- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System
摘要： Quinoxaline-based novel acid-responsive probe Q1 was designed on the basis of a conjugated donor-acceptor (D-A) subunit. Q1 shows colorimetric and fluorometric changes through protonation and deprotonation in dichloromethane. With the addition of the trifluoroacetic acid (TFA), UV-vis absorption spectral changes in peak intensity of Q1 was observed. Moreover, the appearance of a new peaks at 284 nm 434 nm in absorption spectra with the addition of TFA indicating protonation of quinoxaline nitrogen and form Q1.H+ and Q1.2H+. The emission spectra display appearance of new emission peak at 515 nm. The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations. Upon addition of triethylamine (TEA) the fluorescence emission spectral changes of Q1 are found to be reversible. Q1 shows color changes from blue to green in basic and acidic medium, respectively. The paper strip test was developed for making Q1 a colorimetric and fluorometric indicator.
关键词： proton sensor,quinoxaline,fluorescent,colorimetric,reversible sensor
更新于2025-11-19 16:46:39
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Ultrasonication-assisted synthesis of CsPbBr <sub/>3</sub> and Cs <sub/>4</sub> PbBr <sub/>6</sub> perovskite nanocrystals and their reversible transformation
摘要： We demonstrate an ultrasonication-assisted synthesis without polar solvent of CsPbBr3 and Cs4PbBr6 perovskite nanocrystals (PNCs) and their reversible transformation. The as-prepared CsPbBr3 PNCs and Cs4PbBr6 PNCs exhibit different optical properties that depend on their morphology, size, and structure. The photoluminescence (PL) emission and quantum yield (QY) of the CsPbBr3 PNCs can be tuned by changing the ultrasound power, radiation time, and the height of the vibrating spear. The optimized CsPbBr3 PNCs show a good stability and high PL QY of up to 85%. In addition, the phase transformation between CsPbBr3 PNCs and Cs4PbBr6 PNCs can be obtained through varying the amount of oleylamine (OAm) and water. The mechanism of this transformation between the CsPbBr3 PNCs and Cs4PbBr6 PNCs and their morphology change are studied, involving ions equilibrium, anisotropic growth kinetics, and CsBr-stripping process.
关键词： ultrasonication,polar-solvent-free,CsPbBr3 PNCs,Cs4PbBr6 PNCs,reversible transformation
更新于2025-11-19 16:46:39
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A photo-switchable supramolecular hyperbranched polymer with aggregation-induced emission based on host-guest interaction
摘要： In this work, we report a simple strategy by mixing a coumarin appended tetraphenylethylene derivative (TPEC) and γ-cydodextrin(γ-CD) in aqueous solution, based on the host-guest interaction between TPEC and γ-CD to construct a dual-modality supramolecular hyperbranched polymer. The host-guest interaction between γ-CD and TPEC efficiently restricted the intramolecular rotation and the non-radiative relaxation channel, minimizing energy loss, thereby resulting in the strong emission of TPEC in dilute solution. Moreover, we achieved the conversion between non-covalent supramolecular polymers and its corresponding covalent supramolecular hyperbranched polymers under the irradiation of UV light, which can be reversibly controlled through the irradiation at the wavelengths of 254 nm and 365 nm. Furthermore, both non-covalent supramolecular hyperbranched polymers and covalent supramolecular hyperbranched polymers can self-assemble into spherical structures. This methodology provides a new idea for exploring a new type of supramolecular hyperbranched polymers with aggregation-induced emission.
关键词： supramolecular polymer,reversible,host-guest interaction,photo-switchable,dual-modality
更新于2025-09-23 15:23:52
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Design of a novel reversible structure for full adder/subtractor in quantum-dot cellular automata
摘要： Complementary Metal Oxide Semiconductor (CMOS) technology uses voltage levels for binary computation, whereas Quantum Dot-Cellular Automata (QCA) uses free electron location in the QCA cell for logic evaluation. This technology suggests very low power consumption, high speed and very dense structure for performing any logical circuit. Reversible logic is best mechanism with low power and high speed in circuit designing. Reversible gates have N input and N output lines that input lines mapped with output lines one by one. In this paper, a novel design of Reversible Full adder/subtractor with minimum number of cells has been proposed. QCADesigner software has been used to simulate the proposed design.
