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From Wikipedia

Liquid crystal

Liquid crystals (LCs) are a state of matter that have properties between those of a conventional liquid and those of a solidcrystal. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phase, which can be distinguished by their different optical properties (such as birefringence). When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have distinct textures. The contrasting areas in the textures correspond to domains where the LC molecules are oriented in different directions. Within a domain, however, the molecules are well ordered. LC materials may not always be in an LC phase (just as water may turn into ice or steam).

Liquid crystals can be divided into thermotropic, lyotropic and metallotropic phases. Thermotropic and lyotropic LCs consist of organic molecules. Thermotropic LCs exhibit a phase transition into the LC phase as temperature is changed. Lyotropic LCs exhibit phase transitions as a function of both temperature and concentration of the LC molecules in a solvent (typically water). Metallotropic LCs are composed of both organic and inorganic molecules; their LC transition depends not only on temperature and concentration, but also on the inorganic-organic composition ratio.

Examples of liquid crystals can be found both in the natural world and in technological applications. Most modern electronic displays are liquid crystal based. Lyotropic liquid-crystalline phases are abundant in living systems. For example, many proteins and cell membranes are LCs. Other well-known LC examples are solutions of soap and various related detergents, as well as tobacco mosaic virus.

History

In 1888, Austrian botanical physiologist Friedrich Reinitzer, working at the Charles University in Prague, examined the physico-chemical properties of various derivatives of cholesterol, which are now known as cholesteric liquid crystals. Previously, other researchers had observed distinct color effects when cooling cholesterol derivatives just above the freezing point, but had not associated it with a new phenomenon. Reinitzer perceived that color changes in a derivative cholesteryl benzoate were not the most peculiar feature. He found that cholesteryl benzoate does not melt in the same manner as other compounds, but has two melting points. At 145.5|°C|°F it melts into a cloudy liquid, and at 178.5|°C|°F it melts again and the cloudy liquid becomes clear. The phenomenon is reversible. Seeking help from a physicist, on March 14, 1888, he wrote to Otto Lehmann, at that time a Privatdozent in Aachen. They exchanged letters and samples. Lehmann examined the intermediate cloudy fluid, and reported seeing crystallites. Reinitzer's Viennese colleague von Zepharovich also indicated that the intermediate "fluid" was crystalline. The exchange of letters with Lehmann ended on April 24, with many questions unanswered. Reinitzer presented his results, with credits to Lehmann and von Zepharovich, at a meeting of the Vienna Chemical Society on May 3, 1888.

By that time, Reinitzer had discovered and described three important features of cholesteric liquid crystals (the name coined by Otto Lehman in 1904): the existence of two melting points, the reflection of circularly polarized light, and the ability to rotate the polarization direction of light.

After his accidental discovery, Reinitzer did not pursue studying liquid crystals further. The research was continued by Lehmann, who realized that he had encountered a new phenomenon and was in a position to investigate it: In his postdoctoral years he had acquired expertise in crystallography and microscopy. Lehmann started a systematic study, first of cholesteryl benzoate, and then of related compounds which exhibited the double-melting phenomenon. He was able to make observations in polarized light, and his microscope was equipped with a hot stage (sample holder equipped with a heater) enabling high temperature observations. The intermediate cloudy phase clearly sustained flow, but other features, particularly the signature under a microscope, convinced Lehmann that he was dealing with a solid. By the end of August 1889 he had published his results in the Zeitschrift für Physikalische Chemie.

Lehmann's work was continued and significantly expanded by the German chemist Daniel Vorländer, who from the beginning of 20th century until his retirement in 1935, had synthesized most of the liquid crystals known. However, liquid crystals were not popular among scientists and the material remained a pure scientific curiosity for about 80 years.

In 1969, Hans Kelker succeeded in synthesizing a substance that had a nematic phase at room temperature, MBBA, which is one of the most popular subjects of liquid crystal research. The next step to commercialization of liquid crystal displays was the synthesis of further chemically stable substances (cyanobiphenyls) with low melting temperatures by globule of one substance in another, usually gas in a liquid. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance.

Common examples

Bubbles are seen in many places in everyday life, for example:

Physics and chemistry

Bubbles form, and coalesce into globular shapes, because those shapes are at a lower energy state. For the physics and chemistry behind it, see nucleation.

