radioisotope

radioisotope asked:

I feel you so hard on the erasure thing, I only found out that Im not actually that white (even though my skin is so white that I glow in the dark) when my WOC roommate told me that I wasnt. It was a really weird moment for me.

OKAY SO MEGAN STORY TIME

i’ve known i wasn’t white for ages but it was always bc I was Asian. Not bc I was Jewish. Asian. I would describe myself as “half-white” and “legally white”. 

but guess what?? white supremacists in seventh grade sure did not give two flying fucks about that. 

Jews have never and probably will never be given the full protection of white privilege. It will continue to be conditional, based on appearances and how well we hide who we are. 

放射線量の見積りかた(高校数学程度)

放射性物質は時間とともに一定割合で崩壊し放射線を放出する.つまり放射性物質は時間とともに減り続ける.この崩壊の割合を -λ とすると(係数λを正にするため負号を引き出しておく),


という常微分方程式に従う.係数λは壊変定数と呼ぶ.

一般に


の特殊解(Y(0)=1の場合)が


であるから,Y=N, X=-λt とおくと,特殊解は


であり,N(0)を使って一般解を表せば


である.

半減期は N(th)/N(0) = ½ なる th のことであるから,


を解けばよく,


である.

ヨウ素131 (131I) の半減期は 8.02070[d] = 692988[s] なので壊変定数 λI


つまり平均して1秒間に0.000,001,000,23個のヨウ素131が崩壊することになる.1秒間に1個の崩壊を1[Bq]と呼ぶので,ヨウ素1個あたり1.00023[uBq]となる.

ヨウ素131の質量は130.9061246[u]だが簡単な計算方法としては1[mol]あたり131グラム(つまり0.131[kg])と見積もることが出来る.

以下に,放射性物質として例えばヨウ化カリウム(質量166グラム/molヨウ素131で作られたヨウ化カリウムの質量は170グラム/mol程度)で換算してみる.1[mol]はアボガドロ数そのもので 6.02E23 個である.(今後有効数字を3桁にする.)報道にあったように,被曝者から 40,000[カウント/分]= 667[Bq] の放射能を検出したとすると(かつ100%検出できたとすると),これはヨウ素131で667,000,000個分に相当する.全量をヨウ化カリウムとすると 166 170 x 667,000,000 / 6.02E23 = 0.000,000,000,000,184 0.000,000,000,000,188 グラムつまり0.2ピコグラムを帯びていることになる.

体外であれば洗い流せる量であろう.

I131

And still, is your tongue beset
Corrupted, notion-laced
Oh, my love, who poisoned you?
Pressed stained fingers
To your neck, and murmured
Ineptocraticies against and down
Your throat, force-fed
You bigotry, till all
That coated your teeth
Was unrecognizable?
And here, their mark remains,
This pulsing, heavy mass
Beneath your jaw-
Beneath your flushed and fevered
Skin- this tumor, love
Who poisoned you?


(A/N: fun fact, I131 is a radioactive isotope of iodine, used for the tracing and curing of thyroid cancer- which occurs in the thyroid gland of the neck)

Isotope


(source) In 1913, chemist Frederick Soddy introduced the term “isotope”. Soddy was an English chemist and physicist who received the Nobel Prize for Chemistry in 1921 for investigating radioactive substances. He suggested that different elements produced in different radioactive transformations were capable of occupying the same place on the Periodic Table, and on 18 Feb 1913 he named such species “isotopes” from Greek words meaning “same place.” He is credited, along with others, with the discovery of the element protactinium in 1917.

A PET Prototype

This device from the 1960s is an early prototype of a positron emission tomography (PET) scanner. Scientists at the Department of Energy’s Brookhaven National Lab built this circular version of the PET scanner to image small brain tumors and nicknamed it the Head-Shrinker.

PET scans work after radioisotope tracers are introduced into the patient. The imaging equipment picks up gamma rays emitted as a result of the isotope’s decay. The system allows for functional imaging of processes throughout the body. The device is now used for research and to diagnose certain cancers, brain diseases and heart problems.

Keep reading

Uses of Radioisotopes

Smoke Detectors and Americium-241

Ionization smoke detectors use an ionization chamber and a source of ionizing radiation to detect smoke. This type of smoke detector is more common because it is inexpensive and better at detecting the smaller amounts of smoke produced by flaming fires. Inside an ionization detector is a small amount (perhaps 1/5000th of a gram) of americium-241. The radioactive element americium has a half-life of 432 years, and is a good source of alpha particles.

Another way to talk about the amount of americium in the detector is to say that a typical detector contains 0.9 microcurie of americium-241. A curie is a unit of measure for nuclear material. If you are holding a curie of something in your hand, you are holding an amount of material that undergoes 37,000,000,000 nuclear transformations per second. Generally, that means that 37 billion atoms in the sample are decaying and emitting a particle of nuclear radiation (such as an alpha particle) per second. One gram of of the element radium generates approximately 1 curie of activity (Marie Curie, the woman after whom the curie is named, did much of her research using radium).

Food Irradiation

Food irradiation is a method of treating food in order to make it safer to eat and have a longer shelf life. This process is not very different from other treatments such as pesticide application, canning, freezing and drying. The end result is that the growth of disease-causing microorganisms or those that cause spoilage are slowed or are eliminated altogether. This makes food safer and also keeps it fresh longer.

 

Archaeological Dating

Significant progress has been made in this field of study since the discovery of radioactivity and its properties. One application is carbon-14 dating. Recalling that all biologic organisms contain a given concentration of carbon-14, we can use this information to help solve questions about when the organism died. It works like this. When an organism dies it has a specific ratio by mass of carbon-14 to carbon-12 incorporated in the cells of it’s body. (The same ratio as in the atmosphere.) At the moment of death, no new carbon-14 containing molecules are metabolized, therefore the ratio is at a maximum. After death, the carbon-14 to carbon-12 ratio begins to decrease because carbon-14 is decaying away at a constant and predictable rate. Remembering that the half-life of carbon-14 is 5700 years, then after 5700 years half as much carbon-14 remains within the organism.

Geological Dating

U-238 is used for dating rocks. U-238 (half-life of 4.5 billion years) decays to lead-206. The ratio of U-238 to Pb-206, present in a rock, can be used to determine the age of a rock.

