A complete 1H and 13C NMR data assignment for four drimane sesquiterpenoids isolated from Drimys winterii

From the bark of Drimys winterii Forst., the drimane derivatives drimendiol, polygodial, isotadeonal and isodrimeninol were isolated. Complete and unambiguous 1H and 13C NMR chemical shift assignments of these compounds were achieved by COSY experiments, 13C/1H shift correlation diagrams and NOE experiments. Isotadeonal and isodrimeninol were found for the first time in this plant species.     

Terpenoids and phenolics from Plectranthus strigosus, bioactivity screening

Further studies on Plectranthus sp. (Lamiaceae) led to the isolation of terpenes and phenol esters from Plectranthus strigosus Benth. ent-16-Kauren-19-ol (1), ent-16-kauren-19-oic acid (2), xylopic acid (3), xylopinic acid (4), hinokiol (5), 4 beta,6 beta-dihydroxy-1 alpha,5 beta(H)-guai-9-ene (6) 4 beta,6 beta-dihydroxy-1 alpha,5 beta(H)-guai-10(14)-ene (7), mixtures of hexacosan-1,26-diol and octacosan-1,28-diol ferulate diesters (8), of esters from ferulic acid and fatty alcohols (9) and of esters from fatty acids and 2-(4-hydroxyphenyl)-ethanol (10) were for the first time isolated from this genus. Supplementary spectral data for 3,8 and parvifloron D (11) metabolites are also presented. A bioactivity study revealed herpetic inhibitory properties for (1) and (2), and antioxidant ability for (5) and (8) phenolic constituents.     

Ion-specific and reversible wetting of imidazolium-based minigels

Cross-linked imidazolium-based [poly(ViEtIm +Br -)] microparticles were synthesized, and their wetting properties were studied by optical microscopy, after addition of aqueous solutions of sodium halides. Particle wetting showed ion specificity due to counterion binding, described by Desnoyer's model. The interaction between anions and the microparticles allowed exchanging halogenides between them in a reversible way. A salt-independent characteristic wetting time was found as well as a decreasing power law with salt concentration, for the network diffusion coefficient. It modified the polymer network elasticity as ion concentration increased, making the network softer.     

Synthesis and biological evaluation in vitro and in silico of N-propionyl-N′-benzeneacylhydrazone derivatives as cruzain inhibitors of Trypanosoma cruzi

Molecular Diversity - An N-acylhydrazone scaffold has been used to develop new drugs with diverse biological activities, including trypanocidal activity against different strains of Trypanosoma...     

Use of diverging or converging arrangement of plates for the control of chaotic mixing in symmetric sinusoidal plate channels

This paper presents an experimental flow visualization study of the effect that the variation of converging or diverging angles plays in the flow field of a symmetric sinusoidal channel. The experiments were performed in a water tunnel and the visualization technique was laser illumination of seeded particles whose traces were captured using long time exposure photography. Geometrical parameters such as wave amplitude, wavelength and distance between plates were kept constant, while the Reynolds number and divergence or convergence angles were varied. It was found from the experiments that the divergence of the plates is a good way to promote chaotic mixing in channel flows, as the flow becomes more unstable for diverging channels. For the case of converging channels, the flow becomes very stable even for large values of the Reynolds number. These results were compared with those of a channel formed by a pair of sinusoidal parallel plates.     

Stereochemistry modulates the catalytic hydrogenolysis of nitrile-substituted cyclopropanes

The study of Raney-Ni catalyzed chemo- and regioselective hydrogenolysis of diastereomeric nitrile-substituted spirocyclopropyloxindoles is presented. The chemoselectivity outcome of the reaction is remarkably influenced by the relative stereochemistry of the nitrile-substituted spirocyclopropyloxindoles. Chemo- and high regioselective cyclopropane ring-opening occurs from the syn diastereomers to give the corresponding 3-propylacetamide derivatives. X-ray crystallographic studies together with DFT model chemistry calculations indicate that chemo- and regioselectivity are directly dependent on the bond length asymmetry of the cyclopropane ring.     

Highly dispersed encapsulated AuPd nanoparticles on ordered mesoporous carbons for the direct synthesis of H2O2 from molecular oxygen and hydrogen

AuPd nanoparticles (<3 nm) have been encapsulated on the pores of a nanostructured CMK-3 carbon prepared by a nanocasting procedure. This material has been shown to be an excellent catalyst for the direct synthesis of hydrogen peroxide from molecular hydrogen and oxygen.     

Synthesis of fractal light pulses by quasi-direct space-to-time pulse shaping

We demonstrated a simple diffractive method to map the self-similar structure shown in squared radial coordinate of any set of circularly symmetric fractal plates into self-similar light pulses in the corresponding temporal domain. The space-to-time mapping of the plates was carried out by means of a kinoform diffractive lens under femtosecond illumination. The spatio-temporal characteristics of the fractal pulses obtained in this way were measured by means of a spectral interferometry technique assisted by a fiber optics coupler (STARFISH). Our proposal allows synthesizing suited sequences of focused fractal femtosecond pulses potentially useful for several current applications, such as femtosecond material processing, atomic, and molecular control of chemical processes or generation of nonlinear effects.     

Nanocrystalline cobalt oxide: a catalyst for selective alkane oxidation under ambient conditions

Nanocrystalline cobalt oxide activates propane, yielding propene at room temperature and pressure.