2,235 research outputs found
Micro-optical Tandem Luminescent Solar Concentrators
Traditional concentrating photovoltaic (CPV) systems utilize multijunction
cells to minimize thermalization losses, but cannot efficiently capture diffuse
sunlight, which contributes to a high levelized cost of energy (LCOE) and
limits their use to geographical regions with high direct sunlight insolation.
Luminescent solar concentrators (LSCs) harness light generated by luminophores
embedded in a light-trapping waveguide to concentrate light onto smaller cells.
LSCs can absorb both direct and diffuse sunlight, and thus can operate as flat
plate receivers at a fixed tilt and with a conventional module form factor.
However, current LSCs experience significant power loss through parasitic
luminophore absorption and incomplete light trapping by the optical waveguide.
Here we introduce a tandem LSC device architecture that overcomes both of these
limitations, consisting of a PLMA polymer layer with embedded CdSe/CdS quantum
dot (QD) luminophores and InGaP micro-cells, which serve as a high bandgap
absorber on top of a conventional Si photovoltaic. We experimentally synthesize
CdSe/CdS QDs with exceptionally high quantum-yield (99%) and ultra-narrowband
emission optimally matched to fabricated III-V InGaP micro-cells. Using a Monte
Carlo ray-tracing model, we show the radiative limit power conversion
efficiency for a module with these components to be 30.8% diffuse sunlight
conditions. These results indicate that a tandem LSC-on-Si architecture could
significantly improve upon the efficiency of a conventional Si photovoltaic
module with simple and straightforward alterations of the module lamination
steps of a Si photovoltaic manufacturing process, with promise for widespread
module deployment across diverse geographical regions and energy markets
Behavioral and Enhanced Perinatal Intervention (B-EPIC): A Randomized Trial Targeting Tobacco Use among Opioid Dependent Pregnant Women
Background
Opioid use during pregnancy is a significant public health issue. The standard of care for treating opioid use disorder during pregnancy includes medications for opioid disorder (MOUD). However, tobacco use often goes unaddressed among pregnant women on MOUD. In 2018, our team received a National Institute on Drug Abuse (NIDA) funded R34 to conduct a three year-randomized trial to test the feasibility of a novel tobacco intervention for pregnant women receiving MOUD.
Aims
The aims of this study are: (1) to determine the impact of the B-EPIC intervention on maternal tobacco use and stage of change; (2) to determine the impact of B-EPIC on tobacco-related maternal and infant health outcomes including gestational age at birth, birthweight, NAS diagnosis and severity, and number of ear and respiratory infections during the first six months; (3) to compare healthcare utilization and costs incurred by pregnant patients that receive the B-EPIC intervention versus TAU.
Methods
We plan to enroll 100 pregnant women on MOUD for this randomized controlled trial (B-EPIC intervention n = 50 and treatment as usual n = 50). A major strength of this study is its wide range of health and economic outcomes assessed on mother, neonate and the infant.
Conclusions Despite the very high rates of smoking among pregnant women with OUD, there are few tobacco treatment interventions that have been tailored for this high - risk population. The overall goal of this study is to move towards a tobacco treatment standard for pregnant women receiving treatment for OUD
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Design Criteria for Micro-Optical Tandem Luminescent Solar Concentrators
Luminescent solar concentrators (LSCs) harness light generated by luminophores embedded in a light-trapping waveguide to concentrate onto smaller cells. LSCs can absorb both direct and diffuse sunlight, and thus can operate as flat plate receivers at a fixed tilt and with a conventional module form factor. However, current LSCs experience significant power loss through parasitic luminophore absorption and incomplete light trapping by the optical waveguide. Here, we introduce a tandem LSC device architecture that overcomes both of these limitations, consisting of a poly(lauryl methacrylate) polymer layer with embedded cadmium selenide core, cadmium sulfide shell (CdSe/CdS) quantum dot (QD) luminophores and an InGaP microcell array, which serves as high bandgap absorbers on the top of a conventional Si photovoltaic. We investigate the design space for a tandem LSC, using experimentally measured performance parameters for key components, including the InGaP microcell array, CdSe/CdS QDs, and spectrally selective waveguide filters. Using a Monte Carlo ray-tracing model, we compute the power conversion efficiency for a tandem LSC module with these components to be 29.4% under partially diffuse illumination conditions. These results indicate that a tandem LSC-on-Si architecture could significantly improve upon the efficiency of a conventional Si photovoltaic cell
Roadmap on optical energy conversion
For decades, progress in the field of optical (including solar) energy conversion was dominated by advances in the conventional concentrating optics and materials design. In recent years, however, conceptual and technological breakthroughs in the fields of nanophotonics and plasmonics combined with a better understanding of the thermodynamics of the photon energy-conversion processes reshaped the landscape of energy-conversion schemes and devices. Nanostructured devices and materials that make use of size quantization effects to manipulate photon density of states offer a way to overcome the conventional light absorption limits. Novel optical spectrum splitting and photon-recycling schemes reduce the entropy production in the optical energy-conversion platforms and boost their efficiencies. Optical design concepts are rapidly expanding into the infrared energy band, offering new approaches to harvest waste heat, to reduce the thermal emission losses, and to achieve noncontact radiative cooling of solar cells as well as of optical and electronic circuitries. Light–matter interaction enabled by nanophotonics and plasmonics underlie the performance of the third- and fourth-generation energy-conversion devices, including up- and down-conversion of photon energy, near-field radiative energy transfer, and hot electron generation and harvesting. Finally, the increased market penetration of alternative solar energy-conversion technologies amplifies the role of cost-driven and environmental considerations. This roadmap on optical energy conversion provides a snapshot of the state of the art in optical energy conversion, remaining challenges, and most promising approaches to address these challenges. Leading experts authored 19 focused short sections of the roadmap where they share their vision on a specific aspect of this burgeoning research field. The roadmap opens up with a tutorial section, which introduces major concepts and terminology. It is our hope that the roadmap will serve as an important resource for the scientific community, new generations of researchers, funding agencies, industry experts, and investors.United States. Department of Energy (DE-AC36-086038308
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Performance and Operation of the CMS Electromagnetic Calorimeter
The operation and general performance of the CMS electromagnetic calorimeter
using cosmic-ray muons are described. These muons were recorded after the
closure of the CMS detector in late 2008. The calorimeter is made of lead
tungstate crystals and the overall status of the 75848 channels corresponding
to the barrel and endcap detectors is reported. The stability of crucial
operational parameters, such as high voltage, temperature and electronic noise,
is summarised and the performance of the light monitoring system is presented
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