Tracing Chemical

Vitamin B 12 can be tagged with a radioisotope of cobalt to study the absorption of the vitamin from the gastrointestinal tract.

Compounds tagged with Fe-59 and Fe-55 are used to study the absorption of iron.

Glucose tagged with carbon-11 (half-life, 20.3 minutes and positron decay mode) circulates through the body, and the positrons emitted in the heart, brain or some other organ are monitored by a PET detector. A computer uses this information to construct an image (called a PET scan) of the organ that is being examined. PET scans have been used to study the effects of drugs on cancers, to measure damage in victims of stroke or heart attack, and to study chemical changes that occur during epileptic seizures.

Melvin Calvin, a biochemist, labeled CO2 with C-14 and worked out the process by which plants photosynthesize carbohydrate from CO2 and H2O

from-http://www.chemcool.com/regents/nuclearchemistry/aim5.htm

Detection of Disease

Iodine-131, a beta emitter, is taken as sodium iodide in drinking water. Almost all of it will find its way to the thyroid. The rate of iodine-131 uptake, determined with a Geiger counter or other scanning device, indicates whether the thyroid glands are functioning properly.

Sodium chloride containing sodium-24, can be injected into the bloodstream to study blood circulation. The beta particles emitted by the sodium-24 are followed and an impaired circulation is immediately detected.

A thallium-201 compound injected into the bloodstream will concentrate in normal heart muscle but will not remain in damaged tissue. A photograph with a nuclear scintillation camera allows the physician to locate the damaged areas.

Technetium-99m is used for locating brain tumors and damaged heart cells.Technetium-99m is probably the most widely used radioisotope in medicine today; it is a decay product, of molybdenum-99.

from-http://www.chemcool.com/regents/nuclearchemistry/aim5.htm

Treatment of Disease

Radium-226 and cobalt-60 are used in cancer therapy.

from-http://www.chemcool.com/regents/nuclearchemistry/aim5.htm

Past Regents Questions- Usually #49 or #50

Jan 2010-49  Which radioisotope is used to treat thyroid disorders?
(1) Co-60   (3) C-14
(2) I-131    (4) U-238

June 2007-50  Which radioisotope is used in medicine to treat thyroid disorders?
(1) cobalt-60      (3) phosphorus-32
(2) iodine-131     (4) uranium-238

June 2009-50 Which nuclide is used to investigate human thyroid gland disorders?
(1) carbon-14          (3) cobalt-60
(2) potassium-37     (4) iodine-131

August 2008-50 Which nuclide is paired with a specific use of that nuclide?
(1) carbon-14, treatment of cancer
(2) cobalt-60, dating of rock formations
(3) iodine-131, treatment of thyroid disorders
(4) uranium-238, dating of once-living organisms

Jan 2006-50 The decay of which radioisotope can be used to estimate the age of the fossilized remains of an insect?
(1) Rn-222      (3) Co-60
(2) I-131         (4) C-14

Jan 2009-50 Cobalt-60 and iodine-131 are radioactive isotopes that are used in
(1) dating geologic formations
(2) industrial measurements
(3) medical procedures
(4) nuclear power

Aug 2010-50 Which isotope is used to treat cancer?
(1) C-14      (3) Co-60
(2) U-238    (4) Pb-206

June 2008-50 Which radioactive isotope is used in treating cancer?
(1) carbon-14      (3) lead-206
(2) cobalt-60       (4) uranium-238

June 2003-39 Which isotope is most commonly used in the radioactive dating of the remains of organic materials? (1) 14-C    (2) 16-N    (3)32-P   (4)37-K

from: http://www.kentchemistry.com/links/Nuclear/radioisotopes.htm

同位体(アイソトープ)

物質は原子から出来ている.原子の種類は元素と言う.自然界には91種類の元素があると言われている(もう少し多いという説もある).


元素には「化学的によく似た元素」と「化学的にそっくりだけれど違う元素」がある.生物は化学反応なので,化学的によく似た元素は生物にとってもよく似た元素で,化学的にそっくりな元素は生物にとっては区別できない元素である.
化学的によく似た元素とは,周期表の縦の列である.例えば,リチウム(Li),ナトリウム(Na),カリウム(K),ルビジウム(Rb),セシウム(Cs)は化学的に似ている.またベリリウム(Be),マグネシウム(Mg),カルシウム(Ca),ストロンチウム(Sr),バリウム(Ba)もまた化学的に似ている.化学的に似ているとは,「超」大雑把に言うと,燃えるときに同じ比率の酸素を消費するということだ.(この言い方はたぶん大雑把すぎる.)
一方,いくつかの元素には化学的にそっくり同じ種類の元素がある.例えば,「カジュアルな」水素(H)にはそっくりさんの重水素(デューテリウム)や三重水素(トリチウム)がある.水素,重水素,三重水素の化学的性質は全く同じである.水は水素と酸素をくっつけたもの(化合物)なので,重水素と酸素をくっつけた水(重水)は水と全く同じ性質を持つ.三重水素を使った水も作ることが出来る.
水素と重水素の違いは,水素原子と重水素原子の重さの違いに現れる.水素の重さを1とすると,重水素の重さはおよそ2である.元素を考える場合,水素(一番軽い元素である)を基準に考えるので,重水素は重さ2ということにして2Hと書き,水素2と読む.もちろん2Hを重水素と呼んでも構わない.三重水素は3Hで,水素3である.ふだんの水素は1Hである.
水素,重水素,三重水素のように化学的にそっくりだけれど重さが違う元素のことを「同位体」と呼ぶ.重水素,三重水素は水素の同位体であるという言い方をよくするが,重水素から見れば,水素,三重水素は重水素の同位体であるとも言える.
同位体には安定な同位体と不安定な同位体がある.例えば水素1Hや重水素2Hは安定な同位体であるが,三重水素3Hは不安定な同位体である.不安定な同位体はどう不安定なのかと言うと,「放射線」を放出して別の元素にかわるのである.三重水素は放射線の一種であるβ線を放出してヘリウム3という安定(だが自然界では希)な同位体に変わる.
安定な同位体を安定同位体,不安定な同位体を不安定同位体と呼ぶが,不安定な同位体は放射線を放出するので,放射性同位体(ラジオアイソトープ)とも言う.
ウラン(U)にも複数の同位体がある.自然に存在するウラン(天然ウラン)のほとんど(99.275パーセント)はウラン238という同位体で,安定か不安定かと言えば不安定ながら,人間の寿命から見るとほぼ安定といってよい同位体(半減期は44億6000万年)である.天然ウランに0.72パーセント含まれるウラン235というウランの同位体も,人間のスケールから見れば安定と言ってよい同位体(半減期7億年)である.
同じ元素の同位体同士の違いは,原子核—原子の中心部で陽子と中性子から出来ている—の中にある中性子の数の違いだけである.中性子は元素の化学的性質を一切変えないので(だから中性だ),同位体とは中性子の数の違いということになる.陽子と中性子の重さはほぼ等しいことと,原子の重さのほとんどは原子核に由来することから,水素(陽子1個)の重さを1とした我々の基準では,重水素(2H)の中身は陽子1個と中性子1個だし,三重水素(3H)の中身は陽子1個と中性子2個でつじつまが合う.
中性子は単体で存在することはめったにないが,ある種の放射性同位体は中性子を放出する.ウラン235やウラン238はその種の同位体である.
ウラン235やウラン238はまた,中性子を吸収もする.ウラン235は中性子を吸収するとウラン236になるが,ウラン236は核分裂を起こして違う元素へと変化する.このときに,ついでに中性子も放出する.(この中性子が別のウラン235に吸収されると,連鎖的に核分裂がおこる.これは臨界である.)
ウラン238もまた,中性子を吸収する.ウラン238が中性子を吸収するとウラン239という不安定な同位体になり,ウラン239はネプツニウム239へ変化し(中性子が陽子へ変化する),ネプツニウム239はさらにプルトニウム239へ変化する(再び中性子が陽子へ変化する).プルトニウム239はウラン235/238に比べると不安定な同位体で,その半減期は2万4000年である.
オチはないのだが,一応メモとしておいておく.

