Arein Agreement Research Articles

Protective Effect of Natural and Synthetic Anthocyanins against Tert-butyl-hydroperoxide-induced Oxidative Damages in Normal and β-thalassemic Major Human Erythrocytes In Vitro

Background: Even though β-thalassemia major is a genetic blood disorder, the damages endured by erythrocytes are mediated in part by oxidative stress. Antioxidants such as anthocyanins are capable to prevent the pro-oxidant effects induced by reactive oxygen species (ROS). Objective: This study aims to evaluate the in vitro preventive effects of one natural and two synthetic anthocyanins on normal and β-thalassemic erythrocytes on which toxicity has been induced by the free radical generator: tert-butyl-hydroperoxide TBHP. Methods: Erythrocytes isolated from fasting blood samples of healthy and β-thalassemic major individuals were treated either with TBHP alone or with TBHP after being pre-incubated with anthocyanins. Cell viability, reduced glutathione (GSH) and malondialdehyde (MDA) contents were measured after 90 minutes of incubation. In parallel, the antiradical scavenging capacities of the investigated anthocyanins were also estimated by using the 2,2-DiPhenyl-1-PicrylHydrazyl (DPPH•) assay. Results: The results clearly demonstrate that the treatment of erythrocytes with TBHP induces hemolysis along with marked redox state alteration (lipid peroxidation concomitant to GSH depletion) in both normal and β-thalassemia erythrocytes. During the pre-treatment with anthocyanins, erythrocytes become more resistant to oxidative impairments. Cyanin chloride and 6,7,3’,4’- tetrahydroxyflavylium chloride effectively prevent from TBHP-induced: hemolysis, lipid peroxidation and GSH depletion in normal and thalassemic erythrocytes, while 3’4’-dihdroxy-7-methoxyflavylium chloride had a lesser effect on MDA levels with thalassemic erythrocytes. These results are in agreement with those derived from the DPPH• assay. Conclusion: Our study contributes with important insights that tested anthocyanins may exert relevant potential in the alleviation of oxidative stress, especially the one affecting β-thalassemia erythrocytes.

Dynamic Interfacial Tension Behavior of Pure and Binary Surfactant System

Surfactants are very important surface-active agents in implementation of chemical enhanced oil recovery for oil-water interfacial tension and wettability alteration. However, the high adsorption of surfactant on reservoir rock reduces the efficiency of surfactant flooding. Conventionally, inorganic alkali has been introduced to reduce adsorption of surfactant, but alkali will lead to the formation of emulsion, formation damage and scaling. Therefore, lignosulfonate, a sacrificial agent has been introduced as an alternative to inorganic alkali. In this paper, the critical micelle concentration (CMC) and dynamic interfacial tension (IFT) behavior of a pure and binary system of internal olefin sulfonate (IOS) and lignosulfonate (LS) at brine-decane interfaces are determined by using a spinning drop method. The physicochemical properties of pure and binary of IOS and LS system are determined by conductivity and pH measurements. The CMC value of IOS in 3.5 wt% brine salinity is higher compared to LS due to the isomeric branched of IOS which can occupy a larger area per molecules. The dynamic interfacial tension of IOS shows the fast adsorption of surfactant molecules to the brine-decane interfaces. This is indicated by the fast equilibrium interfacial tension reached by IOS. In comparison, the LS pure system shows decreasing behavior of dynamic interfacial tension. The fast adsorption at the interfaces is only reached for higher LS concentrations. The synergy effect between IOS and LS system shows a reduction in the interfacial value with LS optimum concentration of 0.6 wt%. The drop in conductivity and pH values indicated the development of a tightly packed lamellar liquid crystalline structure. These physicochemical properties are in agreement with the dynamic interfacial tension behavior of the IOS and LS system. This study has demonstrated the significant impact of the LS addition in reducing the dynamic interfacial tension of the surfactant system.

