A new polymer acceptor, naphthodiperylenetetraimide-vinylene (NDP-V), featuring a backbone of altenating naphthodiperylenetetraimide and vinylene units is designed and applied in all-polymer solar cells (all-PSCs). With this polymer acceptor, a new record power-conversion efficiencies (PCE) of 8.59% has been achieved for all-PSCs. The design principle of NDP-V is to reduce the conformational disorder in the backbone of a previously developed high-performance acceptor, PDI-V, a perylenediimide-vinylene polymer. The chemical modifications result in favorable changes to the molecular packing behaviors of the acceptor and improved morphology of the donor-acceptor (PTB7-Th: NDP-V) blend, which is evidenced by the enhanced hole and electron transport abilities of the active layer. Moreover, the stronger absorption of NDP-V in the shorter-wavelength range offers a better complement to the donor. All these factors contribute to a short-circuit current density (J(sc)) of 17.07 mA cm(-2). With a fill factor (FF) of 0.67, an average PCE of 8.48% is obtained, representing the highest value thus far reported for all-PSCs.
There is increasing evidence indicating the critical role of ammonia (NH3) in the formation of secondary aerosols. Therefore, high quality NH3 emission inventory is important for modeling particulate matter in the atmosphere. Unfortunately, without directly measured emission factors (EFs) in developing countries, using data from developed countries could result in an underestimation of these emissions. A series of newly reported EFs for China provide an opportunity to update the NH3 emission inventory. In addition, a recently released fuel consumption data product has allowed for a multisource, high resolution inventory to be assembled. In this study, an improved global NH3 emission inventory for combustion and industrial sources with high sectorial (70 sources), spatial (0.1 degrees X 0.1 degrees), and temporal (monthly) resolutions was compiled for the years 1960 to 2013. The estimated emissions from transportation (1.59 Tg) sectors in 2010 was 2.2 times higher than those of previous reports. The spatial variation of the emissions was associated with population, gross domestic production, and temperature. Unlike other major air pollutants, NH3 emissions continue to increase, even in developed countries, which is likely caused by an increased use of biomass fuel in the residential sector. The emissions density of NH3 in urban areas is an order of magnitude higher than in rural areas.
There is a potential for silver nanowires (AgNWs) to be inhaled, but there is little information on their health effects and their chemical transformation inside the lungs in vivo. We studied the effects of short (S-AgNWs; 1.5 mum) and long (L-AgNWs; 10 mum) nanowires instilled into the lungs of Sprague-Dawley rats. S- and L-AgNWs were phagocytosed and degraded by macrophages; there was no frustrated phagocytosis. Interestingly, both AgNWs were internalized in alveolar epithelial cells, with precipitation of Ag2S on their surface as secondary Ag2S nanoparticles. Quantitative serial block face three-dimensional scanning electron microscopy showed a small, but significant, reduction of NW lengths inside alveolar epithelial cells. AgNWs were also present in the lung subpleural space where L-AgNWs exposure resulted in more Ag+ve macrophages situated within the pleura and subpleural alveoli, compared with the S-AgNWs exposure. For both AgNWs, there was lung inflammation at day 1, disappearing by day 21, but in bronchoalveolar lavage fluid (BALF), L-AgNWs caused a delayed neutrophilic and macrophagic inflammation, while S-AgNWs caused only acute transient neutrophilia. Surfactant protein D (SP-D) levels in BALF increased after S- and L-AgNWs exposure at day 7. L-AgNWs induced MIP-1alpha and S-AgNWs induced IL-18 at day 1. Large airway bronchial responsiveness to acetylcholine increased following L-AgNWs, but not S-AgNWs, exposure. The attenuated response to AgNW instillation may be due to silver inactivation after precipitation of Ag2S with limited dissolution. Our findings have important consequences for the safety of silver-based technologies to human health.
