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1.
Chem Commun (Camb) ; 56(92): 14381-14384, 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33140773

RESUMO

An unprecedented CsPbBr3-based polar Dion-Jacobson type bilayered hybrid, (2meptH2)CsPb2Br7 (1, where 2mept = 2-methyl-1,5-diaminopentane), has been reported. Polarization could benefit the charge transport to induce low Ntrap. 1 exhibits a large on/off ratio (∼103), fast response time (∼200 µs) and high photodetectivity (∼109 Jones) for promising UV photodetection.

2.
Water Res ; 189: 116602, 2020 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33189976

RESUMO

Diphenylamine antioxidants (DPAs) are widely used industrial chemicals. Wastewater effluents and biosolids are important pathways for DPAs to enter the environment. Information on the fate of DPAs in wastewater treatment plants (WWTPs) and their environmental releases is limited. In this study, we characterized the occurrence, removal efficiencies, distribution, mass balance, and environmental releases of 17 DPAs in ten Canadian WWTPs and four landfill sites from 2013 to 2015. These WWTPs are different in sizes, and treatment technologies. Median concentrations of ΣDPAs were 78 ng/L in influent, 6.9 ng/L in effluent, 326 ng/L in leachate, and 445 ng/g in biosolids (dry weight), respectively. Diphenylamine (DPA) and ditertoctyl-diphenylamine (DTO-DPA) were the predominant congeners of DPAs in all the matrices. Residues of DPAs were not completely removed during wastewater treatment processes: most DPAs were detected in at least one sample of WWTP effluent with the highest concentration of 117 ng/L (DPA). Overall, high removal efficiencies (median > 90%) of most of the DPAs were observed in the secondary and advanced treatment, as well as in the facultative and aerated lagoons. In contrast, primary treatment exhibited a lower removal efficiency of the DPAs. Mass balance analysis shows that sorption to biosolids is the major removal pathway of DPAs in WWTPs. The results also highlight that environmental releases of DPAs via biosolid applications (70 mg/d/1000 people) can be over several times higher than that via wastewater effluent (2.5-36 mg/d/1000 people).

3.
Chemistry ; 2020 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33145861

RESUMO

Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amount of DMSO residual is often seen on the surface of chemical product. It is difficult to quickly determine whether the residual DMSO is washed completely. This work reports a Cd(II) metal-organic framework (MOF) SXU-4 which can detect trace amount of DMSO in various solvents. Fluorescence experiments reveal its turn on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU-4 (DMSO@ SXU-4 ), in combination with computational results uncover that the enhanced DMSO-MOF conjugation through multiple DMSO-MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33108299

RESUMO

The problem of event-triggered synchronization of master-slave neural networks is investigated in this article. It is assumed that both communication channels from the sensor to controller and from controller to actuator are subject to stochastic deception attacks modeled by two independent Markov processes. Two discrete event-triggered mechanisms are introduced for both channels to reduce the number of data transmission through the communication channels. To comply with practical point of view, static output feedback is utilized. By employing the Lyapunov-Krasovskii functional method, some sufficient conditions on the synchronization of master-slave neural networks are derived in terms of linear matrix inequalities, which make it easy to design suitable output feedback controllers. Finally, a numerical example is presented to show the effectiveness of the proposed method.

5.
Dalton Trans ; 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33021307

RESUMO

Discrete supertetrahedral clusters of metal chalcogenides are rare because of the difficulty involved in meeting global charge matching between the negative charge of the skeleton and counterion. We present herein the third type of a discrete chalcogenide cluster with a double T3 structure in the compound (HDBN)6[In20S33(DBN)6] (DBN = 1,5-diazabicyclo [4.3.0]-5-nonene), the anion of which features quasi-D3 symmetrical double-T3 In20S33 supertetrahedra with six cornered indium atoms coordinated by DBN molecules. DFT theory calculations of the interaction between host and guest show that this compound may have high kinetic stability and low photoelectric reactivity.

