Simulation and optimisation of magnetic and experimental study of magnetic field coupling constructed wetland.

This study developed a novel constructed wetland (CW) coupled with a magnetic field for treating domestic wastewater, and the magnetic field distribution was solved and optimised by the finite element method. Herein, we investigated the effects of optimising magnetic field optimisation and studied its impact on CW treatment performance and the responses of a microbial community. The optimisation results showed that the average magnetic field strength of the CW unit increases from 3 to 8 mT, and the proportion of areas with magnetic field strength greater than 5 mT also increases from 30% to 74%. The water quality analysis results showed that the removal of chemical oxygen demand (COD) and NH4+-N (p < 0.01) was significantly increased by the magnetic field (average 3 mT), increasing by 12.2% and 8.49%, respectively. Moreover, the removal of COD and NH4+-N (p < 0.01) was more significantly increased by M-VFCW(O) (average 8 mT), increasing by 15.58% and 49.1%, respectively. The magnetic field application shifted significantly the abundance of dominant bacteria in CWs. Relative abundance of dominant bacteria such as Proteobacteria (63.3%), Firmicutes (4.72%) and Actinobacteria (2.11%) that played an important role in organics removal and nitrification and denitrification-related bacteria such as Nitrospirae (1.48%) and Planctomycetes (9.58%) significantly promoted in M-VFCW(O). These results suggest that introducing a magnetic field into CWs may improve organics and nitrogen removal via the biological process, and the optimisation of the magnetic field was significant in enhancing the performance of VFCWs.

Dihydroartemisinin engages liver fatty acid binding protein and suppresses metastatic hepatocellular carcinoma growth.

Dihydroartemisinin non-covalently binds liver fatty acid binding protein (FABP1) with micromolar affinity, acts as a FABP1-dependent peroxisome proliferator-activated receptor alpha agonist and inhibits metastatic hepatocellular carcinoma growth.

Chiral Iron Porphyrins Catalyze Enantioselective Intramolecular C(sp3 )-H Bond Amination Upon Visible-Light Irradiation.

Iron-catalyzed asymmetric amination of C(sp3 )-H bonds is appealing for synthetic applications due to the biocompatibility and high earth abundance of iron, but examples of such reactions are sparse. Herein we describe chiral iron complexes of meso- and ß-substituted-porphyrins that can catalyze asymmetric intramolecular C(sp3 )-H amination of aryl and arylsulfonyl azides to afford chiral indolines (29 examples) and benzofused cyclic sulfonamides (17 examples), respectively, with up to 93 % ee (yield: up to 99 %) using 410 nm light under mild conditions. Mechanistic studies, including DFT calculations, for the reactions of arylsulfonyl azides reveal that the Fe(NSO2 Ar) intermediate generated in situ under photochemical conditions reacts with the C(sp3 )-H bond through a stepwise hydrogen atom transfer/radical rebound mechanism, with enantioselectivity arising from cooperative noncovalent interactions between the Fe(NSO2 Ar) unit and the peripheral substituents of the chiral porphyrin scaffold.

Direct photo-induced reductive Heck cyclization of indoles for the efficient preparation of polycyclic indolinyl compounds.

The photo-induced cleavage of C(sp2)-Cl bonds is an appealing synthetic tool in organic synthesis, but usually requires the use of high UV light, photocatalysts and/or photosensitizers. Herein is described a direct photo-induced chloroarene activation with UVA/blue LEDs that can be used in the reductive Heck cyclization of indoles and without the use of a photocatalyst or photosensitizer. The indole compounds examined display room-temperature phosphorescence. The photochemical reaction tolerates a panel of functional groups including esters, alcohols, amides, cyano and alkenes (27 examples, 50-88% yields), and can be used to prepare polycyclic compounds and perform the functionalization of natural product analogues in moderate to good yields. Mechanistic experiments, including time-resolved absorption spectroscopy, are supportive of photo-induced electron transfer between the indole substrate and DIPEA, with the formation of radical intermediates in the photo-induced dearomatization reaction.

A soluble iron(II)-phthalocyanine-catalyzed intramolecular C(sp3)-H amination with alkyl azides.

