Statistical analysis of teeth autotransplantation in Portugal's region of Chaves.

AIM: The aim of this study was to evaluate the success rate of 33 transplanted teeth in a northern population of Portugal. METHODS: The mean follow-up period was 7 years, ranging from 6 months to 20 years. RESULTS: Six teeth (18%) were rated as unsuccessful, 52% of the donor teeth were transplanted to receptor alveolus after immediate exodontia and 24% were transplanted to receptor alveolus surgically prepared. From the total number of cases, 64% had open root apex at the time of the transplantation and, in the latest control, of all teeth root development was over in 55%. Teeth ankylosis was present in 38% of all cases and 58% of all 33 transplants presented pulpar vitality. Data shows that, in males, teeth transplanted into natural alveolus were non-ankylosed, with normal color and vital teeth with incomplete root development at the time of the surgery. All cumulative curves obtained showed no statistical significance, mainly due to the low number of unsuccessful teeth autotransplantations. Orthodontic treatment performed after tooth autotransplantation showed success in 15% of all cases. CONCLUSION: Data reconfirms that autotransplantation of teeth is, in selected patients, the best option to replace a missing tooth in young patients.

Postcoalescence evolution of growth stress in polycrystalline films.

The growth stress generated once grains coalesce in Volmer-Weber-type thin films is investigated by time-multiscale simulations comprising complementary modules of (i) finite-element modeling to address the interactions between grains happening at atomic vibration time scales (~0.1 ps), (ii) dynamic scaling to account for the surface stress relaxation via morphology changes at surface diffusion time scales (~µs-ms), and (iii) the mesoscopic rate equation approach to simulate the bulk stress relaxation at deposition time scales (~sec-h). On the basis of addressing the main experimental evidence reported so far on the topic dealt with, the simulation results provide key findings concerning the interplay between anisotropic grain interactions at complementary space scales, deposition conditions (such as flux and mobility), and mechanisms of stress accommodation-relaxation, which underlies the origin, nature and spatial distribution, and the flux dependence of the postcoalescence growth stress.

A multi-technique approach to understanding delithiation damage in LiCoO2 thin films.

We report on the delithiation of LiCoO2 thin films using oxalic acid (C2H2O4) with the goal of understanding the structural degradation of an insertion oxide associated with Li chemical extraction. Using a multi-technique approach that includes synchrotron radiation X-ray diffraction, scanning electron microscopy, micro Raman spectroscopy, photoelectron spectroscopy and conductive atomic force microscopy we reveal the balance between selective Li extraction and structural damage. We identify three different delithiation regimes, related to surface processes, bulk delithiation and damage generation. We find that only a fraction of the grains is affected by the delithiation process, which may create local inhomogeneities. However, the bulk delithiation regime is effective to delithiate the LCO film. All experimental evidence collected indicates that the delithiation process in this regime mimics the behavior of LCO upon electrochemical delithiation. We discard the formation of Co oxalate during the chemical extraction process. In conclusion, the chemical route to Li extraction provides additional opportunities to investigate delithiation while avoiding the complications associated with electrolyte breakdown and simplifying in-situ measurements.

Mathematical models applied to the Cr(III) and Cr(VI) breakthrough curves.

Trivalent and hexavalent chromium continuous biosorption was studied using residual brewer Saccharomyces cerevisiae immobilized in volcanic rock. The columns used in the process had a diameter of 4.5 cm and a length of 140 cm, working at an inlet flow rate of 15 mL/min. Breakthrough curves were used to study the yeast biosorption behavior in the process. The saturation time (ts) was 21 and 45 h for Cr(III) and Cr(VI), respectively, and a breakthrough time (tb) of 4 h for Cr(III) and 5 h for Cr(VI). The uptake capacity of the biosorbent for Cr(III) and Cr(VI) were 48 and 60 mg/g, respectively. Two non-diffusional mathematical models with parameters t0 and sigma were used to adjust the experimental data obtained. Microsoft Excel tools were used for the mathematical solution of the two parameters used.

