Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 102
Filter
1.
Small ; : e2309922, 2024 Apr 09.
Article in English | MEDLINE | ID: mdl-38593357

ABSTRACT

Self-trapped exciton (STE) luminescence, typically associated with structural deformation of excited states, has attracted significant attention in metal halide materials recently. However, the mechanism of multiexciton STE emissions in certain metal halide crystals remains largely unexplored. This study investigates dual luminescence emissions in HCOO- doped Cs3Cu2I5 single crystals using transient and steady-state spectroscopy. The dual emissions are attributed to intrinsic STE luminescence originating from the host lattice and extrinsic STE luminescence induced by external dopants, respectively, each of which can be triggered independently at distinct energy levels. Theoretical calculations reveal that multiexciton emission originates from structural distortion of the host and dopant STEs within the 0D lattice in their respective excited states. By meticulously tuning the excitation wavelength and selectively exciting different STEs, the dynamic alteration of color change in Cs3Cu2I5:HCOO- crystals is demonstrated. Ultimately, owing to an extraordinarily high photoluminescence quantum yield (99.01%) and a diminished degree of self-absorption in Cs3Cu2I5:HCOO- crystals, they exhibit remarkable X-ray scintillation characteristics with light yield being improved by 5.4 times as compared to that of pristine Cs3Cu2I5 crystals, opening up exciting avenues for achieving low-dose X-ray detection and imaging.

2.
Plant Physiol ; 192(2): 910-926, 2023 05 31.
Article in English | MEDLINE | ID: mdl-36943277

ABSTRACT

Arsenate [As(V)] is a metalloid with heavy metal properties and is widespread in many environments. Dietary intake of food derived from arsenate-contaminated plants constitutes a major fraction of the potentially health-threatening human exposure to arsenic. However, the mechanisms underlying how plants respond to arsenate stress and regulate the function of relevant transporters are poorly understood. Here, we observed that As(V) stress induces a significant Ca2+ signal in Arabidopsis (Arabidopsis thaliana) roots. We then identified a calcium-dependent protein kinase, CALCIUM-DEPENDENT PROTEIN KINASE 23 (CPK23), that interacts with the plasma membrane As(V)/Pi transporter PHOSPHATE TRANSPORTER 1;1 (PHT1;1) in vitro and in vivo. cpk23 mutants displayed a sensitive phenotype under As(V) stress, while transgenic Arabidopsis plants with constitutively active CPK23 showed a tolerant phenotype. Furthermore, CPK23 phosphorylated the C-terminal domain of PHT1;1, primarily at Ser514 and Ser520. Multiple experiments on PHT1;1 variants demonstrated that PHT1;1S514 phosphorylation is essential for PHT1;1 function and localization under As(V) stress. In summary, we revealed that plasma-membrane-associated calcium signaling regulates As(V) tolerance. These results provide insight for crop bioengineering to specifically address arsenate pollution in soils.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Humans , Arabidopsis/genetics , Arabidopsis/metabolism , Arsenates/toxicity , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Calcium Signaling , Phosphate Transport Proteins/metabolism , Phosphates/metabolism , Plants, Genetically Modified/metabolism , Cell Membrane/metabolism
3.
Small ; : e2309233, 2023 Dec 05.
Article in English | MEDLINE | ID: mdl-38050935

ABSTRACT

Perovskite light-emitting diodes (PeLEDs) have shown incalculable application potential in the fields of next-generation displays and light communication owing to the rapidly increased external quantum efficiencies (EQEs). However, most PeLEDs obtain a maximum EQE at small current density (J) region and suffer from severe efficiency roll-off in different extents. Herein, it is demonstrated that the dopant with large dipole moment like KBF4 facilitates the effective dielectric regulation of perovskite emissive layer. The increased dielectric constant lowers the exciton binding energy and suppresses the Auger recombination of the 2D/3D segregated perovskite structure, which improves the photoluminescence quantum yield remarkably at an excitation intensity up to 103  mW cm-2 . Accordingly, the top-emission PeLED that delivers a high maximum EQE above 20% is fabricated and can retain EQE > 10% at an extremely high J of 708 mA cm-2 . These results represent one of the most efficient top-emission PeLEDs with ultra-low efficiency roll-off, which provide a viable methodology for tuning the dielectric response of perovskite films for improved high radiance performance of perovskite electroluminescence devices.