Geochronology, Geochemistry and Geodynamics of the Cabo de Gata volcanic zone, Southeastern Spain

New 40Ar/39Ar ages and major and trace element geochemistry ofthe middle-late Miocene Cabo de Gata volcanic complex, southeastSpain, indicate that the volcanic activity of the Cabo de Gata volcaniczone developed over a short period through several pulses of geochemicallyand isotopically different parental magmas. The oldestvolcanic rocks exposed in the Cabo de Gata volcanic zone are theshoshonite and high-K calc-alkaline rocks of Bujo group, which cry -stallised from a parental magma transitional from calc-alkaline toalkaline potassic generated through large degrees of partial melting,and then affected by a minor contribution from metasomatised veinsand a larger one from the surrounding mantle wedge, in comparisonto ultrapotassic melts. Subsequent partial melting of the mantlesource produced typical calc-alkaline parental magmas belonging tothe Rodalquilar and Agua Amarga groups. Sr-Nd-Pb isotope andincompatible trace element distributions of Cabo de Gata rocks arein agreement with a mantle-wedge source affected by a two-foldmetasomatism. The data suggested that mild potassic to sub-alkalinesubduction-related parental magmas (i.e., high-K calc-alkaline andcalc-alkaline) were generated in the Cabo de Gata sector within amantle wedge metasomatised by a fluid-dominated agent. In contrast,the enrichment in K2O of shoshonitic to ultrapotassic magmaswas achieved through recycling of subducted sediments throughmelts that enriched the mantle wedge in K and related elements.Such a scenario can be easily reconciled with a geodynamic settingat the edge of a destructive plate margin with the subducted slabresponsible for the recycling of sediments within the mantle wedge.

Surrogate Climate Change Scenario and Projections with a Regional Climate Model: Impact on the Aridity in South America

The impact of global warming on the aridity in South America (SA) is investigated. For this purpose, the methodology for generating surrogate climate-change scenarios with a RCM is employed. For the present climate (CTRL) the RCM is initialized with and driven by ECMWF/ERA-Interim reanalysis data. Two aridity indices are used: the Budyko and the UNEP indices. The results for the CTR are in agreement with other model studies which indicate future warming; rainfall increases in southeastern South America, Ecuador and Peru and decreases in the central and eastern Amazon. In general the model reproduces the aridity in the continent compared with the observed data for both indices. The distribution of aridity over SA in surrogate climate-change scenario shows an increase of the dryness in the continent. Over Amazonia the aridity increases 23.9% (for the UNEP index) and 3.1% (for the Budyko index), suggesting that portions of the Amazonia forest are replaced by dry land area. The semi-arid zone over northeast Brazil expands westward, attaining the interior of north Brazil. In this region the aridity increases 20% (for the UNEP index) and 0.6% (for the Budyko index) indicating that areas of humid regime may be occupied by areas with dry land regime. The RCM was also integrated driven by the AOGCM ECHAM5/MPI-OM for the reference climate (CTRL2) and under A1B SRES scenario. The results for the present-day climate are similar in CTRL2 and CTRL, and are in agreement with CRU data. The distribution of the aridity for the present climate seems to be better represented in CTRL using both Budyko and UNEP indices. The changes in aridity (future climate minus control) are higher in the run forced by the A1B SRES scenario. Although the UNEP and Budyko indices show potentialities and limitations to represent the aridity distribution over SA, the changes in aridity due to a pseudo-scenario of global warming are higher using the UNEP index.

The flow of colloids and polymers in channels simulated using non-equilibrium moleculardynamics

Here we report the results of non-equilibrium molecular dynamics simulations of the flow ofcolloidal and polymer particles in a thin channel with explicit inclusion of the backgroundfluid. The simulations used atomic channel walls which were thermostated and anexternal field was imposed to produce planar Poiseuille flow at low Reynoldsnumber. Results are presented which show the effect of channel width and flow rateon the velocity profiles. For wide channels at low flow rates these profiles arein agreement with the results of macroscopic fluid dynamics simulations, butdiscrepancies start to appear when the flow rate is increased and/or the channel widthsbecome smaller until finally the profiles are dominated by wall effects such asparticle layering and then macroscopic theory is not even qualitatively correct.Importantly it is observed that colloidal particles tend to migrate to the walls,but the polymer solutions simulated here tend to migrate to the centre of thechannel.

Femtosecond Third-Order Optical Nonlinearity ofAu:Bi2O3 Nanocomposite Films

Ultrafast third-order optical nonlinearities of the as-deposited andannealed Au:Bi2O3 nanocomposite films deposited bymagnetron cosputtering are investigated by using femtosecondtime-resolved optical Kerr effect (OKE) and pump–probe techniques. Thethird-order optical nonlinear susceptibility is estimated to be2.6×10−10 esu and 1.8×10−9 esu at wavelength of800 nm, for the as-deposited and the annealed film, respectively. TheOKE signal of the as-deposited film is nearly temporally symmetricalwith a peak centred at zero delay time, which indicates the dominantcontribution from intraband transition of conduction electrons. For theannealed film, the existence of a decay process in OKE signal impliesthe important contribution of hot electrons. These characteristics arein agreement with the hot electron dynamics observed in pump–probemeasurement.

