Phenolic Compound Profile by UPLC-MS/MS and Encapsulation with Chitosan of Spondias mombin L. Fruit Peel Extract from Cerrado Hotspot—Brazil

Taperebá (Spondias mombin L.) is a native species of the Brazilian Cerrado that has shown important characteristics such as a significant phenolic compound content and biological activities. The present study aimed to characterize the phenolic compound profile and antioxidant activity in taperebá peel extract, as well as microencapsulating the extract with chitosan and evaluating the stability of the microparticles. The evaluation of the profile of phenolic compounds was carried out by UPLC-MS/MS. The in vitro antioxidant activity was evaluated by DPPH and ABTS methods. The microparticles were obtained by spray drying and were submitted to a stability study under different temperatures. In general, the results showed a significant content of polyphenols and antioxidant activity. The results of UPLC-MS/MS demonstrated a significant content of polyphenols in taperebá peel, highlighting the high content of ellagic acid and quercetin compounds. There was significant retention of phenolic compounds when microencapsulated, demonstrating high retention at all evaluated temperatures. This study is the first to microencapsulate the extract of taperebá peel, in addition to identifying and quantifying some compounds in this fruit.     

Structural Elucidation of an Atropisomeric Entcassiflavan-(4β→8)-Epicatechin Isolated from Dalbergia monetaria L.f. Based on NMR and ECD Calculations in Comparison to Experimental Data

A rare dihydoxyflavan-epicatechin proanthocyanidin, entcassiflavan-(4β→8)-epicatechin, was isolated from Dalbergia monetaria, a plant widely used by traditional people from the Amazon to treat urinary tract infections. The constitution and relative configuration of the compound were elucidated by HR-MS and detailed 1D- and 2D-NMR measurements. By comparing the experimental electronic circular dichroism (ECD) spectrum with the calculated ECD spectra of all 16 possible isomers, the absolute configuration, the interflavan linkage, and the atropisomers could be determined.     

Modified electrode with reduced graphene oxide/poly(3-hydroxyphenylacetic acid): a new platform for oligonucleotide hybridization

Journal of Solid State Electrochemistry - This paper reports a new platform for oligonucleotide hybridization, prepared by electropolymerization of 3-hydroxyphenylacetic acid onto gold electrode...     

Byte structure variable length coding (BS-VLC): a new specific algorithm applied in the compression of trajectories generated by molecular dynamics

Molecular dynamics is a well-known technique very much used in the study of biomolecular systems. The trajectory files produced by molecular dynamics simulations are extensive, and the classical lossless algorithms give poor efficiencies in their compression. In this work, a new specific algorithm, named byte structure variable length coding (BS-VLC), is introduced. Trajectory files, obtained by molecular dynamics applied to trypsin and a trypsin:pancreatic trypsin inhibitor complex, were compressed using four classical lossless algorithms (Huffman, adaptive Huffman, LZW, and LZ77) as well as the BS-VLC algorithm. The results obtained show that BS-VLC nearly triplicates the compression efficiency of the best classical lossless algorithm, preserving a near lossless behavior. Compression efficiencies close to 50% can be obtained with a high degree of precision, and the maximum efficiency possible (75%), within this algorithm, can be performed with good precision.     

Observation of a continuum-continuum interference hole in ultrafast dissociating core-excited molecules

The femtosecond dissociation of HCl after core excitation has been studied through the resonant Auger decay. The spectra contain contributions from decay occurring at both "molecular" and "atomic" internuclear distances. We have observed a new interference mechanism in these spectra: An atomic spectral line develops into a negative spectral contribution, a "hole," when detuning the excitation energy from the maximum of the Cl2p(-1)sigma(*) resonance. Resonant x-ray scattering theory quantitatively explains this behavior as due to a novel destructive continuum-continuum interference between molecular and atomic contributions to the Auger decay.     