CS-10 Verification Survey at Former McClellan AFB, Sacramento, CA.

At the request of the U.S. Air Force Radioisotope Committee Secretariat (RICS), the U.S. Air Force School of Aerospace Medicine, Consultative Services Division completed an independent radiological assessment/verification survey from 20-22 Feb 2013 a http://dlvr.it/56njMw

I actually studied under Fischbach for a while at Purdue, and two of my really good friends are still working for him getting their Ph.d’s [sic]. He is very excited about this research, but he has to temper his excitement because whenever he presents it, it is met with such skepticism. People accuse him of being a quack, because it is such a widely held belief that decay rates are constant and neutrinos do not interact with things. He does not yet have a model for the interaction, so he simply has to present his research as “These are my findings. This is the evidence. And this is what I still want to do in order to collaborate my findings.” As another commenter said, yes this is potentially much bigger than predicting solar flares, but this is how it is being “sold” right now so that he doesn’t have to say “I don’t think decay rates are a constant” which gets him dismissed as a loon.

(21 April 1972) — A partial view of the Apollo 16 Apollo Lunar Surface Experiments Package (ALSEP) in deployed configuration on the lunar surface as photographed during the mission’s first extravehicular activity (EVA-1), on April 21, 1972. The Passive Seismic Experiment (PSE) is in the foreground center; Central Station (C/S) is in center background, with the Radioisotope Thermoelectric Generator (RTG) to the left. One of the anchor flags for the Active Seismic Experiment (ASE) is at right.

Cassini-Huygens mission’s quick facts

Cassini Orbiter:

  • Dimensions: 6.7 meters (22 feet) high; 4 meters (13.1 feet) wide
  • Weight: 5,712 kilograms (12,593 pounds) with fuel, Huygens probe, adapter, etc; 2,125 kilograms (4,685 pounds) unfueled orbiter alone
  • Orbiter science instruments: composite infrared spectrometer, imaging system, ultraviolet imaging spectrograph, visual and infrared mapping spectrometer, imaging radar, radio science, plasma spectrometer, cosmic dust analyzer, ion and neutral mass spectrometer, magnetometer, magnetospheric imaging instrument, radio and plasma wave science
  • Power: 885 watts (633 watts at end of mission) from radioisotope thermoelectric generators

Huygens Probe:

  • Dimensions: 2.7 meters (8.9 feet) in diameter
  • Weight: 320 kilograms (705 pounds)
  • Probe science instruments: aerosol collector pyrolyser, descent imager and spectral radiometer, Doppler wind experiment, gas chromatograph and mass spectrometer, atmospheric structure instrument, surface science package

womurders asked:

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Potassium is a chemical element with symbol K (derived from Neo-Latin kalium) and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive withwater, generating sufficient heat to ignite hydrogen emitted in the reaction and burning with a lilac flame. Naturally occurring potassium is composed of three isotopes, one of which, 40K, is radioactive. Traces (0.012%) of this isotope are found in all potassium, making 40K the most common radioisotope in the human body and in many biological materials, as well as in common building substances such as concrete.

Because potassium and sodium are chemically very similar, their salts were not at first differentiated. The existence of multiple elements in their salts was suspected in 1702,[4] and this was proven in 1807 when potassium and sodium were individually isolated from different salts by electrolysis. Potassium in nature occurs only in ionic salts. As such, it is found dissolved in seawater (which is 0.04% potassium by weight[5][6]), and is part of many minerals.

Most industrial chemical applications of potassium employ the relatively high solubility in water of potassium compounds, such as potassium soaps. Potassium metal has only a few special applications, being replaced in most chemical reactions with sodium metal.

Potassium ions are necessary for the function of all living cells. Potassium ion diffusion is a key mechanism in nerve transmission, and potassium depletion in animals, including humans, results in various cardiac dysfunctions. Potassium accumulates in plant cells, and thus fresh fruits and vegetables are a good dietary source of it. This resulted in potassium first being isolated from potash, the ashes of plants, giving the element its name. For the same reason, heavy crop production rapidly depletes soils of potassium, and agricultural fertilizers consume 95% of global potassium chemical production.[7] Conversely, plants are intolerant of sodium ions and thus sodium is present in only low concentrations, except specialisthalophytes.

Contents

 [

hide

]

Properties[edit]

Physical[

edit

]

The

flame test

of potassium.

