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Anomaly detection (AD) in hyperspectral target detection is of particular interest because no prior knowledge of ground object spectra is required. However, it is difficult to utilize the salient features of hyperspectral image (HSI) and mitigate the effects of noise in hyperspectral AD, which greatly limits the detection performance. Here, we report a strategy to implement hyperspectral AD by visual attention model and background subtraction with adaptive weight. Through band selection method, the most discriminating bands are selected as the input images for subsequent processing. Then, the hyperspectral visual attention model is introduced, for the first time, into hyperspectral AD for extracting the salient feature map of the input images. Furthermore, the background subtraction process that can reduce the background and noise in the salient feature map is developed via curvature filter. Using this operation, the initial anomaly area map is obtained. Finally, incorporating with the spectral information, an adaptive weight map is applied to the initial anomaly area map to further suppress the background. In the experiment, the proposed method is compared with seven other state-of-the-art methods on synthetic and real-world HSI. Most importantly, the results demonstrate that the proposed method is effective and performs better than alternative methods. We believe that this method can open a new avenue of visual processing methods for hyperspectral AD.

Hyperspectral anomaly detection is a challenging task due to the inaccurate evaluation of background statistics and the contamination of anomaly pixels. In this paper, we propose an effecti...

Most CNN-based super-resolution networks require a large number of samples for model training, which may cause overfitting when trained on a specific set, and the internal self-similarity of the test image in this way has also been discarded. To resolve this problem, this paper proposes a novel zero-shot learning (ZSL) network for super resolution. In this model, the training samples are cropped from the input image, which means no extra dataset is required for model training, the overfitting problem in this way can be well avoided. Besides, since all the training samples are cropped from the input itself, the nonlocal self-similarity attributes of the test image can be fully utilized. Moreover, the efficient spatial pyramid of dilated convolutions network with bottleneck (ESP-BNet) is applied in the model as an efficient computational structure to enhance the feature representation. Comparison experiments show that the proposed approach achieves PSNR/SSIM of 31.13dB/87.9% on Set5 dataset and PSNR/SSIM of 27.62dB/78.1% on Set14 dataset, which is around 3dB better than the traditional method and about 1dB higher than those of the state-of-art method.

Ternary I–III–VI semiconductor-based nanocrystals (NCs) exhibit a wide range of applications in optoelectronics, photovoltaics, and biolabeling. This motivates the in-depth study of a method to synthesize them and explore their optical properties. We present an approach for the synthesis of quaternary CuxAg1−xInSe2 (x = 0–1) NCs by means of the cation exchange reaction starting from AgInSe2 NCs. By tailoring the thermodynamic and kinetic parameters, control over both the composition and bandgap was successfully achieved. The optical properties demonstrated significant nonlinear behavior, whereby the photoluminescence (PL) wavelength and bandgap evolved steeply for a range of x 0.5. Optical characterizations indicated that two distinct transition processes, i.e., donor–acceptor pair and free-to-bound recombinations dominated the PL emissions for CuxAg1−xInSe2 NCs with different x values. Furthermore, the obtained NCs were directly modified with phospholipids. In vitro experiments illustrated that the phospholipid-decorated CuxAg1−xInSe2 NCs have excellent biocompatibility and can be used as a fluorescent marker for the fast bioimaging of cancer cells and cancer stem cells in the visible and NIR regions.

Cancer stem cells, which are a population of cancer cells sharing common properties with normal stem cells, have strong self-renewal ability and multi-lineage differentiation potential to trigger tumor proliferation, metastases, and recurrence. From this, targeted therapy for cancer stem cells may be one of the most promising strategies for comprehensive treatment of tumors in the future. We design a facile approach to establish the colon cancer stem cells-selective fluorescent probe based on the low-density lipoprotein (LDL) and the novel AgGa xIn(1- x)S2 quantum dots (AGIS QDs). The AGIS QDs with a high crystallinity are obtained for the first time via cation-exchange protocol of Ga3+ to In3+ starting from parent AgInS2 QDs. Photoluminescence peak of AGIS QDs can be turned from 502 to 719 nm by regulating the reaction conditions, with the highest quantum yield up to 37%. Subsequently, AGIS QDs-conjugated LDL nanocomposites (NCs) are fabricated, in which a cationic polyelectrolyte was used as a coupling reagent to guarantee the electrostatic self-assembly. The structural integrity and physicochemical properties of the LDL-QDs NCs are found to be maintained in vitro, and the NCs exhibit remarkable biocompatibility. The LDL-QDs can be selectively delivered into cancer stem cells that overexpress LDL receptor, and three-dimensional imaging of cancer stem cells is realized. The results of this study not only demonstrate the versatility of nature-derived lipoprotein nanoparticles, but also confirm the feasibility of electrostatic conjugation using cationic polyelectrolyte, allowing reseachers to design nanoarchitectures for targeted diagnosis and treatment of cancer.

