Maximum Principle for the Regularized Schrödinger Operator

In this paper we present analogues of the maximum principle and of some parabolic inequalities for the regularized time-dependent Schrödinger operator on open manifolds using Günter derivatives. Moreover, we study the uniqueness of bounded solutions for the regularized Schrödinger–Günter problem and obtain the corresponding fundamental solution. Furthermore, we present a regularized Schrödinger kernel and prove some convergence results. Finally, we present an explicit construction for the fundamental solution to the Schrödinger–Günter problem on a class of conformally flat cylinders and tori.     

Thalidomide analogs from diamines: Synthesis and evaluation as inhibitors of TNF-alpha production

Fourteen thalidomide analogs bearing two phthalimido units were prepared in high yields (83-94%) by condensation of different diamines with phthalic or 3-nitrophthalic anhydride. An in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. The inhibition was higher for compounds bearing amino and nitro groups and was modulated by increasing the size of the spacers between the phthalimide groups.     

Aggregation and adsorption of reactive dyes in the presence of an anionic surfactant on mesoporous aminopropyl silica

A surface tension technique was used to determine the critical aggregation concentration (cac) of a yellow and a red dye in relation to the presence of the anionic surfactant sodium dodecylbenzene sulfonate (DBS) and to temperature changes in buffered aqueous solutions. The cac values of the yellow dye increase from 25 to 45 degrees C (from 41.37 to 50.32 mg L-1) and decrease from 45 to 55 degrees C (from 50.32 to 38.72 mg L-1). The cac values for the red dye/DBS aggregates decrease (from 124.52 to 88.50 mg L-1) from 25 to 55 degrees C. Adsorption of the two dyes onto a mesoporous aminopropyl silica (Sil-NH2) was also studied. The adsorption of the yellow dye increases with an increase in temperature from 25 to 55 degrees C. In the presence of DBS the adsorption on Sil-NH2 for the yellow dye decreases, and for the red dye increases from 25 to 55 degrees C. Adsorptions occurred below and above the cac of the anionic dyes/DBS aggregates. Adsorption of the dyes onto Sil-NH2 fitted well to the Langmuir, Freundlich, and Redlich-Peterson adsorption models. However, in the presence of DBS, only the Freundlich model fit the experimental adsorption data at low dye concentrations (less than 400 mg L-1). In this case, the Redlich-Peterson model was only fitted to the red dye adsorption data. The magnitude of the Dubinin-Radushkevich energetic parameters (E, from 7.00 to 15.00 kJ mol-1) indicates that the adsorption of the dyes onto Sil-NH2, in the absence and in the presence of DBS, is controlled by water adsorbed/dye in solution ion-exchange interactions. It is observed that the values of DeltaadsH are positive for both dyes and the values are quite similar to each other. The exception is the adsorption of the yellow dye in the presence of DBS, which is slightly exothermic. The DeltaadsG values are all negative. However, the interactions of the dyes with Sil-NH2 silica are more spontaneous in the presence of the surfactant. The positive adsorption entropy values (DeltaadsS) for the interaction of the dyes suggest that entropy is a driving force of the dye adsorptions. However, the entropic contribution is higher for the adsorptions in the presence of DBS. It was suggested that the chemical structures of the dyes play an important role in the formation of the dye/DBS aggregates and in dye adsorption onto the aminopropyl silica.     

Photo-induced destruction of giant vesicles in methylene blue solutions

We study the photodecomposition of phospholipid bilayers in aqueous solutions of methylene blue. Observation of giant unilamellar vesicles under an optical microscope reveals a consistent pattern of membrane disruption as a function of methylene blue concentration and photon density for different substrates supporting the vesicles.     

A Categorical View to Structural Complexity

In the present work we are interested in to provide a universal language for supporting formalisms to specify the approximation hierarchy system for an abstract NP‐hard optimization problem. This work grew from the idea of providing a categorical view of structural complexity to optimization problems. The direction is aimed towards actually exploring the connections among the structural complexity aspects and categorical concepts, which may be viewed in a high‐level, in a structuralistic sense. After introducing the optimization problems categories OPTS and OPT, as well as related questions, a formal system modelling the approximation hierarchy of a given optimization problem is provided, based on categorical shape theory. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

In Situ Incorporation of Praziquantel in Polymer Microparticles through Suspension Polymerization for Treatment of Schistosomiasis

Schistosomiasis is one of the major public health problems worldwide. Even though this is a common illness among preschool children in poor countries, treatment is carried out mainly through the administration of praziquantel tablets, which has some disadvantages, such as the strong bitter taste. As an alternative to overcome this problem, the development of new encapsulated praziquantel formulations is demanded. For this reason, suspension polymerizations are carried out for the in situ encapsulation of praziquantel into polymer microparticles, using methyl methacrylate (MMA) and cationic compounds (diethylaminoethyl methacrylate, DEAEMA, and dimethylaminoethyl methacrylate, DMAEMA) as comonomers. This technique allows for the preparation of polymer microparticles with high encapsulation efficiencies (>90%) with characteristic sizes ranging from 0.5 to 1500 µm. Drug release profiles show that praziquantel is released from poly(methyl methacrylate) microparticles slowly due to the existence of strong diffusional resistance. On the other hand, the addition of cationic comonomers renders polymer particles sensitive to pH variations, allowing for faster release of praziquantel in acidic environments, as found in the stomach.     

