IdeaWazaWiki - User contributions [en]

Russian/Greetings

2008-01-30T13:26:00Z

75.45.172.117:

Приве'т! [prǐvēǐt] = Алло [Ǎllō] = Hello!(familiar with person, over phone)

Здраствуйте! [Zdrǎstvūǐtīē] = Hello! (just met the person, formal way of speaking, greeting a superior)

Пока'! [pǒǔk] = Bye!(familiar with person, over phone)

До свидания [Dǒ svǐdǒnīyŏ] = Good Bye! (formal way of speaking, parting with a superior)

Как дела'? [kǎk dǐlǔ] = How are you?

Хорошо' [kharǎshō] = Fine

Как вас зову'т? [kǎk vǒs zǎvūt] = What is your name?

Меня' зову'т... [mǐnyǒ zǎvūt] = My name is ...

[[Category:Russian]]

[[fr:Se présenter/Russe]]

Precipitation (chemistry)

2007-10-10T20:40:08Z

75.45.240.203: poop

'''Precipitation''' is the formation of a [[solid]] in a [[solution]] during a [[chemical reaction]]. When the chemical reaction occurs the solid formed is called the '''precipitate'''. This can occur when an insoluble substance, the '''precipitate''', is formed in the solution due to a reaction or when the solution has been ''supersaturated'' by a compound. The formation of a precipitate is a sign of a chemical change. In most situations, the solid forms ("falls") out of the solute phase, and sinks to the bottom of the solution (though it will float if it is less dense than the solvent, or form a [[suspension (chemistry)|suspension]]).

==Uses==

Precipitation reactions can be used for making pigments, removing salts from water in water treatment, and for qualitative chemical analysis.

This effect is useful in many industrial and scientific applications whereby a chemical reaction may produce a solid that can be collected from the solution by various methods (e.g. filtration, decanting, centrifuging). Precipitation from a [[solid solution]] is also a useful way to [[precipitation strengthening|strengthen]] [[alloy]]s; this process is known as [[solid solution strengthening]].

==Mechanism==

An important stage of the precipitation process is the onset of [[nucleation]]. The creation of a hypothetical solid particle includes the formation of an interface, which requires some energy based on the relative [[surface energy]] of the solid and the solution. If this energy is not available, and no suitable nucleation surface is available, [[supersaturation]] occurs.

==Representation using chemical equations==

An example of a precipitation reaction: Aqueous silver nitrate (AgNO3) is added to a solution containing potassium chloride (KCl) and the precipitation of a white solid, silver chloride is observed. (Zumdahl, 2005)

:AgNO3(aq) + KCl(aq) → AgCl(s) + KNO3(aq)

The silver chloride(AgCl) has formed a solid, which is observed as a precipitate.

This reaction can be written emphasizing the dissociated ions in a combined solution
:Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq) → AgCl(solid) + K+(aq) + NO3-(aq)

A final way to represent a precipitate reaction is known as a ''net ionic reaction''. In this case, any spectator ions (those which do not contribute to the reaction) are left out of the formula completely. This simplifies the above equations to the following:
:Ag+(aq) + Cl-(aq) → AgCl(s)

==Cation sensitivity==
Precipitate formation is useful in the detection of the type of [[cation]] in [[salt]]. To do this, an [[alkali]] first reacts with the unknown salt to produce a precipitate which is the hydroxide of the unknown salt.

To identify the cation, the colour of the precipitate and its solubility in excess are noted.

Similar processes are often used to separate chemically similar elements, such as the [[Rare earth element|rare earth]] metals.

==Digestion==

Digestion, or ''precipitate ageing'', happens when a freshly-formed precipitate is left, usually at a higher temperature, in the solution from which it is precipitated. It results in cleaner and bigger particles.<ref>[http://www.ktf-split.hr/glossary/en_o.php?def=digestion Chemical dictionary definition.]</ref>

==References==
*Zumdahl, Steven S. ''Chemical Principles.'' 4th ed. New York: Houghton Mifflin Company, 2005.
*Mark Smith ''Principles of Science'' 1993

<references/>

==Further reading==
*Banert, T., Brenner, G., Peuker, U. A. (2006), Operating parameters of a continuous sono-chemical precipitation reactor, Proc. 5. WCPT, Orlando Fl., 23.-27. April 2006.

==External links==
* [http://www.hci.edu.sg/~limth/lessons/2002/qa/cations.htm Test for Cations]
* [http://www.hielscher.com/ultrasonics/precipitation_01.htm Continuous Precipitation Using Ultrasonication (e.g. for nano-size magnetite particles)]

[[Category:Chemical processes]]

[[da:Fældningsreaktion]]
[[de:Fällungsreaktion]]
[[es:Precipitado]]
[[fr:Précipité]]
[[he:תגובת שיקוע]]
[[it:Precipitazione (chimica)]]
[[nl:Neerslag (scheikunde)]]
[[ja:沈殿]]
[[no:Fellingsreaksjon]]
[[nn:Fellingsreaksjon]]
[[pt:Precipitação (química)]]
[[ru:Преципитат (химия)]]
[[su:Présipitasi]]
[[sv:Utfällning]]
[[zh:沉淀]]
poop

Archive:Total parenteral nutrition

2007-04-17T07:46:55Z

75.45.236.188: /* External links */

'''Total parenteral nutrition''' (TPN), is the practice of feeding a person intravenously, circumventing the [[gut]].

