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1.
Nat Commun ; 15(1): 3976, 2024 May 10.
Article in English | MEDLINE | ID: mdl-38729948

ABSTRACT

Bleeding and thrombosis are known as common complications of polycythemia for a long time. However, the role of coagulation system in erythropoiesis is unclear. Here, we discover that an anticoagulant protein tissue factor pathway inhibitor (TFPI) plays an essential role in erythropoiesis via the control of heme biosynthesis in central macrophages. TFPI levels are elevated in erythroblasts of human erythroblastic islands with JAK2V617F mutation and hypoxia condition. Erythroid lineage-specific knockout TFPI results in impaired erythropoiesis through decreasing ferrochelatase expression and heme biosynthesis in central macrophages. Mechanistically, the TFPI interacts with thrombomodulin to promote the downstream ERK1/2-GATA1 signaling pathway to induce heme biosynthesis in central macrophages. Furthermore, TFPI blockade impairs human erythropoiesis in vitro, and normalizes the erythroid compartment in mice with polycythemia. These results show that erythroblast-derived TFPI plays an important role in the regulation of erythropoiesis and reveal an interplay between erythroblasts and central macrophages.


Subject(s)
Erythroblasts , Erythropoiesis , GATA1 Transcription Factor , Heme , Lipoproteins , Macrophages , Polycythemia , Polycythemia/metabolism , Polycythemia/genetics , Polycythemia/pathology , Erythroblasts/metabolism , Heme/metabolism , Humans , Animals , Lipoproteins/metabolism , Macrophages/metabolism , Mice , GATA1 Transcription Factor/metabolism , GATA1 Transcription Factor/genetics , Janus Kinase 2/metabolism , Janus Kinase 2/genetics , Thrombomodulin/metabolism , Thrombomodulin/genetics , Mice, Knockout , Ferrochelatase/metabolism , Ferrochelatase/genetics , Male , MAP Kinase Signaling System , Mice, Inbred C57BL , Female
2.
RSC Med Chem ; 15(5): 1565-1577, 2024 May 22.
Article in English | MEDLINE | ID: mdl-38784474

ABSTRACT

The design, synthesis and investigation of antitumor activities of some coumarin-furo[2,3-d]pyrimidone hybrid molecules are reported. In vitro, HepG2 cells were used to investigate the cytotoxicity of 6a-n and 10a-n. The results demonstrated that coupling a furopyrimidone scaffold with coumarin through a hydrazide linker can effectively improve their synergistic anticancer activity. The coumarin-furo[2,3-d]pyrimidone combination 10a exhibited significant inhibitory activity against HepG2 cells with IC50 = 7.72 ± 1.56 µM, which is better than those of gefitinib and sorafenib. It is worth mentioning that the coumarin-furo[2,3-d]pyrimidone combination 10a showed excellent inhibition of the EGFR enzymatic activity with IC50 = 1.53 µM and 90% inhibition at 10 µM concentration. In silico investigation predicts the possibility of direct binding between the new coumarin-furo[2,3-d]pyrimidone hybrid molecules and the EGFR. The results suggest that coumarin-furo[2,3-d]pyrimidone hybrid molecules are potential antitumor agents targeting human liver cancer cells.

3.
Foods ; 13(8)2024 Apr 20.
Article in English | MEDLINE | ID: mdl-38672934

ABSTRACT

The environmental impacts of excessive phosphorus emissions (PE) have been widely discussed in recent years. This study aims to calculate and evaluate the phosphorus footprint (PF) of food thrown away in Chinese universities. Based on a nationwide survey involving 9192 university students from 29 provinces and 29 universities in China, the result reveals that the PF generated by food waste in Chinese university canteens was 3.209 Kt in 2018. Furthermore, it is found that meal satisfaction, gender, regional economic level, dietary culture, and years of education all have significant impacts on lost food PF. Our findings emphasize the importance of reducing food waste in university canteens, which plays a crucial role in ensuring food security and environmental protection.

