982 resultados para iron Age


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Cognitive health is of central importance for independent and balanced old age, while memory disorders represent the leading cause of intensive and long-term care among the Finnish elderly. The aims of this study were to analyse the effect of height, body mass index, weight change, metabolic conditions and coffee drinking in midlife on cognitive performance in old age among a sample of 2606 Finnish twins aged 65 years or older who had participated in a telephone interview to assess their cognitive status. Since coffee drinking associates with several metabolic conditions and Finns are known to be the greatest consumers of coffee in the world, the heritability and stability of coffee drinking was analysed in the whole Older Finnish Twin Cohort (n=10716). In order to investigate the association between height and cognitive performance in a population with more supportive childhood living conditions, a total of 2161 Danish twins were included in this study. A greater height was found to clearly associate with better cognitive performance in Finnish subjects, but less so among the Danish sample, which may reflect the childhood environmental differences between these cohorts. In the Finnish subjects, there was greater variance in cognitive performance among shorter subjects, and environmental factors were found to play a greater role in their cognitive performance, whereas the cognitive performance of taller participants was mainly explained by genetic factors. Midlife metabolic variables that were found to be significantly associated with a poorer cognitive performance in old age included a higher body mass index and three metabolic conditions: cardiovascular disease, hypertension and, most significantly of all, diabetes. Moreover, both weight gain and loss, even to a lesser degree than suggested previously, were found to be associated with poorer cognition. Furthermore, evidence of a causal relationship between midlife cardiovascular disease and cognitive performance in old age was demonstrated among discordant twin pairs. Conversely, no effect of coffee drinking in midlife on cognitive performance in old age was observed, although coffee drinking was demonstrated to be stable in the study population. The heritability of coffee drinking was found to differ across sexes and age groups, being 51% in men and 52% in women in the whole study population. This study supports the contention that cognitive performance in old age reflects the effects of multiple genetic and environmental exposures, including their complex interactions during the life-span. The demonstrated associations and evidence of a causal pathway between potentially preventable exposures and poorer cognitive performance highlight the importance of preventive medicine.

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Pyridinium poly(hydrogen fluoride) reacts with the oxide of vanadium(V) and chlorides of chromium(III), iron (III) and Co(II) at room temperature forming the pyridinium salts of hexafluoro vanadate(V), hexafluorochromate(III), hexafluoroferrate(III) and hexafluorocobaltate(II) in near quantitative yields (80%). These pyridinium salts are the precursors for the preparation of the alkali metal hexafluorometallates by metathetic reactions in acetonitrile medium with the corresponding metal chlorides. The prepared salts have been identified by their infrared spectral data and elemental analysis.

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Sound recordings and behavioural data were collected from four primate species of two genera (Macaca, Presbytis). Comparative analyses of structural and behavioural aspects of vocal communication revealed a high degree of intrageneric similarity but striking intergeneric differences. In the two macaque species (Macaca silenus, Macaca radiata), males and females shared the major part of the repertoire. In contrast, in the two langurs (Presbytis johnii, Presbytis entellus), many calls were exclusive to adult males. Striking differences between both species groups occurred with respect to age-specific patterns of vocal behaviour. The diversity of vocal behaviour was assessed from the number of different calls used and the proportion of each call in relation to total vocal output for a given age/sex class. In Macaca, diversity decreases with the age of the vocalizer, whereas in Presbytis the age of the vocalizer and the diversity of vocal behaviour are positively correlated. A comparison of the data of the two genera does not suggest any causal relationship between group composition (e.g. multi-male vs. one-male group) and communication system. Within each genus, interspecific differences in vocal behaviour can be explained by differences in social behaviour (e.g. group cohesion, intergroup relation, mating behaviour) and functional disparities. Possible factors responsible for the pronounced intergeneric differences in vocal behaviour between Macaca and Presbytis are discussed.

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A wire-cylinder corona discharge was studied in nitrogen and dry air in crossed electric and magnetic fields for values of magnetic field ranging from 0 to 3000 G with the wire at positive potential. In the absence of a magnetic field pre-onset streamers and pulses were observed in nitrogen. In both nitrogen and dry air breakdown streamers were observed just before spark breakdown of the gap. Furthermore, experiments in dry air at atmospheric pressure in an electric field indicate regular pre-onset streamers appearing at time intervals of 19.5 µs. The appearance of regular pre-onset streamers suggests that it is not possible for negative ions to form a sheath close to the anode as postulated by Hermstein (1960) for the formation of steady or glow corona in a point-plane gap.

