The first homologous series of self-assembled aryl bromo- and aryl cyanocuprates, -argentates,and -aurates; MLi(2)XAr(2) (M = Cu(I), Ag(I), Au(I); X = Br,C(triple bond)N; Ar = [C(6)H(4)CH(2)N(Et)CH(2)CH(2)NEt(2)-2]-)

Reaction of 2 molar equiv of the diamine chelated aryllithium dimers Li(2)(C(6)H(4)[CH(2)N(Et)CH(2)CH(2)NEt(2)]-2)(2) (Li(2)Ar(2)) with the appropriate metal bromide allows the synthesis of the first homologous series of monomeric group 11 bromoate complexes of type MLi(2)BrAr(2) (M = Cu (7), Ag (8), Au (9)). Both in the solid state and in solution, the bromocuprate 7 is isostructural with the bromoargentate 8. The crystal structures of 7 and 8 consist of a MLi(2) core, and each of the two aryl ligands bridges via electron-deficient bonding between the group 11 metal and one Li atom (d(C(ipso)-M) = 1.941(4) (mean) and 2.122(4) (mean) A, for 7 and 8, respectively). The bromine atom exclusively bridges between the two lithium atoms. Each of the ortho-CH(2)N(Et)CH(2)CH(2)NEt(2) moieties is N,N'-chelate bonded to one lithium (d(N-Li) = 2.195(5) and 2.182(0) (mean) A for 7 and 2.154(8) and 2.220(1) (mean) A for 8). Although the MLi(2)BrAr(2) compounds are neutral higher-order -ate species, the structure can also be regarded as consisting of a contact ion pair consisting of two ionic fragments, [Li-Br-Li](+) and [Ar(2)M](-), which are interconnected by both Li-N,N'-chelate bonding and a highly polar C(ipso)-Li interaction. On the basis of NMR and cryoscopic studies, the structural features of the bromoaurate 9 are similar to those of 7 and 8. A multinuclear NMR investigation shows that the bonding between the [Li-Br-Li] and [Ar(2)M] moieties is intermediate between ionic and neutral with an almost equally polarized C(ipso)-Li bond in 7, 8, and 9. Similar reactions between M(C(triple bond)N) and 2 molar equiv of LiAr yield the analogous 2:1 cyanoate complexes of type MLi(2)(C(triple bond)N)Ar(2) (M = Ag (10), Au (11)). Multinuclear NMR studies show that the cyanoate complexes 10 and 11 are isostructural with the bromoate complexes 7, 8, and 9. This paper illustrates that these cyanoaurates may serve as excellent model complexes to gain more insight into the structure of 2:1 cyanocuprates in solution.     

Simultaneous quantification of total medium- and long-chain fatty acids in human milk by capillary gas chromatography with split injection

Four different quantification methods for the capillary gas chromatographic determination of medium-chain fatty acids (6:0-12:0) and myristic acid in human milk samples, using a split injector, were compared. Odd-carbon-numbered fatty acids (5:0-17:0) were added as internal standards. Each medium-chain fatty acid and myristic acid was calculated on the basis of: the peak area of the internal standard with one methylene group less; the peak area of the internal standard with one methylene group more; half the sum of the peak areas of the internal standards with one methylene group less and more (bracketting method); the peak area of 17:0. The peak-area ratio of each analyte and 17:0 in a standard was found to be subject to an unacceptably high coefficient of variation. From the methods using internal standards with one methylene group more and less, the bracketting method was found to be the best, resulting in recoveries close to 100%, with the lowest coefficients of variation. The method was applied for the determination of the fatty acid composition of mature milk samples of 47 Cura?aoan women.     

Pion absorption in the deuteron

Pion absorption in the deuteron is mainly sensitive to the absorption form factor, the propagator of the rescattered pion and the off-shell behaviour of the pion-nucleon interaction. Current ideas about them are difficult to reconcile with existing experimental data.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.     

A Proposal for Positive Cooperativity in Anion-Cation Binding in Yttrium and Lutetium Complexes Based on o-Amino-Substituted Phenolate Ligands. On the Way to Coordination Polymers by Self-Assembly. Molecular Structures of [ClLu(OAr)(3)Na] (X-ray) and [ClY(OAr')(3)Y(OAr')(3)Na] (X-ray and (89)Y-NMR)

