Estudo histomorfométrico da influência do diâmetro do orifício piloto na interface entre o implante e o osso vertebral

OBJETIVO: Estudar as alterações agudas da interface entre os parafusos e o tecido ósseo vertebral, considerando o diâmetro do orifício-piloto em relação ao diâmetro interno do parafuso. MÉTODOS: O estudo foi realizado em carneiros e a segunda vértebra cervical selecionada para o estudo. Foram utilizados parafusos corticais de 3,5mm de diâmetro externo (2,4mm de diâmetro interno) e 14mm de comprimento. Foram formados quatro grupos experimentais: 1) orifício-piloto de 2,0mm e colocação do parafuso de 3,5mm; 2) orifício-piloto de 2,5mm e colocação do parafuso de 2,5mm; 3) orifício-piloto de 2mm sem colocação do parafuso; e 4) orifício-piloto de 2,5mm sem colocação do parafuso. RESULTADOS: O grupo 1 (orifício-piloto menor do que o diâmetro interno do parafuso) apresentou maior densidade óssea no interior da rosca do implante e maior densidade óssea na área em espelho do que o grupo 2 (orifício-piloto maior que o diâmetro interno do parafuso). A superfície de contato entre o tecido ósseo e o implante foi maior no grupo 2 em relação ao grupo 1. A comparação da densidade óssea na área em espelho entre os grupos com e sem implante (1 e 3) e (2 e 4) mostrou que a densidade óssea era maior nos grupos com o implante. Não foi observada diferença estatística entre as comparações dos grupos experimentais. CONCLUSÃO: A utilização de orifício-piloto de menor diâmetro em relação ao diâmetro interno do parafuso apresentou tendência a provocar maior compactação do osso ao redor do implante.

Monitoring in precision metal drilling process using multi-sensors and neural network

This paper presents a new method to estimate hole diameters and surface roughness in precision drilling processes, using coupons taken from a sandwich plate composed of a titanium alloy plate (Ti6Al4V) glued onto an aluminum alloy plate (AA 2024T3). The proposed method uses signals acquired during the cutting process by a multisensor system installed on the machine tool. These signals are mathematically treated and then used as input for an artificial neural network. After training, the neural network system is qualified to estimate the surface roughness and hole diameter based on the signals and cutting process parameters. To evaluate the system, the estimated data were compared with experimental measurements and the errors were calculated. The results proved the efficiency of the proposed method, which yielded very low or even negligible errors of the tolerances used in most industrial drilling processes. This pioneering method opens up a new field of research, showing a promising potential for development and application as an alternative monitoring method for drilling processes. © 2012 Springer-Verlag London Limited.

Estimação do diâmetro e rugosidade em um processo de furação utilizando multi sensores e redes neurais artificiais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo do aumento no diâmetro do corpo de um rebite a ser cravado em furos acima da tolerância de projeto

In this work are discussed the main types of rivets, their characteristics and applicability within the Aeronautical Industry branch. Here are highlighted the solid rivets, showing off its layout, forms and limits of installation, that are required by aviation regulators. The riveting is a popular and simple procedure of fixing and joining two or more parts, and like any other manufacturing process is subject to process deviations that in some situations are beyond the limits of tolerance. One of these deviations is when the hole diameter exceeds the one proposed in project and which is limited by the rule of edge distance. The overall objective here is to study a possible solution to this problem: the installation of a rivet that has his diameter previously increased by compression. Observe the hole filling after riveting, detect the presence of cracks, discover the yield curve of the fasteners and their the crushing limits for failure prediction are tools used to verify this proposal. They demonstrate, at the end of study, the inefficiency of this procedure, with results that go against the safe fixing of parts in a structure

Neural models for predicting hole diameters in drilling processes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Neural models for predicting hole diameters in drilling processes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nose-to-nose transmission of Salmonella Typhimurium between weaned pigs