6.
Environ Sci Technol ; 54(17): 10772-10782, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32786603

RESUMO

Empirical evidence suggests that human occupants indoors, through their presence and activities, can influence the dynamics of semivolatile organic compounds (SVOCs). To better understand these dynamics, a transient multimedia human exposure model was developed (Activity-Based Indoor Chemical Assessment Model (ABICAM)). This model parametrizes mass-balance equations as functions of time-dependent human activities. As a case study, ABICAM simulated exposures of an archetypal adult and toddler over 24 h to diethyl phthalate (DEP), butyl benzyl phthalate (BBzP), and di-2-ethylhexyl phthalate (DEHP) that span a wide range of gas-particle partitioning tendencies. Under baseline (no activities beyond respiration), the toddler's time-average internal doses were three to four times higher than the adult's, due to differences in physical human attributes (e.g., inhalation rate). When time-dependent activities were considered, interindividual (e.g., adult vs toddler) variability was accentuated by up to a factor of 3 for BBzP. Activities with the greatest influence on time-average internal dose were showering (-71% for BBzP), cooking (+27% for DEHP), and sleeping (-26% for DEHP). Overall, the results support the hypotheses that (1) transient indoor activities can give rise to intraindividual variability in estimated internal doses of SVOCs, and (2) interindividual variability in such exposure can result from differences in activity patterns and physical human attributes, according to a compound's physical-chemical properties.

7.
Small ; : e2003824, 2020 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-32830455

RESUMO

The surface reconstruction of oxygen evolution reaction (OER) catalysts has been proven favorable for enhancing its catalytic activity. However, what is the active site and how to promote the active species generation remain unclear and are still under debate. Here, the in situ synthesis of CoNi incorporated Fe3 N nanotubes (CoNi-Fe3 N) on the iron foil through the anodization/electrodeposition/nitridation process for use of boosted OER catalysis is reported. The synergistic CoNi doping induces the lattice expansion and up shifts the d-band center of Fe3 N, which enhances the adsorption of hydroxyl groups from electrolyte during the OER catalysis, facilitating the generation of active CoNi-FeOOH on the Fe3 N nanotube surface. As a result of this OER-conditioned surface reconstruction, the optimized catalyst requires an overpotential of only 285 mV at a current density of 10 mA cm-2 with a Tafel slope of 34 mV dec-1 , outperforming commercial RuO2 catalysts. Density functional theory (DFT) calculations further reveal that the Ni site in CoNi-FeOOH modulates the adsorption of OER intermediates and delivers a lower overpotential than those from Fe and Co sites, serving as the optimal active site for excellent OER performance.

8.
Artigo em Inglês | MEDLINE | ID: mdl-32815706

RESUMO

Metal-organic frameworks (MOFs) with excellent proton conducting ability are crucial to fuel cells, chemical sensors, and redox flow batteries, but achieving them remain a challenge because of the difficulty in simultaneous fulfillment of large number of proton carriers, high mobility of protons, and long-term durable proton conduction. To explore a simple, efficient, and general route toward highly proton-conducting MOFs, we propose herein an aliovalent substitution metal strategy for isostructural aminium-templated MOFs which benefit the acquisition of rich proton sources without modifying ligands or exchanging protic organic molecules. This idea is verified by 100-fold enhancement of conductivity in compounds (Me2NH2)2[Cd(mdhbqdc)2] (Cd-BQ) and (Me2NH2) (Me2NH)[In(mdhbqdc)2] (In-BQ) (H2mdhbqdc = dimethyl 3,6-dihydroxy-2,5-benzoquinone-1,4-dicarboxylic acid) that feature three-dimensional diamond-like structures with two-dimensional intersected channels. Accompanied by the in situ formation of an anilicate ligand, a great number of -OH groups are grafted onto the inner wall of pores, which interact with neutral Me2NH and/or protonated Me2NH2+ cations via N-H···O hydrogen bonds. The high concentration of protons and dynamics of protic amines in the porous framework readily leads to a moderate conductivity of In-BQ (2.10 × 10-4 S cm-1, at 303 K under 95% RH) and an activation energy of 0.73 eV (95% RH). It should be noted that the aliovalent substitution of Cd(II) for In(III) results in the doubling of dimethylaminium proton carriers in Cd-BQ, indicating more frequent hopping and multiple proton-transfer pathways. This indication is supported by a very high protonic conductivity of 2.30 × 10-2 S cm-1 and a reduced activation energy of 0.48 eV under the same conditions. Molecular dynamics simulations visually elucidate the fact that compared with In-BQ, aliovalent-substituted Cd-BQ has shorter proton-migration distances, which in combination with more proton numbers results in more frequent hopping and sliding of protons, in agreement with the experimental results.

