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This study investigated the synthesis of cerium oxide (CeO2) nanoparticles (NPs) and composites with reduced graphene oxide (rGO) for the enhanced electrochemical sensing of ammonia. CeO2 NPs were prepared by the focused laser ablation in liquid (LAL) method, which enabled the production of high-purity, spherical nanoparticles with a uniform dispersion and sizes under 50 nm in a short time. The effects of varying irradiation fluence and time on the nanoparticle size, production yield, and dispersion were systematically studied. The synthesized CeO2 NPs were doped with rGO to form CeO2/rGO composites, which were drop casted to modify the glassy carbon electrodes (GCE). The CeO2/rGO-GCE electrodes exhibited superior electrochemical properties compared with single-component electrodes, which demonstrated the significant potential for ammonia detection, especially at a 4 J/cm2 fluence. The CeO2/rGO composites showed uniformly dispersed CeO2 NPs between the rGO sheets, which enhanced the conductivity, as confirmed by SEM, EDS mapping, and XRD analysis. Cyclic voltammetry data demonstrated superior electrochemical activity of the CeO2/rGO composite electrodes, with the 2rGO/1CeO2 ratio showing the highest current response and sensitivity. The CV response to varying ammonia concentrations exhibited a linear relationship, indicating the electrode's capability for accurate quantification. These findings highlight the effectiveness of focused laser ablation in enhancing nanoparticle synthesis and the promising synergistic effects of CeO2 and rGO in developing high-performance electrochemical sensors. [ABSTRACT FROM AUTHOR]

Guanxing was determined as the study area, and the characteristics and formation mechanism of the transition of "production-life-ecology" were analyzed from 1990 to 2018 by transfer matrix model, habitat quality index model and ecological contribution rate model. The results showed that: 1) The area of production and living space increased by 299.72 square kilometers and 900.34 square kilometers respectively, while the area of ecological space decreased by 1200.06 square kilometers; 2)The high-quality ecological environment zones are distributed in the northern areas with higher elevation, the medium-quality zones are distributed in the central plain areas,and the low-quality zones are distributed in the southern coastal areas; 3)The ecological environment quality changes from population and natural environment as the main controlling factors gradually turned to the driving mechanism of the policy system, socio-economic and demographic factors.Thus, It is an effective measure for Guangxi to deal with the ecological environment problems by reducing the speed of the production and living space crowding out the ecological space in the central plain and the southern coastal areas, and reducing the disturbance of human economic activities to the land space in the severe rocky desertification area in the north.

Integrin receptor αvβ3 and gastrin-releasing peptide receptor (GRPR) expression of tumors could be detected using PET imaging with radiolabeled Arg-Gly-Asp (RGD) and the antagonistic bombesin analog RM26, respectively. The purpose of this study was to investigate the dual receptor-targeting property of the heterodimer RGD-RM26-03 (denoted as LNC1015), demonstrate the tumor diagnostic value of [68Ga]Ga-LNC1015 in preclinical experiments, and evaluate its preliminary clinical feasibility. Methods: LNC1015 was designed and synthesized by linking cyclic RGD and the RM26 peptide. Preclinical pharmacokinetics were detected in a PC3 xenograft model using microPET and biodistribution studies. The clinical feasibility of [68Ga]Ga-LNC1015 PET/CT was performed in patients with breast cancer, and the results were compared with those of 18F-fluorodeoxyglucose (FDG). Results: [68Ga]Ga-LNC1015 had good stability in saline for at least 2 h, and favorable binding affinity and specificity were demonstrated in vitro and in vivo. The tumor uptake and retention of [68Ga]Ga-LNC1015 during PET imaging were improved compared with its monomeric counterparts [68Ga]Ga-RGD and [68Ga]Ga-RM26 at all the time points examined. In our initial clinical studies, the tumor uptake and tumor-to-background ratio (TBR) of primary and metastatic lesions in [68Ga]Ga-LNC1015 PET/CT were significantly higher than those in [18F]FDG PET/CT, resulting in high lesion detection rate and tumor delineation. Conclusion: The dual targeting radiotracer [68Ga]Ga-LNC1015 showed significantly improved tumor uptake and retention, as well as lower liver uptake than [68Ga]Ga-RGD and [68Ga]Ga-RM26 monomer. The first-in-human study showed high TBRs in patients, suggesting favorable pharmacokinetics and high clinical feasibility for PET/CT imaging of cancer. [ABSTRACT FROM AUTHOR]

N-nitrosodimethylamine (NDMA) is a strong carcinogen with high toxicity and environmental persistence. It exists widely in human living environment and has attracted great attention. The toxic effect of NDMA on juvenile Crucian carp was studied by semi-static acute toxicity test and determination of protein content, superoxide dismutase (SOD) and catalase (CAT) activities. The results showed that high concentration of NDMA was significantly toxic to juvenile Crucian carp, and the 50% lethal concentration (LC50) at 24 h, 48 h, 72 h and 96 h were 9.83 mg/L, 9.14 mg/L, 8.11 mg/L and 7.05 mg/L, respectively. The safe concentration (SC) was 0.71 mg/L. NDMA had different effects on protein content and SOD and CAT activities of juvenile Crucian carp. With the increase of NDMA concentration, protein content showed inducible effect. SOD activity was induced in low concentration group (1.18 mg/L and 1.76 mg/L), but significantly inhibited in high concentration group (3.68 mg/L). CAT activity was mainly induced, but inhibited in 3.68 mg/L concentration group. With the extension of exposure time, the inhibition rate of each index was as SOD enzyme activity>CAT enzyme activity>protein content. In this study, the acute toxicity and oxidative stress toxicity of NDMA on juvenile Crucian carp were discussed, which provided a scientific basis for preventing and reducing the toxicity of disinfection by-products to aquatic organisms. [ABSTRACT FROM AUTHOR]

Traditional intelligent frequency-hopping anti-jamming technologies typically assume the presence of an ideal control channel. However, achieving this ideal condition in real-world confrontational environments, where the control channel can also be jammed, proves to be challenging. Regrettably, in the absence of a reliable control channel, the autonomous synchronization of frequency decisions becomes a formidable task, primarily due to the dynamic and heterogeneous nature of the transmitter and receiver's spectral states. To address this issue, a novel communication framework for intelligent frequency decision is introduced, which operates without the need for negotiations. Furthermore, the frequency decision challenge between two communication terminals is formulated as a stochastic game, with each terminal's utility designed to meet the requirements of a potential game. Subsequently, a two-agent deep reinforcement learning algorithm for best-response policy learning is devised to enable both terminals to achieve synchronization while avoiding jamming signals. Simulation results demonstrate that once the proposed algorithm converges, both communication terminals can effectively evade jamming signals. In comparison to existing similar algorithms, the throughput performance of this approach remains largely unaffected, with only a slightly extended convergence time. Notably, this performance is achieved without the need for negotiations, making the presented algorithm better suited for realistic scenarios. [ABSTRACT FROM AUTHOR]