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1.
J Nat Prod ; 86(6): 1449-1462, 2023 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-37243616

RESUMO

Colorectal cancer (CRC) is an exceptionally deadly disease, whereas effective therapeutic drugs for CRC have declined over the past few decades. Natural products have become a reliable source of anticancer drugs. Previously we isolated an alkaloid named (-)-N-hydroxyapiosporamide (NHAP), which exerts potent antitumor effects, but its effect and mechanism in CRC remain unclear. This study aimed to reveal the antitumor target of NHAP and identify NHAP as a promising lead compound for CRC. Various biochemical methods and animal models were used to investigate the antitumor effect and molecular mechanism for NHAP. These results showed that NHAP exhibited potent cytotoxicity, induced both apoptosis and autophagic cell death of CRC cells, and inhibited the NF-κB signaling pathway by blocking the interaction of the TAK1-TRAF6 complex. NHAP also markedly inhibited CRC tumor growth in vivo without obvious toxicities and possessed good pharmacokinetic characteristics. These findings identify, for the first time, that NHAP is an NF-κB inhibitor with potent antitumor activity in vitro and in vivo. This study clarifies the antitumor target of NHAP against CRC, which will contribute to the future development of NHAP as a novel therapeutic lead compound for CRC.


Assuntos
Alcaloides , Antineoplásicos , Neoplasias Colorretais , Animais , Alcaloides/farmacologia , Alcaloides/uso terapêutico , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/metabolismo , NF-kappa B/metabolismo , Fator 6 Associado a Receptor de TNF/metabolismo , Fator 6 Associado a Receptor de TNF/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto
2.
J Org Chem ; 87(21): 14058-14067, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36162105

RESUMO

Two highly oxygenated pentacyclic polyketides with two new carbon skeletons, trichopsistide A (1) and trichopsistide B (2), were isolated from the plant endophyte Trichoderma koningiopsis WZ-196 derived from the leaf of Rubia podantha Diels. The structures of these polyketides with full configurations were determined by comprehensive spectroscopic analysis, computer-assisted structure elucidation software, computational calculation, and X-ray crystal diffraction. Among them, 1 represented the first example of an unprecedented 5/6/6/6/5 pentacyclic ketal-containing polyketide pyridine alkaloid, and 2 possessed a novel 6/6/6/6/5 pentacyclic ketal-containing polyketide scaffold fused with an α-pyrone. The plausible biosynthetic route for 1 and 2 was also proposed. Moreover, biological activity assays showed that 1 and 2 possessed inhibitory effects on the NF-κB signaling pathway with IC50 values of 14.77 and 8.58 µM, respectively. Furthermore, 1 and 2 could also inhibit the expression of IκBα and p65 phosphorylation, decrease the expression of MCP-1, E-selectin, and IL-8 at the mRNA level, and inhibit the TNF-α-induced nuclear translocation of p65.


Assuntos
Hypocreales , Policetídeos , NF-kappa B/metabolismo , Policetídeos/química , Estrutura Molecular , Hypocreales/metabolismo , Transdução de Sinais
3.
J Clin Monit Comput ; 35(3): 663-670, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-32388652

RESUMO

A 67-year-old male patient with chronic obstructive pulmonary disease was admitted to a hospital in northern Taiwan for progressive dyspnea and productive cough with an enlarged left upper lobe tumor (5.3 × 6.8 × 3.9 cm3). Previous chest auscultation on outpatient visits had yielded diffuse wheezes. A localized stridor (fundamental frequency of 125 Hz) was captured using a multichannel electronic stethoscope comprising four microelectromechanical system microphones. An energy-based localization algorithm was used to successfully locate the sound source of the stridor caused by tumor compression. The results of the algorithm were compatible with the findings obtained from computed tomography and bronchoscopy (mean radius = 9.40 mm and radial standard deviation = 14.97 mm). We demonstrated a potential diagnostic aid for pulmonary diseases through sound-source localization technology based on respiratory monitoring. The proposed technique can facilitate detection when advanced imaging tools are not immediately available. Continuing effort on the development of more precise estimation is warranted.