Validation of an HPLC-DAD/UV method for the quantification of cyclamate in tabletop sweeteners: risk of exceeding the acceptable daily intake.

Cyclamate is widely used as intense sweetener in the European Union. The absence of a maximum limit for the use of cyclamate in tabletop sweeteners and the growing demand for this type of product highlights the importance of developing robust analytical methods for the determination of its content to understand if the consumption of tabletop sweeteners can have a negative impact on human health. The present work aimed at the optimisation and validation of an high-performance liquid chromatography (HPLC) analytical method for cyclamate determination in tabletop sweeteners based on the procedure of European Standard EN 12857. The validated method was then applied to the determination of this sweetener in different types of tabletop sweeteners (liquid, powder and tablets). Both standards and samples solutions were submitted to a derivatisation procedure which converted cyclamate to N,N-dichlorocyclohexylamine. The derivatised product was separated and quantified using a reversed-phase column, a mobile phase composed of water (20%) and methanol (80%), isocratic flow of 1 ml min-1, and detection by ultraviolet spectrophotometry at a wavelength of 314 nm. The analytical method was internally validated according to the following validation parameters: working range, linearity, limits of detection and quantification, sensitivity, precision (repeatability and intermediate precision), and uncertainty. This method proved to be specific and selective for the determination of this sweetener, showing repeatability, RSDr ≤ 3%, intermediate precision, RSDR ≤ 3.3%, and recovery rates from 92% to 108% for the different tabletop sweeteners. The method uncertainty was 9.4%. The concentration of cyclamate in the samples varied significantly, from 2.9% to 73.9%, which demonstrated that a possible excessive consumption of one of the analysed sweeteners can lead to exceeding the acceptable daily intake for cyclamate.

Mapping stress in polycrystals with sub-10 nm spatial resolution.

From aircraft to electronic devices, and even in Formula One cars, stress is the main cause of degraded material performance and mechanical failure in applications incorporating thin films and coatings. Over the last two decades, the scientific community has searched for the mechanisms responsible for stress generation in films, with no consensus in sight. The main difficulty is that most current models of stress generation, while atomistic in nature, are based on macroscopic measurements. Here, we demonstrate a novel method for mapping the stress at the surface of polycrystals with sub-10 nm spatial resolution. This method consists of transforming elastic modulus maps measured by atomic force microscopy techniques into stress maps via the local stress-stiffening effect. The validity of this approach is supported by finite element modeling simulations. Our study reveals a strongly heterogeneous distribution of intrinsic stress in polycrystalline Au films, with gradients as high as 100 MPa nm-1 near the grain boundaries. Consequently, our study discloses the limited capacity of macroscopic stress assessments and standard tests to discriminate among models, and the great potential of nanometer-scale stress mapping.

Growth of single-crystalline KNbO3 nanostructures.

This communication reports on the growth of highly uniform KNbO3 nanowires exhibiting a narrow diameter distribution around 60 nm and a length-to-width ratio up to 100. The nanowires were prepared by a hydrothermal route, which enables simple, gram-scale production. A systematic study of the synthesized nanowires in terms of the morphological and chemical characteristics was carried out by varying the temperature-pressure conditions and the composition of the starting mixture. The results indicate that highly uniform single-crystalline nanowires form within a narrow window of the ternary phase diagram of KOH-Nb2O5-H2O.

Growth kinetics of one-dimensional KNbO3 nanostructures by hydrothermal processing routes.

The growth kinetics of one-dimensional single-crystalline KNbO(3) nanostructures (nanowires and nanofingers, the latter understood as defective nanowires) prepared by hydrothermal processing routes has been theoretically studied. A model taking into account the cube-based morphology of the nanostructures, their defects as the KOH proportion in the starting solution increases, and the partial depletion of species in the solution at the kink regions is proposed. Such a model allows the morphological evolution of the nanostructures to be successfully reproduced, shedding light on the origin of their highly anisotropic growth.

Reducing the surface roughness beyond the pulsed-laser-deposition limit.