4.
J Environ Sci (China) ; 125: 823-830, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36375964

ABSTRACT

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is a commonly used organophosphate-based flame retardant and can bio-accumulate in human tissues and organs. As its structure is similar to that of neurotoxic organophosphate pesticides, the neurotoxicity of TDCIPP has raised widespread concerns. TDCIPP can increase neuronal apoptosis and induce autophagy. However, its regulatory mechanism remains unclear. In this study, we found that the expression upregulation of the DNA Damage-Inducible Transcript 4 (DDIT4) protein, which might play essential roles in TDCIPP-induced neuronal autophagy and apoptosis, was observed in TDCIPP-treated differentiated rat PC12 cells. Furthermore, we determined the protective effect of the DDIT4 suppression on the autophagy and apoptosis induced by TDCIPP using Western blot (WB) and Flow cytometry (FACS) analysis. We observed that TDCIPP treatment increased the DDIT4, the autophagy marker Beclin-1, and the microtubule-associated protein light chain 3-II (LC3II) expressions and decreased the mTOR phosphorylation levels. Conversely, the suppression of DDIT4 expression increased the p-mTOR expression and decreased cell autophagy and apoptosis. Collectively, our results revealed the function of DDIT4 in cell death mechanisms triggered by TDCIPP through the mTOR signaling axis in differentiated PC12 cells. Thus, this study provided vital evidence necessary to explain the mechanism of TDCIPP-induced neurotoxicity in differentiated PC12 cells.


Subject(s)
Apoptosis , Autophagy , Organophosphates , Transcription Factors , Animals , Rats , Organophosphates/adverse effects , Organophosphorus Compounds , PC12 Cells , TOR Serine-Threonine Kinases/metabolism , Transcription Factors/metabolism
5.
Angew Chem Int Ed Engl ; 62(19): e202302435, 2023 May 02.
Article in English | MEDLINE | ID: mdl-36892282

ABSTRACT

Perovskite single crystals and polycrystalline films have complementary merits and deficiencies in X-ray detection and imaging. Herein, we report preparation of dense and smooth perovskite microcrystalline films with both merits of single crystals and polycrystalline films through polycrystal-induced growth and hot-pressing treatment (HPT). Utilizing polycrystalline films as seeds, multi-inch-sized microcrystalline films can be in situ grown on diverse substrates with maximum grain size reaching 100 µm, which endows the microcrystalline films with comparable carrier mobility-lifetime (µτ) product as single crystals. As a result, self-powered X-ray detectors with impressive sensitivity of 6.1×104  µC Gyair -1 cm-2 and low detection limit of 1.5 nGyair s-1 are achieved, leading to high-contrast X-ray imaging at an ultra-low dose rate of 67 nGyair s-1 . Combining with the fast response speed (186 µs), this work may contribute to the development of perovskite-based low-dose X-ray imaging.

6.
Small ; 18(45): e2204752, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36156416

ABSTRACT

Vacuum vapor deposition (VVD) is a promising way to advancing the commercialization of perovskite light sources owing to its convenience for wafer-scale mass production and compatibility with silicon photonics manufacturing infrastructure. However, the light emission performance of VVD-grown perovskites still lags far behind that of the conventional solution-processed counterparts due to their inferior luminescence properties. Here, a 0D/3D cesium-lead-bromide perovskite composite film is prepared on Si/SiO2 substrates through composition modulation with the VVD method, which exhibits an ultralow amplified spontaneous emission (ASE) threshold down to 14.3 µJ cm-2 in the optimal films, which is on par with that of the solution-processed counterparts. Meanwhile, they also display intriguing operational stability with negligible emission intensity decay under continuous excitation above ASE threshold for 4 h in the air. The outstanding ASE performance mainly originates from the reduced trap density and weakened electron-phonon coupling in the 3D CsPbBr3 phase enabled by the incorporation of the 0D Cs4 PbBr6 phase. Finally, by integrating the composite film with the distributed feedback (DFB) cavity, DFB lasing is achieved with a low threshold of 18.2 µJ cm-2 under nanosecond-pulsed laser pumping, which highlights the potential of VVD-processed perovskites for developing high-performance lasers.