Appearance

Humans can see bubbles because they have a different refractive index (IR) than the surrounding substance. For example, the IR of air is approximately 1.0003 and the IR of water is approximately 1.333. Snell's Law describes how electromagnetic waves change direction at the interface between two mediums with different IR; thus bubbles can be identified from the accompanying refraction and internal reflection even though both the immersed and immersing mediums are transparent.

One should note that the above explanation only holds for bubbles of one medium submerged in another medium (e.g. bubbles of air in a soft drink); the volume of a membrane bubble (e.g. soap bubble) will not distort light very much, and one can only see a membrane bubble due to thin-film diffraction and reflection.

Applications

Nucleation can be intentionally induced, for example to create bubblegram. In medical ultrasound imaging, small encapsulated bubbles called contrast agent are used to enhance the contrast. In thermal inkjet printing, vapor bubbles are used as actuators. They are occasionally used in other microfluidics applications as actuators. The violent collapse of bubbles near solid surfaces and theresulting impinging jet constitute the mechanism used in ultrasonic cleaning. The same effect, but on a larger scale, is used in weapons such as the bazooka and the torpedo. Pistol shrimp also use the energy focusing of a collapsing cavitation bubble as a weapon. The same effect is used to treat kidney stones in a lithotripter. Marine mammals such as dolphins and whales use bubbles for entertainment or as hunting tools. Aerators cause dissolution of gas in the liquid by injecting bubbles.

Pulsation

When bubbles are disturbed, they pulsate (that is, they oscillate in size) at their natural frequency. Large bubbles (negligible surface tension and thermal conductivity) undergo adiabatic pulsations, which means that no heat is transferred either from the liquid to the gas or vice versa. The natural frequency of such bubbles is determined by the equation:

f_0 = {1 \over 2 \pi R_0}\sqrt{3 \gamma p_0 \over \rho}

where:

Smaller bubbles undergo isothermal pulsations. The corresponding equation for small bubbles of surface tension σ (and negligible liquid viscosity) is

f_0 = {1 \over 2 \pi R_0}\sqrt+{4 \sigma \over \rho R_0}}

Excited bubbles trapped underwater are the major source of liquid sounds, such as when a raindroplet impacts a surface of water.


Liquid and digits

Liquid and digits is a type of gestural, interpretive, rave and urbanstreet dance that sometimes involve aspects of pantomime. The term invokes the word liquid to describe the fluid-like motion of the dancer's body and appendages and digits to refer to illusions constructed with the dancer's fingers. Liquid dancing has many moves in common with popping and waving. The exact origins of the dances are uncertain, although they came out of either popping, raves, or both sometime from the 1970s to 1990s. The dance is typically done to a variety of electronic dance music genres from trance to drum and bass to glitch hop, depending on the dancer's musical taste.

Origins

Since the spontaneous rise and propagation of Liquid throughout the rave culture in the 1980’s and early 1990’s, the root origins of the dance have ultimately remained a source of contention between both those involved directly with the dance as well as those outside of the immediate culture. In fact, even the time frame is difficult to pinpoint. Sightings of the dance range all the way back to the early and mid 1970’s. While some argue that the dance evolved spontaneously from combining elements in the rave culture, others still contend that the dance is merely an extension of existing ideas from other art forms. Scores of these artists (Funk Stylists, Glowstickers Contact Jugglers, Mimes, & The Unknown) attended raves regularly all throughout the 1980’s and 1990’s. In the wake of the decline of the original rave scene, liquid has become a standing part of a worldwide club culture and the underground street dancing movement.

B-boys and funk stylists generally contend that liquid dancing is a development of waving, a technique in popping. Liquid dancing covers many of the same fundamentals as popping and it is fully possible (and common) for dancers to combine the styles, further blurring the distinction between the two. The defining difference is liquid dancing concentrating on smooth movements while popping is characterized by jerky pops (hits) and contractions.

In 2000, a group of liquid dancers from throughout the northeastern United States formed the Liquid Pop Collective (LPC). The name later caused some confusion since some thought the LPC did a dance called "liquid popping" but the name was chosen because many members did both liquid and popping. In Philadelphia, they began performing at events run by Reflective Multimedia, a collective of DJs and visual artists. After performing for a bit, they noticed other people in the clubs who they did not know starting to do liquid and digits. Before this, those that were interested in liquid generally knew each other. The LPC was concerned that these newcomers to the dance did not have anyone teaching them. They thought about how funk styles flourished without any direct teachers and came to the conclusion that they needed to develop a standard vocabulary for the dance. Around this time, the LPC put a video (now available [http://www.youtube.com/watch?v=vBIfCQJi32U on YouTube]) of one of the members, Eric, liquid dancing on Napster. The video spread and people wanted to learn the dance. So, the LPC decided to make an instructional video by the name of All Access Liquid and Digitz, Volume 01 (no other volumes were made) which defined the concepts that are the foundation of liquid and digits and had performances of four members. They sold about 2000 VHS tapes through their now-defunct website lpclabs.com and shipped to all over the world. The LPC has since broken up and no one is shipping the video, although it has all been uploaded [http://www.youtube.com/view_play_list?p=CC8F51A66444D195 to YouTube].

