News tagged with colloids
The butterfly effect in nanotech medical diagnostics
Tiny metallic nanoparticles that shimmer in the light like the scales on a butterfly's wing are set to become the color-change components of a revolutionary new approach to point-of-care medical diagnostics, according to ...
Nanotechnology / Bio & Medicine
Feb 06, 2012 |
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Cosmology in a Petri dish
Scientists have found that micron-size particles which are trapped at fluid interfaces exhibit a collective dynamic that is subject to seemingly unrelated governing laws. These laws show a smooth transitioning ...
Jan 26, 2012 |
4 / 5 (7) |
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Anti-malaria drug synthesized with the help of oxygen and light
The most effective anti-malaria drug can now be produced inexpensively and in large quantities. This means that it will be possible to provide medication for the 225 million malaria patients in developing ...
Jan 17, 2012 |
5 / 5 (5) |
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Engineer guest authors PNAS commentary on directing colloidal assembly
The University of Delaware's Eric M. Furst authored a commentary in the Proceedings of the National Academy of Sciences (PNAS) advance online edition Dec. 19.
Dec 22, 2011 |
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Plant with 'eggbeater' testure inspires waterproof coating
A floating weed that clogs waterways around the world has at least one redeeming feature: It's inspired a high-tech waterproof coating intended for boats and submarines.
Nanotechnology / Nanomaterials
Nov 10, 2011 |
4.8 / 5 (5) |
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How to count nanoparticles
Nanoparticles of a substance can be counted and the size distribution can be determined by dispersing the nanoparticles into a gas. But some nanoparticles tend to aggregate when the surrounding conditions change. Scientists ...
Nanotechnology / Bio & Medicine
Oct 11, 2011 |
4 / 5 (1) |
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First opal-like crystals discovered in meteorite
Scientists have found opal-like crystals in the Tagish Lake meteorite, which fell to Earth in Canada in 2000. This is the first extraterrestrial discovery of these unusual crystals, which may have formed in the primordial ...
Aug 03, 2011 |
5 / 5 (6) |
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Origami in seed capsules
(PhysOrg.com) -- A number of plants disperse their seeds in a rather artistic way: the seed capsules of the ice plant Delosperma nakurense, for instance, unfold lids over the seed compartments in the manner ...
Jun 21, 2011 |
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Making complex fluids look simple
An international research team has successfully developed a widely applicable method for discovering the physical foundations of complex fluids for the first time. Researchers at the University of Vienna and ...
Jun 01, 2011 |
4.3 / 5 (3) |
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A sweet defense against lethal bacteria
(PhysOrg.com) -- There is now a promising vaccine candidate for combating the pathogen which causes one of the most common and dangerous hospital infections. An international team of scientists from the Max ...
May 31, 2011 |
3.8 / 5 (4) |
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Osmosis in colloidal suspensions
(PhysOrg.com) -- It is very difficult to overestimate the importance of colloidal suspensions. Besides being an integral part of our everyday life (food, cosmetics, drugs), they also serve as an excellent ...
May 18, 2011 |
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C60 could form a new kind of gel
(PhysOrg.com) -- C60, the spherical carbon molecule also known as a buckminsterfullerene, has intrigued scientists for its unique properties and potential applications in nanotechnology and electronics. Now scient ...
Nanotechnology / Nanomaterials
Feb 17, 2011 |
4.1 / 5 (9) |
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Nanosilver: A new name -- well-known effects
Nanosilver is not a new discovery by nanotechnologists -- it has been used in various products for over a hundred years, as is shown by a new Empa study. The antimicrobial effects of minute silver particles, which were then ...
Nanotechnology / Nanomaterials
Jan 31, 2011 |
5 / 5 (2) |
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Triblock spheres provide a simple path to complex structures
University of Illinois materials scientists have developed a simple, generalizable technique to fabricate complex structures that assemble themselves.
Jan 19, 2011 |
4.7 / 5 (7) |
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Turning over a new leaf
(PhysOrg.com) -- German researchers have transformed the skeleton of a leaf into iron carbide. The new technique enables the conversion of metal carbides into intricate microstructures in just one step.
Sep 20, 2010 |
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Colloid
A colloid is a type of chemical mixture where one substance is dispersed evenly throughout another. The particles of the dispersed substance are only suspended in the mixture, unlike a solution, where they are completely dissolved within. This occurs because the particles in a colloid are larger than in a solution - small enough to be dispersed evenly and maintain a homogenous appearance, but large enough to scatter light and not dissolve. Because of this dispersal, some colloids have the appearance of solutions. A colloidal system consists of two separate phases: a dispersed phase (or internal phase) and a continuous phase (or dispersion medium). A colloidal system may be solid, liquid, or gaseous.
Many familiar substances are colloids, as shown in the chart below. As well as these naturally occurring colloids, modern chemical process industries utilise high shear mixing technology to create novel colloids.
The subsequent table compares particle(s) diameters of colloids, homogeneous and heterogeneous mixture:
Thus, colloid suspensions are intermediate between homogeneous and heterogeneous mixtures. They are sometimes classified as either "homogeneous" or "heterogeneous" based upon their appearance.
The dispersed-phase particles have a diameter of between approximately 5 and 200 nanometers. Such particles are normally invisible to an optical microscope, though their presence can be confirmed with the use of an ultramicroscope or an electron microscope. Homogeneous mixtures with a dispersed phase in this size range may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions, or hydrosols. The dispersed-phase particles or droplets are largely affected by the surface chemistry present in the colloid.
Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color.
Colloidal systems (also called colloidal solutions or colloidal suspensions) are the subject of interface and colloid science. This field of study was introduced in 1861 by Scottish scientist Thomas Graham.
For more information about Colloid, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