BACKGROUND AND OBJECTIVES: Childhood obesity is increasing. However, little is known about the changes in di-etary factors and supportive facilities associated with childhood obesity. We aimed to document the changes in various dietary factors and supportive facilities and their associations with obesity among pre-school children. METHODS AND STUDY DESIGN: Among 42,531 children 4-5 years old, recruited between 2004 and 2013 in the Jiax-ing Birth Cohort, we examined the changes in the prevalence of various dietary factors and supportive facilities and overweight/obesity over 10 years. We used logistic regression to investigate the cross-sectional association between these factors and childhood overweight/obesity risk, adjusting for potential confounders. RESULTS: The prevalence of childhood overweight/obesity increased steadily from 11.8% (boy: 14.8%; girl: 9%) during 2004-2005 to 18% (boy: 21.4%%; girl: 15%) during 2012-2013. The prevalence of meal/snack frequency 3 times /day decreased substantially from 23% during 2004-2005 to 8% during 2012-2013, with more children having 5 times /day: from 32% to 45.6%. Children with a fair/bad appetite, compared with those with a good appetite, had a 45% (OR: 0.55; 95% CI: 0.49, 0.62) lower risk of overweight/obesity. Children with a meal frequency >=6 times/day (compared with 3 times/day) had a 0.12 (95% CI: 0.03, 0.2) higher BMI-z-score. CONCLUSIONS: The prevalence of childhood overweight/obesity has increased substantially within a decade in southeast China. A better appetite and greater eating frequency were associated with the increased prevalence.
Abstract Economic restructuring, energy planning and environmental protection are subject to inherent uncertainties in a compound system with competing decision objectives. Therefore, an inexact multi-objective programming model for regional economy-energy-environment system management has been developed to obtain absolutely “optimal” solutions. Under two comparative scenarios, three subsystems, six industries, four types of energy, and three kinds of air pollution were considered in an optimization model, and a net system benefit and trade-off analysis between subsystems was conducted. The methods of interval-parameter programming and multi-objective programming were incorporated into the model to tackle the uncertainties and complexities reflected in the case study. The model results indicated that the developed model could provide effective linkages among the economy-energy-environment systems and offer decision makers great insight into the reliability tradeoffs for the adjustment of the existing management policy.
Electric power system involves different fields and disciplines which addressed the economic system, energy system, and environment system. Inner uncertainty of this compound system would be an inevitable problem. Therefore, an inexact multistage fuzzy-stochastic programming (IMFSP) was developed for regional electric power system management constrained by environmental quality. A model which concluded interval-parameter programming, multistage stochastic programming, and fuzzy probability distribution was built to reflect the uncertain information and dynamic variation in the case study, and the scenarios under different credibility degrees were considered. For all scenarios under consideration, corrective actions were allowed to be taken dynamically in accordance with the pre-regulated policies and the uncertainties in reality. The results suggest that the methodology is applicable to handle the uncertainty of regional electric power management systems and help the decision makers to establish an effective development plan.
Highly time-resolved in situ measurements of airborne particles were conducted at Mt. Yulong (3410 m above sea level) on the southeastern edge of the Tibetan Plateau in China from 22 March to 14 April 2015. The detailed chemical composition was measured by a high-resolution time-of-flight aerosol mass spectrometer together with other online instruments. The average mass concentration of the submicron particles (PM1) was 5.7 +/- 5.4 mu g m(-3) during the field campaign, ranging from 0.1 up to 33.3 mu g m(-3). Organic aerosol (OA) was the dominant component in PM1, with a fraction of 68 %. Three OA factors, i.e., biomass burning organic aerosol (BBOA), biomass-burning-influenced oxygenated organic aerosol (OOA-BB) and oxygenated organic aerosol (OOA), were resolved using positive matrix factorization analysis. The two oxygenated OA factors accounted for 87% of the total OA mass. Three biomass burning events were identified by examining the enhancement of black carbon concentrations and the f(60) (the ratio of the signal at m/z 60 from the mass spectrum to the total signal of OA). Back trajectories of air masses and satellite fire map data were integrated to identify the biomass burning locations and pollutant transport. The western air masses from South Asia with active biomass burning activities transported large amounts of air pollutants, resulting in elevated organic concentrations up to 4-fold higher than those of the background conditions. This study at Mt. Yulong characterizes the tropospheric background aerosols of the Tibetan Plateau during pre-monsoon season and provides clear evidence that the southeastern edge of the Tibetan Plateau was affected by the transport of anthropogenic aerosols from South Asia.
