Heat indicator lights

Havaux, M. and W.I. Gruszecki. 1993. Heat- and light-induced chlorophyll a fluorescence changes in potato leaves containing high or low levels of the carotenoid zeaxanthin Indications of a regulatory effect of zeaxanthin on thylakoid membrane fluidity. Photochem. Photobiol. 58 607-614. 

In contrast to the color changes that occurred in modern, uncoated silk after exposure to heat, the light-induced color change was not indicative of the tensile properties of the fabric. Loss in tensile properties with irradiation continued while the color remained static. 

Biocides. The attack of fungi on the several components of a vinyl formulation may manifest itself as an unsightly growth looking much like dirt or may result in the formation of discolored areas (yellow, pink, blue, clear) on the finished goods. Outdoor exposure, indoor exposure in humid atmosphere, soil burial or contact, and electrical insulation compounds are typical areas where biocide addition is indicated. Since most commercial biocides are heavy metal derivatives, care must be taken to assess their effect on heat and light stability and compatibility with the vinyl system in which they are used. 

Indicate reaction conditions and catalysts over and under the arrow in a smaller type size. The Greek capital letter delta indicates heat hv indicates light, where h is Planck s constant and the Greek letter nu is the photon frequency. 

The modern silk sample not subjected to heat or light stress displayed fracture Types 2, 5, 7, and 11. The dominant fracture type exhibited by these fibers was Type 7 50 of the modern silk fractures were of this type. This finding indicates that surface flaws largely govern the fracture mechanism of modern silk. A smaller number of fracture Types 2, 5, and 11 were observed. This observation indicates that at least some of these fibers also exhibit ductility, a moderate loss of interfibrillar cohesion, and large internal voids, although their influence in fiber fracture is considerably less than that of surface flaws. 

How can you tell when a chemical reaction has taken place Although some chemical reactions are hard to detect, many reactions provide evidence that they have occurred. A temperature change can indicate a chemical reaction. Many reactions, such as those that occur during a forest fire, release energy in the form of heat and light. Other reactions absorb heat. 

To create the photograph in Figure 4.1, we directed a stream of chlorine gas (GI2) onto solid phosphorus (P4). The mixture burst into flame, and the chemical reaction produced liquid phosphorus trichloride, PGI3. We can depict this using the balanced chemical equation shown opposite, top, which shows the relative amounts of reactants (the substances combined in the reaction) and products (the substances produced). The physical states of the reactants and products are also often indicated in an equation. The symbol (s) indicates a solid, (g) a gas, and (f) a liquid. What the equation does not show are the conditions of the experiment or if any energy (in the form of heat or light) is involved. Lastly, a chemical equation does not tell you if the reaction happens very quickly or if it takes 100 years. 

Changes in color or odor, production or absorption of heat or light, gas release, and formation of a precipitate are all observable macroscopic changes that indicate that a chemical reaction may have occurred. 

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