The role of personality traits in self-rated oral health and preferences for different types of flawed smiles.

Symmetric, aligned and luminous smiles are usually classified as 'beautiful' and aesthetic. However, smile perception is not strictly governed by standardised rules. Personal traits may influence the perception of non-ideal smiles. We aimed to determine the influence of personality traits in self-rated oral health and satisfaction and in the aesthetic preference for different strategically flawed smiles shown in photographs. Smiles with dark teeth, with uneven teeth, with lip asymmetry and dental asymmetry were ordered from 1 to 4 as a function of the degree of beauty by 548 participants, of which 50·7% were females with a mean age of 41·5 ± 17·6 years (range: 16-89 years). Self-assessment and oral satisfaction were recorded on a Likert scale. Personality was measured by means of the Big Five Inventory (extraversion, agreeableness, conscientiousness, neuroticism and openness), and the Life Orientation Test was used to measure optimism and pessimism. Of the four photographs with imperfect smiles, dental asymmetry was the most highly assessed in 63% of the sample, and the worst was lip asymmetry, in 43·7% of the sample. Some personality traits (above all conscientiousness and openness) were significantly correlated with the position assigned to the photographs with dental and lip asymmetry or with misaligned teeth. The extraversion, agreeableness and openness traits were correlated with the self-perceptions of oral health and aesthetics of the participants. Dental asymmetry seems to be better tolerated than lip asymmetry. Personality traits are weakly but significantly correlated with the aesthetic preference and oral health values, conscientiousness and openness being the most relevant domains in this sense.

Contributions of dental colour to the physical attractiveness stereotype.

Dental appearance may play a key role on the way we develop a first impression of another person. To test whether relatively minor changes in the lightness of tooth colour would influence the perceived social appeal (social, intellectual, psychological and relational abilities) of an unknown male and unknown female, this cross-sectional study was performed on 555 Spanish adults. The two major independent variables related to the photograph were tooth lightness (computer-derived), divided into three levels that included lightened teeth, natural teeth and darkened teeth, and the gender of the observed face. Moreover, six independent variables related to the observer were assessed (age, gender, educational level, place of residence, frequency of brushing and self-reported health status). The dependent variables were scored on five-point Likert scales designed to quantify four domains (social, intellectual, psychological and relationship competences) of the Social Appeal Scale (SAS). Tooth lightness influences the perception of social appeal in all dimensions, as darkened smiles received significantly poorer scores than natural-colour smiles, but these were also worse than lightened smiles. A logistic regression analysis revealed that the major predictor of social appeal was tooth lightness, and for each increment in lightness (from darkened to lightened smiles), the odds ratio (OR) of positive values being perceived increased significantly in all items (from 2·3 in Popularity to 6·9 in Happiness). A perceptible change in dental lightness is the strongest factor associated with the dental attractiveness stereotype, affecting significantly the 12 traits assessed, but mainly the Happiness, Social Relations and Academic Performance.

Magnetic carbon Fe3O4 nanocomposites synthesized via Magnetic Induction Heating.

Magnetic Induction Heating (MIH) of magnetite nanoparticles is employed as a novel synthesis procedure of carbon based magnetic nanocomposites. Magnetic nanoparticles (Fe3O4) and fructose (1:2 weight ratio) were mechanically mixed and submitted to a RF magnetic field (305 kHz). The heat generated by the nanoparticles leads to the decomposition of the sugar and to the formation of an amorphous carbon matrix. Two sets of nanoparticles, with mean diameter sizes of 20 and 100 nm, are comparatively analysed. Structural (X-ray diffraction, Raman spectroscopy, Transmission Electron Microscopy (TEM)), electrical and magnetic (resistivity, SQUID magnetometry) characterizations confirm the nanoparticle carbon coating through the MIH procedure. The percentage of the carbonaceous fraction is suitably increased controlling the magnetic heating capacity of the magnetic nanoparticles. The procedure enables the synthesis of multifunctional nanocomposites with optimized properties to be applied in different technological fields. Particularly, Cr (VI) removal from aqueous media is presented employing the carbon nanocomposite with 20 nm Fe3O4 nanoparticles.

