Sex, size, and toe pad area of geckos used in experimental trials. Toe pad area is an estimate of maximal area of scansors visible on scans.

<p>Sex, size, and toe pad area of geckos used in experimental trials. Toe pad area is an estimate of maximal area of scansors visible on scans.</p

Experimental trials at variable temperatures without controlling for humidity.

<p>Relationship between temperature and body-size corrected adhesion (clinging force [N]; left axis, bars) or relative humidity (%; right axis, solid line).</p

Average maximal adjusted adhesive force (N) by species and temperature. Errors are ±1 SEM.

<p>Average maximal adjusted adhesive force (N) by species and temperature. Errors are ±1 SEM.</p

Adhesion at constant temperature of 12°C and variable relative humidity (RH).

<p>Adhesion increased significantly with RH, but slopes were not significantly different. Red lines and symbols show results of 35% and 80% trials at 32°C designed to test for an interaction of temperature and humidity; error bars represent ±2 SE. See text for details (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002192#s4" target="_blank">materials and methods</a>).</p

Force measuring apparatus.

<p>Geckos could be pulled at a constant rate selectable over a wide range of values. All pulls were accomplished with the substrate in a vertical orientation. Maximum force was the highest value recorded between the start of a pull and the point at which all four feet began to slide on the substrate.</p

Synthesis and Photoresponse of Large GaSe Atomic Layers

We report the direct growth of large, atomically thin GaSe single crystals on insulating substrates by vapor phase mass transport. A correlation is identified between the number of layers and a Raman shift and intensity change. We found obvious contrast of the resistance of the material in the dark and when illuminated with visible light. In the photoconductivity measurement we observed a low dark current. The on–off ratio measured with a 405 nm at 0.5 mW/mm² light source is in the order of 10³; the photoresponsivity is 17 mA/W, and the quantum efficiency is 5.2%, suggesting possibility for photodetector and sensor applications. The photocurrent spectrum of few-layer GaSe shows an intense blue shift of the excitation edge and expanded band gap compared with bulk material

Anisotropically Functionalized Carbon Nanotube Array Based Hygroscopic Scaffolds

Creating ordered microstructures with hydrophobic and hydrophilic moieties that enable the collection and storage of small water droplets from the atmosphere, mimicking structures that exist in insects, such as the Stenocara beetle, which live in environments with limited amounts of water. Inspired by this approach, vertically aligned multiwalled carbon nanotube forests (NTFs) are asymmetrically end-functionalized to create hygroscopic scaffolds for water harvesting and storage from atmospheric air. One side of the NTF is made hydrophilic, which captures water from the atmosphere, and the other side is made superhydrophobic, which prevents water from escaping and the forest from collapsing. To understand how water penetrates into the NTF, the fundamentals of water/NTF surface interaction are discussed

Carbon Nitrogen Nanotubes as Efficient Bifunctional Electrocatalysts for Oxygen Reduction and Evolution Reactions

Oxygen reduction and evolution reactions are essential for broad range of renewable energy technologies such as fuel cells, metal-air batteries and hydrogen production through water splitting, therefore, tremendous effort has been taken to develop excellent catalysts for these reactions. However, the development of cost-effective and efficient bifunctional catalysts for both reactions still remained a grand challenge. Herein, we report the electrocatalytic investigations of bamboo-shaped carbon nitrogen nanotubes (CNNTs) having different diameter distribution synthesized by liquid chemical vapor deposition technique using different nitrogen containing precursors. These CNNTs are found to be efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions. The electrocatalytic activity strongly depends on the nanotube diameter as well as nitrogen functionality type. The higher diameter CNNTs are more favorable for these reactions. The increase in nanotube diameter itself enhances the catalytic activity by lowering the oxygen adsorption energy, better conductivity, and further facilitates the reaction by increasing the percentage of catalytically active nitrogen moieties in CNNTs

An Atomically Layered InSe Avalanche Photodetector

Atomically thin photodetectors based on 2D materials have attracted great interest due to their potential as highly energy-efficient integrated devices. However, photoinduced carrier generation in these media is relatively poor due to low optical absorption, limiting device performance. Current methods for overcoming this problem, such as reducing contact resistances or back gating, tend to increase dark current and suffer slow response times. Here, we realize the avalanche effect in a 2D material-based photodetector and show that avalanche multiplication can greatly enhance the device response of an ultrathin InSe-based photodetector. This is achieved by exploiting the large Schottky barrier formed between InSe and Al electrodes, enabling the application of a large bias voltage. Plasmonic enhancement of the photosensitivity, achieved by patterning arrays of Al nanodisks onto the InSe layer, further improves device efficiency. With an external quantum efficiency approaching 866%, a dark current in the picoamp range, and a fast response time of 87 μs, this atomic layer device exhibits multiple significant advances in overall performance for this class of devices

Dynamics of Ice Nucleation on Water Repellent Surfaces

Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of <i>passive</i> nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing on these surfaces is not clearly understood. In this work, we present an in-depth analysis of ice formation dynamics upon water droplet impact on surfaces with different wettabilities. We experimentally demonstrate that ice nucleation under low-humidity conditions can be delayed through control of surface chemistry and texture. Combining infrared (IR) thermometry and high-speed photography, we observe that the reduction of water–surface contact area on superhydrophobic surfaces plays a <i>dual</i> role in delaying nucleation: first by reducing heat transfer and second by reducing the probability of heterogeneous nucleation at the water–substrate interface. This work also includes an analysis (based on classical nucleation theory) to estimate various homogeneous and heterogeneous nucleation rates in icing situations. The key finding is that ice nucleation delay on superhydrophobic surfaces is more prominent at moderate degrees of supercooling, while closer to the homogeneous nucleation temperature, bulk and air–water interface nucleation effects become equally important. The study presented here offers a comprehensive perspective on the efficacy of textured surfaces for nonicing applications