最大度大于等于7的平面图的线性荫度

图的染色问题在组合优化、计算机科学和Hessians矩阵的网络计算等方面具有非常重要的应用。其中图的染色中有一种重要的染色——线性荫度,它是一种非正常的边染色,即在简单无向图中,它的边可以分割成线性森林的最小数量。研究最大度$\bigtriangleup（G）\geq7$的平面图$G$的线性荫度,证明了对于两个固定的整数$i$,$j\in\{5,6,7\}$,如果图$G$中不存在相邻的含弦$i$,$j$-圈,则图$G$的线性荫度为$\lceil\frac\bigtriangleup2\rceil$。     

物理实验数据的软件处理

通过具体的实验实例,分别详细地介绍了用Excel和Matlab两种软件处理数据的过程,以此为例体现软件处理数据的简便性和准确性.处理过程基本涵盖了常用的数据处理要求和涉及到的相关软件命令,可为其他实验的数据处理提供详细参考.     

The novel rufigallol-based liquid crystals with cholesterol units: synthesis,mesomorphic and photophysical properties

Three novel rufigallol derivatives with four alkyl chains and two cholesteric units 6a, 6b and 6c were prepared in yields of 83–88%. The mesomorphic properties were investigated by DSC, POM and XRD analysis, suggesting that compounds 6a, 6b and 6c possess the ordered hexagonal columnar mesophase. The long alkyl chains contribute to the low phase transition temperature. Sample 6c with four dodecyl chains and two cholesterol units is a room temperature liquid crystal between 31°C and 87°C. Compounds 6a, 6b and 6c also have good fluorescence emission between 400 nm and 500 nm. The studies on CD spectra implied that the chiralities of cholesterol moieties are successfully transferred to the liquid crystalline core. Samples 6a, 6b and 6c are the first fluorescence liquid crystal based on rufigallol core with chiral cholesterol units.     

Double-image encryption based on iterative gyrator transform

A novel double-image encryption algorithm is proposed, which can simultaneously encrypt two images into a single one as the amplitude of gyrator transform with two different groups of angles. The two original images can be retrieved independently by gyrator transforms with two different groups of angles, one common phase mask, and two different private phase masks. The proposed approach can enlarge the key space, achieve faster convergence in iterative process, and avoid cross-talk between two images in reconstruction. Numerical simulations are presented to verify its validity and efficiency.     

带-NH2的嘧啶环对钌配合物与DNA相互作用的瞬态发光特性的影响

采用时间分辨的发光光谱技术,分别测量了两种新合成的钌配合物[Ru(bpy)2 (dpbpd(NH2)2)]2 和[Ru(phen)2(dpbpd(NH2)2)]2 与小牛胸腺脱氧核糖核酸(ctDNA)相互作用时的瞬态发光动力学过程,并与以往对[Ru(phen)2dppz]2 等的研究结果进行对比,从而研究带-NH2的嘧啶环对配合物与DNA作用动力学过程的影响.结果表明:这两种含有带-NH2的嘧啶环的钌配合物与DNA相互作用时的发光按双指数规律衰减,发光寿命为几十纳秒,比dppz类钌配合物与DNA作用时的发光衰变寿命(几百纳秒)小一个数量级.归因于嘧啶环上的N和-NH2可能与水分子、DNA的碱基对或磷酸骨架形成氢键,从而加快激发态的无辐射弛豫,削弱发射光强,缩短发光寿命.该结论为进一步研究配合物分子与DNA的相互作用的机理提供了一定的依据.     

Nanostructured Pt supported on cocoon-derived carbon as an efficient electrocatalyst for methanol oxidation

Development of suitable supports has been proven as an important preparation process for high active catalysts of fuel cell. In this work, a carbon material was prepared by pyrolyzing cocoons with ferric chloride as activator, and then Pt nanoparticles (ca. 50 wt.%) were deposited on its surface. The characteristics of X-ray diffraction and transmission electron microscopy showed that the face-centered cubic structured Pt nanoparticles with nano-sized crystals interconnected each other via grain boundaries were formed on the surface of pyrolyzed cocoons. Afterwards, electrochemical results demonstrate that the nanostructured Pt supported on this support exhibits higher catalytic activity and CO tolerance than Pt nanoparticles supported on Vulcan carbon for methanol oxidation reaction.     