9.
Environ Sci Technol ; 54(13): 8221-8231, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32484664

RESUMO

Identifying potential persistent organic pollutants (POPs) and persistent, bioaccumulative, and toxic (PBT) substances from industrial chemical inventories are essential for chemical risk assessment, management, and pollution control. Inspired by the connections between chemical structures and their properties, a deep convolutional neural network (DCNN) model was developed to screen potential PBT/POP-like chemicals. For each chemical, a two-dimensional molecular descriptor representation matrix based on 2424 molecular descriptors was used as the model input. The DCNN model was trained via a supervised learning algorithm with 1306 PBT/POP-like chemicals and 9990 chemicals currently known as non-POPs/PBTs. The model can achieve an average prediction accuracy of 95.3 ± 0.6% and an F-measurement of 79.3 ± 2.5% for PBT/POP-like chemicals (positive samples only) on external data sets. The DCNN model was further evaluated with 52 experimentally determined PBT chemicals in the REACH PBT assessment list and correctly recognized 47 chemicals as PBT/non-PBT chemicals. The DCNN model yielded a total of 4011 suspected PBT/POP like chemicals from 58 079 chemicals merged from five published industrial chemical lists. The proportions of PBT/POP-like substances in the chemical inventories were 6.9-7.8%, higher than a previous estimate of 3-5%. Although additional PBT/POP chemicals were identified, no new family of PBT/POP-like chemicals was observed.


Assuntos
Aprendizado Profundo , Poluentes Ambientais , Monitoramento Ambiental , Poluentes Ambientais/análise , Poluição Ambiental , Medição de Risco
10.
Inorg Chem ; 2020 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-32558567

RESUMO

The development of new responsive smart materials has been highly desirable in the recent decade due to growing demand in our daily life, and extended viologen-based coordination polymers are regarded as proper and promising candidates for stimuli-responsive study. A tri(pyridinyl)pyridine viologen-based Kagome dual (kgd) topological coordination polymer, [Mn3Cl4(tpptb)2]·Cl2·(H2O)2, (tpptb = N,N',N″-tri(3-carboxybenzyl)-2,4,6-tri(pyridinium-4-yl)pyridine; 1) has been solvothermally synthesized, which can selectively respond to soft X-ray Al-Kα (λ = 8.357 Å) irradiation but not to UV light and hard X-rays of λ < 1.5418 Å at room temperature. Appealingly, 1 is very sensitive and convenient for the visual detection of various volatile amine vapors, especially ethylamine vapors at a low concentration of 100 ppm, and the vapochromic sample can be recovered after exposure in the air at room temperature. The sequence of amines in vapochromism could be rationalized by combined consideration of vapor pressure, the molecular size, and electron-donor ability of various amine molecules as well as the void spaces of 1. In addition, 1 exhibits an obvious hydrochromic transformation upon heating in the air and an anhydrous atmosphere. Combined XPS and EPR confirmed that these physical and chemical stimuli can cause electron transfer from electron-rich groups to quaternary nitrogen atoms of the ligand to generate charge-separated radicals, leading to soft X-ray-induced photochromic and selective vapochromic behavior of 1. Such behavior indicates that it will become a convenient, recyclable, and practical multifunctional material for chemical and environmental sensing. These results provide an effective avenue for the rational design and synthesis of multifunctional chromic materials for potential use in sensing devices.

11.
Chem Commun (Camb) ; 2020 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-32597434

RESUMO

New paracelsian-like beryllophosphates M4LiBe4P7O24 and their tetrahedra-substituted phases M4Li(Li3P)P7O24 (MLiP2O6, M = Cs, Rb) were designed and synthesized. Interestingly, two types of phases undergo a structural transformation, resulting from the radius and valence charge number of tetrahedral cations. Four crystals demonstrate potential deep-UV NLO properties such as short absorption edges (<190 nm) and phase-matching SHG response.

12.
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue ; 32(3): 378-381, 2020 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-32386009

RESUMO

Acute respiratory distress syndrome (ARDS) is a serious disease with high mortality, which is characterized by non-cardiogenic pulmonary edema and hypoxemia. In recent years, the development of supportive therapy has reduced the mortality to some extent, however, the high cost of treatment, side effects and the high mortality of moderate and severe ARDS limit its efficacy. So it is necessary to strengthen the research on specific drugs. The core pathological changes of ARDS are the uncontrolled inflammatory response and the impairment of pulmonary vascular endothelium and alveolar epithelial barrier function. Therefore, regulating the intensity of inflammatory response and promoting the endothelial and epithelial barrier have become two key factors in the current drug treatment of ARDS. This article summarizes the pathogenesis of ARDS and the related preclinical drug therapy of ARDS in recent years from two aspects: the uncontrolled inflammatory response and the destruction of alveolar epithelial and pulmonary vascular endothelial barrier, in order to provide reference for the later treatment of ARDS.


