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A DFT/TDDFT (density functional theory/time-dependent density functional theory) investigation on the geometries in the ground and lowest triplet excited states, the frontier molecular orbitals, the absorption spectra and the phosphorescent emission properties of five heteroleptic iridium(iii) complexes have been performed to obtain a better understanding of structure–property relationships. The key aim was to investigate the effect of π-conjugation on the photophysical properties of these studied complexes. The lowest energy absorption wavelengths are located at 461 nm for 1, 418 nm for 2, 422 nm for 3, 426 nm for 4 and 417 nm for 5. The lowest energy emissions of complexes 1–5 are localized at 572, 463, 583, 707 and 553 nm, respectively, simulated in acetonitrile medium at M052X level. These findings could be useful to provide good guidance for the further design of new potential phosphorescent organic light-emitting diode (OLED) materials. [ABSTRACT FROM AUTHOR]

Aerosol-associated non-polar organic compounds (NPOCs), including 15 polycyclic aromatic hydrocarbons (PAHs), 30 n-alkanes, 2 iso-alkanes, 5 hopanes and 5 steranes, were identified and quantified in PM2.5 samples using the thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method. The samples were mainly collected in autumn and winter in a typical city of eastern China. The total concentrations of NPOCs were 31.7-388.7 ng m-3, and n-alkanes were the most abundant species (67.2%). The heavy-molecular-weight PAHs (four- and five-ring) contributed 67.9% of the total PAHs, and the middle-chain-length n-alkanes (C25-C34) were the most abundant (72.3%) in n-alkanes. PAHs and n-alkanes were mainly distributed in the 0.56-1.00 µm fraction, while ∑ (hopanes+steranes) were associated with the 0.32-1.00 µm fraction, suggesting condensation of combustion products was their important origin. The ratio-ratio plots indicated that NPOCs in the local area were affected by photochemical degradation. To reduce the uncertainty caused by only particle NPOC data for source apportionment, the particle and predicted gaseous-phase NPOCs, incorporated with other PM2.5 compound were used as input data for the positive matrix factorization (PMF) model. Eight factors were extracted for both cases: secondary aerosol formation, vehicle exhaust, industrial emission, coal combustion, biomass burning, ship emission, and dust and light NPOCs. These findings highlight the emissions from different aerosol-associated NPOC origins, which caused different size-specific distributions, photodegradation and gas-particle partitioning, which further affect PM2.5 source apportionment. Considering these effects on organic tracers will help us accurately identify the potential sources of aerosols and then asses the contributions from each source. [ABSTRACT FROM AUTHOR]

The photophysical properties of four Ir(III) complexes have been investigated by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). The effect of the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption and phosphorescent properties has been studied. The theoretical calculation shows that the lowest-lying singlet absorptions for complexes 1-4 are located at 387, 385, 418 and 386 nm, respectively. For 1-4, the phosphorescence at 465, 485, 494 and 478 nm is mainly attributed to the LUMO → HOMO and LUMO → HOMO-1 transition configurations characteristics. In addition, ionisation potential (IP), electron affinities (EAs) and reorganisation energy have been investigated to evaluate the charge transfer and balance properties between hole and electron. The balance of the reorganisation energies for complex 3 is better than others. The difference between hole transport and electron transport for complex 3 is the smallest among these complexes, which is beneficial to achieve the hole and electron transfer balance in emitting layer. [ABSTRACT FROM AUTHOR]

Organoarsenics are widely used as growth promoters in poultry industry, resulting in arsenic (As) accumulation in poultry litter. A greenhouse pot study was implemented to investigate the fate of arsenic originated from poultry litter and their effects on the growth of Brassica napus (oilseed rape), and assess their potential health risks. Five poultry litter application rates (0, 5%, 10%, 20% and 40%) were used, dividing into two groups: one for soil incubation (SI) and the other for plant cultivation (PC). Experimental results indicated that the total arsenic for composted poultry litter was (10.94±0.23) mg/kg, As(V) and As(III) decreased while methylated arsenic increased after 21 d in SI and PC treatments. Seed germination rates were negatively correlated with monomethylarsenic acid (MMA, R2=0.63, p<0.05). The length and biomass of roots and shoots were significantly inhibited by poultry litter, but plant length of 5% treatments was slightly stimulated. Within an average weekly intake of 0.5 kg Brassica napuss, the risk quotient (RQ) values induced from roots nearly all surpassed the acceptable limit (1), were two orders magnitude higher than shoots. According to the potential risk to order, child exhibited the highest risk, adolescent ranked secondly, and adult exhibited the lowest risk. Hence, people should better avoid intake Brassica napus roots to reduce arsenic potential risk. [ABSTRACT FROM AUTHOR]

