Molecular design and architectonics towards film-based fluorescent sensing.

The past few decades have witnessed encouraging progress in the development of high-performance film-based fluorescent sensors (FFSs) for detecting explosives, illicit drugs, chemical warfare agents (CWAs), and hazardous volatile organic chemicals (VOCs), among others. Several FFSs have transitioned from laboratory research to real-world applications, demonstrating their practical relevance. At the heart of FFS technology lies the sensing films, which play a crucial role in determining the analytes and the resulting signals. The selection of sensing fluorophores and the fabrication strategies employed in film construction are key factors that influence the fluorescence properties, active-layer structures, and overall sensing behaviors of these films. This review examines the progress and innovations in the research field of FFSs over the past two decades, focusing on advancements in fluorophore design and active-layer structural engineering. It underscores popular sensing fluorophore scaffolds and the dynamics of excited state processes. Additionally, it delves into six distinct categories of film fabrication technologies and strategies, providing insights into their advantages and limitations. This review further addresses important considerations such as photostability and substrate effects. Concluding with an overview of the field's challenges and prospects, it sheds light on the potential for further development in this burgeoning area.

Reducing annotating load: Active learning with synthetic images in surgical instrument segmentation.

Accurate instrument segmentation in the endoscopic vision of minimally invasive surgery is challenging due to complex instruments and environments. Deep learning techniques have shown competitive performance in recent years. However, deep learning usually requires a large amount of labeled data to achieve accurate prediction, which poses a significant workload. To alleviate this workload, we propose an active learning-based framework to generate synthetic images for efficient neural network training. In each active learning iteration, a small number of informative unlabeled images are first queried by active learning and manually labeled. Next, synthetic images are generated based on these selected images. The instruments and backgrounds are cropped out and randomly combined with blending and fusion near the boundary. The proposed method leverages the advantage of both active learning and synthetic images. The effectiveness of the proposed method is validated on two sinus surgery datasets and one intraabdominal surgery dataset. The results indicate a considerable performance improvement, especially when the size of the annotated dataset is small. All the code is open-sourced at: https://github.com/HaonanPeng/active_syn_generator.

High-entropy relaxor ferroelectric ceramics for ultrahigh energy storage.

Dielectric ceramic capacitors with ultrahigh power densities are fundamental to modern electrical devices. Nonetheless, the poor energy density confined to the low breakdown strength is a long-standing bottleneck in developing desirable dielectric materials for practical applications. In this instance, we present a high-entropy tungsten bronze-type relaxor ferroelectric achieved through an equimolar-ratio element design, which realizes a giant recoverable energy density of 11.0 J·cm-3 and a high efficiency of 81.9%. Moreover, the atomic-scale microstructural study confirms that the excellent comprehensive energy storage performance is attributed to the increased atomic-scale compositional heterogeneity from high configuration entropy, which modulates the relaxor features as well as induces lattice distortion, resulting in reduced polarization hysteresis and enhanced breakdown endurance. This study provides evidence that developing high-entropy relaxor ferroelectric material via equimolar-ratio element design is an effective strategy for achieving ultrahigh energy storage characteristics. Our results also uncover the immense potential of tetragonal tungsten bronze-type materials for advanced energy storage applications.

Konjac glucomannan-based highly antibacterial active films loaded with thyme essential oil through bacterial cellulose nanofibers/Ag nanoparticles stabilized Pickering emulsions.

The aim of this study was to develop novel konjac glucomannan (KGM)-based highly antibacterial active films, where five types of films were prepared and compared. The microstructure results showed that KGM-based films loaded with thyme essential oil (TEO) through bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) stabilized Pickering emulsions (Type V films) displayed the smoothest surface and the most evenly dispersed TEO droplets as compared with the other four types of films. Moreover, Type V films showed the highest contact angle value (86.28°), the best thermal stability and mechanical properties. Furthermore, Type V films presented the highest total phenol content (13.23 mg gallic acid equivalent/g film) and the best antioxidant activity (33.96 %) as well as the best sustained-release property, thus showing the best antibacterial activity, which was probably due to that BCNs/Ag nanoparticles and TEO displayed a synergistic effect to some extent. Consequently, Type V film-forming solutions were used as coatings for tangerines. The results showed that the tangerines treated with Type V coatings displayed excellent fresh-keeping properties. Therefore, the coatings, KGM-based film-forming solutions loaded with TEO through BCNs/Ag nanoparticles stabilized Pickering emulsions, have great potential for the preservation of fruits and vegetables.

