Proportion Of Blue Light Research Articles

Light Transmittance by Apple Leaves and Canopies

Light transmittance and reflectance of sun and shade leaves of apple (cv. Golden Delicious) were measured from May to September over the 380-700 nm wavelength range. The mean light absorptance over the range 400-700 nm of both leaf types was in excess of 85%0 except in May, when the leaves were immature and bright green. Sun leaves had a greater specific leaf weight and a lower transmittance than shade leaves. Reflectance of the two leaf types was similar. The proportion of visible to near infra-red radiation decreased beneath hedgerow orchards. Within patches of shade in the visible waveband, the proportion of blue light was increased and that of red decreased.

Studies in Wool Yellowing

Changes in the yellowness of wool during exposure to sunlight or to an artificial source resembling sunlight (the Xenotest) depend not only on the relative proportions of blue light and uv radiation, which cause partial bleaching and yellowing, respectively, but also on the exposure period and on the initial natural yellowness of the sample. The bleaching reaction is rapid and short-lived and is most pronounced with deeply yellow wools, whereas uv yellowing is more apparent with paler specimens and is sustained throughout irradiation. Even with the deeply yellow samples, the uv yellow ing reaction eventually supervenes and proceeds at a similar rate for all wools, although the level of yellowness at any particular stage of irradiation varies from one wool to another. A linear relationship exists between the initial natural yellowness of scoured wool and the change in yellowness during Xenotest irradiation for any particular period. Action spectra for changes in shade of naturally yellow wool and of wool after yellow ing in the laboratory by either uv radiation, dry heat, or hot alkaline buffer are similar. yellowness increasing to a maximum with decrease in wavelength down to 300-320 mμ (the lowest waveband examined) and decreasing to a minimum at 440-460 mμ in the blue region. However, the absorption spectra determined by the o-dichlorobenzene immersion method differ and so, in general, do the changes in yellowness during irradiation in the Xenotest. Natural yellowness is more likely to be attributable to the deposition of a thin pigment layer at the surface of the wool fiber than to the effects of uv radiation, heat, or alkaline conditions while on the sheep. This important difference in the distribution of pigment between natural and artificially yellowed wools may suggest new methods of improving the color of wool.

The Production of Fruit Bodies in Collybia velutipes III. Influence of the quality of light

Collybia velutipes is known to develop primordia as well as stipes in darkness while the growth of the pileus is greatly stimulated even by weak light (Akai 1940, Plunkett 1953, 1956, Aschan 1954, Takemuru 1954). In those cases where similar effects in other basidiomycetes have been studied in respect to their wave‐length dependence blue light has generally been found most effective (see Marsh et al. 1959). The present author has observed well developed pilei in (Collybia cultures receiving only occasional illumination from a weak incandescent lamp. Such irradiance contains a rather low proportion of blue light, so that the question arose whether this fungus might deviate from the rule.

Professional Motion Picture Photography with High-Intensity Short-Life Incandescent Lamps<!--<xref ref-type="other" rid="fn1-10.5594_J02039">*</xref>-->

To increase the light output per watt, to improve the actinicity of the light, to increase the proportion of blue light badly needed for color photography, and to reduce the size and number and increase the output of the lighting units, tungsten lamp filaments are heated to temperatures as near the melting point as is practicable. Reference data are presented on lumen output, efficiency, color (energy) distribution, and lamp life. Practicable safe operating limits are indicated. A new “super photoflood” lamp is described and data on overvoltage lamp operation for location lighting are presented for reference.