In this paper, smart photovoltaic (SPV) devices, integrating both functions of solar cells and smart windows, was fabricated based on dye-sensitized solar cells using photochromic spiropyran derivatives SIBT as photosensitizers. SPV devices have self-regulated power conversion efficiency (PCE) and light transmission responding to the incident spectra due to the photoisomerization of SIBT. SIBT isomerize from closed-ring form to open-ring form under UV illumination, accompanied with enhanced visible light absorption and electron delocalization. Therefore, increased PCE and absorption in SPV devices were observed under UV treatment and the devices can be restored gradually to the initial status when kept in dark. The SPV devices have self-regulation of PCE and sunlight transmission responding to the changing sun spectra in different times of a day, providing a proper energy usage and a better sun-shading. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Abstract Modernization has been regarded as the best way to solve ecological and poverty problems in many arid and semi-arid areas around the world, but is inevitably accompanied by changes in land-use patterns that can lead to new socio-ecological feedbacks. How people and ecosystems of an area respond to such feedbacks determines whether the changes sustainable or not. In this paper, we describe resettlement of nomadic pastoralists in Alxa Left Banner of western Inner Mongolia. We identified the dominant biophysical limiting factor in this region (water resources), and used amount and efficiency of water use as indicators of the ecological impacts of pastoralism before and after resettlement. We also conducted semi-structured interviews with households to collect information about household income, expenditures, and agricultural production risks caused by water shortages to analyze the impacts of resettlement on their livelihood. We found that resettlement greatly increased the usage of water resources, reduced the efficiency of water use, and exacerbated regional water shortages. Although household income increased after settlement, subsistence costs also increased because water shortages increased production costs and risks. Our results suggest that in this arid grassland area of China, ecological resettlement policy is ecologically and economically unsustainable, and may exacerbate local ecological and social problems.
Fine particulate matter (PM2.5) is a significant health issue in Chinese megacities. However, little information is available regarding the PM2.5-bound toxic organics, especially their sources, atmospheric transformations, and health implications. In this study, we assessed the levels of polycyclic aromatic hydrocarbons (PAHs) and their nitrated, hydroxylated, and oxygenated derivatives (i.e., NPAHs, OHPAHs, and OPAHs, respectively) in PM2.5 collected in Beijing over a 1year period. The median concentration of 23 PAHs, 15 NPAHs, 16 OHPAHs, and 7 OPAHs in PM2.5 was 53.8, 1.14, 1.40, and 3.62ngm(-3), respectively. Much higher concentrations and mass percentages for all species were observed in the heating season, indicating a higher toxicity of PM2.5 during this period of time. Positive matrix factorization was applied to apportion the sources of PAHs and their derivatives. It was found that traffic emissions in the nonheating season, and coal combustion and biomass burning in the heating season, were the major primary sources of PAHs and their derivatives. Secondary formation, however, contributed significantly to the derivatives of PAHs (especially NPAHs and OPAHs) in the nonheating season, suggesting significant impacts of atmospheric transformation on the toxicity of PM2.5.
Much effort has been made for reducing nitrous oxide (N2O) emission in wastewater treatment processes. This paper presents an interesting way to minimize N2O in aerobic denitrification by strain Pseudomonas stutzeri PCN-1 with help of corn flour as cheaper additional carbon source. Experimental results showed that maximal N2O accumulation by strain PCN-1 was only 0.02% of removed nitrogen if corn flour was used as sole carbon source, which was significantly reduced by 52.07-99.81% comparing with others such as succinate, glucose, acetate and citrate. Sustained release of reducing sugar from starch and continuous expression of nosZ coding for N2O reductase contributed to the special role of corn flour as the ideal carbon source for strain PCN-1. Further experiments in sequencing batch reactors (SBRs) demonstrated similarly efficient nitrogen removal with much less N2O emission due to synergy of the novel strain and activated sludge, which was then confirmed by quantitative PCR analysis. (C) 2015 Elsevier Ltd. All rights reserved.
Following older debates in international relations literature concerning the relative importance of domestic versus systemic factors, newer debates emphasize interdependence among states and the complex interactions between systemic and domestic factors. As globalization and democratization advance, theories and empirical models of international politics have become more complicated. We present a systematic theoretical categorization of relationships between domestic and systemic variables. We use this categorization so that scholars can match their theory to the appropriate empirical model and assess the degree to which systemic factors affect their arguments. We also present two advances at the frontier of these empirical models. In one, we combine hierarchical models of moderating relationships with spatial models of interdependence among units within a system. In the other, we provide a model for analyzing spatial interdependence that varies over time. This enables us to examine how the level of interdependence among units has evolved. We illustrate our categorization and new models by revisiting the recent international political economy (IPE) debate over the relationship between trade policy and regime type in developing countries.
This paper presents an analysis for the impedance transformation ratio of microwave rectifier, implemented as an energy recycling unit suitable for RF outphasing transmitters. The experimental demonstration is realised by two single-ended microwave rectifiers with different impedance transformation ratios to separately replace the power-wasting resistive load of an isolating combiner in a multilevel LINC system. The measurement results show that the implemented rectifier can improve the overall efficiency of the multilevel LINC system from original 39.5 % to 46.7 % and 44.9 % respectively, without affecting linearity.