Phosphorescent and thermally activated delayed fluorescence (TADF) emitters have met a bottleneck due to the efficiency roll-off problem caused by the accumulation of the lowest triplet excited states with a relatively long lifetime. To achieve a high performance electroluminescence (EL) device with a simultaneously high radiative exciton ratio and a low efficiency roll-off in lighting applications at high luminance, we have demonstrated a novel strategy to construct an efficient hot exciton channel by effective spin mixing of the high-lying singlet and the triplet charge transfer (CT) excited states and restriction of the internal conversion (IC) from the high-lying triplet CT state to the lower triplet state. We selected luminous anthracene and electron-withdrawing triphenylphosphine oxide groups with a high triplet energy level to build four moderated D–A structure molecules which possess a high-lying CT hot exciton. Furthermore, the electronic coupling between the D and A unit can be precisely reduced by means of twisted structure regulation. In our series of novel synthesized materials, 9-[4-(diphenyl-phosphinoyl)-2-methyl-phenyl]-anthracene (An9-MePo) achieved optimization of the hot exciton radiation process and restriction of the IC. Both the maximum radiative exciton ratio of 74% and 72%, and the low efficiency roll-off of 10.6% and 15.9% at a luminance of 10 000 cd m−2 were achieved in a practical lighting application by the An9-MePo based nondoped and doped EL devices, respectively. Our results provide a novel approach to the fabrication of an efficient hot exciton channel, proving the great potential of this EL molecule design strategy for practical lighting applications.

Cu doped Zn–In–S quantum dots (CZIS QDs) were synthesized by a hydrothermal method. The absorption and fluorescence peaks of CZIS QDs shifted monotonically to longer wavelengths with the increase of the Cu precursor and the decrease of Zn and In precursors. The dopant emission wavelength can be easily tuned in the whole visible region ranging from 465 nm to 700 nm by changing the molar ratio of Cu/Zn/In/S. On the basis of experimental results, it was testified that the emission of CZIS QDs was the trap state emission rather than the excitonic emission. The emission mechanisms of CZIS QDs were attributed to three kinds of approaches: (i) photogenerated holes efficiently move to trap states induced by Cu defects and recombine with the electrons in the energy level of sulfur vacancies; (ii) the holes in Cu trap states recombine with the electrons in the surface defect state; (iii) the electrons in the conduction band recombine with the holes in levels caused by Zn vacancies. After coating the ZnS shell around the CZIS core, the fluorescence quantum yield of CZIS QDs can reach 25–35%. CZIS/ZnS QDs conjugated with antibodies were successfully applied for labeling Hep-G2 liver cancer cells. The cytotoxicity studies revealed that the viabilities of the cells incubated with different concentrations of CZIS/ZnS QDs and at different times all remained at a high level of more than 90%. Hence, the CZIS/ZnS nanoparticle is a promising material as the fluorescent probe for biological applications.

We present a hydrothermal approach for the preparation of biocompatible and high-quality Zn

We prepared novel photoanodes structured as FTO/ZnO nanoflowers/ZnTiO3/CdS/CdTeS/ZnS quantum dots (QDs) with highly exposed large specific area and energy coupling. The design of the photoanode expressed significant enhanced photoelectrochemical (PEC) performance such as improved absorption efficiency, reduced recombination rate, and enhanced charge transportation state, resulting in a significant increase in photoelectron current. The multinanoheterostructures photoanode provides a high photocatalytic activity and a maximum photocurrent density up to 9.41 mA/cm2 under AM 1.5 G illumination. The novel cosensitized multinanoheterostructures photoanodes lead to a remarkable and promising application in photoelectrochemical and water splitting reactions.