Herein, we describe a soluble iron(II)-phthalocyanine, [FeII(tBu4Pc)(py)2] (Pc = phthalocyaninato(2-)), as an effective catalyst in intramolecular C(sp3)-H bond amination, with alkyl azides as the nitrogen source, to afford the amination products in moderate to excellent yields with a broad substrate scope.

Luminescent Platinum(II) Complexes with Bidentate Diacetylide Ligands: Structures, Photophysical Properties and Application Studies.

A series of platinum(II) complexes supported by terphenyl diacetylide as well as diimine or bis-N-heterocyclic carbene (NHC) ligands have been prepared. The diacetylide ligands adopt a cis coordination mode featuring non-planar terphenyl moieties as revealed by X-ray crystallographic analyses. The electrochemical, photophysical and photochemical properties of these platinum(II) complexes have been investigated. These platinum(II) diimine complexes show broad emission with peak maxima from 566 nm to 706 nm, with two of them having emission quantum yields >60% and lifetimes <2 µs in solutions at room temperature, whereas the platinum(II) diacetylide complexes having bis-N-heterocyclic carbene instead of diimine ligand display photoluminescence with quantum yields of up to 28% in solutions and excited state lifetimes of up to 62 µs at room temperature. Application studies revealed that one of the complexes can catalyze photoinduced aerobic dehydrogenation of alcohols and alkenes, and a relatively non-toxic water-soluble Pt(II) complex displays anti-angiogenic activity.

RuV -Acylimido Intermediate in [RuIV (Por)Cl2 ]-Catalyzed C-N Bond Formation: Spectroscopic Characterization, Reactivity, and Catalytic Reactions.

Metal-catalyzed C-N bond formation reactions via acylnitrene transfer have recently attracted much attention, but direct detection of the proposed acylnitrenoid/acylimido M(NCOR) (R=aryl or alkyl) species in these reactions poses a formidable challenge. Herein, we report on Ru(NCOR) intermediates in C-N bond formation catalyzed by [RuIV (Por)Cl2 ]/N3 COR, a catalytic method applicable to aziridine/oxazoline formation from alkenes, amination of substituted indoles, α-amino ketone formation from silyl enol ethers, amination of C(sp3 )-H bonds, and functionalization of natural products and carbohydrate derivatives (up to 99 % yield). Experimental studies, including HR-ESI-MS and EPR measurements, coupled with DFT calculations, lend evidence for the formulation of the Ru(NCOR) acylnitrenoids as a RuV -imido species.

Photoinduced Hydroarylation and Cyclization of Alkenes with Luminescent Platinum(II) Complexes.

Photoinduced hydroarylation of alkenes is an appealing synthetic strategy for arene functionalization. Herein, we demonstrated that aryl radicals generated from electron-deficient aryl chlorides/bromides could be trapped by an array of terminal/internal aryl alkenes in the presence of [Pt(O^N^C^N)] under visible-light (410 nm) irradiation, affording anti-Markovnikov hydroarylated compounds in up to 95 % yield. Besides, a protocol for [Pt(O^N^C^N)]-catalyzed intramolecular photocyclization of acrylanilides to give structurally diverse 3,4-dihydroquinolinones has been developed.

Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions.

The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.

Direct preparation of unprotected aminimides (R3N+-NH-) from natural aliphatic tertiary alkaloids (R3N) by [Mn(TDCPP)Cl]-catalysed N-amination reaction.

A panel of natural aliphatic tertiary alkaloids (R3N) were directly converted to R3N+-NH- (without the need to prepare protected aminimides R3N+-NR'- followed by deprotection) by [Mn(TDCPP)Cl]-catalysed N-amination reaction, with O-(2,4-dinitrophenyl)hydroxylamine as the nitrogen source, in up to 98% yields under mild reaction conditions.

Iron- and cobalt-catalyzed C(sp3)-H bond functionalization reactions and their application in organic synthesis.