Microfabrication by localized electrochemical deposition: experimentalinvestigation and theoretical modelling

Adding to the efforts spent to establish localized electrochemical deposition(LECD) as a standard fabrication process; this paper presents an experimentalinvestigation and theoretical modelling of shape formation of high aspect ratiocolumns and lines fabricated by LECD. The proposed model suggests thattransport of depositing ions leading to deposit formation is mainly dominated bymigration forces. The deposition model is verified by numerical simulation whichutilizes electric field calculation by a boundary element method and a progressiveboundary update approach to determine the evolution of deposition profiles.Simulation results are compared against images of copper columns obtained atdifferent formation stages during the deposition process. Both results arein agreement, which demonstrates the potential and capabilities of theproposed model and simulation procedures as an analysis tool to aid incharacterizing the deposition process and resulting structures, as well as theunderstanding of the dynamics and factors influencing object formation in LECD.

Immunohistochemical determination of thioredoxin and glutaredoxin distribution in the human cervix ,and possible relation to cervical ripening

Thioredoxin (Trx) and glutaredoxin (Grx) are dithiol redox enzymes ,catalyzing general thiol-disulfide oxidoreductions apart from being hydrogen donors for ribonucleotide reductase ,an enzyme essentialfor DNA synthesis. In mammals ,isoenzymes of Trx and Grx are found in the cytoplasm (Trx1 and Grx1) or in mitochondria (Trx2 and Grx2). Trx and Grx play a role in cellular defence against oxidative stressand in redox regulation of cellular function.The localization and levels of human Trx1 and human Grx1 have been determined in the human cervix by immunohistochemistry and image analysis. Cervical biopsieswere obtained from five non-pregnant ,five term pregnant and five postpartum women. The levels of both Trx1 and Grx1 were increased in the nuclei (after translocation from the cytoplasm) of stromal cellsin cervices from the term pregnant group as compared to the non-pregnant group ,but the levels in the postpartum group did not differ significantly from those of the other two groups. These results arein agreement with our previous data on the mRNA expression of these two redox enzymes. The increased levels of the redox enzymes in term pregnancy suggest that they can be regulating factors involved inthe process of cervical ripening ,e.g. transcription factors and enzymes. Secreted Trx may participate in removing inhibitors of collagen-degrading metalloproteinases.

The effect of viscous heating on the stability of Taylor–Couette flow

The influence of viscous heating on the stability of Taylor–Couette flow is investigated theoretically. Based on a linear stability analysis it is shown that viscous heating leads to significant destabilization of the Taylor–Couette flow. Specifically, it is shown that in the presence of viscous dissipation the most dangerous disturbances are axisymmetric and that the temporal characteristic of the secondary flow is very sensitive to the thermal boundary conditions. If the temperature difference between the two cylinders is small, the secondary flow is stationary as in the case of isothermal Taylor–Couette flow. However, when the temperature difference between the two cylinders is large, time-dependent secondary states are predicted. These linear stability predictions are in agreement with the experimental observations of White & Muller (2000) in terms of onset conditions as well as the spatiotemporal characteristics of the secondary flow. Nonlinear stability analysis has revealed that over a broad range of operating conditions, the bifurcation to the time-dependent secondary state is subcritical, while stationary states result as a consequence of supercritical bifurcation. Moreover, the supercritically bifurcated stationary state undergoes a secondary bifurcation to a time-dependent flow. Overall, the structure of the time-dependent state predicted by the analysis compares very well with the experimental observations of White & Muller (2000) that correspond to slowly moving vortices parallel to the cylinder axis. The significant destabilization observed in the presence of viscous heating arises as the result of the coupling of the perturbation velocity and the base-state temperature gradient that gives rise to fluctuations in the radial temperature distribution. Due to the thermal sensitivity of the fluid these fluctuations greatly modify the fluid viscosity and reduce the dissipation of disturbances provided by the viscous stress terms in the momentum equation.

