Freshwater alga Raphidocelis subcapitata undergoes metabolomic changes in response to electrostatic adhesion by micrometer-sized nylon 6 particles

Nylon powders are a type of microplastic (MP) used in personal care products such as cosmetics and sunscreens. To determine the effects of nylon polymers on freshwater microalgae, we investigated the effects of two types of micrometer-sized nylon polymers, i.e., powdered nylon 6 (Ny6-P) and nylon 12 (Ny12), and four other micrometer-sized MPs, i.e., low-density polyethylene, polyethylene terephthalate, polystyrene, and ultra-high-molecular-weight polyethylene, on the microalga Raphidocelis subcapitata. The results showed that Ny6-P inhibited R. subcapitata growth more than the other MPs; R. subcapitata growth was inhibited by 54.2% with 6.25 mg/L Ny6-P compared with the control. Ny6-P in the culture media adhered to R. subcapitata cells electrostatically, which may have disrupted growth and photosynthetic activity. Metabolomic analysis revealed that many metabolites related to the amino acid catabolic pathway and γ-glutamyl cycle were induced, which might trigger responses to avoid starvation and oxidative stress. Our study provides important information on the effects of Ny6-P on algae in freshwater environments.

Freshwater alga Raphidocelis subcapitata undergoes metabolomic changes in response to electrostatic adhesion by micrometer-sized nylon 6 particles

Nylon powders are a type of microplastic (MP) used in personal care products such as cosmetics and sunscreens. To determine the effects of nylon on freshwater microalgae, we investigated the effects of two types of micrometer-sized nylons, i.e., powdered nylon 6 (Ny6-P) and nylon 12 (Ny12), and four other micrometer-sized MPs, i.e., low-density polyethylene, polyethylene terephthalate, polystyrene, and ultra-high-molecular-weight polyethylene, on the microalga Raphidocelis subcapitata. The results showed that Ny6-P inhibited R. subcapitata growth more than the other MPs; R. subcapitata growth was inhibited by 54.2% with 6.25 mg/L Ny6-P compared with the control. Ny6-P in the culture media adhered R. subcapitata cells electrostatically, which disrupted growth and photosynthesis. Metabolomic analysis revealed that many metabolites related to the amino acid catabolic pathway and γ-glutamyl cycle were induced, which might reflect responses to avoid starvation and oxidative stress. Our study provides important information on the effects of Ny6-P on algae in freshwater environments.

A Miniaturized Dual-Slider Linear Actuator Using Electrostatic Adhesion and Inertia Drive

Dual-slider positioning in a miniaturized system is crucial in many industrial applications. This paper presents a miniaturized dual-slider linear actuator by employing one piezoelectric element (PZT) and integrating the methods of electrostatic adhesion and inertia drive. Two inertia drive methods can be converted by clamping and releasing one of the sliders on a base. Two thin-film electrodes are mounted on the base for clamping and releasing the slider by electrostatic adhesion. The actuator can thus drive dual sliders independently by converting the two inertia drive methods. A prototype is developed with a compact size of 30 mm (L) × 11 mm (W) × 11 mm (H) to evaluate the basic performance of the actuator. The maximum driving speeds of the two sliders are 31.7 mm/s and 16 mm/s, respectively, while the resolution of them is 60 nm and 13 nm, respectively. Additionally, the actuator can drive both the two sliders for long motion ranges of 14 mm. With a compact size and excellent physical performance, the proposed device has the potential for multi-slider positioning in miniaturized equipment.

Dual-functionalised shellac nanocarriers give a super-boost of the antimicrobial action of berberine

We demonstrate a strong enhancement of the antimicrobial action of berberine encapsulated in shellac nanoparticles with dual surface functionality. This is attributed to the electrostatic adhesion of the cationic nanocarriers to the microbial cell walls which leads to their accumulation and local delivery of berberine.