Potassium is the second least dense metal after lithium. It is a soft solid that has a low melting point and can easily be cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray immediately after being exposed to air.[8] In a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nm (see movie below).[9]

Chemical[

edit

]

Potassium atoms have 19 electrons, which is one more than the extremely stable configuration of the noble gas argon. Because of this and its low firstionization energy of 418.8 kJ/mol, the potassium atom is thus much more likely to lose the “extra” electron, acquiring a positive charge, than to gain one and acquire a negative charge; (however, such negatively charged alkalide ions (K) are known.[10][11]) This process requires so little energy that potassium is readily oxidized by atmospheric oxygen. In contrast, the second ionization energy is very high (3052 kJ/mol), because removal of two electrons breaks the stable noble gas electronic configuration (the configuration of the inert argon).[11]Potassium therefore does not readily form compounds with the oxidation state of +2 or higher.[10]

Potassium is an extremely active metal, which reacts violently with oxygen and water in air. With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide. The reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium. This reaction requires only traces of water; because of this, potassium and its liquid alloy with sodium — NaK — are potent desiccants that can be used to dry solvents prior to distillation.[12]

Because of the sensitivity of potassium to water and air, reactions with other elements are possible only in inert atmosphere, such as argon gas using air-free techniques. Potassium does not react with most hydrocarbons such as mineral oil or kerosene.[13] It readily dissolves in liquid ammonia, up to 480 g per 1000 g of ammonia at 0 °C. Depending on the concentration, the ammonia solutions are blue to yellow, and their electrical conductivity is similar to that of liquid metals. In a pure solution, potassium slowly reacts with ammonia to form KNH2, but this reaction is accelerated by minute amounts of transition metal salts.[14]Because it can reduce the salts to the metal, potassium is often used as the reductant in the preparation of finely divided metals from their salts by the Rieke method.[15] For example, the preparation of Rieke magnesium employs potassium as the reductant:

MgCl2

+ 2 K → Mg + 2 KClEnergy levels[

edit

]

All alkali metals are similar in this respect: see Zeeman effect for more information.

Compounds[

edit

]

The only common oxidation state for potassium is +1. Potassium metal is a powerful reducing agent that is easily oxidized to the monopositive cation, K+. Once oxidized, it is very stable and difficult to reduce back to the metal.[10]

Potassium hydroxide reacts readily with carbon dioxide to produce potassium carbonate, and is used to remove traces of the gas from air. In general, potassium compounds have excellent water solubility, owing to the high hydration energy of the K+ ion. The potassium ion is colorless in water and is very difficult to precipitate; possible precipitation methods include reactions with sodium tetraphenylborate, hexachloroplatinic acid, and sodium cobaltinitrite.[13]

Potassium oxidizes faster than most metals and forms oxides with oxygen-oxygen bonds, as do all alkali metals except lithium. Three species are formed during the reaction: potassium oxide, potassium peroxide, and potassium superoxide,[16] which contain three different oxygen-based ions: oxide (O2−
),peroxide (O2−
2), and superoxide (O−
2). The last two species, especially the superoxide, are rare and are formed only in reaction with very electropositivemetals; these species contain oxygen-oxygen bonds.[14] All potassium-oxygen binary compounds are known to react with water violently, forming potassium hydroxide. This compound is a very strong alkali, and 1.21 kg of it can dissolve in as little as a liter of water.[17][18]

Structure of solid potassium superoxide (KO

2

).In aqueous solution[

edit

]

Potassium compounds are typically highly ionic and thus most of them are soluble in water. The main species in water are the aquated complexes [K(H2O)n]+ where n = 6 and 7.[19] Some of the few poorly soluble potassium salts include potassium tetraphenylborate, potassium hexachloroplatinate, and potassium cobaltinitrite.[13]

Isotopes[

edit

]Main article:

Isotopes of potassium

There are 24 known isotopes of potassium, three of which occur naturally: 39K (93.3%), 40K (0.0117%), and 41K (6.7%). Naturally occurring 40K has a half-life of 1.250×109 years. It decays to stable 40Ar by electron capture or positron emission(11.2%) or to stable 40Ca by beta decay (88.8%).[20] The decay of 40K to 40Ar enables a commonly used method for dating rocks. The conventional K-Ar dating method depends on the assumption that the rocks contained no argon at the time of formation and that all the subsequent radiogenic argon (i.e., 40Ar) was quantitatively retained. Minerals are dated by measurement of the concentration of potassium and the amount of radiogenic40Ar that has accumulated. The minerals that are best suited for dating include biotite, muscovite, metamorphic hornblende, and volcanic feldspar; whole rock samples from volcanic flows and shallow instrusives can also be dated if they are unaltered.[20][21] Outside of dating, potassium isotopes have been used astracers in studies of weathering and for nutrient cycling studies because potassium is a macronutrient required for life.[22]

40K occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. 40K is the radioisotope with the largest abundance in the body. In healthy animals and people, 40K represents the largest source of radioactivity, greater even than 14C. In a human body of 70 kg mass, about 4,400 nuclei of 40K decay per second.[23] The activity of natural potassium is 31 Bq/g.[24]

Creation and occurrence[

edit

]See also: the categories

Potassium minerals

and

Potassium compounds

.

Potassium in

feldspar

Potassium is formed in the universe by nucleosynthesis from lighter atoms. Potassium is principally created in Type IIsupernovas via the explosive oxygen-burning process.[25]40K is also formed in s-process nucleosynthesis and the neon burning process.[citation needed]

Elemental potassium does not occur in nature because of its high reactivity. It reacts violently with water (see section Precautions below)[13] and also reacts with oxygen. In its various compounds, potassium makes up about 2.6% of the weight of the Earth’s crust and is the seventh most abundant element, similar in abundance to sodium at approximately 1.8% of the crust.[26] It is the 17th most abundant element by weight in the entire planet and 20th most abundant in the Solar System. The potassium concentration in seawater is 0.39 g/L[5] (0.039 wt/v%), far less abundant than sodium at 10.8 g/L (1.08 wt/v%).[27][28]

Orthoclase (potassium feldspar) is a common rock-forming mineral. Granite for example contains 5% potassium, which is well above the average in the Earth’s crust. Sylvite (KCl), carnallite (KCl·MgCl2·6(H2O)), kainite (MgSO4·KCl·3H2O) and langbeinite (MgSO4·K2SO4) are the minerals found in large evaporite deposits worldwide. The deposits often show layers starting with the least soluble at the bottom and the most soluble on top.[28] Deposits of niter (potassium nitrate) are formed by decomposition of organic material in contact with atmosphere, mostly in caves; because of the good water solubility of niter the formation of larger deposits requires special environmental conditions.[29]

History[edit]

Neither elemental potassium nor potassium salts (as separate entities from other salts) were known in Roman times, and the Latin name of the element,kalium, is not Classical Latin but rather neo-Latin. Kalium was taken from the word “alkali”, which in turn came from Arabic: القَلْيَه‎ al-qalyah “plant ashes.” The similar-sounding English term alkali is from this same root, whereas the word for potassium in Modern Standard Arabic is بوتاسيوم būtāsyūm.

