Tailoring the Luminescent Properties of SrS:Ce3+ by Sr-Deficiency and Na+ Doping.

Ce3+-doped SrS phosphors with a charge-compensating Na+ addition were successfully synthesized via a solid-state reaction method, and the related X-ray diffraction patterns can be indexed to the rock-salt-like crystal structure of the Fm3̅m space group. SrS:(Ce3+)x (0.005 ≤ x ≤ 0.05) and SrS:(Ce3+)0.01,(Na+)y (0.005 ≤ y ≤ 0.030) phosphors were excited by 430 nm UV-Vis light, targeted to the 5d1 → 4f1 transition of Ce3+. The composition-optimized SrS:(Ce3+)0.01, (Na+)0.015 phosphors showed an intense broad emission band at λ = 430-700 nm. The doping of Na+ was probed by solid-state nuclear magnetic resonance. The 430 nm pumped white light-emitting diode structure fabricated with a combination of SrS:(Ce3+)0.01,(Na+)0.015 and Sr2Si5N8:Eu2+ phosphors shows a color-rendering index (Ra) of 89.7. The proposed strategy provides new avenues for the design and realization of novel high color quality solid-state LEDs.

[Research on classification of benign and malignant lung nodules based on three-dimensional multi-view squeeze-and-excitation convolutional neural network].

Lung cancer is the most threatening tumor disease to human health. Early detection is crucial to improve the survival rate and recovery rate of lung cancer patients. Existing methods use the two-dimensional multi-view framework to learn lung nodules features and simply integrate multi-view features to achieve the classification of benign and malignant lung nodules. However, these methods suffer from the problems of not capturing the spatial features effectively and ignoring the variability of multi-views. Therefore, this paper proposes a three-dimensional (3D) multi-view convolutional neural network (MVCNN) framework. To further solve the problem of different views in the multi-view model, a 3D multi-view squeeze-and-excitation convolution neural network (MVSECNN) model is constructed by introducing the squeeze-and-excitation (SE) module in the feature fusion stage. Finally, statistical methods are used to analyze model predictions and doctor annotations. In the independent test set, the classification accuracy and sensitivity of the model were 96.04% and 98.59% respectively, which were higher than other state-of-the-art methods. The consistency score between the predictions of the model and the pathological diagnosis results was 0.948, which is significantly higher than that between the doctor annotations and the pathological diagnosis results. The methods presented in this paper can effectively learn the spatial heterogeneity of lung nodules and solve the problem of multi-view differences. At the same time, the classification of benign and malignant lung nodules can be achieved, which is of great significance for assisting doctors in clinical diagnosis.

Cerium Oxysulfide with O-Ce-S Bindings for Efficient Adsorption and Conversion of Lithium Polysulfide in Li-S Batteries.

Understanding of adsorption and kinetic conversion of polysulfide lithium (LiPSs) in Li-S batteries is quite crucial for the design of efficient effective sulfur carriers. Herein, based on the possible interactions with LiPSs, Ce2O2S with unique O-Ce-S bindings is proposed to be used as a promising carrier additive and a 2D Ce2O2S/C composite is synthesized via a one-facile NaCl-template method and subsequent sulfuration under 700 °C. The 2D Ce2O2S/C exhibits a stronger adsorption capability than CeO2/C through the adsorption test for Li2S6. Combined with XPS and DFT results, the superiority is mainly originated from the formation of S-S and Li-S bonds between LiPSs and the lattice S on the surface of Ce2O2S. The 2D Ce2O2S/C composite also exhibits a better catalytic ability than CeO2 according to the change of the free energies of the polysulfides during the discharge process, which coincides with the lower oxidation potential for Li2S2/Li2S transition by cyclic voltammetry. Resultantly, the cathodes using the Ce2O2S/C composite as a carrier manifest an enhanced rate and cycling performances. Hence, our work paves a phenomenon wherein Ce2O2S with O-Ce-S bindings is more beneficial to improve the cycling stability of Li-S batteries than CeO2 containing single Ce-O bonds, which may be also suitable for other kinds of metallic sulfur oxide compounds.

Material and Ingenious Synthesis Strategy for Short-Wavelength Infrared Light-Emitting Device.