Assuntos
Neoplasias , Sons Respiratórios , Idoso , Auscultação , Eletrônica , Humanos , Pulmão , Masculino , Sons Respiratórios/etiologia
4.
Ecotoxicol Environ Saf ; 170: 9-17, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30508754

RESUMO

A novel gelatin/PVA composite nanofiber band loaded with bayberry tannin (GPNB-BT) was prepared by electrostatic spinning and crosslinking for extraction of uranium (VI) from simulated seawater. The influential factors of tannin loaded on the nanofiber band were investigated in detail. Surface morphology and fiber diameter of GPNB-BT were studied by Scanning Electron Microscopy (SEM). Functional groups of GPNB-BT were investigated by Fourier Transform Infrared Spectrometer (FTIR). The adsorption process and mechanism of uranium on GPNB-BT was characterized by Energy Dispersive X-ray (EDX) and X-ray Photoelectron Spectroscopy (XPS). The results revealed that the BT had been stably solidified on the GPNB. Compared with other tannin-immobilized membranes, the nano-network structure of GPNB-BT with 200-400 nm diameter of fibers can promote solidification of tannins and improve adsorption capacity of GPNB-BT for uranium. The maximum adsorption capacity of the GPNB-BT for uranium is 170 mg/g at the optimal pH of 5.5 in 80 mg/L of initial uranium concentration and 1.4 µg/g even at extremely low initial concentration of 3 µg/L in the simulated seawater for 24 h. The GPNB-BT with good hydraulic properties, floatability and adsorption capacity for uranium is expected to be widely used in separation and enrichment of uranium in seawater and radioactive waste water.


Assuntos
Gelatina/química , Nanofibras/química , Água do Mar/química , Taninos/química , Urânio/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Myrica/química , Espectroscopia de Infravermelho com Transformada de Fourier
5.
Chemistry ; 23(41): 9857-9871, 2017 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-28498613

RESUMO

A series of AlNa bimetallic ammonium metal formate frameworks (AlNa AMFFs) have been prepared by employing various ammoniums from NH4+ to large linear polyammoniums. The series consists of six perovskites of (412 ⋅63 ) topology for mono-ammoniums, two chiral (49 ⋅66 ) frameworks incorporating polyethylene ammoniums, two niccolites with (412 ⋅63 )(49 ⋅66 ) topology containing diammoniums, and two layered compounds made of 2D (4,4) AlNa formate sheets intercalated by small diammoniums. The first ten compounds present the structural hierarchy of (412 ⋅63 )m (49 ⋅66 )n framework topologies for (m, n)=(1, 0), (0, 1), and (1, 1), respectively, in parallel to the homometallic AMFFs for divalent metals. The symmetry lowering, asymmetric formate bridges, and different hydrogen-bonding strengths appeared in the bimetallic structures owing to the different charge and size of Al3+ and Na+ seemingly inhibits the occurrence of phase transitions for more than half the AlNa AMFFs within the series, and the bimetallic members undergoing phase transitions show different transition behaviors and dielectric properties compared with the homometallic analogs. Anisotropic/negative/zero thermal expansions of the materials could be rationally attributed to the librational motion, or flip movement between different sites, of the ammonium cations, and the coupled change of AlNa formate frameworks. The thermal and IR spectroscopic properties have also been investigated.

6.
Chemistry ; 22(18): 6199-203, 2016 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-26892832

RESUMO

A niccolite series of [bnH2 (2+) ][M(HCOO)3 ]2 (bnH2 (2+) =1,4-butyldiammonium) shows four kinds of metal-dependent phase transitions, from high temperature para-electric phases to low-temperature ferro-, antiferro-, glass-like, and para-electric phases. The conformational flexibility of bnH2 (2+) and the different size, mass, and bonding character of the metal ion lead to various disorder-order transitions of bnH2 (2+) in the lattice and relevant framework modulations, thus different phase transitions and dielectric responses. The magnetic members display a coexistence or combination of electric and magnetic orderings in the low-temperature region.

