An Efficient Convolutional Denoising Autoencoder-Based BDS NLOS Detection Method in Urban Forest Environments.

The BeiDou Navigation Satellite System (BDS) provides real-time absolute location services to users around the world and plays a key role in the rapidly evolving field of autonomous driving. In complex urban environments, the positioning accuracy of BDS often suffers from large deviations due to non-line-of-sight (NLOS) signals. Deep learning (DL) methods have shown strong capabilities in detecting complex and variable NLOS signals. However, these methods still suffer from the following limitations. On the one hand, supervised learning methods require labeled samples for learning, which inevitably encounters the bottleneck of difficulty in constructing databases with a large number of labels. On the other hand, the collected data tend to have varying degrees of noise, leading to low accuracy and poor generalization performance of the detection model, especially when the environment around the receiver changes. In this article, we propose a novel deep neural architecture named convolutional denoising autoencoder network (CDAENet) to detect NLOS in urban forest environments. Specifically, we first design a denoising autoencoder based on unsupervised DL to reduce the long time series signal dimension and extract the deep features of the data. Meanwhile, denoising autoencoders improve the model's robustness in identifying noisy data by introducing a certain amount of noise into the input data. Then, an MLP algorithm is used to identify the non-linearity of the BDS signal. Finally, the performance of the proposed CDAENet model is validated on a real urban forest dataset. The experimental results show that the satellite detection accuracy of our proposed algorithm is more than 95%, which is about an 8% improvement over existing machine-learning-based methods and about 3% improvement over deep-learning-based approaches.

Controlled Synthesis of Lead-Free Double Perovskite Colloidal Nanocrystals for Nonvolatile Resistive Memory Devices.

Although lead-free double perovskites such as Cs2AgBiBr6 have been widely explored, they still remain a daunting challenge for the controlled synthesis of lead-free double perovskite nanocrystals with highly tunable morphology and band structure. Here, we report the controlled synthesis of lead-free double perovskite colloidal nanocrystals including Cs2AgBiBr6 and Cs2AgInxBi1-xBr6 via a facile wet-chemical synthesis method for the fabrication of high-performance nonvolatile resistive memory devices. Cs2AgBiBr6 colloidal nanocrystals with well-defined cuboidal, hexagonal, and triangular morphologies are synthesized through a facile wet-chemical approach by tuning the reaction temperature from 150 to 190 °C. Further incorporating indium into Cs2AgBiBr6 to synthesize alloyed Cs2AgInxBi1-xBr6 nanocrystals not only can induce the indirect-to-direct bandgap transition with enhanced photoluminescence but also can improve its structural stability. After optimizing the active layers and device structure, the fabricated Ag/polymethylene acrylate@Cs2AgIn0.25Bi0.75Br6/ITO resistive memory device exhibits a low power consumption (the operating voltage is ∼0.17 V), excellent cycling stability (>10 000 cycles), and good synaptic property. Our study would enable the facile wet-chemical synthesis of lead-free double perovskite colloidal nanocrystals in a highly controllable manner for the development of high-performance resistive memory devices.

Gigantic and Continuous Output Power in Ionic Thermo-Electrochemical Cells by Using Electrodes with Redox Couples.

The main obstacle of ionic thermo-electrochemical cells (TECs) in continuous power supply lies in a low heat-to-electricity energy conversion efficiency because most TECs work in thermodiffusion mode in which the ions are confined in a liquid/electrolyte media. The introduction of the redox couple onto the electrode surface may overcome the obstacle by resolving the low mass transport rate of ions caused by the redox process occurring near but not on the electrode surface. Herein, the authors demonstrate enhancement of TECs by integrating the redox couple directly onto the electrode surface to maximize the mass transport efficiency. A discontinuous interfacial modification strategy is developed by using a carbon cloth/iron (II/III) phytate as the symmetric electrodes. The gelled electrolyte consisting of a polyacrylamide matrix and phytic acid is shown to promote selective ion diffusion. A synergistic combination consisting of the thermodiffusion effect and redox reactions on the electrode is established in a pre-treated layout. Such TEC affords a high output voltage of 0.4 V, an excellent instantaneous output power density (20.26 mW m-2 K-2 ) and a record-high 2 h output energy density (2451 J m-2 ) under TH = 30 °C with TC = 15 °C, with an ultrahigh Carnot-relative efficiency of 1.12%.

