Natural and Doubly Natural Dualities

Representable dualities between categories of modules satisfying natural closure properties are investigated and shown to be determined by homological properties shared by various classical and recently investigated types of dualities.     

Quasi Co-Hopfian Modules and Applications

We carry out an extensive study of modules M _R with the property that M/f(M) is singular for all injective endomorphisms f of M. Such modules called “quasi co-Hopfian”, generalize co-Hopfian modules. It is shown that a ring R is semisimple if and only if every quasi co-Hopfian R-module is co-Hopfian. Every module contains a unique largest fully invariant quasi co-Hopfian submodule. This submodule is determined for some modules including the semisimple ones. Over right nonsingular rings several equivalent conditions to being quasi co-Hopfian are given. Modules with all submodules quasi co-Hopfian are called “completely quasi co-Hopfian” (cqcH). Over right nonsingular rings and over certain right Noetherian rings, it is proved that every finite reduced rank module is cqcH. For a right nonsingular ring which is right semi-Artinian (resp. right FBN) the class of cqcH modules is the same as the class of finite reduced rank modules if and only if there are only finitely many isomorphism classes of nonsingular R-modules which are simple (resp. indecomposable injective).     

Removable edges in a 5-connected graph and a construction method of 5-connected graphs

An edge e of a k-connected graph G is said to be a removable edge if G?e is still k-connected. A k-connected graph G is said to be a quasi (k+1)-connected if G has no nontrivial k-separator. The existence of removable edges of 3-connected and 4-connected graphs and some properties of quasi k-connected graphs have been investigated [D.A. Holton, B. Jackson, A. Saito, N.C. Wormale, Removable edges in 3-connected graphs, J. Graph Theory 14(4) (1990) 465-473; H. Jiang, J. Su, Minimum degree of minimally quasi (k+1)-connected graphs, J. Math. Study 35 (2002) 187-193; T. Politof, A. Satyanarayana, Minors of quasi 4-connected graphs, Discrete Math. 126 (1994) 245-256; T. Politof, A. Satyanarayana, The structure of quasi 4-connected graphs, Discrete Math. 161 (1996) 217-228; J. Su, The number of removable edges in 3-connected graphs, J. Combin. Theory Ser. B 75(1) (1999) 74-87; J. Yin, Removable edges and constructions of 4-connected graphs, J. Systems Sci. Math. Sci. 19(4) (1999) 434-438]. In this paper, we first investigate the relation between quasi connectivity and removable edges. Based on the relation, the existence of removable edges in k-connected graphs (k?5) is investigated. It is proved that a 5-connected graph has no removable edge if and only if it is isomorphic to K₆. For a k-connected graph G such that end vertices of any edge of G have at most k-3 common adjacent vertices, it is also proved that G has a removable edge. Consequently, a recursive construction method of 5-connected graphs is established, that is, any 5-connected graph can be obtained from K₆ by a number of θ⁺-operations. We conjecture that, if k is even, a k-connected graph G without removable edge is isomorphic to either K_k+1 or the graph H_k/2+1 obtained from K_k+2 by removing k/2+1 disjoint edges, and, if k is odd, G is isomorphic to K_k+1.     

Use of quasi-isoelectric buffers to limit protein adsorption in capillary zone electrophoresis

The use of quasi-isoelectric buffers consisting of narrow pH cuts of carrier ampholytes (NC) has been investigated to limit protein adsorption on capillary walls during capillary zone electrophoresis experiments. To quantify protein adsorption on the silica surface, a method derived from that of Towns and Regnier has been developed. alpha-Lactalbumin (14 kDa, pI 4.8) and alpha-chymotrypsinogen A (25 kDa, pI 9.2) have been used as model proteins. Acidic narrow pH cuts of carrier ampholytes (NC, pH 3.0) obtained from fractionation of Serva 4-9 carrier ampholytes were used as BGE in bare-silica capillaries, and allowed to decrease significantly protein adsorption, as compared to experiments performed with classical formate buffer. The use of NC as BGE appeared to be as efficient as the use of polydimethylacrylamide coating to prevent protein adsorption. This increase of protein recovery when using NC was attributed to the interaction of carrier ampholytes with the silica surface, leading to a shielding of the capillary wall.     