7.
Inorg Chem ; 55(20): 10075-10082, 2016 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-27366822

RESUMO

A series of isostructural hydrazinium lanthanide (Ln) formate framework compounds of [NH2NH3][Ln(HCOO)4] for Ln3+ ions from Tb3+ to Lu3+ and Y3+ have been successfully prepared by utilizing NH2NH3+. The compounds crystallize in orthorhombic polar space group Pca21, with cell parameters at 180 K of a = 18.2526(7)-18.1048(5) Å, b = 6.5815(2)-6.5261(2) Å, c = 7.6362(3)-7.5044(2) Å, and V = 917.33(6)-886.67(4) Å3, showing the effect of lanthanide contraction. The compounds possess polar perovskite-like structures incorporating the hydrazinium cations in the cavities of the NaCl-like framework, in which the Ln3+ ions in a bicapped trigonal prism are connected by anti-anti and syn-anti formate groups. The N-H···Oformate hydrogen-bonding interactions are between the hydrazinium cations and the anionic framework. One anti-anti formate group is frustrated by the competitive N-H···Oformate hydrogen-bonding interactions. It thus twists or flips upon warming, resulting in large anisotropic thermal expansion and negative thermal expansion below 180 K. A comparison with the transition metal and magnesium analogues revealed that the structural compactness, tighter binding of the hydrazinium cation by the framework, and symmetrically better match between the framework and ammonium cation for Ln compounds could inhibit the occurrence of phase transition in the series. The IR spectroscopic, thermal, and magnetic properties are investigated.

8.
J Environ Manage ; 177: 45-52, 2016 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-27082256

RESUMO

Integrating powdered activated carbon (PAC) into wastewater tertiary treatment is a promising technology to reduce organic micro-pollutant (OMP) discharge into the receiving waters. To take advantage of the existing tertiary filter, PAC was pre-embedded inside the filter bed acting as a fixed-bed adsorber. The pre-embedding (i.e. immobilization) of PAC was realized by direct dosing a PAC solution on the filter top, which was then promoted to penetrate into the filter media by a down-flow of tap water. In order to examine the effectiveness of this PAC pre-embedded filter towards OMP removal, batch adsorption tests, representing PAC contact reactor (with the same PAC mass-to-treated water volume ratio as in the PAC pre-embedded filter) were performed as references. Moreover, as a conventional dosing option, PAC was dosed continuously with the filter influent (i.e. the wastewater secondary effluent with the investigated OMPs). Comparative results confirmed a higher OMP removal efficiency associated with the PAC pre-embedded filter, as compared to the batch system with a practical PAC residence time. Furthermore, over a filtration period of 10 h (approximating a realistic filtration cycle for tertiary filters), the continuous dosing approach resulted in less OMP removal. Therefore, it was concluded that the pre-embedding approach can be preferentially considered when integrating PAC into the wastewater tertiary treatment for OMP elimination.


Assuntos
Carvão Vegetal/química , Filtração/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Filtração/instrumentação , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/análise , Poluentes Químicos da Água/química
9.
Angew Chem Int Ed Engl ; 55(6): 2097-100, 2016 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-26709724

RESUMO

The compound [CH3 CH2 NH3][Cu(HCOO)3] undergoes a phase transition at 357 K, from a perovskite to a diamond structure, by heating. The backward transition can be driven by pressure at room temperature but not cooling under ambient or lower pressure. The rearrangement of one long copper-formate bond, the switch of bridging-chelating mode of the formate, the alternation of N-H⋅⋅⋅O H-bonds, and the flipping of ethylammonium are involved in the transition. The strong N-H⋅⋅⋅O H-bonding probably locks the metastable diamond phase. The two phases display magnetic and electric orderings of different characters.

10.
J Environ Manage ; 160: 98-104, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26093103

RESUMO

Spent granular activated carbons (sGACs) for drinking water treatments were reused via pulverizing as low-cost adsorbents for micro-pollutant adsorption from a secondary treated wastewater effluent. The changes of physicochemical characteristics of the spent carbons in relation to the fresh carbons were determined and were correlated to the molecular properties of the respective GAC influents (i.e. a surface water and a groundwater). Pore size distribution analysis showed that the carbon pore volume decreased over a wider size range due to preloading by surface water, which contains a broader molecular weight distribution of organic matter in contrast to the groundwater. However, there was still considerable capacity available on the pulverized sGACs for atrazine adsorption in demineralized water and secondary effluent, and this was particularly the case for the groundwater spent GAC. However, as compared to the fresh counterparts, the decreased surface area and the induced surface acidic groups on the pulverized sGACs contributed both to the lower uptake and the more impeded adsorption kinetic of atrazine in the demineralized water. Nonetheless, the pulverized sGACs, especially the one preloaded by surface water, was less susceptible to adsorption competition in the secondary effluent, due to its negatively charged surface which can repulse the accessibility of the co-present organic matter. This suggests the reusability of the drinking water spent GACs for micro-pollutant adsorption in the treated wastewater.