Unique hetero(poly)metallic complexes [ClM(OAr)(3)Na] (M = Lu (3a), Y (3b)) and [ClY(OAr')(3)Y(OAr')(3)Na] (4) containing the bis (OAr = OC(6)H(2)(CH(2)NMe(2))(2)-2,6-Me-4) and mono (OAr' = OC(6)H(4)(CH(2)NMe(2))-2) o-amino-substituted phenolate ligands have been synthesized and characterized by NMR ((1)H, (13)C, and (89)Y) and X-ray structure determinations (3a and 4). Crystals of 3a are triclinic, space group P&onemacr;, with unit cell dimensions a = 10.706(1) ?, b = 14.099(2) ?, c = 18.882(3) ?, alpha = 93.48(1) degrees, beta = 99.49(1) degrees, gamma = 108.72(11) degrees, and Z = 2. The chlorine, lutetium, and sodium atoms in 3a lie on a pseudo-3-fold axis ( angleCl-Lu.Na = 177.82(5) degrees ) around which the three phenolate ligands are arranged in such a way that a "propeller-like" molecule with screw-type chirality results. Crystals of 4 are triclinic, space group P1, with unit cell dimensions a = 11.411(4) ?, b = 13.325(4) ?, c = 13.599(4) ?, alpha = 88.91(3) degrees, beta = 65.44(2) degrees, gamma = 72.77(3) degrees, and Z = 1. In 4 the chlorine, the two yttrium and the sodium atoms lie on a pseudo-3-fold axis (Cl-Y(1).Y(2).Na: angleCl-Y.Y = 179.36(8) degrees and angleY.Y.Na = 178.38(10) degrees ) around which the six phenolate ligands are arranged in two shells of three ligands. One shell bridges the yttrium atoms in an asymmetric fashion, while the second shell bridges the second yttrium and the sodium atom, resulting in two shells of opposite screw-type chirality. (1)H, (13)C, and (89)Y (for 3b and 4) NMR confirmed that the structures found for 3a and 4 in the solid state are retained in solution. For 4 (89)Y NMR showed two separate resonances (202.4 and 132.4 ppm), with (2)J(YY) = 0.4 Hz. The formation of 3a and 3b is described as resulting from positive cooperativity in anion-cation bonding: coordination of chloride anion to a neutral metal tris(phenolate) leads to preorganization of available binding sites in the resulting anionic complex for the binding of the sodium cation. In 4 this cooperativity is the driving force for the self-assembly of an anionic bimetallic molecular structure with available, preorganized binding sites for the capture of the cation. A proposal is made to use these observations for the possible synthesis of new coordination polymers.     

Optimization of turbulent jet mixing

We introduce an approach for controlling jet mixing that combines direct numerical simulation of an incompressible jet flow with stochastic optimization procedures. The jet is excited with helical and combined helical and axial actuations at the orifice. An objective function that measures the spreading of the jet evaluates the performance of the actuation parameters. The optimization procedure searches for the best actuation by automatically varying the parameters and calculating their objective function value. Solutions that lead to a pronounced spreading of the jet are found within reasonable time, although the evaluation of the objective function, the DNS of the jet, is expensive. For a jet flow at low Reynolds number the performance of different search algorithms (simulated annealing and evolution strategies) is evaluated. We compare various objective functions based on radial velocity and the concentration of a passive scalar, including functions that penalize actuation with high amplitudes. We find that a combined axial and helical actuation is much more efficient with respect to jet mixing than a helical actuation alone.     

Spectral characteristics of three styles of Croatian folk singing

This paper examines the differences between three Croatian folk singing styles, namely klapa, ojkanje, and tarankanje. In order to factor out singer-specific properties, each of the styles was performed by the same 12 professional male singers. The 36 performances were analyzed with a long-term average spectrum (LTAS) method from which direct effects of the pitch distribution were removed. After factoring out each singer's average, the 36 pitch-corrected LTAS contours were reduced to a two-dimensional representation in two ways: (1) a principal-component analysis and (2) a graphical plot of spectral slope versus speaker's formant strength. Both ways clearly separate the three styles. The spectrum of the klapa style turns out to be similar to that of speech. The ojkanje style is extremely loud and shows two spectral peaks: a sharp one tuned at twice the fundamental frequency and appropriate for long-distance communication on mountain slopes, and a broad one around 3.5 kHz, reminiscent of a speaker's formant. The tarankanje style has a very flat spectrum implemented by vocal pressedness and nasality, which is appropriate for blending into or imitating the timbral characteristics of the sopile folk instrument.     

基于Hilbert-Huang变换的金融收益政策风险因子识别方法

针对政策可能对金融收益产生风险问题,提出了基于Hilbert-Huang变换方法的政策风险因子识别检测方法。通过经验模态分解,Hilbert-Huang频谱分析得到金融时间序列的时域和频域特征,通过与量化处理后的政策进行匹配得到政策产生的异常波动情况,从而实现对政策因子风险的识别与处理。研究结果对于探究宏观政策对金融收益的影响具有重要参考意义。最后以国家房地产调控政策与地产指数为算例,发现本研究提出的方法识别精度高,具有非常好的应用前景。     

The reaction of diarylzinc compounds with silver salts : Synthesis and characterization of arylsilver(I) compounds

The reaction of diarylzinc compounds with silver(I) salts is an excellent method of preparing stable arylsilver compounds in quantitative yields. These compounds have been characterized by IR and ¹H and ¹³C NMR spectroscopy Cryoscopy in benzene shows phenylsilver to be polymeric, and the methyl-substituted phenylsilver compounds to be trimers. All the compounds appear to be associated via aryl groups bridging between two silver atoms. As in the case of the corresponding copper compounds, the data point to the existence of rotation of these aryl groups around the C¹C⁴ axis. C¹C⁴ axis.     

Preparation and crystal structure of [μ-Ni(C5H5)P(C6H5)3] [μ-C5H5] [ZnC5H5]2, a nickel-bridged cyclopentadienylzinc dimer

[μ-Ni(C₅H₅)P(C₆H₅)₃] [μ-C₅H₅]₂ [ZnC₅H₅]₂ has been obtained from the reaction of Cp₂Zn with Ni(COD)₂ in the presence of Ph₃P and its structure determined by X-ray crystallography. It consists of two cyclopentadienylzinc moieties bridged by the Ni atom of a CpNiPPh₃ group and by a Cp group. A possible mechanism for the formation of the compound is discussed.