Multi-ion detection chemosensor based on rhodamine for turn-on fluorescence sensing and bioimaging of Fe3+, Al3+, Cr3+, and Hg2+ under different channels.

A novel rhodamine-based multi-ion fluorescent sensor, RGN, was designed and synthesized for the highly selective detection of mercury ions (Hg2+) in ethanol and water systems, as well as trivalent cations (Fe3+, Al3+, and Cr3+) in acetonitrile and water systems using a two-step Schiff base reaction method. Nuclear magnetic titration experiments and theoretical calculations demonstrated that the sensor achieved the detection of the aforementioned metal ions through the fluorescence turn-on phenomenon induced by lactam ring-opening. Density functional theory (DFT) calculation results showed decreased HOMO-LUMO energy gaps and increased dipole moments, indicating the effective coordination of the sensor with the corresponding metal ions to form more stable complexes, thereby achieving detection objectives. Furthermore, the fluorescence turn-on sensor RGN exhibited relatively low detection limits, with limits of detection (LOD) for Fe3+, Al3+, Cr3+, and Hg2+ being 10.20 nM, 14.66 nM, 58.78 nM, and 73.33 nM, respectively. Finally, practical applications of sensor RGN in environmental water samples, L929 cells, and zebrafish were demonstrated, indicating its potential for detecting and tracking Fe3+, Al3+, Cr3+, and Hg2+ in environmental samples and biological systems, with prospects for biomedical applications in the diagnosis and treatment of heavy metal ion-induced diseases.

Research on the impact of pilot free trade zones on urban green development: A case study based on the Yangtze River Economic Belt in China.

Green development is an important component of China's new development concept. Pilot Free Trade Zones (PFTZs), as "experimental fields" for promoting reform, deepening opening-up, and raising the level of an open economy, are important open areas for China to promote green development. However, existing related research is not extensive. This article takes PFTZs as quasi-natural experiments, with the Yangtze River Economic Belt (YREB) as the research area. Based on urban panel data from 2006 to 2020, using multi-period differences-in-differences and spatial differences-in-differences models, it explores the impact effects of PFTZs on urban green development and their potential mechanisms. The research findings indicate: (1) Overall, PFTZs significantly promote urban green development, with variations in impact effects due to different batches and locations of establishment. (2) Mechanism tests show that PFTZs mainly promote urban green development by stimulating technological innovation, industrial upgrading, and reducing government intervention. (3) From the perspective of spatial spillover effects, the establishment of PFTZs not only promotes the green development process in the host cities but also has a promoting effect on the green development of surrounding cities.

Grit and Second Language Learning Engagement: The Mediating Role of Affect Balance.

The study of the relationship between key psychological attributes of learners and their engagement in second language (L2) learning helps to understand the critical personality mechanisms influencing language learning. The present study examined the L2 learning engagement from the perspectives of grit (i.e., consistent efforts and interests devoted to a long-term goal) and affect balance (a notion that takes into account both positive and negative emotions concurrently, assessing and evaluating which side holds more significance or influence). A cohort of English L2 learners (N = 394) participated in an online survey aimed at gauging their levels of grit, affect balance, and engagement in L2 learning. The results indicated that grit and affect balance were significantly correlated with behavioral engagement and affective engagement in L2 learning. However, among the two components of grit, namely consistency of interest, showed no significant relationship with L2 learning engagement, while perseverance of effort was significantly positively correlated with L2 learning engagement. Affect balance played a partially mediating and full mediating role between perseverance of effort and behavioral engagement as well as affective engagement respectively. These findings confirm the crucial role of perseverance of effort in second language learning and reveal the unique role of affect balance in their relationship.

Preparation and mechanism study of hydrogen bond induced enhanced composited gelatin microsphere probe.

