Paraffins

the general term for the ALKANES, saturated ALIPHATIC HYDROCARBONS with the formula C_nH_2n+2. They are quite unreactive hence the name paraffin (from the Latin parum affinis, little allied).

Taken from Dictionary of Science

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In chemistry, paraffin is the common name for the alkane hydrocarbons with the general formula C_nH_2n+2. Paraffin wax refers to the solids with 20 ≤ n ≤ 40 .

The simplest paraffin molecule is that of methane, CH₄, a gas at room temperature. Heavier members of the series, such as that of octane, C₈H₁₈, and mineral oil appear as liquids at room temperature. The solid forms of paraffin, called paraffin wax, are from the heaviest molecules from C₂₀H₄₂ to C₄₀H₈₂. Paraffin wax was identified by Carl Reichenbach in 1830.

Paraffin, or paraffin hydrocarbon, is also the technical name for an alkane in general, but in most cases it refers specifically to a linear, or normal alkane — whereas branched, or isoalkanes are also called isoparaffins. It is distinct from the fuel known in Ireland, Britain and South Africa as paraffin oil or just paraffin, which is called kerosene in most of the U.S., Canada, Australia and New Zealand.

The name is derived from the Latin parum (= barely) + affinis with the meaning here of "lacking affinity", or "lacking reactivity". This is because alkanes, being non-polar and lacking in functional groups, are very unreactive.

Taken from Wikipedia

Ecosystem

an ecological community that includes all organisms which occur naturally within a specific area.

Taken from Dictionary of Science

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The term ecosystem refers to the combined physical and biological components of an environment. An ecosystem is generally an area within the natural environment in which physical (abiotic) factors of the environment, such as rocks and soil, function together along with interdependent (biotic) organisms, such as plants and animals, within the same habitat. Ecosystems can be permanent or temporary. Ecosystems usually form a number of food webs.

Taken from Wikipedia

Immiscible

the term that describes liquids that cannot be mixed together such as water and oil. Two liquids which can be mixed together are described as being miscible.

Taken from Dictionary of Science

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In chemistry, miscibility is the property of liquids to mix in all proportions, forming a homogeneous solution. In principle, the term applies also to other phases (solids and gases), but the main focus is on the solubility of one liquid in another. Water and ethanol, for example, are miscible since they mix in all proportions.

By contrast, substances are said to be immiscible if in some proportion, they do not form a solution. For example, diethyl ether is fairly soluble in water, but these two solvents are not miscible since they are not soluble in all proportions.

Taken from Wikipedia

Bacteriophage or Phage

a virus that attacks and infects a BACTERIUM.

Taken from Dictionary of Science

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A bacteriophage (from 'bacteria' and Greek φᾰγεῖν phagein "to eat") is any one of a number of viruses that infect bacteria. Bacteriophages are among the most common organisms on Earth. The term is commonly used in its shortened form, phage.

Typically, bacteriophages consist of an outer protein capsid enclosing genetic material. The genetic material can be ssRNA, dsRNA, ssDNA, or dsDNA ('ss-' or 'ds-' prefix denotes single-strand or double-strand) long with either circular or linear arrangement. Bacteriophages are much smaller than the bacteria they destroy.

Phages are estimated to be the most widely distributed and diverse entities in the biosphere. Phages are ubiquitous and can be found in all reservoirs populated by bacterial hosts, such as soil or the intestines of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 9×10⁸ virions per milliliter have been found in microbial mats at the surface, and up to 70% of marine bacteria may be infected by phages. They have been used for over 60 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe. They are seen as a possible therapy against multi drug resistant strains of many bacteria.

Taken from Wikipedia

Ultrasonic

a term used to describe sound waves that are inaudible to humans as they have a frequency above 20kHz. Although the human ear is incapable of detecting such a high FREQUENCY, some animals, such as dogs and bats, can detect ultrasonic waves (also known as ultrasound). Ultrasound is used wisely in industry, medicine and research. For example, it is used to detect faults or cracks in underground pipes and to destroy kidney stones and gallstones. The most recent development in ultrasonics is their use in chemical processes to trigger reactions involved in the production of food, plastics and antibiotics. Ultrasonics make certain chemical processes safer and cheaper as they eliminate the need for high temperatures and expensive catalysts.

