| Letter: P |
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Painting |
A chemical treatment that prevents the adhesion of the non-vulcanized
tyre (the so-called 'green' tyre) to the moulds and/or the vulcanizing
chamber. |
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Pascal |
An international unit of pressure equal to 1 Newton per square metre
(Pa = N/m2). |
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Patenting |
The thermal treatment necessary to restore the structure of steel wire so
as to make it suitable for further deformation via cold drawing. |
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PCB/PCT |
Acronyms for polychlorinated biphenyls and polychlorinated terphenyls,
substances that are potentially dangerous, bioaccumulable, with insulating
and fire-resistant characteristics, principally used in electrical equipment
transformers and/or capacitors ( see entry). |
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Photochemical |
Atmospheric pollution principally caused by the exhaust emissions of
urban vehicular smog traffic; it is the result of a complex chain of
photochemical oxidation reactions triggered by sunlight and favoured by
particular meteorological conditions (inversion...). One of the
consequences of photochemical smog is an increase in ozone in the
troposphere ( see entry), which thus becomes a secondary pollutant.
Furthermore, the relatively non-volatile organic compounds that form may
condense, creating a characteristic mist of tiny droplets. |
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Photonics |
Science and technology relating to a class of devices using photons. The
term photonics was introduced as an analogy with the term electronics in
reference to the replacement of the electron with the photon in
operations typical of electronics such as the processing, transmission and
memorization of data. |
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Pickling |
The elimination of the oxidization of metal surfaces (for example, copper
and steel). The operation is generally conducted in baths containing
solutions of phosphoric or sulphuric acid. |
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Primary energy sources |
Energy sources consumed while supplying final energy services (e.g.
heating and transport) or generating intermediate forms of energy, like for
instance electricity and steam. Examples of primary energy are: coal,
natural gas, liquid propane gas, fuel oil, biomasses. |
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Pressure |
A physical measurement expressing the ratio between the intensity of a
force (expressed in Newtons) exerted on a surface in the normal direction
and the area of that surface (expressed in square metres). |
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