Fluorescent probes offer rapid and efficient detection of metal ions. However, their properties, including high biotoxicity and low detection limits, often limit their utility in biological systems. In this study, we used a microfluidic approach to fabricate photocrosslinked gelatin microspheres with a micropore, providing a straightforward method for loading fluorescent probes into these microspheres based on the adsorption effect and hydrogen bonding interaction. The gelatin microsphere loaded probes, GelMA/TPA-DAP and GelMA/TPA-ISO-HNO were designed and obtained. The results show that these probes exhibit obviously low biotoxicity compared to the original molecular probes TPA-DAP and TPA-ISO-HNO. Simultaneously, it is found that GelMA/TPA-DAP and GelMA/TPA-ISO-HNO have better detection sensitivity, the detection limits are 35.4 nM for Cu2+, 16.5 nM for Co2+ and 20.5 nM for Ni2+ for GelMA/TPA-DAP probe. Compared to the original TPA-DAP they are improved by 37.2 %, 26.3 % and 22.6 % respectively. The corresponding coordination constants were 10.8 × 105, 4.11×105 and 6.04×105, which is larger than homologous TPA-DAP. Similar results were also verified in the GelMA/TPA-ISO-HNO probe. The mechanism was investigated in detail by theoretical simulations and advanced spectral analysis. The density functional theory (DFT) simulations show that the probes are anchored inside the microspheres and the molecular structure is modified due to the hydrogen bonding interaction between the microsphere and the molecular probe, which makes GelMA/TPA-DAP exhibit stronger coordination capacity with metal ions than homologous TPA-DAP. In addition, the adsorption effect also provided some synergistic enhancement contribution. Meanwhile, cellular experiments have also shown that the composite microspheres can improve the biocompatibility of the probe and will provide a wider range of applications towards bioassay. This simple and effective method will provide a convenient way to improve the performance of fluorescent probes and their biological applications.

Mechanical Metamaterials for Handwritten Digits Recognition.

The increasing needs for new types of computing lie in the requirements in harsh environments. In this study, the successful development of a non-electrical neural network is presented that functions based on mechanical computing. By overcoming the challenges of low mechanical signal transmission efficiency and intricate layout design methodologies, a mechanical neural network based on bistable kirigami-based mechanical metamaterials have designed. In preliminary tests, the system exhibits high reliability in recognizing handwritten digits and proves operable in low-temperature environments. This work paves the way for a new, alternative computing system with broad applications in areas where electricity is not accessible. By integrating with the traditional electronic computers, the present system lays the foundation for a more diversified form of computing.

Impact Resistance of 3D-Printed Continuous Hybrid Fiber-Reinforced Composites.

Improving the resilience of 3D-printed composites through material extrusion technology (MEX) is an ongoing challenge in order to meet the rigorous requirements of critical applications. The primary objective of this research was to enhance the impact resistance of 3D-printed composites by incorporating continuous hybrid fibers. Herein, continuous virgin carbon (1k) and Kevlar (130D and 200D) fibers were used with different weight and volume fractions as reinforcing fibers to produce hybrid and non-hybrid composites for impact resistance testing to obtain energy absorption with different impact energies: 20 J, 30 J, 40 J, and 50 J. Moreover, 0°/90° fiber orientations were used. Hybrid composites with combinations of PLA + CF + 130D KF and PLA + CF + 200D KF showed higher impact resistance, less damaged areas (71.45% to 90.486%), and higher energy absorption (5.52-11.64% more) behaviors compared to PLA + CF non-hybrids. CT scan images provided strong evidence to resist the fracture and breakage patterns, because the stiffness and elongation properties of the fibers acted together in the hybrids specimens. Furthermore, positive hybrid effects of the PLA + CF + KF hybrids also showed an ideal match of toughness and flexibility in order to resist the impacts. In the future, these hybrids will have the potential to replace the single type of composites in the fields of aerospace and automobiles.

Spatial 3D Printing of Continuous Fiber-Reinforced Composite Multilayer Truss Structures with Controllable Structural Performance.

Continuous fiber-reinforced composite truss structures have broad application prospects in aerospace engineering owing to their high structural bearing efficiency and multifunctional applications. This paper presents the design and fabrication of multilayer truss structures with controlled mechanical properties based on continuous fiber-reinforced thermoplastic composite 3D printing. Continuous fiber composite pyramid trusses fabricated by 3D printing have high specific stiffness and strength, with maximum equivalent compression modulus and strength of 401.91 MPa and 30.26 MPa, respectively. Moreover, the relative density of a truss structure can be as low as 1.45%. Additionally, structural units can be extended in any direction to form a multilayer truss structure. Structural performance can be controlled by designing the parameters of each layer. This study offers a novel approach for designing a multifunctional multilayer truss structure, a structure with low-density needs and unique load-bearing effects.

A novel polyhedral oligomeric silsesquioxane nanohybrid fluorescent sensor designed based on an osmotic mechanism for specific detection and intelligent scavenging of magnesium ions.

