMs would have a significant potential for increased cancer and risk of diseases. The results of this study show that increasing exposure concentration to HM in the studied scenarios have a significant potential for generating different health endpoints, although exposing to HMs led to generating diseases in individuals particularly in polluted and populated districts; so, environmental measures should be considered by urban air authorities to mitigate the concentration of these pollutants in ambient air

Antitrypanosomal triterpenoid with an ε-lactone e-ring from Salvia urmiensis

A new triterpenoid, urmiensolide (1), was isolated from Salvia urmiensis. The structure was elucidated by a combination of 1D and 2D NMR, HRESIMS, and X-ray crystallographic analyses. The absolute configuration was established by comparison of experimental and simulated ECD spectra. Urmiensolide is the first pentacyclic triterpenoid bearing a ε-lactone E-ring. The compound showed in vitro antitrypanosoal activity with an IC50 value of 5.6 μM against the Trypanosoma brucei rhodesiense STIB 900 strain and a selectivity index of 33. A possible biosynthetic pathway of 1 from α-amyrin is proposed