N‐(Tri­phenyl­methyl­sulfanyl)­phthal­imide

The title compound, C₂₇H₁₉NO₂S, contains chains of fused (19) rings formed by intermolecular C—H·O=C hydrogen bonds and running along the [011] and [01] directions. These chains are linked through short intermol­ecular C—H·π contacts, giving rise to sheets. The conformation of the title compound is dominated primarily by the nearly orthogonal lone‐pair orbitals on the N and S atoms.     

95Mo NMR: a useful tool for structural studies in solution

Oxomolybdenum(VI) complexes containing diverse ligands from an electronic and topological point of view have been analysed by means of ⁹⁵Mo NMR in solution with the purpose of using this technique as a tool to study their coordination chemistry and reactivity. The relationship between the electronic density on the metal tuned by the electron‐donor ability of the coordinated ligands and the ⁹⁵Mo chemical shift has been proved for mono‐ and bimetallic complexes showing a hexa‐ or hepta‐coordination around the metal centre. The different origins of the signal broadening (associated either to the symmetry of the metallic polyhedron or to the presence of isomers or to the ligand de‐coordination) have been also considered to rationalise the obtained data. Copyright © 2009 John Wiley & Sons, Ltd.     

Combination of Raman, Infrared, and X-Ray Energy-Dispersion Spectroscopies and X-Ray Diffraction to Study a Fossilization Process

X-ray diffraction was combined with X-ray energy-dispersion, Fourier-transform infrared, and Raman spectroscopies to study the fossilization of a Cretaceous specimen of the plant Brachyphyllum castilhoi, a fossil from the Ipubi Formation, in the Araripe Sedimentary Basin, Northeastern Brazil. Among the possible fossilization processes, which could involve pyrite, silicon oxide, calcium oxide, or other minerals, we were able to single out pyritization as the central mechanism producing the fossil, more than 100 million years ago. In addition to expanding the knowledge of the Ipubi Formation, this study shows that, when combined with other experimental techniques, Raman spectroscopy is a valuable tool at the paleontologist’s disposal.     

A kinematical study of Kirchhoff-Rayleigh flow

Summary A method of calculating the separated flow of a viscous fluid is proposed, which allows to split up properly the boundary condition problem from the viscous phenomena. The theory is developed for the flow past a plate and yields wakes of finite extension having an underpressure which depends directly on the amount of vorticity diffusion and dissipation occurring in the fluid. Application of the method to real flows shows good agreement between the calculated and the measured velocity distributions in front of the plate and in the wake.

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Résumé Une méthode de calcul de l'écoulement décollé d'un fluide visqueux est proposée qui permet de séparer clairement le problème aux limites des phénomènes visqueux. La théorie est développée pour l'écoulement autour d'une plaque et donne des sillages de longueur finie ayant une dépression de culot directement dépendante de l'intensité de la diffusion et dissipation de la vorticité se produisant dans le fluide. L'application de la méthode à des écoulements réels montre une bonne concordance entre les répartitions de vitesse calculées et mesurées sur le devant de la plaque et dans le sillage.

     

Gold adatoms and clusters on PPV: An ab initio investigation

We have performed an ab initio investigation of the energetic, structural, electronic, and vibrational properties of Au atoms and clusters adsorbed on poly-p-phenylene vinylene (PPV) chains, Au(n)/PPV (with n =?1, 2, 6, 7, 10, and 12). We find that the Au(n)/PPV systems are energetically stable by 0.5 eV, compared with the isolated systems, viz., PPV chain and Au(n) clusters, thus supporting the formation of Au(n)/PPV nanocomposites. Further support to the formation of Au(n)/PPV has been provided by examining the vibrational properties of pristine PPV and Au(n)/PPV systems. In agreement with experimental measurements, we find a reduction on the in-plane vibrational frequency of C-C bonds of Au(n)/PPV, when compared with the same vibrational modes of pristine PPV. The electronic properties of isolated Au(n) clusters are modified when adsorbed on PPV. The highest occupied states of Au(n)/PPV are mostly concentrated on the Au(n) cluster, while the lowest unoccupied states are mainly localized along the PPV chain. The HOMO-LUMO energy gap of the Au(n)/PPV systems are smaller than the energy gap of the isolated systems, Au(n) clusters, and pristime PPV chains.