It is generally believed that studies of liquid water using the generalized gradient approximation to density functional theory require dispersion corrections in order to obtain reasonably accurate structural and dynamical properties. Here, we report on an ab initio molecular dynamics study of water in the isothermal-isobaric ensemble using a converged discrete variable representation basis set and an empirical dispersion correction due to Grimme [J. Comp. Chem. 27, 1787 (2006)]. At 300 K and an applied pressure of 1 bar, the density obtained without dispersion corrections is approximately 0.92 g/cm(3) while that obtained with dispersion corrections is 1.07 g/cm(3), indicating that the empirical dispersion correction overestimates the density by almost as much as it is underestimated without the correction for this converged basis. Radial distribution functions exhibit a loss of structure in the second solvation shell. Comparison of our results with other studies using the same empirical correction suggests the cause of the discrepancy: the Grimme dispersion correction is parameterized for use with a particular basis set; this parameterization is sensitive to this choice and, therefore, is not transferable to other basis sets.

Replacing rigid metal oxides with flexible alternatives as a next-generation transparent conductor is important for flexible optoelectronic devices. Recently, nanowire networks have emerged as a new type of transparent conductor and have attracted wide attention because of their all-solution-based process manufacturing and excellent flexibility. However, the intrinsic percolation characteristics of the network determine that its fine pattern behavior is very different from that of continuous films, which is a critical issue for their practical application in high-resolution devices. Herein, a simple optimization approach is proposed to address this issue through the architectural engineering of the nanowire network. The aligned and random silver nanowire networks are fabricated and compared in theory and experimentally. Remarkably, network performance can be notably improved with an aligned structure, which is helpful for external quantum efficiency and the luminance of quantum dot light-emitting diodes (QLEDs) when the network is applied as the bottom-transparent electrode. More importantly, the advantage introduced by network alignment is also of benefit to fine pattern performance, even when the pattern width is narrowed to 30 μm, which leads to improved luminescent properties and lower failure rates in fine QLED strip applications. This paradigm illuminates a strategy to optimize nanowire network based transparent conductors and can promote their practical application in high-definition flexible optoelectronic devices.

The findings obtained in this study are useful for epidemiological studies to estimate the total personal exposure of children, and to develop appropriate control strategies for minimising the adverse health effects on school children.

Solution‐processed metal nanowire networks have attracted substantial attention as clear transparent conductive electrodes (TCEs) to replace metal oxides for low‐cost and flexible touch panels and displays. While targeting photovoltaic applications, TCEs are expected to be more hazy for enhancing light absorption in the active layer, but are still required to retain high transmittance and low sheet resistance. Balancing these properties (haze, transmittance, and conductivity) in TCEs to realize high performance but high haze simultaneously is a challenge because they are mutually influenced. Here, by precisely tailoring the diameter of thick–long silver nanowires using rapid radial electrochemical etching, high hazy flexible TCEs are fabricated with high figure of merit of up to 741 (4 Ω sq−1 at 88.4% transmittance with haze of 13.3%), surpassing those of commercialized brittle hazy metal oxides and exhibiting superiority for photovoltaic applications. Laminating such TCEs onto the perovskite solar cells as top electrodes, the obtained semitransparent devices exhibit power efficiencies up to 16.03% and 11.12% when illuminated from the bottom and top sides, respectively, outperforming reported results based on similar device architecture. This study provides a simple strategy for flexible and hazy TCEs fabrication, which is compatible with mild solution‐processed photovoltaic devices, especially those containing heat‐sensitive or chemical‐sensitive materials.

The isoscaling and isobaric ratio difference (IBD) methods are used to study the ∆µ/T (∆µ being the difference between the chemical potentials of neutron and proton, and T being the temperature) in the measured 1A GeV 124 Sn + 124 Sn, 112 Sn + 112 Sn, 136 Xe + Pb and 124 Xe + Pb reactions. The isoscaling phenomena in the 124 Sn/ 112 Sn and the 136 Xe/ 124 Xe reactions pairs are investigated, and the isoscaling parameter α and β are obtained. The ∆µ/T determined by the isoscaling method (IS-∆µ/T ) and IBD method (IB-∆µ/T ) in the measured Sn and Xe reactions are compared. It is shown that in most of fragments, the IS-and IB-∆µ/T are consistent in the Xe reactions, while the IS-and IB-∆µ/T are only similar in the less neutron-rich fragments in the Sn reactions. The shell effects in IB-∆µ/T are also discussed.