7.
Ecotoxicol Environ Saf ; 229: 113069, 2022 Jan 01.
Article in English | MEDLINE | ID: mdl-34890987

ABSTRACT

As the typical aryl-organophosphate flame retardants (OPFRs), triphenyl phosphate (TPhP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were reported to be estrogen disruptors. However, estrogen receptor α (ERα) binding experiments could not explain their biological effects. In this study, their action on ERα, G protein-coupled estrogen receptor (GPER) and the synthesis of 17ß-estradiol (E2) were investigated using in vitro assays and molecular docking. The results showed that TPhP acted as an ERα agonist and recruited steroid receptor co-activator 1 (SRC1) and 3 (SRC3), which was found for the first time. Unlike TPhP, TDCIPP acted as an ERα antagonist. However, both TPhP and TDCIPP activated the estrogen pathway by GPER in SKBR3 cells which were lack of ERα. Although molecular docking results revealed that both TPhP and TDCIPP could dock into ERα and GPER, their substituent groups and combination mode might affect the receptor activation. In addition, by using estrogen biosynthesis assay in H295R cells, both of TPhP and TDCIPP were found to promote E2 synthesis and E2/T ratio involving their different alteration on levels of progesterone, testosterone and estrone, and expression of various key genes. Our data proposed estrogen-disrupting mechanism frameworks of TPhP and TDCIPP. Moreover, our results will contribute to future construction of adverse outcome pathway (AOP) framework of endocrine disruptors.


Subject(s)
Flame Retardants , Phosphates , Estrogens , Flame Retardants/toxicity , Molecular Docking Simulation , Organophosphates , Organophosphorus Compounds
8.
J Environ Sci Health B ; 57(4): 305-315, 2022.
Article in English | MEDLINE | ID: mdl-35287560

ABSTRACT

A rapid test method for the determination of pesticide toxicity was established by using carboxylesterase (CES) and fluorescence probe ACE-NH based on the principle of enzyme inhibition, and this method was applied to detect the combined toxicity of 18 binary and 24 ternary pesticide combinations commonly used for fruits and vegetables to CES. The results show that chlorpyrifos + carbendazim, carbofuran + carbendazim, imidacloprid + carbendazim, imidacloprid + dimethomorph, dimethoate + dimethomorph, prochloraz + carbendazim and imidacloprid + acetamiprid + carbendazim had synergistic effects under three concentration gradients, it indicated that most binary combinations containing carbendazim or imidacloprid had synergistic effects. Based on structure-activity relationship between pesticides and CES, pesticides with phosphate ester bonds had great toxicity to CES, or though they have no toxicity to CES alone, they showed a strong synergistic effect when mixed with other pesticides. Pesticides with amide or ester bond had medium toxicity and little synergistic effect. Pesticides with urea, carbamate or nitrite nitrogen group had little or no toxicity, while there was a strong synergistic effect after mixing with other pesticides. The test method and results in this study can provide scientific basis for risk assessment of cumulative exposure to mixed pesticide residues.


Subject(s)
Pesticides , Carboxylesterase , Esters , Fluorescence , Fluorescent Dyes , Pesticides/toxicity , Technology
9.
BMC Microbiol ; 21(1): 197, 2021 06 28.
Article in English | MEDLINE | ID: mdl-34182947