Little attention has been paid to the possibility of transmission of Salmonella in intensive pig production systems through alternate methods, such as airborne or direct nose-to-nose contact. This experimental study tested the hypothesis of nose-to-nose transmission of Salmonella enterica serovars Typhimurium (Trial I) and Agona (Trial II) in weaned pigs using stainless steel/ glass isolation cabinets. In each trial, cabinet 1 (control pigs) and cabinet 2 (sentinel pigs) were connected directly to the fan unit. Cabinet 3 (seeded pigs) was not directly linked to the fan, but was arranged to receive a constant unidirectional airflow from cabinet 2 (sentinel pigs) through a 10 cm diameter hole, which also allowed nose-to-nose contact between pigs housed in these two cabinets. Air was taken out of the system through ducts connecting cabinets 1 and 3 to the exhauster. Therefore, direct contact among seeded and sentinel pigs was allowed but possible aerial transference of contaminated particles between those cabinets was prevented. The system was opened 21 days post-inoculation and tissue samples were collected for bacteriological analysis. The recovery of nalidixic acid-resistant Salmonella Typhimurium from sentinel pigs corroborates the hypothesis of nose-to-nose transmission of that pathogen in pigs. However, serovar-related differences might exist regarding the nose-to-nose transmissibility of Salmonella in pigs, since Salmonella Agona was not detected in sentinel pigs (Trial II). Published by Elsevier B.V.

Evaluation of the Integrity of Horse Hoof Dermal and Epidermal Tissues Collected by Dorsal Transmural Access

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of nitrous oxide on IOP and pupillary diameter in dogs anesthetized with varying concentrations of desflurane

Objective The aim of the present study was to evaluate the effects of nitrous oxide on TOP and pupillary diameter (PD) of dogs anesthetized with varying desflurane concentrations.Animals studied Twenty adult Mongrel dogs were used.Methods They were anesthetized with propofol (10 mg/kg, IV) and maintained with varying concentrations of desflurane (1.6, 1.4, and 1.2 MAC diluted in 100% oxygen (G1) or in 70% nitrous oxide and 30% oxygen (G2) (30 mL/kg/min). TOP was measured by applanation tonometry and horizontal PD was taken with a caliper adjacent to the cornea. Mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), and end-tidal CO, (etCO(2)) were also measured. All parameters were measured at TO, T30, T45, and T60 time points. One-way repeated measures ANOVA and the t-test were used to assess statistical differences (P < 0.05).Results T30, T45, and T60 TOP measures were Within normal limits for both groups and TOP did not differ between groups at any time. There was a significant decrease in PD in G I between TO and T30, T45 and T60, and also between T30 and T60. PD did not differ between groups. All vital parameters were within normal limits throughout anesthesia.Conclusions Administration of nitrous oxide with desflurane results in maintenance of normal TOP and prevents a decrease in horizontal PD during anesthesia. Therefore, this may be a suitable protocol in dogs undergoing intraocular surgeries that require mydriasis and maintenance of normal TOP.

Effect of diameter of the cotton squares in the development of boll weevil

O objetivo deste trabalho foi estudar o efeito do diâmetro dos botões florais de algodoeiro na massa corporal de adultos do bicudo-do-algodoeiro, Anthonomus grandis Boheman (Coleoptera: Curculionidae). O experimento foi realizado em condições de campo e laboratório, em Jaboticabal (SP), Brasil. Foram realizadas seis amostragens, coletando-se ao acaso dez plantas nas cultivares Coodetec 405 e Fibermax 986, avaliando-se o número e o diâmetro de botões florais. Os botões florais com orifícios de oviposição foram individualizados em frascos e observados diariamente para a visualização da emergência dos adultos. Botões florais com maiores diâmetros proporcionam maior massa corporal de adultos de A. grandis recém-emergidos nas duas cultivares.

Produtividade de melância em diferentes níveis de adubação química e orgânica

The experiment aimed to evaluate the effect of different levels of chemical and organic fertilization on watermelon (Crimson Sweet variety) yield. The experimental design was in randomized blocks, factorial scheme 5 x 4 (5 doses of chemical fertilizer 4-30-16 and 4 levels of organic fertilizer: cattle manure). Four replicates and 10 plants per plot were used. The levels of chemical fertilization tested were: 0, 150, 300, 450 and 600 g per hole. In relation to the organic fertilization 0, 3, 6 and 9 L of cattle manure per hole were used. There was a positive linear correlation among all variables evaluated. Only length and diameter of fruit in the doses 0, 3 and 6 L per hole shows interaction between chemical and organic fertilizers. The highest yield (22.989 kg(-1)) was reached with 450 g per hole of 4-30-16. The watermelon yield increase was limited by nitrogen and phosphorus application when cultivated only with chemical fertilizer and cattle manure, respectively.

