Classification of Congeneric and QSAR of Homologous Antileukemic S–Alkylcysteine Ketones

Based on a set of six vector properties, the partial correlation diagram is calculated for a set of 28 S-alkylcysteine diazomethyl- and chloromethyl-ketone derivatives. Those with the greatest antileukemic activity in the same class correspond to high partial correlations. A periodic classification is performed based on information entropy. The first four characteristics denote the group, and the last two indicate the period. Compounds in the same period and, especially, group present similar properties. The most active substances are situated at the bottom right. Nine classes are distinguished. The principal component analysis of the homologous compounds shows five subclasses included in the periodic classification. Linear fits of both antileukemic activities and stability are good. They are in agreement with the principal component analysis. The variables that appear in the models are those that show positive loading in the principal component analysis. The most important properties to explain the antileukemic activities (50% inhibitory concentration Molt-3 T-lineage acute lymphoblastic leukemia minus the logarithm of 50% inhibitory concentration Nalm-6 B-lineage acute lymphoblastic leukemia and stability k) are ACD logD, surface tension and number of violations of Lipinski’s rule of five. After leave-m-out cross-validation, the most predictive model for cysteine diazomethyl- and chloromethyl-ketone derivatives is provided.     

Modelling Monomer/Disc Composites Phase Behaviour

Summary: A model developed by Balazs' group to explain the phase behaviour of polymer/clay composites is extended to obtain an expression for the free energy of polymer/thin disc mixtures. Phase diagrams for monomer/disc mixtures are built by minimizing the free energy and calculating the chemical potentials of the three system components. Via the comparison of the diagrams, it is studied the effects of nanodisc size and interaction parameters on mixture stability and attained morphology. The performed predictions between monomers and discs give criteria that advance the properties of the mixture. Changes in monomer concentration and interaction parameters provide a means to prevent van der Waals-induced agglomeration. The model takes into account, in only a rather approximate manner, the long-range interactions between clay sheets.     

Intersection of Yager’s implications with QL and D-implications

The intersection of the different classes of implications is one of the most popular topics nowadays due to the large number of construction methods of these operators. In this paper, we deal with the characterization of the intersection of Yager’s implications with QL and D-implications. Some initial steps have already been made with the intersection of Yager’s implications with (S, N), R and QL-implications, however some questions remain unanswered. In particular, we solve an open problem related to the characterization of those implications that are both QL-implications and f-generated implications with f(0) < ∞, fully determining the expression of the QL-implications generated by a continuous t-conorm that belong to the considered intersection. Furthermore, we perform a similar study for D-implications and finally, we study the intersection of Yager’s implications with their φ-conjugates.     

Experimental Studies for Modelling the Phase Behaviour of Monomer/Polymer/Disc Composites

Nanoparticles do not stabilize the mixtures of epoxy monomer (prepolymer)/thermoplastic modifier (PS) and the ones of thermoplastic modifier dispersed within cured epoxy matrix. A small amount of thermoplastic co-polymer poly(styrene-b-methyl methacrylate) [P(S-b-MMA)] of MMA 4–22 wt.%, mixed with PS, makes compatible the mixtures with monomer epoxy precursor and cured epoxy matrix. The mixtures of cured epoxy matrix with thermoplastic consisting of PS and P(S-b-MMA), with nanofil 1%, are stable: the instability produced by the nanofil is overcome by the stability provided by the co-polymer. A model by Balazs' group to explain the phase behaviour of polymer/clay composites is extended.     

Construction of Surfaces with Parallelism Conditions

In this paper we define the notion of pseudo-parallel parameterized surfaces, extending that of offset surfaces. Then we consider the problem of fitting a set of scattered points with a surface pseudo-parallel to a given reference surface. We propose a method of solution based on a modified version of the classical smoothing D ^m -splines over a bounded domain. The convergence of the method is established and some numerical examples are given.     

Sur l'erreur d'approximation par éléments finis en utilisant la méthode des plaquettes splines

Résumé. On établit des majorations de l'erreur d'approximation par éléments finis à partir de données de Lagrange pour des fonctions appartenant à un espace de Sobolev d'ordre convenable, lorsque les degrés de liberté sont approchés à l'aide de la méthode des plaquettes splines introduite par A. Le Méhauté (cf. [13], [14], [15]). Les résultats obtenus s'appliquent notamment à la construction de surfaces de classe . Received May 29, 1995 / Revised version received August 20, 1995     

An Improved Force Field for O2, CO and CN Binding to Metalloporphyrins

Parametrization of a molecular-mechanics program to include terms specific for five- and six-coordinate transition metal complexes is applied to heme complexes. The principal new feature peculiar to five and six coordination is a term that represents the effect of electron-pair repulsion modified by the ligand electronegativity and takes into account the different possible structures of complexes. The model system takes into account the structural differences of the fixing centre in the haemoglobin subunits. The customary proximal histidine is added. The macrocycle heme IX is wholly considered in our model. The calculations show clearly that certain conformations of heme IX–histidine models are much more favourable than others for fixing O₂. From the O₂ binding in haemoglobin and myoglobin and in simple Fe porphyrin models it is concluded that the bent O₂ ligand is best viewed as bound superoxide, O₂ ^?. Rotation of axial ligands are practically free. A small modification of the model in both crystal and protein matrix affects the orientation of the ligands in experimental systems.