Synthesis of bacterial cellulose nanofibers/Ag nanoparticles: Structure, characterization and antibacterial activity.

The aim of this study was to compare the characterization of bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) obtained by three different pretreatment methods of BCNs (no pretreatment, sodium hydroxide activation pretreatment and TEMPO-mediated oxidation pretreatment), which were recoded as N-BCNs/Ag nanoparticles, A-BCNs/Ag nanoparticles and O-BCNs/Ag nanoparticles, respectively. The results of scanning electron microscopy and transmission electron microscopy showed the prepared Ag nanoparticles by three different pretreatment methods were spherical and dispersed on the surface of BCNs, while the Ag nanoparticles in O-BCNs/Ag nanoparticles displayed the smallest diameter with a value of 20.25 nm and showed the most uniform dispersion on the surface of BCNs. The ICP-MS result showed O-BCNs/Ag nanoparticles had the highest content of Ag nanoparticles with a value of 2.98 wt%, followed by A-BCNs/Ag nanoparticles (1.53 wt%) and N-BCNs/Ag nanoparticles (0.84 wt%). The cytotoxicity assessment showed that the prepared BCNs/Ag nanoparticles were relatively safe. Furthermore, the O-BCNs/Ag nanoparticles had the best antioxidant and antibacterial activities as compared with the other two types of BCNs/Ag nanoparticles, where O-BCNs/Ag nanoparticles destroyed the structure of bacterial cell membranes to lead the leakage of intracellular components. This study showed that O-BCNs/Ag nanoparticles as antibacterial agents have great potential in food packaging.

Recent Advances in Construction Strategies for Fluorescence Sensing Films.

A year ago, film-based fluorescent sensors (FFSs) were recognized in the "IUPAC Top Ten Emerging Technologies in Chemistry 2022" due to their extensive application in detecting hidden explosives, illicit drugs, and volatile organic compounds. These sensors offer high sensitivity, specificity, immunity to light scattering, and noninvasiveness. The core of FFSs is the construction of high-performance fluorescent sensing films, which are dependent on the processes of "energy transfer" and "mass transfer" in the active layer and involve complex interactions between sensing molecules and analytes. This Perspective focuses on the latest strategies in constructing these films, emphasizing the design of sensing molecules with various innovative features and structures that enhance the mass transfer efficiency. Additionally, it discusses the ongoing challenges and potential advancements in the field of FFSs.

Experimental Study of Skin Contraction Induced by Bipolar Radiofrequency.

