In this study, we demonstrated a noble Ag-decorated graphene oxide catalyst (GOSH-Ag) for use in the decarboxylative cycloaddition reaction. The catalyst was easily prepared by depositing Ag nanoparticles on thiolated graphene oxide (GOSH) surfaces. Transmission electron microscopy (TEM) indicated that the nanoparticles were well-dispersed and of a small, approximately 3.7 nm average size. These characteristics resulted in a high surface area, which enhanced the catalytic activity of the supported catalyst. Moreover, it was found that the aggregation of Ag catalysts was inhibited by the strong adhesion between the GOSHs and the Ag nanoparticles during the chemical reactions, thereby permitting their reuse. Indeed, the supported catalyst could easily be separated and recovered from the reaction mixture and reused several times.

A broadband compact-sized planar four-port multiple-input–multiple-output (MIMO) antenna with polarization diversity is presented. The proposed dual circularly polarized (CP) MIMO antenna consists of four G-shaped monopole elements, two of which are left-hand CP and the other two are right-hand CP. A vertical line strip in the G-shaped radiating element acts in balancing the vertical and horizontal electric field components to obtain 90° phase difference between them for circular polarization. Also, an I-shaped strip is incorporated between the ground planes of the G-shaped antenna elements to obtain equal voltage level in the proposed MIMO configuration. The dual circular polarization mechanism of the proposed MIMO/diversity antenna is analysed from the vector current distributions. The impedance bandwidth (S₁₁ ≤ –10 dB) of the MIMO antenna is 105.9% (4–13 GHz) and the 3 dB axial ratio bandwidth (ARBW) is 67.7% (4.2–8.5 GHz), which is suitable for C-band applications. The overall size of the MIMO antenna is 70 × 68 × 1.6 mm³, and the minimum isolation between the resonating elements is 18 dB. The envelope correlation coefficient is less than 0.25, and the peak gain within the resonating band is 6.4 dBi.

To investigate the relationship between the linker length and the catalytic activities of metal-decorated CNTs, three samples were prepared with different linker molecules, viz.NaSH, HSCH₂CH₂SH, and C₂H₂N₂S₃. The structures of the prepared samples were characterized using transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The analysis of the TEM images and XRD patterns showed that the Pd nanoparticles strongly adhered to the outside of the CNTs, with average particle sizes of ∼3 nm, ∼5 nm, and ∼6 nm for samples A, B and C, respectively. The XPS spectra revealed that the Pd species on the Pd-decorated CNTs consisted of Pd⁰, Pd²⁺ and Pd⁴⁺. The oxidized Pd species were formed by the interaction of the electron-donor Pd⁰ atoms with the electrophilic neighboring protons (H⁺) during the sample preparation. The oxidized Pd species become more abundant with increasing linker length, causing a decrease of their catalytic activities in organic and electrocatalytic reactions. Nevertheless, all of the samples exhibited higher activity in organic and electrocatalytic reactions than that of the reference systems.

A dual-bowtie antenna loaded with a double-sided dielectric lens is presented for wideband and high gain performance. The dielectric lens is a combination of the elliptical and conical frustum lenses formed on two sides (top and bottom) of a rectangular dielectric block, respectively. The conical frustum lens is mounted at the backside of the bowtie radiator to collect the radiated energy towards the elliptical lens. The bowtie antenna is fed by a coplanar strip (CPS) taper connected to a CPS-to-MSL (microstrip line) transition. The proposed lens-integrated antenna is fabricated, and measured to have an operating bandwidth of 20.5 40.0 GHz. The antenna offers a peak gain of 15.1 dB. Also, the use of the double-sided dielectric lens helps to reduce the lens size of the equivalent gain by 31%. The overall size of the proposed lens antenna is 940 mil × 940 mil × 1008 mil.

Objective: This paper presents the design of an electrically small circularly polarized (CP) 3 $ \times $ 3 mm ² antenna system as an intraocular unit for retinal prosthesis application. Methods: The system is operating in ISM and ultra-wideband (UWB) bands to target high programmability of retina stimulation and recording, respectively. The electrical dimensions, including the ground plane, are $\ {{\boldsymbol{\lambda }}_0}/41\ \times \ {{\boldsymbol{\lambda }}_0}/41\ \times \ {{\boldsymbol{\lambda }}_0}/191$ . Physical limitations of the antenna are discussed based on Hansen and Collin's limitations. The proposed wire patch antenna exhibits wideband characteristics by combining multiple modes of the patch antenna in the presence of an interface PCB circuit. Results: By loading polyimide encapsulated patch with stubs, dominant TM ₀₁₀ mode is combined with the higher order modes TM ₀₂₀ – TM ₀₇₀ to exhibit wide –10 dB impedance bandwidth of 2–11 GHz. Annular rings and shorting pins in the ground plane provide CP radiation at 2.45, 5.8, and 8 GHz with 3-dB axial-ratio bandwidth of 0.3, 0.16, and 1.2 GHz, and far-field left hand circularly polarized (LHCP) gain of –18.4, –7.6, and –4.7 dBic, respectively, in broadside direction. A biocompatible antenna system is designed using Ansys HFSS in the presence of a detailed multilayer canonical eye model. Additionally, it is examined in an anatomical HFSS head model. Near and far-field electric field distribution is studied along with peak 1-g average specific absorption rate (SAR) calculations. Conclusion: The proposed antenna is fabricated, and the performance, including coupled power from an external antenna, is measured in a custom made eye model including head phantom. A reasonable agreement is obtained between simulated and measured results. Significance: To generate an artificial vision, image perception capability could be improved with implantable UWB communication systems that feature particularly high data-rate and small size.