生物柴油中微量元素的测定

介绍了全谱直读电感耦合等离子体发射光谱法(ICP-OES)测定生物柴油中Na、K、Ca、Mg、Cu、Pb、Zn、Fe、Al、Cr、Mn、Ni、V、Si与P微量元素含量。结果表明,用该法测定生物柴油中微量元素含量可评价生物柴油品质,具有操作简便、全谱直读、可同时快速测定多元素、灵敏度与精准度高等优点。77%的平均基体加标回收率处于80%—130%之间,平均相对标准偏差不超过10%的占82%。该文可为制定生物柴油新微量元素指标和补充标准提供参考。     

Moduli Space of IIB Superstring and SUYM in AdS5 × S5

This paper consists of two parts. In part I, we interpret the hidden symmetry of the moduli space of IIB superstring on AdS₅×S⁵ in terms of the chiral embedding in AdS₅, which turns out to be the CP³ conformal affine Toda model. We review how the position μ of poles in the Riemann-Hilbert formulation of dressing transformation and the value of loop parameter μ in the vertex operator of affine algebra determine the moduli space of the soliton solutions, which describes the moduli space of the Green-Schwarz superstring. We show also how this affine SU(4) symmetry affinizes the conformal symmetry in the twistor space, and how a soliton string corresponds to a Robinson congruence with twist and dilation spin coefficients μ of twistor. In part II, by extending the dressing symmetric action of IIB string in AdS₅×S⁵ to the D₃ brane, we find a gauged WZW action of Higgs Yang-Mills field including the 2-cocycle of axially anomaly. The left and right twistor structures of left and right α-planes glue into an ambitwistor. The symmetry group of Nahm equations is centrally extended to an affine group, thus we explain why the spectral curve is given by affine Toda.     

Mode correlation of product pairs in the reaction OH+CD4-->HOD+CD3

The hydrogen abstraction reaction from methane by a hydroxyl radical produces two polyatomic molecules. Each product has several vibrational modes that characterize distinct, concerted motions of the constituent atoms of the molecule. This communication describes the first measurement that maps out the coincident information on how the mode of excitation of one product varies with that of the other co-product. Such information on mode correlation of product pairs is particularly appealing in that it provides intuitively a glimpse of the reaction paths by which the chemical transformation occurs.     

Versatile 2,5‐Pyridinedicarboxylate in Linking Transition‐Metal Atoms into 1D and 2D Coordination Polymers and Concomitant Polymorphs

By employing one bridging ligand, 2,5‐pyridinedicarboxylate (2,5‐pda^2?), in the presence or absence of another bridging ligand, 4,4′‐bipyridine (4,4′‐bpy), one one‐dimensional (1D) {[Co₂(2,5‐pda)(2,5‐Hpda)₂(4,4′‐bpy)(H₂O)₃]·6H₂O}_∞ ( 1 ) and two two‐dimensional (2D) coordination polymers, {[Cu₃(2,5‐pda)₃(H₂O)₃]·6H₂O}_∞ ( 2 ) and {[Co(2,5‐pda)(H₂O)]·2H₂O}_∞ ( 3 ) were synthesized. Complexes 2 and 3 are characterized as concomitant polymorphs from a one‐pot reaction at ambient temperature. A comparison of the coordination geometries of all neutral and anionic coordination polymers containing {M_x(2,5‐pda)_y(H₂O)_z}_∞ available to date is presented.     

On a Family of Diophantine Difference Equations

The family of Diophantine difference equations considered byJ. H. Conway, H. T. Croft, P. Erds and M. J. T. Guy can be solvedin closed form when the parameter is a prime. The associatedcharacterisation problem is shown to be related to the determinationof certain constants, which also happen to be coefficients inthe asymptotic formula for the associated exponential sum.     

Reactions of the cationic diruthenium carbonyl complex [Ru2(μ-dppm)2(CO)4(μ,η-O2CMe)] with bidentate ligands; intramolecularly assisted stereospecific synthesis via the second-sphere face-to-face π–π stacking interactions

The reactions of the diruthenium carbonyl complexes [Ru₂(μ-dppm)₂(CO)₄(μ,η²-O₂CMe)]X (X=BF₄⁻ (1a) or PF₆⁻ (1b)) with neutral or anionic bidentate ligands (L,L) afford a series of the diruthenium bridging carbonyl complexes [Ru₂(μ-dppm)₂(μ-CO)₂(η²-(L,L))₂]X_n ((L,L)=acetate (O₂CMe), 2,2′-bipyridine (bpy), acetylacetonate (acac), 8-quinolinolate (quin); n=0, 1, 2). Apparently with coordination of the bidentate ligands, the bound acetate ligand of [Ru₂(μ-dppm)₂(CO)₄(μ,η²-O₂CMe)]⁺ either migrates within the same complex or into a different one, or is simply replaced. The reaction of [Ru₂(μ-dppm)₂(CO)₄(μ,η²-O₂CMe)]⁺ (1) with 2,2′-bipyridine produces [Ru₂(μ-dppm)₂(μ-CO)₂(η²-O₂CMe)₂] (2), [Ru₂(μ-dppm)₂(μ-CO)₂(η²-O₂CMe)(η²-bpy)]⁺ (3), and [Ru₂(μ-dppm)₂(μ-CO)₂(η²-bpy)₂]²⁺ (4). Alternatively compound 2 can be prepared from the reaction of 1a with MeCO₂H–Et₃N, while compound 4 can be obtained from the reaction of 3 with bpy. The reaction of 1b with acetylacetone–Et₃N produces [Ru₂(μ-dppm)₂(μ-CO)₂(η²-O₂CMe)(η²-acac)] (5) and [Ru₂(μ-dppm)₂(μ-CO)₂(η²-acac)₂] (6). Compound 2 can also react with acetylacetone–Et₃N to produce 6. Surprisingly [Ru₂(μ-dppm)₂(μ-CO)₂(η²-quin)₂] (7) was obtained stereospecifically as the only one product from the reaction of 1b with 8-quinolinol–Et₃N. The structure of 7 has been established by X-ray crystallography and found to adopt a cis geometry. Further, the stereospecific reaction is probably caused by the second-sphere π–π face-to-face stacking interactions between the phenyl rings of dppm and the electron-deficient six-membered ring moiety of the bound quinolinate (i.e. the N-included six-membered ring) in 7. The presence of such interactions is indeed supported by an observed charge-transfer band in a UV–vis spectrum.     

Extremal Hosoya index and Merrifield-Simmons index of hexagonal spiders

For any graph G, let m(G) and i(G) be the numbers of matchings (i.e., the Hosoya index) and the number of independent sets (i.e., the Merrifield-Simmons index) of G, respectively. In this paper, we show that the linear hexagonal spider and zig-zag hexagonal spider attain the extremal values of Hosoya index and Merrifield-Simmons index, respectively.     

Methods for estimating the optimal dividend barrier and the probability of ruin

In applications of collective risk theory, complete information about the individual claim amount distribution is often not known, but reliable estimates of its first few moments may be available. For such a situation, this paper develops methods for estimating the optimal dividend barrier and the probability of ruin. In particular, two De Vylder approximations are explained, and the first and second order diffusion approximations are examined. For several claim amount distributions, the approximate values are compared numerically with the exact values. The De Vylder and diffusion approximations can be adapted to the more general situation where the aggregate claims process is a Lévy process with nonnegative increments.