Background: Facial skin relaxation has become an important part in solving the problem of facial rejuvenation. Minimally invasive or noninvasive skin-tightening procedures have become a trend for facial rejuvenation. Bipolar radiofrequency (RF) is a new option for treating skin relaxation and is more effective than noninvasive surgery without surgical incision. Objective: To explore the effect of different bipolar RF powers on the area of the original box, changes of skin and subcutaneous tissue thickness and numbers of fibroblasts in rabbits. Design: The research team performed an animal study. Setting: This study took place in Affiliated Hospital of Nanjing University of Chinese Medicine. Participants: Eighteen common-grade adult New Zealand rabbits (female, 2.5-3.0 kg). Methods: Bipolar radiofrequency therapy was given to a girl rabbit on the left side of the treatment area. Standard HE and Masson staining were performed to assess the pathological changes, area of the original box and the number of fibroblasts in skin and subcutaneous tissues. Outcome Measures: (1) The area of the original box, changes of skin and subcutaneous tissue thickness, and numbers of fibroblasts under different bipolar RF temperatures or under different bipolar RF powers immediately after surgery, 1 month after surgery and 3 months after surgery were observed. (2) Standard HE and Masson staining results. Results: Under the condition of certain instrument power, at 36de 38d and 40nd the area of the original box shrank to different degrees immediately after surgery (16.54±0.37, 17.78±0.03, 17.19±0.01), 1 month after surgery (16.59±0.31, 17.82±0.01, 18.34±0.30) and 3 months after surgery (16.89±0.12, 18.16±0.14, 19.23±0.32) compared with that before surgery (P < .05). Under specific temperature conditions, at 16 W, 18 W, 20 W, and 22 W, the area of the original box shrank to different degrees immediately after surgery (16.40±0.49, 15.55±0.57, 17.54±0.12, 16.19±0.27), 1 month after surgery (16.88±0.12, 17.46±0.02, 18.05±0.35, 19.41±0.08) and 3 months after surgery (19.09±1.01, 18.30±0.69, 20.00±0.29, 21.20±0.90) compared with that before surgery (P < .05). When the power was fixed, the thickness of skin and subcutaneous tissue decreased immediately after surgery (6.7, 6.8, 7), 1 month after surgery (6, 6.1, 6.3) and 3 months after surgery (6.4, 6.5, 6.2) at different temperatures (P < .05). When the temperature was fixed, the thickness of skin and subcutaneous tissue decreased immediately after surgery (6.1, 6.08, 6.03), 1 month after surgery (6.2, 6.15, 6.13), and 3 months after surgery (6.2, 6.23, 6.03) under different powers (P < .05). Under the condition of certain instrument power, at 36de 38d and 40n, the number of fibroblasts increased to different degrees immediately after surgery (26.54±2.37, 30.78±3.03, 37.19±4.01), 1 month after surgery (28.59±2.31, 34.82±3.01, 40.34±4.30), and 3 months after surgery (30.89±0.12, 38.16±0.14, 42.23±0.32) compared with that before surgery, and all were statistically significant (P < .05). Under specific temperature conditions, at 16 W, 18 W, 20 W, and 22 W, the number of fibroblasts increased to different degrees immediately after surgery (28.29±2.49, 30.97±3.57, 38.74±3.12, 45.68±4.27), 1 month after surgery (30.88±3.12, 32.46±4.02, 41.05±0.35, 50.41±0.08), and 3 months after surgery (29.99±2.01, 33.30±2.69, 39.00±3.29, 23.20±2.90) compared with that before surgery, and all were statistically significant (P < .05). Conclusions: Our study clarifies that bipolar RF can decrease the skin and subcutaneous tissue thickness and increase the numbers of fibroblasts at the temperature of 36°C, 38°C, and 40°C and frequency of 16-22 W, which has a therapeutical effect on skin contraction. Our study might effectively improve the skin slack of patients, and the postoperative maintenance rate is high, and will not cause obvious complications. This study may provide a theoretical direction for clinicians to tighten the skin of patients using bipolar RF.

The Development of Highly pH-Sensitive Bacterial Cellulose Nanofibers/Gelatin-Based Intelligent Films Loaded with Anthocyanin/Curcumin for the Fresh-Keeping and Freshness Detection of Fresh Pork.

The aim of this study was to develop highly pH-sensitive bacterial cellulose nanofibers/gelatin-based intelligent films, where the intelligent films were loaded with different ratios (10:0, 0:10 2:8, 5:5 and 8:2, w/w) of curcumin:anthocyanin (Cur/ATH), and the characterization of intelligent films was investigated. The results showed that the microstructures of intelligent films were much rougher as the proportion of curcumin increased. FTIR results showed that anthocyanin and curcumin were fixed in gelatin matrix by hydrogen bonds. Moreover, XRD results showed that curcumin had a significant effect on the crystal structure of the films. Interestingly, films loaded with a Cur/ATH ratio of 5:5 had the best mechanical and antioxidant properties and a high pH-sensitivity property. Consequently, the bacterial cellulose nanofibers/gelatin-based intelligent films loaded with a Cur/ATH ratio of 5:5 were used for the packaging of fresh pork, displaying good fresh-keeping and freshness detection effects. Therefore, this study suggested that bacterial cellulose nanofibers/gelatin-based intelligent films have great potential in the fresh-keeping and freshness detection of meat.