Understanding Synergistic Catalysis on Cu-Se Dual Atom Sites via Operando X-ray Absorption Spectroscopy in Oxygen Reduction Reaction

The construction and understanding of synergy in well-defined dual-atom active sites is an available avenue to promote multistep tandem catalytic reactions. Herein, we construct a dual-hetero-atom catalyst that comprises adjacent Cu-N₄ and Se-C₃ active sites for efficient oxygen reduction reaction (ORR) activity. Operando X-ray absorption spectroscopy coupled with theoretical calculations provide in-depth insights into this dual-atom synergy mechanism for ORR under realistic device operation conditions. The heteroatom Se modulator can efficiently polarize the charge distribution around symmetrical Cu-N₄ moieties, and serve as synergistic site to facilitate the second oxygen reduction step simultaneously, in which the key OOH*-(Cu₁-N₄) transforms to O*-(Se₁-C₂) intermediate on the dual-atom sites. Therefore, this designed catalyst achieves satisfied alkaline ORR activity with a half-wave potential of 0.905 V vs. RHE and a maximum power density of 206.5 mW cm⁻² in Zn-air battery.     

Magnetically‐Confined Fe‐Mn Bimetallic Oxide Encapsulation as an Efficient and Recoverable Adsorbent for Arsenic(III) Removal

Synthesis of bimetallic‐oxide‐encapsulated magnetic nanoparticles is still significantly challenging and has rarely been attempted previously, due to the effects of lattice mismatch, weak chemical interactions and variances in growth rates between different components, as well as the difficulty in process control for uniform co‐deposition. In the present work, Fe‐Mn bimetallic oxide (FMBO) nanoplatelet encapsulated magnetic nanoparticles (Mag‐FeMn) are prepared by controlled engineering of the interparticle coupling of Fe₃O₄ and FMBO, with its multifunctional capabilities highlighted in terms of the potentially superior As(III) sequestration and convenient recoverability. Multiple characterization techniques are employed to examine the derived morphologies and to accurately resolve both compositionally and magnetically the hierarchical structure in detail. The synthesized magnetic composites retain highly porous structure with the main components of Fe₂O₃, FeOOH, Fe₃O₄, and Mn₃O₄. Mag‐FeMn exhibits a quite competitive high capacity for As(III) capture (56.1 mg g^–1), whereby As(III) oxidation coupled with synchronous sorption contributes to the improved performance. The unique heterostructure of FMBO encapsulation with an embedded magnetic core would be applicable to help with rational synthesis of other bimetallic oxide encapsulated magnetic nanoparticles, and definitely shows promise for the development of new nanotechnology enabled approaches for adsorption‐based water purification.     

Synthesis and characterization of green-emitting phosphorescent Ir(III) complexes based on phenyl benzimidazole ligand

Several new Ir(III) complexes with 2-(4-bromophenyl)-1H-benzo[d]imidazole or 2-(4-bromophenyl)- 1-methyl-benzo[d]imidazole ligands as cylcometalated ligand and acetylacetonate or picolinate as the ancillary ligand were synthesized and their structures and photophysical properties were characterized. HOMO and LUMO energy levels and the molecular structures of Ir(III) complexes were scrutinized by DFT calculations. The complexes exhibited green luminescence at the maximum emission peaks at ca 495–522 nm. The methyl group substituent and replacing of acetylacetonate with picolinate complex can enhance the complex thermal stability. HOMO energy levels of the complexes vary from –4.99 to –5.44 eV, the LUMO energy levels are between –1.52 and –1.97 eV.