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Investigation of photo-induced electron transfer between amino-functionalized graphene quantum dots and selenium nanoparticle and it's application for sensitive fluorescent detection of copper ions
摘要： Copper ions play an essential role in some biological processes. Currently, there is a need for the development of convenient and reliable analytical methods for the Cu2+ measurement. In the present work, a sensitive fluorescence method was developed for the determination of copper ions. Amino-functionalized graphene quantum dots (af-GQDs) and selenium nanoparticles (Se NPs) were synthetized, respectively, and they were characterized via transmission electron microscope, infrared spectrum analysis and X-ray photoelectron spectrum measurement. Photo-induced electron transfer (PET) between the prepared two nanomaterials could effectively quench the fluorescence of af-GQDs. Cu(II) was reduced to Cu(I) in the presence ascorbic acid and Cu2Se was finally generated on Se NPs surface, which led to the declined PET efficiency and inhibited the fluorescence quenching of af-GQDs. The change in fluorescence intensity was linearly correlated to the logarithm of the Cu2+ concentration from 1 nM to 10 μM, with a detection limit of 0.4 nM under the optimal conditions. The detections of copper ions in water samples were realized via standard addition method and the recovery values varied from 98.7% to 103%. The proposed fluorescence method was also employed to analyze the uptake of Cu2+ into human cervical carcinoma HeLa cells and cisplatin-resistant HeLa cells (HeLa/DDP cells). The experimental results indicate that the decreased hCTR1 expression level in HeLa/DDP cells weakened the uptake of copper ions into these drug-resistant tumor cells.
关键词： photo-induced electron transfer,selenium nanoparticles,cellular uptake,copper ions,fluorescence quenching,amino-functionalized graphene quantum dots
更新于2025-09-11 14:15:04
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Analysis of 1?MeV electron irradiation-induced performance degradation in the germanium bottom cell of triple-junction solar cells using temperature-dependent photoluminescence measurements
摘要： Temperature-dependent photoluminescence spectra of the germanium bottom cell of triple-junction solar cells unirradiated and irradiated with 1 MeV electrons were measured in the 10–300 K temperature range. In unirradiated germanium bottom cell, the spectra show that the PL intensity increases with temperature but slightly decreases at around 250 K because of the intrinsic defect. However, in irradiated germanium bottom cell, the spectra show that there are two negative thermal quenching processes (10–90 K and 200–270 K) and two usual thermal quenching processes (90–200 K and 270–300 K) as a result of the radiation-induced defects Ec (cid:1) 0.37 eV and Ec (cid:1) 0.12 eV.
关键词： Electron irradiation,germanium bottom cell,thermal quenching,temperature-dependent photoluminescence
更新于2025-09-11 14:15:04
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Oxygen Concentration Distribution Measurement of the Nozzle Flow Field by Toluene/Acetone Planar Laser-Induced Fluorescence
摘要： Planar laser-induced ?uorescence (PLIF) of toluene and acetone is performed for visualization of spatial distribution of oxygen in gas and oxygen mixing region in the nozzle ?ow ?eld. The principle of the calibration methods of oxygen concentration distribution is expounded in this paper. As the two tracers had different situations on oxygen quenching effect, the ratio of the ?uorescence images of the two tracers could be used to measure the oxygen concentration in the mixed area. In this way, the ratio of ?uorescence signal intensity of toluene to acetone was found to be linearly related to oxygen concentration. By using this calibration relationship, we can measure the oxygen concentration distribution of the nozzle ?ow ?eld with an accuracy of 12.6%. It indicates that this measurement method can be applied in a turbulent ?ow ?eld. The variation trend of oxygen concentration distribution in the nozzle ?ow ?eld can be analyzed by capturing multiple PLIF images in time sequence, which has the important reference value for the development of the nozzle burner ?ame.
关键词： nozzle ?ow ?eld,oxygen concentration distribution,?uorescence signal quenching,planar laser-induced ?uorescence,dual-tracers
更新于2025-09-11 14:15:04
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A Mn4+-doped oxyfluoride phosphor with remarkable negative thermal quenching and high color stability for warm WLEDs
摘要： Red-emitting phosphors composed of Mn4+-activated fluorides have attracted considerable interest for their applications in warm white light-emitting diodes (WLEDs). However, in addition to moisture instability, the unsatisfactory thermal stability of these phosphors limits their industrial applications. In this study, a novel red phosphor of CsMoO2F3:Mn4+ was synthesized via simple coprecipitation. This red phosphor exhibits an orthorhombic structure with a bandgap of ~3.43 eV. The Mn4+ ions occupy Mo6+ sites at the centers of [MoO2F4]2- octahedrons. This phosphor shows narrow emission around ～633 nm excited by 450 nm blue-chip with high color purity of 99.58%. Satisfactorily, this phosphor exhibits excellent thermal stability and a strong negative-thermal-quenching. The total PL intensity of CsMoO2F3:3.88%Mn4+ phosphor at 275 K strengthens to ~540% relative to that at 25 K, and its relative emission intensity preserves about 129.3% when the temperature rises from room temperature to 423 K (150 ℃). It also shows admirable color stability with a slight chromaticity shift (ΔE) of only ~33.9 × 10?3 in the temperature region from 298 to 473 K. Furthermore, a warm WLED was fabricated by the mixture of red-emitting CsMoO2F3:3.88%Mn4+ and the yellow-emitting YAG:Ce3+ phosphors with a blue-emitting InGaN LED chip. The device exhibits low correlated color temperature (3983 K) and high color-rendering index (Ra = 81.3). With the increasing drive current from 20 mA to 120 mA, the chromaticity coordinate variation (CCV) is only (-0.0163, 0.0202). All these results indicate that the CsMoO2F3:Mn4+ phosphor holds tremendous potential for practical applications in high-power lighting and display with high-performance WLEDs.