Techniques, concepts, and construction

Liquid dancers use a variety of techniques rhythmically strung together to create an illusion of continuous flow that corresponds to the music.

Hand flow

Hand flow is the most commonly used technique in Liquid dancing and simultaneously the easiest to grasp. It consists of curling the fingers of one hand and following them with the straight fingers of the opposite hand. The wrists, elbows, and shoulders may be involved to extend the motion. A Liquid dancer's personal style is defined by his or her individual approach to hand flow, and how it fits into their dance as a whole.

Rails

Rails, often a heavy focus in liquid, are characterized by the moving of the arms along a set path or "rail".

Waves

Waves maintain the illusion that a wave is passing through one's body by the isolation and alternating tensing and relaxing of one part of the body at a time at a steady speed in a constant direction.

Traces

During a trace, one's hand follows the path of a wave going through one's body. The hand moves at the same speed and in the same direction as the wave.

Contours

This technique entails the hands following exactly the outline of an object, be it real or imaginary. Most commonly the hands follow the outline of one's own body.

Threads

This style maintains the illusion that one is pulling parts of their body through holes created by the positioning of other body parts, typically arms. An example of this would be holding one's shoulder to create a closed loop which the other arm goes through. These are performed at the same speed as the flow of the liquid and waves to maintain an illusion of continuity.

Splits

This technique is characterized by the hands moving independently of each other while maintaining the illusion of a fluid relationship between each other. This is typically accomplished by misaligning the hands but using the same finger motions as regular handflow.

Builds

Builds are identified by the manipulation of imaginary objects in a manner similar to pantomime. These moves can be combined with video editing to show the imaginary object being manipulated as the person dances.

Remotes

Using one part of the body as a remote control for another is referred to as a remote. For example, pulling a hand up while simultaneously lifting a leg as if they are connected by a string is a remote.

Levers

Using one body part to create the illusion of applying a driving force to rotate another body part around a hinge. Typically done with a hand driving the opposite hand + forearm around the opposite elb

Accounting liquidity

In accounting, liquidity (or accounting liquidity) is a measure of the ability of a debtor to pay his debts as and when they fall due. It is usually expressed as a ratio or a percentage of current liabilities.

Calculating liquidity

For a corporation with a published balance sheet there are various ratios used to calculate a measure of liquidity. These include the following:

  • the current ratio, which is the simplest measure and is calculated by dividing the total current assets by the total current liabilities. A value of over 100% is normal in a non-banking corporation. However, some current assets are more difficult to sell at full value in a hurry.
  • the quick ratio - calculated by deducting inventories and prepayments from current assets and then dividing by current liabilities - gives a measure of the ability to meet current liabilities from assets that can be readily sold. A better way for a trading corporation to meet liabilities is from cash flows, rather than through asset sales, so;
  • the operating cash flow ratio can be calculated by dividing the operating cash flow by current liabilities. This indicates the ability to service current debt from current income, rather than through asset sales.

Understanding the ratios

For different industries and differing legal systems the use of differing ratios and results would be appropriate. For instance, in a country with a legal system that gives a slow or uncertain result a higher level of liquidity would be appropriate to cover the uncertainty related to the valuation of assets. A manufacturer with stable cash flows may find a lower quick ratio more appropriate than an Internet-based start up corporation.

Liquidity in banking

Liquidity is a prime concern in a banking environment and a shortage of liquidity has often been a trigger for bank failures. Holding assets in a highly liquid form tends to reduce the income from that asset (cash, for example, is the most liquid asset of all but pays no interest) so banks will try to reduce liquid assets as far as possible. However, a bank without sufficient liquidity to meet the demands of their depositors risks experiencing a bank run. The result is that most banks now try to forecast their liquidity requirements and maintain emergency standby credit lines at other banks. Banking regulators also view liquidity as a major concern.



