More compact invariant manifolds appearing in the non-linear coupling of oscillators

Near partially elliptic rest points of generic families of vector fields or transformations, many types of normally hyperbolic invariant compact manifolds can appear, diffeomorphic to intersections of quadrics. To cite this article: M. Chaperon et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Optimum experimental conditions of the brittle fracture technique for homogenisation of biological materials

Optimum experimental conditions for the brittle fracture technique applied in trace metal analysis of biological material are described. The efficiency of the technique was tested by sieve and radio-tracer experiments. Numerical results are presented for human placenta submitted to eight different grinding procedures.     

Game of two cars: Case of variable speed

A stochastic version of Isaacs's (Ref. 1) game of two cars is dealt with here. In this version, the pursuer, owing to thrust and drag forces, has a variable speed, whereas the evader's speed is constant. Also, the pursuer can maneuver as long as his speed is bounded by some lower and upper limits. The probability of interception, corresponding to optimal (saddle-point) feedback strategies, is computed and serves as a reference for evaluating the performance of four different versions of the proportional navigation pursuit law as well as two other strategies.     

A remark on Serrin’s Theorem

An approximation theorem for families of weakly coercive convex functions by means of countably many smooth families of convex functions is proved. As a consequence, the classical “three-fold” lower semicontinuity theorem for integral functionals of the Calculus of Variations by James Serrin is unified in one single statement.     

混杂配体金属簇合物的分子振动光谱与结构

由于原子簇化合物在催化，生物活性，功能材料等方面所呈现的重要性，使其成为无机和物理化学最重要的研究领域之一。文章中和谱学方法对一些具有混配体的过渡金属簇合物的结构及其两者之间的关系进行.     

Transport properties of a side-chain liquid-crystalline polymer. Poly(4-acryloyloxy biphenyl)

The transport properties of a side-chain liquid-crystalline polymer forming a smectic A phase have been investigated using dichloromethane as a permeant. Samples differing in the isotropization enthaoly were analyzed. A. Correlation between this thermal parameter and sorption has been found, while the diffusion coefficient is substantially the same in all samples. The results obtained can be explained in terms of a biphasis model in which a disordered permeable phase is present within the liquid-crystalline phase, which is impermeable to the diffusant molecules.     

Mössbauer studies in an external field of well-crystallized Al-maghemites made from hematite

A series of hematites with up to 15 mol% Al substitution was converted to maghemites by reduction in the presence of organic matter, followed by slow oxidation. The maghemites formed were studied by Mössbauer spectroscopy in an external field of 60 kOe at 4 K. This technique allows the determination of site occupancy as well as the canting angle. The spectra are in agreement with a model having both vacancies and Al only in the octahedral sites and small canting angles for both sites. A small dipolar field at the tetrahedral sites was required to fit the line shape. The data indicate that about 10 mol% Al may be a solubility limit in maghemite.     

Improved quantitation of 13-cis- and all-trans-acitretin in human plasma by normal-phase high-performance liquid chromatography.

A reliable analytical method has been developed for measurement of 13-cis- and all-trans-acitretin (Neotigason) in human plasma by normal-phase high-performance liquid chromatography, with ultraviolet detection. Human plasma was obtained after centrifugation of whole blood samples and deproteinized by ethanolic denaturation. After liquid-liquid extraction with water-n-hexane, and aliquot ws chromatographed on a silica column using isocratic elution with n-hexane-methylsalicylate-acetic acid (200:18:0.6, v/v). The wavelength was set at 360 nm, and for plasma samples a limit of quantification of 3-4 ng/ml was obtained. All manipulations were carried out under dim light conditions to prevent photoisomerization.     

On the index of composition of integers from various sets

Given an integer n ≥ 2, let λ(n) := (log n)/(log γ(n)), where γ(n) = Π _p|n p, stand for the index of composition of n, with λ(1) = 1. We study the distribution function of (λ(n) – 1) log n as n runs through particular sets of integers, such as the shifted primes, the values of a given irreducible cubic polynomial and the shifted powerful numbers. Research supported in part by a grant from NSERC. Research supported by the Applied Number Theory Research Group of the Hungarian Academy of Science and by a grant from OTKA. Professor M.V. Subbarao passed away on February 15, 2006. Received: 3 March 2006 Revised: 28 October 2006     

Enantioseparation of Dencichine and D-Isomer on L-Cysteine Derivative Phase by Ligand-exchange Chromatography

Dencichine (β-N-oxalyl-L-α, β-diaminopropionic acid, L-ODAP), a nonprotein amino acid, is a haemostatic agent present in important Chinese medicinal herbs such as Panax notoginseng, as well as other Panax species1. It was first isolated from the seeds …