Highly Reversible Zn-Air Batteries Enabled by Tuned Valence Electron and Steric Hindrance on Atomic Fe-N4-C Sites.

The bifunctional oxygen electrocatalyst is the Achilles' heel of achieving robust reversible Zn-air batteries (ZABs). Herein, durable bifunctional oxygen electrocatalysis in alkaline media is realized on atomic Fe-N4-C sites reinforced by NixCo3-xO4 (NixCo3-xO4@Fe1/NC). Compared with that of pristine Fe1/NC, the stability of the oxygen evolution reaction (OER) is increased 10 times and the oxygen reduction reaction (ORR) performance is also improved. The steric hindrance alters the valence electron at the Fe-N4-C sites, resulting in a shorter Fe-N bond and enhanced stability of the Fe-N4-C sites. The corresponding solid-state ZABs exhibit an ultralong lifespan (>460 h at 5 mA cm-2) and high rate performance (from 2 to 50 mA cm-2). Furthermore, the structural evolution of NixCo3-xO4@Fe1/NC before and after the OER and ORR as well as charge-discharge cycling is explored. This work develops an efficient strategy for improving bifunctional oxygen electrocatalysis and possibly other processes.

Dual-Confinement Effect of Nanocages@Nanotubes Suppresses Polysulfide Shuttle Effect for High-Performance Lithium-Sulfur Batteries.

The shuttle effect of lithium polysulfides (LiPSs) severely hinders the development and commercialization of lithium-sulfur batteries, and the design of high-conductive carbon fiber-host material has become a key solution to suppress the shuttle effect. In this work, a unique Co/CoN-carbon nanocages@TiO2-carbon nanotubes structure (NC@TiO2-CNTs) is constructed using an electrospinning and nitriding process. Lithium-sulfur batteries using NC@TiO2-CNTs as cathode host materials exhibit high sulfur utilization (1527 mAh g-1 at 0.2 C) and can still maintain a discharge capacity of 663 mAh g-1 at a high current density of 5 C, and the capacity loss is only 0.056% per cycle during 500 cycles at 1 C. It is worth noting that even under extreme conditions (sulfur-loading = 90%, surface-loading = 5.0 mg cm-2 (S), and E/S = 6.63 µL mg-1), the lithium-sulfur batteries can still provide a reversible capacity of 4 mAh cm-2. Throughdensity functional theory calculations, it has been found that the Co/CoN heterostructures can adsorb and catalyze LiPSs conversion effectively. Simultaneously, the TiO2 can adsorb LiPSs and transfer Li+ selectively, achieving dual confinement for the shuttle effect of LiPSs (nanocages and nanotubes). The new findings provide a new performance enhancement strategy for the commercialization of lithium-sulfur batteries.

Computational anti-COVID-19 drug design: progress and challenges.

Vaccines have made gratifying progress in preventing the 2019 coronavirus disease (COVID-19) pandemic. However, the emergence of variants, especially the latest delta variant, has brought considerable challenges to human health. Hence, the development of robust therapeutic approaches, such as anti-COVID-19 drug design, could aid in managing the pandemic more efficiently. Some drug design strategies have been successfully applied during the COVID-19 pandemic to create and validate related lead drugs. The computational drug design methods used for COVID-19 can be roughly divided into (i) structure-based approaches and (ii) artificial intelligence (AI)-based approaches. Structure-based approaches investigate different molecular fragments and functional groups through lead drugs and apply relevant tools to produce antiviral drugs. AI-based approaches usually use end-to-end learning to explore a larger biochemical space to design antiviral drugs. This review provides an overview of the two design strategies of anti-COVID-19 drugs, the advantages and disadvantages of these strategies and discussions of future developments.

DeepDDS: deep graph neural network with attention mechanism to predict synergistic drug combinations.

