Free Radical Scavenging and Cellular Antioxidant Properties of Astaxanthin

Astaxanthin is a coloring agent which is used as a feed additive in aquaculture nutrition. Recently, potential health benefits of astaxanthin have been discussed which may be partly related to its free radical scavenging and antioxidant properties. Our electron spin resonance (ESR) and spin trapping data suggest that synthetic astaxanthin is a potent free radical scavenger in terms of diphenylpicryl-hydrazyl (DPPH) and galvinoxyl free radicals. Furthermore, astaxanthin dose-dependently quenched singlet oxygen as determined by photon counting. In addition to free radical scavenging and singlet oxygen quenching properties, astaxanthin induced the antioxidant enzyme paroxoanase-1, enhanced glutathione concentrations and prevented lipid peroxidation in cultured hepatocytes. Present results suggest that, beyond its coloring properties, synthetic astaxanthin exhibits free radical scavenging, singlet oxygen quenching, and antioxidant activities which could probably positively affect animal and human health.     

Adiabatic and intrinsic modes for wave propagation in guidingenvironments with longitudinal and transverse variation: formulation andcanonical test

For an application of the present formalism to continuously refracting media, see ibid., vol.39, no.8, p.1137-42 (1991). Adiabatic modes (AMs) fail in cutoff regions and can be made uniform by intrinsic modes (IMs), which are synthesized by a spectral continuum of AMs. Extending previous studies, the AM-IM format is applied here to longitudinally varying guiding environments wherein transverse confinement is due to a transversely graded trapping index of refraction instead of, or in addition to, the presence of boundaries or interfaces. After the general formulation of the problem, which involves the choice of best coordinate system, the solution strategy is applied to a simple test case, a conventional wedge waveguide treated in (nonseparable) rectangular and in (separable) cylindrical coordinates, in order to assess the numerical accuracy of the AM-IM formalism, and of various approximate versions of it     

Adiabatic and intrinsic modes for wave propagation in guidingenvironments with longitudinal and transverse variation: continuouslyrefracting media

The adiabatic and intrinsic mode formalism for nonuniform propagation environments, developed and tested in a companion paper (ibid., vol.39, no.8, p.1130-36, 1991), is applied to continuously refracting media. The first example involves a guiding refractive index profile with transverse and longitudinal, but coordinate separable, variation that may be regarded as a prototype for this class of waveguides. A second example involves a nonseparable profile with a guiding-to-antiguiding transition that converts an initially well trapped mode into a radiated beam. Both examples demonstrate the problems encountered in achieving a good parametrization for tracking mode-like wave phenomena under rather general conditions     

Palladium-catalyzed homogeneous coupling reactions of steroids with organostannanes

Direct and carbonylative coupling reactions of various steroid derivatives possessing iodo- and bromo-alkenyl moiety (17-iodo-androst-16-ene, 1, 17-bromoandrost-2,16-diene, 2, 17-iodo-4-aza-4-methylandrost-16-en-3-one, 3, 17-iodo-4-azaandrost-16-en-3-one, 4) with vinyltributylstannane and ethynyltributylstannane were carried out in the presence of various palladium catalysts. While carbonylation took place only with vinyltributylstannane, 17-vinyl-, and 17-ethynyl-delta 16 steroids were produced via direct coupling with vinyltributylstannane and ethynyltributylstannane, respectively. Activities of some catalysts based on Pd(0) and Pd(II) precursors were compared, and Pd(PPh3)4 was found to be superior to other complexes in most cases. In the coupling of 17-iodoandrost-16-ene with organostannanes Pd2(dba)3 + 8 AsPh3 in situ catalyst was found to be even more effective.     

Three‐dimensional split‐step‐fourier and finite difference time domain‐based rectangular waveguide filter simulators: Validation,verification, and calibration

The split‐step‐Fourier‐based three‐dimensional wave propagation prediction and finite‐difference time‐domain‐based simulators are developed to show network scattering parameters of rectangular waveguide filters with horizontal and/or vertical windows as capacitive and/or inductive irises, respectively. The three‐dimensional‐split‐step parabolic equation simulator is applied to rectangular waveguide filters, and the results are compared with finite‐difference time‐domain model through tests inside a rectangular waveguide. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:660–667, 2016.     

