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Index (B)
BA - BC
BD - BF
BG - BJ
BK - BN
BO - BO
BP - BR
BS - BV
BW - BZ
Moment of truth
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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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BA - BC
B cells Biol.
A type of white blood cells that develop in the bone marrow (in mammals) and are the source of producing antibodies to fight off infections. Also known as B lymphocytes.
Babbitt's metal Eng.
An alloy named after Isaac Babbitt (1799-1862) who originally patented the material. It consists of tin, copper and antimony, in various proportions.
These alloys generally are of low frictional resistance and low wear and are used to make bearing materials for axles and crankshafts. Nowadays traces
of other metals are added while in some cases, lead is substituted for tin for improved mechanical properties such as its ductility and conformability.
background radiation Phys.
Cosmic radiation and radiation originated from naturally occurring radioactive materials found on Earth. Examples of radiation sources in Earth are carbon-14 (in food), radon-222 and radium (1 g per square kilometer of earth).
This unavoidable radiation results in an average dose of about 100 mrem for a person every year.
back titration Chem.
A volume metric analysis technique of adding a reagent in excess and then determining the end-point by titrating the excess. Normally use to determine amount of
insoluble substances, such as insoluble metal carbonates and hydroxides. For example, to determine the content of calcium carbonated present in commercial antacids by
adding excess hydrochloric acid and back titrate the remaining acid with a standardized sodium hydroxide solution.
ball lightning Phys.
A rare phenomenon in which a fiery sphere floats through the air near the surface of the Earth, usually during a thunderstorm. The phenomenon is still a mystery to scientists and there is as yet any theory or experiment that can explain
convincingly its formation and behaviour. The size of the ball can range from a centimetre to a metre or more, usually appear as flame colored but there were eye witness accounts seeing red, blue, green or even white. Its movement can vary
dramatically and can travel quickly in horizontal line, or move vertically upwards from the ground or drop out of the sky. It is also known to enter or leaving buildings by way of chimneys, doors or windows.
All kinds of theories have been suggested. From ignition of fuel to formation of a mini black hole. The most popular of the theories describe ball lightning as some kind of plasma or moving electrical discharge.
Barfoed's reagent Chem., Biochem.
A reagent that is used to test the presence of monosaccharide reducing sugars (e.g. glucose) in solution. It is made of a mixture of ethanoic acid and copper(II) ethanoate. The reagent is added to a test solution and boil. A red-brick precipitate of copper(I) oxide
precipitate will form if any reducing sugars are presence. However, the reaction will be negative if the test solution is disaccharide sugars as they are much weaker reducing agents and, at most, will produce very little precipitate at a lower rate. The reagent was
first devised by a Swedish physician, C. T. Barfoed (1815-1899).
barite Min.
See heavy spar.
barycenter Astron.
The center of gravity of a rotating binary system. In other words, it is the common axis of rotaion of the two-body system. For example, binary stars rotating around each other about the barycenter, as shown in the diagram below.
baryon Phys.
A strong interacting particle, made of three quarks and with a spin of half integral. For example, proton and neutron are baryons. They are classified as one of the two
subgroups of hadrons.
baryon number Phys.
Abbreviated as B, it is a number which can be either +1, -1 or 0 for a particle. All baryons will have a number of +1 and all antibaryons will have a number of -1. All non-baryons willhave a number of 0. The number is used in the
Conservation of baryon number in order to determine the validity of a process in particle physics.
base metal Chem., Eng.
A common, relatively more abundant and cheaper than other metals such as precious metals (gold, silver etc.). Examples are iron, lead and copper. Base metals usually easier to tarnish on exposure to air and moisture or heat.
BA - BC
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B
C
D
E
F
G
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I
J
K
L
M
N
O
P
Q
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U
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