Assuntos
Carvão Vegetal/química , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Adsorção , Atrazina/química , Humanos , Tamanho da Partícula , Águas Residuárias , Poluentes Químicos da Água/química
11.
Angew Chem Int Ed Engl ; 54(8): 2534-7, 2015 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-25585529

RESUMO

An ammonium Mg formate framework, prepared by using di-protonated 1,3-propanediamine (pnH2(2+)), has a rare three-dimensional binodal (4(12)⋅6(3))(4(9)⋅6(6))3 Mg-formate framework with elongated cavities accommodating pnH2(2+)⋅⋅⋅H2O⋅⋅⋅pnH2(2+) assemblies. It displays a para-electric to antiferroelectric phase transition at 275 K, with a 36-fold multiple unit cell from the high-temperature cell of 1703 Å(3) to the low-temperature one of 60,980 Å(3). The change results from the disorder-order transition of the pnH2(2+) cations and H2O molecules. The motions of these components freeze in a stepwise fashion on going from the high-temperature disorder state to the low-temperature ordered state, triggering the switch from high to low dielectric constants, and the spatial limitation of such motions contributes the strong dielectric anisotropy.

12.
Angew Chem Int Ed Engl ; 54(38): 11093-6, 2015 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-26245518

RESUMO

The A-site mixed-ammonium solid solutions of metal-organic perovskites [(NH2 NH3 )x (CH3 NH3 )1-x ][Mn(HCOO)3 ] (x=1.00-0.67) exhibit para- to ferroelectric diffuse phase transitions with lowered transition temperatures from x=1.00 to 0.67. These properties are due to the decreased framework distortion and polarization in their low temperature ferroelectric phases caused by the increased CH3 NH3 (+) concentration.

13.
Chemistry ; 20(48): 15872-83, 2014 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-25303719

RESUMO

We present here the compound [NH4][Cu(HCOO)3], a new member of the [NH4][M(HCOO)3] family. The Jahn-Teller Cu(2+) ion leads to a distorted 4(9)⋅6(6) chiral Cu-formate framework. In the low-temperature (LT) orthorhombic phase, the Cu(2+) is in an elongated octahedron, and the NH4⁺ ions in the framework channel are off the channel axis. From 94 to 350 K the NH4⁺ ion gradually approaches the channel axis and the related modulation of the framework and the hydrogen-bond system occurs. The LT phase is simple antiferroelectric (AFE). The material becomes hexagonal above 355 K. In the high-temperature (HT) phase, the Cu(2+) octahedron is compressed, and the NH4⁺ ions are arranged helically along the channel axis. Therefore, the phase transition is one from LT simple AFE to HT helical AFE. The temperature-dependent structure evolution is accompanied by significant thermal and dielectric anomalies and anisotropic thermal expansion, due to the different status of the NH4⁺ ions and the framework modulations, and the structure-property relationship was established based on the extensive variable-temperature single-crystal structures. The material showed long range ordering of antiferromagnetism (AFM), with low dimensional character and a Néel temperature of 2.9 K. Therefore, within the material AFE and AFM orderings coexist in the low-temperature region.

14.
Chemistry ; 20(4): 1146-58, 2014 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-24375515

RESUMO

We present three Mg-formate frameworks, incorporating three different ammoniums: [NH4][Mg(HCOO)3] (1), [CH3CH2NH3][Mg(HCOO)3] (2) and [NH3(CH2)4NH3][Mg2(HCOO)6] (3). They display structural phase transitions accompanied by prominent dielectric anomalies and anisotropic and negative thermal expansion. The temperature-dependent structures, covering the whole temperature region in which the phase transitions occur, reveal detailed structural changes, and structure-property relationships are established. Compound 1 is a chiral Mg-formate framework with the NH4(+) cations located in the channels. Above 255 K, the NH4(+) cation vibrates quickly between two positions of shallow energy minima. Below 255 K, the cations undergo two steps of freezing of their vibrations, caused by the different inner profiles of the channels, producing non-compensated antipolarization. These lead to significant negative thermal expansion and a relaxor-like dielectric response. In perovskite 2, the orthorhombic phase below 374 K possesses ordered CH3CH2NH3(+) cations in the cubic cavities of the Mg-formate framework. Above 374 K, the structure becomes trigonal, with trigonally disordered cations, and above 426 K, another phase transition occurs and the cation changes to a two-fold disordered state. The two transitions are accompanied by prominent dielectric anomalies and negative and positive thermal expansion, contributing to the large regulation of the framework coupled the order-disorder transition of CH3CH2NH3(+). For niccolite 3, the gradually enhanced flipping movement of the middle ethylene of [NH3(CH2)4NH3](2+) in the elongated framework cavity finally leads to the phase transition with a critical temperature of 412 K, and the trigonally disordered cations and relevant framework change, providing the basis for the very strong dielectric dispersion, high dielectric constant (comparable to inorganic oxides), and large negative thermal expansion. The spontaneous polarizations for the low-temperature polar phases are 1.15, 3.43 and 1.51 µC cm(-2) for 1, 2 and 3, respectively, as estimated by the shifts of the cations related to the anionic frameworks. Thermal and variable-temperature powder X-ray diffraction studies confirm the phase transitions, and the materials are all found to be thermally stable up to 470 K.

