Natural Compounds and Products from an Anti-Aging Perspective

Aging is a very complex process that is accompanied by a degenerative impairment in many of the major functions of the human body over time. This inevitable process is influenced by hereditary factors, lifestyle, and environmental influences such as xenobiotic pollution, infectious agents, UV radiation, diet-borne toxins, and so on. Many external and internal signs and symptoms are related with the aging process and senescence, including skin dryness and wrinkles, atherosclerosis, diabetes, neurodegenerative disorders, cancer, etc. Oxidative stress, a consequence of the imbalance between pro- and antioxidants, is one of the main provoking factors causing aging-related damages and concerns, due to the generation of highly reactive byproducts such as reactive oxygen and nitrogen species during the metabolism, which result in cellular damage and apoptosis. Antioxidants can prevent these processes and extend healthy longevity due to the ability to inhibit the formation of free radicals or interrupt their propagation, thereby lowering the level of oxidative stress. This review focuses on supporting the antioxidant system of the organism by balancing the diet through the consumption of the necessary amount of natural ingredients, including vitamins, minerals, polyunsaturated fatty acids (PUFA), essential amino acids, probiotics, plants’ fibers, nutritional supplements, polyphenols, some phytoextracts, and drinking water.     

Periodic mesoporous organosilica with large heterocyclic bridging groups

Periodic mesoporous organosilica with a heterocyclic bridging group of large molecular weight, tris[3-(trimethoxysilyl)propyl]isocyanurate, is reported. Incorporation of an organic moiety into the silica framework afforded material attractive for adsorption of mercury and related heavy metal ions from aqueous solutions.     

Circularly polarized x rays: another probe of ultrafast molecular decay dynamics

Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s → a(1g)* inner-shell excitation by circularly polarized x rays in SF(6). In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.     

Effects of the material gradation on the SIFs of a crack in a 2-D FGM plate under thermal shock

Crack analysis of linear coupled thermoelasticity in two-dimensional, isotropic, non-homogeneous and linear elastic functionally graded materials subjected to thermal shock is performed by using a boundary-domain element method. The material parameters are assumed to be continuous functions of the spatial coordinates. Fundamental solutions of linear coupled thermoelasticity for the corresponding isotropic, homogeneous and linear elastic solids in Laplace-transformed domain are applied in the boundary-domain integral formulation. A collocation method is implemented for the numerical solution. Numerical examples for an exponential gradation of the material parameters are presented and discussed. The influences of the material gradation on the stress intensity factors are investigated. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stabilization of polystyrene by styrylquinoline containing methacrylates

Abstract

The thermostability of polysterene with/without new styrylquinoline containing methacrylic fragments has been described in the present work. Polystyrene and copolymers based on styrene and new methacrylic styrylquinoline containing monomers were synthesized by free radical thermoinitiated polymerization in the presence of 2,2′-azobisisobutyronitrile (1?wt%) as initiator at inert atmosphere. The impact of 2-[2-(4-methoxyphenyl)ethenyl]quinolin-8-yl 2-methylpropyl-2-enoate (М1), 2-(2-phenylethenyl)quinolin-8-yl 2-methylpropyl-2-enoate (М2), 2-[2-(4-nitrophenyl)ethenyl]quinolin-8-yl 2-methylpropyl-2-enoate (М3) on thermal stability of polystyrene was investigated. The thermostability of polystyrene and copolymers ST:M1, ST:M2, ST:M3 were studied by dynamic thermograviametric analysis. It was shown that destruction of polystyrene with corresponding units M1-M2 starts at 41–42°С higher, than reference polystyrene.     

Nitrone cycloadditions to 1,2-diphenylcyclopropenes and subsequent transformations of the isoxazolidine cycloadducts

1,3-Dipolar cycloaddition of C-aryl,N-aryl (or N-methyl) nitrones with a number of 1,2-diphenylcyclopropenes substituted at the C(3) position occurs with the formation of expected "normal" cycloadducts (with N-methylnitrones) and products of their subsequent transformations. Among them are corresponding alpha-acetophenyl aziridines and tetra (or penta) -arylpyrroles. Aziridines and the normal cycloadducts can be also thermally converted to such arylpyrroles with moderate to good yields. Substitution at the C(3( position of cyclopropenes by an electron acceptor group decreases the reactivity of cyclopropenes.     

Separation of Pyrimidine Bases on a HPLC Stationary RP-18 Phase Coated with Calix[4]resorcinarene

Lipophilic calix[4]resorcinarenes, derived from lauryl aldehyde and resorcinol, are strongly adsorbed on the modified silica gel RP-18 for HPLC chromatography, while their solutions are passed through the column. The calix[4]resorcinarene-coated RP-18 phases were found to be useful beds for HPLC separation of uracil, thymine and cytosine.     

Metallic nanostructures in a polymer matrix and substrate fabrication and structural characterization

Metal nanostructures are of considerable interest in the field of plasmonics and metamaterials and could have a wider impact if they are successfully embedded in a stable, inert and flexible polymer matrix. Fabrication of such structures is challenging for a variety of reasons including thermal stability, material compatibility with processing steps and general handling of material. In this work we have demonstrated the fabrication of metal nanostructures and embedded them in a polymer. Furthermore, these structures were fabricated on a flexible polymer membrane and detached from a carrier substrate. Characterization of these structures was performed with SEM, TEM and EDS.     

Misfit-Dislocation Induced Surface Morphology of InGaAs/GaAs Heterostructures

The correlation between the surface cross-hatched morphology and the interfacial misfit dislocations in partially relaxed InGaAs/GaAs heterostructures was studied by means of atomic force microscopy and electron-beam induced current mode in a scanning electron microscope. A close correspondence between the misfit-dislocation network at the interface and the surface morphology shows that the cross-hatch development results primarily from the misfit-dislocation generation. Statistical analysis of the surface roughness reveals an anisotropy in strain relaxation of the epitaxial layers, which results from an asymmetry in the misfit-dislocation formation.     

Cage-like structure formation during sol–gel polymerization of glycidyloxypropyltrimethoxysilane

The sol–gel polymerization of 3-glycidyloxypropyltrimethoxysilane (GTMS) was followed by size exclusion chromatography and ²⁹Si NMR. Extensive non-random cyclization under formation of polyhedral cycles – cubic cages – predominates at the beginning of the reaction. Structure growth of polysilsesquioxanes proceeds by combining the incompletely condensed cage frameworks. The extent of the cage formation increases with dilution and the amount of water and depends appreciably on a catalyst. The cage fraction was isolated from a reaction mixture using preparative size exclusion chromatography and identified by ²⁹Si NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). High content of polyhedral cages prevents gelation of the trifunctional GTMS monomer. Reaction of pendant epoxy groups is much slower; however, at a late reaction stage the epoxy hydrolysis can be significant. Under some conditions, like base catalysis, polysilsesquioxane clusters are crosslinked by intermolecular condensation of SiOH with hydrolyzed epoxy groups and the system gels. The cage with epoxide functionalities may serve as a rigid precursor of crosslinking.