New Strategy for the Design of Anti-Corrosion Coatings in Bipolar Plates Based on Hybrid Organic-Inorganic Layers.

As a star material in conducting polymers, a polypyrrole coating was assembled onto the surface of 316 stainless steel by an electrochemical method. In the next step, the composite layer consisting of carbon nitride nanosheets (CNNS) and polymethyl methacrylate (PMMA) was sprayed. The corrosion manner of composite coatings in a simulated proton-exchange membrane fuel cell (PEMFC) environment was evaluated. The results show that the final coating generated at a voltage of 1.0 has demonstrated the optimized corrosion resistance. The polypyrrole layer improves the corrosion resistance of the stainless steel substrate, and the CNNS/PMMA coating further strengthens the physical barrier effect of the coating in corrosive solutions.

Wind turbine anomaly detection based on SCADA: A deep autoencoder enhanced by fault instances.

An increasing number of deep autoencoder-based algorithms for intelligent condition monitoring and anomaly detection have been reported in recent years to improve wind turbine reliability. However, most existing studies have only focused on the precise modeling of normal data in an unsupervised manner; few studies have utilized the information of fault instances in the learning process, which results in suboptimal detection performance and low robustness. To this end, we first developed a deep autoencoder enhanced by fault instances, that is, a triplet-convolutional deep autoencoder (triplet-Conv DAE), jointly integrating a convolutional autoencoder and deep metric learning. Aided by fault instances, triplet-Conv DAE can not only capture normal operation data patterns but also acquire discriminative deep embedding features. Moreover, to overcome the difficulty of scarce fault instances, we adopted an improved generative adversarial network-based data augmentation method to generate high-quality synthetic fault instances. Finally, we validated the performance of the proposed anomaly detection method using a multitude of performance measures. The experimental results show that our method is superior to three other state-of-the-art methods. In addition, the proposed augmentation method can efficiently improve the performance of the triplet-Conv DAE when fault instances are insufficient.

The association of serum immunoglobulin and complement levels and liver fibrosis and inflammation stage in patients with chronic hepatitis B.

The utility of measurement of serum immunoglobulin and complement in chronic hepatitis B (CHB) patients remains controversial. This study aimed to investigate the association of serum immunoglobulin and complement levels and liver fibrosis and inflammation stage in CHB patients. A total of 687 patients with CHB who underwent liver biopsy were enrolled. Serum immunoglobulin and complement were measured before liver biopsy, and liver pathological results were recorded. Associations of serum immunoglobulin and complement levels and liver fibrosis and inflammation stage were analysed. C3, C4, IgG and IgG1 had statistically significant differences among different fibrosis and different inflammation groups. Both C3 and C4 negatively correlated with fibrosis and inflammation stage, but IgG and IgG1 showed opposite results. C3, C4, IgG and IgG1 had statistical significance to predict ≥S2, ≥S3 and S4, and also had statistical significance to predict ≥G2, ≥G3 and G4. The area under curve (AUC) of the combination of C3, C4 and IgG (C3 + C4 + IgG) for predicting ≥S2, ≥S3 and S4 was 0.640 (95% CI: 0.603, 0.676), 0.674 (95% CI: 0.638, 0.709) and 0.744 (95% CI: 0.710, 0.776), respectively. The AUC of C3 + C4 + IgG for predicting ≥G2, ≥G3 and G4 was 0.723 (95% CI: 0.688, 0.756), 0.674 (95% CI: 0.638, 0.709) and 0.771 (95% CI: 0.738, 0.802), respectively. C3, C4, IgG and IgG1 are correlated with liver fibrosis and inflammation stage in CHB patients. C3, C4, IgG and IgG1 have diagnostic value for liver fibrosis and inflammation. C3 + C4 + IgG may improve diagnostic accuracy.

[Clinical Study on the Distribution Frequency of Anti-Mur in Southern Fujian Area and Its Cause of Hemolytic Disease of the Newborn].