Novel quasi-interpenetrating network/gold nanoparticles composite matrices for DNA sequencing by CE

In order to further improve ssDNA sequencing performances using quasi-interpenetrating network (quasi-IPN) as a matrix composed of linear polyacrylamide (LPA) with lower viscosity-average molecular mass (3.3 MDa) and poly(N,N-dimethylacrylamide) (PDMA), gold nanoparticles (GNPs) were prepared and added into this quasi-IPN to form polymer/metal composite sieving matrices. The studies of intrinsic viscosity and differential scanning calorimetry (DSC) on quasi-IPN and quasi-IPN/GNPs indicate that there were interactions between GNPs and polymer chains. The sequencing performances on ssDNA using quasi-IPN and quasi-IPN/GNPs (with different GNPs concentrations) as sieving matrices were studied and compared by CE at different temperatures. The results show that resolutions of quasi-IPN/GNPs were higher than those of quasi-IPN without GNPs and approximated those of quasi-IPN composed of LPA with higher MW (6.5 MDa) and PDMA without GNPs in the bare fused-silica capillaries. Furthermore, the sequencing time of quasi-IPN/GNPs was shorter than that of quasi-IPN under the same sequencing conditions. The influences of GNPs and sequencing temperature on the sequencing performances of ssDNA were also discussed. The separation reproducibility of quasi-IPN/GNPs solution was excellent and its shelf life was more than 8 months.     

LIBS/Raman光谱对称零面积变换自动寻峰方法研究

自动寻峰是进行光谱原位探测、实时自动分析的必要环节,对拓展光谱分析技术到长期海洋监测、石油录井等应用领域具有重要意义。该研究以实验室中获得的LIBS/Raman光谱数据,对Gaussian,Lorenz,Voigt三种线型函数构建的对称零面积变换函数进行了比较研究。结果证明各个光谱峰都存在一个最优的对称零面积变换函数,但三种变换函数在各自的最优化参数下获得的峰位、峰宽一致;以实验室中LIBS和Raman光谱定量实验数据对该方法的测试还证明,对称零面积变换寻峰方法对信号的大范围动态变化适应性强,弱峰识别能力达到或优于人工识别水平,有望应用于将来的LIBS/Raman自动原位分析中去。     

庚酸甲酯高温燃烧化学动力学机理的系统简化和分析

采用详细化学反应动力学机理的系统简化方法, 对庚酸甲酯高温燃烧化学动力学机理进行了系统简化. 首先采用两步直接关系图法(Directed relation graph method, DRG)和主成分分析(Principle component analysis, PCA)方法对由1087个物种、4592步可逆反应组成的庚酸甲酯燃烧的详细机理进行框架简化, 得到了包含108个物种, 547步基元反应的框架机理. 在此框架机理基础上, 进一步采用计算奇异值摄动法(Computational singular perturbation, CSP)对框架机理进行时间尺度分析, 再选取30个准稳态物种, 采用准稳态近似(Quasi steady state approximation, QSSA)方法构建了包含78个物种、74步总包反应的全局简化机理. 模拟结果表明, 在较宽的参数范围内, 框架机理和全局简化机理均能重现庚酸甲酯高温燃烧时的点火延迟、物种浓度分布和熄火等燃烧特性. 此外, 基于框架机理阐明了庚酸甲酯高温燃烧的反应路径和对点火有重要影响的基元反应. 与详细机理相比, 框架机理保留了良好的精确性和全局性, 可以很好地反映庚酸甲酯的燃烧特性, 有助于对生物柴油的燃烧过程的理解.     

Investigation of quasi lateral-field-excitation on (yxl)-17° LiNbO3 single crystal

Quasi lateral-field-excitation (LFE) on LiNbO₃ crystal is investigated both theoretically and experimentally. It is found that when the driving electric field direction is parallel to the crystallographic X-axis of the piezoelectric substrate, (yxl)-17° LiNbO₃ LFE bulk acoustic wave devices work on quasi-LFE mode. The experimental results agreed with the theoretical prediction well. The results provide the cut of LiNbO₃ crystal for quasi-LFE bulk acoustic wave devices, which is important for designing high performance LFE sensors on LiNbO₃ substrates.     

气体激光器射频至微波放电激发的某些规律

本文研究了射频至微波激发的Xe和He-Ne原子激光器及CO₂分子激光器,结合各具体激光器的实验结果对其放电物理进行了讨论,提出获得高效率的关键是有效控制放电空间的电子能量,得出了一些有指导意义的结论.     

格上度量理论

通过对格上两种度量理论,即M．A．Erceg意义下的度量理论与史福贵意义下的度量理论的介绍与评述,展现出格上拓扑学中有关度量理论发展的概况,从这里可以看到,这一般拓扑学听度量理论比较,格上度量理论的研究有基本思想和研究方法上都有其独到之处。