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Selective recognition of Cr (VI) ion as Cr <sub/>2</sub> O <sub/>7</sub><sup>2?</sup> in aqueous medium using CTAB‐capped anthracene‐based nanosensor: Application to real water sample analysis
摘要： Surfactant‐capped nanoparticles of 9, 10‐diphenyl anthracene prepared by reprecipitation method found highly fluorescent due to aggregation‐induced enhanced emission (AIEE). Cetyltrimethyl ammonium bromide (CTAB) surfactant not only generated positive zeta potential on the surface of nanoparticles to attract anions of interest but also stabilized nanoparticles into brick‐shape morphology. The fluorescence of nanoparticles is quenched by Cr2O7 ion very significantly in comparison with other diverse ions, namely, MnO4, S2O8 showed increase in the fluorescence of nanoparticles, the interference found is negligible in the Cr (VI) analysis. The selectivity and sensitivity of nanoparticles for recognition of Cr2O7 were explored by systematic fluorescence titration. The fluorescence quenching data fits into the usual Stern‐Volmer equation. A calibration curve constructed by plotting quenching of fluorescence (ΔF) against concentration of Cr (VI) exhibiting a linear fit in the equation, ΔF = 3070x, is used for the estimation of chromium concentration (x). The correlation coefficient value R2 = 0.998 obtained from curve is nearly equal to 1 indicates linear fit between quenching data and concentration of Cr (VI). The estimated values of limit of detection (LOD) in the method 0.01392 μg.mL?1 is far below the permissible value of Cr (VI) 0.05 μg.mL?1 in drinking water approved by world health organization (WHO) and United State Environmental Protection Agency (USEPA). The proposed method of Cr (VI) detection is applied for real sample collected from hard chrome deposition industry from nearby region. The amount of Cr (VI) estimated by present method is comparable with AAS determination for the same samples.
关键词： Diphenylanthracene nanoparticles,Cr (VI) ion,CTAB,aggregation induced enhanced emission,electrostatic interaction
更新于2025-09-04 15:30:14
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High-performance GaAs nanowire cathode for photon-enhanced thermionic emission solar converters
摘要： GaAs nanowire cathodes with exponential doping and graded Al composition structures are proposed for photon-enhanced thermionic emission (PETE) devices. The conversion ef?ciency models with these two nanowire cathodes are deduced on the basis of one-dimensional continuity equations. The conversion ef?ciency as a function of wire length, wire width, Al composition distribution, cathode temperature, emissive surface and back interface recombination velocity are also simulated, respectively. Results show that exponential doping and graded Al composition cathode structures can obviously improve the conversion ef?ciency of devices through introducing a built-in electric ?eld along the growth direction of nanowire. Besides, the optimum wire length and wire width range are 300–340 nm and 5.9–6.4 lm, respectively. Moreover, wider Al composition range is bene?cial to achieve higher conversion ef?ciency. These simulations provide an interesting attempt to explore the working mechanism of GaAs nano-based PETE devices and are expected to be veri?ed by the experimental results in the future.
关键词： exponential doping,graded Al composition,photon-enhanced thermionic emission,GaAs nanowire,conversion efficiency
更新于2025-09-04 15:30:14
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Hybrid anatomo-functional imaging of coronary artery disease: Beneficial irrespective of its core components
摘要： Coronary artery disease (CAD) is the most common and important cause of ischemic heart disease, with major implications on global morbidity and mortality. Non-invasive testing is crucial in the diagnostic and prognostic work-up of patients with or at risk of CAD, and also to guide decision making in terms of pharmacologic and revascularization therapy. The traditional paradigm is to view anatomic (i.e., coronary computed tomography) and functional imaging (e.g., myocardial perfusion scintigraphy) tests as opposing alternatives. Such approach is too reductionist and does not capitalize on the strengths of each type of test while risking to overlook the inherent limitations. The combination of anatomic and functional tests in a logic of hybrid imaging holds the promise of overcoming the limitations inherent to anatomic and functional testing, enabling more accurate diagnosis, prognosis, and guidance for revascularization in patients with CAD.