Thermography Applied to the Study of Fatigue Crack Propagation in Polycarbonate

Thermography was used to study the propagation of fatigue cracks during cyclic loading of pre-cracked SAE keyhole polycarbonate specimens. A micro-bolometer infrared camera (FLIR A655sc) and a commercially available software program (DeltaTherm2) were employed. The stress intensity factors were determined using a hybrid thermoelastic stress analysis (TSA) technique. The crack growth rate was determined via thermography using two different approaches. The first approach used the output of the crack-tip position from the developed TSA algorithm and the number of cycles between data sets. The second approach used temperature measurement as a new way to determine da/dN (crack growth rate) directly. As a result, da/dN vs ΔK (stress intensity factor range) graphs were plotted and fitted using Paris’ law. A comparison between the resultant da/dN vs ΔK curves and results found in the literature, as well as curves from the finite element method (FEM) simulations showed good agreement. The conclusion was that thermography is a very powerful tool that can detect, measure and monitor fatigue cracks in polycarbonate.     

A Comparison Between Shaker and Bioreactor Performance Based on the Kinetic Parameters of Xanthan Gum Production

Xanthan gum production was studied using sugarcane broth as the raw material and batch fermentation by Xanthomonas campestris pv. campestris NRRL B-1459. The purpose of this study was to optimize the variables of sucrose, yeast extract, and ammonium nitrate concentrations and to determine the kinetic parameters of this bioreaction under optimized conditions. The effects of yeast extract and ammonium nitrate concentrations for a given sucrose concentration (12.1–37.8 g L^?1) were evaluated by central composite design to maximize the conversion efficiency. In a bioreactor, the maximum conversion efficiency was achieved using 27.0 g L^?1 sucrose, 2.7 g L^?1 yeast extract, and 0.9 g L^?1 NH₄NO₃. This point was assayed in a shaker and in a bioreactor to compare bioreaction parameters. These parameters were estimated by the unstructured kinetic model of Weiss and Ollis (Biotechnol Bioeng 22:859–873, 1980) to determinate the yields (Y _P/S), the maximum growth specific rate (μ _max), and the saturation cellular concentration (X*). The parameters of the model (μ _max, X*, m, λ, α, and β) were obtained by nonlinear regression. For production of xanthan gum in a shaker, the values of μ _max and Y _P/S obtained were 0.119 h^?1 and 0.34 g g^?1, respectively, while in a bioreactor, they were 0.411 h^?1 and 0.63 g g^?1, respectively.     

Degradation of alachlor herbicide by gamma radiation from cobalt-60 in aqueous and alcohol solution

Alachlor has been widely used in agriculture all over the world. It is suggested that it may be a carcinogen and an environmental estrogen. The aim of this work was to verify the degradation the alachlor by gamma radiation. Gamma radiation from ⁶⁰Co was used to degrade the alachlor herbicide in water and methanol solution. The alachlor in water and alcohol solution in the concentration of 100 mgL⁻¹ was irradiated with doses of 0.25–50 kGy, at dose rate 5–6 and 2.7 kGyh⁻¹. High performance liquid chromatography was used as an analytical technique to determine the degradation rate of herbicide studied.     

Isolation of secondary metabolites from Hortia oreadica (Rutaceae) leaves through high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) with a two-phase solvent system (hexane–ethanol–acetonitrile–water 10:8:1:1, v/v) was applied to examine the leaves of Hortia oreadica, which afforded the known limonoid guyanin (1), the alkaloids rutaecarpin (2) and dictamnine (6), the dihydrocinnamic acid derivatives methyl 5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran-6-propanoate (3), 5,8-dimethoxy-2,2-dimethyl-2H-1-benzopyran-6-propanoic acid (4), together with the new E-3,4-dimethoxy-α(3-hydroxy-4-carbomethoxyphenyl)cinnamic acid (5). The recovery of compounds 1–6 was determined by comparison with LC-atmospheric pressure chemical ionization MS/MS data: 66.2%, 93.1%, 102.5%, 101.2%, 99.0% and 84.9%, respectively. Compound 3 showed IC₅₀ of 23.6 μM against Plasmodium falciparum and 15.6 μM against Trypanosoma brucei rhodesienses and was not toxic to KB cells (IC₅₀ > 100 μM).