4.
Eur J Pharm Sci ; 188: 106520, 2023 Sep 01.
Article in English | MEDLINE | ID: mdl-37423580

ABSTRACT

A series of coumarin-furo[2,3-d]pyrimidinone hybrid derivatives were synthesized, characterized by HR-MS, 1H NMR and 13C NMR. All synthesized compounds were evaluated for antiproliferative activities against hepatic carcinoma (HepG2) and cervical carcinoma (Hela) cell lines in vitro, and results shown that most of the compounds exhibited potent antitumor activity. Moreover, compound 3i, 8d and 8i were selected to induce apoptosis in HepG2 cells, and it displayed a significant concentration-dependent. Further, transwell migration assay was used to detect the most potent compound 8i, and the results revealed that 8i can significantly inhibit HepG2 cells migration and invasion. In addition, kinase activity assay showed compound 8i may be a multi-target inhibitor, which 8i has an inhibition rate of 40-20% on RON, ABL, GSK3α and so on ten different kinases at the concentration 1 µmol/L. At the same time, molecular docking studies revealed the possible binding modes of compounds 3i, 8d and 8i with kinase recepteur d'origine nantais (RON). A comparative molecular field analysis (CoMFA) model was established from 3D-QSAR study that guide us to a more bulkly and electro-positive Y group at the C-2 position of furo[2,3-d]pyrimidinone ring was preferable for the bioactivity improvement of our compounds. Our preliminary research indicated that the coumarin skeleton introducing to the furo[2,3-d]pyrimidine system had a significantly influence on the biological activities.


Subject(s)
Antineoplastic Agents , Carcinoma , Humans , Molecular Docking Simulation , Pyrimidinones/pharmacology , Antineoplastic Agents/chemistry , Coumarins/pharmacology , Molecular Structure , Drug Screening Assays, Antitumor , Structure-Activity Relationship , Cell Proliferation , Cell Line, Tumor
5.
RSC Adv ; 13(24): 16488-16511, 2023 May 30.
Article in English | MEDLINE | ID: mdl-37274408

ABSTRACT

Platinum-based anticancer drugs play a crucial role in the clinical treatment of various cancers. However, the application of platinum-based drugs is heavily restricted by their severe toxicity and drug resistance/cross resistance. Various drug delivery systems have been developed to overcome these limitations of platinum-based chemotherapy. Stimuli-responsive nanocarrier drug delivery systems as one of the most promising strategies attract more attention. And huge progress in stimuli-responsive nanocarrier delivery systems of platinum-based drugs has been made. In these systems, a variety of triggers including endogenous and extracorporeal stimuli have been employed. Endogenous stimuli mainly include pH-, thermo-, enzyme- and redox-responsive nanocarriers. Extracorporeal stimuli include light-, magnetic field- and ultrasound responsive nanocarriers. In this review, we present the recent advances in stimuli-responsive drug delivery systems with different nanocarriers for improving the efficacy and reducing the side effects of platinum-based anticancer drugs.

6.
Molecules ; 28(9)2023 Apr 25.
Article in English | MEDLINE | ID: mdl-37175110

ABSTRACT

Enantioselective labeling of important bioactive molecules in complex biological environments by artificial receptors has drawn great interest. From both the slight difference of enantiomers' physicochemical properties and inherently complexity in living organism point of view, it is still a contemporary challenge for preparing practical chiral device that could be employed in the model animal due to diverse biological interference. Herein, we introduce γ-cyclodextrin onto graphene oxide for fabricating γ-cyclodextrin and graphene oxide assemblies, which provided an efficient nanoplatform for chiral labelling of D-phenylalanine with higher chiral discrimination ratio of KD/KL = 8.21. Significantly, the chiral fluorescence quenching effect of this γ-CD-GO nanoplatform for D-phenylalanine enantiomer in zebrafish was 7.0-fold higher than L-isomer, which exhibiting real promise for producing practical enantio-differentiating graphene-based systems in a complex biological sample.


Subject(s)
Graphite , gamma-Cyclodextrins , Animals , Phenylalanine/chemistry , Graphite/chemistry , Zebrafish , Stereoisomerism
7.
ACS Appl Mater Interfaces ; 15(2): 3651-3663, 2023 Jan 18.
Article in English | MEDLINE | ID: mdl-36595485