ABSTRACT

BACKGROUND: Microfluidic chip detection technology is considered a potent tool for many bioanalytic applications. Rapid detection of foodborne pathogens in the early stages is imperative to prevent the outbreak of foodborne diseases, known as a severe threat to human health. Conventional bacterial culture methods for detecting foodborne pathogens are time-consuming, laborious, and lacking in pathogen diagnosis. To overcome this problem, we have created an embedded paper-based microchip based on isothermal loop amplification (LAMP), which can rapidly and sensitively detect foodborne pathogens. RESULTS: We embed paper impregnated with LAMP reagent and specific primers in multiple reaction chambers of the microchip. The solution containing the target pathogen was injected into the center chamber and uniformly distributed into the reaction chamber by centrifugal force. The purified DNA of Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus, and Vibrio parahaemolyticus has been successfully amplified and directly detected on the microchip. The E. coli O157:H7 DNA was identified as low as 0.0134 ng µL- 1. Besides, the potential of this microchip in point-of-care testing was further tested by combining the on-chip sample purification module and using milk spiked with Salmonella spp.. The pyrolyzed milk sample was filtered through a polydopamine-coated paper embedded in the inside of the sample chamber. It was transported to the reaction chamber by centrifugal force for LAMP amplification. Then direct chip detection was performed in the reaction chamber embedded with calcein-soaked paper. The detection limit of Salmonella spp. in the sample measured by the microchip was approximately 12 CFU mL- 1. CONCLUSION: The paper embedded LAMP microchip offers inexpensive, user-friendly, and highly selective pathogen detection capabilities. It is expected to have great potential as a quick, efficient, and cost-effective solution for future foodborne pathogen detection.


Subject(s)
Food Microbiology/methods , Foodborne Diseases/microbiology , Lab-On-A-Chip Devices , Molecular Diagnostic Techniques/instrumentation , Nucleic Acid Amplification Techniques/instrumentation , Paper , Foodborne Diseases/prevention & control
10.
Ecotoxicol Environ Saf ; 213: 112026, 2021 Apr 15.
Article in English | MEDLINE | ID: mdl-33582411

ABSTRACT

Bisphenol A (BPA) is a typical environmental endocrine disruptor that can migrate into organisms through skin contact, breathing, diet and various other approaches. The reproductive toxicity and neurotoxicity of BPA has been confirmed by several toxicological studies. However, the neurotoxicity of BPA is still controversial. In the present study, we used PC12 cells as a model to investigate the mechanism of BPA-induced neuronal apoptosis. BPA exposure reduced cell viability, altered cell morphology and aggravated intracellular Lactate dehydrogenase (LDH) release, intracellular Ca2+ concentration, Reactive oxygen species (ROS) levels, apoptosis and the reduction in the mitochondrial transmembrane potential (ΔΨm). Moreover, the results of the Western blot (WB) and Real-time quantitative polymerase chain reaction (RT-qPCR) assays indicated that the expression levels of Nur77 in the BPA group were down-regulated and accompanied by the downregulation of the NF-κb/Bcl-2 proteins and the upregulation of cleaved-caspase 3, which is a marker of apoptosis. However, these changes were significantly reversed with the upregulation of the Nur77 protein by introducing plasmids carrying the nur77 gene. These results indicated that BPA-induced apoptosis was closely related to Nur77-mediated inhibition of the NF-κb/Bcl-2 pathway.


Subject(s)
Benzhydryl Compounds/toxicity , Endocrine Disruptors/toxicity , Phenols/toxicity , Animals , Apoptosis , Cell Survival , Orphan Nuclear Receptors , PC12 Cells , Proto-Oncogene Proteins c-bcl-2/metabolism , Rats , Reactive Oxygen Species/metabolism
11.
Anal Bioanal Chem ; 412(4): 861-870, 2020 Feb.
Article in English | MEDLINE | ID: mdl-31865416

ABSTRACT

In this paper, we report the use of a smartphone and B, N, and S co-doped carbon dots (BNS-CDs) as a promising peroxidase mimic to quantify hydrogen peroxide (H2O2). The synthesized BNS-CDs exhibited excellent peroxidase-like activity to catalyze the reaction of the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) with H2O2 to generate a blue oxide product (ox-TMB) with maximum absorption at 652 nm. Steady-state kinetic analysis demonstrated that the BNS-CDs showed much higher affinity than natural horseradish peroxidase (HRP) for H2O2 due to their small size and larger specific surface area. A smartphone colorimetric readout device was employed to record the RGB (red green blue) value of the ox-TMB solution via the Android application Color Grab for quantitative detection. A good linear relationship (R2 = 0.9970) between the H2O2 concentration and |R-Rblank| value was obtained in the range of 3-30 µM with a limit of detection (LOD) of 0.8 µM. The current method was successfully applied to determine H2O2 in mouthwash and milk with recoveries of 92.70-108.30%. The developed assay is a promising portable detection platform for H2O2 with good sensitivity and selectivity, simple operation, fast response, and low cost. Graphical abstract.