Infrared (IR) light-emitting materials have wide applications. However, variety and economical accesses to obtain IR materials and devices are still limited, because the IR-emitting materials are always suffering from two obstacles, namely, lower absorption and lower emission efficiency. In this work, using a modified high-temperature solid-state reaction an efficient short-wavelength IR luminescent material is successfully synthesized. On the basis of the excellent luminescent properties, a convenient IR light-emitting diode (LED) device is fabricated by combining the novel IR material with a commercial UV LED chip. Besides the anticipation that it may lead to a boost of the application of IR device in different fields, importantly, we also consider that the ingenious synthesis strategy may open a door for obtaining novel ions doped functional materials.

The glass phase in the grain boundary of Na3Zr2Si2PO12, created by gallium modulation.

Na3Zr2Si2PO12 has been proven to be a promising electrolyte for solid-state sodium batteries. However, its poor conductivity prevents application, caused by the large ionic resistance created by the grain boundary. Herein, we propose an additional glass phase (Na-Ga-Si-P-O phase) to connect the grain boundary via Ga ion introduction, resulting in enhanced sodium-ion conduction and electrochemical performance. The optimized Na3Zr2Si2PO12-0.15Ga electrolyte exhibits Na+ conductivity of 1.65 mS cm-1 at room temperature and a low activation energy of 0.16 eV, with 20% newly formed glass phase enclosing the grain boundary. Temperature-dependent NMR line shapes and spin-lattice relaxation were used to estimate the Na self-diffusion and Na ion hopping. The dense glass-ceramic electrolyte design strategy and the structure-dynamics-property correlation from NMR, can be extended to the optimization of other materials.

Facile synthesis and thermoelectric properties of self-assembled Bi2Te3 one-dimensional nanorod bundles.

Self-assembled Bi(2)Te(3) one-dimensional nanorod bundles have been fabricated by a low-cost and facile solvothermal method with ethylene diamine tetraacetic acid as an additive. The phase structures and morphologies of the samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectrometry, and transmission electron microscope measurements. The growth mechanisms have been proposed based on the experimental results. The full thermoelectric properties of the nanorod bundles have been characterized and show a large improvement in the thermal conductivity attributed to phonon scattering of the nanostructures and then enhance the thermoelectric figure of merit. This work is promising for the realization of new types of highly efficient thermoelectric semiconductors by this method.

3D multi-view squeeze-and-excitation convolutional neural network for lung nodule classification.

PURPOSE: Early screening is crucial to improve the survival rate and recovery rate of lung cancer patients. Computer-aided diagnosis system (CAD) is a powerful tool to assist clinicians in early diagnosis. Lung nodules are characterized by spatial heterogeneity. However, many attempts use the two-dimensional multi-view (MV) framework to learn and simply integrate multiple view features. These methods suffer from the problems of not capturing the spatial characteristics effectively and ignoring the variability of multiple views. In this paper, we propose a three-dimensional MV convolutional neural network (3D MVCNN) framework and embed the squeeze-and-excitation (SE) module in it to further address the variability of each view in the MV framework. METHODS: First, the 3D multiple view samples of lung nodules are extracted by the spatial sampling method, and a 3D CNN is established to extract 3D abstract features. Second, build a 3D MVCNN framework according to the 3D multiple view samples and 3D CNN. This framework can learn more features of different views of lung nodules, taking into account the characteristics of spatial heterogeneity of lung nodules. Finally, to further address the variability of each view in the MV framework, a 3D MVSECNN model is constructed by introducing a SE module in the feature fusion stage. For training and testing purposes we used independent subsets of the public LIDC-IDRI dataset. RESULTS: For the LIDC-IDRI dataset, this study achieved 96.04% accuracy and 98.59% sensitivity in the binary classification, and 87.76% accuracy in the ternary classification, which was higher than other state-of-the-art studies. The consistency score of 0.948 between the model predictions and pathological diagnosis was significantly higher than that between the clinician's annotations and pathological diagnosis. CONCLUSIONS: The results show that our proposed method can effectively learn the spatial heterogeneity of nodules and solve the problem of multiple view variability. Moreover, the consistency analysis indicates that our method can provide clinicians with more accurate results of benign-malignant lung nodule classification for auxiliary diagnosis, which is important for assisting clinicians in clinical diagnosis.

A novel dichromic self-referencing optical probe SrO:Bi(3+),Eu(3+) for temperature spatially and temporally imaging.