MOTIVATION: Drug combination therapy has become an increasingly promising method in the treatment of cancer. However, the number of possible drug combinations is so huge that it is hard to screen synergistic drug combinations through wet-lab experiments. Therefore, computational screening has become an important way to prioritize drug combinations. Graph neural network has recently shown remarkable performance in the prediction of compound-protein interactions, but it has not been applied to the screening of drug combinations. RESULTS: In this paper, we proposed a deep learning model based on graph neural network and attention mechanism to identify drug combinations that can effectively inhibit the viability of specific cancer cells. The feature embeddings of drug molecule structure and gene expression profiles were taken as input to multilayer feedforward neural network to identify the synergistic drug combinations. We compared DeepDDS (Deep Learning for Drug-Drug Synergy prediction) with classical machine learning methods and other deep learning-based methods on benchmark data set, and the leave-one-out experimental results showed that DeepDDS achieved better performance than competitive methods. Also, on an independent test set released by well-known pharmaceutical enterprise AstraZeneca, DeepDDS was superior to competitive methods by more than 16% predictive precision. Furthermore, we explored the interpretability of the graph attention network and found the correlation matrix of atomic features revealed important chemical substructures of drugs. We believed that DeepDDS is an effective tool that prioritized synergistic drug combinations for further wet-lab experiment validation. AVAILABILITY AND IMPLEMENTATION: Source code and data are available at https://github.com/Sinwang404/DeepDDS/tree/master.

Molecular property prediction by contrastive learning with attention-guided positive sample selection.

MOTIVATION: Predicting molecular properties is one of the fundamental problems in drug design and discovery. In recent years, self-supervised learning (SSL) has shown its promising performance in image recognition, natural language processing, and single-cell data analysis. Contrastive learning (CL) is a typical SSL method used to learn the features of data so that the trained model can more effectively distinguish the data. One important issue of CL is how to select positive samples for each training example, which will significantly impact the performance of CL. RESULTS: In this article, we propose a new method for molecular property prediction (MPP) by Contrastive Learning with Attention-guided Positive-sample Selection (CLAPS). First, we generate positive samples for each training example based on an attention-guided selection scheme. Second, we employ a Transformer encoder to extract latent feature vectors and compute the contrastive loss aiming to distinguish positive and negative sample pairs. Finally, we use the trained encoder for predicting molecular properties. Experiments on various benchmark datasets show that our approach outperforms the state-of-the-art (SOTA) methods in most cases. AVAILABILITY AND IMPLEMENTATION: The code is publicly available at https://github.com/wangjx22/CLAPS.

miR-27a-5p inhibits acute rejection of liver transplantation in rats by inducing M2 polarization of Kupffer cells through the PI3K/Akt pathway.

Liver transplantation (LT), a major therapy for end-stage liver disease, is often associated with acute rejection (AR). MicroRNAs (miRNAs) have been implicated in AR-related gene regulation. In this experiment, the mechanism of miR-27a-5p in AR of LT was studied. Allotransplantation model (LEW-BN) and syngeneic transplantation model (LEW-LEW) of rat orthotopic liver transplantation (OLT) were established. miR-27a-5p was overexpressed in recipient rats 28 days before LT to detect its effects on LT pathology, liver function, and survival time. Kupffer cells (KCs) were isolated and treated with lipopolysaccharide (LPS) and miR-27a-5p overexpression. miR-27a-5p overexpression reduced lymphocyte numbers around portal areas and central veins after LT and mitigated degeneration of epithelial cells of the bile duct. Expression levels of IL-10 and TGF-ß1 were increased while IL-12 was decreased. Liver function damage was alleviated and the survival time of rats with LT was prolonged. miR-27a-5p induced M2 polarization of rats with AR after LT and LPS-treated KCs in vitro and promoted activation of the PI3K/Akt pathway in KCs. Inhibition of the PI3K/Akt pathway averted induction of miR-27a-5p on M2 polarization of KCs. Taken together, miR-27a-5p inhibited AR after LT in rats by inducing M2 polarization of KCs through the PI3K/Akt pathway.

DrugCombDB: a comprehensive database of drug combinations toward the discovery of combinatorial therapy.