关键词： Quantum-dot Cellular Automata (QCA),Reversible Full adder/subtractor
更新于2025-09-23 15:23:52
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Light-Inducible Exosome-Based Vehicle for Endogenous RNA Loading and Delivery to Leukemia Cells
摘要： Exosomes are a novel and promising drug delivery platform because of their endogenous origin, stability, biocompatibility, and other unique features. As the efficient loading and delivery of long RNA to target cells for therapeutic purposes remains challenging, a new exosome-based RNA delivery system is proposed using a controllable RNA enrichment and releasing protocol. The system employs RNA aptamer–protein interactions and reversible light-inducible protein–protein interaction modules by remolding exosome producer cells. Endogenous microRNA 21 (miR-21) sponges, inhibitors of miR-21, are successfully enriched on the plasma membrane and are sorted into exosomes by the biogenesis of the exosomes. The loading capacity of miR-21 sponges is enhanced by 14-fold in the light-inducible loading system. In addition, targeted delivery of miR-21 to leukemia cells is achieved by modifying exosomes with the cholesterol-conjugated aptamer AS1411, resulting in significant cell apoptosis by blocking the function of miR-21 in leukemia cells. This work provides an exosome-based light-inducible vehicle to efficiently load and deliver long endogenous RNA, which can enable more RNA-based therapeutics for personalized cancer medicine.
关键词： miRNA sponge,leukemia,RNA enrichment,exosomes,reversible light-inducible vehicles,aptamers
更新于2025-09-23 15:23:52
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Lossless Information Hiding in Images || Lossless Information Hiding in JPEG- and JPEG2000-Compressed Images
摘要： This chapter focuses on the lossless information hiding in JPEG and JPEG2000 images. For JPEG images, seven typical methods including two schemes from the authors were introduced. For the first five schemes, we introduced the basic ideas, whereas for the schemes from the authors, we provided a detailed introduced detail with experimental results. In the first method of ours, our high-capacity reversible JPEG-to-JPEG data hiding scheme is introduced. Through lowering certain quantization table entries and lifting corresponding quantized DCT coefficients, space is made for embedding data. Using the proposed embedding strategy, our scheme can achieve high embedding capacity and keep the distortion introduced by embedding very low; meanwhile the original cover JPEG image can be restored after the secret data are extracted. Experiments results demonstrate that the proposed scheme maintains the image quality of a stego JPEG image when the embedding capacity is high. Besides, the file size after embedding with not too huge data is acceptable. Compared with Chang et al.’s method and Xuan et al.’s method, the proposed method is superior in terms of the image quality, hiding capacity, and file size. Our scheme is very practical for image files stored and transmitted in the JPEG format. In the second method of ours, a lossless data hiding scheme with file size preservation is proposed. Through analyzing the code space and the statistics of both used and unused VLCs, we find there is still potential free space in the JPEG bitstream that can be explored to hide data. The best of unused VLCs are made and mapped to the used VLCs in specific mapping manners. The proposed scheme embeds data into the VLC codes and whatever mapped VLCs are present are not changed, therefore the image content after data hiding is exactly the same as the original one. Experimental results demonstrate that the proposed scheme can reach better performance irrespective of whether file size preservation is required or not. For JPEG2000 images, we first introduced two schemes from the literature, and then introduce our scheme. In our scheme, high-frequency subbands of the cover image are divided into blocks. In each block, a new histogram shifting method is applied to the histogram of the block for embedding data. Every coefficient that is associated with the peak point embeds 2 bits of data. In addition, we shift the histogram to the left or right adaptively according to a direction sign. Experimental results show that the proposed scheme has high embedding capacity and good invisibility of hidden data.