A novel dichromic luminescence probe SrO:Eu(3+),Bi(3+) for temperature sensing is achieved. The detailed luminescence properties, e.g., the excitation emission spectra, energy transfer efficiency, luminescence decay lifetimes and temperature dependent luminescence are comprehensively studied. The two dominant emissions (5)D0→(7)F2 transition of Eu(3+) and the (3)P1→(1)S0 transition of Bi(3+) display adjustable spectrum area. The interaction effect between Eu(3+) and Bi(3+) are proposed. The dichromic emissions are specifically responding to temperature with high sensitivity at ultra-wide range from 30 to 400 °C. Spatial and temporal temperature images on an aircraft surface have been successfully realized under excitation of commercial 365 nm light emitting diode (LED) by painting the SrO:Bi(3+),Eu(3+) phosphor on a plane model. Finally, the thermal quenching mechanism revealed by Arrhenius theory is employed to interpret the temperature sensitive luminescence behaviour.

Sr9Mg(1.5)(PO4)7:Eu(2+): A Novel Broadband Orange-Yellow-Emitting Phosphor for Blue Light-Excited Warm White LEDs.

A new orange-yellow-emitting Sr9Mg(1.5)(PO4)7:Eu(2+) phosphor was prepared via high-temperature solid-state reaction. The structure and optical properties of it were studied systematically. Sr9Mg(1.5)(PO4)7:Eu(2+) can be well-excited by 460 nm blue InGaN chips and exhibit a wide emission band covering from 470 to 850 nm with two main peaks centered at 523 and 620 nm, respectively, which originate from 5d-4f dipole-allowed transitions of Eu(2+) in different crystallographic sites. The sites attribution, concentration quenching, fluorescence decay analysis, and temperature-dependent luminescence properties were investigated in detail. Furthermore, a warm white LED device was fabricated by combining a 460 nm blue InGaN chip with the optimized orange-yellow-emitting Sr9Mg(1.5)(PO4)7:Eu(2+). The color coordinate, correlated color temperature and color rendering index of the fabricated LED device were (0.393, 0.352), 3437 K, and 86.07, respectively. Sr9Mg(1.5)(PO4)7:Eu(2+) has great potential to serve as an attractive candidate in the application of blue light-excited warm white LEDs.

Tri-chromatic white-light emission from a single-phase Ca9Sc(PO4)7:Eu(2+),Tb(3+),Mn(2+) phosphor for LED applications.

A series of single-phase Ca9Sc(PO4)7:Eu(2+),Tb(3+),Mn(2+) phosphors for UV excitations were synthesized by a high-temperature solid-state reaction. Energy transfer from Eu(2+)→ Tb(3+) and Eu(2+)→ Mn(2+) in a Ca9Sc(PO4)7 sample is a feasible route to realize color-tunable emission because Ca9Sc(PO4)7 single-doped Eu(2+)/Tb(3+)/Mn(2+) emit blue, green and red light, respectively. Most of the white light region in the CIE chromaticity diagram has been realized in Ca9Sc(PO4)7:Eu(2+),Tb(3+),Mn(2+) phosphors. Warm white light including the points of (0.337, 0.331), (0.353, 0.355) and (0.358, 0.327) close to day light (0.33, 0.33) with CCT of 5285 K, 4719 K and 4333 K is obtained, respectively.

Reduction of Eu(3+) due to a change of the topological structure of the BO3 unit in borate glass.

Adjusting and controlling an ion's chemical state has always been a focus of researchers' attention. Herein, an intense long-lasting phosphorescence of Eu(2+) is obtained without any sacrificial reductant. The remarkable self-reducing process and the unique luminescence properties stem from a variation of the topological structure of the BO3 triangle.

Single-phased white-light-emitting Ca4(PO4)2O:Ce³âº,Eu²âº phosphors based on energy transfer.

