Rural residential energy consumption in China is experiencing a rapid transition towards clean energy, nevertheless, solid fuel combustion remains an important emission source. Here we quantitatively ...evaluate the contribution of rural residential emissions to PM
(particulate matter with an aerodynamic diameter less than 2.5 μm) and the impacts on health and climate. The clean energy transitions result in remarkable reductions in the contributions to ambient PM
, avoiding 130,000 (90,000-160,000) premature deaths associated with PM
exposure. The climate forcing associated with this sector declines from 0.057 ± 0.016 W/m
in 1992 to 0.031 ± 0.008 W/m
in 2012. Despite this, the large remaining quantities of solid fuels still contributed 14 ± 10 μg/m
to population-weighted PM
in 2012, which comprises 21 ± 14% of the overall population-weighted PM
from all sources. Rural residential emissions affect not only rural but urban air quality, and the impacts are highly seasonal and location dependent.
With the purpose to investigate the influence of joint dip angle and spacing on the TBM rock-breaking efficacy and cracking behaviour, experiments that include miniature cutter head tests are carried ...out on sandstone rock material. In the experiment, prefabricated joints of different forms are made in rock samples. Then theoretical analysis is conducted to improve the calculating models of the fractured work and crack length of rock in the TBM process. The experimental results indicate that lower rupture angles appear for specimens with joint dip angles between 45° and 60°. Meanwhile, rock-breaking efficacy for rock mass with joint dip angles in this interval is also higher. Besides, the fracture patterns are transformed from compressive shear mode to tensile shear mode as the joint spacing decreases. As a result, failure in a greater extent is resulted for specimens with smaller joint spacings. The results above suggest that joint dip angle between 45° and 60° and joint spacing of 1 cm are the optimal rock-breaking conditions for the tested specimens. Combining the present experimental data and taking the joint dip angle and spacing into consideration, the calculating model for rock fractured work that proposed by previous scholars is improved. Finally, theoretical solution of rock median and side crack length is also derived based on the analytical method of elastoplastic invasion fracture for indenter. The result of the analytical solution is also in good agreement with the actual measured experimental result. The present study may provide some primary knowledge about the rock cracking character and breaking efficacy under different engineering conditions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Tubings in injection and production wells of gas storage serve as dual channels in the process of gas injection and production. However, buckling behavior is prone to occur for the tubing in the ...complicated mechanical environment due to the large volume of gas injection and production, long operation time, forcible injection and production, and multi-cycle injection and production of gas storage, thus increasing the risk of tubing failure. Therefore, a theoretical model of tubing stress and deformation in gas storage under multi-cycle injection-production was established with reference to the operation characteristics of reservoir type gas storage, and the buckling behavior was judged and analyzed for the actual injection and production wells of a Gas Storage. The results show that: i) Buckling deformation may occur to the strings under the combined action of the internal and external pressure, temperature effect, swelling force and compressive force, with the maximum buckling ranging from sinusoidal buckling
In this article, an ultrahigh step-up quadratic boost converter based on coupled-inductor is proposed. The voltage gain of the proposed converter can be enhanced significantly by increasing the duty ...cycle due to the quadratic boost structure. A coupled-inductor integrated with a voltage doubler cell is applied to further improve conversion ratio and reduce voltage stresses. The leakage inductor current is utilized to achieve zero-current switching for output diode . Meanwhile, high efficiency is possible as the energy of the leakage inductor is recycled and transferred to the load. The operating principle and steady-state analysis are provided, and a 280-W prototype is designed to verify the validity of the proposed converter.
As the demand for urban flood prevention and drainage increases, a large number of plastic rainwater facilities are in use. Microplastics will be released inevitably into stormwater systems during ...aging and hydraulic scouring processes, which could cause potential pollution risk. This study simulated the release behavior of microplastics from three typical plastic rainwater facilities including a rainwater inspection well, rainwater storage module, and rainwater pipe (mainly composed of high-density polyethylene, polypropylene, and polyvinyl chloride, respectively) under the effects of aging and hydraulic scouring. After 15–45 days of UV aging and 72 h of hydraulic scouring, the surfaces of the three facilities were found to exhibit increases in roughness, cracks, folds, and cavities, with the most pronounced changes occurring in the rainwater storage module. As the aging time increased, oxygen-containing functional groups formed and led to carbon chain scission. Fourier transform infrared spectroscopy (FTIR), two-dimensional correlation spectroscopy (2D-COS) and X-ray photoelectron spectroscopy (XPS) of facility surfaces showed that the formation of oxygen-containing functional groups was an important factor affecting the release of microplastics. The amount of microplastics released from the three facilities ranged from 160 to 1905 items/g (microplastics/facilities), following in the order of rainwater inspection well > rainwater storage module > rainwater pipe. The particle size of the released microplastics ranged from 3 to 1363 μm, with 10–30 μm accounting for the greatest proportion of particles, 50.10%. The size of microplastics released from the rainwater inspection well and rainwater storage module increased with the aging degree, while the release from the rainwater pipe decreased. The release behavior depends mainly on the composition of the materials and the aging time. Thus, microplastics can be released from plastic rainwater facilities under suitable conditions. The results can be used to further evaluate microplastic pollution caused by urban rainwater facilities.