关键词： steganography,histogram shifting,data hiding,quantization table,reversible watermarking,JPEG2000,Lossless information hiding,JPEG,VLC mapping,DCT coefficients
更新于2025-09-23 15:23:52
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Preparation of a star-shaped copolymer with porphyrin core and four PNIPAM-b-POEGMA arms for photodynamic therapy
摘要： A series of thermosensitive star-shaped copolymers THPP-(PNIPAM-b-POEGMA)4 with 5, 10, 15,20-tetrakis-(4-hydroxyphenyl)-21H,23H-porphyrin (THPP) core and four poly(N-isopropylacrylamide)-b-poly(oligo(ethylene glycol) mono methyl ether methacrylate) (PNIPAM-b-POEGMA) arms were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The low critical solution temperatures (LCSTs) of THPP-(PNIPAM-b-POEGMA)4 with different molecular weights were 37.5 °C, 39.9 °C and 41.9 °C respectively, which depending on the hydrophilic POEGMA contents of copolymers. The micellar structures of copolymers could be formed above the LCSTs. The MTT study indicated that THPP-(PNIPAM-b-POEGMA)4 and THPP showed no significant cytotoxicity toward HeLa cells and L929 cells. And THPP-(PNIPAM-b-POEGMA)4 under light irradiation showed photodynamic activity which photo-toxicity toward HeLa cells was stronger than THPP.
关键词： Porphyrin,Thermosensitivity,Reversible addition-fragmentation chain transfer (RAFT),THPP-(PNIPAM-b-POEGMA)4,Photodynamic therapy
更新于2025-09-23 15:22:29
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Design and analysis of multi-hexagonal reversible encoder using photonic crystals
摘要： In this paper, a 4 × 2 reversible encoder with hexagonal lattice has been designed using two-dimensional photonic crystals with non-linear refractive index. In order to demonstrate the working of the encoder, we have used the multi-hexagonal shaped structure arranged in parallel with appropriate inclination to get the desired output. During its functionality as an encoder, more than 98% of the power is coupled at the output port to obtain logic 1 and less than 17.2% of the power is coupled for obtaining logic 0. In addition, during its functionality as a reversible encoder, the logic 1 and logic 0 correspond to 97.5% and 15.1%, respectively. The proposed encoder provides an improved contrast ratio of 12.18? dB and 11.5?dB for logical states of 01 and 10, respectively.
关键词： Photonic integrated circuits,Optical reversible encoder,Photonic crystal,Photonic band gap
更新于2025-09-23 15:21:21
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[Lecture Notes in Computer Science] Pattern Recognition and Computer Vision Volume 11258 (First Chinese Conference, PRCV 2018, Guangzhou, China, November 23-26, 2018, Proceedings, Part III) || Face Detection and Encryption for Privacy Preserving in Surveillance Video
摘要： A number of techniques have recently been proposed for privacy preserving in video surveillance. Most of them are irreversible or have interference effect to the observation and recognition of human activities. In this paper, we address these issues by developing an effective method including face detection and encryption. In face detection, skin-color based approach fusing with fuzzy clustering is produced to detect facial candidates coarsely, and then we re?ne face by using SVM classi?er. In face encryption, a reversible hybrid encryption (decryption) scheme based on spatial and value scrambling models is proposed. Simulation results verify the proposed mechanism can effectively detect and obscure faces while leaving the activities comprehensible and has high key sensibility for reducing the probability of attacking.
关键词： Privacy preserving,Reversible,Video surveillance,Face detection,Face encryption
更新于2025-09-23 15:21:01
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photoresponsive Soft Materials Based on Reversible Proton Transfer
摘要： Proton transfer is one of the most fundamental processes in nature and numerous chemical, material, and biological processes are driven by proton transfer. For example, biological systems use proton gradient as an energy form to synthesize ATP for their biological functions; many organic reactions are catalyzed by Bronsted acids; and many materials have pH‐sensitive properties. Proton transfer is also involved in different aspects of polymer science relative to preparation, property, and processing. For example, cationic polymerizations can be initiated by proton transfer from a strong acid to a monomer. It has been reported that many polymers are sensitive to the pH (proton concentration) of the environment, and their properties including mechanical, geometrical, electric, optical, and magnetic properties, change with pH due to proton transfer between the polymers and the environment. Polymers with acid‐labile bonds have been studied for drug delivery; and photoinduced cationic polymerization using photoacid‐generators (PAGs) has been applied to photolithography.
关键词： Proton transfer,photoacid,fragrant‐releasing polymers,photoresponsive nanoparticles,photochromic materials,photoresponsive polymers,reversible
更新于2025-09-23 15:21:01