==General Usage==

TPN is normally used following surgery, when feeding by mouth or using the gut is not possible, when a person's digestive system cannot absorb nutrients due to [[chronic (medicine)|chronic disease]], or, alternatively, if a person's nutrient requirement cannot be met by [[enteral feeding]] (tube feeding) and supplementation. It has been used for [[Coma|comatose]] patients, although enteral feeding is usually preferable, and less prone to complications. Short-term TPN may be used if a person's digestive system has shut down (for instance by [[Peritonitis]]), and they are at a low enough weight to cause concerns about nutrition during an extended hospital stay. Long-term TPN is occasionally used to treat people suffering the extended consequences of an accident or surgery. Most controversially, TPN has extended the life of a small number of children born with nonexistent or severely birth-deformed guts. The oldest were eight years old in [[2003]].

The preferred method of delivering TPN is with a medical [[infusion pump]]. A [[sterilization (microbiology)|sterile]] bag of nutrient solution, between 500 mL and 4 L is provided. The pump infuses a small amount (0.1 to 10 mL/hr) continuously in order to keep the vein open. Feeding schedules vary, but one common regimen ramps up the nutrition over a few hours, levels off the rate for a few hours, and then ramps it down over a few more hours, in order to simulate a normal set of meal times.

The nutrient solution consists of [[water]], [[glucose]], [[salt]]s, [[amino acid]]s, [[vitamin]]s and (more controversially) sometimes emulsified [[fat]]s. Long term TPN patients sometimes suffer from lack of trace nutrients or [[electrolyte]] imbalances. Because increased [[blood sugar]] commonly occurs with TPN, [[insulin]] may also be added to the infusion. Occasionally, other drugs are added as well.

Chronic TPN is performed through a [[Hickman line]] or a [[Port-a-Cath]] (venous access systems). In infants, sometimes the [[umbilical artery]] is used.

Battery-powered ambulatory infusion pumps are used with chronic TPN patients, and usually the pump and a small (100 ml) bag of nutrient to keep the vein open are carried in a fanny pack. Outpatient TPN practices are still being refined.

Aside from their dependence on a pump, chronic TPN patients live quite normal lives.

==Complications==

The most common complication of TPN use is bacterial infection, usually due to the increased infection risk from having an indwelling [[central venous catheter]]. [[Liver]] [[Liver failure|failure]] may sometimes occur; a recent study at Children's Hospital Boston on the cause suggests it is due to a large difference in omega-6 to omega-3 ratio. When treated with a different fatty acid infusion (which is not approved for use in the U.S.) two patients were able to recover from their condition.<ref>[http://pediatrics.aappublications.org/cgi/content/full/118/1/e197?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=parenteral+nutrition&searchid=1&FIRSTINDEX=0&volume=118&issue=1&resourcetype=HWCIT| PEDIATRICS Vol. 118 No. 1 July 2006 p e197-e201]</ref>

For more information, please refer to this paper in the journal ''Pediatrics''.
Kathleen M. Gura, Christopher P. Duggan, Sharon B. Collier, Russell W. Jennings, Judah Folkman, Bruce R. Bistrian and Mark Puder. "Management Short Bowel Syndrome Using Parenteral Fish Oil: Implications for Future
Reversal of Parenteral Nutrition–Associated Liver Disease in Two Infants With Short Bowel Syndrome"
Pediatrics 2006;118;197-201

==See also==
* [[Intravenous drip]]

==References==
<div class="references-small" style="-moz-column-count:2; column-count:2;">
<references /></div>

== External links ==

*[http://www.heinrick.com/ryan/tpn.cfm TPN/PPN Calculator] by Ryan Heinrick
*[http://www.childrenshospital.org/newsroom/Site1339/mainpageS1339P1sublevel222.html "Why does prolonged TPN cause liver damage in infants?"], Children's Hospital Boston
*[http://blogs.nutrishare.com TPN Blogs] on [http://www.Nutrishare.com Nutrishare] (a Home TPN provider)
*[http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601166.html TPN Drug Information] from MedlinePlus NIH Database
*[http://worldhealthlibrary.com/uncategorized/tpn-site-care/ TPN Care] from the World Health Library
[[Category:nutrition]]
[[Category:intensive care medicine]]

[[de:Parenterale Ernährung]]
[[nl:Parenterale voeding]]
[[ja:高カロリー輸液]]
[[pt:Nutrição parenteral]]