Drug combinations have demonstrated high efficacy and low adverse side effects compared to single drug administration in cancer therapies and thus have drawn intensive attention from researchers and pharmaceutical enterprises. Due to the rapid development of high-throughput screening (HTS), the number of drug combination datasets available has increased tremendously in recent years. Therefore, there is an urgent need for a comprehensive database that is crucial to both experimental and computational screening of synergistic drug combinations. In this paper, we present DrugCombDB, a comprehensive database devoted to the curation of drug combinations from various data sources: (i) HTS assays of drug combinations; (ii) manual curations from the literature; and (iii) FDA Orange Book and external databases. Specifically, DrugCombDB includes 448 555 drug combinations derived from HTS assays, covering 2887 unique drugs and 124 human cancer cell lines. In particular, DrugCombDB has more than 6000 000 quantitative dose responses from which we computed multiple synergy scores to determine the overall synergistic or antagonistic effects of drug combinations. In addition to the combinations extracted from existing databases, we manually curated 457 drug combinations from thousands of PubMed publications. To benefit the further experimental validation and development of computational models, multiple datasets that are ready to train prediction models for classification and regression analysis were constructed and other significant related data were gathered. A website with a user-friendly graphical visualization has been developed for users to access the wealth of data and download prebuilt datasets. Our database is available at http://drugcombdb.denglab.org/.

Luminescence properties and energy transfer of Tb3+, Eu3+ co-doped YTaO4 phosphors obtained via sol-gel combustion process.

Tantalate is considered as a valuable and efficient luminescence host because of its intense absorption in the ultraviolet area and excellent chemical properties. In this work, a series of pure YTaO4:Eu3+ and/or Tb3+ crystals were prepared via a sol-gel combustion method. The morphology, structure, and optical properties of the samples were discussed in detail. The Eu3+, Tb3+ co-doped YTaO4 samples are consisted of small spherical particles of around 18 nm. The prepared YTaO4:Tb3+ and/or Eu3+ samples exhibit the characteristic wide excitation band around 210-300 nm, the characteristic narrow red emission of Eu3+ (5D0 → 7F2) transitions and green emission of the Tb3+ (5D4 → 7F5) transitions when excited by UV light. It is focused on the energy transfer processes from the YTaO4 to Tb3+ as well as Eu3+ ions and from Tb3+ to Eu3+ ions of YTaO4:Eu3+/Tb3+ phosphors. Color-tunable emissions are realized through adjusting the types of rare earth ion (Eu3+ and Tb3+) and relative doping concentrations excited by a single wavelength. That is to say, the obtained Tb3+ and Eu3+ co-doped YTaO4 phosphors have a promising prospect in lasers, white light diodes (WLED), fluorescent lamp, and field emission display devices, etc.

Utilizing modules of different functions to construct a Janus-type membrane and derivative 3D Janus-type tube displaying synchronous trifunction of conductive aeolotropism, magnetism and luminescence.

The microstructures and macrostructures play a crucial role in the properties and applications of multifunctional materials. Herein, microscopic partition and macroscopic partition are combined by devising and preparing different modules that can be elaborately devised to possess specific performances. A two-dimensional (2D) 3-module Janus-type membrane multifunctionalized by conductive aeolotropism, magnetism and luminescence (defined as 3M-CML Janus-type membrane) is constructed via electro-spinning. The modular structure of 3M-CML Janus-type membrane is obtained by devising and constructing three different modules, including luminescence module (denoted as L module), conductive aeolotropism-luminescence module (marked as C-L module) and magnetism-luminescence module (named as M-L module). The results prove that almost no mutual detrimental influences exist among different modules owing to the macroscopic modular structure and Janus-type structure, which effectively avoids the negative interactions among different materials. Tb(BA)3phen/PVP nanofiber, [PMMA/Eu(BA)3phen]//[PMMA/PANI] Janus-type nanoribbon and [PMMA/Tb(BA)3phen]//[PMMA/Fe3O4] Janus-type nanoribbon are, respectively, selected as building units of the three modules, which further prevents the negative interactions among different materials and improves the versatility of 3M-CML Janus-type membrane. The luminescence, adjustable conductive aeolotropism and variable magnetism of 3M-CML Janus-type membrane are systematically discussed. Meanwhile, novel flexible four types of brand-new three-dimensional (3D) Janus-type tubes are obtained by rolling modularly devised 2D 3M-CML Janus-type membrane with different rolling schemes. As derivatives of the 2D 3M-CML Janus-type membranes, macroscopic 3D Janus-types tubes exhibit similar performances to 2D 3M-CML Janus-type membranes. The 2D Janus-type membrane and 3D Janus-type tube will have momentous applications in flexible electronics and nanodevices in the future.

