抗坏血酸有机锗倍半氧化物的合成及抗癌活性研究

通过三氯锗仿与抗坏血酸分子的加成反应,合成了一种新型有机锗倍半氧化物,产物的结构通过元素分析、IR及UV光谱等方法进行了表征．生物活性实验表明合成物对小鼠S-180肿瘤生长具有显著的抑制作用．     

Purple passion fruit seeds (Passiflora edulis f. edulis Sims) as a promising source of skin anti-aging agents: Enzymatic,antioxidant and multi-level computational studies

This study aimed to assess the anti-aging potential of the ethanol extract of Passiflora edulis f. edulis Sims seeds, through in vitro determination of antioxidant activity and inhibition assays of some enzymes related to skin aging. Furthermore, using in silico methods (docking and molecular dynamics), were established the affinity of the majority compounds of the extract on the target enzymes, ending with the prediction of drug-likeness properties. The extract showed a high total phenolic content, represented mainly by flavonoids and phenolic acids, as well as a considerable antioxidant potential measured through the DPPH, FRAP and ORAC methods. In the inhibition assays of the enzymes collagenase, elastase and tyrosinase, IC₅₀ values presented were optimal. Docking studies demonstrated marked binding ability of the extract constituients (specially, fisetin, galangin and S-eriodictyol) to the Collagenase and Tyrosinase. Molecular dynamics validated the stability and rationality of these molecular docking studies, MM/PBSA calculations provide strong evidence for both their specific heavy binding and how enzyme-ligand complex stabilized inside the catalytic domain, and drug-likeness studies showed suitable dermato-pharmacokinetics indices for most of components of extract. Findings from this study suggest that ethanol extract of P. edulis has a great potential as an anti-aging agent.     

The Pursuit of an Implication for the Logics L3A and L3B

The authors of Beziau and Franceschetto (New directions in paraconsistent logic, vol 152, Springer, New Delhi, 2015) work with logics that have the property of not satisfying any of the formulations of the principle of non contradiction, Béziau and Franceschetto also analyze, among the three-valued logics, which of these logics satisfy this property. They prove that there exist only four of such logics, but only two of them are worthwhile to study. The language of these logics does not consider implication as a connective. However, the enrichment of a language with an implication connective leads us to more interesting systems, therefore we look for one implication for these logics and we study further properties that the logics obtain when this connective is added to these systems.     

Electrical and thermal behavior of non-ferrous noble metal electrodes exposed to MRI fields

MRI is a valuable tool in invasive epilepsy surgery evaluation. However, its use is limited due to concerns that under those conditions it may injure the brain. This study investigates the thermal and electrical behavior of electrodes exposed to MRI fields, using a phantom brain implanted with depth and grid electrodes. Voltages and temperatures were measured during various MRI scan sequences at electrodes whose numbers and orientations were varied in a pre-specified manner. Maximum SAR recorded during the scans was 1.5 W/kg. Temperature changes and DC voltages were negligible. Peak-to-peak voltage induction depended on the position, number of electrodes, MRI modality and sequence. Voltages exceeded 40 V at 63.6 MHz, only when electrode wires formed loops, reaching peak values of 72 V at RF. Estimated charge densities due to leakage currents were well within the safety limit for neural tissue, which is 30 microC/cm(2), even at the highest voltages. Although in the absence of loops, voltages and charge densities recorded in this study were, under most conditions within safe limits for brain tissue, their dependence on: a) the physical dimensions of electrode arrays; b) their position/orientation in reference to each other and to the plane of the magnetic field, and c) the MR sequence and slice thickness, may make these observations and conclusions not generalizable and thus not directly applicable to other conditions with regard to safety risks assessment.     

