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With industrialization and population growth, solid waste management has become a universal challenge. The destination and incorrect storage of the waste from quarries have become a recurring problem caused by the extraction of mineral resources. The possibility of use for this waste, to minimize its impacts, is the creation of new products that can be useful to engineering using stone powder. Therefore, this study aims to create a new composite using limestone powder with different granulometry to analyze the influence that its insertion and the grain size can cause in these materials. The produced laminates were submitted to uniaxial tensile tests under the norm ASTM D 3039 and volumetric density ASTM D 792, The modifications that occurred in the properties of the specimens were studied in detail, obtaining results that show that the insertion of limestone powder provides the material with new mechanical characteristics, such as the rigidity increase. Among the produced composites, the one that had received limestone as obtained presented the best performance, increasing 9.33% of its elasticity modulus in comparison to the original.

Recentemente tem aumentado o interesse em se estudar a utilização de compósitos poliméricos reforçados com tecidos bidirecionais, sejam à base de fibras sintéticas ou naturais, no setor indústrial. Neste sentido, a compreensão do compormento mecânico e da característica da fratura para esses tipos de compósitos é fundamental, pricipalmente no que diz respeito a uma possível aplicação estrutural. Este trabalho tem como objetivo a idealização de 03 (três) laminados compósitos diferentes: um unicamente reforçado com tecido de fibras de vidro-E (LV), outro do tipo híbrido reforçado com tecido de fibras de vidro-E e fibras de juta (LH), e por fim, um biocompósito, ou seja, um laminado apenas reforçado com tecido de fibras de juta (BJ). Os dois primeiros laminados foram impregnados com resina de poliéster tereftálica, enquanto que o biocompósito foi impregnado com resina de poliéster isoftálica do tipo náutica. Os números de camadas dos laminados foram: 04 (quatro) para os laminados compósitos LV e BJ e 05 (cinco) para o laminado compósito LH. O estudo comportamento mecânico dos laminados foi realizado com base nas propriedades mecânicas de resistência (tensão última) e de rigidez (módulo de elasticidade) e característica final de fratura frente ao carregamento de tração uniaxial. Os resultados mostraram influência direta do tipo de reforço e/ou resina utilizados no que diz respeito às propriedades mecânicas e característica de fratura final.

Objectives. To evaluate the success rate of bone grafts and implants carried out at the Latin American Institute for Research and Dental Education (ILAPEO), considering the following: (i) the different pure bone substitutes (autogenous, xenogeneic, and alloplastic), (ii) the presurgical bone height, and (iii) how the treatment is compromised when membrane perforation occurs during sinus lift in maxillary sinus surgeries. Material and Methods. The initial sample comprised 1040 records of maxillary sinus lifting surgeries. After evaluation, the final sample retained 472 grafts performed using the lateral window technique with a total of 757 implants. The grafts were divided into 3 groups: (i) autogenous bone ( n = 197 ), (ii) xenogenous bovine bone ( n = 182 ), and (iii) alloplastic material ( n = 93 ). One calibrated examiner classified the sample into two groups based on the residual bone height ( p = 0.140 ). Only 8 grafts (1.7%) and 21 implants (2.8%) failed. There was a greater success rate for both grafts (96.5%) and implants (97.4%) when the bone height was ≥4 mm. The success rate in the 49 sinuses in which the membrane was perforated was 97.96% for the grafts and 96.2% for the implants. The follow-up periods after rehabilitation ranged from 3 months to 13 years. Conclusions. Within the limitations of the data analyzed in this retrospective study, maxillary sinus lift was a viable surgical technique that enabled implant placement with a predictable long-term success rate, regardless of the type of material used. The presence of membrane perforation did not interfere with the success rate obtained for grafts and implants.

The synthesis of anatase TiO

In this study, we collected saliva and urine samples from individuals in the metropolitan region of Rio de Janeiro, Brazil, during the years of 2017 through 2019 and we were able to detect the presence of Chikungunya virus genome in these samples. Our findings reinforce the possibility to monitor Chikungunya virus circulation by analyzing saliva and urine from individuals during inter-epidemic periods.