Guided by the hexagonal lattice symmetry, triangles and hexagons are the most basic morphological units for two-dimensional (2D) transition metal dichalcogenides (TMDs) synthesized by chemical vapor deposition (CVD). Also, it is widely acknowledged that these units start from the single nucleation site and then grow epitaxially. Accordingly, the triangular monolayer (ML) samples are generally considered as single crystals. Here, we report a 2D core–shell growth mode in the CVD process for ML-MoS2, which leads to one kind of “pseudo” single-crystal triangles containing triangular outline grain boundaries (TO-GBs). It is difficult to be optically distinguished from the “true” single-crystal triangles. The weakening of Raman peaks and the remarkable enhancement of photoluminescence (PL) are found at the built-in TO-GBs, which could be useful for high-performance optoelectronics. In addition, the electrical measurements indicate that the TO-GBs are conductive. Furthermore, TO-GBs and the common grain boundari...

The aim of infrared and visible image fusion is to obtain an integrated image that contains obvious object information and high spatial resolution background information. The integrated image is more conductive for a human or a machine to understand and mine the information contained in the image. To attain this purpose, a fusion algorithm based on multi-level Gaussian curvature filtering (MLGCF) image decomposition is proposed. First, a MLGCF is presented and employed to decompose the input source images into three different layers: small-scale, large-scale, and base layers. Then, three fusion strategies—max-value, integrated, and energy-based—are applied to combine the three types of layers, which are based on the different properties of the three types of layers. Finally, the fusion image is reconstructed by summing the three types of fused layers. Six groups of experiments demonstrate that the proposed algorithm performs effectively in most cases by subjective and objective evaluations and even exceeds many high-level fusion algorithms.

Colorectal cancer (CRC) is one type of cancer with high morbidity and mortality worldwide. Photodynamic therapy (PDT), a promising new therapeutic approach for cancer, induces tumor damage through photosensitizer-mediated oxidative cytotoxicity. Hypericin is a powerful photosensitizer with pronounced tumor-localizing properties. In this study, we investigated the phototoxic effects of hypericin-mediated PDT (HYP-PDT) in HCT116 and SW620 cells. We validated that HYP-PDT inhibited cell proliferation, triggered intracellular reactive oxygen species generation, induced S phase cell cycle arrest and apoptosis of HCT116 and SW620 cells. Mechanistically, the results of western blot showed that HYP-PDT downregulated CDK2 expression through decreasing the CDC25A protein, which resulted in the decrease of CDK2/Cyclin A complex. Additionally, HYP-PDT induced DNA damage as evidenced by ATM activation and upregulation of p-H2AX. Further investigation showed that HYP-PDT significantly increased Bax expression and decreased Bcl-2 expression, and then, upregulated the expression of cleaved caspase-9, cleaved caspase-3 and cleaved PARP, thereby inducing apoptosis in HCT116 and SW620 cells. In conclusion, our results indicated that the CDC25A/CDK2/Cyclin A pathway and the mitochondrial apoptosis pathway were involved in HYP-PDT induced S phase cell cycle arrest and apoptosis in colorectal cancer cells, which shows HYP could be a probable candidate used for treating colorectal cancer.

Attention on semiconductor nanocrystals have been largely focused because of their unique optical and electrical properties, which can be applied as light absorber and luminophore. However, the band gap and structure engineering of nanomaterials is not so easy because of their finite size. Here we demonstrate an approach for preparing ternary AgInS2 (AIS), quaternary AgZnInS (AZIS), AgInS2/ZnS and AgZnInS/ZnS nanocompounds based on cation exchange. First, pristine Ag2S quantum dots (QDs) with different sizes were synthesized in one-pot, followed by the partial cation exchange between In(3+) and Ag(+). Changing the initial ratio of In(3+) to Ag(+), reaction time and temperature can control the components of the obtained AIS QDs. Under the optimized conditions, AIS QDs were obtained for the first time with a cation disordered cubic phase and high photoluminescence (PL) quantum yield (QY) up to 32% in aqueous solution, demonstrating the great potential of cation exchange in the synthesis for nanocrystals with excellent optical properties. Sequentially, Zn(2+) ions were incorporated in situ through a second exchange of Zn(2+) to Ag(+)/In(3+), leading to distinct results under different reaction temperature. Addition of Zn(2+) precursor at room temperature produced AIS/ZnS core/shell NCs with successively enhancement of QY, while subsequent heating could obtain AZIS homogeneous alloy QDs with a successively blue-shift of PL emission. This allow us to tune the PL emission of the products from 483 to 675 nm and fabricate the chemically stable QDs core/ZnS shell structure. Based on the above results, a mechanism about the cation exchange for the ternary nanocrystals of different structures was proposed that the balance between cation exchange and diffusion is the key factor of controlling the band gap and structure of the final products. Furthermore, photostability and in vitro experiment demonstrated quite low cytotoxicity and remarkably promising applications in the field of clinical diagnosis.

