Abstract. As a class of brown carbon, organonitrogen compounds originating from the heterogeneous uptake of NH 3 by secondary organic aerosol (SOA) have received significant attention recently. In the current work, particulate organonitrogen formation during the ozonolysis of α-pinene and the OH oxidation of m-xylene in the presence of ammonia (34-125 ppb) was studied in a smog chamber equipped with a high resolution time-of-flight aerosol mass spectrometer and a quantum cascade laser instrument. A large diversity of nitrogen-containing organic (NOC) fragments was observed which were consistent with the reactions between ammonia and carbonyl-containing SOA. Ammonia uptake coefficients onto SOA which led to organonitrogen compounds were reported for the first time, and were in the range of ∼ 10 −3 -10 −2 , decreasing significantly to < 10 −5 after 6 h of reaction. At the end of experiments (∼ 6 h) the NOC mass contributed 8.9 ± 1.7 and 31.5 ± 4.4 wt % to the total α-pineneand m-xylene-derived SOA, respectively, and 4-15 wt % of the total nitrogen in the system. Uptake coefficients were also found to be positively correlated with particle acidity and negatively correlated with NH 3 concentration, indicating that heterogeneous reactions were responsible for the observed NOC mass, possibly limited by liquid phase diffusion. Under these conditions, the data also indicate that the formation of NOC can compete kinetically with inorganic acid neutralization. The formation of NOC in this study suggests that a significant portion of the ambient particle associated N may be derived from NH 3 heterogeneous reactions with SOA. NOC from such a mechanism may be an important and unaccounted for source of PM associated nitrogen. This mechanism may also contribute to the medium or long-range transport and wet/dry deposition of atmospheric nitrogen.

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Aims: To study the antimicrobial agents of the Bacillus velezensis strain HC6 and assess the application potential of B. velezensis HC6 in maize. Methods and Results: We applied a dual culture technique to test the antimicrobial activity of B. velezensis HC6 against bacteria and fungi of common contaminated crops. Bacillus velezensis HC6 showed antagonistic action on pathogenic fungi, including Aspergillus and Fusarium, as well as pathogenic bacteria (especially Listeria monocytogenes). When applied in maize, B. velezensis HC6 could also inhibit the growth of multiple pathogenic fungi and reduce their production of aflatoxin and ochratoxin. Three kinds of antimicrobial lipopeptides, including iturin, fengycin and surfactin were identified in B. velezensis HC6 culture supernatant by high-performance liquid chromatography and MALDI-TOF mass spectrometry. Iturin and fengycin showed obvious antimicrobial activity to the tested fungal strains. Conclusions: Bacillus velezensis HC6 produces three kinds of lipopeptides which showed antimicrobial activity against several common pathogenic fungi and bacteria. Bacillus velezensis HC6 is potential to be biocontrol bacteria in maize. Significance and Impact of the Study: Bacillus velezensis HC6 shows obvious antimicrobial activity to important crops pathogenic fungi which usually produce mycotoxins that are harmful to animal and human health. We demonstrate that three different types of lipopeptides produced by B. velezensis contributed to the antimicrobial activity. Bacillus velezensis HC6 has the potential to be effective biocontrol agent in crops.

a b s t r a c tThe scarcity of research on the interactive effects of multi-limiting resources has hampered the success in ecological restoration. The effects of water (W), nitrogen (N) and phosphorous (P) on the performance of a perennial shrub, Bauhinia faberi seedlings were studied through a full factorial experimental design. Eighteen treatments was involved including three water (W1: 10, W2: 20 and W3: 40% field capacity), two N (N1: 100 and N2: 280 mg N kg À1 soil) and three P (P1: 12, P2: 24 and P3: 48 mg P kg À1 soil) for 19 weeks in a greenhouse experiment. P strongly regulated the biomass allocation under severe drought stress. Elevated W and P with N1 or N2 level increased root surface area and length, root and shoot mass, water-use efficiency and tissue P concentration, but did not significantly decrease tissue N concentration. The interaction of N and P was significant. Compared to N1, N2 significantly decreased growth parameters at P1 and P2, slightly reduced them at P3, suggesting that P3 alleviated the negative effects of N2.Therefore, the interactive effects of soil N and P should be examined thoroughly in seedlings plantation sites in arid regions to avoid excess level of nitrogen. Crown