The aim of this study is to determine the influence of hybrid twill fabrics on the conception of polymer composites in terms of their mechanical properties and fracture mechanisms. Parameters associated with the type and/or process of hybridization, such as the presence or not of anisotropy, are influential factors in the final performance of these materials. For this, two composite laminates were manufactured, each containing four layers of reinforced hybrid twill fabrics made from Kevlar-49/AS4 carbon and Kevlar-49/E-glass fibers, with a high-performance epoxy vinyl ester as matrix. Mechanical properties were performed for uniaxial tensile, three-point bending and uniaxial compression tests. The type of hybrid twill fabric directly affected the mechanical properties and damage mechanism of the laminates studied for all loads applied. Highlight that specimens tested to carbon direction exhibited better mechanical behavior.

This work reports the use of cellulose-TiO2 hybrids as photocatalysts for hydrogen production from aqueous ethanol solutions under simulated sunlight. The influence of cellulose loading on hybrids incorporated by impregnation was studied. The cellulose-TiO2 hybrids were characterized by elemental analysis (CHNS), thermo-gravimetric (TGA), N2 adsorption-desorption isotherms (BET), X-ray diffraction (XRD), UV–vis, Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM). The experimental results show that cellulose loading influence on the physico-chemical properties and on photoactivity of cellulose-TiO2 hybrids for H2 production from ethanol solutions. All hybrids show a significant increase in the H2 production rate respect to that achieved on bare TiO2. The H2 production rate over cellulose-TiO2 hybrids depend on the cellulose coverage on TiO2, achieving the better photoactivity the hybrid formed with intermediate cellulose loading.

This work reports the reforming of bio-ethanol on chitosan–TiO2 hybrid photocatalysts at ambient temperature. The influence of chitosan composition on the photocatalytic performance of chitosan–TiO2 hybrid was studied. The hybrids were characterized by CHN elemental analysis, nitrogen adsorption–desorption isotherms, thermogravimetric analysis, diffuse reflectance spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the preparation variables used for the incorporation of chitosan on TiO2 promoted changes in the morphology, superficial area, crystal size and porosity of the photocatalyst, affecting the band gap of this semiconductor and consequently the reactivity of the chitosan–TiO2 hybrids. The catalysts were evaluated for hydrogen production from ethanol under visible light. It was demonstrated that the calcination temperature of 623 K and a chitosan content of 20% were the most appropriate preparation conditions and the resulting product displays a pore size of 1.9 nm, crystal size of 11.3 nm, BET area of 178 m2 g−1 and band gap of 2.92 eV. The calcination temperature of 623 K and incorporation of 20% of chitosan obtained the same results in the conversion rate of hydrogen in comparison to the pure TiO2 P25.

This paper proposes ethyl-ester biodiesel synthesis using calcined chicken eggshell as catalyst, ethyl alcohol and wasted cooking oil in an automatic low-cost production plant, using solar energy as a source of electrical and thermal energy. Eggshells based catalyst were used as source of CaO and samples of ethyl-ester were produced under reaction temperatures 40 °C and 50 °C, at molar ratios 1:6 and 1:9 (oil/alcohol), mass of the catalyst (wt% WCO) of 3% and 5%. The process temperature was monitored and controlled by low cost open-source electronic platform in order to maintain the process temperature stable. The eggshell used as catalyst proved technically feasible, such as the temperature control system, producing ethyl-ester with maximum yield of 84.3%, at 50 °C and 1:9 molar ratio with 5% mass of catalyst.