Layered perovskite-related Sm 6 Ti 4 Fe 2 O 20 compound was successfully synthesized through the intercalation of bilayer SmFeO 3 into the Sm 2 Ti 2 O 7 with pyrochlore structure by means of floating-zone melting technique. The microstructural properties were characterized using aberration-corrected scanning transmission electron microscopy and X-ray diffraction. Electron energy-loss spectroscopy investigation reveals that the Fe 3+ ions prefer to occupy the inner sites within the perovskite-like layers. This compound exhibits clearly the spin glass-like behavior as demonstrated by the magnetic properties measurement. Such complex magnetic behavior could be attributed to the partial chemical order of Ti/Fe over the B sites and the interactions between magnetic ions including Sm 3+ and Fe 3+ . In addition, the multiferroic behavior with the coexistence of the ferroelectricity and ferromagnetism was well established by magnetic and piezoresponse measurements.

Cancer stem cells, which are a population of cancer cells sharing common properties with normal stem cells, have strong self-renewal ability and multi-lineage differentiation potential to trigger tumor proliferation, metastases, and recurrence. From this, targeted therapy for cancer stem cells may be one of the most promising strategies for comprehensive treatment of tumors in the future. We design a facile approach to establish the colon cancer stem cells-selective fluorescent probe based on the low-density lipoprotein (LDL) and the novel AgGa

We present a hydrothermal approach for the preparation of biocompatible and high-quality Zn3In2S6 (ZIS) quantum dots (QDs) in the presence of glutathione (GSH) as a stabilizer at different reaction temperatures. The as-prepared QDs exhibited small particle diameters (from 3.3 to 7.5 nm) with a hexagonal structure and size-dependent optical properties. The combination of the pH value and the amount of GSH played a crucial role in the enhancement of PL intensity. After the incorporation of Ag via cation exchange, the obtained Ag–Zn–In–S (AZIS) QDs demonstrated both red-shifted photo-luminescence (PL) emission and higher quantum yield. Furthermore, based on the investigations of PL lifetimes and excitation intensity-dependent PL spectra, we concluded that PL emission of ZIS QDs originated from shallow donor–acceptor (D–A) pair recombination, and intrinsic trap state-related deep D–A pair transition dominated the main emission of AZIS QDs. Furthermore, the biocompatible AZIS QDs with high quantum yield were applied to targeted labeling and imaging in the cytoplasm of hepatocellular carcinoma cells, indicating their promising applications in single-cell monitoring.

Here we demonstrate a novel and facile strategy of highly luminescent water-soluble Zn-doped AgIn5S8 (ZAIS) nanocrystals and ZAIS/ZnS core/shell structures, which were based on hydrothermal reaction between the acetate salts of the corresponding metals and sulfide precursor in the presence of l-cysteine at 110 °C in a Teflon-lined autoclave. The photoluminescent (PL) emission wavelength can be conveniently tuned from 560 to 650 nm by tailoring the stoichiometric ratio of [Ag]/[Zn]. The as prepared nanocrystals were characterized systematically and exhibit long PL lifetimes more than 100 ns. The influence of experimental conditions, including concentration of l-cysteine and reaction temperature, was investigated. In addition, we performed a coating procedure with the ZnS shell outside the ZAIS core and showed excellent PL quantum yields up to 35%. The in vitro experiment exhibited quite low cytotoxicity and marvelous biocompatibility, revealing their promising prospect in bioscience. Furthermore, the obtained ZAIS/ZnS nanocompounds (NCs) were covalently conjugated to alpha-fetoprotein antibodies and targeted fluorescent imaging for hepatocellular carcinoma cells was realized.

