927 resultados para Hetroatomatic rings
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The effects of an in-plane electric field and eccentricity on the electronic spectrum of a GaAs quantum ring in a perpendicular magnetic field are studied. The effective-mass equation is solved by two different methods: an adiabatic approximation and a diagonalization procedure after a conformal mapping. It is shown that the electric field and the eccentricity may suppress the Aharonov-Bohm oscillations of the lower energy levels. Simple expressions for the threshold energy and the number of flat energy bands are found. In the case of a thin and eccentric ring, the intensity of a critical field which compensates the main effects of eccentricity is determined. The energy spectra are found in qualitative agreement with previous experimental and theoretical works on anisotropic rings.
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Oral and facial bone defects can undertake appearance, psychosocial well-being and stomathognatic function of its patients. Over the yerars several strategies for bone defect regeneration have arised to treat these pathologies, among them the use of frozen and irradiated bone allograft. Manipulation of bone grafts it s not determined yet, and several osteotomy alternatives can be observed. The present work evaluated with a microscope the bone fragments obtained from different osteotomy methods and irrigation on rings and blocks allografts irradiated and frozen at 80° negative in a rabbit model. The study is experimental in vitro and it sample was an adult male New Zealand rabbit. The animal was sacrificed to obtain long bones, that were submitted to freezing at 80º negative and irradiated with Cobalt- 60. Then the long bones were sectioned into 24 bone pieces, divided into 4 groups: G1 (n=06) osteotomy was performed with bur No. 6 forming rings with 5 mm thickness with high-speed handpiece with manual irrigation; G2 (n=06) osteotomy was performed with bur No. 6 forming rings with 5 mm thick with surgical motor with a manual irrigation rotation 1500 rpm; GA (n=06), osteotomy with trephine using manual irrigation with saline; and GB (n=06), osteotomy with trephine using saline from peristaltic pumps of surgical motor. Five bone pieces of each group were prepared for analysis on light microscopy (LM) and one on electronic scan electronic microscopy (SEM). On the SEM analysis edges surface, presence of microcracks and Smear Layer were evaluated. Analyzing osteotomy technics on SEM was observed: increased presence of microcracks cutting with high speed; increased presence of areas covered by Smear Layer when cutting with motor implant. The irrigation analysis with SEM was observed: that the presence of microcracks does not depend on the type of irrigation; on manual irrigation, there was greater discrepancy between the cutting lines. The descriptive analysis of the osteotomy and irrigation process on LM showed: histological analysis showing the bony margins with clear tissue changed layer, composed of blackened tissue of charred appearance near to the cortical bone; on the edges of the bony part, bone fragments that were displaced during the bone cut and bone irregularities were observed. After analysis of results we can conclude: that there was greater regularity of the bone cut using high-speed handpiece than using motor implant; the cut with trephine using saline irrigated from peristaltic pumps of surgical motor showed greater homogeneity when compared with manual irrigation; charred tissue was found in all obtained bone samples, whit no significant statistically difference on the proportion of carbonization of the two analysed technics
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The coordination polymer [Cu(Pd(CN)(4))(pn)](n) (pn = 1,3-diaminopropane) has been synthesized and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. The crystal structure showed that three cyano groups of each [Pd(CN)(4)] unit bridge Cu(II) centers leading to the formation of a three-dimensional network. A series of bifurcated hydrogen bonds between the amino groups of the diamine and the nonbridging cyano groups of the cyanometallate result in the organization of suprarnolecular chains and rings along the polymer. (c) 2008 Elsevier B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Polycyclic aromatic hydrocarbons (PAHs) constitute a family of compounds characterized by having two or more condensed aromatic rings and for being a class of substances that are widely distributed in the environment as a complex mixture, being very persistent in the environment due to its low solubility in water. The application of chemometric methods to analytical chemistry has provided excellent results in studying the solubility of PAHs in aqueous media in order to understand the mechanisms involved in environmental contamination. The method consists in analyzing the solubilization of PAHs from diesel oil in water varying parameters such as stirring time, volume of oil added and pH, using a full factorial design of two levels and three factors. PAHs were extracted with n-hexane and analyzed by fluorescence spectroscopy because they have molecular characteristics fluorescent due to the large number of condensed rings and links, and gas chromatography coupled to a mass spectrometer (GC-MS). The results of fluorescence analysis showed that only the stirring time and pH influenced the solubility of PAHs in diesel fuel. How is a non-selective technique for the study of fluorescence was performed on form and semi-quantitative. And for the chromatographic analysis the results showed that the solubility of the different PAHs is influenced differently so that you can classify them into groups by the results of the effects
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The purpose of this study was to evaluate the setting time and the thermal expansion coefficient of 2 endodontic cements, MTA-Angelus and a novel cement called CER. The setting time was determined in accordance to ANSI/ADA specifications no. 57. Three samples of 10 mm diameter and 2 mm thickness were prepared for each cement. The thermal expansion measurements were performed by strain gauge technique. Four samples of each cement were prepared using silicone rings of 5 mm diameter and 2 mm thickness. The data were analyzed statistically using the Student t test. The setting time obtained for the MTA-Angelus and CER cements was 15 (SD 1) min and 7 (SD 1) min, respectively. The linear coefficient of thermal expansion was 8.86 (SD 0.28) mu strain/degrees C for MTA-Angelus and 11.76 (SD 1.20) mu strain/degrees C for CER. The statistical analysis showed significant difference (P < .05) in the setting time and linear coefficient of thermal expansion between the 2 cements. The CER cement has a coefficient of expansion similar to dentin, which could contribute to a decrease of microleakage degree.