OBJECTIVE: To investigate the distribution frequency of anti-Mur and the characteristics of hemolytic disease of the newborn by anti-Mur in this region, and to provide basis for guiding clinical safe blood transfusion. METHODS: Anti-Mur detected in blood preparation or transfusion cases from November 2020 to December 2021 in our hospital were retrospectively analyzed, the laboratory test data and relevant clinical data of the patients were statistically analyzed. RESULTS: Among 39 069 cases of blood preparation or transfusion, 345 cases of irregular antibody were detected, including 23 cases of anti-Mur, 7 cases of male, and 4 cases of blood transfusion history. Among the 16 women, 9 had history of only pregnancy, 2 had history of only blood transfusion, and 5 had history of both blood transfusion and pregnancy. The median age of anti-Mur patients was 59(19-78) years old, which was higher than the median age of other positive patients in the same period, 45(1 day-93 year) years old (P<0.05), but there was no significant difference in gender between groups (P＞0.05). A child with hyperbilirubinemia was diagnosed with hemolytic disease of the newborn by anti-Mur after detection of anti-Mur in erythrocyte elution liquid and maternal serum. CONCLUSION: Anti-Mur has important clinical significance in Southern Fujian area, and its generation is closely related to the history of immunization. The age of anti-Mur detected is higher than that of other positive patients. Hemolytic disease of the newborn caused by anti-Mur has severe anemia symptoms and is easy to miss detection, which should be paid more attention to.

Solvent-Type Passivation Strategy Controls Solid-State Self-Quenching-Resistant Behavior in Sulfur Dots.

Treatment of sulfur dots with polyethylene glycol (PEG) has been an efficient way to achieve a high luminescence quantum yield, and such a PEG-related quantum dot (QD)-synthesis strategy has been well documented. However, the polymeric insulating capping layer acting as the "thick shell" will significantly slow down the electron-transfer efficiency and severely hamper its practical application in an optoelectric field. Especially, the employment of synthetic polymers with long alkyl chains or large molecular weights may lead to structural complexity or even unexpected changes of physical characteristics for QDs. Therefore, in sulfur dot preparation, it is a breakthrough to use short-chain molecular species to replace PEG for better control and reproducibility. In this article, a solvent-type passivation (STP) strategy has been reported, and no PEG or any other capping agent is required. The main role of the solvent, ethanol, is to directly react with NaOH, and the generated sodium ethoxide passivates the surface defects. The afforded STP-enhanced emission sulfur dots (STPEE-SDs) possess not only the self-quenching-resistant feature in the solid state but also the extension of fluorescence band toward the wavelength as long as 645 nm. The realization of sulfur dot emission in the deep-red region with a decent yield (8.7%) has never been reported. Moreover, a super large Stokes shift (300 nm, λex = 345 nm, λem = 645 nm) and a much longer decay lifetime (109 µs) have been found, and such values can facilitate to suppress the negative influence from background signals. Density functional theory demonstrates that the surface passivation via sodium ethoxide is dynamically favorable, and the spectroscopic insights into emission behavior could be derived from the passivation effect of the sulfur vacancy as well as the charge-transfer process dominated by the highly electronegative ethoxide layer.

Key Role Effect of Samarium in Realizing Zero Thermal Quenching and Achieving a Moisture-Resistant Reddish-Orange Emission in Ba3LaNb3O12:Sm3.

