Adaptive memory in multistart heuristics for multicommodity network design

This paper focuses on the use of different memory strategies to improve multistart methods. A network design problem in which the costs are given by discrete stepwise increasing cost functions of the capacities installed in the edges is used to illustrate the contributions of adaptive memory and vocabulary building strategies. Heuristics based on shortest path and maximum flow algorithms are combined with adaptive memory in order to obtain an approximate solution to the problem in the framework of a multistart algorithm. Furthermore, a vocabulary building intensification mechanism supported by the resolution of a linear program is also explored. Numerical experiments have shown that the proposed algorithm obtained the best known solutions for some instances in the literature. These results show the contribution of each memory component and the effectiveness of their combination.     

Theoretical analysis of aggregation in block‐copolymer films: The optical signature

We focus this work on the theoretical investigation of the block‐copolymer poly[oxyoctyleneoxy‐(2,6‐dimethoxy‐1,4phenylene‐1,2‐ethinylene‐phenanthrene‐2,4diyl) named as LaPPS19, recently proposed for optoelectronic applications. We used for that a variety of methods, from molecular mechanics to quantum semiempirical techniques (AM1, ZINDO/S‐CIS). Our results show that as expected isolated LaPPS19 chains present relevant electron localization over the phenanthrene group. We found, however, that LaPPS19 could assemble in a π‐stacked form, leading to impressive interchain interaction; the stacking induces electronic delocalization between neighbor chains and introduces new states below the phenanthrene‐related absorption; these results allowed us to associate the red‐shift of the absorption edge, seen in the experimental results, to spontaneous π‐stack aggregation of the chains. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Biogenesis of the reservosomes of Trypanosoma cruzi.

Reservosomes are endocytic compartments found in the posterior region of epimastigotes of Trypanosoma cruzi. In the differentiation from trypomastigotes to epimastigotes (reverse metacyclogenesis in vitro), one has the rare opportunity of following the biogenesis of an endocytic compartment. Metacyclic trypomastigotes incubated in LIT medium highly enriched with fetal calf serum differentiated directly to epimastigotes. In recently differentiated epimastigotes, acidic organelles were found in round compartments spread along the cell body, whereas in control epimastigotes they were found in reservosomes located in the posterior region. Ultrastructural analysis of intermediate forms showed that the cytostome and reservosomes appeared before differentiation to epimastigotes was completed. Many polymorphic reservosomes, with or without lipid inclusions, were observed from the anterior portion of the cell body, in close relationship with the Golgi complex, to the posterior region. Endocytic tracers were observed in the cytostome, flagellar pocket, vesicles, and newly formed reservosomes. Cruzipain, the main protease of T. cruzi, was localized in newly formed reservosomes and in vesicles budding from the trans-Golgi network that seem to fuse with reservosomes. Ingested gold-labeled albumin and cruzipain colocalized in recently formed reservosomes. Endocytosis and immunocytochemical analysis suggested that the endocytic and the secretory pathways may contribute to reservosome formation.     

On the fractional integral of Weyl inL p

This work has been partially supported by D.G.C.Y.T., grant PS88-0115, Spain     

New approach for natural products screening by real-time monitoring of hemoglobin hydrolysis using quartz crystal microbalance

The hemoglobin (Hb) released from erythrocytes is a primary nutritive component for many blood-feeding parasites. The aspartic protease cathepsin D is a hemoglobinase that is involved in the Hb degradation process and is considered an interesting target for chemotherapy intervention. However, traditional enzymatic assays for studying Hb degradation utilize spectrophotometric techniques, which do not allow real-time monitoring and can present serious interference problems. Herein, we describe a biosensor using simple approach for the real-time monitoring of Hb hydrolysis as well as an efficient screening method for natural products as enzymatic inhibitors using a quartz crystal microbalance (QCM) technique. Hemoglobin was anchored on the quartz crystal surface using mixed self-assembled monolayers. The addition of the enzyme caused a mass change (frequency shift) due to Hb hydrolysis, which was monitored in real time. From the frequency change patterns of the Hb-functionalized QCM, we evaluated the enzymatic reaction by determining the kinetic parameters of product formation (k_cat). The QCM enzymatic assay using immobilized human Hb was shown to be an excellent approach for screening possible inhibitors in complex mixtures, opening up a new avenue for the discovery of novel inhibitors.     