Assuntos
Edema Pulmonar , Síndrome do Desconforto Respiratório do Adulto , Endotélio Vascular , Humanos , Pulmão
13.
Environ Pollut ; 264: 114733, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32417577

RESUMO

Passive samplers are useful tools for monitoring hydrophobic, persistent, and potentially bioaccumulative contaminants in the environment. In this study, low density polyethylene passive samplers were deployed in urban-influenced and background nearshore freshwaters of northwestern Lake Ontario and analyzed for a broad range of both legacy halogenated organic contaminants (HOCs) and halogenated flame retardants (HFRs). Non-targeted analysis was conducted for screening additional halogenated substances. For most compounds, concentrations were greatest in the industrialized Hamilton Harbour and more generally at sites that have stronger influences of wastewater effluent discharges and stormwater run-off through rivers and creeks. Polychlorinated biphenyls (PCBs) remain the dominant class of HOCs in water, with dissolved-phase concentrations ranging from 10 to 4100 pg/L (ΣPCBs), followed by polybrominated diphenylethers (ΣPBDEs; 14-960 pg/L) and the organochlorine pesticides (OCPs; 22-290 pg/L). Several non-PBDE brominated flame retardants (nBFRs) and chlorinated Dechlorane-related compounds were detected, with hexabromocyclododecanes (ΣHBCDD; sum of 3 diastereoisomers) the most abundant (1.0-21 pg/L). Non-targeted screening of samples by high resolution mass spectrometry using Kendrick mass defect plots for data analysis indicated that several other halogenated compounds were present in waters at relatively high abundances compared to the flame retardants, based on semi-quantitative estimates. These included methyl-triclosan, four halogenated anisoles (2,4,6-tribromoanisole, dimethyl-trichloroanisole, pentachloroanisole, and pentachlorothioanisole), and pentachloro-aniline. Dissolved-phase methyl-triclosan was estimated to contribute up to approximately 40% of the summed target HOC concentrations. Polyethylene passive samplers provided an excellent medium for both non-targeted screening of HOCs not currently included in monitoring programs and tracking brominated and chlorinated chemicals slated for reductions in uses and emissions through international (Stockholm Convention) and binational (Great Lakes) agreements.


Assuntos
Retardadores de Chama/análise , Hidrocarbonetos Clorados/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Éteres Difenil Halogenados/análise , Lagos , Ontário
14.
Environ Sci Technol ; 54(12): 7398-7408, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32422038

RESUMO

Over a third of the world's annual chemical production and sales occur in China. Thus, knowledge of the properties of the substances produced and emitted there is important from a global perspective. The chemical Inventory of Existing Chemical Substances of China (IECSC) lists over 45 000 chemicals. When compared to the North American and European chemical inventories, 6916 substances were found to be unique to the IECSC. We retrieved structural information for 14 938 organic chemicals in the IECSC and determined their overall environmental persistence , bioaccumulation factor (BAF), and long-range transport potential (transfer efficiency) using in silico approaches with the goal of identifying new chemicals with properties that might lead to global contamination issues. Overall, 10% of the 14 938 chemicals were unique to the IECSC and their environmental persistence and BAF were statistically higher than the values for the rest of the IECSC chemicals. We prioritized 27 neutral organic compounds predicted to have prolonged environmental persistence, and high potential for bioaccumulation and long-range transport when compared with polychlorinated biphenyls as a benchmark. We also identified 69 organofluorine compounds with three or more perfluorinated moieties, unique to the IECSC. Screening approaches and results from this study help to identify and prioritize those to be considered in further environmental modeling and monitoring assessments.


Assuntos
Poluentes Ambientais , Bifenilos Policlorados , China , Monitoramento Ambiental , Poluentes Ambientais/análise , Indústrias , Compostos Orgânicos
15.
Dalton Trans ; 2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32232276

RESUMO

Isostructural mixed alkali/alkaline-earth metal tellurite halides BaLiTe2O5X (X = Cl, Br) have been successfully synthesized by a mild hydrothermal method, which possess the [Te2O5]∞ chains formed by the corner-sharing connections of the TeO3 and TeO4 polyhedra. The [Te2O5]∞ chains are bridged via the LiO3 polyhedra to form the [LiTe2O5]∞ layers with 4- and 6-membered rings. The adjacent [LiTe2O5]∞ layers are linked via the BaO9 polyhedra to form the [BaLiTe2O5]∞ double layers, which are further connected via weak Ba-X-Li interactions to generate a 3D framework. Analysis of different lithium tellurites shows that the different arrangements of the Te-O and Li-O units in the lithium tellurites can be attributed to the cation-cation repulsion and lone-pair effect. Both compounds display good thermal stability, wide optical bandgaps (4.25 and 4.13 eV), and large birefringence. First-principles calculations indicate that the TeOn groups and X- determine the optical properties of BaLiTe2O5X (X = Cl, Br).