A DFT/TDDFT investigation has been conducted on two series of cyclometalated iridium(III) complexes to shed light on the effects of structure and steric factors on the photophysical properties. The results reveal that the nature of the N substitution can influence the electron density distributions of the frontier molecular orbitals and their energies, resulting in a change in transition character and emission color. The absorption spectra of the complexes are similar to each other, with 2a- 5a and 2b- 5b presenting a slight redshift compared with their parent complexes. Again, on the basis of the calculations, the higher radiative rate constants ( kr) of 1a- 5a with respect to 1b- 5b can be explained by a larger metal contribution to the excited states (MLCT%) and larger S0-S1 transition electric dipole moments ( µ [ABSTRACT FROM AUTHOR]

Theelectronic structures and phosphorescent properties of a seriesof heteroleptic iridium(III) complexes (mpmi)2Ir(dmpypz)(1; mpmi = 1-(4-tolyl)-3-methylimidazolium, dmpypz =3,5-dimethyl-2-(pyrazol-3-yl)pyridine), (bpmi)2Ir(dmpypz)(2; bpmi = 1-biphenyl-4-yl-3-methylimidazole), (dfmi)2Ir(dmpypz) (3; dfmi = 1-(2,6-difluorobiphenyl)-3-methylimidazole),(mtmi)2Ir(dmpypz) (4; mtmi = 1-methyl-3-(4′-(trifluoromethyl)biphenyl-4-yl)imidazole),(fmmi)2Ir(dmpypz) (5; fmmi = 1-(fluoren-2-yl)-3-methylimidazole),and (mhmi)2Ir(dmpypz) (6; mhmi = 1-methyl-3-phenanthren-2-ylimidazole)have been investigated by using density functional theory (DFT) andtime-dependent density functional theory (TDDFT) methods. The influenceof different substituent groups and π-conjugation degrees onthe optical and electronic properties of Ir(III) complexes was alsoexplored by introducing phenyl, fluorophenyl, (trifluoromethyl)phenyl,and rigid construction on the phenylimidazole moiety of a cyclometalatedligand (C∧C) in complex 1. The calculatedresults show that the lowest energy absorption wavelengths of complexes 1–6are 387, 380, 378, 375, 391, and 384nm, respectively. The introduction of different substituent groupsleads to different degrees of red shift for complexes 2–6in emission spectra in comparison with thatof complex 1. It is believed that the highest tripletmetal to ligand charge transfer 3MLCT (%) contribution,smallest ΔES1–T1and higher μS1values,and larger 3MC–3MLCT energy gap for 3ensure its higher quantum yield in comparison with thatof other complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] On the basis of the thiophene-containing and furan-containing complexes, we design four complexes by introducing thiazole, isothiazole, oxazole, isoxazole on main ligands. The electronic structure, absorption and emission spectra, charge injection/transport properties, absorption and phosphorescence properties have been investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT). Introducing S atom to substitute O atom could enhance HOMO energy level, blueshift emission wavelength, decrease Δ E S 1 - T 1 value. The introduction of N atom on furan ring and thiophene ring could decrease HOMO and LUMO energy levels and energy gaps, blueshift emission wavelength, decrease Δ E S 1 - T 1 value, enhance electron transport ability. Introducing thiazole could decrease hole injection ability and Δ E S 1 - T 1 , and then may have higher Φ PL. Isoxazole and isothiazole groups could facilitate the electron transition from HOMO to LUMO and enhance hole injection ability. Thiazole and isothiazole groups could increase absorption peak strength and hole transport ability. [ABSTRACT FROM AUTHOR]

