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Structure and luminescence properties of Zn3V2O8 yellow phosphor for white light emitting diodes
摘要： Extensive attention has been focused on the development of rare-earth-free phosphors, due to their low cost, good absorption and emission properties. However, the yellow light emitted phosphors with good quantum yield and thermal stability are still urgent. Herein, we successfully prepare the single-phase Zn3V2O8 yellow phosphor through a solid state reaction method. The as-prepared phosphors present a broad absorption band in UV/NUV region, and exhibit an intense broadband emission spectrum under the NUV light excitation at 365 nm. The Zn3V2O8 phosphors also show excellent luminescence performance including strong emission intensity, long PL lifetime, high quantum yield, and good thermal stability. Moreover, this sample obtains a CIE coordinate of (0.364, 0.486) in the yellow light region. Therefore, the Zn3V2O8 phosphors can be considered as a novel yellow light source for w-LED devices.
关键词： Phosphors,Zn3V2O8,Crystal structure,Luminescence mechanism
更新于2025-09-10 09:29:36
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Silver polymer complexes as precursors of nanocomposites based on polymers of 1-vinyl-1,2,4-triazole
摘要： Bioactive silver-containing (Ag content of about 6.8-8.2 wt %) polymer complexes based on the synthetic homopolymer of 1-vinyl-1,2,4-triazole and its copolymers have been synthesized and characterized. Structural features of macromolecular complexes were studied by magnetic resonance techniques (EPR, NMR) and other analytical methods (FTIR, SEM, UV-vis, atomic absorption analysis, etc.). The spatial structure of the polymer chain fragment and silver ion/1-vinyl-1,2,4-triazole complexes were investigated by quantum-chemical calculations. The formation of coordinatively saturated polymer complexes of Ag(I) and highly oxidized forms of Ag(II) silver was analyzed. The sites of ions localization and reduced metallic silver in the structure of the polymer matrix were determined.
关键词： Complex,EPR,Polymer,Silver,1-Vinyl-1,2,4-triazole,NMR
更新于2025-09-09 09:28:46
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Silica Nanoparticles with Up-conversion Fluorescence Based on Triplet-Triplet Annihilation Mechanism for Specific Recognition of Apoptosis Cells
摘要： Discriminating of live and apoptotic cells is a crucial task in the research of pharmacology, biology, pathology, and medicine science. Recently, up conversion (UC) luminescent materials have appealed much attention due to their unique ability to convert low energy excitation photons to high energy ones. However, UC fluorescence has not been employed in the field of discriminating of live and apoptotic cells. We presented a facile, and cost-less St?ber method to fabricate robust silica nanoparticles (SiO2 UCNPs) exhibiting several merits, such as narrow size distribution, and UC luminescence. SiO2 UCNPs could discriminate live and apoptosis cells by taking advantage of the unique surface property of SiO2 UCNPs for the first time. This work is also the first demonstration of the use of single photon excited UC fluorescence derived from nanoparticles for biological recognition of a specific type of cells.
关键词： Apoptosis Cells,Triplet-Triplet Annihilation Mechanism,Silica Nanoparticles,Up-conversion Fluorescence
更新于2025-09-09 09:28:46
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A CD probe with a tailored cantilever for 3D-AFM measurement
摘要： A critical dimensional (CD) probe, such as a boot shaped probe, is widely used for measuring the sidewall profiles of nanostructures in atomic force microscopy (AFM). However, conventional CD probes usually have high spring constants that restrict their ability to operate in critical dimension scanning modes. Furthermore, the flexure spring constant of the tip is much smaller than the torsion spring constant of the cantilever, which probably makes the sidewall measurement unstable. Here, we proposed a method of tailoring the probe where the cantilever was trimmed to reduce the spring constant. The simulation results, using a finite element method (FEM), illustrated that both the flexure and torsion spring constants decreased nearly ten times. Meanwhile, the torsional resonant frequency decreased to below 1 MHz, which could benefit the torsional oscillation scanning. By using a focused ion beam (FIB), a CD probe with a rectangular cantilever was reprocessed. It was mounted to a home-built three-dimensional AFM system (3D-AFM), and had the flexure and torsion sensitivities precisely calibrated. The ratio of the flexure sensitivity to torsion sensitivity showed good accordance with the simulation results. Additionally, a grating standard sample was measured using the tailored probe under a modified step-in scanning mode, and the error due to torsional deformation of the tip was compensated. The measurement results demonstrated the validity of the tailored CD probe in 3D metrology.
