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Z-MODULATION

The variations in intensity in the electron beam of a cathode-ray tube which form the display or picture on a sweep or raster.

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Z-VALUE

The empirical value in degrees Celsius or Fahrenheit required to achieve a ten-fold reduction of the rate of inactivation of a specific micro-organism. The Z- value is used to calculate equivalence of sterilization processes. Often used in conjunction with D-value.

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ZAFFER, ZAFFRE

Impure cobalt oxide remaining when arsenic and sulphur have been removed by roasting.

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ZANCLIAN

A stage in the Pliocene. See Tertiary.

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ZAWN

Cavern, natural or man-made in Cornwall. UK.

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ZEBRA PATTERN VIDEO LEVEL INDICATOR

A striped pattern which is superimposed as a warning on over

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ZECHSTEIN

The upper series of the Permian. See Palaeozoic.

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ZEEMAN EFFECT

The splitting of spectrum lines into a number of components by strong magnetic fields. The field splits the atomic energy levels into several compon

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ZEIN

The maize protein used for experimental production of thermoset plastics by cross-linking with formaldehyde. See casein. Other proteins hitherto unsuccessfully used for plastics include those extracted from ground nuts Ardil, soyabean, castor bean and blood.

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ZEISEL'S METHOD

A method for the determination of methoxyl and ethoxyl groups in organic compounds, in which the substance is heated with hydriodic acid; the iodoalkane thus formed is passed into an ethanolic solution of silver I nitrate, and the resulting silver I iodide weighed.

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