Multistable dynamics in a Hopfield neural network under electromagnetic radiation and dual bias currents

Nonlinear Dynamics - This paper investigates a Hopfield neural network under the simulation of external electromagnetic radiation and dual bias currents, in which the fluctuation of magnetic flux...     

Electro-optic polymer assisted optical switch based on silicon slot structure

One kind of electro-optic polymer assisted Mach-Zehnder optical switch based on silicon slot structure is presented in this paper. The interference arms of the switch are slot structures instead of regular single-mode waveguides. By filling electro-optic material in the void slot of the arms, direct electro-optic modulation can be introduced. Theoretical model and detailed analysis are given in this paper. The length-independent product V_πL is about 74 mV cm when slot width is 100 nm, and 37 mV cm when slot width is 50 nm, when the polymer with a electro-optical coefficient of γ₃₃ = 130 pm/V is assisted. An ultralow energy consumption of only 37 fJ/bit is achievable, and the turn-on time of the switch is less than 1.5 ps.     

基于ZnO电子传输层钙钛矿太阳能电池的研究进展

作为新一代低成本、高效率的光伏器件，以有机卤化铅CH₃NH₃PbX₃(MAPbX₃,X=Br、I、Cl)为光吸收层的钙钛矿太阳能电池(PSCs)相比于其他类型的光伏器件，具有原料丰富、工艺简单等特点。在较短的时间内，该类电池效率已由3.8%迅速攀升至25.7%,几乎可以媲美商用硅太阳能电池，成为能源应用领域的一颗新星。氧化锌(ZnO)因其具有材料易于加工、电子迁移率高、制造成本低廉且形貌结构多样等优点，被作为该类电池较为重要的一种电子传输层(ETL)而被广为研究。本文主要以不同结构的ZnO纳米薄膜ETL作为研究对象，对其在PSCs中的应用进行了总结，详细介绍了基于不同形貌ZnO纳米结构PSCs的研究进展，分析了该类电池面临的主要问题与解决处理方式，并对未来的发展趋势进行了展望。     

Seasonal variation of oxygen-18 in precipitation and surface water of the Poyang Lake Basin,China

Based on the monthly δ¹⁸O value measured over a hydrology period in precipitation, runoff of five tributaries and the main lake of the Poyang Lake Basin, combined with hydrological and meteorological data, the characteristics of δ¹⁸O in precipitation (δ¹⁸O_PPT) and runoff (δ¹⁸O_SUR) are discussed. The δ¹⁸O_PPT and δ¹⁸O_SUR values range from?2.75 to?14.12 ‰ (annual mean value=?7.13 ‰ ) and from?2.30 to?8.56 ‰, respectively. The seasonal variation of δ¹⁸O_PPT is controlled by the air mass circulation in this region, which is dominated by the Asian summer monsoon and the Siberian High during winter. The correlation between the wet seasonal averages of δ¹⁸O_SUR in runoff of the rivers and δ¹⁸O_PPT of precipitation at the corresponding stations shows that in the Poyang Lake catchment area the river water consists of 23% direct runoff (precipitation) and 77% base flow (shallow groundwater). This high proportion of groundwater in the river runoff points to the prevalence of wetland conditions in the Poyang Lake catchment during rainy season. Considering the oxygen isotopic composition of the main body of Poyang Lake, no isotopic enrichment relative to river inflow was found during the rainy season with maximum expansion of the lake. Thus, evaporation causing isotopic enrichment is a minor component of the lake water balance in the rainy period. During dry season, a slight isotopic enrichment has been observed, which suggests a certain evaporative loss of lake water in that period.     

A novel electrode structure with a reverse-biased p⿿n diode for high speed polymer-infiltrated slot modulators

This paper demonstrates an alternative electrode structure for low power optical modulation based on a slotted waveguide geometry filled with E-O polymers. A reverse-biased p?n junction is constructed inside the slot waveguide for apply modulation voltage. With this structure, the fabrication tolerance of the slot based E-O modulator should be more flexible. Analysis shows that the modulation speed of our design is comparable with the through-etched slot modulator, at the level of picoseconds.     