关键词： deformation,3D-AFM,sidewall,tailored cantilever,CD probe
更新于2025-09-09 09:28:46
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Multi-modality imaging of a murine mammary window chamber for breast cancer research
摘要： Window chamber models have been developed and utilized as a means to study the complex microenvironment in which cancers develop, proliferate, and metastasize in small animals. Here we utilize rapid prototyping printer technology to construct a new plastic orthotopic mammary window chamber that is compatible with magnetic resonance imaging, nuclear imaging, and optical imaging. Optical imaging allows for high-resolution cellular and molecular level analysis of tissues; magnetic resonance imaging provides quantitative measures of tumor size, perfusion, diffusion, fat/water content relaxation parameters; and a nuclear imaging technique, called the Beta Imager, supports functional and metabolic imaging. Our demonstration of the multiple imaging capabilities of this model suggests that it can be used as a powerful platform for studying basic cancer biology and developing new cancer therapies.
关键词： cancer,optical,window chamber,imaging,nuclear,magnetic resonance
更新于2025-09-09 09:28:46
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Eu3+-doped Sr2(Al1?xMgx)(Al1?xSi1+x)O7 phosphors: electronic, crystal structures and photoluminescence properties
摘要： The union of chemical compositions substitution and spectral controlling is of importance for the discovery of new materials or the implementation of properties optimization. In this work, we employed an effective strategy to regulate crystal structures by chemical unit co-substitution. We applied this strategy to Eu3+-doped Sr2(Al1?xMgx)(Al1?xSi1+x)O7 (0 ≤ x ≤ 1) solid solution phosphor, which was successfully synthesized by high temperature solid state reaction. The crystal structure remained the same group, P-421m, with controlling chemical compositions. The excitation peaks shifted between 263 and 270 nm and emission peaks shifted between 612 and 614 nm with a decreasing Stocks shift in overall tendency. The shift trend was clarified by Crystal Field Theory. The energy band structure and density of states of Sr2Al2SiO7 and Sr2MgSi2O7 were calculated by Density Functional Theory using the generalized gradient approximation. The band gap was also analyzed by diffuse reflectance spectrum as a contrast. The morphology was characterized by field emission scanning electron microscopy. Furthermore, the photoluminescence color of phosphors could be tuned from yellow to orange.
关键词： crystal structure,chemical unit co-substitution,phosphors,photoluminescence,energy band structure
更新于2025-09-09 09:28:46
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Green Synthesis of Glowing Carbon Dots from Carica papaya Waste Pulp and Their Application as a Label-freeChemo probe for Chromium Detection in Water
摘要： The work presents the facile green synthesis of blue luminescent C-dots (CDs) using papaya waste (Carica papaya) as a precursor. The as-synthesized CDS exhibit a quantum yield of 23.7 % and are of size < 10 nm, while their polymerized architecture is confirmed by NMR spectroscopic analysis. The presence of various carbonyl and carboxyl surface groups confirmedthrough FT-IR is utilized for their surface modification with Ethylenediaminetetraacetic acid (EDTA) to detect chromium in water with high sensitivity and selectivity. The sensor demonstrated a fashioned decrease in fluorescence intensity on chromium (Cr (III), Cr (VI), Cr (III) + Cr (VI)) addition in a wide detection window of 10-1000 ppb. The theoretical detection (LOD, 3s/sensitivity) and quantification (LOQ, 10s/sensitivity) limits for total chromium were found to be 0.708 ppb and 2.4 ppb, respectively. The study presents fruit waste-derived and modified green CDS based chromium sensing platform for their potential integration with optical analyzers in water pollutants monitoring.