Abstract: Electronic structure calculations based on density functional theory (DFT) within the generalized gradient approximation (GGA) and GGA+U for manganite cuprate compound LuCu3Mn4O12 have been performed, using the full-potential linearized augmented plane wave method. The calculated results indicate that LuCu3Mn4O12 is ferrimagnetic and half-metallic in both GGA and GGA+U calculations. The minority-spin band gap is 0.7eV within GGA, which is larger than that of LaCu3Mn4O12 (0.3eV), indicating its better half-metallicity. Further, the minority-spin gap enlarges from 0.7 to 2.8eV with U taken into account, and simultaneously the Fermi level being shifted to the middle of the gap, making the half-metallic energy gap to be 1.21eV. These results demonstrate that electronic correlation effect enhances the stability of half-metallic property. These facts make this system interesting candidates for applications in spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The electronic and magnetic properties of the recently synthesized A-site-ordered perovskites A′Cu3Sn4O12 with A′=Ca2+, Sr2+, and Pb2+ were investigated by use of the density functional theory. The results indicate that the ground states of them are all ferromagnetic insulator and the magnetic properties are determined primarily by the direct ferromagnetic interaction between A-site Cu2+ ions, which is consistent with the available experimental results. By replacing bivalent A′ ion by trivalent La ion, we found that the electron is injected into A-site Cu and LaCu3Sn4O12 is predicted to be ferromagnetic half-metallic. [Copyright &y& Elsevier]

The electronic structure and photophysics properties of a series of iridium(III) complexes bearing non-planar tetradentate chelate and substituted bipyrazolate chelate ligands have been theoretically investigated. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been adopted to investigate a series of iridium(III) complexes with different electron-accepting and electron-donating substituents (CF 3 , CN, H, CH 3 and N(CH 3) 2). All the studied complexes have distorted octahedral structures around the Ir(III) metal center with the d6 configuration. The HOMO and LUMO distributions for all the studied complexes are mainly localized on the bipz and L ligands, respectively. The ionization potential and electron affinity have been calculated to evaluate the injection abilities of the holes and electrons in these studied complexes. The calculated lowest energy emissions using the TDDFT/M062X method are located at 498, 502, 445, 477 and 600 nm, respectively. The theoretical results show that these different substituents have different effects on the electronic structure and photophysical properties. This study can be useful for the design of potential blue phosphorescent organic light-emitting diode (OLED) materials. [ABSTRACT FROM AUTHOR]

• Photophysical properties of two series of iridium(III) complexes have been theoretically investigated. • The introduction of –COCH 3 and –SO 2 PhF groups can improve the electron transport property. • Complexes 3 and 4 have the larger μ s 1 , so they may possess the higher quantum efficiency. Using DFT/TDDFT methods to investigate the electronic structure, absorption and emission spectra, charge injection/transport ability and phosphorescence quantum efficiency of two series of Ir(Ⅲ) complexes. Complexes 1a–1c introduce F atom, acetyl group (–COCH 3), 1-fluoro-4-methanesulfonyl-benzene group (–SO 2 PhF) to substitute methyl on benzene ring of mpmi main ligand (1-(4- tolyl)-3-methyl-imidazole) in complex 1, and complexes 2–4 introduce different ligands to substitute the dmpypz ancillary ligand (3,5-dimethyl-2-(1H-pyrazol-5-yl)pyridine) of complex 1, such as heppy ligand (4-(1-hydroxy-ethyl)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-ol), typy ligand (2-thiophen-2-yl-pyridine), quol ligand (quinolin-8-ol). The introduction of F atom, –COCH 3 and –SO 2 PhF has the important effect on the photophysical properties of all studied complexes. Thereinto, introducing –COCH 3 and –SO 2 PhF have great influence on the transition dipole moment from S 0 to S 1 state (μ S 1 ) and can improve electron transport property. Introducing different ancillary ligands can adjust emission wavelength effectively, has great influence on μ S 1 , typy ligand and quol ligand can adjust hole/electron injection ability. Typy ancillary ligand could improve electron balance ability. Complexes 1–1c and 2 have larger HOMO–LUMO energy level, and they are potential blue materials. Complex 1c has better electron injection ability. Complexes 3 and 4 have the larger μ S 1 , so they may have higher quantum efficiency. [ABSTRACT FROM AUTHOR]

