Synthesis and spectral properties of substituted [1,2,4]oxadiazolo[4,5-a] [1,5] benzodiazepines

The preparation of twelve novel substituted [1,2,4]oxadiazolo[4,5-a][1,5]benzodiazepines which have potentially useful pharmacological properties; by 1.3-dipolar cycloaddition of benzonitrile oxides, generated in situ from benzohydroxamoyl chloride and triethylamine, to 1,5-benzodiazepine derivatives, is described. The structure of all products was corroborated by ir, ¹H-nmr, ¹³C-nmr and ms.     

The magnetic hyperfine field at140Ce in nickel

The hyperfine interaction of¹⁴⁰Ce in nickel has been investigated by the time-differential perturbed-angular-correlation technique (TDPAC). The probe was produced by isotope separator implantation of the fission product¹⁴⁰Xe, the ^- decay chain of which finally populates excited states of¹⁴⁰Ce.Different spin rotation spectra were observed before and after an 8 h annealing at 415°C. The analysis of the spectra led to the conclusion that the Ce ions were in the diamagnetic 4⁺ state. The dominant contributions to the hyperfine interaction are two different magnetic hyperfine fields: |H _hf ¹|=385±7 kOe and |H _hf ²|=276±12 kOe.H _hf ¹ disappears after annealing. The fraction of nuclei which observeH _hf ² is increased by the annealing procedure from 16% to 75%. It is assumed thatH _hf ¹ is the hyperfine field of CeNi in an unperturbed substitutional site andH _hf ² is attributed to Ce ions which have trapped a single vacancy.     

Multinuclear calixarene synthons with covalently linked aryl-palladium(II) complexes

New synthetic procedures have been developed for potentially useful metallacalixarene building blocks. The metal sites were covalently connected to calix[n]arenes (n = 4, 6) by oxidative addition of 4-iodobenzyl precursors to either Pd(PPh(3))(4) or Pd(2)(dba)(3)/tmeda (dba = dibenzylideneacetone) to furnish calixarene-modified aryl-Pd(II)I(L(n)()) complexes [L(n)() = bis-PPh(3) or N,N,N',N'-tetramethylethylenediamine (tmeda)]. Methods were explored for the selective preparation of mono-Pd(II)-calix[4]arene and di-Pd(II)-calix[n]arenes (n = 4 or 6) complexes and also for bifunctional calix[4]arene synthons with two Pd(II) complexes accompanied by 4-pyridylmethyl or 4-cyanobenzyl groups. The properties of the Pd(II)-calix[n]arenes were studied in detail by one- and two-dimensional NMR and mass spectrometric techniques. The X-ray molecular structures of two 4-iodobenzylcalix[4]arene precursors were also determined.     

Asymptotically extremal polynomials with respect to varying weights and application to Sobolev orthogonality

We study the asymptotic behavior of the zeros of a sequence of polynomials whose weighted norms, with respect to a sequence of weight functions, have the same nth root asymptotic behavior as the weighted norms of certain extremal polynomials. This result is applied to obtain the (contracted) weak zero distribution for orthogonal polynomials with respect to a Sobolev inner product with exponential weights of the form e−φ(x), giving a unified treatment for the so-called Freud (i.e., when φ has polynomial growth at infinity) and Erdös (when φ grows faster than any polynomial at infinity) cases. In addition, we provide a new proof for the bound of the distance of the zeros to the convex hull of the support for these Sobolev orthogonal polynomials.     

Sheaves and sheafification on Q-sites

We introduce noncommutative sites over a quantale, the so-called Q-sites, and define appropriate presheaves and sheaves over these. We show how most of the technical machinery which allows to construct sheaves associated to arbitrary presheaves in the commutative cases transposes to this setting. This allows us to define and study sheafification in this new, noncommutative context.     

在硅胶表面制备牛血红蛋白分子印迹聚合物

采用表面印迹法, 以乙烯基三甲氧基硅烷修饰的硅胶为载体, 丙烯酰胺为功能单体, N,N-亚甲基双丙烯酰胺为交联剂, 并将改性聚乙烯醇(PVA)作为辅助识别聚合物链(ARPCs)引入聚合体系中, 制备了牛血红蛋白分子印迹聚合物(MIP). 实验使用红外光谱分析了改性PVA的结构特征, 用扫描电镜(SEM)观察MIP的表面形貌, 考察了ARPCs的含量对MIP吸附性能的影响. 吸附动力学实验研究表明, 聚合体系中ARPCs的引入使MIP对模板牛血红蛋白(BHb)的吸附量明显提高|十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)结果显示, MIP对BHb的特异性吸附能力明显提高.     

An optimum velocimetry data display method

This paper proposes a method which determines the optimum grid size for interpolated velocimetry data, without making any priori assumptions about the velocity fields, the system used or analysis method. The method employs condition number as the main criterion for deciding the adequate grid size for a given data set. Data sets displayed accordingly are directly comparable, independently of differing experimental parameters or data processing methods. The discussion is based on computational fluid dynamics (CFD) data of flow past the near wake of a cylinder from which simulated PIV images were generated. These images were analysed with the proposed method and the velocity estimates compared to the CFD data. The method was also applied to a sample PIV image of turbulent flow in a baffled tube.     

Self-assembled pentamers and hexamers linked through quadruple-hydrogen-bonded 2-ureido-4[1H]-pyrimidinones

The preorganization of bifunctional 2-ureido-4-pyrimidinones mediated by either 1,3-substituted adamantane or meta-substituted phenylene ring linkers leads to the preferred formation of stable pentameric (1)(5) and hexameric (2)(6) assemblies, respectively. Despite the high binding constant of the 2-ureido-4-pyrimidinone dimers and the highly preorganized structure of the monomer, the predominant formation of cycles (1)(5) and (2)(6) in solution occurs only within a specific concentration range.