среда, 15 апреля 2009 г.

[Wikipedia] April 16: Niobium

Niobium is a chemical element with symbol Nb and atomic number 41. A
rare, soft, grey, ductile transition metal, niobium is found in the
minerals pyrochlore (the main source for niobium) and columbite.
Niobium has similar physical and chemical properties to another
element, tantalum, and the two are therefore difficult to distinguish.
The German chemist Heinrich Rose determined in 1846 that tantalum ores
contain a second element, which he named niobium, after Niobe from
Greek mythology. It was not until the early 20th century that niobium
was first used commercially. Brazil is the leading producer of niobium
and ferroniobium, an alloy of niobium and iron. Niobium is used mostly
in alloys, the largest part in special steel such as that used in gas
pipelines. Although alloys contain only a maximum of 0.1%, that small
percentage improves the strength of the steel. The temperature
stability of niobium-containing superalloys is important for its use in
jet engines and rocket engines. Niobium is used in various
superconducting materials. These superconducting alloys, also
containing titanium and tin, are widely used in MRI scanners. Other
applications of niobium include its use in welding, nuclear industries,
electronics, optics, numismatics and jewellery. In the last two
applications, niobium's low toxicity and ability to be coloured by
anodisation are particular advantages.

Read the rest of this article:
<http://en.wikipedia.org/wiki/Niobium>

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Today's selected anniversaries:

1853:

The first passenger line of what would become Indian Railways, the
state-owned railway company of India, opened between Bombay and Thane.
<http://en.wikipedia.org/wiki/Indian_Railways>

1912:

American Harriet Quimby became the first woman to fly across the
English Channel.
<http://en.wikipedia.org/wiki/Harriet_Quimby>

1947:

American financier and presidential adviser Bernard Baruch first
described the post-World War II tensions between the Soviet Union and
the United States as a "cold war".
<http://en.wikipedia.org/wiki/cold_war>

2003:

The Treaty of Accession was signed in Athens, admitting ten new member
states, including several countries of the former Eastern Bloc, into
the European Union.
<http://en.wikipedia.org/wiki/Treaty_of_Accession_2003>

2007:

In one of the deadliest shooting incidents in United States history, a
gunman killed 32 people and wounded over 20 more before committing
suicide at Virginia Tech University in Blacksburg, Virginia.
<http://en.wikipedia.org/wiki/Virginia_Tech_massacre>

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Wiktionary's word of the day:

prosaic (adj):
1. Pertaining to or having the characteristics of prose.

2. (of writing or speaking) Straightforward; matter-of-fact; lacking
the feeling or elegance of poetry.

3. (figurative) Overly plain or simple, to the point of being boring;
humdrum
<http://en.wiktionary.org/wiki/prosaic>

___________________________
Wikiquote quote of the day:

All changes, even the most longed for, have their melancholy; for what
we leave behind us is a part of ourselves; we must die to one life
before we can enter another.
--Anatole France
<http://en.wikiquote.org/wiki/Anatole_France>


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