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Quality and Performance Tests for Dermal Drug Delivery Systems
Published in Tapash K. Ghosh, Dermal Drug Delivery, 2020
Margareth R.C. Marques, Tony Bennett, Gregory Fieldson
The test should be performed under diffuse, uniform illumination (natural or artificial daylight) under conditions that reduce shadows and non-spectral reflectance to a minimum. For topical semisolids it is performed either by examination of the material in a clear, colorless vial held against a white background, or by examination of a small portion of the sample removed from its container and placed on a clean white sheet of paper. If more contrast is needed, a black background may be used. Liquids should be examined in a clear, colorless vial held against a white or black background. In each case, lighting conditions should be carefully controlled. Suitable apparatus is described in the section 2.9.20 of the European Pharmacopoeia (EP 2019a).
Modelling and analysis of skin pigmentation
Published in Ahmad Fadzil Mohamad Hani, Dileep Kumar, Optical Imaging for Biomedical and Clinical Applications, 2017
Ahmad Fadzil Mohamad Hani, Hermawan Nugroho, Norashikin Shamsudin, Suraiya H. Hussein
Because the molar absorptivity of skin pigments are different and is a function of the light wavelength, it is hypothesized that the spectral reflectance of skin can be utilized to analyse skin pigments (chromophores) to find out the concentrations of melanin categories and concentration noninvasively because reflectance spectrum is influenced by dermal absorption. The dermal absorption itself is defined as the sum of skin pigment absorption which is wavelength-dependent. In summary, by knowing the contribution of skin pigments to the dermal absorption and other factors (i.e., scattering coefficients, skin thickness and anisotropy factor) we can determine melanin types and concentration in a non-invasive and objective manner.
Physics and characteristics of radiochromic films
Published in Indra J. Das, Radiochromic Film, 2017
Martin Butson, Gwi Cho, Simran Gill, Dane Pope
The XR T (therapy film) and XR R (diagnostic film) show distinct different spectra as shown in Figures 3.5 and 3.6. Figure 3.6 provided the spectral reflectance spectra for GAFchromic XR type R film measured by a reflectance spectrometer instead of a transmission photo spectrometer [14].
Scene through the eyes of an apex predator: a comparative analysis of the shark visual system
Published in Clinical and Experimental Optometry, 2018
Both the ocular pigmentation and the tapetal reflectance in the sandbar shark, Carcharhinus plumbeus differs in its two habitats, that is, a blue tapetal reflex is observed in clear‐water, shelf populations, compared to an orange‐green tapetal reflex observed in turbid‐water, estuary populations. This indicates that the coloured reflex elicited by the fundus may be tuned to match the predominant spectrum of light available in the habitat of each species.2009 The ability to vary tapetal spectral reflectance in C. plumbeus may be an adaptation to match ambient illumination (intensity and spectral composition) in a variety of light environments for the purposes of camouflage, in addition to increasing retinal illumination2009 (Figure 8A, B).
Multimodal imaging of tapetal like fundus reflex in a young male with cone dystrophy
Published in Clinical and Experimental Optometry, 2022
Dheepak Sundar M, Harpreet Kaur Narde, Rohan Chawla
The pathogenesis of TLR remains controversial and is primarily ascribed to outer retinal changes. Hashimoto et al.,6 in an OCT-based study, suggested that it was difficult to demarcate EZ and RPE at the level of TLR in Oguchi disease and hence attributed abnormal accumulation of rhodopsin in shortened outer-segments of photoreceptors as the possible cause of TLR based on the OCT finding. Yamada et al.7 also conveyed similar findings. Berendschot et al.8 showed increased spectral reflectance at the outer-segment level in X-linked RP carriers with TLR.