Ni doped Fe3O4 magnetic nanoparticles.

In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure.

Temperature and time dependent magnetic phenomena in a nearly stoichiometric Ni(2)MnGa alloy.

In this work, the temperature and time dependence of the magnetic properties of a polycrystalline Ni(49.7)Mn(24.1)Ga(26.2) alloy is analysed. The law of approach to magnetic saturation has been employed to estimate the magnetic anisotropy in the three structural phases of the alloy (martensitic, pre-martensitic and austenitic). The temperature dependences of magnetic parameters, such as the magnetic susceptibility and coercive field, are interpreted in terms of the changes in the magnetic anisotropy taking place with the structural transformations. The strong magnetocrystalline anisotropy is confirmed to mainly control the magnetic response of the low temperature martensitic phase. Furthermore, magnetic relaxation studies (magnetic after-effect) have been employed to analyse the main differences between the magnetization processes in the three characteristic structural phases. The time decay of the magnetization displays a distinctive response in the pre-martensitic state. The results (logarithmic time decay of the remanent magnetization and field dependence of the magnetic viscosity) indicate the thermally activated nature of the relaxation process.

Magnetic properties of nickel and cobalt catalysts supported on nanoporous oxides.

The aim of this work is to use magnetic measurements as a research tool in the study of possible metal-support interactions in nickel and cobalt nanoporous catalysts. Several physicochemical techniques, namely nitrogen adsorption, X-ray diffraction, temperature-programmed reduction and chemical analysis, were used to analyze the role of the preparation method and the nature of the support on the existence of such metal-support interactions and to relate them with the magnetic response of these nanoporous systems. The catalysts were prepared by incipient wetness impregnation and precipitation-deposition with two commercial oxides, gamma-Al2O3 and SiO2, as supports. The magnetic behavior of the catalysts is drastically affected by the existence of interactions between the metal and the support during the preparation procedure. The samples with weak metal-support interactions have characteristic magnetic behavior of antiferromagnetic metal oxide nanoparticles, while the ones having strong interactions display spin-glass like behavior.

Personality traits and dental anxiety in self-reported bruxism. A cross-sectional study.

OBJECTIVES: The aim of this study was to investigate the association between psychological factors (Personality and Dental anxiety) with self-reported bruxism-related symptoms. METHODS: 526 subjects, over 18 years old and not seeking dental treatment, were recruited from the families and acquaintances of dental students from the University of Salamanca. Bruxism activity was estimated by means of a six-item questionnaire aimed at recording common bruxism-related symptoms and clenching/grinding awareness. The Spanish version of the modified dental anxiety scale (MDAS) was used to determine the level of anxiety perceived in 5 typical scenarios of dental assistance. The NEO-FFI inventory was applied to assess personality profiles associated with 5 different factors (neuroticism, extroversion, openness, agreeableness, and conscientiousness). Pearson correlations, Student T-tests, and logistic regression modelling were used for the statistical analyses. RESULTS: Thirty-five point nine percent of this adults sample was classified as being bruxers, where sleep bruxers comprised more than half of the sample at 20.2%. Bruxers tended to perceive more anxiety in all of the situations included within the MDAS, where they exhibited a higher level of phobia towards the teeth scaling and local anaesthetic injection. The risk of being considered a bruxer is reduced with age (OR: 0.99), and increases proportionally for some personality traits, such as neuroticism (OR: 1.06) and extraversion(OR: 1.04), to the MDAS total score (OR: 1.08) and in smokers (OR: 1.61), after controlling for all potentially confounding factors. CONCLUSIONS: Self-reported bruxism is significantly associated to several personality traits (mainly neuroticism and extraversion) and to the level of dental anxiety (MDAS score). CLINICAL SIGNIFICANCE: Clinicians should be aware of the typical psychological profiles of patients who experience bruxism and the relationship with dental phobias.