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Adult male Nilgiri langurs (Presbytis johnii) utter loud call bouts consisting of one or more phrases. Phrases are made up of several units showing similar or different structural features. The units involved differ with respect to not only their physical structure but also their overall utilization: three vocal patterns are uttered exclusively by mature males living in bisexual groups or all-male bands and, in addition to being part of loud call bouts, are given during encounters with terrestrial predators; two vocal patterns are uttered by males and females, again not just as constituents of loud calls; and one vocal pattern is given exclusively by mature males living in bisexual groups. Within a given bout, phrases differ not only with respect to their composition but also in their temporal organization. In addition to the acoustic components, loud calls are regularly accompanied by stereotyped motoric displays. The motoric and acoustic components of loud call displays appear independently of each other and at different times during ontogeny. The development of the display is characterized by combination of units with different structural features and synchronization of vocal and motoric components. Although more evidence is needed, our observations suggest that the development of loud call displays coincides with the aquisitation of social maturation and competence and requires not only social experience but also a certain amount of motoric training. In spite of the high degree of ritualization, loud call displays are not completely fixed in form, but instead are open to individual- and population-specific variation.

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Open-circuit potential—time transients during the discharge of alkaline porous iron electrodes at various states-of-charge have been studied. From this, it has been possible to arrive at a correlation between the parameters of self-discharge kinetics of the electrode and observed open-circuit potential—recovery time constants. The study provides a method of estimate the state-of-charge of the rechargeable iron electrodes. As a hydrogen evolution reaction inevitably occurs on alkaline iron electrodes, the kinetics of the reaction have also been investigated.

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Hydrazinium metal chlorides, (N2H5)2MCl4·2H2O (where M = Fe, Co, Ni and Cu), have been prepared from the aqueous solutions of the respective metal chlorides and hydrazine hydrochloride (N2H4·HCl or N2H4·2HCl) and investigated by spectral and thermal analyses. The crystal structure of the iron complex has been determined by direct methods and refined by full-matrix least-squares to an R of 0.023 and Rw of 0.031 for 1495 independent reflections. The structure shows ferrous ion in an octahedral environment bonded by two hydrazinium cations, two chloride anions and two water molecules. In the complex cation [Fe(N2H5)2(H2O)2Cl2]2+, the coordinated groups are in trans positions.

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Using dynamic TG in H2, X-ray powder diffraction and Mössbauer Spectroscopy the reactivities fot hydrogen reduction of Fe2O3 prepared at different temperatures, Fe2O3 doped with oxides of Mn, Co, Ni and Cu prepared at 300DaggerC from nitrate precursors and intermediate spinels derived from above samples during reduction have been explored. The reactivity is higher for finely divided Fe2O3 prepared at 250DaggerC. The reduction is retarded by Mn, marginally affected by Co and accelerated by Ni and Cu, especially at higher (5 at.%) dopant concentration. These reactivities confirmed also by isothermal experiments, are ascribed to the nature of disorder in the metastable intermediate spinels and to hydrogen rsquospill overrsquo effects.

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The present study analyses the memories of watching Finnish television in Estonia during the last decades of the Soviet occupation from the late 1960s until the beginning of 1990s. The study stems from a culturalist approach, perceiving television as a relevant aspect in the audiences’ everyday lives. It explores the significance of Finnish television on the society of occupied Estonia from the point of view of its historical audiences. The literature review concentrates on concepts such as the power of television, transnational media, historical audience reception and memory as an object of research. It also explains the concept of spillover, which refers to the unintentional bilateral flow of television signals from one country to another. Despite the numerous efforts of the Soviet authorities to prevent the viewing of the "bourgeois television", there still remained a small gap in the Iron Curtain. The study describes the phenomenon of watching Finnish television in Estonia. It provides understanding about the significance of watching Finnish television in Soviet Estonia through the experiences of its former audience. In addition, it explores what do people remember about watching Finnish television, and why. The empirical data was acquired from peoples’ personal memories through the analysis of private interviews and written responses during the period from February 2010 to February 2011. A total of 85 responses (5 interviews and 83 written responses) were analysed. The research employed the methods of oral history and memory studies. The main theoretical sources of the study include the works of Mati Graf and Heikki Roiko-Jokela, Hagi Šein, Sonia Livingstone, Janet Staiger and Emily Keightley. The study concludes that besides fulfilling the role of an entertainer and an informer, Finnish television enabled its Estonian audiences to gain entry into the imaginary world. Access to this imaginary world was so important, that the viewers engaged in illegal activities and gained special skills, whereby a phenomenon of "television tourism" developed. Most of the memories about Finnish television are vivid and similar. The latter indicates both the reliability and the collectiveness of such memories, which in return give shape to collective identities. Thus, for the Estonian viewers, the experience of watching Finnish television during the Soviet occupation has became part of their identity.

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X-Ray and uv photoelectron spectra of FeO, Fe2O3, and Fe3O4 have been studied along with those of a few model compounds. It has been possible to assign distinct bands due to Fe2+ and Fe3+ in the 3d, 3p, 3s, and 2p bands of Fe3O4. The spectra of Fe3O4 do not show major changes through the Verwey transition.