Direct C-H bond functionalization catalyzed by non-precious transition metals is an attractive strategy in synthetic chemistry. Compared with the precious metals rhodium, palladium, ruthenium, and iridium commonly used in this field, catalysis based on non-precious metals, especially the earth-abundant ones, is appealing due to the increasing demand for environmentally benign and sustainable chemical processes. Herein, developments in iron- and cobalt-catalyzed C(sp3)-H bond functionalization reactions are described, with an emphasis on their applications in organic synthesis, i.e., the synthesis of natural products and pharmaceuticals and/or their modification.

Arsenic Distribution, Accumulation and Tolerance Mechanisms of Typha angustifolia in Different Phenological Growth Stages.

Variations of phytoaccumulation and tolerance in different growth stages of plant are important factors for effective removal of pollutants in phytoremediation. The present work investigated arsenic (As) accumulation, As-tolerance and the physiological tolerance mechanisms of Typha angustifolia under different As-level during the seedling, fast-growing and breeding stages. The results showed that As mainly distributed in the underground part and total As accumulation increased with growth stages. Maximum growth rates under lower As occurred in seedling stage, whereas occurred in breeding stage under higher As. T. angustifolia exhibited the highest tolerance ability under 150 mg kg-1 As and tolerance index (TI) varied from seedling to breeding stages. During seedling stage, TI was affected by plant height (Hshoot) and net photosynthesis, which control biomass production. During fast-growing stage, Hshoot and root glutathione (GSH) co-regulated plant As-tolerance. During breeding stage, physiological metabolic processes, especially GSH-mediated processes, played a critical role in improving plant As-tolerance.

Ruthenium porphyrin catalysed intermolecular amino-oxyarylation of alkenes to give primary amines via a ruthenium nitrido intermediate.

Ruthenium porphyrin catalysed direct intermolecular amino-oxyarylation of alkenes including styrenes and 1,3-dienes to give primary amines with O-(2,4-dinitrophenyl)hydroxylamine as the amine source was achieved in moderate to good yields under mild reaction conditions. Spectroscopic analyses revealed that a ruthenium nitrido complex was the key reaction intermediate for the amino-oxyarylation reaction.

Intramolecular Nitrene Insertion into Saturated C-H-Bond-Mediated C-N Bond Cleavage of a Coordinated NHC Ligand.

Ruthenium(II) complexes bearing a tridentate bis(N-heterocyclic carbene) ligand reacted with iminoiodanes (PhI=NR) resulting in the formation of isolable ruthenium(III)-amido intermediates, which underwent cleavage of a C-N bond of the tridentate ligand and formation of an N-substituted imine group. The RuIII -amido intermediates have been characterized by 1 H NMR, UV/Vis, ESI-MS, and X-ray crystallography. DFT calculations were performed to provide insight into the reaction mechanism.

Efficient acceptorless photo-dehydrogenation of alcohols and N-heterocycles with binuclear platinum(ii) diphosphite complexes.

Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.

Spatial and temporal changes of P and Ca distribution and fractionation in soil and sediment in a karst farmland-wetland system.

Phosphorus (P) is a critical element affecting eutrophication in aquatic ecosystems. Its availability is closely related to calcium (Ca) in calcareous soils and sediments, but their relations are unclear. In this study, the spatial and temporal changes in P and Ca fractionation and distribution in a karst farmland-wetland ecosystem were investigated. The results showed that total P concentrations were 1.25-3.19 g kg-1, with higher concentrations in paddy soil than in sediment. Total Ca concentrations were 3.93-10.2 g kg-1, with higher Ca being accumulated in sediments than in soils. The P fractionations varied seasonally, with Ca-bound P being dominant. The moderately-stable Fe/Al-bound P showed temporal variation, while Ca was dominant in acid-soluble fraction, both probably playing an important role in controlling P availability. Correlation analysis showed seasonal relation between Ca and P distribution in soil/sediment. This study suggests that P migration from farmland to wetland may be a major source for P accumulation in sediments in a karst farmland-wetland system.