Abstract The electron-carrier-doping effects in an antiferromagnetic insulator Ba 2 MnMoO 6 were investigated by La doping using the first-principles calculation. We examined the magnetic properties and the electronic structures for different doping ratios of La. The results indicate that a transition from an antiferromagnetic (AFM) insulating Ba 2 MnMoO 6 to a AFM half-metallic Ba 2- x La x MnMoO 6 (x ≤ 1.0) and then a AFM metallic phase (x = 1.5, 2.0) occurs upon La doping. The injected electron accommodated into the Mo 4d states accounts for the metallic properties. Moreover, the electron correlation plays a crucial role in the determination of the electronic structure. The evaluated magnetic ordering temperatures for the doping systems are all higher than room temperature revealing the potential applications. Highlights • The magnetic properties of electron doped Ba 2-x La x MnMoO 6 system is determined. • A transition from insulating to half-metallic and then to metallic is obtained. • The magnetic exchange parameter and the magnetic ordering temperature were evaluated. • The virtual atom method is suggested to be accurate and effective. [ABSTRACT FROM AUTHOR]

The types and structures of the intermetallic phases formed during solidification in an as-cast Mg−4Al−15Gd−4Y−1Zn alloy were systematically investigated in detail using transmission electron microscopy (TEM). The results indicate that both 14H- and 18R-long period stacking-ordered (LPSO) phases are clearly different from the conventional LPSO phases in the Mg−TM−RE (TM = transition metal) systems and with the order-disorder structures. Furthermore, these two LPSO phases occasionally coexisted with each other following an orientation relationship as (0014) 14H about 70.6° from (0018) 18R and [1 1 ¯ 00] 14H //[1 1 ¯ 00] 18R . In addition, another six intermetallic phases namely the large and the small blocky phases on grain boundary, the short and the long parallel plates near grain boundary, the large lamellae phase with irregular profile and the small lamellae phase coexisted on the 18R-LPSO phase were found in the studied alloy. The former three phases are Mg 5 RE phase and the later three phases are 14H-LPSO, Mg 4.8 Al 12 RE 7.2 and Mg 24 RE 5 , respectively. Finally, the special 18R-LPSO phase in the studied alloy may be transformed from the Mg 4.8 Al 12 RE 7.2 phase following an orientation relationship as (0018) 18R //(111) Mg4.8Al12RE7.2 and [1 1 ¯ 00] 18R //[0 1 ¯ 1] Mg4.8Al12RE7.2 . [ABSTRACT FROM AUTHOR]

• A recyclable MoS 2 /Fe 3 O 4 was developed to remediate mercury-contaminated water. • The MoS 2 /Fe 3 O 4 exhibited excellent adsorption capacity and selectivity for Hg(II). • The hierarchical microstructure improved the accessibility of sulfur active sites. • The application potential of MoS 2 /Fe 3 O 4 was verified in various real water matrices. • The mechanism of Hg(II) immobilization was mainly owning to surface coordination. Developing practical and cost-effective adsorbents with satisfactory mercury (Hg) remediation capability is indispensable for aquatic environment safety and public health. Herein, a recyclable hierarchical MoS 2 /Fe 3 O 4 nanocomposite (by in-situ growth of MoS 2 nanosheets on the surface of Fe 3 O 4 nanospheres) is presented for the selective removal of Hg(II) from aquatic samples. It exhibited high adsorption capacity (∼1923.5 mg g −1), fast kinetics (k 2 ∼ 0.56 mg g −1 min−1), broad working pH range (2–11), excellent selectivity (K d > 1.0 × 107 mL g −1), and great reusability (removal efficiency > 90% after 20 cycles). In particular, removal efficiencies of up to ∼97% for different Hg(II) concentrations (10–1000 μg L −1) in natural water and industrial effluents confirmed the practicability of MoS 2 /Fe 3 O 4. The possible mechanism for effective Hg(II) removal was discussed by a series of characterization analyses, which was attributed to the alteration of the MoS 2 structure and the surface coordination of Hg-S. The accessibility of surface sulfur sites and the diffusion of Hg(II) in the solid-liquid system were enhanced due to the advantage of the expanded interlayer spacing (0.96 nm) and the hierarchical structure. This study suggests that MoS 2 /Fe 3 O 4 is a promising material for Hg(II) removal in actual scenarios and provides a feasible approach by rationally constructing hierarchical structures to promote the practical applications of MoS 2 in sustainable water treatments. [Display omitted] [ABSTRACT FROM AUTHOR]