ABSTRACT

The dispute over the effect of cavitation heat on material surface intensifies the fuzziness of cavitation erosion (CE) mechanism and limits the development of protective materials. Here, an anti-CE Al10Cr28Co28Ni34 high-entropy alloy (HEA) coating with single face-centered cubic (FCC), prepared by high-velocity oxy-fuel (HVOF) spraying technologies, was designed by inducing mechanical and thermal energy-induced behaviors to transform or counteract each other. The results showed that, on the one hand, this coating underwent the refinement of the average grain size from 1.22 to 1.02 µm, the increase in dislocation density from 1.28 × 10-10 to 1.83 × 10-10 m-2, and the martensitic transformation from FCC to body-centered cubic (BCC) under the cavitation load; on the other hand, cavitation heat could indeed induce grain growth and realize structural relaxation, which confirmed that cavitation heat acting on the material surface at temperatures theoretically above 1206.28 K also played a significant role in the CE mechanism. That is, the surface microstructure of this coating was always in a dynamic cycle during the CE process. Therefore, the coating achieved the simultaneous absorption of mechanical impact energy and thermal energy released by the bubble collapse while effectively avoiding the overenrichment of crystal defects and finally exhibited a CE resistance 2 times better than that of the classical AlCrCoFeNi HEA coating. This design concept of inducing different energy restraints or neutralization through the special response behaviors of surface microstructure provides a completely new way for the development of CE-resistant materials.

8.
Front Chem ; 10: 986908, 2022.
Article in English | MEDLINE | ID: mdl-36212057

ABSTRACT

The light-responsive nanochannel of rhodopsin gained wider research interest from its crucial roles in light-induced biological functions, such as visual signal transduction and energy conversion, though its poor stability and susceptibility to inactivation in vitro have limited its exploration. However, the fabrication of artificial nanochannels with the properties of physical stability, controllable structure, and easy functional modification becomes a biomimetic system to study the stimulus-responsive gating properties. Typically, light-responsive molecules of azobenzene (Azo), retinal, and spiropyran were introduced into nanochannels as photo-switches, which can change the inner surface wettability of nanochannels under the influence of light; this ultimately results in the photoresponsive nature of biomimetic nanochannels. Furthermore, the fine-tuning of their stimulus-responsive properties can be achieved through the introduction of host-guest systems generally combined with a non-covalent bond, and the assembling process is reversible. These host-guest systems have been introduced into the nanochannels to form different functions. Based on the host-guest system of light-responsive reversible interaction, it can not only change the internal surface properties of the nanochannel and control the recognition and transmission behaviors but also realize the controlled release of a specific host or guest molecules in the nanochannel. At present, macrocyclic host molecules have been introduced into nanochannels including pillararenes, cyclodextrin (CD), and metal-organic frameworks (MOFs). They are introduced into the nanochannel through chemical modification or host-guest assemble methods. Based on the changes in the light-responsive structure of azobenzene, spiropyran, retinal, and others with macrocycle host molecules, the surface charge and hydrophilic and hydrophobic properties of the nanochannel were changed to regulate the ionic and molecular transport. In this study, the development of photoresponsive host and guest-assembled nanochannel systems from design to application is reviewed, and the research prospects and problems of this photo-responsive nanochannel membrane are presented.

9.
Cell Rep ; 40(12): 111361, 2022 09 20.
Article in English | MEDLINE | ID: mdl-36130501

ABSTRACT

Hematopoietic stem/progenitor cells (HSPCs) are supported and regulated by niche cells in the bone marrow with an important characterization of physiological hypoxia. However, how hypoxia regulates HSPCs is still unclear. Here, we find that meteorin (Metrn) from hypoxic macrophages restrains HSPC mobilization. Hypoxia-induced factor 1α and Yin Yang 1 induce the high expression of Metrn in macrophages, and macrophage-specific Metrn knockout increases HSPC mobilization through modulating HSPC proliferation and migration. Mechanistically, Metrn interacts with its receptor 5-hydroxytryptamine receptor 2b (Htr2b) to regulate the reactive oxygen species levels in HSPCs through targeting phospholipase C signaling. The reactive oxygen species levels are reduced in HSPCs of macrophage-specific Metrn knockout mice with activated phospholipase C signaling. Targeting the Metrn/Htr2b axis could therefore be a potential strategy to improve HSPC mobilization for stem cell-based therapy.


