The design and fabrication of a micromechanical capacitive membrane microwave switching device is described. The switching element consists of a thin metallic membrane, which has two states, actuated or unactuated, depending on the applied bias. A microwave signal is switched on and off when the membrane is switched between the two states. These switches have a switching on speed of less than 6 s and a switching off speed of less than 4 s. The switching voltage is about 50 V. The switches have a bowtie shape and showed low insertion loss of 0.14 dB at 20 GHz and 0.25 dB at 35 GHz, and isolation of 24 dB at 20 GHz and 35 dB at 35 GHz. These devices offer the potential for building a new generation of low-loss high-linearity microwave circuits for a variety of phased antenna arrays for radar and communications applications. [324]

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This letter details the construction and performance of metal membrane radio frequency MEMS switches at microwave and millimeter-wave frequencies. These shunt switches possess a movable metal membrane which pulls down onto a metal/dielectric sandwich to form a capacitive switch. These switches exhibit low loss (< < <0.25 dB at 35 GHz) with good isolation (35 dB at 35 GHz). These devices possess on-off capacitance ratios in the range of 80-110 with a cutoff frequency (figure of merit) in excess of 9000 GHz, significantly better than that achievable with electronic switching devices.

An efficient and regioselective synthesis of fused polycyclic furo[3,4-c]indolo[2,1-a]isoquinolines through Rh(III)catalyzed cascade C−H activation/annulation/lactonization of 2-arylindoles and 4-hydroxy-2-alkynoates has been developed. This cascade reaction displays high step economy and efficiency and tolerates various functional groups. The titled polycyclic furo[3,4c]indolo[2,1-a]isoquinolines exhibit fluorescence emission.

In this paper, novel self-supported micropatterns of double-fold snowflake copper sulfide (Cu 2 S) dendrites were successfully synthesized by a template-and surfactant-free method based on a simple reaction of CuSO 4 ‚5H 2 O and dimethyl sulfoxide (DMSO), in which DMSO performed multiple roles as a solvent, a sulfur source, and a reducing agent. The influences of the concentration of CuSO 4 ‚5H 2 O, the reaction time, and the temperature on the morphology of the products are discussed. Possible crystal growth processes are also proposed on the basis of the experimental results.

Micrometer-scaled hierarchical tubular structures of CuS assembled by nanoflake-built microspheres were first synthesized in high yield via a one-pot intermediate crystal templating process without surfactant or added templates, in which the intermediate complex Cu 3 (TAA) 3 Cl 3 formed in situ and subsequently served as a self-sacrificed template. Whereas the intermediate complex and final hierarchical structures were well characterized, the formation mechanism was preliminarily studied based on X-ray diffraction (XRD) studies and scanning electron microscopy (SEM) observations by arresting the growth at a series of intermediate stages in the formation of the hierarchical tubular structures. The benefits for the as-obtained nanostructures arise from their ultrahigh Brunauer-Emmett-Teller (BET) value and the potential capacity advantage for the catalyst industry and hydrogen storage.

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We report on the results of a diary study of the everyday volunteering and help giving of individuals in the millennial generation. We describe the breadth of work structures implicated in volunteering, the social structures implicated in volunteering, and the interdependencies between the two. We analyze the roles that technology plays in volunteering with a particular focus on the forms of infrastructure that are constituted through the work and social structures of this philanthropic activity. Finally, we reflect on design opportunities for infrastructures where work and social structures meet to support more everyday, ubiquitous forms of volunteering.