The nest architecture of the ant, Pheidole oxyops Forel, 1908 (Hymenoptera : Formicidae)

Pheidole oxyops builds subterranean nests, with an external architecture that is distinctive and easily recognizable by its wide and specific entrance hole, measuring up to 12.2 cm in diameter, denoting a pitfall-trap. In order to study the nests'internal architecture, seven nests were excavated; four were identified with neutral talc, while the others were cast in cement and then excavated. Measurements were made in order to gain a better understanding of their structures, and a photographic documentation was obtained as well. The excavations revealed that the nests are perpendicular relative to the ground, beginning with a cylindrical channel with a mean length of 13.5 cm, containing irregular formations, and whose diameter becomes progressively narrower until the first chamber is formed. As the channel continues, dish-like chambers appear, interconnected by channels that become progressively narrower and longer, while the chambers are arranged at greater distances from each other as nest depth increases. Both channels and chambers are located on the vertical projection of the entrance hole. Nests may reach a depth of up to 5.09 m, with a number of chambers ranging between 4 and 14.

Stem diameter and height of chrysanthemum cv Yokoono as affected by gibberellic acid

The effect of gibberellic acid has been shown mainly to promote cell division and elongation. This study was aimed to evaluate the development of height and diameter of the stems of chrysanthemum cultivar Yoko ono by the applications of gibberellic acid (GA(3)) in the field. The treatments were composed of four doses (0, 40, 80 and 120 mg L(-1)) at 15 and 30 days after transplanting. From the findings, It can be concluded that GA(3) significantly affected the diameter of stem at higher doses, and was unable to affect the height of stem.

Kinetics of interface state-limited hole injection in alpha-naphthylphenylbiphenyl diamine (alpha-NPD) thin layers

Injection-limited operation is identified in thin-film, alpha-NPD-based diodes. A detailed model for the impedance of the injection process is provided which considers the kinetics of filling/releasing of interface states as the key factor behind the injection mechanism. The injection model is able to simultaneously account for the steady-state, current-voltage (J-V) characteristics and impedance response. and is based on the sequential injection of holes mediated by energetically distributed surface states at the metal-organic interface. The model takes into account the vacuum level offset caused by the interface dipole, along with the partial shift of the interface level distribution with bias voltage. This approach connects the low-frequency (similar to 1 Hz) capacitance spectra, which exhibits a transition between positive to negative values, to the change in the occupancy of interface states with voltage. Simulations based on the model allow to derive the density of interface states effectively intervening in the carrier injection (similar to 5 x 10(12) cm(-2)), which exhibit a Gaussian-like distribution. A kinetically determined hole barrier is calculated at levels located similar to 0.4 eV below the contact work function. (C) 2008 Elsevier B.V. All rights reserved.

Photoinduced hole-transfer in semiconducting polymer/low-bandgap cyanine dye blends: evidence for unit charge separation quantum yield

Power-conversion efficiencies of organic heterojunction solar cells can be increased by using semiconducting donor-acceptor materials with complementary absorption spectra extending to the near-infrared region. Here, we used continuous wave fluorescence and absorption, as well as nanosecond transient absorption spectroscopy to study the initial charge transfer step for blends of a donor poly(p-phenylenevinylene) derivative and low-band gap cyanine dyes serving as electron acceptors. Electron transfer is the dominant relaxation process after photoexcitation of the donor. Hole transfer after cyanine photoexcitation occurs with an efficiency close to unity up to dye concentrations of similar to 30 wt%. Cyanines present an efficient self-quenching mechanism of their fluorescence, and for higher dye loadings in the blend, or pure cyanine films, this process effectively reduces the hole transfer. Comparison between dye emission in an inert polystyrene matrix and the donor matrix allowed us to separate the influence of self-quenching and charge transfer mechanisms. Favorable photovoltaic bilayer performance, including high open-circuit voltages of similar to 1 V confirmed the results from optical experiments. The characteristics of solar cells using different dyes also highlighted the need for balanced adjustment of the energy levels and their offsets at the heterojunction when using low-bandgap materials, and accentuated important effects of interface interactions and solid-state packing on charge generation and transport.