Highly time-resolved in situ measurements of airborne particles were conducted at Mt. Yulong (3410 m above sea level) on the southeastern edge of the Tibetan Plateau in China from 22 March to 14 April 2015. The detailed chemical composition was measured by a high-resolution time-of-flight aerosol mass spectrometer together with other online instruments. The average mass concentration of the submicron particles (PM1) was 5.7 +/- 5.4 mu g m(-3) during the field campaign, ranging from 0.1 up to 33.3 mu g m(-3). Organic aerosol (OA) was the dominant component in PM1, with a fraction of 68 %. Three OA factors, i.e., biomass burning organic aerosol (BBOA), biomass-burning-influenced oxygenated organic aerosol (OOA-BB) and oxygenated organic aerosol (OOA), were resolved using positive matrix factorization analysis. The two oxygenated OA factors accounted for 87% of the total OA mass. Three biomass burning events were identified by examining the enhancement of black carbon concentrations and the f(60) (the ratio of the signal at m/z 60 from the mass spectrum to the total signal of OA). Back trajectories of air masses and satellite fire map data were integrated to identify the biomass burning locations and pollutant transport. The western air masses from South Asia with active biomass burning activities transported large amounts of air pollutants, resulting in elevated organic concentrations up to 4-fold higher than those of the background conditions. This study at Mt. Yulong characterizes the tropospheric background aerosols of the Tibetan Plateau during pre-monsoon season and provides clear evidence that the southeastern edge of the Tibetan Plateau was affected by the transport of anthropogenic aerosols from South Asia.
The organic component is the most abundant fraction of atmospheric submicron particles, while the formation mechanisms of secondary organic aerosol (SOA) are not fully understood. The effects of sulfate seed aerosols on SOA formation were investigated with a series of experiments carried out using a 9m(3) smog chamber. The presence of FeSO4 or Fe-2(SO4)(3) seed aerosols decreased SOA yields and increased oxidation levels in both ozonolysis and OH-oxidation of a-pinene compared to that in the presence of ZnSO4 or (NH4)(2)SO4. These findings were explained by metal-mediated aerosol-phase oxidation of organics: reactive radicals were generated on FeSO4 or Fe-2(SO4)(3) seed aerosols and reacted further with the organic mass. This effect would help to explain the high O/C ratios of organics in ambient particles that thus far cannot be reproduced in laboratory and model studies. In addition, the gap in the SOA yields between experiments with different seed aerosols was more significant in OH-oxidation experiments compared to ozonolysis experiments, while the gap in estimated O/C ratios was less obvious. This may have resulted from the different chemical compositions and oxidation levels of the SOA generated in the two systems, which affect the branching ratio of functionalization and fragmentation during aerosol oxidation.
The influence of water vapor on the electronic property of MoS2 field effect transistors (FETs) is studied through controlled experiments. We fabricate supported and suspended FETs on the same piece of MoS2 to figure out the role of SiO2 substrate on the water sensing property of MoS2. The two kinds of devices show similar response to water vapor and to different treatments, such as pumping in the vacuum, annealing at 500 K and current annealing, indicating the substrate does not play an important role in the MoS2 water sensor. Water adsorption is found to decrease the carrier mobility probably through introducing a scattering center on the surface of MoS2. The threshold voltage and subthreshold swing of the FETs do not change obviously after introducing water vapor, indicating there is no obvious doping and trap introducing effects. Long time pumping in a high vacuum and 500 K annealing show negligible effects on removing the water adsorption on the devices. Current annealing at high source-drain bias is found to be able to remove the water adsorption and set the FETs to their initial states. The mechanism is proposed to be through the hot carriers at high bias.