Electrocatalytic hydrogen evolution with a copper porphyrin bearing meso-(o-carborane) substituents.

A newly designed copper complex of 5,15-bis(pentafluorophenyl)-10,20-bis(o-carborane)porphyrin (1) was synthesized and tested for the electrocatalytic hydrogen evolution reaction (HER). In acetonitrile, 1 was much more efficient than Cu 5,15-bis(pentafluorophenyl)-10,20-diphenylporphyrin (2) for electrocatalytic HER by shifting the catalytic wave to the anodic direction by 190 mV. In aqueous media, 1 also outperformed 2 by achieving higher current densities under smaller overpotentials. This enhancement was attributed to the aromatic and the strong electron-withdrawing properties of o-carborane groups. This work is significant to address the crucial effects of meso-(o-carborane) substituents of metal porphyrins on boosting the electrocatalytic HER.

Low oil Pickering emulsion gels stabilized by bacterial cellulose nanofiber/soybean protein isolate: An excellent fat replacer for ice cream.

Food-grade Pickering emulsion gels with different oil phase fractions stabilized by Bacterial cellulose nanofibers/Soy protein isolate complex colloidal particles were prepared by one-step method. The properties of Pickering emulsion gels with different oil phase fractions (5 %, 10 %, 20 %, 40 %, 60 %, 75 %, v/v) and their applications in ice cream were investigated in the present study. The microstructural results showed that Pickering emulsion gels with the low oil phase fractions (5 %-20 %) were an emulsion droplet-filled gel, where the oil droplets were embedded in the network structure of cross-linked polymer, while Pickering emulsion gels with higher oil phase fractions (40 %-75 %) were an emulsion droplet-aggregated gel, which formed a network structure by flocculated oil droplets. The rheology result showed that the low oil Pickering emulsion gels had the same excellent performance as the high oil Pickering emulsion gels. Furthermore, the low oil Pickering emulsion gels showed good environmental stability under harsh conditions. Consequently, Pickering emulsion gels with 5 % oil phase fraction were used as fat replacers in ice cream and ice cream with different fat replacement rates (30 %, 60 % and 90 %, w/w) was prepared in this work. The results showed the appearance and texture of the ice cream with low oil Pickering emulsion gels as fat replacers was similar to that of the ice cream with no fat replacers, and the melting rate of the ice cream with low oil Pickering emulsion gels as fat replacers showed the lowest value of 21.08 % during the 45 min of melting experiment, as the fat replacer rate in the ice cream reached to 90 %. Therefore, this study demonstrated that low oil Pickering emulsion gels were excellent fat replacers and had great potential application in low calorie food production.

Automatic summarization of endoscopic skull base surgical videos through object detection and hidden Markov modeling.

Endoscopic endonasal surgery is a medical procedure that utilizes an endoscopic video camera to view and manipulate a surgical site accessed through the nose. Despite these surgeries being video recorded, these videos are seldom reviewed or even saved in patient files due to the size and length of the video file. Editing to a manageable size may necessitate viewing 3 h or more of surgical video and manually splicing together the desired segments. We suggest a novel multi-stage video summarization procedure utilizing deep semantic features, tool detections, and video frame temporal correspondences to create a representative summarization. Summarization by our method resulted in a 98.2% reduction in overall video length while preserving 84% of key medical scenes. Furthermore, resulting summaries contained only 1% of scenes with irrelevant detail such as endoscope lens cleaning, blurry frames, or frames external to the patient. This outperformed leading commercial and open source summarization tools not designed for surgery, which only preserved 57% and 46% of key medical scenes in similar length summaries, and included 36% and 59% of scenes containing irrelevant detail. Experts agreed that on average (Likert Scale = 4) that the overall quality of the video was adequate to share with peers in its current state.

Superior Energy Density Achieved in Unfilled Tungsten Bronze Ferroelectrics via Multiscale Regulation Strategy.

