ABSTRACT Summary form only given. Over the last three decades of the 20 th century many experimen... more ABSTRACT Summary form only given. Over the last three decades of the 20 th century many experiments have demonstrated that the rate of spontaneous emission for an emitter is determined by its electromagnetic surrounding. This phenomenon has been usually studied for atoms or molecules placed in the vicinity of mirrors or in optical resonators. Furthermore, it is also well-known that the fluorescence lifetime of an emitter changes after being embedded in dielectric media where aside from a change in the refractive index, it experiences the local fields in the dielectric. For a spherical medium larger than the order of a wavelength it is known that the coupling to Mie modes of this dielectric resonator has a large influence on the emission rate of an emitter inside. However, when the medium becomes comparable or smaller than a wavelength one can no longer speak of resonator modes. Here we report on an experiment where we have studied the variation of the spontaneous emission rate as the dielectric medium surrounding an emitter is made smaller and smaller down to a few nanometers.
Studying the webs of the Chilean recluse spider made from the spider's peculiar ribbon silk, ... more Studying the webs of the Chilean recluse spider made from the spider's peculiar ribbon silk, we discovered a self-strengthening mechanism in junctions of two adhesive tapes that eliminates the weakness inherent in tape peeling.
Nanofibrils play a pivotal role in spider silk and are responsible for many of the impressive pro... more Nanofibrils play a pivotal role in spider silk and are responsible for many of the impressive properties of this unique natural material. However, little is known about the internal structure of these protein fibrils. We carry out polarized Raman and polarized Fourier-transform infrared spectroscopies on native spider silk nanofibrils and determine the concentrations of six distinct protein secondary structures, including β-sheets, and two types of helical structures, for which we also determine orientation distributions. Our advancements in peak assignments are in full agreement with the published silk vibrational spectroscopy literature. We further corroborate our findings with X-ray diffraction and magic-angle spinning nuclear magnetic resonance experiments. Based on the latter and on polypeptide Raman spectra, we assess the role of key amino acids in different secondary structures. For the recluse spider we develop a highly detailed structural model, featuring seven levels of st...
La presente invention concerne des compositions d'oxyde de graphene/polyamide, ainsi que des ... more La presente invention concerne des compositions d'oxyde de graphene/polyamide, ainsi que des procedes de preparation et d'utilisation des compositions. Le constituant oxyde de graphene des compositions presente un rapport C:O entre 3 et 20, et constitue de 0,01 % a 5,0 % en poids de la composition. Des constituants polyamide typiques comprennent des nylons de specialite tels que le PA-11 et le PA-12. Les compositions presentent une absorption d'eau reduite et une durabilite amelioree par rapport a des compositions de polyamide identiques par ailleurs exemptes du constituant oxyde de graphene. Les compositions sont particulierement utiles, par exemple, dans des tubes et des tuyaux flexibles utilises pour transporter du petrole et du gaz.
Wednesday, 2 November 2005 - 1:10 PM 357c. Studying Surfactant Aggregates on Metals by Atomic For... more Wednesday, 2 November 2005 - 1:10 PM 357c. Studying Surfactant Aggregates on Metals by Atomic Force Microscopy. Hannes C. Schniepp, Ho C. Shum, Dudley A. Saville, and Ilhan A. Aksay. Department of Chemical Engineering ...
International Journal of Oral & Maxillofacial Implants
A number of environmental and patient-related factors contribute to implant failure. A significan... more A number of environmental and patient-related factors contribute to implant failure. A significant fraction of these failures can be attributed to limited osseointegration resulting from poor bone healing responses. The overall goal of this study was to determine whether surface treatment of a titanium-aluminum-vanadium alloy (Ti-6Al-4V) implant material in combination with a biomimetic protein coating could promote the differentiation of attached osteoblastic cells. The specific aims of the study were to investigate whether osteoprogenitor cells cultured on a rigorously cleaned implant specimen showed a normal pattern of differentiation and whether preadsorbed fibronectin accelerated or enhanced osteoblast differentiation. Ti-6Al-4V disks were rigorously cleaned, passivated in nitric acid, and dry heat- sterilized; some of the disks were then coated with 1 nmol/L fibronectin. MC3T3 osteoprogenitor cells were then cultured on the pretreated disks for several weeks. Quantitative real...
