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Enhanced optical absorption in semiconductor nano- particles enabled by nearfield dielectric scattering

Nano Research 2017年第4期10卷 1292-1301页

作者： Kowsalya D. Rasamani jonathan j. foley iv Brittney Beidelman Yugang Sun Department of Chemistry Temple University 1901 North 13th Street Philadelphia Pennsylvania 19122 USA Department of Chemistry William Paterson University 300 Pompton Road Wayne New Jersey 07470 USA Department of Physics Bryn Mawr College 101 North Merion Avenue Bryn Mawr Pennsylvania 19010 USA

The optical absorption of semiconducting AgBr nanocubes is significantly increased by up to 5 times in the measured spectral range when they are bonded to the surface of dielectric SiO2 nanospheres through electrostatic interaction. The absorption enhancement factor depends on the wavelength and the size of the SiO2 nanoparticles （NPs）. Finite-difference time-domain calculations provide the nearfield intensity mapping of a heterostructure that is composed of a AgBr nanocube in close contact with a SiO2 nanosphere. The electric-field distributions indicate the field enhancement near the SiO2/AgBr interface due to light scattering and absorption enhancement in the AgBr nanocube, implying that the enhanced scattering nearfield increases the absorption cross section of the AgBr nanocube. The absorption cross-section spectra calculated using Mie theory agree with the experimental observations. This discovery sheds light on the utilization of dielectric spherical particles to increase the absorption in semiconductor NPs, thus improving the light-harvesting efficiency for solar-energy conversion.

关键词： enhanced scattering nearfield dielectric scattering absorption enhancement Mie theory

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Role of Turbulent Heat Fluxes over Land in the Monsoon over East Asia

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International j.urnal of Geosciences 2011年第4期2卷 420-431页

作者： Eungul Lee Carol C. Barford Christopher j. Kucharik Benj.min S. Felzer jonathan A. foley 不详

Atmospheric heat and moisture over land are fundamental drivers of monsoon circulations. However, these drivers are less frequently considered in explaining the development and overall intensity of monsoons than heat and moisture over the ocean. In this study, the roles of turbulent heat fluxes over land in the monsoon system over East Asia are examined using Climatic Research Unit observations and European Centre for Medium-Range Weather Forecasts reanalysis, and they are further explored using simulated sensible (H) and latent (LE) heat fluxes from an ecosystem model (Predicting Ecosystem Goods and Services Using Scenarios or PEGASUS). Changes in the H fluxes over the land during the pre-monsoon season (March-May: MAM) affect the differential heating between land and ocean, which in turn controls monsoon development. In j.ly, an intensified contrast of the mean sea level pressure between land and ocean is observed during the years of stronger land-sea H contrast in MAM, which results in enhanced onshore flows and more rainfall over southern East Asia. After monsoon onset, the contrast of H is influenced by monsoon rainfall through the cooling effect of precipitation on surface air temperature. During the monsoon season (j.ne-September: j.AS), LE fluxes are more important than H fluxes, since LE fluxes over land and ocean affect overall monsoon intensity through changes in the land-sea contrast of turbulent heat fluxes. Significantly increased monsoon rainfall over western East Asia is observed during the years of larger LE over the land in j.AS. In ecosystem modeling, we find that the monsoon can be weakened as potential (natural) vegetation is converted to bare ground or irrigated cropland. Simulated H fluxes in MAM and LE fluxes in j.AS over the land significantly decrease in irrigated crop and bare ground scenarios, respectively, which play crucial roles in controlling monsoon development and overall intensity.

关键词： Heat Fluxes Monsoons Land Cover/Land Use Changes Ecosystem Modeling East Asia

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MRI Classification of Subtalar j.int Osteoarthritis Using a Novel Scoring System

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Open j.urnal of Radiology 2020年第2期10卷 69-78页

作者： Razi Zaidi Rikin Hargunani Michele Callej. jonathan foley Andy Goldberg University Hospital Lewisham Lewisham High St London UK Royal National Orthopaedic Hospital Brockley Hill Stanmore UK Lothian NHS Waverleygate Waterloo Place Edinburgh UK UCL Institute of Orthopaedics & Musculoskeletal Science London UK MSK Lab Imperial College London UK London Ankle & Arthritis Centre Wellington Hospital London UK

Background: Plain radiography usual method to detect degeneration in the subtalar and talonavicluar j.ints. MRI is a better way to fully characterise non-ossified structures, such as articular cartilage, marrow tissue and synovial fluid and therefore detect changes of arthritis. The motivation behind this study was to develop a quantitative way to score arthritic changes to the subtalar and talonavicular j.ints using MRI. The developed system will then be used as a research tool and in the close assessment and monitoring of patients with hindfoot degenerative disease. Methods: The MRI scans of thirty consecutive subj.cts with foot and ankle pain were retrospectively evaluated. Images were interpreted independently by three musculoskeletal radiologists in order to determine intra-observer reliability as well as the inter-observer reliability of the score. Five features of osteoarthritis were scored in the Subtalar j.int and the Talonavicular j.int. These were cartilage morphology, subarticular marrow, subarticular cyst, marginal osteophytes and synovitis. Results: For the 30 MRI scans the mean score for the Subtalar j.int ranged from 11.7 to 14.4 and for the Talonavicular j.int ranged from 3.7 to 5.6. The inter-observer correlation for the Subtalar j.int between the three readers ranged between 0.53 and 0.83 for the individual features but overall was excellent at 0.76. For the Talonavicular j.int the total correlation was good at 0.67. The inter-observer ICC for the total score was 0.75 which showed excellent agreement between the three readers. The total intra-observer correlation was excellent. Conclusions: The current work has shown excellent reliability for the scoring system. It will be a useful tool to diagnose and monitor disease progression of the Subtalar and Talonavicluar j.ints.

关键词： Magnetic Resonance Imaging Subtalar Talonavicular Osteoarthritis Cartilage

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生活在土地上的人们:20世纪全球人口和耕地的变化

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AMBIO－人类环境杂志 2002年第3期31卷 251-257页

作者： Navin Ramankutty jonathan A.foley Nicholas j.Olej.iczak 谈明洪威斯康星州(Wisconsin)大学环境研究学院威斯康星州(Wisconsin)大学环境研究学院

本研究评述了20世纪全球耕地分布发生的主要变化。在20世纪,耕地基数大幅度减小,人均耕地从1900年的0.75hm^2/人下降到1990年的0.35hm^2/人。耕地流失的速度在不同的地方不一样:世界上超过一半的人口居住在发展中国家,他们丧失了人均耕... 详细信息

本研究评述了20世纪全球耕地分布发生的主要变化。在20世纪,耕地基数大幅度减小,人均耕地从1900年的0.75hm^2/人下降到1990年的0.35hm^2/人。耕地流失的速度在不同的地方不一样:世界上超过一半的人口居住在发展中国家,他们丧失了人均耕地面积的2/3。耕地的分布在20世纪90年代变得更不均衡,世界上80%的人口依靠低于0.35hm^2的人均耕地面积而生存。发展中国家农业产量的增长速度勉强跟上人口的增长速度。总的来说,由于全球粮食生产系统对昂贵的技术和全球粮食贸易的依赖程度不断增加,它正变得越来越易受区域性破坏的影响。

关键词： 20世纪人口耕地变化全球范围粮食

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