关键词： hybrid imaging,single-photon emission computed tomography,computed tomography,Coronary artery disease
更新于2025-09-04 15:30:14
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Dicyanoisophorone-Based Near-Infrared Emission Fluorescent Probe for Detecting NAD(P)H in Living Cells and <i>in Vivo</i>
摘要： NADH and NADPH are ubiquitous coenzymes in all living cells and play vital roles in numerous redox reactions in cellular energy metabolism. To accurately detect the distribution and dynamic changes of NAD(P)H under physiological condition is essential for understanding its biological functions and pathological roles. In this work, we developed a near-infrared (NIR) emission fluorescent small-molecule probe (DCI-MQ) composed of a dicyanoisophorone chromophore conjugated with a quinolinium moiety for in vivo NAD(P)H detection. DCI-MQ owns the advantages of high water solubility, rapid response, extraordinary selectivity, great sensitivity (detection limit of 12 nM), low cytotoxicity and a NIR emission (660 nm) in response to NAD(P)H. Moreover, the probe DCI-MQ was successfully applied for the detection and imaging of endogenous NAD(P)H in both living cells and tumor-bearing mice, which provides an effective tool for the study of NAD(P)H-related physiological and pathological processes.
关键词： NAD(P)H,near-infrared emission,fluorescent probe,bioimaging,dicyanoisophorone
更新于2025-09-04 15:30:14
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Bright Orange Electroluminescence from Lead-Free Two-Dimensional Perovskites
摘要： Lead halide perovskites are important materials for solar cells and light emitting diodes (LEDs), but the toxicity of lead is a matter of concern for these and other commercial applications. Here, we demonstrate a lead-free two-dimensional (2D) Ruddlesden-Popper-type (C18H35NH3)2SnBr4 perovskite with a strong emission from the self-trapped states, whose photoluminescence quantum yields in colloidal suspension and in film are 88% and 68%, respectively. The insulating character of the organic oleylamine cation prevents electronic band formation between the [SnBr6]4- octahedron layers, which results in the Stokes-shifted orange emission. Electroluminescence of these 2D lead-free perovskite materials was demonstrated in an inverted LED structure with a low turn-on voltage of 2.2 V and a luminance of 350 cd/m2.
关键词： orange emission,two-dimensional perovskites,self-trapped states,lead-free,electroluminescence
更新于2025-09-04 15:30:14
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Visualizing the Initial Step of Self-Assembly and the Phase Transition by Stereogenic Amphiphiles with Aggregation-Induced Emission
摘要： Many highly ordered structures with smart functions are generated by self-assembly with stimuli responsiveness. Despite the electron microscopes enable us to directly observe the end products, they are hard to visualize the initial step and the kinetic stimuli-responsive behavior of self-assembly. Here, we report the design and synthesis of stereogenic amphiphiles, namely (Z)-TPE-OEG and (E)-TPE-OEG, with aggregation-induced emission (AIE) characteristics from the hydrophobic tetraphenylethene core and thermoresponsive behavior from the hydrophilic oligoethylene glycol monomethyl ether chain. The two isomers can be easily isolated by high-performance liquid chromatography and characterized by 2D NMR spectroscopy. While (Z)-TPE-OEG self-assembles into vesicles, its (E)-cousin forms micelles in water. The initial step of their self-assembly processes can be visualized based on AIE characteristics, with the sensitivity much higher than the method based on transmittance measurement. The entrapment and release capabilities of the (Z)-stereogenic amphiphile are demonstrated by employing pyrene as a guest. The thermoresponsive behavior of the (Z)-amphiphile results in its continuous phase transition from microscopic self-assembly to macroscopic aggregation, which is successfully visualized in-situ by confocal laser scanning microscopy accompanied with AIE technique. Such kinetic process shows different stages according to the microscopic visualization and these stages have never been monitored through roughly observing the appearance of precipitates. It is anticipated that this study can deepen the understanding of the self-assembly processes for better monitoring and controlling them in different systems.