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The quenching of fluorescence of the free-base tetraphenylporphyrin, H2TPP, and its metal derivatives, MgTPP and ZnTPP by diverse iron(III) complexes, [Fe(CN)6]3−, Fe(acac)3, [Fe(mnt)2]−, Fe(Salen)Cl, [Fe4S4(SPh)4]2−·, FeTPPCl and [Fe(Cp)2]+ has been studied both in homogeneous medium (CH3CN) and micellar media, SDS., CTAB and Triton X-100. The quenching efficiencies are analysed in terms of diffusional encounters and it has been possible to separate static quenching components. The quenching constants are dependent on the nature of the ligating atoms around iron(III) and also on the extent of π-conjugation of the ligands. The quenching mechanism has been investigated using steady-state irradiation experiments. Evidence for oxidative quenching by iron(III) complexes was obtained, though the spin multiplicities of the excited electronic states of iron(III) complexes permit both energy and electron transfer mechanisms for quenching of the singlet excited state of the porphyrins.

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To test the reliability of the radiocarbon method for determining root age, we analyzed fine roots (originating from the years 1985 to 1993) from ingrowth cores with known maximum root age (1 to 6 years old). For this purpose, three Scots pine (Pinus sylvestris L.) stands were selected from boreal forests in Finland. We analyzed root 14C age by the radiocarbon method and compared it with the above-mentioned known maximum fine root age. In general, ages determined by the two methods (root 14C age and ingrowth core root maximum age) were in agreement with each other for roots of small diameter (<0.5mm). By contrast, in most of the samples of fine roots of larger diameter (1.5-2mm), the 14C age of root samples of 1987-89 exceeded the ingrowth core root maximum age by 1-10 years. This shows that these roots had received a large amount of older stored carbon from unknown sources in addition to atmospheric CO2 directly from photosynthesis. We conclude that the 14C signature of fine roots, especially those of larger diameter, may not always be indicative of root age, and that further studies are needed concerning the extent of possible root uptake of older carbon and its residence time in roots. Keywords: fine root age, Pinus sylvestris, radiocarbon, root carbon, ingrowth cores, tree ring

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The chemical potential of oxygen corresponding to the iron-rutile-ilmenite (IRI) and iron-ilmenite-ulvospinel (IIU) equilibria has been measured employing solid-state galvanic cells,$$Pt, Fe + TiO_2 + FeTiO_3 //(Y_2 O_3 ) ZrO_2 //Fe + FeO, Pt$$ and $${\text{Pt, Fe + FeTiO}}_{\text{3}} {\text{ + Fe}}_{\text{2}} {\text{TiO}}_{\text{4}} {\text{//(Y}}_{\text{2}} {\text{0}}_{\text{3}} {\text{) ZrO}}_{\text{2}} {\text{//Fe + FeO, Pt}}$$ in the temperature range of 875 to 1275 K and 900 to 1373 K, respectively. The cells are written such that the right-hand electrodes are positive. The electromotive force (emf) of both the cells was found to be reversible and to vary linearly with temperature over the entire range of measurement. The chemical potential of oxygen for IRI equilibrium is represented by Δμo2(IRI) = -550,724 - 29.445T + 20.374T InT(±210) J mol−1 (875 <-T<- 1184 K) = -620,260 + 369.593T - 27.716T lnT(±210) J mol−1 (1184 <-T<- 1275 K) and that for IIU equilibrium by Δμo2(IIU) = -501,800 - 49.035T + 20.374T lnT(±210) J mol−1 (900 <-T<- 1184 K) = -571,336 + 350.003T− 27.716T lnT(=−210) J mol-1 (1184 <-T<- 1373 K) The standard Gibbs energy changes for IRI and IIU equilibria have been deduced from the measured oxygen potentials. Since ilmenite contains small amounts of Ti³+ ions, a correction for the activity of FeTiO3 has been incorporated by assuming ideal mixing on each cation sublattice in the FeTiO3-Ti2O3 system. Similarly, the ulvospinel contains some Fe³+ ions and a correction for the activity of Fe2TiO4 has been included by modeling the Fe2TiO4-Fe3O4 system. The third-law analysis of the results obtained for IRI equilibrium gives ΔH 298 0 = -575 (±1.0) kJ mol-1 and for IIU equilibrium yields ΔH 298 0 = -523.7 (±0.7) kJ mol−1}. The present results suggest that Fe2+ and Ti4+ cations mix almost ideally on the octahedral site of spinel lattice in Fe2TiO4, giving rise to a configurational contribution of 2R In 2 (11.5256 J mol-1 K-1) to the entropy of Fe2TiO4.