The electronic structure and photophysical properties of five cyclometalated Ir(III) complexes bearing different substituted acetylacetone moieties have been theoretically investigated. [Display omitted] Using time-dependent density functional theory (TDDFT) approach, the electronic structure and photophysical properties of five cyclometalated Ir(III) complexes bearing different substituted acetylacetone moieties have been calculated and investigated. The calculated geometry structure of complex 2 shows a very good agreement with the available experimental data. The HOMO of complex 1 has the different distribution from those of complexes 2 – 5 , that is, residing on the d-orbital of Ir, π-orbital of acac and L ligands. The S 0 → S 1 transition of complex 1 is from HOMO → LUMO and HOMO–1 → LUMO, that is, different from those of complexes 2 – 5. The lowest energy emissions for these complexes from CAM-B3LYP level are localized at 591, 581, 576, 574, and 571, respectively. Complex 4 might possess the largest k r value among these studied complexes. We anticipate that this study can shine some light on Ir(III) emitters in the fabrication of efficient organic light-emitting diodes (OLEDs). [ABSTRACT FROM AUTHOR]

Mercury pollution has attracted worldwide attention due to its toxicity, bioaccumulation and persistence. Cement clinker production is the top emitter of atmospheric mercury in China and the emissions from raw mill systems account for about 85% of all emissions. However, the mercury emission characteristics and mechanisms as a function of time during an operation cycle are still unclear. This study aims to reveal the mercury emission characteristics and mechanisms in cement plants by comprehensively using offline and online field measurements, control experiments and heat transfer analysis. Research results indicated that an intermediate temperature (300–500 °C) desorption and the heterogeneous oxidation of mercury in the precalciner, the selective adsorption of oxidized gaseous mercury (Hg2+) to raw meal, and Hg2+ re-vaporization in the conditioning tower jointly caused an increase in the Hg2+ ratio (15.3%−83.6%) during the mill-off mode. In addition, mercury concentrations remained at approximately 6.5 μg/Nm3 during the mill-on mode while the values reached a peak of 1835.4 μg/Nm3 during the mill-off mode. Thus, atmospheric mercury emissions during the mill-off mode accounted for 35.0%− 71.7% of the emissions during the entire cycle, although the mill-off period only lasted for 5%− 17% of the whole cycle. Our results therefore suggest that supervisory monitoring of mercury in cement clinker production should specify the operating status of raw mills. Mercury control technologies targeting a relatively short period for the mill-off mode can substantially reduce mercury emissions from cement clinker production, and thus, the related impacts on ecosystems and human health. [Display omitted] • Mercury concentrations of the tested plants increase by orders of magnitude after mill-off. • Elevated Hg2+ emission ratio attributes to the cyclic Hg2+ adsorption and desorption processes. • Technologies on mercury emission reduction during mill-off are more effective. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photophysical properties of five iridium(III) complexes have been theoretically investigated. • Calculated emission wavelength of complex 1 is in agreement with the experimental datum. • The different positional N-substitution has the important effect on the photophysical properties of Ir(III) complexes. The electronic structure in the ground and lowest triplet excited states, the frontier molecular orbitals, the absorption spectra, and phosphorescence properties of five iridium(III) complexes bearing fluorine substituted 2,3′-bipyridine and bromine substituted pyridinyltetrazolate ligands have been investigated to explore blue phosphorescent materials. Complexes 1 – 5 have different transitions responsible for the phosphorescence wavelength. The emission wavelengths of 2 , 4 and 5 have an obvious redshift in comparison with 1 , indicating that changing the main ligand can effectively adjust the phosphorescence properties. Complex 3 has the best balance of charge transport among these complexes. [ABSTRACT FROM AUTHOR]