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in mosses (Hypnum cupressiforme) in Hungary

The atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) was investigated in Hungary by analyzing a moss (Hypnum cupressiforme) species as a bioindicator. In the autumn of 1997, samples were collected at 29 sites distributed across Hungary. The concentrations of total PAH at these sites were in the range of 0.1567-10.45 x 10(4) microg kg(-1) with a mean value of 1.87 x 10(4) microg kg(-1). More than 99% of the total PAHs atmospheric deposition were low molecular weight PAHs (up to 3 ring compounds). The total PAH values showed no correlation with metal concentrations. However, most of the sites in this region showed a positive linear relationship between PAHs levels and traffic volume (r2 = 0.83; P < 0.001) while no relationship existed between PAH levels and population (r2 = 0.01; P > 0.1). Atmospheric deposition of PAHs at different regions in Hungary may be due to incomplete combustion of fuel. The total concentrations of PAHs were compared to the PAH levels in vegetation samples collected from different regions around the world. The highest PAHs concentrations accumulated were found in Hypnum cupressiforme than other vegetation species. A greater affinity for PAH compounds by Hypnum cupressiforme than other moss species probably caused larger amounts of accumulation. A relationship between accumulations of PAH compounds in Hypnum cupressiforme and octanol-air partition coefficients was obtained and is briefly discussed.     

Histomorphometric evaluation of implants coated with enamel or dentine derived fluoride-substituted apatite

Objectives The aim of this study was to compare osseous healing characteristics of titanium implants coated with enamel-derived fluoride-substituted apatite (EFSA) or dentin-derived fluoride-substituted apatite (DFSA). Methods Fluoride-substituted apatite was derived from extracted human teeth with calcination method at 850 °C. DFSA and EFSA were separated and carefully ground with a blade grinder. Twenty-four titanium implants were prepared from a 99.99% pure titanium bar. EFSA and DFSA powders were sprayed separately on implants. As control group, unsprayed and sandblasted pure titanium implants were used. Eight adult rams were used in the study. One EFSA coated, 1 DFSA coated and 1 control implants were placed into right tibia of each rams. The rams were sacrificed after 6 months of healing. Undecalcified sections were prepared according to Donath’s method and histomorphometric evaluation of implants was made. Results The mean bone contact percentage of DFSA-coated, EFSA-coated and control implants was 89.88% ± 2.34, 70.19% ± 13.11 and 53.12% ± 5.76 respectively. This study suggests that DFSA-coated implants achieved better bone contact than EFSA-coated implants (P < 0.05). Also study groups presented better bone contact than control group (P < 0.05). Conclusions The results of this study show that although DFSA-coated implants achieved better bone contact, both DFSA and EFSA can be considered as appropriate coating materials.     

In vitro mutagenic and anti‐mutagenic properties of green synthesised silver nanoparticles

This study is aimed at determining the mutagenic and anti‐mutagenic properties of silver nanoparticles (AgNPs) biosynthesised from Streptomyces griseorubens AU2. To the authors’ knowledge, this is the first study about the investigation of these properties for biogenic AgNPs bacterially synthesised. The mutagenic and anti‐mutagenic potencies were determined by the Ames Salmonella /microsome mutagenicity test using Salmonella typhimurium TA98 and TA100 strains. After determining the cytotoxic dose of green synthesised AgNPs against S. typhimurium TA98 and TA100 strains, subcytotoxic doses (250, 100 and 50 µg/plate) were used in the assays. Biogenic AgNPs at the tested concentrations exhibited no mutagenic effects in the mutagenicity test conducted with the test strains. Moderate anti‐mutagenic effects were observed at high test concentrations. The concentration of 250 µg/plate showed the strongest anti‐mutagenic activity on S. typhimurium TA98. The results did not indicate any mutagenic effect against either of the strains used for screening the mutagenicity of the biogenic AgNPs as they were found to be genotoxically safe. It can be concluded that biogenic AgNPs showed great anti‐mutagenic attributes, standing as a significant factor with respect to medical, pharmaceutical and cosmetic industries.Inspec keywords: biomedical materials, microorganisms, nanomedicine, nanoparticles, silver, toxicologyOther keywords: in vitro mutagenic properties, in vitro antimutagenic properties, green synthesised silver nanoparticles, Streptomyces griseorubens AU2, biogenic silver nanoparticle biosynthesis, microsome mutagenicity test, Salmonella typhimurium TA98 strains, Salmonella typhimurium TA100 strains, subcytotoxic doses, medical industries, pharmaceutical industries, cosmetic industries, Ag     

Magnetic properties and spin-reorientation transition in DyFe10−xNixSi2 compounds

The magnetic properties of DyFe_10−xNi_xSi₂ compounds with x = 0, 1, 2, 3, 4, 6, 9 and 10 have been investigated by means of X-ray diffraction and magnetic measurements. Substitution of Ni for Fe leads to a decrease in the lattice constants a, c and the unit-cell volume V. The Curie temperature reaches a maximum of 590 K at x = 2, then decreases strongly for x ≥ 2. The spin reorientations are observed for the compounds with x = 0, 1, 2 and 3. The spin reorientation temperature decreases strongly from 255 to 60 K as the Ni content is increased from x = 0 to 3. Below the spin reorientation temperature, the compounds exhibit ferrimagnetic ordering. For the Ni-rich compounds with x = 9 and 10, the magnetization of the Dy sublattice decreases strongly since the magnetization of the Dy sublattice is strongly affected by the molecular field produced by the 3d sublattice.