The most promising candidates for energy storage capacitor application are relaxor ferroelectrics, among which, the perovskite structure ferroelectric ceramics have witnessed great development progress. However, less attention has been paid on tetragonal tungsten bronze structure (TTBS) ceramics because of their lower breakdown strength and polarization. Herein, a multiscale regulation strategy is proposed to tune the energy storage performances (ESP) of TTBS ceramics from grain, domain, and macroscopic scale. The enhanced relaxor behavior with dynamic polar nanodomains guarantees low remanent polarization, while the refined grains and enlarged bandgap ensure increased breakdown strength. Hence, excellent ESP is realized in unfilled TTBS Sr0.425 La0.1 □0.05 Ba0.425 Nb1.4 Ta0.6 O6 (SLBNT) ceramics with an ultrahigh recoverable energy density of 5.895 J cm-3 and a high efficiency of 85.37%. This achievement notably surpasses previous studies in TTBS ceramics and is comparable to that of perovskite components. Meanwhile, the energy density exhibits a wide temperature, frequency, and cycling fatigue stability. In addition, high power density (257.89 MW cm-3 ), especially the ultrafast discharge time (t0.9 = 16.4 ns) are achieved. The multiscale regulation strategy unlocks the energy storage potential of TTBS ceramics and thus highlights TTBS ceramics as promising candidates for energy storage, like perovskite structured ceramics.

Advances in Molecular Design and Photophysical Engineering of Perylene Bisimide-Containing Polyads and Multichromophores for Film-Based Fluorescent Sensors.

Film-based fluorescent sensors (FFSs) represent an important chemistry technology for meeting the urgent needs of on-site and real-time analysis, thereby enabling significant applications in environmental and health monitoring. As the core of FFSs, innovative design of sensing fluorophores and their intrinsic excited-state-related response nature endow FFSs with superior sensing performances in an endless expansion. In this Perspective, we specifically focus on perylene bisimide (PBI)-containing polyads and multichromophores with rigid configuration and notable photochemical stability for developing high-performance FFSs. These nonplanar structures mitigate aggregation and create abundant gaps for the sake of mass transfer and availability of the sensing units in the adlayer of the sensing films. We also comprehensively discuss how to adjust electronic coupling governing the excited-state events by appropriate functionalization strategies, thus providing a plethora of valuable insights for the exploration of the structure-property relationships in these orchestrated molecular systems. Throughout this Perspective, we also identify opportunities for FFSs in the future developments.

Single-Fluorophore-Based Organic Crystals with Distinct Conformers Enabling Wide-Range Excitation-Dependent Emissions.

Achieving wide-range tunable emission colors, especially in the solid state of single-fluorophore materials, remains a significant challenge. Herein, we report a molecular design strategy that affords wide-range excitation-dependent emissions spanning over ≈230 nm in crystalline states. Under the donor-π-acceptor configuration, we judiciously choose a rotatable acceptor fragment, o-carborane, to enrich conformational diversities in the crystalline state and generate conformation-dependent multicolor emissions. We further show that this molecular platform is generalizable in creating crystalline materials with multicolor emissions. Based on these materials, a high-capacity information storage device and a finite-state machine were fabricated to showcase multicolor displays and information storage.

Rigid Bay-Conjugated Perylene Bisimide Rotors: Solvent-Induced Excited-State Symmetry Breaking and Resonance-Enhanced Two-Photon Absorption.

Intramolecular charge transfer and excited-state symmetry breaking have a significant effect on the nonlinear optical properties of multipolar chromophores. Rigid and nonplanar perylene bisimide derivatives (PBIs) functionalized at bay positions were comparatively and comprehensively investigated. In apolar solvents, two quadrupolar molecular rotors showed an obvious decrease of the A0-0/A0-1 ratios, suggesting strong exciton coupling with the adjacent PBI units initiated by the π-π stacking. The vanishment of the preferable dimer emission in polar solvents supported the plausible phenomena of excited-state symmetry breaking, thanks to the facile rotation around the rigid linkers. Comparative femtosecond transition absorption studies confirmed their notable differences in relaxation dynamics and the generation of radical anions (PBI•-) and cations (PBI•+). The maxima two-photon absorption (2PA) wavelengths obtained for the molecular rotors were slightly red-shifted to 670 nm with intrinsic resonance-enhanced characteristics, reflecting the synergistic effect of functional positions and molecular architectures. Meanwhile, the obvious increase of significant 2PA cross-section values in polar solvents illustrated the stabilization of the symmetry-broken dipolar states. Further femtosecond Z-scan also manifested the contribution of excited-state dynamics on the nonlinear optical properties of multipolar chromophores.

