对海监视雷达杂波的建模及仿真

杂波是雷达回波信号的重要组成部分,研究中常用幅度概率分布模型和相关谱型来描述。采用零记忆非线性变换法(ZMNL)进行建模设计,生成同时满足幅度分布条件和相关特性的随机序列,并将模拟杂波数据的概率密度和功率谱与理论曲线对比,进一步验证 ZMNL 法杂波建模的有效性和准确性。最后针对海航大学对海探测的雷达回波实测数据,进行海杂波和云雨杂波回波的幅度概率分布和功率谱的分析。     

Poly(pentahydropyrimidine)-Based Hybrid Hydrogel with Synergistic Antibacterial and Pro-Angiogenic Ability for the Therapy of Diabetic Foot Ulcers

Bacterial infection and impaired angiogenesis make the treatment of diabetic foot ulcers (DFU) extremely challenging. Cationic polymers are expected to treat infected wounds due to their excellent antibacterial properties, but still, it is difficult to meet the therapeutic needs of pro-angiogenesis and anti-infections due to their simple construction units and outmoded synthesis methods. Herein, a cationic poly(pentahydropyrimidine) (PPHP) library with strong modifiability is synthesized to construct a hybrid hydrogel with synergistic therapeutic effects for the treatment of infected DFUs. It is found that the as-synthesized hybrid hydrogel can up-regulate angiogenesis-related gene (HIF-1, VEGF, and bFGFR/bFGF) expression and targeted disruption of bacterial cell membranes, which finally promotes the healing of infected DFU (wound healing rate: 92%) within 10 days. This hydrogel, thus, holds great promise in developing new strategies to significantly enhance the treatment of DFU and other bacterial-infected pathological diagnoses.     

Scavenging of “Dead Sulfur” and “Dead Lithium” Revealed by Integrated–Heterogeneous Catalysis for Advanced Lithium–Sulfur Batteries

The simultaneous engineering of sulfur cathode and Li anode is critical for electrolyte-starved high energy density Li–S batteries, in which slow electrochemical conversions and side chemical reactions of dead sulfur are found to be the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li–S batteries. Herein, this work challenges the conventional wisdom of heterogeneous and homogeneous catalyses in Li–S batteries and proposes the concept of integrated–heterogeneous catalysis to simultaneously scavenge the dead sulfur and dead lithium to compensate the active materials sulfur and lithium loss simply through adding a small amount of ZnI₂ into conventional electrolyte of Li–S cells. Regulated by integrated–heterogeneous catalysis, over 1300 h of cycling is realized in Li||Li symmetric cells, revealing superb compatibility of the ZnI₂-incorporated electrolyte with lithium metal. Meanwhile, the ZnI₂ shows good prospects in promoting the reutilization of dead sulfur in both theoretical calculation and experimental tests. Practically, a high initial capacity of 1170 mAh g⁻¹ with decent cycling stability is achieved in electrolyte-starved and high-loading pouch cells (5.0 µL mg⁻¹ and 5.2 mg cm⁻²).     

All-Visible-Light Triggered Photoswitch of Dithienylethene Derivatives with Molecular Conformation Changes Excess 5 Å

Developing new all-visible-light driven fluorescent molecular switches has attracted much interests due to their important application prospects in materials science and life science. Herein, three novel all-visible-light triggered fluorescent molecular photoswitches ( 2P3 , 4F , and 4Cl ) are designed and prepared, which are realized by prolonging π-conjugation length with aggregated-induced emission units. These photoswitches show reversible photochromic and fluorescent switching in dilute solutions and films under 420 nm and 560 nm irradiations. Meanwhile, upon alternating irradiations with 450 nm/560 nm light, effective photochromic and fluorescent switching in powder states are also achieved. More interestingly, two distinct conformations with different photochromic abilities can be altered by solvents polarity. The size difference of the two conformations is over 5 Å in the vertical direction which is one of the largest changes among photochromic molecules based on dithienylethene. The accompanying conformational changes are analysed to understand the relationship between solvent characteristics and crystal structure, as well as the intermolecular interaction in solid state for all-visible-light triggered photoswitching molecules.