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Ultrahydrophobicity
In chemistry and materials science, ultrahydrophobic (or superhydrophobic) surfaces are highly hydrophobic, i.e., extremely difficult to wetting, wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°. This is also referred to as the lotus effect, after the superhydrophobic leaves of the Nelumbo, lotus plant. A droplet striking these kinds of surfaces can fully rebound like an elastic ball. Interactions of bouncing drops can be further reduced using special superhydrophobic surfaces that promote symmetry breaking, pancake bouncing or waterbowl bouncing. Theory In 1805, Thomas Young (scientist), Thomas Young defined the contact angle ''θ'' by analysing the forces acting on a fluid droplet resting on a smooth solid surface surrounded by a gas. :\gamma_\ =\gamma_+\gamma_\cos where :\gamma_\ = Interfacial tension between the solid and gas :\gamma_\ = Interfacial tension between the solid and liquid :\gamma_\ = Interfacial tension between the li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lotus Effect
The lotus effect refers to self-cleaning properties that are a result of ultrahydrophobicity as exhibited by the leaves of ''Nelumbo'', the lotus flower. Dirt particles are picked up by water droplets due to the micro- and nanoscopic architecture on the surface, which minimizes the droplet's adhesion to that surface. Ultrahydrophobicity and self-cleaning properties are also found in other plants, such as ''Tropaeolum'' (nasturtium), ''Opuntia'' (prickly pear), ''Alchemilla'', cane, and also on the wings of certain insects. The phenomenon of ultrahydrophobicity was first studied by Dettre and Johnson in 1964 using rough hydrophobic surfaces. Their work developed a theoretical model based on experiments with glass beads coated with paraffin or Polytetrafluoroethylene, PTFE fluorotelomer, telomer. The self-cleaning property of ultrahydrophobic micro-nanotechnology, nanostructured surfaces was studied by Wilhelm Barthlott and Ehler in 1977, who described such self-cleaning and ultr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nelumbo
''Nelumbo'' is a genus of aquatic plants with large, showy flowers. Members are commonly called lotus, though the name is also applied to various other plants and plant groups, including the unrelated genus '' Lotus''. Members outwardly resemble those in the family Nymphaeaceae ("water lilies"), but ''Nelumbo'' is actually very distant from that family. ''Nelumbo'' is an ancient genus, with dozens of species known from fossil remains since the Early Cretaceous. However, there are only two known living species of lotus. One is the better-known ''Nelumbo nucifera'', which is native to East Asia, South Asia, Southeast Asia, and probably Australia and is commonly cultivated for consumption and use in traditional Chinese medicine. The other lotus is '' Nelumbo lutea'', which is native to North America and the Caribbean. Horticultural hybrids have been produced between these two allopatric species. Description Ultrahydrophobicity The leaves of ''Nelumbo'' are highly water-rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cassie's Law
Cassie's law, or the Cassie equation, describes the effective contact angle θc for a liquid on a chemically heterogeneous surface, i.e. the surface of a composite material consisting of different chemistries, that is, non-uniform throughout. Contact angles are important as they quantify a surface's wettability, the nature of solid-fluid intermolecular interactions. Cassie's law is reserved for when a liquid completely covers both ''smooth'' and ''rough'' heterogeneous surfaces. More of a rule than a law, the formula found in literature for two materials is; \cos \theta_c = \sigma_1 \cos \theta_1 + \sigma_2 \cos \theta_2 where \theta_1and \theta_2 are the contact angles for components 1 with fractional surface area \sigma_1, and 2 with fractional surface area \sigma_2 in the composite material respectively. If there exist more than two materials then the equation is scaled to the general form of; \cos \theta_ =\sum_^N \sigma_k \cos \theta_k , with \sum_^N \sigma_k = 1. Cassi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanotechnology
Nanotechnology is the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). At this scale, commonly known as the nanoscale, surface area and quantum mechanical effects become important in describing properties of matter. This definition of nanotechnology includes all types of research and technologies that deal with these special properties. It is common to see the plural form "nanotechnologies" as well as "nanoscale technologies" to refer to research and applications whose common trait is scale. An earlier understanding of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabricating macroscale products, now referred to as molecular nanotechnology. Nanotechnology defined by scale includes fields of science such as surface science, organic chemistry, molecular biology, semiconductor physics, energy storage, engineering, microfabrication, and molecular engineering. The associated rese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutting A Water Droplet Using A Superhydrophobic Knife On Superhydrophobic Surfaces
