Ultraviolet radiation design

Table II shows, as an example, the combinations of low and high levels for three factors selected by a design team for an accelerated test Involving photovoltaic solar cells. In column 2 the three factors are seen to be temperature T (50 C, 95 C), relative humidity RH (60%, 85%), and ultraviolet radiation UV (five suns, 15 suns). The eight combinations of the high and low levels are shown, together with the predicted months to failure for each combination. In this example the documentation to support each prediction is symbolically referenced as shown in the last column. The documentation includes assumptions, calculations, references to the literature, laboratory data, computer simulation results, and other related material. Such a factorial table is first completed by each scientist independently. Subsequently, the team alms to generate a single consensus factorial table has the same form as that shown in Table II.

Air or water cooled mercury discharge lamps find many uses, one of the more obvious of which is the study of photochemical reactions. These lamps are usually made of vitreous silica because of its low thermal expansion, high melting point and its transparency to ultraviolet radiation. Their operating pressure has a profound effect on the spectral distribution of the radiation produced and therefore it is important to consider the requirements in the design of such lamps. 

Millward and Bihan [59] studied the effect of humic material on the determination of mercury by flameless atomic absorption spectrometry. In both fresh and seawater, association between inorganic and organic entities takes place within 90 min at pH values of 7 or above, and the organically bound mercury was not detected by an analytical method designed for inorganic mercury. The amount of detectable mercury was related to the amount of humic material added to the solutions. However, total mercury could be measured after exposure to ultraviolet radiation under strongly acid conditions. 

The anthracenylmethyl lariat ether shown as (10) was reported by de Silva and coworkers (1986) as a crown that is useful for fluorescence sensing. Binding of K+ resulted in a detectable fluorescence emission signal. Recent advances in this area include the development of compounds that can sense ion pairs. The anthracenyl crown shown as (11) was designed to simultaneously sense sodium and phosphate ions (de Silva, 2003). Excitation of the complex with ultraviolet radiation results in a fluorescent output only when Na+ is complexed in the crown and the ammonium groups are bound to the anion. The complex self-quenches in the case when either no or only one of the ions is present. 

Karentz, D. and Lutze, L. H., Evaluation of biologically harmful ultraviolet radiation in Antarctica with a biological dosimeter designed for aquatic environments, Limnol. Oceanogr., 35, 549, 1990. 

By far, the most detrimental factors influencing adhesives aged in a nonseacoast environment are heat and humidity. The reasons why warm, moist climates degrade many adhesive joints were presented in the last section. Near the seacoast, corrosion due to salt water and salt spray must also be considered when one is designing an adhesive joint. Thermal cycling due to weather, oxygen, ultraviolet radiation, and cold are relatively minor factors with most structural adhesives. 

Radiation-induced fatigue has received considerable attention. Polymers used in photoreceptors generally absorb only in the ultraviolet. Donor or acceptor molecules may absorb into the blue. Generation materials are designed to absorb throughout the visible and into the near infrared. Exposure to ultraviolet radiation can lead to irreversible changes due to transport-layer photochemistry. In fact, such chemistry has been used for many years in the production of... 

The average shore A hardness of the cured sealant is 20 to 25 but increases with ageing. Resistance to ultraviolet radiation is excellent, but this is not important for indoor applications. The maximum movement accommodation factor (MAF) can be 15% of the total joint width. Joints should be designed so that movement due to shrinkage and thermal changes does not exceed the maximum MAF, related to the joint width. Table 5.4 lists the properties in general for acrylic emulsion sealants. These properties are summarised from the commercial literature of several acrylic emulsion sealant manufacturers and should not be considered as specifications. Table 5.5 lists the standard specifications for these sealants. 

A low-pressure mercury lamp sold by Westinghouse under the trade-mark, Sterilamp, was placed on the market in 1936. The lamp was primarily designed to emit a copious amount of bactericidal ultraviolet radiation with a minimum amount of radiation below 2000 A. The latter radiation is responsible for the photochemical production of ozone from oxygen of the air. The effectiveness of the lamp in destroying bacteria (2S) and mold 21) on Petri plates, in operating rooms 17,18), bacteriological laboratories 32), and air-conditioning systems 22, 24) has been amply demonstrated. 

Although rickets was first described in the mid-1600s, it was not until the 1920s that deficiency of vitamin D was recognized as its cause. Despite its designation as a vitamin, dietary vitamin D is needed only if a person receives inadequate exposure to sunlight. Normally, vitamin D3 is synthesized in the skin by irradiation of 7-dehydrocholesterol (Figure 37-1). Sufficient exposure to ultraviolet radiation can cure rickets. 

Compared with acrylic glass, polystyrene has a lower light stability and resistance to ultraviolet radiation. The slight degradation when exposed to ultraviolet radiation is a disadvantage that occurs with all optical plastics. The higher refractive index of polystyrene permits its use in conjunction with acrylic lenses for the design of colour-... 

An example of the former is the ultraviolet spectrophotometer which may be of fixed wavelength (usually 254 or 280 nm) or variable wavelength design. The detector functions by monitoring the change in absorbance as the solute passes through the detector flow cell, i.e. it utilises the specific property of the solute to absorb ultraviolet radiation. 

Infrared Absorption Detectors. Two types of infrared detectors have been offered commercially. The first is a filter instrument similar in design to that shown in Figure 16-13. The second, and more sophisticated, type of infrared detector is based on Fourier transform instruments similar to those discussed in Section I6B-1. Several of the manufacturers of Fourier transform infrared (FTIR) instruments offer accessories that permit their use as HPLC detectors. Infrared detector cells are similar in construction to those used with ultraviolet radiation except that windows arc constructed of sodium chloride or calcium fluoride. Cell path lengths range from 0.2 to 1.0 mm and volumes from 1.5 to 10 pL. 

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