Tunable polarization comb based on the electromagnetically induced transparency with hybrid metal-graphene metamaterial

Noted a linear-to-circular polarization comb based on electromagnetically induced transparency (EIT) with hybrid metal-graphene metamaterial in terahertz (THz) spectroscopy. Due to the near field coupling between the bright mode of metal cut-wire (MCW) and multiple dark modes, the multi-peak EIT effect is exhibited under the x-polarized incidence supported by the three-level theory. With another orthogonal MCW etched on the back of the SiO2, the asymmetry responses in both polarized incidences (x- and y-polarized waves) further triggers the linear-to-circular polarization conversion (LTCPC). The values of four corresponding circular-polarized frequencies combined with transmission coefficients respectively are 0.90 THz with 0.45, 1.02 THz with 0.64, 1.15 THz with 0.60, 1.32 THz with 0.53, confirmed via relevant axial ratios and the electric field distributions. On the other hand, the drastic phase changes in transparent windows raise high group delays, among which the maximum value approaches 325 ps. Additionally, DC-voltage-driven graphene strips are doped at both ends of the back MCW to enhance the reconfigurability, superior tunable transmission behaviors illuminated by y-polarization with obvious changes at 0.90 THz and 1.02 THz can be achieved with the dynamic Fermi level fluctuating between 0.01 eV and 0.8 eV. Such an implementation creates a novel path to polarization modulators, signal transceivers, and information transmission devices.

Fabrication of Transparent and Conductive SWCNT/SiO2 Composite Thin-Film by Photo-Irradiation of Molecular Precursor Films

A single-walled carbon nanotube (SWCNT)-silica composite thin film on a quartz glass was formed by ultraviolet irradiation (20–40 °C) onto a spin-coated precursor film. With 7.4 mass% SWCNTs, the electrical resistivity reached 7.7 × 10−3 Ω·cm after UV-irradiation. The transmittance was >80% at 178–2600 nm, and 79%–73% at 220–352 nm. Heat treatment increased the transparency and pencil hardness, without affecting the low electrical resistivity. Raman spectroscopy and microscopic analyses revealed the excellent film morphology with good SWCNT dispersal. The low refractive index (1.49) and haze value (<1.5%) are invaluable for transparent windows for novel optoelectronic devices.

Dynamically Tunable Plasmon-induced Transparency in Parallel Black Phosphorus Nanoribbons

In this paper, we investigate the dynamically tunable plasmon-induced transparency (PIT) effects in parallel black phosphorus nanoribbons (BPNRs). The results show that the BPNRs having different lengths can be regarded as bright modes. Single-band, double-band, triple-band, and multi-band PIT effects based on the bright-bright mode coupling between parallel BPNRs are achieved. The physical mechanism of the single-band model can be explained theoretically by the radiating two-oscillator (RTO) model. Due to the heavier effective mass in the zigzag (ZZ) direction of the BP, the frequencies of the transparent peaks are shifted to lower frequencies when the placement directions of BPNRs are changed from the X-direction to the Y-direction. Furthermore, the resonant frequencies of the transparent windows in each model can be tuned by changing the relaxation rates of the BPNRs. The frequencies of the transparent windows are blue-shifted as the relaxation rates are increased. Finally, The corresponding sensors based on single-band PIT effect show high sensitivities of 7.35 THz/RIU. Our study has potential applications for improving the design of multiple-band filters, sensors and on-off switcher.

