一类含时滞的比率依赖捕食系统正平衡点的全局稳定性分析

讨论了一种食饵增长为Gilpin-Ayala型的比率依赖的食饵捕食者模型,利用第二加性复合矩阵原理证明线性化系统正轨道解的稳定性,结合系统在凸集中存在唯一的局部正平衡点,证明了正平衡点的全局渐近稳定性.结合数值模拟验证了所得结论的合理性,同时指出定理结论仅为充分条件,丰富完善了模型的动力学性质.     

Colossal Stability of SiB11(BO)12−: An Implication as Potential Electrolyte in High-Voltage Alkali-ion Battery

High-voltage alkali metal-ion batteries (AMIBs) require a non-hazardous, low-cost, and highly stable electrolyte with a large operating potential and rapid ion conductivity. Here, we have reported a halogen-free high-voltage electrolyte based on SiB₁₁(BO)₁₂⁻. Because of the weak π-orbital interaction of −BO as well as the mixed covalent and ionic interaction between SiB₁₁-cage and −BO ligand, SiB₁₁(BO)₁₂⁻ has colossal stability. SiB₁₁(BO)₁₂⁻ possesses extremely high vertical detachment energy (9.95 eV), anodic voltage limit (∼10.05 V), and electrochemical stability window (∼9.95 V). Furthermore, SiB₁₁(BO)₁₂⁻ is thermodynamically stable at high temperatures, and its large size allows for faster cation movement. The alkali salts MSiB₁₁(BO)₁₂ (M=Li, Na, and K) are easily dissociated into ionic components. Electrolytes based on SiB₁₁(BO)₁₂⁻ greatly outperform commercial electrolytes. In short, SiB₁₁(BO)₁₂⁻-based compound is demonstrated to be a high-voltage electrolyte for AMIBs.     

中空碳纳米球的制备及VOCs吸附性能

首先, 在碱性条件下, 不使用表面活性剂, 采用St?ber小球法以正硅酸四乙酯(TEOS)和正硅酸四丙酯(TPOS)为硅源, 生成初级氧化硅球形颗粒; 然后, 使酚醛树脂(间苯二酚和甲醛)与球形氧化硅的羟基共缩合形成酚醛树脂-氧化硅复合材料; 最后, 经高温碳化和酸蚀获得了空心碳纳米球(HCNSs). 通过调节TEOS/TPOS的摩尔比获得了一系列具有良好的单分散性且粒径、 壁厚可调节的HCNSs, 其粒径和壁厚分别在280~430 nm和15~63 nm的范围内. 仅以TPOS为硅源时合成的HCNS-0/4具有较大的粒径(426 nm)和壁厚(63 nm)、 较高的比表面积(1216 m²/g)和孔容(0.508 cm³/g), 并且具有较大的挥发性有机化合物(VOCs)吸附性能, 其正己烷、 甲苯和油气的静态吸附容量分别为2.02, 1.42和0.926 g/g, 正己烷和甲苯的动态吸附容量分别为2.01 g/g和1.37 g/g, 均远高于商业化活性炭.     

Selective alcohol oxidation catalysed BY FeCl3 /novel glycine functionalised IONIC liquid

An effective and eco-friendly technique were designated for quick alcohol oxidation by glycine functionalised imidazolium ionic liquids in presence of FeCl₃ at ambient-temperature. No over the primary alcohols oxidation to carbonyl compounds was observed in presence of this FeCl₃/[Gmim]Cl. These benefits of the catalyst resulted mainly from the circumstance with alcohols-H₂O₂, and the Fe³⁺ was coordinated by the immobilized IL to permitted both reactants to access the active sites of the catalyst effectively. The catalyst recycled nine times without loss of activity.     

电催化醇选择性氧化为醛酮的研究进展

醇选择性氧化为相应的羰基化合物是有机化学中最常用的生成羰基化合物的反应,电催化氧化具有反应条件温和、环境友好等优点,是一种非常有前途的醇催化氧化绿色生产工艺。本文综述了直接和间接电催化氧化反应的方法,并对各类体系的催化效果进行了简要介绍。     

脱水Ni-Fe类水滑石的制备及其作为环保型催化剂用于生物质糠醛的高选择性缩醛化反应

合成了含硝酸根离子的脱水Ni-Fe类水滑石（Ni-Fe HTLCs）并将其应用于室温下的糠醛缩醛化反应。脱水Ni-Fe HTLCs对糠醛缩醛化反应显示出高选择性并基本实现糠醛的完全转化。作为耐水的路易斯酸和脱水剂,脱水Ni-Fe HTLCs被证明是适用于糠醛缩醛化反应的高效双功能催化剂。通过研究发现,脱除Ni-Fe HTLCs中水分导致颗粒收缩并增强层板间硝酸根离子间的电荷互斥,Ni-Fe HTLCs中弱酸性位点在糠醛缩醛化中发挥重要作用,脱水可改变酸性位点结构并增强其活性。脱水Ni-Fe HTLCs可吸收缩醛化反应中产生的大部分水分,但吸水后Ni-Fe HTLCs的结构并不能完全恢复,这可能是由扩散进入HTLCs层板间的有机分子导致。     