Humphry Davy

The English name for the element potassium comes from the word “potash”,[30] and refers to the method by which potash was obtained – leaching the ash of burnt wood or tree leaves and evaporating the solution in a pot. Potash is primarily a mixture of potassium salts because plants have little or no sodium content, and the rest of a plant’s major mineral content consists of calcium salts of relatively low solubility in water. While potash has been used since ancient times, it was not understood for most of its history to be a fundamentally different substance from sodium mineral salts.Georg Ernst Stahl obtained experimental evidence that led him to suggest the fundamental difference of sodium and potassium salts in 1702,[4] and Henri Louis Duhamel du Monceau was able to prove this difference in 1736.[31] The exact chemical composition of potassium and sodium compounds, and the status as chemical element of potassium and sodium, was not known then, and thus Antoine Lavoisier did not include the alkali in his list of chemical elements in 1789.[32][33]

Potassium metal was first isolated in 1807 in England by Sir Humphry Davy, who derived it from caustic potash (KOH, potassium hydroxide) by the use of electrolysis of the molten salt with the newly discovered voltaic pile. Potassium was the first metal that was isolated by electrolysis.[34] Later in the same year, Davy reported extraction of the metal sodiumfrom a mineral derivative (caustic soda, NaOH, or lye) rather than a plant salt, by a similar technique, demonstrating that the elements, and thus the salts, are different.[32][33][35][36] Although the production of potassium and sodium metal should have shown that both are elements, it took some time before this view was universally accepted.[33]

For a long time the only significant applications for potash were the production of glass, bleach, soap and gunpowder as potassium nitrate.[37] Potassium soaps from animal fats and vegetable oils were especially prized, as they tended to be more water-soluble and of softer texture, and were known as softsoaps.[7] The discovery by Justus Liebig in 1840 that potassium is a necessary element for plants and that most types of soil lack potassium[38] caused a steep rise in demand for potassium salts. Wood-ash from fir trees was initially used as a potassium salt source for fertilizer, but, with the discovery in 1868 of mineral deposits containing potassium chloride near Staßfurt, Germany, the production of potassium-containing fertilizers began at an industrial scale.[39][40][41] Other potash deposits were discovered, and by the 1960s Canada became the dominant producer.[42][43]

Commercial production[edit]

Sylvite

from New Mexico

Potassium salts such as carnallite, langbeinite, polyhalite, and sylvite form extensive deposits in ancient lake bottoms and seabeds,[27] making extraction of potassium salts in these environments commercially viable. The principal source of potassium – potash – is mined in Canada, Russia, Belarus, Germany, Israel, United States, Jordan, and other places around the world.[44][45][46] The first mined deposits were located near Staßfurt, Germany, but the deposits span from Great Britain over Germany into Poland. They are located in the Zechstein and were deposited in the Middle to Late Permian. The largest deposits ever found lie 1,000 meters (3,300 feet) below the surface of the Canadian province of Saskatchewan. The deposits are located in the Elk Point Group produced in the Middle Devonian. Saskatchewan, where several large mines have operated since the 1960s, pioneered the use of freezing of wet sands (the Blairmore formation) in order to drive mine shafts through them. The main potash mining company in Saskatchewan is the Potash Corporation of Saskatchewan.[47] The water of the Dead Sea is used by Israel and Jordan as a source for potash, while the concentration in normal oceans is too low for commercial production at current prices.[45][46]

Monte Kali

, a potash mining and

beneficiation

waste heap in

Hesse, Germany

, consisting mostly of

sodium chloride

.

Several methods are applied to separate the potassium salts from the present sodium and magnesium compounds. The most-used method is to precipitate some compounds relying on the solubility difference of the salts at different temperatures. Electrostatic separation of the ground salt mixture is also used in some mines. The resulting sodium and magnesium waste is either stored underground or piled up in slag heaps. Most of the mined potassium minerals end up as potassium chloride after processing. The mineral industry refers to potassium chloride either as potash, muriate of potash, or simply MOP.[28]

Pure potassium metal can be isolated by electrolysis of its hydroxide in a process that has changed little since Davy. Although the electrolysis process was developed and used in industrial scale in the 1920s the thermal method by reacting sodium with potassium chloride in a chemical equilibrium reaction became the dominant method in the 1950s. The production of sodium potassium alloys is possible by changing the reaction time and the amount of sodium used in the reaction. The Griesheimer process employing the reaction of potassium fluoride with calcium carbide was also used to produce potassium.[28][48]

Na + KCl → NaCl + K                      (Thermal method)2 KF + CaC

2

→ 2 K + CaF

2

+ 2 C    (Griesheimer process)

Reagent-grade potassium metal cost about $10.00/pound ($22/kg) in 2010 when purchased in tonne quantities. Lower purity metal is considerably cheaper. The market is volatile due to the difficulty of the long-term storage of the metal. It must be stored under a dry inert gas atmosphere or anhydrous mineral oil to prevent the formation of a surface layer of potassium superoxide. This superoxide is a pressure-sensitive explosive that will detonate when scratched. The resulting explosion will usually start a fire that is difficult to extinguish.[49][50]

Biological role[edit]

Main article:

Potassium in biology

Biochemical function[

edit

]Main article:

Action potential

The action of the

sodium-potassium pump

is an example of primary

active transport

. The two carrier proteins on the left are using

ATP

to move sodium out of the cell against the concentration gradient. The proteins on the right are using secondary active transport to move potassium into the cell.