Subject(s)
Carbon/chemistry , Colorimetry/instrumentation , Hydrogen Peroxide/analysis , Milk/chemistry , Mouthwashes/analysis , Animals , Benzidines/chemistry , Biomimetic Materials/chemistry , Catalysis , Equipment Design , Food Analysis/instrumentation , Limit of Detection , Peroxidase/chemistry , Smartphone/instrumentation
12.
Mikrochim Acta ; 187(12): 660, 2020 11 17.
Article in English | MEDLINE | ID: mdl-33201307

ABSTRACT

Blue carbon dots (BCDs) and red gold nanoclusters modified by bovine serum albumin (BSA-Au NCs) were selected as luminescent nanomaterials, and the nanohybrid materials were successfully prepared and applied to the fluorescent measurement of copper ions. The prepared ratio fluorescent probe has two emission peaks near 452 and 654 nm under an excitation of 330 nm. The fluorescence intensity was gradually quenched because Au NCs was aggregated in the presence of Cu2+, resulting in a gradation of the fluorescent color from red to pink to purple to blue for visual detection. BCDs have almost the same fluorescence intensity due to their light stability and chemical inertness to Cu2+ and serve as a background reference in the sensing system. Under the optimal condition, the detection limit (LOD) is 16 nM, the linear range is 0.05-1.85 µM, and the coefficient of determination R2 is 0.9987 for copper determination. Compared with other single probes, the ratio fluorescent probe in the current study has good water solubility, low cytotoxicity, and is easy to synthesize. The nanoprobe provides a high-quality and sensitive visible light platform for monitoring copper ions. Graphical abstract.


Subject(s)
Carbon/chemistry , Copper/analysis , Fluorescent Dyes/chemistry , Gold/chemistry , Metal Nanoparticles/chemistry , Quantum Dots/chemistry , Limit of Detection , Microscopy, Electron, Transmission , Reproducibility of Results , Spectrum Analysis/methods , X-Ray Diffraction
13.
Nano Lett ; 17(12): 7330-7338, 2017 12 13.
Article in English | MEDLINE | ID: mdl-29110483

ABSTRACT

Recently, two-dimensional (2D) organic-inorganic perovskites emerged as an alternative material for their three-dimensional (3D) counterparts in photovoltaic applications with improved moisture resistance. Here, we report a stable, high-gain phototransistor consisting of a monolayer graphene on hexagonal boron nitride (hBN) covered by a 2D multiphase perovskite heterostructure, which was realized using a newly developed two-step ligand exchange method. In this phototransistor, the multiple phases with varying bandgap in 2D perovskite thin films are aligned for the efficient electron-hole pair separation, leading to a high responsivity of ∼105 A W-1 at 532 nm. Moreover, the designed phase alignment method aggregates more hydrophobic butylammonium cations close to the upper surface of the 2D perovskite thin film, preventing the permeation of moisture and enhancing the device stability dramatically. In addition, faster photoresponse and smaller 1/f noise observed in the 2D perovskite phototransistors indicate a smaller density of deep hole traps in the 2D perovskite thin film compared with their 3D counterparts. These desirable properties not only improve the performance of the phototransistor, but also provide a new direction for the future enhancement of the efficiency of 2D perovskite photovoltaics.