Cutting is the separation or opening of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for cutting are the knife and saw, or in medicine and science the scalpel and microtome. However, any sufficiently sharp object is capable of cutting if it has a hardness sufficiently larger than the object being cut, and if it is applied with sufficient force. Even liquids can be used to cut things when applied with sufficient force (see water jet cutter). Cutting is a compressive and shearing phenomenon, and occurs only when the total stress generated by the cutting implement exceeds the ultimate strength of the material of the object being cut. The simplest applicable equation is: :\text = or \tau=\frac The stress generated by a cutting implement is directly proportional to the force with which it is applied, and inversely proportional to the area of contact. Hence, the smaller the area (i.e., the sharper t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penguin
Penguins are a group of aquatic flightless birds from the family Spheniscidae () of the order Sphenisciformes (). They live almost exclusively in the Southern Hemisphere. Only one species, the Galápagos penguin, is equatorial, with a small portion of its population extending slightly north of the equator (within a quarter degree of latitude). Highly adapted for life in the ocean water, penguins have countershaded dark and white plumage and flippers for swimming. Most penguins feed on krill, fish, squid and other forms of sea life which they catch with their bills and swallow whole while swimming. A penguin has a spiny tongue and powerful jaws to grip slippery prey. They spend about half of their lives on land and the other half in the sea. The largest living species is the emperor penguin (''Aptenodytes forsteri''): on average, adults are about tall and weigh . The smallest penguin species is the little blue penguin (''Eudyptula minor''), also known as the fairy pen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anole
Dactyloidae are a family of lizards commonly known as anoles (singular anole ) and native to warmer parts of the Americas, ranging from southeastern United States to Paraguay. Instead of treating it as a family, some authorities prefer to treat it as a subfamily, Dactyloinae, of the family Iguanidae. In the past they were included in the family Polychrotidae together with ''Polychrus'' (bush anoles), but the latter genus is not closely related to the true anoles. Anoles are small to fairly large lizards, typically green or brownish, but their color varies depending on species and many can also change it. In most species at least the male has a dewlap, an often brightly colored flap of skin that extends from the throat and is used in displays. Anoles share several characteristics with geckos, including details of the foot structure (for climbing) and the ability to voluntarily Autotomy, break off the tail (to escape predators), but they are only very distantly related, anoles bein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gecko
Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from . Geckos are unique among lizards for their vocalisations, which differ from species to species. Most geckos in the family Gekkonidae use chirping or clicking sounds in their social interactions. Tokay geckos (''Gekko gecko'') are known for their loud mating calls, and some other species are capable of making hissing noises when alarmed or threatened. They are the most species-rich group of lizards, with about 1,500 different species worldwide. All geckos, except species in the family Eublepharidae lack eyelids; instead, the outer surface of the eyeball has a transparent membrane, the brille. They have a fixed lens within each iris that enlarges in darkness to let in more light. Since they cannot blink, species without eyelids generally lick their own brilles whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lizard
Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic islands, oceanic Archipelago, island chains. The grouping is Paraphyly, paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon. Most lizards are quadrupedal, running with a strong side-to-side motion. Some lineages (known as "legless lizards") have secondarily lost their legs, and have long snake-like bodies. Some lizards, such as the forest-dwelling ''Draco (genus), Draco'', are able to glide. They are often Territory (animal), territorial, the males fighting off other males and signalling, often with bright colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquatic Insect
Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some ''diving'' insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete. Breathing One problem that aquatic insects must overcome is how to get oxygen while they are under water. Almost all animals require a source of oxygen to live. Insects draw air into their bodies through spiracles, holes found along the sides of the abdomen. These spiracles are connected to tracheal tubes where oxygen can be absorbed. All aquatic insects have become adapted to their environment with the specialization of these structures ;Aquatic adaptations # Simple diffusion over a relatively thin integument # Temporary use of an air bubble # Extraction of oxygen from water using a plastron or blood gill # Storage of oxygen in hemoglobin and hemocyanin molecules in hemolymph # Taking oxygen from surface via brea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