The switch from vegetative to reproductive growth is a major developmental transition in flowering plants, which depends on the balanced expression of the genes within a complex network that is controlled by both environmental and endogenous factors. Molecular regulation of flower development has been investigated extensively in model plants, particularly Arabidopsis. However, little is known about the mechanisms that regulate flowering in lotus. To analyse the molecular regulation of flowering in lotus, comparative transcript profiling was performed at two stages of bud development – the initial developmental stage (T1) and the fast developing stage (T2) – in the lotus cultivars ‘BG’ (B, temperate lotus) and ‘WR1’ (W, tropical lotus). A total of 140 504 368 high‐quality 100‐bp reads were obtained and aligned against the lotus reference genome. Of the 23 361 genes assembled, at least 88% of these transcripts were detected in each sample. These genes were significantly enriched in 40 Gene Ontology terms and 236 Kyoto Encyclopedia of Genes and Genomes pathways. Further comparisons of the transcripts in the four libraries revealed that 1808, 1330, 785, 702, 1954, and 2050 genes were differentially expressed between BT1 and BT2, WT1 and WT2, BT1 and WT1, BT2 and WT2, BT1 and WT2 and BT2 and WT1 samples, respectively. Analysis of the four libraries identified 147 lotus flowering‐time genes homologous to genes that control flowering‐time pathways in other plants. Differential regulation of the COP1, CCA1, LHY, CO‐LIKE, VIN3, GAI, and FT genes, which participate in the photoperiod, vernalization and gibberellic acid pathways, suggested that they might control the early flowering of lotus. The extensive transcriptome dataset should provide a foundation for comparative gene expression studies on the regulation of flowering in lotus. Comparative transcriptomic analysis detected several differentially expressed genes and potential candidate genes required for early flowering in lotus. These results provide new insight into the molecular mechanisms that regulate flowering in lotus.

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Abstract. A particle-phase relative rates technique is used to investigate the heterogeneous reaction between OH radicals and tris-2-butoxyethyl phosphate (TBEP) at 298 K by combining aerosol time-of-flight mass spectrometry (C-ToF-MS) data and positive matrix factor (PMF) analysis. The derived second-order rate constants (k2) for the heterogeneous loss of TBEP is (4.44 ± 0.45) × 10−12 cm3 molecule−1 s−1, from which an approximate particle-phase lifetime was estimated to be 2.6 (2.3–2.9) days. However, large differences in the rate constants for TBEP relative to a reference compound were observed when comparing internally and externally mixed TBEP/organic particles, and upon changes in the RH. The heterogeneous degradation of TBEP was found to be depressed or enhanced depending upon the particle mixing state and phase, highlighting the complexity of heterogeneous oxidation in the atmosphere. The effect of gas-particle partitioning on the estimated overall lifetime (gas + particle) for several organophosphate esters (OPEs) was also examined through the explicit modeling of this process. The overall atmospheric lifetimes of TBEP, tris-2-ethylhexyl phosphate (TEHP) and tris-1,3-dichloro-2-propyl phosphate (TDCPP) were estimated to be 1.9, 1.9 and 2.4 days respectively, and are highly dependent upon particle size. These results demonstrate that modeling the atmospheric fate of particle-phase toxic compounds for the purpose of risk assessment must include the gas-particle partitioning process, and in the future include the effect of other particulate components on the evaporation kinetics and/or the heterogeneous loss rates.

Abstract. The mixed-phase relative rates approach for determining aerosol particle organic heterogeneous reaction kinetics is often performed utilizing mass spectral tracers as a proxy for particle-phase reactant concentration. However, this approach may be influenced by signal contamination from oxidation products during the experiment. In the current study, the mixed-phase relative rates technique has been improved by combining a positive matrix factor (PMF) analysis with electron ionization aerosol mass spectrometry (unit-mass resolution), thereby removing the influence of m / z fragments from reaction products on the reactant signals. To demonstrate the advantages of this approach, the heterogeneous reaction between OH radicals and citric acid (CA) was investigated using a photochemical flow tube coupled to a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS). The measured heterogeneous rate constant (k2) of citric acid toward OH was (3.31 ± 0.29) × 10−12 cm3 molecule−1 s−1 at 298 K and (30 ± 3)% relative humidity (RH) and was several times greater than the results utilizing individual m / z fragments. This phenomenon was further evaluated for particulate-phase organophosphates (triphenyl phosphate (TPhP), tris-1,3-dichloro-2-propyl phosphate (TDCPP) and tris-2-ethylhexyl phosphate (TEHP)), leading to k2 values significantly larger than previously reported. The results suggest that heterogeneous kinetics can be significantly underestimated when the structure of the products is highly similar to the reactant and when a non-molecular tracer is measured with a unit-mass resolution aerosol mass spectrometer. The results also suggest that the heterogeneous lifetime of organic aerosol in models can be overestimated due to underestimated OH uptake coefficients. Finally, a comparison of reported rate constants implies that the heterogeneous oxidation of aerosols will be dependent upon a number of factors related to the reaction system, and that a single rate constant for one system cannot be universally applied under all conditions.