Controlled Morphology, Improved Photoluminescent Properties, and Application of an Efficient Non-rare Earth Deep Red-Emitting Phosphor.

Transition-metal tetravalent manganese ions (Mn4+) as luminescence center of red phosphors have drawn much attention owing to their broad-band absorption extended from UV to blue regions and narrow red-emissive band. In the present work, a series of Mn4+-doped BaGeF6 red phosphors were obtained via hydrothermal method. X-ray powder diffraction, energy-dispersive X-ray spectrometer, scanning electron microscope, and photoluminescence spectra were employed to determine the crystal structure, composition, morphology, and photoluminescence properties of all samples. The prepared BaGeF6:Mn4+ samples demonstrate two dominant broadband absorption at near-UV (∼366 nm) and blue regions (∼470 nm) and intense red emissions (∼635 nm) under 470 nm excitation. In addition, the morphology and the emission intensities were successfully controlled by adjusting doping concentrations, reaction times, reaction temperatures, barium sources, and surfactants. Concentration quenching and thermal quenching mechanisms were studied in detail. When the BaGeF6:Mn4+ red phosphor was introduced into the light-emitting diode, warm white light-emitting diodes (w-LEDs) were successfully fabricated, which have high color rendering index (Ra = 86.3) and low correlated color temperature (4766 K), indicating that the BaGeF6:Mn4+ red phosphor provides a good opportunity for application in w-LEDs.

Dual-mode, tunable color, enhanced upconversion luminescence and magnetism of multifunctional BaGdF5:Ln(3+) (Ln = Yb/Er/Eu) nanophosphors.

A series of Yb(3+), Er(3+), and Eu(3+) ions doped BaGdF5 dual-mode (down-conversion (DC) and upconversion (UC)) luminescent nanophosphors were successfully prepared by a simple one-step hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, fluorescence lifetime measurements, and vibrating sample magnetometry (VSM) were utilized to characterize the samples. Under 274 nm UV light excitation, BaGd0.78-zF5:0.2Yb(3+),0.02Er(3+),zEu(3+) phosphors emitted orange emission. Under 980 nm NIR irradiation, intense up-converted visible green emissions were observed in BaGdF5:Yb(3+),Er(3+)/Eu(3+) samples. The mechanism of UC emissions involved two-photon absorption. In the Yb(3+),Er(3+),Eu(3+) co-doped BaGdF5 phosphors, the energy transfer processes from Gd(3+) to Eu(3+) and from Yb(3+) to Er(3+) were discussed. Tunable colors were visualised with the help of the Commission Internationale de L'Eclairage (CIE) chromaticity diagram and the processes responsible for the DC and UC emissions were discussed in detail. The enhanced up-conversion luminescence of Yb(3+),Er(3+)/Eu(3+) co-doped BaGdF5 nanophosphors (NPs) was realized by modifying the trisodium citrate (Cit(3-)) surfactant. Moreover, the as-prepared samples exhibited paramagnetic properties at room temperature. This type of multifunctional orange-green emitting nanophosphor has promising applications in solid state lasers, lighting, MRI, anti-counterfeiting, biolabels, and so on.

Assembly of 1D nanofibers into a 2D bi-layered composite nanofibrous film with different functionalities at the two layers via layer-by-layer electrospinning.