Potassium is the eighth or ninth most common element by mass (0.2%) in the human body, so that a 60 kg adult contains a total of about 120 g of potassium.[51] The body has about as much potassium as sulfur and chlorine, and only the major minerals calcium and phosphorus are more abundant.[52]

Potassium cations are important in neuron (brain and nerve) function, and in influencingosmotic balance between cells and the interstitial fluid, with their distribution mediated in all animals (but not in all plants) by the so-called Na+/K+-ATPase pump.[53] This ion pumpuses ATP to pump three sodium ions out of the cell and two potassium ions into the cell, thus creating an electrochemical gradient over the cell membrane. In addition, the highly selective potassium ion channels (which are tetramers) are crucial for thehyperpolarization, in for example neurons, after an action potential is fired. The most recently resolved potassium ion channel is KirBac3.1, which gives a total of five potassium ion channels (KcsA, KirBac1.1, KirBac3.1, KvAP, and MthK) with a determined structure.[54] All five are from prokaryotic species.

Potassium can be detected by taste because it triggers three of the five types of taste sensations, according to concentration. Dilute solutions of potassium ions taste sweet, allowing moderate concentrations in milk and juices, while higher concentrations become increasingly bitter/alkaline, and finally also salty to the taste. The combined bitterness and saltiness of high-potassium solutions makes high-dose potassium supplementation by liquid drinks a palatability challenge.[55][56]

Membrane polarization[

edit

]

Potassium is also important in preventing muscle contraction and the sending of all nerve impulses in animals through action potentials. By nature of their electrostatic and chemical properties, K+ ions are larger than Na+ ions, and ion channels and pumps in cell membranes can distinguish between the two types of ions, actively pumping or passively allowing one of the two ions to pass, while blocking the other.[57]

A shortage of potassium in body fluids may cause a potentially fatal condition known as hypokalemia, typically resulting from vomiting, diarrhea, and/orincreased diuresis.[58] Deficiency symptoms include muscle weakness, paralytic ileus, ECG abnormalities, decreased reflex response and in severe cases respiratory paralysis, alkalosis and cardiac arrhythmia.[59]

Filtration and excretion[

edit

]

Potassium is an essential macromineral in human nutrition; it is the major cation (positive ion) inside animal cells, and it is thus important in maintaining fluid and electrolyte balance in the body. Sodium makes up most of the cations of blood plasma at a reference range of about 145 mmol/L (3.345 g)(1 mmol/L = 1mEq/L), and potassium makes up most of the cell fluid cations at about 150 mmol/L (4.8 g). Plasma is filtered through the glomerulus of the kidneys in enormous amounts, about 180 liters per day.[60] Thus 602 g of sodium and 33 g of potassium are filtered each day. All but the 1–10 g of sodium and the 1–4 g of potassium likely to be in the diet must be reabsorbed. Sodium must be reabsorbed in such a way as to keep the blood volume exactly right and the osmotic pressure correct; potassium must be reabsorbed in such a way as to keep serum concentration as close as possible to 4.8 mmol/L (about 0.190 g/L).[61]Sodium pumps in the kidneys must always operate to conserve sodium. Potassium must sometimes be conserved also, but, as the amount of potassium in the blood plasma is very small and the pool of potassium in the cells is about thirty times as large, the situation is not so critical for potassium. Since potassium is moved passively[62][63] in counter flow to sodium in response to an apparent (but not actual) Donnan equilibrium,[64] the urine can never sink below the concentration of potassium in serum except sometimes by actively excreting water at the end of the processing. Potassium is secreted twice and reabsorbed three times before the urine reaches the collecting tubules.[65] At that point, it usually has about the same potassium concentration as plasma. At the end of the processing, potassium is secreted one more time if the serum levels are too high.

If potassium were removed from the diet, there would remain a minimum obligatory kidney excretion of about 200 mg per day when the serum declines to 3.0–3.5 mmol/L in about one week,[66] and can never be cut off completely, resulting in hypokalemia and even death.[67]

The potassium moves passively through pores in the cell membrane. When ions move through pumps there is a gate in the pumps on either side of the cell membrane and only one gate can be open at once. As a result, approximately 100 ions are forced through per second. Pores have only one gate, and there only one kind of ion can stream through, at 10 million to 100 million ions per second.[68] The pores require calcium in order to open[69] although it is thought that the calcium works in reverse by blocking at least one of the pores.[70] Carbonyl groups inside the pore on the amino acids mimic the water hydration that takes place in water solution[71] by the nature of the electrostatic charges on four carbonyl groups inside the pore.[72]

In diet[

edit

]Deficiency[

edit

]

Diets low in potassium lead to hypertension.[73]

Adequate intake[

edit

]

A potassium intake sufficient to support life can in general be guaranteed by eating a variety of foods. Foods rich in potassium include yam, parsley, driedapricots, dried milk, chocolate, various nuts (especially almonds and pistachios), potatoes, bamboo shoots, bananas, avocados, coconut water, soybeans, andbran, although it is also present in sufficient quantities in most fruits, vegetables, meat and fish.[74]

Optimal intake[

edit

]

Epidemiological studies and studies in animals subject to hypertension indicate that diets high in potassium can reduce the risk of hypertension and possiblystroke (by a mechanism independent of blood pressure), and a potassium deficiency combined with an inadequate thiamine intake has produced heart disease in rats.[75] There is some debate regarding the optimal amount of dietary potassium. For example, the 2004 guidelines of the Institute of Medicinespecify a DRI of 4,700 mg of potassium (100 mEq), though most Americans consume only half that amount per day, which would make them formally deficient as regards this particular recommendation.[76][77] Likewise, in the European Union, in particular in Germany and Italy, insufficient potassium intake is somewhat common.[78] Italian researchers reported in a 2011 meta-analysis that a 1.64 g higher daily intake of potassium was associated with a 21% lower risk of stroke.[79]

Medical supplementation and disease[

edit

]

Supplements of potassium in medicine are most widely used in conjunction with loop diuretics and thiazides, classes of diuretics that rid the body of sodium and water, but have the side-effect of also causing potassium loss in urine. A variety of medical and non-medical supplements such as bicarbonate of potassium are available. Potassium salts such as potassium chloride may be dissolved in water, but the salty/bitter taste of high concentrations of potassium ion make palatable high concentration liquid supplements difficult to formulate.[55] Typical medical supplemental doses range from 10 mmol (400 mg, about equal to a cup of milk or 6 US fl oz (180 ml). of orange juice) to 20 mmol (800 mg) per dose. Potassium salts are also available in tablets or capsules, which for therapeutic purposes are formulated to allow potassium to leach slowly out of a matrix, as very high concentrations of potassium ion (which might occur next to a solid tablet of potassium chloride) can kill tissue, and cause injury to the gastric or intestinal mucosa. For this reason, non-prescription supplement potassium pills are limited by law in the US to only 99 mg of potassium.