14.
Environ Toxicol ; 32(6): 1784-1791, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28181390

ABSTRACT

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is one of the widely used organophosphorus flame retardants (OPFRs), which are regarded as suitable substitutes for brominated flame retardants (BFRs). Previously, we have validated the toxicity of TDCIPP in PC12 cells owing to the induced alterations in GAP43, NF-H, CaMK2a/2b, and tubulin α/ß proteins; however, limited information is currently available on the toxicity and mechanism of TDCIPP. In the present study, cytotoxicity effects were evaluated by exposing PC12 cells to different concentrations of TDCIPP (0-50 µM) for 4 days. To explore the possible mechanisms through which cytotoxicity is induced, changes in intracellular [Ca2+ ]i levels and the activation of calmodulin dependent protein kinase 2 (CaMK2), c-Jun N-terminal kinase (JNK), extracellular regulated protein kinases (ERK1/2), and p38 mitogen-activated protein kinases (MAPK) pathways were evaluated. Furthermore, PC12 cells were pretreated with CaMK2 inhibitor KN93 to investigate the relationship between TDCIPP-induced phosphorylation of CaMK2 and activation of JNK, ERK1/2, and p38 MAPK pathways. Our results indicate that TDCIPP-induced toxicity might be associated with the overload of [Ca2+ ]i levels, increased phosphorylation of CaMK2, and activation of the JNK, ERK1/2, and p38 MAPK pathways, the lattermost of which was further demonstrated to be partially elicited by the CaMK2 phosphorylation.


Subject(s)
Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Flame Retardants/toxicity , MAP Kinase Signaling System/drug effects , Organophosphorus Compounds/toxicity , Animals , Cell Survival/drug effects , Enzyme Activation/drug effects , JNK Mitogen-Activated Protein Kinases/metabolism , Mitogen-Activated Protein Kinase 3/metabolism , Mitogen-Activated Protein Kinases/metabolism , PC12 Cells , Phosphorylation , Protein Serine-Threonine Kinases/metabolism , Rats , p38 Mitogen-Activated Protein Kinases/metabolism
15.
Opt Express ; 24(22): 25876-25884, 2016 Oct 31.
Article in English | MEDLINE | ID: mdl-27828536

ABSTRACT

ZnO nanorod arrays were synthesized by hydrothermal method with two different zinc salts as precursors: zinc acetate and zinc nitrate. Different anions in solution distinctly influence the intrinsic defects in ZnO nanostructures, resulting in different photoluminescence properties. The defects induced by precursors were systematically studied by photoluminescence spectroscopy, X-ray photoelectron spectrometer and electron paramagnetic resonance. The results show that zinc acetate precursor mainly introduces zinc vacancy to the lattice while ZnO nanorods obtained from zinc nitrate contain more interstitial oxygen.

16.
Nanotechnology ; 27(26): 265201, 2016 Jul 01.
Article in English | MEDLINE | ID: mdl-27196112

ABSTRACT

We report on the feasible control of the threshold voltage (V th) in ultra-thin ZnO nanobelt FETs by using substoichiometric molybdenum trioxide (MoO x , x < 3) either as a modification layer on the surface of ZnO nanobelts or as electrodes instead of the widely used Ti/Au. ZnO nanobelt FETs using Ti/Au as the electrodes usually exhibit a negative threshold voltage, indicating n-channel depletion mode behavior, whereas ZnO FETs with MoO x /Au electrodes instead of Ti/Au show a positive shift of threshold voltage, exhibiting an n-channel type enhancement mode, which can be explained by a high Schottky barrier created at the interface of MoO x and the ZnO channel. In contrast, the decoration on the surface of ZnO channel by MoO x significantly increases the zero-bias conductivity and electron carrier concentration, and then negatively shifts the threshold voltage. We propose that MoO x thin film may play a passivation effect role, much more so than the doping effect role, due to the large amount of adsorbed species on as-grown ZnO nanobelts, especially oxygen species.

17.
Phys Chem Chem Phys ; 18(44): 30484-30490, 2016 Nov 09.
Article in English | MEDLINE | ID: mdl-27782266

ABSTRACT

Understanding the influence of light on ion migration in organic-inorganic halide perovskite (OIHP) materials is important to understand the photostability of perovskite solar cells. We reveal that light could greatly reduce the ion migration energy barrier in both polycrystalline and single crystalline OIHP. The activation energies derived from conductivity measurement under 0.25 Sun decrease to less than one half of the values in the dark. A typical ion drift velocity in CH3NH3PbI3 polycrystalline films is 1.2 µm s-1 under 1 Sun, compared with 0.016 µm s-1 under 0.02 Sun. Ion migration across the photoactive layers in most OIHP devices thus takes only subseconds under 1 Sun illumination, which is much shorter than what it was thought to take. Most important of all, ion migration through a single crystal surface is still too slow to be observed even after illumination for two days due to the large ion diffusion activation energy, >0.38 eV.

