RESUMEN
In 1911, the Danish physician Hans Christian Gram (1853-1938) sustained to have found signs of hyperthyroidism in a marble head of a Roman woman that he observed in the Ny Carlsberg Glyptotek in Copenhagen. It could be one of the first examples of a clinical diagnosis of an endocrine disease in an ancient statue.
Asunto(s)
Endocrinología/historia , Hipertiroidismo/diagnóstico , Medicina en las Artes/historia , Escultura/historia , Dinamarca , Endocrinólogos/historia , Femenino , Cabeza/patología , Historia del Siglo XIX , Historia Antigua , Humanos , Hipertiroidismo/historia , Mundo Romano/historia , Ciudad de RomaRESUMEN
Phase transformations at the nanoscale represent a challenging field of research, mainly in the case of nanocrystals (NCs) in a solid host, with size-effects and interactions with the matrix. Here we report the study of the structural evolution of γ-Ga2O3 NCs in alkali-germanosilicate glass - a technologically relevant system for its light emission and UV-to-visible conversion - showing an evolution drastically different from the expected transformation of γ-Ga2O3 into ß-Ga2O3. Differential scanning calorimetry registers an irreversible endothermic process at â¼1300 K, well above the exothermic peak of γ-Ga2O3 nano-crystallization (â¼960 K) and below the melting temperature (â¼1620 K). Transmission electron microscopy and X-ray diffraction data clarify that glass-embedded γ-Ga2O3 NCs transform into LiGa5O8via diffusion-driven kinetics of Li incorporation into NCs. At the endothermic peak, ß-Ga2O3 forms from LiGa5O8 dissociation, following a nucleation-limited kinetics promoted by size-dependent order-disorder change between LiGa5O8 polymorphs. As a result of the changes, modifications of UV-excited NC light emission are registered, with potential interest for applications.
RESUMEN
The objective of this study was to present a systematized review of different methods used to evaluate the masticatory efficiency in conventional complete denture wearers. A survey was conducted in the databases PubMed, Scopus, and Cochrane, seeking scientific articles according to the previously selected terms: "Masticatory performance", "Masticatory efficiency" and "Chewing ability complete denture". Moreover, complementary studies have been carried out with library manual search/databases, which included studies related to different ways to assess masticatory efficiency, specifically as it related to conventional complete denture wearers. Forty three papers were selected to be used in the present review. Despite the wide variety of methodologies in the literature, the sieves method is currently considered the gold standard method to evaluation of conventional complete denture wearers masticatory efficiency, since it is the simplest, does not depend on specific devices (beyond the set of sieves), allows for a rational assessment, and it has been widely reproduced in various types of oral rehabilitation. More, the almond, as natural test food, and the optocal (made from the molding material Optosil), as artificial test food, are the most constantly employed test foods to evaluate masticatory efficiency.
RESUMEN
In this Letter, we show functionalization of NiO-doped 7.5Li(2)O·2.5Na(2)O·20Ga(2)O(3)·35SiO(2)·35GeO(2) glass by space-selective nanocrystallization via exposure to the focused beam of a pulsed copper vapor laser (510.6 and 578.2 nm) at temperature close to the glass transition point (570°C). Irradiated areas drastically change their color, caused by electronic transitions of Ni(2+) dopant ions, without any alteration of the optical quality. Importantly, irradiated regions acquire broadband infrared luminescence (centered at about 1400 nm and possessing 400 nm effective bandwidth) typical of Ni(2+) ions in crystalline environment, and by positive change of refractive index (more than 10(-3)). Spectroscopic and diffractometric data of the irradiated regions indeed resemble those previously observed in thermally nanocrystallized glass, with Ni(2+) ions embedded in γ-Ga(2)O(3) nanocrystals. The results demonstrate the possibility of laser writing nanocrystallized multifunction patterns in germanosilicate glasses for the fabrication of active integrated devices.