Introduction The long-term implant-supported prosthetic rehabilitation monitoring is extremely important in evaluating parameters that could interfere in the success of the treatment. Objective To evaluate the influence of macrodesign (shape of the body and apex), length and diameter, insertion torque, site of installation as well as the loading protocol, on long-term survival rates. Material and method The data obtained was from the medical records of rehabilitated patients who had had at least one Morse taper implant surgery done at ILAPEO School between 2006 -2012. Incomplete medical records, from which it would have been impossible to extract all data essential to complete the study, were excluded. Result A total of 1,142 patient’s medical records comprised the sample; documenting the progress of 5,601 implants, done in both jaws and mandibles. The final survival rate was 98.31%, over an average time of 37.54 months. The type of implant most used was cylindrical (70.33%). The mean installation torque most evidenced in the study was between 41 and 50 Ncm. A logistical regression analysis showed that none of the following variables, site of installation, body and apex shape designs and length, had any significant statistical influence on implant loss. Torque increase and diameter influenced implant loss while immediate loading favored implant maintenance. Conclusion It can be concluded that Morse taper implants present a long-term survival rate that can be lowered by excessive torque, as well as by the diameter of the implant. Resumo Introdução O monitoramento a longo-prazo de reabilitações implantossupportadas é extremamente importante para avaliação dos parâmetros que podem interferir no sucesso do tratamento. Objetivo Avaliar a influência do macrodesenho (forma do corpo e ápice), comprimento e diâmetro, torque de inserção, região de instalação, assim como o protocolo de carregamento, na sobrevivência a longo-prazo. Material e método Os dados foram obtidos a partir dos prontuários de pacientes reabilitados com pelo menos um implante cone Morse na Faculdade Ilapeo entre os anos de 2006 e 2012. Prontuários com preenchimento incompleto, que pudesse interferir na coleta de dados foram excluídos da amostra. Resultado Um total de 1142 prontuários compôs a amostra, resultando num total 5601 implantes, instalados tanto em mandíbula como em maxila. A taxa de sobrevivência final foi de 98,31%, em um tempo médio de 37,54 meses. O tipo de implante mais utilizado foi o cilíndrico (70,33%). O torque médio de instalação ficou entre 41 e 50 Ncm. Uma análise de regressão logística mostrou que nenhuma das seguintes variáveis, local de instalação, forma do corpo e ápice e comprimento, teve influência estatisticamente significante na perda de implantes. O aumento do torque e o diâmetro influenciaram a perda do implante e a carga imediata favoreceu a estabilidade. Conclusão Pode ser concluído que implantes cone Morse apresentam índice de sobrevivência elevado que pode ser influenciado por um torque excessivo assim como pelo diâmetro do implante.

In an effort to show the influence of the hybridization method in hybrid fabric reinforced composites within the characteristic of the fracture and the mechanical properties, two laminate reinforced with bi-directional woven were developed, where one of them was reinforced with a hybrid strand (hybrid strand composite laminate) and the other with a different strands (hybrid fabric composite laminate). Both laminates used polyester resin, Kevlar-49 and glass-E fibers, had four layers and were prepared industrially by hand lay-up manufacturing. The percentages by weight of fiberglass and Kevlar in each type of woven are equal. The hybrid strand composite laminate showed a higher tensile strength, however the hybrid fabric composite laminate showed superior properties in three-point bending test, for example, 41.7 % superiority in flexural strength. The results showed that the hybridization method in hybrid reinforced composites influences the mechanical behavior of laminates and the formation and spread of damage.

Rapid maxillary expansion (RME) is the technique of increasing the transverse dimension of the upper jaw using lateral forces applied by palatal expander. Usually, this palatal appliance is anchored on posterior teeth. The purposes of this computer simulation study were to analyze the stress and strain distribution generated in the maxilla, mainly in midpalatal suture (MPS), during RME by tooth-borne and bone-borne expanders and to study the correlation between mechanical strain and Wolff's Law. The analysis was performed with finite element models developed based on Cone Beam computed tomography (CT). To simulate the expansion load, displacements were applied concerning one (0.125 mm) and three (0.375 mm) activations in the medial sides of the tooth-borne expander, and one activation (0.125 mm) for miniscrews (MSIs) in transverse and lateral direction. It was observed that to obtain approximately the same spacing in the MPS activating once the expander with bone support, three activations for the tooth-borne were necessary. However, the strain level caused by bone-borne expansion, when applying a single activation, reached 900 and 5000 μɛ, with peaks up to 20 000 μɛ, in a region very close to the MSIs. Comparing the results, bone-borne appliance anchorage in the palatine bone is more effective than tooth-borne expander. Nevertheless, the stresses and strains increased significantly in the entire jaw when the bone-borne expander is used.