Systematics and biogeography of pygmy possums (Burramyidae : Cercartetus)

Mitochondrial DNA sequences from the ND2 gene were used to investigate the systematic relationships within pygmy possums (Cercartetus) at the subspecies and species level. The phylogenetic relationships identified between Cercartetus species using partitioned ND2 sequences are in agreement with published morphological characters. C. caudatus was identified as the basal member of this assemblage, whilst C. nanus and C. concinnus are linked to the exclusion of C. lepidus. Molecular data identifies some inconsistencies in the assignment of subspecies within Cercartetus, suggesting that revision may be warranted.

Fe4+ content and ordering of anion vacancies in partially reducedAFexTi1-xO3-y (A = Ca, Sr; x⩽0.6) perovskites. An57Fe Mössbauer spectroscopy study

CaFexTi1-xO3-y (0.05⩽x⩽0.60) andSrFexTi1-xO3-y (0.20⩽x⩽0.60) perovskites were prepared bysolid state reaction and subjected to different heat treatments in differentatmospheres. Mössbauer spectroscopy of the CaFexTi1-xO3-y coulddetect Fe4+ in all the samples, even in those heated at 1000 °Cin Ar atmosphere for 10 hours. Fe3+ coordinated by six, five and fouranions were also identified and the estimated hyperfine parameters wereconsistent with those previously reported for theCaFexTi1-xO3-x/2 oxides where all the Fe cations were present asFe3+. The Fe4+/Fe3+ ratios estimated from Mössbauer data arein agreement with coulometric titration data. The absence of tetracoordinatedFe3+ in SrFexTi1-xO3-y suggests that in contrast toCaFexTi1-xO3-y no ordering of anion vacancies takes place evenfor x = 0.60 and explains the differences in the Fe concentration dependenceof the electric transport properties of these materials.

MODULATION OF WIND RIPPLES BY LONG SURFACE WAVES VIA THE AIR FLOW: A FEEDBACK MECHANISM

The evolution of a short-wave (SW) spectrum along a long wave (LW) isstudied. The evolution of the SW spectrum variation is treated in therelaxation time approximation. The variation of the SW spectrum is caused bythe LW orbital velocities and by the variation of the wind stress along thesurface of a LW. The latter is due to the distortion of the flow by a LW, andto the variation of the roughness induced by the modulated short waves. Thisintroduces a feedback mechanism: more SWs give rise to a larger roughness,which by increasing the local stress stimulates the growth of more SWs. It isshown that this aerodynamic feedback effect dominates the modulation of theSW spectrum for moderate and strong winds. The feedback mechanism is mosteffective for SWs in the gravity-capillary range, increasing its dominancewith increasing windspeed and decreasing frequency of a LW. The maximum ofthe SW amplitude modulation is situated at the crest of a LW. The results arein agreement with laboratory and field measurements of the short-wavemodulation.

Tenuous Surface Layer on the Moon: Evidence Derived from Radar Observations

By radar backscattering, observations of the moon have been made which show a systematic difference between the backscattering coefficient of waves polarized in, and perpendicular to, the local plane of incidence. The results arein agreement with a model consisting of a tenuous top layer at least 10 centimeters thick, supported by a denser underlying layer.

Some Studies in Inorganic Complexes. XI. Group 2B with 2-Picolylamine and O-Phenylenebisdimethylarsine

The colourless complexes [ZnX2di], [CdX2di], [HgX2di], [Zndi2][ClO4]2, [Cddi2][ClO4]2, [Hgdi2][ClO4]2, [ZnX2pic2], [HgX2pic], [Znpic2][ClO4]2, [Hgpic2][ClO4]2, and [Hgpic2][NO3]2 have been prepared and studied; X being halogen ; di, o-phenylene-bisdimethylarsine ; and pic, the ligand 2 picolylamine. In methanol and nitromethane the perchlorates and nitrate behave as bi-univalent electrolytes, whilst the mercury halide complexes are almost un-ionized. The diarsine complexes of the zinc and cadmium halides are only slightly ionized in nitromethane and appear to be tetrahedral, although they undergo considerable decomposition in methanol. The zinc halide complexes of 2-picolylamine, having a conductance of about half that of a uni-univalent electrolyte in nitromethane, have metal-halogen bonding, although they are not necessarily octahedral. In methanol they ionize to bi-univalent electrolytes. A study of absorption spectra of respective halide complexes has also been made, and the results are in agreement with the conductances.