WordNet

name or recite the numbers in ascending order; "The toddler could count to 100"
the total number counted; "a blood count"
the act of counting; reciting numbers in ascending order; "the counting continued for several hours" (同)counting, numeration, enumeration, reckoning, tally
a nobleman (in various countries) having rank equal to a British earl
have faith or confidence in; "you can count on me to help you any time"; "Look to your friends for support"; "You can bet on that!"; "Depend on your family in times of crisis" (同)bet, depend, look, calculate, reckon
have weight; have import, carry weight; "It does not matter much" (同)matter, weigh
put into a group; "The academy counts several Nobel Prize winners among its members" (同)number
determine the number or amount of; "Can you count the books on your shelf?"; "Count your change" (同)number, enumerate, numerate
have a certain value or carry a certain weight; "each answer counts as three points"
include as if by counting; "I can count my colleagues in the opposition"
speak in response; "He countered with some very persuasive arguments"
a piece of leather forming the back of a shoe or boot; "a counter may be used to stiffen the material around the heel and to give support to the foot" (同)heel counter
a calculator that keeps a record of the number of times something happens (同)tabulator
(computer science) a register whose contents go through a regular series of states (usually states indicating consecutive integers)
game equipment (as a piece of wood, plastic, or ivory) used for keeping a count or reserving a space in various card or board games
table consisting of a horizontal surface over which business is transacted
a person who counts things
in the opposite direction; "run counter"
a particle that is electrically charged (positive or negative); an atom or molecule or group that has lost or gained one or more electrons

PrepTutorEJDIC

(一つ一つ順に)〈数〉'を'『数える』,〈物〉'を'数え上げる《+『up』+『名,』+『名』+『up』》 / …'を'『勘定に入れる』,含める(include) / …'を'『思う』,みなす(consider) / 数を数える,計算する《+『up』》 / 数にはいる,数に含まれる / 価値がある,重大である / 〈C〉〈U〉『数えること』,『計算』 / 〈U〉総数,総計 / 〈U〉(起訴状の)訴因 / 《the~》(ボクシングで)カウント(選手がノックダウンされたときレフリーが1から10まで数えること) / 〈C〉(野救で打者の)ボールカウント / 〈U〉《話》考慮,注目(account)
(英国以外の)伯爵
(商店・銀行などの)『売り台』,勘定台,カウンター / (食堂などに)『カウンター』 / (おもちゃの)模造貨幣
計算する人 / (特に電動式の)計算器,計数器 / (ゲームの得点計算用)数取り,点棒
『反対の』,逆の(opposite) / (一対の)片方の,副の / (…と)反対に,逆に《+『to』+『名』》 / …‘に'『逆らう』,立ち向かう / …'を'無効にする / (ボクシングなどで)〈打撃〉'を'返す,‘に'反撃する / (ボクシングなどで)打ち返す / 『逆』,反対,対立物 / (フェンシングの)受け流し / (ボクシングなどで)打ち返し,カウンター / (靴の)かかとの皮
イオン

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/09/29 04:56:27」(JST)

wiki en

[Wiki en表示]

Polystyrene sulfonate, a cation exchange resin, is typically supplied with Na⁺ as the counterion.

A counterion (pronounced as two words, i.e. "counter" "ion", and sometimes written as two words) is the ion that accompanies an ionic species in order to maintain electric neutrality. In table salt (NaCl), the sodium cation is the counterion for the chlorine anion and vice versa.

Interfacial chemistry

Counterions are the mobile ions in ion exchange polymers and colloids.^[1] Ion exchange resins are polymers with a net negative or positive charge. Cation exchange resins consist of an anionic polymer with countercations, typically Na+. The resin has a higher affinity for highly charged countercations, e.g., by Ca²⁺ in the case of water softening. Complementarily, anion exchange resins are typically provided in the form of chloride, which is a highly mobile couteranion.

Counterions are used in phase-transfer catalysis. In a typical application lipophilic countercation such as benzalkonium solubilizes reagents in organic solvents.

Solution chemistry

Solubility of salts in organic solvents is a function of both the cation and the anion. The solubility of cations in organic solvents can be enhanced when the anion is lipophilic. Similarly, the solubility of anions in organic solvents is enhanced with lipophilic cations. The most common lipophilic cations are quaternary ammonium cations, called "quat salts".

Lipophilic counteranions
Lithium tetrakis(pentafluorophenyl)borate is the lithium salt of a highly lipophilic tetraarylborate anion, often referred to as a weakly coordinating anion.^[2]
Tetraphenylborate is less lipophilic than the perfluorinated derivative, but widely used as a precipitating agent.
Hexafluorophosphate is a common weakly coordinating anion.
As illustrated by the small counteranion tetrafluoroborate (BF₄⁻), lipophilic cations tend to be symmetric and singly charged.