The strategy to enhance phosphor stability against thermal quenching and moisture conditions will contribute to controlling the feature of phosphor-converted white-light-emitting diodes (pc-WLEDs). Herein, an effective strategy is achieved with the incorporation of Sm3+ ions, and a robust reddish-orange emission (no thermal quenching up to 498 K) is obtained based on Ba3LaNb3O12 as a host. In light of excitation by near-ultraviolet irradiation at 408 nm, Ba3LaNb3O12:Sm3+ gives rise to a typical signal ascribed to the 4G5/2 → 6HJ/2 (J = 5, 7, 9, and 11) transitions of Sm3+ ions. The concentration quenching effect is observed when the Sm3+ content exceeds 10%, and the quenching mechanism is caused by electronic dipole-dipole interactions. Based on the narrow emission curves, a very high color purity (92.4%) could be recorded. The Sm3+ substitution at the Ba2+/La3+ site leads to a rigid structural lattice and abundant electron-trapping centers for the Sm3+ ions, which will be responsible for the zero-thermal-quenching phenomenon. In addition, oleic acid (OA) is selected to form a hydrophobic covering surface structure to protect Ba3LaNb3O12:Sm3+, which can assist in improving the moisture resistance. The most favorable parameters concerning the warm-light emission (a high general color rendering index, Ra, of 85.7 and a low correlated color temperature, CCT, of 4965 K) can be achieved in pc-WLEDs containing an OA-modified sample. Moreover, its luminous efficiency, LE, can maintain 82.9% of its initial value after 120 h under controlled environmental conditions of 85 °C and 85% humidity. These results pave a new way to optimize the sample as a potential candidate for red-emitting materials.

Multi-Geometric Reasoning Network for Insulator Defect Detection of Electric Transmission Lines.

To address the challenges in the unmanned system-based intelligent inspection of electric transmission line insulators, this paper proposed a multi-geometric reasoning network (MGRN) to accurately detect insulator geometric defects based on aerial images with complex backgrounds and different scales. The spatial geometric reasoning sub-module (SGR) was developed to represent the spatial location relationship of defects. The appearance geometric reasoning sub-module (AGR) and the parallel feature transformation (PFT) sub-module were adopted to obtain the appearance geometric features from the real samples. These multi-geometric features can be fused with the original visual features to identify and locate the insulator defects. The proposed solution is assessed through experiments against the existing solutions and the numerical results indicate that it can significantly improve the detection accuracy of multiple insulator defects using the aerial images.

Lanthanide Molecular Species Generated Fe3O4@SiO2-TbDPA Nanosphere for the Efficient Determination of Nitrite.

The presence of nitrite (NO2-) in water and food leads to serious problems in public health and the environment. Therefore, it is important to develop a rapid and efficient method for the selective detection of NO2-. In this work, the synthesis and characterization of magnetic Fe3O4@SiO2-TbDPA nanoprobe have been carried out. The Fe3O4@SiO2-TbDPA aqueous solution exhibits a strong green emission. Due to the addition of various concentrations of NO2- (0-100 µM), the fluorescence intensity has been suppressed. The nanoprobe Fe3O4@SiO2-TbDPA exhibits excellent selectivity and sensitivity toward NO2- ions. Excellent linearity is obtained in the range of 5-80 µM with a detection limit of 1.03 µM. Furthermore, the presence of magnetic Fe3O4 nanoparticles in Fe3O4@SiO2-TbDPA nanospheres will also facilitate the effective separation of Fe3O4@SiO2-TbDPA from the aqueous solution. Our proposed strategy is expected to fabricate an organic-inorganic hybrid magnetic nanomaterial and can be used as an efficient sensor. It has been shown that this new strategy has numerous advantages, such as high stability, selectivity, and simplicity of operation. It demonstrates great potential for simple and convenient NO2- detection. It may expand to a variety of ranges in environmental monitoring and biomedical fields.

Exploration of Sulfur-Containing Nanoparticles: Synthesis, Microstructure Analysis, and Sensing Potential.

In this work, three different sulfur sources such as sulfur powder, sodium sulfide, and sodium thiosulfate are selected to prepare sulfur-derived quantum dots (S-QDs), Na2S-derived nanoparticles (NS-NPs), and Na2S2O3--derived QDs (NSO-QDs) in the presence of NaOH or assisted by hydrogen peroxide etching. The low sulfur percentage in the above three samples and the synthesis experiments in the presence of nitrogen/oxygen all support that poly(ethylene glycol) (PEG) plays an important role during the assembly process and the definition of sulfur dots is not accurate. For photophysical features, remarkable green quantum dots (S-QDs) possess an excitation-independent emission peak at 500 nm. But NS-NPs and NSO-QDs demonstrate observable shift tendency, and the evolution of emission profiles varies from 480 to 586 nm. NSO-QDs can be used as a fluorescent probe for highly selective and quantitative detection of Ni2+ in an aqueous solution in the presence of potential interfering ions with a low detection limit (0.18 µM) and a wide linear range (8-380 µM). Their reusability performance has also been demonstrated by employing dimethylglyoxime as the restoration reagent.

