To reaffinn the use of a mainstream CMOS process for designing passive-like attenuator structures, a linear-controlled variable attenuator is realized with 0.35um CMOS process, which covers the broad frequency band (DC-I GHz). Compared to existing passive-like CMOS attenuators, it is demonstrated that this work advances the frequency band from MHz to GHz, and reduces the size. To elevate the limit of bandwidth, an alternative topology, which covers DC2GHz, is proposed as well. Operation principle and its characteristics are exolained in detail.

Aerosolized droplets are produced en masse in dental practices; these aerosols disperse in the surrounding space, posing a health threat if the patient is infected with a transmittable disease, particularly COVID-19. Here, a viscoelastic polyacrylic acid (PAA) solution was used to minimize liquid aerosolization and limit the travel distance of aerosols. The PAA concentration was varied to evaluate its effect on aerosolization and droplet size resulting from procedures using dental handpieces, which include tooth cutting, grinding, and polishing. In addition, a thermocouple was inserted at the center of the model tooth to measure its temperature during a handpiece operation. The temperature data suggest that the cooling performance of the PAA solution is comparable to that of pure water in operations in the occlusal and facial directions. The PAA solution droplets splattered on the patient's facial area during the handpiece operation are markedly larger than those of pure water, which is evidence of the settling of the PAA droplets, preventing further transmission. Accordingly, the travel distance of the aerosolized PAA droplets was limited by viscoelastic resistance to droplet detachment. This comparison of the aerosol suppression capability between water and PAA solutions confirms the benefit of using viscoelastic solutions for various dental operations.

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In the present work, aqueous solutions of NaPAA [poly (sodium acrylate)] or PAA [polyacrylic acid] are used as the coolants for a dental handpiece to evaluate their suppressive effect on the aerosolization and bacteria ( Staphylococcus epidermidis) transmission in an actual dental environment. Both polymer solutions significantly suppressed the formation of aerosols (<50  μm) and droplets (50–100  μm). The suppression effect was stronger at higher concentrations. The 10 and 20 wt. % of viscous Newtonian solutions of low-molecular weight NaPAA were much less effective in disintegration suppression than the viscoelastic 1 and 2 wt. % PAA solutions. The latter was capable of complete suppression of disintegration, forming instead long liquid threads attached to the rotating bur and settling down underneath. The suppression efficiency of the 2 wt. % PAA solution stems from significant elastic forces in it which prevent drop detachment. In the case of water used as a coolant, the bacterial spread was observed through aerosol, droplets, and splatter. The bacterial spread by large splatters was inversely proportional to the distance from the rotating bur. The spread of aerosols significantly occurred in the direction that the handpiece was facing, and multiple airborne aerosols settled on the wall rather than on the floor. On the other hand, the viscoelastic aqueous 2 wt. % PAA solution suppressed bacterial spread, regardless of the distance or direction.

Cooling liquids used in ultrasonic scalers are aerosolized into droplets. Larger droplets splatter over dental practitioners and patients, and small aerosols become airborne, posing a health threat to people in the surrounding area if a patient is infected by viral or bacterial infections. Polyacrylic acid (PAA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP) can efficiently cool teeth and suppress aerosolization owing to their rheological properties, with PAA being the superior viscoelastic suppressant. Although the solutions of PEG and PVP studied here are also efficient in suppressing aerosol formation, their high viscosity may hinder their supply to the dental tools because of high viscous dissipation. The rheological behavior of PAA, PEG, and PVP is studied in the uniaxial elongational flow in self-thinning capillary threads. Then, the behavior of these solutions in an ultrasonic scaler in dental practice is explored. In particular, the aerosolization phenomena and the corresponding aerosol size distributions and droplet trajectories are studied and compared. The tooth temperature is found to be similar to that of water when these polymer solutions are used. The dispersion of the aerosolized droplets is qualitatively demonstrated by performing scaling using model teeth on a phantom mannequin face.

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Summary We fabricated ultrathin nanosheets of bimetallic chalcogenides (NiGa2S4) using a hydrothermal process, which significantly reduced the number of Li+ diffusion pathways and promoted rapid electron transport. Flexible carbon nanofibers (CNFs) were prepared by electrospinning and post‐annealing. These CNFs were electroplated with nickel and decorated with gallium, which has a relatively high theoretical capacity and low volume‐expansion rate during lithiation. The gallium concentration was optimized to obtain the thinnest and most uniform NiGa2S4 nanosheets. The optimal anode exhibited a reversible specific capacity of 1349 mAh·g−1 at a current density of 62.5 mA·g−1 in the first cycle. Furthermore, the NiGa2S4 anode was used to power a light‐emitting‐diode under severe bending conditions, demonstrating its superior mechanical durability.

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