Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives.

Particulate matter 2.5 (PM2.5) filter samples were collected in July and October 2014 and January and April 2015 in urban Shanghai and analyzed using ultrahigh‐performance liquid chromatography coupled to Orbitrap mass spectrometry. The measured chromatogram‐mass spectra were processed by a nontarget screening approach to identify significant signals. In total, 810–1,510 chemical formulas of organic compounds in the negative polarity (negative electrospray ionization (ESI−)) and 860–1,790 in the positive polarity (ESI+), respectively, were determined. The chemical characteristics of organic aerosols (OAs) in Shanghai varied among different months and between daytime and nighttime. In the January samples, organics were generally richer in terms of both number and abundance, whereas those in the July samples were far lower. More CHO− (compounds containing only carbon, hydrogen, and oxygen and detected in ESI−) and CHOS− (sulfur‐containing organics) were found in the daytime samples, suggesting a photochemical source, whereas CHONS− (nitrogen‐ and sulfur‐containing organics) were more abundant in the nighttime samples, due to nocturnal nitrate radical chemistry. A significant number of monocyclic and polycyclic aromatic compounds, and nitrogen‐ and sulfur‐containing heterocyclic compounds, were detected in all samples, indicating that biomass burning and fossil fuel combustion made important contributions to the OAs in urban Shanghai. Additionally, precursor‐product pair analysis indicates that the epoxide pathway is an important formation route for organosulfates observed in Shanghai. Moreover, a similar analysis suggests that 35–57% of nitrogen‐containing compounds detected in ESI+ could be formed through reactions between ammonia and carbonyls. Our study presents a comprehensive overview of OAs in urban Shanghai, which helps to understand their characteristics and sources.

Many dsDNA viruses first assemble a DNA-free procapsid, using a scaffolding protein-dependent process. The procapsid, then, undergoes dramatic conformational maturation while packaging DNA. For bacteriophage T7 we report the following four single-particle cryo-EM 3D reconstructions and the derived atomic models: procapsid (4.6-Å resolution), an early-stage DNA packaging intermediate (3.5 Å), a later-stage packaging intermediate (6.6 Å), and the final infectious phage (3.6 Å). In the procapsid, the N terminus of the major capsid protein, gp10, has a six-turn helix at the inner surface of the shell, where each skewed hexamer of gp10 interacts with two scaffolding proteins. With the exit of scaffolding proteins during maturation the gp10 N-terminal helix unfolds and swings through the capsid shell to the outer surface. The refolded N-terminal region has a hairpin that forms a novel noncovalent, joint-like, intercapsomeric interaction with a pocket formed during shell expansion. These large conformational changes also result in a new noncovalent, intracapsomeric topological linking. Both interactions further stabilize the capsids by interlocking all pentameric and hexameric capsomeres in both DNA packaging intermediate and phage. Although the final phage shell has nearly identical structure to the shell of the DNA-free intermediate, surprisingly we found that the icosahedral faces of the phage are slightly (∼4 Å) contracted relative to the faces of the intermediate, despite the internal pressure from the densely packaged DNA genome. These structures provide a basis for understanding the capsid maturation process during DNA packaging that is essential for large numbers of dsDNA viruses.bacteriophage T7 maturation | DNA packaging intermediates | noncovalent topological linking | procapsid | single-particle cryo-EM M any dsDNA viruses, including tailed phages and herpes viruses, initially assemble a DNA-free procapsid with assistance of a network of scaffold proteins. Accompanying the exit of scaffolding proteins during subsequent ATP-driven DNA packaging, the icosahedral shell of the procapsid undergoes dramatic conformational changes and matures into a typically larger and more angular shell of the infectious phage (1-6). However, structural details, including those of capsid intermediates, are limited to the phage HK97 system (5, 7-9), for which recombinantly produced procapsid and nonphysiological conversion products were analyzed.The packaging of the 39.937-kbp DNA genome of the shorttail Escherichia coli bacteriophage, T7, is a model for understanding basic principles common to dsDNA tailed phages and herpes viruses. The T7 system is also of interest because it has been used for popular biotechnologies, such as recombinant protein expression (10) and protein display on the capsid surface (11). The T7 capsid contains 415 copies of the major shell protein gp10 (12) that form a T = 7L icosahedral lattice. From lowresolution cryo-EM 3D reconstructions the tertiary topology of gp10 can be divided into four regions: N-...

Quantum-dot light-emitting diodes (QLEDs) combine the stable, efficient, and high color-purity emission of quantum dots (QDs) and the advantages of cost-effective solution-based processing techniques, promising large-area electroluminescent devices ideal

With the fast development of high-temperature metal oxide semiconductor field effect transistors for power electronics in electric vehicles, current state-of-the-art biaxially oriented polypropylene (BOPP) film capacitors need further improvement because they have a temperature rating of only 85 °C without derating the voltage to maintain a long lifetime. If a high-temperature polymer can replace BOPP without sacrificing the overall dielectric performance and cost, it is possible to remove the current water-cooling system for capacitors and significantly reduce the cost of the power electronic unit. In this work, we demonstrated new polycarbonate (PC)/nylon multilayer films (MLFs), which has a potential for even higher temperature rating because of the higher melting temperature for nylons (e.g., nylon-6). Structural and dielectric studies showed that these PC/nylon MLFs had a similar dielectric performance, such as dielectric constant, dielectric loss, and breakdown strength, as the PC/poly­(vinylidene fluoride) PVDF MLFs, which were developed in the past. These PC/nylon MLFs could perform well up to 120 °C, which was limited by the glass transition temperature of PC at 145 °C. More intriguingly, packaged PC/nylon-12 MLF capacitors exhibited a self-healing capability, which had been difficult for packaged high-temperature film capacitors. Because self-healing is such a fundamental requirement for polymer film capacitors, our PC/nylon MLFs offer a potential for next-generation high-temperature and high-energy density film capacitors.