On the wing of the moth Trichoplusia orichalcea a prominent, apparently highly reflective, golden... more On the wing of the moth Trichoplusia orichalcea a prominent, apparently highly reflective, golden spot can be seen. Scales from this area of the wing exhibit a regular microstructure resembling a submicrometer herringbone pattern. We show that a diffraction process from this structure is responsible for the observed optical properties, such as directionality, brightness variations, polarization, and color.
Abstract High power pulsed-laser irradiation of semiconductor surfaces often results in the forma... more Abstract High power pulsed-laser irradiation of semiconductor surfaces often results in the formation of a permanent or transient periodic surface structure. A simple ellipsometer-based technique is discussed, which can be used to detect and characterize these structures in real time. The method produces much stronger signals than diffractometry and it is especially suited to the study of low amplitude transient surface features.
Biomaterials-Africa 2009, CSIR Convention Centre, Pretoria, South Africa, 20-22 September 2009 Mi... more Biomaterials-Africa 2009, CSIR Convention Centre, Pretoria, South Africa, 20-22 September 2009 Minimalistic or non-invasive diagnosis and treatment of skin disorders requires accurate information regarding skin optical properties. Spectrophotometric and Integrating Sphere (IS) methods are commonly used to extract information regarding absorption and scattering properties of samples, although in the field of skin optics the latter is used more widely. The aim of this study is to extract and compare absorption coefficients of liquid skin phantoms with these two methods.
The attenuation behaviour of two different types of skin-like phantoms representing the range of ... more The attenuation behaviour of two different types of skin-like phantoms representing the range of Skin Types I to VI were investigated and compared to real human skin. Intralipid and Pheroid TM artificial lipid membrane vesicles respectively were added to synthetic eumelanin concentrations ranging from 0.0044 to 0.13 mg/mL to produce skin-like phantoms. Spectrophotometric absorbance and transmittance measurements were performed. Results predicted some of the non-monotonic trends observed in real human skin, albeit shifted more towards the visible wavelength range. There exist however an underlying difference in interaction between the melanin and the Pheroid TM and Intralipid skin-like phantoms.
Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in... more Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in nature. The photosynthetic process is very much dependent on the aggregation state of the chlorophylls and secondary conformational structure of the apoproteins in the light-harvesting systems. The aim of this study was to test possible buffer influence on these in the light-harvesting complex (LHCII) of Photosystem II (PSII).
Paper presented at the 33rd Annual conference of South African Society for Atmospheric Sciences (... more Paper presented at the 33rd Annual conference of South African Society for Atmospheric Sciences (SASAS), 21-22 September 2017, Polokwane, South Africa.
On the wing of the moth Trichoplusia orichalcea a prominent, apparently highly reflective, golden... more On the wing of the moth Trichoplusia orichalcea a prominent, apparently highly reflective, golden spot can be seen. Scales from this area of the wing exhibit a regular microstructure resembling a submicrometer herringbone pattern. We show that a diffraction process from this structure is responsible for the observed optical properties, such as directionality, brightness variations, polarization, and color.
Abstract High power pulsed-laser irradiation of semiconductor surfaces often results in the forma... more Abstract High power pulsed-laser irradiation of semiconductor surfaces often results in the formation of a permanent or transient periodic surface structure. A simple ellipsometer-based technique is discussed, which can be used to detect and characterize these structures in real time. The method produces much stronger signals than diffractometry and it is especially suited to the study of low amplitude transient surface features.
Biomaterials-Africa 2009, CSIR Convention Centre, Pretoria, South Africa, 20-22 September 2009 Mi... more Biomaterials-Africa 2009, CSIR Convention Centre, Pretoria, South Africa, 20-22 September 2009 Minimalistic or non-invasive diagnosis and treatment of skin disorders requires accurate information regarding skin optical properties. Spectrophotometric and Integrating Sphere (IS) methods are commonly used to extract information regarding absorption and scattering properties of samples, although in the field of skin optics the latter is used more widely. The aim of this study is to extract and compare absorption coefficients of liquid skin phantoms with these two methods.
The attenuation behaviour of two different types of skin-like phantoms representing the range of ... more The attenuation behaviour of two different types of skin-like phantoms representing the range of Skin Types I to VI were investigated and compared to real human skin. Intralipid and Pheroid TM artificial lipid membrane vesicles respectively were added to synthetic eumelanin concentrations ranging from 0.0044 to 0.13 mg/mL to produce skin-like phantoms. Spectrophotometric absorbance and transmittance measurements were performed. Results predicted some of the non-monotonic trends observed in real human skin, albeit shifted more towards the visible wavelength range. There exist however an underlying difference in interaction between the melanin and the Pheroid TM and Intralipid skin-like phantoms.
Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in... more Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in nature. The photosynthetic process is very much dependent on the aggregation state of the chlorophylls and secondary conformational structure of the apoproteins in the light-harvesting systems. The aim of this study was to test possible buffer influence on these in the light-harvesting complex (LHCII) of Photosystem II (PSII).
Paper presented at the 33rd Annual conference of South African Society for Atmospheric Sciences (... more Paper presented at the 33rd Annual conference of South African Society for Atmospheric Sciences (SASAS), 21-22 September 2017, Polokwane, South Africa.
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