Subject(s)
Bone Marrow Cells , Bone Marrow , Animals , Bone Marrow/metabolism , Bone Marrow Cells/metabolism , Hematopoietic Stem Cell Mobilization , Hematopoietic Stem Cells/metabolism , Hypoxia/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Nerve Tissue Proteins , Reactive Oxygen Species/metabolism , Receptors, Serotonin/metabolism , Type C Phospholipases/metabolism
10.
Front Chem ; 9: 774090, 2021.
Article in English | MEDLINE | ID: mdl-34912781

ABSTRACT

A simplefuro [2,3-d]pyrimidinone-based Schiff base FPS was synthesized via aza-Wittig reaction and structure elucidation was carried out by spectroscopic studies FT-IR, 1H NMR, and 13C NMR and mass spectrometry. FPS showed weak fluorescence emission in methanol and the selectivity of FPS to different metal ions (Mn2+, Ca2+, Fe2+, Fe3+, Mg2+, Al3+, Ba2+, Ag+, Co2+, Na+, K+, Cu2+, Zn2+, Pb2+, Bi3+) were studied by absorption and fluorescence titration. The results show that FPS has selective fluorescence sensing behavior for Zn2+ ions and the limit of detection (LOD) was calculated to be 1.19 × 10-8 mol/L. Moreover, FPS-Zn2+ acts as a metal based highly selective and sensitive new chemosensor for Cu2+ ions and the LOD was calculated to be 2.25 × 10-7 mol/L. In accordance with the results and theoretical calculations, we suspected that the binding mechanisms of FPS to Zn2+ and Cu2+ were assigned to be the cooperative interaction of Zn2+(Cu2+)-N.

11.
Pharmaceutics ; 13(7)2021 Jun 24.
Article in English | MEDLINE | ID: mdl-34202452

ABSTRACT

Cancer is one of the most devastating and ubiquitous human diseases. Conventional therapies like chemotherapy and radiotherapy are the most widely used cancer treatments. Despite the notable therapeutic improvements that these measures achieve, disappointing therapeutic outcome and cancer reoccurrence commonly following these therapies demonstrate the need for better alternatives. Among them, bacterial therapy has proven to be effective in its intrinsic cancer targeting ability and various therapeutic mechanisms that can be further bolstered by nanotechnology. In this review, we will discuss recent advances of nanotechnology-facilitated bacteria-based drug and gene delivery systems in cancer treatment. Therapeutic mechanisms of these hybrid nanoformulations are highlighted to provide an up-to-date understanding of this emerging field.

12.
Molecules ; 26(11)2021 Jun 05.
Article in English | MEDLINE | ID: mdl-34198794

ABSTRACT

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, causing approximately 17.9 million deaths annually, an estimated 31% of all deaths, according to the WHO. CVDs are essentially rooted in atherosclerosis and are clinically classified into coronary heart disease, stroke and peripheral vascular disorders. Current clinical interventions include early diagnosis, the insertion of stents, and long-term preventive therapy. However, clinical diagnostic and therapeutic tools are subject to a number of limitations including, but not limited to, potential toxicity induced by contrast agents and unexpected bleeding caused by anti-platelet drugs. Nanomedicine has achieved great advancements in biomedical area. Among them, cell membrane coated nanoparticles, denoted as CMCNPs, have acquired enormous expectations due to their biomimetic properties. Such membrane coating technology not only helps avoid immune clearance, but also endows nanoparticles with diverse cellular and functional mimicry. In this review, we will describe the superiorities of CMCNPs in treating cardiovascular diseases and their potentials in optimizing current clinical managements.


Subject(s)
Biomimetic Materials/therapeutic use , Cardiovascular Diseases/drug therapy , Cell Membrane/chemistry , Biomimetic Materials/chemical synthesis , Biomimetic Materials/chemistry , Drug Delivery Systems , Humans , Nanoparticles
13.
Entropy (Basel) ; 22(3)2020 Mar 22.
Article in English | MEDLINE | ID: mdl-33286138

ABSTRACT

To describe both the global and local characteristics of a network more comprehensively, we propose the weighted K-order propagation number (WKPN) algorithm to extract the disease propagation based on the network topology to evaluate the node importance. Each node is set as the source of infection, and the total number of infected nodes is defined as the K-order propagation number after experiencing the propagation time K. The simulation of the symmetric network with bridge nodes indicated that the WKPN algorithm was more effective for evaluation of the algorithm features. A deliberate attack strategy, which indicated an attack on the network according to the node importance from high to low, was employed to evaluate the WKPN algorithm in real networks. Compared with the other methods tested, the results demonstrate the applicability and advancement that a lower number of nodes, with a higher importance calculated by the K-order propagation number algorithm, has to achieve full damage to the network structure.

