Ultrathin layers of 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) Oxidized Cellulose Nanofibers (TOCNF) embedded with Graphene Oxide nanosheets (GOs) in different ratios were built,
via
the blade ...coating technique, on a polyvinylidene difluoride (PVDF) substrate to obtain superior membranes for separating water pollutants from aqueous media. Cellulose nanofiber-graphene oxide hybrid materials have shown a great potential for water purification due to their active microporous structure with extended areas rich in negatively charged carboxyl functional groups capable of adsorbing positively charged contaminants efficiently. In contrast to the pristine free-standing TOCNF films, which are completely impermeable, the ultrathin (68 nm thick) hybrid coating with a 100 : 1 TOCNF : GO ratio showed a stable water permeability (816 ± 3.4 L m
−2
h
−1
bar
−1
) higher than that of common polymeric membranes, and a very efficient size selectivity during filtration of water contaminated by various types of dyes. The membranes had high retention efficiency (82-99%) for dyes with hydrated radii greater than 0.5 nm due to the favorable combination of electrostatic/hydrophobic interactions with the hybrid matrices and steric entrapment controlled by the pore size. This was confirmed by theoretical calculations that revealed both the structure and dynamic behavior of the dyes in the complex environment of the membranes.
Nanocellulose-graphene oxide ultrathin coatings for water purification membranes with excellent swelling resistance, permeability and dyes retention are presented.
Respiratory syncytial virus (RSV) is a major cause of serious lower respiratory tract infections in infants, children, and older persons. Currently, the only approved anti-viral chemotherapeutic drug ...for RSV treatment is ribavirin aerosol; however, its significant toxicity has led to restricted clinical use. In a previous study, we developed various benzimidazole derivatives against RSV. In this study, we synthesised 3-azide substituted furoxazine-fused benzimidazole derivatives by sulfonylation and azide substitution of the 3-hydroxyl group of the furoxazine-fused benzimidazole derivatives. Subsequently, a series of 3-(1,2,3-triazol-1-yl)-substituted furoxazine-fused benzimidazole derivatives were synthesised using the classical click reaction. Biological evaluations of the target compounds indicated that compound 4a-2 had higher activity against RSV (EC50 = 12.17 μM) and lower cytotoxicity (CC50 = 390.64 μM). Compound 4a-2 exerted anti-viral effects against the RSV Long strain by inhibiting apoptosis and the elevation of reactive oxygen species (ROS) and inflammatory factors caused by viral infection in vitro. Additionally, the clinical symptoms of the virus-infected mice were markedly relieved, and the viral load in the lung tissues was dramatically decreased. The biosafety profile of compound 4a-2 was also favourable, showing no detectable adverse effects on any of the major organs in vivo. These findings underscore the potential of compound 4a-2 as a valuable therapeutic option for combating RSV infections while also laying the foundation for further research and development in the field.
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•A series of 3-(1,2,3-triazol-1-yl)-substituted furooxazine-substituted benzimidazole derivatives were synthesised.•Compound 4a-2 exhibited significant anti-respiratory syncytial virus activity.•The antiviral activity is exerted through inhibition of apoptosis, reduction of reactive oxygen species levels, and interference with cytokine storms.
The aim of this study was to develop a fundamental understanding of the adsorption behavior of metal ions on cellulose surfaces using experimental techniques supported by computational modeling, ...taking Ag(I) as an example. Force interactions among three types of cellulose microspheres (native cellulose and its derivatives with sulfate and phosphate groups) and the silica surface in AgNO3 solution were studied with atomic force microscopy (AFM) using the colloidal probe technique. The adhesion force between phosphate cellulose microspheres (PCM) and the silica surface in the aqueous AgNO3 medium increased significantly with increasing pH while the adhesion force slightly decreased for sulfate cellulose microspheres (SCM), and no clear adhesion force was observed for native cellulose microspheres (CM). The stronger adhesion enhancement for the PCM system is mainly attributed to the electrostatic attraction between Ag(I) and the negative silica surface. The observed force trends were in good agreement with the measured zeta potentials. The scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analyses confirmed the presence of silver on the surface of cellulose microspheres after adsorption. This study showed that PCM with a high content of phosphate groups exhibited a larger amount of adsorbed Ag(I) than CM and SCM and possible clustering of Ag(I) to nanoparticles. The presence of the phosphate group and a wavenumber shift of the P–OH vibration caused by the adsorption of silver ions on the phosphate groups were further confirmed with computational studies using density functional theory (DFT), which gives support to the above findings regarding the adsorption and clustering of Ag(I) on the cellulose surface decorated with phosphate groups as well as IR spectra.