PAHs in urban soils of two Florida cities: Background concentrations, distribution, and sources.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants, which are found in soils throughout the U.S. The objective of this study was to determine the background concentrations, distributions, and sources of 16 USEPA priority PAHs in two urban soils. A total of 114 soil samples were collected from two large cities in Florida: Orlando and Tampa. The results showed that soils were dominated by high molecular weight PAHs in both cities. The average ∑16-PAHs in Orlando and Tampa soils were 3227 and 4562 µg kg-1, respectively. The averages of 7 carcinogenic PAHs based on the benzo[a]pyrene-equivalent (BaP-EQ) concentrations in the two cities were 452 and 802 µg kg-1. BaP-EQ concentrations in 60-62% of samples were higher than the Florida Soil Cleanup Target Level (FSCTL) for residential soils at 100 µg kg-1 and 20-25% of samples were higher than FSCTL for industrial soils at 700 µg kg-1. Based on molecular diagnostic ratios and PMF modeling, major sources of soil PAHs in both cities were similar, mainly from pyrogenic sources including vehicle emissions, and biomass and coal combustion. Based on ArcGIS mapping, PAH concentrations in soils near business districts and high traffic roads were higher. Thus, it is important to consider background PAH concentrations in urban soils when considering soil remediation.

Visible-Light-Promoted Transition-Metal-Free Phosphinylation of Heteroaryl Halides in the Presence of Potassium tert-Butoxide.

A novel visible-light-promoted C-P bond formation reaction in the absence of both transition metal and photoredox catalysts is disclosed. By employing easily available and inexpensive heteroaryl chlorides/bromides as substrates, a variety of heteroaryl phosphine oxides were obtained in moderate to good yields. This strategy provides a simple and efficient route to heteroaryl phosphine oxides.

Water extract of indoor dust induces tight junction disruption in normal human corneal epithelial cells.

In corneal epithelium, tight junctions play a vital role in its barrier function. Human cornea is highly susceptible to damage by dust. Continued daily exposure to dust has been associated with increased risks of corneal injury. Studies demonstrated that water extract of dust induced cytotoxicity in human corneal epithelial cells (HCECs); however, its effects on corneal epithelial barrier function are unknown. In this study, we determined the concentrations of heavy metals in water extracts of dust, with office dust having higher concentrations of heavy metals than housedust, and Cu and Zn being highest among metals for both dust. Changes in barrier function and its associated mechanism after exposing HCECs to water extracts of dust at 48 µg/100 µ L for 7 d were evaluated. Water extracts of both dust caused decrease of TEER value (39-73%), down-regulation of gene expression related to tight junction and mucin (0.2-0.8 fold), and loss of ZO-1 immunoreactivity from cellular borders, with office dust having greater potential than housedust to disrupt corneal epithelial barrier function. Our data implied the importance to reduce heavy metals in dust to reduce their adverse impacts on human eyes.

Total and available metal concentrations in soils from six long-term fertilization sites across China.

Approximately 19% of agricultural soils in China are contaminated by heavy metals. However, the effects of agricultural management practices on soil contamination are not well understood. Taking advantage of six long-term (23-34 years) field sites across China, this study examined the effects of different agricultural fertilization treatments, including control (no fertilization), inorganic nitrogen, phosphorus and potassium fertilization (NPK), manure fertilization (M), and NPK plus manure fertilization (NPKM), on the total and available metal concentrations in soils. The results showed that after 23-34 years of fertilization, the M and NPKM treatments significantly increased the total concentration of cadmium (Cd), copper (Cu), and zinc (Zn) in soils compared with the concentrations measured for the control and NPK treatments. In contrast, the fertilization treatments had almost no influence on soil lead (Pb) and nickel (Ni) concentrations. The results of analysis via diffusive gradients in thin films demonstrated that long-term sheep or cattle manure fertilization increased the available metals, especially Cd, Cu, and Zn, but long-term swine manure application decreased the available metals, except for Cu and Zn, in soils. Further analysis revealed that the manure source, soil pH level, and biogeochemical properties of metals affected the availability of Cd, Cu, Pb, Zn, and Ni in soils. Collectively, organic fertilizers had the potential to reduce metal uptake by crops, but caution should be taken to reduce metal concentrations in manure.