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Silicon-based lithium-ion battery anodes have brought encouraging results to the current state-of-the-art battery technologies due to their high theoretical capacity, but their large-scale application has been hampered by a large volume change (>300%) of silicon upon lithium insertion and extraction, which leads to severe electrode pulverization and capacity degradation. Polymeric surfactants directing the combination of silicon nanoparticles and reduced graphene oxide have attracted great interest as promising choices for accommodating the huge volume variation of silicon. However, the influence of different polymeric surfactants on improving the electrochemical performance of silicon/reduced graphene oxide (Si/RGO) anodes remains unclear because of the different structural configurations of polymeric surfactants. Here, we systematically study the effect of different polymeric surfactants on enhancing the Si/RGO anode performance. Three of the most well-known polymeric surfactants, poly(sodium 4-styrenesulfonate) (PSS), poly(diallydimethylammonium chloride) (PDDA), and polyvinylpyrrolidone (PVP), were used to direct the combination of silicon nanoparticles and RGO through van der Waals interaction. The Si/RGO anodes made from these composites act as ideal models to investigate and compare how the van der Waals forces between polymeric surfactants and GO affect the final silicon anode performance from both experimental observations and theoretical simulations. We found that the capability of these three surfactants in enhancing long-term cycling stability and high-rate performance of the Si/RGO anodes decreased in the order of PVP > PDDA > PSS.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), has evolved resistance to various types of insecticides in the field. In the present study, the resistance of P. xylostella (designated Cya-SEL) to cyantraniliprole increased to 30.6 and 326-fold after 26 generations of selection, compared with the field population (TA) and susceptible population (LAB), respectively. The resistant population also had developed low to moderate levels of resistance to abamectin (3.3-fold), flubendiamide (14.1-fold), and chlorantraniliprole (24.3-fold). Synergism tests indicated that piperonyl butoxide (PBO) and diethyl maleate (DEM) increased the toxicity of cyantraniliprole in the selected strain, i.e., synergism ratio was 2.8 and 3.3-fold, respectively. Reciprocal crosses were made between the susceptible (LAB) and resistant strain collected from Zengcheng (ZC). The degree of dominance and overlapping confidence intervals of LC 50 values of F1 progenies (ZC♀ 9 LAB♂ and LAB♀ 9 ZC♂) suggested an autosomal and incompletely recessive mode of resistance to cyantraniliprole. The test of monogenic inheritance based on a backcross of F1 progeny with the ZC population indicated that resistance to cyantraniliprole was controlled by multiple genes. Additionally, Cya-SEL had a lower reproductive ability and relative fitness than the other tested populations. These findings provide useful information for effective resistance management strategies against P. xylostella.

Atomically thin materials, such as graphene and transition metal dichalcogenides, are promising candidates for future applications in micro/nanodevices and systems. For most applications, functional nanostructures have to be patterned by lithography. Developing lithography techniques for 2D materials is essential for system integration and wafer‐scale manufacturing. Here, a thermomechanical indentation technique is demonstrated, which allows for the direct cutting of 2D materials using a heated scanning nanotip. Arbitrarily shaped cuts with a resolution of 20 nm are obtained in monolayer 2D materials, i.e., molybdenum ditelluride (MoTe2), molybdenum disulfide (MoS2), and molybdenum diselenide (MoSe2), by thermomechanically cleaving the chemical bonds and by rapid sublimation of the polymer layer underneath the 2D material layer. Several micro/nanoribbon structures are fabricated and electrically characterized to demonstrate the process for device fabrication. The proposed direct nanocutting technique allows for precisely tailoring nanostructures of 2D materials with foreseen applications in the fabrication of electronic and photonic nanodevices.

Inspired by the anti-reflection functionality of cicada wings decorated with nanocone arrays, a facile technique to endow flexible polymer substrates of diverse chemical compositions with the same functionalities has been devised. In this universally applicable two-step technique based on a capacitatively coupled radiofrequency plasma (CCRP), first oxygen-plasma treatment (OPT) is implemented to grow arrays of vertical elongated nanostructures with almost uniform cross-sectional diameter of the polymer substrate, and then fluorocarbon polymer deposition (FPD) is carried out so that the nanostructures evolve into nanocones with small apex angle. The dependence of ion-bombardment-induced sputtering on the local impingement angle of ions taper the vertical nanostructures into the nanocones during the FPD under CCRP. The nanocone arrays exhibit low specular reflectance in a broad wavelength range and a wide incidence angle range that is quite insensitive to the polarization state of the incident light. The effective refractive index gradient of irregularly arranged nanocone arrays is characterized from the refractive index of the fluorocarbon polymer and the volume fraction considering the nanocone probability with the Gaussian distribution. The excellent broadband and omnidirectional anti-reflection properties are in consequence of a graded refractive index.

The presence of random arrays of elongated nanostructures with dimensional nonuniformity on the cuticular surfaces of insects endows them with antiwetting characteristics, as exemplified by nanopillar arrays on dragonfly wings and nanocone arrays on cicada wings. But the roles of the nanostructure shape and dimensional nonuniformity, as well as of the randomness of placement, on antiwetting characteristics are difficult to delineate because of the different chemical compositions of the surfaces of dragonfly and cicada wings. Therefore, biomimetic random arrays of nanopillars and nanocones with a similar tip diameter, placement irregularity, and chemical composition were fabricated on polypropylene substrates by plasma etching and polymerization. Gaussian nonuniformity of the nanopillar/nanocone dimensions as well as the irregularity of their placement were considered in determining the antiwetting capillary pressure and the adhesion energy. The gradient of the antiwetting capillary pressure normal to the substrate plane is the reason for nanocone arrays to resist wetting by water droplets impacting at high speeds much better than nanopillar arrays. The tapered shape of nanocones also promotes the dewetting transition of droplets from the sticky Wenzel state to the slippery Cassie state.

No abstract

Steroid estrogens, such as 17β-estradiol (E2), in animal manure pose a potential threat to the aquatic environment. The transport and estrogenicity of estrogens influence the sorption of estrogens to dissolved organic matter (DOM) in animal manure, and composting treatment alters the structure and composition of the manure. The objectives of the present study were to identify the contribution of the molecular composition of DOM of composted manure to the sorption of E2 and then elucidate the dominant mechanisms involved in the interaction of E2 with manure-derived DOM. The excitation-emission matrix (EEM) spectra and atomic force microscopy (AFM) showed that composting significantly altered the chemical composition and structure of DOM. A decrease in the atomic ratios of oxygen (O)/carbon (C) occurred in conjunction with the formation of DOM aggregates in the composted manure, indicating that the hydrophilicity and polarity of the DOM decreased after composting. Composting increased the sorption coefficients (K) for E2 to DOM, and K was positively correlated with the proportion of the fulvic acid (FA)-like fraction and molecular weight (MW) fractions of the DOM (range of 1.0 × 10-7.0 × 10 Da and 7.0 × 10-1.4 × 10 Da). Specifically, E2 showed a tendency for sorption to medium-sized FA-like molecules of DOM aggregates in composted manure. Hydrophobic forces and π-π binding appeared to be the main mechanisms underlying the aforementioned interaction.