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The aim of this study was to clinically and radiographically evaluate acute bone shortening followed by gradual lengthening in the treatment of large segmental tibia defects induced in seven clinically normal dogs. A circular external fixator was assembled with one proximal 5/8-circle ring, one middle ring and one distal ring connected with three rods. Thirty per cent of the tibia and fibula were removed in the middle and distal parts of the diaphyses, between the middle and distal rings. Acute bone shortening with compression of proximal and distal segments was performed. A subperiosteal osteotomy was performed between the half-ring and middle ring. Bone distraction started 7 days after surgery; after lengthening, the apparatus was left in place for 14 weeks for consolidation of regenerated bone. The frame was removed at the end of this period, and the dogs observed for four more weeks. Functional results were considered excellent in two, good in three and fair in the other two dogs. Bone regeneration within the distraction gap was obtained 14 weeks after neutral fixation period. We concluded that acute bone shortening followed by gradual lengthening by Ilizarov method can be used to treat extensive tibial defects in dogs, although it presents limb temporary abnormal limb shape and unequal length as early disadvantages.
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JUSTIFICATIVA E OBJETIVOS: A laqueadura laparoscópica (LL) é um dos procedimentos mais dolorosos e a intensidade da dor varia com a técnica selecionada, sendo mais intensa com a técnica de oclusão das tubas uterinas com anel. As pacientes submetidas à LL referem dor em cólica no período PO e a N-butilescopolamina e a dipirona sódica, por suas propriedades anti-espasmódicas e analgésicas, associadas às propriedades antiinflamatórias do cetoprofeno, podem ser opção para profilaxia e tratamento de dor. O objetivo deste foi estudar a eficácia da N-butilescopolamina e da dipirona sódica associadas ao cetoprofeno, na prevenção de dor PO em pacientes submetidas à LL, com duas técnicas diferentes - diatermia e pinçamento com anel. MÉTODO: Participaram do estudo 50 pacientes, estado físico ASA I e II, com idade entre 23 e 47 anos. As pacientes foram distribuídas aleatoriamente em dois grupos: G1 - oclusão das tubas uterinas com anéis, G2 - oclusão das tubas uterinas com diatermia. Todas as pacientes receberam N-butilescopolamina (20 mg) e dipirona sódica (2500 mg) e cetoprofeno (100 mg), por via venosa, imediatamente antes da indução da anestesia. A dor foi avaliada pelo critério de escala numérica verbal, variando de 0 a 10, sendo 0 ausência de dor e 10 o máximo de dor, a cada 10 minutos na primeira hora, na sala de recuperação pós-anestésica (SRPA) e na 1ª, 2ª, 3ª e 4ª horas após a alta da SRPA. Dor com intensidade maior que 3 era tratada com tramadol (100 mg), por via venosa. A avaliação da dor foi realizada sem que se soubesse a que grupo pertencia a paciente. Para análise estatística, testes t de Student, Mann-Whitney e Friedman. RESULTADOS: Ambos os grupos foram idênticos com relação à idade, ao peso, à altura, à duração da cirurgia e anestesia. As pacientes do G1 apresentaram maior escore de dor que as do G2, em todos os momentos do estudo. Valores estatisticamente significativos: 80% das pacientes de G1 e 16% de G2 necessitaram de tramadol em algum momento do estudo. CONCLUSÕES: A N-butilescopolamina e a dipirona sódica associadas ao cetoprofeno mostraram ser alternativa de analgesia pós-operatória quando a laqueadura é realizada com a técnica de diatermia.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The aims of the present study were to relate intramammary infection (IMI) occurrence and somatic cell count (SCC) with teat-end condition (TEC) and udder cleanliness (UC). Milk samples from 1931 teats were evaluated according to the presence of IMI and SCC. Scores were applied to teats according to the TEC and to UC. Teats ends with a very rough ring had the largest number of IMI when compared to the other three categories, as well as animals with dirtier udders. The change in a TEC score increased by around 30% the chance of IMI. Also, the chance of the animal developing IMI increased by approximately 47% when the UC score increased. No significant association between both scores and quarter SCC was found. It can be concluded that animals with very rough teat end rings and very dirty udders have a greater predisposition to IMI. (C) 2011 Elsevier Ltd. All rights reserved.