Protein unfolding studied by fluorescence methods and electrical impedance spectroscopy: the cases of Cratylia mollis and Concanavalin A

This work is dedicated to the investigation of the prevailing molecular interactions between Cratylia mollis (Cramoll) and Concanavalin A (Con A) lectins and ionic (sodium dodecylsulfate, SDS) and non-ionic (Triton X-100, TX-100) surfactants, where we have used electrical impedance spectroscopy to map the dielectric characteristics of mixed lectin/surfactant solutions. The disorder induced in the lectin conformation is proportional to the extent of the access of the surfactant to the fluorophore present in the protein, resulting in its progressive unfolding. The complete unfolding of the lectin is associated to the formation of micelles in the core of the protein, each one of them containing a large number of detergent molecules, and therefore the process can be accompanied by measuring the electrical response of the binary surfactant/lectin system. For instance, the change in the real part of the impedance as a function of the relative concentration of the surfactant in the binary solution exhibits a breaking in its linear behavior that can be taken as indicative of a qualitative change in the environment surrounding the protein residue. We consider these results strong evidence in favor of using impedance spectroscopy methods for the analysis of protein-surfactant associations and for the characterization of the interactions that must prevail when the protein unfolds as the relative surfactant concentration is increased in aqueous solutions of these binary systems.     

Natural products and Chagas' disease: a review of plant compounds studied for activity against Trypanosoma cruzi

Here, we review studies that have investigated the activity of plant-derived compounds against Trypanosoma cruzi, the etiologic agent of Chagas’ disease. In the last decade, more than 300 species belonging to almost 100 families have been evaluated for activity, and here we describe the compounds isolated; 85 references are cited.     

Antitrypanasomal activity of novel benzaldehyde-thiosemicarbazone derivatives from kaurenoic acid

A series of new thiosemicarbazones derived from natural diterpene kaurenoic acid were synthesized and tested against the epimastigote forms of Trypanosoma cruzi to evaluate their antitrypanosomal potential. Seven of the synthesized thiosemicarbazones were more active than kaurenoic acid with IC?? values between 2-24.0 mM. The o-nitro-benzaldehyde-thiosemicarbazone derivative was the most active compound with IC?? of 2.0 mM. The results show that the structural modifications accomplished enhanced the antitrypanosomal activity of these compounds. Besides, the thiocyanate, thiosemicarbazide and the p- methyl, p-methoxy, p-dimethylamine, m-nitro and o-chlorobenzaldehyde-thiosemicarbazone derivatives displayed lower toxicity for LLMCK? cells than kaurenoic acid, exhibing an IC?? of 59.5 mM.     

Thermal studies on solid 1,4-bis(3-carboxy-3-oxo-prop-1-enyl) benzene of lighter trivalent lanthanides

Solid-state compounds of general formula Ln₂L₃·nH₂O, where L represents 1,4-bis(3-carboxy-3-oxo-prop-1-enyl)benzene and Ln = La, Ce, Pr, Nd, Sm, were synthesized. Complexometric titrations with EDTA, thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and infrared spectroscopy have been employed to characterize and to study the thermal behavior of these compounds in dynamic air atmosphere. The results led to information about the composition, dehydration, crystallinity, and thermal decomposition of the synthesized compounds.     

Trypanocidal activity of oxoaporphine and pyrimidine-β-carboline alkaloids from the branches of Annona foetida Mart. (Annonaceae)

Phytochemical investigation of the branches of Annona foetida Mart. led to isolation from the CH(2)Cl(2) extract of four alkaloids: Atherospermidine (1), described for the first time in this species, liriodenine (2), O-methylmoschatoline (3), and annomontine (4). Their chemical structures were established on the basis of spectroscopic data from IR, MS, NMR (1D and 2D), and comparison with the literature. Compounds 2-4 showed potent trypanocidal effect when evaluated against epimastigote and trypomastigote forms of Trypanosoma cruzi.