Currently, studies on the characteristics, reactivity and source apportionment of volatile organic compounds (VOCs) are mainly focused on large cities, however, information about the source characteristics of VOCs in less-developed regions is insufficient. In this study, ambient air samples (n = 352) were collected from 11 sampling sites (including urban areas, suburban areas, outer suburb areas, and background areas) in Guilin, a typical tourist city located in southwest China, during the period 1st May to 30th November 2018 to determine the concentrations, temporal and spatial distribution, and activity of VOCs and to identify their sources. The results showed that the concentration of VOCs was 23.67 ± 9.77 ppbv, and aromatics were the most abundant VOCs, accounting for 65.75% of the total VOCs concentrations. The propylene-equivalent concentration and the ozone formation potential (OFP) of VOCs were 10.08 ppbv and 158.02 ppbv, respectively, and aromatics contributed the largest, accounting for 88.87% and 93.00%, respectively. Moreover, the ratios of T/B and X/E were 1.44 ± 0.92 and 0.74 ± 1.10, respectively. The temporal and spatial distribution of VOCs showed that there were significant differences of the VOCs concentrations between seasons (higher in autumn and lower in summer) and the VOCs concentrations were both high in urban areas and outer suburb areas. Based on the positive matrix factorization (PMF) method, 5 sources were identified as fuel evaporation, vehicle exhaust, industrial productions, solvent use, and biogenic emissions, contributing 35.32%, 28.29%, 15.65%, 11.20%, and 9.54%, respectively. Results indicated that a high proportion of aromatics in ambient VOCs and a large contribution of aromatics to O 3 generation are the main characteristics that differentiate Guilin as a typical tourist city from other types of cities. We concluded that the VOCs in Guilin mainly come from the emissions of fuel evaporation and vehicle exhaust, and the impact of industrial emissions is relatively small, which is consistent with the characteristics of a tourist city. Moreover, our results revealed that the aging degree of air mass in Guilin is relatively higher than other cities, which inferred that the VOCs in Guilin may be affected by transmission from external sources. Image 1 • First time continuous observation of ambient VOCs in a typical tourist city. • The temporal and spatial distribution characteristics of ambient VOCs were examined. • Aromatics were the most abundant VOCs and the largest contributors to OFP. • Fuel evaporation made the largest contribution to ambient VOCs. [ABSTRACT FROM AUTHOR]

In this experiment, Bi 2 Sn 2 O 7 /ZnO composite photocatalytic materials were synthesized by a hydrothermal method and characterized by XRD, SEM, and EDS, etc. The prepared Bi 2 Sn 2 O 7 /ZnO has a nanorod structure and high phase purity. The photocatalytic antimicrobial performance of Bi 2 Sn 2 O 7 /ZnO against bacteria and fungi under visible light was significantly better than that of single Bi 2 Sn 2 O 7 and ZnO. In particular, 1000 mg/L 1 : 3 Bi 2 Sn 2 O 7 /ZnO showed an antimicrobial rate of more than 97 % against Escherichia coli, Staphylococcus aureus, and Candida albicans, which are widely present in the nature. The free radical trapping experiments were selected and the antimicrobial mechanism was investigated, and the results showed that the antimicrobial process of the Bi 2 Sn 2 O 7 /ZnO system was regulated by the free radicals such as ⋅OH, h + , and e - , which were generated by its unique photocatalytic activity. Finally, MTT cytotoxicity experiments demonstrated that the Bi₂Sn₂O₇/ZnO composite was not toxic to cells. In addition, the antimicrobial performance of Bi 2 Sn 2 O 7 /ZnO on real livestock wastewater and the real-life application of the prepared Bi 2 Sn 2 O 7 /ZnO PCL composite antibiotic film for antimicrobial treatment of freshly cut fruits' surfaces under visible light were experimentally investigated. This study provides a new idea for Bi 2 Sn 2 O 7 /ZnO as a photocatalytic antimicrobial agent., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

