Regeneration studies on solid acids for batch reactor. Alkylation of isobutane with 2-butene

The regeneration of solid acid catalysts used in alkylation was studied using cal-ad. It was found that an acid site strength of −ΔH=32 kcal/mol is needed to catalyze the reaction.     

Spectra of unicyclic graphs

Unicyclic graphs are discussed in the context of graph orderings related to eigenvalues. Several theorems involving lexicographical ordering by spectral moments as well as the ordering by the largest eigenvalue are proved. An appendix contains a table of the 89 unicyclic graphs on eight vertices together with their spectra, spectral moments and characteristic polynomials.Carnegie Research Fellow, University of Stirling, 1985–86.     

Fractional exclusion statistics in general systems of interacting particles

I show that fractional exclusion statistics is manifested in general interacting systems and I calculate the exclusion statistics parameters. Most importantly, I prove that the mutual exclusion statistics parameters are proportional to the dimension of the Hilbert space on which they act [D.V. Anghel, J. Phys. A: Math. Theor. 40 (2007) F1013].     

Does Maternal Treatment with Zidovudine Affect Changes in Mandibles of Newborns? Laser Induced Fluorescence Study

The influence of antiretroviral drug zidovudine treatment during pregnancy on mandible development in newborn rats was studied. The fluorescence of mandibles from 7-, 14- and 28-days old individuals was measured by means of fiber-optical fluorescence analyzer with 407 nm laser excitation. Obtained results revealed disturbing effect of maternal zidovudine administration on mandible fluorescence intensity which should decrease with bone development. Small changes in fluorescence of porphyrin forms are maintaining in the first month of newborns life while the changes observed in 440–585 nm range disappear.     

Simultaneous pH and Temperature Measurements Using Pyranine as a Molecular Probe

Steep variations in concentration and temperature frequently occur in small fluid compartments such as those found in cells or microfluidic devices. A quantitative characterization of concentration and temperature gradients is therefore required before these systems can be fully understood. Although different spatially resolved fluorescence methods have been developed to measure either the temperature or the concentration of ions such as proton or calcium, often concentration measurements depend on temperature and vice versa. Here, we describe a method allowing simultaneous measurement of pH and temperature. This method is based on the detection of the blinking of the fluorescent pH indicator pyranine, a process due to its alternating between a basic form and an acidic form. Fluorescence correlation spectroscopy allows measuring both the protonation and deprotonation rates of pyranine, and each pair of rates can be uniquely related to a pair of pH and temperature values. We show, however, that the relationship between rates, pH and temperature, is very sensitive to the presence of other acid-base molecules in solution. We also show that it is influenced by the overall ionic strength of the solution, in a manner that depends on buffer composition.     

On the Bergman Theory for Solenoidal and Irrotational Vector Fields. II. Conformal Covariance and Invariance of the Main Objects

This is a continuation of our work (González-Cervantes et al. in On the Bergman theory for solenoidal and irrotational vector fields. I. General theory. Operator theory: advances and applications. Birkhauser, accepted) where for solenoidal and irrotational vector fields theory as well as for the Moisil–Théodoresco quaternionic analysis we introduced the notions of the Bergman space and the Bergman reproducing kernel and studied their main properties. In particular, we described the behavior of the Bergman theory for a given domain whenever the domain is transformed by a conformal map. The formulas obtained hint that the corresponding objects (spaces, operators, etc.) can be characterized as conformally covariant or invariant, and in the present paper we construct a series of categories and functors which allow us to give such characterizations in precise terms.