A two-dimensional (2D) bi-layered composite nanofibrous film assembled by one-dimensional (1D) nanofibers with trifunctionality of electrical conduction, magnetism and photoluminescence has been successfully fabricated by layer-by-layer electrospinning. The composite film consists of a polyaniline (PANI)/Fe3O4 nanoparticle (NP)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional layer on one side and a Tb(TTA)3(TPPO)2/polyvinylpyrrolidone (PVP) photoluminescent layer on the other side, and the two layers are tightly combined face-to-face together into the novel bi-layered composite film of trifunctionality. The brand-new film has totally different characteristics at the double layers. The electrical conductivity and magnetism of the electrical-magnetic bifunctional layer can be, respectively, tunable via modulating the PANI and Fe3O4 NP contents, and the highest electrical conductivity can reach up to the order of 10-2 S cm-1, and predominant intense green emission at 545 nm is obviously observed in the photoluminescent layer under the excitation of 357 nm single-wavelength ultraviolet light. More importantly, the luminescence intensity of the photoluminescent layer remains almost unaffected by the electrical-magnetic bifunctional layer because the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe3O4 NPs. By comparing with the counterpart single-layered composite nanofibrous film, it is found that the bi-layered composite nanofibrous film has better performance. The novel bi-layered composite nanofibrous film with trifunctionality has potential in the fields of nanodevices, molecular electronics and biomedicine. Furthermore, the design conception and fabrication technique for the bi-layered multifunctional film provide a new and facile strategy towards other films of multifunctionality.

NaGdF4:Dy3+ nanofibers and nanobelts: facile construction technique, structure and bifunctionality of luminescence and enhanced paramagnetic performances.

Luminescent-magnetic bifunctional NaGdF4:Dy3+ nanofibers and nanobelts have been successfully fabricated by a combination of electrospinning followed by subsequent calcination with fluorination technology for the first time. The structure, morphologies, and luminescence and magnetic properties of the synthesized materials have been investigated by a variety of techniques. X-ray diffraction (XRD) analysis shows that as-prepared NaGdF4:Dy3+ nanostructures are pure hexagonal structures. Scanning electron microscopy (SEM) observations indicate that directly electrospinning-made PVP/[NaNO3 + Gd(NO3)3 + Dy(NO3)3] composite nanofibers and nanobelts have smooth surfaces, good dispersion and uniform size, and surfaces of NaGdF4:Dy3+ nanofibers and nanobelts become rough after calcination and fluorination processes. The mean diameters of PVP/[NaNO3 + Gd(NO3)3 + Dy(NO3)3] composite nanofibers and NaGdF4:0.5%Dy3+ nanofibers are, respectively, 402.20 ± 2.39 nm and 246.06 ± 5.84 nm at the confidence level of 95%. The mean widths and thicknesses of PVP/[NaNO3 + Gd(NO3)3 + Dy(NO3)3] composite nanobelts and NaGdF4:0.5%Dy3+ nanobelts are 4.16 ± 0.17 µm and 279 nm, and 0.83 ± 0.01 µm and 130 nm, respectively. Under the excitation of 274 nm ultraviolet light, NaGdF4:Dy3+ nanofibers and nanobelts show the predominant blue and yellow emission peaks at 478 and 570 nm corresponding to the 4F9/2 → 6HJ/2 (J = 15, 13) energy level transitions of Dy3+ ions, respectively. NaGdF4:0.5%Dy3+ nanofibers have higher photoluminescence intensity than their nanobelt counterpart. In addition, all the NaGdF4:Dy3+ nanofibers and nanobelts display superparamagnetic properties. The NaGdF4:0.5%Dy3+ nanobelts show the highest magnetization, and NaGdF4:0.5%Dy3+ nanofibers have slightly higher magnetization values than NaGdF4 nanofibers. NaGdF4:Dy3+ nanofibers and nanobelts simultaneously possess excellent luminescence and enhanced superparamagnetic properties, which make them ideally suitable for application in many fields such as solid-state lasers, lighting and displays, and magnetic resonance imaging. The design conception and construction strategy developed in this work may provide some new guidance for the synthesis of other rare earth fluoride nanostructures with various morphologies.