14.
Chem Asian J ; 15(7): 1025-1029, 2020 Apr 01.
Article in English | MEDLINE | ID: mdl-32073754

ABSTRACT

In the life system, the biointerface plays an important role in cell adsorption, platelet adsorption and activation. Therefore, the study of protein adsorption on the biointerface is of great significance for understanding life phenomena and treatment in vitro. In this paper, a chiral biointerface was constructed by the virtue of host-guest interaction between a water-soluble pillar[5]arene (WP5) and phenethylamine (PEA) over a gold surface for adsorption of lysozyme proteins. From the experimental results it was identified that the host-guest biointerface has a high adsorption capacity and strong chiral selectivity. Furthermotre, it was identified that the host-guest interaction plays the decisive role in the enhancement of chirality of the interface, which was much beneficial for increasing protein adsorption and amplifying the capacity of chiral discrimination. Therefore, this work provides a new idea for the construction of biointerface materials with high protein adsorption capacity and high chiral selectivity through supramolecular interaction, which will have potential applications in the fields of biosensors, biocatalysts, biomaterials.


Subject(s)
Calixarenes/chemistry , Gold/chemistry , Phenethylamines/chemistry , Proteins/metabolism , Adsorption , Biocatalysis , Biocompatible Materials , Biosensing Techniques , Muramidase/metabolism , Stereoisomerism
15.
Front Neurosci ; 14: 557095, 2020.
Article in English | MEDLINE | ID: mdl-33408603

ABSTRACT

Electroencephalograph (EEG) plays a significant role in the diagnostics process of epilepsy, but the detection rate is unsatisfactory when the length of interictal EEG signals is relatively short. Although the deliberate attacking theories for undirected brain network based on node removal method can extract potential network features, the node removal method fails to sufficiently consider the directionality of brain electrical activities. To solve the problems above, this study proposes a feature tensor-based epileptic detection method of directed brain networks. First, a directed functional brain network is constructed by calculating the transfer entropy of EEG signals between different electrodes. Second, the edge removal method is used to imitate the disruptions of brain connectivity, which may be related to the disorder of brain diseases, to obtain a sequence of residual networks. After that, topological features of these residual networks are extracted based on graph theory for constructing a five-way feature tensor. To exploit the inherent interactions among multiple modes of the feature tensor, this study uses the Tucker decomposition method to get a core tensor which is finally reshaped into a vector and input into the support vectors machine (SVM) classifier. Experiment results suggest that the proposed method has better epileptic screening performance for short-term interictal EEG data.

16.
Small ; 15(8): e1804397, 2019 02.
Article in English | MEDLINE | ID: mdl-30677228

ABSTRACT

Multiple drug resistance (MDR) of cancer cells is a major cause of chemotherapy failure. It is currently a great challenge to develop a direct and effective strategy for continuously inhibiting the P-glycoprotein (P-gp) drug pump of MDR tumor cells, thus enhancing the intracellular concentration of the therapeutic agent for effectively killing MDR tumor cells. Here, a new implantable hierarchical-structured ultrafine fiber device is developed via a microfluidic-electrospinning technology for localized codelivery of doxorubicin (DOX) and apatinib (AP). An extremely high encapsulation efficiency of ≈99% for the dual drugs is achieved through this strategy. The release of the loaded dual drugs can be controlled in a programmable release model with a rapid release of the micelles, while AP is slowly released. The sustained release of AP can continuously inhibit the P-gp drug pump of MDR tumor cells, increasing the intracellular DOX accumulation. The in vivo DOX biodistribution displays that the DOX accumulation in the tumor tissues achieves 17.82% after implanting the fiber device for 72 h, which is 6.36-fold higher than that of the intravenously injected DOX. Importantly, the fiber device shows an excellent antitumor effect on MDR tumor-bearing mice with low systemic toxicity.


Subject(s)
Doxorubicin/administration & dosage , Drug Carriers/administration & dosage , Drug Carriers/chemistry , Pyridines/administration & dosage , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Animals , Cell Line, Tumor , Doxorubicin/therapeutic use , Drug Resistance, Multiple/genetics , Drug Resistance, Neoplasm , Endothelial Cells/metabolism , Female , Humans , MCF-7 Cells , Mice , Micelles , Pyridines/therapeutic use
17.
ACS Appl Mater Interfaces ; 11(1): 1665-1671, 2019 Jan 09.
Article in English | MEDLINE | ID: mdl-30561183

