Abstract The effect of microwave heating on the expansion of vermiculite was studied at a level of 700 W for 4 min exposure time and compared with raw vermiculite. In this study, the characterization of vermiculite from a mine in the northeast region of Brazil was performed using thermogravimetry, N2-adsorption, cation exchange capacity, X-ray powder diffraction (XRD), infrared (IR) spectroscopy, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy (SEM). Following the microwave heating, the vermiculite was characterized using XRD, IR spectroscopy, and SEM. Microwave irradiation of the vermiculite sample caused structural changes such as loss of crystallinity and disorder, as revealed by the XRD patterns, but did not cause expansion. Results from SEM and IR spectroscopy showed that the microwave heating did not cause profound alterations to the morphology, clay structure, and chemical composition of the vermiculite.

Resumo Este trabalho teve por objetivo a síntese e caracterização do material hidrotalcita-hidroxiapatita (HTHAp) dopado com três diferentes proporções (1, 5 e 15% p/p) de nanotubos de carbono (NTC) a fim de avaliar seu potencial como catalisador heterogêneo na reação de metanólise do óleo de soja. A síntese do material HTHAp foi realizada pelo método de coprecipitação (10≤pH≤11) com homogeneização ultrassônica e tratamento hidrotérmico a 80 °C. DRX, MEV/EDS, FT-IR, Raman, fisissorção de N2 e TG/DTA foram as técnicas de caracterização utilizadas. A amostra HTHAp1NTC, dopada a 1% p/p, foi testada como catalisador em duas condições de temperatura (180 e 240 °C), 4 h de tempo de reação, carga de 2,5% de catalisador e razão álcool:óleo de 12:1. A dopagem contribuiu para melhorar propriedades estruturais, morfológicas e a estabilidade térmica do material. Os resultados de rendimento obtidos de 35,2% (180 °C) e 40,5% (240 °C) qualificam o material HTHAp dopado com NTC como catalisador em potencial na reação de transesterificação.

Abstract The aim of this study was to synthesize and characterize hydrotalcite-hydroxyapatite (HTHAp) material doped with three different proportions (1, 5 and 15% w/w) of carbon nanotubes (NTC) in order to evaluate its potential as a heterogeneous catalyst in the soybean oil methanolysis reaction. The synthesis of the HTHAp material was performed by the co-precipitation method (10≤pH≤ 11) with ultrasonic homogenization and hydrothermal treatment at 80 °C. XRD, SEM/EDS, FT-IR, Raman, N2 physisorption and TG/DTA were the characterization techniques performed. The sample HTHAp1NTC, doped at 1% w/w, was tested as a catalyst under two temperature conditions (180 and 240 °C), 4 h reaction time, 2.5% catalyst loading and alcohol:oil ratio of 12:1. Doping contributed to improve structural, morphological and thermal stability properties of HTHAp material. The yield results achieved 35.2% (180 °C) and 40.5% (240 °C) qualifying the HTHAp material doped with CNT as a potential catalyst in the transesterification reaction.

Pain control is one of the most important aspects contributing that the patient has a positive behavior in the dental office. However, this still constitutes a challenge for the dentist when treating anxious patients, because the administration of local anesthesia is the cause of many patients to avoid dental treatment. With the purpose of reducing pain sensation for patients and promote greater comfort for patients and professionals was developed a computerized anesthesia injection method. The aim of this investigation was to compare the conventional local anesthetic technique with the computer-controlled local anesthetic. Participated in this study 30 volunteers patients who had indication for bilateral surgical extraction of lower third molars. The patients, randomly selected, were subjected to each of the two mentioned anesthetic techniques (conventional and computer-controlled). Although the degree of professional satisfaction with the computer-controlled local anesthetic technique has been significant, the most of them reported to prefer the conventional method. There was no significant hemodynamic changes in any of the two methods used in this study. The computer-controlled local anesthetic technique was simple, effective and safe. The patients enrolled in this study responded better to the computer-controlled local anesthetic technique, reporting less pain.

El control del dolor es uno de los aspectos más importantes para propiciar al paciente un comportamiento positivo en la consulta odontológica. Sin embargo, esto aún constituye un desafío para el cirujano dentista cuando trata pacientes ansiosos, ya que la administración de la anestesia local es lo que determina que muchos pacientes eviten el tratamiento odontológico. Con el propósito de disminuir la sensación dolorosa en pacientes y promover mayor comodidad, los profesionales han desarrollado un método de anestesia computarizada. El objetivo de esta investigación fue comparar la técnica de anestesia local convencional con la técnica de anestesia local controlada por computador. Participaron 30 pacientes voluntarios adultos que tenían indicación para exodoncia de terceros molares inferiores de ambos lados. Los pacientes, elegidos de forma aleatoria, fueron sometidos a las dos técnicas anestésicas mencionadas (convencional y controlada por computador). Aunque el grado de satisfacción de los profesionales con la técnica anestésica controlada por computador fue significativa, la mayoría declaró preferir el método convencional. No hubo cambios hemodinámicos significativos en cualquiera de los dos métodos utilizados en este estudio. La técnica anestésica controlada por computador se mostró sencilla, eficaz y segura. Los pacientes que participaron en este estudio respondieron mejor al método de anestesia controlada por computador, reportando menos dolor.

Pós nanométricos de ferritas de níquel dopadas com cromo foram sintetizados por reação de combustão em forno de microondas. A influência da concentração de Cr3+ nas proporções de x = 0; 0,5 e 1 no sistema NiCr xFe2-xO4 foi investigada. Os pós foram preparados de acordo com o conceito da química dos propelentes e aquecidos em forno microondas com potência 980 W. Os pós sintetizados foram caracterizados por difratometria de raios X, adsorção de nitrogênio (método BET), microscopia eletrônica de varredura, picnometria de hélio e medidas magnéticas. Os resultados mostraram que foi possível obter nanopós de ferritas de níquel dopadas com cromo e que a elevação da concentração de cromo causou um aumento no tamanho de partículas (15 nm para 55 nm) e redução nos parâmetros magnéticos.

Chromium-doped nickel nanoferrite powder was prepared by combustion reaction, using microwave energy as the external heating source, and the influence of the Cr3+concentration on the NiCr xFe2-xO4 system was investigated. The powder, which was prepared according to the concept of propellant chemistry, was heated in a microwave oven under a power of 980 W. The resulting material was characterized by XRD, BET, SEM, helium picnometry and magnetic measurements. The results indicate that it was possible to obtain chromium-doped nickel ferrite nanopowders and that raising the chromium concentration caused an increase in particle size (from 15 nm to 55 nm), and a reduction in the magnetic parameters.