Luminescent polymer nanomaterials not only have the characteristics of various types of luminescent functional materials and a wide range of applications, but also have the characteristics of good ...biocompatibility and easy functionalization of polymer nanomaterials. They are widely used in biomedical fields such as bioimaging, biosensing, and drug delivery. Designing and constructing new controllable synthesis methods for multifunctional fluorescent polymer nanomaterials with good water solubility and excellent biocompatibility is of great significance. Exploring efficient functionalization methods for luminescent materials is still one of the core issues in the design and development of new fluorescent materials. With this in mind, this review first introduces the structures, properties, and synthetic methods regarding fluorescent polymeric nanomaterials. Then, the functionalization strategies of fluorescent polymer nanomaterials are summarized. In addition, the research progress of multifunctional fluorescent polymer nanomaterials for bioimaging is also discussed. Finally, the synthesis, development, and application fields of fluorescent polymeric nanomaterials, as well as the challenges and opportunities of structure-property correlations, are comprehensively summarized and the corresponding perspectives are well illustrated.
Range hood is a local ventilation device applied widely in residential kitchen for maintaining healthy environment. This study firstly defines the direct capture efficiency (DCE) based on the ...two-zone model in a confined kitchen space. A mass flux ratio of the secondary captured pollutant to the entrained pollutant from the room zone is proposed for the determination of DCE, where the distribution coefficient is firstly solved, and then its sensitivity analysis on the DCE is carried out. To validate the mass flux ratio and concisely identify the DCE, a virtual purification method that artificially sets the escaped pollutant to zero, is further applied. Compared with the newly developed DCE, the existing indexes, such as contaminant removal efficiency (CRE), total capture efficiency (TCE), fail to differentiate the direct capture from the total capture. Finally, the effects of such factors as makeup airflow pattern, exhaust flow rate, cooking source temperature and the individual occupied/unoccupied on the DCE are fully studied. It is confirmed that different makeup airflow pattern results in distinguished airflow distribution, which makes a significant difference of more than 30% in DCE. Over 50% increase of DCE can be achieved when the exhaust flow rate is increased from 300 to 600 m
3
/h. About 30% decrease of DCE is observed with the increased cooking source temperature from 100 to 300 °C, and 10% increase of DCE is appeared in the individual occupied case. This reasonable definition and determination of DCE would help to improve the real capture performance of range hoods.
As global food security faces challenges, enhancing crop yield and stress resistance becomes imperative. This study comprehensively explores the impact of nanomaterials (NMs) on Gramineae plants, ...with a focus on the effects of various types of nanoparticles, such as iron-based, titanium-containing, zinc, and copper nanoparticles, on plant photosynthesis, chlorophyll content, and antioxidant enzyme activity. We found that the effects of nanoparticles largely depend on their chemical properties, particle size, concentration, and the species and developmental stage of the plant. Under appropriate conditions, specific NMs can promote the root development of Gramineae plants, enhance photosynthesis, and increase chlorophyll content. Notably, iron-based and titanium-containing nanoparticles show significant effects in promoting chlorophyll synthesis and plant growth. However, the impact of nanoparticles on oxidative stress is complex. Under certain conditions, nanoparticles can enhance plants' antioxidant enzyme activity, improving their ability to withstand environmental stresses; excessive or inappropriate NMs may cause oxidative stress, affecting plant growth and development. Copper nanoparticles, in particular, exhibit this dual nature, being beneficial at low concentrations but potentially harmful at high concentrations. This study provides a theoretical basis for the future development of nanofertilizers aimed at precisely targeting Gramineae plants to enhance their antioxidant stress capacity and improve photosynthesis efficiency. We emphasize the importance of balancing the agricultural advantages of nanotechnology with environmental safety in practical applications. Future research should focus on a deeper understanding of the interaction mechanisms between more NMs and plants and explore strategies to reduce potential environmental impacts to ensure the health and sustainability of the ecosystem while enhancing the yield and quality of Gramineae crops.
Graph convolutional networks have achieved remarkable performance in action recognition from skeleton videos. However, most of the existing GCN-based methods improve performance by increasing model ...parameters, which require a high amount of data. This means that they usually perform poorly on small sample learning tasks. In this paper, we propose a novel enhanced data guidance algorithm to improve the performance of the GCN-based method on small sample datasets. These enhanced data perform coordinate transformation on the skeleton to obtain robustness to scale, rotation and translation. The proposed guidance algorithm allows the target model to learn the advantages of enhanced data and reduce the complexity of the task. We also propose a new key node method, which can select key joints and frames in the spatial and temporal dimensions respectively. This removes the redundant information of the skeleton sequence and significantly reduces the computational cost. Furthermore, the combination of key nodes and enhanced data can greatly reduce the demand for training data. The recognition accuracy rates of 94.81% and 94.19% have been achieved on the public MSR Action3D and UTD-MHAD datasets, respectively. This result proves that our method is significantly better than mainstream 3D action recognition methods.
Zwitterionic microspheres of poly2-(dimethylamino) ethyl methacrylate (PDMAEMA) block polymethacrylic acid (MAA) were prepared by RAFT dispersion polymerization in alcohols. ...4-Cyano-4-(phenylcarbonothioylthio) pentanoic acid (CPDB) was used as the RAFT agent. 2,2′-Azobis(2,4-dimethyl) valeronitrile (V65) was used as the initiator, and PDMAEMA-CPDB was used as the macro-chain transfer agent (CTA).