Tunable photoluminescence and magnetic properties of Dy(3+) and Eu(3+) doped GdVO4 multifunctional phosphors.

A series of Dy(3+) or/and Eu(3+) doped GdVO4 phosphors were successfully prepared by a simple hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrometry (EDS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The results indicate that the as-prepared samples are pure tetragonal phase GdVO4, taking on nanoparticles with an average size of 45 nm. Under ultraviolet (UV) light excitation, the individual Dy(3+) or Eu(3+) ion activated GdVO4 phosphors exhibit excellent emission properties in their respective regions. The mechanism of energy transfer from the VO4(3-) group and the charge transfer band (CTB) to Dy(3+) and Eu(3+) ions is proposed. Color-tunable emissions in GdVO4:Dy(3+),Eu(3+) phosphors are realized through adopting different excitation wavelengths or adjusting the appropriate concentration of Dy(3+) and Eu(3+) when excited by a single excitation wavelength. In addition, the as-prepared samples show paramagnetic properties at room temperature. This kind of multifunctional color-tunable phosphor has great potential applications in the fields of photoelectronic devices and biomedical sciences.

Multifunctional MWCNTs-NaGdF4:Yb(3+),Er(3+),Eu(3+) hybrid nanocomposites with potential dual-mode luminescence, magnetism and photothermal properties.

A novel dual-mode luminescence multifunctional hybrid nanomaterial has been successfully prepared by coating the NaGdF4:Yb(3+),Er(3+),Eu(3+) nanoparticles (NPs) on the surface of MWCNTs. The as-synthesized MWCNTs-NaGdF4:Yb(3+),Er(3+),Eu(3+) nanocomposites (NCs) can simultaneously take advantage of both magnetic and optical properties of NaGdF4:Yb(3+),Er(3+),Eu(3+) NPs and the photothermal conversion property of MWCNTs. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), vibrating sample magnetometry (VSM), UV-Vis absorption, luminescence spectroscopy and fluorescence lifetime measurements. Meanwhile, the photothermal conversion was examined under irradiation with a 980 nm laser. The results show that the MWCNTs-NaGdF4:Yb(3+),Er(3+),Eu(3+) NCs have preferably magnetic, dual-mode (up- and down-conversion) luminescence and photothermal properties. And the NCs have good biocompatibility, low toxicity and up-conversion luminescence for cell imaging. As a consequence, the dual-mode luminescence multifunctional nanomaterials have potential applications in environmental science fields and clinical fields for magnetic resonance imaging, fluorescence imaging, photothermal therapy, bioseparation and targeted drug delivery.

A novel strategy to directly fabricate flexible hollow nanofibers with tunable luminescence-electricity-magnetism trifunctionality using one-pot electrospinning.

Novel photoluminescent-electrical-magnetic trifunctional flexible Eu(BA)3phen/PANI/Fe3O4/PVP (BA = benzoic acid, phen = phenanthroline, PANI = polyaniline, PVP = polyvinylpyrrolidone) hollow nanofibers were fabricated by a one-pot electrospinning technique using a specially designed coaxial spinneret for the first time. Very different from the traditional preparation process of hollow fibers via coaxial electrospinning, which needs to firstly fabricate the coaxial fibers and followed by removing the core through high-temperature calcination or solvent extraction, in our current study, no core spinning solution is used to directly fabricate hollow nanofibers. The morphology and properties of the obtained hollow nanofibers were characterized in detail using X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy, a 4-point probe resistivity measurement system and vibrating sample magnetometry. The Eu(BA)3phen/PANI/Fe3O4/PVP hollow nanofibers, with outer diameters of ca. 305 nm and inner diameters of about 140 nm, exhibit excellent photoluminescence performance, electrical conductivity and magnetic properties. Fluorescence emission peaks of Eu(3+) are observed in the Eu(BA)3phen/PANI/Fe3O4/PVP hollow nanofibers and assigned to the (5)D0→(7)F0 (580 nm), (5)D0→(7)F1 (592 nm) and (5)D0→(7)F2 (616 nm) energy level transitions of Eu(3+) ions, and the (5)D0→(7)F2 hypersensitive transition at 616 nm is the predominant emission peak. The electrical conductivity of the hollow nanofibers reaches up to the order of 10(-3) S cm(-1). The luminescent intensity, electrical conductivity and magnetic properties of the hollow nanofibers can be tuned by adding various amounts of Eu(BA)3phen, PANI and Fe3O4 nanoparticles. The new-type photoluminescent-electrical-magnetic trifunctional flexible hollow nanofibers hold potential for a variety of applications, including electromagnetic interference shielding, microwave absorption, molecular electronics and biomedicine. The design conception and synthetic strategy developed in this study are of universal significance to construct other multifunctional hollow one-dimensional nanomaterials.

