ABSTRACT
The thylakoid membrane inside chloroplasts hosts the light-dependent reactions of photosynthesis. Its embedded protein complexes are responsible for light harvesting, excitation energy transfer, charge separation, and transport. In higher plants, when the illumination conditions vary, the membrane adapts its composition and nanoscale morphology, which is characterized by appressed and non-appressed regions known as grana and stroma lamellae, respectively. Here we investigate the nanophotonic regime of light propagation in chloroplasts of higher plants and identify novel mechanisms in the optical response of the thylakoid membrane. Our results indicate that the relative contributions of light scattering and absorption to the overall optical response of grana strongly depend on the concentration of the light-harvesting complexes. For the pigment concentrations typically found in chloroplasts, the two mechanisms have comparable strengths, and their relative value can be tuned by variations in the protein composition or in the granal diameter. Furthermore, we find that collective modes in ensembles of grana significantly increase light absorption at selected wavelengths, even in the presence of moderate biological disorder. Small variations in the granal separation or a large disorder can dismantle this collective response. We propose that chloroplasts use this mechanism as a strategy against dangerously high illumination conditions, triggering a transition to low-absorbing states. We conclude that the morphological separation of the thylakoid membrane in higher plants supports strong nanophotonic effects, which may be used by chloroplasts to regulate light absorption. This adaptive self-organization capability is of interest as a model for novel bioinspired optical materials for artificial photosynthesis, imaging, and sensing.
ABSTRACT
The authors present a case report of a nurse who worked from 1993 to 1996 in a Metabolic Radiotherapy Unit. Five years later she developed a SCC tumor on the base of IIIrd finger of right hand. The patient was operated in "Regina Elena Plastic Surgery Unit" of I.C.P. Hospital of Milan. A vein dorsal flap of the hand was performed after a radical excision of the skin tumour and excellent reconstructive and aesthetic results was obtained. The purpose of the present case report was to stimulate generals doctors, dermatologist, and plastic surgeons to carefully evaluate patients with cutaneous tumor, due to contamination of medical radiation dose during and after dispensing of radiopharmaceuticals.
Subject(s)
Carcinoma, Squamous Cell/surgery , Hand , Adult , Female , Humans , Plastic Surgery Procedures/methodsABSTRACT
In this paper the authors present their experience in the surgical treatment of gynecomastia; the different surgical techniques used (liposuction, adenomammectomy, liposuction associated with adenomammectomy) are compared bilaterally 42 patients (37 patients) were affected of bilateral gynecomastia, 5 patients monolateral only (age 18-38 years) were treated in the Department of Plastic and Reconstructive Surgery-Ca' Granda Hospital of Milan, from 1985 to 1991. 12 patients were treated by the adenomammectomy technique; plain liposuction alone was used in 4 patients only. The associated method (liposuction and adenomammectomy) was performed on 26 patients. The results obtained suggest that the associated method is usually the most effective, because esthetic results are excellent and post-operative complications are very low. In selected cases however the other techniques should be preferred, and the criteria of selection are discussed.