1
HNMR was applied to determine the polymerization degrees of both PDMAEMA-CTA and PDMAEMA-b-PMAA. SEM, dynamic light scattering (DLS), and small-angle X-ray diffraction (SAX) were employed to characterize the microspheres. It was observed that the polarity of alcohols impacted the partition of MAA and V65 between the mini-droplets of PDMAEMA-CTA/MAA complexes and the continuous phase, thereby affected on the diameters of microspheres, the total conversion of MAA, and the polymerization degree of PMAA in the copolymers. For example, in methanol, the smallest diameter and polymerization degree of PMAA in the block copolymers were obtained, whereas the total conversion of MAA of the RAFT polymerization system was the highest. Most of RAFT polymerization of MAA occurred nearby PDMAEMA-CTA chains; thus, PDMAEMA-CTA acted as a template to regulate the length of PMAA in the copolymers. pH-sensitive characteristics of microspheres were dependent to the extra length of PDMAEMA-CTA, i.e., the difference of lengths between two blocks. When the length of PMAA was too short, e.g., PDMAEMA
600
-b-PMAA
87
, or the length of PMAA was closed to that of PDMAEMA, e.g., PDMAEMA
79
-b-PMAA
93
and PDMAEMA
102
-b-PMAA
131
, the amphoteric characteristics of microspheres disappeared. The self-assembly behavior of diblock copolymers in KCl alcohol-water solution was also determined by the extra length of PDMAEMA. Microspheres turned into nanofibers or nano-ribbons, but for PDMAEMA
600
-b-PMAA
87
, the microspheres maintained their original spheric morphology. These results indicated that the charge-screening effects of salts played the key roles in the self-assembly.
Graphical abstract
Low‐temperature fuel cells (LTFCs) are considered to be one of the most promising power sources for widespread application in sustainable and renewable energy conversion technologies. Although ...remarkable advances have been made in the mass activity of catalysts, mass transport impedance needs to be urgently addressed at a well‐designed membrane electrode assembly (MEA) scale. Increasing the loading of electrocatalysts is conducive to prepare thinner and more efficient MEAs owing to the resulting enhanced reactant permeability, better proton diffusion, and lower electrical resistance. Herein, recent progress in high‐loading (≥40 wt.%) Pt nanoparticle catalysts (NPCs) and high‐loading (≥2 wt.%) single‐atom catalysts (SACs) for LTFC applications are reviewed. A summary of various synthetic approaches and support materials for high‐loading Pt NPCs and SACs is systematically presented. The influences of high surface area and appropriate surface functionalization for Pt NPCs, as well as coordination environment, spatial confinement effect, and strong metal‐support interactions (SMSI) for SACs are highlighted. Additionally, this review presents some ideas regarding challenges and future opportunities of high‐loading catalysts in the application of LTFCs.
Increasing the loading of electrocatalysts is considered as a practical strategy to achieve thin catalyst layer resulting in smooth reactant permeability and low electrical resistance. Various synthetic approaches and functionalized support materials are presented for obtaining high‐loading Pt nanoparticle catalysts (≥40 wt.%) and single‐atom catalysts (≥2 wt.%).
According to the concept of fire life cycle assessment (LCA), a new type of intumescent flame retardant was designed and synthesized by chemically bonding chitosan, phosphorus pentoxide and melamine. ...The resultant compound, chitosan ethoxyl melamine phosphate (CEMP), was characterized by FTIR,
H NMR,
P NMR, XRD and SEM. The performance of CEMP and organic montmorillonite (OMMT) was evaluated in the substrate of epoxy resin (EP) with limited oxygen index (LOI), UL-94, cone calorimetric test (CCT), TGA and TG-IR. As a result, intumescent flame retardant EP (EP3) containing 30.6% LOI and V-0 rating was prepared by adding 3 wt% OMMT and 15 wt% CEMP. The CCT results indicated that CEMP and OMMT reduced the peak of heat release rate (PHRR) to about one fourth that of pure EP and total heat release (THR), 1/2. Decomposition of EP and EP3 was traced from 100 to 600°C by TG-IR.
AbstractIn this work, Cu (II) ion was chosen as an analyte because it is an important trace element in the human body to maintain organism health. AuNCs (gold nanoclusters) with a mean diameter of ∼2 ...nm were prepared by a microwave-assisted method, using homocysteine (Hcy) as a reducer and stabilizer. The optimal sample showed a red emission peaking at 624 nm with an emission quantum yield of 17.1%, which was assigned as a ligand to metal nanoparticle core charge transfer (LMNCT). This red emission was effectively quenched by Cu (II) but immune to competing metal cations and anions, showing good selectivity. The quenching mechanism was found as the Cu (II) quenching on the LMNCT procedure to AuNCs. The primary advantage of Hcy-modified AuNCs was the easy and quick synthetic procedure, along with acceptable sensing performance, including good selectivity, linear response, and wide working region.
Although Sparse Representation based Classifier (SRC), a non‐parametric model, can obtain an interesting result for pattern recognition , a reasonable interpretation has been lacked for its ...classification mechanism. What is more, the training samples are used as off‐the‐shelf dictionary directly in SRC, which can make the feature hidden in the training samples hard be extracted. At the same time, the complexity of the algorithm is increased because of too many atoms of the dictionary. The authors first explains in detail the classification mechanism of SRC from the view of probabilistic collaborative subspace and offer the process to improve the stability of the algorithm using the joint probability in the case of the multi‐subspace. Then, the authors introduce the dictionary learning (DL) and Fisher criterion into the model to further enhance the discrimination of the coding coefficient. In order to ensure the convexity of the discrimination term and further enhance the discrimination, the authors add the L21‐norm term into the Fisher discrimination term and offer the proof for its convexity. Finally, the experimental result on a series of benchmark databases, such as AR, Extended Yale B, LFW3D‐hassner, LFW3D‐sdm and LFW3D‐Dlib, show that PCDDL outperforms existing classical classification models.
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