Lipophilic countercations
Bis(triphenylphosphine)iminium chloride is the chloride salt of a bulky lipophilic phosphonium cation [Ph₃PNPPh₃]⁺.
Tetraphenylphosphonium chloride (C₆H₅)₄PCl, abbreviated Ph₄PCl or PPh₄Cl is the chloride of a symmetrical phosphonium cation that is often used in organometallic chemistry. The arsonium salt is also well known.
The bromide salt of tetrabutylammonium, one of the most common counter cations. Many analogous "quat salts" are known.
Alkali metal cations bound by crown ethers are common lipophilic countercations, as illustrated by [Li(12-crown-4)₂]⁺.

Many cationic organometallic complexes are isolated with inert, noncoordinating counterions. Ferrocenium tetrafluoroborate is one such example.

Electrochemistry

In order to achieve high ionic conductivity, electrochemical measurements are conducted in the presence of excess electrolyte. In water the electrolyte is often a simple salt such as potassium chloride. For measurements in nonaqueous solutions, salts composed of both lipophilic cations and anions are employed, e.g., tetrabutylammonium hexafluorophosphate. Even in such cases potentials are influenced by ion-pairing, an effect that is accentuated in solvents of low dielectric constant.^[3]

Counterion stability

For many applications, the counterion simply provides charge and lipophilicity that allows manipulation of its partner ion. The counterion is expected to be chemically inert. For counteranions, inertness is expressed in terms of low Lewis basicity. The counterions are ideally rugged and unreactive. For quaternary ammonium and phosphonium countercations, inertness is related to their resistance of degradation by strong bases and strong nucleophiles.

References

^ http://goldbook.iupac.org/C01371.html
^ I. Krossing and I. Raabe (2004). "Noncoordinating Anions - Fact or Fiction? A Survey of Likely Candidates". Angewandte Chemie International Edition. 43 (16): 2066–2090. doi:10.1002/anie.200300620. PMID 15083452.
^ Geiger, W. E., Barrière, F., "Organometallic Electrochemistry Based on Electrolytes Containing Weakly-Coordinating Fluoroarylborate Anions", Acc. Chem. Res. 2010, 43, 1030. doi:10.1021/ar1000023

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 非動脈炎性前部虚血性視神経症：疫学、発症機序、および病因 nonarteritic anterior ischemic optic neuropathy epidemiology pathogenesis and etiologies
2. 後部虚血性視神経症 posterior ischemic optic neuropathy
3. 非動脈炎性前部虚血性視神経症：臨床的特徴および診断 nonarteritic anterior ischemic optic neuropathy clinical features and diagnosis
4. 非動脈炎性虚血性視神経症：予後および治療 nonarteritic ischemic optic neuropathy prognosis and treatment
5. 非眼科手術のための麻酔後の視力低下 postoperative visual loss after anesthesia for nonocular surgery

English Journal

Poly(tetrafluoroethylene) composite membranes coated with urchin-like polyaniline hiberarchy: Preparation and properties.

Shi Z, Zhou H, Dai T, Lu Y.SourceDepartment of Polymer Science and Engineering, State Key Lab Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China.
Journal of colloid and interface science.J Colloid Interface Sci.2012 Nov 1;385(1):211-7. Epub 2012 Jul 20.
Spiny polyaniline (PANI) spheres (urchin-like) were coated on a poly(tetrafluoroethylene) (PTFE) membrane via a counter-diffuse interfacial oxidation polymerization of aniline in an aqueous medium. The produced composite membrane has both unexpected superhydrophilicity and conductivity. The microstr
PMID 22878001

Highly-controlled grafting of mono and dicationic 4,4'-bipyridine derivatives on SBA-15 for potential application as adsorbent of CuCl(2) from ethanol solution.

Fattori N, Maroneze CM, Magosso HA, Kholin YV, Gushikem Y.SourceInstitute of Chemistry, State University of Campinas, PO Box 6154, 13083-970 Campinas, SP, Brazil.
Journal of colloid and interface science.J Colloid Interface Sci.2012 Oct 15;384(1):137-42. Epub 2012 Jul 4.
This work describes a highly controlled post-grafting of mono and dicationic 4,4'-bipyridine alkoxysilane derivatives (Bipy(+) and Bipy(2+)) onto the surface of an ordered mesoporous silica, SBA-15. The materials obtained are designated as SBA-15/Bipy(+)Cl(-) and SBA-15/Bipy(2+)Cl(2)(-), both posses
PMID 22832098