| 1. |
- Wang, Meiyang, et al.
(författare)
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Promoted photocatalytic degradation and detoxication performance for norfloxacin on Z-scheme phosphate-doped BiVO4/graphene quantum dots/P-doped g-C3N4
- 2021
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866. ; 274
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Tidskriftsartikel (refereegranskat)abstract
- A novel kind of Z-scheme ternary heterojunctions phosphate-doped BiVO4/graphene quantum dots/P-doped g-C3N4 (BVP/GQDs/PCN) were fabricated for the visible light degradation of norfloxacin (NOR), a typical antibiotic. Compared with binary type-II heterojunction phosphate-doped BiVO4/PCN (BVP/PCN), Z-scheme BVP/GQDs/PCN exhibited promoted interfacial charge transfer efficiency and broadened visible light response range, endowing them with excellent photodegradation activity and mineralization ability in NOR degradation. A high NOR degradation rate of 86.3% with a removal rate of total organic carbon (TOC) of 55.8% can be achieved over BVP/GQDs/PCN for 120 min visible light irradiation, which is an excellent performance compared with ever reported similar photocatalysts. In particular, because of the enhanced redox ability of photogenerated charges and the generation of multiple active species (eg. [rad]OH and [rad]O2−) over Z-scheme photocatalytic system, the accumulation of highly toxic degradation intermediates was greatly inhibited, and a better detoxication performance was obtained compared to PCN and BVP/PCN. This work may shed light on the inhibition of highly toxic degradation intermediates of antibiotics by regulating the charge transfer mechanism, photocatalytic active species, and the degradation pathway of antibiotics.
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| 2. |
- Bhat, P. Narayana, et al.
(författare)
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THE THIRD FERMI GBM GAMMA-RAY BURST CATALOG : THE FIRST SIX YEARS
- 2016
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics Publishing (IOPP). - 0067-0049 .- 1538-4365. ; 223:2
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Tidskriftsartikel (refereegranskat)abstract
- Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two.-ray bursts (GRBs) every three days. Here, we present the third of a series of catalogs of GRBs detected by GBM, extending the second catalog by two more years through the middle of 2014 July. The resulting list includes 1405 triggers identified as GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM-detected GRBs. For each GRB, the location and main characteristics of the prompt emission, the duration, peak flux, and fluence are derived. The latter two quantities are calculated for the 50-300 keV energy band where the maximum energy release of GRBs in the instrument reference system is observed, and also for a broader energy band from 10 to 1000 keV, exploiting the full energy range of GBM's low-energy [NaI[Tl)] detectors. Using statistical methods to assess clustering, we find that the hardness and duration of GRBs are better fit by a two-component model with short-hard and long-soft bursts than by a model with three components. Furthermore, information is provided on the settings and modifications of the triggering criteria and exceptional operational conditions during years five and six in the mission. This third catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.
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| 3. |
- Burgess, J. Michael, et al.
(författare)
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AN OBSERVED CORRELATION BETWEEN THERMAL AND NON-THERMAL EMISSION IN GAMMA-RAY BURSTS
- 2014
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 784:2
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Tidskriftsartikel (refereegranskat)abstract
- Recent observations by the Fermi Gamma-ray Space Telescope have confirmed the existence of thermal and non-thermal components in the prompt photon spectra of some gamma-ray bursts (GRBs). Through an analysis of six bright Fermi GRBs, we have discovered a correlation between the observed photospheric and non-thermal gamma-ray emission components of several GRBs using a physical model that has previously been shown to be a good fit to the Fermi data. From the spectral parameters of these fits we find that the characteristic energies, E-p and kT, of these two components are correlated via the relation E-p proportional to T-alpha which varies from GRB to GRB. We present an interpretation in which the value of the index alpha indicates whether the jet is dominated by kinetic or magnetic energy. To date, this jet composition parameter has been assumed in the modeling of GRB outflows rather than derived from the data.
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| 4. |
- Cao, Kequan, et al.
(författare)
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Constructing ZnTe Spherical Quantum Well for Efficient Light Emission
- 2024
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Ingår i: Nano Letters. - 1530-6984.
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Tidskriftsartikel (refereegranskat)abstract
- ZnTe colloidal semiconductor nanocrystals (NCs) have shown promise for light-emitting diodes (LEDs) and displays, because they are free from toxic heavy metals (Cd). However, so far, their low photoluminescence (PL) efficiency (∼30%) has hindered their applications. Herein, we devised a novel structure of ZnTe NCs with the configuration of ZnSe (core)/ZnTe (spherical quantum well, SQW)/ZnSe (shell). The inner layer ZnTe was grown at the surface of ZnSe core with avoiding using highly active and high-risk Zn sources. Due to the formation of coherently strained heterostructure which reduced the lattice mismatch, and the thermodynamic growth of ZnTe, the surface or interface defects were suppressed. A high PL efficiency of >60% was obtained for the green light-emitting ZnSe/ZnTe/ZnSe SQWs after ZnS outer layer passivation, which is the highest value for colloidal ZnTe-based NCs. This work paves the way for the development of novel semiconductor NCs for luminescent and display applications.
