Zaozhuang University

In this study, using bio-based eugenol as the basic polymerization unit, the directional coupling of quaternary phosphonium cations and eugenol was achieved through covalent bonding, and a new type of degradable antibacterial monomer (Eu-PH) was successfully synthesized. Notably, cubic nanoparticles were obtained via the self-assembly of Eu-PH during its homopolymerization, whereas spherical nanoparticles were generated when Eu-PH was copolymerized with N-vinylpyrrolidone (NVP). This structural transformation not only induced significant changes in the material's physicochemical properties but also markedly enhanced its antibacterial efficacy. Experimental results demonstrated that PHx-PVPy achieved inhibition rates of 100% against Escherichia coli and Staphylococcus aureus, with a relative biocompatibility of 99% toward L-929 cells. In addition, PHx-PVPy exhibited excellent degradability and fruit preservation performance. In brief, by virtue of structural regulation of bio-based eugenol and NVP, a promising new approach is proposed for the development of antibacterial materials that simultaneously possess high antibacterial activity, good biocompatibility, and satisfactory degradability.

Controlled drainage (CD) can improve crop yield by optimizing the soil water and nutrient environment. Nevertheless, the combined effects of reduced nitrogen fertilization and CD on crop leaf senescence characteristics is unclear. Thus, a two-year field experiment was conducted to address the effects of nitrogen fertilizer rates (280, 252, 224, and 196 kg N ha-1, denoted as N1, N2, N3, and N4, respectively) on the leaf area index (LAI), SPAD value, net photosynthetic rate (Pn), activities of superoxide dismutase (SOD), peroxidases (POD), catalase (CAT), and the contents of soluble protein (SP) and malondialdehyde (MDA) in plant leaves, and the seed yield of cotton under CD and free drainage (FD). CD resulted in greater LAI, SPAD value, Pn, SOD, POD, and CAT activities, and SP content, and smaller MDA content at the three reduced nitrogen rates, and thus obtained a relatively high seed cotton yield. The delayed leaf senescence characteristics were due to greater soil moisture and NO3--N content in the plough (0–40 cm) layer under CD. Notably, all reduced nitrogen rates significantly decreased the cottonseed yield under FD, but N2 and N3 had comparable cottonseed yields under CD. Therefore, we concluded that controlled drainage could stabilize seed cotton yield by improving photosynthesis, the antioxidant defenses and osmoregulation at 80%-90% of normal nitrogen fertilizer rate. The results also reveal the physiological mechanisms through which the drainage regime mediates crop yield under varying nitrogen rates.

Deep-silicon detectors emerge as a prime solution for next-generation X-ray photon-counting CT imaging due to their exceptional high-energy compatibility (up to 100 keV), sub-nanosecond temporal resolution, and superior radiation hardness. Similar to silicon microstrip readout, these detectors require multi-channel front-end readout application-specific integrated circuits (ASICs) to process and count charge signals from microstrips. Leveraging existing X-ray tube technology, the low energy deposition per detector unit (as low as 2 keV) necessitates ultra-low-noise analog front-ends with ENC < 100 el.rms. Exploiting the silicon detector’s high temporal resolution enables count rate exceeding 100 Mcps/mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. Conventional noise models fail to optimize such high-flux circuits. In this paper, a physics-based ENC model is derived for high-count-rate automatic feedback reset architecture, revealing fundamental trade-offs between noise, speed, and power. Guided by this model, we propose a systematic low-noise design methodology and implement a 64-channel ASIC in 130-nm CMOS. The error between circuit-level simulation results and modeling predictions is within 10%. Experimental results demonstrate a maximum count rate of 10.2 Mcps and the ENC is 250 el.rms with a 12.4 el/pF slope at 2.5 mW/channel. Simulations and measurements jointly confirm the model’s accuracy in guiding low-noise design for high-count-rate photon-counting ASICs.