16.
ACS Nano ; 2020 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-32207915

RESUMO

Rational design and controllable synthesis of efficient and robust electrocatalysts for hydrogen evolution reaction (HER) remain a critical challenge for the renewable energy economy. Herein, heterostructured Nb4N5-xOx-MoS2 (0 < x < 1) anchored on N-doped graphene (defined as Nb4N5-xOx-MoS2/NG) is synthesized by hydrothermal and chemical vapor deposition (CVD) approaches. During the CVD process, MoS2 nanosheets are etched into small pieces and covalently interconnected with Nb4N5-xOx to form fine Nb4N5-xOx-MoS2 heterostructures, which possess abundant interfaces and fully exposed edge active sites. The as-prepared Nb4N5-xOx-MoS2 heterostructures with Nb-(N,S)-Mo bridges provide desired electron density, which exhibit excellent chemisorption ability for both H and water, significantly improving the intrinsic HER activity. Meanwhile, the covalently connected Nb4N5-xOx-MoS2 heterostructures together with chemical coupling of Nb4N5-xOx-MoS2 and N-doped graphene improve the structural stability and ensure fast electron transfer in the Nb4N5-xOx-MoS2/NG nanocomposite, further supporting the H2 generation and stability.

17.
Chem Commun (Camb) ; 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32182322

RESUMO

Herein two unprecedented octanuclear Co8 clusters are presented, [Cl@Co8 (TEOA)4(CH3CN)Cl3] (1) and [S@Co8(DEOA)6(NCS)2] (2) (H3TEOA = triethanolamine, H2DEOA = diethanolamine), in which tetrahedral µ4-chloride and in situ generated octahedral µ6-sulfide are used as templates. In spite of them being derivatives of cubes, eight Co atoms in 1 consist of two co-centered tetrahedra of different sizes, whereas in 2 they appear as a rhombohedron formed via elongating a cube along the C3-axis direction. Strong intra-cluster antiferromagnetic interactions were found.

18.
Chemosphere ; 250: 126324, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32135441

RESUMO

Human exposure to formaldehyde, toluene, xylene (FTX) and other volatile organic compounds (VOCs) are associated with negative health impact. To characterize the exposure and health effects of FTX and TVOC from indoor environments, we conducted an extensive monitoring campaign involving 1278 measurements of 472 indoor locations in Harbin, a megacity in China from May 2013 to March 2018. The results showed that household had the highest mean formaldehyde concentration (0.171 ± 0.084 mg m-3) among all types of indoor environments. Meanwhile, there was no significant differences in formaldehyde concentration of the living room, master bedroom, secondary bedroom and study room (p > 0.05), as well as toluene and xylene. The highest mean concentration of toluene, xylene and TVOC was measured in public bath center. Great difference was found between formaldehyde concentrations in 2013 and other years, except 2015. There were great positive nonlinear correlations between the indoor temperature and concentration of formaldehyde (p < 0.01), good negative nonlinear correlations between the finish time of decoration and concentration of formaldehyde (p < 0.01), good positive linear correlations between the relative humidity and concentration of formaldehyde (p < 0.01). A risk assessment methodology was utilized to evaluate the potential adverse health effects of the individual FTX compounds according to their carcinogenicities. The predicted carcinogenic risk of formaldehyde was greater than the threshold value 1E-06 at all environments. The non-carcinogenic risk of TX compounds in the population is negligible. For estimating human health risk exposure, sensitivity analysis showed that more attention should be given to the influential variables such as the level of pollutants.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental/métodos , Compostos Orgânicos Voláteis/análise , Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , China , Formaldeído/análise , Humanos , Medição de Risco , Tolueno/análise , Xilenos/análise
20.
IEEE Trans Cybern ; PP2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32031960

RESUMO

This article addresses the problem of cluster consensus for multiagent systems (MASs) associated with weighted antagonistic interactions. Compared with some existing results, a general communication topology among agents is introduced in this article, where there is no need to confine directed cycles to the root of a spanning tree. By taking into consideration the structures of directed cycles and multiple paths, the judgment of structural balance is simplified significantly. A novel cluster consensus protocol is also proposed for structurally unbalanced digraphs. Moreover, two necessary and sufficient conditions are derived, by which cluster consensus can be achieved in an MAS if and only if its communication topology contains a directed spanning tree. Then, by employing an algebra theorem, a sufficient criterion for the unstable system under a directed cycle is obtained, whether the number of agents on this cycle is odd or even. Some illustrative examples are given to demonstrate the effectiveness of theoretical results.

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