Optical absorption in asymmetric double quantum wells driven by two intense terahertz fields

Optical absorption is investigated for asymmetric double quantum wells driven by a resonant terahertz field and a varied terahertz field,both polarized along the growth direction.Rich nonlinear dynamics of the replica peak and the Autler-Townes splitting of various dressed states are systematically studied in undoped asymmetric double quantum wells by taking account of multiple factors,such as the frequency of the varied terahertz field and the strength of the resonant terahertz field.Each electron subband splits into two dressed states when the resonant terahertz field is applied in the absence of the varied terahertz field,the optical absorption spectrum shows the first-order Autler-Townes splitting of the electron subbands.When a varied terahertz field is added into the resonant system,the replica peak and the second-order Autler-Townes splitting of the dressed states near the band edge respectively emerge when the varied terahertz field is non-resonant and resonant with these dressed states.When the strength of the resonant terahertz field is increased,the first-order Autler-Townes double peaks and the replica peak in the optical absorption spectrum shift with the shifts of the dressed states.The presented results have potential applications in electro-optical devices.     

关于一个改进的Hardy-Hilbert不等式

通过建立权系数并利用改进了的Hlder不等式,得到了一个新的改进的Hardy-Hilbert不等式.当p=2时,便得到了经典的Hilbert不等式的一个改进.     

Necklace solitons in Bessel photonic lattice: Stability and internal oscillation

Stability, internal modes and internal oscillation of 12-pearled necklace solitons in photorefractive crystal with imprinted Bessel photonic lattices are investigated. It is shown that the imaginary parts of internal modes are negligible comparing with real parts. The stable solitons perform long-distance and quasi-periodic oscillation of intensity and shape under the perturbation of internal modes.     

Synthesis and application of multi-walled carbon nanotubes-molecularly imprinted sol-gel composite material for on-line solid-phase extraction and high-performance liquid chromatography determination of trace Sudan IV

A novel composite material of multi-walled carbon nanotubes (MWNTs)-Sudan IV molecularly imprinted polymers (MIPs) was prepared by surface molecular imprinting technique in combination with sol-gel technology. The MWNTs-MIPs were evaluated by scanning electron micrograph (SEM), Fourier transform infrared spectroscopy (FT-IR), and adsorption experiments. The results showed that the MWNTs-MIPs exhibited good selective recognition to Sudan IV. The maximum saturated binding capacity (Q_max) is 63.2 μmol g⁻¹. Applied as sorbent, the MWNTs-MIPs were used for the determination of trace Sudan IV in chilli powder by on-line solid-phase extraction-high-performance liquid chromatography (SPE-HPLC). The results showed that an enrichment factor of 741 was achieved with a loading flow rate of 1.0 mL min⁻¹ for sampling 50 mL. The MWNTs-MIPs provided a fast and convenience determination platform for Sudan IV in real samples.     

多壁碳纳米管表面对硝基苯酚印迹复合材料的制备与吸附性能

以多壁碳纳米管表面接枝的L-苯丙氨酸为结合位点, 甲基丙烯酸为功能单体, 乙二醇二甲基丙烯酸酯为交联剂, 采用沉淀聚合技术, 在碳纳米管表面制备了对硝基苯酚印迹复合材料. 采用红外光谱和扫描电镜研究了该印迹复合材料的结构和形貌, 结果表明, 在碳纳米管表面接枝了一层稳定的印迹材料. 采用高效液相色谱研究了该印迹材料的等温吸附性能, 结果表明, 该印迹材料对模板分子具有较大的吸附容量(Qmax=80.5 μmol/g)和良好的选择吸附性能(选择因子达2.5). 以该印迹材料作为固相萃取吸附剂, 研究了它对对硝基苯酚和其它结构类似物混合溶液的动态吸附性能, 结果表明, 印迹复合材料对对硝基苯酚的吸附容量不受结构类似物浓度的影响, 能较好地应用于对硝基苯酚的分离富集检测.     

Fabrication of urchin-like NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> microspheres assembled by using SDS as soft template for anode materials of Lithium-ion batteries

In this paper, the urchin-like NiCo₂O₄ microspheres assembled by using sodium dodecyl sulfate (SDS) as soft template are successfully fabricated by a facile procedure including microemulsion-solvothermal reaction and subsequent calcination at 400 °C for 4 h. The structure and morphology of synthesized NiCo₂O₄ particles are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been clearly revealed that the prepared three-dimensional urchin-like NiCo₂O₄ microspheres are constituted by one-dimension nanowires. As it is applied to anode for lithium-ion batteries (LIBs), the initial coulombic efficiency is up to 75.7%, and the specific reversible capacity retains up to 1034.2 mAh/g even after 40 cycles at a current density of 100 mA/g. Furthermore, as the current density gradually increases to 800 mA/g, it still delivers the reversible capacity of 895.4 mAh/g. The high reversible specific capacity, perfect cyclability, and rate performance are attributed to the unique urchin-like NiCo₂O₄ microspheres, which can alleviate the volume expansion and shorten the diffusion path of ions and electrons during lithiation/delithiation process. The self-standing urchin-like NiCo₂O₄ microspheres may be a very promising candidate in place of the commercial graphite-based anode materials for high-performance LIBs.     

Linear analysis of degree correlations in complex networks

Many real-world networks such as the protein–protein interaction networks and metabolic networks often display nontrivial correlations between degrees of vertices connected by edges. Here, we analyse the statistical methods used usually to describe the degree correlation in the networks, and analytically give linear relation in the degree correlation. It provides a simple and interesting perspective on the analysis of the degree correlation in networks, which is usefully complementary to the existing methods for degree correlation in networks. Especially, the slope in the linear relation corresponds exactly to the degree correlation coefficient in networks, meaning that it can not only characterize the level of degree correlation in networks, but also reflects the speed that the average nearest neighbours’ degree varies with the vertex degree. Finally, we applied our results to several real-world networks, validating the conclusions of the linear analysis of degree correlation. We hope that the work in this paper can be helpful for further understanding the degree correlation in complex networks.     

印迹聚合物改性多壁碳纳米管固相萃取熊果酸

以聚乙二醇改性的碳纳米管为基质,熊果酸为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,采用沉淀聚合法成功制备碳纳米管-印迹复合材料。采用红外光谱和扫描电镜研究该复合印迹材料的结构和形貌。结果表明,在碳纳米管表面接枝一层稳定且均匀的印迹材料。采用静态吸附实验研究此印迹材料的吸附性能,此印迹材料对模板分子具有较大的表观吸附容量(Qmax为100.1μmol/g)和良好的选择吸附性能。以此印迹材料作为固相萃取材料,优化固相萃取条件,成功分离富集猕猴桃根提取液中熊果酸,富集因子为5.35。     

微波辅助快速制备核-壳型尿苷印迹聚合物及其在线富集应用研究

采用微波辅助加热,以尿苷为模板分子,丙烯酰胺(AA)为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,快速制备尿苷印迹聚合物,聚合时间大大缩短,仅为传统加热的1/8.采用红外光谱和扫描电镜对印迹聚合物进行表征,结果表明二氧化硅表面成功包覆尿苷印迹壳层;该印迹聚合物颗粒分散均匀,印迹壳层厚度约为100 nm.将该印迹聚合物填充萃取柱用于核苷类组分在线富集,结合高效液相色谱仪技术,实现了板蓝根提取液中尿苷、鸟苷和腺苷在线富集和检测.