关键词： Water Analysis,Papaya waste,Cr detection,CDs
更新于2025-09-09 09:28:46
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A Study of Controllable Synthesis and Formation Mechanism on Flower-Like TiO2 with Spherical Structure
摘要： The development of photocatalytic materials with specific morphologies promises to be a good opportunity to discover geometrically relevant properties. Herein, this paper reported a facile hydrothermal method to directly synthesize TiO2 crystals with flower-like structures using tetrabutyl titanate (TBT) as a titanium source and ethylene glycol as an additive. We also proposed a reasonable growth mechanism by controlling reaction time in detail. The as-prepared samples were analyzed by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy for structure and morphology characterization. The N2 adsorption-desorption isotherm results showed that the surface area of flower-like TiO2 with 10 h reaction time can reach 297 m2/g. We evaluated the photocatalytic performance of samples by using the degradation rate of methylene blue (MB) solution under UV-vis light. The TiO2 with 10 h reaction time exhibited a superior photocatalytic property than other samples in degrading MB under UV-vis light irradiation. More importantly, the catalyst could be reused many times. These results could benefit from the special morphology, high crystallinity and large specific surface area of the samples.
关键词： flower-like,photocatalytic activity,TiO2
更新于2025-09-04 15:30:14
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Tailoring chemical and physical properties of graphene-added DNA hybrid thin films
摘要： While the characteristics of DNA and graphene are well studied, the chemical and physical properties of graphene-embedded DNA and cetyltrimethyl-ammonium chloride-modified DNA (CT-DNA) hybrid thin films (HTFs) have been rarely discussed due to the limited development of fabrication methodologies. Herein, we developed a simple drop-casting method for constructing DNA and CT-DNA HTFs added with graphene nanopowder (GNP). Additionally, we demonstrated their distinct characteristics, such as their structure, elemental composition, spin states and chemical functional groups, binding interactions, vibration/stretching modes, UV-Vis absorption, PL, and electrical properties. The EDS spectra of GNP-added DNA HTFs showed C, N, O, Na, and P peaks at characteristic energies. Because of the physical adsorption of GNP on DNA, the peak shifts and suppression of the core spectra of O 1s and P 2p were observed by XPS. The intensity variation of Raman and FTIR bands indicated hybrid formation of GNP in DNA and CT-DNA through adsorption, electrostatic interaction, and π–π stacking. UV-Vis absorption and PL spectra showed the considerable influence of GNP in DNA and CT-DNA HTFs. DNA and CT-DNA HTFs with relatively higher [GNP] showed significant increases of current due to the formation of interconnected networks of GNP in the DNA and CT-DNA HTFs.
关键词： spectroscopy,DNA,electrical property,hybrid thin film,graphene
更新于2025-09-04 15:30:14
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Group 10 metal–thiocatecholate capped magnesium phthalocyanines – coupling chromophore and electron donor/acceptor entities and its impact on sulfur induced red-shifts
摘要： A new and facile method of generating thiolate groups at the phthalocyanine (Pc) β-position is presented as well the unique properties that these groups confer on the Pc ligand upon coordination of group 10 metals Ni, Pd and Pt(dppe) or SnMe3. In particular, the Q-band is shifted to almost 800 nm for all group 10 metals used, and the complexes show panchromatic absorption owing to new absorbance bands that appear between 400 and 650 nm. Enhanced intersystem-crossing for all transition metal co-ordinated Mg(Pc) complexes was demonstrated by the moderate to very high singlet oxygen quantum yields of 0.36, 0.76 and 0.91 for the Ni, Pd and Pt coordinating complexes, respectively, which show that the heavy metals have direct influence on the Pc π-system and inter-system-crossing (ISC). This was further confirmed by MO calculations, which show mixing of metal and ligand orbitals, as well as suggest that the Q-band transition has both π → π* and ligand-to-metal charge transfer characteristics. Furthermore, the origin of the Q-band red-shift was shown to be due to greater destabilization of the HOMO compared to LUMO/LUMO+1, thus decreasing the HOMO–LUMO band gap.
关键词： thiolate groups,intersystem-crossing,phthalocyanine,MO calculations,HOMO–LUMO band gap,panchromatic absorption,singlet oxygen quantum yields,group 10 metals,Q-band
更新于2025-09-04 15:30:14