Light damage

Figure B-1. Pressure impulse diagrams for damage to brick houses. Line 1 Threshold for light damage. Line 2 Threshold or moderate damage partial collapse of roof some bearing wall failures. Line 3 Threshold for severe damage 50 to 75 percent of bearing wall destruction. P, side-on overpressure. /, side-on impulse (Baker et al. 1983).

Barbe, M.F., Tytell, M., Gower, D.J., Welch, W.J. (1988). Hyperthermia protects against light damage in the rat retina. Science 241,1817-1820. 

Roberts, JE, Kukielczak, BM, Hu, DN, Miller, DS, Bilski, P, Sik, RH, Motten, AG, and Chignell, CF, 2002. The role of A2E in prevention or enhancement of light damage in human retinal pigment epithelial cells. Photochem Photobiol 75, 184-190. 

Photocycloaddition and photoaddition provide good models for the mechanism by which ultraviolet light can cause damage to nucleic acids. When ultraviolet light damages DNA, the principal reactions occurring involve the nucleic acid bases. Photocycloaddition reactions to form... 

Reme C, Reinboth J, Ciausen M, et ai. Light damage revisited converging evidence, diverging views Graefe s Arch din Exp Ophthaimol 1996 234 2-11. 

Ultraviolet light damages proteins as well as DNA. Residues of Trp, Tyr, His, Cys, and Met are especially susceptible to photolysis, or photooxidation by 02, or by singlet oxygen. Also damaged are unsaturated lipids, porphyrins, flavins, etc. Kynurenic acid (Fig. 25-11) and urocanic acid (Eq. 14-44), an important ultraviolet filter in skin,196 are also decomposed by light. 

Light damage to collections in historic houses and museums is increasing in the recent decades. With the availability of air conditioning to maintain an artificial climate balance, there is little need to seal off the sunlight entering a room. This phenomenon is coupled with the increase in the number of historic private houses that are being converted into public museums with an emphasis on visibility and easy accessibility. 

Polytetrafluoroethylene (PTFE) was subjected to 3 keV electron bombardment and then heated in vacuum to 300 C. The behavior of the material as a function of radiation dose and temperature was studied by x-ray photoelectron spectroscopy (XPS) of the surface and mass spectroscopy of the species evolved. Lightly damaged material heated to 300 C evolved saturated fluorocarbon species, whereas unsaturated fluorocarbon species were evolved from heavily damaged material. 

The problem of light damage to collection objects was also a special concern of Mr. du Pont. Even when the du Pont family still lived in the house, the shades were regularly pulled and the shutters were regularly closed to prevent daylight and sun damage. When the museum opened, Mr. du Pont specified that these procedures continue (3) ... 

In addition, Mr. du Pont underwrote installation of the Pittsburgh Plate Glass tinted Pennvemon Graylite storm windows to further protect the rooms from light damage, and this installation became an added bonus of the new air-conditioning system (4). 

Silverman MS, Hughes SE (1989) Transplantadon of photoreceptors to light-damaged redna. Invest Ophthalmol Vis Sci 30 1684— 1690. 

In the case of exposure to sources such as welding torches and arc welding equipment producing both IR and visible light, a small temperature rise caused by IR can work synergistically to increase blue light damage. 

Where there is sublethal damage, or very light damage, the cells must eliminate or repair the damaged and ineffective proteins, increase protection of the proteins that did... 

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