Tailored preparation of porous aromatic frameworks in a confined environment.

The growth of porous aromatic frameworks (PAFs) on the surface of polymer brushes is reported for the first time. In contrast to PAFs formed in solution, polymer brushes provide a confined environment for PAF growth, resulting in nanosized and homogeneous spherical PAFs formed amongst the polymer brushes. 4-Bromobenzene functionalities from the polymer brushes are utilized to induce PAF growth by a Yamamoto-type Ullman coupling reaction. The size of PAFs can be tailored from 30 nm to 500 nm by subtly changing the structural parameters: e.g. reaction time, grafting density, and concentration of 4-bromobenzene on the surface. The established strategy is not only applicable to the preparation of PAF-1, but can also be extended to the controlled preparation of PAF-5. In addition, free-standing and flexible PS/PAF-1 hybrid membranes are obtained via dissolving the oxidized layer between the polymer layer and the silicon substrate, which can be transferred to any flat substrate. The obtained PS/PAF-1 membrane is proven to show high efficiency in removing dye from water and is promising for eliminating other foulants, such as microorganisms and trace organics.

Self-assembled nanoparticles based on cationic mono-/AIE tetra-nuclear Ir(III) complexes: long wavelength absorption/near-infrared emission photosensitizers for photodynamic therapy.

Cyclometalated Ir(III) complexes as photosensitizers (PSs) have attracted widespread attention because of their good photostability and efficient 1O2 production ability. However, their strong absorption in the UV-vis region severely limits their applications in photodynamic therapy (PDT) because the short wavelength illuminating light can be easily absorbed by the skin and subcutaneous adipose tissue causing damage to the patient's normal tissue. Herein, mono- and tetra-nuclear Ir(III) complex-porphyrin conjugates are rationally designed and synthesized, especially [TPP-4Ir]4+ exhibits obvious aggregation-induced emission (AIE) characteristics. PSs comprising Ir(III) complex-porphyrin conjugates self-assembled as nanoparticles (NPs) are successfully achieved. The obtained [TPP-Ir]+ NPs and [TPP-4Ir]4+ NPs exhibit long wavelength absorption (500-700 nm) and near-infrared emission (635-750 nm), successfully overcoming the inherent defects of short wavelength absorption of traditional Ir(III) complexes. Moreover, [TPP-4Ir]4+ NPs exhibit good biocompatibility, high 1O2 generation ability, low half-maximal inhibitory concentration (IC50) (0.47 × 10-6 M), potent cytotoxicity toward cancer cells and superior cellular uptake under white light irradiation. This work extends the scope for transition metal complex PSs with promising clinical applications.

Kinetic Hydrate Inhibition of Natural Gels in Complex Sediment Environments.

Natural gels are emerging as a hotspot of global research for their greenness, environmental-friendliness, and good hydrate inhibition performance. However, previous studies mostly performed experiments for simple pure water systems and the inhibition mechanism in the sediment environment remains unclear. Given this, the inhibition performance of xanthan gum and pectin on hydrate nucleation and growth in sediment environments was evaluated via hydrate formation inhibition tests, and the inhibition internal mechanisms were revealed via a comprehensive analysis integrating various methods. Furthermore, the influences of natural gels on sediment dispersion stability and low-temperature fluid rheology were investigated. Research showed that the sediments of gas hydrate reservoirs in the South China Sea are mainly composed of micro-nano quartz and clay minerals. Xanthan gum and pectin can effectively inhibit the hydrate formation via the joint effects of the binding, disturbing, and interlayer mass transfer suppression processes. Sediments promote hydrate nucleation and yet inhibit hydrate growth. The interaction of sediments with active groups of natural gels weakens the abilities of gels to inhibit hydrate nucleation and reduce hydrate formation. Nonetheless, sediments help gels to slow down hydrate formation. Our comprehensive analysis pointed out that pectin with a concentration of 0.5 wt% can effectively inhibit the hydrate nucleation and growth while improving the dispersion stability and low-temperature rheology of sediment-containing fluids.

A highly agricultural river network in Jurong Reservoir watershed as significant CO2 and CH4 sources.