Giant direct and inverse magnetocaloric effect linked to the same forward martensitic transformation.

Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic transformation (martensite to austenite). In some of these alloys, the austenite phase can be retained on cooling under high magnetic fields, being the retained phase metastable after field removing. Here, we report a giant direct magnetocaloric effect linked to the anomalous forward martensitic transformation (austenite to martensite) that the retained austenite undergoes on heating. Under moderate fields of 10 kOe, an estimated adiabatic temperature change of 9 K has been obtained, which is (in absolute value) almost twice that obtained in the conventional transformation under higher applied fields. The observation of a different sign on the temperature change associated to the same austenite to martensite transformation depending on whether it occurs on heating (retained) or on cooling is attributed to the predominance of the magnetic or the vibrational entropy terms, respectively.

Effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles.

In this work the effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles obtained by the sol-gel method is analyzed. Two sets of samples were prepared: Fe3O4 nanoparticles and Fe3O4@SiO2 core-shell composites. The samples display the characteristic spinel structure associated with the magnetite Fe3O4 phase, with the majority of grain sizes around 5-10 nm. At room temperature the nanoparticles show the characteristic superparamagnetic behavior with mean blocking temperatures around 160 and 120 K for Fe3O4 and Fe3O4@SiO2, respectively. The main effect of the SiO2 coating is reflected in the temperature dependence of the high field magnetization (µ(0)H = 6 T), i.e. deviations from the Bloch law at low temperatures (T < 20 K). Such deviations, enhanced by the introduction of the SiO2 coating, are associated with the occurrence of surface spin disordered effects. The induction heating effects (magnetic hyperthermia) are analyzed under the application of an AC magnetic field. Maximum specific absorption rate (SAR) values around 1.5 W g(-1) were achieved for the Fe3O4 nanoparticles. A significant decrease (around 26%) is found in the SAR values of the SiO2 coated nanocomposite. The different heating response is analyzed in terms of the decrease of the effective nanoparticle magnetization in the Fe3O4@SiO2 core-shell composites at room temperature.

Temperature dependence of magnetic susceptibility in the vicinity of martensitic transformation in ferromagnetic shape memory alloys.

Temperature dependences of low-field quasistatic magnetic susceptibility in the vicinity of martensitic transitions in an NiFeGa alloy are studied both by experiment and analytically. Pronounced reversible jumps of the magnetic susceptibility were observed near the martensitic transition temperature. A general description of the temperature dependences of the susceptibility in ferromagnetic austenite and martensite phases and the susceptibility jump at the transition is suggested. As a result, the main factors governing the temperature dependences of the magnetic susceptibility in the magnetic shape memory alloys are revealed. The magnetic susceptibility jump value is found to be related to changes of: (i) magnetic anisotropy; (ii) magnetic domain wall geometrical constraints (those determined by the alignment and size of twin variants) and (iii) mean magnetic domain spacing.

Vibrational and magnetic contributions to the entropy change associated with the martensitic transformation of Ni-Fe-Ga ferromagnetic shape memory alloys.

Ferromagnetic shape memory alloys undergo a martensitic transformation accompanied by a change in the magnetic and vibrational properties. However, these property changes are not independent. In this paper, the interplay between magnetic and vibrational properties in the martensitic transformation entropy change has been analyzed for Ni-Fe-Ga ferromagnetic shape memory alloys. The martensitic transformation entropy change has a magnetic and a vibrational contribution, ΔS(p−>m)=ΔS(vib)(p−>m) + ΔS(mag)(p−>m). Using a mean field approximation for the magnetic entropy, the full entropy ΔS(p−>m) has been decomposed and the magnetic contribution ΔS(mag)(p−>m) calculated. Upon removing the magnetic term, the vibrational entropy ΔS(vib)(p−>m) does not change substantially in the composition range where T(M) is below T(C). This latter contribution to the martensitic transformation entropy change has been analyzed using a Debye distribution for the density of states and a proportion of Einstein modes that account for the anomalous phonon mode of the austenite.