High-speed compact silicon digital optical switch with slot structure

A high-speed compact silicon digital optical switch (DOS) is proposed in this paper. The direct electro-optic effect is applied by filling electro-optic polymer in the void slot of the branches, which compensates the limitation of silicon itself. The crosstalk of about 35 dB and the insertion loss of 0.7 dB is obtained, the switching speed is less than 1 ps, and the whole device length can be shortened to 616 μm even using the basic mode-evolving principle and a simple Y-type structure. Analysis also shows that the device has good fabrication tolerance and wavelength independence over the C-band.     

水杨酸的添加对全无机锡铅混合钙钛矿太阳能电池的影响

全无机钙钛矿太阳能电池(PSCs)因其优异的光电转换效率和高的环境稳定性而被广大学者关注,但Pb元素的使用对环境危害较大限制了其进一步应用。尽管科研人员目前在努力寻找一种危害较小的元素替代铅,但无铅钙钛矿仍然比含铅钙钛矿更易分解,性能也更低。本文采用Sn部分取代Pb制备得到全无机锡铅混合钙钛矿薄膜,并通过添加一定量的水杨酸从而抑制Sn²⁺氧化为Sn⁴⁺,达到稳定相态提升电池光电转换效率的目的。结果表明随着水杨酸的添加量由2 mg·mL^-1增加至6 mg·mL^-1,器件的光电转换效率先增大后降低。通过SEM、XRD、XPS等测试结果发现,当添加量为4 mg·mL^-1时,薄膜相稳定性最好,与不添加水杨酸的器件相比,其短路电流密度(J_sc)从14.7 mA·cm^-2显著提高至15.1 mA·cm^-2,光电转换效率由5.8%提高至6.5%。此外,最优器件在空气环境中存放5 d后,初始光电转换效率仍可保持原有效率的50％,进一步表明水杨酸的添加对锡铅混合钙钛矿相稳定性的提升具有一定的促进作用。     

Generalized Rayleigh surface waves in a piezoelectric semiconductor half space

Meccanica - In this paper, plane strain surface waves, also named generalized Rayleigh surface waves, in a transversely isotropic piezoelectric semiconductor half space are investigated. The...     

Synthesis and Antitumor Activity of Sorafenib Analogs Containing a Tetrazole Moiety

A novel series of diaryl biuret derivatives containing a tetrazole moiety was designed and synthesized.All the target compounds were evaluated for their in vitro antitumor activity against HT-29,HepG2,MCF-7 and A549 cells by MTT assay.Most of them exhibited obvious antitumor activity,and four of them(4a,4c,4h and 7a)were superior to sorafenib in general.Among them,Compound 4h displayed more potent activity than sorafenib in all tested cancer cells.Compound 4c exhibited the most outstanding activity in inhibition of growth of HepG2 cells(IC50=0.55 μmol/L).Further,they both revealed favorable metabolic stability in in vitro assay.Compounds 4c and 4h are promising candidates for further development.     

准静态条件下金属材料的临界断裂准则研究

本文针对9种金属材料完成了具有不同约束程度的10类试样的延性断裂试验, 获得了发生拉、压、扭和裂尖断裂等破坏形式构型试样的载荷-位移试验关系; 基于圆棒漏斗试样拉伸试验所得直至破坏的载荷-位移曲线, 采用有限元辅助试验(finite-element-analysis aided testing, FAT)方法得到了9种材料直至破坏的全程等效应力-应变曲线, 以此作为材料本构关系通过有限元分析获得了各类试样直至临界破坏的载荷-位移关系模拟. 载荷-位移关系模拟结果与试验结果有较好的一致性, 表明用于解决试样颈缩问题的FAT方法所获得的全程材料本构关系针对各向同性材料具有真实性和普适性. 对应9种材料、10类试样的36 个载荷-位移临界断裂点, 通过有限元分析获得了对应的材料临界断裂应力、应变与临界应力三轴度, 研究表明, 第一主应力在延性变形过程中为主控断裂的主导参量; 通过研究光滑、缺口、裂纹等构型试样的断裂状态, 提出了$-1$至3范围的应力三轴度下由第一主应力主控的统一塑性临界断裂准则.