From Encyclopedia

liquid

liquid one of the three commonly recognized states in which matter occurs, i.e., that state, as distinguished from solid and gas, in which a substance has a definite volume but no definite shape. Properties of Liquids In general, liquids show expansion on heating, contraction on cooling; water, however, does not follow the rule exactly. A liquid changes at its boiling point to a gas and at its freezing point, or melting point , to a solid. The boiling point is especially important because, since liquids change their states at different temperatures, those in a mixture can be separated from one another by raising the temperature of the mixture gradually so that each component in turn undergoes vaporization at its boiling point. This process is known as fractional distillation. Liquids, like gases, exhibit the property of diffusion. When two miscible liquids (i.e., they mix without separation) are poured carefully into a container so that the denser one forms a separate layer on the bottom, each will diffuse slowly into the other until they are thoroughly mixed. Liquids, like gases, differ from solids in that they are fluids, that is, they flow into the shape of a containing vessel. Liquids exert pressure on the sides of a containing vessel and on any body immersed in them, and pressure is transmitted through a liquid undiminished and in all directions. Liquids exert a buoyant force on an immersed body equal to the weight of the liquid displaced by the body (see Archimedes' principle and specific gravity ). Unlike gases, liquids are very nearly incompressible, and for that reason are useful in such devices as the hydraulic press. Liquids are useful as solvents. No one liquid can dissolve all substances; each takes into solution only certain specific substances. Molecular Structure of Liquids The molecules (or atoms or ions) of a liquid, like those of a solid (and unlike those of a gas), are quite close together; however, while molecules in a solid are held in fixed positions by intermolecular forces, molecules in a liquid have too much thermal energy to be bound by these forces and move about freely within the liquid, although they cannot escape the liquid easily. Although the molecules of a liquid have greater cohesion than those of a gas, it is not sufficient to prevent some of those at the free surface of the liquid from bounding off (see evaporation ). On the other hand, the cohesive forces between the molecules at the surface of a mass of liquid and those within cause the free surface to act somewhat like a stretched elastic membrane; it tends to draw inward toward the center of the liquid mass, to draw the liquid into the shape of a sphere, thus exhibiting the phenomenon known as surface tension . A liquid is said to "wet" a solid substance when the attractive force between the molecules of the liquid and those of the solid is great enough to hold the liquid's molecules at the solid surface. For example, water "wets" glass since its molecules cling to glass surfaces, whereas mercury does not since the adhesive force between its molecules and those of glass is not strong enough to hold them together. Capillarity is an example of surface tension and adhesion acting at the same time.


From Yahoo Answers

Question:What is a liquid-liquid solution and what is an example of one that can be separated by distillation?

Answers:You can distill acetone from water. Water boils at 100 degrees C, while acetone is around 50. So by heating the solution to around acetone's boiling point, the acetone will evaporate, while (most of) the water will remain in the initial solution.

Question:something that is commonly found, like a household item would be good :) Thanks so much! it must be a household item, thanks so much :) and let me add to that, after seeing a milli's answer, i have to be able to bring it into school haha.

Answers:White vinegar consists of about 6% acetic acid in water which can be separated by distillation in the hands of an expert. Vodka, a mixture of roughly 50% ethyl alcohol in water, is more easily separated by distillation into 95% alcohol and water.

Question:

Answers:Gasoline contains 3 or 4 different Hydrocarbon Liquids in solution.

Question:Which term refers to a solute that cannot be dissolved in a particular solvent? a) insoluble b) immiscible c) homogenous Soda water is an example of: a) a liquid solution b) a solid solution c) a gaseous solution Ocean water is: a) a liquid solution b) an aqueous solution c) both a liquid and aqueous solution

Answers:a) a) c)

From Youtube

LIQUID SOLUTION :What do you do with an unquenchable thirst paired with an essential deadline? Find a liquid solution! Strap in and laugh hard as the epic mayhem unfolds for Paul, the unfortunate soul who is forced to work his way through unimaginable obstacles to get the one thing he needs most. This hilarious shortfilm is the Liquid Solution for your thirsty eyes! For more, visit www.myspace.com/LightspeedProductions

Liquid Solutions :This General Chemistry lecture covers ideal solutions of solvents and solutes and Raoults Law of vapor pressures for ideal solutions. We discuss the Gibbs Free Energy of solutions, and how this leads to colligative properties of freezing point depression, boiling point elevation, and osmotic pressure.