Investigating microcrystalline cellulose crystallinity using Raman spectroscopy

Cellulose - Microcrystalline cellulose (MCC) is a semi-crystalline material with inherent variable crystallinity due to raw material source and variable manufacturing conditions. MCC crystallinity...     

2-(Glucosylthio)ethyl Groups as Potential Biolabile Phosphate- Protecting Groups of Mononucleotides

The in vitro anti-HIV effects and the stability studies of mononucleoside phosphotriester derivatives 1 – 3 of 3′-azido-3′-deoxythymidine (AZT) containing 2-(glucosylthio)ethyl moieties as potential biolabile phosphate-protecting groups are reported. The results of the anti-HIV evaluation demonstrate that the described compounds act via the release of the free nucleoside analogue and cannot be considered as mononucleotide prodrugs (pronucleotides). These data can be related to the lack of substrate affinity of these derivatives towards target-enzymes as corroborated by decomposition studies in various media and experiments with a purified β-D glucosidase.     

On composite formal power series

Let be a holomorphic map from to defined in a neighborhood of such that . If the Jacobian determinant of is not identically zero, P. M. Eakin et G. A. Harris proved the following result: any formal power series such that is analytic is itself analytic. If the Jacobian determinant of is identically zero, they proved that the previous conclusion is no more true.

The authors get similar results in the case of formal power series satifying growth conditions, of Gevrey type for instance. Moreover, the proofs here give, in the analytic case, a control of the radius of convergence of by the radius of convergence of .

RÉSUMÉ. Soit une application holomorphe de dans définie dans un voisinage de et vérifiant . Si le jacobien de n'est pas identiquement nul au voisinage de , P.M. Eakin et G.A. Harris ont établi le résultat suivant: toute série formelle telle que est analytique est elle-même analytique. Si le jacobien de est identiquement nul, ils montrent que la conclusion précédente est fausse.

Les auteurs obtiennent des résultats analogues pour les séries formelles à croissance contrôlée, du type Gevrey par exemple. De plus, les preuves données ici permettent, dans le cas analytique, un contrôle du rayon de convergence de par celui de .

     

On weakly eutactic forms

We make precise some properties of the Hermite function in relationwith the Morse theory introduced by Avner Ash in his papers‘On eutactic forms’,Canad. J. Math. 29 (1977) 1040–1054and ‘On the existence of eutactic forms’,Bull. LondonMath. Soc. 12 (1980) 192–196, and with the cellular decompositionof the space of positive definite quadratic forms. We also establisha link between Ash's and Bavard's mass formulae.     

An economic theory of public facilities in space

This paper deals with the determination of the number and locations of facilities in which a public service is made available to consumers. The solutions obtained by planning and voting are characterized and compared for both a benefit taxation, based on consumers' locations, and an income taxation.     

The specific contribution of phosphorus in dendrimer chemistry

Besides properties commonly found for all types of dendrimers, phosphorus-containing dendrimers possess some specific properties seldom or never found for other types of dendrimers. Emphasis will be put on these specificities.     

List of subject

We report the high resolution emission (S₁ → S₀, T₁ → S₀) and laser single site singlet excitation (S₁ ← S₀) spectra for the various insertion sites of coronene in n-heptane cooled to 1.5 K. The observation of site splitting of doubly degenerate vibrations and weak electric dipole forbidden 0, 0 bands in the S₁ → S₀ and T₁ → S₀ spectra indicates that the ground state, the first excited singlet and lowest triplet states are all distorted. In these spectra, the intensity distribution of the various sites in the 0, 0 bands suggests that the distortion is different from site to site but similar in S₀, S₁ and T₁. Identical ordering of the sites in S₁ S₀ and S₁ S₀ spectra as well as the observation of weak shifts in the vibrational frequencies in the two states implies the absence of strong pseudo Jahn-Teller forces in the first excited singlet state. We propose, further, that this is also true for the triplet state. This conclusion is supported by the similarity in zero-field splitting parameters of coronene and deuterated coronene. Taken together, these results indicate strongly that the distortion of coronene in n-heptane is primarily crystal field induced and is not greatly changed upon excitation of the molecule to its lowest excited states.