Differential resin-dentin bonds created after caries removal with polymer burs

The objective of this article was to investigate the effect of carbide and polymer burs caries removal methods on the bond strength of different adhesives to dentin. Resin restorations were performed in sound and caries-affected dentin, after using polymer or carbide burs and bonding with four different adhesive (Single bond, SB; Clearfil SE bond, SEB; FL-Bond II, FLB; and Fuji II-LC, FUJI). Microtensile bond strength (MTBS) was measured. Data were analyzed with ANOVA and Student-Newman-Keuls tests. Debonded surfaces were observed by scanning electron microscopy. Bonded interfaces were examined using light microscopy (Masson's trichrome staining). In sound dentin, MTBS was similar for SEB and SB, and higher than that of FLB and FUJI. Bond strength to carbide bur prepared dentin was similar for SB, SEB, and FLB; FUJI presented the lowest. SB applied on polymer bur excavated dentin presented similar values to those of the carbide bur group; MTBS attained by SEB, FLB, and FUJI decreased when bonding to dentin treated with polymer burs; FUJI yielded pretesting failures in all specimens. Polymer burs created a thick smear layer that was not infiltrated by tested self-etching agents. The bonding effectiveness of self-etching and glass-ionomer-like adhesives to dentin decreased when polymer burs were used.     

Vibrational spectroscopy and density functional theory calculations of poly‐D‐mannuronate and heteropolymeric fractions from sodium alginate

The tetrasaccharide of 1 → 4β‐D‐mannopyranuronate (MM) and the alternating tetrasaccharide of 1 → 4 b‐D‐mannopyranuronate and 1 → 4α‐L‐gulopyranuronate (MG) were analyzed based on density functional theory (DFT) by employing the Gaussian 03 W package. The molecular geometries were fully optimized by using the Becke's three‐parameter hybrid exchange functional combined with Lee–Yang–Parr correlation functional (B3LYP) and using a 6‐31G(d,p) basis set. The calculated IR spectrum of MM presents a band at 1093 cm⁻¹ for C C stretching vibration, which is in good agreement with the experimental observation (1096 cm⁻¹) for the polymannuronate fraction obtained by partial hydrolysis of sodium alginate extracted from the hybrid brown seaweed Lessonia–Macrocystis. The calculated value at 826 cm⁻¹for MM is in close agreement with the experimental value and confirms that this band is characteristic of polymannuronate blocks. Most of the bands in the IR spectrum are also present in the observed Raman spectrum of the polymannuronate fraction. The experimental IR spectrum of heteropolymeric fraction obtained by partial hydrolysis of sodium alginate shows absorbances similar to those calculated for the model tetrasaccharide (MG). Surface‐enhanced Raman scattering (SERS) allows differentiation between the homopolymeric and heteropolymeric fractions of sodium alginate. The SERS spectrum of the heteropolymeric fraction shows an enhanced signal at 731 cm⁻¹which is present in the calculated Raman spectrum of the tetrasaccharide MG at 729 cm⁻¹. This band is assigned to the ring‐breathing deformation of the β‐D‐mannopyranuronate and α‐L‐gulopyranuronate residues. Copyright © 2010 John Wiley & Sons, Ltd.     

Primordial superstrings and the origin of the universe

We discuss some of the cosmological implications of superstring theories. We pay particular attention to the issue of the initial state and its relationship withR-duality.     

Dithiafulvene (1,3-dithiole): Monomers and polymers

Monomers and polymers of 2-benzylidene-1,3-dithioles (dithiafulvenes) were synthesized. Polymerization of substituted dithiafulvenes with diacid chlorides, p-phenylene diisocyanate, or terephthalaldehyde yielded yellow polymers with inherent viscosities ranging from 0.10 to 0.21 dL/g.     

Chemical constituents from the colombian medicinal plant Niphogeton ternata

Two coumarins and one polyacetylene, 5-0-(3-chloro-2-hydroxy-3-methylbutyl)-8-methoxypsoralen (1), 2',3'-dihydro-jatamansin (2), and 10-chloro-1-heptadecene-4,6-diyne-3,8,9-triol (3), along with 15 known compounds (4-18), were isolated from the methanol extract of Niphogeton ternata. Their structures were elucidated by spectroscopy.