Photochemical smog, characterized by high concentrations of ozone (O) and fine particles (PM) in the atmosphere, has become one of the top environmental concerns in China. Volatile organic compounds (VOCs), one of the key precursors of O and secondary organic aerosol (SOA) (an important component of PM), have a critical influence on atmospheric chemistry and subsequently affect regional and global climate. Thus, VOCs have been extensively studied in many cities and regions in China, especially in the North China Plain, the Yangtze River Delta and the Pearl River Delta regions where photochemical smog pollution has become increasingly worse over recent decades. This paper reviews the main studies conducted in China on the characteristics and sources of VOCs, their relationship with O and SOA, and their removal technology. This paper also provides an integrated literature review on the formulation and implementation of effective control strategies of VOCs and photochemical smog, as well as suggestions for future directions of VOCs study in China.

Ammonia (NH 3 ) is the primary alkaline gas in the atmosphere that contributes to formation of secondary particles. Emission of NH 3 from vehicles, particularly gasoline powered light duty vehicles equipped with three-way catalysts, is regarded as an important source apart from emissions from animal wastes and soils, yet measured emission factors for motor vehicles are still not available in China, where traffic-related emission has become an increasingly important source of air pollutants in urban areas. Here we present our tunnel tests for NH 3 from motor vehicles under 'real world conditions' in an urban roadway tunnel in Guangzhou, a central city in the Pearl River Delta (PRD) region in south China. By attributing all NH 3 emissions in the tunnel to light-duty gasoline vehicles, we obtained a fuel-based emission rate of 2.92 ± 0.18 g L −1 and a mileage-based emission factor of 229.5 ± 14.1 mg km −1 . These emission factors were much higher than those measured in the United States while measured NO x emission factors (7.17 ± 0.60 g L −1 or 0.56 ± 0.05 g km −1 ) were contrastingly near or lower than those previously estimated by MOBILE/PART5 or COPERT IV models. Based on the NH 3 emission factors from this study, on-road vehicles accounted for 8.1% of NH 3 emissions in the PRD region in 2006 instead of 2.5% as estimated in a previous study using emission factors taken from the Emission Inventory Improvement Program (EIIP) in the United States.

Abstract. Agricultural residues are among the most abundant biomass burned globally, especially in China. However, there is little information on primary emissions and photochemical evolution of agricultural residue burning. In this study, indoor chamber experiments were conducted to investigate primary emissions from open burning of rice, corn and wheat straws and their photochemical aging as well. Emission factors of NO x , NH 3 , SO 2 , 67 non-methane hydrocarbons (NMHCs), particulate matter (PM), organic aerosol (OA) and black carbon (BC) under ambient dilution conditions were determined. Olefins accounted for > 50 % of the total speciated NMHCs emission (2.47 to 5.04 g kg −1 ), indicating high ozone formation potential of straw burning emissions. Emission factors of PM (3.73 to 6.36 g kg −1 ) and primary organic carbon (POC, 2.05 to 4.11 gC kg −1 ), measured at dilution ratios of 1300 to 4000, were lower than those reported in previous studies at low dilution ratios, probably due to the evaporation of semi-volatile organic compounds under high dilution conditions. After photochemical aging with an OH exposure range of (1.97-4.97) × 10 10 molecule cm −3 s in the chamber, large amounts of secondary organic aerosol (SOA) were produced with OA mass enhancement ratios (the mass ratio of total OA to primary OA) of 2.4-7.6. The 20 known precursors could only explain 5.0-27.3 % of the observed SOA mass, suggesting that the major precursors of SOA formed from open straw burning remain unidentified. Aerosol mass spectrometry (AMS) signaled that the aged OA contained less hydrocarbons but more oxygen-and nitrogencontaining compounds than primary OA, and carbon oxidation state (OS c ) calculated with AMS resolved O / C and H / C ratios increased linearly (p < 0.001) with OH exposure with quite similar slopes.