β-二亚胺配体支持的铝胺化合物的制备及其催化ε-己内酯开环聚合的高效性能

成功合成了由β-二亚胺配体(L)支持的铝胺化合物(L)AlH(NMe2)2(L=HC(C(Me)NAr)2,Ar=2,6-iPr2C6H3)(1)。该化合物采用分步合成法进行制备,以n-BuLi与HNMe2反应生成的锂盐LiNMe2作为前驱体,进一步与(L)AlH2溶液共混通过消除LiH得到目标产物。通过核磁共振谱、元素分析、红外漫反射光谱和X射线单晶衍射确定了铝胺化合物(L)AlH(NMe2)2的组成与结构。该铝胺化合物中,金属Al中心同时形成Al-H和Al-NMe2基团,在催化ε-己内酯的开环聚合的反应中展现出了优异的催化活性。通过高效凝胶渗透色谱测定了所得聚合物的分子量和分子量分布。     

Monitoring the Reaction of the Body State to Antibiotic Treatment against Helicobacter pylori via Infrared Spectroscopy: A Case Study

The current understanding of deviations of human microbiota caused by antibiotic treatment is poor. In an attempt to improve it, a proof-of-principle spectroscopic study of the breath of one volunteer affected by a course of antibiotics for Helicobacter pylori eradication was performed. Fourier transform spectroscopy enabled searching for the absorption spectral structures sensitive to the treatment in the entire mid-infrared region. Two spectral ranges were found where the corresponding structures strongly correlated with the beginning and end of the treatment. The structures were identified as methyl ester of butyric acid and ethyl ester of pyruvic acid. Both acids generated by bacteria in the gut are involved in fundamental processes of human metabolism. Being confirmed by other studies, measurement of the methyl butyrate deviation could be a promising way for monitoring acute gastritis and anti-Helicobacter pylori antibiotic treatment.     

Standard enthalpies of formation of selected XYZ half-Heusler compounds

The standard enthalpies of formation of selected ternary half-Heusler type compositions XYZ (X = Au, Co, Fe, Ir, Ni, Pd, Pt, Rh, Ru; Y = Hf, Mn, Ti, Zr; Z = Ga, Sn) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation (in kJ/mole of atoms) of the half-Heusler compounds (prototype MgAgAs, Pearson symbol cF12, space group F-43m) are, IrMnSn (−29.4 ± 1.8); NiTiSn (−52.6 ± 2.4); PtHfSn (−98.8 ± 3.4); PtMnSn (−55.8 ± 2.6); PtTiSn (−93.6 ± 3.3); PtZrSn (−104.9 ± 3.8); for the B2 compound (prototype CsCl, Pearson symbol cP2, space group Pm-3m), RuMnGa (−26.9 ± 1.7); for the C1 structured (prototype CaF₂, Pearson symbol cF12, space group Pm-3m) or the C1_b structured compound IrMnGa (−40.9 ± 1.7). Indicative standard enthalpies of formation of the following compounds were obtained, half-Heusler compounds AuMnSn, CoTiSn, IrZrSn, NiHfSn, NiZrSn, PdHfSn, PdZrSn, RhTiSn; Heusler compound (prototype Cu₂MnAl, Pearson symbol cF16, space group Fm-3m) RhMnSn; hexagonal compound (prototype BeZrSi, Pearson symbol hP6, space group P6₃/mmc) PtMnGa and another type of hexagonal compound (prototype RhHfSn, Pearson symbol hP18, space group P-62c) RhHfSn, IrZrsn, RhZrSn. Values were compared with ab initio calculations from AFLOW and OQMD. Lattice parameters of these compounds were determined using X-ray diffraction (XRD) analysis. Microstructures were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Selected alloys were further annealed to investigate phase transformations and phase relationships.     

Four Metal Complexes Based on Bulky Imidazole Ligands: Solvothermal Syntheses,Crystal Structures,and Fluorescence Properties

In order to explore the influences of (de‐)protonation of the imidazole ring on the structural diversity of the resulting complexes, the imidazole‐based ligands 4, 5‐diphenylimidazole (Hdpi) and 1H‐phenanthro[9, 10‐d]imidazole (Hpi) were utilized as bulky building blocks to construct four complexes by solvothermal reactions, i.e. [Ag(Hdpi)₂](NO₃) · (H₂O) ( 1 ), [Cu(dpi)]_∞ ( 2 ), [Cu(Hpi)(NO₃)]_∞ ( 3 ), and [(H₂pi)(NO₃)] · H₂O ( 4 ). In complex 1 , two Hdpi ligands adopt a monodentate pattern and coordinate with one Ag^I ion to form a mononuclear unit, which is further connected by hydrogen bonds into a 1D supramolecular helix. The deprotonated dpi ligand of 2 acts in bidentate mode, and bridges Cu^I ions to afford a 1D chain. In 3 , the NO₃^– ion, acts as a monodentate bridging ligand and joins Cu^I ions to generate a 1D chain. The Hpi ligand employs a monodentate mode to bond with Cu^I ions of the 1D chain. 4 is protonated and two H₂pi nitrogen atoms are free of coordination. Interestingly, hydrogen bonds among the NO₃^– ion, the H₂pi ligand, and the water molecule yield a macro ring R⁴₄(14). The resulting structural diversity reveals that the (de‐)protonation of imidazole ring directly steers the coordination number of ligand, and thus causes a significant effect on the structure, especially the dimensionality. Furthermore, the solid‐state fluorescence properties of the free ligands and compounds 1 – 4 were studied at room temperature.