A LTCC-Based Ku-Band 8-Channel T/R Module Integrated with Drive Amplification and 7-Bit True-Time-Delay

Ku-band drive amplification and a 7-bit true-time-delay (TTD) function were realized as a part of a LTCC-based T/R module to increase integration. The 8-channel T/R module was fabricated and its key characteristics were measured, including a 3-bit (1/2/4 λ) TTD, 4-bit (0.25/0.5/1/2 λ) TTD, receive gain, noise figure and output power. The 8-channel T/R module can be further adopted to increase bandwidth and scanning angle of phased arrays without beam squint

In situ preparation, characterization, magnetic and catalytic studies of surfactant free RGO/FeₓCo₁₀₀₋ₓ nanocomposites

A novel, "wet" and "clean" methodology was developed to prepare FeₓCo₁₀₀₋ₓ nanoparticles on reduced graphene oxide (RGO) surfaces in an aqueous solution through a coreduction process. Without any surface treatment, FeₓCo₁₀₀₋ₓ nanoparticles can in situ grow on the RGO sheets. It was found that RGO nanosheets can effectively prevent the aggregation of FeₓCo₁₀₀₋ₓ nanoparticles. The results reveal that the RGO/FeₓCo₁₀₀₋ₓ nanocomposites have ferromagnetic characteristics and show composition dependent magnetic properties. The effectiveness of the as-prepared RGO/FeₓCo₁₀₀₋ₓ nanocomposites as solid phase heterogeneous catalysts have been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess sodium borohydride. The effect of initial 4-NP concentration, and catalyst loading dose were evaluated. The catalyst efficiency was examined on the basis of turnover frequency (TOF) and recyclability. The RGO/Fe₂₅Co₇₅ nanocomposites exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the graphene oxide (GO) supports also enhance the catalytic activity via a synergistic effect. The as-prepared RGO/FeₓCo₁₀₀₋ₓ nanocomposite catalysts are very efficient, stable, easy to prepare, eco-friendly, cost-effective, and have potential industrial applications7 page(s

Colorimetric Method for Sensitive Detection of Microcystin-LR Using Surface Copper Nanoparticles of Polydopamine Nanosphere as Turn-On Probe

A novel, facile sensor was further developed for microcystin-LR (MC-LR) determination by visible spectroscopy. Antibody-functionalized SiO2-coated magnetic nanoparticles (Fe3O4@SiO2) and aptamer-functionalized polydopamine nanospheres decorated with Cu nanoparticles (PDA/CuNPs) recognized specific sites in MC-LR and then the sandwich-type composites were separated magnetically. The Cu in the separated composites was converted to Cu2+ ions in solution and turn-on visible absorption was achieved after reaction with bis(cyclohexanone)oxaldihydrazone (BCO) (λmax = 600 nm). There was a quantitative relationship between the spectral intensity and MC-LR concentration. In addition, under the optimum conditions, the sensor turns out to be a linear relationship from 0.05 to 25 nM, with a limit of detection of 0.05 nM (0.05 μg/L) (S/N = 3) for MC-LR. The sensitivity was dependent on the low background absorption from the off-to-on spectrum and label amplification by the polydopamine (PDA) surface. The sensor had high selectivity, which shows the importance of dual-site recognition by the aptamer and antibody and the highly specific color formed by BCO with Cu2+. The bioassay was complete within 150 min, which enabled quick determination. The sensor was successfully used with real spiked samples. These results suggest it has potential applications in visible detection and could be used to detect other microcystin analogs