By using the density functional theory (DFT) and time-dependent density functional theory (TDDFT), the electronic structure and photophysical properties of a series of cyclometalated iridium(III) complexes bearing the substituted phenylpyrazole have been theoretically investigated. All studied iridium(III) complexes have the distorted octahedral geometry with cis-C,C, cis-O,O, and trans-N,N chelate disposition. The lowest lying singlet → singlet absorptions of all studied iridium(III) complexes are respectively located at 405 nm, 387 nm, 382 nm, 370 nm, and 387 nm. The calculated emission wavelengths for all studied iridium(III) complexes are 654 nm, 513 nm, 506 nm, 505 nm and 499 nm, respectively. The calculated emission wavelength for complex 4 at the CAM-B3LYP level is in good agreement with the experimental value. From the theoretical results, it can be seen that the electron-donating substituent groups have the important effect on the electronic structure and photophysical properties of all studied iridium(III) complexes. We hope that this study can provide valuable guidance for the design of new phosphorescent organic light-emitting diodes (OLEDs) materials., (© 2021. The Author(s), under exclusive licence to European Photochemistry Association, European Society for Photobiology.)

Coastal ecosystem is vulnerable to heavy metal contamination. The northern Hangzhou Bay is under intensifying impact of anthropogenic activities. To reveal the heavy metal pollution status in the coastal environment of the Hangzhou Bay, a long-term investigation into the heavy metal contamination during 2011 to 2016 was initiated. Seawater and sediment samples of 25 locations depending on the sewage outlet locations in the northern Hangzhou Bay were collected to analyze the concentrations and temporal and spatial distribution of Cu, Pb, Zn, Cd, Hg, and As. Pollution condition, ecological risk, and potential sources were additionally analyzed. Results show that the annual mean concentrations of Cu, Pb, Zn, Cd, Hg, and As were 2.13-4.59, 0.212-1.480, 7.81-20.34, 0.054-0.279, 0.026-0.090, and 1.08-2.57 μg/L in the seawater, and were 16.34-28.35, 16.25-26.33, 67.32-97.61, 0.084-0.185, 0.029-0.061, and 6.09-14.08 μg/L in the sediments. A decreasing trend in Cu, Pb, Zn, Cd, and Hg concentrations and an increasing trend in As of the seawater were observed. However, in the sediment, the heavy metals demonstrated a rising trend, except for Hg. The single-factor pollution index showed an increasing trend in Cd and As in the seawater, depicting an enhanced pollution of Cd and As, while in the sediments, Cu, Pb, and As were in pollution-free level (average Geo-accumulation index (I geo ) values below 0) in general, and only occasional slight pollution occurred in individual years, e.g., As with 0.403 in 2016. The mean I geo values of Cd ranged from - 0.865 to 0.274 during 2011 to 2016, indicating that the pollution level of Cd was slight, but is likely to increase in the forthcoming years. The level of heavy metal contamination in sediments was low in 2011 (5.853) and 2012 (5.172), and moderate during 2013 to 2016 (in the range of 6.107 to 7.598), while the degree of potential ecological risk was low in the study period, except moderate in 2013 (125.107). The highest contamination degree and potential ecological risk appeared in 2013 (Cd = 7.598; RI = 125.107), while Cd and Hg contributed over 75% of the ecological risk. Overall, the results show low pollution level and low potential ecological risk in the northern Hangzhou Bay; however, more attention should be paid to the potential ecological risk due to Hg and Cd. Graphical abstract Spatial distribution of the heavy metal levels in the sediment of the coastal environment of the northern Hangzhou Bay on a long-term basis.