A novel single-composition Ca4(PO4)2O:Ce(3+),Eu(2+) phosphor emitting white light was synthesized by conventional solid-state reaction for light-emitting diode applications. X-ray diffraction, photoluminescence spectra, and luminescence decay spectra were used to characterize the samples. Energy transfer from Ce(3+) to Eu(2+) ions was observed in the co-doped samples, and the transfer mechanism in the Ca4(PO4)2O:Ce(3+),Eu(2+) phosphors was dipole-dipole interaction. The emission hue of Ca4(PO4)2O:Ce(3+),Eu(2+) was found to vary from blue (0.165, 0.188) to white (0.332, 0.300) and eventually to orange (0.519, 0.366) by precisely controlling the ratio of Ce(3+) to Eu(2+). The combination of a 380 nm near-ultraviolet chip with a Ca4(PO4)2O:0.02Ce(3+),0.012Eu(2+) phosphor produced a diode emitting white light with ultra-wideband emission and a correlated color temperature of 4124 K. Overall, results indicated that the prepared samples may be potentially applied in white-light-emitting diodes.

Investigation on Luminescence Properties of a Long Afterglow Phosphor Ca2SnO4:Tm³âº.

A series of new long afterglow phosphors Ca2 SnO4:xTm(3+) were synthesized by using traditional solid-state reactions. XRD measurements and Rietveld refinement revealed that the incorporation of the Tm(3+) dopants generated no second phase other than the original one of Ca2 SnO4, which indicated that the dopants completely merged into the host. The corresponding optical properties were further systematically studied by photoluminescence, phosphorescence, and thermoluminescence (TL) spectroscopy. The results show that the Tm(3+)-related defects account for the bright bluish green afterglow emission from the characteristic f-f transitions of Tm(3+) ions. The bluish green long-lasting phosphorescence could be observed for 5 h by the naked eye in a dark environment after the end of UV irradiation. Two TL peaks at 325 and 349 K from the TL curves were adopted to calculate the depth of the traps, which were 0.45 and 0.78 eV, respectively. The mechanism of the long afterglow emission was also explored.

Sr(1.7)Zn(0.3)CeO4: Eu3+ novel red-emitting phosphors: synthesis and photoluminescence properties.

A series of novel red-emitting Sr1.7Zn0.3CeO4:Eu(3+) phosphors were synthesized through conventional solid-state reactions. The powder X-ray diffraction patterns and Rietveld refinement verified the similar phase of Sr1.7Zn0.3CeO4:Eu(3+) to that of Sr2CeO4. The photoluminescence spectrum exhibits that peak located at 614 nm ((5)D0-(7)F2) dominates the emission of Sr1.7Zn0.3CeO4:Eu(3+) phosphors. Because there are two regions in the excitation spectrum originating from the overlap of the Ce(4+)-O(2-) and Eu(3+)-O(2-) charge-transfer state band from 200 to 440 nm, and from the intra-4f transitions at 395 and 467 nm, the Sr1.7Zn0.3CeO4:Eu(3+) phosphors can be well excited by the near-UV light. The investigation of the concentration quenching behavior, luminescence decay curves, and lifetime implies that the dominant mechanism type leading to concentration quenching is the energy transfer among the nearest neighbor or next nearest neighbor activators. The discussion about the dependence of photoluminescence spectra on temperature shows the better thermal quenching properties of Sr1.7Zn0.3CeO4:0.3Eu(3+) than that of Sr2CeO4:Eu(3+). The experimental data indicates that Sr1.7Zn0.3CeO4:Eu(3+) phosphors have the potential as red phosphors for white light-emitting diodes.

Tunable long lasting phosphorescence due to the selective energy transfer from defects to luminescent centres via tunnelling in Mn(2+) and Tm(3+) co-doped zinc pyrophosphate.

A series of new phosphors Zn2(0.97-x)P2O7:0.06Tm(3+),2xMn(2+) (0 ≤ x ≤ 0.05) were synthesized and their luminescence properties were investigated. The results showed that the defects in all the phosphors were related to Tm(3+), and Mn(2+) merely served as the emission centres. Tm(3+) also acted as an emission centre and yielded blue phosphorescence corresponding to its characteristic f-f emissions in the phosphors where the Mn(2+) concentration was low (x ≤ 0.001), while in the phosphors with high concentrations of Mn(2+) it mainly served as a defect by forming Tm. The electrons thermally released from defects selectively transferred to Mn(2+) centres mainly through thermally-assisted tunnelling and this resulted in their red to near-infrared phosphorescence. By adjusting the ratio of Mn(2+) to Tm(3+) to control the spectral distribution, tunable long lasting phosphorescence from blue to near-infrared was achieved.