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Moment of truth
The fastest man-made object that ever leave the Earth is the Pinoeer 10 spacecraft, launched in 1972, and attained a speed of more than 32000 mph. ||
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bohr magneton Phys.
The atomic unit of magnetic moment, defined as eh/4pme where h is the Planck's constant; me mass of the electron and e is the
elementary charge. Hence, it defines the moment associated with a single electron spin.
boiling point Phys., Chem.
The temperature at which the liquid and gas phases of a substance are in equilibrium at a specific pressure. Normally, the boiling point is quoted at standard atmospheric pressure of
A celestial object such as an asteroid or meteor that hits the planet or its satellites. The falling object usually explodes on impact, creating a large crater.
bolometric magnitude Astron.
A logarithmic measure of total radiation emitted by a celestial object. This not only includes visible lights but also the entire range of electromagnetic spectrum such as x-ray that cannot penetrate the Earth's atmosphere. This is in contrast to magnitude,
which only quantifies visible brightness of an object.
bond potential Chem.
A mathematical functional form that empirically represents the chemical bond between two atoms that is normally used in molecular simulations. For example, the bond between two atoms i and j are represented by the functional form
V(rij) = ½k(rij - r0)2
where k is a constant, r0 is the equilibrium bond length and rij is the distance between the two atoms. The mathematical form shown
above is in fact a harmonic function, which is one of the form that is commonly used.
Born-Oppenheimer approximation Phys.
Assumption that introduced in electronic calculations that, because a nucleon (proton and neutron) is about 1800 times more massive than an electron, the electron relaxation is instantaneous
with respect to nuclear position. In other words, the electronic interaction within a molecular system depends on the positions of the nuclei, but not on their velocities. This assumption is one of the approximation
used to simplify the solution of the Schrodinger wave equation.
An important copper ore of a mixed copper-iron sulfide, Cu5FeS4. It appears metallic reddish-brown when freshly exposed but soon develop a very thin layer of iridescent bluish-purple tarnish in a few hours, due to the formation of mixed copper oxides and hydroxides.
It is therefore commonly known as the peacock ore due to its appearance. Bornite is orthorhombic with a hardness of 3. The mineral was discovered since 1725 but its name was only given until the middle of 19th century, which was derived from Ignaz von Born (1742-1791), an Austrian Mineralogist.
borosilicate glass Chem.
A specialized glass variety that is heat and chemical resistant. It is produced by the fusion of silica-borax mixtures to form complex polymers of sodium borosilicate. It is frequently used to make laboratory glassware (beakers, test tubes etc.) but is also used to make
other scientific equipment such as telescope mirrors and nuclear waste containment.
High performance, light composite material of boron fibre coated with silicon carbide. It is normally used in the aerospace industry.
Bosch process Chem.
(1) Industrial production of hydrogen by the catalytic reduction of steam with carbon monoxide at 500°C:
The process is named after Carl Bosch (1874-1940), a German chemist.
(2) A Deep Reactive Ion Etching (DRIE) technique that involves repeated, alternative exposure of a photoresist-masked silicon to an etchant (such as SiF6) and a passivant plasma (such as C4F8)
Bose-Einstein condensate Phys.
A state of matter exist only at temperatures very near to 0 K (absolute zero), where the gas atoms are in the same quantum level. This means that all the atoms are identical and essentially lump up to give a single giant blob of ensemble atom. The atoms change from fermionic
to bosonic and no longer obey the Pauli exclusion principle.
The first Bose-Einstein condensate (BEC) was discovered in 1995 by E. Cornell and C. Wieman when a gas cloud of rubidium and sodium atoms were cooled to less than a millionth of a degree above 0 K. This state of matter was first predicted by S. N. Bose in 1924, and subsequently
further developed by Albert Einstein. BEC possesses unusual property that may provide clue on the basic behavior of matter.
A virtual particle that transmit force. According to the theory of particle physics (the Standard Model), the particles of matter all act through boson, a force carrier, which is exchanged between the interacting particles. Bosons can occupy
the same state at the same time. In other words, a boson can share the same space with other bosons, a fact that different forces can exist in the same space at the same time. Example of boson is photon, also known as particle of light, which is responsible to 'carry' the
Boyle's law Chem.
An ideal gas law which states that the volume of a given mass (n) of a gas is inversely proportional to its pressure (p) at constant temperature (T). It was derived by R. Boyle who discovered the relationship in 1662 as a results of experiments on the
compressibility of air. The law is usually expressed in the form:
PV = constant (for fixed n and T)
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