This study aims to develop a rapid bacterial antibiotic susceptibility test (AST) method by Bacteria-aptamer@AgNPs-surface enhanced Raman spectroscopy (SERS) and further evaluate the influence of different antibiotics on the Raman intensity of bacteria. The Raman intensity of Escherichia coli O157:H7 (E. coli O157:H7) and Staphylococcus aureus (S. aureus) in the presence of different concentrations of antibiotics in 2 h was detected by Bacteria-aptamer@AgNPs-SERS in this study. Our results found that the bacteria Raman signal peak at 735 cm -1 and the minimum inhibitory concentration (MIC) value was determined in 1 h according to Raman signals. In 2 h, the bacteria Raman signal growth at sub-MIC concentrations of four different kinds of antibiotics and the bacteria colony-forming unit (CFU) have similar enhancements. SERS utilizes special functions of rough metal surfaces and offers a huge enhancement of Raman intensities with reduced fluorescence backgrounds, which makes it an ultrasensitive tool of detection. This rapid AST method and the enhancement effect should be of value in search of new antibiotic drugs.

Iron and steel industry emission is an important industrial source of air pollution. However, little is known about the relationship between volatile organic compounds (VOCs) emitted and regional air pollution. In this study, VOCs emissions from a typical iron and steel plant in Yangtze River Delta (YRD, China) were monitored from April 2018 to March 2019. The ozone formation potential (OFP) and secondary organic aerosol (SOA) formation of VOCs were calculated to reveal the influence of VOCs emissions on regional ozone and particulate pollution, and the sensitivity analysis approach was performed to explore the qualitative and quantitative relationships between VOCs and O 3 , as well as VOCs and PM 2.5 . The VOCs concentration was 93.76 ± 266.97 ppbv during the study. The OFP was 760.08 ± 2391.90 μg m -3 , and aromatics were the predominant precursors, contributing 54.05% of the total OFP. Furthermore, the SOA estimated by fractional aerosol coefficient (FAC) and time-resolved (TR) methods were 6.032 ± 13.347 μg m -3 and 0.971 ± 4.650 μg m -3 , accounting for 8.65-26.39% (13.78 ± 7.46%) and 1.55-4.20% (2.22 ± 1.23%) of the PM 2.5 concentrations, respectively. The results indicated that VOCs were more sensitive to O 3 pollution in high pollution domains, whereas VOCs were more sensitive to PM 2.5 pollution in low pollution domains. We concluded that reducing VOCs emissions might be effective in alleviating photochemical pollution episodes in areas around iron and steel industry, and the haze pollution occurred in these regions may be caused by the primary emission of PM, and the contribution of SOA was relatively small.

Volatile organic compounds (VOCs) are important precursors of ozone and atmospheric particulates that have attracted extensive attention worldwide. Cooking emissions, the chemical characteristics of which vary dramatically due to different cooking styles, are a main source of ambient VOCs, especially in large cities. This research focused on the emission characteristics of VOCs from six types of restaurants in Shanghai: hot pot (HP), Sichuan cuisine (SC), Cantonese cuisine (CS), seafood (SF), Western fast food (WFF), and authentic Shanghai cuisine (ASC). It was found that HP, which discharged cooking fumes indoors, produced the highest mass concentration of VOCs (1900.2 ± 364.8 μg m -3 ), followed by SC (1403.7 ± 403.8 μg m -3 ), WFF (656.0 ± 156.9 μg m -3 ), SF (638.6 ± 145.1 μg m -3 ), CC (632.7 ± 127.7 μg m -3 ), and ASC (612.3 ± 51.3 μg m -3 ), the cooking fumes from which were collected by emission extraction stacks. Additionally, the VOC species from each cuisine were mainly low carbon substances. Alkanes were the major VOC pollutants from all six cuisines, accounting for 34.4-71.7%. The coefficient divergence values were 0.287-0.593, suggesting that there were differences between the cuisines in the present study. Ozone formation potential and secondary organic aerosol formation potential indicated that O-VOCs and aromatics were the largest contributors. Health risk assessment of VOCs via non-carcinogenic risk values (HQ) and carcinogenic risk values (RISK) indicated that frying, grilling, and stir-frying had relatively large impacts on human health. VOCs collected in emission extraction stacks were significantly higher risk compared with those in the indoor environment, but the RISK score of the HP restaurant was larger, second only to SC. The HQ and RISK values of 1,3-butadiene, acetaldehyde, and trichloroethylene in the HP restaurant all exceeded US EPA standards, indicating that long-term exposure in an HP restaurant would have a significant impact on human health and might carry a potential cancer risk.