|
Nanofiber
Nanofibers are fibers with diameters in the Nanometre, nanometer range (typically, between 1 nm and 1 μm). Nanofibers can be generated from different polymers and hence have different physical properties and application potentials. Examples of natural polymers include collagen, cellulose, silk fibroin, keratin, gelatin and polysaccharides such as chitosan and alginate. Examples of synthetic polymers include poly(lactic acid) (PLA), polycaprolactone (PCL), polyurethane (PU), poly(lactic-co-glycolic acid) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and Ethylene-vinyl acetate, poly(ethylene-co-vinylacetate) (PEVA). Polymer chains are connected via covalent bonds. The diameters of nanofibers depend on the type of polymer used and the method of production. All polymer nanofibers are unique for their large surface area-to-volume ratio, high porosity, appreciable mechanical strength, and flexibility in functionalization compared to their microfiber counterparts. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrospinning Image For Wikipedia
Electrospinning is a fiber production method that uses electrical force (based on electrohydrodynamic principles) to draw charged threads of polymer solutions for producing nanofibers with diameters ranging from nanometers to micrometers. Electrospinning shares characteristics of both electrospraying and conventional solution dry spinning of fibers.Ziabicki, A. (1976) ''Fundamentals of fiber formation'', John Wiley and Sons, London, . The process does not require the use of coagulation chemistry or high temperatures to produce solid threads from solution. This makes the process particularly suited to the production of fibers using large and complex molecules. Electrospinning from molten precursors is also practiced; this method ensures that no solvent can be carried over into the final product. Process When a sufficiently high voltage is applied to a liquid droplet, the body of the liquid becomes charged, and electrostatic repulsion counteracts the surface tension and the dro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrospinning
Electrospinning is a fiber production method that uses Electrostatics, electrical force (based on electrohydrodynamic principles) to draw charged threads of polymer solutions for producing nanofibers with diameters ranging from nanometers to micrometers. Electrospinning shares characteristics of both electrospraying and conventional solution spinning (polymers)#Dry spinning, dry spinning of fibers.Ziabicki, A. (1976) ''Fundamentals of fiber formation'', John Wiley and Sons, London, . The process does not require the use of coagulation chemistry or high temperatures to produce solid threads from solution. This makes the process particularly suited to the production of fibers using large and complex molecules. Electrospinning from molten precursors is also practiced; this method ensures that no solvent can be carried over into the final product. Process When a sufficiently high voltage is applied to a liquid droplet, the body of the liquid becomes charged, and electrostatic repuls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellulose Nanofiber Network
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%. Cellulose is mainly used to produce paperboard and paper. Smaller quantities are converted into a wide variety of derivative products such as cellophane and rayon. Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol is under development as a renewable fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton. Cellulose is also greatly affected by direct interaction with several organic liquids. Som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Covalent Bonds
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding. Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term "covalence" was introduced by Irving Langmuir in 1919, with Nevil Sidgwick using "co-valent link" in the 1920s. Merriam-Webster dates the specific phrase ''covalent bond'' to 1939, recognizing its first known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Vernon Boys
Sir Charles Vernon Boys, FRS (15 March 1855 – 30 March 1944) was a British physicist, known for his careful and innovative experimental work in the fields of thermodynamics and high-speed photography, and as a popular science communicator through his books, inventions, and his public lectures for children. Early life Boys was the eighth child of the Reverend Charles Boys, the Anglican vicar of Wing, Rutland. He was educated at Marlborough College and the Royal School of Mines, where he learned physics from Frederick Guthrie and taught himself higher mathematics while completing a degree in mining and metallurgy. As a student at the School of Mines he invented a mechanical device (which he called the "integraph") for plotting the integral of a function. He worked briefly in the coal industry before accepting Guthrie's offer of a position as "demonstrator." Experimental physics Boys achieved recognition as a scientist for his invention of the fused quartz fibre torsion b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrostatic Force
Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that calculates the amount of force between two electrically charged particles at rest. This electric force is conventionally called the ''electrostatic force'' or Coulomb force. Although the law was known earlier, it was first published in 1785 by French physicist Charles-Augustin de Coulomb. Coulomb's law was essential to the development of the theory of electromagnetism and maybe even its starting point, as it allowed meaningful discussions of the amount of electric charge in a particle. The law states that the magnitude, or absolute value, of the attractive or repulsive electrostatic force between two point charges is directly proportional to the product of the magnitudes of their charges and inversely proportional to the square of the distance between them. Coulomb discovered that bodies with like electrical charges repel: Coulomb also showed that oppositely charged bodies attract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension (physics), tension is what allows objects with a higher density than water such as razor blades and insects (e.g. Gerridae, water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to Cohesion (chemistry), cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This ''tangential'' force is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Types Of Equilibrium