Individuals suffering from kidney diseases may suffer adverse health effects from consuming large quantities of dietary potassium. End stage renal failurepatients undergoing therapy by renal dialysis must observe strict dietary limits on potassium intake, as the kidneys control potassium excretion, and buildup of blood concentrations of potassium (hyperkalemia) may trigger fatal cardiac arrhythmia. [80]

Applications[edit]

Fertilizer[

edit

]

Potassium and magnesium sulfate fertilizer

Potassium ions are an essential component of plant nutrition and are found in most soil types.[7] They are used as afertilizer in agriculture, horticulture, and hydroponic culture in the form of chloride (KCl), sulfate (K
2SO
4), or nitrate(KNO
3). Agricultural fertilizers consume 95% of global potassium chemical production, and about 90% of this potassium is supplied as KCl.[7] The potassium content of most plants range from 0.5% to 2% of the harvested weight of crops, conventionally expressed as amount of K
2O. Modern high-yield agriculture depends upon fertilizers to replace the potassium lost at harvest. Most agricultural fertilizers contain potassium chloride, while potassium sulfate is used for chloride-sensitive crops or crops needing higher sulfur content. The sulfate is produced mostly by decomposition of the complex minerals kainite (MgSO4·KCl·3H2O) and langbeinite (MgSO4·K2SO4). Only a very few fertilizers contain potassium nitrate.[81] In 2005, about 93% of world potassium production was consumed by the fertilizer industry.[46]

Food[

edit

]

The potassium cation is a nutrient necessary for human life and health. Potassium chloride and bicarbonate are used by those seeking to control hypertension.[82] The USDA lists tomato paste, orange juice, beet greens, white beans, potatoes, bananas and many other dietary sources of potassium, ranked in descending order according to potassium content.[83]

Potassium sodium tartrate (KNaC4H4O6, Rochelle salt) is the main constituent of baking powder; it is also used in the silvering of mirrors. Potassium bromate(KBrO
3) is a strong oxidizer (E924), used to improve dough strength and rise height. Potassium bisulfite (KHSO
3) is used as a food preservative, for example in wine and beer-making (but not in meats). It is also used to bleach textiles and straw, and in the tanning of leathers.[84][85]

Industrial[

edit

]

Major potassium chemicals are potassium hydroxide, potassium carbonate, potassium sulfate, and potassium chloride. Megatons of these compounds are produced annually.[86]

Potassium hydroxide KOH is a strong base, which is used in industry to neutralize strong and weak acids, to control pH and to manufacture potassium salts. It is also used to saponify fats and oils, in industrial cleaners, and in hydrolysis reactions, for example of esters.[87][88]

Potassium nitrate (KNO3) or saltpeter is obtained from natural sources such as guano and evaporites or manufactured via the Haber process; it is the oxidantin gunpowder (black powder) and an important agricultural fertilizer. Potassium cyanide (KCN) is used industrially to dissolve copper and precious metals, in particular silver and gold, by forming complexes. Its applications include gold mining, electroplating, and electroforming of these metals; it is also used inorganic synthesis to make nitriles. Potassium carbonate (K
2CO
3 or potash) is used in the manufacture of glass, soap, color TV tubes, fluorescent lamps, textile dyes and pigments.[89] Potassium permanganate (KMnO4) is an oxidizing, bleaching and purification substance and is used for production of saccharin.Potassium chlorate (KClO3) is added to matches and explosives. Potassium bromide (KBr) was formerly used as a sedative and in photography.[7]

Potassium chromate (K2CrO4) is used in inks, dyes, stains (bright yellowish-red color); in explosives and fireworks; in the tanning of leather, in fly paper andsafety matches,[90] but all these uses are due to the properties of chromate ion containment rather than potassium ions.

Niche uses[

edit

]

Potassium compounds are so pervasive that thousands of small uses are in place. The superoxide KO2 is an orange solid that acts as a portable source of oxygen and a carbon dioxide absorber. It is widely used in respiration systems in mines, submarines and spacecraft as it takes less volume than the gaseous oxygen.[91][92]

4 KO

2

+ 2 CO

2

→ 2 K

2

CO

3

+ 3 O

2

Potassium cobaltinitrite K3[Co(NO2)6] is used as artist’s pigment under the name of Aureolin or Cobalt Yellow.[93]

Laboratory uses[

edit

]

An alloy of sodium and potassium, NaK is a liquid used as a heat-transfer medium and a desiccant for producing dry and air-free solvents. It can also be used in reactive distillation.[94] The ternary alloy of 12% Na, 47% K and 41% Cs has the lowest melting point of −78 °C of any metallic compound.[8]

Metallic potassium is used in several types of magnetometers.[95]

Precautions[edit]

A reaction of potassium metal with water. Hydrogen is liberated that burns with a pink or lilac flame, the flame color owing to burning potassium vapor. Strongly alkaline potassium hydroxide is formed in solution.

Potassium metal reacts very violently with water producing potassium hydroxide (KOH) and hydrogen gas.

2 K (s) + 2 H

2

O (l) → 2 KOH (aq) + H

2

↑ (g)

This reaction is exothermic and releases enough heat to ignite the resulting hydrogen. It in turn may explode in the presence of oxygen. Potassium hydroxide is a strong alkali that causes skin burns. Finely divided potassium will ignite in air at room temperature. The bulk metal will ignite in air if heated. Because its density is 0.89 g/cm3, burning potassium floats in water that exposes it to atmospheric oxygen. Many common fire extinguishing agents, including water, either are ineffective or make a potassium fire worse. Nitrogen, argon, sodium chloride (table salt), sodium carbonate (soda ash), and silicon dioxide (sand) are effective if they are dry. Some Class D dry powder extinguishers designed for metal fires are also effective. These agents deprive the fire of oxygen and cool the potassium metal.[96]

Potassium reacts violently with halogens and will detonate in the presence of bromine. It also reacts explosively withsulfuric acid. During combustion potassium forms peroxides and superoxides. These peroxides may react violently withorganic compounds such as oils. Both peroxides and superoxides may react explosively with metallic potassium.[97]