Wall wettability effect on process of collapse of single cavitation bubbles in near-wall region using pseudo-potential lattice Boltzmann method.

This study investigates the effect of wall wettability on cavitation collapse based on a large-density-ratio lattice Boltzmann method (LBM) pseudo-potential model. The validity and superiority of the proposed model in simulation of cavitation under complex conditions are confirmed by comparing with theories, experiments, and numerical results by other models. Our simulations indicate that wall wettability has a significant influence on near-wall cavitation of an order no less than the effect of the initial bubble distance. A criterial initial distance exists in near-wall cavitation within which the micro-jet will direct toward the wall. This criterial distance is shown to be positively correlated with the contact angle by a cosine function. Within this distance, the lifetime of the bubble decreases by up to 50%, and the increase of the maximum micro-jet velocity and collapse pressure are up to 131% and 65%, respectively, when the contact angle increases from the hydrophilic 53° to the hydrophobic 113°. Without considering the shock-wave mechanism, the impact pressure transmitted to the hydrophilic wall is of the same order as the maximum collapse pressure while the impact velocity is an order smaller than the maximum micro-jet velocity. Wall wettability affects collapse through the Bjerknes force and the pressure around the bubble. Preliminary analysis also suggests that the relation between the pressure difference and the intensity of collapse exhibits more patterns than we have assumed, which fits a logistic curve well, and appears not changing with the contact angle or the initial bubble distance.

Resonance-Enhanced Two-Photon Absorption and Optical Power Limiting Properties of Three-Dimensional Perylene Bisimide Derivatives.

Push-pull organic structures characterized by an intramolecular charge transfer (ICT) process and π-electron delocalization are potentially interesting luminescent materials. A series of three-dimensional o-carborane-containing perylene bisimide derivatives (PBIs) were synthesized, and their optical properties were systematically investigated to illustrate the stereo effect, especially on the two-photon absorption (2PA) and optical power limiting (OPL) properties. Open-aperture Z-scan curves showed that all four PBIs displayed strong and broad two-photon absorptivities based on the resonance-enhanced phenomenon. The maximum degenerate two-photon absorption cross section (δ2PA) increased with the number of PBI substituents. The derivative CB-PBI possessed a δ2PA value of ∼2400 GM at 650 nm, a significant enhancement in comparison with that of the parent PBI (∼719 GM), ascribed to the present stereo effect. When the aromatic-donating units changed from naphthyl and pyrenyl to PBI, the generated multidimensional intramolecular charge transfer (ICT) from the aromatic units to the o-carborane cage contributed to the 2PA processes. All of the fluorophores exhibited excellent optical power limiting (OPL) performances as well as a minimum limiting threshold of ∼4.98 mJ/cm2 for CB-PBI. These significant results not only allow us to get deep insight into the nature of the fundamental stereo effect and nonlinear optical (NLO) response involved but also guide us toward the design of new multifunctional luminescent materials.

SCMAG: A Semisupervised Single-Cell Clustering Method Based on Matrix Aggregation Graph Convolutional Neural Network.

Clustering analysis is one of the most important technologies for single-cell data mining. It is widely used in the division of different gene sequences, the identification of functional genes, and the detection of new cell types. Although the traditional unsupervised clustering method does not require label data, the distribution of the original data, the setting of hyperparameters, and other factors all affect the effectiveness of the clustering algorithm. While in some cases the type of some cells is known, it is hoped to achieve high accuracy if the prior information about those cells is utilized sufficiently. In this study, we propose SCMAG (a semisupervised single-cell clustering method based on a matrix aggregation graph convolutional neural network) that takes into full consideration the prior information for single-cell data. To evaluate the performance of the proposed semisupervised clustering method, we test on different single-cell datasets and compare with the current semisupervised clustering algorithm in recognizing cell types on various real scRNA-seq data; the results show that it is a more accurate and significant model.