RESUMEN
The objective of this study is to compare the effects of canine guidance (CG) and bilateral balanced occlusion (BBO) on denture satisfaction and kinesiographic parameters of complete denture wearers, by means of a cross-over trial. Fifty edentulous patients received new maxillary and mandibular complete dentures. After the intra-oral adjustments and adaptation period, 44 participants were enrolled in the trial and randomly received a sequence of occlusal schemes: BBO followed by CG, or CG followed by BBO. Outcomes were assessed after 30 days of each occlusal scheme. Participants answered a denture satisfaction questionnaire and a kinesiograph instrument recorded mandibular physiologic movements and pattern of maxillary denture movement during chewing. Wilcoxon test and paired sample t-test were used to compare satisfaction levels and kinesiographic data for each occlusal scheme, respectively (α=0.05). The results showed no differences between occlusal schemes on participant's satisfaction and in any of the kinesiographic parameters studied, except for the vertical intrusion of the maxillary complete denture during chewing, which was lower with CG. It can be concluded that the occlusal scheme did not influence on satisfaction and kinesiographic parameters evaluated, as long as volume and resilience of residual edentulous ridges of the participants were normal. Clinical Trial Registration Identifier: NC.T01420536.
Asunto(s)
Oclusión Dental , Dentadura Completa/normas , Boca Edéntula/rehabilitación , Satisfacción del Paciente , Anciano , Estudios Cruzados , Oclusión Dental Balanceada , Femenino , Humanos , Masculino , Mandíbula/fisiología , Maxilar/fisiología , Persona de Mediana EdadRESUMEN
The target of taking advantage of the near-infrared light-emission properties of nickel ions in crystals for the design of novel broadband optical amplifiers requires the identification of suitable nanostructured glasses able to embed Ni-doped nanocrystals and to preserve the workability of a glass. Here we show that Ni doping of Li(2)O-Na(2)O-Ga(2)O(3)-GeO(2)-SiO(2) glass (with composition 7.5:2.5:20:35:35 and melting temperature 1480 °C, sensibly lower than in Ge-free silicates) enables the selective embedding of nickel ions in thermally grown nanocrystals of spinel-like gallium oxide. The analysis of transmission electron microscopy and x-ray diffraction data as a function of Ni-content (from 0.01 to 1 mol%) indicates that Ni ions promote the nanophase crystallization without affecting nanoparticle size (~6 nm) and concentration (~4 × 10(18) cm(-3)). Importantly, as shown by optical absorption spectra, all nickel ions enter into the nanophase, with a number of ions per nanocrystal that depends on the nanocrystal concentration and ranges from 1 to 10(2). Photoluminescence data indicate that fast non-radiative decay processes become relevant only at mean ion-ion distances shorter than 1.4 nm, which enables the incorporation of a few Ni ions per nanoparticle without too large a worsening of the light-emission efficiency. Indeed, at 0.1 mol% nickel, the room temperature quantum yield is 9%, with an effective bandwidth of 320 nm.
RESUMEN
We investigate the effects of erbium doping on SnO(2) nanoclustering in Sn-doped silica. Vibrational spectroscopy data from Raman and infrared absorption measurements show nanostructuring effects on the SnO(2) nanophase. Ultraviolet absorption spectra evidence a gap shift ascribable to size-dependent quantum confinement, also suggesting a role of erbium doping in determining cluster sizes and the amount of localized states on the nanophase boundary. Transmission electron microscopy confirms and details the spectroscopic data. As a result of these measurements, we find that the nanocrystal size distribution becomes narrower, increasing the erbium concentration, while the density of localized states at the nanocrystal surface decreases. The distribution of erbium ions among the possible environments is then examined through simultaneous spectroscopy of luminescence excited by nanocrystal-to-erbium energy transfer and the absorption of nanocrystal luminescence by erbium ions. This analysis shows that erbium behaves as an extrinsic nucleation centre of the SnO(2) nanophase at low doping levels, whereas at high concentrations it modifies the matrix, hindering the growth of SnO(2) crystals and passivating the interface.
RESUMEN
The possibility of obtaining permanent photoinduced refractive index changes, up to -10(-3), in nanostructured silica-based composites has been demonstrated in SiO(2):SnO(2) optical-grade glass ceramics exposed to ultraviolet radiation. Optical and electron paramagnetic resonance data suggest that the negative refractive index change involves a modification at the surface of the SnO2 nanoclusters, leading to a reduction of their crystalline size.