Realization of an Optical Thermometer via Structural Confinement and Energy Transfer.

The influence of temperature on a variety of physiological or chemical processes has generated considerable interest, and recently noninvasive lanthanide-incorporated optical thermometers have been considered as promising candidates for monitoring its changes at different scales. Herein, a novel Bi3+-activated Sr3-xGdxGaO4+xF1-x phosphor with tunable color has been constructed by a cooperative cation-anion substitution strategy with to the replacement of [Sr2+-F-] by [Gd3+-O2-]. When x = 0, the sample Sr3GaO4F/Bi3+ possesses a peak wavelength at 438 nm, and this value will shift to 470 nm if x is equal to 1 (Sr2GdGaO5/Bi3+). In addition, photoluminescence tuning from blue to red has been realized successfully by an efficient Bi3+ → Eu3+ energy migration model in Sr2.6Gd0.4GaO4.4F0.6 samples. The specific Bi3+ → Eu3+ energy transfer has been explained by dipole-dipole interactions derived from a model of the Dexter pathway. Intriguingly, the two dopants (a blue signal from Bi3+ and a red signal from Eu3+) possess different thermal responses to increasing temperature. Accordingly, the intensity ratio values are sensitive to the temperature changes. The energy level cross relaxation causes the quenching effect of Bi3+, and the multi-phonon de-excitation mode leads to the thermal quenching of Eu3+. At room temperature (298 K), the determined maximum relative sensitivity (Sr) is 1.27% K-1. Moreover, the absolute sensitivity (Sa) is 0.067 K-1 since the temperature is elevated to 523 K. The collected results are superior to most of the reported optical thermometry materials.

Extension of Spectral Shift Controls from Equivalent Substitution to an Energy Migration Model Based on Eu2+/Tb3+-Activated Ba4-xSrxGd3-xLuxNa3(PO4)6F2 Phosphors.

Single-phase phosphors with tunable emission colors are crucial to develop high-performance white light-emitting diodes since they are valuable to improve the energy efficiency, color rendering index, and correlated color temperature. Most of the studies have been conducted to control the spectral shifts via a polyhedral distortion or chemical unit cosubstitution strategy. The combination of host optimization and dopant activator design in a single-phase phosphor system is very rare. Herein, a partial substitution strategy of [Ba2+-Gd3+] by [Sr2+-Lu3+] has been employed in Ba4-xSrxGd3-x-yLuxNa3(PO4)6F2/5% Eu2+ (x = 0-0.40) phosphors. Also, the energy migration from Eu2+ to Tb3+ ions has been investigated in as-prepared samples. Consequently, the emitted signal is observed to shift from 470 to 575 nm derived from equivalent substitutions, which is attributed to specific performance by the emission profile of Eu2+, and such results are closely related to splitting of the crystal field and energy transfer among various luminescent centers. Moreover, the tunable yellowish-green emitting material has been assembled by incorporating ion pairs (Eu2+ → Tb3+) into the Ba3.85Sr0.15Gd2.85Lu0.15Na3(PO4)6F2, and their relative ratios are varied. The corresponding Eu2+ → Tb3+ energy migration process is assigned to be the dipole-quadrupole interaction by the Inokuti-Hirayama model. This work provides rational guidance for the design and discovery of new products with tunable emission colors, originating from the cosubstitution strategy and energy conversion model.

[Investigation and Analysis of Non-ABO Hemolytic Disease of the Newborn].

