In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water.
Salvinia molesta, commonly known as giant salvinia, or as kariba weed after it infested a large portion of Lake Kariba between Zimbabwe and Zambia, is an aquatic fern, native to south-eastern Brazil. It is a free-floating plant that does not attach to the soil, but instead remains buoyant on the surface of a body of water. The fronds are 0.5–4 cm long and broad, with a bristly surface caused by the hair-like strands that join at the end to form eggbeater shapes. They are used to provide a waterproof covering. These fronds are produced in pairs also with a third modified root-like frond that hangs in the water. It has been accidentally introduced or escaped to countless lakes throughout the United States, including Caddo Lake in Texas, where the invasive species has done extensive damage, killing off other life.
Salvinia, a genus in the family Salviniaceae, is a floating fern named in honor of Anton Maria Salvini, a 17th-century Italian scientist. Watermoss is a common name for Salvinia. The genus was published in 1754 by Jean-François Séguier, in his description of the plants found round Verona, Plantae Veronenses Twelve species are recognized, at least three of which are believed to be hybrids, in part because their sporangia are found to be empty.
The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in an aqueous solution and exclude water molecules. The word hydrophobic literally means "water-fearing", and it describes the segregation of water and nonpolar substances, which maximizes hydrogen bonding between molecules of water and minimizes the area of contact between water and nonpolar molecules. In terms of thermodynamics, the hydrophobic effect is the free energy change of water surrounding a solute. A positive free energy change of the surrounding solvent indicates hydrophobicity, whereas a negative free energy change implies hydrophilicity.
Superhydrophilicity refers to the phenomenon of excess hydrophilicity, or attraction to water; in superhydrophilic materials, the contact angle of water is equal to zero degrees. This effect was discovered in 1995 by the Research Institute of Toto Ltd. for titanium dioxide irradiated by sunlight. Under light irradiation, water dropped onto titanium dioxide forms no contact angle.
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, Alchemilla, cane, and also on the wings of certain insects.
In chemistry and materials science, ultrahydrophobic surfaces are highly hydrophobic, i.e., extremely difficult to 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 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.
A plant cuticle is a protecting film covering the outermost skin layer (epidermis) of leaves, young shoots and other aerial plant organs that have no periderm. The film consists of lipid and hydrocarbon polymers infused with wax, and is synthesized exclusively by the epidermal cells.
Notonecta glauca is a species of aquatic insect, and a type of backswimmer. This species is found in large parts of Europe, North Africa, and east through Asia to Siberia and China. In much of its range it is the most common backswimmer species. It is also the most widespread and abundant of the four British backswimmers. Notonecta glauca are Hemiptera predators, that are approximately 13–16 mm in length. Females have a larger body size compared to males. These water insects swim and rest on their back and are found under the water surface. Notonecta glauca supports itself under the water surface by using their front legs and mid legs and the back end of its abdomen and rest them on the water surface; They are able to stay under the water surface by water tension, also known as the air-water interface. They use the hind legs as oars; these legs are fringed with hair and, when at rest, are extended laterally like a pair of sculls in a boat. Notonecta glauca will either wait for its prey to pass by or will swim and actively hunt its prey. When the weather is warm, usually in the late summer and autumn, they will fly between ponds. Notonecta glauca reproduce in the spring.
Membrane fouling is a process whereby a solution or a particle is deposited on a membrane surface or in membrane pores in a processes such as in a membrane bioreactor, reverse osmosis, forward osmosis, membrane distillation, ultrafiltration, microfiltration, or nanofiltration so that the membrane's performance is degraded. It is a major obstacle to the widespread use of this technology. Membrane fouling can cause severe flux decline and affect the quality of the water produced. Severe fouling may require intense chemical cleaning or membrane replacement. This increases the operating costs of a treatment plant. There are various types of foulants: colloidal, biological, organic and scaling.
Wilhelm Barthlott is a German botanist and biomimetic materials scientist. His official botanical author citation is Barthlott.
Direct bonding, or fusion bonding, describes a wafer bonding process without any additional intermediate layers. The bonding process is based on chemical bonds between two surfaces of any material possible meeting numerous requirements. These requirements are specified for the wafer surface as sufficiently clean, flat and smooth. Otherwise unbonded areas so called voids, i.e. interface bubbles, can occur.
Samea multiplicalis, the salvinia stem-borer moth, is an aquatic moth commonly found in freshwater habitats from the southern United States to Argentina, as well as in Australia where it was introduced in 1981. Salvinia stem-borer moths lay their eggs on water plants like Azolla caroliniana, Pistia stratiotes, and Salvinia rotundifolia. Larval feeding on host plants causes plant death, which makes S. multiplicalis a good candidate for biological control of weedy water plants like Salvinia molesta, an invasive water fern in Australia. However, high rates of parasitism in the moth compromise its ability to effectively control water weeds. S. multiplicalis larvae are a pale yellow to green color, and adults develop tan coloration with darker patterning. The lifespan, from egg to the end of adulthood is typically three to four weeks. The species was first described by Achille Guenée in 1854.
Salvinia minima is a species of aquatic, floating fern that grows on the surface of still waterways. It is usually referred to as common salvinia or water spangles. Salvinia minima is native to South America, Mesoamerica, and the West Indies and was introduced to the United States in the 1920s-1930s. It is classified as an invasive species internationally and can be detrimental to native ecosystems. This species is similar to but should not be confused with giant salvinia, Salvinia molesta.
A superhydrophobic coating is a thin surface layer that repels water. It is made from superhydrophobic (ultrahydrophobicity) materials. Droplets hitting this kind of coating can fully rebound. Generally speaking, superhydrophobic coatings are made from composite materials where one component provides the roughness and the other provides low surface energy.
The surface chemistry of paper is responsible for many important paper properties, such as gloss, waterproofing, and printability. Many components are used in the paper-making process that affect the surface.
Icephobicity is the ability of a solid surface to repel ice or prevent ice formation due to a certain topographical structure of the surface. The word “icephobic” was used for the first time at least in 1950; however, the progress in micropatterned surfaces resulted in growing interest towards icephobicity since the 2000s.
Surface tension is one of the areas of interest in biomimetics research. Surface tension forces will only begin to dominate gravitational forces below length scales on the order of the fluid's capillary length, which for water is about 2 millimeters. Because of this scaling, biomimetic devices that utilize surface tension will generally be very small, however there are many ways in which such devices could be used.
Self-cleaning surfaces are a class of materials with the inherent ability to remove any debris or bacteria from their surfaces in a variety of ways. The self-cleaning functionality of these surfaces are commonly inspired by natural phenomena observed in lotus leaves, gecko feet, and water striders to name a few. The majority of self-cleaning surfaces can be placed into three categories:
- superhydrophobic
- superhydrophilic
- photocatalytic.
Bioinspiration is the development of novel materials, devices, and structures inspired by solutions found in biological evolution and refinement which has occurred over millions of years. The goal is to improve modeling and simulation of the biological system to attain a better understanding of nature's critical structural features, such as a wing, for use in future bioinspired designs. Bioinspiration differs from biomimicry in that the latter aims to precisely replicate the designs of biological materials. Bioinspired research is a return to the classical origins of science: it is a field based on observing the remarkable functions that characterize living organisms and trying to abstract and imitate those functions.