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•O-containing groups on facility surfaces are key to the release of microplastics.•Released microplastics range from 160 to 1905 items/g following HDPE>PP > PVC facility.•Released microplastics range from 3 to 1363 μm, predominant with 10–30 μm fraction.•Release of microplastics increases with aging time, especially for the small size.•Release of microplastic mainly depends on the composed materials and aging time.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Previously reported examples of electrochemical pseudocapacitors based on cheap metal oxides have suffered from the need to compromise between specific capacitance, rate capacitance, and ...reversibility. Here we show that NiO nanorod arrays on Ni foam have a combination of ultrahigh specific capacitance （2018 F/g at 2.27 A/g）, high power density （1536 F/g at 22.7 A/g）, and good cycling stability （only 8% of capacitance was lost in the first 100 cycles with no further change in the subsequent 400 cycles）. This resulted in an improvement in the reversible capacitance record for NiO by 50% or more, reaching 80% of the theoretical value, and demonstrated that a three-dimensional regular porous array structure can afford all of these virtues in a supercapacitor. The excellent performance can be attributed to the slim （〈 20 nm） rod morphology, high crystallinity, regularly aligned array structure and strong bonding of the nanorods to the metallic Ni substrate, as revealed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray diffraction （XRD）.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs ...remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface.
Abstract
Background
To build prediction models with radiomics features, clinical/conventional radiographic signs and combined scores for the discrimination of micropapillary or solid subtypes ...(high-risk subtypes) of lung adenocarcinoma.
Methods
This retrospective study enrolled 351 patients with and without high-risk subtypes. Least Absolute Shrinkage and Selection Operator (LASSO) regression with cross-validation was performed to determine the optimal features of radiomics model. Missing clinical data were imputed by Multiple Imputation with Chain Equations (MICE). Clinical model with radiographic signs was built and scores of both models were integrated to establish combined model. Receiver operating characteristics (ROC) curves, area under ROC curves and decision curve analysis (DCA) were plotted to evaluate the model performance and clinical application.
Results
Stratified splitting allocated 246 patients into training set. MICE for missing values obtained complete and unbiased data for the following analysis. Ninety radiomic features and four clinical/conventional radiographic signs were used to predict the high-risk subtypes. The radiomic model, clinical model and combined model achieved AUCs of 0.863 (95%CI: 0.817–0.909), 0.771 (95%CI: 0.713–0.713) and 0.872 (95%CI: 0.829–0.916) in the training set, and 0.849 (95%CI: 0.774–0.924), 0.778 (95%CI: 0.687–0.868) and 0.853 (95%CI: 0.782–0.925) in the test set. Decision curve showed that the radiomic and combined models were more clinically useful when the threshold reached 37.5%.
Conclusions
Radiomics features could facilitate the prediction of subtypes of lung adenocarcinoma. A simple combination of radiomics and clinical scores generated a robust model with high performance for the discrimination of micropapillary or solid subtype of lung adenocarcinoma.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Global atmospheric emissions of 16 polycyclic aromatic hydrocarbons (PAHs) from 69 major sources were estimated for a period from 1960 to 2030. Regression models and a technology split method were ...used to estimate country and time specific emission factors, resulting in a new estimate of PAH emission factor variation among different countries and over time. PAH emissions in 2007 were spatially resolved to 0.1° × 0.1° grids based on a newly developed global high-resolution fuel combustion inventory (PKU-FUEL-2007). The global total annual atmospheric emission of 16 PAHs in 2007 was 504 Gg (331–818 Gg, as interquartile range), with residential/commercial biomass burning (60.5%), open-field biomass burning (agricultural waste burning, deforestation, and wildfire, 13.6%), and petroleum consumption by on-road motor vehicles (12.8%) as the major sources. South (87 Gg), East (111 Gg), and Southeast Asia (52 Gg) were the regions with the highest PAH emission densities, contributing half of the global total PAH emissions. Among the global total PAH emissions, 6.19% of the emissions were in the form of high molecular weight carcinogenic compounds and the percentage of the carcinogenic PAHs was higher in developing countries (6.22%) than in developed countries (5.73%), due to the differences in energy structures and the disparities of technology. The potential health impact of the PAH emissions was greatest in the parts of the world with high anthropogenic PAH emissions, because of the overlap of the high emissions and high population densities. Global total PAH emissions peaked at 592 Gg in 1995 and declined gradually to 499 Gg in 2008. Total PAH emissions from developed countries peaked at 122 Gg in the early 1970s and decreased to 38 Gg in 2008. Simulation of PAH emissions from 2009 to 2030 revealed that PAH emissions in developed and developing countries would decrease by 46–71% and 48–64%, respectively, based on the six IPCC SRES scenarios.
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IJS, KILJ, NUK, PNG, UL, UM
Zinc-air batteries have recently attracted considerable interest owing to the larger storage capacity and lower cost compared to their lithium-ion counterparts. Electrode catalysts for the oxygen ...reduction reaction （ORR） and oxygen evolution reaction （OER） play a critical role in the operation of rechargeable zinc-air batteries. Herein, we report a simple and scalable strategy to fabricate porous carbon polyhedra using Zn-doped Co-based zeolitic imidazolate frameworks （ZnCo-ZIFs） as precursors. Strikingly, Zn doping leads to smaller Co nanoparticles and higher nitrogen content, which in turn enhances the ORR and OER activities of the obtained porous carbon polyhedra. The synergistic effect of the N-doped carbon and cobalt nanoparticles in the composite, the improved conductivity resulting from the high graphitization of carbon, and the large surface area of the porous polyhedral structure resulted in porous carbon polyhedra with excellent ORR and OER electrocatalytic activity in alkaline media. More importantly, air cathodes based on the optimal porous carbon polyhedra further exhibited superior performance to Pt/C catalysts in primary and rechargeable zinc-air batteries.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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