Bird-window collisions: Mitigation efficacy and risk factors across two years

Background Research on bird-window collision mitigation is needed to prevent up to a billion bird fatalities yearly in the U.S. At the University of Utah campus (Salt Lake City, Utah, USA), past research documented collisions, especially for Cedar Waxwings (Bombycilla cedrorum) drawn to fruiting ornamental pears in winter. Mirrored windows, which have a metallic coating that turns window exteriors into mirrors, had frequent collisions, which were mitigated when Feather Friendly®bird deterrent markers were applied. Bird-friendly windows–ORNILUX®ultraviolet (UV) and fritted windows–also reduced collisions when data were collected across fall and winter. Extending this prior research, we evaluated additional mitigation and tested the replicability of effects for pear trees, mirrored windows, and bird-friendly windows across two years. Methods Using published data from eight buildings monitored for collisions in year 1 (Fall and Winter, 2019–2020), we added another year of monitoring, Fall and Winter, 2020–2021. Between years, Feather Friendly®mitigation markers were added to collision-prone areas of two buildings, including both mirrored and transparent windows. Results The two buildings that received new Feather Friendly®mitigation had significantly fewer collisions post-mitigation. Control areas also had nonsignificant decline in collisions. The interaction of area (mitigation vs. control) by time (year 1 vs. 2) was significant, based on generalized estimating equations (GEE). The total yearly collisions across all eight buildings declined from 39 to 23. A second GEE analysis of all 8 buildings showed that mirrored windows, pear trees, and bird-friendly windows were each significant when analyzed separately. The best-fit model showed more collisions for mirrored windows and fewer collisions for bird-friendly windows. We found pear tree proximity to be related to more collisions in winter than fall. In addition, pear trees showed reduced collisions from year 1 to 2, consistent with new mitigation for two of three buildings near pear trees. Discussion Feather Friendly® markers can mitigate collisions with transparent windows, not only mirrored windows, compared to unmitigated areas over 2 years. Results also underscore the dangers of pear tree proximity and mirrored windows and the efficacy of bird-friendly windows. Thus, bird collisions can be prevented by window mitigation, permanent bird-friendly windows, and landscape designs that avoid creating ecological traps.

Xenon Plasma Focused Ion Beam Milling for Obtaining Soft X-ray Transparent Samples

We employ xenon (Xe) plasma focused ion beam (PFIB) milling to obtain soft X-ray transparent windows out of bulk samples. The use of a Xe PFIB allows for the milling of thin windows (several 100 nm thick) with areas of the order of 100 µm × 100 µm into bulk substrates. In addition, we present an approach to empirically determine the transmission level of such windows during fabrication by correlating their electron and soft X-ray transparencies. We perform scanning transmission X-ray microscopy (STXM) imaging on a sample obtained by Xe PFIB milling to demonstrate the conceptual feasibility of the technique. Our thinning approach provides a fast and simplified method for facilitating soft X-ray transmission measurements of epitaxial samples and it can be applied to a variety of different sample systems and substrates that are otherwise not accessible.

The effect of hydrophobic gases on the water fleaDaphnia magna

It is well known that some hydrophobic atomic and molecular gases provoke anaesthetic effects in mammal animals. Depending on the gas, there is a Minimum Alveolar Concentration (MAC) to produce anaesthesia. The gas enters in the lungs, dissolve in the blood and reaches the brain. Where are the targets and which are the action mechanisms are subjects not fully understood yet. Very recently, we reported the effects of local anaesthetics on the swimming behaviour of the water fleaDaphnia magna(STOTEN691, 278-283, 2019). Our aim now is to report new studies on the behaviour of this aquatic invertebrate in the presence of three hydrophobic gases: xenon, nitrous oxide and krypton. However, if local anaesthetics easily dissolve in water, these gases do not. Therefore, we designed a chamber to dissolve the gases using pressures up to 50 atmospheres. Simultaneously, we were able to measure in real time the response of the animals through transparent windows able to support such high pressures. Xenon and nitrous oxide effectively induce lack of movement in the daphnids. The effective pressures EP50for xenon and nitrous oxide were and 5.2 atmospheres, respectively. Krypton does not present clear effects on the motile suppression, even after the exposure to 44 atmospheres. Our findings provide insight on the physiological effects important gases used in human medicine produce in aquatic invertebrate animals considered as potential models to study anesthesia.

Visual Comfort Analysis of Semi-Transparent Perovskite Based Building Integrated Photovoltaic Window for Hot Desert Climate (Riyadh, Saudi Arabia)

Buildings consume considerable amount of energy to maintain comfortable interior. By allowing daylight, visual comfort inside a building is possible which can enhance the occupant’s health, mood and cognitive performance. However, traditional highly transparent windows should be replaced with semitransparent type window to attain a comfortable daylight inside a building. Evaluation of visual comfort includes both daylight glare and colour comfort analysis. Building integrated photovoltaic (BIPV) type windows are promising systems and can possess a range of semitransparent levels depending on the type of PV used. In this work, the semitransparent Perovskite BIPV windows was investigated by employing daylight glare analysis for an office building located in Riyadh, KSA and three wavelength dependent transmission spectra for colour comfort analysis. The results showed that the transmissions range between 50–70% was optimum for the comfortable daylight for south facing vertical pane BPV-windows. However, excellent colour comfort was attained for the transmission range of 90% which provided glare issues. Colour comfort for 20% transparent Perovskite was compared with contemporary other type of PV which clearly indicated that wavelength dependent transmittance is stronger over single value transmittance.