A simple synthesis of 2,4-diaryl-1,3,5-triazines

Summary Arylamidines2 react with 5-methoxymethylen-2,2-dimethyl-1,3-dioxan-4,6-dione5 to give 2,4-diaryl-1,3,5-triazines in moderate to good yields.5 can be comprehended as a formic acid derivative which transfers a C₁-building block. Other formic acid derivatives give only poor to moderate yields of triazines by treatment with amidines. The synthetic method is applicable to aromatic amidines.

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Eine einfache Synthese von 2,4-Diaryl-1,3,5-triazinen

Zusammenfassung Die Arylamidine2 reagieren mit 5-Methoxymethylen-2,2-dimethyl-1,3-dioxan-4,6-dion5 in guten Ausbeuten zu 2,4-Diaryl-1,3,5-triazinen. Verbindung5 kann als Derivat der Ameisensäure aufgefaßt werden, welches einen C₁-Baustein überträgt. Andere Derivate der Ameisensäure ergeben bei Umsetzung mit Amidinen nur schlechte Ausbeuten an Triazinen. Die beschriebene Methode ist auf aromatische Amidine anwendbar.

     

Titanium-Oxo Clusters, Versatile Nanobuilding Blocks for the Design of Advanced Hybrid Materials

Summary. This review describes the major advances made on titanium-oxo clusters chemistry and their derived hybrid materials. The main synthesis procedures, the cluster structures presented in literature, and the relation between the titanium-oxo clusters condensation degree and poisoning ratio are discussed. The tuned organo-functionalisation of the titanium-oxo based nanobuilding blocks allows to develop a LEGO-like chemistry, able to direct the assembling of a large variety of structurally well defined complex hybrid architectures.     

Electron－rich Polynuclear Transition Metal Clusters：Ⅱ．Synthetic and Structural Studies of Some Polynuclear Coinage Metal Cluster Compounds

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Playing with Structures at the Nanoscale: Designing Catalysts by Manipulation of Clusters and Nanocrystals as Building Blocks

The purpose of this Concept is to highlight some of the most recent and promising methods for the preparation of tailored catalysts by designing and preparing the component building blocks and by assembling them in a controlled fashion. We want to emphasize how rational design and synthesis of catalysts must be coupled to precise catalytic and structural characterization of the systems in an ideal feedback loop. New catalyst design and preparation techniques, dictated by information about the active sites that the specific application requires, are frequently available. The building blocks for developing these novel catalysts include colloidal methods for the preparation of uniform nanostructures, physical methods for rational assembly of the building blocks (Langmuir–Blodgett, liquid–air self‐assembly), and development of rational interactions between the building blocks for enhanced activity of the assemblies. These methods, which apply techniques normally used in other fields of nanotechnology to catalysis, offer exciting opportunities to help improve currently available catalytic systems in terms of activity, stability and selectivity.     

Silica dissolution as a route to octaanionic silsesquioxanes

The octaanion, [OSiO_1.5]₈^8? (OA) is a low cost, discrete nano silica particle that can be made directly from high surface area, amorphous silica reacted with Me₄NOH in water alcohol mixtures. It would be ideal if Me₄NOH could be formed in situ from, for example, Me₄NCl and NaOH, as long known in the literature. This process would reduce costs and enable recycling of Me₄NCl produced in the functionalization of OA with chlorosilanes, RMe₂SiCl, to form [RMe₂SiOSiO_1.5]₈ organic/inorganic hybrid nanobuilding blocks. Kinetic studies were conducted to assess base‐promoted dissolution of fumed silica (25 m 2 /g) as a function of concentrations, times, etc., to form the octaanion [OSiO_1.5]₈^8? using Me₄NOH, NaOH and mixtures of NaOH/Me₄NCl. Surprisingly, we find that small amounts of Me₄NCl greatly inhibit the dissolution reaction for reasons that are as yet unknown. Copyright © 2005 John Wiley & Sons, Ltd.     

The spectrum of α‐resolvable designs with block size four

Abstact: An α‐resolvable BIBD is a BIBD with the property that the blocks can be partitioned into disjoint classes such that every class contains each point of the design exactly α times. In this paper, we show that the necessary conditions for the existence of α‐resolvable designs with block size four are sufficient, with the exception of (α, ν, λ) = (2, 10, 2). © 2000 John Wiley & Sons, Inc. J Combin Designs 9: 1–16, 2001     

On e-cuspidal pairs of finite groups of exceptional Lie type

Let G be a simple, simply connected algebraic group of exceptional type defined over ${\mathbb{F}}_q$ with Frobenius endomorphism $F:G\to G$. Let $??q$ be a good prime for G. We determine the number of irreducible Brauer characters in the quasi-isolated ?-blocks of $G^F$. This is done by proving that generalized e-Harish-Chandra theory holds for the Lusztig series associated to quasi-isolated elements of $G^{?F}$.     

The three-dimensional origin of the classifying algebra

It is known that reflection coefficients for bulk fields of a rational conformal field theory in the presence of an elementary boundary condition can be obtained as representation matrices of irreducible representations of the classifying algebra, a semisimple commutative associative complex algebra.     

改进二元分布估计算法求解置换流水车间调度问题

针对置换流水车间调度这类组合最优化问题的求解,提出了一种改进二元分布估计算法(Improved binary estimation distribution algorithm, I-EDA)。算法以二元分布估计算法为架构,使用NEH(Nawaz-Enscore-Ham)启发式算法生成初始解,提高了初始解的质量;通过对优势解的统计采样构建位置矩阵模型和链接矩阵模型,依照两个矩阵模型的合并概率组合链接区块产生子代。提出了NEH插入式重组策略和基于位置概率的交换策略和两种全新局部搜索机制替代原二元分布估计算法的相邻交换法,以进一步筛选优势解。最后通过对Reeves标准测试集的仿真实验和算法比较验证了所提出算法的有效性。     

Generation of three-dimensional block-structured grids based on rotation of two-dimensional multiply connected cross sections

An algorithm for generating curvilinear block-structured grids in axisymmetric three-dimensional domains of any connectivity is developed. The organization of the connection between the blocks is automated. The grids constructed are used to compute ideal gas steady flows past axisymmetric bodies at a nonzero angle of attack.