BACKGROUND: Mg2+ has long been recognized as one of the most vital cations due to its diverse physiological and pathological roles, making it indispensable in both biomedical and biological research. Organic fluorescent sensors are commonly employed for Mg2+ detection, but they often lack high selectivity and exhibit poor hydrophilicity, limiting their biomedical applications. RESULTS: Herein, we introduced a novel organic-inorganic hybrid fluorescence sensor, PFHBS, constructed on the POSS nanoplatforms. The efficient connection between PEGylated POSS and the small molecule sensor FHBS through Click chemistry enhances the selectivity and reduces interference, making this chemical sensor ideal for the accurate detection of Mg2+. Furthermore, the incorporation of POSS amplifies the ligand field effect of FHBS, making it more conducive to Mg2+ capture. The modification of PEG chains enhances the sensor's amphiphilicity, facilitating efficient cell penetration and effective Mg2+ detection at the biological level. SIGNIFICANCE: Finally, relying on spontaneous permeation, coupled with its strong ligand field effect and excellent cell permeability, the chemosensor demonstrates the capability to intelligently remove excess Mg2+ from the body. It has been successfully applied to mitigate renal overload resulting from acute Mg2+ poisoning.

Programmable spatial deformation by controllable off-center freestanding 4D printing of continuous fiber reinforced liquid crystal elastomer composites.

Owing to their high deformation ability, 4D printed structures have various applications in origami structures, soft robotics and deployable mechanisms. As a material with programmable molecular chain orientation, liquid crystal elastomer is expected to produce the freestanding, bearable and deformable three-dimensional structure. However, majority of the existing 4D printing methods for liquid crystal elastomers can only fabricate planar structures, which limits their deformation designability and bearing capacity. Here we propose a direct ink writing based 4D printing method for freestanding continuous fiber reinforced composites. Continuous fibers can support freestanding structures during the printing process and improve the mechanical property and deformation ability of 4D printed structures. In this paper, the integration of 4D printed structures with fully impregnated composite interfaces, programmable deformation ability and high bearing capacity are realized by adjusting the off-center distribution of the fibers, and the printed liquid crystal composite can carry a load of up to 2805 times its own weight and achieve a bending deformation curvature of 0.33 mm-1 at 150 °C. This research is expected to open new avenues for creating soft robotics, mechanical metamaterials and artificial muscles.

Distribution of phthalate metabolites, benzophenone-type ultraviolet filters, parabens, triclosan and triclocarban in paired human hair, nail and urine samples.

In this study, the distribution of nineteen ingredients of personal care product (PCPs), including seven metabolites of phthalates (mPAEs), five benzophenone-type ultraviolet filters (BPs), and seven antimicrobial agents (AAs), were investigated in paired human hair, nail and urine samples. The median concentrations of ΣmPAEs, ΣBPs and ΣAAs were 135, 2.76 and 179 ng/g in hair, 37.3, 2.95 and 297 ng/g in nails, and 345, 4.03 and 50.1 ng/mL in urine, respectively. Mono-methyl phthalate (49%), 2,4-dihydroxybenzophenone (45%) and triclosan (71%) were the most abundant mPAE, BP and AA in hair samples, respectively, and had similar abundance in nail samples. In contrast, mono-n-butyl phthalate (45%), 4-hydroxy benzophenone (29%) and methyl paraben (54%) were the predominant mPAE, BP and AA in urine samples, respectively. Significant differences in the concentrations of some target compounds were observed between male and female but inconsistent across different matrices. Moreover, most compounds with significant correlations had quite different correlation coefficients in each matrix. No significant correlations were found between hair, nail and urine samples for most of the target analytes. These results suggest these analytes have matrix-specific distribution, and it is necessary to use multiple matrices to comprehensively assess the risk of ingredients of PCPs to human health.

Virus transmission risk of college students in railway station during Post-COVID-19 era: Combining the social force model and the virus transmission model.

In the post-epidemic era, people's lives are gradually returning to normal, and travel is gradually resuming. The safe evacuation of cross-regional travelers in railway station has also attracted more and more attention, especially the evacuation behavior of college students in railway station. In this paper, considering the pedestrian dynamics mechanism in the emergency evacuation process during the COVID-19 normalized epidemic prevention and control, an Agent-based social force model was established to simulate the activities of college students in railway station. Combined with the virus infection transmission model, Monte Carlo simulation was used to calculate the total exposure time and the number of high-risk exposed people in the railway station evacuation process. In addition, sensitivity analysis was conducted on the total exposure time and the number of high-risk exposed people under 180 combinations of the number of initial infections, social distance, and the proportion of people wearing masks incorrectly. The results show that with the increase of social distances, the total exposure time and the number of high-risk exposures do not always decrease, but increase in some cases. The presence or absence of obstacles in the evacuation scene has no significant difference in the effects on total exposure time and the number of high-risk exposures. During the evacuation behavior of college students in railway station, choosing the appropriate number of lines can effectively reduce the total exposure time and the number of high-risk exposures. Finally, some policy suggestions are proposed to reduce the risk of virus transmission in the railway station evacuation process, such as choosing dynamic and reasonable social distance and the number of queues, and reducing obstacles.

