Suberitane sesterterpenoids from the Antarctic sponge Phorbas areolatus (Thiele, 1905)

Following ecological and chemical screenings, the Antarctic sponge Phorbas areolatus was chemically investigated for the first time. Three new suberitane derivatives named isosuberitenone B, 19-episuberitenone B, and isoxaspirosuberitenone were identified together with the known compounds suberitenones A and B, and oxaspirosuberitenone after a thorough inspection of their NMR data. These compounds were found to exhibit moderate cytotoxic activity and their presence in this sponge rules out their use as a chemotaxonomic marker for Suberites sponges.     

Porous framework of T2[Fe(CN)6]·xH2O with T=Co, Ni, Cu, Zn, and H2 storage

The materials under study were prepared from aqueous solutions of ferrocyanic acid and salts of the involved transition metals and their crystal structure solved and refined from X-ray powder diffraction data. Complementary information from thermogravimetric, infrared and Mössbauer data was also used for the structural study. Three different crystal structures were found: hexagonal (P-3) for Zn with the zinc atom coordinated to three N ends of CN groups plus a water molecule, cubic (Pm-3m) for Ni and Cu, and monoclinic (P2₁/m) for Co. For Ni and Cu the obtained solids have an open channel framework related to 50% of vacancies for the building unit, [Fe(CN)₆]. In the as-synthesized material the framework free volume is occupied by coordinated and hydrogen-bonded water molecules. These of hexacyanoferrates (II) have received certain attention as prototype of materials for the hydrogen storage. In the anhydrous phase of Ni and Cu, 50% of the metal (T) coordination sites, located at the cavities surface, will be available to interact with the hydrogen molecule. However, when the crystal waters are removed the porous frameworks collapse as it is suggested by H₂ and CO₂ adsorption data. For Co, a structure of stacked layers was found where the cobalt atoms have both tetrahedral and octahedral coordination. The layers remain together through a network of hydrogen-bonding interactions between coordinated and weakly bonded water molecules. No H₂ adsorption was observed in the anhydrous phase of Co. For Zn, the porous framework remains stable on the water removal but with a system of narrow channels and a small available volume, also inaccessible to H₂.     

Hausdorff dimension and conformal measures of Feigenbaum Julia sets

We show that contrary to anticipation suggested by the dictionary between rational maps and Kleinian groups and by the ``hairiness phenomenon', there exist many Feigenbaum Julia sets whose Hausdorff dimension is strictly smaller than two. We also prove that for any Feigenbaum Julia set, the Poincaré critical exponent is equal to the hyperbolic dimension . Moreover, if , then . In the stationary case, the last statement can be reversed: if , then . We also give a new construction of conformal measures on that implies that they exist for any , and analyze their scaling and dissipativity/conservativity properties.

     

Rheological complexity in simple chain models

Dynamical properties of short freely jointed and freely rotating chains are studied using molecular dynamics simulations. These results are combined with those of previous studies, and the degree of rheological complexity of the two models is assessed. New results are based on an improved analysis procedure of the rotational relaxation of the second Legendre polynomials of the end-to-end vector in terms of the Kohlrausch-Williams-Watts (KWW) function. Increased accuracy permits the variation of the KWW stretching exponent beta to be tracked over a wide range of state points. The smoothness of beta as a function of packing fraction eta is a testimony both to the accuracy of the analytical methods and the appropriateness of (eta(0)-eta) as a measure of the distance to the ideal glass transition at eta(0). Relatively direct comparison is made with experiment by viewing beta as a function of the KWW relaxation time tau(KWW). The simulation results are found to be typical of small molecular glass formers. Several manifestations of rheological complexity are considered. First, the proportionality of alpha-relaxation times is explored by the comparison of translational to rotational motion (i.e., the Debye-Stokes-Einstein relation), of motion on different length scales (i.e., the Stokes-Einstein relation), and of rotational motion at intermediate times to that at long time. Second, the range of time-temperature superposition master curve behavior is assessed. Third, the variation of beta across state points is tracked. Although no particulate model of a liquid is rigorously rheologically simple, we find freely jointed chains closely approximated this idealization, while freely rotating chains display distinctly complex dynamical features.     