15.
Chemistry ; 20(27): 8269-73, 2014 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24909766

RESUMO

A metal-cyanide framework undergoes a dehydration-rehydration triggered reversible single-crystal-to-single-crystal transformation. The resulting accordion-like contraction-expansion corresponds to a size change along the c axis as much as 24 %. This anisotropic response arises from the cooperativity among the water molecules, K ions, and CN groups between the unique two-dimensional bimetallic layers through weak interactions of hydrogen bonds and electrostatic (ionic) interactions. The key role of the water molecules in the dehydration-rehydration process is revealed by solid-state (1)H NMR spectroscopy and dielectric measurements.

16.
Inorg Chem ; 53(16): 8708-16, 2014 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-25072411

RESUMO

We report an ammonium uranyl formate framework of formula [(C2H5)4N][U2O4(HCOO)5], prepared by using components of tetraethylammonium, uranyl, and formate. The compound possesses a layered structure of anionic uranyl-formate wavy sheets and intercalated (C2H5)4N(+) cations. The sheet consists of pentagonal bipyramidal uranyl cations connected by equatorial anti-anti and anti-syn HCOO(-) bridges, and it has a topology of 3(3)·4(3)·5(4) made of edge-sharing square and triangle grids. The high-temperature (HT) phase belongs to the chiral but nonpolar tetragonal space group P42(1)m. In the structure, one HCOO(-) is 2-fold disordered, showing a flip motion between the two anti-syn orientations. On cooling, this flip motion slowed and finally froze, leading to a phase transition at ∼200 K. The low-temperature (LT) structure is monoclinic and polar in space group P2(1); the cations shift, and the layers slide. Especially, the concerted and net shifts of the ammonium cations toward the -b direction, with respect to the anionic sheets, result in an estimated spontaneous polarization of 0.86 µC cm(-2) in LT. The phase transition is thus para- to ferro-electric, in Aizu notation 42mF2, accompanied by significant, anisotropic dielectric anomalies, with a quite significant thermal hysteresis. Variable-temperature luminescent spectroscopy and differential scanning calorimetry confirmed the transition and provided further information. The structure-property relationship is established.

17.
Environ Sci Technol ; 48(5): 2885-92, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24502417

RESUMO

Potassium permanganate (KMnO4) preoxidation is capable of enhancing cyanobacteria cell removal. However, the impacts of KMnO4 on cell viability and potential toxin release have not been comprehensively characterized. In this study, the impacts of KMnO4 on Microcystis aeruginosa inactivation and on the release and degradation of intracellular microcystin-LR (MC-LR) and other featured organic matter were investigated. KMnO4 oxidation of M. aeruginosa exhibited some kinetic patterns that were different from standard chemical reactions. Results indicated that cell viability loss and MC-LR release both followed two-segment second-order kinetics with turning points of KMnO4 exposure (ct) at cty and ctr, respectively. KMnO4 primarily reacted with dissolved and cell-bound extracellular organic matter (mucilage) and resulted in a minor loss of cell viability and MC-LR release before the ct value reached cty. Thereafter, KMnO4 approached the inner layer of the cell wall and resulted in a rapid decrease of cell viability. Further increase of ct to ctr led to cell lysis and massive release of intracellular MC-LR. The MC-LR release rate was generally much slower than its degradation rate during permanganation. However, MC-LR continued to be released even after total depletion of KMnO4, which led to a great increase in MC-LR concentration in the treated water.