This is a list presents the various articles at Wikipedia that use the term equilibrium (or an associated prefix or derivative) in their titles or leads. It is not necessarily complete; further examples may be found by using the Wikipedia search function, and this term. Biology * Equilibrioception, the sense of a balance present in human beings and animals * Equilibrium unfolding, the process of unfolding a protein or RNA molecule by gradually changing its environment * Genetic equilibrium, theoretical state in which a population is not evolving * Homeostasis, the ability of an open system, especially living organisms, to regulate its internal environment * Punctuated equilibrium, theory in evolutionary biology * Sedimentation equilibrium, analytical ultracentrifugation method for measuring protein molecular masses in solution * Equilibrium Theory ( Island biogeography), MacArthur-Wilson theory explaining biodiversity character of ecological islands * Osmotic equilibrium, ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John William Strutt, 3rd Baron Rayleigh
John William Strutt, 3rd Baron Rayleigh ( ; 12 November 1842 – 30 June 1919), was an English physicist who received the Nobel Prize in Physics in 1904 "for his investigations of the densities of the most important gases and for his discovery of argon in connection with these studies". He served as president of the Royal Society from 1905 to 1908 and as chancellor of the University of Cambridge from 1908 to 1919. Rayleigh provided the first theoretical treatment of the elastic scattering of light by particles much smaller than the light's wavelength, a phenomenon now known as "Rayleigh scattering", which notably explains why the sky is blue. He studied and described transverse surface waves in solids, now known as "Rayleigh waves". He contributed extensively to fluid dynamics, with concepts such as the Rayleigh number (a dimensionless number associated with natural convection), Rayleigh flow, the Rayleigh–Taylor instability, and Rayleigh's criterion for the stability of Ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taylor Cone
A Taylor cone refers to the cone observed in electrospinning, electrospraying and hydrodynamic spray processes from which a jet of charged particles emanates above a threshold voltage. Aside from electrospray ionization in mass spectrometry, the Taylor cone is important in field-emission electric propulsion (FEEP) and colloid thrusters used in fine control and high efficiency (low power) thrust of spacecraft. History This cone was described by Sir Geoffrey Ingram Taylor in 1964 before electrospray was "discovered". This work followed on the work of Zeleny who photographed a cone-jet of glycerine in a strong electric field and the work of several others: Wilson and Taylor (1925), Nolan (1926) and Macky (1931). Taylor was primarily interested in the behavior of water droplets in strong electric fields, such as in thunderstorms. Formation When a small volume of electrically conductive liquid is exposed to an electric field, the shape of liquid starts to deform from the shape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrostatic Attraction
Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that calculates the amount of force between two electrically charged particles at rest. This electric force is conventionally called the ''electrostatic force'' or Coulomb force. Although the law was known earlier, it was first published in 1785 by French physicist Charles-Augustin de Coulomb. Coulomb's law was essential to the development of the theory of electromagnetism and maybe even its starting point, as it allowed meaningful discussions of the amount of electric charge in a particle. The law states that the magnitude, or absolute value, of the attractive or repulsive electrostatic force between two point charges is directly proportional to the product of the magnitudes of their charges and inversely proportional to the square of the distance between them. Coulomb discovered that bodies with like electrical charges repel: Coulomb also showed that oppositely charged bodies attract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Gilbert (astronomer)
William Gilbert (; 24 May 1544? – 30 November 1603), also known as Gilberd, was an English physician, physicist and natural philosophy, natural philosopher. He passionately rejected both the prevailing Aristotelian philosophy and the Scholasticism, Scholastic method of university teaching. He is remembered today largely for his book ''De Magnete'' (1600). A unit of magnetomotive force, also known as magnetic scalar potential, magnetic potential, was named the ''Gilbert (unit), Gilbert'' in his honour; it has now been superseded by the Ampere-turn. Life and work Gilbert was born in Colchester to Jerome Gilberd, a borough Recorder (judge), recorder. He was educated at St John's College, Cambridge. After gaining his Doctor of Medicine, MD from Cambridge in 1569, and a short spell as bursar of St John's College, he left to practice medicine in London, and he travelled on the continent. In 1573, he was elected a Fellow of the Royal College of Physicians. In 1600, he was elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