关键词： oxyfluoride,red phosphor,luminescence,negative thermal quenching,Mn4+
更新于2025-09-11 14:15:04
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A Novel Rare Earth Ion Fluorescent Probe towards the Trace Detection of 2,4,6-Trinitrotoluene Based on Fluorescence Resonance Energy Transfer
摘要： This paper reports a resonance energy transfer-fluorescence quenching of the core-shell structure of CaMoO4:Tb3+@SiO2 modified by amino group on the surface for the ultrasensitive and ultratrace detection of 2,4,6-trinitrotoluene (TNT) in solution environments. Organic amine was covalently modified onto the surface of silica shell to form a hybrid monolayer of amino group. The particle can specifically bind TNT species by the charge-transfer complexing or acid-base pairing interactions between electron-rich amine ligands and electron-deficient aromatic rings. The resultant TNT-amine complexes bound at the silica surface can strongly suppress the fluorescence emission of the chosen dye by the fluorescence resonance energy transfer (FRET) from CaMoO4:Tb3+ fluorescence donor to the irradiative TNT-amine acceptor through intermolecular polar-polar interactions at spatial proximity. The nanoparticle can sensitively detect down to 1 nM TNT with the use of only 10 μL of solution (2 pg TNT). The simple FRET-based nanoparticle sensors reported here exhibit a high and stable fluorescence brightness, strong analyte affinity and good assembly flexibility and can thus find many applications in the detection of ultratrace analytes.
关键词： Fluorescence quenching,FRET,Ultratrace detection,2,4,6-Trinitrotoluene,Rare earth ion
更新于2025-09-11 14:15:04
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Tailoring the ligand shell for the control of cellular uptake and optical properties of nanocrystals
摘要： In this short review, the main challenges in the use of hydrophobic nanoparticles in biomedical application are addressed. It is shown how to overcome the different issues by the use of a polymeric encapsulation system, based on an amphiphilic polyisoprene-block-poly(ethylene glycol) diblock copolymer. On the basis of this simple molecule, the development of a versatile and powerful phase transfer strategy is summarized, focusing on the main advantages like the adjustable size, the retained properties, the excellent shielding and the diverse functionalization properties of the encapsulated nanoparticles. Finally, the extraordinary properties of these encapsulated nanoparticles in terms of toxicity and specificity in a broad in vitro test is demonstrated.
关键词： quantum dots,biolable,poylmeric micelles,cellular uptake,fluorescence quenching
更新于2025-09-10 09:29:36
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Prospects of applications of fluorescent sensors based on zinc(II) and boron(III) bis(dipyrromethenate)s
摘要： To date, synthesis and study of luminophores with practically significant sensory characteristics are the most promising direction of the oligopyrrole dyes chemistry. The results of sensory characteristics study of zinc(II) and boron(III) bis(dipyrromethenate)s to the various analytes presence in solutions and gas mixtures are discussed in this mini-review. The main aim of the mini-review is to examine the causes and mechanisms of the spectral signal of zinc(II) bis(dipyrromethenate)s to the presence of various nature analytes. The prospects of applications of fluorescent sensors based on zinc(II) and boron(III) bis(dipyrromethenate)s are discussed.
关键词： Zinc(II) bis(dipyrromethenate),Fluorescence quenching,Fluorescence,bis(BODIPY),Gas analyzer,Sensor,Supramolecular system
更新于2025-09-10 09:29:36
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Fluorescent Chemosensor for Pb2+ Based on 1,2,4-Triazole
摘要： A new fluorescent sensor for Pb2+ based on functionalized 1,2,4-triazole is synthesized. The crystal structure and molecular conformation is confirmed by single crystal X-ray diffraction. Its binding properties investigated by fluorescence spectroscopy show that it can selectively bind Pb2+ with fluorescence quenching.
关键词： 2,4-triazole,Pb2+,fluorescence quenching,synthesis
更新于2025-09-10 09:29:36
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Investigation of alpha particle tracks in GEM-type structures based on SQS mode
摘要： In this study, the performance of two GEM-type structures for the detection of alpha particle tracks in gaseous detectors based on SQS mode is presented. The operation of these structures was investigated in the presence of air, pure argon and P10 gas. By increasing the applied voltage to GEM-type plates beyond a certain value, each GEM-type’s through-hole individually entered to the SQS mode, when detector operated in the P10 gas. This mode was followed by the appearance of visible streamers in the space of holes exposed to alpha radiation. Two types of Thick Gas Electron Multipliers (TGEM) and Electron Multiplier Assemblies (EMA) with different geometries, as well as a cascade configuration of EMAs, were designed and constructed. Depending on the hole diameters in these structures, the location of the input beams can be determined optically with a specific resolution.
关键词： Alpha particle tracks,Electron multiplier assembly (EMA),Thick gas electron multipliers (TGEM),Self-quenching streamer mode (SQS mode)
更新于2025-09-10 09:29:36
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Effect of linear energy transfer on the scintillation properties of Ce:Gd3Al2Ga3O12
摘要： We analyzed the scintillation properties of Ce:Gd3Al2Ga3O12 (GAGG), which are dependent on linear energy transfer (LET). The rise in the scintillation temporal profiles was slow at high LET, whereas the decay did not significantly depend on LET. The slow rise at high LET could be explained as follows. Competition among multiple excited states for energy transfer to a nearby Ce3+ ion led to failure in energy transfer for some of the excited states. Subsequent competition occurred among the residual excited states for energy transfer to the Ce3+ ions located far from the original position of the excited states, followed by quenching.
关键词： Excitation density,Energy transfer,Quenching,Scintillation
更新于2025-09-10 09:29:36