Calcium alginate/silk fibroin peptide/Bletilla striata polysaccharide blended microspheres loaded with tannic acid for rapid wound healing.

Biodegradable natural polymers are receiving increasing attention as potential candidates for wound dressing. In the present study, composite microspheres (mCSB) based on calcium alginate (CA), silk fibroin peptide (SP), and Bletilla striata polysaccharide (BSP) were prepared by the reverse emulsion method. The excellent swelling properties of microspheres enable them to rapidly promote thrombosis. Microspheres can increase the platelet aggregation index to 1.5 and the aggregation rate of red blood cells to as high as 80 %. Furthermore, tannic acid (TA)-loaded microspheres demonstrate a slow-release effect on TA; this allows the microspheres to exhibit good long-lasting antibacterial properties. Due to the synergistic effects of SP and TA, the cell senescence was delayed, with a 126.69 % survival rate of fibroblasts after 3 days of incubation. In addition, TA led to a rapid reduction in inflammation levels, with a wound closure rate of >92.80 % within 7 days. The multifunctional TA-loaded mCSB has great application potential for rapid wound healing and the treatment of wound hemostasis.

Fabrication of microspheres containing coagulation factors by reverse microemulsion method for rapid hemostasis and wound healing.

Traditional dressings, such as bandages, gauze, and cotton pads stick to new granulation tissue, thereby aggravating wound injury or causing secondary injury during replacement. Microspheres that are biodegradable and adaptable to various wound shapes are a good alternative to traditional dressings. In this work, a novel microsphere was prepared by reverse microemulsion method using sodium alginate and silk peptide (SP) as the aqueous phase. After cross-linking by Ca2+, calcium alginate (CA) and SP composite microspheres called CA/SP were prepared. By adjusting the SP content, the swelling rate of microspheres reached 1050 % and the pore diameter reached 19.59 nm. In addition, the introducing SP provided a stable loading site for thrombin (Th). This platform (called CA/SP@Th)-integrating rapid blood enrichment, calcium release, and Th catalysis-can ensure rapid hemostasis in a variety of bleeding models. Additionally, the SP present in this modality also promoted fibroblast proliferation, this increased the wound closure rate in a total cortex injury mouse model (more than 97 % within 15 days). Therefore, CA/SP@Th can be used as a multifunctional dressing for rapid hemostasis and wound healing.

Interfacial Transcrystallization and Mechanical Performance of 3D-Printed Fully Recyclable Continuous Fiber Self-Reinforced Composites.

To fully exploit the preponderance of three-dimensional (3D)-printed, continuous, fiber-reinforced, thermoplastic composites (CFRTPCs) and self-reinforced composites (which exhibit excellent interfacial affinity and are fully recyclable), an approach in which continuous fiber self-reinforced composites (CFSRCs) can be fabricated by 3D printing is proposed. The influence of 3D-printing temperature on the mechanical performance of 3D-printed CFSRCs based on homogeneous, continuous, ultra-high-molecular-weight polyethylene (UHMWPE) fibers and high-density polyethylene (HDPE) filament, utilized as a reinforcing phase and matrix, respectively, was studied. Experimental results showed a qualitative relationship between the printing temperature and the mechanical properties. The ultimate tensile strength, as well as Young's modulus, were 300.2 MPa and 8.2 GPa, respectively. Furthermore, transcrystallization that occurred in the process of 3D printing resulted in an interface between fibers and the matrix. Finally, the recyclability of 3D-printed CFSRCs has also been demonstrated in this research for potential applications of green composites.

3D Printing of Continuous Fiber Reinforced Low Melting Point Alloy Matrix Composites: Mechanical Properties and Microstructures.

A novel 3D printing route to fabricate continuous fiber reinforced metal matrix composite (CFRMMC) is proposed in this paper. It is distinguished from the 3D printing process of polymer matrix composite that utilizes the pressure inside the nozzle to combine the matrix with the fiber. This process combines the metallic matrix with the continuous fiber by utilizing the wetting and wicking performances of raw materials to form the compact internal structures and proper fiber-matrix interfaces. CF/Pb50Sn50 composites were printed with the Pb50Sn50 alloy wire and modified continuous carbon fiber. The mechanical properties of the composite specimens were studied, and the ultimate tensile strength reached 236.7 MPa, which was 7.1 times that of Pb50Sn50 alloy. The fracture and interfacial microstructure were investigated and analyzed. The relationships between mechanical properties and interfacial reactions were discussed. With the optimized process parameters, several composites parts were printed to demonstrate the advantages of low cost, short fabrication period and flexibility in fabrication of complex structures.