Application of nanoparticles for the enhancement of latent fingerprints

Two different types of nanoparticles dissolved in organic solution, gold stabilized by n-alkanethiols and CdSe/ZnS stabilized by n-alkane-amine, adhere preferentially to the ridges of latent fingerprints; the gold deposits catalyze silver electroless deposition from "Silver Physical Developer" (Ag-PD), an aqueous solution containing silver colloids stabilized by cationic surfactants, to form dark impressions of the ridge details; the hydrophobic capped gold nanoparticles significantly improve the intensity and clarity of the developed prints compared with Ag-PD alone; finger marks treated with CdSe/ZnS nanoparticles can be viewed directly, due to their fluorescence under UV illumination.     

Linear stability analysis of the natural convection in inclined rotating parallel plates

The linear stability analysis of the natural convection in a rectangular tilted infinite cavity filled with a Boussinesq fluid subject to Coriolis force is presented. The bottom and top surfaces have fixed temperatures. Both unstable and stable thermal conditions are studied (heated from below and heated from above respectively). The rotation axis passes through the center and it is orthogonal to the hot and cold surfaces. The stability equations were solved using the Tau–Chebyshev spectral method. The critical Rayleigh number and critical wave number were obtained for several rotation rates and different orientation of convective oblique rolls in a range of inclination of the cavity from 0 to 120 degrees. The stability analysis show that rotation rate affects the basic velocity profile, onset of convection, wave number and critical orientation of convective rolls.     

Co-Treatment of Purified Annatto Oil (Bixa orellana L.) and Its Granules (Chronic®) Improves the Blood Lipid Profile and Bone Protective Effects of Testosterone in the Orchiectomy-Induced Osteoporosis in Wistar Rats

This study aimed to evaluate and compare the effects of co-treatment with purified annatto oil (PAO) or its granules (GRA, Chronic^®) with that of testosterone on the orchiectomy-induced osteoporosis in Wistar rats. After surgery, rats were treated from day 7 until day 45 with testosterone only (TES, 7 mg/kg, IM) or TES + PAO or GRA (200 mg/kg, p.o.). The following parameters were evaluated: food/water intake, weight, HDL, LDL, glucose, triglycerides (TG), total cholesterol (TC), alkaline phosphatase levels, blood phosphorus and calcium contents, femur weight, structure (through scanning electron microscopy), and calcium content (through atomic absorption spectrophotometry). Our results show that orchiectomy could significantly change the blood lipid profile and decrease bone integrity parameters. Testosterone reposition alone could improve some endpoints, including LDL, TC, bone weight, and bone calcium concentration. However, other parameters were not significantly improved. Co-treatment with PAO or GRA improved the blood lipid profile and bone integrity more significantly and improved some endpoints not affected by testosterone reposition alone (such as TG levels and trabeculae sizes). The results suggest that co-treatment with annatto products improved the blood lipid profile and the anti-osteoporosis effects of testosterone. Overall, GRA had better results than PAO.     

Toward Tailor‐Made Biocide Materials Based on Poly(propylene)/Copper Nanoparticles

A set of poly(propylene) composites containing different amounts of copper nanoparticles (CNP) were prepared by the melt mixed method and their antimicrobial behavior was quantitatively studied. The time needed to reduce the bacteria to 50% dropped to half with only 1 v/v % of CNP, compared to the polymer without CNP. After 4 h, this composite killed more than 99.9% of the bacteria. The biocide kinetics can be controlled by the nanofiller content; composites with CNP concentrations higher than 10 v/v % eliminated 99% of the bacteria in less than 2 h. X‐ray photoelectron spectroscopy did not detect CNP at the surface, therefore the biocide behavior was attributed to copper in the bulk of the composite.

     

Simultaneous analysis of esters and acylglycerols in biodiesel by high-performance liquid chromatography with refractive index detection

Currently, gas chromatography (GC) is the most widely used analytical technique to verify the quality of biodiesel in relation to its glyceride and fatty acid methyl ester (FAME) contents, even though its use has some disadvantages, such as damage to the injector and column caused by the presence of trace levels of triacylglycerols in biodiesel, which means the column has to be replaced every 3 months; the need for the sample to be derivatized, which, while improving chromatographic separation, also increases analysis time; and the use of several imported standard solutions. The main aim of this work was to use high-performance liquid chromatography with refractive index detection (HPLC-RI) to simultaneously quantify the glyceride (mono, di, and triacylglycerol) and FAME contents of biodiesel. The proposed method showed satisfactory results when compared with those obtained by the reference method (GC), particularly when these results were within the working ranges of the reference method. The proposed method using HPLC-RI is therefore promising and could potentially be used instead of the reference method, since the results it yielded were statistically equivalent, with 95% confidence, to the results obtained by the reference method (GC) for the nine samples of commercial biodiesel analyzed in this study.