The text in a low-resolution (LR) image is usually hard to read. Super-resolution (SR) is an intuitive solution to this issue. Existing single image super-resolution (SISR) models are mainly trained ...on synthetic datasets whose LR images are obtained by performing bicubic interpolation or gaussian blur on high-resolution (HR) images. However, these models can hardly generalize to practical scenarios because real-world LR images are more difficult to super-resolve. The newly proposed TextZoom dataset is the first dataset for real-world text image super-resolution. We propose a new model termed TSRGAN trained on this dataset. First, a discriminator is designed to prevent the SR network from generating over-smoothed images. Second, we introduce triplet attention into the SR network for better representational ability. Moreover, besides L2 loss and adversarial loss, wavelet loss is incorporated to help reconstruct sharper character edges. Since TextZoom provides text labels, the recognition accuracy of scene text recognition (STR) model can be used to evaluate the quality of SR images. It can reflect the performance of text image SR models better than traditional SR evaluation metrics such as PSNR and SSIM. Comprehensive experiments show the superiority of our TSRGAN. Compared with the state-of-the-art method, the proposed TSRGAN improves the average recognition accuracy of ASTER, MORAN and CRNN by 0.8%, 1.5% and 3.2% on TextZoom respectively.
A comprehensive study of a new planar-type balun prototype is presented in this paper for application in the design of balun bandpass filters (BPFs) with widely used open-type resonators. The ...proposed balun is in general composed of two identical back-to-back quarter-wavelength (λ/4) coupled line sections. The design concept originates from the analysis of the standing wave pattern on a half-wavelength (λ/2) open-circuited transmission line. After an intuitive illustration is given, its working principle is presented to validate the feasibility of the proposed balun. Afterward, two types of the coupled line prototypes are analyzed to implement the proposed balun with filtering response, whereas a basic rule is given to realize the transmission zeros. To further demonstrate the validity of the proposed balun prototype, two practical balun BPFs with common dual-mode resonators are designed and fabricated. As expected, transmission zeros are generated near the desired passband of our presented balun filters, thereby improving their frequency selectivity. Both simulated and measured results exhibit good filtering and balun performance.
Biofluorescence imaging enables real-time, visual detection of biomolecules, cells and tissues/organs on a three-dimensional scale. And it can track the various physiological processes of the ...organism and understand the relationship between biomolecules and their structure and function. Near-infrared imaging has a high temporal and spatial resolution, low damage to biological tissues and strong penetrating capability, good sensitivity and low background fluorescence interference, which are the advantages of imaging technology. However, at present, the deficiencies of fluorescent groups include relatively low fluorescence quantum yield and unfavorably short emission wavelength in the NIR region, especially in the second near-infrared window (1000–1700 nm, NIR-II). In the in vivo processes and applications of NIR fluorescence materials, biocompatibility, fluorescence quantum efficiency and adjustability of excitation and emission wavelengths in the NIR region should be considered. Therefore, organic polymeric materials are ideal for the construction of the NIR fluorescence probe. In this review, the synthesis and applications of NIR fluorescence polymers were summarized and the future trend has prospected as well.
A new design method of microstrip wideband balun bandpass filter (BPF) is presented in this letter. By utilizing the standing-wave property of voltage distribution along an open-circuited ...half-wavelength <inline-formula> <tex-math notation="LaTeX">(\lambda/2)</tex-math></inline-formula> microstrip transmission line, the out-of-phase signals can be obtained at two output ports of a balun. Meanwhile, proper coupling topologies between the open-circuited <inline-formula> <tex-math notation="LaTeX">\lambda/2</tex-math></inline-formula> microstrip transmission line and the multi-mode resonators are selected to achieve a balun BPF with both characteristics of balance performance and wideband filtering properties. To validate our proposal, a balun BPF operating at 1 GHz with a 3 dB FBW of 30% is designed, fabricated, and measured. Both the simulation and measurement results of the designed balun BPF are provided with a good agreement. Results indicate that this balun BPF exhibits not only a high selectivity filtering performance with two common transmission zeros (Tzs) of <inline-formula> <tex-math notation="LaTeX">{\mathrm S}_{21}</tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">{\mathrm S}_{31}</tex-math></inline-formula> outside the passbands, but also a good balance performance with 0.5 dB amplitude imbalance and 5 <inline-formula> <tex-math notation="LaTeX">^{\circ}</tex-math></inline-formula> phase imbalance.