关键词： phase transition,aggregation-induced emission,self-assembly,amphiphiles,microscopic visualization
更新于2025-09-04 15:30:14
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Synthesis of novel luminescent copper nanoclusters with substituent driven self-assembly and aggregation induced emission (AIE)
摘要： We demonstrate a novel strategy to synthesize highly stable luminescent mercaptoimidazole-capped copper nanoclusters (CuNCs). Herein we depict that a simple modification of substituents on the mercaptoimidazole ligand dictates the self-assembly and photophysical properties of the clusters. These CuNCs showed aggregation induced emission (AIE) with a large Stokes shift (Dk 4 200 nm), and the formation of clusters corresponding to Cu4L3 was confirmed by MALDI-TOF mass spectrometric analyses. Interestingly, these nanoclusters e?ectively internalize into mammalian cells while retaining their fluorescent properties and exhibit negligible toxicity.
关键词： mercaptoimidazole-capped,luminescent copper nanoclusters,AIE,aggregation induced emission,self-assembly
更新于2025-09-04 15:30:14
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Rare earth phosphors based on spherical infinite coordination polymers
摘要： A novel luminescent infinite coordination polymer (Tb-M), constructed by the interaction between Tb3+ ions and 3,5-pyrazoledicarboxylate and malonate linkers, was prepared by water microwave-assisted synthesis. The material self-assembles into amorphous microspherical particles. Under UV excitation, a very intense green luminescence is observed by the naked eye at room temperature for Tb-M. A Gd3+ analogue compound (Gd-M) was also synthesized. Successful attempts at codoping Tb-M and Gd-M samples with Eu3+ and Dy3+ ions were carried out and different emission colors were obtained, including white-light emission.
关键词： infinite coordination polymers,rare earth phosphors,microwave-assisted synthesis,luminescence,white-light emission
更新于2025-09-04 15:30:14
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Electrical characteristics and carrier injection mechanisms of atomic layer deposition synthesized n-SnO<sub>2</sub>/p-Si heterojunction
摘要： The SnO2/Si heterojunction was prepared through depositing SnO2 thin film onto p-Si substrate by means of atomic layer deposition using TDMASn (tetrakis(dimethylamino)tin) and deionized water as precursors. We found that there were three types conduction process in the SnO2/Si heterojunction. When the temperature was lower than 340 K, the carrier conduction at low bias mainly was direct tunneling. Whereas, the carrier transport at high bias turned into Fowler-Nordheim (F-N) tunneling. At temperature above 340 K, the carrier injection mechanism showed coexistence of thermionic emission and direct tunneling when the applied voltage was low, while in the high applied voltage region the thermionic emission and F-N tunneling existed simultaneously. The saturated reverse current obtained from the current-voltage characteristic at different temperature indicated that there was no barrier saddle point in the SnO2/Si heterojunction. The rectification ratio at ±4.5 V varied from 176 to 327, which was better than traditional ZnO-based heterojunction. The calculated conduction band offset and valence band offset between SnO2 and Si were 0.68 eV and 2.12 eV, respectively. The smaller conduction band offset compared with the valence band offset led to the control of the electron transport easier than that of the hole transport. We believe the results in this study should be helpful in understanding the interfacial carrier injection mechanism of silicon-based oxide structure at various temperatures and bias voltages.
关键词： Fowler-Nordheim tunneling,direct tunneling,SnO2/Si heterojunction,thermionic emission
更新于2025-09-04 15:30:14
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Investigation of gas discharge features during HiPIMS using optical emission spectroscopy
摘要： The paper presents the results of the investigation of the emission spectra of a gas discharge during high-power impulse magnetron sputtering (HiPIMS) of a titanium target at different power supply parameters. In such mode, the fraction of ionized atoms of the target material in the discharge increases significantly, what affects the properties of the deposited coatings. The characteristic features of the operation of the system in HiPIMS mode were singled out, and also the discharge spectra were compared at high-power impulse and conventional (sputtering on a direct current) operation modes of the magnetron. As a result of the study, it was shown that the use of optical emission spectroscopy during HiPIMS makes it possible to effectively determine the parameters of the stable operation of the system and determine the boundary at which a transition into high-power regime occurs.
关键词： titanium target,HiPIMS,gas discharge,magnetron sputtering,optical emission spectroscopy
更新于2025-09-04 15:30:14