Assuntos
Microcistinas/metabolismo , Microcystis/efeitos dos fármacos , Permanganato de Potássio/farmacologia , Sobrevivência Celular , Cinética , Toxinas Marinhas , Microcystis/metabolismo , Permanganato de Potássio/química , Toxinas Biológicas , Purificação da Água/métodos
18.
Sci Rep ; 14(1): 19727, 2024 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-39183210

RESUMO

This study addresses the growing anxiety and depression among Chinese university students by evaluating and ranking music education strategies to alleviate these issues. We integrates Fuzzy Analytic Hierarchy Process (FAHP) and Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). FAHP was utilized to determine the weight of factors such as academic pressures, social relationships, and cultural norms, while fuzzy TOPSIS ranked the effectiveness of music education interventions based on these weights. The results revealed that 'Mental health stigma' and 'Academic Pressures and Rigidity' are among the highest weighted factors, significantly impacting student anxiety. 'Music Appreciation and Music-Based Self-Care' emerged as the most effective strategy. These results highlight the importance of direct involvement in music-related activities for improving student mental health.


Assuntos
Saúde Mental , Música , Estudantes , Humanos , Estudantes/psicologia , Universidades , Masculino , Música/psicologia , Feminino , China , Adulto Jovem , Lógica Fuzzy , Ansiedade/terapia , Ansiedade/prevenção & controle , Depressão/terapia , Adulto
19.
Nanomaterials (Basel) ; 14(3)2024 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-38334586

RESUMO

The construction of semiconductor heterojunction photocatalysts that improve the separation and transfer of photoinduced charge carriers is an effective and widely employed strategy to boost photocatalytic performance. Herein, we have successfully constructed a CdS/Ag/Bi2WO6 Z-scheme heterojunction with an Ag-bridge as an effective charge transfer channel by a facile process. The heterostructure consists of both CdS and Ag nanoparticles anchored on the surface of Bi2WO6 nanosheets. The photocatalytic efficiency of the CdS/Ag/Bi2WO6 system was studied by the decontamination of tetracycline (TC) and Rhodamine B (RhB) under visible light irradiation (λ ≥ 420). The results exhibited that CdS/Ag/Bi2WO6 shows markedly higher photocatalytic performance than that of CdS, Bi2WO6, Ag/Bi2WO6, and CdS/Bi2WO6. The trapping experiment results verified that the •O2- and h+ radicals are the key active species. The results of photoluminescence spectral analysis and photocurrent responses indicated that the CdS/Ag/Bi2WO6 heterojunctions exhibit exceptional efficiency in separating and transferring photoinduced electron-hole pairs. Based on a series of characterization results, the boosted photocatalytic activity of the CdS/Ag/Bi2WO6 system is mostly due to the successful formation of the Ag-bridged Z-scheme heterojunction; these can not only inhibit the recombination rate of photoinduced charge carriers but also possess a splendid redox capacity. The work provides a way for designing a Z-scheme photocatalytic system based on Ag-bridged for boosting photocatalytic performance.

20.
Inorg Chem ; 51(24): 13363-72, 2012 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-23214977

RESUMO

We report the synthesis, crystal structures, IR, and thermal, dielectric, and magnetic properties of a new series of ammonium metal formate frameworks of [HONH(3)][M(II)(HCOO)(3)] for M = Mn, Co, Ni, Zn, and Mg. They are isostructural and crystallize in the nonpolar chiral orthorhombic space group P2(1)2(1)2(1), a = 7.8121(2)-7.6225(2) Å, b = 7.9612(3)-7.7385(2) Å, c = 13.1728(7)-12.7280(4) Å, and V = 819.27(6)-754.95(4) Å(3). The structures possess anionic metal formate frameworks of 4(9)·6(6) topology, in which the octahedral metal centers are connected by the anti-anti formate ligands and the hydroxylammonium is located orderly in the channels, forming strong O/N-H···O(formate) hydrogen bonds with the framework. HONH(3)(+) with only two non-H atoms favors the formation of the dense chiral 4(9)·6(6) frameworks, instead of the less dense 4(12)·6(3) perovskite frameworks for other monoammoniums of two to four non-H atoms because of its small size and its ability to form strong hydrogen bonding. However, the larger size of HONH(3)(+) compared to NH(4)(+) resulted in simple dielectric properties and no phase transitions. The three magnetic members (Mn, Co, and Ni) display antiferromagnetic long-range ordering of spin canting, at Néel temperatures of 8.8 K (Mn), 10.9 K (Co), and 30.5 K (Ni), respectively, and small spontaneous magnetizations for the Mn and Ni members but large magnetization for the Co member. Thermal and IR spectroscopic properties are also reported.

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