WordNet

related by blood; not adopted
(craps) a first roll of 7 or 11 that immediately wins the stake
a notation cancelling a previous sharp or flat (同)cancel
someone regarded as certain to succeed; "hes a natural for the job"
being talented through inherited qualities; "a natural leader"; "a born musician"; "an innate talent" (同)born, innate
unthinking; prompted by (or as if by) instinct; "a cats natural aversion to water"; "offering to help was as instinctive as breathing" (同)instinctive
(used especially of commodities) being unprocessed or manufactured using only simple or minimal processes; "natural yogurt"; "natural produce"; "raw wool"; "raw sugar"; "bales of rude cotton" (同)raw, rude
(of a musical note) being neither raised nor lowered by one chromatic semitone; "a natural scale"; "B natural"
existing in or in conformity with nature or the observable world; neither supernatural nor magical; "a perfectly natural explanation"
existing in or produced by nature; not artificial or imitation; "a natural pearl"; "natural gas"; "natural silk"; "natural blonde hair"; "a natural sweetener"; "natural fertilizers"
functioning or occurring in a normal way; lacking abnormalities or deficiencies; "its the natural thing to happen"; "natural immunity"; "a grandparents natural affection for a grandchild"
in accordance with nature; relating to or concerning nature; "a very natural development"; "our natural environment"; "natural science"; "natural resources"; "natural cliffs"; "natural phenomena"
the property of a more than adequate quantity or supply; "an age of abundance" (同)copiousness, teemingness
(chemistry) the ratio of the total mass of an element in the earths crust to the total mass of the earths crust; expressed as a percentage or in parts per million
(physics) the ratio of the number of atoms of a specific isotope of an element to the total number of isotopes present

PrepTutorEJDIC

『自然のままの』,自然にある,自然が作る / 自然に関する / 『当然の』,あたりまえの / 『生まれつきの』(inborn) / 生き写しの,真に迫った / 気どらない,飾らない / (音階が)本位の / (音階の)本位音;本位記号 / 《単数形で》《話》(…の)生来の達人,(…に)最初からうってつけの人《+『for』(『as』)+『名』》
(あり余るほど)『たくさん』,『豊富』;《an~》たくさん(の…)《+『of』+『名』》

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2018/07/20 14:09:10」(JST)

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In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic weight listed for the element in the periodic table. The abundance of an isotope varies from planet to planet, and even from place to place on the Earth, but remains relatively constant in time (on a short-term scale).

As an example, uranium has three naturally occurring isotopes: ²³⁸U, ²³⁵U and ²³⁴U. Their respective natural mole-fraction abundances are 99.2739–99.2752%, 0.7198–0.7202%, and 0.0050–0.0059%.^[1] For example, if 100,000 uranium atoms were analyzed, one would expect to find approximately 99,274 ²³⁸U atoms, approximately 720 ²³⁵U atoms, and very few (most likely 5 or 6) ²³⁴U atoms. This is because ²³⁸U is much more stable than ²³⁵U or ²³⁴U, as the half-life of each isotope reveals: 4.468 × 10⁹ years for ²³⁸U compared with 7.038 × 10⁸ years for ²³⁵U and 245,500 years for ²³⁴U.

Exactly because the different uranium isotopes have different half-lives, when the Earth was younger, the isotopic composition of uranium was different. As an example, 1.7×10⁹ years ago the NA of ²³⁵U was 3.1% compared with today's 0.7%, and for that reason a natural nuclear fission reactor was able to form, something that cannot happen today.

However, the natural abundance of a given isotope is also affected by the probability of its creation in nucleosynthesis (as in the case of samarium; radioactive ¹⁴⁷Sm and ¹⁴⁸Sm are much more abundant than stable ¹⁴⁴Sm) and by production of a given isotope as a daughter of natural radioactive isotopes (as in the case of radiogenic isotopes of lead).

Deviations from natural abundance

It is now known from study of the sun and primitive meteorites that the solar system was initially almost homogeneous in isotopic composition. Deviations from the (evolving) galactic average, locally sampled around the time that the sun's nuclear burning began, can generally be accounted for by mass fractionation (see the article on mass-independent fractionation) plus a limited number of nuclear decay and transmutation processes.^[2] There is also evidence for injection of short-lived (now extinct) isotopes from a nearby supernova explosion that may have triggered solar nebula collapse.^[3] Hence deviations from natural abundance on earth are often measured in parts per thousand (per mille or ‰) because they are less than one percent (%).

The single exception to this lies with the presolar grains found in primitive meteorites. These bypassed the homogenization, and often carry the nuclear signature of specific nucleosynthesis processes in which their elements were made.^[4] In these materials, deviations from "natural abundance" are sometimes measured in factors of 100.

Natural abundance of some elements

The next table gives the isotope distributions for some elements. Some elements like phosphorus and fluorine only exist as a single isotope, with a natural abundance of 100%.