18.
Chemistry ; 21(42): 14862-70, 2015 Oct 12.
Article in English | MEDLINE | ID: mdl-26337902

ABSTRACT

The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12 O40 ](3-) (PW12 ) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73 Al0.22 (OH)2 [PW12 O40 ]0.04 ⋅0.98 H2 O (Mg3 Al-PW12 ) has been successfully obtained by applying a spontaneous flocculation method. The Mg3 Al-PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3 Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3 Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2 -Z' type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2-propanol :Vwater =2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3 Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3 Al-PW12 -catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction.

19.
Phys Chem Chem Phys ; 17(45): 30712-20, 2015 Nov 11.
Article in English | MEDLINE | ID: mdl-26527195

ABSTRACT

We report polymer photodetectors (PPDs) with an evident photomultiplication (PM) phenomenon, based on a sandwich structure ITO/PEDOT:PSS/P3HT:PC71BM(100:1)/Al. A similar device structure has been reported in our previous work, showing great potential as a new type of high performance PPD. However, we found more interesting new phenomena from these PPDs. Solid evidence is provided to prove the existence of photogenerated electron transport in the almost hole-only active layer under an applied bias. The transport of photogenerated electrons leads to electron accumulation near the Al electrode and the electron redistribution, which strongly affect the EQE spectral shape and the transient response of the PPDs. Our conclusion is further confirmed by confirmatory devices with a structure of Al(1)/P3HT:PC71BM(100:1)/Al(2). EQE spectra and transient Jph curves of the confirmatory devices accord well with our speculation. This discovery may provide a new insight to increase the response speed of PM type PPDs by adjusting the photogenerated electron distribution in the active layer. Considering that the PM type PPDs have much higher EQE than the traditional organic photodetectors, the improvement may further extend its potential applications with low cost.

20.
Ecotoxicol Environ Saf ; 104: 220-5, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24726932

ABSTRACT

The effect of concurrent degradation of tetrabromobisphenol A (TBBPA) by the strain Ochrobactrum sp. T under aerobic condition was investigated. The results demonstrated that four extra energy source-addition systems still followed pseudo-first order kinetics. The addition of ethanol or glucose could promote the biodegradation ability of Ochrobactrum sp. T to TBBPA, and 90.1 percent and 77.5 percent of TBBPA (5mg L(-1)) could be removed with corresponding TBBPA half-lives of 26 and 36h, respectively, after 96h reaction. Comparatively, the degradation efficiency of the sole TBBPA system was only 72.9 percent under the same condition. In contrast, two other co-substrates 2,4,6-tribromophenol (TBP) and bisphenol A (BPA) showed a negative effect on the TBBPA biodegradation, and the degradation efficiencies of TBBPA were achieved as 44.7 percent and 67.4 percent, respectively. For the TBBPA+TBP system, the competitive inhibition for the TBBPA debromination was less than the inhibition of the toxicity to the bacterium. While for the TBBPA+BPA system, the degradation of TBBPA could be promoted at the beginning of the reaction, and was then inhibited slightly with further prolonging of reaction time. This is probably due to the substrates being oxidized, and BPA can consume partial oxygen and provide the electrons during the concurrent biodegradation process. In addition, although higher estrogenic activity could be detected for the debrominated intermediates in TBBPA co-degradation process than the original TBBPA, the estrogenicity of the whole system still decreased finally after 96h degradation.


Subject(s)
Ochrobactrum/metabolism , Polybrominated Biphenyls/metabolism , Aerobiosis , Benzhydryl Compounds/chemistry , Biodegradation, Environmental , Environmental Pollutants/metabolism , Estrogens/chemistry , Phenols/chemistry
SELECTION OF CITATIONS
SEARCH DETAIL