ABSTRACT Summary form only given. Over the last three decades of the 20 th century many experimen... more ABSTRACT Summary form only given. Over the last three decades of the 20 th century many experiments have demonstrated that the rate of spontaneous emission for an emitter is determined by its electromagnetic surrounding. This phenomenon has been usually studied for atoms or molecules placed in the vicinity of mirrors or in optical resonators. Furthermore, it is also well-known that the fluorescence lifetime of an emitter changes after being embedded in dielectric media where aside from a change in the refractive index, it experiences the local fields in the dielectric. For a spherical medium larger than the order of a wavelength it is known that the coupling to Mie modes of this dielectric resonator has a large influence on the emission rate of an emitter inside. However, when the medium becomes comparable or smaller than a wavelength one can no longer speak of resonator modes. Here we report on an experiment where we have studied the variation of the spontaneous emission rate as the dielectric medium surrounding an emitter is made smaller and smaller down to a few nanometers.
Studying the webs of the Chilean recluse spider made from the spider's peculiar ribbon silk, ... more Studying the webs of the Chilean recluse spider made from the spider's peculiar ribbon silk, we discovered a self-strengthening mechanism in junctions of two adhesive tapes that eliminates the weakness inherent in tape peeling.
Nanofibrils play a pivotal role in spider silk and are responsible for many of the impressive pro... more Nanofibrils play a pivotal role in spider silk and are responsible for many of the impressive properties of this unique natural material. However, little is known about the internal structure of these protein fibrils. We carry out polarized Raman and polarized Fourier-transform infrared spectroscopies on native spider silk nanofibrils and determine the concentrations of six distinct protein secondary structures, including β-sheets, and two types of helical structures, for which we also determine orientation distributions. Our advancements in peak assignments are in full agreement with the published silk vibrational spectroscopy literature. We further corroborate our findings with X-ray diffraction and magic-angle spinning nuclear magnetic resonance experiments. Based on the latter and on polypeptide Raman spectra, we assess the role of key amino acids in different secondary structures. For the recluse spider we develop a highly detailed structural model, featuring seven levels of st...
La presente invention concerne des compositions d'oxyde de graphene/polyamide, ainsi que des ... more La presente invention concerne des compositions d'oxyde de graphene/polyamide, ainsi que des procedes de preparation et d'utilisation des compositions. Le constituant oxyde de graphene des compositions presente un rapport C:O entre 3 et 20, et constitue de 0,01 % a 5,0 % en poids de la composition. Des constituants polyamide typiques comprennent des nylons de specialite tels que le PA-11 et le PA-12. Les compositions presentent une absorption d'eau reduite et une durabilite amelioree par rapport a des compositions de polyamide identiques par ailleurs exemptes du constituant oxyde de graphene. Les compositions sont particulierement utiles, par exemple, dans des tubes et des tuyaux flexibles utilises pour transporter du petrole et du gaz.
Wednesday, 2 November 2005 - 1:10 PM 357c. Studying Surfactant Aggregates on Metals by Atomic For... more Wednesday, 2 November 2005 - 1:10 PM 357c. Studying Surfactant Aggregates on Metals by Atomic Force Microscopy. Hannes C. Schniepp, Ho C. Shum, Dudley A. Saville, and Ilhan A. Aksay. Department of Chemical Engineering ...
International Journal of Oral & Maxillofacial Implants
A number of environmental and patient-related factors contribute to implant failure. A significan... more A number of environmental and patient-related factors contribute to implant failure. A significant fraction of these failures can be attributed to limited osseointegration resulting from poor bone healing responses. The overall goal of this study was to determine whether surface treatment of a titanium-aluminum-vanadium alloy (Ti-6Al-4V) implant material in combination with a biomimetic protein coating could promote the differentiation of attached osteoblastic cells. The specific aims of the study were to investigate whether osteoprogenitor cells cultured on a rigorously cleaned implant specimen showed a normal pattern of differentiation and whether preadsorbed fibronectin accelerated or enhanced osteoblast differentiation. Ti-6Al-4V disks were rigorously cleaned, passivated in nitric acid, and dry heat- sterilized; some of the disks were then coated with 1 nmol/L fibronectin. MC3T3 osteoprogenitor cells were then cultured on the pretreated disks for several weeks. Quantitative real...
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