Freshwaters are receiving growing concerns on atmospheric carbon dioxide (CO2) and methane (CH4) budget; however, little is known about the anthropogenic sources of CO2 and CH4 from river network in agricultural-dominated watersheds. Here, we chose such a typical watershed and measured surface dissolved CO2 and CH4 concentrations over 2 years (2015-2017) in Jurong Reservoir watershed for different freshwater types (river network, ponds, reservoir, and ditches), which located in Eastern China and were impacted by agriculture with high fertilizer N application. Results showed that significantly higher gas concentrations occurred in river network (CO2: 112 ± 36 µmol L-1; CH4: 509 ± 341 nmol L-1) with high nutrient concentrations. Dissolved CO2 and CH4 concentrations were supersaturated in all of the freshwater types with peak saturation ratios generally occurring in river network. Temporal variations in the gas saturations were positively correlated with water temperature. The saturations of CO2 and CH4 were positively correlated with each other in river network, and both of these saturations were also positively correlated with nutrient loadings, and negatively correlated with dissolved oxygen concentration. The highly agricultural river network acted as significant CO2 and CH4 sources with estimated emission fluxes of 409 ± 369 mmol m-2 d-1 for CO2 and 1.6 ± 1.2 mmol m-2 d-1 for CH4, and made a disproportionately large, relative to the area, contribution to the total aquatic carbon emission of the watershed. Our results suggested the aquatic carbon emissions accounted for 6% of the watershed carbon budget, and fertilizer N and watersheds land use played a large role in the aquatic carbon emission.

Surface nitrous oxide concentrations and fluxes from water bodies of the agricultural watershed in Eastern China.

Agriculture is one of major emission sources of nitrous oxide (N2O), an important greenhouse gas dominating stratospheric ozone destruction. However, indirect N2O emissions from agriculture watershed water surfaces are poorly understood. Here, surface-dissolved N2O concentration in water bodies of the agricultural watershed in Eastern China, one of the most intensive agricultural regions, was measured over a two-year period. Results showed that the dissolved N2O concentrations varied in samples taken from different water types, and the annual mean N2O concentrations for rivers, ponds, reservoir, and ditches were 30 ±â€¯18, 19 ±â€¯7, 16 ±â€¯5 and 58 ±â€¯69 nmol L-1, respectively. The N2O concentrations can be best predicted by the NO3--N concentrations in rivers and by the NH4+-N concentrations in ponds. Heavy precipitation induced hot moments of riverine N2O emissions were observed during farming season. Upstream waters are hot spots, in which the N2O production rates were two times greater than in non-hotspot locations. The modeled watershed indirect N2O emission rates were comparable to direct emission from fertilized soil. A rough estimate suggests that indirect N2O emissions yield approximately 4% of the total N2O emissions yield from N-fertilizer at the watershed scale. Separate emission factors (EF) established for rivers, ponds, and reservoir were 0.0013, 0.0020, and 0.0012, respectively, indicating that the IPCC (Inter-governmental Panel on Climate Change) default value of 0.0025 may overestimate the indirect N2O emission from surface water in eastern China. EF was inversely correlated with N loading, highlighting the potential constraints in the IPCC methodology for water with a high anthropogenic N input.

[Characteristics and Source Analysis of Carbonaceous Components of PM2.5 During Autumn in the Northern Suburb of Nanjing].

In this study, PM2.5 samples were collected from October to November of 2015 in the northern suburb of Nanjing. The mass concentrations of organic carbon (OC), elemental carbon (EC), and levoglucosan in the samples were analyzed by thermal optical transmittance (TOT) and ion chromatography. The average concentrations of OC and EC were respectively (11.3±4.9) µg·m-3 and (1.1±0.9) µg·m-3. The average total carbon (TC) was 22.9%, and the OC/EC was 7.4. The quality concentrations of PM2.5, OC, EC, and SOC all reflected daytime features, and the correlation between OC and EC was better during the day than at night (correlation coefficients of 0.86 for day and 0.7 for night). By analyzing the mass concentrations of PM2.5, levoglucosan, and SOC, as well as the data of backward trajectories and fire point data, it was determined that the northern suburb of Nanjing is affected by the long-distance transportation of biomass from Hebei and other places from October 13-16. The correlations between levoglucosan and OC, EC, or SOC were significant (correlation coefficients of 0.78, 0.79, and 0.65, respectively), and the contribution of biomass combustion during sampling to OC was 21.9%.