Taken from Dictionary of Science

Zenith Distance

the angular distance of a heavenly body from the ZENITH.

Taken from Dictionary of Science

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The term zenith distance is more often used in astronomy and is the complement of the elevation. That is: 0° in the zenith, 90° on the horizon, up to 180° at the nadir.

Taken from Wikipedia

Vacuum

in theory, a space in which there is no matter. However, a perfect vacuum is unobtainable and the term describes a gas at a very low pressure.

Taken from Dictionary of Science

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In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". Even putting aside the complexities of the quantum vacuum, the classical notion of a perfect vacuum with gaseous pressure of exactly zero is only a philosophical concept and never is observed in practice. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they simply call "vacuum" or "free space", and use the term partial vacuum to refer to real vacuum. The Latin term in vacuo is also used to describe an object as being in what would otherwise be a vacuum.

The quality of a vacuum refers to how closely it approaches a perfect vacuum. Residual gas pressure is a primary indicator of quality, and is most commonly measured in units called torr, even in metric contexts. Lower pressures indicate higher quality, although other variables must also be taken into account. See ultra-high vacuum. Quantum theory sets limits for the best possible quality of vacuum, predicting that no volume of space can be perfectly empty. See QCD vacuum, for example. Outer space and interstellar space are naturally occurring high quality vacuums, mostly of much higher quality than can be created artificially with current technology. Low quality artificial vacuums have been used for suction for many years.

Vacuum has been a frequent topic of philosophical debate since Ancient Greek times, but was not studied empirically until the 17th century. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A torricellian vacuum is created by filling a tall glass container closed at one end with mercury and then inverting the container into a bowl to contain the mercury.

Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technology has since become available. The recent development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general.

Taken from Wikipedia

Labile

a term used in chemistry which means not stable, likely to change.

Taken from Dictionary of Science

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The term is used to describe a relatively unstable and transient chemical species. As a general example, if molecule exists in a particular conformation for a short life-time, before adopting a lower energy conformation, the former molecular structure is said to have 'high lability' (such as C₂₅, a 25-carbon fullerene spheroid). The term is sometimes also used in reference to reactivity - for example, a complex which quickly reaches equilibrium in solution is said to be labile (with respect to that solution).

Taken from Wikipedia

Habit

the term for the characteristic external shapes of crystals due to the number, shape, size , and orientation of the crystal faces. The extent to which perfect habit may be approached depends upon conditions during formation, speed of growth, impurities etc. Individual crystals of particular minerals may show typical growths. Habits include tabular (flat blades), fibrous ( like thin fibres), prismatic (elongated) and acicular (needle-shaped).

Taken from Dictionary of Science

Abscissa

the term given to the horizontal or x-co-ordinate when describing the position of a point on a graph. It is the distance of the point from the vertical or y-axis. For example, a point two units along the x-axis and three units up the y-axis is said to have CARTESIAN CO-ORDINATES (2,3) where the abscissa is 2.

Taken from Dictionary of Science

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In mathematics, abscissa (plural abscissae) refers to the first element of an ordered pair.

It is the first of the two terms (x, y) by which a point is referred to, in a system of fixed rectilinear coordinate (Cartesian coordinate) axes. The abscissa is also known as the "x" coordinate of a point. The second coordinate, or "y" coordinate, is called the ordinate.

Taken from Wikipedia

Y-Axis

the "vertical" axis when constructing and plotting a graph

Taken from Dictionary of Science

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The vertical axis of a two-dimensional plot in Cartesian coordinates. Physicists and astronomers sometimes call this axis the ordinate, although that term is more commonly used to refer to coordinates along the -axis.

Taken from Wolfram MathWorld