We report the synthesis of ZnIn2S4/AgIn5S8 (ZIS/AIS) heteromicrospheres with tailorable composition and controllable band gap via partial cation exchange for the first time. Detailed studies of the as-prepared samples were carried out using SEM, TEM, STEM-EDS, XRD and layer-by-layer depth XPS analysis. Based on these results, possible cation exchange was proposed, and a critical concentration of Ag+ in the crystals was identified, below which cation exchange cannot occur. Besides, an enhanced photodegradation mechanism was discussed by analyzing the UV-vis-NIR reflectance spectra and the band structure, illustrating that an appropriate thickness of the AIS layer is beneficial to the generation of active species thus favoring the degradation reaction. Further application of dye degradation demonstrated a remarkable photodegradation rate up to 99.2%. Our results shed light on how the cation exchange occurs between ternary and binary crystals, which may open a new avenue to the field for synthesizing materials at the micro-scale.

Guided by the hexagonal lattice symmetry, triangles and hexagons are the most basic morphological units for two-dimensional (2D) transition metal dichalcogenides (TMDs) synthesized by chemical vapor deposition (CVD). Also, it is widely acknowledged that these units start from the single nucleation site and then grow epitaxially. Accordingly, the triangular monolayer (ML) samples are generally considered as single crystals. Here, we report a 2D core-shell growth mode in the CVD process for ML-MoS

Au nanoparticle@SiO2@CdTe/CdS/ZnS quantum dot (QD) composite structures were synthesized by a liquid phase synthesis method. In this paper, three steps were adopted to gradually grow PVP-stabilized Au seeds from which PVP-stabilized Au nanoflower (NF) structures were successfully synthesized. For the sake of controlling the distance between Au NFs and QDs, silica was used as the shell material for coating Au NFs. The applications of this multi-functional nanoprobe in photothermal treatment and bio-labeling were demonstrated on MCF-7 and MDA-MB-231 breast cancer cells labeled with Au NF@SiO2@QDs. The experimental results of viability staining indicate that Au NF@SiO2@QDs composites with an excitation threshold of the photothermal effect of only 1.0 W cm−2 exhibit excellent photothermal conversion efficiency owing to the large absorption cross sections of Au NFs. Compared with that of pure QDs, the fluorescence efficiency of Au NF@SiO2@QDs was increased by 40%, which could be attributed to localized surface plasmon enhanced dipole radiation. Fluorescence imaging results reveal that Au NF@SiO2@QDs targeted the membrane of cancer cells showing strong fluorescence. Therefore, it can be concluded that the composite structure combines the therapeutic and diagnostic modalities.

Background The oncogenesis of hepatocellular carcinoma (HCC) is not clear. The current methods of the pertinent studies are not precise and sensitive. The present study was to use liver cancer cell line to explore the bio-compatibility and cytotoxicity of ternary quantum dots (QDs) probe and to evaluate the possible application of QDs in HCC. Methods CuInS2-ZnS-AFP fluorescence probe was designed and synthesized to label the liver cancer cell HepG2. The cytotoxicity of CuInS2-ZnS-AFP probe was evaluated by MTT experiments and flow cytometry. Results The labeling experiments indicated that CuInS2-ZnS QDs conjugated with AFP antibody could enter HepG2 cells effectively and emit intensive yellow fluorescence by ultraviolet excitation without changing cellular morphology. Toxicity tests suggested that the cytotoxicity of CuInS2-ZnS-AFP probe was significantly lower than that of CdTe-ZnS-AFP probe (t test, F= 0.8, T=-69.326, P>0.001). For CuInS2-ZnS-AFP probe, time-effect relationship was presented in intermediate concentration (>20%) groups (P>0.05) and dose-effect relationship was presented in almost all of the groups (P>0.05). Conclusion CuInS2-ZnS-AFP QDs probe had better bio-compatibility and lower cytotoxicity compared with CdTe-ZnS-AFP probe, and could be used for imaging the living cells in vitro.

Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents.

The coupling of local surface plasmon (LSP) of nanoparticle and surface plasmon (SP) mode produced by metal film can lead to the enhanced electromagnetic field, which has an important application in enhancing the fluorescence of quantum dots (QDs). Herein, the Ag nanocube and Ag film are used to enhance the fluorescence of CdSe QDs. The enhancement is found to relate to the sizes of the Ag nanocube and the thickness of the Ag film. Moreover, we also present the fluorescence enhancement caused by only SP. The result shows that the coupling between metal nanoparticles and metal film can realize larger field enhancement. Numerical simulation verifies that a nanocube can localize a strong electric field around its corner. All the results indicate that the fluorescence of QDs can be efficiently improved by optimizing the parameters of Ag film and Ag cubes.