High-temperature crystal structure and electronic properties of cesium niobate Cs2Nb4O11

The antiferroelectric material Cs₂Nb₄O₁₁ transforms at 165 °C from a low-temperature, antiferroelectric phase in space group Pnna to a high-temperature, paraelectric phase in space group Imma; the latter structure has been determined by single-crystal X-ray diffraction. The high-temperature lattice is comprised of niobium-centered tetrahedra and octahedra connected through shared vertices and edges; cesium atoms occupy channels afforded by the three-dimensional polyhedral network. Calculated band structures for both phases predict a bandgap of 3.1-3.2 eV, which is similar to that found experimentally through photoluminescence. The calculated band structure is also conducive to its observed photocatalytic properties.     

Tunable charge-transport properties of I(h)-C80 endohedral metallofullerenes: investigation of La2@C80, Sc3N@C80, and Sc3C2@C80

Fullerene crystals or films have drawn much interest because they are good candidates for use in the construction of electronic devices. The results of theoretical calculations revealed that the conductivity properties of I(h)-C(80) endohedral metallofullerenes (EMFs) vary depending on the encapsulated metal species. We experimentally investigated the solid-state structures and charge-carrier mobilities of I(h)-C(80) EMFs La(2)@C(80), Sc(3)N@C(80), and Sc(3)C(2)@C(80). The thin film of Sc(3)C(2)@C(80) exhibits a high electron mobility μ = 0.13 cm(2) V(-1) s(-1) under normal temperature and atmospheric pressure, as determined using flash-photolysis time-resolved microwave conductivity measurements. This electron mobility is 2 orders of magnitude higher than the mobility of La(2)@C(80) or Sc(3)N@C(80).     

Fredholmness of multipliers on Hardy–Sobolev spaces

This paper discusses the Fredholmness of multipliers on Hardy–Sobolev Spaces and obtains an index formula for the multipliers with some special symbols. Our results show that Hardy–Sobolev spaces have richer properties than classical holomorphic function spaces, and the behavior of the operators on these spaces is complex. Some methods of Hardy or Bergman spaces fail in the case of the Hardy–Sobolev space.     

Automorphism Group of Toeplitz Algebras on Certain Pseudoconvex Domains

in this paper, we characterize the automorphism groups of Toeplitz algebras oncertain strongly pseudoconvex domains of Cn, and obtain a generalized BDF theorem for aspecial kind of essential normal operator tupies.     

Segal-Bargmann空间上带无界符号的Toeplitz算子

In this paper,we construct a function φ in L2(Cn,d Vα) which is unbounded on any neighborhood of each point in Cnsuch that Tφ is a trace class operator on the SegalBargmann space H2(Cn,d Vα).In addition,we also characterize the Schatten p-class Toeplitz operators with positive measure symbols on H2(Cn,d Vα).     

Evaluation of the enantioselectivity of carbon nanoparticles‐modified chiral separation systems using dextrin as chiral selector by capillary electrokinetic chromatography

Nanoparticles (NPs) can be used as pseudostationary phases (PSPs) in EKC, which is similar to the use of micelle additives as applied in MEKC. To date, the use of NPs to enhance enantiomeric separation by EKC with β‐CD or its derivative as chiral selector has been reported only in two papers. However, to the best of our knowledge, there has been no prior effort to use NPs for achieving enantioseparation with polysaccharides as chiral selector. This paper describes for the first time the use of carbon nanoparticles (CNPs) as PSPs to modify chiral separation system employing dextrin as chiral selector for the enantioseparations of several basic drugs in capillary EKC. Three different types of CNPs, including carbogenic nanoparticles (NPs), carboxylated single‐walled carbon nanotubes, and carboxylated multiwalled carbon nanotubes, were used as running buffer additives, respectively. The potential of the PSPs and the effects of dextrin concentration, buffer pH, and buffer concentration on the enantioseparations were evaluated. Four pairs of tested enantiomers were successfully resolved in less than 15 min with the resolution values in the range of 1.41–4.52 under optimized conditions. Compared to the buffer without NPs, the introduction of NPs into the buffer enhanced the separation of the enantiomers.     

Quantitative analysis of single aerosol particles using polycapillary X-ray optics

A laboratory micro X-ray fluorescence spectrometer based on polycapillary X-ray optics (PXRO) was used to carry out the quantitative X-ray fluorescence analysis of single aerosol particles with smaller size than that of focal spot of PXRO. The minimum detection limits measured with the thin-film reference standards were in the range from 13.3 to 0.7 ng cm^? 2 when the operating current and voltage were 70 mA and 35 kV, respectively. In order to reduce the effects of the inhomogeneous distributions of the X-ray intensity in the focal spot of the PXRO on the analysis results, the sensitivities were corrected by using a Gaussian function for the quantitative analysis of single aerosol particles. The accuracy of the analysis of single standard solution drops was on average 25% depending on the element and concentration. The precision of the analysis was better than 5%.     

对具有定常故障率和任意系统修复率的可修复系统的猜测分析

研究了具有定常人为故障率 (human error rates)和通常故障率 (common-cause failure rates) ,修复时间任意分布的可修复系统的数学模型 .首先将此系统转换为 Banach空间下的 Volterra积分方程 ,得到了系统非负解的存在性和唯一性结果 .     

Composition operators on a Banach space of analytic functions

In this paper, we study composition operators on a Banach space of analytic functions, denoted byX, which includes the Bloch space. This space arises naturally as the dual space of analytic functions in the Bergman spaceL _α ¹ (D) which admit an atomic decomposition. We characterize the functions which induce compact composition operators and those which induce Fredholm operatorson this space. We also investigate when a composition operator has a closed range. Supported by NNSFC No.19671036