OBJECTIVE: To study the serological detection characteristics and antibody specific distribution of hemolytic disease of the newborn (HDN) caused by irregular antibodies through retrospective case analysis. METHODS: A total of 3 047 suspected cases of HDN were submitted by the Neonatal Department of our hospital from January 2014 to December 2019. Non ABO-HDN cases confirmed in our laboratory were taken as the research objects, while some cases of ABO-HDN were randomly selected as control. Disease-causing antibody specificity, serological detection characteristics, total bilirubin change trend and gender ratio of non ABO-HDN patients were explored. RESULTS: Sixty-seven cases of non ABO-HDN were confirmed from the suspected cases of HDN, Among which 45 males and 22 females were detected with the positive rate 1.48% and 0.72%, respectively. The mothers of 65 cases had two or more pregnancies. The detected irregular antibodies were mainly involved with Rh system, MNS system, Kidd system and Lewis system, among which Rh system accounted for 88.07% of the total antibody detection rate. Compared with that of ABO-HDN patients, the total bilirubin of non ABO-HDN patients developed more rapidly with a higher peak and a longer duration (P<0.001). In terms of serological detection, the positive rate of non ABO-HDN direct antibody test was 97.01%, which was higher than 47.00% of ABO-HDN (P<0.001), and the agglutination strength was often ≥ 2+, but there were still weak positive or negative cases of direct antibody test. CONCLUSION: Non ABO-HDN caused by irregular antibodies mostly occurs in fetuses whose mothers experience multiple pregnancies, and the number of males is more than females. The irregular antibodies detected are mainly attributed to Rh system. The peak value of bilirubin in non ABO-HDN patients is higher and lasts longer than that in ABO-HDN patients. Direct antiglobulin test may be used to roughly distinguish ABO-HDN from non ABO-HDN.

Determination of Hypochlorite via Fluorescence Change from Blue to Green Based on 4-(1 H-imidazo [4,5-f] [1,10]-phenanthrolin-2-yl) Benzaldehyde Oxime.

The new design strategy will provide the possibility for preparing a dynamic sensor by employing the inhibition of C = N isomerization. In this work, the functional probe 4-(1 H-imidazo [4,5-f] [1,10]-phenanthrolin-2-yl) benzaldehyde oxime (compound 4) has been synthesized and such molecule gives rise to blue emission. Due to the incorporation of hypochlorite, the oxime group can be oxidized to the structure of aldehyde. As a result, the molecular motif exhibits sharp emission change from blue to green due to the addition of hypochlorite with enough sensitivity and selectivity (detection limit = 53 nM, linear range 0.5-8.0 µM). It has also been used for monitoring ClO- by employing solution color change and the absorption signal difference could effectively rule out the effects of interference species. To our knowledge, it will be the first case of a highly selective hypochlorite sensor derived from oxime isomerization reaction based on phenanthroline backbone.

Stepwise Assembly Protocols for the Rational Design of Lanthanide Functionalized Carbon Dots-Hydrogel and its Sensing Evaluation.

Inorganic-organic optical probe based on lanthanide emission will provide a new way for specific applications. In this work, sarcosine and urea are selected as raw materials to synthesize carbon dots with cyan-emissive color. In the next step, indicator components (Ethylene Diamine Tetraacetic Acid and lanthanide ions) are incorporated onto carbon quantum dots (CQDs) and the flexible alginate hydrogel is employed as the host to accommodate the emissive species. The soft material can exhibit typical red and green emissions. Its luminescence is responsive to calcium ions and the detection limit has been calculated to be 0.84 µM and 0.92 µM respectively. Such optical device can be employed as a portable probe in a variety of scientific fields due to its convenience and flexibility.

Single optical sensor to multiple functions: Ratiometric sensing for SO32- and dual signal determination for copper (II).