**Natural abundance of some elements** ^[5]
Isotope	% nat. abundance	atomic mass
¹H	99.985	1.007825
²H	0.015	2.0140
¹²C	98.89	12 (definition)
¹³C	1.11	13.00335
¹⁴N	99.64	14.00307
¹⁵N	0.36	15.00011
¹⁶O	99.76	15.99491
¹⁷O	0.04	16.99913
¹⁸O	0.2	17.99916
²⁸Si	92.23	27.97693
²⁹Si	4.67	28.97649
³⁰Si	3.10	29.97376
³²S	95.0	31.97207
³³S	0.76	32.97146
³⁴S	4.22	33.96786
³⁷Cl	24.23
³⁵Cl	75.77	34.96885
⁷⁹Br	50.69	78.9183
⁸¹Br	49.31	80.9163

Footnotes and References

^ Uranium Isotopes, retrieved 14 March 2012
^ Clayton, Robert N. (1978). "Isotopic anomalies in the early solar system". Annual Review of Nuclear and Particle Science. 28: 501–522. Bibcode:1978ARNPS..28..501C. doi:10.1146/annurev.ns.28.120178.002441.
^ Zinner, Ernst (2003). "An isotopic view of the early solar system". Science. 300 (5617): 265–267. doi:10.1126/science.1080300. PMID 12690180.
^ Zinner, Ernst (1998). "Stellar nucleosynthesis and the isotopic composition of presolar grains from primitive meteorites". Annual Review of Earth and Planetary Sciences. 26: 147–188. Bibcode:1998AREPS..26..147Z. doi:10.1146/annurev.earth.26.1.147.
^ Lide, D. R., ed. (2002). CRC Handbook of Chemistry and Physics (83rd ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0483-0.

External links

Berkeley Isotopes Project Interactive Table
Scientific Instrument Services List
Tools to compute low and high precision isotopic distribution

UpToDate Contents

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1. ナチュラルキラー（NK）細胞大顆粒リンパ球性白血病 natural killer nk cell large granular lymphocyte leukemia
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5. 若年性特発性関節炎：疫学と免疫病態学 juvenile idiopathic arthritis epidemiology and immunopathogenesis

English Journal

Morphological and Molecular Differentiation of Sporidiobolus johnsonii ATCC 20490 and Its Coenzyme Q10 Overproducing Mutant Strain UF16.

Ranadive P1, Mehta A2, Chavan Y3, Marx A1, George S1.
Indian journal of microbiology.Indian J Microbiol.2014 Sep;54(3):343-57. doi: 10.1007/s12088-014-0466-8. Epub 2014 May 1.
Coenzyme Q10 (CoQ10) is an industrially important molecule having nutraceutical and cosmeceutical applications. CoQ10 is mainly produced by microbial fermentation and the process demands the use of strains with high productivity and yields of CoQ10. During strain improvement program consisting of se
PMID 24891743

The virus of my virus is my friend: Ecological effects of virophage with alternative modes of coinfection.

Taylor BP1, Cortez MH2, Weitz JS3.
Journal of theoretical biology.J Theor Biol.2014 Aug 7;354:124-36. doi: 10.1016/j.jtbi.2014.03.008. Epub 2014 Mar 21.
Virophages are viruses that rely on the replication machinery of other viruses to reproduce within eukaryotic hosts. Two different modes of coinfection have been posited based on experimental observation. In one mode, the virophage and the virus enter the host independently. In the other mode, the v
PMID 24662503

Effects of feral cats on the evolution of anti-predator behaviours in island reptiles: insights from an ancient introduction.

Li B1, Belasen A2, Pafilis P3, Bednekoff P4, Foufopoulos J2.
Proceedings. Biological sciences / The Royal Society.Proc Biol Sci.2014 Aug 7;281(1788). pii: 20140339. doi: 10.1098/rspb.2014.0339.
Exotic predators have driven the extinction of many island species. We examined impacts of feral cats on the abundance and anti-predator behaviours of Aegean wall lizards in the Cyclades (Greece), where cats were introduced thousands of years ago. We compared populations with high and low cat densit
PMID 24943365

Japanese Journal

Effects of CO2 and iron availability on rbcL gene expression in Bering Sea diatoms

Endo H.,Sugie K.,Yoshimura T.,Suzuki K.
Biogeosciences 12(7), 2247-2259, 2015-04-15
… However, there is little information available on the impact of CO2-induced seawater acidification on natural phytoplankton assemblages in HNLC regions. … Interestingly, regardless of Fe availability, the transcript abundance of rbcL decreased in the high CO2 treatments (600 and 1000 ppm). …
NAID 120005613574

Using Acetate and Formate as the Substrates for Geobacter sulfurreducens Exoelectrogenesis Resulted in Different Half-saturation Potentials

PENG Luo,ZHANG Xiao-Ting,KAWAICHI Satoshi,XIE De-Ti,LI Zhen-Lun
Electrochemistry 83(8), 600-604, 2015
… Due to implications to relevant engineering and natural systems, this study evaluated such possibility and underlying causes. … Significant changes in the relative abundance of high-potential and low-potential electrocatalytically active conduits were not observed as well. …
NAID 130005092001

Compositions of non-hydrocarbon and noble gases in natural gas samples from Tarim Basin, China

HE DAXIANG,CHEN JIANFA,ZHANG CHEN [他],Li Wei,Zhou Jianxun
GEOCHEMICAL JOURNAL 49(3), 271-282, 2015
… Compositions of non-hydrocarbon and noble gases in natural gas samples collected from the Kuqa Depression, Tabei Uplift Belt, North Depression, Tazhong Uplift, and Southeast Depression in the Tarim Basin, China were analyzed to investigate the origin of the natural gases. … The results show that the largest component of the natural gases is hydrocarbon gas with a concentration of 33.46% to 99.26%. …
NAID 130005074563

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