Scene text image super‐resolution (STISR) has recently received considerable attention. Existing STISR methods are applicable to the situation that all the LR‐HR pairs are available. However, in ...real‐world scenarios, it is difficult and expensive to collect ground‐truth HR labels and align them with LR images, and thus it is essential to find a way to implement weakly supervised learning. We investigate the STISR problem in the situation that only a subset of HR labels is available and design a weak supervision framework using coarse‐grained text labels named TLWSR, which combines incomplete supervision and inexact supervision. Specifically, a lightweight text recognition network and connectionist temporal classification loss are used to guide the super‐resolution of text images during training. Extensive experiments on the benchmark TextZoom demonstrate that TLWSR generates distinguishable text images and exceeds the fully supervised baseline TSRN in boosting text recognition accuracywith only 50% HR labels available. Meanwhile, TLWSR can be applied to different super‐resolution backbones and significantly improves their performance. Furthermore, TLWSR shows good generalization capability to low‐quality images on scene text recognition benchmarks, which verifies the effectiveness of this framework. To the authors' knowledge, this is the first work exploring the problem of STISR in weakly supervised scenarios.
To reduce dependencies on expensive and rare paired real‐world text images, a novel weak supervision framework named TLWSR is designed. Given a subset of HR labels in the training set, text recognition network CRNN and CTC loss with text labels are employed to assist in the super‐resolution of text images. To the authors' knowledge, this is the first work exploring the problem of STISR in weakly supervised scenarios.
•Two new fluorescent sensors were synthesized only containing two steps.•The sensor displayed a high selectivity and high sensitivity for N2H4.•The single crystal X-ray and mass data demonstrate the ...proposed mechanism base on excited state intramolecular proton transfer (ESIPT).•The sensors were successfully applied to detect N2H4 in gas state by coating on filter paper through volatilization of N2H4.•The sensors were applied for imaging intracellular N2H4 by using Hela cells.
Two novel fluorescent chemosensors based on the benzothiazole derivative were designed, synthesized, and used as a selective hydrazine sensor in a DMSO and HEPES buffer mixture (10mM, pH 7.4)(9:1, v/v). The probes displayed high sensitivity and selectivity of hydrazine after adding more than 18 types of analyte. The application of the probes in detecting N2H4 in living cells and in the gas state was also investigated. The single crystal X-ray study of the fluorescent sensor both before and after treatment with N2H4 confirmed the proposed mechanism based on excited state intramolecular proton transfer (ESIPT).
Developing a convenient, efficient and eco-friendly approach for the recovery of U(VI) ion is a key measure to solve the environmental problems arising from the utilization of nuclear energy. Herein, ...the high efficiency of uranium extraction is realized by the piezo property of perovskite BaTiO3, revealing the intrinsically morphological engineering effect on the piezocatalytic performance. Especially, BaTiO3 nanowires (BTO NWs) exhibit not only an excellent piezocatalytic activity with U(VI) extraction rate of 96.8% in a UO2(NO3)2 aqueous solution compared to 71.3% of BaTiO3 nanoparticles (BTO NPs), but also a promising piezocatalyst for U extraction in a real U-mining wastewater with various pH ranges. Piezo response force microscopy and finite elemental simulation show that the piezo response of BTO NWs is much higher than BTO NPs. Additionally, some factors (pH, various ions, different powers) are explored on piezocatalytic efficiency for U(VI) extraction. The results from electron spin resonance and the charge/radical capture experiments confirm that the active species (e-, •O2-, •OH) stemmed from the piezo induction of BTO NWs and BTO NPs in the piezocatalytic U(VI) reduction process. The present work reveals the structure-performance correlation during piezocatalysis and highlights the crucial role of piezocatalysis in dealing with environmental problems.
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•Nanowire/nanoparticle-like BaTiO3 was fabricated via a hydrothermal reaction.•Morphology-induced piezoelectric property was revealed.•Piezoelectricity of BaTiO3 enhanced by morphology boosted the U(VI) extraction.•Various factors on piezocatalytic performance were explored for U(VI) extraction.•Active species were verified and the piezocatalytic mechanism was proposed.
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