Because potassium reacts with water vapor present in the air, it is usually stored under anhydrous mineral oil or kerosene. Unlike lithium and sodium, however, potassium should not be stored under oil for longer than 6 months, unless in an inert (oxygen free) atmosphere, or under vacuum. After prolonged storage in air dangerous shock-sensitive peroxides can form on the metal and under the lid of the container, and can detonate upon opening.[98]

Because of the highly reactive nature of potassium metal, it must be handled with great care, with full skin and eye protection and preferably an explosion-resistant barrier between the user and the metal. Ingestion of large amounts of potassium compounds can lead to hyperkalemia strongly influencing the cardiovascular system.[99][100] Potassium chloride is used in the United States for executions via lethal injection.[99]

[ Authors ]
T. R. Gentile, M. J. Bales, H. Breuer, T.E. Chupp, K. J. Coakley, R. L. Cooper, J. S. Nico, B. O'Neill
[ Abstract ]
We present measurements of nonproportionality in the scintillation light yield of bismuth germanate (BGO) for gamma-rays with energies between 6 keV and 662 keV. The scintillation light was read out by avalanche photodiodes (APDs) with both the BGO crystals and APDs operated at a temperature of approximately 90 K. Data were obtained using radioisotope sources to illuminate both a single BGO crystal in a small test cryostat and a 12-element detector in a neutron radiative beta-decay experiment. In addition one datum was obtained in a 4.6 T magnetic field based on the bismuth K x-ray escape peak produced by a continuum of background gamma rays in this apparatus. These measurements and comparison to prior results were motivated by an experiment to study the radiative decay mode of the free neutron. The combination of data taken under different conditions yields a reasonably consistent picture for BGO nonproportionality that should be useful for researchers employing BGO detectors at low gamma ray energies.

The Global Market for Radiopharmaceuticals is Projected to Reach US$6 Billion by 2020

Expanding Commercial Use in Nuclear Imaging Drives Demand for Radiopharmaceuticals, According to a New Report by Global Industry Analysts, Inc.

GIA announces the release of a comprehensive global report on Radiopharmaceuticals. The global market for Radiopharmaceuticals is projected to reach US$6 billion by 2020, driven by the growing mainstream interest in nuclear medicine, and the development of new radionuclides for cancer nuclear imaging and internal radiotherapy.

Defined as radioactive isotopes, radiopharmaceuticals are used as tracers to diagnose and treat various life-threatening diseases. The global market for radiopharmaceuticals is driven by the increase in the number of nuclear imaging procedures in the field of cardiology, neurology, pulmonology, and oncology. Diagnostic radiopharmaceuticals represent the largest market, supported by the well-established use of radioisotopes in diagnostic imaging. While cardiovascular and oncology imaging represent the core application areas for diagnostic radiopharmaceuticals, research has expanded its use to other areas of medicine including neurology. Stringent regulations governing the production and storage of radiopharmaceuticals, fears associated with radioactivity exposure, and shortage of raw materials, represent immediate challenges to growth in the market. The global production and supply of Technetium-99, a key radioisotope used in radiopharmaceuticals, remains challenged. As a result, development of a new technology is currently underway to produce isotopes without a nuclear reactor.

Therapeutic radiopharmaceuticals represents the fastest growing market, supported by numerous advantages over traditional therapies and drugs. Few of these benefits include targeted therapeutic irradiation with lower side effects, and superior radioactivity enabled noninvasive external monitoring. Easy detection of metastatic sites and uninterrupted monitoring of progress in treatment are key factors driving use of radiopharmaceuticals in targeted treatment applications. Cancer is therefore emerging as a lucrative application area for radiopharmaceuticals. The success of radioimmunotherapy, which involves the use of radiolabelled antibodies to release cytotoxic radiation to a target cell, holds promising prospects for radiopharmaceuticals. Research revolving around therapeutic radiopharmaceuticals is mainly focused on antibody-based drugs and the relatively new-targeted peptides linked to therapeutic isotopes.

As stated by the new market research report on Radiopharmaceuticals, the United States represents the largest market worldwide. Asia-Pacific is forecast to emerge as the fastest growing market with a CAGR of 10.4% over the analysis period. The growth in the region is led by developing healthcare infrastructure, growing R&D interest in nuclear medicine, commitment to technology and development of new therapeutic isotopes, and the need for safe and effective therapies and products to meet the complex healthcare needs of a growing population.  

Major players covered in the report include Actinium Pharmaceuticals Inc., Advanced Medical Isotope Corporation, Alliance Medical, Alseres Pharmaceuticals Inc., Avid Radiopharmaceuticals, Bayer HealthCare Medical Care, Bracco Diagnostics Inc., Cardinal Health, Inc., GE Healthcare,  Ion Beam Applications SA, Immunomedics, Inc., Jubilant Pharma, Lantheus Medical Imaging Inc., Mallinckrodt Pharmaceuticals, Medi-Radiopharma Ltd., Nordion, Inc., Peregrine Pharmaceuticals, Inc., PETNET Solutions Inc., Positron Corporation, Singapore Radiopharmaceuticals Pte Ltd., and Triad Isotopes Inc., among others.

The research report titled “Radiopharmaceuticals: A Global Strategic Business Report” announced by Global Industry Analysts Inc., provides a comprehensive review of current market trends, key growth drivers, recent industry activity, and major companies worldwide. The report provides market estimates and projections in US$ for all major geographic markets including the United States, Canada, Japan, Europe (France, Germany, Italy, UK, Spain, Russia and Rest of Europe), Asia-Pacific (China, India and Rest of Asia-Pacific), Middle East, and Latin America (Brazil and Rest of Latin America). Product segments analyzed include Diagnostic Radiopharmaceuticals and Therapeutic Radiopharmaceuticals.

Cancer treatment ads exaggerated, says govt

Cancer treatment ads exaggerated, says govt

ขอบคุณแหล่งข้อมูล : ศาสตร์เกษตรดินปุ๋ย : หนังสือพิมพ์ The Nation

http://www.nationmultimedia.com/national/Cancer-treatment-ads-exaggerated-says-govt-30258449.html

Pratch Rujivanarom

The Nation April 22, 2015 1:00 am

MANY THAI PATIENTS FLYING TO CHINA FOR UNPROVEN, POSSIBLY DANGEROUS, THERAPY

WHILE the government cannot prevent cancer patients from flying to China to get radioisotope…

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Pengelolaan Limbah Radioaktif

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