Raman spectroscopy of human teeth using integrated optical spectrometers

We have designed an arrayed-waveguide grating in silicon oxynitride technology for the detection of Raman signals from tooth enamel in the spectral region between 890 nm and 912 nm. The detected signals for both parallel and cross polarizations are used to distinguish between healthy and carious regions on the tooth surface of extracted human teeth. Our experimental results are in very good agreement with those achieved using conventional Raman spectrometers. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers

Low-resolution Raman spectroscopy over a wide spectral range with a single-diffraction order arrayed-waveguide grating

An integrated arrayed-waveguide grating (AWG) fabricated in silicon oxynitride (SiON) technology is used as the wavelength separation and selection element for Raman spectroscopy. With a spectral resolution of 5.5 nm and a free spectral range of 215 nm, the AWG enables wavelength separation of the full Raman fingerprint region in a single diffraction order without order overlap. It is demonstrated that Raman signal detection of cyclohexane with the AWG is feasible and that the information on position and relative intensities of the Raman bands of cyclohexane are preserved. A detailed description of the signal processing methodology to obtain AWG-based Raman measurements corrected for instrument response is presented. The Raman measurement based on the integrated intensity output of the device corresponds well to the expected relative intensity channel output of the AWG. Raman information based on band intensity ratios from the AWG channels is also preserved compared with the spectral integration of bands, with a maximum relative error of 9% attributed to some light that might have leaked from the channels to the device substrate. These results are a step towards the realization of a technology suitable for dedicated, low-cost, miniaturized Raman devices

Investigating the variation in CO[subscript 2] sequestration supply curves

CCS projects that can bring together all pieces of the system—capture, transport, and storage—at the lowest cost will likely be the first to become operational. We have modeled the cost per tonne of CO[subscript 2] of a geologic sequestration system that stores CO[subscript 2] in saline aquifers in the United States. The model includes aspects of capture, transport, storage, and finance, and we present the sensitivity of the model to various source- and sink-specific parameters. From our cost model we developed CO[subscript 2] sequestration supply curves for CO[subscript 2] sources within 100 miles of nine identified CO2 sinks in the Illinois Basin. The supply curves present the amount of CO[subscript 2] that can be sequestered under current economic and technical conditions at a given CO[subscript 2] price, and can and should be used by policy makers and commercial organizations to determine the most economical combinations of sources and sinks for CCS on national, regional, and local levels

Integrated optical confocal system for Raman spectroscopy

We have designed a polarization insensitive arrayed-waveguide grating as a wavelength-selective device for Raman spectroscopy of the skin. The integrated spectrometer was characterized. Experimental results are presented and compared with a simulation. We tested our device in a novel confocal arrangement with a similar device that was used for focusing the excitation signal onto the sample. Experimental results on the collection efficiency and volume are presented together with a demonstration of multi-wavelength imaging

Design of Low-loss Arrayed Waveguide Gratings for Applications in Integrated Raman Spectroscopy

An integrated low-loss arrayed waveguide grating is designed for Raman spectroscopy of the human skin. The device layout targets spectral analysis of Raman-scattered light for in vivo determination of water concentration in the stratum corneum

Jerarquías reproductivas: maternidad y desigualdad en el ejercicio de los derechos humanos de las mujeres

A partir da concepção contemporânea de direitos humanos, o texto discute os direitos reprodutivos e o exercício da maternidade. Após histórico e definição dos direitos reprodutivos e dos direitos sexuais, o artigo trata da maternidade voluntária, segura, socialmente amparada e prazerosa, para propor uma reflexão sobre 'hierarquias reprodutivas'. Defende-se que diferentes aspectos das mães - tal como raça, classe social, idade e parceria sexual - determinam a legitimidade e aceitação social destas maternidades, e, portanto, suas vivências. Quanto maior o número de aspectos 'negativos' presentes na mulher (ou casal) ao exercitar a maternidade e/ou a reprodução e cuidado com os filhos, mais próxima da base da pirâmide hierárquica estará e, ainda, maior dificuldade encontrará no exercício de seus direitos humanos. O texto conclui que são necessárias políticas públicas de suporte social à maternidade para as mulheres que assim escolham, indistintamente, visando promover o exercício de seus direitos humanos

Economic and energetic analysis of capturing CO[subscript 2] from ambient air

Capturing carbon dioxide from the atmosphere (“air capture”) in an industrial process has been proposed as an option for stabilizing global CO[subscript 2] concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO[subscript 2], making it cost competitive with mainstream CO[subscript 2] mitigation options like renewable energy, nuclear power, and carbon dioxide capture and storage from large CO[subscript 2] emitting point sources. We investigate the thermodynamic efficiencies of commercial separation systems as well as trace gas removal systems to better understand and constrain the energy requirements and costs of these air capture systems. Our empirical analyses of operating commercial processes suggest that the energetic and financial costs of capturing CO[subscript 2] from the air are likely to have been underestimated. Specifically, our analysis of existing gas separation systems suggests that, unless air capture significantly outperforms these systems, it is likely to require more than 400 kJ of work per mole of CO[subscript 2], requiring it to be powered by CO[subscript 2]-neutral power sources in order to be CO[subscript 2] negative. We estimate that total system costs of an air capture system will be on the order of $1,000 per tonne of CO[subscript 2], based on experience with as-built large-scale trace gas removal systems