Nitryl chloride (ClNO2) is a dominant source of chlorine radical in polluted environment, and can significantly affect the atmospheric oxidative chemistry. However, the abundance of ClNO2 and its exact role are not fully understood under different environmental conditions. During the summer of 2014, we deployed a chemical ionization mass spectrometer to measure ClNO2 and dinitrogen pentoxide (N2O5) at a rural site in the polluted North China Plain. Elevated mixing ratios of ClNO2 (> 350 pptv) were observed at most of the nights with low levels of N2O5 (< 200 pptv). The highest ClNO2 mixing ratio of 2070 pptv (1 min average) was observed in a plume from a megacity (Tianjin), and was characterized with a faster N2O5 heterogeneous loss rate and ClNO2 production rate compared to average conditions. The abundant ClNO2 concentration kept increasing even after sunrise, and reached a peak 4 h later. Such highly sustained ClNO2 peaks after sunrise are discrepant from the previously observed typical diurnal pattern. Meteorological and chemical analysis shows that the sustained ClNO2 morning peaks are caused by significant ClNO2 production in the residual layer at night followed by downward mixing after breakup of the nocturnal inversion layer in the morning. We estimated that similar to 1.7-4.0 ppbv of ClNO2 would exist in the residual layer in order to maintain the observed morning ClNO2 peaks at the surface site. Observation-based box model analysis show that photolysis of ClNO2 produced chlorine radical with a rate up to 1.12 ppbv h(-1), accounting for 10-30% of primary ROx production in the morning hours. The perturbation in total radical production leads to an increase of integrated daytime net ozone production by 3% (4.3 ppbv) on average, and with a larger increase of 13% (11 ppbv) in megacity outflow that was characterized with higher ClNO2 and a relatively lower oxygenated hydrocarbon (OVOC) to non-methane hydrocarbon (NMHC) ratio.
Although efficient aerobic denitrification has received increasing attention, few studies have been made on simultaneous denitrification and phosphorus removal (SDPR) under aerobic condition. In this study, SDPR by an efficient aerobic denitrifier, Agrobacterium sp. LAD9, was firstly demonstrated. High nitrate and phosphorus removal rates of 7.50 and 1.02 mg L-1 h(-1) were achieved in wide range of O-2 concentration from 5.92 to 20.02 mg L-1. The N2O production would be inhibited as O-2 concentration exceeded 11.06 mg L-1, while the phosphorus removal efficiency would be generally improved with increasing O-2 concentration. N-15 mass spectrometry revealed that nitrogen removal accorded with the typical aerobic denitrification pathway, while P-31 nuclear magnetic resonance spectroscopy (P-31 NMR) indicated the fate of phosphorus to cells, extracellular polymeric substances (EPS), and polyphosphate (poly-P) of the denitrifier. EPS acted as a reservoir of phosphorus and the transformation of poly-P was dynamic and depended on initial orthophosphate (ortho-P) content. The aerobic SDPR would greatly simplify the conventional wastewater treatment processes which required separated considerations of nitrogen and phosphorus removal.
In the present investigation, we reported the fabrication of host networks formed by two newly prepared phenanthrene-butadiynylene macrocycles (PBMs) at the liquid-solid interface. Size, shape and concentration controlled experiments have been performed to investigate the PBMs/coronene (COR) host-guest system with the structural polymorphism phenomenon. Initially, PBM1 could form a regular linear network structure and PBM2 form a well-ordered nanoporous network structure. When the COR molecules were introduced, the self-assembled structure of PBM1 remained unchanged, while COR could be entrapped into the cavities of the PBM2 nanoporous network, and the co-assembly of the PBM2/COR host-guest systems underwent a structural transformation with the increase of concentration of COR. Scanning tunneling microscopy (STM) measurements and density functional theory (DFT) calculations are utilized to reveal the formation mechanism of the molecular nanoarrays controlled by the solution concentration.
Atmospheric size-fractionated particles were collected at different heights in an e-waste recycling zone (QY) and urban Guangzhou (GZ), China and analyzed for organophosphate flame retardants (OPFRs). The total air concentrations of eight OPFRs were 130 +/- 130 and 138 +/- 127 ng m(-3) in QY and GZ, respectively. Compositional profiles of chlorinated OPFRs were different between QY and GZ, but the size distribution patterns of all OPFRs were not significantly different at different heights. Estimated atmospheric deposition fluxes of OPFRs were 51 +/- 67 and 55 +/- 13 mu gm(-2) d(-1) in QY and GZ, respectively, and the coarse particles (D-p > 1.8 mu m) dominated both the dry and wet deposition fluxes. Moreover, not all particle-bound OPFRs were inhalable and deposited in the human respiratory tract. The calculated inhalation doses of OPFRs were much lower than the reference doses, suggesting that potential health risk due to inhalation exposure to particle-bound OPFRs in the e-waste recycling zone and urban site was low. (C) 2015 Elsevier B.V. All rights reserved.
We endogenize credit misallocation by introducing the government’s preference. The local government determines the credit subsidy to SOEs after a trade-off between SOEs’ profits and local aggregate outputs. Credit misallocation is more severe in regions where SOE share is high.
We consider the nonlinear Dirac (NLD) equation in (1 + 1) dimensions with scalar–scalar self interaction $\displaystyle \frac{{g}^{2}}{\kappa +1}{(\bar{{\rm{\Psi }}}{\rm{\Psi }})}^{\kappa +1}$ in the presence of external forces as well as damping of the form $f(x)-{\rm{i}}\mu {\gamma }^{0}{\rm{\Psi }}$, where both f and Ψ are two-component spinors. We develop an approximate variational approach using collective coordinates (CC) for studying the time dependent response of the solitary waves to these external forces. This approach predicts intrinsic oscillations of the solitary waves, i.e. the amplitude, width and phase all oscillate with the same frequency. The translational motion is also affected, because the soliton position oscillates around a mean trajectory. For $\kappa =1$ we solve explicitly the CC equations of the variational approximation for slow moving solitary waves in a constant external force without damping and find reasonable agreement with solving numerically the CC equations. We then compare the results of the variational approximation with no damping with numerical simulations of the NLD equation for $\kappa =1$, when the components of the external force are of the form ${f}_{j}={r}_{j}\mathrm{exp}(-{\rm{i}}{Kx})$ and again find agreement if we take into account a certain linear excitation with specific wavenumber that is excited together with the intrinsic oscillations such that the momentum in a transformed NLD equation is conserved.