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| 5. |
- Cheng, Chunyan, et al.
(författare)
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Near-Unity Quantum Yield ZnSeTe Quantum Dots Enabled by Controlling Shell Growth for Efficient Deep-Blue Light-Emitting Diodes
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Ingår i: Advanced Functional Materials. - 1616-301X.
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Tidskriftsartikel (refereegranskat)abstract
- Core–shell structural ZnSeTe/ZnSe/ZnS quantum dots (QDs) have attracted great attention for advanced illumination and displays because of their environmentally friendly composition, but still suffering from poor photoluminescence (PL) and electroluminescence (EL) performance due to severe non-radiative charge recombination. Herein, a stepwise injection shell growth process to manipulate the monomer concentration and ensure adequate growth interval is devised, which enables the controllable uniform epitaxial growth of ZnSe and ZnS shells on the ZnSeTe core, thus relieving the lattice distortion and defects to greatly suppress the non-radiative charge recombination. The ZnSeTe/ZnSe/ZnS QDs presented deep-blue emission at 448 nm with narrow full width at half maximum (FWHM, 23 nm), and near-unity PL quantum yield (PLQY, ≈100%) The light-emitting diodes (LEDs) based on the QDs exhibited a high external quantum efficiency (EQE) of 10.9%, a maximum brightness of 10240 cd cm−2, and a high current efficiency of 7.9 cd A−1, demonstrating a good performance for deep blue QDs LEDs (QLEDs) This shell growth strategy will be an effective approach to achieving efficient QDs and QLEDs.
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| 6. |
- Huang, Zheng, et al.
(författare)
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Constructing type-II CuInSe2/CuInS2 core/shell quantum dots for high-performance photoelectrochemical cells
- 2024
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Ingår i: SCIENCE CHINA Materials. - 2095-8226. ; 67:1, s. 134-142
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Tidskriftsartikel (refereegranskat)abstract
- CuInSe2 (CISe) quantum dots (QDs) have shown promising applications in photoelectrochemical (PEC) cells due to their nontoxicity, high extinction coefficient, and wide optical absorption range; however, their low PEC performance prevents their applications due to insufficient charge carrier separation and severe charge recombination. Herein, CISe/CuInS2 (CISe/CIS) core/shell structured QDs are designed and constructed to promote charge separation and diminish interface defects. Afterward, the copper vacancy (VCu) state of CISe/CIS QDs is enriched by modulating the precursor molar ratios of In/Cu. Therefore, the radiative recombination of the conduction band edge electrons with the VCu localized holes becomes dominant and prolongs the carrier lifetime compared with intrinsic band-to-band recombination, thus promoting charge separation. Consequently, the VCu-rich CISe/CIS QD-based photoanode shows a high photocurrent density of 8.0 mA cm−2, which is one of the highest values reported for CISe QD-based PEC cells. This work provides an effective approach for promoting charge carrier separation and transfer through surface or intrinsic defect mediation for PEC applications of I–III–VI semiconductor nanocrystals.
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| 7. |
- Zhu, Ying, et al.
(författare)
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Effects of divalent copper on tetracycline degradation and the proposed transformation pathway
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 27:5, s. 5155-5167
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Tidskriftsartikel (refereegranskat)abstract
- To reveal the characteristics of tetracycline (TC) photocatalytic degradation under Cu(II) coexistence, effects of Cu(II) on TC photocatalytic degradation by ZnO nanoparticles (ZnO NPs) as a function of pH, humic acid (HA), and initial Cu(II) concentration were investigated. Interaction of TC with Cu(II) in the treatment process was analyzed by circular dichroism (CD) spectroscopy, while TC degradation pathway was investigated by high-performance liquid chromatography-mass spectrometry. Sixty-five percent and ninety-one percent TC degradation within 60 min in the absence and presence of Cu(II), respectively, was reported. Both adsorption and photocatalytic degradation of TC under Cu(II) coexistence increased with increasing pH from 3 to 6, while decreased with further increase in pH. HA inhibited the degradation of TC by ZnO NPs both in the presence as well absence of Cu(II), while TC degradation decreased from 91 to 73% and from 73 to 37% in the presence and absence of Cu(II), respectively. TC degradation by ZnO NPs first increased then decreased with increasing Cu(II). Maximum TC degradation (about 94%) was obtained in the optimum concentration range of Cu(II) (0.05-0.15 mmol/L). In addition, there was a lag effect between TC adsorption and degradation on ZnO NPs. TC degradation was improved via Cu(II)-TC surface complexation and followed N-demethylation and hydroxylation routes. This study could be of potential importance in extrapolating the transformation of TC or other antibiotics under the coexistence of heavy metals in water.
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