Here, we outline the theoretical fundamentals of a promising growth kinetics of films from the vapor phase, in which pulsed fluxes are combined with temperature transients to enable short-range surface relaxations (e.g., species rearrangements) and to inhibit long-range relaxations (atomic exchange between species). A group of physical techniques (fully pulsed thermal and/or laser depositions) based on this kinetics is developed that can be used to prepare films with roughnesses even lower than those obtained with pulsed-laser deposition, which is the physical vapor-phase deposition technique that has produced the flattest films reported so far.

Preventing kinetic roughening in physical vapor-phase-deposited films.

The growth kinetics of the mostly used physical vapor-phase deposition techniques -molecular beam epitaxy, sputtering, flash evaporation, and pulsed laser deposition-is investigated by rate equations with the aim of testing their suitability for the preparation of ultraflat ultrathin films. The techniques are studied in regard to the roughness and morphology during early stages of growth. We demonstrate that pulsed laser deposition is the best technique for preparing the flattest films due to two key features [use of (i) a supersaturated pulsed flux of (ii) hyperthermal species] that promote a kinetically limited Ostwald ripening mechanism.

Role of cluster transient mobility in pulsed laser deposition-type growth kinetics.

The ballistic motion of kinetically hyperthermal clusters on corrugated potential energy surfaces is studied by molecular dynamics simulations. Under pulsed laser deposition conditions, such clusters are generated due to the supersaturation flux and nonthermal energies of the incident species, a fraction of which is transferred to the clusters. This energy transfer, together with the flattening of the potential energy surface due to the cluster inner bonds, causes a lengthening of the ballistic paths as the cluster size increases. These results help explain the enhancement of growth kinetics by pulsed laser deposition.

Estenosis de la anastomosis uretero vesical en paciente con neovejiga ileal: tratamiento percutáneo con ureteroplastia y stent de nitinol / Percutaneous treatment with Nitinol stent implant in benign ureteral stenosis (patient with ileal neo-bladder)

Los autores realizan la presentación de un caso de estenosis ureteral distal benigna, en una paciente con cirugía por carcinoma de vejiga, con neovejiga ileal y reimplante ureteral bilateral. La misma fue tratada con éxito mediante la realización primero de una ureteroplastia con balón inflable, decidiéndose en el momento de la intervención, la colocación de un stent de Nitinol, debido a la imposibilidad de lograr una correcta y permanente dilatación del trayecto con la dilatación solamente. El resultado fue óptimo habiendo transcurrido hasta el momento 14 meses del procedimiento, no habiendo requerido otro tratamiento, permaneciendo con permeabilidad de la prótesis

Hallazgos con ecografía Doppler color y tomografía computada helicoidal en tumores renales: relación entre volumen y grado de neovascularización / Renal tumors: correlation of volume with neovascularity by means of color Doppler, US and helical CT

Entre julio de 1997 y agosto de 1998, se analizaron en nuestro Servicio 23 neoplasias renales de distinta histología que fueron estudiadas mediante ecografía convencional, Doppler color, Power Doppler y tomografía computada helicoidal, obteniéndose en todos los casos confirmación antomopatológica. Basándonos en sus características volumétricas, los tumores se clasificaron en tres grupos. A la vez, se utilizó Doppler color como power Doppler para caracterizar el tipo e intensidad de neuvascularización tumoral, para obtener distintos registros espectorales, arteriales y venosos, y para calcular las diferentes velocidades de flujo con sus índices de resistencia. Se realizó TC helicoidal, antes y después de la inyección de contraste yodado endovenoso, con el objeto de establecer una correlación entre el volumen ecográfico y el obtenido por tomografía, así como observar los diferentes tipos de realce vascular tumoral y entablar una relación con los hallazgos obtenidos mediante Doppler color y Power Doppler. Los hallazgos deberán ampliarse a un mayor número de casos pero los resultados iniciales indican una importante correlación entre el volumen tumoral y el grado de vascularización en el examen Doppler color, especialmente en tumores de pequeño volumen, con un predominio del patrón hipovascular de los mismos. También se observó un aporte importante de este último en la caracterización de los tumores renales en relación con su histopatología