Polymer dots possess superior emissive features, but most of them give rise to luminescence bands in the blue region. In addition, blue or green emissions have difficulty in penetrating tissue deeply. Therefore, long wavelength emissive signals are welcome for the development and application of polymeric dots towards sensing and bio-analysis. Herein, the color-tunable fluorescence polymer nanoparticles (F-PNPs) have been synthesized via one-step strategy based on the employment of hydroquinone and polyethyleneimine as precursors at low temperature. Moreover, its emission peak can be shifted from 523 nm to 612 nm by varying the excitation wavelength in the range of 380 nm to 480 nm. In view of sensing assessment, F-PNPs enable the quantitative determination of trace amount of SO32- and Cu2+. In the presence of SO32-, the polymer dots exhibit ratiometric fluorescence signals in deionized water and the color change from green to blue has been clearly observed by naked eyes (detection limit = 59 nM). In addition, two emission bands at 545 nm (green) and 601 nm (red) are observed to be responsive to the exposure of Cu2+. The entire dual sensing system for the detection of Cu2+ will be more accurate and reliable. The evaluation results reveal their optical signals are improved linearly due to the addition of Cu2+ at increasing concentrations and the detection limits are calculated to be 76 nM (green) and 41 nM (red), respectively. Such polymeric network will provide a new dynamic platform for sensing purposes in biomedicine study, environmental protection, and food safety.

Efficient Energy Transfer from Trap Levels to Eu3+ Leads to Antithermal Quenching Effect in High-Power White Light-Emitting Diodes.

The most critical aspect in the assembly of phosphor-converted white light-emitting diodes (pc-WLEDs) is how to stabilize the device in a practical environment. The high applied currents can generate enormous heat up to more than 100 °C, and such a continuous illumination process will lead to serious effects concerning the stability of the device. Therefore, the new search for examples to fully suppress thermal quenching effect is a real challenge. In this study, a novel Eu3+-activated CaMgGeO4 (CMGO) phosphor of olivine type is developed via a conventional solid-state reaction. The results reveal that Eu3+ occupies the low symmetric Ca2+ site of this host. Upon visible-light sensitization at 464 nm, a dominant red emission band with maximum at 612 nm is witnessed. Its full width at half-maximum (fwhm) is merely ∼4.37 nm, and a high color purity of around 94% is achieved. Their corresponding Commission Internationale de L'Eclairage (CIE) coordinates are very close to standard red color coordinates (0.666, 0.333). The influence of concentration and temperature on the optical property has been explored. It has been discovered that the optimized sample (CMGO:0.01Eu3+) is not influenced by the thermal quenching effect and its fluorescent intensity is improved even up to 473 K, which is mainly attributed to the incorporation of abundant trap sites generated by the nonequivalent substitution Eu3+ for Ca2+. After it is integrated into commercially available YAG:Ce3+ phosphor-based pc-WLEDs, the excellent optical parameters of the fabricated WLEDs are evaluated. The correlated color temperature (CCT) varies from cool white (6458 K) to warm (4370 K), and the color rendering index (CRI) increases from 78 to 86 under a high flux operating current of 200 mA. Furthermore, the chromaticity coordinates remain almost stable with the increasing drive current from 200 mA to 1000 mA. It is highly expected that CaMgGeO4:0.01Eu3+ will become a suitable red phosphor for the preparation of white LEDs with high efficiency.

Rapid conversion from common precursors to carbon dots in large scale: Spectral controls, optical sensing, cellular imaging and LEDs application.

The commercial production of carbon dots will be concerned with the simplicity and energy consumption. Herein, maleic acid and m-phenylenediamine form elegantly simple sources for carbon dots. The two precursors are dissolved in formamid (abbreviated as FA) or N,N-dimethylformamide (abbreviated as DMF) and the dehydration-condensation processes have been performed at 30 min or 120 min under room temperature. No external energy/irradiations, reactants or high temperature will be required and the afforded carbon dots (abbreviated as CDs) are collected by extraction, centrifugation, dialysis and column chromatography. It has been found for the first time the choice of organic solvents has been correlated with emission color. The blue-emitting CDs (abbreviated as B-CDs) and green-emitting CDs (abbreviated as G-CDs) are yielded in FA and DMF respectively. Facts support that the increase of -CONH- units causes red-shift in emissions. The optical sensing of tetracycline has been explored and the detection limit of blue-emitting CDs is as low as 25 nM. Live cells exposed to B-CDs and G-CDs (0.5 mg/ml) show no apparent changes via both Cell Counting Kit-8 and Annexin V/7-AAD analysis. The blue and green fluorescent signals can be easily tracked in cells. It has been demonstrated that the two carbon dots can be fabricated as multiple-color light-emitting diodes (abbreviated as LEDs).