The rapid developments of ultra-intense and ultra-short laser offer the possibility to study laser driven ion acceleration with using solid density target. However, the prepulse and amplified spontaneous emission generated in the amplification can create preplasma at the target front by heating, melting and evaporating a portion of a solid density. The main pulse then interacts with the preplasma, which would be harmful to laser ion acceleration. Therefore, many methods have been developed to enhance the temporal contrast of high power laser system, such as saturable absorber, cross polarized wave generation (XPW) and plasma mirror. With many advantages, such as high conversion efficiency, introducing neither spatial nor spectral distortions, and easy setup compared with other mechanisms, XPW has been used to clean the femtosecond laser system. Besides that, the spectrum of the XPW pulse could be broadened by root 3 times under the best condition compared with the initial spectrum. It can solve the spectrum narrowing problem during the laser amplification to obtain ultra-short femtosecond laser pulse. Here, we experimentally investigate the output power, spectrum bandwidth and center wavelength shift of the generated cross-polarized wave according to the input pulse quadratic spectral phase.The femtosecond laser pulse in compact laser plasma accelerator system at Peking University is used to investigate the role of quadratic spectral phase in characterizing the two crystal cross-polarized generation. The Ti: Sapphire-based laser system has a central wavelength of 798 nm and bandwidth of 35.5 nm which allows the pulse to be compressed down to 40 fs duration (FWHM). Typical the input pulse energy of XPW is 150 mu J and the laser system operates well at 1 kHz repetition rate. The quadratic spectral phase can be increased by changing the position of compressor grating. The conversion efficiency, spectrum bandwidth and the central wavelength shift by changing the quadratic spectral phase are measured. The conversion efficiency is 17% when quadratic spectral phase phi(2) = 0, and decreases as quadratic spectral phase increases. The rapid decrease is caused by negative quadratic spectral phase. The spectrum bandwidth is 62 nm under the optimum condition, and the broadening effect exists when quadratic spectral phase is in a range of 280 fs(2) < phi(2) < 1400 fs(2). It is slowly blue-shifted when phi(2) > 0 and stays at 772 nm when phi(2) > 1 0 0 0 fs(2). It starts to be red-shifted when phi(2) < 0 and stays at 806 nm finally.In conclusion, with the increase of quadratic spectral phase, we observe the effects of conversion efficiency and spectrum bandwidth and the shift of central wavelength. Moreover, the influences of positive and negative quadratic spectral phase on characteristics of XPW are different. Our result shows that the negative quadratic spectral phaseis more effective at reducing the conversion efficiency and spectrum bandwidth than the positive one.
Abstract Economic restructuring, water resources management, population planning and environmental protection are subjects to inner uncertainties of a compound system with objectives which are competitive alternatives. Optimization model and water quality model are usually used to solve problems in a certain aspect. To overcome the uncertainty and coupling in reginal planning management, an interval fuzzy program combined with water quality model for regional planning and management has been developed to obtain the absolutely “optimal” solution in this study. The model is a hybrid methodology of interval parameter programming (IPP), fuzzy programing (FP), and a general one-dimensional water quality model. The method extends on the traditional interval parameter fuzzy programming method by integrating water quality model into the optimization framework. Meanwhile, as an abstract concept, water resources carrying capacity has been transformed into specific and calculable index. Besides, unlike many of the past studies about water resource management, population as a significant factor has been considered. The results suggested that the methodology was applicable for reflecting the complexities of the regional planning and management systems within the planning period. The government policy makers could establish effective industrial structure, water resources utilization patterns and population planning, and to better understand the tradeoffs among economic, water resources, population and environmental objectives.