Novel flexible belt-shaped coaxial microcables with tunable multicolor luminescence, electrical conductivity and magnetism.

A novel type of flexible [Fe3O4/PANI/PMMA]@{[Eu(BA)3phen + Tb(BA)3phen]/PMMA} (PMMA = polymethyl methacrylate, BA = benzoic acid, phen = phenanthroline, PANI = polyaniline) belt-shaped coaxial microcable possessing electrical conductivity, magnetism and color-tunable photoluminescence has been successfully fabricated by electrospinning technology using a specially designed coaxial spinneret. Every strip of belt-shaped coaxial microcable is assembled with a Fe3O4/PANI/PMMA electrically conductive -magnetic bifunctional core and a [Eu(BA)3phen + Tb(BA)3phen]/PMMA insulative and photoluminescence-tunable shell. The conductivity of the core of belt-shaped coaxial microcables reaches up to the order of 10(-2) S cm(-1) and all belt-shaped coaxial microcables are insulated from each other. The tuning of emission color is possible by changing the Eu(3+)/Tb(3+) molar ratio of the belt-shaped coaxial microcables. The electrical conductivity, magnetic and photoluminescence properties of belt-shaped coaxial microcables can be tuned by adjusting the content of PANI, Fe3O4 nanoparticles (NPs) and rare earth complexes. More importantly, the proposed design idea and the construction technique are universal regarding the preparation of other multifunctional one-dimensional micromaterials.

Electrospinning preparation and photoluminescence properties of Y3Al5O12:Tb3+ nanostructures.

Novel nanostructures of Y3Al5O12:Tb(3+) (denoted as YAG:Tb(3+) for short) nanobelts and nanofibers were fabricated by calcination of the respective electrospun PVP/[Y(NO3)3 + Tb(NO3)3 + Al(NO3)3] composite nanobelts and nanofibers. YAG:Tb(3+) nanostructures are cubic in structure with a space group of Ia 3d. The thickness and width of the YAG:7%Tb(3+) nanobelts are respectively ca. 125 nm and 5.9 ± 0.3 m, and the diameter of YAG:7%Tb(3+) nanofibers is 166.0 ± 20 nm (95% confidence level). The YAG:Tb(3+) nanostructures emit predominantly at 544 nm from the energy levels transition of (5) D4 → (7) F5 of Tb(3+) ions under the excitation of 274-nm ultraviolet light. It was found that the optimum doping molar concentration of Tb(3+) ions for YAG:Tb(3+) nanostructures was 7%. Compared with YAG:7%Tb(3+) nanofibers, YAG:7%Tb(3+) nanobelts exhibit a stronger photoluminescence (PL) intensity under the same doping concentration. Commission International de l'Eclairage (CIE) analysis demonstrates that the emitting colors of YAG:Tb(3+) nanostructures are located in the green region and color-tuned luminescence can be obtained by changing the doping concentration of Tb(3+) and morphologies of the nanostructures, which could be applied in the field of optical telecommunication and optoelectronic devices. The possible formation mechanisms of YAG:Tb(3+) nanobelts and nanofibers are also proposed.

Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3) S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials.