葡聚糖修饰的超顺磁性氧化铁纳米粒子的制备及表征

以乙酰丙酮铁为铁源,聚乙二醇为溶剂,采用高温热分解法制备了超顺磁性氧化铁纳米粒子,得到聚乙二醇修饰的超顺磁性氧化铁纳米粒子,进一步修饰葡聚糖.苯酚-浓硫酸显色法表明葡聚糖修饰在SPIONs表面,获得葡聚糖修饰的氧化铁纳米粒子.采用透射电镜、纳米粒度和Zeta电位分析仪、超导量子干涉仪和热重对产物进行检测.葡聚糖/聚乙二醇修饰的超顺磁性氧化铁纳米粒子的平均粒径为8.7±1.5 nm;水合动力学粒径33 nm,Zeta电位为13mV.葡聚糖/聚乙二醇修饰的超顺磁性氧化铁纳米粒子为超顺磁性,饱和磁化强度为21 emu/g;热重分析表明约有42wt;的葡聚糖和30wt;的PEG修饰在SPIONs表面,计算得到纯氧化铁纳米粒子的饱和磁化强度为75 emu/g.     

FeS2能隙的外压微扰调制

 采用基于密度泛函理论的自洽赝势方法，计算了FeS₂在外压调制下的电子结构性质。计算结果表明：随着压缩度的增加，外压调制下的Fe—S键长缩短，FeS₂小的能隙变宽，Fe的d电子与S的p电子杂化增强，原子间相互作用增大。这一能隙随压力增大而增大的结果，与非导体在高压下金属化的特征相反。     

HOLE-BURNING SPECTROSCOPY OF ACTIVE AND INACTIVATEE) PHOTOSYSTEM II PARTICLES

This paper reports transient and persistent hole-burning of photosynthetically active as well as chemically reduced and heat inactivated photosystem II particles isolated from cyanobacteria. Transient spectra of active and non-active particles are significantly different. For both, the possible origin of the bottle-neck state is discussed. Persistent holes were ascribed to the antenna complex of photosystem II. From their width the energy transfer rate was estimated to be 4.8 ps at 4.2 K.     

meso‐Bis{η5‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}iron(II) and the cobalt(II) analogue

The two title crystalline compounds, viz.meso‐bis{η⁵‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}iron(II), [Fe(C₁₂H₂₀NSi)₂], (II), and meso‐bis{η⁵‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}cobalt(II), [Co(C₁₂H₂₀NSi)₂], (III), were obtained by the reaction of lithium 1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienide with FeCl₂ and CoCl₂, respectively. For (II), the trimethylsilyl‐ and dimethylaminoethenyl‐substituted cyclopentadienyl (Cp) rings present a nearly eclipsed conformation, and the two pairs of trimethylsilyl and dimethylaminoethenyl substituents on the Cp rings are arranged in an interlocked fashion. In the case of (III), the same substituted Cp rings are perfectly staggered leading to a crystallographically centrosymmetric molecular structure, and the two trimethylsilyl and two dimethylaminoethenyl substituents are oriented in opposite directions, respectively, with the trimethylsilyl group of one Cp ring and the dimethylaminoethenyl group of the other Cp ring arranged more closely than in (II).     

Hierarchical Porous NiCo2O4 Microboxes Constructed by Low-Dimensional Substructures for Electrochemical Supercapacitor

The design and synthesis of new materials/structures for high-performance electrochemical capacitors (ECs) is an ongoing challenge. Herein, a hierarchical porous NiCo₂O₄ microbox superstructure made of low-dimensional substructures was reported. The as-prepared NiCo₂O₄ microboxes are constructed by 2D nanosheets building units, which are futher woven by 0D nanoparticles and 1D nanowires. Such microbox superstructures combine the merits of all material dimensions in electrochemical capacitors, such as high porosity, sufficient active sites, and fast mass and charge transport. Benefiting from the structural advantages, the resultant NiCo₂O₄ microbox electrode exhibits ultra-high capacitor performance, i.e., the initial capacitance of 1820 F · g^–1 and 96.6 % capacitance retention after 4000 cycles at 5 A · g^–1.     

ChemInform Abstract: [Ta3O3]A (A: Li,Na, K) and [Ta3O3]B[Ta3O3] (B: Ca,Sr, Ba): Sandwich‐Type Complexes Containing Ta3O3‐ δ and π Double Aromatic Ligands.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Use of optical fibres in Raman spectroscopy

A detailed study of the parameters governing the design of an optical fibre system for use in Raman spectroscopy is described. The results have led to the design and construction of a flexible fibre optic remote sampling system which is easily adaptable for use on most commercial instruments. A variety of samples were used to evaluate the performance of the system and have been classified in terms of the efficiency of the new technique relative to more conventional methods of excitation and collection.