ABSTRACT

The self-assembly of macroscopic droplets on interfaces has attracted much attention and shown promising potential in the field of materials as a sensing or delivery system. Herein, we reported a new strategy to construct a d-tartaric acid-functionalized pillar[5]arene (d-TP5) interface for macroscopic differentiation of histidine enantiomers. At the molecular level, it has been proved that d-TP5 has the ability to distinguish between l-Histidine and d-Histidine ( KL/ KD = 4.6). Furthermore, a functional d-TP5 surface was constructed by a click reaction and characterized by contact angle measurements and attenuated total reflection-Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. The d-TP5 surface exhibited the selective dynamic adhesion of l-His droplets on the tilted interface. It means that a d-TP5 surface can distinguish histidine enantiomers at a macrolevel. The amount of d/l-His absorbed by a d-TP5 surface and the morphology of His particles formed by removing the solvent have been investigated to prove that the self-assembly of His occurs on the d-TP5 surface. The possible mechanism has been discussed from host-guest interaction and chiral recognition. The proposed chiral material displays rapidly remarkable selectivity and is convenient to be utilized, which should be suitable for comprehending chiral recognition processing and applied to chiral recognition detection of histidine in a living body.


Subject(s)
Calixarenes/chemistry , Histidine/chemistry , Photoelectron Spectroscopy , Stereoisomerism
18.
Nat Commun ; 9(1): 2617, 2018 07 05.
Article in English | MEDLINE | ID: mdl-29976986

ABSTRACT

Inspired by glucose-sensitive ion channels, herein we describe a biomimetic glucose-enantiomer-driven ion gate via the introduction of the chiral pillar[6]arene-based host-guest systems into the artificial nanochannels. The chiral nanochannels show a high chiral-driven ionic gate for glucose enantiomers and can be switched "off" by D-glucose and be switched "on" by L-glucose. Remarkably, the chiral nanochannel also exhibited a good reversibility toward glucose enantiomers. Further research indicates that the switching behaviors differed due to the differences in binding strength between chiral pillar[6]arene and glucose enantiomers, which can lead to the different surface charge within nanochannel. Given these promising results, the studies of chiral-driven ion gates may not only give interesting insight for the research of biological and pathological processes caused by glucose-sensitive ion channels, but also help to understand the origin of the high stereoselectivity in life systems.

19.
Anal Chem ; 90(13): 8270-8275, 2018 07 03.
Article in English | MEDLINE | ID: mdl-29877691

ABSTRACT

Modulating protein selective translocation is a significant process, which has great potential for mimicking and understanding complex biological activities. As such, how to construct a nanochannel that can accomplish well gating protein transport is vital and challenge. Herein, inspired by nature, we presented a robust strategy to construct a switchable nanochannel by introducing a pH responsive binary host-guest system into a nanochannel. Benefiting from the novel design of the pillar[5]arene as gatekeeper, the functional nanochannel can well facilitate histone transport. Under pH regulation, the host-guest assembled nanochannel is capable of switching "on" and "off" to manipulate the histone translocation process. This study exemplifies the importance of molecular switch mediated protein transport in this process and provides a new theoretical model for biological research, which will open a new avenue for better understanding of some physiological and pathological behaviors.


Subject(s)
Biomimetics/methods , Calixarenes/chemistry , Nanotechnology/methods , Hydrogen-Ion Concentration , Protein Transport
20.
Sensors (Basel) ; 18(4)2018 Apr 01.
Article in English | MEDLINE | ID: mdl-29614778

ABSTRACT

Sky detection plays an essential role in various computer vision applications. Most existing sky detection approaches, being trained on ideal dataset, may lose efficacy when facing unfavorable conditions like the effects of weather and lighting conditions. In this paper, a novel algorithm for sky detection in hazy images is proposed from the perspective of probing the density of haze. We address the problem by an image segmentation and a region-level classification. To characterize the sky of hazy scenes, we unprecedentedly introduce several haze-relevant features that reflect the perceptual hazy density and the scene depth. Based on these features, the sky is separated by two imbalance SVM classifiers and a similarity measurement. Moreover, a sky dataset (named HazySky) with 500 annotated hazy images is built for model training and performance evaluation. To evaluate the performance of our method, we conducted extensive experiments both on our HazySky dataset and the SkyFinder dataset. The results demonstrate that our method performs better on the detection accuracy than previous methods, not only under hazy scenes, but also under other weather conditions.

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