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System configuration for microcomputer-controlled, low-temperature differential thermal analysis

1990; Elsevier BV; Volume: 5; Issue: 3 Linguagem: Inglês

10.1016/0168-1699(90)90013-f

1872-7107

Michael Wisniewski, G. W. Lightner, Glen Davis, Mark Schiavone,

Thermoregulation and physiological responses

A microcomputer-based differential thermal analysis system is described. It consists of a 16-bit, 48-channel data acquisition unit, relay output device, and signal-processing software. With this system, several aluminum block heat sinks, each containing five samples and a temperature reference, can be programmed independently to produce different, highly accurate freezing rates. Temperature deviation is ± 0.1°C at any given temperature along the ramp. Drift (> 1°C) from any temperature setpoint during a prolonged hold (up to 10 h) was not observed. The system is sensitive enough to detect exotherms from both floral buds and xylem tissue. Output is acquired from each sample as a millivolt differential in comparison to a reference sample and the signal is displayed using signal processing software. Acquisition of signal noise during any run of samples was negligible, relative to the millivolt output obtained from the exothermic events occurring during the freezing of water within a given sample of tissue. The latter software can be used to interactively analyze and compare collected data and also obtain hard-copy plots of the thermograms.